What causes the pressure difference fluctuations in GE water-coal slurry vaporization burners?
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With the gasifier operating at a load of 900 revolutions per minute, and after the GE coal-water slurry burner had been in use for 7 days, the pressure difference across the burner began to drop frequently, from 300 KPA to 100 KPA, before rising again quickly; such fluctuations occurred on multiple occasions. On-site inspections showed that the pressures indicated by the two pressure gauges at the outlet of the coal-slurry pump and at the point where the slurry entered the furnace also decreased accordingly. However, the flow rates indicated by all three electromagnetic flowmeters remained normal. The CH4 online analyzer showed a rapid decrease in levels, along with an increase in oxygen content. Sometimes, the pressure difference across the burner would drop to 50 KPA and take around 30 minutes to recover to normal levels. The two more serious incidents were when the burner pressure difference dropped to a negative value, forcing a manual shutdown. Upon stopping the machine and checking the check valves at the inlet and outlet of the slurry pump, no abnormalities were found.
The burner pressure difference in water-coal slurry gasification generally refers to the difference between the pressure of the high-pressure coal slurry and the pressure in the gasifier. It is related not only to the burner but also significantly to the pressure and flow rate of oxygen. Therefore, first of all, the original poster should check whether the burners themselves are already worn out; this is a factor that needs to be ruled out first. 2. Please have the original poster check whether there are any significant fluctuations in oxygen pressure or flow rate when the burner pressure difference decreases. Because an increase in oxygen pressure leads to an increase in the oxygen flow rate, creating an effect similar to that of a vacuum pump at the tip of the burner, which results in a decrease in the pressure difference across the burner. 3. As described by the poster, only the burner pressure difference decreased, while the slurry flow rate remained unchanged; however, the methane content decreased, which indicates an increase in the oxygen-to-coal ratio. It is likely that fluctuations in the oxygen flow rate caused the variations in the burner pressure difference.
Could the poster please explain the status of the process burner? Only then can I help analyze it for you.
Reply to 3# Qianli Bù Liú Xíng: At that time, the oxygen pressure remained stable while the flow rate increased; the system pressure was also stable. The oxygen supply at the center was 4600 kg, and the pressure difference between the oxygen in the burner and the combustion chamber of the gasifier was 1600 kPa. The burner was in good condition, as it had only been in use for about a week! The cause has not been identified, which is very confusing; it has become a bottleneck in production.
Pay attention to the quality of the slurry – it’s possible that something is stuck in the check valve. When you stop the machine, you flush the pipelines before removing the slurry pump, so you won’t notice anything. Since methane levels are dropping, it must be that there is less coal slurry, and yet your electromagnetic flowmeters are not detecting this change; in my opinion, this is a potential problem.
Reply to 5# qihuajingling: If there are iron pieces in the slurry, shouldn’t the burner pressure difference decrease?
Reply to 7# qihuajingling: The key is to calibrate the 3 electromagnetic flowmeters multiple times; they are very sensitive to changes in volume, so it’s really hard to detect any abnormalities! It’s hard!
After inspection, the burner appears normal, as expected; I understand now. I also want to know what the coal slurry flow rate is per furnace at full load in your gasification units? Please let me know.
Reply to 9# Qianli Bu Liuxing: Texaco, 8.7 MPa; the amount of slurry fed per furnace at full load is 36 m3
Pay close attention to see if there are any leaks in the return pipeline or elsewhere in the slurry pipeline I also think that all three slurry flow meters are accurate; the amount of slurry should not decrease – after all, there is a difference between the amount of slurry entering the burner and the slurry flow rate. However, a decrease in the burner pressure difference may be due to a reduction in the amount of coal slurry fed into the burner. As the amount of coal slurry decreases, the resistance to oxygen flow is reduced, resulting in an increase in oxygen flow rate. As a consequence, the oxygen-to-coal ratio in the furnace increases significantly (although this might not be detectable by instruments), leading to changes in the composition of the process gas. I hope experts can help clarify this. . .