US3581475A

US3581475A - Variable heat-exchange system

Info

Publication number: US3581475A
Application number: US813435A
Authority: US
Inventors: Robert A Sauder
Original assignee: Sauder Tank Co Inc
Current assignee: Sauder Tank Co Inc
Priority date: 1969-04-04
Filing date: 1969-04-04
Publication date: 1971-06-01
Anticipated expiration: 1988-06-01

Abstract

A heat-exchange system involving heat-exchange coils adapted to be immersed in a body of liquid to effect heat exchange through the coils between the liquid and the fluid flowing through the coils. The heat-exchange coils are covered by an inverted trough which is open at the bottom only and which is provided with a means for introducing a gas into the trough. Gas can be introduced into the trough, therefore, to displace the liquid, such that the heat exchange is now between the gas which surrounds the coils and the fluid flowing within the coils.

Description

United States Patent [72] Inventor Robert A. Sauder [56] References Cited [21] A l N 53 x;? Kans- UNITED STATES PATENTS pp o. g i [22] Filed Apt 4,1969 3,327,772 6/1967 Kodalra 165/61 [45] Patented June 1, 1971 Primary ExaminerCharles Sukalo [73] Assignee Sauder Tank Company, Inc. Attorney-William S. Dorman Emporia, Kans.

ABSTRACT: A heatexchange system involving heatexchange coils adapted to be immersed in a body of liquid to effect heat exchange through the coils between the liquid and [54] yfl i 'fix SYSTEM the fluid flowing through the coils.v The heat-exchange coils rawmg are covered by an inverted trough which is open at the bottom [52] U.S. Cl 55/269, only and which is provided with a means for introducing a gas 165/1, 165/66, 165/96 into the trough. Gas can be introduced into the trough, there- [51 Int. Cl BOld 51/00 fore, to displace the liquid, such that the heat exchange is now [50] Field of Search 165/1, 2, between the gas which surrounds the coils and the fluid flowing within the coils.

PATENI'EUJUH I III 3,581,475

SHEET 1 BF 3 36 7 52 f ,38 I I I I I I I B as l? E 29 l0 58 62 v5'2 I II II .52

J 68 FROM 70 T TO CQLD WELL STREAM SEPARATOR 52/ II I I I T0 PIPE LINE FIG. FROM COLD SEPARATOR ROBERT A. SAUDER 2 INVENTOR.

ATTORNEY PATENEUJUM H97! 7 3.581.475

" 'SHEET 2 o 3 FIG. 3

ROBERT A. SAUDER IN'VENTOR.

wwam J. Am

ATTORNEY PATEN I'E-D JUN 1 Ian saw 3 or 3 ROBERT'A. SAUDER IN VENTOR.

ATTORNEY VAlllllABLE HEAT-EXCHANGE SYSTEM The present invention relates to an improved system of heat transfer and, more particularly, to a system for varying the heat transfer between a body of liquid which is adapted to selectively surround the coils of a heat exchanger or to be displaced therefrom so as to provide, in the first instance, a liquid'fluid heat transfer and in the second instance a gas'fiuid heat transfer.

in the past, where it has been desired to vary the amount of heat transferred to a gas stream, for example, heat-exchange coils carrying the gas may be embedded in a bath of hot liquid. One method of controlling the amount of heat transferred is to vary the temperature of the bath; obviously, such a method would be slow and somewhat ineffective. Another method would be to bypass variable quantities of gas around the heatexchange coil; however, this method requires additional piping with attendant increased costs, etc.

I It is a principal object of the present invention to provide an improved heat-transfer system which is simple in operation and relatively inexpensive to construct and maintain.

It is a further object of the present invention to provide a variable heat-transfer system where, under one condition of operation, the heat-transfer medium surrounding the coils is liquid and, under another condition of operation, the heattransfer medium surrounding the coils is gaseous with control means for changing the heat-exchange medium instantly from gas to liquid and vice versa.

Other and further objects and advantageous features of the present invention will hereinafter more fully appear in connection with a detailed description of the drawings in which:

FIG. 1 is a plan view of one embodiment of the present invention showing the heat-exchanger assembly in the form of a double-coil heat exchanger;

FIG. 2 is a front elevation of the heat-exchange assembly shown in lFlG. 3;

FIG. 3 is a partial sectional view through a gas-treating apparatus employing the heat-exchange assembly shown in FIGS. )1 and 2;

FIG. 4 is a side elevation of a gas-treating apparatus, with certain internal portions shown in dotted lines, employing two heat-exchange assemblies, each of the single-coil type, and adapted to treat two separate gas streams; and

H6. 5 is an end elevation of the gas-treating apparatus shown in MG. 41.

