CA1249583A - Counterflow tubular heat exchanger having center pipe construction - Google Patents
Counterflow tubular heat exchanger having center pipe constructionInfo
- Publication number
- CA1249583A CA1249583A CA000451259A CA451259A CA1249583A CA 1249583 A CA1249583 A CA 1249583A CA 000451259 A CA000451259 A CA 000451259A CA 451259 A CA451259 A CA 451259A CA 1249583 A CA1249583 A CA 1249583A
- Authority
- CA
- Canada
- Prior art keywords
- attached
- heat exchanger
- head
- shell
- inner shell
- 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.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D7/16—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
- F28D7/163—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation with conduit assemblies having a particular shape, e.g. square or annular; with assemblies of conduits having different geometrical features; with multiple groups of conduits connected in series or parallel and arranged inside common casing
- F28D7/1669—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation with conduit assemblies having a particular shape, e.g. square or annular; with assemblies of conduits having different geometrical features; with multiple groups of conduits connected in series or parallel and arranged inside common casing the conduit assemblies having an annular shape; the conduits being assembled around a central distribution tube
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F2280/00—Mounting arrangements; Arrangements for facilitating assembling or disassembling of heat exchanger parts
- F28F2280/02—Removable elements
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Geometry (AREA)
- Thermal Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
ABSTRACT
A tube type counterflow heat exchanger adapted for high temperature service. The heat exchanger contains a tube bundle having a central pipe construction used for intro-ducing a hot inlet gas into the exchanger, so as to minimize the temperature to which the primary pressure boundary shell is exposed and also cause minimal differential thermal contraction of the tube bundle. An annular space containing a thermal sleeve is provided between the center pipe and the tube bundle inner shell for passage of a minor flow of gas therethrough to heat the inner shell and thus minimize the temperature difference existing between the inner shell and the tubes. Any excessive differential expansion which occurs between the inlet end tube sheet and inner shell is accommodated by an expansion joint.
A tube type counterflow heat exchanger adapted for high temperature service. The heat exchanger contains a tube bundle having a central pipe construction used for intro-ducing a hot inlet gas into the exchanger, so as to minimize the temperature to which the primary pressure boundary shell is exposed and also cause minimal differential thermal contraction of the tube bundle. An annular space containing a thermal sleeve is provided between the center pipe and the tube bundle inner shell for passage of a minor flow of gas therethrough to heat the inner shell and thus minimize the temperature difference existing between the inner shell and the tubes. Any excessive differential expansion which occurs between the inlet end tube sheet and inner shell is accommodated by an expansion joint.
Description
:~LZ'~5~3 COUNTERFLOW TUBULAR HEAT EXCHANGER HAVING
CENTER PIPE CONSTRUCTION
_ BACKGROUND OF INVENTION
This invention pertains to a tube type counterflow heat exchanger arranged for operation at elevated temperature and pressure conditions. It particularly pertains to such heat exchanger having an elongated removable center pipe construction for handling a hot gas inlet stream, so as to minimize exposure of the pressure stressed metal walls to the high temperature conditions.
As energy conservation has become increasingly important, particularly in the chemical processing industry, improved tubular type heat exchangers have been developed suitable for ~
high temperature service, such as for inlet gas temperatures above about 1000-F. However, a major problem with such heat exchangers for high temperature service is minimizing the differential thermal expansion between the tube passes and reducing as much as possible those portions of the pressurized boundary walls of the exchanger which are subjected to the higher temperature ~7ithin the unit. To overcome these problems, the heat exchanger configuration of the present invention was developed and it ic principally intended for use in hydro-deal}cylation (HDA) process units to exchange heat between the reactor feedstream and the reactor hot effluent gas stream, so as 5 to provide more reliable and trouble-free operations.
SUMMARY OF INVENTION
The present invention provides an improved tube type counterflow heat exchanger for high temperature service. The heat exchanger unit includes a tube bundle of parallel tubes within an outer pressurizable shell, and contain6 an elongated center pipe for a hot gas inlet stream. The central pipe is arranged in flow communication with the single pass tube bundle and i~ capable of operating at a high tubeside temperature, such as up to about 1250-F., and to minimize exposure of stressed metal parts to high temperature gas flows. More specifically, the heat exchanger comprises a pressurizable outer shell having a head attached at each opposite end, said heat at the inlet end being attached to the shell by a bolted flange type connection;
and the head at the opposite end heing welded to the shell;
multiple parallel tubes provided longitudinally within said outer shell, said tubes being located outwardly from a centrally-located parallel inner shell and sealably connected to a tube sheet at each en~; with the inlet end stationary tube ~heet being also connected to ~aid inl.et head; a central pipe extended longitudinally within 6 aid inner shell so as to provide a narrow annular space between the central pipe and the inner shell; and a metal bellows attached at one end to Eaid inner shell stationary tube sheet and attached at the other end to said inner 6hell, so as to accommodate dif~erential thermal expansion between the stationary tube sheet and the inner shell.
