Enhance heat transfer efficiency and reduce heat transfer resistance

Regularly clean the heat exchange surface: Scaling of the heat exchange tubes is the primary cause of decreased heat transfer efficiency, and a cleaning cycle should be developed based on the quality of the wastewater. It is recommended to clean high salt and high hardness wastewater once every 1-2 months. A combination of chemical cleaning (citric acid and amino sulfonic acid pickling) and physical cleaning (high-pressure water jet, ultrasonic descaling) can be used to thoroughly remove scale and dirt from the pipe wall and restore the heat transfer coefficient.

Replace high-efficiency heat exchange components: Upgrade traditional smooth heat exchange tubes to threaded tubes, corrugated tubes, or titanium alloy tubes, which have a heat transfer area 30% -50% higher than smooth tubes and can significantly improve heat exchange efficiency; At the same time, check whether the heat exchange tubes are blocked or corroded, and replace damaged pipes in a timely manner.

Optimizing the flow rate of heat transfer medium: Increasing the flow rate of the medium on the shell or tube side can reduce the thickness of the boundary layer on the heat transfer surface and enhance heat transfer. By adjusting the frequency of the circulation pump, the flow rate is controlled within the optimal range of equipment design (usually 1.0-2.0m/s) to avoid insufficient heat transfer caused by low flow rate.

Optimize operating parameters and match optimal operating conditions

Precise control of vacuum degree and temperature: Adjust the vacuum degree and heating temperature to the optimal matching value while ensuring sufficient evaporation of wastewater. For example, when treating high salt wastewater, the vacuum degree should be controlled at -0.085-0.095MPa, and the heating temperature should be controlled at 55-65 ℃. This can not only avoid the acceleration of scaling caused by high temperature, but also ensure the evaporation rate.

Stable feed load and concentration: Avoid significant fluctuations in feed quantity and concentration, as these fluctuations can cause an imbalance in evaporator operating conditions and a sudden drop in processing efficiency. A buffer tank can be set to stabilize the feed flow rate, and the wastewater concentration can be controlled within the rated treatment range of the equipment (generally TDS 10% -30%) through pretreatment. When the concentration is too high, it can be appropriately diluted, and when it is too low, it can be refluxed for concentration to increase the processing capacity per unit time.

Using heat pump technology to recover waste heat: Installing a vapor compression heat pump (MVR) or waste heat recovery heat exchanger to compress and heat the secondary steam generated by the evaporator, and then using it as a heating source again, can reduce external heat input and improve heat utilization efficiency, increasing processing efficiency by 20% -40%.

Reduce system resistance and minimize energy loss

Check and optimize pipeline design: Check whether there are too many bends and too small pipe diameters in the evaporator inlet and outlet, condensate, and vacuum pipelines. Excessive pipeline resistance can cause poor material circulation and reduce processing efficiency. Revamp unreasonable pipelines by increasing pipe diameter and reducing bends to ensure smooth material flow.

Maintaining the stability of the vacuum system: Insufficient vacuum degree can lead to an increase in the boiling point of wastewater and a decrease in evaporation rate. Regularly inspect the sealing components and filter elements of the vacuum pump, and replace aging parts in a timely manner; Clean the accumulated liquid and impurities in the vacuum pipeline to ensure the pumping efficiency of the vacuum system and maintain a stable vacuum environment.

Strengthen pre-processing to reduce evaporation difficulty

Removing impurities and viscous substances from wastewater: Through pre-treatment processes such as flocculation precipitation, precision filtration, and activated carbon adsorption, suspended solids, colloids, and large organic molecules in wastewater are removed, reducing wastewater viscosity, avoiding impurities from depositing on the heat exchange surface, and reducing subsequent evaporation load.

Separate treatment of different types of wastewater: separate high concentration, high viscosity wastewater from low concentration wastewater to avoid increasing evaporation difficulty after mixing. Treating and concentrating high concentration wastewater separately before entering a low-temperature evaporator can improve overall treatment efficiency.