US2947151A

US2947151A - Method and apparatus for operating regenerators

Info

Publication number: US2947151A
Application number: US563340A
Authority: US
Inventors: Clarence J Schilling
Original assignee: Air Products Inc
Current assignee: Air Products Inc
Priority date: 1956-02-03
Filing date: 1956-02-03
Publication date: 1960-08-02
Anticipated expiration: 1977-08-02

Description

Aug. 2, 1960 i c. J. scHlLLxNG METHOD AND APPARATUS PoR OPERATING REGENERATORS Filed Feb. 3. 1956 2 Sheets-Shet 1 mkv INVETOR CLARENCE J. SGH/LING Aug. 2, 1960 c. J. scHlLLlNG METHOD AND APPARATUS FOR OPERATING REGENERATORS Filed Feb. s, 195e 2 sheets-sheet?.-

- INVENTOR CLARENCE J. SGH/LING that the drawings are designed for purposes of illustration only and not as a denition of the limits of the invention, reference for the latter purpose being had to the appended claims. j V

In the drawings, in which similar reference characters denote similar elements throughout thev several views: Fig. 1 isa diagrammatic presentation of a low temperature fractionating cycle embodying the principles of the present invention; Y

Fig. Z is an elevational view, partially in section, of a ow control device provided by the present invention, the control device being shown in open position and in operative relationship with a cold regenerator;

Fig. 3 is a view in vertical section of the control device of Fig. 2, the control device being shown in closed position; Fig. 4 is a view in section taken along the line 4-4 of Fig. 2, and

Fig. 5 is an elevational view, in section, of a ow control device constructed in accordance with another embodiment of the present invention. The present invention provides a novel method of and apparatus for controlling the ow of relatively high pressure residual gas upwardly from regenerators in such a manner as to prevent the production of nes from the particles or pellets comprising the packing material of the regenerators. According to the present invention the velocity of the fluid stream owing upwardly through a regenerator is maintained below a critical velocity, irrespective o'f the pressure involved, such that the resulting upward force on the packing material is at all times less than the density of the packing material. Thus a quiescent bed of packingv material is obtained and the use of spring loaded screens for preventing movement of the packing material is rendered unnecessary.

With reference more particularly to Fig. 1 of the drawings, there is disclosed an air fractionating cycle which incorporates the principles of the present invention. Al-

though the present invention is disclosed and described in the environment of separating air into low boiling point nitrogen and oxygen components, it is to be expressly understood that the principles of the present invention are applicable to the separation of other gaseous mixtures not limited to binary mixtures. As shown, the fractionating cycle includes a two stage column 10 having -a high pressure section 11, a low pressure 12 and a conventional refluxing condenser 13. The cycle also includes Atwo sets of

cold regenerators

14 and 15, each comprising one pair of

cold regenerators

15, 16 and 17, 18, respectively. It is to be expressly understood however, that additional sets may be provided and that each set may include more than two regenerators. A stream of gaseous mixture under relatively high pressure, such as air at 80 pounds gage, for example, enters the cycle .through a conduit 20 serially connected by a proportioning valve 21 to a conduit 22.

Branch conduits

23 and 24 are connected to the conduit 20 and to oppositely related individual ports 25 and 26 of a pair of twopositioned switching valves 27 and 28, respectively, the other

individual ports

29 and 30 being joined by a conduit 31 communicating with the atmosphere through a conduit 32. The switching valves include common ports 33 and ,34 connected to

conduits

35 and 36 communicating with the upper ends of the cold regenerators 16 and 17, respectively. Conduits 37V and 38 respectively extending `from the bottom ends of the regenerators 16 and -17 are connected to common ports of

switching valves

39 and ,40. One pair of oppositely disposed individual ports of

fthe switching valves

39 and 40 are connected to a common conduit 41 by way of

conduits

42 and 43, while Ythe other pair of individual ports are joined by acommon conduit 44. The upper endsrof vthe regeneratorslS and -,19 of the set 15 are connected tothe conduit 22V and to a conduit 45 leading to the atmosphere'in a similar manner rbyfmeans of'switching valves 46 and 47, one pair of opposed individual ports being connected to the conduit 22 by way of

conduits

48 and 49 and the other pair of individual ports being joined together by a conduit 50 communicating with the conduit 45. The common ports of the switching valves 46 and 47 communicate through

conduits

51 and 52 to the upper ends of the

regenerators

18 and 19, respectively. Also, the lower ends of the

regenerators

18 and 19 are connected through

conduits

53 and 54 to the common ports of a pair of switching valves 55 and 56, the latter switching valves having one pair of opposed individual ports connected to the conduit 41 by way of

conduits

57 and 58, and another pair of individual ports connected together by a common conduit 59.

With the switching valves in the positions shown in the drawing, a major component stream of the incoming air flows downwardly through the regenerator 16 while the remaining minor component stream ows downwardly through the regenerator 18, the proportions of the total air stream comprising component streams being determined by the valve 21. The component air streams are cooled upon owing downwardly in the

regenerators

16 and 18 which have been previously cooled in a manner described below, and leave the lower ends of the regenerators by way of

conduits

37 and 53 at a relatively low temperature, such as approximately the dew point temperature corresponding to the existing pressure. The cold streams pass through

conduits

42 and 57 and are merged in the conduit 41, and the merged streams are conducted to an expansion valve 61 and then introduced by way of a conduit 62 into the high pressure section 11 of the fractionating column 10. The high pressure section 11 includes a plurality of fractonating trays 63 provided with liquid vapor contacting devices 64 of the bubble cap type, for example, and the gaseous mixture undergoes preliminary fractionation therein producing liquid crude oxygen fraction collecting in a pool 65 in the base of the high pressure section and gaseous nitrogen fraction which Hows upwardly into the reuxing condenser 13 where it is condensed by heat exchange with liquid oxygen product collecting in a pool 66 in the base of the low pressure section 12. The liqueed high pressure nitrogen fraction ows downwardly from the refluxing condenser with a portion of the liquid providing reux for the high pressure section 11, and another portion collecting in a pool 67 formed by a trough 68. A stream of liquefied nitrogen fraction is withdrawn from the pool 67 through a conduit 69, passed through an expansion Vvalve 70 and introduced into the upper end of the low pressure section as reux liquid. The feed for the low pressure section comprises a stream of liquid crude oxygen fraction withdrawn from the pool 65 by way of a conduit 71, expanded in; an expansion valve 72 and introduced into lthe low pressure section at a mid point 73.

