Cryogenic Fluid Supply with Phase Separation for Stable Machining
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Solution Overview
Problem
Existing systems for supplying cryogenic liquids, such as liquid nitrogen, in machining operations face challenges in maintaining consistent temperature and pressure conditions, leading to variations in the two-phase flow rate, which affects machining quality and efficiency, and previous solutions like phase separation and venting result in inefficiencies and costs due to gas loss and thermal bridging.
Innovation Solution
A system that measures fluctuations in the two-phase flow rate by monitoring gas flow at the outlet of a degasser pot, allowing for adjustments to maintain consistent operating conditions, including using a flow sensor to detect gas flow and determine opening times, and implementing actions to inform the user station or modify operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If phase separation means are used to supply cryogenic liquid to the user station, then the liquid/gas two-phase ratio can be controlled, but the system complexity and operational disturbances increase due to continuous monitoring and adjustment requirements
Solution Approach 1:
The patent applies preliminary action by performing phase separation in advance within the storage tank before the cryogenic liquid is supplied to the user station. The separation means are located inside the tank, where gas is removed from the liquid phase beforehand, ensuring that only liquid or controlled two-phase mixture is discharged. This preliminary separation eliminates the need for complex external monitoring and adjustment systems, as the composition is stabilized before supply.
Solution Approach 2:
The patent introduces an intermediary phase separation mechanism within the storage tank that acts as a mediator between the stored cryogenic fluid and the user station. This internal separation system prevents direct contact between gas and liquid phases during supply, using the separation means as an intermediary component to control the two-phase ratio without requiring complex external control systems.
2Ease of operation
If the storage tank operates at fixed gas pressure, then the system is simple to operate, but the liquid pressure and flow rate vary with liquid level, causing operational disturbances
Solution Approach 1:
The patent implements feedback control by continuously monitoring the liquid level in the storage tank and automatically adjusting the operation of the phase separation means or discharge valve accordingly. As the liquid level changes, the system detects this variation and adjusts the separation or discharge rate to maintain consistent liquid pressure and flow rate at the user station, eliminating operational disturbances while keeping the system easy to operate.
Solution Approach 2:
The patent applies dynamics by making the phase separation means or discharge mechanism adjustable based on liquid level conditions. Rather than a fixed system, the separation efficiency or discharge rate dynamically adapts to the current liquid level, ensuring stable liquid pressure and flow rate delivery to the user station while maintaining operational simplicity through automated adjustment.
3Temperature
If venting is used to depressurize the storage tank, then the cryogenic liquid temperature decreases improving cooling quality, but significant nitrogen loss occurs
Solution Approach 1:
The patent applies discarding and recovering by capturing the gas phase that would otherwise be vented and redirecting it back into the storage tank or to useful purposes. The phase separation means separate the gas from the liquid, and the recovered gas is reused to maintain pressure or temperature control without requiring fresh nitrogen, thus improving cooling quality through controlled temperature management while minimizing nitrogen loss.
Solution Approach 2:
The patent converts the harmful effect of gas venting (nitrogen loss) into a beneficial process by using the separated gas phase for useful purposes such as maintaining tank pressure, pre-cooling incoming liquid, or controlling the two-phase ratio. The gas that would be wasted is instead utilized to improve the overall system efficiency and reduce nitrogen consumption while achieving the desired temperature reduction.
4Duration of action of stationary object
If repressurization is used after venting, then the storage tank can be reused, but hot gas introduction causes thermal bridging and increases system complexity
Solution Approach 1:
The patent applies self-service by enabling the storage tank to repressurize itself using the gas phase that is already present in the system after phase separation. The separated gas is redirected back into the tank to restore pressure without requiring external hot gas introduction or complex repressurization equipment. This self-repressurization mechanism maintains tank availability while avoiding thermal bridging and system complexity.
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 allows for precise control of two-phase flow, improving machining efficiency by maintaining desired temperature and pressure conditions, reducing gas loss, and enhancing operational stability without the need for costly repressurization or complex equipment.
Implementation Method 1
a means of gas/liquid phase separation supplied with cryogenic fluid from said reservoir, carrying out the separation of an essentially liquid phase and an essentially gaseous phase of said cryogenic fluid
Implementation Method 2
measuring the gas flow rate from the gas outlet of the phase separation means
Data Source
Figure 1~2
AI summary
A method for supplying a user station with cryogenic fluid, such as liquid nitrogen, wherein the liquid/gas two-phase content arriving at the user station is a factor influencing the quality of the operation carried out by said station, from a cryogenic fluid storage tank, which contains, under a storage pressure higher than atmospheric pressure, the cryogenic fluid in the liquid phase at the bottom of the tank and in the gaseous phase at the top of the tank, the tank being suitable for supplying the station with liquid drawn from the bottom of the tank, as well as for being provided with fluid from the outside, characterised in that: i) a means (6) for gaseous/liquid phase separation, for example a degasser pot or a phase separator, is provided, and is supplied (20) with cryogenic fluid from the tank, and separates an essentially liquid phase and an essentially gaseous phase (40) of the cryogenic fluid, the essentially liquid phase (30) being directed to the user station; j) fluctuations in the liquid/gas two-phase content arriving at the user station over time, for example in the course of each operating phase of the user station, are measured (8): - by providing a measurement of the flow of gas from the gas outlet of the phase separation means and by measuring any deviations of said gas flow over time; or - by having the information provided by a flow sensor located at the gas outlet of the phase separation means, 0/1 binary-type information, enabling the detection of a flow exiting the separation means, and determining the opening time of the sensor over a given time range; k) one or more actions (2, 10...) are undertaken, depending on the outcome of the determinations made in j), to inform the user station and/or modify the operating conditions of said user station.