Relationship between pressure difference at the slag outlet of the gasifier and furnace temperature
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Hello, seniors. I’m a newcomer to gasification. Recently, our company’s 1.5mpa four-nozzle furnace. Recently, due to a change in our slurry concentration from 57 liters to 60 liters, our furnace temperature dropped, falling from 1300 degrees to 1230 degrees, at an operating load of 83 percent with an average slurry flow rate of 10. At 2 m3/S, the oxygen-coal ratio is normally controlled at 500 to 505, with a pressure of 1. The slag port pressure difference is around 34 KPA at 35 MPa. Wall temperature 226°. As the furnace temperature continued to drop while the slurry concentration increased, I raised the oxygen-to-coal ratio to 520 and the central oxygen level from 17 to 17.2. At this point, the furnace temperature could be increased to around 1250°, the pressure difference at the slag outlet rose to 43 KPA, while the wall temperature remained around 226°. The temperature of the black exhaust gas increased by 1°. When the oxygen-to-coal ratio was further increased to 525, the pressure difference rose by 50 KPA. In the absence of supervision, I was concerned that more slag might accumulate at the slag outlet, so I reduced the ratio back to 520; as a result, the pressure difference at the slag outlet dropped to 46 KPA, the wall temperature fell from 1300° to 1260°, and the wall temperature itself dropped from 225° to 203°. My judgment is that the slag sticking to the wall caused the wall temperature to drop. The next day, the engineer came and suggested reducing the oxygen-reducing coal ratio to 520, lowering the pressure to 1.25–1.3, and decreasing the liquid level in the gasification furnace by 3.9 meters. Is the purpose of lowering the pressure to reduce the speed at which the slag on the wall flows downward? How should we balance changes in the slurry concentration with furnace temperature and pressure? As the slag port pressure difference increases, we raise the temperature to melt the slag on the wall; however, this slag accumulates at the slag port, further increasing its pressure difference. How should we proceed? I would appreciate some guidance from those with more experience
If the furnace temperature is accurate, it is necessary to control it; one should not rely solely on the oxygen-coal ratio. Other factors should be considered once the furnace temperature is stable.
A decrease in the slag port pressure difference due to a reduced oxygen flow rate is a normal phenomenon. Reducing pressure is merely to increase the gas flow rate. Pressure has a certain impact on the displayed value of the furnace temperature. An increase in the taphole pressure difference indicates that blockage of the taphole has occurred. During normal operation, the response time of the slag sample is faster than that of the slag port pressure difference. Although the gas composition also changes, the gas generation is only for reference and cannot determine whether the current operating temperature is appropriate.
Furnace temperature control mainly depends on the viscosity-temperature characteristics of the ash. If the ash fusion point is high, the furnace temperature must be increased.
Why can increasing speed be achieved by reducing pressure? I don’t quite understand