Reasons for overheating of the lockhopper in the Texaco gasifier

Since high-pressure gray water is used for the lock-hopper stamping, this can affect the temperature curve of the lock-hopper; the issue may lie in poor slag discharge or slag accumulation, or it could be due to insufficient water volume.

It must be that the slag discharge system is not functioning properly, such as slag accumulation at the slag outlet and downcomer.

This post was last edited by wang06120325 on 2015-7-5 at 10:38. If slag discharge is not smooth or there is a problem with the frame bridge lock hopper, its temperature should decrease. Additionally, the flow rate in the gasifier’s sludge discharge pipeline will experience significant fluctuations. The current consumption of the slag skimmer can also be monitored. The person who posted above only mentioned an increase in the hopper temperature; it’s difficult to determine what the status of other process parameters is. It’s possible that the thermometer is malfunctioning, but the likelihood of both devices failing at the same time is almost zero. In my opinion, the rise in the temperature of the lockbox is ultimately caused by an excessively high temperature of the black water in the quench chamber of the gasifier. The person asking the question can also check the thermometer on the black water pipeline of the gasifier to see if there is a trend of increase in temperature in the short term. The possible reasons for the high temperature of the black water in the quenching chamber are as follows: 1. The amount of water used for quenching is not adjusted in a timely manner when the load on the gasification furnace increases; 2. There may be large fluctuations in the oxygen-to-coal ratio in the gasification furnace, and these fluctuations are not addressed promptly; 3. The amount of black water discharged from the gasification furnace is too small, preventing the heat generated therefrom from being removed; 4. The high temperature at the inlet of the quenching water pump results in suboptimal heat exchange efficiency in the gasification furnace. 5. Compared to the previous coal type, this coal variety has a higher calorific value; in such cases, the system’s thermal balance is prone to being disrupted, so it is essential to be vigilant against water entering the gasifier.

As a supplementary point, regarding the overheating issue mentioned above, I’m not sure what the temperatures are on both thermometers in the lock box; by how much do they exceed the normal levels? The temperature in our area during the locking process is around 60°C; it drops a bit after slag removal. I’m not sure if the people upstairs have made any adjustments to the outlet flow rate of the lockhopper circulation pump recently; increasing that outlet flow rate would also cause the temperature of the lockhopper to rise compared to before. This phenomenon also occurs because, after increasing the circulation rate, the heat from the gasifier quench chamber is carried to the lockhopper.

You didn’t explain the specific circumstances clearly; there are many reasons for high temperatures, and it’s necessary to determine the cause based on the specific situation

First, check whether the flow rate of the lockhopper circulation pump has increased; then examine whether there is internal leakage in the lockhopper pressure relief valve and the slag discharge valve. If there is internal leakage, the hot water from the quenching chamber will flow down, causing the temperature in the lockhopper to rise.

It must be caused by internal leakage in the valves; go and measure the temperatures before and after valves 10, 13, 14, and 15

Reasons for the increase in the temperature of the lock hopper: First, the flow rate of the pump used in the lock hopper circulation is too high, which causes heat from the quenching chamber of the gasification furnace to be transferred to the lock hopper, resulting in an increase in its temperature； II. The amount of black water discharged from the gasification furnace’s quenching chamber is low; the ash and water form a viscous fluid, and the temperature in the quenching chamber gradually rises. Water presence has already occurred in the gasification furnace’s quenching chamber, resulting in an increase in temperature during the slag collection process in the lockhopper ； III. Cracking occurred at the weld of the downcomer in the gasification furnace, causing the gas to flow in a deviated direction and leading to an increase in the temperature of the lockhopper. (In 2007, in our company, excessive temperature control during the slag formation process resulted in cracking on one side of the downcomer in the gasification furnace; the gas flowed in a deviated direction, the temperature of the lockhopper remained high, and it became very difficult to remove the slag.)

A crack on one side of the downcomer in the gasifier can cause the gas to flow in a deviated direction, which may also lead to continuously high temperatures in the lockhopper

When the operating temperature of the gasifier is low, the fluidity of the ash in the gasifier decreases; the coarse ash particles become larger and form clumps. Ash particles with larger sizes spend less time in the quenching chamber where they exchange heat with water. As a result, those ash particles with higher internal temperatures remain in the quenching chamber for a shorter period of time before entering the lockhopper, where they continue to release heat. This leads to an increase in the temperature of the lockhopper, thereby increasing the oxygen-to-coal ratio and improving the fluidity of the ash while reducing its particle size