Referring to the drawings in detail, the heat-exchanger assembly w shown in FlGS. l and 2 is supported within a vessel 12 (see now PEG. 3) containing a quantity of water M or other suitable liquid. Supported on the vessel 12 are a horizontal cold separator (high-pressure separator) 16 and a vertical low pressure separator 18. The cold separator 16 is supported on the vessel 12 in such a manner that its bottom may contact the water M within the vessel 12. The upper level of the water is variable, as will be explained hereinafter, and is indicated by the line 2i). The water M is heated by a horizontal furnace or combustion tube 22 in any conventional manner.

As best shown in FIGS. l and 2, the heat exchanger is formed by a series of horizontal pipes of relatively smaller diameter concentrically disposed within a series of horizontal pipes of relatively larger diameter so as to form a central passageway and an annular passageway; that is, inner pipe 24 is concentrically arranged within outer pipe 26. The outer diameter of the inner pipe 2a is somewhat less than the inner diameter of the outer pipe 26 so as to form an annular space between the two pipes. A plug or collar 28 serves to support the inner pipe 24 concentrically with respect to the outer pipe 26; this plug 28 also serves to seal off the annular space between the two pipes at the forward end of the heat exchanger. A similar plug or collar 30 is located towards the rear end of the heat exchanger to support the other end of the pipe 24 concentrically with respect to the outer pipe 26 and also for the purpose of sealing the other end of the annular space.

Similarly, horizontal pipes 32, M, 36, 38 and lb of relatively smaller diameter are concentrically supported within

horizontal pipes

42, 44, 46, 48 and 50, respectively, of relatively larger diameter. The resulting annular spaces are sealed by the plugs or

collars

52, 52, etc.

As best shown in FIG. 2, the tube assemblies are staggered so as to form two horizontal rows vertically spaced from each other. Thus, the

pipes

26, 44 and 48 are in the lower row and the pipes 42, &6 and 50 are in the upper row. The open adjacent ends of the inner pipes are connected by means of U shaped pipes 54, as best shown in FIG. 1. The annular space between the pipe 24 and the pipe 26 communicates with the annular space between the pipe 32 and the pipe 42 by means of the short interconnecting pipe 56. The annular space between the pipe 32 and the pipe communicates with the annular space between the pipe 34 and the pipe 44 by means of the short pipe 58. Successive annular spaces are interconnected by means of the short pipes (all, 62 and 64 as shown in FIG. 1.

As will appear from the above, a continuous central passageway is provided through the interiors of the

smaller pipes

24, 32, M, 36, 38 and 40 in succession, by virtue of the U-shaped connectors 54. Also, a continuous annular passageway is provided in series around the above mentioned pipes by virtue of the annular spaces created and through the interconnecting

short pipes

56, 58, 60, 62 and 64. Access to one end of the closed annular passageway is provided by the short vertical riser 66 which connects with the forward end of the pipe 26 leading to the annular space between the pipe 24 and the pipe 26. Access to the other end of the continuous annular passageway is provided by the short horizontal connector 68 which connects with the forward end of the pipe 50 and which communicates with the annular space between the pipe 40 and the pipe 50. Access to the central passageway is achieved simply through the forward openings in the

pipes

24 and 50.

The heat-exchanger assembly 10 is provided with a front plate 70 to which is connected an inverted trough 72. The trough 72 is adapted to surround the heat-exchange tubes. The trough 72 is closed along all the vertical sides and across the top and is open only at the bottom. An inlet pipe 74 communicates with the upper rear end of the trough to permit air to be introduced to or withdrawn from the inverted trough 72.

