Drainage at the lowest point of the heat exchanger
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In chemical production, for various heat exchange devices such as heat exchangers and reboilers, is there only a low-point drain in the shell side, or are there drains in both the shell side and the tube side? Is it still the manager that enables low-point sewage discharge? I’m referring to the general case; don’t give examples of the behavior of specific substances. Under normal circumstances, it is the substances with lower temperatures that flow through the shell side, following the principle of low inlet and high outlet. If there is drainage from the shell side, then what is drained is the waste from the previous process stages, not the dirt accumulated within the heat exchanger itself
What you say makes a lot of sense. However, by \"discharging waste\", what is meant is the removal of impurities from the fluid – usually corrosive substances – whose density is generally higher than that of the fluid itself; therefore, the waste discharge outlet must be placed at a lower level.
The drain point is definitely at the lowest position; otherwise it wouldn’t be called a low-point drain or low-point discharge outlet. However, on the design flow diagram, each heat exchange unit has only one drain. I wonder whether, under normal circumstances, the low-point drain is located at the inlet of the shell side or at the outlet of the tube side. For example, the crude methanol vapor coming out of the methanol synthesis tower passes through the gas preheater before entering the tower, where it exchanges heat with the converted gas. In the diagram, this is indicated as the low-point drain at the outlet of the tube side. If it were on the shell side, then the drain would have to be located at the inlet of the next heat exchanger. But my supervisor once told me that generally, the low-point drain is installed on the shell side. Now I’m completely confused
For shell-and-tube heat exchangers, low-point drainage is carried out on the shell side, while there is no drainage on the tube side. Your master is right.
For shell-and-tube heat exchangers, low-point drainage is carried out on the shell side, while there is no drainage on the tube side.
Oh, I see. Thank you all for your advice
Generally speaking, for materials flowing from a lower level to a higher one, since there is material remaining in the pipeline after the inlet valve is closed, it is usual to install a drain valve at its inlet end (the lower point)； For materials flowing from a higher level to a lower level, it is generally not necessary to install a drain valve; however, depending on the specific circumstances, a drain valve can be installed at its outlet end (the lower point) ； That’s also fine.
Zhang Jun, you should have said it earlier. I wouldn’t have come up to ask; I could have just asked you directly
For shell-and-tube heat exchangers, it is necessary to drain the tube side as required! ! A plug can be used for occasional waste discharge! !
Waste discharge at the lower point and exhaust at the higher point – it depends on the specific connection points; it can be either in the pipe side or the shell side. As for heat exchange, it can be either counter-current or co-current, and this also needs to be determined based on the actual conditions, taking into account factors such as equipment safety and heat exchange efficiency; there is no one-size-fits-all solution