Document No.
AK685_971.01
Revision
0
Revision Date / saved on 06 January 2014
INSTRUCTION MANUAL
IM
BOOK-1
GENERAL INSTRUCTION & OPERATION
AK685 – CALQUIPA S.A.C.
Callalli, Peru
Table of Contents
1
BASIC INFORMATION
9
1.1 About this instruction manual 9
1.2 Terminology 9
1.3 Reference material 9
1.4 Explanation of signs and symbols 10
1.4.1 Signs and symbols used in the manual 10
1.4.2 Safety labels and signs on plant equipment 10
1.5 Liability and warranty 16
1.6 Copyright protection 16
1.7 Transport, Packaging and Storage 17
1.7.1 Safety notes 17 1.7.2 Transport inspection 18 1.7.3 Packaging 18 1.8 Spare parts 19 1.9 Storage 19 1.10 Disassembly 20 1.11 Waste disposal 20
2
SAFETY
21
2.1 General 212.2 Responsibility of the plant operator 22
2.3 Intended use 23
2.4 Workers' safety 23
2.5 Personal safety equipment (PSE) 24
2.6 Possible dangers at the plant 25
2.7 Emergency process stop 28
2.7.1 Staff and kiln protection 28
2.7.2 Emergency process stop system 28
2.7.3 Emergency stop switch reset 29
2.8 Operating personnel 30
2.9 Conduct in dangerous situations and in case of accidents 30
2.10 Danger areas 32
3
TECHNOLOGICAL PRINCIPLE
37
3.1 Useful literature 37
3.2 Calcination of limestone and dolomite 37
3.2.1 Limestone 37
3.2.2 Formation of limestone 37
3.2.3 Mineralogical composition 37
3.2.4 Impurities 38
3.2.5 Mineral structure and grain size 39
3.2.6 Porosity and density 39
3.2.7 Bulk density and particle size 40
3.2.8 Thermal dissociation of carbonate 40
3.2.9 Mechanical strength and abrasion resistance 41
3.2.10 Data and properties of limestone 42
3.3 Calcination of limestone 43
3.3.1 Thermal decomposition of calcium carbonate 43
3.3.2 Physical-chemical phenomena during calcination 44
3.3.3 Reactivity of quicklime 47
3.3.4 Influence of feed size on retention time 48
3.3.5 Lime to limestone factor 50
3.4 Fuel 51
3.4.1 Definition of calorific values 52
3.4.2 Combustion air volume (v’ol) 52
3.4.3 Wobbe index 52
3.4.4 Heat flow 53
3.4.5 Fuel data 53
4
DESIGN AND FUNCTIONING (TYPE FS)
55
4.1 Design 56
4.2 Design 58
4.2.1 Parallel-flow firing system 58
4.2.2 Preheating the combustion air 58
4.2.3 Two-shaft kiln 58 4.2.4 Burner lances 59 4.2.5 Reversing devices 59 4.2.6 Charging device 60 4.2.7 Discharge device 61 4.2.8 Hydraulic system 62
4.4.3 Heat and mass flow 67
4.4.4 Temperature profile 68
4.5 Kiln control system 69
4.6 Electric switchboard 70
4.6.1 Main components 70
4.6.2 Safety information 73
4.6.3 Additional documents 73
4.7 Local operation panel 74
4.7.1 Main components 74
4.8 Instrumentation 76
4.8.1 General description 76
4.8.2 Arrangement of instruments 76
4.8.3 Wiring diagrams 76
4.8.4 Purpose of the most important measuring instruments 76
5
COMMISSIONING
81
5.1 General information / Definition 81
5.2 Requirements for cold commissioning 82
5.2.1 Consumables 82
5.2.2 Lubricating points 82
5.2.3 Shaft construction 83
5.2.4 Refractory 85
5.2.5 Kiln systems 85
5.2.6 Electrical installations / instrumentation 85
5.2.7 Firing system 86
5.2.8 Waste gas filter 86
5.3 Cold commissioning 87
5.3.1 Suspended cylinder (if existent) 87
5.3.2 Components 87
5.3.3 Software 87
5.3.4 Integration test 87
5.3.5 Charging the kiln with limestone: 88
5.4 Hot commissioning 89
5.4.1 Process adjustments 89
6
OPERATION
91
6.1 General 91 6.2 Safety 91 6.3 Visualization system 95 6.3.1 Screen layout 96 6.3.2 Color definitions 99 6.3.3 User level 101 6.3.5 Parameter tables 102 6.3.6 Process pictures 105 6.3.7 Alarms 120 6.3.8 Tuning screens 124 6.3.9 Trend messages 1256.4 Theoretical Basis of Lime Kiln Operation 127
6.4.1 Modes of operation 127
6.4.2 Filling mode 127
6.4.3 Heating mode 128
6.4.4 Production mode “charging during reversal time” 128
6.4.5 Production mode “charging during burning time” 129
6.5 Reversal and charging sequences 130
6.5.1 Production mode “charging during the reversal time” 130
6.5.2 Production mode “Charging during burning time” 133
6.6 Calculation of the process parameters (sample) 135
6.7 Description of the Operational Procedures 137
6.7.1 Limestone charging 137
6.7.3 Filling the kiln 138
6.7.4 Start-up process 139
6.7.5 Production operation 145
6.8 Preconditions for production operation 147
6.8.1 Basic recommendations 147
6.8.2 Key factors for the lime burning process in the lime kiln 147
6.8.3 Adjustment of the cooling air 147
6.8.4 Setting the Heat Input 148
6.8.5 Adjusting the Air Excess Factor 148
6.8.6 Setting the Fuel Parameters 150
6.8.7 Setting the Reversal Time 150
6.10 Fine Lime Charging 157
6.10.1 Effect on lime quality 157
6.10.2 Distribution system 158
6.10.3 Kiln charging method 158
7
MALFUNCTION
165
7.1 Safety 165
7.2 Steps to be taken in the event of a failure 166
7.3 Alarm systems 167
7.3.1 Failure of machine components 168
7.3.2 Failure of the machine's control system 168
7.4 Restart after failure 169
7.5 Steps for troubleshooting 169
8
MAINTENANCE
175
8.1 In general 175 8.2 Safety 176 8.3 Lubricating instruction 176 8.4 Maintenance schedule 177 8.4.1 Check list 177 8.5 After maintenance 1889
INDEX
189
1
Basic information
1.1
About this instruction manual
This instruction manual describes the design, start-up, operation, and maintenance of the kiln plant.
Compliance with all safety notes and directives specified is a precondition for safe working with and proper handling of the plant. Furthermore, all specific local accident prevention regulations and general safety rules must be strictly observed.
This instruction manual is an essential part of the product. At least one copy must be kept in the kiln plant control room at all times. It must be accessible to the operating, maintenance, and cleaning personnel.
The illustrations in this manual are meant for better understanding and are not
necessarily true to scale. The contents of the manual may vary from the version of the actual plant. For more precise and detailed information, the respective drawings and diagrams must be kept on hand.
