Low-temperature ethylene vaporizer
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Dear everyone, the low-temperature ethylene vaporizer used in our company operates as follows: the shell side contains methanol, while the tube side contains ethylene. The principle behind its operation is that an electric heater heats the methanol in the shell side, and the methanol vapor is then used to heat the ethylene in the tube side, thereby controlling the temperature of the ethylene gas phase. The question I would like to ask is: what impact does the amount of methanol filled have on the heat exchange efficiency? I hope those with expertise can provide some guidance.
It’s a strange manufacturing process; surely your company and the designers know better the purpose of such a design. I find this strange; the results probably won’t be good, and there are definitely other alternatives available. As for the amount of methanol that can be filled, it is known that the container should not be filled to capacity, in order to prevent thermal expansion from causing the container to burst
Have you never been exposed to cryogenic liquefied hydrocarbons? SEI, Tianchen, and Kunlun are all designed this way.
This usage is rather unusual; it’s better to ask people from SEI, Tianchen, or Kunlun to explain it – it’s difficult for outsiders to understand
A simple analysis will make it clear; this choice is made based on the heat exchange requirements. The purpose of such a design is to allow the gaseous methanol to exchange heat with ethylene using its latent heat of vaporization, resulting in a milder heat exchange process – thereby making it easier to control the temperature on the cold side. If a high heat exchange rate is required, the liquid level on the hot side should be kept low; otherwise, it should be kept higher.
The heat source for ethylene vaporization is primarily provided by the phase change of methanol vapor; relatively speaking, less heat is supplied by the liquid phase of methanol. Therefore, adjusting the liquid level of methanol can be understood as a way to control the amount of vaporization by adjusting the heat exchange area of the vaporizer.
That is to use methanol as saturated steam, which works on the same principle as a reboiler
The methanol level should just be high enough to cover the heat exchanger tubes
Can’t we use low-pressure steam for heat exchange with low-temperature ethylene directly?
Why is methanol chosen as the medium for heating ethylene in the middle stage? Isn’t it bad to use propane or propylene? The cooling capacity can also be recovered using ethylene glycol chilled water. Using electric heating not only results in wasted cooling capacity but also consumes electricity.