The low pressure section 12 includes a plurality of fractionating trays 75 each provided with liquid vapor 'contact devices 76, and the fractionating process is completed therein producing a substantially pure liquid oxygen product collecting in the pool 66, and a gaseous nitrogen product which flows upwardly in the dome of the low pressure section and leaves the section through 'a conduit 77. The conduit 77 is joined to the common conduit 44 connected between the switching valves '39 and 40. With the switching valves in the position shown, the stream of cold nitrogen` product gas passes through the 'cold regenerator 17 and is exhausted from the cycle at substantially atmospheric temperature and pressure lthrough the conduit 32. The oxygen product maybe withdrawn from the column 10 in liquid phase, or in gaseous phase through a conduit 78 communicating within the low pressure section above the poolY of liquid oxygen product 66. The conduitl 7'8 is joined to the common conduit 59 connected to the switching valves 55 and 56, and with the switchingyalves in.v the position shown in the drawing, the 'streamof gaseous oxygen 2gsm; rs1

product flows upwardly t-lrroughthe regen'erator 19 and leaves theA cycle through the conduit 45 aty substantially atmospheric temperature and pressure. Y

The

regenerators

116, 17, 18 and 19 are of similar conventional construction,` and, although the regenerators of the

sets

14 and 15 are of different capacity, it will only be necessary to describe in detail the construction of one Iegenerator, 'such as the regenerator 16. As shown in Fig. 2'the regenerator 16 comprises a hollow cylindrical casing 80 closed at -its upper and lower ends by dished

end plates

81 and 82, respectively, defining a chamber 83 substantially completely housing a bed 84 of low temperature heat regenerator packing material in the form of a plurality of relatively small particles or pellets 85 of heat storing material such as stone, quartz or metal. The lower end 82 of the regenerator is provided with a centrally disposed opening 86 communicating with the conduit 3'7,pand a screen 87 is positioned within the chamber 83 overlying the opening `86 to prevent the pellets from flowing out of the chamber 83 into the conduit 37. In this type of regenerator the flow of cold product streams upwardly through the packing material cools the particles of heat Vstoring material, and when the switching valves are operated to pass the incoming air stream downwardly through the packing material the stored cold is transferred to and cools the air stream.

Asmentioned above, the incoming air stream in the conduit 20 is under relatively high pressure, such as 8O pounds gage,A while the cold product nitrogen andoxygen streams enter the lower ends of the regenerators at a relatively. low pressure, 4 pounds gage for example.

Thus, when the switching valves are moved from one phase of operation to the other, the regenerators previ- `ously passing a stream on incoming air will contain a residual volume ofrair under the relatively high pressure which must be exhausted from the upper ends of the regenerators before respective cold product streams may ilow therethrough. According to the present invention the velocity of the residual air flowing outwardly from the. top of the regenerators is controlled to allow the residual air to exhaust as quickly as possible from the regenerators without producing disturbing effects upon the. bed 84 of packing material. This is accomplished by means of a novel liow control valve 90 positioned at the upper ends of the regenerators in communication between -the interior of the regenerators and their

respective feed conduits

35, 36, 51 Iand 52. The ilow control valves 90 function to maintain the rateof flow of fluid streams upwardly through the regenerators at all times slightly below a critical value above which the resulting upward force on the packing material 34 would exceed the density of the packing material, irrespective of the pressure drop of the residual air during the exhausting process. The flow control valves also function to Aallow normal rates of flow of the cold product streams up- Vwardly through the regenerators and the streams of gaseous mixture downwardly through the regenerators.

As shown moreparticularly in Figs. 2, 3 and 4 of the drawings, each of flow control valve 90 comprises a vertically disposed hollow cylindrical member 91 having its lower end 92 extending through an opening in the `top end plate `81 of the regenerator in communication with the regenerator chamber 83 and secured thereto by any suitable means, such as by welding, for example, and anupper end 93 provided with an annular flange 94 for forming a connection with one of the

feed conduits

35, 36, 51 or 52. The flow control valve further ind wardlyfrom Yits other end, the area of theopenings gradually decreasing in a `direction towardV the plate 99 and terminating in a plane spacedY upwardly from the lower end of the cylindrical member 100 to provide a continuous portion V102 at its lower end adjacent theplate 99. The piston 97' is mounted for axial movement in a closed cylinder 103 rigidly supported in concentric relation within the casing 91 by means of radial vanes 10d, the cylinder and the piston defining a` chamber 105. An annular ilange member'106 is positioned within the casing below the cylinder 103, and is provided with a centrally disposed opening 10.7 for receiving the hollow cylindrical member 100. The movable member is supported in Vits lowermost position in theV casing 91, as shown in Fig. 2, by means of a plurality of angularly spaced stop members 108'1ocated in a horizontal plane below the flange member 106 and projecting inwardly from the casing to beyond the outer periphery of the plate member 99. The plate member 99 extends outwardly beyond the walls of the hollow cylindrical member and presents an :annular flange 109 for contacting the lower annular surface 110 of the flange member 106 to limit upward movement of the movable member 95 to the position shown in Fig. 3. The longitudinal space between the planes of the annular flange member 106 and the stop members 108 and the length of the hollow cylindr-ical member 100 are proportioned to preferably maintain contiguous relationship between the outer surface of the hollow lcylindrical member and the opening 107 throughout the range of longitudinal movement of the movable member 9S. Also, the strokeof the piston 97 in the cylinder 103 is Vat least equal to the range of longitudinal movement of the member-95 so that the opening 107 and the cylinder 103 function as guides for the .member 95. VA helical spring 111 is positioned in the chamber between the upper end surface of the piston 97 and the end wall of the cylinder 103 to normally urge the movable member 95 downwardly to the position shownin Fig. 2. A downward force is also applied to theV member 95 by the pressure of the Vfluid in the chamber 105 acting on the piston 97, the fluid being supplied to the chamber through a longitudinal passageway 112 Yextending throughout the valve stem from the lower side hollow cylindrical member permits Ylimited uid ilow across the lilange member 106 when 'the member 95 is in the latter position.

The effective area of the piston ,97 and the size of fthe spring 112 are proportioned with respect to the eifective area of the plate member 99 so that the member 95 moves to its uppermost, or closed position, as shown in Fig. 3,` whenever the pressure of the fluid on the regenerator side, or Vat the inlet of the casing 91 exceeds a predetermined value. In this position, the Huid flows from the inlet to the outlet only through the orifices 113 and any desired predetermined maximum rate of flow.

may be established by calibration of these orifices.` YWhen the pressure of the fluid at the inlet drops .fro a value -such that the downward force presented by the spring 112 and the pressure ofthe liuid acting on the piston 97 exceeds theupward force presented bythe pressure ofthe fluid acting onI the plate member 9.9 the member 95 begins to move downwardly from it/sposition shown in Fig.` 3.

` Upon suti'eient downward movement of the member `95,

thelower ends of the openings 101 extend downwardly beyond the lower'surfac'e of. the annular flange member 106 to allow uid How around the periphery of the plate member 99 and through the opening 107. Due to the tapered shape of the openings '1, the eiective sizeof the opening 107 gradually increases as the member 9S moves further downwardly, and maximum opening is attained when the member 95 moves to its lowermost or open position, shown in Fig. 2. VIn the latter position minimum restriction is olered to fluid ow through the casing 91 in either direction.

