US3458973A

US3458973A - Method and apparatus for component concentration in the vapor phase

Info

Publication number: US3458973A
Application number: US600498A
Authority: US
Inventors: John R Spencer; Walton D Greathouse; James H Cheek
Original assignee: Continental Oil Co
Current assignee: ConocoPhillips Co
Priority date: 1966-12-09
Filing date: 1966-12-09
Publication date: 1969-08-05
Anticipated expiration: 1986-08-05
Also published as: GB1183213A; BE723734A; DE1619858A1; SE336424B; NL6713774A; NO123833B

Description

Aug. 5, 1969 Filed Dec. 9. 1966 RAW GAS IN J. R. SPENCER E AL IN THE VAPOR PHASE 2 Sheets-Sheet. l

vs V I3 6 l4 7 9 IO H vs vs 3.4 4-

l8 a a a m m m n: 8 3 w o a 0 -l9 1 GAS COOLER -24 GAS HEATER VII BLOWER 29 RESIDUE GAS 4 44 42 3sv GAS TO GAS B OW HEAT EXCHANGER 39 ENRICHED GAS IN VEN TORS JOHN R. SPENCER WALTON D. GREATHOUSE JAMES H. CHEEK AGENT g- 5, 1969 J. R. SPENCER ET AL 3,458,973

METHOD AND APPARATUS FOR COMPONENT CONCENTRATION IN THE VAPOR PHASE e'zva 7 IO -M a v9 24 GAS HEATER via V I5 -30 Filed Dec. 9. 1966 2 Sheets-Sheet 2 RAW GAS IN ABSORBER k GAS TO GAS BLOWER HEAT EXCHANGER 2o v|9 vzo ENRICHED GAS HEAVY ENDS REJECTION FIG. 2 I

IN VENTORS JOHN R. SPENCER WALTON D. GREATHOUSE JAMES H. CHEEK United States Patent us. or. 5562 v 21 Claims ABSTRACT OF THE DISCLOSURE A cyclical method and apparatus for separating intermediate molecular weight hydrocarbon gases (ethane and ethylene) from primarily methane gas are disclosed. The feed stream of methane, ethane and ethylene gas is flowed through a sorbent bed where ethane and ethylene are adsorbed to a point of saturation. The saturated bed is then desorbed of ethane and ethylene by heating it in a closed heating circuit. As gas pressure in the heating circuit increases, part of the gas therein is bled from the circuit yielding a gas product enriched in ethane and ethylene. At the end of the heating or desorption step the heated bed is cooled by a stream of cool gas before being returned to the ethane-ethylene sorption step. A continuous operation is maintained by cycling three or more beds through the sorption, heating and cooling phases.

This invention relates to the separation of intermediate molecular Weight hydrocarbons from a gas stream. More specifically, this invention is concerned with the recovery of ethane from natural gas streams and with the recovery of ethane and ethylene from refinery gas streams.

Many hydrocarbon gas streams are processed to recover the propane and higher molecular weight hydrocarbons present. The intermediate molecular weight hydrocarbons, particularly ethane and ethylene, now also have become of importance as a source of raw material for certain chemical syntheses. Often, however, even though the ethane and ethylene fractions of these hydrocarbon gas streams are substantial, these fractions are not recovered because of the expense of the required equipment. The recovery methods most commonly used now are based essentially on absorbing ethane and ethylene in a cold oil sorbent and subsequently recovering the ethane and ethylene by regenerating the liquid sorbent. But again, cold oil absorption techniques are disadvantageous in that they require a great amount of expensive refrigeration equipment. Obviously, method and apparatus for recovering ethane and ethylene operating at or near atmospheric temperature will have advantages.

It is an object of this invention to present an improved method of recovering intermediate molecular weight hydrocarbons from hydrocarbon gas streams.

Another object of this invention is to present a method and apparatus for recovering intermediate molecular weight hydrocarbons which require a minimum of refrigeration equipment. I

Another object of this invention is to present method and apparatus for recovering ethane and ethylene from hydrocarbon gas streams by adsorption at or near atmospheric temperatures.