In addition, the individual documents and instructions related to the installed
components and equipment will apply. Strictly observe the notes contained therein - especially safety notes.
1.2
Terminology
The terms "plant" or "kiln” used in this manual refer to the Maerz® Parallel Flow Regenerative Shaft Kilns for Limestone and Dolomite.
Some views in this manual, the PI diagrams, as well as other documents and drawings use identifiers and tag numbers to refer to a specific component installed.
The term "operating company" is used to relate to the "plant owner". The term "operator" however is used strictly to refer to the "operating person" to the "kiln attendant".
1.3
Reference material
Unless otherwise specified, the individual components of the kiln plant are purchased from other manufacturers than MAERZ. All components used in the plant have been tested and subjected to risk assessment by the respective manufacturers. The
manufacturers of these components have confirmed the compliance of the equipment with applicable European and national regulations.
The declarations of conformity of the manufacturers as well as operating, maintenance, and repair instructions for the various plant components are integral parts of the overall documentation. The directives on safety, setup and installation, operation, preventive maintenance, disassembly and disposal of the components included in the
1.4
Explanation of signs and symbols
1.4.1 Signs and symbols used in the manual
Important safety and technical notes in this operating manual are marked with symbols. These notes must be adhered to in order to avoid accidents, personal injuries and damage to property.
WARNING
This symbol stands for dangers that can lead to adverse effects on health, injuries, permanent physical damage, or death.
Absolutely adhere to the notes regarding safety at work, and be particularly careful in this respect.
DANGER OF ELECTRIC CURRENT
This symbol draws attention to dangerous situations involving electrical currents. There is the risk of serious injuries or death if the safety notes are not complied with. Any work is to be carried out by qualified electricians only.
CAUTION
This symbol stands for dangers that can lead to adverse effects on health, injuries, or physical damage.
NOTICE
This symbol indicates notes, which if not complied with can lead to damage, malfunctions and/or breakdown of the plant.
INFORMATION
This symbol highlights tips and information to be observed for efficient and trouble-free operation of the plant.
1.4.2 Safety labels and signs on plant equipment
The following table lists all mandatory signs, prohibition, warning, fire, and rescue labels attached to plant equipment.
WARNING
Prohibition labels
Prohibition labels are white and contain a crossed-out black symbol surrounded by a red circle.
Smoking prohibited
Risk of fire caused by combustible or explosive solid, liquid, or gaseous materials.
Do not touch, live housing
Danger caused by electric shock.
Fire, open light, and smoking prohibited
Do not introduce or generate any kind of ignition source, such as: - open flames and hot gases (e.g. burning candles, matches, welding
beads, welding sparks, or gleaming charcoal)
- warm / hot surfaces (e.g. radiators, hot plates, light bulbs, crankcases, exhaust systems)
- frictional heat (e.g. hot bearings)
- mechanically generated sparks (e.g. rock, concrete, metal sparks produced by grinding, abrasive cutting, or hammer strokes)
Fire extinguishing with water prohibited
Water may prove to be unsuitable for extinguishing fires and may further increase the danger caused by fire
Authorized personnel only
Access to the danger area is limited to authorized persons (personnel authorized by the plant operator to enter the danger area).
Do not touch
Containers or parts may become damaged when touched.
Prohibition
Mandatory signs
Mandatory signs are blue and contain a white symbol.
Wear safety goggles
Wear hearing protection
Wear safety shoes
Wear safety clothing
Wear safety harness
Wear safety hat
Wear breathing mask
Wear safety gloves
Warning signs
Warning signs are yellow and contain a black symbol.
Warning of inflammable materials
Warning of a danger area
Danger of tripping and falling
Warning of gas bottles
Warning of explosive atmosphere
Danger of crushing
Warning of automatic start
Warning of hand injuries
Warning of dangerous voltage
Warning of hot surface
Warning of toxic materials
Fire labels
Fire labels are red and contain a white symbol.
Fire hose
Fire fighting equipment
Directional arrow (only to be used in combination with another fire label)
Ladder
Fire alarm box
Rescue signs
Rescue signs are green and contain a white symbol.
First aid
Stretcher
Eye rinsing facility
Emergency phone
Arrow pointing to first-aid facilities (only to be used in combination with another first aid symbol)
Rescue paths and emergency exits
Emergency path
Emergency path
Emergency exit
Emergency exit
1.5
Liability and warranty
All specifications and information used in this instruction manual are provided in consideration of all applicable regulations, the current state of the art, and our long-standing expertise and experience.
For special designs and order-specific configurations or, in the event of technical changes, the actual scope of supply may deviate from the described specifications and provided drawings and sketches. Please contact MAERZ if you have any questions.
INFORMATION
Carefully read this instruction manual before starting any work at or with the plant and, in particular, before first-time operation. MAERZ cannot assume any liability for damage or failures caused by the non-observance of the instructions provided in this instruction manual.
We reserve the right to introduce technical modifications to the product with the intention to improve and further develop the useful properties of the plant.
Components, such as tools that are subject to normal wear and tear during standard operation of the kiln, as well as commodities, such as greases, oils, or detergents, are excluded from the warranty.
The obligations agreed upon in the supply contract, the terms and conditions, as well as the manufacturer’s terms of delivery, and all legal requirements applicable at the time of conclusion of the contract remain in full effect.
1.6
Copyright protection
The instruction manual is to be treated confidentially. It is exclusively intended for persons working on and with the plant. Leaving the instruction manual to a third party without written approval of the manufacturer is not permitted. Please contact MAERZ in case of any questions.
INFORMATION
The contents, text, drawings, illustrations, and other presentations contained in this manual are protected by copyright and subject to additional commercial property rights. Any misuse is punishable by law. Copying by use of any type and format – even in excerpts – as well as the use and/or publication of the contents is not permitted without written approval by MAERZ. Infringements are liable to damage compensation. Additional claims are reserved.
1.7
Transport, Packaging and Storage
INFORMATIONThe installation and initial operation of the kiln must only be performed by employees of the manufacturer or by persons authorized by him to perform such tasks.
However, the installation and further use of the kiln may require that employees of the operator be entrusted with the task of handling packing units. When performing such tasks, make sure to observe the information provided below:
1.7.1 Safety notes
WARNING Danger of injury!
There is a danger of injury due to falling parts when lifting, swinging, and lowering materials. The machine can be damaged or destroyed by improper transport.
For this reason, basically observe the following safety notes:
Always use appropriate lifting tackle and slinging devices with sufficient carrying capacity.
Only secure the machine on the fastening points provided; do not fasten at projecting machine parts or eyelets of attached components. Make sure the slinging device is secure!
Ropes and belts must be equipped with safety hooks. Do not use torn or worn ropes. Do not lay ropes and belts on sharp edges and corners, do not knot or twist. Pay attention to the centre of gravity of the equipment when fastening the tackle.
Never lift, swing, or lower loads over people.
Always move the equipment with utmost care and attention.
WARNING Risk of death!
Suspended loads can fall down and lead to severe injuries. Do not stand or pass under suspended loads when transporting with lifting tackle!