The -ow control valves 90 are operable to automatically limit the rate of liuid flow therethrough to below a predetermined value whenever the regenerator inlet of the casing 91 is subject to a relatively high pressure, such as the relatively high pressure residual iluid existing in the regenerator chamber 83 upon the regenerator being switched when passing a stream of relatively high pressure gaseous mixture. 'Ihe orifices 113 may be calibrated to maintain the rate of uid flow through the valve below a predetermined critical value for the maximum inlet pressure as determined by the pressure of the fluid in the chamber 83. Also, the valve is operable to exhaust the relatively high pressure residual fluid in the chamber 83 during the shortest period of time while maintaining the rate of fluid'ow through the casing 91 below the predetermined critical value. This is accomplished by the feature of increasing the effective size of the opening 107 responsively to decreases in inlet pressure.

Operation of the ow control valves 90 will be more fully understood by consideration of their performance in the fractionating cycle shown in Fig. 1. Upon the

switching devices

27, 28, 37, 38, 46, 47, 55 and 56 being moved to the positions shown, streams of incoming gaseous mixture under relatively high pressure, such as compressed air, llow downwardly through the

regenerators

16 and 18, while cold product streams under relatively low pressure, such as nitrogen and oxygen product streams, ow upwardly through the regenerators 17 and 19, respectively. During this phase of operation the flow control valves 90 associated with each regenerator are in their open positions, shown in Fig. 2, in which the -valves present a minimum restriction to uid ow therethrough in either direction. The nitrogen and oxygen product streams are introduced into the lower ends of the regenerators 17 and 19 at a pressure substantially corresponding to the pressure of the low pressure section of the fractionating column, which may be in the order of 4 pounds gage, for example. Since the product streams are exhausted from the upper ends of the regenerators at atmospheric pressure, a pressure drop of 3 pounds per square inch will exist across the bed 84 of packing material. In an installation in which the regenerators are packed to a height of 2.1 feet withheat adsorbing material having a density of 1-.10 pounds per cubic foot, such as quartzite, a lifting force of approximately 20.6 pounds per cubic foot will be exerted on the packing material by the pressure drop resulting from the ilow of the cold product streams upwardly through the regenerators. This lifting force is about one fth the density of the packing material and is insuicient to disturb the bed.

When the switching valves are simultaneously moved to their other phasev of operation, the cold product streams are conducted upwardly through the

regenerators

16 and 18, while the streams of gaseous mixture are conducted downwardly through the regenerators 17 andv 19 previously cooled by the cold product streams. During this phase of operation the flow control valves associated with the regenerators 17 and 19 remain in the fopen position, while the ow control valves connected to the

regenerators

16 and 18 move to the closed posi-- tion, as shown in Fig. 3, responsively to the residual volume of relatively vhigh pressure. gaseous mixture present in the latter regenerators at the time the switching valves are operated. In the fractionation of air, as mentioned above, the incoming airstream may be underar.

rposition shown in Fig. 3 and maintains the member 95 inclosed position until the pressure of the air in the regenerator chamber 83 drops to below a critlcal value. When the tlow control valves associated with the

regenerators

16 and 18 are closed, the residual air ows 'om the respective regenerators through the restricted orifices 1113. These orifices are calibrated to establish a maxi- 4mum permissible rate of flow, at the maximum pressure of the residual air, such that the resulting lifting force on the bed of packing material is less than the density of the packing material. In the case of quartzite packing material of a density of 110 pounds per cubic foot packed to a height of 2l feet inthe regenerators, the orifices -113 are calibrated to provide a maximum permissible rate of ow, when subject to a pressure head of pounds gage, to produce a pressure drop across the packing material less than the density of the packing material, or less than live times the pressure drop developed during upward flow of cold product streams through the regenerators. Since the pressure drop varies as the square of the mass liow and inversely as the density, the required orifice size may be easily calculated. In the present example, the orifices 113 are designed to provide a maximum permissible rate of flow less than 5.45 times the rate of flow of the cold product streams.

As the residual air exhausts from the regenerator chamber, the pressure of the residual air remaining in the regenerator chamber decreasesv with a proportional decrease in the ow through the orifices 113. Inasmuch Vas it is advantageous to exhaust the residual air from the .regenerators within the shortest period of time, the ow control valves are characterized in such a manner as to maintain, yupon a gradualdecrease of the pressure of the Vresidual air in the regenerator chambers,l the rate of flow Vthe open position responsively to a progressive pressure drop in the regenerator chamber while maintaining the rate of flowbelow theV maximum .permissible rate.

@When the member moves downwardly to a position Vwherein the closed ends ofthe openings 111 extend Adownwardly beyond the lower surface of the annular flange memberA 106, the effective. size -of the orifice in the annular flange member 106 is increased and a predetermined rate Of-ow-may be maintained with a rer.duced pressure head.V The rate of downward movement of the member 95, and the shape of the openings 111, are proportioned in accordance with the pressure gradient within the regenerator chamber, to maintain the rate of flow from the regenerator less than the maximum permissible rate of ow discussed above.

Y The liow control valves may be designed to operate Vresponsively to any degree of pressure drop to increase the effective size of the opening 107 presented by. the annular ilange member 106. The operating requirements ofthe cycle and thev sensitivity of the flow control valves are primary factors in determining the degree of pressure reduction required for this operation. If desired, the variable orifice may be caused-to open responsively to a -pressure reduction of the order of one pound or less, ,however such an operation would require a ow control valve of extremely high sensitivity vand the resulting relativelyminute reduction of the exhaust periodmay not antritt- Y 9 ordinarily justify the expense involved; In general,.a ilow controln valve operable to increase` the size of'tlieoriiice responsively to a` regenerator chamber pressure intermediate the maximum residual air" pressure and the Vcold product pressure,-or less,.may be manufactured at relatively low cost tompossess the necessary sensitivity and also provide for the exhaust of the residual-airwithin a period of time which does not adversely Veiect column operation. For example, ina fractionating cycle in which theV air stream is introducedat 80 pounds gage and the cold product streams enterthe regenerators at `4 pounds gage, the elements ofthe flow control valves maybe proportioned to initiate downward movement of Ythe member 95 upon the regenerator chamber pressure dropping to 40 pounds gage, andthereafter being operable to progressively `increase the sizeof the orice responsively to further `deduction of the pressure head to exhaust the residual air and establish a-Yregenerator pressure of 4 pounds gage within a period-ofY lessfthanA five seconds. This short exhausting period approaches the lower range of interrupted nitrogen ilow present` during operation of conventional fractionating cycles employing switching tubular heat-exchangers or switching regenerators. Consequently,tthe provision of the iiow control-valves according to the present invention does not-increase the pressure in the low pressurel sectionlofV thel columnror reduce the l.rate'of evolution as compared toconventionalcyoles, but

inY some cases actually decreases the exhaust period and minimizes their eiect.

