CA2072295A1 - Adsorbent vessel having a convective heat exchanger and flow developer - Google Patents
Adsorbent vessel having a convective heat exchanger and flow developerInfo
- Publication number
- CA2072295A1 CA2072295A1 CA002072295A CA2072295A CA2072295A1 CA 2072295 A1 CA2072295 A1 CA 2072295A1 CA 002072295 A CA002072295 A CA 002072295A CA 2072295 A CA2072295 A CA 2072295A CA 2072295 A1 CA2072295 A1 CA 2072295A1
- Authority
- CA
- Canada
- Prior art keywords
- adsorbent
- flow
- component
- gas mixture
- component gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
- B01D53/0407—Constructional details of adsorbing systems
- B01D53/0438—Cooling or heating systems
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
- B01J8/0242—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly vertical
- B01J8/025—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly vertical in a cylindrical shaped bed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
- B01J8/0278—Feeding reactive fluids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
- B01D2253/10—Inorganic adsorbents
- B01D2253/106—Silica or silicates
- B01D2253/108—Zeolites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2256/00—Main component in the product gas stream after treatment
- B01D2256/12—Oxygen
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/10—Single element gases other than halogens
- B01D2257/102—Nitrogen
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Separation Of Gases By Adsorption (AREA)
Abstract
Abstract The present invention provides an adsorbent vessel adapted to contain an adsorbent and form an adsorbent bed for use in adsorbing a component of a multicomponent gas mixture during a pressure swing adsorption process. In accordance with such process the adsorbent bed is regenerated by desorbing the adsorbed component. The adsorption capacity of the adsorbent decreases with decreasing temperature and the pressure swing adsorption process produces a cold spot of reduced temperature within a region of the adsorbent bed. In order to combat the resulting decreased adsorption capacity, a convective heat exchanger extends into the cold spot to raise the temperature of the cold spot. The convective heat exchanger is provided with at least two passes for the entering multi-component gas mixture or the outward bound desorbed component to transverse and thereby transfer heat to the cold spot. Additionally, the heat exchanger can also serve to supply a sufficiently long straight run for the entering multi-component gas mixture to fully develop. The full development of the entering flow prevents unequal distribution of the multi-component gas mixture within the adsorbent bed.
Description
2~722~
ADSORBENT VESSEL HAVI~G A CONVECTIVE EEAT EXCHANGER
AND FLOW DEVELOPER
Background of the Invention The present invention relates to an adsorbent vessel containing an adsorbent to form an adsorbent bed for use in a pressure s~ing adsorption process wherein a cold spot forms in the adsorbent bed and/or flow to the adsorbent bed is not fully developed. More particularly, the present invention relates to such an adsorbent vessel in which a convective heat exchanger is located with the adsorbent vessel to raise the temperature of the cold spot and/or to fully develop fiow to the adsorbent bed.
Pressure swing adsorption is used to produce a product gas from a multi-component gas misture by adsorbing a component contained within the gas mi~ture. In a typical pressure swing adsorption process to generate o~ygen, air is passed under pressure into an adsorbent formed of zeolite pellets to adsorb nitrogen and to produce a product gas composed essentially of oxygen. The adsorbent is then regenerated by desorbing nitrogen therefrom. ~everal interconnected adsorbent vessels containing the adsorbent are ordinarily used in carrying out the pressure swing adsorption process so that the adsorbent ~essels can alternately be used to produce product or to - 2 - 2~ 72~
regenerate the adsorbent.
Adsorption by the adsorbent is e~othermic while desorption of the adsorbent is endothermic. If a pressure swing adsorption process were conducted to thermodynamic perfection, then the heat produced by adsorption could be used in desorption. However, adsorption does not uniformly occur in the adsorbent bed. Additionally, heat is carried away in the product gas and the desorbed gas. As a result, a cold spot forms near an inlet of the adsorption vessel and a hot spot forms near an outlet of the adsorption vessel. The adsorption capacity of some adsorbents such as zeolites, however, decreases with decreasing temperature, and therefore, the effectiveness of the adsorption decreases within the cold spot.
Another possible factor that can decrease the effectiveness of adsorption concerns the flow of the gas mixture into the adsorbent bed. For instance, if a bend or tee fitting is located too close to the inlet of the adsorbent vessel, the flow of the gas mixture will not be fully developed upon its entry into the adsorbent vessel. That is, the flow velocity will vary across the flow of thP gas mi~turs. The disadvantage of this is that the gas mi~ture will be distrihuted on an unequal basis within the adsorbent bed and thereby decrease the degree to which the component of the gas mi~ture is actually adsorbed in the adsorbent bed.
The present invention provides an apparatus that has principal use in increasing the temperature of the cold spot, and therefore, decreasing the deterioration of the adsorbent capacity of the adsorbent due to the cold spot. Additionally, the present invention also provides a compact device to fully develop flow entering an adsorbent bed to insure that the gas to be ~eparated is equally distributed throughout the adsorbent bed.
Dr~R o 92591 PATENT
2~722~
~ummary Qf the Inven~ion The present invention provides an adsorbent vessel for containing an adsorbent to ~orm an adsorbent bed used in a pressure ~wing adsorption process wherein a component of a multi-component gas mixture is adsorbed to produce a product gas essentially free of the component and the adsorbent bed is regenerated by desorbing the component from the adsorbent bed.
The adsorbent has a deteriorating adsorption capacity at a reduced temperature and the prPssure swing adsorption process produces a cold spot of the reduced temperature within the adsorbent bed.
