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Eco-efficiency of Indian Dyehouses
Final Report
Produced for Defra Sustainable Clothing Roadmap by
Phil Patterson
Colour Connections Textile Consultancy
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Contents
1. Introduction (page 3)
a. Criteria for dyehouse selection
b. Background information
i. Information on the Tirupur regional dyeing industry
ii. Cotton dyeing processes
iii. Basic dyehouse infrastructure
iv. Dyehouse inputs and outputs
2. The Project (page 14)
a. Dyehouse screening summary (page 14)
b. Details of selected dyehouses (page 16)
c. Project Progress (page 16)
i. Dyehouse #1 (page 17)
1. Summary
2. Action Plan
3. Data analysis
4. Reduction of environmental impacts and cost savings
ii. Dyehouse #2 (page 29)
1. Summary
2. Action Plan
3. Data analysis
4. Reduction of environmental impacts and cost savings
iii. Dyehouse #3 (page 37)
1. Summary
2. Action Plan
3. Data analysis
4. Reduction of environmental impacts and cost savings
3. EcoMetrics (page 44)
4. Best practice seminars (page 47)
5. Key best practice emerging from the project (page 49)
6. Summary of project (page 50)
7. Recommendations for future Eco-efficiency projects (page 50)
8. Appendix
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1. Introduction
This demonstration project is part of the Defra co-ordinated Sustainable Clothing Roadmap, voluntary
industry initiative to improve the environmental and ethical performance of clothing across its supply chain http://www.defra.gov.uk/environment/business/products/roadmaps/clothing/index.htm
Because 90% of clothing consumed in the UK is imported, encouraging environmental and ethical
improvements across the international clothing supply chains feeding the UK is essential for improve the
sustainability of clothing we wear in the UK. India is the second largest manufacturer of clothing imported
into the UK. For this reason, demonstration projects have been funded under the Sustainable Development
Dialogues http://www.defra.gov.uk/sustainable/government/international/dialogues/ to support
knowledge sharing and dissemination on key issues between UK /India supply chains. This project focused
on demonstrating the environmental and business case for eco-efficiency in Indian dyehouses supplying the
UK clothing market and was funded by Defra as part of the UK-India Sustainable Development Dialogue.
Dyeing is recognised as being a high impact process that consumes large quantities of water, energy and
chemicals, and the dyeing industry is known to be one of the major global polluters.
The project set out to select three dyehouses of differing ability and to work with them to reduce the
amount of water, energy and chemicals used to dye their products by:-
Improving Quality
Improving Efficiency
Implementing Green Initiatives
The project had two broad aims:-
1. Identify opportunities to improve the performance of the selected dyehouses
2. Develop and disseminate best practice for use by the wider dyeing industry
Criteria for Dyehouse Selection
In order to maximise the time spent with the dyehouses it was decided to select three dyehouses from the
same region of India.
It was also decided to select dyehouses from the same industry sector - to enables easy and reliable
comparisons between the selected dyehouses to be made.
Tirupur was chosen for the project because it has unique and interesting local challenges and, since it is
renowned as a centre for T-shirt production, the selected industry sector was jet dyeing of weft knit cotton.
The project is supported by three UK retailers, Marks and Spencer, Tesco and Next.
Each retailer put forward a shortlist of their preferred suppliers in the region and a total of nine dyehouses
were screened for inclusion in the project.
The original aim was to select one ‘excellent’ dyehouse, one ‘good’ dyehouse and one ‘poor’ dyehouse but
none of the dyehouses suggested by the retailers fell into the ‘poor’ category.
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This was not a major problem but it must be recognised that there are many more poor dyehouses in the
world than good ones, and an opportunity was lost to demonstrate some of the easy, quick wins that can
be achieved with poorer dyehouses.
The three project dyehouses were chosen in consultation with the retailers having first considered the
opportunity to improve and the willingness of the senior technical management to try to improve.
Full details of the initial assessments of the shortlisted dyehouses are provided in the appendix.
Background Information
In order to understand some of the details in this report a basic explanation of cotton dyeing processes and
how a dyehouse works is provided.
Some details of the specific local challenges faced by the Tirupur industry are also provided to enable the
reader to fully understand the differences between this region and the wider dyeing industry.
Information on the Tirupur regional dyeing industry
The Tirupur region has been selected for the project on the basis that it is an area that has been subjected
to a large degree of environmental damage as a result of the high density of cotton dyehouses that have
that have been operating in the area.
Tirupur is a relatively dry area and the rivers are not even sufficiently full to give reasonable dilution to
contaminants in treated dyehouse effluent, let alone the untreated effluent that has been discharged by
significant numbers of dyehouses until the very recent past.
Tirupur is the centre of the weft knit cotton industry (T-shirt type fabrics) and the by-product of typical
cotton dyeing is lots of unfixed dye and lots of salt in effluent.
Normal effluent treatment will remove colour, but not salt - so even the dyehouses who were treating their
effluent to levels that would be accepted throughout most of the world were still adding the environmental
problems by discharging vast amounts of salt.
The past few years have seen a remarkable change in the region and dyehouses have had to clean up their
act.
This change was catalysed by the people of the region who became so concerned about the pollution being
caused by the unregulated dyeing industry that they took their case to the courts and won.
It is therefore the courts who enforced the clean-up programme and they have had huge success to date in
moving the industry forward.
The courts and government are now working in unison to deliver a balanced package of incentives and
punitive measures to keep the economy moving whilst reducing environmental impacts.
Almost all dyehouses in the region now have to be zero discharge factories, or they have to discharge their
effluent to a communal zero discharge effluent treatment plant – under the conditions of their operating
permits they are not allowed to discharge one drop of even fully treated effluent.
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At the start of this project in Spring 2009 there were still mills that discharged partially treated effluent into
the rivers (colour removed but other contaminants remaining) and their hours of operation were severely
restricted but this situation is now coming to a close and all dyehouses have to be zero discharge in 2010.
Despite the closure of over 150 polluting dyehouses in the two years running up to the project, local
experts are still convinced some mills are illegally discharging completely untreated effluent into the rivers.
Several Central Effluent Treatment Plants (CETP’s) were closed down in early 2010 because they had not
met the stringent standards for zero discharge and this caused the temporary closure of even more
dyehouses, including one of the dyehouses selected for the project.
Pollution is a major issue for the global textile industry, and some respects it would have been better to
include a polluting dyehouse in the project as a case study.
However the best practice being employed in the Tirupur area is so good, in many respects it is THE ideal
place, worldwide, to conduct a project with a view to sharing the best practice with the wider industry.
There are still major environmental challenges for the industry and society in the Tirupur region, namely a
scarcity of electricity and a scarcity of water.
Dyehouses do not get electricity for 24 hours a day and have to generate their own using diesel generators
when the supply is cut off - this is inconvenient and much more expensive than electricity from the
government grid.
Improving the efficiency of processing in dyehouses, the major industry of the region, can alleviate a real
societal problem as well as providing better profitability for the dyers.
Cotton Dyeing Processes
Cotton dyeing is generally accepted as having the greatest negative environmental impacts of all dyeing
processes. The most common method for weft knitted cotton (the type used in T-shirt type fabrics) is a
method called jet dyeing and all the dyehouses considered for the project use these machines.
A long length of fabric (up to 1km in the largest machines) is sewn together in a loop and this is propelled
around a machine using pulleys and jets of hot water containing the dyes and chemicals used in the
process. In the schematic diagram of a jet dyeing machine below the fabric is shown in red and the hot
water circulation and jet system is shown in blue. (Manufacturer –Thies GmbH)
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A typical (but not world class) jet dyeing process is outlined below:
Jet dyeing machines use electricity to run the motors, pulleys and pumps and the longer a process takes,
the more electricity is used. Processes normally operate on the principle of sequential filling and draining of
the dye machine and each time the machine is refilled it is referred to as a new ‘bath’. The water in the
machine is heated by steam, so it follows that processes that have more baths and/or hotter baths use
more steam and each bath typically contains between 5 and 10 times as much water as fabric (by weight).
Using less water per kg of fabric means less steam has to be used to heat the water, and the water can be
heated up more quickly thus saving time and electricity. Since most chemicals are used on a g/l basis the
use of fewer litres of water means the use of fewer chemicals – thus reducing effluent loading.
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The class of dye used to produce high quality T-shirt type fabrics are called reactive dyes and these require
large amounts of salt in order to get the dyes to be attracted to the cotton in a dyebath – and then large
amounts of alkali to get the dyes to permanently fix to the fibres.
At the end of the process the dye that is not fixed to the fabric, but is still sitting on the surface, has to be
removed to deliver satisfactory colour fastness but it cannot be removed in the presence of salt – since the
salt actually ‘pushes’ the dye onto the fibres. Therefore a long, water and energy intensive process has to
be employed to remove the salt before the unfixed dye can be removed, and this results in the wash-off
phase typically accounting for over half the time of the total process.
When a dyer is asked to produce fabric of a given colour they will first carry out a dyeing in a laboratory on
a 5 or 10g sample of fabric. Once this colour is approved they will scale up to bulk dyeing. The first time a
bulk dyeing is produced on a particular colour there is a chance it will be wrong – and dyers should measure
their lab to bulk scale up success rate. Once a colour is established in bulk it is easier to guarantee
consistency and the overall right first time figure for their total production, including new and established
colours, is another important quality measure.
Dyeing fabric the wrong colour uses just as much energy, water and chemicals as dyeing it the right colour,
and is a major unnecessary contributor to environmental impacts.
After dyeing the fabric is unloaded from the dyeing machine and excess water is removed by either a
mangle:-
Or a spin dryer.
Finally the fabric is dried on a continuous drying machine called a relax drier. Fabrics typically have between
70% and 100% of their own weight in water after the mangling or spin drying and the lower the amount,
the less energy is required for final drying.
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Some fabrics undergo further processes where chemicals are put on the surface of the fabric but most T-
shirts undergo a fairly simple dye-hydroextract-dry process and all the factories involved in this study use
this method for the majority of their fabrics.
Dyehouse Infrastructure
In order to carry out dyeing and drying processes any dyehouse, anywhere in the world requires:-
Electricity to run the dyeing machine machines, drying machines and effluent treatment plants
o Large blowers, high pressure pumps and Infra Red dryers (for yarns) are the largest
consumers
Steam to heat the water in dyeing machines (produced by an industrial boiler powered by wood,
coal, electricity or gas)
A method of heating drying equipment
o In most factories electrically powered blowers distribute heat produced by burning oil or
gas
o In Tirupur most factories use a thermic flue (where hot oil, heated by a wood fired boilers,
is circulated around machines)
A reliable supply of high quality soft water
o Water is often softened on-site
Compressed air to operate valves on machines
A reliable supply of dyes and chemicals
o Cheap dyes and chemicals save money on dye and chemical bills but are usually a false
economy because they are inconsistent and lead to costly mistakes
A method of treating effluent to comply with local regulations or access to a central effluent
treatment plant
o The exact design depends on local conditions and regulations but the treatment plant has
to remove colour, COD (oxygen depleting substances) and suspended solids.
Effluent treatment is becoming more expensive and many dyers are looking at ways to reduce the amount
of chemicals in effluent - mainly to reduce cost rather than an altruistic environmental move.
Water is primarily used in machines to bleach, dye and wash fabric but it is also used to generate steam and
in cooling systems.
Most dyers try to recycle cooling water and steam condensate to reduce their overall water consumption
(failure to do so can double water usage) and it is becoming more popular to try and use special heat
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exchangers to recycle heat energy that would normally be lost up a chimney or when hot water goes down
a drain.
