Problems with sulfur foam flotation in desulfurization systems

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In the coke oven gas desulfurization system, the process of sulfur foam formation and regeneration involves the desulfurization liquid containing numerous bubbles flowing within a regeneration tank or regeneration tower, where these bubbles form numerous bubble clusters inside the equipment. Driven by their own buoyancy, the bubble clusters float upward, while elemental sulfur present in the solution gathers around the bubbles and adheres to their surfaces. As the bubbles rise, they become smaller and more numerous, with correspondingly more elemental sulfur adhering to their surfaces. This **improves the flotation capacity of elemental sulfur while maintaining a stable liquid level. In a regeneration tank without a distribution plate, as bubbles rise from the bottom upward, the pressure acting on them decreases, causing their volume to increase. This can lead to vigorous agitation of the solution in the tank, and the bubbles that rise to the surface tend to break easily, failing to form a stable foam layer. As a result, less elemental sulfur is carried away, which affects the efficiency of regeneration. This situation mainly occurs in tall towers with poor distribution effects. The formation of air bubbles and numerous soap bubbles in the desulfurization system is an abnormal phenomenon associated with sulfur foam flotation; if not corrected in time, the problem can become quite serious. Common causes include a dirty desulfurization solvent system, and cleaning is an essential part of maintaining such systems. The desulfurization solvent system experiences dissolution and emulsification due to changes in coal type, excessively high furnace temperatures, and hydrocarbons carried in the gas from other sources; this leads to a high surface tension and the formation of bubbles. Prolonged use of the desulfurization solvent or too high a temperature of the heating steam source results in an excessive amount of degradation products ； Or, if no fresh solvent is added for an extended period, the antifoam agent present in the solvent is lost and cannot be replenished in a timely manner. Other types of rainwater, sewage, or recycled water containing surfactants, as well as cooling water, can also cause the foam to become weak. Therefore, attention should be paid to the pretreatment of gas to reduce the entry of substances prone to foaming, such as oil, dust, and other impurities, into the desulfurization solution; otherwise, this can result in the absence of sulfur-free foam in the oxidation regeneration tank (tower) or the formation of a large amount of foam. The temperature of the desulfurization liquid must be strictly controlled, especially during hot summers. When its temperature rises by more than 50°C, its viscosity and surface tension decrease, making it difficult for bubbles to form in the regeneration tank. However, if the temperature of the desulfurization liquid is too low (below 35°C), its viscosity increases, and foam forms in the oxidation regeneration tank; this foam resembles cotton fluff and floats on the surface of the tank, making it difficult to separate. In addition, the amount of air flow and the changes in sulfur foam on the tank surface should be checked regularly to maintain a stable blowing intensity. Sulfur foam anomalies are caused by various factors; therefore, when addressing them, it is necessary to investigate the causes from aspects such as equipment, processing methods, and catalyst usage, and take appropriate measures to resolve the underlying issues.