Method and device for recovering byproduct chloromethane in preparation of glyphosate or dimethyl phosphite

The invention provides a method for recovering byproduct chloromethane in preparation of glyphosate or dimethyl phosphite. The method comprises the steps of sequentially carrying out pressurized absorption, primary steam stripping, normal-pressure absorption and secondary steam stripping on the byproduct chloromethane. The invention provides a brand new process of pressurized absorption, steam stripping, normal pressure absorption and steam stripping for removing dimethyl ether in chloromethane by taking water as an absorbent, and the problem that dimethyl ether and chloromethane are difficult to separate is essentially solved; and under the condition that the purity of the chloromethane product reaches 99.5% or above, the recovery rate is ensured to exceed 95%. Steam stripping is adopted, other components are not introduced, and the process route is clean, simple and convenient. Separated dimethyl ether tail gas serves as fuel to be fed to be incinerated, and the safety risk in the using process of concentra