Issues related to the treatment of sulfoxide chloride exhaust gases
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The problem is as follows: The sulfur dioxide and hydrogen chloride emissions generated during the acyl chlorination process need to be treated (mass ratio: sulfur dioxide:hydrogen chloride ≈ 2:1). The proposed solution is to use three-stage falling film water absorption to handle the hydrogen chloride and the salts produced as by-products, followed by the use of alkali to absorb sulfur dioxide. Question: Sulfur dioxide is also considered to be readily soluble in water; its solubility at room temperature is around 10 g/100 ml (compared to around 70 for hydrogen chloride), and it reacts to form sulfurous acid ； Is this solution feasible? Can such by-product salt acid meet the required standards, and can it be sold?
This post was last edited by Desert Fish on 2016-3-1 22:34. When chlorination reactions are carried out using sulfuryl chloride or thionyl chloride as chlorinating agents, a large amount of mixed exhaust gas consisting of sulfur dioxide and hydrogen chloride is generated; this exhaust gas also contains certain amounts of organic vapor along with vapor of the chlorinating agents. Currently, the treatment method used in most factories involves multi-stage water absorption followed by alkaline absorption, with the aim of converting acidic exhaust gases into by-product salts, acids, and sodium sulfite. However, this process cannot separate hydrogen chloride from sulfur dioxide satisfactorily; as a result, the large quantities of by-product salts, acids, and sodium sulfite produced cannot be utilized effectively due to purity issues, and in the end they can only be neutralized and treated as wastewater. The sulfur dioxide and hydrogen chloride mixed gas recovery unit developed by Jiangsu Nuomeng Chemical Co., Ltd. employs a pressure-swapped distillation process tailored to the characteristics of such mixed exhaust gases, thereby perfectly solving the problem of separating these gases. It enables the production of hydrogen chloride and sulfur dioxide with a purity of over 99.9%, achieving a recovery rate of greater than 98%; in addition, it allows for the recovery and reuse of most of the chlorinating agents as well as some organic substances. By recovering hydrogen chloride, sulfur dioxide, and chlorinating agents from the exhaust gases, not only are valuable products obtained, but liquid alkali required in the original treatment method is also eliminated; furthermore, waste liquid generation is reduced, resulting in significant economic and social benefits. The investment can be recovered within one to three years of normal operation of the device. The sulfur dioxide and hydrogen chloride mixed gas recovery units are available in various capacities; the larger the unit, the greater the economic benefits. At present, the smallest capacity unit has a processing rate of 200 m3/hr (at normal temperature and slight positive pressure). The unit consists of several components, including pretreatment, pressure swing distillation, reactor liquid recovery, hydrogen chloride charging, sulfur dioxide charging, and an emergency absorption system. The pretreatment process requires the selection of a suitable approach based on factors such as the composition, temperature, and pressure of the exhaust gas; it is necessary in most operating conditions ； The pressure swing distillation process is the core of this unit ； Owners of the other sections can choose their own configurations according to their needs and existing conditions. If you are interested in this technology, feel free to contact me.