Introduction to the working principle of multi-effect evaporator

### Multi-Effect Evaporator Operation Process

1. **Solution Flow**:

- The dilute solution is pumped into the third-effect circulation pump intake.

- It passes through a preheater and enters the feed chamber of the third-effect evaporator.

- The solution is heated and evaporated in the heating tube, then enters the separation chamber where vapor and liquid are separated.

- The solution flows to the pump intake, circulating through the system for further evaporation.

2. **Vapor Handling**:

- Vapor from the evaporator enters the separator to remove liquid droplets.

- Clean secondary steam is directed to the condenser for condensation.

- A branch from the circulating pump outlet directs the solution to the second-effect pump intake, where the process is repeated.

3. **Steam Circulation**:

- Secondary steam from the second effect is used as heating steam for the third effect.

- Similarly, secondary steam from the first effect is directed to the second effect.

- Heating steam for the first effect is supplied directly from the boiler, with condensate returned to the boiler room.

4. **Concentrate Discharge**:

- A branch from the pump outlet discharges the concentrate, with the discharge rate adjusted to maintain the desired concentration.

- In countercurrent operation, the concentrate is discharged from the first effect at a higher temperature, reducing viscosity and facilitating concentration to 75%.

5. **Liquid Level Control**:

- Each effect is equipped with a liquid level controller to maintain a constant liquid level.

- The boiler steam supply line includes a control valve to regulate heating steam pressure.

- Condensate from each effect is collected in a condensate tank, with a liquid level controller ensuring proper levels.

This process ensures efficient evaporation, separation, and concentration while maintaining consistent operation and control across all effects.