A metal therma~ sleeve is advantageously prov.ided within the annular space between the center pipe and inner ehell and attached to the center pipe to minimize exposure o~ the inner shell to the temperature of the hot inlet gas stream passing through the center pipe. To protect the heat exchanger tubes from the effect of excessive differential temperature, the metal bellows i~ provided between the stationary tubesheet and the lnner shell of the exchanger. Also, the inlet end removable head is made generally conical shaped and has an annular-shaped baffle th~rein arranged to direct the flow of coolsd gas exiting the tubes past the bellows an~ past mo~t of the metal inner surfaces in the end he~d Advantages of the heat exchanger construction provided by the present invention include minimizing the temperature of stressed metal parts exposed to the high primary unit pressure, thus reducing the quantity of expensive steel alloy material required for the exchanger, and also minimizing stresse6 usually caused by differential thermal expansion of the tubes relative to the inner shell.
~2'~3~1~3 BRI EF DESCRI PTI ON OF DR~WI NGS
FIG. 1 shows a longitudinal sectional view of the tube type counterflow heat exchanger constructed according to the present invention.
FIG. 2 is an enlarged partial sectional view ~howing details of the central pipe and thermal sleeve construction for the heat exchanger.
DETAI LED DESCRI PTI ON OF I NVENTI ON
The various features provided by a preferred embodiment of the present invention are generally shown in FIG. 1, in which heat exchanger assembly 10 has an outer pres6urizable shell 12 which i6 flange connected to the tube side inlet and outlet bead as6embly 14 and i~ welded to the shellside outlet head 16.
Multiple parallel tube6 20 are provided in a removable tube bundle 22 within the outer 6hell 12, the tubes being sealably attached at one end to stationary tube sheet 23 and at the - opposite end to floating tubesheet 25. Tube bundle 22 is also provided with an inner cylindrical shell 26 which is flexibly attached to the tube sheet 23 by bellows 40 and is rigidly attached to the floating tube6heet 25. Attached to the removable inlet head assembly 14 i6 a center pipe 30 which i6 attached to flange 13 and i8 provided concentrically within inner shell 26, and extends past the stationary tubesheet 23 to the floating t~b~sh~et 25. The center pipe 30 conduct6 the hot inlet gas directly from the tube 6ide inlet nozzle 13 to the floating head 24 of the heat exchanger bundle 22 from where it flows baak through multiple tubes 20 to head 14. Central pipe 30 is made of a stainle6s steel material suitable for the high temperature service up to about 1250 F., 6uch as AISI Type 347 6 teel.
From the hsat exchanger floating head 24 end, the hot gas then flows back mainly ll:hrough the tubes 20, but a small portion of the hot ga~ is also distributed through an annulus 32 formed between inner shell 26 and a thermal 61eeve 34 attached to the outer surface of center pipe 30. From the floating head 24 end, the small bypass gas stream enters the annular space 32 and pa6ses between the thermal sleeve 34 and the inside diameter of the inner shell 26, and thereby flows parallel to the gas flow~ng through multiple tubes 20. The annulus 32 is of such cross-6ectional area that the small flow of hot bypasR gas therethrough will re6ult in the temperature for inner shell 26 being approximately that of tubes 20, so as to minimize the differential temperature between the inner ~hell 26 and tubes 20 and thereby minimize the difference in thermal growth between shell 26 and the tubes 20. Thus, because a substantially "dead air" space effectively exists in the annular space 32 between the thermal 61eeve 34 and center pipe 30 to provide an insulating gas layer therebetween, the temperature profile along the inner shell 26 6ubstantially matches the temperature profile of the tubes 20.
If desirea, the thermal sleeve 34 can be provided as multiple ~leeves 35 arranged in serie6 and, each attached at one end to center pipe 30, as is shown in FIG. 2.
The center pipe assembly 30 is separately attached to head assembly 1~ and bolted flange 18. By this construction arrangement, the central pipe assembly can be advantageously removed rom within shell 26 of tube bundle 22 of the heat exchanger 10, to permit removal of carbon deposits within passageway 32.
