Transient CFD modelling of low-temperature spontaneous heating behaviour in multiple coal stockpiles with wind forced convection

Abstract

G. (2016). Transient CFD modelling of low-temperature spontaneous heating behaviour in multiple coal stockpiles with wind forced convection. Fuel Processing Technology, 149 55-74.Transient CFD modelling of low-temperature spontaneous heating behaviour in multiple coal stockpiles with wind forced convection AbstractSpontaneous heating of coal stockpile has long been a thermal dynamic hazard during coal storage, processing, and transport. A transient non-equilibrium thermal CFD model has been developed to study the low-temperature self-heating behaviour of coal in multiple stockpiles under different prevailing wind conditions. Modelling results from the initial steady wind flow simulation indicate that a wake region can be induced on the leeward side of each coal stockpile. Pressure coefficient drops when the wind stream encounters or leaves a stockpile and the pressure coefficient profiles of multiple stockpiles tend to have more resemblance with a wider spacing. The first stockpile acts like a wind barrier to the adjacent stockpiles and the maximum temperature of it tends to be the first approaching the critical temperature. A 'hot spot' will develop and then migrate towards deep regions in each of these stockpiles that are loosely compacted under higher wind velocity conditions. Wind velocity and porosity of stockpile have significant influences on self-heating behaviour of the stockpiles and transport pattern of gaseous products liberated by coal oxidation. Compacting stockpiles from loosely packed scenario to slightly packed scenario might not be able to slow down the temperature rising rate at low-temperature range but could considerably minimize the volume of deteriorated coal. The highest temperature rising profiles of the stockpiles located in downwind side can approach to that of the first stockpile, particularly when they are more widely stacked. Stacking coal stockpiles as close as practically possible is recommended to maximise the "protection" of adjacent stockpiles but would cause undesirable accumulation of carbonic gases. Stockpiles in low height and gentle slope will have a prolonged safe storage period, especially for the first stockpile directly facing the wind direction. However, it may not slow down the self-oxidation process of the adjacent stockpile at very initial stage due to "weakened protection" of the first stockpile. This study has practical reference to coal industry especially where multiple coal stockpiles require to be constructed. 13The first stockpile acts like a wind barrier to the adjacent stockpiles and the maximum temperature of it tends to 14 be the first approaching the critical temperature. A 'hot spot' will develop and then migrate towards deep 15 regions in each of these stockpiles that are loosely compacted under higher wind velocity conditions. Wind 23Stockpiles in low height and gentle slope will have a prolonged safe storage period, especially for the first 24 stockpile directly facing the wind direction. However, it may not slow down the self-oxidation process o...

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Prediction of BP neural network and preliminary application for suppression of low‐temperature oxidation of coal stockpiles by pulverized coal covering

“…Coal spontaneous combustion can be affected by the degree of coalification, petrographic composition, coal void ratio, coal moisture, and particle size, etc. [ 1–3 ] For a particular coal stockpile, the inherent properties such as degree of coalification and petrographic composition cannot be changed. The coal spontaneous combustion can only be prevented or controlled by altering the coal pile structure and external conditions, such as reducing the impacts from environment and strengthening the monitoring of cryogenic latency, through hindering the infiltration of air in the coal stockpile, evacuating the heat of the coal pile, and decreasing the temperature of the coal pile.…”

Effects of ionic liquid concentration on coal low‐temperature oxidation

“…[1][2][3][4] Therefore, CSC prevention is of great significance for the safe production of coal. Coal spontaneous combustion (CSC) can not only produce lots of toxic and harmful gases, but also cause casualties.…”

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