Four process factors that lead to sticking of stainless steel reactor wall

Sticking in stainless steel reactors is a common issue that can severely impact performance. It often arises from specific process factors that are challenging to avoid but can be mitigated with proper operation.

1. **Raw Material Factors**:

Urea with excessive sulfate content can act as a curing agent when added late in the resin polycondensation reaction, causing rapid crosslinking and solidification within the reactor. To prevent this, use standard industrial urea with sulfate levels below 0.01%.

2. **Operational Balance**:

Unstable or fluctuating process parameters, such as temperature and pressure, can lead to uneven resin polycondensation and wall sticking. Gradually increase pressure and temperature during production, starting with steam at 0.15 MPa for 2-3 minutes and raising pressure at a rate of 0.1-0.15 MPa per minute.

3. **Reactor Wall Temperature Difference**:

A significant temperature difference between the reactor wall and the material can cause sticking. Maintain reasonable temperature ranges during heating and cooling. For example, steam temperature should stay below 180°C, thermal shock below 120°C, and cooling shock below 90°C. Properly regulate cooling medium inlet and outlet temperatures to ensure balanced operation.

4. **Reaction Temperature and Time**:

Low reaction temperatures (<80°C) combined with ammonium chloride as a catalyst can accelerate the polycondensation reaction, leading to coagulation and sticking. Prolonged reaction times and high viscosity also contribute to this issue. Control reaction temperature (0-95°C) and time to terminate the reaction promptly and avoid excessive molecular weight or viscosity.

By addressing these factors and adhering to proper operational guidelines, sticking in stainless steel reactors can be effectively minimized.