Another object of this invention is to present method and apparatus for separating ethane and ethylene from hydrocarbon gas streams which are etficient and economical.

Other aspects, objects, and advantages of our invention will become aparent from the following disclosure, the claims, and the accompanying figures. FIGURE 1 presents schematically one embodiment of applying our in- Patented Aug. 5, 1969 ventive method and apparatus. FIGURE 2 presents schematically a second embodiment.

In brief, our invention provides a cyclical method and apparatus for recovering intermediate molecular weight gases, such as ethane and ethylene, from a gas stream by adsorbing intermediate molecular Weight gases cyclically in one of a plurality of beds of solid sorbent; another spent bed of solid sorbent (saturated with ethane and/or ethylene) is regenerated by circulating through it a heated regeneration gas in a closed heating or regenerating circuit. As this sorbent bed is heated, the ethane and ethylene are desorbed from the sorbent and become part of the circulating regenerating gas, thereby causing the pressure in the closed regeneration circuit to increase. When pressure in the heating circuit reaches a predetermined value, a portion of the circulating gas is removed to maintain the predetermined pressure as heating and regenerating is continued. This gas stream removed is a mixture rich in ethane and ethylene and is a desired product of our method and apparatus.

It will be understood that the raw gas treated must consist primarily of ethane, ethylene, methane, and other inerts, with only traces of higher molecular weight hydrocarbons such as propane, butane, etc. Sources of such streams are natural gas from subterranean hydrocarbon reservoirs and petroleum refiney processing steams.

The method of our invention will now be described as embodied in and with reference to FIGURE 1. Raw gas, such as natural gas, containing an intermediate molecular weight hydrocarbon (ethane) to be recovered, flows into the system by way of conduit 1 to one of the

adsorbers

16, 17, and 18. The adsorbers are filled with a sorbent material, for example, activated carbon, capable of removing the intermediate molecular weight hydrocarbons from the raw gas stream. Let it be assumed that adsorber 16 is on stream, although during

latter phases conduits

3 and 4 will serve to conduct gas to adsorbers 17 and 18, respectively. The raw gas, in flowing through adsorber 16, is stripped of ethane. The residual gas flows from adsorber 16 by way of conduit 22 and is removed from the system. In subsequent phases of the cycle,

conduits

23 and 24 will serve similarly to remove gas from

adsorbers

17 and 18, respectively. In summary, the adsorption step of the method comprises flowing a raw gas through a sorbent body, thereby removing all or part of the intermediate molecular weight gas, for example ethane, in the gas and flowing the stripped residue gas from the sorbent body.

When the sorbent material in an adsorber becomes spent or saturated with ethane, it must be regenerated by passing through it a heated gas to desorb the adsorbed ethane. Let it be assumed that adsorber 18 is in the process of being heated and regenerated. A heated gas, obtained prior to beginning the heating step, from the residue gas stream flowing from another adsorber in the adsorption step of the method, flows by way of

conduits

11, 7, 14, and 4 to adsorber 18.

Conduits

11, 5, 12, and 2, and 11, 6, 13, and 3 serve a similar purpose when adsorbers '16 and 17 are regenerated. The heated gas flowing through adsorber 18 heats the sorbent material therein and causes the adsorber ethane to be desorbed. The gas stream flows from adsorber 18 by way of

conduits

24, 34, and 27 into conduits leading to the gas heater.

Conduits

22, 32, and 25, and 23, 33, and 26 serve a similar purpose when

adsorbers

16 and 17 are being heated. As the temperature of the regenerating gas circulating through adsorber 1-8 and that of the sorbent therein increases, the pressure within adsorber 18, heater 19, the interconnecting conduits and other equipment, increases substantially. When this pressure rises above a predetermined value, gas in the regeneration circuit is bled off through conduit 36 and valve V19 sufficiently to maintain pressure in adsorber 18 and heater 19 at the predetermined level. The gas thus removed is a concentration of ethane and is a desired product of the method. In summary, the regeneration step of the method comprises circulating a heater regeneration fluid through a spent sorbent bed in a closed circuit and removing gas enriched in ethane from the circuit to maintain a predetermined pressure in the circuit.