Another form of iiow control valve provided by the present invention is illustrated in Fig.- 5 of the drawings. As shown, the valve includes a hollow cylindrical casing 125 havingv its -lower end 126 secured to the upperl end plate S1 of a regenerator, such as the regenerator 16,-in communication with the regenerator chamber; 83,` and its upperV endA 127 provided withanannular flange 128. A hollow cylindrical member 2129,'V havingV a closed upper end 13d,` is rigidly supported concentrically within the case 125 by means' of a pluralitypofradial vanes 131, and an elongated valve stem- 132 isv slidably mounted longitudinallyof the casing in acentrally disposed opening 133formed in the end plate 130.V A- hollow valve member 131i including cylindrical sidewalls 135 and upper, and lower end plates 1361 and 137 respectively,

Yoverlies the lower end ofthe -valve stem 132, and `is rigidly securedthereto in concentric relation. The cylindrical sidewalls' 135 are shaped so thatthe upper endof the valve member '13d-extends into the hollow cylindrical member 129 in sliding contact with its internalT surface upon longitudinal movement of the valve stem 132.` The upper end of the valve member 134 and the cylindrical member 129 function asa piston and cylinder assembly and together deiine Va chamberV 138. The lower end of the valve member 134 extends through a circular opening 139 formed by an annular flange 140 secured tothe casingt1=25 4below the cylindrical member 129. The

end plate

13,7 of the valve member 13'4 extends outwardly beyond; the cylindrical side walls 135' and is positioned below the annular ilanger140'to contact the lower surface of the latter Vflange and limit upward movement of the `valve stem 132. The valve stem 132 extends upwardly beyond the closed end 130of the cylindrical member 129 and is joined to Va valve operating member 141 comprising a transversely disposed concentrically positioned cir-k j inside surface ofthe casing.V The plate includes a pluralunderstood that various changes and substitutions may be 1 ity of downwardly depending stop members 143 which function to limit downward movement of the valve operative member and space the plate 1l41rfrom the upper 4surface of the closed end 130 of the cylindrical member 129; Ihe valve 'stem 132 is provided with a longitudinal passageway 144 extendingv from its lower end 1'45 upwardly beyond the end plate 136 of the valve member where the passagewayv communicates with" thek chamber t'through a portv 146. The passageway 144equalizes the pressures acting on the end-plates 136 and'137,rand the end plates are proportioned to present equal eiective areas so that the valve member moves independently of the inlet pressure. The end plate y137 is provided with a plurality of restricted orices 147, and the side walls are provided with angular-ly spaced longitudinally extending openings 148, of varyingA area, to control the ow of fluid across the annular flange 140.

lnoperation of the flow control valve shown in Fig. 5, when thev inlet is subject to. a relatively high pressure, such asfhigh pressure residual air present inthe regen'- erator chamber 83 at the time the regenerator is switched to pass a stream of cold` product upwardly therethrough, 'the high rate of iiow through the fixed annular orifice 142 produces a pressure drop across the valve operating member 141 causing the valve operating member and the valve member 134 to move upwardly to its maximum or closed position shown in the drawing. position iiuid iiows only through the restricted orifices 147 and these orifices may be calibrated to provide a predetermined maximum permissible rate of `flow. As the inlet pressure decreases, the pressure drop acrossv the valve operating member 141 decreases therewith, and a condition is eventually attained in which the upward force on the valve operating member is less than the downward force determined by the mass of the valve member 13d and its connected moving elements. When the latter torce relationship exists, the valve member 134 moves downwardly relatively to the annular flange 14! to position the openings 14S below the lower surface of the annular ange and thus increase the size of the opening across the annular flange. Sincev the valve member moves independently of the pressure of the iluid, the valve member is automatically positioned relative to the annular ange to maintain a constant rate of fluidow through the'casing 125 independently of pressure variations. rthis form of flow control valve has particular utility in connection with regenerators, although it may be employed in other environments, since substantially the total volume of residual gas may be exhausted from the regenerator chamber at a substantially constant rate of flow no greater than the maximum rateof flow established by the fixed orifices 147.

There Vis thus provided by the present invention a novel cycle for the separation of gaseous mixtures by liquefaction and fractionation including cold regenerators containing beds of packing material made up of small heat absorbing particles, in which the rate of ilow of high pressure residual gaseous mixture from the regeneratorstis controlled in such a manner as to prevent disturbance of the bed and resulting production of fines due to attrition or crushing of the heat absorbing particles, without increasing substantially the time required to exhaust the residual gaseous mixture. The present invention also provides two forms of liow Ycontrol valves which may be utilized with regenerator to achieve the foregoing operation. The flow control valves have utility in other environments requiringV a controlled rate of fluid flow, and one of the how control valves is capable of maintaining substantially constant rate of flow independently of pressure.

Although several embodiments of the invention have been disclosed and described above, it is to be expressly made therein without departure from the spirit of the invention as well understood by those skilled in the art.

Reference therefore will be had to the appended claims for a definition of thelimits of the invention.

- What is claimed is: Y

` l. Method of operating a regenerator including a bed of-particles of regenerative material and adapted to be switched between liirst and second operating phases, in which relatively high pressure iiuid flows through the f11 regenerator during the-rst operating phase and relatively low pressure tluid ilows through the regenerator during the'second operating phase, the method of controlling the flow of relatively high pressure fluid in the bed upon switching the regenerator from one operating phase to the other operating phase which comprises the steps of restricting the flow of relatively high-pressure Iuid in the bed upon the regenerator being switched from one operating phase to the other operating phase to maintain the pressure drop across the bed less than a predetermined value to produce an upward force on the bed less than the density ofthe regenerative material, and establishing normal unrestricted flow of uid in the bed upon the pressure of uid in the bed decreasing to a predetermined low value, the predetermined low value being such that normal unrestricted ow of fluid in the bed at a pressure corresponding to the predetermined low kvalue establishes a pressure drop across the bed which produces an upward force on the bed less than the density of the regenerative material.

2. Method of operating a regenerator including a bed of particles of regenerative material and adapted to be switched between iirst and second operating phases, in which relatively high pressure uid flows through the regenerator during the first operating phase and relatively low pressure fluid ows through the regenerator during the second operating phase, the method of con` trolling the ow of relatively high pressure fluid in the bed upon switching the regenerator from one operating phase to the other operating phase which comprises the steps of restricting the ow of relatively high pressure fluid in the bed upon the regenerator being switched from one operating phase to the other operating phase to maintain the pressure drop across the bed less than a predetermined value to produce an upward force on the bed less than the density of the regenerative material,

decreasing the restriction to the flow of relatively high pressure fluid in the bed as the pressure drop across the bed decreases while maintaining the flow of fluid in the bed such that the resulting pressure drop across the bed is less than said predetermined value, and establishing normal unrestricted flow of fluid in the bed upon the pressure of fluid in the bed decreasing to a predetermined low value, the predetermined low value being such that normal unrestricted flow of fluid in the bed at a pressure corresponding to the predetermined low value establishes a pressure drop across the bed Which produces an upward force on the bed less than the density of the regenerative material.