The basic design concept for the heat exahanger of the present invention is to avoid or minimize elevated temperatures for those metal parts subject to the high primary unit pressure, such as above about 500 psig. The utilization of the center pipe 30, which immediately conducts the hot inlet gas stream entering at flange 13 to those parts subjected only to differential pressure 80 that the hot gas i6 cooled immediately by the counteraurrent gas flow exiting from tubes 20, aids in accomplishing this desired result. Thus the gas flow streams are arranged so as to minimiz0 exposure of the pressure stressed ,. ~
,., ~lL2'~9~33 metal walls to the high temperature inlet gas and to expose as much as po~sible of the shell 12 and channel head assembly 14 to the lower temperature proces~ gas stream within the shell and tube side of the exchanger. Also, the heat exchanger i~ ar~anged so as to avoid insofar as possible differing temperatures across the diameter of the exchanger. In addition, the tube sheet bolted joints at 27 and 28 located at opposite ends of tube bundle 22 are designed to accommodate unexpected strains and movements that may occur in the tube bundle 22 dua to rapid temperature changes such as during start-up or shut-down operation of the heat exchanger unit.
To minimize the temperature level6 to which the heat exchanger pres6urized outer 6hell 12 and flow ohannel head assembly 14 are exposed, the hot effluent stream entering the channel head assembly is conducted via center pipe 30 directly to the floating head 24, which serves to isolate the hot gas temperature from the high pressure boundary shell 12 and the boundary channel head assembly 14 of the exchanger. The shell side gas flow enters at nozzle 17 and flows around multiple parallel tubes 20 and then through the annular space 24a around the floating head 24 to exit at centrally located nozzle 19.
This flow pattern tends to keep the temperatures uniform around the inner floating head 24, avoids distortions of flange joint 28, and prevents the shell side outer head lS from overheating due to it~ proximity to the higher temperature floating head 24.
In order to additionally protect the tubes 20 and inner shell 26 from damaging differential temperature stresses during process ~tartup or any upset conditions, a metal bellows expansion -~oint 40 is provided at the channel head assembly end between the inner shell 26 and the fixed tubesheet 23. The cooled gas exiting from the tubes 20 within the head assembly 14, which gas has been lowered in temperature by heat exchange with the feedstream flowing in the shellside, flow~ past the bellows expansion joint 40 and thereby cools the ~oint to a temperature level where reasonable allowable metal stresses can be used in the design of the joint.
Another important feature of the heat exchanger of the invention is the use of an annular channel provided by conical-shaped f~ow baffle 42 located within inlet head assembly 14 and attached at its base to head assembly 14, as shown in FIG. 1.
Baffle 42 serves to direct the flow exiting from tubes 20 towards the inlet point for the reactor hot gas feedstream in the central pipe 30, and then annularly through the annular flow channel ~4 to exit at 15. This gas return flow in the annulus 44 formed by ~affle 42 and the inner wall of head assembly 14 cools this head a~sembly, which restricts the elevated metal temperature to that area immediately adjacent to the hot gas 15 entry pipe 30. Thu6, the gas flow exiting from tubes 20 is deflected by annular baffle 42 through the annular flow channel 44 towards the location of tube side exit 15, which flow path cools the head assembly 14 and minimizes the metal temperature at the point where the hot gas stream enters the heat exchanger.
The tube bundle 22 is preferably made removable from the outer shell 12, which can be accomplished by removal of head assembly 14 at outer bolted type flange 29. The bolted joints at 27 and 28 are ring type joints designed with a clamp ring to enable the use of longer bolts 37 than if the fixed tube sheet and floating cover head 24 were each bolted directly to their ad~acent mating pieces. The use of an oval-shaped ring gasket 38 in these flanged ~oints 27 and 28 permit6 adequate joint rotation to accommodate strains and distortions in the joint, while the additional strain available in the longer bolts 37 aids in maintaining a tight joint during transient as well as normal temperature conditions.
As explained above, to limit the amount of heat transmitted from the hot inlet gas s~tream through nozzle 13 to the pressurized inner shell 26, the center pipe 30 is preferably fitted with a plurality of thermal sleeves 35 extending from pipe ~, ~2'~
free end 30a to a point beyond the internal expansion joint 40, as best shown by FIG. 2. Also, short lengths of tubes or ferrules 21 having an outside diameter slightly smaller than the inside diameter of tubes 20 are preferably provided attached in the floating head end of tubes 20, so as to provide gas pockets at 21a within the tubes 20 to absorb the differences in temperature at this location.