1.7.2 Transport inspection
Check delivered goods immediately on receipt for completeness and transport damage.
Do not accept the delivery or only accept under reserve if there is externally recognizable transport damage. Note the scope of damage on the transport documents/delivery note of the carrier. Start complaints procedure.
Register complaint about hidden deficiencies as soon as they are discovered, as indemnity claims can only be asserted within the applicable time for complaints.
1.7.3 Packaging
INFORMATION
Keep environmental protection in mind!
Packaging materials are valuable raw materials and can continue to be used in many cases, or can be suitably reconditioned and recycled. If there is no return agreement for packaging, sort materials according to type and size, and route them for further use or recycling.
NOTICE
Always dispose of packaging materials in an environmentally friendly manner and in accordance with the applicable, local disposal guidelines. If necessary, order a recycling company.
1.8
Spare parts
Use only spare parts authorized by the manufacturer of the relevant equipment.
NOTICE
Wrong or faulty spare parts can lead to damage, malfunctions, or total failure of the plant.
All claims for warranty, service, damage compensation, as well as liability claims against the manufacturer or his representatives, dealers and agents become void when unauthorized spare parts are used.
1.9
Storage
Keep packed goods in this state until installation, and store such items as specified by the externally attached installation and storage information.
Store packing units only under the following conditions: - Do not keep in the open air.
- Store in dry and dust-free environment. - Do not subject to aggressive media. - Protect against direct sunlight. - Avoid mechanical vibration. - Storage temperature: 15 to 25°C - Relative humidity: max. 60%
- For longer periods of storage (>3 months), check the general condition of all parts and the packaging at regular intervals. If necessary touch up or renew conservation.
INFORMATION
Refractory magnesite stones may absorb moisture from the surrounding air and chemically react with this moisture. If the stones are stored for more than 3 months, this reaction may cause damage to the magnesite stones, even if the storage information provided above is observed. It is therefore recommended to store impregnated stones only.
1.10
Disassembly
For disassembly, the plant must be cleaned and dismantled in strict compliance with the applicable industrial safety regulations and accident prevention instructions.
WARNING Danger of injury!
Stored residual energies, sharp edged components, pointed corners and edges on and inside the plant or on the required tools can cause severe injuries. Any disassembly work on the plant is therefore to be carried out by skilled personnel only.
Before starting disassembly:
- Shut down the plant and secure it against restarting.
- Physically disconnect the complete energy supply from the plant, and properly discharge stored residual energies.
- Dispose of fuels and lubricants as well as residual processing materials in an environmentally acceptable manner.
1.11
Waste disposal
If no agreement concerning retrieval or waste disposal has been made, disassembled components must be passed on for recycling after correct dismantling:
- Metal material residues must be scrapped
- Plastic elements must be forwarded for recycling of plastics - Other components must be sorted by material properties
NOTICE
Electric scrap, electronic components, lubricants and other auxiliary materials must be treated as hazardous waste and must only be disposed of by specially approved waste disposal companies!
Remove operating materials like greases, oils, preservation agents and detergents from the plant, separate by type, and dispose of in an environmentally responsible manner. In this process, use collection and storage containers that are suitable and approved for the respective operating materials.
2
Safety
This section provides an overview of all important safety aspects for optimal protection of personnel against any danger and ensures safe and trouble-free operation of the plant.
In addition, specific notes on safety to avert danger are provided and marked with symbols in the individual chapters.
All pictograms, signs, and labels on the plant are to be strictly observed and kept legible at all times.
2.1
General
The plant has been manufactured according to generally accepted engineering standards applicable at the time of its development, and production and is considered operationally safe. However, the plant may entail dangers, if not used properly or according to its intended purpose by professionally trained personnel. Therefore, any person commissioned to work on or with the plant must have read and understood the “Instruction Manual” before commencing work. It is recommended that the company operating the plant should request concrete proof that the personnel have taken full knowledge of the instruction manual's contents.
Modifications of any type as well as attachments or changes to the plant without written authorization by Maerz are prohibited.
All safety, warning and operating notes affixed to the plant or any of its components must always be kept legible. Damaged signs or stickers are to be replaced without delay.
2.2
Responsibility of the plant operator
- Store the instruction manual in the direct vicinity of the kiln and keep it readily available for the erection, operating, maintenance and cleaning personnel at all times.
- Do not operate the lime kiln plant unless it is in proper technical condition and operationally safe.
- Keep safety devices accessible at all times and check proper functioning on a regular basis.
All information regarding safety at work refers to the guidelines issued by the European Union applicable at the time the kiln was manufactured. The plant operator is
responsible for ensuring that while the kiln is in operation, the specified work safety regulations comply with the latest updates of all applicable current and future regulations. Outside the territory of the European Union, the plant operator must comply with all work safety laws as well as with all regional laws and regulations applicable at the place of operation.
In addition to the information regarding safety at work specified in this instruction manual, the plant operator must also follow and comply with all regulations regarding general safety, accident prevention, and protection of the environment applicable at the place of operation.
The plant operator and any personnel authorized by him are responsible for the trouble-free operation of the kiln as well as for assigning unambiguous responsibilities with regard to the installation, operation, maintenance and cleaning of the kiln.
The information provided in this instruction manual must be followed in full and without limitation.
The plant operator has the obligation to attach signs limiting access to the kiln to trained and authorized personnel. In accordance with this instruction manual, the plant operator must also attach warning signs or plates at all access points to the kiln, informing of the dangers involved with working at and with the kiln.
The plant operator must provide a sufficient number of fire-fighting equipment inside the kiln area.
The plant operator must equip the personnel working at the kiln with sufficient and suitable first-aid equipment. The personnel must be trained in handling first-aid equipment.
The plant operator must familiarize his personnel with the recommendations provided by the "International Chemical Safety Cards" for handling calcium oxide, fuels, and other dangerous materials, and the personnel must adhere to these recommendations.
2.3
Intended use
Safety and reliability of the equipment is only guaranteed if it used as intended in accordance with the information provided in the instruction manual.
The intended use of the lime kiln is the production of quicklime in accordance with specifications. The kiln may only be operated with the fuel specified in the chapter Technical Data.
NOTICE
Any use of the system, beyond or different from the intended one, is prohibited and considered not as intended.
Claims of any kind against the manufacturer and/or his authorized representatives resulting from damage caused by use of the kiln not as intended are excluded.
The customer/plant operator is solely liable for any damage caused by a use other than intended.
Intended use also includes correct adherence to erection, operating, maintenance and cleaning instructions.
2.4
Workers' safety
Follow the safety instructions to prevent persons and property from becoming injured or damaged during the operation of the kiln. Failure to observe this information represents a serious risk of injury to the personnel and may cause damage to or the destruction of the kiln, especially if the kiln is operated in an explosive environment.
The manufacturer or his agents shall not be liable for any defects caused by failure to observe these safety instructions.
2.5
Personal safety equipment (PSE)
Operation, maintenance, troubleshooting/fault elimination/repairs and cleaning work require wearing a personal protective outfit.