The adsorbent vessel has an inlet through which the multi-component gas mi~ture and the adsorbed component flow, to and from the adsorbent, respectively. At least one elongated, convective heat e~changer, fabricated from a heat conductive material, is located within the adsorbent vessel to extend into the cold spot. The at least one elongated, convective heat e~changer has at least two oppositely directed, lengthwise extending passes in communication with one another and also with the inlet such that the multi-component gas mi~ture and the desorbed component traverse the at least two oppositely directed passes upon entering and leaving the adsorbent vessel. As a result, heat is transferred from the multi-component gas mi~ture and the desorbed component to the cold spot to raise cold spot temperature above the reduced temperature. Consequently, the deterioration of the adsorbent capacity of the adsorbent will decrease with the increase in temperature.
In another aspect, the present invention provides an adsorbent vessel for containing an adsorbent to form an adsorbent bed used in a pressure swing adsorption process wherein a component of a multi-component gas mixture is adsorbed to produce a product gas essentially free of the DMR092591 PATE~T
20722~
component. The multi-component gas mi~ture is supplied to the adsor~ent vessel under conditions of non-fully developed flow.
As a result, the multi-component gas misture is not uniformly distributed to the adsorbent bed.
The adsorbent vessel has an inlet through which the non-fully developed flow of the multi-component gas mi~ture enters the adsorbent vessel. In order to cure problems associated with the non-uniform distribution of the multi-component gas mi~ture, an elongated flow developer is provided. The flow developer is located within the adsorbent vessel and has two oppositely directed, lengthwise e~tending passes. The two lengthwise e~tending passes are in communication with one another and the inlet such that the multi-component gas mi~ture traverses the two passes before entering the interior of the adsorbent vessel. One of the two passes, through which the multi-component gas mixture flows just prior to entering the adsorbent vessel, is configured to provide a straight run having a length sufficient to fully develop the flow of the multi-component gas mi~ture.
In still another aspect, the present invention provides an adsorbent vessel containing at least one elongated heat exchanger as described above. Such a heat e~changer can be fabricated to also act ~s a flow developer. In such case, one of the at least two passes, through which the multi component gas flows just prior to entering the adsorbent vessel, is configured to provide a straight run having a length sufficient to fully develop the flow of the multi-component gas mi~ture.
Brief DescriPtion of the Dr~winqs While the specification concludes with claims particularly pointinq out the subject matter that Applicant regards as his invention, it is believed that the invention will be better understood from the following description taken in conjunction DMR092591 PATE~T
2~72~
with the accompanying drawings in which:
Fiq. 1 is a ~chematic, sectional view of an adsorbent vessel in accordance with the present invention; and Fig. 2 is a sectional view taken along line 2-2 of Fiq. 1.
~tailed DesçriPtion With reference to the Figs., an adsorbent vessel 10 in accordance with the present invention is illustrated.
Adsorbent vessel 10 has an interior 12 to contain a zeolite adsorbent for use in fractionating oxygen from air. As would bP appreciated by those skilled in the art, adsorbent vessel 10 could be shaped wider and flatter than the form illustrated in complete dependence upon process considerations and the amount of adsorbent to be utilized.
A pair of opposed inlet and outlet distributors 14 and 16 are provided at openings 18 and 20 at the ends of adsorbent vessel 10 and are held in place in a manner well known in the art. Both inlet and outlet flow distributors 14 and 16 are provided with end walls 22 and 24 and sidewalls 26 and 28 of cylindrical configuration projecting into openings 18 and 20.
End walls 22 ana 24 are provided with inlet and outlet openings 30 and 32 defined ~in end walls 22 and 24 and sidewalls 26 and 28 are provided with a plurality of ~lit-like apertures 34 and ~6. Outlet distributor 16 is provided with an opposed end wall 37 connected to sidewall 28 thereof so that process gasses are constrained to pass through slit-like apertures 36 of sidewall 28. Inlet distributor 14 is not provided with such an opp^ _d end wall and as such constitutes a ~odified form of a flow distributor for purposes that will become apparent.
Inlet and outlet pipes 38 and 40 pass through inlet and outlet openings 30 and 32 of end walls 22 and 24 and are welded :
- 6 - 2~22~5 to end walls 22 and 24. Pressurized air enters interior 12 of adsorbent vessel 10 via an inlet pipe 38 for adsorption of nitrogen within the zeolite adsorbent that can be contained within adsorbent vessel 10. The zeolite adsorbent, not illustrated, is contained and supported within adsorbent vessel 10 between perforate supporting structures 42 and 44, well known in the art, that allow passage of the process gases to and from the adsorbPnt. The perforate supporting structures allow a sufficient volume to be created within interior 12 of adsorbent vessel 10 above and below the zeolite adsorbent to allow for the accumulation and distribution of process gases~
The adsorption of nitrogen within the zeolite adsorbent produces a product o~ygen gas essentially free of the nitrogen which is discharged from adsorbent vessel 10 via outlet conduit 40. As would be known to those skilled in the art, additional process streams such as purge, backfill and equali~ation gases also flo~ to and from vessel 10 through outlet conduit 40.
During regeneration, reduced pressure is applied to inlet conduit 38 to cause adsorbed nitrogen to desorb from the zeolite and ke drawn from adsorbent vessel 10 through inlet conduit 38.
As mentioned previously~ due to heat of adsorption, a cold spot tends to form within the zeolite contained within adsorbent vessel 10 closer to inlet distributor 16 than to outlet distributor 18. In adsorbent vessel 10, the cold spot e~ists within the central, lower one third region of the zeolite contained within the vessel. The reduction in temperature of the zeolite within the cold spot decreases the capacity of zeolite to adsorb nitrogen. In the present invention, the cold spot is heated by an elongated, convective heat e~changer 46 fabricated from a heat conductive material, for instance stainless steel. Heat exchanger 46 is located within the adsorbent vessel so as to e~tend into the cold spot.
