Why is the hydrogen concentration in the process gas at the outlet of the gasifier high?
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Recently, in the composition of the process gas at the outlet of our gasifier, the hydrogen content has been above 36%, with values as high as 37%; the content of useful gases is also low, at around 80%. Please analyze it – what’s going on here? Furnace type: coal water slurry gasification furnace. Coal type: Shenhua
I wonder how the data you usually process looks like? But based on your hydrogen data, it’s not high; the manufacturers I’ve worked with that use Shenhua coal have a higher H2 content than yours, and the proportion of usable gas is also around 80%. So if you think the H2 content is high, please first provide your actual operating data.
Basically, hydrogen makes up 35%, with fluctuations of no more than 1%; carbon monoxide is between 44% and 46%
Well, it’s mainly a matter of operation; I think the CO2 level during normal operation should be well controlled, probably below 20%, and possibly even below 18%. So, if the H2 content increases, does that mean the CO and CH4 contents decrease while the CO2 content increases? This may be related to slight blockage at the slag vent, improper spraying from the burner, and a slight increase in the oxygen-coal ratio; it is recommended to conduct inspections in these areas.
Based on the nature of the reaction process, an increase in temperature and a decrease in pressure lead to an increase in the levels of CO and H2; it is not clear what the trend will be for CO； From past experiments, it’s possible that the instability in the oxygen to water-coal slurry ratio is caused by the pipes and nozzles
H2 is greater than 36, and CO is less than 45; this is mainly related to the operating temperature (excluding equipment-related factors). Adjustment can be made with reference to methane and CO2 levels.
This post was last edited by GSP on 2009-8-28 09:44. I agree with Comrade Li from the sixth floor – the temperature is too high! It is estimated that CO2 levels are also high; temperature variations affect the decomposition rate of water vapor, resulting in an increase in hydrogen content. I recently calculated such data, and my conclusion is that the decomposition rate of water vapor has a significant impact on fluctuations in hydrogen content. An effective gas content of 80% is not bad at all; the hydrogen content of 37% is a bit high, but it’s not that extreme either. This is because we’re used to seeing values around 35%, haha.
It’s normal; it’s difficult for Texaco’s effective gas content to reach 80%
GSP, what you said above isn’t quite correct; usually we’re at 81%, and it hardly ever goes below 80%. So this time it’s a bit abnormal, and we find it strange. Later, we adjusted the oxygen-to-coal ratio slightly, and things returned to normal
For the gasification reaction, it is important to control the furnace temperature appropriately. The furnace temperature is too low, resulting in a low conversion rate of carbon, which is not economical ； A too high furnace temperature facilitates the conversion of carbon, but it has a significant impact on the refractory bricks and the composition of the gases. If the type of coal remains constant, a higher furnace temperature increases the rate of steam decomposition, resulting in an increase in the H2 content in the effective gas mixture. By appropriately adjusting the oxygen-to-coal ratio, that is, by maintaining an appropriate furnace temperature, a relatively ideal composition for the effective gases can be achieved.