Inputs and Outputs
Dyehouses can be considered as very simple ‘black box’ model with inputs, activities and output.
The aim of this project was to improve the efficiency of the activities to minimise inputs and negative
outputs
In order to improve the efficiency of a dyehouse it is important that data is collected to measure and
monitor certain key performance indicators.
Improving performance KPI’s has a direct effect on the consumption of the inputs but there are other
initiatives that are largely independent of product quality and factory efficiency that have a significant
effect (such as the purchase of new boilers and heat recovery).
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Input Detail
In many areas of the world the resources are ‘on-tap’, and there is a readily available supply of the water,
power and fuel a dyehouse needs to operate that can be provided without catastrophic local impacts on
the environment.
However in other areas of the world the use of resources by industry is causing severe local environmental
impacts and is also depriving the local population of water and electricity - as was the case in Tirupur until
recently.
The industry in Tirupur has been forced to recognise that there are finite quantities of water, power and
fuel in their region and there are particular restrictions in place.
Water
Industry in the region is largely reliant on water that is piped in by the government from 60 km away.
Abstraction of water from local rivers is not permitted and the use of bore hole water (that can lower the
water table) for industrial use is severely restricted.
Despite many factories being zero discharge, and therefore nominally recycling their water for re-use, there
are losses of approximately 20% of process water (by evaporation) and this has to be purchased from the
government pipeline.
The cost of water varies, with higher prices being charged for dyehouses in a municipal setting than those
in Government industrial zones such as SIPCOT.
SIPCOT (State Industries Promotion Corporation of Tamil Nadu) is based in Perundurai - and is a fully
government owned institution, established to catalyse development of small, medium and large scale
industries in Tamil Nadu. http://www.sipcot.org/ ). It provides infrastructure and some concessions to
dyehouses who re-locate from municipal areas.
Electricity
Electricity is in short supply in this part of India. A rapidly growing population and rapid increase in the
standard of living means that demand outstrips supply, and the region generally works on a system of
rationing.
For prolonged periods of each day the Government electricity supply is turned off and individuals and
industry either go without power or resort to the use of local generation.
Dyehouses typically have diesel powered generators to supplement the government supply and also
capacitors to store electricity to ensure that machines and control systems are never without power.
The consumption of diesel in power generation is not insignificant, and dyehouses report that their own
electricity costs up to 2 or 3 times as much as that provided by the government.
Dyehouses are assessed to see what their capacity and electricity needs are and they are allocated a
percentage of that requirement by the government, with the balance being generated on-site. Throughout
the period of the project this has varied from 10 - 40% being generated on site.
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It is possible to generate renewable electricity in other areas of the country and off-set this but
interestingly this does not mean they get more electricity, but it does mean that they get cheaper
electricity – the only way to make the allocated electricity go further is via dyehouse efficiency measures.
Boiler Fuel
In order to run a dyehouse you need electricity to run machinery and you need to generate steam to heat
the process water.
Steam is generated in a boiler and is transported through pipes to the machines where heat is transferred
to the water in the machine by means of a heat exchanger. (a series of pipes that take heat from the steam
and transfer it to the water without the steam coming into contact with the process bath).
The main factor in deciding what type of fuel is used for the boiler is price.
Gas and oil fired boilers are probably the most efficient in terms of the ease with which the fuel can be
dosed into the boiler to match the steam requirements of the factory, but gas and oil is so expensive in
Tirupur that no-one uses these fuels.
The majority of boilers in the Tirupur region use firewood.
It is difficult to control the output of wood powered boilers - the steam requirement of the dyehouse
(which varies depending on the number of dyeing machines that need heating up at any stage) has to be
approximately matched by the manual addition of wood to the furnace so efficient use of fuel is difficult to
achieve.
Unlike modern gas boilers many of the firewood boilers have little or no insulation, so a significant amount
of the heat generated does not in fact go to producing heat, but is merely lost to the surroundings.
It is apparent that some dyehouses simply feed the furnaces with firewood on a continuous basis
irrespective of steam requirement.
The calorific value of wood is less than that of coal, oil or gas, particularly if there is moisture in the wood,
and some dyehouses report that they find it difficult to heat up process water as quickly as they would like.
Machines still run during slow heating and so consume more electricity than machines that can be heated
quickly.
Wood can be a good fuel since it from a renewable source and all dyehouses report that the wood they use
“comes from Government approved sources”, the inference being that the wood is being sustainably
managed.
Although this project sets out to reduce the amount of resources used to produce dyed fabric rather than
passing judgement on the types of fuel used it is important that the nature of the forestry is examined
more closely as it could be a major factor on whether the regional industry has an overall high or low
impact.
This is especially important because dyehouses are now switching to coal powered boilers because coal
works out cheaper in terms of Rupees/ kg steam.
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Coal is a better fuel in terms of heat output per unit of feedstock but is quite obviously a non-renewable
resource so it would make sense for the economics to be adjusted to make the most sustainable fuel the
most cost effective.
For the wider industry electric boilers are also worthy of consideration, primarily because electricity can be
generated by sustainable energy such as wind power and solar.
However since dyehouses in Tirupur have their electricity rationed they would need to site wind farms on-
site to get a benefit.
The other inputs of dyes, chemicals and fabric will be considered as part of the dyehouse process as they
are inextricably linked.
Dyehouse Outputs
Water Vapour
Approximately 20% of the water lost by evaporation during:-
Dyeing
Drying
Effluent Treatment
Effluent
Dye effluent contains dye, salt, and other chemicals used in processing - these are the major constituents of
Colour, TDS (total dissolved solids) and COD (chemical oxygen demand).
Until recently it was acceptable for dyehouses in Tirupur to remove the colour and dump the salt and
chemical-containing effluent into the river – but no more.
There are a variety of colour removal techniques including flocculation and sedimentation, ozonolysis and
chlorination (the reality is that colour is a minor environmental issue but a massive aesthetic issue – it is the
things that you can’t see that should cause concern).
COD, a measure of the amount of oxygen depletion potential of the chemicals in effluent, can be reduced
by biological treatment plants, where microbes digest the chemicals and break them down into species that
have less potential to rob the rivers of essential oxygen.
However the problem is salt, which is not removed by any standard effluent treatment techniques.
The only way to satisfactorily remove salt from effluent is by reverse osmosis (osmosis is where water
travels across a semi-permeable membrane into a more concentrated solution of salt and reverse osmosis
is the opposite where water is ‘squeezed out’ of a salt solution by forcing it through a semi-permeable
membrane under pressure).
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Reverse osmosis leaves a residue of highly concentrated salt solution from which water is removed using a
highly costly and energy intensive evaporation process - however both the condensed water and recovered
salt can be re-used in the dyehouse.
Dyehouses who treat their own effluent essentially have two build two factories: one to dye the fabric and
one to treat the water. There is a large capital investment, but from then on the costs are manageable, but
still significant, in terms of energy, chemicals and replacement parts.
The major benefit is that 70-80% of their water needs are met by themselves, thus making more water
available for the rest of society.
Dyehouses who send their effluent to a communal effluent treatment plant for processing have to pay
approximately 150 Rupees per m3 for their effluent to be treated and it can be returned to them for
processing (the communal plants also have to be zero discharge).
The one thing that remains to be resolved is sludge – this is the solid residue that remains after treating
effluent and is comprised of one or more of the following: biological sediment from biological treatment
plant, chemical sediment from chemical flocculation and filtration processes, and contaminated salt (that is
the ultimate residue of the reverse osmosis and salt recovery process).
Most dyehouses are currently storing sludge on-site in bunded landfill areas, awaiting news of disposal
recommendations - but the more enlightened ones are developing processes to minimise the creation of
sludge.
Air Emissions
Burning wood, coal and diesel creates CO2 and particulates.
There are mixed reports on the issue of air pollution that requires further investigation. Some mills claim
that there are no requirements with regard to air pollution provided the chimneys are sufficiently high and
other report monthly inspections by the authorities.
Solid Waste
Burning wood produces lots of soot and ash. This is collected and either disposed of or stored.
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2. The Project
Dyehouse Screening Summary
Dyehouses on the retailers’ shortlists were screened in April 2009.
Specific information relating to the individual screened dyehouses are provided in the appendix but there
are some general points worth making with regard to the dyehouses that were been screened.
Each of the retailers who supported the project has standards they expect of their suppliers, and they also
have teams on the ground to assess and monitor factory and product standards.
The shortlisted dyehouses were therefore from the better end of the industry where factories, systems and
products are better than average.
Some of the local garment manufacturers reported that they do deal with dyehouses that are of a much
lower standard than those screened for this project.
At the time of screening the concept of efficiency and quality had already been forced on the dyehouses by
the pollution standards and scarcity of water and electricity.
Some dyehouses had some key measures in place but in general hard facts were difficult to obtain, with
several mills giving estimates that were unlikely to be accurate.
The Process Systems i.e. those to get a batch of fabric through the production process were generally
sound, but the Quality Systems i.e. those that record pass/fail data, problems, timings, efficiency and
resource utilisation were generally in need of improvement.
One of the main reasons for poor quality data is that there was confusion between what was acceptable by
a customer (commercially OK) and what met the technical standards laid out by the customer (technically
OK).
The only way to improve is to aim to meet technical standards and measure performance against those
standards.
Some of the dyehouses that were screened are part of vertical garment organisations and so they are
essentially their own customer – this can lead to acceptance of things by the garment factory that are
subsequently rejected by downstream retail customers and the failure figures are not likely to be recorded
at the dyehouse.
Colour laboratories were generally very well equipped in terms of weighing, dispensing and machine
control.
Colour matching generally seemed to be done visually in most dyehouses, and in order to become world
class dyehouses must use instrumental colour measurement as their main method of pass/fail assessment
for laboratory and bulk dyeings.
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Those that did use instrumental colour measurement had mixed levels of ability and only one of the
dyehouses screened had a conditioning cabinet – a prerequisite for world class colour measurement.
The standard of bulk dye storage, weighing and dispensing was mixed, but generally adequate. Some had
conditioned rooms and check-weigh systems but most operated on a manual basis. Most dyehouses
claimed to be using top quality dyes in order to achieve their quoted right first time figures but examination
of the dye stores often revealed a majority of local, lower quality dyes.
No in-depth checks were done on chemicals as part of the screening process but most did come from the
reputable international suppliers who provide good safety and technical data.
Most dyehouses would like to shorten their dyeing cycles. When the industry is doing well and orders are
good shortened dyeing cycles provide extra production capacity, subject to availability of electricity and
effluent consent levels.
In the dyehouses that were screened, typical dyeing cycle times varied between 8 and 12 hours – the
shorter times being achieved by those with pre-heated hot water and sophisticated machine control.
One aspect which continues to halt progress is the slavish adherence to dye companies’ salt
recommendations for reactive dyeing.
Dye company salt recommendations are robust and far too safe. They were derived decades ago before the
advent of sophisticated dyehouse control systems and concentrations could easily be reduced with no
negative effect on quality.
The majority of water is consumed on washing off of reactive dyes and less salt in the dyebath means less
water is required for washing off - and also cycle times can be reduced. Reduced cycle times mean reduced
electricity consumption (the motors and pumps are running for less time) and reduced salt of course means
lower chemical consumption and lower effluent loading.
Salt in effluent is also an issue with regard to the high cost of running zero discharge facilities so it is
therefore surprising that the majority of screened dyehouses had not looked at this issue in more detail -
particularly those with on-site ETP’s.
There was limited evidence of heat recovery initiatives, either from effluent of from finishing equipment
such as stenters and driers.
