Technical measures for desulfurization, purification, capacity expansion and efficiency improvement of coke oven gas

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The desulfurization and purification of coke oven gas is a systematic aspect of technical management, and it represents an essential part of the coking production process. By carrying out necessary technical upgrades to adapt to changes in production demands, it is possible to reduce the intensity and risks associated with management, while also supporting the company’s efforts to achieve energy savings, reduced consumption, and lower carbon emissions. Currently, the desulfurization and purification of coke oven gas relies primarily on the traditional HPF desulfurization process, using cobalt-based desulfurization catalysts of the PDS type. The HPF method for desulfurizing coke oven gas boasts high stability and decent desulfurization efficiency. However, it still faces issues such as being constrained by the properties of the catalyst, requiring larger process equipment that leads to high investment costs; low working sulfur capacity resulting in excessive circulation volume of liquid in the desulfurization tower, and thus high operating costs. At the same time, as coking capacity continues to increase and there is a tendency to use coals with higher sulfur content in production, the existing systems exhibit the drawback of insufficient flexibility. In such cases, to improve the operational stability of the desulfurization system, a capacity expansion and efficiency improvement upgrade of the wet oxidation desulfurization purification system for coke oven gas is a practical technical solution. (1) The desulfurization system is equipped with high-sulfur-capacity desulfurization catalysts of excellent performance. A higher sulfur-removal capacity means not only a greater amount of hydrogen sulfide that can be removed using the same volume of circulating liquid, but it also allows for a reduced volume of circulating liquid to achieve the same level of hydrogen sulfide removal. In actual production, when the production load increases or the hydrogen sulfide load in the gas rises, the use of desulfurization catalysts with a high sulfur tolerance helps to avoid overloading the system, thereby facilitating the stable operation of the desulfurization system and enabling adjustments to meet production demands. (2) Under the operating conditions of the desulfurization rich liquid volume-enlarging and absorption modification catalyst with high sulfur capacity, the desulfurization rich liquid that has absorbed hydrogen sulfide, especially that from the secondary desulfurization process, still retains a remaining working sulfur capacity for absorbing hydrogen sulfide; it can therefore be used as a desulfurization liquid for pre-desulfurizing gas ； It is also possible to use specialized reactors; especially when the hydrogen sulfide content in the gas is high, selecting such desulfurization-rich liquids for pre-desulfurization of the gas can reduce the desulfurization load on the conventional desulfurization towers used later on, thereby improving the purity of the gas after desulfurization. (3) The combined renovation of high-efficiency reactors and conventional desulfurization towers results in the hydrogen sulfide content in the gas depending on the sulfur content of the coal used. When high-sulfur coal is utilized, the desulfurization load on the desulfurization system increases. Additionally, as coking capacity expands and becomes more centralized, the volume of gas that needs to be processed by each desulfurization tower grows larger. With conventional desulfurization catalysts, the size of the tower equipment also increases, and an increase in tower size inevitably leads to higher requirements for mass transfer. In such cases, choosing a desulfurization reactor with a high liquid-to-gas ratio and efficient mass transfer as the primary desulfurization tower, and subsequently incorporating a conventional packed-bed desulfurization tower or a flexible combination of various desulfurization and mass transfer devices, not only allows full utilization of the catalyst’s high sulfur capacity, thereby improving desulfurization efficiency, but also reduces the investment costs and operational energy expenses for enterprises. This approach is also suitable for technical upgrades and process optimizations of existing desulfurization systems as well as new ones.