The effect of water-coal slurry gasification pressure on gas composition

Pressure has little effect on the components of syngas, whereas coal slurry concentration and operating temperature have a significant impact on the effective gas content.

Pressure determines the residence time; how could it not be relevant?

This post was last edited by defeil on 2017-5-11 09:55. The effect of gasification pressure on the coal gasification reaction: Gasification pressure/Mpa; Composition of syngas/(vol,%) – CO, H2, CO2, CO+H2. At 3.1 Mpa, the values are 48.37%, 30.87%, 20.23%, and 79.24% respectively; at 3.6 Mpa, they are 48.36%, 30.87%, 20.23%, and 79.23%; at 3.9 Mpa, they remain 48.36%, 30.87%, 20.23%, and 79.23%; and at 4.1 Mpa, they are still 48.36%, 30.87%, 20.23%, and 79.23%. As can be seen from these data, as the gasification pressure increases, the concentrations of CO, H2, and CO2 hardly change. Within the pressure range considered, gasification pressure has no impact on the results of the gasification reaction. The reason why pressurized operation is commonly used in coal gasification processes is that it increases the concentration of reactants, accelerates the reaction rate, and improves the efficiency of gasification； Pressurized gasification helps improve the atomization quality of water-coal slurry ； It reduces the size of the equipment, increases the gas production per furnace, and facilitates larger-scale implementation ； Pressurized gasification can reduce compression power consumption.

Is the effect of reaction equilibrium ignored when the pressure is increased?

Is the parameter provided here for water-coal slurry gasification? Is the CO2 content already at 30%? Dry coal powder gasification also cannot reach this level; the CO2 output from 40-kilogram Ruhr-type furnaces is unlikely to reach 30 either. Additionally, the sum of CO and H2 has reached 91.7%, and such an effective gas content can only be achieved with dry coal powder. And CO+H2+CO2 exceeded 100% by a large margin. Upon careful consideration, an increase in pressure has a suppressive effect on the increase in volume. The decomposition reactions of C and water vapor, whether into CO2+H2 or CO+H2, are both reactions that result in an increase in volume. Therefore, I think that, with all other conditions remaining constant, an increase in pressure will lead to a decrease in the hydrogen content in the gas, while the water vapor content in the gas exiting the combustion chamber will increase after the reaction. Furthermore, the incomplete combustion of C is a reaction in which the volume increases, whereas the complete combustion of C is a reaction in which the volume remains unchanged. Furthermore, in the reaction where C reacts with water vapor to produce CO2 and H2, the reaction volume coefficient increases only from 2 to 3; whereas in the reaction where C reacts with water vapor to produce CO and H2, the reaction volume coefficient increases from 1 to 2. In terms of the magnitude of this change, an increase in pressure has a greater inhibitory effect on the reaction that produces CO. So I think that, with all other conditions remaining the same, as pressure increases, both hydrogen and CO in the gas will decrease, while the CO2 content will increase.

Actually, we can make an assumption: how can pressure increase? If the slag outlet is blocked, could the gasification pressure increase? As we all know, a blocked slag outlet leads to changes in the composition of the raw gas

The slag port pressure difference is usually normal and stays below 100 KPa. It seems that there is also an interlock mechanism that triggers a shutdown when the slag port pressure difference exceeds 100 KPa; in such cases, either a manual shutdown or an automatic interlocked shutdown occurs. Or, even before reaching 100 KPa, center oxygen is already used to pull the flame and slag. Therefore, in practical operations, it is somewhat difficult to determine the effect of pressure changes on gas composition by observing slag port blockages.

Are these data your actual production operation data?

Is there something wrong with the numbers in the first sentence that you saw? Hehe

I’m not mistaken; there were indeed problems with the gas composition earlier, but upon checking again, it has been edited and corrected once more