Heat Exchanger Operation & Maintenance Procedures
Analyzing And Troubleshooting Heat Exchanger Performance
Heat exchanger problems are not always accompanied by obvious symptoms such as leaks or channel intermixing. Some problems are minor but progressive, causing higher energy consumption and performance variability. Dirt, deposits, scale and other fouling rob your plate-type heat exchangers of their design efficiency, risking damage to expensive equipment and unscheduled downtime for repairs.
Process data around the heat exchanger is invaluable in analyzing and troubleshooting performance. Pressure, flow rate and temperature data from channel inlets and outlets can indicate problems with either stream. Instrumentation is well worth the cost of installation, especially for process-critical exchangers, serving to signal operators when the process is about to become uncontrollable.
If measurements and inspections indicate that cleaning and regasketing is warranted, doing the job properly can prevent damage to costly plates. Plate damage leads to leaks, faulty operation and reduced equipment life.
Standard Heat Exchanger Operating Procedures
Standard operating principles are critical for preventing damage to the unit:
1. In steam applications, never leave the steam on with the liquid side turned off. Turn the steam off first and on last.
2. Water hammer, if suspected, must be diagnosed and eliminated, or damage may result.
3. Pumps should always be started against closed valves.
4. Valves must be set to open and close gradually. Sudden opening and closing of the valves will subject the exchanger to mechanical and thermal shock and may cause material fatigue.
Starting up and shutting down should be managed to minimize differential expansion. Follow the stated start-up and shut-down steps in order.
The rate of heat transfer surface fouling is affected by fluid velocity. Tranter recommends that the flow rate be increased if possible at regular intervals. The increased turbulence within the channel retards the rate of fouling. The frequency and duration of this preventive cleaning practice will vary depending on operating fluid velocities and fouling tendencies of the medium.
Maintaining Plate Heat Exchangers
Heat exchanger maintenance is critical for controllability and energy efficiency. Operations managers will be quick to detect a problem and contact you about it. Typical problems include interior comfort complaints, off-grade product, escalating utility bills and related troubles. Methodical diagnostics will save time and prevent wasted effort. These should be outlined in your heat exchanger operations and maintenance manuals.
Tranter Service Center Crews are ready to restore leaking, inefficient, fuel-wasting heat exchangers to nameplate performance (right) at any time.