Co-funded by the Intelligent

Energy Europe Programme of

the European Union 1

Co-funded by the Intelligent Energy Europe

Programme of the European Union

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 2

Overview

Introduction

Theory Approach (some remarks)

Main components

Compressed air flow rate

Inappropriate air users

Leakage

Parameters that influence consumption

Exercises

Business Case

Summary

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 3 Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 4 Introduction - Theory - Exercises - Business Case - Summary

AIR IS FREE….BUT COMPRESSED AIR ISN’T FREE

ENERGY EFFICIENCY OF MOST OF

COMPRESSED AIR PLANTS IS QUITE

LOW

COMPRESSED AIR CAUSES A COST THAT ISN’T ALWAYS TAKEN

IN ACCOUNT

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 5 Introduction - Theory - Exercises - Business Case - Summary

Electric energy costs

Leakage costs

Maintenance cost

Plant modification cost

The costs of electric energy reach the 73% of total cost during the life

of air compressed system.

REASONS FOR EXCESS COST

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 6

Reasons for exces consumption

Excess consumption through technical issues:

– Use of outdated and low efficiency electric engines

– Air distribution system not appropriated

– To high air leakage

– Compressed air engines fed with hot air

Excess consumption through behavioral issues:

– Use of too high pressure

– Compressed air engines turned on unnecessarily

– Use of compressed air to do the cleaning

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 7

Optimizzation of air

compressed system will

deliver savings of up to 35

%.

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 8 Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 9

Approach (some remarks)

1. Identify how much air flow and

pressure each user machine needs

2. Find the right place for each user

machine

3. Identify the right place for compressed

air machines

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 10

MAIN COMPONENTS

1. Air inlet filter

2. Air compressor, electric

motor and panel control

3. Air treatment (oil separator,

dryer, filtration)

4. Storage tank

5. Distribution Network Fonte: Improving air system performance DoE - Energy Efficiency and Renewable Energy

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 11

Compressed air flow rate

- inappropriate air users

- leakage

The flow rate produced a direct bearing on

consumption.

The compressed air flow rate depended on

requirements.

Therefore must be avoided:

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 12

Inappropriate air users

Transport of powders at low pressure

Ventilation

Agitation liquids

Cleaning in general

Removal of defective products from a line

Blowers

Mechanical arm

Electrobrushes

Mechanical agitators

Fans; Blowers

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 13

LEAKAGE

• Accurate assessment with specific equipment

• Rough estimate

If more than 5% requires action!!

How to assess the losses?

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 14

Parameters that influence

consumption

• L is the work

• M is the mass flow rate of air

• R is the universal gas constant,

• T1 is the inlet air temperature (°K),

• β is the ratio between the compression end pressure and beginning of compression,

• m is the exponent of the transformation,

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 15

Choose an appropriate level

The increase of a bar of produced air pressure causes an

increase of about 7% of the energy consumption

If the process requires two pressure levels is good to evaluate the installation

of two compressors instead of one (with the need to achieve the lowest

pressure by reducing valves).

Parameters that influence consumption Maximum pressure

The operating pressure of a compressor directly affects the power consumption

and energy consumption.

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 16

• Increase in operating costs

• Small diameters, lower installation costs, more losses and hence higher

operating costs

The pressure drop of the network (pipes) should never result in a pressure

drop greater than 0.1 bar

• The level of surface finish of the tubes affects the load losses

Parameters that influence consumption Pressure drop

The pressure drop of the network (pipes) should never result in

a pressure drop greater than 0.1 bar

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 17

• The minor work is assured in the case of an isothermal transformation m = 1

• The work is greater in the case of an adiabatic m = 1.4

Parameters that influence consumption Type of transformation

To get closer to an isotherm must carry away heat during

compression

The removed heat can be used

• Only 10% of the electricity consumed by a compressor is converted into

useful energy to compress the air

• 90% of the electrical energy is converted into heat to be eliminated, but that

can be recovered (heating environment, pre-heat combustion air, heating hot

water, pre-heat process water)

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 18

The work made by the compressor for compressing the air increases with

increasing temperature of the inlet

• The temperature of the input should be as short as possible, consistent with

current environmental conditions

• Do not take air from the compressor room or another, it is always best to take

air from the outside

• The starting point must be taken possibly in the north and in the shaded area

Parameters that influence consumption Inlet air temperature

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 19

The air quality depends on its content:

• Particulate.

• Water (expressed in temperature of the dew point of the air pressure)

• Oil (measure)

• Material of the network and its state

Parameters that influence consumption Air quality

Air quality must be adapted to the needs of the process

Air quality has a greater cost.

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 20

Water

The water comes from atmospheric moisture in the air

Removing water from the air can be done:

- At central Referigeration

- At the local level Steam Traps

The refrigeration is more efficient, but more expensive from the point of view of

plant and exercise.

The steam traps have a lower cost of installation, but require higher maintenance

costs and leads to losses of air.

