Control of methanol separation temperature
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Our facility has newly installed a methanol system, with the outlet temperature of the water cooler being controlled at around 30 degrees; after that, the fluid goes into the methanol separator. However, methanol still escapes from behind the separator. Is this due to an inadequate separation efficiency or to the high temperature control? So, what temperature should be maintained behind the water cooler in order to prevent wax buildup? I would appreciate some guidance from experts. Thank you. This post was last edited by sdtzwh on 2007-12-2 13:51]
The outlet temperature of our water cooler is 32 degrees, and the liquid level in the separator is kept at around 400 mm. The alcohol content in the washing alcohol solution is 5%, and the separation effect is still good. I think the outlet temperature of the water cooler in your factory could be increased by a few degrees, and the amount of alcohol-water mixture used could be increased; this might yield better results.
If the temperature after water cooling is kept below 40 degrees, there should be no problems; at that temperature, most of the methanol will have condensed, and substances such as paraffin can also be condensed and separated. It’s normal for some methanol to be carried away along with the alcohol components – it’s not possible to achieve 100% condensation. Consider checking or modifying the separator, by adding an alcohol-washing device at the top of the separator to wash the circulating gas. This way, first, the production volume can be increased, and second, the composition of the gas can be optimized...
Wax formation has little to do with the temperature after separation; there is no need to lower the temperature significantly, as it is not cost-effective. Please, the original poster, clarify what the main purpose of starting this topic is.
The unit that designed it stated that the lower the temperature at the beginning of operation, the better the separation effect; however, colleagues from another unit who trained us on how to operate it said that the temperature should not be too low, as this would cause wax-like substances to form at the water-cooling areas, leading to blockages. It seems that the cooling efficiency of our water-cooling system is getting worse, and the system resistance has increased. I started this discussion in order to ask everyone what temperature would be appropriate. Our current heat exchange efficiency is poor; could it be that the temperature is too low, resulting in waxy substances adhering to the heat exchanger?
I think a water cooling temperature of around 40 is quite suitable; it’s normal for methanol to be carried away, but what matters is the amount of methanol that is carried away. Additionally, the pressure used to control the alcohol content also has a significant impact on the separation efficiency. . . . . . .
It’s definitely due to poor separation efficiency; liquid alcohol is present, and it has nothing to do with the water cooling temperature
There are many factors that affect the performance of alcohols, such as liquid level, water cooling temperature, and the pressure of the alcohol; a comprehensive analysis is necessary when examining these aspects. . . . . . . . .
Keeping the outlet temperature of the water cooler at around 30 degrees is already low enough. What level is the liquid level in your methanol separator controlled at? It’s important to verify the accuracy of this level; 40% should be sufficient. Also, could it be that the demister in your separator has fallen out? If that’s the case, the gas coming out of the top of the methanol separator will definitely contain alcohol.