The heat exchanger of this invention is suitable for high temperature service at high pressure, such as for 1000-1300-F
temperature and 500-1000 psig pressure. By using this heat exchanger design configuration, the temperature of the two counterflowing gas streams can be brought close together and even crossed if desired, so as to maximize the heat recovery from the hot gas stream provided by the exchanger. This heat exchanger is typically used for exchanging heat between a feedstream to a reactor entering at connection 17 and the reactor hot effluent stream being passed first through the center pipe assembly 30 and then back through the multiple tubes 20 to heat the feedstream passing through the exchanger shell side and around the tubes to near the reactor inlet temperature, and thereby reduce furnace heating costs for the feedstream.
Although this heat exohanger invention has been described broadly and in terms of a preferred embodiment, it will be understood that design modifications and variations to the exchanger can be made within the spirit and scope of the invention, which is definad by the following claims.
',,~
CENTER PIPE CONSTRUCTION
_ BACKGROUND OF INVENTION
This invention pertains to a tube type counterflow heat exchanger arranged for operation at elevated temperature and pressure conditions. It particularly pertains to such heat exchanger having an elongated removable center pipe construction for handling a hot gas inlet stream, so as to minimize exposure of the pressure stressed metal walls to the high temperature conditions.
As energy conservation has become increasingly important, particularly in the chemical processing industry, improved tubular type heat exchangers have been developed suitable for ~
high temperature service, such as for inlet gas temperatures above about 1000-F. However, a major problem with such heat exchangers for high temperature service is minimizing the differential thermal expansion between the tube passes and reducing as much as possible those portions of the pressurized boundary walls of the exchanger which are subjected to the higher temperature ~7ithin the unit. To overcome these problems, the heat exchanger configuration of the present invention was developed and it ic principally intended for use in hydro-deal}cylation (HDA) process units to exchange heat between the reactor feedstream and the reactor hot effluent gas stream, so as 5 to provide more reliable and trouble-free operations.
SUMMARY OF INVENTION
The present invention provides an improved tube type counterflow heat exchanger for high temperature service. The heat exchanger unit includes a tube bundle of parallel tubes within an outer pressurizable shell, and contain6 an elongated center pipe for a hot gas inlet stream. The central pipe is arranged in flow communication with the single pass tube bundle and i~ capable of operating at a high tubeside temperature, such as up to about 1250-F., and to minimize exposure of stressed metal parts to high temperature gas flows. More specifically, the heat exchanger comprises a pressurizable outer shell having a head attached at each opposite end, said heat at the inlet end being attached to the shell by a bolted flange type connection;
and the head at the opposite end heing welded to the shell;
multiple parallel tubes provided longitudinally within said outer shell, said tubes being located outwardly from a centrally-located parallel inner shell and sealably connected to a tube sheet at each en~; with the inlet end stationary tube ~heet being also connected to ~aid inl.et head; a central pipe extended longitudinally within 6 aid inner shell so as to provide a narrow annular space between the central pipe and the inner shell; and a metal bellows attached at one end to Eaid inner shell stationary tube sheet and attached at the other end to said inner 6hell, so as to accommodate dif~erential thermal expansion between the stationary tube sheet and the inner shell.
A metal therma~ sleeve is advantageously prov.ided within the annular space between the center pipe and inner ehell and attached to the center pipe to minimize exposure o~ the inner shell to the temperature of the hot inlet gas stream passing through the center pipe. To protect the heat exchanger tubes from the effect of excessive differential temperature, the metal bellows i~ provided between the stationary tubesheet and the lnner shell of the exchanger. Also, the inlet end removable head is made generally conical shaped and has an annular-shaped baffle th~rein arranged to direct the flow of coolsd gas exiting the tubes past the bellows an~ past mo~t of the metal inner surfaces in the end he~d Advantages of the heat exchanger construction provided by the present invention include minimizing the temperature of stressed metal parts exposed to the high primary unit pressure, thus reducing the quantity of expensive steel alloy material required for the exchanger, and also minimizing stresse6 usually caused by differential thermal expansion of the tubes relative to the inner shell.
~2'~3~1~3 BRI EF DESCRI PTI ON OF DR~WI NGS
FIG. 1 shows a longitudinal sectional view of the tube type counterflow heat exchanger constructed according to the present invention.
FIG. 2 is an enlarged partial sectional view ~howing details of the central pipe and thermal sleeve construction for the heat exchanger.