Most of the dyehouses evaluated had very little finishing equipment since their products were mainly pure
finish cotton. There is a small amount of stretch fabric produced in the region, that requires more stenter
capacity, but there was very little evidence of performance chemical finishes being applied or even
peaching and sueding.
Several dyehouses reported that they send dyed fabric to other third party factories to finishers, en route
to the customer. This is one of the contributors to the less than perfect quality measurement attitude -
since they don’t carry out the last process before garment making they absolve themselves of some of the
responsibility for quality judgements and monitoring.
Examination departments, absolutely essential as part of a quality improvement process, were almost non-
existent. The garment factories carried out this role for the vertical operations and the customers carried
this out for the commission dyers.
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One dyer in a vertical organisation reported that 2.5% of garment panels were rejected in their garment
factory – a massive cost that could have been highlighted at the dyehouse stage.
The quality of testing Laboratories was mixed. Some had fully equipped, accredited laboratories and other
had very basic QC and rely on customers, garment facilities and third party laboratories to do the checking.
The danger of not having a lab is that the dyehouse can equate a commercial decision (agreeing to take off-
specification merchandise) as an endorsement of a faulty process.
There is a concern that the provision and use of personal protective equipment is almost non-existent, and
one has to be concerned that if safety instructions are ignored then technical instructions may also be
ignored, resulting in unnecessary product failures.
Despite the points raised above the screened dyehouses were very good, with some talented individuals in
place, but they have got potential to improve.
Several dyehouses were processing organic cotton. Although of secondary importance to the project, GOTS
certification is a good indicator that dyehouses understand the concept of controlling restricted substances.
Selected Dyehouses
The following three dyehouses were selected for the project because, although they had some common
areas for improvement, they needed to focus on different aspects to reduce their environmental impacts.
Dyehouse # 1 is part of a vertical group who have good quality and efficiency. They have evaluated
investments in infrastructure and new technology in addition to quality initiatives to further
improve their environmental performance.
Dyehouse # 2 is a busy commission dyer, with reasonably good processes and levels of efficiency.
They have primarily focussed on improvement in right first time performance and hardware
upgrades to reduce environmental impacts.
Dyehouse # 3 is part of a vertical group who reported high levels of quality and right first time. They
primarily needed to optimise their processes and dyehouse planning to reduce environmental
impacts.
Project Progress
The three selected dyehouses were examined in detail in June 2009 using the ICE Compliance dyehouse
auditing methodology to evaluate opportunities for improvement and an action plan was developed for
each one.
The purpose of the detailed evaluation was to:-
1. Establish baseline performance (quality and environmental)
2. Develop recommendations and action plans
a. Free of charge actions
b. Capital investments where pay-back calculations are required
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In an ideal world it is advisable to clearly establish baseline performance before implementing action
plans - in order to accurately quantify the benefits of the actions. However because of the very tight
timescales of the project it was necessary to provide action plans before full baseline data was collected.
Further visits were made in September 2009, January 2010 and March 2010 to check progress with action
plans.
The major challenge of this project has been getting reliable data from the dyehouses with only Dyehouse
#1 providing good quality data from an early stage despite a simple pro-forma being produced for each
dyehouse to collect key pieces of information.
Without wishing to make excuses for the dyehouses that did not provide good data it must be understood
that their number 1 priority throughout the project period has been delivering products to their customers
and this project has been very much secondary to their day to day business.
This is a key lesson from the project that is applicable to all sustainability projects - the major challenge is
to make time and money available to allow managers look at long term improvements rather than
focusing on day to day fire fighting. If time cannot be made available by the managers then it can make
long term sense to employ external project teams to identify and implement improvements.
Dyehouse Reports
Dyehouse #1
Dyehouse #1 is a zero discharge dyehouse situated in the Sipcot development that carry out yarn and fabric
dyeing for their own vertical garment company and also some commission work.
They have reasonable quality machines, good machine control systems and use high quality dyes for the
majority of their production.
They have the capacity to dye 8 tonnes of fabric and 2 tonnes of yarn per day and they have been operating
at close to this capacity for the duration of the project.
The quality performance figures quoted at the start of the project indicated that they had limited scope to
improve and at their major focus was on improving the infrastructure of the factory.
However Dyehouse #1 have provided reliable data since the early stages of the project and this has
highlighted opportunities to improve quality and also some unexpected opportunities to improve
infrastructure.
They have shown an excellent attitude towards improving their factory throughout the project and have
carried out many of the actions on their action plan - to their benefit. The factory manager has voiced his
frustration at not being able to make faster progress due to time and financial constraints and has
expressed a desire to continue working with Colour Connections beyond the completion of the Defra
project.
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The action plan below shows everything that has been worked on but a summary of the key actions they
have taken is as follows:-
Data showed lab to bulk reproducibility to be a bigger problem than they thought. They have
improved laboratory procedures to almost halve the number of failures.
Instead of using look-up tables they now use a graph to determine the amount of salt used in
dyeings resulting in a reduction of approximately 5% of salt.
Data has shown that dyeing cycle times are longer than the programmed times and they are
conducting a detailed review of all batches that over-run to identify the reasons.
They are also going to embark on programme to reduce dyeing cycle times by a minimum of 20%
by:-
o Introducing lower temperature enzyme bleaching (Huntsman Gentle Power Bleach) where
possible. Trials have shown it uses less time and energy and has lower environmental
impacts but the overall cost saving is zero due to high cost of speciality chemicals.
o Removing unnecessary high temperature ‘migration’ dyeing methods for some shades
o Evaluating current wash off methods in detail to remove unnecessary wash baths
o Evaluating new wash off detergent technology (CHT) to reduce time and water
consumption
They have established that savings in boiler fuel from quality and process optimisation initiatives
are largely theoretical because the wood boiler cannot be modulated to match steam production
with steam demand. They are now investing in a more controllable coal fuelled boiler that will pay
for itself in less than one year.
They have calculated that the addition of a third reverse osmosis module to their current water
recycling facility will be cost effective. Adding an RO module will cost money and will require extra
electricity to run it but it will reduce the volume of salt solution sent to the evaporators by 20% and
thus reduce the overall energy consumption for effluent treatment.
Dyehouse #1 are now committed to installing Cold Pad Batch dyeing equipment and are currently
assessing quotes from different suppliers. This will use this as additional (low impact) capacity to
supplement their jet dyeing capacity so there will be an increase in total impacts but an overall
reduction in impacts per unit of production.
At the time of the fourth visit in Jan 2010 Dyehouse #1 reported that they were very busy and were
therefore sub-contracting business to other jet dye dyehouses (because of a move to viscose
dyeing which is less productive - see data analysis). Bringing this in-house to a lower impact method
(CPB) would therefore reduce total impacts.
In the action plan below the right hand column indicates whether the dyehouse needs to make an
investment to carry out the action - more detailed costs are available in the ‘Reduction of environmental
impacts and cost savings’ section.
19
Action Progress £
Basics and Minimum Standards
Ensure all operatives wear appropriate personal protective equipment (gloves, goggles, shoes) at all times, including dyehouse operatives
Ongoing monitoring required
Free
Quality Introduce specific gravity checks to confirm salt levels
Now commenced on difficult shades £
Create standardised continuity cards so that batch to batch variations can be easily compared. Include details of right first time / additions/ top ups and DE read-outs on the continuity cards. (more than one format in use and difficult separate card kept for each batch)
Has been actioned and is operational.
Free
Use instrumental colour measurement in the dyehouse to judge pass/ fail rather than using visual assessment alone. Continue to make commercial decisions but record DE failures as failure to get true figures for shade right first time.
Instrumental colour measurement being used in conjunction with visual assessment
Free
Introduce a standardised procedure for colour measurement - including conditioning for temperature, humidity and light.
Now done
Free
Always use the original master standard when judging colour. Even if a secondary standard has been created (to account for compacting) the use of the original master shade will reduce the chance of drifting away from what the customer specified
Not done. Part of reason is that dyehouse only receives tiny cuttings as master standards that are deemed to be almost useless - better standards are now being received from some customers.
Free
Always measure fabrics in the same way - textured fabrics give different results depending on the angle with which they are presented to a spectrophotometer.
Already actioned. Benefits already being reported in terms of ease of decision making
Free
Conduct failure trend analysis to see if particular shades, dye combinations, machines, operatives are a problem and to analyse if problems are hue or depth problems are the major cause of failure. Most problems are reported as being depth problems - this may be due to 'loose' standardisation (shades need to be darker to account for thinning of shade on compacting - but extra depth is not specified)
Data collection is now enabling this process to take place. Even so more detailed analysis is required. Number of bulk failures is low so small amount of data to work with.
Free
Ensure lab dye pot with the temperature probe has additions made to it - even when being used as a blank pot.
Done
Free
Seek permission from customers to submit one lab dye only for approval
Do not want to jeopardise customer relations. Would rather this was raised a neutral best practice seminar
Free
Process Optimisation
Evaluate salt-at start dyeing techniques (enables s.g. Measurement - but must consider additional volume of liquid introduced with dye and alkali)
Introduced to the majority of new bulk shades
Free
20
Look at using reduced salt levels in all dyeings to a) reduce salt consumption b)improve level dyeing and c)provide an opportunity for reducing wash off processes. Do not alter any running bulk shades without thorough laboratory trials.
Not yet done but trials are planned to coincide with s.g. Checks - salt levels from graphs now coming through into bulk.
£
Create a graph for determining salt requirements rather than traditional dosage based on dye concentration bands. This will reduce salt usage by up to 5%
Done
Free
Evaluate the possibility of re-using the final wash off bath in subsequent dyeings (this contains so little dye as to be insignificant compared to the first post-dye wash off bath and so can be used with little risk)
Not started
£
Evaluate the possibility of re-using the post-bleaching wash off bath for post-dye washing
Not started - water recycling and hot water system will now considered after introduction of CPB
£
Reduce in-bath fabric sampling to one after bleaching and one after dyeing and wash off.
Still convinced that multiple samples add benefit. Data analysis has highlighted that cycle times are longer than initially thought (average of 10 hours 15 mins) so this may now be actioned. Over-running processes are now being analysed in detail to establish causes.
Free
Rigorously monitor process times and the % of time taken in sampling and for decision making - consider moving to blind dyeing for certain shades
Free
Factory Planning
Assess and record the real impact of inefficient colour approval processes on the dyehouse. Explain the benefits of a single numerical colour standard to customers.
Don't want jeopardise relations with customers
Free
Take control of your own QC. Try to stop finishing of a sample of each batch for judgment by customers - finish the whole batch and present data to customer telling them it is on specification.
Don't want jeopardise relations with customers
Free
Remove the time allowed for batches to 'condition' after drying - they will not reach ambient conditions in 24 hours
Done Free
Monitor steam and heat requirement of dyeing and drying equipment
Now decided to move to coal powered boiler to match steam output with steam demand - monitoring was free but new boiler is an investment
Monitor fueling of boilers and whether this can be further optimised to match heat and steam requirements
Hardware / Machinery
Investments
Consider purchase of a conditioning cabinet to improve consistency of colour measurement processes
Being considered
£
Consider purchase of electronic dosing pipettes to improve accuracy of lab processes
Done. Now used to make alkali additions to dyepots instead of inaccurate syringes £
Consider replacing mangle rollers to reduce moisture content of fabrics prior to drying - pay back in less than 12 months
Mangle rollers have been reground to squeeze 3% more moisture out of fabric. New rollers being priced up to deliver greater savings
£
Consider investment in moisture meters for relax drier to prevent over-drying and unnecessary use of energy
Moisture meters installed but need attention £
21
CPB Examine cold pad batch to eliminate use of salt in some dyeing processes and reduce energy requirement of evaporator
Successful trails have been completed and they are committed to installation in 2010 £
Assess machine insulation technology to reduce energy requirements e.g. http://www.nansulate.com/
Not done. Cooling is a bigger problem than heating due to hot water returned from evaporator.