Parameters that influence consumption Air quality

Particulate matter can be removed by input filters

The oil can be removed by filters or at the source, using oil-free compressors.

The two solutions should be evaluated as a function of the different costs.

The oil-free compressors increase the cost of installation

The filters increase the costs of operation and maintenance

The filters should be checked regularly

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 21

1. Start - stop (power 5-10 kW)

2. Running load - idling - stop (power> 10 kW)

3. Speed control of Compressors

Regulation system are influenced by:

• Oversized Compressor

• Control of the compressor speed

• The presence of a storage tank

Parameters that influence consumption Regulation system

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 22

•Meets sudden demands for air

•Allows for greater stability in the level of pressure on the network

•Reduces Stop & Go of the compressor

•Provides sizing the compressor below the maximum values pressure

• The option of installing secondary tanks near the isolated users and / or highly

intermittent can be consider

Sizing of the storage tank

•The size of the tank depends on the extent of changes in the demand for air.

The size should be at least 10 times the volume of air produced by the

compressor (l/s)

•The size of the tank affects the sizing of the compressor

Parameters that influence consumption STORAGE TANK

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 23

• Do not oversize the compressor

• Storage Tank

• Control of the compressor speed

• Type of compressor

• High efficiency engine

Parameters that influence consumption Compressor & control

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 24

Acquisition of data on consumption of electricity

• Can I make special measures? (High cost, more accurate)

• Can I use the data available? (low-cost, lower precision)

Parameters that influence consumption How to handle the compressed air system

Evaluate the cost of compressed air

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 25 Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 26

LEAKAGE REDUCTION

What is the effect of a hole of 10 mm in

a compressed air network (@ 7 bar

pressure)

Introduction - Theory - Exercises - Business Case - Summary

a.Up to 10 kW loose

b.Up to 40 kW loose

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 27

HOLE (mm)

Flow rate @ 7bar (l/s)

Power loss (kW)

1 1,2 0,4

3 11,1 4

5 31 10,8

10 124 43

Introduction - Theory - Exercises - Business Case - Summary

LEAKAGE REDUCTION

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 28 Introduction - Theory - Exercises - Business Case - Summary

HIGH EFFICIENCY ENGINES

How much to save by replacing a

standard engine with a high

efficiency engine?

a. Up to 1%

b. Up to 5%

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 29 Introduction - Theory - Exercises - Business Case - Summary

Power [kW]

HIGH EFFICIENCY MOTOR

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 30 Introduction - Theory - Exercises - Business Case - Summary

REDUCTION OF AIR SUCTION

TEMPERATURE

How much energy savings can be

obtained with the cooling air inlet 5°C?

a. Up to 2%

b. Up to 10%

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 31 Introduction - Theory - Exercises - Business Case - Summary

Technical literature reports that a

reduction of 5 °C of compressor input air

temperature (with respect to usual

temperature) would allow saving of 2%

of yearly consumed kWh.

REDUCTION OF AIR SUCTION

TEMPERATURE

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 32 Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 33

Practical example Porsche industry

Introduction - Theory - Exercises - Business Case - Summary

Description:

In 1997, the system of compressed air production of "plant2 " of the German

automobile factory Dr. Ing hc F. Porsche AG near Stuttgart was constituted by a

screw compressor - cooled water (22,2 m3/min, FAD) plus four reciprocating

compressors water cooled from 15 m3/min each.

The maximum operating pressure was 8.7 bar.

An analysis on the compressed air system, carried out by specialists of a factory

compressors, noted compressed air demand varies between 15 and 65 m3/min.

By processing all relevant data has been defined a new compressed air system

with optimized use of energy.

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 34

Action taken:

The new system was divided into two stages comprising only air-cooled screw

compressors.

Load peaks were satisfied with the use of three machines with a 5.62 m3/min

FAD each, while the base load was covered with four compressors with a FAD of

16.4 m3/min each.

All seven compressors are managed by a centralized control system.

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 35

Results:

The optimization of the compressed air system allowed us to calculate the cost

of energy and make energy savings.

the operating pressure was lowered from 8.5 to 7.5 bar and the specific power

of the overall compression station has been reduced from 8.19 to 6.19 kW /

(m3/min).

The total savings amounted to 483000 kWh of electricity per year.

Furthermore have been spared approximately € 55,000 in savings for non-

consumption of cooling water.

The optimization of the compressed air system has been realized with a

reasonable payback time

Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 36 Introduction - Theory - Exercises - Business Case - Summary

Co-funded by the Intelligent

Energy Europe Programme of

the European Union 37

Excess energy consumption through compressed air is

caused by technichal as well as behavioural issues.

Through the optimization of the compressed air plant savings

of up to 35 % are possible.

The leakage reduction can effect up to 20 % energy saving.

Adoption of high efficiency engines can effect up to 5 %

energy saving.

A reduction of 5 °C of compressor input air temperature

would allow saving of 2% of yearly consumed kWh.

Repetition

Introduction - Theory - Exercises - Business Case - Summary