The plant operator must make sure that all persons involved in work with or at the kiln have the required protective equipment at their disposal and wear it for work.
Operating persons and expert personnel occupied with work at the kiln are obliged to wear their personal safety equipment before and during work.
In principle, the following items are to be worn when working on or with the
plant:
Tight-fitting work clothing
minimal tear strength, no wide sleeves, no rings or other jewellery, etc.
Safety goggles
to protect the eyes against liquids and particles flying about
Face screen
to protect the eyes and the face against flames, sparks, or embers as well as hot particles or emissions
Breathing mask
to protect against inhaling particles or emissions
Safety shoes
to protect against heavy parts being dropped, and slipping on slippery surfaces
Safety gloves
to protect the skin against friction, excoriation, pricking and deeper injuries on the hands and against contact with health affecting substances
Safety helmet
to protect against objects and materials falling down or flying around
Ear defenders
2.6
Possible dangers at the plant
The plant has been subjected to risk assessment. The resulting construction and design of the plant correspond to the state of the art. Nonetheless, some risks remain.
The plant works with high pressure hydraulic oil
Any damage to the hydraulic system may result in a strong stream of liquid.
WARNING Risk of injury
Danger caused by liquids spurting out under high pressure. Wear personal safety equipment when working at the kiln.
The plant works with electrical voltage
DANGER OF ELECTRIC CURRENT
Electrical power can cause severe injuries. There is imminent danger to life and health caused by electrical current if the insulation or individual
components are damaged.
- Disconnect the main switch, and secure against switching on again before maintenance, cleaning, or repair work.
- Switch off the power supply before starting work in the electrical system and make sure that the system is dead.
- Do not remove any safety features or do not modify such installations in a way that would affect their function.
The plant works with movable components
WARNING Risk of injury
Rotating and/or linearly moving components can cause severe injuries. Do not reach with your hands into or touch moving parts during operation. Do not open covers and maintenance flaps.
- Allow components to run out after switching off the plant.
- Before starting cleaning, repair, maintenance, or any other work, wait until all components have stopped, switch off the plant and reliably secure against being switched on again.
- After cleaning, repair, maintenance, or any other work, close and lock all covers, maintenance flaps, etc.
The plant comprises pneumatic components WARNING
Risk of injury
Pneumatic energies can cause severe injuries. In case of damage to individual components, operating media can escape under high pressure and cause injuries and material damage.
Therefore:
- Always relieve the system from any pressure before starting work on pneumatic equipment.
- Do not remove or inhibit any safety facilities.
- Do not adjust pressure levels beyond the limits specified in the instruction manual.
The plant has sharp edges and corners
CAUTION Risk of injury
Sharp-edged housing parts and sharp corners can cause grazes on the skin. Wear protective gloves when working at the plant.
The kiln works with powerful fans
WARNING Risk of injury
The fast-running impeller installed inside the blower may cause serious injuries such as cutting or severing of body parts. Therefore:
- Do not operate the blowers, unless the impeller cage, protection caps, and maintenance covers are closed.
- Prior to performing any work at the blower, shut down the unit, secure it against re-starting, and keep it closed until all running components have come to a complete stop.
- Do not open the impeller cage, protection caps, and maintenance covers until the impeller has come to a complete stop. Afterwards, secure all moving components against uncontrolled movements by appropriate means such as clamping.
Operation of the kiln may release highly flammable materials WARNING
Risk of injury
Highly flammable materials, liquids, and/or gases might catch fire and cause serious injuries.
- Smoking, handling open light, fire, and/or sources of ignition of all kinds in the vicinity of the kiln and within a distance of 5 m or less is strictly prohibited.
- Locate any suspicious materials, liquids and gases, and notify your superior without delay.
- Stop working immediately. Leave the danger zone, until the all-clear is given.
The kiln works with CaO (quicklime)
WARNING
Risk of chemical burns caused by CaO
There is a risk of sustaining chemical burns in places labeled accordingly. Any person working inside these areas must proceed with great caution when handling caustic materials.
In addition to the danger of damaging one's clothing, there is also the risk of burning one's eyes, skin and possibly one's mucous membranes. Burning one’s eyes may cause irreparable visual impairment.
When handling caustic materials, wear personal safety equipment as required by the Chemical Safety Datasheet.
The plant operator must keep available at all times rinsing liquids for cleaning eyes.
When burnt lime is mixed with water it reacts by generating a lot of heat and thus becoming leach.
The kiln works under high pressure
WARNING Risk of injury
The kiln is operated under pressure. Flames or hot gases may spurt out when any access or inspection doors are opened. The high pressure inside the kiln may cause the kiln doors to fly open with great force.
Do not open the kiln doors until the pressure difference between the inside and the outside of the kiln is zero.
2.7
Emergency process stop
2.7.1 Staff and kiln protection
To protect the kiln and the staff working at it, the kiln is equipped with an emergency process stop system comprising emergency process stop buttons and safety locks. The emergency process stop system is a category 1 system with one-channel disconnection. The emergency process stop and safety features of the kiln control system are fully integrated into this emergency system, which is equipped with its own controller.
The operating, cleaning, service and maintenance personnel must be instructed about the location and the functionality of the safety devices on a regular basis. Proof of such instruction must be provided upon request.
2.7.2 Emergency process stop system
The entire emergency process stop system consists of an emergency process stop sequence. This means that as soon as the emergency process stop button has been pushed or the safety lock has been engaged, the entire kiln will immediately be set to a safe operating mode.
The safe operating mode is either achieved by immediately interrupting the power supply to the drives, by shutting down the drives until they have come to a complete stop, or by moving them into a safe position until the power is cut off with a delay.
For kilns with suspended cylinders
NOTICE
The operating process requires the cooling system of the suspended cylinders to continue to run, even if the emergency process stop function has been activated.
Do not turn off the cooling system of the suspended cylinders as otherwise the suspended cylinders, and consequently the kiln, may become heavily damaged.
In the event of a failure of the cooling system of the suspended cylinders, activate the emergency cooling system without delay.
If the operation of the cooling system for the suspended cylinders poses a danger to the kiln operating person, immediately shut down the kiln by pushing the emergency process stop button. However, make sure to manually activate the emergency cooling system directly after shutting down the kiln.
2.7.3 Emergency stop switch reset WARNING
Risk of injury
Any uncontrolled re-starting of the kiln may cause serious personal damage.
Prior to re-starting the kiln or any of its components, check whether the cause of the emergency process stop has been eliminated, and make sure that all safety devices have been re-installed and are properly functioning.
After having successfully reset the triggered contact (e.g. by rotating and unlocking the emergency process stop button), proceed by acknowledging the emergency process stop.
2.8
Operating personnel
The kiln may only be operated and maintained by authorized, qualified and instructed personnel. These personnel must have received special instructions regarding any dangers that may occur.
Instructed personnel have been taught about the tasks entrusted to them and the possible dangers resulting from improper actions, and if necessary, have been instructed practically in this respect. Moreover, the personnel have been informed of the required protective features and protective measures.
