Cause analysis and preventive measures of combusti

With the continuous progress of cement production technology, the new dry process kiln has been widely recognized and promoted by the cement industry for its advantages of energy conservation and environmental protection, good clinker quality, large-scale production, low investment cost, high operation rate and stable operation. In recent years, the new dry process kiln has increased at a faster rate every year. Because the growth of technology and management personnel can not keep pace with the development of the new dry process kiln, there are often new dry process kiln combustion and explosion process accidents, resulting in shutdown and equipment damage, and even casualties, causing great economic losses to enterprises, especially in winter, which is the frequent period of new dry process kiln combustion and explosion process accidents. This paper analyzes several combustion and explosion process accidents in the production of new dry process kiln, and formulates preventive measures to prevent the recurrence of similar accidents

1 Combustion Accident of coal mill electrostatic precipitator

in the winter of 2006, continuous rain and snow caused the raw coal and other materials in the open storage yard of plant a to be wet. Because the raw coal is wet, not only the production of the coal mill is greatly reduced and the supply of pulverized coal is tight, but also the humidity of the flue gas entering the dust collector of the coal mill is increased, resulting in the condensation of the electrostatic precipitator of the coal mill and the blockage of the ash hopper. Before the accident, the central control operator found that the voltage of the second electric field of the coal mill electrostatic precipitator was low, and then arranged to stop the machine for inspection, opened the inspection door of the coal mill electrostatic precipitator, and found that the pulverized coal in the electric field had been burned, a large amount of smoke appeared in the electric field, and there were sparks on the surface of the pulverized coal in the ash hopper, and the temperature was high. Then organize personnel to deal with the aftermath of the accident and make preparations for the shutdown of the kiln. The accident not only caused the shutdown of the kiln for 31 hours and the loss of more than 20 tons of pulverized coal, but also caused serious environmental pollution

1.1 accident aftermath treatment

(1) after the accident, immediately shut down the coal mill system, shut down the fan of the coal mill electrostatic precipitator, and close the inspection door of the coal mill electrostatic precipitator. Due to the small fire area, it is not necessary to turn on C and there will be no polymer exudation O2 fire extinguishing system. Open the ash discharge channel, reverse the screw conveyor under the ash bucket of the electrostatic precipitator, so that the pulverized coal in the ash bucket of the electrostatic precipitator is discharged from the ash discharge channel to the outside of the mill. At the same time, the fire water bag is used to spray the discharged pulverized coal in time to prevent secondary combustion until the pulverized coal in the ash bucket is discharged

(2) at the same time, check the condition of pulverized coal bunker. Since the pulverized coal bunker is not on fire, it is required to use up the pulverized coal bunker as soon as possible and make preparations for kiln shutdown

(3) for the discharged pulverized coal, in addition to the on-site water spraying and fire extinguishing, people are also sent on duty to prevent the resurgence of the dead ash. After normal production, the first is to organize personnel in the form of data to clean up pulverized coal and clean the on-site environment

1.2 cause analysis

(1) coal mill electrostatic precipitator is one of the main process equipment of coal mill system, and its function is to collect pulverized coal products. When the ash hopper is blocked, the amount of pulverized coal entering the pulverized coal bunker will decrease significantly, and the hole depth of the pulverized coal bunker will change greatly. According to the abnormal change of hole depth of pulverized coal bunker, it is easy to judge whether the ash hopper of coal mill electrostatic precipitator is blocked. Before the accident, the central control operator and patrol inspection personnel did not make a timely judgment, so they could not take measures in time, leaving hidden dangers for the accident

(2) because the coal mill electrostatic precipitator of the cement plant is a 2-electric field 4 ash hopper structure, before the accident, the first electric field works normally, and the second electric field is blocked due to condensation. At this time, the amount of pulverized coal entering the pulverized coal bunker decreases. Due to the wet raw coal, the output of the coal mill decreased significantly, and the material level in the pulverized coal bunker was low. In order to avoid kiln shutdown, managers and operators subjectively want to fill the pulverized coal bunker as soon as possible and then shut down for treatment. With the blockage of the ash hopper, the coal mill system has entered a vicious cycle, creating conditions for the further accumulation of pulverized coal in the ash hopper

(3) after the coal) powder accumulated to a certain extent in the ash hopper of the second electric field of the electrostatic precipitator and the natural and environmental friendly new material "bamboo fiber" was prepared from the abundant bamboo resources of nature, it began to affect the operation of the electrostatic precipitator, the secondary voltage of the second electric field of the electrostatic precipitator decreased, and the dust emission at the outlet increased. If the machine is shut down at this time, the accident can still be avoided; However, due to the lack of understanding of the possibility and severity of combustion and explosion accidents, the managers continued to start production, which eventually led to the occurrence of accidents

1.3 improvement measures

(1) revise the operating procedures of coal mills and electrostatic precipitators, include the management of preventing pulverized coal combustion and explosion, and organize managers and operators to train the knowledge of fire management of coal mills as soon as possible, so as to improve the safety awareness of preventing pulverized coal combustion and explosion

(2) patrol inspectors are required to check the blanking conditions of the ash hopper and pulverized coal bunker of the electrostatic precipitator every hour, especially in rainy and snowy weather. If blockage is found, immediately organize cleaning to prevent the accumulation of pulverized coal in the electrostatic precipitator of the coal mill

(3) regularly check the fire-fighting system of the coal mill, timely replace the steel cylinders with CO2 leakage and expired fire extinguishers, and timely take measures in case of accidents to ensure the production safety of the coal mill