£
New Technology
Assess the Huntsman enzyme 'gentle power bleach' to see if preparation temperatures and costs can be reduced
Trial has been completed - will introduce on appropriate fabrics Free
Assess the use of DyStar alkali clearable disperse dyes for use on cotton/poly blends. A
Will be evaluated when next poly/cotton orders are placed £
Assess the use of Cotoblanc SEL 200 in conjunction with CHT technical team to see if wash off processes can be optimised
Trials to be arranged in April 2010
Free
Infrastructure Conduct cost-benefit analysis of heat recovery from stenter and dryers
Basic figures to be discussed with experts such as Koenig - cost benefit analysis will be required
£
Hot water /Heat recovery from effluent
Project is now planned for 2010 - plans have been drawn up and quotes being assessed
£
Data Analysis
The information is split into three sections: quality performance, process optimisation and resource
utilisation.
In some respects monitoring the performance of a dyehouse is like trying to hit a moving target as their
production volumes and product changes from month to month.
The major factors that can skew results are:-
Total production volume - efficiency is nearly always poorer when production volumes are low.
The balance between coloured and white production. Dyeing whites takes approximately half the
time, energy and water as an average colour.
Fibre type - dyers are trying to move away from commodity products such as simple cotton and are
looking at other fibres such as viscose. In the early stages of product development it is common to
employ long, over-safe dyeing methods to reduce the chance of customer dissatisfaction.
Quality Performance
The quality performance of the dyehouse is generally very good. The data analysis early in the project
highlighted there was an issue with lab to bulk reproducibility and steps have been taken to improve
laboratory processes, resulting in a marked improvement in lab to bulk right first time performance*.
Jun July Aug Sept Oct Nov Dec Jan Feb
Fabric 1st Bulk Batches 20 26 50 48 22 18 62 58 50
Fabric 1st Bulk Batches RFT 13 18 35 28 16 11 46 50 42
22
Fabric Right First Time % 65 69 70 58 73 61 74 86 84
Yarn 1st Bulk Batches 77 79 101 114 107 105 147 151 154
Yarn 1st Bulk Batches RFT 62 58 71 98 96 86 135 120 112
Yarn Right First Time % 81 73 70 86 90 82 92 79 73
Total 1st Bulk Batches 97 105 151 162 129 123 209 209 204
Total 1st Bulk Batches RFT 75 76 106 126 112 97 181 170 154
Total Right First Time % 77 72 70 78 87 79 87 81 75
*The figure for fabric right first time shows a steady improvement but the figures for January and February
2010 have been affected by underlying problems in the bulk dyehouse. The fabric figure remains on an
upward track but it is believed the figures for the yarn dyehouse have been affected by a, yet undiagnosed,
underlying problem in the yarn dyehouse that has affected both bulk to bulk and lab to bulk performance.
When a bulk dyeing is judged to be off-shade the dyer makes an addition of dye to the dyeing to correct the
colour. This correction step (known as a top up) adds on average 5 hours to the process and uses extra
water, energy and chemicals. This process has a lower negative impact than a complete re-dye (where the
fabric undergoes and complete new dyeing process to add the corrective dye) but still has a marked effect -
and a batch may need to be topped up more than once.
The figures for running bulk shades are shown below.
Jun July Aug Sept Oct Nov Dec Jan Feb
Fabric Bulk Batches 127 181 172 163 134 118 145 120 141
Fabric Bulk Batches RFT 116 163 165 151 119 103 129 113 124
Fabric Right First Time % 91 90 96 93 89 87 89 94 88
Yarn Bulk Batches 71 99 97 93 109 184 184 140 131
Yarn Bulk Batches RFT 63 88 88 80 95 171 175 104 99
Yarn Right First Time % 89 89 91 86 87 93 95 74 76
Total Bulk Batches 198 280 269 256 243 302 329 260 272
Total Bulk Batches RFT 179 251 253 231 214 274 304 217 223
Total Right First Time % 90 90 94 90 88 91 92 83 82
The bulk right first time figure was fairly steady at around 90% for both fabric and yarn dye until December
2009 (see later section on January and February 2010). One of the major reasons for the 10% failure rate is
that small sample dyeing machines are being used to dye bulk production.
The sample machines are not as well controlled and it is also difficult to get consistent liquor ratios in these
machines.
Dyehouse #1 are currently analysing the breakdown of failures from bulk and sample machines to
determine whether investment in extra bulk capacity is worthwhile.
90% is good but not world class. In order to get to 95% + they may need new equipment and may also
benefit from a move to blind dyeing for bulk running shades.
23
When a batch is complete the dyer checks the colour and makes an addition of dye if the batch is off-shade
- this checking procedure adds around 20 - 30 minutes to every single batch - even when there is no need
to make a correction.
Blind dyeing (the process where the dyeing is completed, unloaded and then checked) saves time on every
batch but it means the consequences of failure are large because fabric has to be reloaded and re-dyed
using a full process.
Increasing the consequences of failure therefore increases the pressure to get things right first time and
this generally has the result of improving performance.
January - February 2010
The bulk to bulk right first time performance of the yarn dyehouse deteriorated from an average of around
90% for the previous months to approximately 75% in January and February.
This equates to 1.5 failed batches per working day which does not seem like a major problem on a day to
day basis and it is only the data analysis that has highlighted the problem. The causes are now being
examined in detail - the problem appears to have affected both bulk to bulk performance and lab to bulk
performance in the yarn dyehouse but the performance of the fabric dyehouse has been good.
Although not good news at all for Dyehouse #1 it demonstrates the necessity of data collection to highlight
deviations from expected performance.
Process Optimisation
Dyehouse #1 are now recording the length of time for each individual and this shows that the time taken
for dyeing processes is a) longer than the pre-programmed time and b) significantly longer than industry
best practice times.
Jun July Aug Sept Oct Nov Dec Jan Feb
Average Process Time (fabric)* 10.48 10.84 10.08 10.2 10.26 10.75 10.7 10.8 10.7
Average Process Time (yarn)* 10.01 10.12 10.02 10.05 9.94 9.91 10.17 10.3 10.3
*Data analysis has indicated that the figures being recorded in the yarn dyehouse are all too low as they
have not added the time taken for top-ups to the initial process time. This was highlighted by the fact that
recorded average process times did not change significantly even though quality performance dropped
dramatically.
It is also apparent that the time taken for re-dyes is also not added to either yarn or fabric process times -
thus making average times for both fabric and yarn dye lower than they actually are. However the trend of
increasing process times in the fabric dyehouse is real and has enabled action to be taken.
These times are only for dyeing processes so are not affected by the level of white production.
An increase in the amount of viscose fabric being processed from November through to February has had a
negative effect on process times. The plan was to dye a premium product for a better price but the dyeing
machines are not ideal for viscose and therefore long, ultra-safe, methods were employed to avoid
customer dissatisfaction. However the data analysis has shown that cycle times and water and energy
24
consumption have increased dramatically and they are no longer taking orders for viscose until they can
produce them using cold pad batch dyeing.
Viscose should actually be processed in a shorter time than cotton (albeit using more water per bath) if
industry best practice methods are used and they have been advised to enlist the assistance of major dye
companies to advise.
They are now analysing the reasons for over-run vs programmed timings on a batch by batch as well as
looking at ways to fundamentally reduce the length of dyeing programmes.
In addition to average (mean) times Dyehouse #1 are looking at a more in-depth statistical analysis of
process times. For example the graph below for June 09 shows the most common process time is 9 hours
but ‘problem batches’, that take up to 31 hours, take the average up to 10 and a half hours.
In addition to reducing the number of ‘problem batches’ Dyehouse #1 are now also planning to introduce
shorter bleaching, dyeing and wash off methods with the aim of reducing the processing times by 20%. This
will reduce their energy costs and also increase their effective capacity.
Resource Utilisation
Daily Analysis
Full data allows for trend analysis to be conducted and this data has been instrumental in helping Dyehouse
#1 make the decision to move to a more controllable coal powered boiler.
The full data for boiler wood and electricity consumption vs total production volume for one month is
shown below.
The graph has had data from non-production days removed (where the ETP operates but no dyeing is
done).
25
It gives a figure for total electricity consumption (combining government units and generator units using a
conversion factor of 3.5 units per litre of diesel). The low points in the electricity graph are for the days
following a dyehouse shut-down - this is because less electricity is required in the ETP.
However the electricity low points are not always matched by boiler fuel low points and it is apparent that
boiler wood consumption is fairly level compared to the variations in production volume, (indicating lack of
ability to match steam output with dyehouse demand).
To be doubly sure that the boiler isn’t being modulated effectively it is wise to make an adjustment for the
level of white production.
As mentioned previously the amount of energy required to produce whites is about half that to dye an
average colour - the graph below therefore adjusts the production volume by halving the volume of white
per day in order to see if the electricity and boiler fuel consumption tracks total net production volume.
The graph below also adjusts the wood consumption to consider just that used for production in the
dyehouse (the ETP uses a fairly steady 13 tonnes per day)
26
This demonstrates that boiler fuel consumption isn’t well matched to net production volume and is the
basis for a move to a more controllable coal fired boiler.
Monthly Averages
The table below shows the trend of resource utilisation over the period July to December 2009 - the figures
for June are included but are from 6th June to 30th June only (i.e. incomplete)
Jun* July Aug Sept Oct Nov Dec
Tonnes of colour 99 133 128 124 127 112 139
Tonnes of white 84 103 84 113 89 85 100
Total production 183 236 212 237 216 197 239
Total diesel use 21789 20987 24154 25534 28437 28794 31200
Total govt units 166425 238476 210656 211800 196032 201704 212156
Total electricity units 242686 311930 295195 301169 295561 302483 321356
Electricity units / tonne 1326 1321 1392 1270 1368 1535 1344
Total water 2232 3419 3015 2981 3052 3299 2565
Water use l/kg 12.4 14.5 14.2 12.6 14.1 16.7 10.7
Total tonnes boiler fuel 643 832 762 781 747 724 759
Boiler fuel / tonne 3.5 3.5 3.6 3.3 3.5 3.7 3.2
It can be seen that the major factor on the efficiency of Dyehouse # 1 is the volume of business. When
volumes drop the amount of water, energy and boiler fuel used per tonne increases.
Throughout this period of time the dyehouse has operated for 6 days per week and the best way to reduce
impacts when production volume fall is to plan to complete the production in a shorter period of time and
then shut down machines and boilers.
Comparing July with December, where volumes and percentages of white vs coloured production are very
similar, it can be seen that water usage (-25%) and boiler fuel usage (- 10%).
The percentage of white production varied between 40% and 47% over the period and the impacts per
tonne are obviously less for months where white forms a larger proportion of the production.
January - February 2010
Jun July Aug Sept Oct Nov Dec Jan Feb
Tonnes of colour 99 133 128 124 127 112 139 109 128
Tonnes of white 84 103 84 113 89 85 100 71 77
Total production 183 236 212 237 216 197 239 180 205
Total diesel use (l) 21789 20987 24154 25534 28437 28794 31200 16974 9897
Total govt units 166425 238476 210656 211800 196032 201704 212156 254311 287643
Total electricity units 242686 311930 295195 301169 295561 302483 321356 313720 322282
Electricity units / tonne 1326 1321 1392 1270 1368 1535 1344 1742 1572
Total water 2232 3419 3015 2981 3052 3299 2565 3372 3486
Water use l/kg 12.4 14.5 14.2 12.6 14.1 16.7 10.7 18.7 17
Total tonnes boiler fuel 643 832 762 781 747 724 759 697 689
27
Boiler fuel / tonne 3.5 3.5 3.6 3.3 3.5 3.7 3.2 3.9 3.4
The general trend of improvement reversed in January 2010 as a result of an increase in viscose dyeing
production in the fabric dyehouse and reduced quality in the yarn dyehouse.
