水煤浆热解过程中HCN和NH_3释放特性的分析

An Analysis of HCN and NH_3 Release Characteristics of Coal-water Slurry in its Pyrolysis Process

采用固定床反应器对水煤浆及其制浆原煤在惰性气氛下,制浆原煤在水蒸气气氛进行热解试验,研究HCN、NH3的释放特性。结果发现,制浆原煤和水煤浆HCN的释放量,随温度增加变化缓慢,趋于稳定;而制浆原煤在水蒸气气氛下,HCN的量随温度变化增加迅速,析出量远远超出制浆原煤及水煤浆的释放量。制浆原煤NH3释放量随温度升高先增加后有下降,在1 000℃左右出现一个峰值,温度继续升高,NH3的量不再增加反而开始降低;水煤浆中NH3析出的量随温度增加,虽变化缓慢,但是仍比制浆原煤释放出的NH3量要多;制浆原煤在水蒸气气氛下,随温度的升高,NH3的量一直呈增加趋势,温度到达1 000℃后,增加更加迅速,释放量大于制浆煤和水煤浆的NH3释放量。综合考虑HCN和NH3的释放量以及燃料的着火、燃烧,显然水煤浆燃烧要优于煤粉的单独燃烧和煤粉喷水蒸气燃烧。

A pyrolysis test was performed of coal-water slurry and its raw coal in an inertial atmosphere and of its raw coal in a vapor atmosphere on a fixed bed reactor to study HCN and NH_3 release characteristics.The results show that with an increase in temperature the amount of HCN released from the raw coal and coal-water slurry changes slowly and finally tends to be constant.In the vapor atmosphere, however,the amount of HCN released from the raw coal will with a change in temperature quickly increase and the amount being separated out far exceeds the amount released from the raw coal and coal-water slurry.The amount of NH_3 released from the raw coal will with an increase in temperature first increase and then decrease and a peak value will emerge at about 1 000 ℃.If the temperature continues to go up,the amount of NH_3 will not increase,but on the contrary begin to decrease.The amount of NH_3 separated out from the coal-water slurry will increase with an increase in temperature.Although the change proceeds slowly,the NH_3 amount released is still larger than that released from the raw coal.In the vapor atmosphere,with a rise in temperature,the amount of NH_3 all along exhibits a tendency to increase and after the temperature reaches 1 000 ℃,such an increase will go on still more rapidly with the amount released to be larger than that released from the raw coal and coal-water slurry.When the amount of HCN and NH_3 released as well as the ignition and combustion of fuel are taken into account in a comprehensive way,it can be clearly seen that the combustion of coal-water slurry is superior to that of pulverized coal alone and of pulverized-coal with steam injection.