maerz ofenbau lime burning technology 2008 en
TRANSCRIPT
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
1/15
Maerz
Lime Burning Technology
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
2/15
Our Company
1 2
Maerz Ofenbau AG was established in 1950
in Zurich, Switzerland, by Austrian magnesite
producers to design and sell open hearth
furnace technology to the worldwide steel
industry.
In 1965 Maerz began the design and
construction of the MAERZ Parallel Flow
Regenerative (PFR) Lime Kiln, characterised
by its high thermal efficiency and superiorlime quality, now generally known as the
MAERZ PFR Kiln.
The initial design was an oil-fired lime kiln of
150 tpd capacity. Soon larger units were
designed and gas firing technology was
added to oil firing. In the late seventies a
patented system to apply pulverised solid
fuels was introduced. Today Maerz offers
designs for PFR Kilns with nominal capacities
between 100 and 800 tpd and with firing sys-
tems for virtually all types of liquid, gaseousand pulverised solid fuels.
As a further milestone, in the late eighties,
Maerz introduced the Maerz Finelime Kiln.
This vertical-shaft kiln type allows the calci-
nation of small-size limestone and dolomite,
which in the past had to be processed in
rotary kilns with significantly lower thermal
efficiency, i.e. higher heat consumption.
In 1995 RCE Industrieofenbau Engineering
GmbH, located in Radenthein, Austria, a
specialist in the field of furnaces and kilns
for the production of refractory materials,
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
3/15
Our Achievements
3 4
became a subsidiary company of Maerz,
adding its high-efficiency single shaft kiln
to the existing product portfolio.
To satisfy the steadily increasing market
demand in Eastern Europe, Maerz established
a subsidiary engineering division MaerzOfenbau s.r.l. in Timioara, Romania, in
2005.
In 2006 Maerz joined the Polysius Group,
becoming the centre of lime business activi-
ties of the entire Group.
With Polysius know-how and personnel re-
sources, Maerz now also offers rotary kilns,
annular shaft kilns, suspension calciners and
equipment up- and downstream of the lime
kilns, thus turning into a full-line supplier of
kilns and associated equipment for the lime
industry.
By combining Maerz, Polysius and RCEs
know-how and experience in the lime burning
technology field, Maerz is in a unique position
to offer tailor-made solutions to its cus-
tomers.
The different kiln systems such as PFR
Kilns, Single Shaft Kilns, Rotary Kilns or
Suspension Calciners do not compete with,
but complement each other.
Depending on the application conditions, such
as production capacity, type of fuel, raw mat-
erial feed size, lime quality required, etc. the
decision for a certain kiln type is made by
evaluating the balance between cost, techno-
logical reliability and flexibility.
It is Maerzs policy on the basis of an extensive
product portfolio to carefully assess all initial
conditions before recommending the most suit-
able kiln technology to its customers to meetthe specific project conditions and to achieve
the required product quality.
Maerz the world leader in the construction
of lime kilns is not only in a position to offer
the most energy-efficient type of lime shaft kiln
existing to date but also the most comprehen-
sive scope of lime burning equipment.
Supported by a global network of representa-
tives and partners, Maerz can present the lar-
gest number of reference plants installed
worldwide in the lime industry by one singlecompany.
Large photo + Fig. 1
Headquarters of
Maerz Ofenbau AG in Zurich,
Switzerland.
Fig. 2 4 From the Idea
to the Start of Production.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
4/15
Lime is one of the most widespread and ver-
satile chemicals produced and applied world-
wide.
Quicklime and hydrated lime
have been used in many civilisa-
tions for more than 3000 years.
Starting from the construction
and building industry in the early
days, the uses of lime, dolomiticlime and dolomite have become
almost countless.
Vital in the steel, building and
chemical industries, as well as
in agriculture, lime is a basic
raw material that has made an
essential contribution to many
of the achievements of our
modern world.