When a sorbent body has been heated sufficiently to remove the adsorbed ethane, it must be cooled before it can function again as a sorbent. Let it be assumed that adsorber 17 is to be cooled. The source of cooling gas is part or all of the residue gas stream flowing through conduit 44. This stream is diverted through conduit 46 and flows through a blower 21 and cooler 20. The cooling gas then flows through

conduits

15, 9, 13, and 3 into adsorber 17, and from adsorber 17 through

conduits

23, 33, 29, and 38 and returns to the residue gas stream 44. In summary, the cooling step of the method comprises diverting a portion of the residue gas stream from the adsorbing step, cooling the diverted stream, and passing it through the bed to be cooled.

As shown in FIGURE 1, it is desirable to flow the effiuent gas from the bed being cooled in heat exchange with gas in the heating circuit through a heat exchanger 41.

After heating a sorbent bed to a condition where the adsorbed and absorbed ethane is vaporized, the heated bed and associated conduits are filled with a gas rich in ethane. It is desirable to retain this gas within the system. At the same time, another spent sorbent bed must be placed in the regeneration step. To increase the efficiency of our method, therefore, the gas in the hot adsorber is displaced into the cold adsorber that is about to be regenerated by heating. A portion of residue gas from the adsorber in the sorption circuit is diverted and flowed into the hot regenerated bed and the conduits associated therewith. Simultaneously, gas in the cold spent adsorber is displaced back into the residue gas stream. As shown in FIGURE 1, assuming that adorber 18 is hot and adsorber 16 is about to be placed in the regeneration circuit, adsorber 17 would be switched into the adsorption step and a portion of the efliuent residue gas from adsorber 17 flowing in conduit 44 would be diverted through

conduits

46, 47, 15, 10, 14, and 4 through the hot regenerated bed 18. Since there is direct communication between adsorber 18 and adsorber 16 by way of

conduits

24, 34, 27, 31, 35, 45, 43, 40, heater 19,

conduits

11, 5, 12, and 2, a certain volume of gas will be displaced from adsorber 16 through conduit 22. This displaced gas is a lean, stripped gas and is discarded in the residue gas line 44.

The apparatus of our invention will now be described as embodied in and with reference to FIGURE 1.

The apparatus comprises a minimum of three circuits, a sorption circuit, a cooling circuit, and a heating or regenerating circuit. The sorption circuit comprises a raw gas inlet manifold coupled with the three sorbent beds which in turn are coupled with an exit residue gas manifold. In FIGURE 1, conduit 1 and

conduits

2, 3, and 4 in conjunction with valve V1, V2, and V3, respectively, make up the inlet gas manifold and control the flow of raw gas into the

adsorbers

16, 17, and 18. Similarly,

conduits

22, 23, and 24 intersecting with conduit 44 and interrupted by valves V16, V17, and V18, respectively, comprise the residue gas outlet manifold and control the flow of gas from the

adsorbers

16, 17, and 18 when each of these is in the sorption circuit.

Thus, if it be assumed that adsorber '16 is connected in the sorption circuit, valves V1 and V16 would be open and valves V2, V3, V4, V7, V10, and V13 would be closed so that raw gas may fiow through conduits 1 and 2, adsorber 16,

conduits

22 and 44.

The heating or regenerating circuit comprises inlet and outlet manifolds coupled with the three sorbent beds, a compressor, optionally a heat exchanger, and a gas heater.

In FIGURE 1, conduit 11 and

conduit

5, 6, and 7 interrupted by valves V4, V5, and V6 comprise the inlet heating gas manifold, which connects with the gas heater 19 and by

conduits

12 and 2, 13 and 3, and 14 and 4, with

adsorbers

16, 17, and 18, respectively.

