Some suggestions for the desulfurization process using ammonia as a base source

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In the desulfurization process of coke oven gas, the HPF process using ammonia as the alkaline source is the most widely applied. Under this process, control must be strengthened regardless of the catalyst used; in addition to the standard requirements, attention must also be paid to various details. The following suggestions are drawn from actual on-site conditions and are provided for sharing only. 1. A gas pre-cooler must be installed before desulfurization in order to cool the gas temperature to 27–30°C. 2. Prevent the loss of ammonia during the pre-cooling process. 3. The presence of certain substances in the coolant causes blockages in the cooling equipment, affecting its heat exchange efficiency. 4. Consider ammonia supplementation methods from the perspectives of water conservation, energy saving, and pollution reduction. 5. Fully consider the driving force of the reaction during the absorption process. 6. Use the remaining ammonia water as the cooling water or make-up water for the direct-type pre-cooling tower. To reduce the temperature of the gas, this ammonia water should be cooled to 23–24°C; however, this is difficult to achieve in months with high temperatures. Using a spiral plate heat exchanger as an indirect cooling device presents the problem of blockage by tar and other substances. It is possible to use the cooled ammonia vapor wastewater instead as the make-up water for the pre-cooling tower, which helps to avoid frequent blockages in the pre-cooling heat exchangers. 7. Ammonia gas is directly introduced into the pre-cooling tower; due to the heat it carries, especially latent heat, this leads to increased local temperatures in the equipment, thereby accelerating corrosion. Additionally, it raises the temperature of the gas, which is highly detrimental to the cooling process in the pre-cooling tower. 8. When the desulfurization systems are operated in series, ammonia water can be added to the last system. Since the carbon dioxide and hydrogen cyanide levels in the gas coming from the previous system have been reduced, the pH value in the subsequent system increases significantly, thereby enabling the advantages of this series operation to be fully utilized.