Help! Ask an expert about the distillation tower

Check to see if the reboiler is mounted on the wall. The heat transfer effect is not good.

1. First check whether the measuring instrument is accurate. 2. Whether the reboiler circulation is smooth. 3. Check whether there is liquid leakage between the liquid redistributor and the tower wall, and whether the wall flow in the packing layer is serious. If leakage and wall flow are serious, the liquid will flow directly to the tower kettle, causing the light components of the tower kettle to exceed the standard and the temperature to be unable to rise.

1. Is the heat exchanger scaled? 2. Is the forced circulation pump normal?

1. Check whether the reboiler is scaled 2. Check whether the operating pressure of the tower is normal 3. The reboiler may have poor circulation

I think it may not be a problem of reboiler scaling or circulation, because since the packing and tower have been cleaned, these must have been checked. Is it possible that the pressure of the tower is low and the pressure gauge does not truly show it.

Fouling of the reboiler, too small a pressure difference, and poor circulation are the first things to check. There are also changes in feed volume.

Thank you for your advice. It should be pointed out that: The pressure of the tower should be fine. The on-site pressure gauge and DCS display are basically consistent. ； Includes reboiler steam flow and steam pressure. Also, I don’t quite understand the meaning of wall hanging and scaling in the reboiler (not long after I graduated from school). Does it mean that the inner wall of the heat exchanger tubes (the shell layer carries steam, and the tubes carry material) is the material scaling or the shell layer? The steam should not contain magnesium carbonate and calcium carbonate, right? :loveliness: :loveliness:

Check the inner wall of the reboiler tube immediately. It must be blocked by scale. According to experience, when the temperature of the tower kettle obviously cannot rise, it is mostly caused by scaling of the reboiler tubes. What material is your filler made of? Are the grids intact?

Thanks to this brother, the packing of the tower is a metal saddle ring, the grid is intact, and there is a liquid redistributor with eight holes blocked (a total of 36 holes). After cleaning and restarting, the kettle still cannot warm up. The reboiler finger removed the upper and lower heads and moved them a little. The leader checked that there was no blockage and then reinstalled it. I checked that there was no blockage, but there was obviously something stuck on the inner wall of the tube, but I did not dare to raise an objection to the leader due to lack of experience. If the reboiler is scaled, what can be done to solve it? Thanks! This post was last edited by Crazy Distillation on 2009-3-13 22:38 ]

If it is scaling on the inner wall, you can use a special detergent. If it is scaling on the outer wall, it is probably due to coking of the material. It depends on the nature of the material before deciding what to use for cleaning:)

It may be due to scaling or blockage. When we first used the reboiler, the temperature could not rise. Later, after adjusting the tower liquid level, the tower pressure suddenly rose and caused the safety valve to trip, which only took 2 seconds. I think maybe your packing fell to the bottom of the tower and blocked the pipeline. I suggest maintenance and inspection.

For old systems, the reboiler may be clogged 70% of the time, so chemical cleaning is recommended. Polycrystalline silicon has high requirements for packing. After chemical cleaning, the packing should not be a problem. Moreover, the temperature at the bottom of the tower has not changed, so the heat of the steam has not been transferred to the circulating liquid. 1. Check whether the steam condensate accumulates in the heat exchanger, whether the condensate outlet flow is the same as before, and the size of the heat exchange area. 2. Chemically clean the tubes, prepare washing liquid according to the medium, or use a professional cleaning company. 3. Check the internal circulation structure at the bottom of the tower, such as anti-collision plates, etc.

If the tower pressure is normal, it means that the content of light components in the column material is high, the heat exchange effect of the reboiler is not good, and the light components cannot be evaporated. There are many reasons for poor heat exchange effect: It may be due to scaling, blockage, non-condensable gas on the steam side, small reboiler circulation volume, etc. . . .

Usually check the following parameters of the tower to check whether the top pressure is normal. If it is too small, lift it up. To reduce the problem, reduce the reflux ratio. Is there any change in the composition of the feed, whether there are more light things and less heavy things. Is there any problem with the production volume at the top of the tower? Is there any problem with the production volume at the bottom of the tower? Is the tower pressure indicator normal? The temperature indicator and the liquid level indicator are scaling. This post was last edited by Albertlu on 2009-3-14 23:35 ]

1. The steam and condensate flow rates do not change much, which is definitely not a problem with the reboiler. If scaling and other phenomena occur, the heat transfer will decrease significantly. 2. You should first consider your material balance. There may be problems. Check whether there are problems in the extraction of the tower top and tower kettle. Calculate whether the amount of materials extracted from the tower top and tower kettle is appropriate. You can make appropriate adjustments. 3. At the same time, check whether the load of the tower top condenser meets the requirements. If the condensation is incomplete, some gas phase materials may be discharged with the tail gas. Check the opening of the tail gas discharge valve. 4. Appropriately adjust the return flow and increase the return flow within the operating load, which is effective for separation. However, if the return flow is too large and exceeds its processing capacity, the separation effect will be significantly reduced. 5. Reduce the feed load appropriately to see if there is improvement.

The circulation pipe at the lower part of the reboiler may also be scaled. Generally, if the reboiler is scaled, the circulation pipe will also be clogged due to excessive scale. I have encountered this situation before. Your reboiler must be scaled, but according to you, shutting down the boiling tower should be able to solve the problem.

Does the pressure of your tower meet the requirements? Is your water delivery device too small? Have you tried opening a pay line? Is there any excess heating area of ​​the reboiler? Have you recalculated the heating area?

Is your distillation column new equipment or has it been used for some time?

Most likely the reboiler efficiency is reduced: Including scaling, inert gas accumulation, steam quality, etc., scaling treatment: High pressure water cleaning is followed by component issues: Wall flow or channel flow occurs in the packing layer, the kettle liquid contains many light components, and the temperature cannot be raised. ； Changes in feed composition may also lead to instrument problems.