Qualified personnel are persons who can assess the work entrusted to them and recognize potential dangers based on their special training, expertise, and experience as well as on their knowledge of appropriate conditions.
If staff members do not have the necessary knowledge, they are to be trained accordingly.
Responsibilities for operation and maintenance must be clearly determined and adhered to so that there is no unclear division of competence with regard to safety. The kiln may only be operated and maintained by persons who can be expected to carry out their work reliably. This means that any mode of operation that affects the safety of persons, of the environment or the kiln is to be avoided.
Persons who are under the influence of drugs, alcohol, or medication that affects their responsiveness may under no circumstances carry out work on or with the kiln plant. When selecting personnel, attention must be paid to the regulations protecting young workers in the relevant country regarding the minimum age and, if necessary, to the job-related instructions based on this.
The operating company must ensure fully that only authorized persons work on or with the kiln plant.
All non-authorized persons, such as visitors etc., must at any time be kept at an appropriate safety distance to the kiln and any of its ancillary equipment.
The operating personnel are obliged to immediately report to the plant operator or his representative any safety-relevant incidents in kiln operation.
2.9
Conduct in dangerous situations and in case of accidents
Always be prepared for accidents or fire.
In a dangerous situation or in case of an accident, stop the kiln by immediately activating the EMERGENCY PROCESS STOP SWITCH.
The EMERGENCY PROCESS STOP SWITCH may only be operated in emergency situations and must not be used for normal kiln stops.
Item Description
1 Reversal flap (filter / direct chimney) 2 Reversal flap (combustion air / waste gas) 3 Shaft closing flap
4 Thermal radiation and heat on kiln shaft 5 Access doors and inspection openings to kiln 6 Lime belt conveyor
7 Lime vibrating feeder 8 Lime discharge hopper 9 Discharge flap
10 Discharge table
11 Air blast unit (not shown) 12 Poking hole
13 Emergency venting for suspended cylinder cooling system 14 Relief flap combustion air (not shown)
15 Stone distribution flap 16 Rotating bucket
17 Reversible belt conveyor 18 Limestone vibrating feeder
Additional danger areas (not shown)
Hydraulic unit and hydraulic system Blowers and ventilators
Limestone belt conveyor Waste gas filter
Item Description ~LAeq [dBA]
1 Chimney exit 80
2 Reversal flap 70
3 Relief flap combustion air (not shown) 105
4 Relief flap cooling air (not shown) 95
5 Lime vibrating feeder 90
6 Discharge flap and hopper 90
7 Discharge table 85
8 Emergency fan for suspended cylinder 100
9 Air blast unit (not shown) 95
10 Emergency venting suspended cylinder cooling system 100
11 Kiln charging 95
12 Rotating bucket 105
13 Limestone feeder 95
14 Stone hopper 105
Additional noisy areas (not shown)
Description ~LAeq [dBA]
Hydraulic unit 90
Blower house internal 110
Blower house external 75
Transport system for limestone and lime 105
3
Technological Principle
3.1
Useful literature
- Boynton, R.S., "Chemistry and Technology of Lime and Limestone" John Wiley &. Sons, 1980, ISBN 0-471-02771-5.
- Oates, J.A.H., "Lime and Limestone" Wiley-VCH, 1998, ISBN 3-527-29527-5
- European Commission, "Integrated Pollution Prevention and Control (IPPC)" - Reference Document on Best Available Techniques in the Cement and Lime Manufacturing Industries (adopted Dec 2001)
- Schiele, E., Berens L.W., "Kalk – Herstellung, Eigenschaften, Verwendung" (in German), Stahleisen m.b.H., 1972, ISBN 3-514-00115-4
3.2
Calcination of limestone and dolomite
3.2.1 Limestone
Limestone is found widely throughout the world and is an essential raw material for many industries.
3.2.2 Formation of limestone
Limestone is one of the most widely distributed sedimentary rocks throughout the world. Commercially used limestone is mainly of organic origin. Deposits were formed by the building-up of fossiliferous marine sediments in oceans consisting of shells and skeletons of plants and animals. Some of these sediments were deposited by natural chemical reaction. Calcium bicarbonate was produced by the extremely slow
dissolution of calcium carbonate fossils through the solvent action of carbon dioxide, which was subsequently re-precipitated in carbonate form. Layer by layer of these deposits form massive beds of limestone.
3.2.3 Mineralogical composition
Limestone and dolomite can be composed of the following four minerals, characterized by the following physical data:
Chemical formula Molecular weight Specific gravity [g/cm3] Hardness [Mohs Scale] Crystal system
Calcite CaCO3 100.1 2.71 3.0 rhombohedral
Aragonite CaCO3 100.1 2.94 3.5-4.0 orthorhombic
Dolomite CaMg(CO3)2 92.2 2.84 3.4-4.0 rhombohedral
Magnesite MgCO3 84.3 3.00 5.0-4.5 rhombohedral
Dolomite and calcite play the main role as industrial minerals.
- Pure limestone (calcite and aragonite) is 100% calcium carbonate.
- Pure dolomite contains 54.3% CaCO3 and 45.7% MgCO3 (30.4% CaO, 21.8% MgO,
INFORMATION
Limestone and dolomite used for industrial purposes include: - Pure calcite with 97–99% CaCO3
- Pure dolomite with 40–43% MgCO3 and 57–60% CaCO3
Impurities in these limestone and dolomite rocks are usually between 1 and 3%.
3.2.4 Impurities
Impurities in limestone are classified as homogeneous and heterogeneous.
Silica and alumina
- Homogeneous impurities such as clay, silt, sand, and other forms of silica like quartz are well dispersed throughout the formation.
- Heterogeneous impurities, which are found, for example, as siliceous pieces or nodules of sand, chert or flint are loosely embedded in the limestone.
Iron
- The third major impurity is homogeneously distributed after the limestone has started to form iron carbonate by chemically replacing calcium with iron. This frequently occurs in oolitic limestone.
- It is heterogeneously distributed as iron sulphide or iron oxide in minerals like pyrite, limonite, and hematite.
Phosphorous and sulphur
- They usually occur only in small quantities.
Manganese, copper, titanium
- These and further impurities are virtually negligible and considered as trace elements in the pure stone.
3.2.5 Mineral structure and grain size
Limestone is crystalline. The grain size (to be distinguished from particle size)
increases with the amount of re-crystallization that has occurred during the formation of the deposit.
The crystalline structure varies greatly in density and hardness.
Micro <4 × 10-6 m
Fine 4 – 50 × 10-6 m
Medium 50 – 250 × 10-6 m
Coarse >250 × 10-6 m (up to about 1000 × 10-6 m)
The particle shape depends partly on the microstructure of the grain, but also on the crushing characteristics of the crushing machine.
NOTE
Cubic or spherical shapes of limestone particles are usually preferred for lime kilns.
Avoid processing layered or flat limestone particles whenever possible.