DETAI LED DESCRI PTI ON OF I NVENTI ON
The various features provided by a preferred embodiment of the present invention are generally shown in FIG. 1, in which heat exchanger assembly 10 has an outer pres6urizable shell 12 which i6 flange connected to the tube side inlet and outlet bead as6embly 14 and i~ welded to the shellside outlet head 16.
Multiple parallel tube6 20 are provided in a removable tube bundle 22 within the outer 6hell 12, the tubes being sealably attached at one end to stationary tube sheet 23 and at the - opposite end to floating tubesheet 25. Tube bundle 22 is also provided with an inner cylindrical shell 26 which is flexibly attached to the tube sheet 23 by bellows 40 and is rigidly attached to the floating tube6heet 25. Attached to the removable inlet head assembly 14 i6 a center pipe 30 which i6 attached to flange 13 and i8 provided concentrically within inner shell 26, and extends past the stationary tubesheet 23 to the floating t~b~sh~et 25. The center pipe 30 conduct6 the hot inlet gas directly from the tube 6ide inlet nozzle 13 to the floating head 24 of the heat exchanger bundle 22 from where it flows baak through multiple tubes 20 to head 14. Central pipe 30 is made of a stainle6s steel material suitable for the high temperature service up to about 1250 F., 6uch as AISI Type 347 6 teel.
From the hsat exchanger floating head 24 end, the hot gas then flows back mainly ll:hrough the tubes 20, but a small portion of the hot ga~ is also distributed through an annulus 32 formed between inner shell 26 and a thermal 61eeve 34 attached to the outer surface of center pipe 30. From the floating head 24 end, the small bypass gas stream enters the annular space 32 and pa6ses between the thermal sleeve 34 and the inside diameter of the inner shell 26, and thereby flows parallel to the gas flow~ng through multiple tubes 20. The annulus 32 is of such cross-6ectional area that the small flow of hot bypasR gas therethrough will re6ult in the temperature for inner shell 26 being approximately that of tubes 20, so as to minimize the differential temperature between the inner ~hell 26 and tubes 20 and thereby minimize the difference in thermal growth between shell 26 and the tubes 20. Thus, because a substantially "dead air" space effectively exists in the annular space 32 between the thermal 61eeve 34 and center pipe 30 to provide an insulating gas layer therebetween, the temperature profile along the inner shell 26 6ubstantially matches the temperature profile of the tubes 20.
If desirea, the thermal sleeve 34 can be provided as multiple ~leeves 35 arranged in serie6 and, each attached at one end to center pipe 30, as is shown in FIG. 2.
The center pipe assembly 30 is separately attached to head assembly 1~ and bolted flange 18. By this construction arrangement, the central pipe assembly can be advantageously removed rom within shell 26 of tube bundle 22 of the heat exchanger 10, to permit removal of carbon deposits within passageway 32.
The basic design concept for the heat exahanger of the present invention is to avoid or minimize elevated temperatures for those metal parts subject to the high primary unit pressure, such as above about 500 psig. The utilization of the center pipe 30, which immediately conducts the hot inlet gas stream entering at flange 13 to those parts subjected only to differential pressure 80 that the hot gas i6 cooled immediately by the counteraurrent gas flow exiting from tubes 20, aids in accomplishing this desired result. Thus the gas flow streams are arranged so as to minimiz0 exposure of the pressure stressed ,. ~
,., ~lL2'~9~33 metal walls to the high temperature inlet gas and to expose as much as po~sible of the shell 12 and channel head assembly 14 to the lower temperature proces~ gas stream within the shell and tube side of the exchanger. Also, the heat exchanger i~ ar~anged so as to avoid insofar as possible differing temperatures across the diameter of the exchanger. In addition, the tube sheet bolted joints at 27 and 28 located at opposite ends of tube bundle 22 are designed to accommodate unexpected strains and movements that may occur in the tube bundle 22 dua to rapid temperature changes such as during start-up or shut-down operation of the heat exchanger unit.
To minimize the temperature level6 to which the heat exchanger pres6urized outer 6hell 12 and flow ohannel head assembly 14 are exposed, the hot effluent stream entering the channel head assembly is conducted via center pipe 30 directly to the floating head 24, which serves to isolate the hot gas temperature from the high pressure boundary shell 12 and the boundary channel head assembly 14 of the exchanger. The shell side gas flow enters at nozzle 17 and flows around multiple parallel tubes 20 and then through the annular space 24a around the floating head 24 to exit at centrally located nozzle 19.