Production levels in January in February were relatively low but you can see that by comparing months
where production levels were similar (January vs June and February vs August) that the performance was
not due to overall production volume alone - the data allows you to look at historical trends.
At this stage it is not possible to separate out the impacts of poor quality in the yarn dyehouse and longer
viscose processes in the fabric dyehouse but the key point is that the detailed data analysis has highlighted
two issues that could have put the dyehouse out of business if left unchecked.
Salt
Dyehouse #1 has an on-site water and salt recycling facility.
Dyehouse #1 are now deliberately using approximately 5% less salt for each shade in the dyehouse but this
figure is not apparent from the figures below. This is because the total (gross) amount of salt used in
processing is actually governed by the colours required by customers (darker shades need more salt).
However Dyehouse #1 are now making using a greater proportion of recycled salt and this has led to a
drastic reduction of the amount of fresh salt being used.
Jun July Aug Sept Oct Nov Dec Jan Feb
Tonnes of colour 99 133 128 124 127 112 139 109 128
Fresh Salt (kg) 11295 14640 8203 6525 5910 4315 4845 3792 3026
Total Salt (kg) 31020 40384 41973 44185 40095 43000 45025 31087 32914
Kgs / Tonne Production 313 304 328 356 316 384 324 285 257
Kgs Fresh Salt / Tonne 114 110 64 53 47 39 35 35 24
Reduction of environmental impacts and cost savings
The following table gives a summary of overall annual resource usage and costs. The annual figures and
savings have been calculated using the data provided from June to December 2009.
The exchange rates used for the calculations are as follows:
1 GBP = 69 Rupee
1 USD =46 Rupee
1 Euro =63 Rupee
Dyehouse # 1
Annual Production (Tonnes) 2,674
Cost of Boiler Wood (R/Tonne) 3,000
Annual Consumption (Tonnes) 9,210
28
Annual boiler wood cost (R) 27,630,000
Cost of Diesel (R/l) 35
Annual consumption (Litres) 318,212
Annual diesel cost (R) 11,137,420
Cost of Electricity R/unit 5
Annual Govt Electricity 2,541,648
Annual cost of Govt Electricity 12,708,240
Total Annual Electricity Units 3,655,390
Total Annual Electricity Cost (R) 23,845,660
Cost of Fresh Water (R / m3) 25
Annual consumption (m3) 36,662
Annual water cost (R) 916,550
Annual Effluent volume (m3) n/a
Annual Dyebath Effluent cost (R) n/a
Dyehouse #1 has no cost for external effluent treatment since they are a zero discharge unit but they have
extra boiler fuel and electricity costs associated with running their ETP.
The following gives a picture of how resources are used in Dyehouse #1 when operating at capacity - the
purpose is to give an accurate estimation of the savings that various efficiencies will deliver.
Boiler Fuel Electricity Water
Dyeing 25% 38%* 100%
Finishing 25% 35% 0
Effluent Treatment 50% 27% 0
For example an initiative that saves 20% of the fuel consumption in the effluent treatment will have an
overall effect of saving 10% of boiler fuel consumption since the ETP only accounts for 50%
*The figure for electricity use is much higher than indicated in a previous report - this is because the figure
for yarn dyeing is now included. Despite accounting for only approximately 20% of the production volume
the yarn dyeing machines’ pumps operate under very high pressure and consume a huge amount of
electricity.
The detail of the savings generated by the following initiatives are provided in the appendix:
Improving Lab to bulk reproducibility from 75%-90%
Reducing cycle times by 20%
Moving from a wood powered boiler to a coal powered boiler
Introducing a 3rd Reverse Osmosis module in the ETP
Introducing Cold Pad Batch dyeing
29
Some of these items require significant capital outlay but others are free - but to give an indication of what
can be achieved for little or no investment a combination of quality improvements, process optimisation
and introduction of a 3rd RO module will save Dyehouse #1 20% of its costs (approx $200,000), 2500 tonnes
of wood, half a million units of electricity and over 8000 m3 of water per annum - for a single investment of
$28,000.
The bigger capital outlay items that they now have in the pipeline can only be fully judged when the new
increased production capacity is known - however it is anticipated that the benefits will be much greater
than those highlighted above.
Dyehouse # 2
This is a busy commission dyer based in Tirupur who can dye up to 11 tonnes per day of weft knit cotton.
They have good quality machines and use a mixture of high quality European dyes and some from local
manufacturers.
Dyehouse #2 have a good attitude towards improvement and have carried out a lot of actions that will
improve their performance and efficiency.
However their data collection has been poor, and unreliable, so it is difficult to confidently quantify the
effect of their quality improvements and machinery upgrades has had on the reduction of water, energy
and chemical usage.
At the commencement of the project their (balanced) effluent was treated at an off-site CETP but they had
plans in place to move to a communal ETP that was operated by themselves and two other dyehouses in
order to reduce the cost of effluent treatment.
At the beginning of 2010 Dyehouse #2 had to suspend production for two months because of the closure of
the CETP that previously handled their effluent - Dyehouse #2 re-started at the end of February 2010 with a
reduced capacity and at the close of the project they were capped at 4.5 tonnes per day whilst their
effluent treatment plant became fully operational (it takes several weeks for the population of bacteria in a
biological effluent treatment plant to grow and become fully established).
The temporary dyehouse closure was no fault of Dyehouse #2 and it is unfortunate that they lost business
because of the closure of the CETP.
However they will ultimately emerge from the process with a lower cost operation and a lower
environmental impact process.
A relatively small dyehouse (by global standards) like Dyehouse #2 is still likely to use approximately 550
tonnes of salt each year so the move to zero discharge prevents this huge amount of salt being placed into
the local environment.
Dyehouse #2 used the time during the factory closure to implement some of the recommended process
changes and also make some upgrades to equipment which has resulted in the performance being much
better than prior to the closure.
They are also beginning to collect some data which will enable them to target areas for improvement.
30
Their full action plan is shown below but a summary of their key improvements is as follows:-
They have put measures and ‘checkpoints’ in place to get more consistent bulk processing including
control of liquor ratios, salt concentrations, pH and measurement of post-bleach whiteness levels.
Since introducing all these checks they report that ‘all bulk batches have been OK’ with no failures -
whilst a claim of 100% right first time may seem a little optimistic there is no doubting they have
improved drastically - and now even admit to pre-closure levels of 70% for bulk to bulk right first
time
Having started to gather process data the most striking feature was that their right first time
performance for new colours was significantly worse than they originally thought. They originally
said that 20% of first bulk batches required corrections and it is now apparent that the figure is
closer to 50%. Commission dyers can have up to 50% of their production made up of new shades at
certain times of the year so this single piece of information could provided them with the
opportunity to improve their performance and environmental impacts considerably.
They have identified that a single faulty laboratory dyeing machine was the biggest single cause of
their problems. Since taking it out of commission and applying the bulk ‘checkpoints’ to the first
bulk dyeings they have improved to 80% right first time.
Rather than improving a completely unsatisfactory dye and chemical storage and weighing area
they built a new one - should be operational in mid 2010.
New mangle rollers have been installed and have been operational since the factory re-start. In
theory this will dramatically reduce the electricity and fuel bills for fabric drying.
AC drives have been installed on several pieces of equipment including dryers to reduce
consumption of electricity
The dyehouse central controller has been repaired and re-programmed and has reduced dye cycle
times by ‘on average one hour’
The automatic chemical dispensing system repaired and is now operational
Dyehouse #2 have started to examine the possibility of Cold Pad Batch dyeing as part of a plan to
increase their dyeing capacity. This is probably the single most beneficial this they can do to reduce
their costs and environmental impacts. It is an inherently lower cost and lower impact process than
jet dyeing but, being a salt-free process, it is doubly beneficial in a zero discharge situation since
effluent can be recycled by the use of reverse osmosis alone rather than the need to use expensive
and energy intensive evaporators to remove salt.
£ Basics and Minimum Standards
Ensure all operatives wear appropriate personal protective equipment (gloves, goggles, shoes)
Nothing actioned
Free
Ensure all dispensed chemicals, ready for use in a dyeing, are labelled
Nothing actioned
Free
31
Improve storage and housekeeping in the dye and chemical weighing area
Major building work in progress to create improved dye and chemical storage facility
Free
Consider creating a cooled/conditioned environment for dye storage and weighing area £
Quality START TO COLLECT ALL INPUT, OUTPUT AND QUALITY INFORMATION ON SPREADSHEETS PROVIDED
Some data collection started in November - data on bulk dyeings, water, diesel, electricity and wood consumed per day still outstanding Free
Introduce specific gravity checks to confirm salt levels
S.G. Checks now in place and enabling more consistent liquor ratios. Also implemented pH and whiteness checks Free
Improve standardisation of bulk liquor ratios
Free
Always re-check lab dyes if standard liquor ratio cannot be used in bulk processing
Done
Free
Introduce a batch card for use in the dyehouse, onto which operatives record all process details
New batch card being printed
Free
Check the strength of incoming dye deliveries via lab dye checks
Nothing auctioned - may not be required if bulk RFT of 100% is maintained! Free
Create continuity cards so that batch to batch variations can be easily compared. Include details of right first time / additions/ top ups and DE read-outs on the continuity cards.
Nothing auctioned - needs to be addressed
Free
Take a sample after bleaching and measure whiteness to establish consistency of preparation.
Done - whiteness levels recorded on batch cards
Free
Use EDP's to make additions to lab dyes rather than inaccurate syringes
Now happy that syringes are sufficiently accurate £
Create a single record card for all lab dye information (to augment / replace current system of multiple cards for different aspects of lab dyeing process
Nothing actioned
Free
Seek permission from customers to submit one lab dye only for approval
Do not want to jeopardise relations with customer. Will fully support educational seminar for brands and garment makers
Free
Use instrumental colour measurement in the dyehouse to judge pass/ fail rather than using visual assessment alone. Continue to make commercial decisions but record DE failures as failure to get true figures for shade right first time.
Still done visually except where there is a problem
Free
Introduce a standardised regime for colour measurement for bulk samples - along the same lines as the lab processes. They should be washed off in the same manner, neutralised, dried and conditioned before measurement.
Nothing actioned
Free
32
Always use the original master standard when judging bulk batches. Even if a secondary standard has been created (to account for compacting) the use of the original master shade will reduce the chance of drifting away from what the customer specified
Now being used
Free
Create a team of dyehouse and laboratory staff to conduct failure analysis for all batches at are not right first time
Lab manager conducts failure analysis
Free
Conduct failure trend analysis to see if particular shades, dye combinations, machines, operatives are a problem and to analyse if problems are hue or depth problems are the major cause of failure.
Free
Repair automated chemical dispensing system
Repaired and in use £
Repair central dyehouse controller Repaired and re-programmed £
Make adjustments to account for weight losses in preparation, scouring and biopolishing
Free
Process Optimisation
Evaluate salt-at start dyeing techniques (enables s.g. Measurement - but must consider additional volume of liquid introduced with dye and alkali)
Done for dark shades
Free
Look at using reduced salt levels in all dyeings to a) reduce salt consumption b)improve level dyeing and c)provide an opportunity for reducing wash off processes. Do not alter any running bulk shades without thorough laboratory trials.
