Questions regarding four-effect evaporation
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Our facility has a four-effect evaporation unit. Materials containing water and dimethyl ether enter the wastewater treatment unit through the shell side, while the heavier component, propylene glycol, enters the propylene glycol recovery unit through the tube side. Recently, it was found that the propylene glycol concentration in the shell side is somewhat high, at around 0.8 percent; it is not possible to process this mixture further. I would like to ask experts how we can reduce the propylene glycol concentration in the shell side What are the key operational points for four-effect evaporation?
Is there backflow? Increase the backflow volume. Is the amount of steam added sufficient? Is the thermometer accurate?
The increase in propylene glycol content in the shell side is caused by secondary vapor carrying material during evaporation. The key aspects of the process operation are vacuum level, liquid level, and stable feed and discharge. Please check whether there have been any changes in these process parameters. Another point is whether the heat exchange tubes are cleaned in a timely manner when the evaporator is used for a long time; this is related to heat exchange. Poor heat exchange will also affect the processing capacity and vacuum level.