Conduits

25, 26, and 27, interrupted by valves V10, V11, and V12, and

conduits

31 and 35 make up the exit heating gas manifold. The manifold is connected to the

adsorbers

16, 17, and 18 by

conduits

32 and 22, 33 and 23, and 34 and 24, respectively, and communicates through conduit 45, compressor 42, conduit 43, heat exchanger 41, and conduit 40 with gas heater 19. Thus, if it is assumed that adsorber 18 is connected in the heating circuit, valves V6 and V12 will be open and valves V3, V4, V5, V9, V10, V11, V15, and V18 will be closed. Heating gas can then circulate from the gas heater 19 through

conduits

11, 7, 14, 4, adsorber 18,

conduits

24, 34, 27, 31, 35, 45, compressor 42, conduit 43, heat exchanger 41, conduit 40, and back to gas heater 19. Conduit 36 and valve V19 are also connected into the heating circuit. As adsorber bed 18 is regenerated, pressure in the heating circuit will increase. Whne the pressure reaches a predetermined value, gas is bled off through valve V19 and conduit 36 to maintain the predetermined pressure value. The gas removed is enriched in ethane when processing a natural gas stream and is one of the desired products of the apparatus. Valve V19 can be made automatically responsive to the pressure in the heating circuit, opening and closing to maintain the desired pressure.

The cooling circuit comprises inlet and outlet cooling gas manifolds coupled with the three sorbent beds, a compressor or blower (if desired), and gas cooler. As shown in FIGURE 1, conduit 15 and

conduits

8, 9, and 10 interrupted by valves V7, V8, and V9 make up the cooling gas inlet manifold which connects with cooler 20 and through

conduits

12 and 2, 13 and 3, and 14 and 4 with

adsorbers

16, 17, and 18, respectively.

Conduits

28, 29, and 30 interrupted by valves V13, V14, and V15 and conduit 38 make up the cooling gas outlet manifold which is connected by

conduits

32 and 22, 33 and 23, 34 and 24 with

adsorbers

16, 17, and 18, respectively, and communicates through heat exchanger 41 and conduit 39 with the residue gas conduit 44. Thus, if it is assumed that adsorber 17 is connected in the cooling gas conduit, valves V8 and V14 will be open and valves V2, V5, V7, V9, V11, V13, V15, and V17 will be closed. Gas will then fiow from the residue gas line 44 through conduit 46, the blower 21, conduit 47, gas cooler 20,

conduits

15, 9, 13, and 3, adsorber '17,

conduits

23, 33, 29, and 38, heat exchanger 41, conduit 39, and back to the residue gas line 44.

As discussed above, when a hot sorbent bed is converted from the heating circuit to the cooling circuit, the gas present in the hot bed is displaced into the spent adsorbent bed by a volume of gas taken from the residue gas line. Assume adsorber 18 is to be switched from the heating circuit to the cooling circuit and adsorber 16 is to be switched to the heating circuit when adsorber 17 is switched to the sorption circuit. Under these conditions, valves V2, V4, V9, V12, V13, and V17 are open and valves V1, V3, V5, V6, V7, V8, V10, V11, V14, V15, V16, V18, and V19 are closed. Raw gas will then flow through conduits I and 3, adsorber 17, and the residue gas flow through

conduits

23 and 44. A portion of the residue gas will be diverted through conduit 46, blower 21, conduit 47, gas cooler 20,

conduits

15, 10, 14, 4, and into adsorber 18; correspondingly, gas in adsorber 18 will be displaced through

conduits

24, 34, 27, 31, 35, 45, blower 42, conduit 43, heat exchanger 41, conduit 40, heater 19,

conduits

11, 5, 12, and 2 into adsorber 16. Gas will flow from adsorber 16 through conduits 22 32, 12 8, heat exchanger 41, and conduit 39 to residue gas ine At the end of this displacement or purge step, the approprtate valves are opened and closed to continue the next cycle of adsorbing, heating, and cooling the adsorbers.

Alternatively, the efiluent gas from the adsorber about to be regenerated can be returned to the residue gas line by Opening the valve in the residue gas outlet manifold from the bed and closing the valve in the cooling gas outlet manifold. For example, in the preceding description of valve opening and closing during purging, valve V16 would be opened and valve V13 would remain closed. This flow path will bypass the heat exchanger 41 and may be advantageous in some cases.

