Research On Prevention Of Coal Spontaneous Combustion In Closed Coal Yard

Closed coal yard becomes the new storage ways of coal-fired power plant, however, it’s relatively difficult to handle if the coal spontaneous combustion occurs, so the closed coal yard needs to take some effective measures to prevent the occurrence of coal spontaneous combustion to ensure the safety operation of the coal field during the coal storage.The pressure value of’chimney effect’ in closed coal yard of Changxing Power Plant is about0-138Pa, and the gas flowing through the coal pile in the closed coal field is a similar cone diffusion by the’chimney effect’. The R10000of the fine particles is from13%to15%in the intermediate region of coal pile, and the R10000of the coarse particles around the coal pile is up to70%since the segregation of coal particles. While the gas flow qv flowing through the coarse particles is43times to the fine particles under the same pressure, the intermediate coal region can be considered in the state of suffocation, and the coarse particles around the coal pile have good air conditions, so the surrounding area of coal should pay more attention during the coal storage in the closed coal yard, and the region should target inerting protection at the same time.The rise of coal temperature is the result of low-temperature oxidation of coal itself and temperature transfer interaction. The temperature and diameter of thermal point is increase with the low-temperature oxidation of coal carried out.When the temperature of thermal point is90℃,the passing distance of temperature is up to954cm, and the response time outside5m is down to67.17h (2.80days), while the temperature rises2.39℃outside5m. The measure of actual temperature points in closed coal yard of Changxing Power Plant needs to be further optimized. The maximum distance from the measuring point is472cm when the closed coal yard arranges six sets and in circular arrangement, and it can monitor the coals temperature status effectively. When predicting the low-temperature oxidation status of coals, the temperature and the rate of temperature rise of the temperature measuring points should be focused on at the same time. When the temperature and the rate of temperature rise is high of the adjacent temperature measuring points, indicating that the coal pile around the temperature measuring points is in the period of self-heating and combustion, and it needs inerting protection.The inert gas can play a protective role to the bottom of coal pile when filling inert gas from the corner of closed coal yard, and the inerting protection area increases as the inert gas pressure and flow rate increases. The closed coal yard achieves idle inerting protection when the coal pressure at the bottom of closed coal yard becomes positive, the outside air can’t enter the coals and part of the inert gas outflow from the bottom of the coals. The inert gas making the pressure of the bottommost coal pile into OPa or positive requires larger pressure and flow and make the inert gas waste when the coal temperature is higher. Therefore, if the primary alarm issues, just open the inflatable pipe at the early storage stage of the closed coal yard. If the coal at higher temperature and the intermediate or advanced warning issues, open the inflatable pipe and lock gas pipeline simultaneously, making the inert gas protect the top and parts of bottom coal area.