3. Method of operating a regenerator including a bed lof particles of regenerative material and adapted to be switched between rst and second oper-atingphases, in which relatively high pressure fluid ows downwardly through the regenerator during the iirst operating phase and relatively low pressure luid ows upwardly through the regenerator during the second operating phase, the method of controlling the iiow `from the regenerator ot relatively high pressure fluid remaining in the regenerator upon the regenerator being switched from the rst operating phase to the second operating phase to prevent movement of particles forming the bed and the resulting production of fines, the method comprising the steps of restricting the flow of relatively high pressure tluid from the regenerator upon the the regenerator being switched from the tirst operating phase to the second operating phase to maintain the pressure drop across the bed less than a predetermined value to produce an upward force on the bed less than the density of the regenerative material, and establishing normal unrestricted flow of uid from the regenerator .upon the pressure of fluid in the regenerator decreasing toV a .predetermined low value, the, predetermined low value being'such that normal unrestricted ow of fluid in the bed at a pressure corresponding to the predeterminedlow value establishes a pressure drop across the bed which produces an up- 12 ward force on the bed less than the density of the regenerative material.

4. Method of operating a regenerator including a bed of particles of regenerative material and adapted to be switched between tirst and second operating phases, in which relatively high pressure uid ows downwardly through the regenerator during the lirst operating phase and relatively low pressure diuid ows upwardly through the regenerator during the second operating phase, the method of controlling flow from the regenerator of relatively high pressure uid remaining in the regenerator upon the regenerator being switched from the first operating phase to the second operating phase to prevent movement of particles forming Ilthe bed and the resulting production of fines, the method comprising the steps Vof restricting the ow of relatively high pressure uid from the regenerator upon the regenerator being switched from the first operating phase to the second operating phase to maintain the pressure drop across the bed less than a predetermined value to produce an upward force on the bed less than the density of the regenerative material, decreasing the restriction to the flow of relatively high pressure fluid from the regenerator as the pressure drop across the bed decreases while maintaining Vthe ow of fluid from .the regenerator such that the re- -tionating operation employing a switching regenerator Yincluding a bed of particles of regenerative material and adapted to be switched betweenl first and second operjating phases, in which relatively high pressure gaseous mixture to be fractionated ows through the regenerator during the rst operating phase and relatively low pressure cold product from the fractionating operation ows through the regenerator during the second operating phase, the method of controlling the ow of relatively high pressure gaseous mixture in the bed upon switching the regenerator lfrom one operating phase to the other operating phase to prevent movement of particles forming the bed and the resulting production of fines, the method comprising the steps of restricting the flow of relatively high pressure gaseous mixture in the bed upon the regenerator being switched yfrom one operating phase to the other operating phase to maintain the pressure drop across the lbed less than a predetermined value to produce an upward force on the .bed less than the density of the regenerative material, and establishing norm-al unrestricted iiow of gaseous mixture in the bed upon the pressure of gaseous mixture in the bed decreasing to a predetermined low value, the predetermined low value being such that normal unrestricted flow of gaseous mixture in the bed at a pressure corresponding to the predetermined lowv value establishes a pressure drop across the bed which produces an upward -force on 6. In the separation of gaseous mixtures by a frac- -including abcd of particles of regenerative material and adapted to be switched between iirst and second operating phases, in which relatively high pressure gaseous mixture to be fractionated Hows downwardly through the regenerator during the first operating phase and relatively low pressure cold product from the iractionating operation iiowsupward-ly through the regenerator during the second operating phase, the method of controlling the flowof relativelyr high pressure gaseous mixture in the Y 13 bed ,uponv switching the' regenerator from one operating phase to the other operating .phase to prevent movement of partieles forming the bed' and the resulting production of lines, the method comprising the steps of. restricting the flow of relatively `high pressure gaseous ,mixturel in the bed upon `the regenerator being switched`l from one operating phase to the other operating phase to maintain the pressure drop across the bed less than a predetermined value to produce an upward force on the bed less than the density of the regenerative material, decreasing the restriction to the flow of relatively high pressure ygaseous mixture in the' bed as .the pressure drop across the bed decreases while maintaining .the flow of gaseous mixture in the bed suc-h that the resulting pressure drop is less than saidy predetermined value, and establishing norrnai unrestricted ilow of gaseous mixture in the bed upon the pressure of fluid in the bed decreasing to a predetermined low value, Vthe predetermined low value being such that normal unrestricted ow of gaseous mixture in the bed at apressure corresponding to the predetermined low value establishes a pressure drop across the bed which produces an upward force on the bed less than the density of the regenerative material.

Y 7. In the separation of gaseous mixtures by a` fractionatiiig operation employing la switching regenerator including a bed of particles of regenerative material and adapted to be switched `between irst and secondoperating phases, iii which relatively high pressure gaseous mixture to be fractionated hows downwardly through the regenerator during the iirst operating phase and relatively low pressure cold product `from the fractionating operation flows upwardly through the regfnerator during the second operating phasefthe method of Vcontrollingfilow from the regenerator Vofgaseous mixture remaining` in the regenerator upon the regenerator being switched Afrom the first operating phase to the second operating phase to prevent movement ofV particles forming the bed and the resulting production of fines, the method comprising the steps of restricting ow of Agaseous mixture from the regenerator upon the regenerator being switched from the iirst operating phase tothe `second operating phase to maintain `theiiow fof nresidual gaseous mixture from the regenerator belowa maximum ilow such that the resulting pressure drop across` the bed of regenerative i material produces an upward force on the hed which is less than the density of the regenerative material, and establishing normal unrestrictedilow oi gaseous mixture in thekregenerator upon the gaseous mixture inthe regenerator dropping toa predeterminedl'ow pressure, Vthe y' predetermined low value being such 'that norma-'1 unrestricted ow of gaseous mixture from the'iregeneratorfat the predetermined low pressure (establishes ia pressure drop across the bed `of regenerativev material *producing an upward force on the bed less than the density of the regenerative material. I M

8. In the separation of gaseous mixtures byV a fractionating operation employing a switching regenerator including a bed of particles of regeneratiye material and adapted to be switched between Vfirst andse'cond operating phases, in which relativelyhigh pressure gaseous mixture to be fractionated yflows downwardly through the regenerator during the hrst operating phase audr'elatively low pressure cold product from the fractionating operation flows upwardly through theregenerator during the second operating phase, the method of' controlling t-he liow from the regenerator of gaseous mixture remaining in the regenerator upon the regenerator being switched from the iirst operating phase to theA second operating phase to prevent movement of `particles forming the bed and the resultingV production of fines, the method comprising the steps of restrictingthe Vflow of gaseous mixture from' the regenerator upon theV regenerator beingswitched from the first operating phase to the vsecond operating phase to establish Va maximum flow of Y V14. t x gaseous mixture from the regenerator` such that the re'- sultingfpres'sure'drop across the bedv of regenerative material produces an upward force on the bedV which is less than theV density of the regenerative material, decreasing the restriction to the flow of gaseous mixture frorn the -regenerator as the pressure of the gaseous mixturejin the regenerator decreases while maintaining' the flow of gaseous mixture from the regenerator below the maximum ow, and establishing normalV unrestricted ilow of gaseous mixture from the regenerator upon the gaseous mixture in the regenerator dropping to a predetermined low pressure, the predetermined low pressure being such that normal unrestrictedilow of gaseous-mixture'from the regenerator at the predetermined low pressurev establishes a pressure drop across the bed ofV regenerative material producing -anupward force on the bed less than the density of the regenerative material.

