The Quenching Process For Pyrolysis Gas Of Plasma In Coal Chemical Industry

Producing acetylene by coal pyrolysis in the plasma reactor is regarded as a promising technique due to its short process, low resource consumption, cleanliness and effectiveness. It is expected to be a new way for the clean use of coal. But the pyrolysis gas from the plasma reactor is very hot, and acetylene is unstable under high temperatures and prone to decompose, so pyrolysis gas requires quenching. Based on the practical experience from the lab test and pilot test, this thesis tried to solve the problems encountered in the quench cooler, and simulated the quenching process for pyrolysis gas. The main contents are as follows:In order to solve the problems encountered in the quench cooler of lab test, the inner structure of the cooler was redesigned. For overcoming the difficulty that different kinds of quenching agents could not inject into the quench cooler at the same time, a new solution was proposed, where a static mixer was added before the quench cooler, and the flow characteristic and mixing characteristic of the quenching agents in the static mixer was simulated.In order to solve the problems encountered in1MW level annular-type quench cooler for pilot test, a more reasonably structured quench cooler without water cooling pipeline in the base was designed, which allows for multi-medium quenching agent’s injection at one time. A gas-liquid two phase mathematical model was proposed, and was used to simulate the temperature field in the quench cooler with no pulverized coal injection. The results show that the model could describe the performance of the quench cooler in the pilot test.Combined with the experimental data of a company’s2MW pilot test, a gas-liquid-solid three phase mathematical model was proposed, and was used to simulate the quenching process. The results indicate that the model is usually in accordance with the actual situation. Besides, a "soft-barrier" method was proposed. The method can not only quench the high temperature gas, but also protect the quenching core against the impact from pyrolysis gas and coal powder, thus laying a good foundation for further quenching process optimization.