In December 2022, after obtaining the utility model patent certificate of “Auxiliary Measuring Equipment Applied to the Pressure Vessel of a Skid-mounted Green Ammonia Plant”, LUVA won another new patent of “A Device for By-Production of Anhydrous Sodium Sulfite in a Sulfuric Acid Plant”.
At present, there are many kinds of anhydrous sodium sulfite production processes, mainly using lye to absorb, neutralize, concentrate, evaporate and crystallize, separate and dry the SO2-containing gas to obtain the product. However, in the concentration evaporative crystallization section, a large amount of steam needs to be consumed for evaporative crystallization, resulting in high energy consumption, high production costs, and low product quality and purity.
The sulfuric acid plant absorbs the low-grade heat generated by SO3. At present, some devices do not recover it, and some devices increase the acid concentration of the heat recovery tower to 99~100%, the acid temperature 200~220°C, and low-pressure steam is produced as a by-product. High-temperature sulfuric acid has relatively high requirements on equipment materials, and it is absorbed by high-temperature and high-concentration acid liquid, which is easy to generate more acid mist. A layer of filler needs to be set on the upper part of the heat recovery tower, but this will increase the height of the heat recovery tower and increase the investment cost of the equipment.
Aiming at the existing technical problems, our process experts have developed a high-concentration SO2-containing flue gas and sulfuric acid tail gas produced by a sulfuric acid plant, which is absorbed by general lye, and the heat generated by the low-grade heat generated by absorbing SO3 by a sulfuric acid plant. Water is used as a heat source for concentrated crystallization to produce anhydrous sodium sulfite. The device has the advantages of low energy consumption, low investment, no generation of three wastes, and high product quality and purity.
