CL in methanol distillation wastewater
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Should there be no chloride ions in normal methanol distillation wastewater? If it reaches 30PPM, does it necessarily mean there is a leak in the wastewater cooler, or in one of the water coolers in that tower?
On the second floor, you have facilities for methanol extraction there. Could you share some experience? I am interested in carrying out extraction using a ternary system of methyl acetate, methanol, and water.
The composition of the extraction water in our factory is still DW, and the chloride content in DW is definitely below 10PPM. Only the CW with additives has a high value, right?
Adding extractant water is intended to allow the formed methanol azeotrope to be separated from methanol, so that low-boiling compounds can be removed during distillation to obtain high-purity methanol
Of course, there should be no chloride ions (in the ppb range) during the synthesis phase; if present, they can poison the synthesis catalyst. Therefore, it is most likely that they are introduced by the extraction water
Is it because of the high chloride content in the alkaline solution? We’re using industrially pure material, so the chloride content should be high; it’s just my guess. You might as well give it a try!
It shouldn’t be a water issue. Generally, deionized water is used for extraction. It’s impossible for chloride levels to be too high. Could it be a problem with the alkaline solution? It could also be a leak in the crude methanol preheater.
The distillation wastewater at the bottom of the tower is generally assumed to have a H2O content of 99.5%, CH3OH content of 0.1%, and a content of other alcohols of 0.4%. The influence of perchloride ions is not taken into account. The material used for the heat exchanger is also assumed to be carbon steel.
The wastewater from our plant is sent to gasification coal grinding; the flow rate of the wastewater pump remains constant. Therefore, when the amount of wastewater increases, we need to find out the reason for this. A reboiler is impossible; there’s none even in the steam ； The pressure tower and the three-tower water coolers can’t leak; otherwise, the moisture content of the finished product would already be high ； Methanol synthesis cannot exceed a certain limit, so I suspect the issue lies in the tower and the wastewater cooler. As for the chloride content in the alkaline solution, that wasn’t taken into account; thanks for pointing it out. I’ll go check it after work
It has been analyzed: the chloride content before the wastewater cooler is 2.0 PPM, while it is 26 PPM after the cooler. 10PPM in alkaline solution