Shell gasifier; calcium sulfite (calcium sulfate) is used as a cosolvent instead of limestone powder
Thread Content
The Shell gasifier uses limestone as a co-solvent, which is applied to coal types with a relatively high ash melting point in order to lower it. After the high-temperature decomposition of limestone, the active component is calcium oxide; the same holds true for calcium sulfite (calcium sulfate) after high-temperature decomposition, as calcium oxide is also obtained. The exact mechanism behind this is not very clear, so I would like everyone to analyze and discuss whether it is possible to use this substance as a complete substitute for limestone Make a comparison of the impacts of the gases produced after decomposition, namely carbon dioxide and sulfur dioxide, on the gasification furnace as well as on the downstream processes. I’m not familiar with technical aspects; the idea is to make use of solid waste desulfurization ash (calcium hydroxide gypsum produced by semi-dry desulfurization methods). I hope experts can offer some guidance:victory:
This post was last edited by Tianya Langji on 2019-9-11 at 15:51. Technically, it is possible to use desulfurization waste to replace limestone powder, with only the calcium content in it being utilized to adjust the melting point of coal ash. In terms of engineering, facilities need to be added for storage, drying, and transportation. The amount of desulfurization waste is small, and it only becomes economically viable when it is accumulated; the wet desulfurization products need to be dried before they can be transported by pneumatic means to dry coal mills (if wet gasification is used, the issue of proportioning can be resolved simply). As for what happens after entering the gasifier, the calcium component combines with silicon, magnesium, and others to form a glassy substance that ends up in the ash; this does not result in an increase in carbon dioxide emissions, or the amount produced is negligible. However, hydrogen is consumed to form water. In a reducing atmosphere, sulfur dioxide is not produced; only hydrogen sulfide is generated. The formation of hydrogen sulfide is advantageous when using coal with a lower sulfur content, as it facilitates the conversion process. Therefore, its effect is merely that calcium sulfite (calcium sulfate) contains more oxygen and sulfur, thereby consuming a small amount of hydrogen. The original poster needn’t worry; just move forward boldly to keep the solid waste from leaving the factory :)
Thank you to “Tianya Langji” for their participation and guidance. The desulfurization ash produced by the semi-dry method of calcium hydroxide desulfurization is in a dry powder form; compared with wet limestone desulfurization, the drying step is omitted, allowing it to be loaded and unloaded directly using tank trucks. If desulfurization ash is used to replace limestone, do the production process parameters need to be adjusted? The gasifier project is part of a project for the clean utilization of high-sulfur coal; the sulfur content in the coal isn’t very low. It’s not clear whether the desulfurization ash will affect downstream production processes The amount of desulfurization ash in this solid waste is not large, accounting for about 20% of the limestone powder used; therefore, it is sufficient if it can replace part of the limestone powder without any changes to the production process. For convenience, send a private message with your contact details, or use my WeChat: 57206283