` 9. InV the separation'of gaseous mixtures by a fractionating-operation employingv a switchingV regenerator including a bed of particles of regenerative material and adapted to be switched between first and second operating phases, in which relatively high pressure gaseous mixture to be fractionated ows downwardly through the regenerator' during the first operating phase and relatively low pressure" cold product from the fractionating operation flows upwardly through the regenerator during the second operating phase, the method of controlling the ilow from the regenerator of gaseous mixture remaining in the regenerator' upon the regenera'tor beingiswitched from' the Viirst loperating phase `1to the second operating phase to prevent movement of particles forming the bed and the resulting production of lines, the method' cornprising the'rsteps of restricting the ow of gaseous mixture from the regeneiator upon the regenera'tor being switched :from the first operating phase to the second operating phase to establish a maximum ow of residual gaseous mixture from the regenerator such that the resulting pressure'drop across the bed of regenerative material Vproduces an upward force on the bed which is less than the density ofthe regenerative material, progressively decreasing' the restriction to the flow of gaseous mixture frein the regenerator as the pressure of the gaseous mixture'in the regenerator decreases while at all times maintaining 'the now of gaseous mixture from the regenerator below 'the maximum flow, 4and establishing normall unrestrictedl flow of gaseous mixture from the regenerator upon the gaseous mixture in the regenerator dropping to a predetermined :low pressure, the predetermined low pressure being such that normal unrestricted flow of gaseous mixture from the regenerator at the predetermined c low pressure establishes a pressure drop across the bed of regenerfativernaterial producing `an upward force on the bed less than the density of the regenerative material.

l0. In ythe separation of gaseous mixtures by a fractionating operation employing a switchingoregenerator :including '-a bed of particles of regenerativey material and adapted to' beswitchedpbetween rst and second operating phases, in which relatively high pressure gaseous mixture' to be` fractionated hows downwardly through the ViegelneratorAduring the first operating phase and relatively low pressugecoid product from thefractionating operation `Vtllovvrs upwardly through the regenerator during the second operating phase', the method of controlling the ow yfrom the regenerator of gaseous mixture remaining'in the re- Vgenerator upon the regenerator being switched from the first operating phaseV to the second operating phasefto o prevent movement of particles forming thebed andthe resulting production of lrines, the method comprising the steps of restricting th'eiiowof` gaseous mixture from the regen'erator upon the regenerator being switched from the Vvfirst peratinggphase to 'theisecond operating phase to terial produces an upward force on the bed which is less than the density of the regenerative material, establishing normal unrestricted flow of gaseous mixture from the regenerator upon the gaseous mixture in the regenerator dropping to a predetermined low pressure, the predetermined low pressure of the gaseous mixture being such that normal unrestricted ow from the regenerator o f gaseous mixture at the predetermined low pressure establishes a pressure drop across the bed of regenerative material producing an upward force on the bed less than the density of the regenerative material, and establishng normal unrestricted flow of gaseous mixture downwardly through the regenerator upon the regenerator being switched from the second operating phase to the first operating phase.

`1l. In thel separation of gaseous mixtures by a fractionating operation Yemploying switching regenerators each including a bed of particles of regenerative material and adapted to be alternately switched between first and second operating phases, in which gaseous mixture Vunder relatively high pressure flows downwardly through one of thev regenerators and relatively low pressure cold product from the fractionating operation ilows upwardly through another regenerator during the rst operating phase and in which gaseous mixture under relatively high pressure Hows downwardly through the another regenerator and relatively low pressure cold product flows upwardly through the one regenerator during the second operating phase, the method of controlling the ow from the regenerators of gaseous mixture under relatively high pressure remaining in the regenerators upon the regenerators being switched to ow relatively low pressure cold product upwardly through the regenerators to prevent movement of particles forming the beds and resulting production 'of' iines, the method comprising the steps of establishing normal flow of gaseous mixture downwardly through one regenerator upon the one regenerator being switched from the second operating phase to the first operating phase, restricting the flow of gaseous mixture from another regenerator upon the another regenerator being switched from the rst operating phase to the second operating phase to establish a predetermined maximum ilow of gaseous mixture from the another regenerator with a resulting pressure drop across the bed of regenerative material producing an upward force on the bedless than the density ofv the regenerative material,

establishing normal unrestricted how of gaseous mixture ironr the another regenerator uponthe gaseous mixture 1n the another regenerator dropping to a predetermined ,low pressure, the predetermined low pressure of the gaseous mixture being such that normal unrestricted ow ofgaseous mixture from the another regenerator at the Ypredetermined low pressure establishes a pressure drop across thebed of regenerative material producing an upward force on the bed less than the density of the regenerative material. Y

. l2.V In the separation of gaseous mixtures by fractionating operation employing switching regenerators each including a bed of particles of regenerative material and adapted to be alternately switched between rst and secfines, the method comprising the steps of establishing normal ow of gaseous mixture downwardly through one regenerator upon the one regenerator being switched from the second operating phase to the lirst operating phase, restricting the ilow of gaseous mixture from another regenerator upon the another regenerator being switched from the first operating phase -to the second operating phase to establish a predetermined maximum ilow of gaseous mixture from the another regenerator such that the resulting pressure drop across the bed of regenerative material produces an upward force on the bed of regenerative material less than the density of the regenerative. material, maintaining normal flow of gaseous mixture downwardly through the one regenerator and progressively reducing the restricted ow of gaseous mixture from the another regenerator as the pressure of the gaseous mixture in the another regenerator decreases while maintaining the ow of gaseous mixture from the another regenerator below the predetermined maximum flow until the pressure of gaseous mixture in the another regenerator drops to a relatively low predetermined value such that the resulting pressure drop produced `across the bed upon unrestricted ow of gaseous mixture from the another regenerator at the relatively low value produces an Vupward force on the bed less than the density of the regenerative material, and providing unrestricted normal flow of gaseousV mixture from the another regenerator upon the pressure of the gaseous mixture in the another regenerator dropping to the relatively low value.

