Problems and Solutions of Sulfur Foam Flotation in Coke Oven Gas Desulfurization Systems

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Coke oven gas desulfurization systems often encounter the problem of sulfur foam flotation, and knowing how to address this issue properly has a significant impact on the entire desulfurization system. The process of sulfur foam formation involves the desulfurization liquid containing numerous bubbles in the regeneration tank or regeneration tower, which creates numerous bubble clusters within 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 liquid level stability. Question: In a regeneration tank without distribution plates, an increase in air bubbles in the desulfurization system occurs. As these bubbles rise from the bottom upward, the pressure acting on them decreases, causing their volume to increase. This leads to intense agitation of the solution in the tank, and the bubbles that emerge are prone to breaking apart, preventing the formation of a stable foam layer. As a result, less elemental sulfur is carried away, which affects the efficiency of regeneration. The formation of air bubbles and a large number of soap bubbles in the desulfurization system is an abnormal phenomenon in sulfur foam flotation; if not corrected in time, the problem will become quite serious. Reasons for weak foam: 1. In the desulfurization solvent system, changes in coal type lead to excessively high furnace temperatures, and gases carry hydrocarbons through other pathways; this results in dissolution and emulsification, leading to higher surface tension and the formation of bubbles. 2. Additionally, if the desulfurization solvent is used for too long or if the temperature of the heating steam source is too high, excessive degradation products are generated, resulting in weak foam ； 3. Failing to add fresh solvent over a long period of time results in the defoamer present in the solvent being depleted and not being able to be replenished in time, which causes the foam to become weak ； 4. Other types of rainwater, sewage, or recycled water containing surfactants, as well as cooling water, can also cause the foam to become weak. Solution: 1. One of the reasons for the formation of bubbles in the desulfurization system is that the desulfurization solvent system is too dirty; therefore, cleaning is a necessary part of maintaining the solvent system. 2. Pay attention to the pretreatment of gas to reduce the entry of oils, dusts, and other substances prone to foaming into the desulfurization solution along with the gas; this can prevent the formation of sulfur-free foam in the oxidation regeneration tank (tower) or result in the generation of a large amount of false bubbles. 3. Strictly control the temperature of the desulfurization liquid, especially during hot summers. When the temperature of the desulfurization liquid 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 floats on the surface of the tank in a cotton-like manner and is 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, in addressing them, it is necessary to investigate the causes from aspects such as equipment, processing techniques, and catalyst usage, and take appropriate measures to resolve the underlying problems.