A complete schedule of the opening and closing of valves is presented in Table I for three cycles.

TAB LE I ABSORBER AND VALVE SEQUENCE Absorber: I

16 Sorbing Purging Heating Purging Cooling Sorbing 17 Cooling Sorbing Sorbing Purging Heating Purging 18 Heating Purging Cooling Sorbing Sorblng Purging Valves:

C C C C O O O C C C C C O O C O C C C C C 0 0 C C C C C 0 C C O O C C C C C O O O C C C C O O C C C C C O 0 O C C C C O C C C O C C C O C C C C O C C O C C O C C C O O 0 C O C C C C 0 O C O Vl9 O 2 C O 2 C O 3 C Abbreviations: C=va1ve closed; O=valve opened.

An alternate sequence is indicated in the right-hand column for each purge step for valves V13 to V18.

2 Opened to maintain predeterlmned maximum pressure 1n heating circuit. At the end of three cycles, each of the sorbent beds has transferred through each circuit and is ready to resume 1ts first function. The switching of each bed from one circuit to another can be controlled by a time cycle mechanism or by temperature sensing mechanisms. The temperature sensing mechanisms are preferred. For example it may be desirable to place a temperature sensing element in the conduits leading from the heating circuit so that when the temperature of a bed in the heating circuit reaches a predetermined value, as indicated by the temperature of heating gas flowing from that bed, a new cycle can be started. Activated carbon is preferred for the sorbent material used in the sorbent beds.

FIGURE 2 depicts a second embodiment of our method and apparatus. Most of the elements of FIGURE 2 are identical to those in FIGURE 1 and so have been given identical numeral designations in FIGURE 2. In FIG- URE 2, the adsorption circuit is the same as in FIGURE 1. The heating circuit has been modified b adding a second release conduit 48 with valve V20, which is discussed below. The cooling circuit has been modified in that the position of the gas cooler 20 and blower 21 have been reversed, and valve V21 has been interposed between the two. Further, a conduit 49 now connects the upstream side of'the valve V21 to the residue gas line 44 and another conduit 50 the downstream side of the valve V21 to the residue gas line 44.

In the method depicted in FIGURE 2, the schedule for the valves of Table I remains the same; the adsorp tion and heating steps also are the same as described for FIGURE 1. Valve V20 remains closed and valve V21 open. The step of cooling, however, is conducted by recycling the cooling gas through the bed being cooled in a semi-closed cooling circuit.

Conduits

49 and 50 are connected to the cooling circuit to permit additional gas to enter the cooling circuit from the residue gas line as cooling progresses and the gas volume in the cooling circuit shrinks.

For example, if it is assumed adsorber 17 is being cooled, cooling gas will flow from the compressor 21 through

conduits

15, 9, 13, and 3, adsorber 17,

conduits

23, 33, 29, and 38, heat exchanger 41, conduit 51, gas cooler 20, conduit 52, valve V21, conduit 53, and back to the blower 21.

Conduits

49 and 50 connect the cooling circuit to the residue gas line, and gas flows through these conduits in quantity sutficient to compensate for shrinkage of gas volume in the cooling circuit.

In the purge or displacement step, the gas volume in the heated bed is displaced by circulating, in a semiclosed cycle, gas from the bed about to be heated into the bed about to be cooled, and simultaneously, gas from the bed to be cooled into the bed to be heated. For example, if it is assumed adsorber 1 8 is to begin cooling an adsorber 16 is to begin heating, then gas will be flowed through blower 21, conduit 15, valve V9,

conduits

10, 14, and 4, into adsorber 18, and from adsorber 18 through

conduits

24, 34, conduit 27, valve V12,

conduits

31, 35, 45, blower 42, conduit 43, heat exchanger 41, conduit 40, heater 19, conduit 11, valve V4,

conduits

5, 12, 2, adsorber 16,

conduits

22, 32, valve V13,

conduits

28, 38, heat exchanger 41, conduits 51, cooler 20, valve V21, conduit 52, conduit 53, and back to blower 21.

