A plant chemical company originally designed a 20m shell-and-tube heat exchanger for decompression concentration and recovery of methanol, acetic anhydride, and petroleum ether. Now it uses a 4m spiral wound tube heat exchanger. Not only does it greatly reduce the heat exchange area, saving installation costs, but it also increases the concentration volume per unit time by 3-4 times, the outlet temperature is lower, the recovery rate is also improved accordingly, and the unit consumption of products is greatly reduced.