Rotary kiln working principle

1. Rotary kiln introduction

　　Rotary kiln refers to rotary calciner, belongs to building material equipment. It can be divided into cement rotary kiln, metallurgy rotary kiln and lime rotary kiln. Cement rotary kiln is mainly used to calcine cement clinker, it can be divided into dry process and wet process. Metallurgy kiln is mainly used to calcine lean iron ore, bauxite, aluminium hydroxide, chrome ore etc. Lime rotary kiln is used to calcine active lime and light roasting dolomite.

　　2. Rotary kiln Work principle

　　Rotary kiln is made of steel plate, and inside the kiln body inserts refractory lining, which keeps specified inclination with horizontal line. Three tires are supported by each supporting device, around the tire at feed end uses tangential spring plate to fix big gear, under which a pinion is meshing with. During normal operation, the rotary kiln is driven by main motor through main reducer to transmit power to open gear.

　　Material is fed into kiln from kiln tail. Due to the slope and rotation of the cylinder, the material make a composite motion—it rolls in circumferential direction and at the same time moves in axial direction. After sintering process, the material is calcined in cement clinker and discharged into cooler machine through kiln head hood.

　　Sprayed into the kiln from the kiln head, the fuel burns in the kiln, after exchanging with the material, the generated waste is discharged from kiln tail. The burner in this design is excluding fuel.

　　(1) Cylinder is made of 20g and Q235-B steel plate, and it adopts automatic welding. The thickness of cylinder is 25mm, burning zone is 32mm, under kiln tire is 65mm, and transition section is 38mm, all of those not only ensure the rigidity of cross section, but also improve loading condition of supporting device. The discharged end of cylinder has guard plate with high temperature resistance and wear resistance. Kiln tail is made of length 1m 1Cr18Ni9Ti steel plate. Guard plate at kiln head and air cowl form sleeve space, blew into the kiln from horn mouth, clod air cools the non-working surface of guard plate, which makes this parts work long-term. There are three rectangular and solid tires on cylinder. The space between tire and raiser block is determined by expansion number, during normal operation, tire can cover cylinder moderate to reduce the radial deformation of cylinder.

　　(2) Transmission system uses single drive. Driven by adjustable frequency motor, hard tooth surface and three-level cylinder gear speed reducer drives open gear. This transmission adopts rubber coupler in order to increase the drive stability. It is also equipped with auxiliary transmission device connected to the security power supply, which can ensure the normal operation when the main power cut off.

　　(3) Kiln head seal uses housing seal, labyrinth and spring steel strap double layer seal. Blew into kiln through horn mouth, cold air cools guard plate, and discharged from top after being heated. Using flexibility seal under the heat resistance spring steel strap compress the cylinder of air cow, the kiln head seal can ensure the seal function when the cylinder of kiln head has a bit deflection.

　　(4) Kiln tail uses the flexibility seal of steel strap and graphite. This device is easy to installation and safe to use.

　　Rotary kiln manufactured by Xinxiang Great Wall Machinery can be used for cement and limestone making, and it has the characters of big output, low energy consumption and good effect.

Cement Mill - Necessary Machine In Cement Production Line

Cement mill belongs to cement machinery, and what’s more, it is the necessary part of cement production line. The raw material will be conveyed to cement mill for recrushing after the first crushing. It is the key part of in the process. The ball mill is widely applied in the following industries including cement, silicate products, new building materials, refractory material, fertilizer, ferrous and non-ferrous metal ore dressing, glass ceramic, etc. It can grind various ores and other grindable materials through dry way or wet way. 

Greatwall Series ball mill is mainly applied in cement factory for cement products production and raw material grinding, also applied in industrial and mining enterprises including metallurgy, chemical engineering, electric power etc. to grinding various ores and other grindable materials. It is suitable for open circuit grinding process also for closed circuit grinding process with separator. Cement mill has strong adaptability, continuous operation, big crushing ratio, easier to adjust final product size, etc. It is capable for dry way operation and wet way operation, also for operation with grinding and drying at the same time. 

