I. Failure to Achieve Required Vacuum Level: The Vacuum Pump "Loses Power"

Most low-temperature evaporation systems use water-ring vacuum pumps, whose performance is highly dependent on the temperature of the working fluid.

- Low water temperature in winter → Abnormally large pumping capacity of the water-ring pump

In northern China, circulating water, groundwater, and tap water in winter may be only 0–5℃.

The lower the water temperature, the greater the theoretical pumping capacity of the water-ring pump, but the actual operating conditions become unstable.

- Excessive pumping capacity → "Overload" of the vacuum system

The system is designed to match normal water temperature. In winter, the pumping capacity surges, leading to:

  - Severe water entrainment in the gas-liquid separator

  - Steam-water mixing → Air path blocked by water

  - Turbulent gas-liquid mixing inside the vacuum pump chamber

Result: The vacuum level fluctuates, fails to rise, or becomes unstable.

- Condensation and water accumulation inside vacuum pipelines and valves

Due to the cold external environment, the inner walls of pipelines cool rapidly.

Moisture in the secondary steam immediately condenses into water films and accumulates upon contact with cold pipes,

causing local water blockages and air resistance, slowing down vacuum transmission and resulting in failure to reach the target vacuum.

II. Abnormally Increased Energy Consumption: Excessive Cooling → "Frozen" Evaporation Efficiency

The core of low-temperature evaporation lies in the balance among:

heating temperature → evaporation → condensation and cooling.

In winter, the cooling water temperature is extremely low, resulting in excessive cooling capacity and two critical problems:

- Overly low condensation temperature → Depressed boiling point

The lower the condensation temperature, the lower the evaporation boiling point.

The lower the boiling point, the lower the evaporation efficiency under the same heating input.

In short:

Heat that should easily drive evaporation is directly absorbed by excessive cooling.

- Increased steam/electricity consumption on the heating side to compensate for evaporation rate

Reduced evaporation requires the following to meet treatment capacity:

  - Increased heating steam/power

  - Higher circulation flow rate

  - Longer residence time

Final result: Significant rise in energy consumption.

- Overly low feed liquid inlet temperature → Surge in preheating load

Raw water and wastewater in northern winter may approach 0℃.

The equipment must heat it from 0℃ to 30–40℃ for evaporation,

consuming substantial extra energy just for preheating, thus driving up energy use.

III. Increased Equipment Heat Dissipation, Wasting Heat

For equipment installed outdoors or semi-outdoors:

- Sharply increased heat dissipation from cylinders, pipelines, and circulation pump casings

- Reduced effectiveness of insulation layers at extremely low temperatures

- Continuous temperature drop of feed liquid during circulation

Result:

The heating section keeps supplying heat while the evaporation section cannot keep up, with heat being lost as it is generated.

IV. Sluggish Vacuum Valves and Pneumatic Components Further Reducing Efficiency

Under low-temperature conditions:

- Lubricant of pneumatic vacuum valves thickens

- Slow response of solenoid valves

- More noticeable micro air leaks

- Measurement drift of liquid level and temperature sensors

Unstable system control forces higher energy consumption to maintain output,

creating a vicious cycle.

V. Core Summary

The increased energy consumption and poor vacuum performance of low-temperature evaporators in northern winter are essentially caused by:

reduced evaporation efficiency due to excessive cooling + disordered low-temperature performance of vacuum pumps + increased material preheating load + increased system heat dissipation.

This is not a malfunction, but an imbalance in seasonal operating conditions.