Compare current operating temperatures with the unit’s normal temperature profile. A larger-than-normal temperature difference between the heating-vapor side and the product boiling side in a particular effect is an indication of reduced performance.

Areas to Inspect

Condensate removal. Confirm condensate can drain freely from the effect in question. Flooded condensate on the shell side can block venting and limit heat transfer. Check for backed-up lines, closed or partially closed valves, blocked orifices, or condensate entering venting lines.

Request an assessment.

Non-condensable gas venting. Verify that shell vents are open and unobstructed. Inspect vent lines. A simple blow-through check can help identify blockages. If venting capacity appears insufficient, a larger vent orifice size may be needed.

Tube cleanliness. Inspect heat-transfer tubes for product buildup, plugging, or other evidence that the cleaning cycle is not removing deposits effectively. Review cleaning conditions, including flow, chemistry, concentration, temperature, and cycle duration against best practices.

Product foaming. Inspect for foam using available sight glasses during operation. Persistent foam can block vapor flows and reduce heat transfer, ultimately affecting temperatures. If foaming is present, inspect associated pumps, gaskets, and mechanical seals for air ingress or leakage.

Here are some additional best practices for troubleshooting:

• Confirm that operating data is accurate.
• Inspect for vacuum leaks, verify temperature and pressure instrumentation, and look for vapor-flow restrictions or product overflow between passes.
• When tube fouling recurs despite cleaning, investigate liquid distribution rather than treating deposits as purely a cleaning issue.
• If the cause remains unclear, a formal evaporator assessment can help identify the source of the performance loss and determine corrective action.

Operating Practices