During the latter part of the displacement step, it may be desirable to displace the latter portion of the gas displaced from the hot adsorber completely from the system. This gas may contain traces of heavier hydrocarbons which, if displaced into the cold adsorber about to be regenerated, would tend to accumulate within the system. These heavier hydrocarbons are the last to be desorbed in regenerating the spent sorbent and are the last to be displaced from the sorbent as the purge step proceeds. This secondary purge step is accomplished by opening valve V20 and closing valve V21 and venting the effluent gas from the bed being purged from the system. Thus, for FIGURE 2, the flow path of gas will be from conduit 44 through conduit 50 and blower 21, conduit 15, valve V9, conduits 10, 1-4, 4, adsorber 18,

conduits

24, 34, 27, valve V12,

conduits

31, 35, 45, blower 42,

conduits

43, 48, and valve V20. This gas removed can be treated to remove the heavy hydrocarbons if desirable. This secondary purge step is optional and in many cases may not be necessary. A valve program showing the valve positions for the embodiment of FIGURE 2, including the secondary or subpurge step, is presented in Table H.

TABLE II ABSORBER AND VALVE SEQUENCE Adsorber:

16 Sorbing Purging Heating Purging Cooling Sorbing 17 Cooling Sorbing Sorbing Purging Heating Purging 18 Heating Purging Cooling Sorbing Sorbing Purging Valves:

V C C C C C C 0 O O O 0 C C C C C C C C O 0 0 C C O O O C C C C C C C C 0 O 0 C C C C C C C C O 0 C C C O O O C C C C C C C C O O 0 O 0 C C C C C C C O O O C C C C C C C C O 0 O O O C C C C C C O C C C C 0 C C C C C O C C C C C C O C C C 0 C C C C C C C O 0 O O O C C C C C C C C 0 O O C C C C O a C C 0 2 C C C 0 C C O C C 0 V21 0 0 C O O C O 0 0 Abbreviations: C=valve closed; O=valve opened. 1 Sequence in right column is for subpurge step at end of purge step. 2 Opened to maintain predetermined maximum pressure in heating circuit.

EXAMPLE to the next in response to a gas-temperature sensing point in the adsorber being reactivated when the gas-temperature reaches 400 F. Feed gas in conduit 1 is at about 100 F. and 820 p.s.i.g. in an amount of about 20 MM c.f./day (measured at 60 F. and 14.65 p.s.i.a.)

Adsorber vessels

16, 17, and 18 each have a volume, empty, of 592 ft. and operate at a pressure of about 810-830 p.s.i.a. Each adsorber contain about 16,200 lbs. of activated carbon (8-10 mesh). Temperature of the sorbent material is about 110 F. during adsorption, a maximum of about 450 F. and an average of about 375 F. during reactivation, and is cooled to about 120 F. during the cooling phase. Residue gas in an amount of about 18,800 M c.f./day at about 115-125 F. and 800 p.s.i.a. is produced by way of conduit 44. Reactivation gas is circulated in conduit 11 in an amount of about 13,500 M c.f./day at about 450 F. and 812 p.s.i.a. Reactivation gas in conduit 45 is maintained at a predetermined pressure of about 806 p.s.i.a. by bleeding off gas through valve V19 in an amount of about 1,200 M c.f./day. Gas in conuduit 15 has a temperature of about 120 F. and in conduit 39 (FIGURE 1) has a temperature of about 175 F. and flows through conduit 15 (FIGURE 1) or conduit 49 (FIGURE 2) in an amount of about 20,000 M c.f./day. Heater 19 is designed for a duty of 6,600,000 B.t.u./hr. and 1,000 p.s.i.g.

Average compositions in mole percentages at various points throughout the system are tabulated below:

Carbon Propane Conduit N2 dioxide Methane Ethane plus The words sorption, sorbent, adsorb, etc., are used herein to connote the phenomena of adsorption and/ or absorption.