Global production of lime isestimated to be approx. 300
million tons per year, where-
of the sales-relevant portion
amounts to approx. 120 million
tons per year. In industrialised
countries the yearly per capita
consumption of lime products
amounts to approx. 80 kg.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
5/15
Applications of Lime
Iron and steelmaking
- capturing of impurities inthe steel bath
- iron ore sintering
- desulphurisation
Non-ferrous metals
- beneficiation of non-ferrous
metal ores, e.g. copper
- recovery of gold and silver
in cyanide extraction
- flotation processes for lead,
nickel, zinc, molybdenum
and uranium
Construction and building
- mortars and plasters- sandlime bricks, aerated
concrete bricks
Chemical industry
- manufacture of sodium
alkalis, e.g. soda ash
- production of calcium carbide
Environmental applications
- treatment of water, waste
water and sewage
- air pollution control
Agriculture
- liming of soils, forests and
lakes
- compound fertilisers
Soil stabilisation
- stabilisation of road beds
for high performance roads
- construction of airport
runways, parking lots and
railway tracks
PCC industry
- paper industry
- paints and coatings
- plastics
The most important consumers of lime, dolomitic lime and
dolomite are:
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
6/15
Types of
Kilns and Calciners
Kiln type
Capacity [tpd]
Stone size [mm]
Heat input [kJ/kg]
[kcal/kg]
Key criteria
Services
Revamping
Upgrading Modernisation
Alternative Fuels
Automation
Spare parts
Rectangular
PFR Kiln
E1 E6
100 400
30 120
3390 3650
810 870
high reactivity
lime
PFR Kilns
Multi-fuel firing systems
Conversion to alternative fuels Advanced charging technology for increase of quarry yield and production
Circular
PFR Kiln
R1 R5
300 800
30 160
3390 3650
810 870
high reactivity
lime
Finelime
Kiln
F1 F3
200 400
15 40
3310 3560
790 850
high reactivity
lime
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
7/15
Product Portfolio
Annular Shaft
Kiln
A1 A3
200 600
15 200
3800 4100
910 980
high CO2-content
in off-gas
Annular Shaft Kilns
Application of solid fuels
Single Shaft Kilns
Conversion of mixed feed
kilns to solid fuel dust firingwith significant increase of
kiln capacity
Rotary Kilns
Conversion to preheater kilns
Sulphur bypass system
Single Shaft
Kiln
H1 H5
50 300
10 100
4100 4610
980 1100
medium to hard
burnt lime
Preheater
Rotary Kiln
500 1200
10 50
4820 5650
1150 1350
high production rate
low sulphur product
Suspension
Calciner
300 1200
0.03 2
5450 5860
1300 1400
finest raw material
size
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
8/15
PFR Kilns
The PFR (Parallel Flow Regenerative) kiln type is
characterised by two vertical shafts connected by
a cross-over channel.
This allows parallel flow heating, i.e. the paral-
lel flow of limestone and hot gases as well as
regenerative preheating of the combustion air in
one shaft (the burning shaft) whilst the mixture of
combustion gases and lime cooling air simultane-
ously preheats the limestone in the second shaft
(the non-burning shaft). Each shaft cycles through
the burning and non-burning mode at intervals of
approx. 10 to 15 minutes.
The Parallel Flow Principle is ideal for producing
high reactivity quicklime at the highest thermal
efficiency of all modern lime kilns.
PFR Kilns are available for capacities from 100 to
800 mt/day and can be fired with gaseous, liquid
and pulverised solid fuels.
Depending on the required production capacity,
the limestone grain size to be processed and the
fuels available, PFR Kilns of rectangular, circular
or Finelime design are proposed.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
9/15
Parallel Flow Regenerative Shaft Kilns
Rectangular PFR Kiln
The simplest design of a PFR
Kiln is to place two shafts with
rectangular cross section side
by side lengthwise in such a
manner that the kiln gases can
flow directly from one shaft to
the other via a direct cross-over
channel. Because of its geom-etry this kiln type is simple to
manufacture with reduced re-
quirements for steel structure
and refractory materials.
This straightforward and cost-
efficient kiln type is mainly ap-
plied for output rates up to 400
tons of burnt lime or dolomite
per day.
As from 1966, Maerz has builtroughly 200 rectangular kilns
worldwide operating with gas-
eous, liquid and pulverised solid
fuels.
