Problems with black water and gray water from coal water slurry gasification!
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The water produced by our gasification furnace is alkaline, but we do not add any alkaline substances such as ammonia during the pulping process. Why is the water alkaline? What are these alkaline substances, and where do they come from?
For the NH3 formed during the gasification process, try reducing the flow at the points where high-pressure N2 gas is supplied, and see if the ammonia nitrogen level in the system remains high.
The ash itself is a mixture of basic and acidic oxides; therefore, it is not surprising that the black liquor becomes alkaline when fluxes such as CaO are added during pulping.
It’s possible that ammonia was generated during the production of syngas; check whether the alkaline substance is ammonia
I think it must be an additive, because additives are generally strongly alkaline, which is why this happens.
What was said on the 2nd floor makes sense: when the upper part of the lock chamber gets blocked, HN backpressure may be used, and N gas used in other places can form NH3
May I ask the original poster: what type of gasification furnace are you referring to? Logically speaking, no excessive alkaline substances should be added to your coal slurry; however, adding too much dispersant in the ash treatment stage could also cause this problem. But generally, it will not become alkaline. You had better take new samples for analysis, and it would be best to analyze the main components of the alkaline substances.
In my opinion, alkalinity is caused by the ammonia generation in the vaporization reaction, and it is closely related to the presence of nitrogen. Nitrogen itself is difficult to dissolve in water, and it is also hard for it to dissociate in water; thus, the formation of ammonia is even more difficult. It cannot be said that this factor does not play any role, but I think its impact is minimal. Please, esteemed teachers, point out any mistakes in my view!