Heating and insulation operation of jacketed kettle

**Double-Layer Kettle Heating and Insulation Process**

1. **Heating Process:**

- Steam (electric or gas) is introduced to raise the material's temperature to the required cooking level.

- As the temperature increases, the cooking speed accelerates.

- A small venting operation is performed at a certain temperature to remove air and volatile substances like turpentine, eliminating false pressure and reducing cellulose oxidation.

2. **Small Venting Operation:**

- When the pressure reaches the rated level, the vent valve is opened to release air.

- Once the pressure drops to the specified value, the vent valve is closed, and heating continues until the maximum pressure is achieved.

3. **Insulation Process:**

- The highest temperature is maintained for a specific period to ensure raw material deoxygenation and breakdown into pulp.