Now considering FIGS. 1 and 2 together with FIG. 3, the well stream from an essentially gas-producing well (not shown) enters the short vertical pipe 66 and passes into the continuous annular passageway between the inner and outer pipes. The well stream passes out of the annular area and into a vertical pipe 76 which connects at its lower end (in any conventional manner, not shown) with the short horizontal pipe 68 at the other end of the annular passageway. The well stream flows upwardly in the pipe 76, horizontally to the left in the interconnecting pipe 78, downwardly at an angle through the interconnecting pipe 80, and into the cold separator 16. A choke or expansion device (not shown) is located at or near the inlet 82 to the vessel 16 for the purpose of creating the well-known pressure drop as the well stream enters the vessel 116. A temperature-sensing device 84 ("the details of which are not shown) is located within the pipe b ll so as to sense the temperature of the well stream immediately prior to entering the vessel 16. A three-way valve 86 (the details of which are not shown) is connected to the temperature-sensing device 8 in such a manner that the position of the valve 86 is varied in accordance with the temperature sensed. The valve 86 connects with a source of air (not shown) and also with the atmosphere. A third port on the valve 86 connects with a horizontal pipe 8% which, in turn, connects with a vertical pipe 90, which in turn connects with the pipe 74 that leads into the inverted trough 72.

The relationships among the valve 816, temperature-sensing device M and

pipes

90 and 74% is such that, as the temperature rises above a predetermined value, air will be passed into the inverted trough 72 to displace hot water therefrom so as to diminish the heat transfer from the hot water bath M and incoming well stream flowing through the annular passageway;

conversely, as the temperature falls below a predetermined value, air will be bled from the inverted trough 72 through

pipes

74 and 90 and through the valve 86 to the atmosphere. Since the space above the water line 20 will be at atmospheric pressure, it is possible to fill the trough 74 completely with water. Preferably, however, the control arrangement is such that air supply or bleed, as the case may be, will cease as soon as the indicated temperature is achieved at the sensor 84 such that trough 72 may be only partially filled with water.

Gas 36 the cold separator 16 passes upwardly through the short vertical pipe 92, horizontally towards the right through the interconnecting pipe 94, downwardly through the interconnecting pipe 96 and into the pipe 40 through appropriate elbows, etc. The'gas entering the pipe 41) passes into the central passageway of the heat-exchanger tubes and discharges from the pipe 24 to be sent to the pipe line or other point of use.

FIGS. 4 and show a heat-exchange arrangement adapted to handle the gas production from two separate wells. Each incoming well stream, therefore, passes through a separate heatexchange assembly which as will also hereinafter appear, is of the single-coil type as opposed to the double-coil type shown in FIGS. 1 and 2.

The structure shown in FIGS. 4 and 5 includes a vertically extending rectangular vessel 100 which is adapted to hold a quantity of water 102. The highest water level is indicated by the dotted line 104 and the lowest water level is indicated by the dotted line 106. That is, when both heat-exchanger troughs, as will hereinafter appear, are filled with air, the water level will be at line 104; conversely, when both heatexchanger troughs are filled with water, the water level in the vessel 102 will be at the line 106. As was the case in connection with FIG. 3, the upper portion of the vessel 102 will be at atmospheric pressure.

At either side of the vessel I00, low temperature (high pressure)

separators

108 and 110 will be mounted in any conventional manner. Portions of these separators will project into the vessel 100 so as to contact a portion of the hot water therein. A suitable combustion unit 112 will be provided in the lower interior of the vessel 100 so as to heat the water 102. The combustion furnace will be provided with an external stack 114.

The heat exchangers and the controls therefor are shown semidiagrammatically. Lower heat exchanger 116 is shown having an inlet pipe 118 and an outlet pipe 120. The central dotted line portions represent parallel horizontal pipes connected at their adjacent ends by U-shaped connectors in a manner similar for that shown in FIGS. 1 and 2. Thus, heat exchanger 1 16 would be provided with a total of six horizontal portions extending for the length of the heat exchanger 116. The heat exchanger 116 is also provided with an inverted trough 122 closed on all sides except for the bottom which is open. The trough 122 is also provided with an inlet opening 124 similar to the inlet pipe 74 shown in FIGS. 1 and 2. A conduit 126 connects between the inlet 124 and a control device 128 for the purpose of introducing air to, or exhausting air from, the inverted trough 122. A detailed description of the control device 128 is considered to be unnecessary; it should suffice to point out that the control device 128 includes a means for sensing the temperature within the vessel 110 and a valve (preferably a three-way valve) capable of connecting the line 126 to a source of air pressure or to the atmosphere in response to an increase or decrease, respectively, of the temperature within the vessel 110.