Lab checks have indicated 'unacceptable' loss in depth but dyehouse #2 do use lower salt levels than most dyers
Free
Create a graph for determining salt requirements rather than traditional dosage based on dye concentration bands. This will reduce salt usage by up to 5%
Nothing actioned
Free
Evaluate the possibility of re-using the final wash off bath in subsequent dyeings (this contains so little dye as to be insignificant compared to the first post-dye wash off bath and so can be used with little risk)
Long term aspiration
£
Evaluate the possibility of re-using the post-bleaching wash off bath for post-dye washing
Long term aspiration
£
Reduce in-bath fabric sampling to one after bleaching and one after dyeing and wash off.
Done
Free
Rigorously monitor process times and the % of time taken in sampling and for decision making - consider moving to blind dyeing for certain shades
Nothing actioned
Free
33
Factory Planning
Assess and record the real impact of inefficient colour approval processes on the dyehouse. Explain the benefits of a single numerical colour standard to customers.
Do not want to jeopardise relations with customer. Will fully support educational seminar for brands and garment makers
Free
Monitor steam and heat requirement of dyeing and drying equipment
Estimates now available
Free
Monitor fuelling of boilers and whether this can be further optimised to match heat and steam requirements
Will assess ability to match boiler output with dyehouse demand
Free
Hardware / Machinery
Investments
Consider purchase of a conditioning cabinet to improve consistency of colour measurement processes
Will cost and establish cost / benefit
£
Consider purchase of electronic dosing pipettes to improve accuracy of lab processes
Have decided to not pursue this. Auto dispenser better for dyes and satisfied with syringes for alkali additions £
Consider replacing mangle rollers to reduce moisture content of fabrics proir to drying - pay back in less than 12 months
Installed and will operate on factory re-start
£
Consider investment in moisture meters for relax drier to prevent over-drying and unnecessary use of energy
Finally clarity was obtained - they have a system for monitoring exhaust gases for moisture and control the machine using this - not as good as a fabric moisture meter but better than nothing £
Look at using /repairing moisture meters on the stenter to prevent over-drying. Even if these are shown to temporarily mark the fabric it is a useful exercise to see if the current conditions are over-drying certain fabrics. Work with garment makers to see if marks are permanent - they are unlikely to be visible on final garments.
See above
£
Assess machine insulation technology to reduce energy requirements e.g. http://www.nansulate.com/
low priority
£
Conduct cost-benefit analysis of introduction of AC drives throughout the factory (major benefit will be on the on dryer blowers
AC drives for dryers now installed
£
New high speed multi-pass stenter being considered
Colour Connections do not know of its use elsewhere £
New Technology
Assess the Huntsman enzyme 'gentle power bleach' to see if preparation temperatures and costs can be reduced
To run trials with Huntsman in April
Free
Assess the use of Cotoblanc SEL 200 in conjunction with CHT technical team to see if wash off processes can be optimised
To run trials with CHT on factory re-start
Free
Infrastructure Conduct cost-benefit analysis of heat recovery from stenter and dryers
Will carry out initial investigations
£
Data Analysis
34
Only limited data has been provided so it is difficult to present the information in any conclusive form
despite the excellent progress with certain action points.
Quality Performance
The original estimate of 80% lab to bulk right first time, provided at the start of the project was proven to
be very optimistic.
Nov Dec
Fabric 1st Bulk Batches 131 126
Fabric 1st Bulk Batches RFT 66 70
Fabric Right First Time % 50 56
The reality was that the lab to bulk right first time performance was much less than the estimated figure
and had to be addressed to improve performance. Commission dyers have a disproportionately high
number of first bulk batches compared to vertical organisations so lab to bulk right first time has a
disproportionately high impact on overall factory performance.
Detailed failure analysis highlighted that the main cause of the failures was a faulty laboratory dyeing
machine and by taking this out of commission they have achieved 80% right first time on the small number
of 1st bulk batches that have been produced sine the factory re-start - the figure of 80% is credible and has
been verified by Colour Connections.
The has been some anecdotal evidence to suggest that bulk performance had improved prior to the factory
closure, largely due to improved management of lot sizes, salt concentration and liquor ratio but data
wasn’t available to confirm this.
However since the factory re-start they have definitely been taking greater care over bulk dyeings and have
introduced ‘checkpoints’ including the measurement of salt concentration, pH, and whiteness of fabric
after bleaching and data does indicate a remarkable, if unsustainable, figure of 100% right first time on the
small number of batches that have been produced since the re-start.
It was concerning that the reason for 100% rft was given as ‘we can keep out eyes on everything all the
time when volumes are low’. On one hand it proves what they are capable of, but on the other there seems
to be an acceptance that things will get worse when they get busy. The importance of demanding
checkpoint data and ensuring processes are carried out in line with standard operating procedures has
been emphasised.
Process Optimisation
No consolidated data provided but they claim that process times have reduced to an average of 8 hours
from 9 hours as a result of the use of the repaired central dyehouse controller with new shortened
programmes - this is very plausible and appeared to be the case during the last project visit.
Resource Utilisation
35
Some actions taken by Dyehouse #2 will certainly reduce the overall environmental impacts (such as new
mangle rollers and the introduction of AC Drives) compared to the start of the project but no data is
available to confirm the extent of the improvement.
The estimates of daily resources utilisation that were provided at the start of the project are in the table
below along with monthly figures provided for the post-re-start period where production volumes were
capped.
Current Daily Production Volume (tonnes) 10
Daily wood consumption (tonnes) 37.5*
Wood consumption / tonne of fabric 3.75
Daily diesel consumption (litres) 650
Diesel consumption / tonne of fabric 65
Daily electricity consumption (units) 6480
Electricity consumption, units / tonne of fabric 648
Daily water consumption (m3) 600
Water consumption, m3 / tonne of fabric 60
Monthly figures:
Jun 09 Mar 10 Production Volume (tonnes) 240 108 Wood consumption (tonnes) 900 552
Wood consumption / tonne of fabric 3.75 5.11 Diesel consumption (litres) 15600 1920 Electricity consumption (units) 155520 144000 Total Electricity units 210120 150720
Electricity consumption, units / tonne of fabric 875 1396 Water consumption (m3) 14400 7200
Water consumption, m3 / tonne of fabric 60 67
*Previous reports have carried a figure of 15 tonnes of wood used per day. It is now clear that the figure
was for boiler wood only and that a further 22.5 tonnes (estimated) would have been required to heat the
dryers and stenters (Dyehouse #2 report that 60% of wood is used for the finishing department).
The figures provided for the factory post-start up can be treated as no more than estimates, and since the
production volume is less than half that in June it is not surprising that more wood fuel and electricity is
used per tonne.
However if the figures are even vaguely credible it does indicate that the water consumption is impressive -
particularly compared to Dyehouse #3.
In future when their ETP is working they will be consuming much less water (net) because they will be
recycling water.
Reduction of environmental impacts and cost savings
36
Dyehouse #2 report that they have the following breakdown of water, wood and electricity consumption in
their dyehouse:
Boiler Fuel Electricity Water
Dyeing 40% 40% 100%
Finishing 60% 60% 0
Their quoted usage and unit costs for the pre-shut down situation are in the following table and these
figures have been used to calculate savings from the initiatives they have put in place.
Dyehouse # 2
Annual Production (Tonnes) 2880*
Cost of Boiler Wood (R/Tonne) 3,100
Annual Consumption (Tonnes) 10800
Annual boiler wood cost (R) 33,480,000
Cost of Diesel (R/l) 38
Annual consumption (Litres) 187,200
Annual diesel cost (R) 7,113,600
Cost of Electricity R/unit 5
Annual Govt Electricity 1,866,240
Annual cost of Govt Electricity 9,331,200
Total Annual Electricity Units 2,521,440
Total Annual Electricity Cost (R) 16,444,800
Cost of Fresh Water (R / m3) 55
Annual consumption (m3) 172,800
Annual water cost (R) 9,504,000
Annual Effluent volume (m3) 155520
Annual Dyebath Effluent cost (R) 12,441,600
The appendix contains estimates of the savings generated by the following initiatives that have already
been implemented - water and electricity savings will definitely be seen by the dyehouse although savings
on boiler fuel will only be realised if the boiler and thermic flue can be modulated:
Improving bulk to bulk from 75 - 90%
Improving Lab to bulk from 55 - 80%
Installing new mangle rollers to squeeze out more moisture
Installation of AC drives on dryer and stenter
As with Dyehouse #1 it shows that remarkable reductions of 20% of annual costs and environmental
impacts can be achieved for a relatively low investment.
37
In this case an investment of $80,000 leads to annual savings of approx $300,000 -achieved by saving 2200
tonnes of wood, 750,000 units of electricity, 12700 m2 of water which in turn leads to less effluent.
The savings in effluent treatment costs will now not be realised in terms of CETP fees but it will make their
own ETP cheaper to run.
The calculations for Dyehouse #2 will be slightly more complicated in the future because their new zero
discharge effluent treatment plant will be co-owned by three different dyehouses. The calculations in the
report are based on their present set up of off-site effluent treatment.
(NOTE: an example of how Dyehouse #2 justified investment in new mangle rollers was given in a previous interim
report and they based their calculations on 60% of boiler fuel and 70% of electricity being used for drying and finishing
but these figures have not been confirmed - it doesn’t alter the fact that investing in new mangles is a sensible move
but does slightly change the calculated payback time)
Dyehouse # 3
Dyehouse #3 is part of a vertical garment company and is based in the Sipcot development in Perundurai.
They are a small dyehouse with a capacity of 3 tonnes per day and at times during the project they were
operating at very low production volumes.
Effluent is sent to a SIPCOT based CETP for treatment and Dyehouse #3 pay a charge for this service.
They use good dyes, the dyeing machines are of a good standard and they are technically proficient.
Dyehouse #3 have a mix of simple, lower impact washing processes (pre-dyed striped fabrics that are
simply washed) and higher impact dyeing processes.
Of the selected factories Dyehouse #3 have implemented the least number of items from their action plan.
This is largely because their bulk to bulk reproducibility is so good (95%+) they do not want to do anything
that will jeopardise that performance - even though they recognise the merits of the actions.
Towards the end of the project they provided some good data dating back to November 2009 onwards that
enabled us to highlight to them their actual performance and which also allows them to quantify the
benefits of the proposed initiatives.
Some actions have been taken and the most beneficial are as follows:-
Data analysis has shown lab to bulk reproducibility is not as good as they thought. They are now
working with dye companies to introduce better dye combinations and are also improving their
internal processes and laboratory equipment.
Trials have now convinced the management that there is variation between the laboratory
technicians and they are looking to purchase more robust equipment. Difficult shades are now
being dyed with more appropriate dye recipes.
38
They are also seeking advice from the dye companies on shortening dyeing processes by removal of
unnecessary migration methods.
Failure analysis is now conducted to look at the reasons why batches have gone wrong.
The biggest issue for Dyehouse #3 during the project has been the cost of running the factory when
production volumes have been low. They are now taking steps to consolidate production and turn
off boilers and machines where possible to reduce fuel and electricity use per unit of production.
The detailed action plan that was drawn up for Dyehouse #3 is shown below.