Circular PFR Kiln
For larger capacities, e.g. from
300 to 800 tons per day, kilns
of circular cross section are rec-
ommended. These kilns feature
circular ring channels collecting
the combustion gases before
they enter the non-burning shaft
via the cross-over channel. Thegases exit the burning shaft and
enter the non-burning shaft ra-
dially around the complete shaft
perimeter, thereby guaranteeing
an even heat distribution.
A bucket positioned vertically
above each shaft is used for
charging raw stone into the
kiln shafts. Stone distribution
is further improved by rotat-
ing the bucket during chargingfrom conveyor belts or vibrat-
ing feeders. The circular shaft
design facilitates uniform stone
and fuel distribution during
charging, as well as calcination
throughout the complete shaft
cross section.
Since 1966, more than 200 cir-
cular Maerz Kilns operating
with gaseous, liquid and pulver-
ised solid fuels, or a combinationof these, have been built world-
wide.
Finelime Kiln
Typical stone sizes processed
in conventional vertical shaft
kilns are larger than 30 mm.
Stone sizes of 6 to 30 mm can
be calcined in rotary kilns, but
with lower thermal efficiency. To
solve this shortcoming, Maerz
has developed a special type ofPFR Kiln the Finelime Kiln.
While maintaining the unique
features of PFR Kiln principles,
i.e. the parallel flow of material
and combustion gases in the
burning zone and the regenera-
tive preheating of combustion
air, the Finelime Kiln is able to
burn limestone sized between
approx. 15 and 40 mm at ther-
mal efficiencies superior to con-ventional PFR Kilns.
Since 1989 the year of its
introduction Maerz has built
approx. 35 Finelime Kilns world-
wide.
2 3 4
Large photo
Rectangular PFR Kiln.
Fig. 1 Circular PFR Kiln.
Fig. 2 Finelime Kiln.
Fig. 3 Startup burner.
Fig. 4 Refractory lining
work.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
10/15
1 2 3
Fig. 1 Pusher of t he Preheater.
Fig. 2 View into a Rotary Kiln.
Fig. 3 Preheater Rotary Kiln.
Preheater Rotary Kiln
Preheater Rotary Kilns are the preferred
technology for the burning of limestone and
dolomite if the following conditions apply:
high production capacity, preferably
greater than 1,000 tpd
small stone feed size, e.g. 15 to 40 mm
maximum fuel flexibility
production of low sulphur lime (e.g. for
the steel industry) despite the usage of
cheap, high sulphur fuels.
The energetic efficiency of a rotary kiln is
highly enhanced by a shaft preheater that
uses the kiln off-gases to preheat and par-
tially calcine the limestone.
The modular preheater design most effec-
tively combines heat transfer with optimal
accessibility for maintenance during opera-
tion.
Our technology of preheater rotary kilns is
based on the joint know-how of Polysius
and Maerz.
Polysius contributes its broad knowledge of
rotary kilns and its R&D capabilities while
Maerz contributes profound process knowl-edge of lime burning such as gas flow pat-
terns in bulky material beds.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
11/15
Rotary Kilns
4
Large photo New-Generation
Lime Shaft Preheater.
Fig. 4 The Sulphur Bypass System.
Sulphur Bypass System
Todays steel industry has a growing de-
mand for lime with minimal sulphur con-
tent.
Furthermore, the sharp increase in fuel
costs has created the necessity of looking
for cheaper fuel sources in order to limit
operating costs. Unfortunately, the usage ofcheaper fuels often means an increased in-
put of sulphur and other impurities into the
kiln system.
A special sulphur bypass system was
developed by Polysius to allow the firing of
high sulphur fuels for the production of low
sulphur lime in rotary kilns being equipped
with a shaft preheater.
In this novel system, the countercurrent
streams of material and kiln exhaust gasesare separated between preheater and rotary
kiln. The material is subject to a hot screen-
ing and classifying process.
The sulphur bypass system provides a very
effective solution to produce low sulphur
quicklime even when using highly contami-
nated fuels.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
12/15
1 2
Suspension Calciner
The POLCAL process was developed by
Polysius based on their extensive experi-
ence in the field of thermal treatment of bulk
materials acquired over many decades. It is
especially suitable for treating fine-grained
limestone and dolomite.
