1. Most Common Fault: Scaling / Coking

Phenomena:

Decreased heat transfer efficiency, reduced evaporation capacity, increased pressure difference, and sharp rise in energy consumption.

Causes:

Excessively high material viscosity or uneven temperature;

Too thick liquid film and low flow rate;

Excessively high temperature and local overheating;

Precipitation of impurities, salts, and organic substances.

Prevention:

Control the evaporation temperature not to exceed the tolerance value of the material;

Maintain a thin and stable liquid film (falling film, forced circulation, wiped film);

Regular online cleaning (CIP);

Control the concentration to avoid excessive saturation.

Solutions:

Shutdown for chemical cleaning (acid cleaning, alkali cleaning);

Adopt online cleaning devices (sponge balls, jet cleaning);

Increase the circulation flow rate or switch to forced circulation / wiped film evaporators.

2. Vacuum System Fault: Unstable Vacuum / Vacuum Loss

Phenomena:

Increased evaporation temperature, inability of the equipment to operate at low temperatures, and decreased output.

Causes:

Poor condenser performance, insufficient cooling water volume;

Vacuum pump failure, impeller corrosion, water shortage;

System seal leakage;

Excessively high temperature of cooling water / condensate water.

Prevention:

Regularly check the vacuum pump oil, impeller, and seals;

Ensure sufficient cooling water volume for the condenser;

Regularly leak-check equipment flanges and interfaces;

Timely recool the condensate water.

Solutions:

Overhaul the vacuum pump, replenish water, change oil, and clean nozzles;

Detect and repair leaks, strengthen thermal insulation;

Clean the condenser tubes to restore condensation efficiency.

3. Heat Exchange System Fault: Small Heat Transfer Temperature Difference, Contaminated Heat Exchange Surface

Phenomena:

Low evaporation capacity, increased heating steam consumption, and large fluctuations in equipment temperature.

Causes:

Scaling and dirt on the heat exchange surface;

Insufficient flow rate and low flow velocity;

Unstable steam pressure.

Prevention:

Regular cleaning;

Maintain high flow rate of the circulation pump;

The control system maintains stable pressure.

Solutions:

Clean the heat exchange surface;

Increase the pump frequency or clean the pump impeller;

Check the heat source pressure and regulating valve.

4. Foaming / Entrainment (Material Run-off)

Phenomena:

Secondary steam entrains liquid droplets, condensate water is contaminated, and product loss occurs.

Causes:

High content of surfactants in the material liquid;

Excessively high evaporation intensity;

Insufficient design of the separator.

Prevention:

Control the evaporation intensity;

Defoam before feeding;

Add high-efficiency demisters.

Solutions:

Add defoamers;

Adjust the liquid level and evaporation temperature;

Clean the demister and upgrade the internal structure of the separator.

5. Unstable Concentrate Concentration / Abnormal Discharge

Phenomena:

Concentration fluctuates, failing to meet process requirements.

Causes:

Unstable feed flow rate;

Inaccurate liquid level control;

Lag in the control system.

Prevention:

Stabilize the feed;

Optimize liquid level and flow rate automatic control;

Install buffer tanks to smooth fluctuations.

Solutions:

Adjust the frequency of the variable frequency pump;

Calibrate the liquid level gauge;

Optimize the PLC control logic.

6. Equipment Corrosion / Leakage

Phenomena:

Abnormal noise, corrosion points, metal powder, and leakage of acid / alkali liquid.

Causes:

Weak material selection (e.g., 304 used for high chlorine content);

Long-term exceeding of temperature and concentration standards;

Corrosion at welding points.

Prevention:

Select materials according to water quality (316L, titanium, Teflon);

Strictly control temperature and PH range;

Ensure qualified welding quality and perform anti-corrosion treatment.

Solutions:

Shutdown for repair welding and anti-corrosion repair;

Replace with higher-grade materials;

Scrap severely corroded parts.

7. Electrical and Intelligent Control System Faults

Phenomena:

Equipment shutdown, parameter out of control, and frequent alarms.

Causes:

Drift of sensors (temperature, pressure, liquid level);

Control system failure;

Motor overload, poor waterproofing.

Prevention:

Regularly calibrate instruments;

Provide waterproof, dustproof, and moisture-proof protection;

Keep the electrical cabinet dry and clean.

Solutions:

Replace sensors;

Restart the PLC system;

Overhaul the motor and cables.