7 2~722~
Heat e~changer 46 has a reversing flow path for either the air entering interior 12 of adsorbent vessel lO or desorbed nitrogen passing out of interior 12 of adsorbent vessel 10.
Since the air is much warmer than the cold spot, typically 0 C., but as low as -60 C., the reversing path taken by the entering air tends to raise the temperature of the cold spot.
Additionally, since desorbed nitrogen is approximately 20 C., a good deal warmer than the cold spot, heat tends to transfer to the cold spot from also the outgoing desorbed nitrogen to raise the temperature of the cold spot, and thus, prevent deterioration of the performance of the zeolite adsorbent.
Convective heat e~changer 46 comprises inlet pipe 38, which is sized to project inwardly and is left open to form an inner tube of heat e~changer ~6, an outer tube 48, and an inner end cap 50. Inner end cap 50 is connected to one of the ends of outer tube 48. Outer tube 48 is connected at the other of its ends to cylindrical sidewall 26 of inlet distributor 16.
The resulting structure of heat exchanger 46 has two oppositely directed, lengthwise extending passes formed by inlst pipe 38 and an annular flow area 52 formed between inlet pipe 38 and outer tube 48. For instance, air passing through the pass formed by inlet pipe 38 flows toward and înto the cold spot to heat -the cold spot~ The air then reverses direction at inner end cap 50 and then flows through the pass formed by annular flow area 52. The air then flows into inlet distributer 18 and passes into interaor 12 of vessel lO through slit-like apertures 34 thereof. After passage through slit-like apertures 34, the air reverses direction again in its flow to the adsorbent. The desorbed nitrogen flows along a flow path that is the reverse of that taken by the entering air.
The passes are designed to allow heat to be transferred, through the heat conductive material forming elongated heat e~changer 46, to the ~old spot from the air or desorbed nitrogen during their transverse of the reversinq flow path - B - ~ 072295 defined by the two passes. Practically, this is accomplished by appropriately sizing heat e~changer 46 to e~tend into the cold spot region or slightly past the cold spot region of the adsorbent bed. If necessary, heat e~changer 42 can e~tend the full length of adsorption vessel 10.
Heat e~changer 46 can serve to fully develop the air flow into adsorbent vessel 10 in the event that such flow is not fully developed. In this regard, it is 60metimes necessary to locate tee kittings and bends, through which air flows to the adsorbent vessel, very near the inlet to the adsorbent vessel.
As the air flow changes direction around a bend or through a tee fitting, the ~elocity distribution across the air flow becomes non-uniform or not fully developed. Normally a straight run o~ si~ or more pipe diameters are provided after the tee fitting or bend to allow the air flow to fully develop before entering the adsorbent vessel. When this is not or cannot be done because of other design considerations, the non-uniform velocity distribution across the air flow will cause the air to non-uniformly distribute itself in the adsorbent vessel and thus, the adsorbent. As a result, adsorb~nt will be unequally utilized to decrease the adsorption capability of the adsorption bed.
Convective heat e~changer 46 solves this problem by providing a sufficient straight run of flow for the entering air to fully dPvelop prior to its entry into the adsorbent bed. In this regard, this sufficient straight run is proYided by annular flow area 52. In order to decrease the length of annular flow area 52 and hence, heat e~changer 46, required for such a purpose, flow straighteners such as radially e~tending plates 54 can be provided within annular ~low area 52. In place of plates 54, bundles of open ended pipes could be ir.serted into annular flow area 52.
In the event that in addition to a cold spot problem, a - DM~092591 PATENT
2~722~
flow development problem, as described above, is inherent in the pressure swing adsorption system design, then heat exchanger can be designed to also fully develop the flow of incoming air. As may be appreciated, heat exchanger 46 can be solely designed to solve flow development problems without regard to potential cold spot problems. In any possible embodiment of or use for heat e~changer 46, the flow areas of annular flow area 52 and inlet ~ipe 38 should each be no less than the transverse cross-sectional area of process piping to prevent excessive pressure drops in the process piping. In addition to the foregoing, other possible embodiments of the subject invention could include the use of mo~e than one elongated, convective heat exchangers or an elongated convective heat exchanger having more than two passes. The disadvantage of such embodiments would be the increase in pressure drop produced by the additional passes.
While a preferred embodiment of the invention have been shown and described in detail, it will be readily understood and appreciated by those skilled in the art, that numerous omissions, changes and additions may be made without departing from the spirit and scope of the invention.
ADSORBENT VESSEL HAVI~G A CONVECTIVE EEAT EXCHANGER
AND FLOW DEVELOPER
Background of the Invention The present invention relates to an adsorbent vessel containing an adsorbent to form an adsorbent bed for use in a pressure s~ing adsorption process wherein a cold spot forms in the adsorbent bed and/or flow to the adsorbent bed is not fully developed. More particularly, the present invention relates to such an adsorbent vessel in which a convective heat exchanger is located with the adsorbent vessel to raise the temperature of the cold spot and/or to fully develop fiow to the adsorbent bed.
Pressure swing adsorption is used to produce a product gas from a multi-component gas misture by adsorbing a component contained within the gas mi~ture. In a typical pressure swing adsorption process to generate o~ygen, air is passed under pressure into an adsorbent formed of zeolite pellets to adsorb nitrogen and to produce a product gas composed essentially of oxygen. The adsorbent is then regenerated by desorbing nitrogen therefrom. ~everal interconnected adsorbent vessels containing the adsorbent are ordinarily used in carrying out the pressure swing adsorption process so that the adsorbent ~essels can alternately be used to produce product or to - 2 - 2~ 72~
regenerate the adsorbent.