3.2.6 Porosity and density
The porosity of limestone particles varies considerably depending on the degree of compaction and structure of the limestone. It is defined as the ratio of the void volume Vv and the total volume Vtot. The void volume Vv comprises both accessible and
inaccessible pores. The figure below illustrates different kinds of pores.
Fig. 3 Different kinds of pores (typical)
Item Description 1 solid pore 2 inaccessible pore 3 accessible pore
Density is defined as the ratio of mass m and volume V of a particular particle.
The solid or specific density (D) considers the volume of the pure solid without any void volume.
The apparent density (Ds) considers the volume of the solid with the inaccessible
space.
The apparent porosity (Ps) describes the accessible volume as the difference of that
part of the specific density minus the apparent density with the amount of inaccessible space.
100
1
D
D
P
s s Ps = Apparent porosity [%] Ds = Apparent density D = Specific densitySome data regarding apparent porosities and apparent densities of commonly used types of limestone is provided in the table below.
Industrial limestone shows a wide range of apparent porosities (0.1 to 40%) and densities (1.50 to 2.90 g/cm3) caused by the different forming conditions and levels of re-crystallization.
Apparent porosity [%] Apparent density [g/cm3] dried at 110 °C
Dense limestone 0.1 to 3.0 up to 2.7
Marble 0.1 to 2.0 2.7 to 2.8
Chalk 15 to >40 1.5 to 2.3
3.2.7 Bulk density and particle size
Bulk density is the mass per unit volume of a solid, including the voids in a bulk sample of the material.
Bulk density depends largely on the apparent density of the limestone, its particle size distribution, and on the particle shape.
Crushed, screened limestone with a size ratio of 2:1 generally has a bulk density of 1.3 to 1.6 g / cm3.
Crushed, unscreened limestone has a bulk density of 1.6 to 1.75 g / cm3.
3.2.8 Thermal dissociation of carbonate
Thermal dissociation is the most important characteristic of limestone.
All carbonate rocks dissociate at high temperatures, forming oxides and CO2 gas.
For example:
The dissociation temperature may be reduced by several hundred degrees due to higher amounts of impurities, such as SiO2, Al2O3, and Fe2O3 in the limestone. The
effect of SiO2 (silica) is shown in the following figure.
Fig. 4 p,t diagram of the CaO-SiO2 system (typical)
Curve Element Temperature range
1 CaCO3 + SiO2 400–590 °C
2 CaCO3 + 2CaO·SiO2 400–750 °C
3 CaCO3 650–890 °C
3.2.9 Mechanical strength and abrasion resistance
Pore volume and pore distribution give the limestone a specific structure, which results in different apparent densities. They have a direct influence on the mechanical
properties of the limestone.
Mechanical strength and abrasion resistance of the limestone must be sufficiently high to avoid breakage. Breakage of limestone particles during handling or passage through the kiln causes the generation of fine lime and compresses the stone packing in the kiln. The gas flow and heat transfer may thus be adversely affected causing
downgrading of the quality of the quicklime (also see Influence of feed size on the retention time in this chapter).
The compressive strength varies from 10 MPa for some types of marl and chalk to 200 MPa for some types of marble.
INFORMATION
The compressive strength of limestone to be burnt in a Maerz lime kiln should generally not be lower than 30 MPa.
3.2.10 Data and properties of limestone
The following table lists some fundamental data and properties of limestone.
Properties Data
Expansion coefficient 5 x 10-6 K-1 at 20°C. Total expansion of limestone during heating up from 20 to 800°C is approx. 2-2.5%.
Thermal conductivity Limestone at 130 °C
Dolomitic limestone at 123 °C
1.6341 W / mK 1.4246 W / mK
Integrated specific heat
CaCO3 at 100°C at 800°C CaO at 100°C at 800°C [kJ / Kg °C] 0.874 1.104 0.786 0.887 [kcal/kg °C] 0.209 0.264 0.188 0.212 Strength Compressive strength: Shear strength: Tensile strength: 10 – 200 MPa 5 – 20 MPa 2 – 7 MPa
Chemical properties Limestone and dolomite are unaffected by CO2-free water. Decomposition can only occur at very high temperatures or by reaction with strong acids.
3.3
Calcination of limestone
Carbonate rocks decompose at high temperatures releasing gaseous CO2 and convert
into calcium oxide and/or magnesium oxide. Depending on the process temperature, a range of products from soft-burnt to hard-burnt lime can be produced.
The Maerz lime kiln is designed to primarily produce soft-burnt lime. Therefore, this manual focuses on the production of soft-burnt lime obtained from high-purity limestone.
By appropriately adapting kiln design and operating mode, the Maerz lime kiln is also suitable for burning dolomite.
3.3.1 Thermal decomposition of calcium carbonate
The thermal decomposition of CaCO3 into CaO and CO2 is an endothermic reaction.
CaCO3 + heat = CaO + CO2
It starts at about 810°C with surface calcination and is completed at about 900°C at a partial CO2 pressure of 100 kPa.
3.3.2 Physical-chemical phenomena during calcination
During heating-up, the limestone passes several stages of physical-chemical and thermo-mechanical phenomena.
The chemical reaction of calcination starts at the surface of the limestone particle and moves into the core with the progress of reaction. Mechanisms of mass and heat transport take place in parallel during this process.
The physical-chemical phenomena may be described, in principle, by the 5 steps represented in the figure below.
Fig. 5 Processes during calcination (typical)
Item Description
1 Heat transfer by convection and radiation from the surrounding area to the surface of the limestone particle.
2 Heat transfer through the already calcined lime zone.
3 The heat is absorbed by the chemical reaction at the lime-limestone interface on the way into the core. The limestone decomposes into lime and CO2.
4 The generated CO2 diffuses from the centre to the surface of the particle. 5 The CO2 is released from the particle surface into the surrounding atmosphere.
The diameter and density of the particles have a strong influence on the speed for these mechanisms.
With increasing process temperature, the physical properties (especially the volume of the limestone crystals) change through the different stages of calcination. The figure below visualizes these steps by means of a cubical sample.
Fig. 6 Stages of limestone decomposing to lime during calcination (typical)
Item Description 1
When heating up from room temperature to calcining temperature the limestone expands. 2
3 After surface calcination has begun, the pore volume of the surface zone increases while the volume of the sample remains more or less constant.
4 After calcination is completed, the sample has reached the maximum porosity, but the volume of the sample remains unchanged.
5 When temperature and calcining time are further increased, the lime crystals will start to sinter. The pore volume and the sample volume will decrease.
The strong decrease of the pore and sample volume at high temperatures is caused by crystal growth. Fig. 5 below shows different apparent densities of quicklime which was calcined at different temperatures and over periods ranging from about 3 to 30 hours.
Fig. 7 Apparent density of quicklime varying with temperature and time, produced from dense, high-calcium limestone (typical) Item Description 1 1400°C 2 1300°C 3 1200°C 4 1200°C 5 1000°C
In Fig. 6 below, structures of quicklime with different apparent densities are shown in three scanning electron micrographs.
Fig. 8 Scanning electron micrographs of quicklime (typical)
3.3.3 Reactivity of quicklime
The reduction in pore volume notably reduces the specific surface area of the quicklime and causes a strong decrease in reactivity.
