Cryogenic Tank Pump Column Layout for Low-Level Liquid Extraction
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Solution Overview
Problem
Existing cryogenic full containment storage tanks have a large ineffective working volume at the bottom due to the minimum operable liquid level requirement of submersible pumps, leading to residual medium that cannot be extracted efficiently.
Innovation Solution
A cryogenic full containment storage tank design incorporating a pump column and a material pre-extraction device with a Venturi mixer and cofferdam to create a higher liquid level, allowing extraction of low-temperature medium below the minimum operable level, utilizing the entrainment effect of the Venturi mixer to suck in medium from outside the cofferdam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cryogenic submersible pump is used to discharge liquid from the storage tank, then the pump can operate under the liquid, but the minimum liquid level must be maintained at about 1.2m above the bottom, creating a large ineffective working volume
Solution Approach 1:
The storage tank is divided into two functional zones: a cofferdam (pump pool) at the bottom with height of 1.2-1.5m that maintains minimum liquid level for pump operation, and the upper storage zone that provides effective working volume. This segmentation allows the pump to reliably operate while maximizing the usable storage volume.
Solution Approach 2:
The cofferdam acts as an intermediary structure between the pump and the main storage zone. It maintains the minimum liquid level required for pump operation while allowing the main storage tank to be emptied to a much lower level, thus resolving the contradiction between pump reliability and effective working volume.
2Quantity of substance
If the storage tank height is increased to accommodate larger capacity, then the storage capacity increases, but the ineffective volume at the bottom also increases proportionally
Solution Approach 1:
The bottom portion of the tank (cofferdam) is given a specialized function of maintaining minimum liquid level, while the upper portion provides bulk storage. This local differentiation of function allows the tank to achieve high storage capacity while minimizing the proportion of ineffective volume.
3Ease of operation
If vaporization is used to discharge material from the bottom of the tank during maintenance, then the residual medium can be removed, but it consumes a lot of energy and requires a long period of time
Solution Approach 1:
The cofferdam is pre-configured with a discharge pump and piping system during normal operation. During maintenance, this pre-existing infrastructure can immediately discharge residual material without requiring energy-intensive vaporization, thus reducing both energy consumption and discharge time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces the ineffective volume by allowing extraction of low-temperature medium beyond the minimum operable level, increasing the effective working volume and reducing the tank's height, thus improving utilization and saving engineering investment.
Implementation Method 1
an entrainment effect of local low pressure and high-speed flow is formed in the Venturi mixer, so that the low-temperature medium outside the cofferdam in the inner tank is sucked into the Venturi mixer through the suction hole under the action of the pressure difference
Implementation Method 2
a discharging pump arranged in a pump column extending from a roof of the outer tank into a bottom of the inner tank; the low-temperature medium in the pump column can be inputted into the Venturi mixer
Data Source
Figure 1
Figure 2~3
AI summary
Provided is a low-temperature full-capacity tank for realizing a low liquid level material extraction function by using a pump column, comprising an inner tank (1), an outer tank (2), a pump column (3), a submersible pump (4) and a material pre-extraction device (5); wherein the material pre-extraction device (5) comprises a cofferdam (51), a Venturi mixer (52), a backflow pipe (53), a return control valve (55), a lead-out pipeline (54) and a liquid level detection system (56); wherein the cofferdam (51) is located at the bottom of the inner tank (1) and surrounds the outside of the pump column (3); the height of the cofferdam (51) is greater than the minimum liquid level required for the normal operation of the submersible pump (4); the Venturi mixer (52) is installed at the bottom of the inner tank (1) and located outside the cofferdam (51), with a suction hole (5202) on the outer circumference thereof; the backflow pipe (53) is connected to the upper part of the pump column (3) to the inlet of the Venturi mixer (52); the return control valve (55) is set on the backflow pipe (53); and the lead-out pipe (54) is connected to the outlet (5203) of the Venturi mixer (52) to the inside of the cofferdam (51). The low-temperature full-capacity tank can make use of a low-temperature medium flowing back from the pump column (3) to extract the low liquid level material outside the cofferdam (51) into the cofferdam (51) to form a local high liquid level and maintain the normal operation of the submersible pump ( 4), thereby reducing the lower limit of the operating liquid level in the tank and improving the volume utilization rate.