Adsorption by the adsorbent is e~othermic while desorption of the adsorbent is endothermic. If a pressure swing adsorption process were conducted to thermodynamic perfection, then the heat produced by adsorption could be used in desorption. However, adsorption does not uniformly occur in the adsorbent bed. Additionally, heat is carried away in the product gas and the desorbed gas. As a result, a cold spot forms near an inlet of the adsorption vessel and a hot spot forms near an outlet of the adsorption vessel. The adsorption capacity of some adsorbents such as zeolites, however, decreases with decreasing temperature, and therefore, the effectiveness of the adsorption decreases within the cold spot.
Another possible factor that can decrease the effectiveness of adsorption concerns the flow of the gas mixture into the adsorbent bed. For instance, if a bend or tee fitting is located too close to the inlet of the adsorbent vessel, the flow of the gas mixture will not be fully developed upon its entry into the adsorbent vessel. That is, the flow velocity will vary across the flow of thP gas mi~turs. The disadvantage of this is that the gas mi~ture will be distrihuted on an unequal basis within the adsorbent bed and thereby decrease the degree to which the component of the gas mi~ture is actually adsorbed in the adsorbent bed.
The present invention provides an apparatus that has principal use in increasing the temperature of the cold spot, and therefore, decreasing the deterioration of the adsorbent capacity of the adsorbent due to the cold spot. Additionally, the present invention also provides a compact device to fully develop flow entering an adsorbent bed to insure that the gas to be ~eparated is equally distributed throughout the adsorbent bed.
Dr~R o 92591 PATENT
2~722~
~ummary Qf the Inven~ion The present invention provides an adsorbent vessel for containing an adsorbent to ~orm an adsorbent bed used in a pressure ~wing adsorption process wherein a component of a multi-component gas mixture is adsorbed to produce a product gas essentially free of the component and the adsorbent bed is regenerated by desorbing the component from the adsorbent bed.
The adsorbent has a deteriorating adsorption capacity at a reduced temperature and the prPssure swing adsorption process produces a cold spot of the reduced temperature within the adsorbent bed.
The adsorbent vessel has an inlet through which the multi-component gas mi~ture and the adsorbed component flow, to and from the adsorbent, respectively. At least one elongated, convective heat e~changer, fabricated from a heat conductive material, is located within the adsorbent vessel to extend into the cold spot. The at least one elongated, convective heat e~changer has at least two oppositely directed, lengthwise extending passes in communication with one another and also with the inlet such that the multi-component gas mi~ture and the desorbed component traverse the at least two oppositely directed passes upon entering and leaving the adsorbent vessel. As a result, heat is transferred from the multi-component gas mi~ture and the desorbed component to the cold spot to raise cold spot temperature above the reduced temperature. Consequently, the deterioration of the adsorbent capacity of the adsorbent will decrease with the increase in temperature.
In another aspect, the present invention provides an adsorbent vessel for containing an adsorbent to form an adsorbent bed used in a pressure swing adsorption process wherein a component of a multi-component gas mixture is adsorbed to produce a product gas essentially free of the DMR092591 PATE~T
20722~
component. The multi-component gas mi~ture is supplied to the adsor~ent vessel under conditions of non-fully developed flow.
As a result, the multi-component gas misture is not uniformly distributed to the adsorbent bed.
The adsorbent vessel has an inlet through which the non-fully developed flow of the multi-component gas mi~ture enters the adsorbent vessel. In order to cure problems associated with the non-uniform distribution of the multi-component gas mi~ture, an elongated flow developer is provided. The flow developer is located within the adsorbent vessel and has two oppositely directed, lengthwise e~tending passes. The two lengthwise e~tending passes are in communication with one another and the inlet such that the multi-component gas mi~ture traverses the two passes before entering the interior of the adsorbent vessel. One of the two passes, through which the multi-component gas mixture flows just prior to entering the adsorbent vessel, is configured to provide a straight run having a length sufficient to fully develop the flow of the multi-component gas mi~ture.
In still another aspect, the present invention provides an adsorbent vessel containing at least one elongated heat exchanger as described above. Such a heat e~changer can be fabricated to also act ~s a flow developer. In such case, one of the at least two passes, through which the multi component gas flows just prior to entering the adsorbent vessel, is configured to provide a straight run having a length sufficient to fully develop the flow of the multi-component gas mi~ture.
Brief DescriPtion of the Dr~winqs While the specification concludes with claims particularly pointinq out the subject matter that Applicant regards as his invention, it is believed that the invention will be better understood from the following description taken in conjunction DMR092591 PATE~T
2~72~
with the accompanying drawings in which:
Fiq. 1 is a ~chematic, sectional view of an adsorbent vessel in accordance with the present invention; and Fig. 2 is a sectional view taken along line 2-2 of Fiq. 1.
~tailed DesçriPtion With reference to the Figs., an adsorbent vessel 10 in accordance with the present invention is illustrated.
Adsorbent vessel 10 has an interior 12 to contain a zeolite adsorbent for use in fractionating oxygen from air. As would bP appreciated by those skilled in the art, adsorbent vessel 10 could be shaped wider and flatter than the form illustrated in complete dependence upon process considerations and the amount of adsorbent to be utilized.
A pair of opposed inlet and outlet distributors 14 and 16 are provided at openings 18 and 20 at the ends of adsorbent vessel 10 and are held in place in a manner well known in the art. Both inlet and outlet flow distributors 14 and 16 are provided with end walls 22 and 24 and sidewalls 26 and 28 of cylindrical configuration projecting into openings 18 and 20.