Quicklime with many pores has a high affinity to water. The reaction with water is exothermal, causing the release of hydration heat, which may be measured as an indicator for the reactivity of quicklime. Other test methods are mentioned in the following figure. The reference values given in Fig. 7 below only apply to the specific limestone examined and may differ from values applicable to different types of limestone.
Fig. 9 Relationship between reactivity testing methods used for quicklime (typical)
Item Description
1 BS 6463 [°C] after 2 min.
2 EN 459-2 t60 [min] - time to reach 60°C 3 EN 459-2 tu [min] - time for 80% slaking 4 ASTM C110 [°C] - temperature rise after 30 s 5 ASTM C110 [°C] - maximum temperature rise 6 ASTM C110 [min] - time to maximum temperature 7 Acid titration [ml] after 3 min.
8 Acid titration [ml] after 5 min. 9 Acid titration [ml] after 10 min.
Fig. 10 Relationship between reactivity (BS 6463) and apparent density of quicklime (typical)
Due to the influence of the pore volume, the reactivity of quicklime is indirectly proportional to the apparent density.
3.3.4 Influence of feed size on retention time
The size of particles fed to the kiln influences the retention time required for the calcining process.
Fig. 9 below shows that bigger particle sizes need more retention time in the kiln than smaller ones at a given process temperature.
INFORMATION
The figure may be used as a guideline for adjusting the burning time to the particle size of the stone.
Fig. 11 Calcining times for spheres of dense limestone (typical) Item Description 1 15 cm 2 12.5 cm 3 10 cm 4 7.5 cm 5 5 cm 6 2.5 cm
The influence of particle size and temperature on the calcining and sintering
mechanisms leads to the important issue of heat distribution in the kiln. The distribution of open voids in the limestone package must be optimized to allow for uniform gas flow and efficient heat transfer.
A lime shaft kiln has to be designed in such a way that the heat is evenly distributed over the whole shaft cross-section. Areas with a high ratio of fine particles can cause heat stagnation, which will result in local overheating. The particles in this area will be overheated, which may lead to an inappropriately high apparent density and possibly even to sintering and/or fusion.
The right particle size distribution of the limestone feed, the kiln type, and the kiln operation procedure are closely related, and only an optimized concept will result in optimal quicklime quality.
Summary
Heat distribution, temperature, and retention time influence the properties of the produced quicklime.
Three categories of particle types may be discharged from the kiln: - not fully calcined
- just fully calcined
These two categories of particles have a low apparent density and a high reactivity with water.
- different grades of calcining/sintering
In this case, the particles have an increased apparent density and a reduced reactivity with water.
3.3.5 Lime to limestone factor
Calculation based on dry limestone:
A O R MgO CaO O R MgO CaO CO Limestone Lime 3 2 3 2 2 (1.785 ) (2.092 ) 100 100
CO2 [%] Residual CO2 content in burnt lime
CaO [%] CaO content in burnt lime MgO [%] MgO content in burnt lime R2O3 [%] Impurities in burnt lime
Calculation based on wet limestone:
100
)
-100
(
moisture
A
Limestone
Lime
3.4
Fuel
Different heating systems burning solid, liquid or gaseous fuels are available for the lime kiln. Quality and type of fuel have a considerable impact on the quality of the quicklime produced. In limestone calcination, fuel is more than just a heat source. The fuel interacts with the process and the combustion products, which in turn react with the quicklime.
In the kiln, fuels such as coal, lignite, petcoke, light and heavy fuel oils, low calorific fuels, lean gas, natural gas, as well as combinations of these fuels are used. The selection of the right fuel requires experience and the consideration of numerous parameters.
The most important parameters are listed in the following table.
Properties Remarks
Costs Fuel costs represent 40 to 70% of the production cost. Calorific value The calorific value is linked to the costs of fuel per unit.
Moisture Solid fuels have to be dried to prevent them from sticking together during dosing and transport to the lances.
Sulphur About 70% of the fuel sulphur is absorbed by the quicklime forming calcium sulphate. The sulphur retained in the quicklime may affect the quality of the product.
Particle size The particle size of solid fuels influences combustion time and thus production time.
Volatile components
The combustion properties of solid fuels vary with the amount of volatile components and moisture. Consequently, the calorific value and the shape of the flame may change. Volatile components lead to the release of energy, whereas moisture consumes extra energy for vaporization.
Ash
Ash generally contaminates the lime to some degree with silica, alumina, and iron oxide. This may cause the lime lumps to stick together. The pressure on the lime lumps in the charge may enhance this bridging effect. The mixture of ash, lime dust and/or alkali (sodium and potassium) form low-melting mineral stages at the surface of the limestone particles. High amounts of ash may increase the danger of clogging caused by the effects of sintering (bridging) and the formation of low-melting stages.
3.4.1 Definition of calorific values
Lower calorific value (LCV)
The lower calorific value is the heat available after complete combustion of 1 kg or 1 m3n of fuel and cooling down of the combustion products to start-up temperature.
The LCV is defined by excluding the latent heat produced by the condensation of water in the waste gas.
Higher calorific value (HHV)
This value is the lower calorific value plus the latent heat produced by the condensation of water in the waste gas. Since the water in the waste gas is usually in the steam phase, the vaporization heat cannot be regained.
Fuel Lower calorific value [LCV] Higher calorific value [HCV] [MJ/kg] or [MJ/m3n] [kcal/kg] or [kcal/ m3n] [MJ/kg] or [MJ/m3n] [kcal/kg] or [kcal/ m3n] Hard coal, anthracite, coke 28 – 33 6500 – 8400 28 – 35.5 6760 – 8500
Dry wood dust 18 4300 19.3 4600
Fuel oil class S 40.5 9680 43.1 10290
LPG (~30% propane ~70% butane) 92.9 22190 101.2 24181 Natural gas 35.9 8570 39.8 9510 Lean gas 17.9 4275 20.1 4800
3.4.2 Combustion air volume (v’ol)
The lime kiln burns fuels using combustion air. The required combustion air volume (see tables under 1.3.5) – considering any excess or deficiency factor – must be entered into the combustion calculation program of the lime kiln.
3.4.3 Wobbe index
For gaseous fuels, e.g. coke oven gas, containing tar or other impurities, the installation of an orifice plate to measure the gas flow is required. In order to
compensate for varying gas densities, the Wobbe index is added to the formula used for calculating the heat flow.
The Wobbe index considers the ratio between the calorific value and the relative density of the gas.