Materials within a grain size range of 0.03 to2 mm can be processed in this gas suspen-
sion process.
POLCAL systems have several vertically
arranged cyclone stages and a reactor for
thermal treatment of the raw materials as
well as one or several cooling cyclones to
cool the treated product. The individual
cyclone stages are interconnected by gas
ducts.
With production capacities ranging between300 and 1,200 tpd of burnt product, liquid,
gaseous and to a certain extent solid
fuels are applicable. The fuel is supplied
via several injectors arranged around the
reactor.
By varying the temperature and/or resi-
dence time in a conditioning drum installed
downstream the reaction chamber, the de-
gree of reactivity of the burnt material can
readily be adjusted to meet customer re-
quirements.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
13/15
Shaft Kilns Suspension Calciners
543
Large photo Single Shaft Kiln.
Fig. 1 Suspension Calciner.
Fig. 2 Cyclone of the Suspension Calciner.
Fig. 3 Detail of an Annular Shaft Kiln.
Fig. 4 Annular Shaft Kiln.
Fig. 5 Oil Burner of an Annular Shaft Kiln.
Annular Shaft Kiln
The Annular Shaft Kiln is characterised byits annular shaped shaft cross section lo-
cated between an outer and inner refractory
lined cylindrical steel shell.
The main feature of this kiln type is the
continuous stream of exhaust gases with a
high CO2-content, ranging between 26 and
32 %, depending on the type of fuel used.
Furthermore, the kiln allows the adjustment
of the reactivity of the quicklime produced
from soft to medium burnt. These charac-
teristics have made the Annular Shaft Kiln
the preferred choice for PCC and soda pro-
duction.
A wide range of fuels can be applied on this
kiln with production ranging between 200
and 600 tons per day.
Single Shaft Kiln
Special applications of lime, e.g. in the pro-duction of sandlime bricks and aerated con-
crete bricks or blocks, require hard burnt,
low reactivity quicklime. The RCE designed
single shaft lime kiln satisfies this require-
ment.
Based on the design of the RCE High Tem-
perature Kiln, mainly used in the refractory
materials industry for sintering magnesite,
dolomite and alumina, and in response to
market requirements, a high efficiency sin-
gle shaft kiln for the calcination of limestone,
dolomite and magnesite was subsequently
designed and patented. The main features
of this novel single shaft kiln type are:
the use of cooled, retractable side
burners
a wide range of product reactivity due
to the easy adjustability of operating
temperatures and
the high specific output per shaft
cross section.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
14/15
Services
Research and Development
Excellent technological competence is the key
to winning over and retaining customers as well
as to exploiting growth potential in existing and
new markets. Increasing the size of production
units and improving the operating economy
of production plants are main development
priorities.
Maerz makes use of the Polysius Research
Centre. With its modern equipment, this is one
of the leading institutions for technological
development in the mineral industry.
Customer Services
Maerz can assist their customers in many
different ways and offers the following services:
Project feasibility studies
Engineering services
Supply of key equipment for lime, dolomite
and magnesite kiln plants
Turn-key erection of complete kiln plants
Supervision services for erection, commis-
sioning and operation of kiln plants
Spare parts supply
Technical audits on kiln plants in operation
Training of operating and maintenance
personnel
After sales services including consulting for
operating and maintenance problems
Elaboration of modernisation proposals.
-
7/28/2019 Maerz Ofenbau Lime Burning Technology 2008 En
15/15
The World Leader in Lime Kilns
References
About 500 new kilns for the lime and dolomite in-dustry have been built since 1950 in some 60 coun-
tries by Maerz, Polysius and RCE.
Since their introduction in the late 1950s, the Maerz
PFR Kilns have become standard equipment in the
lime and dolomite industry. Their superior thermal
efficiency, paired with the flexibility of being able to
apply virtually all types of fuel and raw materials,
has made them an excellent choice whenever the
installation of new calcining equipment is an issue.
For special applications, such as production capacities of more
than 1000 tons per day, the requirement to burn powdery raw
material or to produce low reactivity lime, a continuous off-gas
flow from the kiln with high CO2-content and the production of
low sulphur lime, rotary kilns, single shaft kilns, annular shaft
kilns and suspension calciners complement Maerzs product