Rotary Kiln refers to a rotary calcining kiln (commonly known as a rotary kiln), which is similar in shape to a rotary bed and is mainly used for calcining cement clinker. Rotary kiln can be divided into cement kiln, metallurgical chemical kiln and lime kiln according to different materials. Widely used in cement, silicate products, new building materials, refractory materials, glass ceramics and other production industries.
The working principle of Rotary Kiln
The rotary kiln (rotary kiln) is a cylindrical object with a certain slope, the slope is 3-3.5%, and the material is stirred in the rotary kiln (rotary kiln) by means of the rotation of the kiln, so that the materials are mixed and contacted with each other. reaction. The coal injection combustion at the kiln head generates a lot of heat, and the heat is transferred to the material by the radiation of the flame, the convection of the hot gas, and the conduction of the kiln brick (kiln skin). The material moves forward in the kiln depending on the inclination of the kiln cylinder and the rotation of the kiln.
Features of dry Rotary Kiln
- 1. The dry rotary kiln has a solid structure and stable operation, and can provide users with advanced high-efficiency vertical drum preheaters and five-stage cyclone preheaters.
- 2. The dry rotary kiln is a combustion device in which pulverized coal is burned to generate heat; it is also a heat transfer device, and the raw materials absorb the heat of the gas for calcination.
- 3. The dry rotary kiln has stable performance, low energy consumption, high output and convenient operation. Convenient and reliable structure and production process control, wear-resistant parts and high operating rate
- 4. Dry rotary kiln is a kind of rotary kiln, which is mainly used for calcining cement clinker. It is the main equipment of the new dry process cement production line.
Classification of Rotary Kiln
Rotary kilns are divided into variable diameter rotary kilns and full diameter rotary kilns according to their appearance, and can be divided into cement rotary kilns, ceramsite sand rotary kilns, kaolin rotary kilns, lime rotary kilns, etc. For gas-fired rotary kiln, coal-fired rotary kiln, mixed fuel rotary kiln.
(1) Variable diameter rotary kiln
Rotary kiln with varying diameters front and rear. Generally, the diameter changes before and after about 30cm. Compared with the traditional diameter rotary kiln, it has the advantages of energy saving and high output, but the variable diameter rotary kiln is more difficult to process, which is more difficult to process than the traditional diameter rotary kiln. Stricter requirements for equipment.
(2) diameter rotary kiln
It is a rotary kiln with the same diameter at the front and back. Our common type of rotary kiln was invented by Dietz Germany in 1883. After years of evolution, the rotary kiln has become a general-purpose equipment. It has better effect and higher output than traditional shaft kiln. The processing is simple, but it consumes more energy than the variable diameter rotary kiln.
The choice of rotary kiln
Rotary kiln refers to rotary calcining kiln (commonly known as rotary kiln), which belongs to the category of building materials equipment. Rotary kiln can be divided into cement kiln, metallurgical chemical kiln and lime kiln according to different materials. Cement kilns are mainly used for calcining cement clinker, and are divided into two categories: dry production cement kilns and wet production cement kilns. Metallurgical chemical kilns are mainly used for magnetization roasting of lean iron ore in iron and steel plants in the metallurgical industry; oxidative roasting of chromium and nickel iron ore; roasting of high alumina vanadium ore in refractory plants and clinker and aluminum hydroxide in aluminium plants; and chrome ore powder and other minerals. Lime kiln (that is, active lime kiln) is used for roasting active lime and light-burning dolomite for iron and steel plants and ferroalloy plants.
Rotary kiln structure
Kiln head part
The kiln head is the discharge part of the rotary kiln, the diameter is larger than the diameter of the rotary kiln, and it is sealed by the stainless steel fish scales and the kiln body.
