The quench water pipeline and the large filter screen are heavily scaled, and there is a lot of ash buildup inside the gasifier; the syngas outlet is almost completely blocked!
Thread Content
What happened: A few months ago, this gasification furnace experienced overheating in its lockhopper. Investigations were carried out to find the cause, and eventually the circulation rate of the lockhopper was reduced, which prevented overheating! (A method that only treats the symptoms, not the root cause)! During a recent operation, it was found that the liquid level in the gasifier could not be raised; under normal conditions it is around 40-50%, but after the problem arose the level dropped to 30% or even lower. The level control interlock was even disabled! When the operating cycle came to an end, the unit was shut down for maintenance, and it was found that there was a large amount of hard scale formed from fine ash inside the large filter There are also large amounts of scale in the quench water pipeline. Please, teachers, analyze these together to figure out where the problem lies Please help to solve this! Thank you!
Based on what you’ve described, the main issues are high ash content in the raw materials, a low level of slag discharge due to inadequate control of the gasifier’s liquid level, and a high temperature at the syngas outlet of the gasifier, all of which lead to overheating in the lockhopper. The blockage in the quench water pipeline is related to the presence of ash in that pipeline, as well as the blockage in the synthesis gas pipeline. The quenching and dust-removal functions of the gasifier’s quench chamber are not working properly, which results in a large amount of fine ash being carried into the carbon scrubber.
Reduce the gasification temperature, lower the ash content of the feed coal, and increase the amount of quenching water. . . . . . . . . . . . . . . . . .
The thermal balance of the gasifier was not properly controlled; the amount of black water discharged was too low, resulting in high temperatures in the quench chamber and overheating of the lock hopper. The intense heat exchange in the downcomer exacerbates water carryover in the gasifier, preventing the liquid level from rising. A low liquid level results in poor washing efficiency, and the syngas carries a large amount of fine ash that gets stuck at the syngas outlet. It is recommended to switch to coal types with low ash content and low ash melting point, increase the amount of black water discharged from the gasifier, and properly control the inlet temperature of the quench water pump as well as the amount of quench water used. Generally, the amount of water used for quenching is about five to six times the corresponding load, while the discharge volume of black water from the gasifier is around 130. These control parameters can also be adjusted with reference to the process design parameters.
I agree with what was said above; I would like to add a small point – we should pay attention to the components of gasified coal and analyze them at the source. Such problems need to be analyzed comprehensively.
Don’t keep worrying too much about the issue of raw materials; for those involved in gasification, it’s often not possible to have the raw materials exactly as one wishes.