NMR Cold Gas Supply with Pre-Cooling to Cut Nitrogen Loss
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Solution Overview
Problem
Existing NMR LT MAS cooling devices consume excessive liquid nitrogen, leading to high operating costs and frequent tank refills due to high gas pressures and flow rates, which are not efficiently managed by current pre-cooling methods.
Innovation Solution
A device with additional pre-cooling exchangers that utilize boil-off gas and evacuated gases from the NMR probe to pre-cool gas streams before they enter the main exchangers, reducing the thermal load on the liquid nitrogen and minimizing its consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high gas pressures and flow rates are used to ensure stable rotor rotation and effective sample cooling, then the rotor rotation stability and cooling efficiency are improved, but the liquid nitrogen consumption increases significantly
Solution Approach 1:
The patent implements pre-cooling exchangers that cool the gas streams before they enter the main cooling system. This preliminary cooling action reduces the thermal load on the liquid nitrogen, allowing the system to maintain stable rotor rotation with lower liquid nitrogen consumption. The pre-cooling stage prepares the gas in advance, reducing the energy that would otherwise need to be removed by the expensive liquid nitrogen cooling system.
Solution Approach 2:
The cooling system is divided into multiple independent stages: pre-cooling exchangers for each gas stream (VT, Bearing, Drive) and the main cooling system with liquid nitrogen. This segmentation allows each stage to perform its specific cooling function efficiently, reducing the overall liquid nitrogen consumption while maintaining the required cooling performance for stable rotor operation.
2Temperature
If high gas pressures are used to maintain constant chamber pressure, then the cooling efficiency is improved, but the liquid nitrogen consumption increases proportionally
Solution Approach 1:
Pre-cooling exchangers are installed upstream of each chamber to reduce the temperature of incoming gas streams before they enter the liquid nitrogen cooling chambers. This preliminary cooling action reduces the temperature differential that the liquid nitrogen must manage, allowing effective cooling at lower pressures and thus reducing liquid nitrogen consumption while maintaining cooling efficiency.
3Reliability
If three separate cooling exchangers are used for VT, Bearing, and Drive gases, then each gas stream is cooled effectively, but the overall liquid nitrogen consumption increases
Solution Approach 1:
Each of the three separate gas streams (VT, Bearing, Drive) is equipped with its own pre-cooling exchanger upstream of the main cooling chamber. This preliminary cooling of each stream individually reduces the total thermal load on the liquid nitrogen system, maintaining effective cooling of all three streams while significantly reducing liquid nitrogen consumption compared to cooling all streams without pre-cooling.
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 significantly reduces liquid nitrogen consumption by up to 50%, allowing for continuous operation with fewer tank refills and maintaining stable rotor rotation and sample cooling, while ensuring dry gas delivery to the probe.
Implementation Method 1
at least one additional exchanger (8) that ensures a pre-cooling of the gas stream in question before it is channeled to the corresponding exchanger (6), with said additional exchanger (8) being supplied with gaseous vapor (5') that is produced by the boiling of the liquid gas (5) in the tank (4)
Implementation Method 2
gaseous vapor (5') that is produced by the boiling of the liquid gas (5) in the tank (4)
Implementation Method 3
additional exchangers (8', 8'') that ensure the pre-cooling of the cold gases intended to ensure respectively the lift and the rotation of the sample are supplied by the gases (9) that are evacuated or that escape at the probe (3)
Data Source
AI summary
A device for supplying cold gases to an NMR installation or analytical apparatus equipped with a measuring probe, with cold gases ensuring the cooling of the sample contained in the probe, but also its lift and rotation, the device including an insulated tank containing liquid gas at boiling point and in which are arranged exchangers through which gas streams to be cooled pass, these exchangers being connected to transfer lines channeling the cooled gases to the probe. The device also includes at least one additional exchanger that ensures a pre-cooling of the gas stream before it is channeled to the corresponding exchanger, with the or each additional exchanger coming in the form of a double-flow exchanger that is supplied either by the gaseous vapor produced by the boiling of the liquid gas in the tank or by the cold gas that is evacuated or that escapes at the probe.