Great Wall "multi-purpose vertical mill " is about to debut Nanjing International Summit

It is reported that the Great Wall Co., Ltd. of Xinxiang will release a Lecture about multi-purpose vertical mill at 2015 Eighth International grinding Summit which Will be held on May 22, then, Xinxiang Great Wall Machinery "multi-purpose vertical mill" will shock debut to promote the energy-saving innovation and low-cost production of the cement grinding system.

　　Why select vertical mill for cement plant?

　　Clearly, In today's energy-saving background of cement industry, vertical mill has become the best cement grinding equipment. Vertical mill's application has become a powerful guarantee to reduce energy consumption, efficient production, high-quality production of the cement plant.

　　Why select "multi-purpose"vertical mill for cement plant?

　　"multi-purpose" is an effective way to reduce the cost of cement production. Cement plant need grinding the cement clinker, accessories and slag admixture separately, Therefore,many cement plant import several sets of vertical mill grinding production to meet the production needs of a variety of materials.

　　How is the Application Effect of the “multi-purpose”vertical mill in the cement plant?

　　According to the China Building Materials News reported, Xinxiang Great Wall, "multi-purpose " vertical mill has been successfully applied in Yuhui 1 million t/a cement line and 0.6million t/a slag powder line, and was tested and running smoothly in December 11.

　　In Henan Yuhui cement plant, you can see the GRMS46.41 vertical mill was used in the cement production line, can grinding the cement clinker, accessories and slag admixture separately, converte these three materials according to production requirements in 20 minutes.

　　From the control room data, we know that in this vertical mill, the production capacity of the 95 Mineral composite 32.5 cement, concrete admixtures are 130 t/h, 190 t/h and 225 t/h, especially production performance of the cement clinker is much more better than the other company's production.

　　Great Wall Machinery "multi-purpose" vertical mill has become a backbone of cement plants for improving grinding efficiency, reduce grinding power consumption and reduce cost of cement production ! May 22, the Nanjing International grinding Summit, a multi-purpose vertical grinding mill-so stay tuned !

Great Wall "multi-purpose vertical mill " is about to debut Nanjing International Summit

　　It is reported that the Great Wall Co., Ltd. of Xinxiang will release a Lecture about multi-purpose vertical mill at 2015 Eighth International grinding Summit which Will be held on May 22, then, Xinxiang Great Wall Machinery "multi-purpose vertical mill" will shock debut to promote the energy-saving innovation and low-cost production of the cement grinding system.

　　Why select vertical mill for cement plant?

　　Clearly, In today's energy-saving background of cement industry, vertical mill has become the best cement grinding equipment. Vertical mill's application has become a powerful guarantee to reduce energy consumption, efficient production, high-quality production of the cement plant.

　　Why select "multi-purpose"vertical mill for cement plant?

　　"multi-purpose" is an effective way to reduce the cost of cement production. Cement plant need grinding the cement clinker, accessories and slag admixture separately, Therefore,many cement plant import several sets of vertical mill grinding production to meet the production needs of a variety of materials.

　　How is the Application Effect of the “multi-purpose”vertical mill in the cement plant?

　　According to the China Building Materials News reported, Xinxiang Great Wall, "multi-purpose " vertical mill has been successfully applied in Yuhui 1 million t/a cement line and 0.6million t/a slag powder line, and was tested and running smoothly in December 11.

　　In Henan Yuhui cement plant, you can see the GRMS46.41 vertical mill was used in the cement production line, can grinding the cement clinker, accessories and slag admixture separately, converte these three materials according to production requirements in 20 minutes.

　　From the control room data, we know that in this vertical mill, the production capacity of the 95 Mineral composite 32.5 cement, concrete admixtures are 130 t/h, 190 t/h and 225 t/h, especially production performance of the cement clinker is much more better than the other company's production.

