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lime-kiln

Lime kiln

There are different lime kilns . AGRM can customized lime kilns according to your requirements.

According to the shape of the kilns, they can be divided into square kilns, circular kilns, etc.
According to the characteristics of flame flow, it can be divided into horizontal flame kilns, ascending flame kilns, inverted flame kilns, horseshoe shaped flame kilns, etc;
According to the type of fuel used, it can be divided into coal burning kilns, oil burning kilns, gas kilns, etc;
According to the material transportation method, it can be further divided into kiln-car kilns, roller bottom kilns, push plate kilns, etc.

lime-kiln


More commonly, it is classified based on the physical state of roasted products and combined with production methods.
The kiln type of lime kiln is widely used in the building materials industry. Many of its predecessors were used in the cement industry to burn clinker.
In recent years, by introducing many foreign technologies and developing them, China has already had multiple advanced kiln types suitable for lime production.

AGRM Lime kiln types are classified by structure

Lime Rotary kiln

The Rotary kiln is a rotating horizontal cylindrical lime kiln. It includes dry process kilns (including dry process kilns with waste heat boilers), dry suspension preheating kilns, precalcining kilns and various new lime burning kiln systems. The lime Rotary kiln series products with vertical preheaters and vertical coolers independently developed in China have been widely promoted in China. The designed production capacity covers 250t/d to 1200t/d to meet the needs of different enterprises. Take a relatively complete 600t/d lime Rotary kiln production line as an example: the investment is 40 million to 45 million RMB, the heat consumption is below 1150×4.18kJ/kg, and the power consumption is below 45kwh/t. The Rotary kiln can use pulverized coal, calcium carbide furnace gas, coke oven gas, natural gas, and mixed gas commonly used in China, as well as multiple gas co firing, or multiple gas co firing with pulverized coal, which can basically meet the requirements of production enterprises to use local cheap energy.

lime-kiln
Lime Shaft kiln (also known as vertical kiln)

A shaft kiln is a stationary vertical cylindrical lime kiln that includes both mechanical shaft kilns and ordinary shaft kilns. Ordinary shaft kilns involve manual feeding and unloading, or mechanical feeding and manual unloading; Mechanical vertical kilns are used for mechanical feeding and unloading. Compared to ordinary vertical kilns, mechanical vertical kilns are operated continuously, and their output, quality, and labor productivity are higher than ordinary vertical kilns. In recent years, the various indicators of China’s independently developed fully automatic mechanized environmentally friendly and energy-saving active lime kilns have approached the advanced kiln type indicators of foreign countries

lime-kiln

lime-kiln
Double chamber vertical Lime kiln

Double chamber vertical kiln, as one of the advanced lime kilns, is characterized by the principle of parallel flow thermal storage roasting, which has the minimum heat consumption recognized by the lime production industry. At present, the double chamber vertical kilns designed in China have a design capacity ranging from 120t/d to 800t/d. The gas fuel heat consumption is as low as 850×4.18kJ/kg, and the power consumption is 40kWh/t. The coal powder and gas heat sources are safe and reliable, and the critical kiln lining life can reach 3-6 years.

lime-kiln
lime-kiln
Sleeve Lime kiln – Annular shaftlime Lime kiln

The sleeve kiln and lime shaft kiln were introduced into China in the 1980s. At present, the typical specifications of sleeve lime kiln types on the market include 150t/d, 300t/d, 500t/d, 600t/d. The operation of the sleeve kiln is relatively simple, the product quality is stable, the Thermodynamic activity is more than 360ml, the gas fuel heat consumption is 900×4.18kJ/kg, the power consumption is 40kwh/t, and the kiln lining life can reach 3-6 years. However, the main problems restricting the development of sleeve kilns are their complex structure, numerous irregular bricks, complex masonry, difficult maintenance, high infrastructure investment, and unsuitable use of coal powder. 2.4 Beam kiln is a lime production equipment that uses combustion beams as thermal tools to calcine lime. Since its domestication in 2000, more than 200 beam lime kilns with a capacity of 100t/d to 500t/d have been built in China and have been exported to foreign countries. The beam kiln is suitable for various fuels, such as natural gas, coke oven gas, converter gas, blast furnace gas (calorific value ≥ 800×4.18kJ/m3), mixed gas, coal powder, coke powder, heavy oil or solid liquid, solid gas mixed fuel. When the production operation is normal, the Thermodynamic activity of lime can reach more than 350ml, the energy consumption can reach 900×4.18kJ/kg, and the power consumption can reach 30kwh/t.