End walls 22 ana 24 are provided with inlet and outlet openings 30 and 32 defined ~in end walls 22 and 24 and sidewalls 26 and 28 are provided with a plurality of ~lit-like apertures 34 and ~6. Outlet distributor 16 is provided with an opposed end wall 37 connected to sidewall 28 thereof so that process gasses are constrained to pass through slit-like apertures 36 of sidewall 28. Inlet distributor 14 is not provided with such an opp^ _d end wall and as such constitutes a ~odified form of a flow distributor for purposes that will become apparent.
Inlet and outlet pipes 38 and 40 pass through inlet and outlet openings 30 and 32 of end walls 22 and 24 and are welded :
- 6 - 2~22~5 to end walls 22 and 24. Pressurized air enters interior 12 of adsorbent vessel 10 via an inlet pipe 38 for adsorption of nitrogen within the zeolite adsorbent that can be contained within adsorbent vessel 10. The zeolite adsorbent, not illustrated, is contained and supported within adsorbent vessel 10 between perforate supporting structures 42 and 44, well known in the art, that allow passage of the process gases to and from the adsorbPnt. The perforate supporting structures allow a sufficient volume to be created within interior 12 of adsorbent vessel 10 above and below the zeolite adsorbent to allow for the accumulation and distribution of process gases~
The adsorption of nitrogen within the zeolite adsorbent produces a product o~ygen gas essentially free of the nitrogen which is discharged from adsorbent vessel 10 via outlet conduit 40. As would be known to those skilled in the art, additional process streams such as purge, backfill and equali~ation gases also flo~ to and from vessel 10 through outlet conduit 40.
During regeneration, reduced pressure is applied to inlet conduit 38 to cause adsorbed nitrogen to desorb from the zeolite and ke drawn from adsorbent vessel 10 through inlet conduit 38.
As mentioned previously~ due to heat of adsorption, a cold spot tends to form within the zeolite contained within adsorbent vessel 10 closer to inlet distributor 16 than to outlet distributor 18. In adsorbent vessel 10, the cold spot e~ists within the central, lower one third region of the zeolite contained within the vessel. The reduction in temperature of the zeolite within the cold spot decreases the capacity of zeolite to adsorb nitrogen. In the present invention, the cold spot is heated by an elongated, convective heat e~changer 46 fabricated from a heat conductive material, for instance stainless steel. Heat exchanger 46 is located within the adsorbent vessel so as to e~tend into the cold spot.
7 2~722~
Heat e~changer 46 has a reversing flow path for either the air entering interior 12 of adsorbent vessel lO or desorbed nitrogen passing out of interior 12 of adsorbent vessel 10.
Since the air is much warmer than the cold spot, typically 0 C., but as low as -60 C., the reversing path taken by the entering air tends to raise the temperature of the cold spot.
Additionally, since desorbed nitrogen is approximately 20 C., a good deal warmer than the cold spot, heat tends to transfer to the cold spot from also the outgoing desorbed nitrogen to raise the temperature of the cold spot, and thus, prevent deterioration of the performance of the zeolite adsorbent.
Convective heat e~changer 46 comprises inlet pipe 38, which is sized to project inwardly and is left open to form an inner tube of heat e~changer ~6, an outer tube 48, and an inner end cap 50. Inner end cap 50 is connected to one of the ends of outer tube 48. Outer tube 48 is connected at the other of its ends to cylindrical sidewall 26 of inlet distributor 16.
The resulting structure of heat exchanger 46 has two oppositely directed, lengthwise extending passes formed by inlst pipe 38 and an annular flow area 52 formed between inlet pipe 38 and outer tube 48. For instance, air passing through the pass formed by inlet pipe 38 flows toward and înto the cold spot to heat -the cold spot~ The air then reverses direction at inner end cap 50 and then flows through the pass formed by annular flow area 52. The air then flows into inlet distributer 18 and passes into interaor 12 of vessel lO through slit-like apertures 34 thereof. After passage through slit-like apertures 34, the air reverses direction again in its flow to the adsorbent. The desorbed nitrogen flows along a flow path that is the reverse of that taken by the entering air.
The passes are designed to allow heat to be transferred, through the heat conductive material forming elongated heat e~changer 46, to the ~old spot from the air or desorbed nitrogen during their transverse of the reversinq flow path - B - ~ 072295 defined by the two passes. Practically, this is accomplished by appropriately sizing heat e~changer 46 to e~tend into the cold spot region or slightly past the cold spot region of the adsorbent bed. If necessary, heat e~changer 42 can e~tend the full length of adsorption vessel 10.
Heat e~changer 46 can serve to fully develop the air flow into adsorbent vessel 10 in the event that such flow is not fully developed. In this regard, it is 60metimes necessary to locate tee kittings and bends, through which air flows to the adsorbent vessel, very near the inlet to the adsorbent vessel.
As the air flow changes direction around a bend or through a tee fitting, the ~elocity distribution across the air flow becomes non-uniform or not fully developed. Normally a straight run o~ si~ or more pipe diameters are provided after the tee fitting or bend to allow the air flow to fully develop before entering the adsorbent vessel. When this is not or cannot be done because of other design considerations, the non-uniform velocity distribution across the air flow will cause the air to non-uniformly distribute itself in the adsorbent vessel and thus, the adsorbent. As a result, adsorb~nt will be unequally utilized to decrease the adsorption capability of the adsorption bed.
