Water seal structure of periodic blowdown flash tank

The utility model discloses a water seal structure of a periodic blowdown flash tank, and belongs to the technical field of boiler steam water of a thermal power plant. Comprising a first vertical pipe section connected with a drain outlet in the bottom of the periodic blowdown flash tank, a second vertical pipe section connected with the bottom of the first vertical pipe section through a first connector and a third vertical pipe section connected with the top end of the second vertical pipe section through a second connector. The parts of the first vertical pipe section, the second vertical pipe section and the third vertical pipe section, which are exposed out of the cover plate at the upper end of the pollution discharge cooling pool, and the second joint are arranged in a heat preservation manner; the lower part of the first vertical pipe section, the first joint, the lower part of the second vertical pipe section and the lower part of the third vertical pipe section are all arranged in the pollution dis