Helium purification method and apparatus

Claim 1

An apparatus in accordance with claim 1 wherein said first source and said first reservoir are the high-pressure and low-pressure fluid passages, respectively, of the main heat exchanger of a helium liquefier.

Claim 6

An apparatus for purifying gaseous helium, comprising in combination a. a source of pure, cold, high-pressure helium; b. a reservoir of pure, cold, low-pressure helium; c. a source of pure, essentially room-temperature, high-pressure helium; d. a reservoir of pure, essentially room-temperature, low-pressure helium; e. a source of high-pressure impure helium; f. a reservoir of low-pressure impure helium; g. a purifying heat exchanger having a first pure helium flow passage and a second helium flow passage, said passages being arranged to effect indirect heat exchange between the helium streams flowing therein; h. liquid impurity trap means within said purifying heat exchanger; i. a vapor pressure bulb positioned within the coldest section of said purifying heat exchanger; j. first and second pressure-actuated switch means in signal receiving relationship with said vapor pressure bulb; k. first fluid conduit means connecting said source of pure, cold, high-pressure helium with the cold end of said first flow passage in said purifying heat exchanger; l. second fluid conduit means connecting said source of pure, cold, high-pressure helium with the cold end of said second flow passage in said purifying heat exchanger; m. third fluid conduit means connecting said reservoir of pure, cold, low-pressure helium with the cold end of said first flow passage in said purifying heat exchanger; n. fourth fluid conduit means connecting the warm end of said first fluid flow passage in said purifying heat exchanger with said source of pure, essentially room-temperature, high-pressure helium; o. fifth fluid conduit means connecting the warm end of said first fluid flow passage in said purifying heat exchanger with said reservoir of pure, essentially room temperature, low-pressure helium; p. sixth fluid conduit means connecting the warm end of said second fluid flow passage in said purifying heat exchanger with said source of high-pressure impure helium; q. third pressure-actuated switch means associated with said sixth fluid conduit means; r. seventh fluid conduit means connecting the warm end of said second fluid flow passage with said reservoir of low-pressure impure helium; s. eighth fluid conduit means in fluid communication with said liquid impurity trap means; t. time delay switch means; u. purifying filter means associated with said first, second and third conduit means; v. valve means associated with each of said eight fluid conduit means and adapted to control the flow of fluids within said conduits and through said purifying heat exchanger, said valve means being actuated by said pressure switches thereby to permit

Claim 13

A method of purifying helium, comprising the steps of a. refrigerating a second periodically flowing stream of high-pressure impure helium, containing impurities to be removed, by indirect heat exchange with a countercurrently continuously flowing first stream of cold high-pressure pure helium withdrawn from a first source and directed to a reservoir of pure low-pressure helium thereby to produce a stream of purified cold, high-pressure helium for delivery to said first source, said heat exchange between said first and second streams being confined to a single purifying heat exchanger and the periodic flow of said second stream being regulated so that said second impure helium flows in heat exchange with said first stream during those periods when the temperature of said second stream is increasing within a preset temperature range and ceases to flow during those periods when the temperature of said second stream is decreasing within said preset temperature range, whereby said impurities are condensed out in said second stream and acCumulated; b. continuing the heat exchange between said first and second streams as in step (a) until the pressure drop experienced by said second stream increases to a preset pressure level by virtue of the condensation of said impurities within said second stream; c. cutting off the flow of said first and second streams while warming the residual helium in said second stream by indirect heat exchange with warm, pure high-pressure helium of a third stream flowing between a second source and a low-pressure, pure cold helium reservoir in a direction opposite to the direction of said first stream in step (a) thereby forcing said residual helium in said second stream to flow in a direction opposite to the direction of said second stream in step (a) to a low-pressure, impure helium reservoir and to vaporize or liquefy said impurities; d. discharging said impurities for a set period of time; ; e. cutting off the flow of said impurities; f. beginning the continuous flow of said first stream as in step (a); and g. then beginning the periodic flow of said second stream as in step (a) when the temperature reaches the lower level of said preset temperature range.