Experimental Study On Flame Propagation Characteristics Of Coal Clouds

In order to achieve efficient use of energy and nearly zero emissions, coal-oxygen-steam combustion mode was proposed by our research group. The minerals are removed from coal and the de-ash coal burns with pure oxygen in which spray water is gradually used to produce high temperature, high pressure, high steam concentration and high oxygen concentrations(namely, “four high” condition) of combustion environment. The resultant mixed gas pass through the advanced turbine to do work, the exhaust gas from the turbines is condensed into water and high concentrations of CO2, so as to achieve the near-zero emissions of carbon dioxide. The studies of the flame propagation characteristics on the types and concentrations of de-ash pulverized coal which is under the condition of the "four high" are one of the most important theoretical basis to realize coal-oxygen-steam combustion. It is also the key to realize "OCCSS" power generation system.This paper is based on the experimental device of 20 L spherical which was set on our own. Experimental studies on explosion characteristics of the different Shenhua and Zhundong pulverized coal cloud concentration, particle size under the condition of normal temperature and air to verify the feasibility of the test vessel. Using high-speed camera combined with image processing technology, we conducted experimental studies on flame propagation speed of different concentrations and particle sizes of Shenhua and Zhundong pulverized coal clouds under the condition of normal temperature air. The results show that the concentration of pulverized coal clouds is in the vicinity of 600 g/m3, the flame propagation speed is the fastest. With the decrease of the pulverized coal particle size, the flame propagation speed of the pulverized coal clouds is faster. Flame propagation speed of Shenhua pulverized coal clouds is greater than Zhundong pulverized coal clouds under any different conditions. The de-ash process results in the decrease of flame propagation speed of pulverized coal cloud, The alkali metals and alkaline earth metal which promote the pulverized coal combustion are removed.Aiming at fundamental issue of "OCCSS" power system, the volume proportion of O2/H2 O is 40/60, the effect of concentration of Shenhua de-ash pulverized coal clouds on the flame propagation speed were studied. This paper also studied the effect of different volume proportions of O2/H2 O on flame propagation speed when concentrations of Shenhua and Zhundong de-ash pulverized coal clouds are 0.8 kg/m3. The results show that when the O2 content is 40%,the flame propagation speed of Shenhua de-ash pulverized coal clouds present a downward trend after increasing with the increased concentration of clouds. When the concentration of Shenhua de-ash pulverized coal clouds is 1.6 kg/m3, the flame propagation speed of Shenhua de-ash pulverized coal clouds spread to the fastest is 12.2 m/s. the flame propagation speed of Shenhua de-ash pulverized coal clouds and Zhundong de-ash pulverized coal clouds present a linear increasing trend as O2/H2 O volume proportion increased. When the oxygen content increased from 21% to 50%, the flame propagation speed of Shenhua de-ash pulverized coal clouds increase from 3.8 m/s to 11.8 m/s, the flame propagation speed of Zhundong de-ash pulverized coal clouds flame propagation speed increased from 2.4 m/s to 11 m/s.