Discussion on methods to prevent instrument freezing
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Location: Inner Mongolia, Type of facility: Chemical industry. Temperature: During this cold wave, the temperature dropped as low as -28°C. Although there are insulation measures for the instruments on site and steam heating in place, it’s still extremely cold everywhere, and employees are too busy to cope with the situation. Based on past experience, maintaining temperature and providing heating below -18°C poses no challenges. -Above 10 degrees, as long as there is insulation it’s fine. But below -20 degrees, problems start to arise one after another; even the entire insulation of the integrated steam orifice plate, as well as the diaphragms and springs inside the solenoid valves and injection valves, freeze over. The dew point of the process gas at operating pressure is -40, meeting the specification requirements. I can’t figure out how units with even lower temperatures than mine manage to prevent freezing Please share your own methods for preventing freezing
The temperature in Daqing is similar to that where you are; hot water heating is used here, and it works well. It turns out that even with steam tracing, freezing still often occurs; during winter, the main task of the instrument technicians is to blow air through the tracing system.
I worked at a chemical plant in the northeast; in those years, the nighttime temperatures there could drop to -30 degrees Celsius, and the instruments often froze as well. We used the following methods to prevent freezing: 1. Utilize sufficient steam heating; 2. Place the instruments that are most prone to freezing in insulated boxes, with steam heating pipelines running inside those boxes; 3. Increase the frequency of inspections, especially at night; 4. Use Yokogawa EJA instruments filled with ethylene glycol, designed to withstand temperatures of -40 degrees Celsius. In summary, for instruments that are prone to freezing, it’s important to choose ones of high quality that can withstand such conditions and remain functional after freezing. Previously we used Yokogawa’s transmitters, but due to relations between China and Japan, we stopped using their products. Yet, to be honest, the EJA transmitters do indeed have good resistance to freezing.
Agreed; EJA transmitters are indeed durable and resistant to freezing. Even after being frozen and thawed, they can still be used. I’ve used many Siemens and Rosemount transmitters as well, and in most cases the sensor becomes unusable after being frozen and thawed
It turns out that even with steam tracing, freezing still often occurs; during winter, the main task of the instrument technicians is to blow air through the tracing system.
It indicates that there isn’t enough heat; discuss this with the process team to increase the amount of steam used. Additionally, place the instruments in insulated boxes and provide heating so that the temperature stays above 10 degrees Celsius – in that case, the instruments definitely won’t freeze.
This low temperature represents a test for instruments; it’s possible that just a drop of one or two degrees Celsius was enough to cause many instruments to freeze. The heat tracing provides sufficient heat, the instruments are well insulated, and strict precautions are taken by the workers.
These past two days it’s really cold, with temperatures as low as minus 16 degrees. The instruments on the ground are fine, but no matter how high the heating level on the frames is set, it doesn’t help. From 2 a.m. to 4 a.m., there’s basically no way to get any rest; without using asbestos for insulation, everything inside the insulated box freezes over
Petrochemical workers have great aspirations; they fight against the harsh cold to overcome difficulties. :Victory: We’ve been working in the southern area, involved in oil extraction. The surface doesn’t freeze in winter, but when it’s cold, the crude oil in the pressure pipes can solidify. That’s why we use electric heating elements; these elements are wrapped around the pipes entirely, and they’re so hot to the touch. The electricity needed for this heating is generated on-site, so there’s no concern about high power consumption – after all, it’s only a few barrels of oil at stake. :Lol, it’s just my personal opinion for reference only.
It is mainly steam tracing, with a small amount of self-tracing. For steam tracing, check daily that the traps and tracing lines are unobstructed ； For self-heating types, check whether the insulation thickness is sufficient to cope with changes in ambient temperature.
Thermal insulation inspection must be carried out carefully; one must not simply check the area in front of and behind the manual valve, but should try to examine the thermal insulation condition at a distance from those areas； If the hot water heating effect is not good, connect a rubber tube, supply steam, and wrap it around