lime-kiln
lime-kiln
Mixing lime kiln

There are currently three popular types of mixing kilns in China: mechanized vertical kilns, energy-saving kilns, and martensitic kilns. The domestic mechanized shaft kiln has a lime kiln type of 50~500m3 and a utilization coefficient of 0.65~0.8. The fuel is coke, smokeless lump coal and smokeless briquette. The heat consumption per ton of ash is 140 kilograms of standard coal, and the raw coal is burned at about 10%. Energy saving kiln is an energy-saving lime kiln developed by the building materials industry based on the clay kiln, with reasonable optimization of kiln structure, addition of batching facilities, and air supply and exhaust devices. The kiln type has a capacity of 50-300m3, with a utilization coefficient of around 0.5, and the fuel is smokeless crushed coal. The heat consumption per ton of ash is 140 kilograms of standard coal, and the raw coal is burned at about 10%. The shape of the Ma kiln is a vase type, with a production capacity of 150t/d and a utilization coefficient of around 0.2. The fuel is smokeless lump coal. Using limestone with a CaO content of 53.5% and SiO2 content of 1.25%, the particle size after screening is 40-80mm, and the fuel is smokeless coal with a low calorific value of ≥ 6500kcal/kg. The quality of lime can reach CaO>90% and Thermodynamic activity>300ml.

lime-kiln
lime-kiln

AGRM Mixed and Gas firing Lime kilns

Mixed firing lime shaft kiln

The mixed burning lime shaft kiln generally refers to a lime kiln that uses solid fuels to burn lime, including coke, coal, and other fuels. The modern environmentally friendly and energy-saving mixed burning lime shaft kiln refers to a reasonable aspect ratio that can achieve the three stages of thermal technology inside the kiln, namely pre heating zone, calcination zone, and cooling zone. This enables the full utilization of fuel heat energy, and the top loading and bottom unloading of the kiln are closed throughout the entire operation process, The flue gas is discharged through pipelines and undergoes dust removal to achieve pollution-free emissions. It is operated and controlled mechanically or automatically from loading, distribution, material level, temperature detection, and ash unloading, which can save energy and protect the environment

lime-kiln
lime-kiln
Gas fired lime kiln

Gas fired lime kiln is a furnace that uses gas fuel to burn lime, which is called gas fired lime kiln. Currently, gas fuels used for burning lime include blast furnace gas, coke oven gas, natural gas, producer gas, biogas, and other combustible gases

lime-kiln

The existing types of lime kilns include complete sets of lime Rotary kiln calcination equipment (referred to as “Rotary kiln equipment”) and complete sets of lime shaft kiln calcination equipment (referred to as “vertical kiln equipment”). The mainstream equipment types of vertical kiln equipment include double chamber vertical kiln equipment, single chamber vertical kiln equipment, annular sleeve kiln equipment, and beam kiln equipment. The five mainstream equipment types mentioned above are all reflected in the standards.

AGRM lime kiln specifications and models

According to different purposes, lime kilns have the following specifications and models:

Capacity (t/d)1502002503003504005006007508001000
ProductActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomiteActive lime, Calcined dolomite
PreheaterCircular vertical preheater or polygonal vertical preheaterCircular vertical preheater or polygonal vertical preheaterCircular vertical preheater or polygonal vertical preheaterCircular vertical preheater or polygonal vertical preheaterCircular vertical preheater or polygonal vertical preheaterCircular vertical preheater or polygonal vertical preheaterCircular vertical preheater or polygonal vertical preheaterCircular vertical preheater or polygonal vertical preheaterpolygonal vertical preheaterpolygonal vertical preheaterpolygonal vertical preheater
Rotary kilnsize(m)Φ2.5×40Φ2.8×42Φ3×46Φ3.2×50Φ3.5×54Φ3.6×56Φ3.8×58Φ4×60/Φ4.2×50Φ4.3×58Φ4.3×64Φ4.8×68
Effective  volume (m3142190235292390430505575/5486707381005
Temperature (℃)1350/12501350/12501350/12501350/12501350135013501350135013501350
CoolerSquare vertical coolerSquare vertical coolerSquare vertical coolerSquare vertical coolerSquare vertical coolerSquare vertical coolerSquare vertical coolerSquare vertical coolerSquare vertical coolerSquare vertical coolerSquare vertical cooler
FuelGas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Gas,
pulverized coal
Heat rate(KJ/Kg)5300/50005300/50005300/50005300/50005225522551005100481048104810

There are seven types of lime kilns

Including Rotary kiln equipment with production capacity of 300 t/d~1500 t/d;
The production capacity of the double chamber vertical kiln equipment is from 200 t/d to 800 t/d, with a total of 6 scales;
The production capacity of single chamber vertical kiln equipment is from 100 t/d to 600 t/d, with a total of 6 scales;
The production capacity of the annular sleeve kiln equipment is from 150 t/d to 800 t/d, with a total of 5 scales;
The production capacity of the beam kiln equipment is from 100 t/d to 800 t/d, with a total of 7 scales.

AGRM Lime Kiln working principle

Rotary kiln equipment includes preheater, Rotary kiln and cooler with independent preheating, pyrolysis and cooling functions;
The calcination equipment of the kiln equipment is a single shaft kiln (also known as a “vertical kiln”) with centralized preheating, high-temperature decomposition, and cooling functions.

lime-kiln

Based on the composition of the calcination equipment in the complete set of lime calcination equipment and the functional classification of other main equipment in the equipment, combined with the two types of fuel morphology (powder or gas fuel, block fuel), six different types of lime kiln are classified into two equipment compositions. That is, “complete equipment for lime calcination using powdered or gaseous fuels” and “complete equipment for lime calcination using block fuels”. The main difference between the two types of equipment composition lies in the separate combustion of fuel and the mixed combustion with limestone raw materials. And it is clear that equipment using block fuel is only suitable for mixed combustion (referred to as “mixed combustion”) of single chamber shaft kiln equipment.

The production capacity and calcination quality of lime kilns are important indicators for guiding users to select equipment based on the requirements of lime grade. If it is necessary to stably produce high-grade lime (for example, Thermodynamic activity is greater than 360, or even Thermodynamic activity reaches 400+), Rotary kiln equipment should be used; If you need to produce low-grade lime normally, you can choose one of the vertical kiln equipment.

Basic working principle of lime kiln:

lime-kiln

The main component of limestone is calcium carbonate, and the main component of lime is Calcium oxide. The basic principle of lime burning is to use high temperature to decompose calcium carbonate in limestone into quicklime of Calcium oxide and carbon dioxide. Limestone and fuel are loaded into a lime kiln (if gas fuel is fed through pipelines and burners) and preheated before decomposition at 850 ℃, and calcination is completed at 1200 ℃; After cooling, it is discharged from the kiln to complete the production of quicklime products. Different kiln shapes have different preheating, calcination, cooling, and ash unloading methods, but there are several process principles that are the same: high quality raw materials, good quality lime; High fuel calorific value and low quantity consumption; The particle size of limestone is directly proportional to the calcination time; The Thermodynamic activity of quicklime is inversely proportional to the calcination time and temperature.
The lime kiln is mainly composed of kiln body, feeding device, distribution device, combustion device, ash unloading device, electrical appliances, instrument control device, dust removal device, etc.

lime Kiln Equipment

Distribution device

The distribution of materials in the mixed firing lime kiln is a key link, and the selection and use of distribution devices have a significant impact on the production efficiency of the lime kiln. There are now various distribution devices, including rotary distribution devices, conch shaped distribution devices, fixed distribution devices, etc. The selection principle is to ensure that the raw materials and fuels used in the lime kiln are evenly mixed and the size and particle size are reasonably distributed; Secondly, it has high temperature resistance and wear resistance characteristics; Thirdly, it is convenient for maintenance.