Convective heat e~changer 46 solves this problem by providing a sufficient straight run of flow for the entering air to fully dPvelop prior to its entry into the adsorbent bed. In this regard, this sufficient straight run is proYided by annular flow area 52. In order to decrease the length of annular flow area 52 and hence, heat e~changer 46, required for such a purpose, flow straighteners such as radially e~tending plates 54 can be provided within annular ~low area 52. In place of plates 54, bundles of open ended pipes could be ir.serted into annular flow area 52.
In the event that in addition to a cold spot problem, a - DM~092591 PATENT
2~722~
flow development problem, as described above, is inherent in the pressure swing adsorption system design, then heat exchanger can be designed to also fully develop the flow of incoming air. As may be appreciated, heat exchanger 46 can be solely designed to solve flow development problems without regard to potential cold spot problems. In any possible embodiment of or use for heat e~changer 46, the flow areas of annular flow area 52 and inlet ~ipe 38 should each be no less than the transverse cross-sectional area of process piping to prevent excessive pressure drops in the process piping. In addition to the foregoing, other possible embodiments of the subject invention could include the use of mo~e than one elongated, convective heat exchangers or an elongated convective heat exchanger having more than two passes. The disadvantage of such embodiments would be the increase in pressure drop produced by the additional passes.
While a preferred embodiment of the invention have been shown and described in detail, it will be readily understood and appreciated by those skilled in the art, that numerous omissions, changes and additions may be made without departing from the spirit and scope of the invention.
Claims (16)
1. In an adsorbent vessel for containing an adsorbent to form an adsorbent bed used in a pressure swing adsorption process wherein a component of a multi-component gas mixture is adsorbed to produce a product gas essentially free of the component, the adsorbent bed is regenerated by desorbing the component from the adsorbent bed, the adsorbent has a deteriorating adsorption capacity at a reduced temperature, and the pressure swing adsorption process produces a cold spot of the reduced temperature within the adsorbent bed, the adsorbent vessel having an inlet through which the multi-component gas mixture and the desorbed component flow, to and from the adsorbent bed, respectively, the improvement comprising:
at least one elongated, convective heat exchanger, fabricated from a heat conductive material, located within the adsorbent vessel so as to extend into the cold spot, and having at least two oppositely directed, lengthwise extending passes;
the at least two oppositely directed, lengthwise extending passes in communication with one another and the inlet such that the multi-component gas mixture and the desorbed component traverse the at least two oppositely directed passes upon entering and leaving the adsorbent vessel and transfer heat to the cold spot and thereby raise cold spot temperature above the reduced temperature and decrease the deterioration of the adsorption capacity of the adsorbent.
at least one elongated, convective heat exchanger, fabricated from a heat conductive material, located within the adsorbent vessel so as to extend into the cold spot, and having at least two oppositely directed, lengthwise extending passes;
the at least two oppositely directed, lengthwise extending passes in communication with one another and the inlet such that the multi-component gas mixture and the desorbed component traverse the at least two oppositely directed passes upon entering and leaving the adsorbent vessel and transfer heat to the cold spot and thereby raise cold spot temperature above the reduced temperature and decrease the deterioration of the adsorption capacity of the adsorbent.
2. The improvement of claim 1, wherein the heat exchanger comprises:
an elongated outer tube projecting into the cold spot;
an inner end cap connected to one end of the outer tube; and an elongated inner tube coaxially extending within the outer tube and sized such that an annular flow area is defined between the inner tube and the outer tube;
one of the at least two passes formed by the annular flow area and the other of the at least two passes formed by the elongated inner tube.
an elongated outer tube projecting into the cold spot;
an inner end cap connected to one end of the outer tube; and an elongated inner tube coaxially extending within the outer tube and sized such that an annular flow area is defined between the inner tube and the outer tube;
one of the at least two passes formed by the annular flow area and the other of the at least two passes formed by the elongated inner tube.
3. The improvement of claim 2, wherein the inner tube and the annular flow area defined between the outer tube and the inner tube have flow areas of no less than process piping of the pressure swing adsorption process.
4. The improvement of claim 3, wherein:
the inner and outer tubes are each of cylindrical configuration; and the inner end cap is of hemispherical configuration.
the inner and outer tubes are each of cylindrical configuration; and the inner end cap is of hemispherical configuration.
5. In an adsorbent vessel for containing an adsorbent to form an adsorbent bed used in a pressure swing adsorption process wherein a component of a multi-component gas mixture is adsorbed to produce a product gas essentially free of the component and the multi-component gas mixture is supplied to the adsorbent vessel under conditions of non-fully developed flow, the adsorbent vessel having, an inlet through which the non-fully developed flow of the multi-component gas mixture enters the adsorbent vessel, the improvement comprising:
an elongated flow developer, located within the adsorbent vessel and having two oppositely directed, lengthwise extending passes in communication with one another and the inlet such that the multi-component gas traverses the two passes before entering the interior of the adsorbent vessel;
one of the two passes, through which the multi-component gas flows just prior to entering the adsorbent vessel, configured to provide an unobstructed straight run having a length sufficient to fully develop the flow of the multi-component gas mixture.
an elongated flow developer, located within the adsorbent vessel and having two oppositely directed, lengthwise extending passes in communication with one another and the inlet such that the multi-component gas traverses the two passes before entering the interior of the adsorbent vessel;
one of the two passes, through which the multi-component gas flows just prior to entering the adsorbent vessel, configured to provide an unobstructed straight run having a length sufficient to fully develop the flow of the multi-component gas mixture.
6. The improvement of claim 5, further comprising flow straightening means located within the one of the at least two passes for straightening the flow of the multi-component gas mixture and thereby decreasing the sufficient length that would otherwise be required for the flow of the multi-component gas mixture to fully develop.
