Novel plunger used for drainage gas recovery and capable of carrying liquid foaming agent

The invention discloses a novel plunger used for drainage gas recovery and capable of carrying a liquid foaming agent. The novel plunger comprises a plunger outer cavity and a plunger shaft block. A lower cavity is reserved between the plunger outer cavity and the plunger shaft block, the lower cavity is filled with a foam scrubbing agent, and a liquid drainage check valve outputting liquid from inside to outside is arranged on the outer side wall of the lower cavity; a cavity is formed in the plunger shaft block, a mass ball and a limiting stopper are arranged above the cavity, and the mass ball is used for penetrating through the limiting stopper under the inertia effect and moving towards the lower portion of the cavity. A spring buffer is arranged below the cavity, the lower end of the spring buffer extends out of the lower end of the plunger shaft block from the cavity, and the mass ball is used for driving the spring buffer to extend towards the interior of the lower cavity. According to the scheme, whe