Gas Expansion Cooling Capacity Control via Liquid Refrigerant Storage
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Solution Overview
Problem
Gas expansion cooling systems face challenges in capacity regulation, particularly in large installations, where reducing cooling medium flow leads to efficiency losses and difficulties in maintaining low temperatures, often resulting in gas loss and prolonged recovery times.
Innovation Solution
A method and system that temporarily liquefy a fraction of the cooling medium at higher pressure, store it, and reintroduce it when needed, allowing for quick capacity adjustments by evaporating the liquid back into the circuit, thereby reducing the system's filling rate and operating pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cooling medium flow rate is reduced to achieve capacity regulation, then the cooling capacity is reduced, but the expansion turbine efficiency and power output decrease and control problems arise
Solution Approach 1:
The invention changes the phase parameter of the cooling medium from gas to liquid by introducing a liquefaction stage before storage. This parameter change allows the cooling medium to be stored in liquid form at lower pressures, and when needed, evaporated back to gas phase to maintain expansion turbine efficiency and reliable operation while achieving capacity regulation.
Solution Approach 2:
The invention utilizes phase transitions of the cooling medium (gas to liquid during storage, liquid to gas during retrieval) to enable capacity regulation. By liquefying the cooling medium for storage and then evaporating it back to gas phase for reintroduction into the circuit, the system maintains expansion turbine reliability while adjusting cooling capacity.
2Quantity of substance
If the operating pressure is reduced to achieve lower cooling duty, then the cooling capacity is reduced, but the system requires permanent or temporary removal of cooling medium from the closed loop
Solution Approach 1:
The invention uses phase transition to liquid form for storage and back to gas phase for quick recovery. By storing cooling medium in liquid form and evaporating it when needed, the system achieves rapid capacity restoration without the lengthy recovery times associated with gas-phase storage or re-compression.
Solution Approach 2:
The invention changes the physical state parameter of the cooling medium to enable efficient storage and rapid recovery. By converting to liquid phase for storage (smaller volume) and back to gas phase for circuit reintroduction, the system minimizes both storage requirements and recovery time.
3Quantity of substance
If cooling medium is stored in compressed gas form, then large amounts of gas can be stored, but considerably larger storage volumes are required compared to liquid form
Solution Approach 1:
The invention utilizes the phase transition to liquid form for storage purposes. By liquefying the cooling medium before storage, the system achieves much higher density and storage capacity in a given volume compared to compressed gas storage, while maintaining the ability to quickly evaporate and reintroduce the cooling medium when needed.
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
This approach enables rapid cooling capacity adjustments with smaller storage volumes, maintaining efficiency and reducing gas loss, especially beneficial for large installations like LNG production.
Implementation Method 1
a gaseous cooling medium goes through a work cycle based on compression, cooling, expansion and thereafter, heat exchange with the fluid that is to be cooled down
Implementation Method 2
The gas expansion leads to the generation of a very cold gas, or a mixture of gas and liquid
Implementation Method 3
The liquefied gas can at any time be evaporated into the cooling circuit again to quickly increase the duty of the cooling installation
Data Source
AI summary
A method and associated system for regulation of the cooling capacity of a cooling system that uses a gas expansion cooling circuit where the cooling principle is expansion of one or more gaseous cooling medium streams from a higher pressure to a lower pressure are described, characterised by the following steps: —reducing the amount of cooling medium which is circulated in the cooling circuit (100) temporarily in that a fraction of gaseous cooling medium is pre-cooled at a higher pressure and is extracted from the cooling circuit (100), —expanding the fraction of cooled gaseous cooling medium across an expansion device (102) to a lower pressure so that at least one part of liquid cooling medium separates, —separating the liquid from the non-condensed gas for temporary storage in a storage unit (104) so that the liquid is temporarily not circulated in the otherwise closed cooling circuit (100), —thereafter to return temporarily stored gaseous cooling medium from the storage unit (104) to the cooling circuit (100) according to need, and—returning non-condensed gas and evaporated cooling medium from the storage unit (104) to a suitable location in the cooling circuit (100). A system to reduce the cooling capacity of a cooling installation based on gas expansion cooling, is also described.