7. The improvement of claim 5, wherein the elongated flow developer comprises:
an elongated outer tube;
an inner end cap connected to one end of the outer tube; and an elongated inner tube coaxially extending within the outer tube and sized such that an annular flow area is defined between the inner tube and the outer tube;
one of the two passes formed by the annular flow area and the other of the two passes formed by the elongated inner tube.
an elongated outer tube;
an inner end cap connected to one end of the outer tube; and an elongated inner tube coaxially extending within the outer tube and sized such that an annular flow area is defined between the inner tube and the outer tube;
one of the two passes formed by the annular flow area and the other of the two passes formed by the elongated inner tube.
8. The improvement of claim 7, further comprising flow straightening means located within the annular flow area for straightening the flow of the multi-component gas mixture and thereby decreasing the sufficient length that would otherwise be required for the flow of the multi-component gas mixture to fully develop.
9. The improvement of claim 8, wherein the inner tube and the annular area defined between the outer tube and the inner tube have flow areas of no less than process piping of the pressure swing adsorption process.
10. The improvement of claim 9, wherein:
the inner and outer tubes at each of cylindrical configuration; and the inner end cap is of hemispherical configuration.
the inner and outer tubes at each of cylindrical configuration; and the inner end cap is of hemispherical configuration.
11. In an adsorbent vessel for containing an adsorbent to form an adsorbent bed used in a pressure swing adsorption process wherein a component of a multi-component gas mixture is adsorbed to produce a product gas essentially free of the component, the adsorbent bed is regenerated by desorbing the component from the adsorbent bed, the adsorbent has a deteriorating adsorption capacity at a reduced temperature, the multi-component gas mixture is supplied to the adsorbent vessel under conditions of non-fully developed flow, and the pressure swing adsorption process produces a cold spot of the reduced temperature within the adsorbent bed, the adsorbent vessel having, an inlet through which the non-fully developed flow of the multi-component gas mixture and the desorbed component flow, to and from the adsorbent bed, respectively, the improvement comprising:
at least one elongated, convective heat exchanger, fabricated from a heat conductive material, located within the adsorbent vessel so as to extend into the cold spot, and having at least two oppositely directed, lengthwise extending passes;
the at least two oppositely directed, lengthwise extending passes in communication with one another and the inlet such that the multi-component gas mixture and the desorbed component traverse the at least two oppositely directed passes upon entering and leaving the adsorbent bed and transfer heat to the cold spot and thereby raise cold spot temperature above the reduced temperature and decrease the deterioration of the adsorbent capacity of the adsorbent; and one of the at least two passes, through which the multi-component gas flows just prior to entering the adsorbent vessel, configured to provide a straight run having a length sufficient to fully develop the flow of the multi-component gas mixture.
at least one elongated, convective heat exchanger, fabricated from a heat conductive material, located within the adsorbent vessel so as to extend into the cold spot, and having at least two oppositely directed, lengthwise extending passes;
the at least two oppositely directed, lengthwise extending passes in communication with one another and the inlet such that the multi-component gas mixture and the desorbed component traverse the at least two oppositely directed passes upon entering and leaving the adsorbent bed and transfer heat to the cold spot and thereby raise cold spot temperature above the reduced temperature and decrease the deterioration of the adsorbent capacity of the adsorbent; and one of the at least two passes, through which the multi-component gas flows just prior to entering the adsorbent vessel, configured to provide a straight run having a length sufficient to fully develop the flow of the multi-component gas mixture.
12. The improvement of claim 11, further comprising flow straightening means located within the one of the at least two passes for straightening the flow of the multi-component gas mixture and thereby decreasing the sufficient length that would otherwise be required to fully develop the flow of the multi-component gas mixture.
13. The improvement of claim 11, the at least one elongated heat exchanger comprises:
an elongated outer tube projecting into the cold spot;
an inner end cap connected to one end of the outer tube; and an elongated inner tube coaxially extending within the outer tube and sized such that an annular flow area is defined between the inner tube and the outer tube;
one of the at least two passes formed by the annular flow area and the other of the at least two passes formed by the elongated inner tube.
an elongated outer tube projecting into the cold spot;
an inner end cap connected to one end of the outer tube; and an elongated inner tube coaxially extending within the outer tube and sized such that an annular flow area is defined between the inner tube and the outer tube;
one of the at least two passes formed by the annular flow area and the other of the at least two passes formed by the elongated inner tube.
14. The improvement of claim 13, further comprising flow straightening means located within the annular flow area to decrease the sufficient length that would otherwise be required to straighten the flow of the multi-component gas mixture.
15. The improvement of claim 14, wherein the inner tube and the annular area defined between the outer tube and the inner tube have flow areas of no less than process piping of the pressure swing adsorption process.
16. The improvement of claim 15. wherein:
the inner and outer tubes are each of cylindrical configuration; and the inner end cap is of hemispherical configuration.
