The 6.5MPa single-nozzle gasification furnace frequently experiences high temperatures on the brick support plate

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Dear colleagues: Our unit uses a Texaco gasification furnace with a pressure of 6.5 MPa and dimensions of 3.2*3.8 meters. During operation, there have been multiple instances of overtemperature alerts related to the brick support plates in the furnace. Almost every time, overtemperature alerts were triggered by the thermocouples located above the manhole right opposite the crude gas outlet of the furnace. In the past, there was a serious problem of dust accumulation at these thermocouples, which led to poor heat exchange and thus overtemperature issues. Now, dust accumulation is rare at the thermocouples, but overheating of the support trays still occurs. Inspections during shutdowns have shown that in recent cases, this overheating was caused by slag blocking or scale fragments blocking the upward passage of raw gas between the rising and descending pipes, which in turn led to overheating of the thermocouples on the support trays above that area (our facility has four thermocouples on the support trays, arranged at 90-degree intervals). Also, every time we stop the machine to enter the quenching chamber of the gasifier for inspection, we find severe scaling on the walls surrounding the manhole; whereas there is little scaling on the walls of the quenching chamber at the location of the raw gas outlet opposite the manhole. What’s the reason for this? Could it be due to the different air flow speeds inside the quench chamber? Is it still due to one of the two water inlet pipes at the outlet of the lock-hopper pump being blocked (the outlet at the bottom of the cone of the gasification furnace where air enters the lock-hopper pump has two outlets, which are positioned exactly where the manhole and exhaust port of the gasification furnace are located)? The above problems occur both when an adequate amount of quenching water is supplied and when the amount of quenching water is low in the later stage. It doesn’t connect; I hope fellow sailors can help find out the reason. Thank you!