How to deal with spontaneous combustion in coal piles

Raw coal storage and spontaneous combustion-------------------------------------------------------------------------------- Author: Cement Network Unit: Cement Network Keywords: Activity-spontaneous combustion Summary: 1. Moisture 2. Ventilation rate 3. Particle fineness 4. Volatile content 5. Temperature Coal is not a highly dangerous active substance compared with other fuels, but if its characteristics are not fully understood, it will lead to serious problems in operation. First of all, coal has the property of spontaneous combustion, especially those low-grade bituminous coals. When the heat absorbed from the environment is greater than the heat released into the environment, spontaneous combustion will occur. The following factors mainly affect spontaneous combustion:: 1. Moisture: The content and changes of moisture are the most important factors affecting the self-heating of coal. When water evaporates, it absorbs a large amount of heat from the outside world, and when it condenses, it transfers this heat to coal powder. Theoretically, a 1% increase in moisture content will increase the coal temperature by 17°C. Therefore, water cannot be used to cool the coal pile that has generated self-heating. This is because the cooling water is difficult to penetrate all the coal and only allows part of the temperature to rise. 2. Ventilation rate: Theoretically, if the stagnant air reacts completely in a loose coal pile, the temperature will rise by 2°C. In fact, when the air circulates at high speed, it will also take away a lot of heat while providing oxygen to the coal. The opposite is true at low speed. Although it also provides a considerable amount of oxygen, it cannot take away the heat generated spontaneously. In terms of operation, the pulverized coal placed for a long time must be compacted, and the surrounding weeds must be removed to prevent the grass roots from causing the coal pile to become loose, making it easy for air to enter and the temperature to increase. 3. Particle fineness: There is an inverse relationship with self-heating. The smaller the particle, the larger its surface area, and the more fully it contacts the air, making it easier to generate self-heating. However, for storage considerations, so that the coal pile will not collapse easily, the fineness is generally controlled within a certain range. 4. Volatile content: Coal can be divided into bituminous coal, lignite, and anthracite according to its volatile content. Its calorific value increases and the possibility of self-heating decreases. Moreover, since pulverized coal and fly ash are mixed with raw meal (G raw meal ingredients must take this into consideration), different proportions of raw meal are required according to different coal burning requirements, and the firing operation must also be adjusted. 5. Temperature: The most important operating parameter, according to laboratory testing, the reaction rate decreases when the temperature rises below 80°C, and the activity increases as the temperature rises above 80°C. During operation, the temperature of the coal pile is measured once every month from the 1st to the 5th and the 15th to the 20th. Each ship is measured at at least three points with a height of 0.5m~3m. The record must indicate the measurement location and method (A, B, C, T, E). A value is the feed belt conveyor roller number ； The B value is the starting point from both sides of the coal pile and is filled in separately. ； The C value is the visual height ； T value is the measured temperature. When measuring, it needs to be inserted to a depth of 40cm and held at this point for at least 30 seconds. ； The E value is the ambient temperature. When the pulverized coal is more than 30°C above the ambient temperature, it must be compacted or scraped first, and the temperature measurement should be changed to once per shift. When the difference between the coal pile temperature and the ambient temperature is within 20°C, the original measurement frequency should be restored to avoid spontaneous combustion of raw coal. In addition, the stacking height of coal scrapers must be lower than 12.5 meters, and the stacking height of manual coal stacking areas must be lower than 8 meters to prevent fly ash and collapsed coal caused by strong winds and rains from flowing into farmland or roads around the coal yard. To suppress flying dust, properly maintain * * facility. Keep the drainage system of the stockyard unobstructed to avoid poor drainage when it rains, which may cause excessive coal moisture content and cause collapse and loss. An important principle in scraping coal is to pile it first and scrape it to avoid spontaneous combustion of coal stored for too long. If the coal yard operator discovers that spontaneous combustion has occurred, he should notify his supervisor to investigate the disaster situation and arrange for rescue operations. Use water to extinguish the spontaneously igniting coal pile, and then use a crawler bucket truck to excavate the spontaneously igniting coal pile and move it to an open area nearby for isolation, scattering, and compaction. After the coal in the area where spontaneous combustion occurs has been watered, isolated, scattered, compacted, etc., and the temperature is lower than 80°C and there are no sparks, it must be scraped as soon as possible. Add water appropriately after scraping.

Of course, we need to organize personnel to extinguish the fire as soon as possible, spray a large amount of water to cool down, use forklifts and other tools to isolate and trample the coal, and use water to cool down the overturned coal to prevent resurgence. Is the compaction mentioned above to reduce air, block combustion-supporting materials, and achieve the purpose of extinguishing fire by suffocation method?