A second heat-exchanger assembly 130 is mounted within the vessel above the heat exchange assembly 116. The heatexchange assembly 130 is essentially identical to the heatexchange assembly 116 described above and includes an inlet pipe 132, an outlet pipe 134, six horizontal lengths of pipe within the heat exchanger connected at their adjacent ends by U-shaped connectors as represented by the dotted line arrangement, an inverted trough 135, an inlet port 136 connected by means of conduit 138 to the control device 1 mounted on the separator 1118. The relationship between the inlet 136, the conduit 138 and the control device 140 is the same as that described above in connection with the corresponding description of inlet 124, conduit 126 and control device 128.

The operation of the device shown in FIGS. 4 and 5 will now be described. The well stream from a first well can enter the heat exchanger 116 through the inlet pipe 118. The well stream makes six passes through the heat exchanger 116 and then passes upwardly through the pipe into the low-temperature separator 110. A choke (not shown) is located in the vessel 110 downstream of the inlet 142 where the pipe 121) connects with the vessel 110. This choke allows the well stream to expand somewhat into the vessel 110 thereby lowering the gas temperature and pressure in a well-known and conventional manner. The gas will leave the vessel 110 by means of the conduit 144 for subsequent treatment of the gas stream.

A well stream from a second well enters the pipe 132 and passes into the heat exchanger making six horizontal passes therethrough emerging from the pipe 134 after which the gas passes into the vessel 108. The vessel 108 will also be provided with a choke 146 which is downstream of the connection between the pipe 134 and the vessel 108 for the purpose of reducing the temperature and pressure of the well stream. The vessel 108 will also be provided with an outlet (not shown) for directing the gas to subsequent treatment.

If the temperature within the vessel 110 rises above a predetermined value as determined by the control device 128, the latter will cause air under pressure to be directed through the conduit 126 and through the inlet 124 into the inverted trough 122 thereby displacing water from the inverted trough and cutting down on the heat transfer between the gas flowing inside the heat exchanger tubes and the water 102 within the vessel 100. Conversely, if the temperature within the vessel 110 falls below a predetermined value as determined by the control device 128, the latter will connect the conduit 126 to the atmosphere so as to bleed air from the inverted trough 122 thereby allowing hot water to enter the heat exchanger 116 to increase the heat transfer effect between the gas flowing in the heat exchanger 116 and the hot water 102.

The manner of introducing air into, and bleeding air from, the inverted trough for heat exchanger 1311 is substantially the same as that set forth above in connection with heat exchanger 116. That is, the control device senses the temperature within the vessel 1118 and, accordingly, forces air into or out of the inverted trough 135.

It should be apparent that the controls for the heat exchangers 116 and 1311 are separate and individual; thus, the inverted trough 122 could be full of water while the inverted trough 135 could be full of air, or vice versa. Likewise, both inverted troughs could be filled with air at the same time or they could be both filled with water at the same time.

Whereas the dual-coil heat exchanger shown in FIGS. 1 to 3 describes the influent as passing into the annular area first and later through the central area, it should be obvious that the influent could be introduced to the central area first and to the annular area thereafter, if it appeared necessary or desirable to do so.

The heat exchanger shown in FIGS. 1, 2 and 3 on the one hand, and the heat exchangers shown in FIGS. 4 and 5 on the other hand, operate on the same principle; that is, the heatexchange coils are adapted to be immersed in a liquid, such as hot water. The heat transfer between this liquid and the gas flowing through the pipes is at a maximum when the heat exchange coils are totally immersed in the liquid. Conversely, the heat exchange is at a minimum when the heat exchange coils are no longer in contact with the hot water; i.e. when air is introduced into the inverted

troughs

72, 122 or 135 to force the water out of the troughs.

Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention. For example, although the variable heat transfer has been described above in terms of a variation in the heat added to the fluid flowing through the heat exchanger, it should be obvious that this variable heat transfer could take place under conditions where it would be desirable to cool, or remove heat from, said fluid.

What I claim is:

1. A method of varying the heat transfer between a fluid flowing through a heating coil and a liquid in which the heating coil is immersed which comprises surrounding the heating coil within an inverted trough open at the bottom only, and selectively introducing and withdrawing a gaseous medium into and from said inverted trough to alternatively displace and permit entry of, respectively, the liquid from and into said trough.

2. A method as set forth in claim 1 wherein the heating coil is divided into a continuous closed central zone and a continuous closed annular zone concentric with said central zone and wherein said fluid is conducted through said heating coil through both zones countercurrently.

