National invention patent (ZL201911026606.1)

Introduction to beam type sleeve kiln (national invention patent ZL201,911,026,606.1)

Lime kiln is an important tool for calcining lime and has a long history of development. At present, there are two kinds of lime kilns in the world, one is rotary kiln, which is generally called horizontal kiln; The other type includes mechanical shaft kiln, beam kiln, double chamber kiln, sleeve kiln, opposite fired sleeve kiln and other kilns, which are generally referred to as shaft kilns. At present, the maximum single kiln capacity of horizontal kiln is basically 1200 tons/day; The maximum capacity of shaft kiln is basically 600 tons/day. It is known that the most direct way to improve the efficiency is to improve the unit production capacity of the furnace. The higher the unit production is, the higher the efficiency is, and the lower the energy consumption is. Restricted by the existing technology, the maximum capacity of shaft kiln is 600 tons/day, which restricts the development of large-scale shaft kiln. According to statistics, the world's current lime production capacity is 360 million tons/year, of which the total capacity of the shaft kiln is about 280 million tons. It can be seen from the statistics that the market is large.

The beam sleeve kiln, referred to as CAB kiln, is a new type of active large lime shaft kiln developed by our technicians, which combines the advantages of traditional sleeve kiln, counter fired sleeve kiln, double chamber kiln and beam kiln, and has obtained the national invention patent. The design features of this kiln type break the bottleneck of low output of traditional shaft kiln. The output of a single kiln reaches 1200 tons/day, and the heat and power consumption are less than or equal to the lowest level of each kiln type. In addition, the process design structure of this kiln is simple, unlike the traditional sleeve kiln and double chamber kiln. The characteristics of low investment cost and low operation and maintenance costs make the whole beam sleeve kiln more cost-effective.

The overall structure of the beam type sleeve kiln is divided into four zones, namely, the storage zone, the pre heating zone, the calcination zone and the cooling zone. It is composed of feeding system, automatic static distribution system of kiln top, annular kiln body, combustion system, closed constant volume and quantitative automatic ash discharge system, air supply and dust removal system. The annular material surface of the kiln body makes the material surface width smaller, which means that the air flow bias in the kiln chamber is smaller and the air flow distribution is more uniform, thus ensuring the uniformity of calcination. The combustion system adopts the air cooled combustion beam for lime kiln (patent No. ZL2016 1020 4622.5), which is a national invention patent product of our company. The combustion beam is divided into upper and lower layers in staggered arrangement. It has the advantage of uniform burner arrangement and complete calcination, which makes the product quality more stable. The product activity can reach more than 360ml (4N-HCL titration for 10min), and the residual CO2 content is less than 1.5%. If the raw material conditions are good, the lime activity can reach more than 400ml.

Section diagram of beam type sleeve kiln

technological process

Core features of beam type sleeve kiln:

1 Kiln shell device
The shell of the beam type sleeve kiln is composed of two cylinders inside and outside, forming an annular section. This design is one of the characteristics of the beam type sleeve kiln. The inner and outer kiln shells are welded with steel structures. Six layers of platforms are set at different heights of the kiln shells as required to facilitate equipment installation, operation and maintenance. The inner cylinder diameter of the design is more than 5 meters, and the operators can enter the inner cylinder freely along the channel for operation. This design makes operation and maintenance very simple and direct.

2 Refractory material
The kiln lining adopts a composite structure, which is the working layer, thermal insulation layer and thermal insulation layer from the inside to the outside. According to the thermal system, the interior of beam type sleeve kiln can be divided into heat storage zone, pre heat zone, calcination zone and cooling zone. According to the characteristics and working temperature of each belt, refractory materials of different materials shall be used, such as high alumina bricks, clay bricks, light clay bricks, calcium silicate boards, ceramic fiber felt and ramming materials, to meet the use requirements of refractory materials for each part and ensure the normal service life of each part of the kiln. Due to the characteristics of our kiln structure and the optimization of design, there are only 6 types of refractory bricks for beam sleeve kiln. Compared with other kiln types, the bricks are greatly simplified. All refractory materials are standard brick type, compact in structure, cost-effective.

3 Combustion device and fuel range
The combustion system adopts the air cooled combustion beam for lime kiln (patent No. ZL2016 1020 4622.5), a national invention patent product of our company. Two layers are staggered at the top and bottom of the calcination zone of the kiln body. Several burners are designed in each combustion beam to evenly cover the annular section of the whole kiln body. The number and layout of combustion beams and burners shall be determined according to the production requirements. Ensure that the flame temperature distribution of the whole kiln section is uniform to achieve uniform calcination.

This calcination method uses the most fuel among all kilns in the world:

1) Gas fuel: natural gas, coke oven gas, converter gas, blast furnace gas, producer gas, coke gas, yellow phosphorus furnace gas, calcium carbide furnace gas, biomass gas, or mixed gas.

2) Solid fuel (powder): bituminous coal, anthracite, lignite, coke powder, bio powder fuel, etc.

3) Liquid fuel: heavy oil, light oil, etc.

4) Composite fuel: gas+pulverized coal; Fuel mixed with gas and oil.

Of course, different fuels have different process equipment and control methods.