Crude monomer separation energy-saving method and device

According to the energy-saving crude monomer separation device and method, crude monomers enter a first rectifying tower, high-boiling gas phase substances are removed from the tower top, the crude monomers enter a reboiler of a tower kettle of a third rectifying tower for condensation, one part serves as tower reflux and returns to the tower top of the first rectifying tower, and the other part enters a second rectifying tower. Light components are extracted from the top of the rectifying tower II, and a rectifying tower III and a rectifying tower IV are extracted from the tower kettle; tower top gas-phase materials of the third rectifying tower enter tower kettle reboilers of the second rectifying tower and the fourth rectifying tower respectively, after condensation, one part serves as tower reflux and returns to the rectifying towers, and products are extracted from the other part; a methyl trichlorosilane product is extracted from the tower top of the fourth rectifying tower, and a dimethyl dichlorosilan