Air Gas
H
W
/
W Wobbe index H Calorific value ρGas Gas densityρAir Air density
3.4.4 Heat flow
The heat flow is calculated as follows:
Heat flow [kJ / h] = gas volume [m3 / h] × Wobbe index [kJ / m3]
3.4.5 Fuel data
Solid fuels
Fuel Average composition (% by weight) Vola-tiles Lower calorific value Required combustion air C H O N H2O S LCV v’ol [%] [kcal/kg] [MJ/kg] [m3n/Mcal] [m 3 n/MJ] Wood 50.4 6.2 43.3 0.1 11 0 75 4300 18.02 1.09 0.2603 Lignite (Rheinbraun) 58.5 4.3 21.0 0.7 11 0.35 46 5278 22.1 1.09 0.2606 Bright burning coal 84.0 5.5 8 1.5 11 1.0 35 8100 33.94 1.08 0.258 Hard coal 88.0 5.0 4.5 1.5 11 1.0 25 8350 34.99 1.09 0.2603 Forge coal 90.0 4.5 3.0 1.5 11 1.0 15 8450 35.41 1.09 0.2603 Anthracite 91.5 3.8 2.2 1.5 11 1.0 10 8425 35.30 1.08 0.258 Coke 96.7 0.6 0.6 1.1 11 1.0 0 7870 32.98 1.12 0.2675 Petcoke 89.7 3.6 0.6 0.6 11 5.5 10.7 8240 34.5 1.10 0.2627 Liquid fuels
(Table valid for sulphur contents up to 2.5%)
C/H Number Density Lower calorific value Required combustion air
d LCV v’ol
[g/cm3] [kcal/kg] [MJ/kg] [m3n/Mcal] [m 3
n/MJ]
Fuel oil L (light) 6.7 0.86 10150 43 1.099 0.2625 Fuel oil S (heavy) 7.8 0.96 9680 40.5 1.103 0.2634 6.5 0.843 10052 42 1.096 0.2618 7 0.889 9906 41.5 1.098 0.2623 7.5 0.935 9760 41 1.102 0.2623
8 0.981 9614 40 1.108 0.2646
Gaseous fuels
Fuel Lower calorific value Average composition (% by volume) Required combustion air LCV CO H2 CH4 CnHm CO2 N2 O2 HHC* v’ol [kcal/m3 n] [MJ/m3n] [%] [m 3 n/ Mcal] [m 3 n/MJ] Carbon monoxide CO 3021 12.64 100 0.79 0.1887 Hydrogen H2 2572 10.76 100 0.93 0.2221 Methane CH4 8556 35.80 100 1.12 0.2675 Ethane C2H6 15370 64.31 100 1.09 0.2603 Propane C3H8 22363 93.57 100 1.07 0.2556 Butane C4H10 29280 122.51 100 1.06 0.2532 Liquefied petroleum gas (LPG) ~30% propane ~70% butane 27366 114.5 100 1.06 0.2532 Russian natural gas 8915 37.30 93.3 4.9 1.1 0.8 1.109 0.2649 Groningen natural gas (NL) 7552 31.6 81.4 3.2 0.8 14.1 1.109 0.2649 Blast furnace gas 750–951 3.14–3.98 24–30 1–2 19–21 56–57 0.8 0.1911 Coke oven gas 4275 17.9 8.6 51.4 25.9 2.7 8.1 0.3 3.0 1.027 0.2453 HHC* = Heavy Hydrocarbons
4
Design and Functioning (Type FS)
Mandatory reference materialThis chapter contains general and typical information. For details, dimensions as well as to determine and locate a specific component, reference to diagrams and drawings is mandatory. The complete reference list is included in the Appendix.
Items required with this chapter
- 010 “Steel binding - assembly“
- 059 “Poking door with measuring point“ - 154 “Protection tubes for measuring points“ - 178 “Stone distributor“
- 192…195 “Installation of limit switches“
- 500 “Hydraulic scheme” + 502 list of material - 510 “Firing system: Liquid fuel “ (if applicable) - 520 “Firing system: Natural gas “ (if applicable) - 530 “Firing system: Lean gas “ (if applicable) - 540 “Firing system: Solid fuel“ (if applicable) - 550 “Compressed air scheme“
- 600 “PI Diagram“
- 603 “Configuration control system“ - 611 “Installation: Electrical equipment“ - 612 “Installation: Measuring equipment“ - 640 “Instrument list“
- 641 “Motor list“
- Electrical documentation / Manufacture’s documentation
- Instruction Manual Book-02, Specific Data & Component Description
Technical data
Important benchmark figures and performance data can also be found in chapter
Item Description
1 Reversal flap filter / direct chimney 2 Reversal flap combustion air / waste gas 3 Reversible conveyor belt
4 Rotating bucket 5 Shaft closing flap 6 Lance cooling air duct 7 Combustion air duct 8 Kiln door
9 Discharge hopper 10 Lime vibration feeder 11 Discharge flap 12 Cooling air duct 13 Discharge table 14 Crossover channel 15 Suspended cylinder 16 Ring channel 17 Kiln shaft 18 Burner lances 19 Level indicator 20 Stone distributor
21 Stone distributor - swivel-mounted 22 Limestone vibration feeder 23 Kiln hopper
4.2
Design
4.2.1 Parallel-flow firing system
The parallel-flow firing system yields ideal burning conditions.
The flame moves in the same direction as the charge, providing the maximum temperature difference at the beginning of calcination in the burning zone. The flame pattern ensures a minimum temperature at the end of the calcination process in order to protect the smaller particles in the charge from over burning.
4.2.2 Preheating the combustion air
The regenerative preheating of the combustion air provides a thermodynamic advantage. The stone preheating zone acts as a regenerator for preheating the combustion air produced by the excess heat of the waste gas. The limestone itself temporarily stores the heat. This regenerative process is completely insensitive to dust-laden or corroding gases while providing excellent heat transfer characteristics.
Regenerative preheating of combustion air makes the kiln virtually independent of the excess combustion air factor. This considerably simplifies setting the correct length of the flame, as a large volume of excess air produces a shorter flame while a smaller volume of excess air produces a longer flame.
4.2.3 Two-shaft kiln
The regenerative system and the parallel-flow firing system demand a kiln with two shafts (1 and 2). The two shafts alternate their firing and regenerative functions at intervals. The connecting channel between the shafts is located near the bottom end of the burning zone. At this point, the kiln gases flow from the combustion shaft to the regenerative shaft.
4.2.4 Burner lances
Fuel is fed from a main system through a number of steel lances and is evenly distributed over the cross-section of the burning shaft. The lances enter the shafts at the upper, cooler part of the preheating zone and are freely suspended into the vertically descending charge.
In addition to housing them, the regenerative shaft also flushes air through the lances to cool and protect them from dust.
The amount of fuel entering the lances of the firing shaft is regulated by means of a valve system that ensures even distribution to all lances.
4.2.5 Reversing devices
Periodically switching from the burning to the non-burning shaft (regenerative shaft) requires reversing devices for fuel, combustion air, and waste gas. All reversal processes are controlled automatically.
The reversal processes are steered automatically.
The supply of the combustion air, alternatively the waste gas, is steered by a hydraulic cylinder.
Positions of the reversal flap
Regenerative shaft (secondary shaft) – waste gas pipe is open Burning shaft (primary shaft) – combustion air pipe is open
Fig. 14 Combustion air / waste gas reversal (typical)
Item Description 1 Regenerative shaft 2 Burning shaft
