The vibration level of the smoke extractor is extremely high – do anyone have any solutions? Come in and chat~
Thread Content
This morning, when I went to the control room, the shift supervisor reported that the vibration level of the rear shaft of the smoke extractor had suddenly risen from around 30 to 38. After checking the trend, I tried adjusting the cooling steam valve for the smoke extractor’s rotor; the valve position was increased from 50% to 100%, and the amount of cooling steam used rose from 1.5 tons to 3 tons, but there was no change in the vibration levels. After several cycles of operation, the vibration level rose step by step to over 70. The standby unit was urgently brought online to operate under no-load conditions; production was adjusted according to the parameters of this standby unit, while the steam control valve used for cooling the fan wheel was gradually closed. The vibration level remained relatively stable, so the operator dared to open the bypass line of that steam control valve. As a result, the vibration values at the four measurement points on the fan’s front and rear axes began to fluctuate significantly, with one of those points reaching as high as 90, while the temperature of the fan wheel dropped to 280°C. After repeating this process several times, the vibration value eventually stabilized around 40. In my opinion, the reason for these fluctuations in vibration levels is the excessively low temperature of the flue gas. Currently, due to the improved properties of the feed oil, it is lighter in nature and produces less coking; as a result, the temperature in the regenerator bed remains around 660°C–670°C (the regenerant turns gray in color when it burns). This leads to the flue gas temperature dropping to between 640°C and 650°C. Operating the flue gas extractor within this temperature range makes it most likely for the blades to become fouled, thereby leading to an increase in vibration levels. Theoretically, a flue gas temperature of 660°C to 670°C is the ideal range to ensure long-term operation of the flue gas extractor. My workshop uses a single-stage flue gas extractor from Lanzhou Refinery, model YL6000F. There is no on-line analyzer for measuring the particle size and concentration of flue gas in the pipeline ahead of the extractor, and the efficiency of the regenerator’s centrifugal separators as well as the triple centrifuges is also poor. Carrying out major renovations would require a large amount of money; haha, not very interesting at all! :Q The purpose of posting this thread is to spark discussion – how do everyone else handle similar situations? :o Those who are interested, come and chat~:lol
Putting aside the issue of the flue gas extractor’s temperature, why is the bed temperature in the regenerator so low? The vibration problems of the flue gas extractor have a direct impact on the device’s ability to operate over long periods of time. In the past, when vibration was high, we would gradually shut down the flue gas extractor and restart it once the temperature dropped to around 300 degrees
The low bed temperature in the regenerator is due to the light nature of the feedstock, which is pure wax oil (deparaffinized and modified wax oil). Another point is to generate more steam; since the external heat exchanger extracts a large amount of heat, the bed temperature remains low. Your method is very good. We have a backup unit; when the vibration level rises, we switch to it and disassemble the smoke extractor to clean any catalyst scaling.
We don’t have a backup machine; there’s no other way. We can only try to fix it twice like this. If that still doesn’t work, we’ll have to remove the smoke extractor and use a motor to drive the production process
Theoretically, our motor is capable of driving the main fan; we’ve tried it a few times, but we’re worried about extremely high currents. If something goes wrong and causes the motor to trip, that would be problematic, so basically we use a backup motor whenever it’s time to clean the smoke extractor. In my post, what was done was to start the backup unit at no load as a precaution, and then reduce the opening of the flue gas damper to 20%. The temperature in front of the flue gas fan did not decrease at all; instead, the cooling steam control valves on the flue gas fan were adjusted by opening and closing them repeatedly, with the aim of using steam to dislodge the scale that had accumulated on the rotor blades – and this approach achieved the desired result. However, the results are still not very satisfactory. Next time I encounter a situation with excessively high vibration levels, I’ll try your method. :lol
Monitor the motor’s current, power, and other parameters at any time, as well as the overall temperature, vibration, and displacement of the motor
This post was last edited by wt2008 on 2016-9-7 21:24. Recently, I’ve been working with some single-stage exhaust fans, and I’ve found that they are particularly sensitive to any disturbance that disrupts their dynamic balance, resulting in an increase in vibration levels. These increases are often significant or occur rapidly, leading to sharp fluctuations in vibration levels; sometimes the consequences can be difficult to control. Therefore, compared to two-stage systems, single-stage smoke extractors should place more emphasis on preventing scaling in normal operation, rather than on dealing with it once it has occurred. Any online processing can encounter accidents. After reading the original poster’s post, I personally think the scaling on your smoke extractor is quite mild, so there’s no need for frequent treatment; careful consideration should be given to the approach taken when dealing with it.
You’re putting so much strain on your crew; be careful it takes its revenge on you! With the raw materials becoming lighter, haven’t you considered increasing the use of reprocessed oil, or introducing reprocessed oil slurry? To produce more steam, your approach is really unsuitable; you fail to distinguish between what’s important and what’s not. . . . .
If the amplitude of vibration is not very high, it is possible to lower the temperature of the lubricating oil appropriately; it should be no lower than 30°C! I won’t tell you the principle; P
Many things cannot be decided in the workshop; most of the time, we can only carry out orders passively. ;P
Thank you, master; I’ve learned something new again! :handshake