　　Great Wall Machinery "multi-purpose" vertical mill has become a backbone of cement plants for improving grinding efficiency, reduce grinding power consumption and reduce cost of cement production ! May 22, the Nanjing International grinding Summit, a multi-purpose vertical grinding mill-so stay tuned !

Slag powder line, raise the value of the slag, reduces environmental pollution.

In response to the call of the national five-year plan of energy saving, many companies began to adjust the industrial structure, the slag ground into powder, as a new type of building material, a good way to processing slag, is not only change waste into treasure, raise the value of the slag, but also reduces environmental pollution.

Slag powder is widely used in engineering construction, can replace 10 to 40% of cement when configuration of concrete, concrete strength can reach more than C60, also can improve the life of concrete, increase its strength, reduce project cost; not only that, slag powder in the production of cement clinker can replace part of the same amount of usage, a significant reduction in production costs, reduce the free calcium, improve stability and performance of the passing rate of cement, slag powder mixed with cement, and to improve the overall performance of cement，and sales  the same price like cement; therefore, slag powder has broad market prospects.

Talk about slag powder process, probably a lot of people have question: what is the process of slag powder line?

1.Material System

Slag is transported via train to the slag heap, after the preliminary dehydration, sent into silos, and then transported via conveyor to the drying room feeder.

2.drying system

Slag in Drying room silo feed into the dryer for drying by vibration feeder, drying heat needed by the dryer before the supply of coal-fired stove, slag after drying sent into a steel cage by crew conveyor, bucket hoist, and then sent into the mill by belt conveyor after removal of iron.

3.Grinding System

Slag sent into vertical mill after drying , then the slag powder was selected by separator filter, and returned to the mill slag powder by the screw conveyor to continue grinding mill, and the mill to form a closed loop qualified slag powder has a screw conveyor to the finished product warehouse.

4.Finished system

Slag powder production line last have a finished product warehouse, finished the slag powder is transported through the screw conveyor over, you can have the package delivered to require manufacturers of.

Last August, Shanghai Baosteel and Xinxiang Great Wall machinery co., LTD signed an annual 1.5 million tons of slag slag powder turnkey contract, at present, the project is running smoothly; Great Wall company has its own annual output of 600,000 tons of slag powder demonstration training base, and use the vertical mill equipment is the Great Wall Machinery Company research team independently developed, whether it is quality or delivery, efficiency, etc., have a safe and reliable protection.

Compact and Efficient main drive of Rotary Kilns

• By Gaby
 
• May 21, 2015  UTC+8
 
• Views: 0
 
• Tags: Rotary Kilns drive main drive of rotary kiln

Either single, double or triple reduction gearboxes are used, depending on the torque to be transmitted.These are the most common types of drive for rotary kilns because they have a high degree of efficiency and long-term economical design.

Nothing can shake them

The even, smooth operation of the kiln and optimal contact pattern with the pinion is achieved by mounting the girth gear on the kiln shell using tangential springs. The centered action of the girth gear is adjustable.

One special feature of the gear drive, as a single drive with two pinions,
is that it can operate with only one main motor. This type of drive is often
used to increase productivity using the existing girth gear.
This variant, which was developed by Great Wall Machinery, has two
positive advantages:
• no additional foundation is necessary for a second drive unit
• each pinion transmits precisely half of the torque

Feel free to create friction

alternatively, it’s possible to transmit the drive torque from the rollers to the tire. this type of drive is only suitable for two station kilns. the characteristics of both types of drive are listed in the adjacent table. hydraulic drives – acting directly or via gears on the driven shaft – also permit smooth kiln operation but are less efficient. this is why they are also considerably less economical.

learn more by video(check here )

vertical roller mills used in coal grinding

Coal pulverisation with vertical roller mills

requirements of pulverisation

Within the power industry, vertical roller mill (VRM) is the predominant equipment used for coal pulverisation. The essential requirements of pulverisation are grinding, heating, classification and transport of the pulverised coal from the pulveriser.

