Corrosion of calcium sulfate evaporation equipment

The following measures can be taken for protection and control: 1. Choose corrosion-resistant materials: Replace or upgrade the materials used in the sodium sulfate evaporation equipment, using materials with better corrosion resistance such as stainless steel and titanium alloys. 2. Surface coating protection: Apply anti-corrosion coatings, such as epoxy resin coatings, to the surface of the equipment to prevent contact between the equipment and corrosive substances. 3. Cathodic protection: The corrosion process is controlled based on chemical principles by using sacrificial anodes or external current. 4. Regular inspection and maintenance: Periodically check for corrosion on the equipment, and carry out cleaning and necessary repairs as needed. 5. Control the working environment: Optimize the working environment by controlling humidity, temperature, and the concentration of chemical substances to reduce the corrosion rate. .

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Your calcium sulfate solution must contain other components, such as chloride ions

When corrosion occurs in the evaporation equipment for sodium sulfate, the following protective and remedial measures can be taken: 1. Material selection – Corrosion-resistant materials: Use materials that are resistant to sodium sulfate corrosion, such as stainless steel (316L), titanium alloys, Hastelloy, etc. Lining protection: Use corrosion-resistant linings on the inner walls of the equipment, such as rubber, polytetrafluoroethylene (PTFE), or fiberglass-reinforced plastic. 2. Coating protection: Anti-corrosion coatings such as epoxy resin and polyurethane are applied to enhance the equipment’s resistance to corrosion. Regular inspections: Regularly check the condition of the coating and repair any damaged areas promptly. 3. Process optimization: Control concentration and temperature: Avoid excessively high concentrations and temperatures to reduce the risk of corrosion. Flow rate control: Properly control the flow rate to prevent high-speed fluids from causing erosion and corrosion of the equipment. 4. Cathodic protection – Sacrificial anodes: Zinc, magnesium, and other sacrificial anodes are installed to protect equipment from electrochemical corrosion. External current: Cathodic protection is achieved through an external current, which is suitable for large-scale equipment. 5. Regular maintenance and cleaning of equipment: Periodically remove scale and deposits to prevent localized corrosion. Corrosion monitoring: Install corrosion monitoring devices to monitor corrosion in real time and take timely action. 6. Medium treatment: Addition of corrosion inhibitors: Corrosion inhibitors are added to the medium to reduce the corrosion rate. pH adjustment: Adjust the pH of the medium to reduce acidic or alkaline corrosion. 7. Design improvements and structural optimization: Avoid areas prone to corrosion such as dead corners and gaps, and optimize the equipment structure. Enhanced support: Additional supports and reinforcement bars are added to reduce vibration and stress corrosion. 8. Emergency handling: Emergency shutdown: In the event of severe corrosion, shut down the equipment immediately for inspection and repair. Local repair: Perform local repair or replacement of the corroded area. 9. Training and Management: Employee training: Strengthen training for operators to enhance awareness of corrosion protection. Management system: Establish a comprehensive system for equipment maintenance and corrosion protection. Through the above measures, the corrosion problem of calcium sulfate evaporation equipment can be effectively prevented and controlled, thereby extending the equipment’s lifespan.

Is there severe corrosion on the heater? If it is heater corrosion, a graphite heat exchanger can be used, which can fundamentally solve the corrosion problem.

I. Analysis of corrosion mechanisms – Chemical corrosion: Sodium sulfate solutions, at high temperatures (>80°C), accelerate metal oxidation; they particularly attack the grain boundaries of carbon steel and common stainless steels (such as 304), leading to pitting and stress corrosion cracking. Electrochemical corrosion occurs when local scaling on the inner wall of equipment or differences in solution concentration create a potential difference, leading to galvanic corrosion; this phenomenon is common in areas with complex structures such as welds and valves. Scale-induced corrosion: Sodium sulfate crystals adhere to the surface of equipment, causing local temperature and concentration abnormalities that increase metal fatigue and the corrosion rate. II. Protective Measures (1) Material Upgrade and Surface Treatment: For the selection of primary materials, duplex stainless steel (2205/2507) or titanium alloys (Gr2/Gr5) should be given priority, as they exhibit better resistance to chloride and sulfate corrosion compared to ordinary stainless steel. Case: After a chemical plant switched to 2205 duplex steel, the lifespan of its evaporators increased from 2 years to 8 years. Corrosion-resistant coating technology: spraying PTFE or ceramic coatings with a thickness of 200–300 μm to isolate corrosive agents. The integrity of the coating must be regularly checked to prevent peeling. (2) Optimization of process parameters – Temperature control: The evaporation temperature was reduced from 120°C to 90–100°C; vacuum evaporation was used to reduce the thermal load and minimize the risk of oxidation at high temperatures. Concentration gradient management: The solution concentration is maintained at 20-30% (to avoid supersaturated crystallization), and a continuous feeding mode is used to reduce local concentration fluctuations. (3) Corrosion inhibitors and water quality control: Sodium molybdate (0.1–0.3%) or silicate corrosion inhibitors are added to suppress electrochemical corrosion reactions. Pre-treatment of the inlet water requires filtering out impurities such as Cl⁻

The calcium sulfate evaporator in our Nanfeng Chemicals has no signs of corrosion; your liquid’s composition must be incorrect