Factors causing reactor wall sticking, treatment methods for stainless steel reactor wall sticking

### Reaction Process Factors Affecting Wall Sticking in Stainless Steel Reactors:

1. **Reaction Temperature and Time:**

- At temperatures below 80°C, ammonium chloride as a catalyst hinders pH readings due to its rapid reaction rate. As the temperature rises, the pH drops rapidly, accelerating the reaction and causing excessive polycondensation, leading to coagulation and wall sticking.

- Prolonged polycondensation with high molecular weight and viscosity can also cause wall sticking. To prevent this, control the reaction temperature (~95°C) and terminate the reaction promptly.

2. **Reactor Wall Temperature Difference:**

- Sudden or excessive cooling can create a significant temperature difference between the reactor wall and the material, causing sticking.

- Maintain reasonable temperature differentials: steam temperature < 180°C, thermal shock < 120°C, and cooling shock < 90°C. Gradually increase pressure and temperature during production, starting at 0.15 MPa and increasing by 0.1–0.15 MPa per minute.

3. **Reaction Material Factors:**

- Urea with high sulfate content can act as a curing agent, causing the resin to crosslink and solidify. Use industrial-grade urea with sulfate content below 0.01% to prevent this.

### Reactor Equipment Factors:

1. **Flow Characteristics:**

- Improve material flow to reduce wall sticking. The new turbine agitation design creates radial flow, minimizing sticking.

2. **Eliminating Dead Corners:**

- Dead corners in reactor design increase sticking risks. New heat exchangers with large heat exchange areas and improved material flow help reduce this issue.

3. **Feeding Pipe Position:**

- The feeding pipe is a common sticking point due to high liquid concentration. Use side-by-side pipes at an angle to prevent material from splashing onto reactor walls, and ensure constant stirring for even distribution.

### Methods to Treat Wall Sticking:

- **Inner Wall Treatment:** Polish the reactor's interior, heat exchangers, and welds to improve surface finish and reduce sticking.

- **High-Pressure Cleaning:** Use a high-pressure water jet to clean stuck material from reactor walls.

### Temperature Control Device:

- A reactor temperature control device with temperature sensors and solenoid valves automates temperature regulation, reducing manual labor. It includes cooling water pipes, water jets, and a ring-shaped cooling pipe connected to mains or backup water supply.

### Industry Development:

- China's stainless steel reactor industry has transitioned from import dependence to self-sufficiency in mid- and low-end products, with rapid export growth. The industry is now focused on qualitative transformation to meet growing demand and compete globally.