Drainage system of pressure vessel

The utility model provides a pressure vessel drainage system. The pressure vessel drainage system comprises a pressure vessel tank, a liquid level detection part, a drainage part and a control part. The drainage part comprises two drainage pipelines which are arranged in parallel, and each drainage pipeline is provided with a one-way valve and a manual valve. The liquid level detection part can detect the liquid level height of accumulated water in the pressure container in real time, when the liquid level height reaches the set height, the control part controls the one-way valve to be opened to discharge the accumulated water, and when the liquid level height drops to the safety range, the control part controls the one-way valve to be closed, and automation of drainage of the pressure container is achieved. The manual ball valve does not need to be opened regularly manually to drain accumulated water, the labor intensity is reduced, the liquid level in the pressure container tank is controlled within a reaso