What to do if the temperature of the acid gas after low-temperature methanol washing does not reach the designed value in the water cooler?
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As the title suggests, in the Luchi process, the temperature of the acid gas at the outlet of the thermal regeneration tower, after passing through the water cooler, is designed to be 35 degrees. However, in actual operation it is preferable for this temperature to reach over 45 degrees. I’m not sure whether it’s due to a small heat exchange area or some issue with the operation procedures. Please help discuss what could be causing this situation.
The heat exchange efficiency is poor – is the heat exchanger clogged or leaking? It’s possible in either case; it’s better to conduct an analysis to rule things out, as a dirty inner wall of the heat exchanger can also affect its performance. :)
There are too many reasons; without detailed information, no one can make a diagnosis. . . Check the water temperature; if it’s above 35 degrees, how can it be reduced to below 35? Also, check the water flow rate – is there any blockage on the water side that’s causing a low flow? Is there any non-condensable gas in the circulating water side? . . . Also, what is the installation height of this water cooler? Is it possible that its position is too high, preventing the circulating water from reaching there, or causing a negative pressure on the water side that draws in air? . . . There are too many reasons; otherwise, let’s check the design issues
Are the temperature and pressure at the top of your tower different from the design values?
It can be determined from several aspects: (1) If the return water temperature is also higher than the design value, it is possible to consider whether there is an insufficient water flow； (2) If the return water temperature is normal, there are two possible reasons: the steam volume at the top of the tower exceeds the design value ； The heat exchange area of the heat exchanger is small or its heat exchange efficiency is low (due to scaling, etc.)
There is basically no difference; normal operations are carried out based on the design values. As long as the sulfur content in the purified gas is within acceptable limits, the temperature of the acidic gas coming out of the thermal regeneration tower is kept as low as possible compared to the design value, so that the temperature of the acidic gas at the water cooler also reaches the design value.
It was cleaned during the major repair, and the only possible explanation now is that the heat exchange area has decreased. Initially, it was suspected that the amount of circulating water was insufficient; to address this issue, a circulating water booster pump was installed.
It seems that the heat exchange area is insufficient and the heat exchanger is undersized. I wonder if there are any ways to improve the heat exchange capacity without replacing the heat exchanger.
First, it is important to observe the temperature difference between the cold and hot ends: if the difference is small, it indicates that the heat exchanger is performing well in terms of heat transfer, and there are no issues with its design. This post was last edited by Shujian on 2009-3-31 10:54.]
You can check if the water cooler is clogged! We have encountered the problem of a clogged water cooler, with sand all inside it! After cleaning, the metrics are qualified!
It has been cleaned; it’s not too dirty. There isn’t much change in its condition
The load on the methanol water tower is too high, and the temperature of the gas exiting the tower is too high; I guess the water content in your system must be higher than the designed value
Is the cooling water flow too low, or is there a blockage? It’s best to stop the car first and check it carefully, otherwise it will affect the purity!
Could the original poster tell us about the operating pressure and temperature you use? [It’s not a secret at all.] Let’s see if it’s possible to lower the temperature at the top of the tower by reducing the operating pressure and temperature!
It’s certainly no secret: the outlet temperature of the lean methanol stream from our thermal regeneration tower is 98 degrees, while the designed value at the top of the tower is 82.4 degrees; in practice, however, this temperature remains around 81 degrees, with a pressure of 0.22 MPa.
I think the temperature at the top of your tower is too high! The operating pressure at the top of the tower here is 0.31 M, while it is 0.34 M at the bottom of the tower; the operating temperature at the bottom of the tower is also 98 degrees! So I think the operating temperature at the bottom of your tower is high; could it be that the amount of nitrogen used for stripping in your hydrogen sulfide concentration tower T103 is too low, or that the operating pressure is too high?
The design decisions must not be deviated from too much, for fear that it might cause the hydrogen sulfide content in the purified gas to exceed the allowed levels.
What those upstairs said is all based on inspections from the water side; I suggest that you check whether the amount of nitrogen used for stripping in Tower T3 is too low, which results in a high carbon dioxide content in the methanol-rich stream entering the heat regeneration tower. As a result, the carbon dioxide content in the acidic gas exiting the tower is also high. If the flow rate increases, it may be impossible to lower the temperature of the acidic gas at the outlet of the cooler!
We hadn’t considered this aspect, but generally, the amount of nitrogen gas we remove by air lift is on the high side, based on the ratio between the volume of the converted gas and the designed value for nitrogen gas. Over the past two years, it has become clear that this is due to insufficient heat exchange in the heat exchanger, resulting in suboptimal heat transfer effects. Therefore, we need to consider changing the size of the heat exchanger
Has it been like this since it was put into use? The nitrogen stripped is low. . C4 also means overpressure. Load shifts upward. If it was working fine before but started to malfunction after maintenance. It’s due to the heat exchanger