Action Progress £ Basics and Minimum Standards
Ensure all operatives wear appropriate personal protective equipment (gloves, goggles, shoes)
Nothing changed but not a major problem anyway Free
Ensure all dispensed chemicals, ready for use in a dyeing, are labelled
Nothing changed but not a major problem anyway Free
Consider creating a cooled/conditioned environment for dye storage and weighing area
Non-critical suggestion, nothing actioned
£
Mend all leaking steam pipes Some fixed Free
Quality START TO COLLECT ALL INPUT, OUTPUT AND QUALITY INFORMATION ON SPREADSHEETS PROVIDED
Data collection has started - need some more detail Free
Introduce specific gravity checks to confirm salt levels in bulk dyeings
Now checked in critical shades Free
Calculate liquor carry-over from one bath to the next for different fabric qualities using s.g. checks and water meters to get accurate liquor ratio information
Nothing actioned
Free
Seek permission from customers to submit one lab dye only for approval
Not prepared to upset customers despite illogical request! Free
Use instrumental colour measurement in the dyehouse to judge pass/ fail rather than using visual assessment alone. Continue to make commercial decisions but record DE failures as failure to get true figures for shade right first time.
Instrumental colour measurement being done on finished fabric - New Spectrophotometer in use
Free
Always use the original master standard when judging bulk batches. Even if a secondary standard has been created (to account for compacting) the use of the original master shade will reduce the chance of drifting away from what the customer specified
More data standards are being provided Still using secondary standard. Customers giving very small cuttings rather than good standards and qtx data files in most cases.
Create a team of dyehouse and laboratory staff to conduct failure analysis for all batches at are not right first time
Failure analysis being implemented
Free
Conduct failure trend analysis to see if particular shades, dye combinations, machines, operatives are a problem and to analyse if problems are hue or depth problems are the major cause of failure.
Data showing that lab to bulk RFT is major area for quality improvement - 66% is much worse than verbally quoted figure at the start of the project
Free
39
Introduce consistent method for conditioning samples prior to colour measurement
Not done Free
Process Optimisation
Look at using reduced salt levels in all dyeings to a) reduce salt consumption b)improve level dyeing and c)provide an oportunity for reducing wash off processes. Reducing salt by 10 or 20% may result in a drop in depth of shade of 1 or 2 % in some instances but does offer the opportunity to reduce wash off procedures considerably. Currently using 15-20% more salt than other dyehouses in the region for similar shades.Do not alter any running bulk shades without thorough laboratory trials.
Lab trials have shown reduced salt level to yield reduced depth of colour. However need to re-examine this using mixed alkali package
Free
Create a graph for determining salt requirements rather than traditional dosage based on dye concentration bands. This will reduce salt usage by up to 5%
Not Done
Free
Trichromats are currently dyed with Remazol RGB shades. This is not a recommended combination - consider moving to Levafix CA or Itofix VM ( probably the most robust trichromat available) to improve reliability and levelness
Meetings held with DyStar and Huntsman to look at all dye combinations, salt and alkali recommendations and processing methods. New dye recipes now being used for difficult shades.
Free
Examine all shades currently dyed using migration methods and consider which can easily be moved to shorter and cheaper isothermal processes.
Free
Used mixed alkali systems to fix dark shades. Higher levels of fixation will allow shorter wash off procedures.
Free
Rigorously monitor process times and the % of time taken in sampling and for decision making.
Data collection started Nov 1st Free
Factory Planning /
Management Systems
Assess and record the real impact of inefficient colour approval processes on the dyehouse. Explain the benefits of a single numerical colour standard to customers.
Reluctant to do anything to jeopardise customer relationship
Free
Monitor steam and heat requirement of dyeing and drying equipment
Data not yet available - estimates only Free
Monitor fueling of boilers and whether this can be further optimised to match heat and steam requirements
Data not yet available
Free
Monitor and report sample volumes produced compared to bulk production and consider setting an in-house limit
Done
Free
Consider partial wash-off of samples and issuing disclaimer to customers saying sample is for colour only (to save on water and energy used in sampling)
Samples dyed on bulk bleached fabric to shorten processes
Free
When production volume is low consider taking on commission work to improve per unit costs and environmental impacts
Not part of company policy
Free
40
When production volume is low consider reducing working time of factory to less than 6 days per week. Sending workers home on full pay is much cheaper than inefficient operation of the factory
Factory planning now higher priority when production volumes are low.
Free
Hardware / Machinery
Investments
Consider purchase of a conditioning cabinet to improve consistency of colour measurement processes
Deemed too expensive
£
Consider purchase of electronic dosing pipettes to improve accuracy of lab processes
Evaluating Mettler and Toledo £
Consider investment in moisture meters for relax drier to prevent over-drying and unnecessary use of energy
Quotes ‘due from Monforts’ - original request was allegedly made in September £
Assess machine insulation technology to reduce energy requirements e.g. http://www.nansulate.com/
£
Consider pin-entry for relax dryer to remove the need to double passes on certain heavy fabrics.
Quotes due from Bianco. Double pass now replaced by single slow speed pass. £
New Technology
Assess the Huntsman enzyme 'gentle power bleach' to see if preparation temperatures and costs can be reduced
Meeting to be arranged.
Free
Assess the use of Cotoblanc SEL 200 in conjunction with CHT technical team to see if wash off processes can be optimised
Meeting to be arranged.
Free
Infrastructure Conduct cost-benefit analysis of heat recovery from and dryers (Koenig suggested)
In discussion with Forbes Marshall, who have carried out some on-site surveys £
Hot water system - planned In-house project still not started £
Data Analysis
Dyehouse #3 have provided data for November, December and January.
They have three types of production:
Whites
Coloured dyeings
Washing of yarn dye stripes
Full information on the split between whites and coloured production is not available but information on
the amount of washing vs dyeing is provided.
The data needs to be handled carefully as results will vary from month to month depending on the
production mix (for example in both November and January 60% of batches were dyed and 40% were
washed, but in December 73% of batches were dyed).
Quality Performance
41
The figures below are for November 2009 to January 2010 inclusive and are for coloured dyeings only. No
information was made available for January onwards.
Nov - Jan
Fabric 1st Bulk Batches 32
Fabric 1st Bulk Batches RFT 21
Fabric Right First Time % 66
This figure is significantly lower than they indicated at the start of the project - Dyehouse #3 now taken the
sensible step of moving to industry best practice dye recipes to address the problem and have reported an
improvement ‘to about 80%’ - although no data was available to confirm this.
The bulk to bulk performance is exceptionally good and can be rated at world class - but the reluctance to
do anything that may risk a drop in this figure is holding Dyehouse #3 back and they are in danger of going
out of business due to high costs.
Nov - Jan
Fabric Bulk Batches 203
Fabric Bulk Batches RFT 195
Bulk Right First Time 96
Process Optimisation
The average process time is 10.89 hours which is much longer than industry best practice.
Reducing cycle times provides Dyehouse #3 with a major opportunity for improvement and they are to
examine shorter dyeing process, lower impact bleaching and shorter wash off processes.
Dyehouse #3 are certainly good enough to move to blind dyeing (96% right first time is world class) and the
removal of checks at the end of dyeing would save them time.
Resource Utilisation
Daily analysis of electricity and boiler fuel consumption in relation to production volumes is not possible
because daily production data is not available.
However it is possible to look at the relationship between electricity consumption and boiler fuel
consumption over the period of November 2009 to January 2010.
Dyehouse # 3 have had low production volumes over the period of the project and encouragingly they do
now try to plan production so that the boiler and machines can be switched off on days when there is no
production - resulting in lower energy consumption.
The graph below shows that in contrast to Dyehouse #1 the amount of boiler fuel used each day does vary
significantly. This suggests that they are able to modulate steam output to match dyehouse steam demand
- although it will need to be viewed against daily production volumes to confirm this.
42
Electricity consumption is more consistent, particularly in December and January (number 31 onwards on
the horizontal axis), indicating that they will need to monitor whether high consumption machines are
being left switched on all day even when production volumes vary - again this will need to be viewed
alongside daily production volumes to confirm this.
Monthly Averages
Jun* Nov Dec Jan
Tonnes of colours + white 25 51 42
Tonnes of washing 15 17 30
Total production ~50 40 68 72
Total diesel use 1840 7804 3450
Total govt units 49237 81484 66054
Total electricity units 55677 108798 78129
Electricity units / tonne 1462 1391 1600 1085
Total water 4439 6835 6522
Water use l/kg 60 111 100 91**
Total tonnes boiler fuel 170 283 234
Boiler fuel / tonne 5 4.3 4.2 3.3
*Figures for June were estimations only
**The water consumption is probably even higher than the figures given in the table. Up to 115 litres per
Kg are taken into the factory and explanations that around 15% of incoming water ‘is low grade water for
watering plants only’ lack credibility.
The reduction in water and boiler fuel usage per tonne looks impressive but this is largely because of the
increasing production volume between November and December and also a greater proportion of
(relatively low impact) washing work in January compared to December.
Detailed data on the comparative energy and water use of coloured dyeings, white dyeings and washing
processes are required to make it possible to confirm there is a genuine underlying improvement in
resource utilisation.
The most obvious figure here is that Dyehouse #3 uses approximately 100 litres of water per kg of
production - a lot more than their estimate of 60 l/kg at the start of the project.
43
Reduction of environmental impacts and cost savings
Dyehouse #3 have not been able to provide data to firmly establish the breakdown of resource utilisation in
the different areas of the factory but their estimate is as follows:
Boiler Fuel Electricity Water
Dyeing 50% 50% 100%
Finishing 50% 50% 0
The annual usage of resources and cost is shown in the table below:
Dyehouse # 3
Annual Production (Tonnes) 724
Cost of Boiler Wood (R/Tonne) 3,500
Annual Consumption (Tonnes) 2,748
Annual boiler wood cost (R) 9,618,000
Cost of Diesel (R/l) 44
Annual consumption (Litres) 52,376
Annual diesel cost (R) 2,304,544
Cost of Electricity R/unit 4
Annual Govt Electricity 787,100
Annual cost of Govt Electricity 3,148,400
Total Annual Electricity Units 970,416
Total Annual Electricity Cost (R) 5,452,944
Cost of Fresh Water (R / m3) 40
Annual consumption (m3) 83260
Annual water cost (R) 3,330,400
Annual Effluent volume (m3) 59980
Annual Dyebath Effluent cost (R) 9,596,796
The potential savings for the initiatives that have been discussed with Dyehouse #3 are contained in the
appendix.
Consolidation of work into 5 days
Improvement of lab to bulk reproducibility from 65 to 80%
Reducing cycle times by 20%
Finding water ‘losses’ and reducing consumption by 20% (The dyehouse manager is insistent that
dyeing processes use less water than they are consuming/paying for so water losses need to be
accounted for).
44
At this stage it is not possible to verify whether any savings have been delivered despite assertions that lab
to bulk reproducibility has been improved and indications that greater efforts have been made to
consolidate production into fewer days.
However the data shows that Dyehouse could reduce their costs and environmental impacts by up to 30%
without any capital investment. The majority of the savings will be achieved by reducing cycle times and
simply planning the production more efficiently.
3. EcoMetrics
EcoMetrics (www.colour-connections.com/EcoMetrics) is a tool developed by Colour Connections to
qualitatively assess products and processes in terms of water, energy, use of chemicals and pollution.
It considers the whole life cycle of a product from fibre production through to disposal but it can be applied
to examine specific processes such as dyeing in more detail.
High negative environmental impacts are given a high score and denoted by red flags and and low
environmental impacts are given a low score and denoted by green flags - each part of the process is
assessed in terms of water, energy, chemicals and pollution and a total score is calculated. A bright pink
colour is used to indicate scores/impacts that are significantly worse than industry average.
