A Complete Troubleshooting Guide for Industrial Evaporation Systems   Industrial evaporators—whether used for wastewater concentration, crystallization, MVR evaporation, or multi-effect evaporation—operate under high temperature, negative pressure, and long-duty cycles. This makes them susceptible to a series of predictable and recurring faults.  This guide compiles the most common industrial evaporator problems, their typical symptoms, engineering root causes, and step-by-step troubleshooting methods used by experienced process engineers.   Q1: The evaporator’s heat transfer efficiency drops sharply. How to Fix Sharp Drops in Evaporator Heat Transfer Efficiency?   Typical Symptoms   Significant reduction in evaporation rate Higher-than-normal steam consumption Abnormal temperature difference across effects Difficulty maintaining stable vacuum   Likely Causes of Efficiency Loss   You already mentioned the major ones—here：   1. Scaling or fouling on heat exchange tubes（>60% of cases）   Salt crystallization: CaCl₂, Na₂SO₄, CaCO₃ Organic fouling from high-COD wastewater Silica scaling (the most difficult to remove) Oil/grease films from chemical or food industries   Severe scaling reduces the heat transfer coefficient by 50–80%.   2. Steam leakage / insufficient primary steam pressure   Gasket aging Improper bolt torque Steam trap malfunction Condensate not being discharged on time   3. Circulation pump performance decline   Cavitation Impeller erosion Bearing wear Reduced NPSH due to pipeline buildup   4. Insufficient vacuum   Air ingress Condenser blockage Undersized vacuum pump Liquid ring pump fluid deterioration   5. Incorrect operating parameters   Feed temperature too low Material viscosity increases at high concentration Operating pressure deviates from design   How to Troubleshoot (Professional Workflow)   Step 1 — Heat Transfer Diagnostics   Conduct a heat balance test Compare actual vs. design U-value Check temperature profiles across effects   Step 2 — Mechanical Inspection   Measure ΔP of pipelines Inspect pump performance curves Check impeller wear thickness   Step 3 — Vacuum System Assessment   Use helium leak detection Validate condenser cooling water flow Measure vacuum pump discharge temperature   Step 4 — Tube Condition Inspection   Insert an endoscope to observe scale Measure fouling thickness If silica scale: prepare alkaline + chelating cleaning formula   Additional Recommended Actions   Install an online fouling monitor Add anti-scalant chemicals for high-hardness wastewater Optimize feed preheating to reduce viscosity   Q2: The circulation pump shows cavitation or abnormal vibration. How to solve it?   Typical Symptoms   Loud crackling noise (“gravel sound”) Sudden pressure fluctuation Vibration amplitude > 0.1 mm Honeycomb pits on impeller   Causes   1. Inadequate inlet pressure   Tank level too low Strainer clogged Suction line too long Poor piping design (90° elbows too close to pump inlet)   2. Gas entrainment   Air leaks in seals Gas released from supersaturated solution Gas accumulation at high points in the pipeline   3. Mechanical installation errors   Soft foundation Pump misalignment Unbalanced impeller   Solutions   1. Optimize NPSH   Increase suction liquid height（≥1.5 m static head） Enlarge suction pipeline Avoid unnecessary valves before pump inlet   2. Remove gas from the system   Install a cyclone degasser Add vacuum deaeration before feed tank Install automatic vent valves at pipeline high points   3. Strengthen pump maintenance   Laser alignment (accuracy ±0.02 mm) Quarterly impeller wear measurement Replace bearings annually in heavy-duty systems   4. Process Parameter Optimization   Reduce feed viscosity via preheating Maintain turbulence in evaporation chamber Avoid oversized pumps that cause low-flow cavitation   Q3: The evaporator’s vacuum system is unstable. How to troubleshoot?   Typical Symptoms   Vacuum cannot reach design value Secondary steam cannot fully condense Large fluctuations in temperature & pressure Condensate with bubbles   Causes (Expanded)   1. Condenser problems   Cooling water flow too low Heat exchange tubes fouled High cooling-water temperature (summer issue) Improper condenser design for new production loads   2. Vacuum pump failures   Damaged rotor Worn vanes / worn impeller Contaminated working fluid Overheated vacuum pump   3. System leakage   Gasket hardening Improper flange torque sequence Micro cracks at welds Aging sight glass seals   Troubleshooting Steps   Step 1 — Vacuum Leak Diagnosis   Helium mass spectrometer Pressure decay test Soap test for quick diagnosis   Step 2 — Condenser Management   Mechanical descaling (≥100 bar) Acid cleaning using 5% citric acid Increase cooling water flow   Install secondary condenser for energy-intensive systems   Step 3 — Vacuum Pump Maintenance   Replace oil Clean water-ring pump working fluid Check vane-to-cylinder clearance (0.05–0.08 mm) Replace vanes every 6–12 months   Advanced Tip   Install vacuum buffer tank to stabilize negative pressure during load fluctuations.   Q4: Crystal particle size is uneven. How to optimize evaporation parameters?   Key Parameters    1. Supersaturation   High supersaturation → fine particles Low supersaturation → large agglomerates   2. Circulation velocity