Numerical simulation of multiphase flow process and structural improvement measures in the quench chamber of a gasifier
The entrained flow coal gasification technology is one of the important means for the clean utilization of coal.In the syngas cooling device,the quench chamber with riser-downcomer structure is widely used in the coal gasification device.There is a situation where synthetic gas escapes from the black water outlet in the quench chamber of this type of quench chamber,resulting in a waste of resources.In this work,the gas-liquid two phase flow in the quench chamber is stuided with the numerical simulation method.The causes of syngas escape problem from the black water outlet in the quench chamber are analyzed,and three improved structures for the quench chamber are proposed as follow:extending the black water outlet pipe(structure A),extending the riser pipe downwards(structure B),adding a baffle on the rising pipe near the black water outlet(structure C).The simulation results indicate that all three improvement schemes can avoid the problem of syngas escape.In addition,the liquid-solid two phase flow in the black pool with four structures(structures A,B,C,and the original structure)are simulated,and the carry-out rate of ash particles with different particle sizes under the same conditions are compared in different structures.The results show that the carry-out rate of ash particle in the improved structure C is the smallest,followed by the structure A.These two structural schemes are suitable for the situation where the residual carbon in the filter cake is not recycled,and the low carry-out rate of ash by black water is beneficial for improving the water quality of the water circulation system.Compared with the original structure,the structure B has a higher carry-out rate for particles size smaller than 20 μm,but a low carry-out rate for large particles,which is suitable for recycling the residual carbon in the filter cake.
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