In the innovation of the caustic soda evaporation system, we have made significant technological improvements. We have implemented the 32%-99% (3+2) process flow. In this process, sodium hydroxide (NaOH) with an initial concentration of 32% goes through multiple-effect falling film evaporators, including the triple-effect, double-effect, and single-effect evaporators, as well as pre-concentrators and a final concentrator, gradually increasing the concentration to 98.5%-99.3%.
Finally, the concentrated caustic soda is sliced using a slicing machine to produce high-purity caustic soda flakes with a purity of up to 99%. These flakes have a controlled thickness ranging from 0.8-1.2mm and strict shape specifications within the range of 0.25-1cm². Additionally, the bulk density of these flakes is between 0.7-0.9kg/dm³, and the energy consumption for producing one ton of caustic soda flakes is very low, with a specific heat consumption of only 1,120,000 kcal per ton.
These technical parameters demonstrate that our caustic soda evaporation system is highly efficient and can produce high-quality products. Low energy consumption is also an essential factor in reducing production costs and environmental impact.
Our independently developed leak-free slicing machine utilizes the working principle of an air jet pump. By using an air pump to extract water, the shaft seal is ensured to be leak-free, completely eliminating the problem of water leakage and effectively removing potential safety hazards. This technological innovation is of significant importance in improving the reliability and safety of the equipment.
Furthermore, we have adopted a specially designed nickel material, N4LJ-2, and conducted long-term repeated tests on its structure to find the optimal solution. Our material research institute has optimized the smelting process by optimizing 19 process control points to meet the caustic soda plant’s requirements for nickel material’s resistance to solid alkali corrosion and high temperatures. This includes using high-purity Jinchuan No.1 nickel (with a purity of up to 99.96%) as a fine raw material and avoiding the use of recycled materials to prevent impurities. Additionally, corresponding forging equipment has been designed, and multiple forging techniques have been developed to ensure that the nickel material meets the highest industry standards.
In terms of welding, pure nickel materials tend to form coarse grains when heated due to their poor metal flowability. This leads to a rapid decline in corrosion resistance and a shortened equipment lifespan. However, pure nickel is widely used in acidic soda evaporation systems due to its excellent corrosion resistance. To achieve high-quality and efficient welding of pure nickel, we have gone through extensive exploration and testing to address the challenges encountered during the welding process.
These technological innovations and optimizations are of significant importance in improving the quality, corrosion resistance, and lifespan of caustic soda evaporation systems.