Having thus described our invention by providing specific examples thereof, it is to be understood that no undue limitations or restrictions are to be drawn by reason thereof and that many variations and modifications are within the scope of the invention.

What is claimed is:

1. Apparatus for removing sorbable components from a hydrocarbon gas stream comprising:

(a) a plurality of vessels containing a solid sorbent;

(b) a heater;

(c) a cooler;

(d) gas circulating means;

(e) a plurality of first conduits conducting said hydrocarbon gas stream to said vessels (a);

(f) a plurality of second conduits communicating between said vessels (a) and a first point of utility;

(g) a plurality of third conduits communicating between said vessels (a) and said heater (b);

(h) a plurality of fourth conduits communicating between said vessels (a) and said gas circulating means (i) a fifth conduit communicating between said gas circulating means ((1) and said heater (b);

(j) a gas releasing means communicating between a second point of utility and a circuit consisting of said heater (b), at least one of conduits (g), at least one of vessels (a), at least one of conduits (h), gas circulating means (d), and conduit (i);

(k) a plurality of sixth conduits communicating between said vessels (a) and said cooler (c);

(l) a plurality of seventh conduits communicating between said vessels (a), said first point of utility (f), and said cooler (c); and

(m) valve means in each of said plurality of first, second, third, fourth, sixth, and seventh conduits of (e), (f), (g), (h), (k), and (1), respectively.

2. The apparatus of claim 1 and a gas-to-gas heat exchanger communicating between said plurality of conduits (l) and said point of utility of (e) and communicating between one of said vessels (a) and said heater (b).

3. The apparatus of claim 1 wherein said gas releasing means (j) is a valve.

4. The apparatus of claim 1 wherein said gas releasing means (j) is a valve responsive in action to the gas pressure in the circuit of (j).

5. The apparatus of claim 1 and a gas circulating means communicating between said cooler (c) and said plurality of vessels (2.).

6. Apparatus for removing sorbable components from a hydrocarbon gas stream comprising:

(a) a plurality of vessels containing a solid sorbent;

(b) a heater;

(c) a cooler;

(d) gas circulating means;

(e) a plurality of first conduits conveying said gas stream of said vessels (a);

(h) a plurality of fourth conduits communicating between said vessels (a) and said gas circulating means (i) a fifth conduit communicating between said gas circulating means (d) and said heater (b);

(j) a gas releasing means communicating between a second point of utility, and a circuit consisting of said heater (b), at least one of conduits (g), at least one of said vessels (a), at least one of conduits (h), gas circulating means (d), and conduit means (i);

(k) a plurality of sixth conduits each communicating at one end with said vessels (a);

(l) a plurality of seventh conduits communicating between said said vessels (a) and one end of said cooler (m) a valve communicating, when opened, between a second end of said cooling means (c) and the other end of each of said plurality of sixth conduits (k);

(u) an eighth conduit communicating between one end of said valve (m), said second end of said cooling means (c), and said first point of utility of (f);

(o) a ninth conduit communicating between a second end of said valve (m), said plurality of conduits (f and said plurality of conduits (k); and

(p) valve means in each of said plurality of first, second, third, fourth, sixth and seventh conduits of (g) and respectively- 7. The apparatus of claim 6 and a gas-to-gas heat exchanger communicating between said plurality of conduits (l) and said cooler (c) and communicating between one of said vessels (a) and said heater (b).

8. The apparatus of claim 6 and a second gas releasing means (q) communicating between a third point of utility and the circuit of (j).

9. The apparatus of claim 8 wherein said gas releasing means (j) and (q) are each a valve.

10. A method of separating ethane and ethylene gas from a gas stream comprising ethane, ethylene, and methane, and containing only traces of higher molecular weight hydrocarbons comprising:

(a) contacting a solid sorbent body with said gas stream, thereby adsorbing said ethane and ethylene gas onto said solid sorbent body;

(b) contacting said solid sorbent body with a heated flowing gas in a closed circuit, thereby desorbing said solid sorbent body of ethane and ethylene gas into said flowing gas;

(c) withdrawing a portion of said heated gas of (b) containing desorbed ethane and ethylene gas as product from said closed circuit;

(d) returning the remaining poriton of said heated gas to contacting said solid sorbent body in step (b);

(e) purging said sorbent body of heated gas; and

(f) contacting said sorbent body with a cool gas, thereby cooling said sorbent body to a temperature suflicient to repeat step (a).

