Plate-type quadruple-effect evaporator

1. Working Principle 

The plate-type four-effect evaporator consists of four evaporators connected in series. It utilizes the secondary steam from the previous effect as the heat source for the next effect, achieving multi-effect operation. The specific process is as follows:

First-Effect Evaporation: Live steam enters the first-effect evaporator, heating the material and generating secondary steam.

Second-Effect Evaporation: The secondary steam generated in the first effect enters the second-effect evaporator, serving as a heat source to heat the material again, generating secondary steam.

Third-Effect Evaporation: The secondary steam generated in the second effect enters the third-effect evaporator, continuing to heat the material and generating secondary steam.

Fourth-Effect Evaporation: The secondary steam generated in the third effect enters the fourth-effect evaporator, completing the final evaporation. The generated secondary steam then enters the condenser.

Condensation and Recovery: The secondary steam generated in the fourth effect is condensed into water in the condenser, maintaining the system vacuum. The condensate can be recycled.

2. Process Flow

Feeding: After pretreatment, the material is fed into the plate preheater via a feed pump for preheating.

First-Effect Evaporation: Preheated material enters the first-effect evaporator, where it is heated and evaporated by the first-effect circulating pump. The resulting secondary steam enters the second-effect evaporator.

Second-Effect Evaporation: The secondary steam from the first effect serves as a heat source, heating the material in the second-effect evaporator. The resulting secondary steam enters the third-effect evaporator.

Third-Effect Evaporation: The secondary steam from the second effect heats the material in the third-effect evaporator. The resulting secondary steam enters the fourth-effect evaporator.

Fourth-Effect Evaporation: The secondary steam from the third effect heats the material in the fourth-effect evaporator. The resulting secondary steam enters the condenser.

Condensation and Crystallization: The secondary steam generated in the fourth effect condenses into water in the condenser. The concentrated material crystallizes in the crystallizer and is then separated by a centrifuge.

3. Equipment Structure

Plate Heat Exchanger: The core component, made of titanium or 316L stainless steel corrugated plates, offering high heat transfer efficiency and strong corrosion resistance.

Separator: Enables gas-liquid separation, ensuring the purity of the secondary steam.

Condenser: Condenses the secondary steam generated by the fourth effect into water, maintaining the system vacuum.

Vacuum System: The last effect maintains negative pressure (0.08~0.09MPa), lowering the boiling point and saving energy.

Pump Set: Includes feed pump, circulation pump, etc., used for material conveying and circulation.

4. Advantages

Rapid Energy Saving: The four-effect design allows for the reuse of steam heat energy four times, significantly reducing energy consumption.

Compact Structure: The plate heat exchanger has a compact design and small footprint.

Flexible Operation: Multiple feeding processes such as parallel flow, counter-flow, and horizontal flow can be adopted.

Easy Maintenance: The plates can be quickly disassembled for cleaning, minimizing downtime.

5. Precautions

Equipment Maintenance: Clean the equipment regularly to prevent scaling and corrosion.

Safe Operation: Operators must wear protective equipment and avoid contact with corrosive substances.

Environmental Requirements: Waste gas generated during evaporation must be treated before discharge. The design and operation of a plate-type quadruple-effect evaporator need to be optimized according to the specific material characteristics and process requirements to ensure rapid system operation and product quality.