Liquefied Gas Recirculation Circuit and Pump

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Solution Overview

Problem

Current methods for transferring liquefied gas, such as gravity unloading and pumping, face challenges including pressure drops, flow rate reductions, energy inefficiency, and operator complexity, particularly due to the need for cooling and narrow operational pressure ranges in cryogenic pumps.

Innovation Solution

A device with a recirculation circuit and axial flow pump using permanent magnets and a field winding for efficient liquefied gas recirculation, coupled with a pressure-measurement sensor and control unit to maintain constant pressure, and powered by electrical energy storage and capture means, allowing for compact, easy operation with minimal cooling requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a cryogenic pump is used to transfer liquefied gas, then the flow rate can be maintained, but the pump requires extensive cooling time and has narrow operational pressure range

Engineering Contradiction:
Improveflow rateVSAvoidcooling time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The pump is pre-cooled by circulating liquefied gas through internal cooling channels before operation. This preliminary cooling action ensures the pump is ready for immediate operation without requiring external cooling equipment or lengthy cooling periods, thus resolving the contradiction between maintaining flow rate and reducing cooling time.

Inventive Principle:
Principle #10Preliminary action

2Stress or pressure

If a recirculation circuit with atmospheric heater is used to compensate pressure drop, then pressure can be maintained, but the system complexity increases

Engineering Contradiction:
ImprovepressureVSAvoidsystem complexity
Core Design Contradiction:
Stress or pressureVSDevice complexity

Solution Approach 1:

The recirculation circuit is integrated with the transfer circuit, and the atmospheric heater is combined with the pump structure. The pump serves dual functions: transferring liquefied gas and recirculating it for pressure compensation. This merging reduces the number of separate components and simplifies the overall system while maintaining pressure compensation capability.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If pump operation is controlled within narrow pressure range, then sealing and wear are optimized, but operator difficulty increases

Engineering Contradiction:
Improvesealing performanceVSAvoidoperator difficulty
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

A pressure sensor continuously monitors the pressure in the container and provides feedback to the control system. The control system automatically adjusts the pump operation based on the measured pressure, ensuring it remains within the optimal range for sealing performance and minimizing wear. This automated feedback control eliminates the need for operators to manually monitor and adjust pressure, reducing operational difficulty while maintaining reliability.

Inventive Principle:
Principle #23Feedback

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

The solution maintains constant pressure during transfer, reduces energy consumption, simplifies operator control, and enhances the reliability and efficiency of liquefied gas transfer, addressing the limitations of existing systems.

Implementation Method 1

a recirculation circuit that opens out into the container via an end of a duct forming part of this circuit and that is arranged to receive liquid phase from the container bottom and to deliver it to the container top

Methodology Applied
Scientific EffectRecirculation flow:

Implementation Method 2

a heat exchanger arranged to heat the liquid phase leaving the container via this circuit, so as to cause this liquid phase to boil

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

cause this liquid phase to boil, this circuit returning with the gas phase that results from this boiling

Methodology Applied
Scientific EffectBoiling: Boiling

Implementation Method 4

a bladed wheel mounted to rotate inside the pump body and having permanent magnets arranged at the periphery of the wheel, the pump further including a field winding arranged to drive the wheel in rotation by means of the magnets

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentEP3368815B1Device for transporting liquefied gas and method thereof
Publication Date: 2022.06.22 CRYODIRECT LTD
  • EP3368815B1 patent drawingFigure 1
  • EP3368815B1 patent drawingFigure 2
  • EP3368815B1 patent drawingFigure 3

AI summary

A device and method for transporting a liquefied gas (29, 30) comprises: a thermally insulated container (12) for containing the liquefied gas (29, 30) under pressure; a circuit (17, 18) for transferring the liquefied gas (29, 30) in the liquid phase (29), which is connected to the bottom portion of the container (12), does not include a pump, and includes a member (24) for connection to a tank (25) or to a gas transport network that is to be fed with gas such that the liquefied gas (29) is allowed or ensured to be transferred to the tank (25) or to the network under the effect of a higher pressure in the container (12); and a circuit (19, 20, 21, 22) for recirculating the liquefied gas (29), which is connected to the top portion of the container (12) and includes a heater (11) and a recirculation pump (15) that is connected in series with the heater (11), upstream from the heater (11), and is arranged to deliver into the heater (11) the pumped liquefied gas (29) taken from the bottom portion of the container (12) so as to accelerate the circulation of the liquefied gas (29) through the heater (11). The pressure of the gas space (30) in the container (12) can be maintained or increased by the recirculating circuit (19, 20, 21, 22).