The grinding elements coupled with proper alignment and compression are critical to coal pulverisation in the lower mill body (grinding zone) while the classification of the pulverised coal, discharge and recirculation, is critical in the upper mill body (classification zone).

The proper metering, distribution and control of air flow through the mill, called primary air, is critical throughout the pulveriser and is the bridge between the lower grinding zone and the upper classification zone.

The coal pulveriser is the critical component of the fuel delivery system and is a major influence of combustion efficiency in the burner zone as well as the performance and efficiency of the furnace itself. As such the coal pulveriser is truly the 'heart' of the combustion process for a coal-fired power station.

Coal pulveriser design

In general, coal pulverisers are designed to achieve the maximum rated capacity grinding a design coal with a grindability of 55 HGI and 8-12 per cent moisture and achieving a discharge fineness of 70 per cent passing a 200 mesh screen (74 micron) and 99.5 per cent passing a 50 mesh screen. Variation of the coal hardness and/or moisture content will effect, up or down, the discharge capacity or the discharge fineness.

To achieve these design considerations it is essential that the grinding elements are in good condition and they maintain a consistent profile. The loss of the grinding profile results in a loss of grinding efficiency, meaning the pulveriser must work harder to achieve an equal result.

Ultimately a point will be reached in which either a loss of capacity or a loss of fineness will result under uniform conditions. Longer lasting, more consistent grinding elements are crucial to pulveriser operation yielding longer operating campaigns, reduced maintenance and a lower overall invested cost.


Wear mechanisms in a coal pulveriser

Compression, abrasion and impact are the three wear mechanisms that act upon the grinding elements and the pulveriser internals.

Compression is a wear component that results from the crushing of the material upon itself (attrition) between the grinding elements, ie between the tyres/rolls and the table. Compression is a force that acts normal (perpendicular) to the surface of the grinding elements.

Abrasion (also called erosion) is a velocity driven wear component that results when the crushed material that is suctioned off the bowl and entrained in the primary air rushes past the grinding elements. Abrasion is a shearing force that acts upon the grinding elements at an acute angle. The severity of abrasion is a function of the shear angle, the primary air velocity and the abrasiveness of the entrained material.

Impact is a momentum driven wear component that is a function of the density and the force by which the component being crushed or impacted makes contact with the crushing surface.

The primary source of impact wear in VRMs is generally from undesirable dense rock or tramp metal that enters the pulveriser with the coal.

Compression and abrasion are the primary wear mechanisms that affect the grinding elements in a coal pulveriser.

Several factors will influence the type and the severity of wear. The largest influences will be the quality of the coal being processed, the required capacity factor on the pulveriser, the PA mass flow rate, distribution, and resulting velocity profile around the bowl and pulveriser body and the orientation of the grinding elements relative to the velocity vectors.

Quartz (SiO2), found in ash, is the most abrasive component of coal and has a hardness of 1700-1800 Vickers. Quartz, being dense, will tend to concentrate itself on the table/bowl. The build-up of quartz on the bowl will increase the wear due to compression and the quartz that becomes entrained in the air stream will aggressively attack by abrasion the exposed grinding elements as well as the other exposed mill internals. A small increase in PA velocity can yield a large increase in abrasive wear when significant amounts of quartz are present.



Pulveriser grinding elements

Pulveriser grinding elements that are composed of materials that can withstand these mechanisms of wear will aid by minimising the wear velocity on the tyres and the table thus maintaining a more consistent grinding profile for a longer period thereby achieving optimised grinding efficiency for a much longer duration.

great wall vertical roller mill

Great Wall Machineryis  first-class supplier of complete grinding system,cement mill ,vertical roller mill,raw mill,ball mill,rotary kiln,cement plant..etc in China .


