Problem with the addition of steam in powder coal gasification
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Everyone, I’ve heard that many coal gasification manufacturers no longer supply steam during operation; even when the plants are running normally, the amount of steam supplied is quite low. Could you please discuss what the main reason for not using steam is?
This post was last edited by tfx511024 on 2016-10-25 at 18:39. Can you believe that without the introduction of steam, the effective gases are mainly CO with a small amount of hydrogen? Transform again in the transformation section?
Current powder coal gasifiers are divided into two types: waste-heat boiler cooling and water cooling. For a gasifier in a waste-heat recovery process, a relatively larger amount of steam needs to be added to facilitate the production of H2 in the syngas ； For gasifiers that use a quenching process, the amount of steam that needs to be added can be relatively less, as the high-temperature raw gas undergoes a water-gas reaction with water during the water quenching process, thereby producing the desired H2 component.
In the few documents I’ve seen, very little steam is used in the design for dry powder. For example, one plant uses only 8.3 tons of steam for 696 tons of coal. Firstly, there is no problem from a principle standpoint: it is possible to use carbon dioxide as a conveying gas to replace steam as a reducing agent. The technology of gasification furnaces that use pure carbon dioxide and oxygen as gasifying agents is already well-established, and it is entirely feasible to do without steam as well. At the same time, a dry powder-based quenching process is used to supply water vapor; even with changes in the water vapor ratio, the catalyst functions properly at a level of 0.25. Of course, deep conversion isn’t possible in such cases, as there isn’t enough driving force for that, so producing methanol or methane is no problem. In this way, energy and water consumption are relatively low. The utilization efficiency of vapor transformation is definitely higher than that of a vaporizer; is it a catalytic reaction? This requires less investment than dry powder waste pot systems, and the operation is more stable. Oxygen and water consumption are lower than those of water-coal slurry. Even if it’s 40 kilograms against 80 kilograms, it should still not be lower than water-coal slurry. That’s probably how it is; I’ve never done any of the things mentioned, so please feel free to correct me.