Burner

The main auxiliary equipment of a lime kiln is a burner. Gas fuel is mixed with the required oxygen (air) in a certain proportion in the burner and then sent into the furnace for combustion. Different types of gas require different amounts of air, furnace types, heating methods, and flame types. For example, pre mixed, semi mixed, external mixed, oxidation flame, neutral flame, reduction flame, etc. The burner of a gas fired kiln to a certain extent determines the calcination effect of a lime kiln.

lime-kiln
Air supply device

Both mixed firing and gas firing lime kilns require reasonable air supply, and combustion must meet three conditions: fuel, air (oxygen), and open flame. Without any of these conditions, combustion will not occur. The amount of air used is calculated based on the oxygen demand of the combustible components of the fuel. If the air supply is insufficient, the fuel will not fully burn, and if the air supply is excessive, the excess air will become smoke and lose a large amount of heat, resulting in an increase and waste of fuel. The selection of fans should be based on both theoretical calculations and specific furnace types and practical experience.

Dust removal equipment

4.1 Lime kiln cyclone dust collector – Primary dust removal is more suitable for separating and collecting high-temperature, coarse and fine dust particles, with high efficiency, large processing air volume, and stable performance. It is suitable for primary dust removal of flue gas.
4.2 Lime Kiln Bag Filter – After reaction and primary dust removal, the temperature of the limestone dust flue gas is lower than 180 ℃, which meets the temperature requirements of the bag filter; The concentration of acidic gases in the flue gas decreases, the corrosiveness is low, and the service life of the cloth bag is guaranteed; The dust particles are dry powder particles with poor adhesion and are not easy to stick or block bags. The bag filter is suitable for capturing small, dry, and non fibrous fine dust particles; It has strong adaptability to changes in gas processing capacity, can capture a large range of dust particle sizes, and has a simple structure and stable operation.

lime-kiln

At present, there are many types of lime kilns in China, but the process principles are similar and the real difference lies in the different needs. In actual production, it is possible to consider how to solve kiln problems from a holistic to local perspective; At the same time, pay attention to daily maintenance and optimization of supporting equipment

Why Choose AGRM for Your Lime Kiln Needs?

AGRM take immense pride in being a comprehensive lime kiln enterprise, offering end-to-end solutions encompassing design, processing, and installation. AGRM commitment to excellence and decades of industry experience set us apart as the ideal partner for your lime production requirements.

Expert Design Team: Our talented and innovative design team is dedicated to creating customized lime kiln solutions tailored to your specific needs. We leverage the latest technologies and industry insights to optimize efficiency, maximize output, and ensure environmental sustainability.

State-of-the-Art Processing: As pioneers in the lime kiln industry, we employ cutting-edge processing techniques that guarantee the production of high-quality lime. Our advanced facilities and quality control measures ensure consistent results that meet the most stringent industry standards.

Seamless Installation: When you choose us, you’re opting for a seamless and hassle-free installation process. Our skilled technicians possess in-depth knowledge of lime kiln systems, ensuring swift and precise installation, minimizing downtime, and getting your operations up and running promptly.

Customer-Centric Approach: We prioritize our customers’ needs above all else. Our team works closely with you throughout the project, providing regular updates, addressing any concerns, and ensuring that your expectations are not only met but exceeded.

Timely Support and Maintenance: Our dedication to customer satisfaction doesn’t end after installation. We offer ongoing support and maintenance services to keep your lime kiln operating optimally, extending its lifespan and reducing operational disruptions.

Sustainable Solutions: As environmentally-conscious practitioners, we emphasize sustainable practices in our designs and processes. By choosing to collaborate with us, you align your organization with eco-friendly solutions that contribute to a greener future.

lime-kiln
lime-kiln

Choosing AGRM as your partner for lime kiln projects means partnering with a team of industry experts who are committed to delivering exceptional results. Join us on the journey towards unparalleled efficiency, reliability, and success in your lime production endeavors.

Contact us today to explore how we can take your lime kiln project to new heights!

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