Influence Of Particle Configuration On Coal Pyrolysis In Reactor With Internals

Coal pyrolysis can extract tar and gas which is rich in hydrogen and high-quality char which is rich in carbon under relative mild conditions with high resource utilization efficiency. To achieve high-quality tar with low dust and high yield, Chinese Academy of Sciences Institute of Process Engineering recently developed an fixed bed pyrolysis reactor with internals, which has a good prospect. To further optimize the coal pyrolysis technology, this paper studied the influence of inner particle configuration on coal pyrolysis in the fixed bed reactor with gas collecting pipe. The main results show as follows:1. Mongolia and Shenmu coal are used as raw materials in this paper. We studied the pyrolysis characteristics of raw coal through thermogravimetric analysis and Gray-King assay. The results show: tar is generated in 350-500? for Mongolia and Shenmu coal; As particle size decrease the weight loss of Mongolia coal increases, the weight loss of Shenmu coal decreases yet; With the increase of heating rate, the weight loss of both coal decrease; With the increase of particle size, the tar yield of both coal decrease.2.It is studied in this paper that the influence of particle configuration on pyrolysis product distribution in the fixed bed reactor with gas collecting pipe through several experiments, taking the effect of factors such as coal species, temperature into considered. One set of experiments(include(a)inside large size outside small size?(b)mixture?(c)inside small size outside large size)were carried out at 800?, where Mongolia coal is used. While the other two sets of experiments were conducted at 800? and 900?, where Shenmu coal is used. The results show the same regularity: tar yield:(a)>(b)>(c); char yield:(c)>(b)>(a).3. A cold-state simulate experiment was performed to research the effect of particle size on the escaping resistance of pyrolysis gas. The results show: the pressure drop of different coal particle on pyrolysis gas lies in this order: small size>mixture>middle size>large size. Pyrolysis gas get out of the fixed bed reactor by two ways:(?) pyrolysis gas flow to the inner layer, and then get out of reactor through middle gas collecting pipe directly.(?)pyrolysis gas spread to outer layer firstly, then flow to the top of the reactor along the outer wall of the reactor, flow down along the slit of gas collecting pipe and go out lastly. Pyrolysis gas of reaction(a) mainly outflow by the way(?), which has short path and less secondary reactions leading to high tar yield and low char yield. Pyrolysis gas of reaction(c) mainly outflow by the way(?), which has long path and more secondary reactions leading to low tar yield and high char yield. Pyrolysis gas of reaction(b) will outflow by the both ways, yet the pressure drop in the both ways will be higher. Thus, tar yield:(a)>(b)>(c); char yield:(c)>(b)>(a).