Kiln body part
It is the main body of the rotary kiln (rotary kiln), usually 30~150 meters long, cylindrical, with 3~5 rolling rings in the middle. Most of the cylinders are processed by factories into 3~10 sections, which are transported by large trucks to the destination and welded. The rolling ring part, also commonly known as (the tire ring), is cast from molten steel, and the rolling ring part of the kiln body is slightly thicker than other parts of the kiln body due to its load-bearing. The supporting tug is also a part of the kiln body and the rolling ring is connected to the foundation correspondingly, and is the load-bearing pillar of the entire rotary kiln. Usually a set of idlers consists of two idlers and two stop wheels. The rotary kiln should be covered with refractory bricks during normal operation.
Kiln tail part
The kiln tail part is also an important part of the rotary kiln. The shape of the feed end is similar to the cover of a rotary kiln, and it is mainly responsible for feeding and sealing.
Rotary Kiln support frame
- 1. The support frame of the rotary kiln can make our rotary kiln equipment more solid, so that it will not shake when working, and stable production;
- 2. The support frame of the rotary kiln is mainly to fix our rotary kiln equipment, which can prevent the deformation of our rotary kiln equipment when it is used. Everyone knows that the rotary kiln equipment will be out of shape if it is not operated properly, so it has such a role. ;
- 3. The rotary kiln support can facilitate the hoisting of our rotary kiln equipment, etc., and facilitate transportation.
Also called preheater, it is a device that preliminarily heats the material by the waste heat of the exhaust gas discharged from the rotary kiln before the material enters the rotary kiln, and it is mostly vertical structure. The principle is to pass the waste heat discharged from the kiln tail of the rotary kiln through the preheating tower filled with raw materials to realize the raw material heating process. In addition, the preheating tower can effectively reduce energy consumption and improve the quality of finished products.
On the contrary, the cooler and the preheater are the devices that rapidly cool down the material of the rotary kiln after firing. It looks like a small rotary kiln, but the diameter is smaller and shorter, and there is no need to lay refractory bricks, and the inside is replaced by a lifting plate. The main function is to rapidly cool the finished product.
The conveyor belt is the material conveying device of the rotary kiln. During use, various forms of damage often occur, such as: edge delamination, festering, defects and cracks; long-distance longitudinal tearing, deep scratches, holes, and large-area wear , Covering the rubber drum bag or peeling, internal defects of the joint, etc. Among them, the longitudinal tear is the most urgent, the edge damage is the most common, the inherent defects of the joint are unavoidable, and the service life after repair is the most concerned.
Rotary Kiln Application
- (1) The technical performance and operation of the rotary kiln largely determine the quality, output and cost of the company's products. The folk song "As long as the big kiln turns, there are thousands" is a vivid description of the importance of the rotary kiln in production.
- (2) In the building materials industry, in addition to calcining cement clinker, rotary kiln is also used for calcining clay, limestone and slag drying; in the production of refractory materials, rotary kiln is used to calcine raw materials to make it dimensionally stable and strong. Increase, re-process molding.
- (3) During the beneficiation process, the rotary kiln is used to magnetize and roast the lean iron ore, so that the original weak magnetism of the ore is changed to strong magnetism, which is beneficial to the magnetic separation.
- (4) In the chemical industry, rotary kilns are used to produce soda, calcine phosphate fertilizers, barium sulfide, etc. In the 1960s, LapPle and others in the United States invented a new process for producing phosphoric acid with a rotary kiln. The method has the advantages of low energy consumption, low electricity consumption, no need for sulfuric acid and the availability of medium and low grade phosphate rock.
- (5) The entire production process of cement is summarized as "two grinding and one firing", in which "one firing" is the process of firing the prepared raw meal after grinding into clinker under the high temperature of the rotary kiln. Therefore, the rotary kiln is the main engine in cement production, commonly known as the "heart" of the cement plant.
- (6) In terms of environmental protection, developed countries in the world have used cement rotary kilns to incinerate hazardous waste and garbage for more than 20 years, which not only reduces and harmless waste, but also uses waste as fuel, saving coal dust, Recycle waste.