the inner and outer tubes are each of cylindrical configuration; and the inner end cap is of hemispherical configuration.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/765,609 US5160355A (en) | 1991-09-25 | 1991-09-25 | Adsorbent vessel having a convective heat exchanger and flow developer |
| US07/765,609 | 1991-09-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2072295A1 true CA2072295A1 (en) | 1993-03-26 |
Family
ID=25073999
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002072295A Abandoned CA2072295A1 (en) | 1991-09-25 | 1992-06-25 | Adsorbent vessel having a convective heat exchanger and flow developer |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US5160355A (en) |
| EP (1) | EP0534657A1 (en) |
| JP (1) | JPH0639231A (en) |
| AU (1) | AU641866B2 (en) |
| CA (1) | CA2072295A1 (en) |
| NZ (1) | NZ243122A (en) |
| TR (1) | TR26447A (en) |
| TW (1) | TW221980B (en) |
| ZA (1) | ZA925021B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4119660C2 (en) * | 1991-06-14 | 1994-03-31 | Draegerwerk Ag | Air cleaning cartridge for a respirator with an insert |
| DE4243816A1 (en) * | 1992-12-23 | 1994-06-30 | Zeolith Tech | Sorbent cartridge |
| GB2280386A (en) * | 1993-07-29 | 1995-02-01 | Boc Group Plc | Vessel baffle arrangement |
| US5453112A (en) * | 1994-02-02 | 1995-09-26 | Praxair Technology, Inc. | Pressure swing adsorption heat recovery |
| US7881390B2 (en) | 2004-12-01 | 2011-02-01 | Intel Corporation | Increased discrete point processing in an OFDM communication system |
| US7491259B2 (en) * | 2006-05-09 | 2009-02-17 | Equistar Chemicals, Lp | Residence time distribution method and apparatus for operating a curvilinear pressure vessel where transport phenomena take place |
| US7531024B2 (en) * | 2006-05-17 | 2009-05-12 | Equistar Chemicals, Lp | Plug-flow method and apparatus for operating a curvilinear pressure vessel where transport phenomena occur |
| US8500884B2 (en) | 2010-09-27 | 2013-08-06 | Uop Llc | Vessel and process pertaining to an impermeable impingement plate |
| FR2966574B1 (en) * | 2010-10-20 | 2012-12-07 | Coldway | THERMO-CHEMICAL SYSTEM WITH MODULAR CONNECTION |
| CN106043961A (en) * | 2016-08-15 | 2016-10-26 | 安徽翼迈科技股份有限公司 | Two-component epoxy adhesive storage device |
Family Cites Families (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3258899A (en) * | 1962-02-06 | 1966-07-05 | Puregas Equipment Corp | Apparatus for fractionating gaseous mixtures |
| US3734293A (en) * | 1970-03-04 | 1973-05-22 | Air Prod & Chem | Thermoelectric adsorber |
| US3800507A (en) * | 1970-06-23 | 1974-04-02 | Us Navy | Low pressure air dehydrator |
| US3735563A (en) * | 1971-11-04 | 1973-05-29 | C Adams | Regenerating desiccator |
| US3917458A (en) * | 1972-07-21 | 1975-11-04 | Nicoll Jr Frank S | Gas filtration system employing a filtration screen of particulate solids |
| US4093429A (en) * | 1975-12-19 | 1978-06-06 | General Electric Company | Gas separation system |
| NL7610120A (en) * | 1976-09-12 | 1978-03-14 | Droogtech | Pressure vessel for drying compressed air by heat exchange - has only one end cover, facilitating production, inspection and assembly |
| DE7727993U1 (en) * | 1977-09-09 | 1978-02-16 | Bauer - Kompressoren Heinz Bauer, 8000 Muenchen | FILTER CARTRIDGE |
| US4162146A (en) * | 1977-12-14 | 1979-07-24 | Pall Corporation | Multi-chamber adsorbent gas fractionator with non-jamming effluent flow control valve |
| US4312640A (en) * | 1979-03-12 | 1982-01-26 | Pall Corporation | Heat-reactivatable adsorbent gas fractionator and process |
| US4322223A (en) * | 1979-03-30 | 1982-03-30 | Pall Corporation | Adsorbent fractionators with electronic sequence timer cycle control and process |
| US4312641A (en) * | 1979-05-25 | 1982-01-26 | Pall Corporation | Heat-reactivatable adsorbent gas fractionator and process |
| US4552570A (en) * | 1980-05-02 | 1985-11-12 | Pall Corporation | Adsorbent fractionator with automatic cycle control and process |
| FR2541588B1 (en) * | 1983-02-28 | 1985-07-05 | Air Liquide | CONTAINER AND PURIFICATION PLANT BY ADSORPTION |
| US4687573A (en) * | 1984-08-13 | 1987-08-18 | Pall Corporation | Sorbing apparatus |
| JPS6314533U (en) * | 1986-07-15 | 1988-01-30 | ||
| JPH01299622A (en) * | 1988-05-30 | 1989-12-04 | Mitsubishi Electric Corp | Air drying apparatus |
-
1991
- 1991-09-25 US US07/765,609 patent/US5160355A/en not_active Expired - Fee Related
-
1992
- 1992-06-12 NZ NZ243122A patent/NZ243122A/en unknown
- 1992-06-15 AU AU18268/92A patent/AU641866B2/en not_active Ceased
- 1992-06-25 CA CA002072295A patent/CA2072295A1/en not_active Abandoned
- 1992-07-06 ZA ZA925021A patent/ZA925021B/en unknown
- 1992-07-22 TW TW081105793A patent/TW221980B/zh active
- 1992-09-02 TR TR92/0833A patent/TR26447A/en unknown
- 1992-09-10 JP JP4242122A patent/JPH0639231A/en active Pending
- 1992-09-14 EP EP92308344A patent/EP0534657A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| TW221980B (en) | 1994-04-01 |
| NZ243122A (en) | 1994-11-25 |
| ZA925021B (en) | 1993-03-16 |
| TR26447A (en) | 1995-03-15 |
| US5160355A (en) | 1992-11-03 |
| AU641866B2 (en) | 1993-09-30 |
| AU1826892A (en) | 1993-04-01 |
| EP0534657A1 (en) | 1993-03-31 |
| JPH0639231A (en) | 1994-02-15 |
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