Regulation ideas and methods for severe liquid carryover in sulfur foam during coking desulfurization

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This post was last edited by Steven_p0kTk on 2024-1-11 at 09:27. With the gradual adoption of iron complex catalysts in the desulfurization processes within the chemical production sections of coking plants, an increasing number of coking enterprises are making use of these catalysts. Currently, the replacement of catalysts is carried out in a rather simplistic manner; however, given that iron complex catalysts originally exhibited compatibility issues when used together with the HPF process, their combined application will inevitably lead to conflicts and a range of problems. Regarding the issues of foam collapse and excessive liquid carryover in sulfur foam, it is possible to adjust the conventional approach, thoroughly identify the root causes, and take targeted measures to address them. In the HPF desulfurization process, which uses ammonia as the alkali source, the use of a complexed iron catalyst makes it prone to the phenomenon of sulfur foam becoming weak over time. The main reason is that the preceding process introduces a large amount of light tar. In contrast to PDS catalysts, which require substantial liquid discharge for replacement, the amount of liquid discharged from the iron-complex catalyst **is reduced or even nonexistent**. As a result, the tar brought into the desulfurization system by the syngas gradually accumulates; this quantitative change eventually leads to qualitative changes. After this problem occurred, some manufacturers followed the original PDS approach, primarily by reducing the circulation rate and the volume of regeneration air. This method proved somewhat effective in the short term; however, over time it became evident that as the volume of regeneration air continued to decrease, the circulation rate failed to increase. Eventually, this led to a vicious cycle, resulting in an uncontrollable surge in the formation of by-products, a decline in desulfurization efficiency, blockage of the spray nozzles and packing material in the desulfurization tower, ultimately forcing the tower to be shut down for maintenance. This has led to an increasing number of negative evaluations of complexed iron by coking enterprises, adversely affecting its promotion and application. Through a comparative analysis of the differences in foam formation after using complexed iron in both ammonia-based desulfurization and post-alkaline desulfurization processes, we found that the root cause of this problem is not related to the catalyst itself, but rather to tar impurities introduced at the initial stage of the desulfurization process. To address this issue, we conducted reverse engineering and found that a phenolic substance in the tar is the main culprit behind the formation of weak foam. Controlling or reducing the entry of such substances into the desulfurization system is the key to resolving the problem of weak foam formation. On this basis, our company conducted an analysis by integrating the coking chemical production process as well as the upstream and downstream aspects of desulfurization, thereby identifying the main source facilities. In conjunction with coking technology experts, we carried out on-site investigations. Ultimately, we determined a solution, which became part of the technologies related to the adaptability of complexed iron-based desulfurization in the coking industry—namely, the “technological retrofit for controlling impurities in the upstream process.” This retrofit has been successfully implemented in several projects, yielding notable improvements. In addition, we will continue to analyze and research various compatibility issues associated with coking complex iron desulfurization, so as to develop a complete set of technical process packages.