Cryogenic full containment storage tank for realizing low-liquid-level material extraction function by using pump column

A cryogenic full containment storage tank for realizing a low-liquid-level material extraction function by using a pump column, applied to petrochemical industry, comprising:

• an inner tank;
• an outer tank surrounding a periphery of the inner tank;
• a pump column extending through a roof of the outer tank to a bottom of the inner tank;
• a submersible pump arranged in the pump column;
• and
• a material pre-extraction device for extracting low-liquid-level material in cooperation with the pump column, comprising:
• a cofferdam with a diameter ranged from 3 m to 5 m and about one tenth of a diameter of the inner tank at most, arranged at the bottom of the inner tank and surrounding an outside of the pump column, and fixed with a bottom of the inner tank to form a pump pool, wherein a height of the cofferdam is greater than a minimum liquid level required for a normal operation of the submersible pump;
• a plurality of Venturi mixers connected in parallel, and arranged at the bottom of the inner tank and located outside the cofferdam, two ends of which are respectively an inlet and an outlet, wherein a suction hole is arranged on an outer periphery of the plurality of Venturi mixer, and the suction hole is communicated with an interior of the inner tank;
• a return pipeline, communicating an upper part of the pump column with the inlet of the plurality of Venturi mixer;
• a return control valve, arranged on the return pipeline to control a state of opening and closing and a return flow of the return pipeline;
• an outlet pipeline, communicating the outlet of the plurality of Venturi mixer with an interior of the cofferdam;
• and
• a liquid level detection system for detecting a liquid level in the cofferdam to ensure that the liquid level in the cofferdam is not lower than the minimum liquid level required for the normal operation of the submersible pump.