How to clean the reactor after the reaction of sticky materials?

To clean a reactor affected by scale or sticky materials, follow these steps based on the reactor material:

### **For Stainless Steel Reactors:**

1. **Preparation and Flushing**:

- Perform open-circuit flushing to remove impurities like mud and scale from the jacket. This step enhances the effectiveness of the cleaning process and reduces acid consumption.

2. **Pickling Process**:

- **Temperature**: Maintain the pickling temperature at 60°C for optimal descaling without excessive corrosion.

- **Solution Concentration**: Prepare the pickling solution with 81.0% formic acid, 17.0% water, 1.2% buffer, and 0.8% surfactant.

- **Method and Duration**:

- Start with 2 hours of static immersion in the acid solution.

- Follow with 3–4 hours of dynamic circulation, alternating between forward and reverse cycles every 0.5 hours.

- **Testing**: Frequently sample the solution to monitor concentration. Stop the process when the concentration difference is less than 0.2%.

3. **Passivation Treatment**:

- After pickling, passivate the equipment to protect the freshly exposed metal from corrosion.

4. **Alkaline Cleaning**:

- Use a solution of NaOH, NaHPO₄, and softened water for dynamic circulation to neutralize any remaining acid and prevent corrosion.

5. **Final Rinse**:

- Rinse the reactor repeatedly with softened water for 0.5 hours to remove all residues.

6. **Record Keeping**:

- Document each step of the cleaning process to ensure consistency and verify effectiveness.

### **Additional Notes**:

- If a drop test is not performed to determine the exact cleaning cycle, a fixed cleaning time can be used as an alternative.

- Proper neutralization of the cleaning solution is essential before disposal to avoid environmental harm.

By following these steps, stainless steel reactors can be effectively cleaned and maintained for long-term use.