At present, the Chinese cement market has become saturated, we are looking to the global market. In Central Asia, South Asia, Southeast Asia, the Middle East and other regions, demand for cement is growing rapidly. As we all know, the products from China has great quality and affordable price, Great Wall Machinery’s ball mill, vertical roller mill, rotary kiln has these features. We hope our products enter these areas, who can provide support for infrastructure of these countries.

With this objective, we provide chance for cooperation and some jobs. If your company intend to be our agent, please send an email to vip@great-wall.co, attach introduction and website address of your company. If you possess skills and knowledge in machinery or cement industry, our sales job will be right for you. You can send an english resume to vip@great-wall.co, we will contact you asap.

Our website:www.great-wall.co

Factors affecting the slag vertical mill production quality

Usually in industrial production will discharge some abandoned slag. In the past they are always not rational use, not only pollute the environment, but also caused a lot of waste of resources. With the development of industrial technology, these problems have been resolved gradually, slag is grinded by vertical mill and applied to concrete, cement to improve their overall performance. By this way not only protect the environment, but also improve the utilization of resources, bring great economic and social benefits.

As more and more slag ore appears in the market, the competition is become more and more intense.So what is the main factors that impact the production quality of vertical slag mill yield ? How to improve the slag vertical mill production quality?

The factors influenced the quality are quite many, the most important ones are as below:

First, the influence of the material

Stability of feeding the amount is the key of vertical mill normal operation, Feeding unstable will cause feed material bed wear, even severe uneven stove when coking production.The iron content of the material also affects the yield and quality of vertical mill, the material contains coarse particles of iron or material conveyor belt has chunks of other impurities, it may even result in a stuck impeller feeder, therefore, require homogeneous material level of stability and as much 

Second, the impact mill operating pressure

The mill operating pressure will directly affect the yield and quality of vertical mill.If the operating pressure increased, their grinding capacity also will increase.Therefore,base on ensuring the quality of the vertical mill capacity mill operating pressure can not be set too high, it should be ready to adjust the operating pressure of the actual situation.

Pressure on the ratio of the reference

Grinding clinker: 8.0 ~ 9.0MPa

Grinding slag: 9.0 ~ 9.5MPa

Third, the influence of the classifier 

classifier powder selection ability directly affects the quality of the grinding. The higher the efficiency ,less qualified fine powder go back grinding, finished product output is higher, the opposite is low.Therefore, choose a kind of powder with high efficiency of vertical mill equipment.

Classifier speed reference 

grinding clinker: 105 ~ 120 r/min 

grinding slag: 130 ~ 145 r/min

Forth, the influence of air flow 

in general, the size of the mill air volume is one of most important factors affecting yield.Insufficient air volume will form the ability of dust, and the air volume is too big and will increase the load of dust collector, this will affect the quality of vertical mill production.Therefore, different ground conditions, different production, different requirements have different air volume control results.

Fifth, the quality of the vertical grinding machine itself

 the quality of slag vertical roller mill itself is also one of the most important factor.Therefore, choose a good slag vertical mill equipment is very important.Xinxiang Great Wall machinery since established in 1958, focused on vertical grinding machine for more than 50 years.GRMS slag vertical grinding machine is the Great Wall machinery in response to the national energy conservation and emission reduction policy, scientific research team after more than 10 years research and develop this significant energy saving, environmental protection, low carbon product machine.This machine was deeply loved by the masses of customers at home and abroad, this advantage is closely linked with grinding machine itself.The following is the unique advantages of Great Wall mechanical slag vertical mill:

1, Vertical slag mill production line system power consumption is 43 KWH/t commonly, energy-saving effect is remarkable

2, unit coal consumption quantity is little, reduce the cost

3, slag vertical mill machine equipment stable performance, operation rate is above 95%

4, widely used, can grinding a variety of materials

5, little noise, dust concentration is low, environmental effect is remarkable

6, customer purchasing many cases, all over the country