November 25, 2010 (One Question per Day)

Although the HPF method for gas desulfurization has advantages such as stable operation and high desulfurization efficiency, there are also many problems in actual production, which are described below. 1 Influence on catalyst performance: The performance of the catalyst not only directly affects the desulfurization efficiency of gas, but also influences the production costs associated with desulfurization. Normal operation was restored by replacing the catalyst. Therefore, it is important to choose a catalyst manufacturer with stable quality and a good reputation. Currently, there are many catalyst manufacturers, but few new products that offer better cost-performance for similar products. Furthermore, users also lack testing methods to directly assess the quality of catalyst performance. 2 Effects of tower blockage: It is generally believed that the HPF desulfurization process is less prone to tower blockage and has a certain self-cleaning capability, but tower blockage can still occur when problems arise in the system. Therefore, strict process control is necessary: the initial cooling temperature must be kept at 25°C, with a temperature difference between the initial cooling towers of less than 3°C. This ensures that the tar content in the gas after passing through the electrostatic tar catcher is less than 50 mg/m3, and the naphthalene content is less than 500 mg/m3. Selecting appropriate packing materials is also of great importance for maintaining the proper operation of the desulfurization system, improving its efficiency, and preventing tower blockages. 3 Effect of the amount of regenerating air: Regenerating air serves two purposes: it participates in the regeneration reaction and it floats the sulfur foam. The purpose of controlling the amount of regenerative air is to regulate an appropriate regenerative reaction time, thereby creating favorable conditions for the flotation of sulfur foam. Therefore, in practical operation, the fluctuation in the amount of regenerative air should not be too large. 4 Effects of ammonia concentration and reaction temperature: The HPF method is a desulfurization process that uses ammonia as a base source; it is essential to maintain a certain level of ammonia content in the desulfurization solution. 5 Effects of by-product salts and waste liquids: During the desulfurization process using the HPF method, by-product salts such as (NH4)2S2O3, NH4CNS, and (NH4)2S are inevitably generated. On the one hand, the formation of salts consumes some of the ammonia ； On the other hand, the accumulation of by-product salts in the desulfurization fluid affects the desulfurization efficiency and the proper operation of the system. Therefore, it is generally required to keep the total concentration of by-products below 350 g/L. In the HPF process, apart from a portion that is lost during sulfur melting, most of the by-products accumulate in the desulfurization solution. 6 The impact of regenerator off-gases and sulfur melting: Intermittent sulfur melting reactors are used for this purpose, but in practice, they result in high steam consumption and serious environmental pollution due to off-gases and waste residues. It is advisable to adopt more advanced processes such as continuous sulfur melting or membrane filtration to handle sulfur foam, thereby further improving the HPF method for coal gas desulfurization. The gas desulfurization process is a systematic issue. To ensure the long-term, stable, and efficient operation of the HPF method for gas desulfurization, on the one hand, process management must start at the source of gas purification, with continuous optimization and improvement of the entire desulfurization process ； On the other hand, catalysts with better cost-performance should be selected to reduce or minimize the impact of by-products on the desulfurization system, thereby further improving the desulfurization efficiency.

1. Temperature of the desulfurization solution and pH value of the solution 2. Circulation volume and mass of the desulfurization solution 3. Volume and pressure of compressed air 4. Type and concentration of catalyst 5. Structure of the desulfurization tower, packing material, and specific surface area 6. Content of by-products in the desulfurization solution