Slag accumulation at the quenching ring area of the water-coal slurry gasification furnace and the temperature-dependent properties of coal slag
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Gentlemen, has slagging occurred in the extreme cooling ring area? How to handle slag after it forms? Recently, slag accumulation has occurred in the quenching ring area (in the GE water-coal slurry gasification quenching process). Before the shutdown of the first furnace, there were fluctuations in the slag outlet pressure difference and in the gas composition, but the temperature in the lockhopper remained stable. After significantly increasing the oxygen-to-coal ratio (from 465 to 490), the gas composition stabilized, but the CO content remained high. After dumping the furnace, a stop was made for inspection; the quenching ring was intact with no leaks, and the cone bottom bricks were in good condition, though there was a large amount of slag accumulation in the area around the quenching ring. The second furnace also experiences fluctuations in the slag outlet pressure difference at present; there are no changes in the gas composition. However, the temperature of the lockhopper remains high (rising from 58 to 79 degrees). Even after increasing the oxygen-to-coal ratio (from 465 to 490), the gas composition stays stable, though the CO content is on the high side. Nevertheless, there is no significant improvement in either the slag outlet pressure difference or the lockhopper temperature. (The temperature of the lock hopper matches exactly the fluctuations in the slag outlet pressure difference); when the slag outlet pressure difference fluctuates, the temperature of the lock hopper rises, while when the pressure difference remains stable, the temperature of the lock hopper returns to its normal stable level. The exact reason is currently unclear; have the viscosity-temperature properties of the ash not been analyzed? Is it suspected that the viscosity-temperature properties of the ash are poor? (This has happened for the first time in the 8 years since the unit began operating; in previous instances, when the slag outlet was blocked, improving the oxygen-coal ratio for two days would resolve the issue, but this time there has been no improvement.) ）
The second furnace is likely suffering from slag accumulation at the lower part of the downcomer, with the serrations located a bit higher up
I’ve heard of slag accumulation – it’s dangerous, and even if it’s cleared to some extent, it only provides a temporary solution; the problem will reappear after a while. This happens because large fluctuations in the pressure difference at the slag outlet and in the temperature of the lock hopper indicate severe slag accumulation, which narrows the passages; once those passages are blown open again, slag accumulation occurs once more.
Today, respectively at low load with low central oxygen ratio and high oxygen coal ratio, and at high load with low central oxygen ratio and high oxygen coal ratio； Low load, high central oxygen ratio, high-oxygen coal ratio; high load, low central oxygen ratio, high-oxygen coal ratio ； Slag treatment experiments were attempted across four time periods. No significant effects have been seen yet. The furnace has been operating despite being faulty for over 20 days; hopefully it will improve by tomorrow.
I’ve learned it. I hope the original poster will continue to keep us updated on the progress!
How large is the fluctuation range of the taphole pressure difference? What is the range of fluctuations in the slag port pressure difference? By how much is the average slag port pressure difference higher than normal?
The fluctuation range is not large either; it’s just frequent, with values ranging between 31–39 kPa. This fluctuation in pressure difference is usually acceptable; this time, the carbon monoxide content in the gas produced increased from 44 to 46. After increasing the oxygen-to-coal ratio significantly, the carbon monoxide level failed to drop, and at the same time the temperature in the lockhopper was high.
What is the range of the composition of CO2 gas, and is it fluctuating or stable? The slag tap differential is within normal levels, and there is no issue with the fluidity of the molten slag; it is recommended to consider the coal type or slurry parameters