Oil temperature control method for ammonia-cooled screw ammonia compressors?
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We have used several large-scale refrigeration units as well as screw-type ammonia refrigeration compressors from Yantai Binglun. Oil cooling is achieved through ammonia cooling, but over the years of use, we have found that controlling the oil temperature to be a hassle. If the inlet valve for ammonia in the ammonia cooler is opened too wide, the oil temperature drops, often falling below 30°C; if the valve is too small, then the oil temperature rises too high. Since the oil temperature is crucial for the operation of the refrigeration unit, it poses significant challenges for operators, who need to constantly monitor and adjust it. It’s incredible that for refrigeration units costing hundreds of thousands of dollars, the method of controlling the oil temperature is such an outdated and complicated one. Could it be that our control methods are incorrect? I would appreciate some advice on reasonable methods for controlling the oil temperature in ammonia-cooled screw ammonia compressors. Thank you!
The screw-type ammonia refrigeration compressors used in our factory are also produced by Yantai Binglun. Generally, the inlet and outlet valves are kept open. If ammonia levels at the inlet are high enough to cause the oil temperature to drop below 10 degrees, it will increase the viscosity of the refrigeration oil, which in turn leads to a decrease in oil pressure. In this case, we will temporarily reduce or fully close the inlet valve of the ammonia cooler, and only open it fully after the oil temperature rises and stabilizes. Under normal conditions, the oil temperature is generally within the range of 40 to 55 degrees. Please point out any mistakes!
Reply to 1# chinazwr: It turns out that in oil-cooled systems, the amount of ammonia is not controlled by a thermal expansion valve
The oil cooling system in our facility also uses ammonia; during startup, the oil temperature often drops low, causing the system to shut down automatically due to interlock mechanisms. Do anyone have any good solutions?
I also have a large ammonia-based screw compressor with cooling, though its cooler is of the water-cooled type; it’s also difficult to control, as control is achieved by regulating the valves for the circulating water at the inlet and outlet. Due to changes in ambient temperature, the temperature of the circulating water system changes as well, so frequent adjustments are necessary. As for modifications, I think it would be better to adopt the lubricating oil cooling method used in air compressors, controlling it with a thermostat – this approach is more economical.
The ammonia chillers in our facility are manufactured by Dalian Daling, and the oil coolers are also cooled using liquid ammonia. The control method involves keeping the ammonia inlet valve fully open and adjusting the opening degree of the ammonia outlet valve. In practice, this approach proves to be quite troublesome for the operators. With rising temperatures recently, the oil temperature has started to increase again; with the valves fully open, the temperature has reached 55°C. The set point for an alarm is 60°C, while shutdown occurs at 65°C – it’s really a cause for concern! Just a quick question, fellow sailors: what is the opening degree of the air intake shut-off valve on your engines?
Hello, do you have the manual for Yantai Binglun? Please send me an electronic version
Use an oil temperature control valve, or control the temperature and flow rate of the cooling water.