The main reasons for tower blockage in wet oxidation desulfurization

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There are several aspects: 1. The composition of the gas entering the desulfurization tower is poor, with a high content of impurities (such as fly ash, coal tar, and other solid particles) that clog the packing layer. 2. During the desulfurization reaction in the desulfurization tower, an oxidation-regeneration sulfur precipitation reaction also takes place. If the sulfur that is precipitated (especially when the H2S concentration at the inlet is high) cannot be carried out of the desulfurization tower along with the desulfurization fluid in a timely manner, it can easily accumulate on the surface of the packing, leading to local blockages and uneven flow; in severe cases, this can result in a blockage of the entire tower. 3. The spray density in the desulfurization tower is insufficient. The required value is generally between 50 and 60 m3/m2·h; a lower spray density not only leads to the formation of dry areas in the packing inside the tower, resulting in sulfur blockages, but it also **reduces the purification efficiency of the desulfurization tower. Especially for towers with larger diameters, it is essential to ensure an adequate amount of lean liquid. 4. The amount of air used for regeneration is insufficient, resulting in low blowing intensity (generally, it should be between 50 and 80 m3/m2·h), or the regeneration equipment is not appropriate. This situation inevitably makes it difficult to float sulfur bubbles in the regeneration tank, leading to a high level of suspended sulfur in the lean solution; prolonged operation can easily result in tower blockage. 5. There is a problem with the equipment structure of the desulfurization tower itself. If the filler is not selected properly, or if the structure of the tower’s liquid distributor and redistributor is unsuitable or installed incorrectly, this phenomenon can easily lead to uneven distribution of the solution or the accumulation of sulfur in the distribution channels, thereby causing blockages in the tower. 6. The concentrations of various salts formed as by-products are high; at low temperatures, these salts precipitate and can cause blockages in the tower. Under normal operating conditions, especially in plants with good management (where there are no leaks or spills), an increase in the amount of by-product salts in the desulfurization solution is understandable, as the absorption of H2S by the desulfurization solution involves simultaneous side reactions, which are inevitable. When the amount of by-product salts increases, it is necessary to take timely measures (such as discharging or removing some of the solution to facilitate cooling and crystallization) to prevent salt-related blockages. As for what level constitutes an excess, specific thresholds vary among different companies due to differences in operating conditions. We believe that the amount of by-products should not exceed 250 g/L; in particular, the concentration of Na2SO4 in the solution should generally not exceed 40 g/L. Exceeding these limits is not only a problem related to salt buildup but also leads to severe corrosion of the equipment. 7. Insufficient understanding of sulfur melting production management: shortages of steam for heating lead to the shutdown of sulfur melting equipment; improper operation or issues with the sulfur melting apparatus itself result in an increase in sulfur particles and foam in the residual liquid. Without proper precipitation, filtration, and separation, these substances are returned to the system, eventually causing blockages in the packing inside the tower. 8. Improper control of the components in the desulfurization solution, such as an imbalance in the ratios of tannin and vanadium, leading to the formation of S—O—V precipitates, or inadequate pretreatment of the tannin before it is added to the system. This leads to an increase in the particle size of the desulfurization liquid, making it easier for sulfur to adhere to the filler surfaces. 9. Impact of water quality. Some companies treat hard water, or other types of hard water flow into the sedimentation tanks and then into the system, causing blockages due to calcium, magnesium, and salts. 10. Improper selection of catalysts: We know that different types of catalysts exert varying effects in the catalytic oxidation process. In particular, the crystal structure of elemental sulfur formed after oxidation differs, which in turn affects its viscosity and particle size. If the viscosity of the elemental sulfur that is produced is high, it is essential to consider carefully how this sulfur adheres to the packing material or distributor inside the tower; care must be taken not to neglect any aspect. 11. Sulfur accumulation and blockage in the desulfurization tower demister. This kind of blockage is often overlooked by companies and is also the hardest to detect. Generally, when manufacturers measure the resistance of desulfurization towers, they only measure the pressure difference between the inlet and outlet of the tower. Of course, there are also manufacturers that can measure the pressure difference across each section of the packing. Generally, when a pressure difference is detected in a section of packing, it is determined that that section of packing or distributor is blocked. What is not known is that the reasons for the clogging of the demister are, on the one hand, the lack of cleaning over time, and on the other hand, severe entrainment of air bubbles, which leads to sulfur accumulation and clogging.