fll. In therseparation of gaseous mixtures by a fractionating operation employing switching regenerators each including a bed of particles of regenerative material and adapted to be alternately switched between first and second operating phases, in which gaseous mixture under relatively high pressure flows downwardly through one of the regenerators and relatively low pressure cold product from the fractionating operation flows upwardly through another regenerator during the first operating phase and in which gaseous mixture under relatively high pressure ows downwardly through the another regenerator and relatively low pressure cold product ows upwardly through the one regenerator during the second operating phase, the method of controlling the ilow from the regenerators of gaseous mixture under relatively high pressure remaining in the regenerators upon the regenerators being switched to ow relatively low pressure cold product upwardly through the regenerators to prevent movement of particles forming the beds and the .resulting production of fines, the method comprising the steps of establishing normal flow of gaseous mixture `downwardly through one regenerator upon the one regenond operating phases, in which gaseous mixture under relatively high pressure ows downwardly through one of the regenerators and relatively low pressure cold product from the fractionating operation iiows upwardly through another regenerator during the first operating phase and 1n which gaseous mixture under relatively high pressure flows downwardly through Vthe another regenerator and relatively low pressure Vcold product ilows upwardly through the one regenerator during the second operating phase, the method of controlling theow from the regenerators ofV gaseous mix-ture under relatively high pressure remaining in the regenerators upon the regenerators being switched to flow relatively low pressure cold product upwardly through the regenerators to prevent movement of Werator being switched from the second operating phase to the rst operating phase, restricting the flow of gaseous mixture from another regeneratorV upon the another regenerator being switched from the rst operating phase to the second operating phase to establish a predetermined maximum ow of gaseous mixture from the lanother re- `genator such thatthe resulting pressure drop across the bed of regenerativematerial produces an upward force on the bed less'than the Vdensity of theregenerative material, maintaining normal ow of gaseous mixture downwardly through the one regenerator while progressively Q reducing the restriction to flow of gaseous mixture from the another regenerator as the pressure of gaseous mixture in the another regenerator decreases to maintain ow of gaseous mixture from the another regenerator below the l predetermined maximum flow until the pressure of gaseous mixture in the another regenerator drops to a predetermined low value such that the pressure drop produced yacross the bed upon unrestricted flow of gaseous mixture from the another regenerator at the i relatively low value produces an upward force on the bed 17 l mixture in the another regenerator dropping to a relatively'lowv value, and establishing normal ow of gaseous mixture downwardly through the another regenerator upon the another regeneratorr being switched from the, second operating phase to the iirst operating phase, and establishing restricted flow of gaseous mixture from the oneregenerator upon the one regenerator lbeing switched from the first operating phase to the second operating phase, and controlling the restricted flow of gaseous mixture from 'the one regenerator to maintain the flow of gaseous mixture from the one regenerator below the predetermined maximum flow until the pressure of the gaseous mixture intheV one regenerator drops to the relatively low'value and thereafter establishing unrestricted normal How of gaseous mixture`from the one regenerator.

14. 'In combination with a regenerator comprising a gnam bed of Vparticles of regenerative material and means inl cluding conduit means and switching means for alternately flowing fluids under'diierent pressuresthrough the bed, valve means in 'the conduit means for controlling the ilow of iluid through the bed upon operation ofA the switching-means toterminate the tlow through the regen- 'eratorofiuid' under one pressure/and' initiate the ilow through the regenerator of Huid under ai differentY pressure, the: valvefmeans including means operable respon sively to apresslire 'diierential between fluid in the regenerator and fluid in the conduit means for restricting to a predetermined value the flow of uid iny the b'ed such that the pressure drop developed across the. bed produces an upward force on the bedless than the density of the regenerativefmateri'al, and means for establishingV normal unrestricted flow in the bed upon the pressure differential dropping to a value such that the resulting pressure drop produces. upward force'on the bed less than the density of theV regenerativev material.

`15. In combination with a regenerator` comprising a bed ofparticles of regenerative material and means including conduit-,means and switching' means forfflowing high pressure iluiddownwardly through the regenerator whenaswitched to oneoperating phase and for ilo'wing relatively low pressure fluid upwardly through the regenerator when. switchedto another operating phase, valve means in the' conduit meansfor controlling'the flow of highpressureluid in they regenerator uponV operation of the switching means to terminate the ow through the regenerator of `high pressure fluid and initiateftheiiow through the,` regenerator of relatively low pressure fluid, the. valvenmeans. includingl means operable responsively tothe relatively high `pressure of the fluid in the regeneratorfor `restricting to a predetermined value theA flow of high pressure fluid from the regenerator such that the pressure drop developed across the bed of regenerative material."` produces upward force on the bed less than the density oitheV yregenerative material, and means for establishing normal unrestricted flow from the regeneraltor upon-the'pressure of theuid in the regenerator dropping to avalue such that the resulting pressure drop across the bed produces an Aupward force on the bed less than the density of the regenerative material.

1 6. "1n combination with aV regenerator comprising a bed of particles eti-'regenerative material and means including conduit means and switching means for alternatelyfilowing fluids under diiferent pressure throughfthe bed, valve means'iii the Aconduit means for controlling the flow of fluid in the bed upon operation of the switching means to terminate the flow through the regenerator of fluid under one pressure and initiate the flow through the regenerator of iiuid under a different pressure, the valve means including means operable responsively to a pressure differential between Huid in the regenerator and fluid in the conduit means for restricting to a predetermined value the flow of liuid in the bed such that the resulting pressure drop across the bed produces an upward force on the bed less than the density of the regenerative material, means for progressivelyA increasing l is .18. the ow of fluid in the bed as the pressure of the ud in the bed decreases, vand means for establishing. normal unrestricted ilow in the bed upon the pressure differential dropping to a value such that the resulting pressure drop across the bed produces an upward force on the bed less than the density of the regenerative material.