3. Apparatus for varying the heat-transfer effect between a fluid flowing in a heating coil and a liquid surrounding the heating coil comprising a vessel containing a quantity of said liquid, means mounting said heating coil in said vessel below the upper level of said liquid, means for introducing said fluid into one end of said heating coil, means for withdrawing said fluid from the opposite end of said heating coil, an inverted trough mounted in said vessel surrounding said heating coil, said trough being closed along the top and along all sides thereof except for the bottom, means responsive to the temperature of the fluid leaving said heating coil for selectively introducing gaseous medium into said inverted trough and withdrawing said gaseous medium therefrom whereby said liquid is forced outwardly from said inverted trough in response to a first temperature condition and allowed to enter said trough under a second temperature condition.

4. Apparatus as set forth in claim 3 wherein said heating coil is formed of a plurality of concentric pipes, one set of concentric pipes being supported within a second set of concentric pipes, the outer diameter of said first set of concentric pipes being smaller than the inner diameter of the second set of concentric pipes so as to form annular spaces between said two sets of pipes, means connecting the individual annular spaces in series to form a continuous annular passageway, means connecting the resulting central spaces together to form a continuous central passageway, means for flowing said fluid through said heating coil countercurrently through both said passageways.

5. Apparatus as set forth in claim 4 wherein said fluid flowing through said heating coil is a well stream from a gasproducing well and wherein said well stream is passed through a low-temperature separator between its two passes through the two passageways.

6. Apparatus as set forth in claim 4 wherein said means for flowing said fluid through said heating coil countercurrently through both said passageways includes means for introducing a well stream from a gas-producing well into one end of the annular passageway of said heating coil, means for withdrawing said well stream from the other end of said annular passageway, a cold-temperature separator, means for introducing the well stream withdrawn from said annular passageway into said cold-temperature separator wherein said well stream is allowed to expand to a lower pressure and lower temperature, means for withdrawing gas from said cold temperature separator, means for introducing the gas withdrawn from said coldtemperature separator into one end of said central passageway of said heating coil, and means for withdrawing gas from the other end of said central passageway of said heat exchanger.

7. Apparatus as set forth in claim 4 wherein said means for flowing said fluid through said heating coil countercurrently through both said passageways includes means for introducing a well stream from a fgas-producing well into one end of the central passageway o sax heating coil, means for withdrawing said well stream from the other end of said central passageway, a cold-temperature separator, means for introducing the well stream withdrawn from said central passageway into said cold temperature separator wherein said well stream is allowed to expand to a lower pressure and lower temperature, means for withdrawing gas from said cold-temperature separator, means for introducing the gas withdrawn from said cold-temperature separator into one end of said annular passageway of said heating coil, and means for withdrawing gas from the other end of said annular passageway of said heat exchanger.

Claims

5. Apparatus as set forth in claim 4 wherein said fluid flowing through said heating coil is a well stream from a gas-producing well and wherein said well stream is passed through a low-temperature separator between its two passes through the two passageways.

6. Apparatus as set forth in claim 4 wherein said means for flowing said fluid through said heating coil countercurrently through both said passageways includes means for introducing a well stream from a gas-producing well into one end of the annular passageway of said heating coil, means for withdrawing said well stream from the other end of said annular passageway, a cold-temperature separator, means for introducing the well stream withdrawn from said annular passageway into said cold-temperature separator wherein said well stream is allowed to expand to a lower pressure and lower temperature, means for withdrawing gas from said cold temperature separator, means for introducing the gas withdrawn from said cold-temperature separator into one end of said central passageway of said heating coil, and means for withdrawing gas from the other end of said central passageway of said heat exchanger.

7. Apparatus as set forth in claim 4 wherein said means for flowing said fluid through said heating coil countercurrently through both said passageways includes means for introducing a well stream from a gas-producing well into one end of the central passageway of said heating coil, means for withdrawing said well stream from the other end of said central passageway, a cold-temperature separator, means for introducing the well stream withdrawn from said central passageway into said cold temperature separator wherein said well stream is allowed to expand to a lower pressure and lower temperature, means for withdrawing gas from said cold-temperature separator, means for introducing the gas withdrawn from said cold-temperature separator into one end of said annular passageway of said heating coil, and means for withdrawing gas from the other end of said annular passageway of said heat exchanger.