1.High-pressure flushing
For tackling heavy physical scale, the efficiency boost is dramatic
The first time Lao Zhou tackled a plate heat exchanger used for cooling, the fouling consisted mainly of substantial mineral deposits from the circulating water. He still remembers the procedure vividly: first, disconnect the power and shut off the media, then remove the end plates on both sides to expose the plates. Next, he adjusted the high-pressure washer to 150 bar and sprayed back and forth from about 40 cm away. After flushing, he found some scale remaining in the gaps of two plates, gave them a second pass, and finally dried everything with compressed air.
What thrilled him most was the performance difference before and after-he specifically recorded the data. Pre-cleaning, the heat exchanger's thermal efficiency was only 68%, with cold water inlet at 25°C and outlet barely reaching 42°C, just a 17°C温差. Post-cleaning, efficiency skyrocketed to 95%, outlet temperature hit 58°C, and the temperature difference jumped to 33°C-nearly doubled! And because heat transfer efficiency improved, the supporting water pump no longer needed to run at full capacity, saving nearly 10 kWh per day. That works out to over 300 yuan in monthly electricity savings.
But the method has its headaches too. Once, while helping a neighboring factory, the operator lost pressure control and dented a thin plate. Though it didn't leak, they had to run it at reduced load, and eventually spent over 2,000 yuan on a replacement. Lao Zhou's advice: high-pressure flushing works best for thick, hard physical deposits like scale and sediment, but if plates are soft or show aging, lower the pressure and flush slowly-don't rush it.
2.Chemical Cleaning
Deep removal of stubborn scale, performance gains more stable
Last summer, the heating heat exchanger at Lao Zhou's plant developed sticky, oily fouling with black deposits mixed in. After half a day of high-pressure flushing, the surface scale came off, but the gaps remained clogged. They brought in a professional chemical cleaning team who first took samples for lab analysis. The results showed the fouling contained grease, organics, and sulfate scale, so they selected a mixed formula of acidic cleaning agent and degreaser.
For the operation, they first diluted the cleaning agent at a 1:10 ratio, pumped it into the heat exchanger for circulation, drained it after 4 hours of cycling, then circulated a neutralizer for 1 more hour, and finally rinsed with clean water three times. The data comparison was striking: pre-cleaning heat exchange efficiency was only 62%, with steam inlet at 120°C and outlet still at 85°C-a massive waste of heat. Post-cleaning efficiency jumped to 94%, outlet water temperature dropped to 55°C, and heat utilization became highly efficient. Most importantly, the steam valve previously had to be opened to 80% to achieve production temperatures but now only needed 60%, saving nearly 1 ton of steam per month. At current steam prices, that saves over 1,200 yuan monthly.
But chemical cleaning risks must be noted. Lao Zhou once heard about a small factory that bought strong acid cleaner themselves, didn't control concentration properly, and let it circulate too long. The result? The plates corroded with pinholes, and they had to replace the entire heat exchanger-losing tens of thousands of yuan. He constantly emphasizes: always hire professional teams for chemical cleaning, conduct sample analysis first, and select the right chemicals and concentration-never just wing it yourself.
3.Backwashing
Ultra-convenient daily maintenance that keeps data stable above safety thresholds
Lao Zhou's plant now has a rule: all plate heat exchangers must undergo backwashing once a week to prevent scale buildup. The operation is incredibly simple-no equipment disassembly needed. First, shut off the normal medium circuit, open the backwash valve, and let clean water flow through the heat exchanger in reverse. Start the pump to maintain 0.3 MPa pressure for 15 minutes, then switch back to the normal circuit.
Don't underestimate these 15 minutes-the data really proves its effectiveness. Take the small heat exchanger in the workshop: without backwashing, thermal efficiency drops about 3% per week. In half a month, efficiency falls from 92% to 85%, and the inlet-outlet temperature difference shrinks from 30°C to 25°C. But with weekly backwashing, efficiency stays stable above 90%, the temperature difference remains around 28°C, and there's no need for frequent shutdowns for deep cleaning. Plus, backwashing costs nothing extra-just some water, which is negligible compared to deep cleaning expenses.
However, backwashing has clear limitations. If scale has already become thick and hard, backwashing is essentially useless. Once when Lao Zhou was on a business trip, no one performed backwashing at the plant for three weeks. When he returned, the heat exchanger efficiency had dropped to 78%. After two backwashing cycles, efficiency only recovered to 82%, and chemical cleaning was finally needed to restore it to 93%. That's why he always says backwashing is "daily healthcare"-it prevents minor issues but can't cure major ones. Deep scaling still requires other methods.
Looking at all three methods, each has its own advantages. The choice should be based on data and actual conditions: for large physical scale where quick efficiency gains are needed, high-pressure flushing is suitable-post-cleaning efficiency can increase by 20%-30%. For stubborn or complex scale where long-term stability is the goal, chemical cleaning is more reliable-efficiency can recover and stabilize above 90%. For daily maintenance, use backwashing to minimize efficiency loss and avoid frequent deep cleaning.
Lao Zhou's current approach is: weekly backwashing, quarterly high-pressure flushing, and annual chemical cleaning. With this combination, the plant's heat exchanger efficiency stays between 92%-95%, electricity and steam costs have dropped significantly, and equipment failures have decreased.
I've just compiled this from listening to Lao Zhou talk so much-some technical details might not be perfectly accurate. If your plant also has plate heat exchangers, have you recorded performance changes after cleaning? Or encountered any frustrating problems during cleaning? Feel free to share in the comments. Let's exchange experiences and help others avoid detours. If you have doubts about any cleaning method's effectiveness, just ask, and I'll check if Lao Zhou has more data to share.
