Application of air cooler in rotary kiln tail of cement industry--Conventional air cooler problems

Kiln tail flue gas is characterized by: large flue gas, high temperature, high concentration and contains acid and alkali oxides and other corrosive ingredients. In addition, more than 60% of the dust particle size is less than 2.5 μm, making the dust viscosity. Flue gas through the cooling of the steel pipe easily lead to clogging. In fact, at first when the dry cement production line was introduced into China, the kiln tail flue gas treatment has indeed tried the air cooler. At that time the cooling pipe diameter of air cooler was less than Φ60 mm. Shortly after put into use, due to the nature of the kiln tail flue gas, serious obstruction within the tube happened, affecting the normal operation of the process. So solving the steel cooling pipe blockage is the key to decided success or failure of air cooler application in kiln tail.

Usually there are three ways to prevent and clear the blockage:

1) By reducing the inner diameter of the steel pipe or reducing the number of steel pipes to improve the speed of flue gas into the cooling steel pipe, so that smoke quickly through the tube to reduce the fouling time. Disadvantages: high-speed flue gas will flush and wear the nozzle, reducing the life of the cooling pipe, and increase the resistance of the tube and exhaust fan energy consumption.

2) Expand the diameter of the cooling steel pipe. Disadvantages: cooling pipe diameter to expand, resulting in a sharp decline in heat transfer efficiency, need to increase the cooling fan air volume and power.

3) direct removal of the cooling tube fouling, when the popular gas box pulse or anti-blowing cleaning technology, low efficiency, low strength, making clear the block is very difficult.

Neither of these 3 methods can solve the problem effectively. The blockage of the cooling steel tube seriously affects the normal process production, which has led to the stagnation of the air cooler in the rotary kiln for many years.

With the development of new technology in dust removal field and cement production line, after years of development, pulse jet cleaning technology has become the mainstream, with high efficiency, high strength, one to one injection characteristics. It has been widely used in all walks of life dust removal equipment. Can we combine the pulse jet blowing and soot cleaning technology to improve the air cooler again so that it can be applied to the flue gas field at the kiln end? After careful analysis, each cooling tube is like a filter bag, which can be used as a dust collector, so that each cooling pipe is pulsed by the pulse air flow to remove the dust attached to the inner wall of the cooling pipe.

After analysis and demonstration by dust removal test: for an upright cooling pipe, one end is fixed, one end is articulated, use high voltage (0.5~0.7 MPa) gas pulse to inject the interior of the pipe, and the cooling pipe vibrates to a certain extent, accompanied by the gravity and downward gas flow driven, to make the dust off the tube wall, so as to eliminate dust tube blockage.