Chlorine Migration Characteristics In Coal Gasification System

Coal had very complicated composition and now did not have an clarified rule for chlorine migration characteristics which just could be analyzed for specified coal type and process. In order to make it clear that how chlorine distributes in gasification system, the migration characteristics of chlorine was investigated in this paper in coal gasification system by some ways, such as experiments, sampling and analysis, thermodynamic calculation and system simulation.Gasification experiments with Inner Mongolia coal were operated on the fixed bed reactor. In fixed bed reactor, the release characteristics of chlorine in gasification process were studied. Results indicated that most of chlorine was released during pyrolysis stage, while a little during gasification stage; After adding CaO into feedstock, the phenomenon that chlorine was adsorbed by the CaO was founded, and this results was also confirmed in thermodynamic calculation.The distribution characteristic of chlorine in Entrained-flow gasification system was researched through sampling and analysis from two gasification plant. One was Entrained-flow coal water slurry gasification plant with Shenfu coal, and the other one was Entrained-flow pulverized coal gasification plant with Anhui coal. And the influencing factors were also studied. Results showed that in the Entrained-flow coal water slurry gasification plant with Shenfu coal, most of chlorine existed in waste water, but a little in coarse slag and fine slag; in the Entrained-flow pulverized coal gasification plant with Anhui coal, most of chlorine existed in coarse slag, fly ash and waste water, however, a little in fine slag, and sodium and potassium enriched in fly ash particulates was founded. The factors that influence chlorine distribution in system, such as coal type, the mode of occurrence in coal, gasification feeding method, operating temperature, Heat-recovery and Ash-deposited way.Based on chlorine conversion ratio in gasifier which was calculated according to the data of chlorine distribution in Entrained-flow coal water slurry gasification plant with Shenfu coal, simulation of chlorine distribution in Entrained-flow coal water slurry gasification system was conducted using Aspen Plus software. Simulation results indicated that most of chlorine existed in waste water, which was basically agreed with that of analysis; and the chlorine concentration at the outlet of Vacuum Flash was the biggest.