Explosion proof and flame proof measures for bag t

Explosion proof and anti combustion measures for coal mill bag type dust collector

the coal mill bag type dust collector adopts fan back blowing for ash removal. When the system works under high negative pressure and the negative pressure at the inlet of the dust collector reaches more than -3000pa, the reverse blower can be used

the imported air box pulse bag filter can also be used as a coal mill dust collector, but the filter material used must be anti-static polyester needle felt. When other design considerations are the same, it can also ensure that the measurement results are the same

if there is fine pulverized coal in the air, there is a risk of combustion and explosion, and its limit concentration is> 50g/m3, <2000g/m3. The concentration of coal dust emitted by the coal mill is 25 ~ 80g/m3, which is an explosive dust gas. The accumulation of pulverized coal makes the heat generated by the slow oxidation of pulverized coal cannot be lost in time, and the internal temperature rises. If the accumulation is too thick, the temperature can reach the combustion temperature, causing the spontaneous combustion of pulverized coal. The influencing factors of combustion and explosion include: first, ambient temperature; Second, pulverized coal concentration; Third, the fineness of pulverized coal. The higher the ambient temperature, the higher the concentration or fineness of pulverized coal, the greater the risk of combustion and explosion; Fourth, the gas oxygen content. When the gas oxygen content is less than 10% - 12%, there is actually no danger of explosion. The dust collector used for coal mill ventilation must be explosion-proof and flame-proof

(1) explosion proof and anti combustion measures adopted in the design of domestic developed coal mill bag filter

1) ash hopper wall inclination 70. Weld the chute on the right angle formed by the two inclined planes of the ash hopper to avoid ash deposition at the 90 included angle

2) anti static filter cloth is adopted, and its friction potential is lower than that of general filter materials, which is conducive to preventing spark discharge caused by electrostatic accumulation and ignition of pulverized coal

3) gravity pressure relief valve is adopted. When the pressure in the body exceeds 1000Pa, the pressure relief valve will be opened, which can limit the explosion consequences to a minimum

4) there is no ash plane with small inclination in the body, and the angle steel used for internal support is also designed as an inclined plane

5) temperature measuring elements are installed at the inlet, outlet and ash hopper, and the signal is transmitted to the microcomputer console. When the temperature at any point exceeds 90 ℃, the console will send an audible and visual alarm signal, and the enterprise will be more closely involved in clarifying how to use new materials to truly promote the process of economic development and even the birth of a new industry, and notify the post workers to deal with it immediately. If there is no one to operate, the console will automatically cut off the air path and force the system to stop after 1 ~ 2min

(2) precautions

when designing the dust removal system of coal mill, the following aspects should be paid attention to:

1) effective ash unloading valve is adopted, and the rotating shaft torque durability tester adopts high-precision load element measurement and stepping electromechanical drive to prevent excessive dust concentration in the exhaust air of coarse particle separator due to the failure of ash unloading valve

2) if possible, preheater exhaust gas should be used as hot gas source. The oxygen content of preheater exhaust gas is very low, generally 8% - 10%. Under this inert atmosphere, pulverized coal will not burn

3) before shutdown, it is necessary to do this first, so the gain is not worth the loss. Carry out ash cleaning operation, and then shut down after unloading the pulverized coal in the ash hopper

4) if the lower ash discharge valve of the ash hopper fails, it must be repaired immediately. Do not wait, so as to avoid excessive accumulation of pulverized coal in the ash hopper and spontaneous combustion

5) if the pulverized coal preparation system is a double fan system, when the main fan stops and the dust removal fan operates, the heat engine can directly enter the coal mill bag type dust collector through the short circuit of the connecting pipe, so that the temperature of the dust collector will soon rise above the warning temperature. In order to prevent hot air from entering the dust remover in a short circuit, the main fan must be interlocked with the dust removal fan so that the dust removal fan cannot operate alone