The three elements of combustion and explosion of coal dust explosion proof pulse dust collectors are combustible substances, enough oxygen and fire.
1 The first element of the combustion and explosion of the coal mill dust collector: combustible material The fine coal powder captured by the coal mill dust collector is itself a flammable substance, its combustion and explosion characteristics and coal volatile, ash, moisture, particle size, gas temperature Concerned with dust concentration and other factors. The volatile components of coal have the greatest influence on the flammability of pulverized coal. The greater the volatility, the greater the explosion risk. The relationship between the volatile content of coal and the ignition temperature and maximum explosion pressure.
b. The ash content of coal is also closely related to the explosiveness of pulverized coal. Only when coal contains more than 70% non-flammable substances will it lose its explosiveness. In fact, the ash content of coal is not more than 40%.
c. Explosiveness of coal is impaired when its moisture content is greater than 4% to 6%, and explosiveness is lost when moisture content exceeds 10%. Coal-fired coal kiln must be dried, generally requires about 1% moisture, thus increasing the explosiveness of pulverized coal. If the particle size is the same, the higher the moisture, the lower the maximum explosion pressure of the pulverized coal.
d. The fineness of pulverized coal has a great influence on the explosion. The finer the pulverized coal, the easier it is to catch fire.
e. The combustion or explosion of pulverized coal is directly related to the temperature. According to practical experience, the self-ignition temperature during pulverized coal accumulation should be controlled at 70-90°C. The temperature is lower than 70°C, which is advantageous from the perspective of preventing explosion, but it is easy to approach the dew point to generate condensate, so that the coal powder adheres to the dust collector and is harmful to the safe operation of the pulse dust collector.
f. The lower explosive limit of gas containing pulverized coal concentration is generally 20-60g/m3 and the upper limit is 2000-7000g/m3. The reasons for the large changes in scope are mainly affected by the above factors. The pulverized coal concentration of coal dust collector electrostatic precipitator should generally be less than 40g/m3.
2 The second element of the combustion and explosion of the coal mill dust collector: Sufficient oxygen coal mill to dry the coal. Use a special hot blast stove or use a low oxygen content kiln tail gas or a high oxygen content cooler exhaust, from a safety perspective. Considering that coal mill drying should use kiln tail gas as much as possible. Because the oxygen content of the kiln exhaust gas is generally less than 14%, it can be considered as an inert gas, and the cooler exhaust gas with oxygen content close to 21% has more stringent requirements for flameproof and explosion-proof. Even if kiln tail gas is used as a heat source, the oxygen content may increase during grinding and grinding. Therefore, the oxygen content of coal-heated gas is generally controlled within the range of less than 14%, and the oxygen entering the precipitator during actual production should be controlled within the range of less than 12%. Above 12%, audible and visual signals should be emitted, exceeding 14%, and the mill should stop running.
3 Burning and Explosion of Coal Mill Dust Collector Third element: The ignition temperature of the pulverized coal of the fire source differs depending on the type of coal, generally greater than 580°C, and the ignition energy is greater than 20mJ. This is the two conditions that must be possessed as a source of fire. Although the temperature in the coal dust collector is lower than 100°C, it is unavoidable to generate sparks in the electrostatic precipitator, and its ignition energy is greater than 20mJ. When the dust-containing gas in the bag filter passes through the filter bag, static electricity is generated due to friction, and the charge is accumulated to a certain amount, which may also become a source of ignition. However, electrostatic accumulation of bag filter electrostatic ignition can be much smaller than the electrostatic precipitator ignition energy, which is the main reason for bag-type pulse dust collector is not easy to produce explosion. Bag-type dust collectors often cause fire burning accidents, which are mainly caused by improper process operations.
Keda environmental protection company produces various types of environmental protection machinery and dust removal accessories. The company has strong technical force, strict quality management, excellent manufacturing and first-class after-sales service to win the praise of customers.
1 The first element of the combustion and explosion of the coal mill dust collector: combustible material The fine coal powder captured by the coal mill dust collector is itself a flammable substance, its combustion and explosion characteristics and coal volatile, ash, moisture, particle size, gas temperature Concerned with dust concentration and other factors. The volatile components of coal have the greatest influence on the flammability of pulverized coal. The greater the volatility, the greater the explosion risk. The relationship between the volatile content of coal and the ignition temperature and maximum explosion pressure.
b. The ash content of coal is also closely related to the explosiveness of pulverized coal. Only when coal contains more than 70% non-flammable substances will it lose its explosiveness. In fact, the ash content of coal is not more than 40%.
c. Explosiveness of coal is impaired when its moisture content is greater than 4% to 6%, and explosiveness is lost when moisture content exceeds 10%. Coal-fired coal kiln must be dried, generally requires about 1% moisture, thus increasing the explosiveness of pulverized coal. If the particle size is the same, the higher the moisture, the lower the maximum explosion pressure of the pulverized coal.
d. The fineness of pulverized coal has a great influence on the explosion. The finer the pulverized coal, the easier it is to catch fire.
e. The combustion or explosion of pulverized coal is directly related to the temperature. According to practical experience, the self-ignition temperature during pulverized coal accumulation should be controlled at 70-90°C. The temperature is lower than 70°C, which is advantageous from the perspective of preventing explosion, but it is easy to approach the dew point to generate condensate, so that the coal powder adheres to the dust collector and is harmful to the safe operation of the pulse dust collector.
f. The lower explosive limit of gas containing pulverized coal concentration is generally 20-60g/m3 and the upper limit is 2000-7000g/m3. The reasons for the large changes in scope are mainly affected by the above factors. The pulverized coal concentration of coal dust collector electrostatic precipitator should generally be less than 40g/m3.
2 The second element of the combustion and explosion of the coal mill dust collector: Sufficient oxygen coal mill to dry the coal. Use a special hot blast stove or use a low oxygen content kiln tail gas or a high oxygen content cooler exhaust, from a safety perspective. Considering that coal mill drying should use kiln tail gas as much as possible. Because the oxygen content of the kiln exhaust gas is generally less than 14%, it can be considered as an inert gas, and the cooler exhaust gas with oxygen content close to 21% has more stringent requirements for flameproof and explosion-proof. Even if kiln tail gas is used as a heat source, the oxygen content may increase during grinding and grinding. Therefore, the oxygen content of coal-heated gas is generally controlled within the range of less than 14%, and the oxygen entering the precipitator during actual production should be controlled within the range of less than 12%. Above 12%, audible and visual signals should be emitted, exceeding 14%, and the mill should stop running.
3 Burning and Explosion of Coal Mill Dust Collector Third element: The ignition temperature of the pulverized coal of the fire source differs depending on the type of coal, generally greater than 580°C, and the ignition energy is greater than 20mJ. This is the two conditions that must be possessed as a source of fire. Although the temperature in the coal dust collector is lower than 100°C, it is unavoidable to generate sparks in the electrostatic precipitator, and its ignition energy is greater than 20mJ. When the dust-containing gas in the bag filter passes through the filter bag, static electricity is generated due to friction, and the charge is accumulated to a certain amount, which may also become a source of ignition. However, electrostatic accumulation of bag filter electrostatic ignition can be much smaller than the electrostatic precipitator ignition energy, which is the main reason for bag-type pulse dust collector is not easy to produce explosion. Bag-type dust collectors often cause fire burning accidents, which are mainly caused by improper process operations.
Keda environmental protection company produces various types of environmental protection machinery and dust removal accessories. The company has strong technical force, strict quality management, excellent manufacturing and first-class after-sales service to win the praise of customers.
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