How is the operating temperature for gasification determined?
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In the gasification process, the operating temperature varies depending on the process used. The Texaco process uses furnace bricks; the closer the T4 flow temperature of the coal slurry is to the operating temperature, the better, as this reduces the ablation of the furnace bricks and extends their service life. Gasification furnaces equipped with water-cooled walls require slag formation in order to use slag as a protective layer for the water-cooled wall coils. However, in order to increase the carbon conversion rate, the temperature in such furnaces is raised. While a higher operating temperature does lead to an increased carbon conversion rate, it also increases the fluidity of the slag, making it less suitable for serving as a protective layer. What is the relationship between the normal operating temperature and the flow temperature in a water-cooled wall gasifier, and what value is appropriate for control?
Judgment can be made based on the heat flux of the water wall; at the same time, attention should also be paid to factors such as the slag port pressure difference and the slag discharge pattern in the lock hopper, in order to make judgments or adjust the furnace temperature
Under normal circumstances, water-cooled wall gasifiers use coarse coal with high ash content and high ash melting point; therefore, the operating temperature is definitely higher than that of ordinary gasifiers. The key factors are the composition of the gases, the pressure difference at the slag outlet, and the heat balance calculations for the water-cooled wall
If a large amount of coal is fed, there’s no need to worry about slag accumulation on the water wall; haha, it’s difficult to remove slag in such cases anyway
Whether slag forms is related to the viscosity-temperature properties; one should consider the operating range for coal at a viscosity of around 20 PA·S – a wider range makes operation easier, while a narrower range tests the operator’s skills