Alkali washing system and alkali washing method for removing and recovering residual auxiliary agent in vinyl chloride monomer

The alkali washing system comprises an alkali washing tower, the alkali washing tower comprises an alkali washing upper tower and an alkali washing lower tower, the bottom of the alkali washing lower tower is provided with a recycled monomer gas inlet pipe, the top of the alkali washing upper tower is provided with a recycled monomer gas outlet pipe, and the recycled monomer gas outlet pipe is provided with a recycled monomer gas outlet pipe. An upper tower alkali liquor feeding pipeline and a lower tower alkali liquor feeding pipeline are respectively arranged at the upper parts of the upper alkali washing tower and the lower alkali washing tower, an alkali liquor circulating pipeline is arranged between the upper tower alkali liquor feeding pipeline and the lower tower alkali liquor feeding pipeline, and an upper tower circulating pump and an upper tower cooler are arranged between the upper tower alkali liquor feeding pipeline and the upper tower alkali liquor discharging pipeline; and a lower tower circul