The EcoMetrics principles have been used throughout the Eco Efficiency project and there has been a
balanced assessment of each of the four key factors (rather than, say, focusing just on carbon emissions).
Tirupur is a great example of where a balanced approach, promoted by EcoMetrics, has been important in
reducing the environmental impacts. Had the focus been on CO2 emissions rather than on pollution the
move to zero discharge would not have been made. The move to Zero discharge has almost eliminated
water pollution, drastically reduced net use of water for dyeing in the region (because of enforced
recycling), reduced chemical consumption (because of forced recycling of salt) but has necessitated the use
of more fuel and electricity to power the zero discharge plants.
The principles of EcoMetrics have been applied to the project rather than a rigorous scoring system but a
qualitative indication of how the selected dyehouses compare to industry average is shown below.
The EcoMetrics tool can assess a whole production process but in this case we have focussed on a
combined snapshot for the dyeing process.
The approach gives a qualitative snapshot of the performance in terms of:
Water impact
Energy
Use of non-renewables (other than for energy production)
Pollution
The industry average profile for reactive dyeing process of weft knitted cotton in jet dyeing machines is
based on a total water consumption of 100 – 120 litres of water per kg, 8 -12 hour dyeing cycles and
effluent treatment followed by discharge into a receiving waterway.
45
It looks like this:
Water Energy Use of non-renewables Pollution
Lots of water is used and therefore lots of energy has to be used to heat the water and run the machines
for prolonged periods of time. Lots of chemicals have to be used for scouring and bleaching, and lots of dye
is applied using lots of salt. Even though effluent treatment is carried out there is still a significant amount
of chemicals that enter the environment as a result of the process.
The following section gives a visual indication of how good and bad the dyehouses the selected dyehouses
are compared to industry average.
Dyehouse # 1
Water Energy Use of non-renewables Pollution
The water impact is very low as the net usage is less than 10 litres per kg. Salt is re-cycled and, being a zero
discharge dyehouse, no pollution leaves the site, except from the boiler stacks and generators. The
downside is that the energy consumption is very high because of the need to power the dyehouse and the
ETP and evaporators. The high quality, good factory efficiency and low water consumption keeps energy
usage in line with ‘average’ dyehouses.
As demonstrated in the project their key objective is to reduce energy consumption and to achieve this
they do have to consider their gross water consumption.
When Cold Pad Batch dyeing is introduced alongside the jet dyeing they will reduce gross water and energy
consumption and their profile is likely to reach the following excellent situation.
Water Energy Use of non-renewables Pollution
Dyehouse # 2
46
Water Energy Use of non-renewables Pollution
The water consumption figures at the start of the project were much better than the industry average but it
has been established that energy consumption was quite poor (after the latest boiler fuel figures became
available). The use of non-renewables was in line with industry average but since it has been established
that the CETP they were using was NOT zero discharge the impact was high. (The amount of effluent was
the same as say a European dyehouse but the impact is much higher in Tirupur because of the existing
problems and lack of dilution).
The move to their own zero discharge facility will drastically improve their net water usage and use of non
renewables (they will use recycled water and salt from the ETP) and they will no longer have a pollution
issue.
However they will use even more energy per tonne of production (required to run the ETP) and they will
have to constantly strive to reduce energy consumption. They are likely to achieve the following:
Water Energy Use of non-renewables Pollution
If they do go ahead and introduce cold pad batch dyeing (currently being examined) they can improve
towards the performance of Dyehouse #1 although will need to work very hard to achieve an orange rating
for energy.
Dyehouse # 3
Water Energy Use of non-renewables Pollution
The water usage originally quoted at the start of the project was much better than industry average but it
became clear that they were under-estimating the amount they use. Because a relatively large dyehouse is
being used to dye a relatively small amount of production, the energy consumption is enormous.
47
It became clear during the project that the CETP used by Dyehouse #3 was genuinely zero discharge but
they do not use any recycled salt and the use of recycled water is very low.
By improving production planning, reducing water consumption and reducing cycle times they will be able
to achieve the following:
Water Energy Use of non-renewables Pollution
This is not as good as the other two dyehouses but is still much better than the industry average. Ultimately
they could potentially obtain a green rating for water if they used more recycled water in their processing.
4. Key Best Practice
The following is a summary of the best practice developed for the dyehouses in this project. Some of the
best practice is only applicable to jet dyeing of cotton (indicated by [co] but most is universally applicable to
all dyehouses.
Quality
Systems to collect and analyse quality data are essential for determining factory performance and
identifying opportunities for improvement. Key measures that should be put in place are:-
o % Lab to bulk right first time
o % Bulk to bulk right first time
o %Re-finish
o Actual dye process times vs programmed process times
o Machine utilisation
o Resource utilisation
Electricity per unit of production
Boiler / Heating fuel per unit of production
Water consumption per unit of production
Chemical consumption per unit of production
Effluent cost/volume per unit of production
Set up a team to conduct failure analysis to highlight the reasons why things have gone wrong
Ensure batch cards are designed to collect maximum amount of process data and that operatives
sign cards to confirm processes have been carried out correctly
Ensure production is managed to give a consistent liquor ratio in dyeing
[co] Ensure salt levels in dyeings are measured, controlled (and reproduced in laboratory dyeings)
Use high quality, tightly standardised dyes
Use the best dye weighing and dispensing equipment you can afford
48
Use sophisticated machine controllers to ensure process consistency and to automatically record
deviations from set programmes
Ensure product examination and testing is carried out in-house and that results are used as data for
continuous improvement programmes
Never confuse a commercial decision with a technical decision - ensure all right first time data is
based on a ‘pass’ against a set standard
Dyeing Process Optimisation
Ensure process time is a business Key Performance Indicator
Use machine controllers to develop shortest possible dyeing programmes
o Use pre-heated hot water to save time on heating
o Use ‘parallel’ functions rather than sequential functions wherever possible to shorten time
o Use combined cooling and rinsing (CCR) type rinsing programmes to save time but ensure
water use is carefully managed
[co] Reduce the amount of salt in dyeings to allow easier dye wash off with less water
[co] Do not use migration methods unless absolutely necessary for the most difficult shades
Evaluate current wash off processes to see if any baths can be removed without compromising
quality
Review dyeing methods and reduce ‘over-safe’ dosing times and unnecessary holding times
[co] Reduce unnecessary fabric checks and sampling but ensure pH and salt checks are retained
Factory Planning / Systems
Conduct machine utilisation studies to calculate the portion of time machines are actually
processing production
Consolidate production and switch off machines and infrastructure (boilers, generators,
compressors) when not in use
Develop factory processes based on objective colour management and the dyehouse ability to
match a data standard and make objective pass/fail judgements
o Do not keep fabric in a wet state whilst QC subjective decisions are made by customers
Machinery Upgrades and Hardware
Install machines controllers, or better still central controllers to ensure process consistency and
recording of process data
Invest in high speed hydroextractors and harder mangle rollers to improve removal of water prior
to final drying
Replace DC drives on motors, pumps and blowers with more efficient AC drives
Insulate machines to reduce heat losses
New Technology
[co] Evaluate enzyme bleaching technology to save energy
[co] Evaluate in-salt detergent technology to reduce time, water and energy used in reactive dye
wash off
[co] Evaluate the use of continuous bleaching and counter-flow wash off to reduce time, water and
energy used in reactive dye wash off
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[co] Consider cold pad batch dyeing for knitted cotton fabrics to reduce time, water, energy and
chemicals used in dyeing AND to remove salt from effluent
Infrastructure
Select boilers that can be modulated to match steam demand
Recycle steam condensate
Recover heat from effluent and from dryers and stenters
Develop a hot water system to save on heating time and to provide heat sink for re-cycled heat
Consider co-generation
Consider renewable energy sources
Consider full or partial recycling of water
5. Best Practice Seminars
Best practice seminars were held in three locations to share best practice with the wider Indian dyeing
industry.
Colour Connections enlisted the assistance of the Society of Dyers and Colourists to help with local
arrangements a selection of world renowned organisations presented best practice lectures to address the
specific opportunities highlighted by the project.
Each seminar had a cap of 100 pre-registered delegates.
Tirupur 24th March 2010
Demand was exceptional and locals described the event as the best ever held there and said delegate
numbers were ‘unprecedented’. The project focussed on processes for weft knit cotton and since the
majority of the audience were from that industry both the specific and general content was relevant to
them - the venue had to be closed when 153 delegates had entered the conference! 40 more unregistered
delegates had to be turned away for safety reasons.
Mumbai 25th March 2010
The Mumbai seminar also attracted over 100 delegates on the day but the number was not as great as at
Tirupur and the venue coped easily.
Unlike Tirupur, where they only produce weft knit cotton, there is a mix of different industries in the
region. Some of the specific references to weft knit cotton would not have been directly relevant to all
delegates but most of the best practice from the project is still applicable to any dyeing operation and
delegates stated that they were highly satisfied with the content.
Jodhpur 26th March 2010
The industry in Jodhpur is basic and in need of significant improvement. On one hand it was the perfect
place to hold a best practice seminar as the industry is in dire need of expert advice. However some
delegates’ existing level of knowledge was so low that some of the seminar content was aspirational.
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An audience of over 90 delegates was judged once again to be ‘unprecedented’. Credit must go to the
Society of Dyers and Colourists who have identified this area as being in need of improvement and who
lobbied Colour Connections to run one of the seminars in this region rather than in more developed areas.
The support of retail brands was genuinely beneficial to the project but if future dyehouse projects do take
place the Jodhpur is probably a better candidate than Tirupur. Most dyehouses have no concept of
efficiency because water is free (although incredibly scarce) and they discharge untreated effluent into the
rivers.
There is no way large brands would want to be associated with this sort of dyehouse but there is need to
improve to reverse the environmental damage that is occurring.
6. Key Findings of the Project
There is potential to make very large reductions in the environmental impact of dyehouses by
implementation of best practice.
The biggest challenge is getting dyehouse staff engaged and motivated to improve when they are
busy with day to day production issues.
o The inability of factory staff to allocate sufficient time to improvement projects is the major
hurdle to improving the dyeing industry.
Data collection is very, very important. In good dyehouses it is very difficult to identify areas that
require improvement without data and opportunities for improvement can be lost.
It is possible to significantly reduce costs and environmental impacts by simple, low cost actions but
in order to maximise progress some capital investment is necessary.
Even though some progress has been made with the selected dyehouses and steps taken to deliver
further benefits in the coming months the time allowed for an industrial project with working
factories was not enough (June 2009 to March 2010)
7. Recommendations for modifications if Eco-efficiency project is run in other Countries
Allow more time.
Choose poorer dyehouses - representative of the industry average and below. Brand support would
be difficult because do not want to be publicly associated with poorer dyehouses.
Engage factory owners at the outset.
o Eco-efficiency projects are dyehouse profitability projects! The owners will get the main
financial benefits whereas the factory managers get no extra money whilst being expected
to do the projects in addition to their day job.
Include an on-site expert project (such as MentorSys from Intertrad, www.intertradgroup.com )
with permanent on-site project teams in addition to the consultancy approach.
Next Steps
Each dyehouse will be provided with an action plan to work on after the completion of the Defra project.
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8. Appendix
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The appendix is contained in a separate document and contains the details of the following:-
1. Dyehouse screening reports
2. Data collection templates
3. Calculations for savings for dyehouse initiatives
Phil Patterson Managing Director +44 (0)7799 656786
www.colour-connections.com
Colour Connections Consultancy Ltd is a private limited company, registered in England & Wales 10th Sept 2007, no. 6366020, registered office
141-145 Dale Road, Matlock, Derbyshire, England.