Control of by-products salts and treatment measures in wet flue gas desulfurization

Thread Content

This post was last edited by sdwfsgyykai on 2020-5-17 07:52. Scientifically speaking, in the wet oxidation method for desulfurization, the formation of by-products is inevitable; they are by-products of chemical reactions and exist objectively. However, based on our experience from years of actual production, we can take a series of effective measures to reduce or suppress its formation. Thereby reducing the presence of by-products in the desulfurization solution. There are several reasons for the formation of by-products. First, controlling the solution temperature: once the desulfurization temperature exceeds 50°C, the production rate of by-products increases sharply. II. Control of solution pH: Once the solution pH exceeds 9.0, the production rate of by-products increases sharply as the pH value rises. Therefore, too low temperatures and pH values directly affect the absorption of hydrogen sulfide, while too high temperatures and pH values exacerbate the occurrence of side reactions. Therefore, the temperature of the desulfurization solution should be kept below 45°C, and its pH value should be maintained between 8.3 and 9.0. III. Control of the amount of air used for regeneration: Under oxygen-enriched conditions, sulfur ions are oxidized to elemental sulfur, which is then directly oxidized into sulfates. Therefore, the amount of air used for regeneration must not be too large nor too small; an excessive amount can lead to the formation of by-products, while too little amount can affect the flotation of sulfur bubbles. http://p3.pstatp.com/large/pgc-image/739d6e9ba6714a2eb7ba6acd9e3efeb4 IV. Gas volume and sulfur content in the input gas: When the gas volume and sulfur content are too high, manufacturers tend to increase the amount of alkali used in order to raise the pH value of the solution, thereby meeting the requirements regarding sulfur content in the output product. This will further exacerbate the formation of by-products. Therefore, proper equipment selection and process design are key to wet flue gas desulfurization. In summary, proper equipment selection and process design, along with standardized production operations, can help control the production rate of by-products. The treatment of excessive by-products under extreme conditions mainly involves two processes: discharge and extraction. Most manufacturing enterprises introduce the by-product salt solution into coal yards for blending with coal during combustion as a means of harmless treatment. Some companies also separate substances such as sodium thiocyanate and sodium thiosulfate from the desulfurization wastewater through processes like decolorization, filtration, concentration, cooling, and centrifugation. They then extract the mixed salt of sodium thiocyanate and sodium thiosulfate and sell it, thereby generating some revenue.