Recycling method for methanol in formaldehyde production

The invention relates to a recycling method for methanol in formaldehyde production; a formaldehyde solution after reaction in an oxidation device is subjected to formaldehyde cyclic absorption through a first-level absorption tower, a second-level absorption tower and a third-level absorption tower, a third-level absorption tower circulating liquid is subjected to partial formaldehyde cyclic absorption through a circulating pump, a part of the circulating liquid is sent into a rectifying tower, 0.25 MPa steam self-produced by the oxidation device is introduced into the rectifying tower, the circulating liquid is rectified to obtain 98% fine methanol, the 98% fine methanol is introduced into a methanol evaporator through a pipeline, residual liquid rectified out by the rectifying tower returns to the second-level absorption tower and is subjected to repeated cyclic absorption. The recycling method has the advantages that the three-tower circulating liquid is finely processed by the rectifying tower into the 98% fine methanol for reutilization, the consumption of methanol is reduced, the alcohol content in the finished product is reduced to be beneficial for production of downstream products pentaerythritol and neopentyl glycol, and the content of wastewater COD in the production process of the two products is reduced.