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The desulfurization of coke oven gas involves removing hydrogen sulfide from it, as well as other acidic gases such as hydrogen cyanide. Due to the strong corrosive nature of these acidic gases, by-products are also generated during the production process; high levels of these by-products can cause severe corrosion, leading to problems such as equipment perforation. Therefore, manufacturing companies pay close attention to the corrosion issues associated with desulfurization equipment. Most desulfurization equipment in domestic coking plants is made of carbon steel, especially desulfurization towers. In addition to ensuring proper internal and external anti-corrosion treatment of the equipment itself, it is also necessary to properly control the desulfurization process, which helps to keep corrosion in the desulfurization system at a low level. There are many factors that affect the corrosion rate associated with desulfurization, and these factors lead to an increase in the corrosion rate. The analysis is carried out from the following 4 aspects. 1. First of all, the alkalinity value of the desulfurization solution is directly related to the corrosion rate. In other words, the acidic gases H2S and HCN present in coke oven gas need to be neutralized by sufficient hydroxide ions (OH-) in the desulfurization solution, thereby making the solution slightly alkaline. The alkalinity level indicates the amount of hydroxide ions in the solution; if the alkalinity of the desulfurization solution decreases, the acid-base balance shifts toward acidity, and the corrosion rate of the solution increases. Conversely, increasing the alkalinity level reduces the corrosion rate significantly. In a normally operating system, the alkalinity value is directly related to the solution temperature and the content of acidic gases in the gas. Corrosion increases as a result of rising operating temperatures. As an example, in a coking plant in the south, during January to August 2024, the average temperature of the desulfurization lean solution was 35°C, with an average alkalinity level of 0.44 mol/L. On August 26, 2024, changes occurred in the production system; the average temperature of the lean solution rose to 37.7°C, while the average alkalinity level dropped to 0.36 mol/L. The average temperature of the lean solution increased by 2.7°C, and the average alkalinity level decreased by 0.08 mol/L. Meanwhile, the corrosion rate increased by 0.2 mm/s, representing an increase of nearly 30%. Therefore, as the operating temperature of the ammonia-based desulfurization system increases, dissolved ammonia escapes more rapidly; a decrease in alkalinity leads to an increased corrosion rate of the lean solution. An increase in the content of acidic gases in coke oven gas also leads to increased corrosion. During the production process, if the sulfur content of the coal used in the upstream coke ovens increases, then the levels of hydrogen sulfide and hydrogen cyanide in the gas rise accordingly; however, the ammonia content in the gas remains constant. This results in an increase in the ratio of acidic gases such as hydrogen sulfide and hydrogen cyanide to ammonia. With more acidic gases and less ammonia, the alkalinity of the desulfurization solution drops rapidly, which is another factor contributing to the decrease in the solution’s alkalinity. When the process changes in the desulfurization system are not sufficient to maintain its own alkalinity level, it is necessary to add a certain amount of alkali source to raise the system’s alkalinity to the specified range. 2. Secondly, during the regeneration process, an excess of oxygen leads to increased corrosion. Oxidation corrosion in the desulfurization system cannot be ignored. When the desulfurization reaction equation for coke oven gas is simplified, it can be understood as hydrogen sulfide reacting with oxygen in the presence of a catalyst to produce elemental sulfur and water, while heat is released in the process. The amount of hydrogen sulfide present in the gas requires a corresponding quantity of oxygen in order to completely remove it; taking into account the efficiency of oxygen utilization, in practice it is necessary to ensure an excess of air. When the production load is reduced significantly to 50% or when the furnace temperature is kept lower, the desulfurization unit operates in single-system mode. The circulation rate in the regeneration tank must be sufficient to ensure the minimum amount required for the flotation of regenerated sulfur foam, and a proper spraying density in the desulfurization tower also needs to be maintained; under such conditions, the amount of air drawn in is far greater than what is actually needed for desulfurization. At low load levels, excessive dissolved oxygen is carried into the lean solution tank during the regeneration process, increasing the oxygen corrosion rate of carbon steel. This is a problem resulting from a mismatch in the process under low load conditions, and it needs to be addressed by increasing the alkalinity of the solution. 3. Third is the tri-salt corrosion in the desulfurization liquid. The increase in salt content in the desulfurization liquid used for coke oven gas desulfurization is also a cause of increased corrosion. The three salts—thiocyanate, sulfate, and thiosulfate—are all sulfur-containing compounds; once they ionize in the desulfurization solution to form thiocyanate ions, sulfate ions, and thiosulfate ions, they exhibit weak acidity. An increase in these three salts necessarily leads to an increased corrosion rate during desulfurization. To control the three-salt content and reduce the corrosion rate, it is first necessary to manage the desulfurization reaction properly and control the conversion rate, ensuring that hydrogen sulfide is completely converted into elemental sulfur within the desulfurization tower and reaction tank. This prevents divalent sulfur from entering the regeneration tank and reacting with oxygen to form by-products. However, no reaction can occur without side effects; therefore, in daily control, the “zero waste liquid” technology can also be utilized to maintain the tri-salt content in the desulfurization liquid at a stable level, while completely eliminating the desulfurization waste liquid. 4. Finally, corrosion caused by unstable catalysts. There are many types of catalysts for desulfurizing coke oven gas, such as salicylic hydroquinone, PDS, complexed iron, etc. During operation, the instability of the catalyst causes the metals within it to lose their protective groups and become free, where they combine with the carbon elements in carbon steel to initiate electrochemical corrosion. Catalysts fall within the category of fine chemicals, and their formulations are constantly being improved. While the main components may remain unchanged from batch to batch, the auxiliary components can vary. Especially in some small manufacturing enterprises where strict control over the production process is not exercised, it is difficult to ensure the stability of the catalysts; as a result, there is a possibility that the corrosiveness of these catalysts increases when their products are used. In such cases, it is necessary to choose well-known, highly capable catalyst manufacturers with R&D capabilities, in order to avoid increased corrosion in the system due to unstable catalysts.