Expander running cold problem
Thread Content
I don’t know what happened to the expander in our factory recently. The speed has reached 30,000 rpm, but the main cooling liquid level is still accumulating very slowly. It can’t even reach 50mm in an hour. It reaches the rated speed at 32,000. However, the shaft temperature of the expansion joint is obviously lower than the oil temperature. The oil temperature is 38 degrees, and the expansion joint temperature is only about 28. The supercharging cutoff is at least around 48 degrees, and the outlet temperature of the expander is also higher than before. Is it running cold? What impact will it have on distillation? We often encounter difficulties with liquid accumulation during cold driving, and sometimes we open two expanders. It is not really whether the expander is running cold or there is a problem somewhere else. Does that senior understand? What methods can be used to speed up fluid accumulation when driving cold?
It can be judged based on ordinary experience. The main comparison is to look at the changes in the expansion flow rate and the outlet temperature of the expansion section when the speed is certain and the inlet temperature and pressure are basically the same. If there is no change, then there is no problem. If you want to quickly establish the liquid level when driving in cold conditions, you can only use the expander to have the maximum load of refrigeration. If there are two units, open two units.
Under normal circumstances, before starting the expander, if the oil temperature is too low, the lubricating oil must be heated, and the lubricating oil must be heated until it reaches a certain temperature before starting the machine. Furthermore, if the expansion amount is large, liquid accumulation may not be fast. Sometimes, if the expansion amount is large, liquid accumulation will be difficult. It mainly depends on the efficiency of the expander. When the outlet temperature of the expander is reached and the expansion amount is reached, it is necessary to check whether there are any problems with other operations. Check the sealing air pressure to prevent cross-flow of cooling capacity. According to what you said, it may not necessarily mean running cold. When liquid accumulates, many factors such as the main cooling temperature difference, the pressure of the upper and lower towers, the amount of expansion air, etc. will affect it.
1) The low shaft temperature is generally related to your shaft seal and sealing gas. It is recommended that you check it. According to your description, it may be that the cold air of the expander is leaking. 2) The unit starts up slowly and the liquid accumulation becomes more complicated. It is recommended that you check the temperature difference of the main heat exchanger, the working condition of the expander, whether there is frost in the air separation tower, and whether the cooling capacity distribution is appropriate. 3) Our factory always uses liquid oxygen backflow during startup.
Brother, can you tell me where the expander is? How big? Rated speed of 32,000?