11. The method of claim wherein the heated gas of (b) is circulated in heat exchange relationship with the cool gas of step (f).

12. In the method for removing ethane and ethylene gas from a gas mixture comprising ethane, ethylene, and methane, and containing only traces of higher molecular weight hydrocarbon gases, utilizing the contact of solid sorbent material with the gas mixture, with resultant adsorption of the ethane and ethylene gas by the solid sorbent material and the subsequent treatment of the solid sorbent material with a heated gas to desorb and remove the adsorbed ethane and ethylene gas and to thereby regenerate a solid sorbent material for further contact with the gas mixture, the improvement which comprises:

(a) maintaining at least one bed of solid sorbent material in each of a plurality of zones;

(b) continuously heating and flowing gas in a closed circuit through at least one of said beds of sorbent material to desorb ethane and ethylene gas contained on the sorbent in said bed, and to heat the sorbent material in said bed;

(c) removing a portion of said heated gas of (b) from said closed circuit;

(d) returning the remaining portion of said heated gas to the heating and flowing step of (b);

(e) continuously directing a flow of cool gas through at least another one of said beds of sorbent material to cool said sorbent bed;

(f) directing a rflow of gas containing ethane and ethylene gas through an additional one of said beds of sorbent material to remove said ethane and ethylene gas from said gas by sorption in said bed; and

(g) periodically shifting the relative positions of the beds of sorbent material and the flow of gases in each of said beds so that each bed of step (a) is heated as in (b), cooled as in (d), and contacted with gas as in (f).

13. The method as set forth in claim 12 wherein after a sorbent bed being heated has become desorbed of ethane and ethylene gases adsorbed therein, the heated gas present in said bed is displaced into another sorbent bed subsequently to be heated, and simultaneously the gas present in that latter sorbent bed is displaced therefrom, thereby conserving the desorbed ethane and ethylene gases contained in said heated gas.

14. The method as set forth in claim 12 wherein said portion of heated gas removed from said closed circuit in step (c) is removed at a rate suificient to maintain a predetermined pressure in said closed circuit.

15. The method of claim 12 wherein after the sorbent bed of step (b) has become desorbed of ethane and ethylene gases, the volume of heated gas then present in said bed of step (b) is displaced into the sorbent bed of step (f) and the volume of gas then present in said bed of step (f) is displaced therefrom into said sorbent bed of step (b).

16. The method of claim 12 wherein after the sorbent bed of step (b) has been desorbed of ethane and ethylene gases, a first portion of the regeneration gas in said bed of step (b) is displaced into the sorbent bed of step (f) and a second portion of the regeneration gas in said bed of step (f) is discharged independently of said sorbent beds of steps (b), (d), and (f).

17. The method of claim 12 wherein the gas of step (b) is flowed in heat exchange relationship with the cool gas of step (e).

18. The method of claim 12 wherein the gas removed from said gas mixture is ethane.

19. The method of claim 12 wherein the gas removed from said gas mixture is ethylene.

20. The method of claim 12 wherein said gas mixture is a natural gas stream.

21. The method of claim 12 wherein said gas mixture is a refinery gas stream.

References Cited UNITED STATES PATENTS 3,055,157 9/1962 Lavery et al. -62 X 3,080,692 3/ 1963 Staley et al. 55-62 X 3,186,144 6/1965 Dow 5562 X 3,266,221 8/1966 Avery 55-62 X 3,324,669 6/1967 Cooper et al 55-62 X 3,311,189 7/1967 Worley 55-62 REUBEN FRIEDMAN, Primary Examiner I. ADEE, Assistant Examiner US. Cl. X.R.