17. In combination with a regenerator comprising a bed of particles of regenerative material and means including conduitrmeans and switching means for flowing fluid under relatively high pressure downwardly through the bed when the switching means is moved to one phase and for ilowing lluid under relativelyv low pressure Vupwardly through the bed when vthe switching means is moved to a second phase,.valve means including means operable responsively to iluid under relatively high pressure in the regenerator upon the regenerator being switched to the iirst phase to restrict to a predetermined Value the flow of fluid from the bed ysuch that the pressure dropidevelopedacross the bed produces an upward force on the bed less than the density of the regenerative material, means for progressively increasing the ilow of fluid from the regenerator as the pressure of the fluidin the regenerator decreases, and means for establishing normal unrestricted ow from the regenerator upon the pressure diierentiall dropping to a value such that the pressure drop developed across the bed produces 'an upward force on; the bed less than the .densitygof the regenerative material. c 18. In the separation of gaseous mixtures by a fractionating operation employing a switching regenerator including a bedof particles of regenerative material and adapted to be switched between first and second operating phases, in which relatively high pressure gaseous mixture to be fractionated flows downwardly through the regenerator during the iirst operating stage and relatively low pressure product from the fractionating operation' flows upwardly through the regenerator during the second operating stage, valvularv means for controlling flow from the 'regenerator of gaseous mixture remaining in the regenerator upon the regenerator being switched from the rs't operating phase to the second operating phase to prevent movement of particlesforming thel bedI and' the resulting production of'nes, the valvular means including means for restricting the flow of gaseous mixture from the regenerator upon the regenerator being switched from the first operating phase to the second operating phase to maintain'the ow of gaseous mixture from the Vregeneratory below a predetermined maximum fl'ow such that the resulting pressure drop across the bed ofregenerative material produces an upward force on they bed less than the density of the regenerative material, and means for establishing'normal unrestricted How of gaseous mixture from the: regenerator upon the gaseous mixture dropping toa predetermined low pressure, the .predetermined low pressure of the gaseous mixture being such that normal unrestricted: flow Yfrom the regenerator of gaseous mixture at the predetermined low pressure establishes a pres'- sure drop across the bed of regenerative material pro ducing an upward. force on the bed less than the density'of theregenerative material. i i 1-9. In; the separation of gaseous mixtures by'afractionating'operatiort employing a switchingV regenerato 'nf eind-ing; abed'o'parti'cles. of regenerative material" and' adapted to be switched between rst and second operating phases, in which relatively high pressure gaseous mixture to be fractionated flows downwardly through the regenerator during the iirst operating phase and relatively low pressure product from the fractionating operation flows upwardly through the regenerator during the second operating phase, valvular means for controlling iow from the regenerator of gaseous mixture remaining in the'regenerator upon the regenerator being switched from the iirst operating phase to the second operating phase to prevent movement `of particles forming the bed and the resulting production of iines, said valvular means comprising means for restricting the flow of gaseous mixture from the regenerator upon the regenerator being switched -from the rst operating phase to the second operating phase to establish la predetermined maximum flow of gaseous mixture at the relatively high pressure with the re- ,j

sulting pressure drop across the bed producing an upward force on the bed which is less than the density of the regenerative material, means for progressively decreasing the restriction to the ilow of gaseous mixture from the regenerator as the pressure of the gaseous mixture in the regenerator decreases while maintaining the flow of gase- `ous mixture from the regenerator below the predetermined maximum flow, and means establishing normal unrestricted ow of gaseous mixture from the regenerator upon the gaseous mixture in the regenerator dropping to a predetermined low pressure, the predetermined low pressure being such that normal unrestricted ilow of gaseous mixture at the predetermined low pressure from the regenerator establishes a pressure drop across the bed of regenerative material which produces an upward force on glie bed less than the density of the regenerative mater 120. In the separation of gaseous mixtures by a fractionating operation employing switching regenerators each including a bed of particles of regenerative material and adapted to be alternately switched between rst and second operating phases, in which gaseous mixture under relatively high pressure to be fractionated llows downwardly through one of the regenerators and relatively low pressure cold product from the fractionating operation ows upwardly through another regenerator during the rst operating phase and wherein relatively high pressure gaseous mixture ows downwardly through the another regenerator and relatively low pressure cold product ows upwardly through the one regenerator during the second operating phase, valvular means for controlling the flow from the regenerators of gaseous mixture under relatively high pressure remaining in the regenerators upon the regenerators being switched to flow relatively low pressure cold product upwardly through the regenerators to prevent movement of particles forming the bed and resulting production of iines, said valvular means comprising means for establishing normal flow of gaseous mixture downwardly through one regenerator upon the one regenerator being switched from the second operating phase to the lrst operating phase, means for restricting the flow of gaseous mixture from another regenerator being switched from the flrst operating phase to the second operating phase, the restricted flow of gaseous mixture establishing a predetermined maximum ow of gaseous mixture from the another regenerator such that the resulting pressure drop developed across the bed of regenerative material produces a lifting force on the bed less than the density of the regenerative material, means for maintaining normal ow of gaseous mixture downwardly through the one regenerator, means for progressively reducing the restriction to flow of gaseous mixture from the another regenerator as the pressure of the gaseous mixture in the another regenerator decreases to maintain the flow of gaseous mixture from the another regenerator below the predetermined maximum flow until the pressure of gaseous mixture in the another regenerator drops to a relatively low value such that the pressure drop developed across the bed upon'unrestricted llow of gaseous mixture from the another regenerator at the relatively low value produces an upward force on the bed less than the density of the regenerative material, means providing unrestricted Ynormal flow of gaseousmixture from the another regenerator when the pressure of the gaseous mixture drops to-the relatively low value, means establishing normal low of gaseous mixture downwardly through the another regenerator upon the another regenerator being switched from the second operating phase to the rst operating phase, means for establishing a restricted ilow of gaseous mixture from the one regenerator upon the one regenerator being switched from the rst operating phase to the second operating phase, and means for controlling the restricted flow of gaseous mixture from the one regenerator to maintain the ow of gaseous mixture om the one regenerator below the predetermined maximum ow until the pressure of the gaseous mixture drops to the relatively low value and thereafter establish unrestricted normal ow of residual gaseous mixture from the one regenerator.

21. In the separation of gaseous mixtures by a fractionating operation employing a regenerator including a bed of particles of regenerative material and adapted to be switched between rst and second operating phases, in which gaseous mixture under relatively high pressure ilows downwardly through the regenerator during the first operating phase and relatively low pressure cold product from the fractionating operation flows upwardly through the regenerator during the second operating phase, a fluid control valve connected to the regenerator and comprising a casing having an inlet and an outlet, means for forming an opening of variable cross-section between the inlet and the outlet, the last-named means including a valve member mounted Afor movement to a first position in which a restricted opening is established between the inlet and the outlet and a second position in which a relatively unrestricted opening is established between the inlet and the outlet and to positions intermediate the rst and second positions, means operable to progressively increase the size of the opening upon movement of the valve member from the rst position to the second position, means for normally urging the valve member tol the second position, means operable responsively to a predetermined pressure of uid at the inlet for moving the valve member to the first position, and means for moving the valve member from the rst position in a direction towards the second position in proportion to a drop in pressure of the fluid at the inlet below i the predetermined pressure to establish a controlled flow through the opening.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE `CEBfrIFICArE 0F CORRECTION Patent Non, 2947y151 l Auguste, 1960 Clarence J Schilling It is hereb'l Certified 'that error' appears in the-printed Specification of the above -'numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Columnll, line 64, for "the the" read the column l2., line 34 for "tensty" read density g column lv lines 57 and 58.,- or "regenator" read regenerator Signed and sealed this 4th day of April 1961,

(SEAL) Attest: ERNEST W. kSWIDER XXQLXXXMXME ARTHUR w. CROCKER Attesting Officer Acting Commissioner of Patents