Browse Prior Art Database

Publication Date: 2005-Apr-06
Document File: 9 page(s) / 58K

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The Prior Art Database


In one embodiment, a ramp lead helium gas recovery system (RGRS) is configured having easily connectible to an existing cool down recovery system or can be used stand-alone. In either case, the RGRS is connected to an existing helium gas processing system which includes a piping, a plurality of valves, collection bags, heat exchangers, compressors, purification filters, etc. A remote temperature monitoring unit is provided to ensure and determine that the ramp lead cooling gas is flowing properly and does not rely on visual monitoring.

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[0001]               This invention relates generally, to gas recovery systems, and more particularly to, a ramp lead helium gas recovery system for super conducting magnets in medical imaging especially, magnetic resonance imaging (MRI).


[0002]                Helium is very expensive.  Superconducting magnets for MRI contain large volumes of liquid helium for the purpose of reducing the temperature of the superconductor below the critical temperature.  During the energization of the magnet (ramping), some of the liquid helium is vaporized and escapes through cooling passages in the ramp leads.  This helium gas is lost to atmosphere.  The cost of the lost liquid is significant.  If the gas can be cost effectively recovered, it can be processed and sold, thereby reducing the net cost of ramping superconducting magnets.  

[0003]               In order to be effective, the recovery system must operate while not impeding the ramp process.  This process requires that the leads be cooled effectively and continuously.  The current method for determining that this cooling process is proceeding is by visual observation of the gas plume escaping the leads into the atmosphere.  The recovery system must therefore provide a means to monitor that the cooling process is proceeding (either visually or by some other means).  If the magnet is energized with insufficient ramp lead cooling, the result could be damage to the leads and or quenching of the magnet., resulting in significant expense to repair.

[0004]               It is also necessary that the escaping helium gas be collected in a manner that will prevent contamination with surrounding air.  This is essential so that when the gas is deposited into a processing system, the system will not be overwhelmed with impurities such as water, air and nitrogen.  These impurities will saturate the processing system filters resulting in excessive maintenance costs that will negate the savings from recovering the helium.  Helium recovery systems for other applications, such as during magnet cool down, are, therefore, closed systems.  The closed nature of these type systems precludes visual  observation of the flowing gas in order to ensure the lead cooling process is proceeding. In order to use clear materials (e.g. Glass, plastic, etc.) to enclose the ramp lead recovery system, the problem of condensation on the material, thereby eliminating visual observation would have to be solved.  The solution would undoubtedly involved heaters, and would more than likely be overly complex and prohibitively expensive.

[0005]               In order to provide a closed system, a physical connection between the electrically conductive ramp lead and the system must be made safely.  This will require non-conductive parts that are compatible with cryogenic temperature.  Gaseous helium may be as cold as 4.2 K during operation of the system.  An interface tool to accomplish this task must be...