Thermal power plants require large quantities of coal storage to ensure normal production. However, through long-term accumulation and running-in time, the coal will slowly produce oxidation reactions and generate heat, resulting in a gradual increase in the coal temperature and natural fire. This not only causes certain economic losses, but also easily causes fires. How to effectively prevent fires and ensure the safety of coal storage is crucial to the safety of production and economic operations of enterprises.
1. Reasons for spontaneous combustion of coal
Due to long-term accumulation and running-in time, an oxidation reaction will occur slowly and generate heat, resulting in an increase in the coal temperature. the coal will gradually increase, and finally the coal prewill fire naturally. And this is the reason and process of spontaneous combustion of coal. At the same time, the spontaneous combustion of coal is very different from other combustions, because its temperature slowly increases at the same time, depending on the accumulation of coal - low temperature oxidation heat - heat release - internal drying. sharp increase in temperature. Increase - self-ignition and fire are caused by these processes.
There are many factors for the spontaneous combustion of coal, which are mainly related to the physical and chemical properties of coal, accumulation state, environmental factors and other aspects. ?
(1) Influence of chemical composition
Coal itself contains sulfur substances, especially sulfur will produce chemical reactions and changes at a certain temperature, so sulfur oxide is generated once the sulfur. Oxide material meets water, it will generate dilute sulfuric acid. This reaction process is an exothermic process. Through this reaction process, the temperature of the coal pile can be significantly increased. ?
(2) The influence of oxygen
Under the action of various natural forces such as light, heat, rain, etc., the surface of the coal will undergo oxidative decomposition and fragmentation after contact with oxygen in the atmosphere and release heat, at the same time forming a new surface, and the new surface is oxidized again, and this cycle is repeated, resulting in the temperature of the coal pile (3) Influence of humidity
< p>A certain amount of humidity in the coal pile promotes various reactions, such as the acidification of sulfur, for example, the heat generated accelerates the process oxidation reaction and intensifies the spontaneous combustion of coal. ?(4) The influence oftemperature and air pressure
Experience shows that spontaneous combustion of coal piles often occurs after autumn, when the atmospheric temperature drops. At this season, the density of. the atmosphere is larger than that of the coal piles. As a result, the amount of air infiltrating the coal pile increases, leading to increased spontaneous combustion. Generally speaking, as the atmospheric temperature decreases and the density increases, the amount of fresh air entering the coal pile increases and the spontaneous combustion of the coal pile accelerates, and vice versa. ?
2. Measures to prevent spontaneous combustion in coal yards?
In order to reduce or prevent spontaneous combustion in coal yards, preventive measures can be taken:?
< p> (1) Superposition Compact the pile. For coals sensitive to oxidation, such as lignite and long flame coale, it is better to compact them in layers when forming a pile. At least the surface layer must be compacted. If possible, a coating layer can be applied. the surface of the coal pile. Practice has proven that this is a very effective and economical fundamental measure. ?(2) Establish a regular temperature inspection system. For coal piles with large storage capacity and long storage period, especially coal with a low degree of deterioration, the temperature of coal piles should be checked once a day. For other types of coal, the temperature inspection time can be extended and good appropriately. Detailed records. ?
(3) Timely eliminate the “disaster source” of spontaneous combustion. During the temperature inspection process, once it is found that the temperature of the coal pile reaches the temperatureextreme of 60 degrees, or the average temperature of the coal pile continually rises more than 2 degrees every day and night, the "source of disaster" must be eliminated immediately. The method of eliminating the "source of disaster" of the Spontaneous combustion involves extracting the coal in the "source" area and exposing it to air to dissipate heat and cool it. Do not add water to the coal in the "source" area, as this will speed up the process. oxidation and spontaneous combustion of coal
3. Fire fighting measures in coal deposits
For coal that ignites spontaneously, especially in areas with high sulfur content or thick coal seams, the effect of watering is not obvious. If the watered coal is not removed in time, the water will become an oxygen-rich zone. time, the coal particles will accumulate and flow easily, forming a larger oxidation space et widening the spontaneous combustion zone. Additionally, there is a risk of explosion and injury when carbon is burned in an open flame upon contact with water. This requires professional coal fire prevention and suppression technology. Praite fire prevention and extinguishing technology is an effective technical measure for extinguishing fires in coal fields. This technology was developed by Xuzhou Ji'an Mining Technology Co., Ltd. and China University of Mining and Technology.
Technical characteristics:
(1) It integrates the fire prevention and extinguishing advantages of gel, yellow mud slurry, two-phase or three-phase foam, inert gas and chemical retarder, and can be combined. The water contained in the foam is solidified in the body of the gel, which avoids the disadvantages of large water loss or collapse of the slurry in the yellow mud joints.ne and other foams;
(2) It has good diffusion performance in the goafs area, and the generated Praite uses foam as support to cover high, medium and low fire sources in the fire zones of goafs or coal deposits in a wide range and in all directions, keeping the coal moist and fresh for a long time, isolating oxygen and the additives contain chemical retardants. The agent can resist the coal body for a long time and completely prevent the spontaneous combustion of coal;
(3) Once Prat is injected into the fire area, it will. cover the fire area with a gel layer in all directions, and the gel layer is more than 95% water, which has a long-term heat absorption and cooling effect and can effectively prevent re-ignition of fire zones;
(4) Praite uses foam as a support, whichcan reach high temperatures in fire prevention and extinguishing areas. Builds up everywhere, Praite can effectively cover and adhere to floating coal cracks wherever it goes, and has good properties. performance in blocking air leak channels;
(5) The nitrogen contained in the foam is released slowly, avoiding separate injection. Nitrogen has the disadvantage of easy nitrogen loss, so it can keep the fire zone inert for a long time. time.
Conclusion
The safety management of coal storage farms is mainly based on the principle of fire prevention and suppression. With a sound management system and effective measures, spontaneous combustion can be effectively suppressed. occurrence. ?