This flow pattern tends to keep the temperatures uniform around the inner floating head 24, avoids distortions of flange joint 28, and prevents the shell side outer head lS from overheating due to it~ proximity to the higher temperature floating head 24.
In order to additionally protect the tubes 20 and inner shell 26 from damaging differential temperature stresses during process ~tartup or any upset conditions, a metal bellows expansion -~oint 40 is provided at the channel head assembly end between the inner shell 26 and the fixed tubesheet 23. The cooled gas exiting from the tubes 20 within the head assembly 14, which gas has been lowered in temperature by heat exchange with the feedstream flowing in the shellside, flow~ past the bellows expansion joint 40 and thereby cools the ~oint to a temperature level where reasonable allowable metal stresses can be used in the design of the joint.
Another important feature of the heat exchanger of the invention is the use of an annular channel provided by conical-shaped f~ow baffle 42 located within inlet head assembly 14 and attached at its base to head assembly 14, as shown in FIG. 1.
Baffle 42 serves to direct the flow exiting from tubes 20 towards the inlet point for the reactor hot gas feedstream in the central pipe 30, and then annularly through the annular flow channel ~4 to exit at 15. This gas return flow in the annulus 44 formed by ~affle 42 and the inner wall of head assembly 14 cools this head a~sembly, which restricts the elevated metal temperature to that area immediately adjacent to the hot gas 15 entry pipe 30. Thu6, the gas flow exiting from tubes 20 is deflected by annular baffle 42 through the annular flow channel 44 towards the location of tube side exit 15, which flow path cools the head assembly 14 and minimizes the metal temperature at the point where the hot gas stream enters the heat exchanger.
The tube bundle 22 is preferably made removable from the outer shell 12, which can be accomplished by removal of head assembly 14 at outer bolted type flange 29. The bolted joints at 27 and 28 are ring type joints designed with a clamp ring to enable the use of longer bolts 37 than if the fixed tube sheet and floating cover head 24 were each bolted directly to their ad~acent mating pieces. The use of an oval-shaped ring gasket 38 in these flanged ~oints 27 and 28 permit6 adequate joint rotation to accommodate strains and distortions in the joint, while the additional strain available in the longer bolts 37 aids in maintaining a tight joint during transient as well as normal temperature conditions.
As explained above, to limit the amount of heat transmitted from the hot inlet gas s~tream through nozzle 13 to the pressurized inner shell 26, the center pipe 30 is preferably fitted with a plurality of thermal sleeves 35 extending from pipe ~, ~2'~
free end 30a to a point beyond the internal expansion joint 40, as best shown by FIG. 2. Also, short lengths of tubes or ferrules 21 having an outside diameter slightly smaller than the inside diameter of tubes 20 are preferably provided attached in the floating head end of tubes 20, so as to provide gas pockets at 21a within the tubes 20 to absorb the differences in temperature at this location.
The heat exchanger of this invention is suitable for high temperature service at high pressure, such as for 1000-1300-F
temperature and 500-1000 psig pressure. By using this heat exchanger design configuration, the temperature of the two counterflowing gas streams can be brought close together and even crossed if desired, so as to maximize the heat recovery from the hot gas stream provided by the exchanger. This heat exchanger is typically used for exchanging heat between a feedstream to a reactor entering at connection 17 and the reactor hot effluent stream being passed first through the center pipe assembly 30 and then back through the multiple tubes 20 to heat the feedstream passing through the exchanger shell side and around the tubes to near the reactor inlet temperature, and thereby reduce furnace heating costs for the feedstream.
Although this heat exohanger invention has been described broadly and in terms of a preferred embodiment, it will be understood that design modifications and variations to the exchanger can be made within the spirit and scope of the invention, which is definad by the following claims.
',,~
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A tube type counterflow heat exchanger arranged for high temperature service, comprising:
(a) a pressurizable outer shell having a head attached at each end of the shell, said head at an inlet end being attached to the shell by a bolted flange type connection and the head at the opposite outlet end being welded to the shell;
(b) multiple parallel tubes provided longitudinally within said outer shell, said tubes being located outwardly from a centrally-located parallel inner shell and sealably attached at one end to an inlet end stationary tube sheet which is connected to said inlet head, said multiple tubes being sealably attached at the other end to a floating tube sheet having an attached floating head;
(c) a central pipe extended longitudinally within said inner shell, as so to provide a narrow annular space between the central pipe and the inner shell; said central pipe being attached at one end to said inlet head so that the pipe is removable from said inner shell; and (d) a metal bellows attached at one end to said inner shell and attached at the other end to said stationary tube sheet; so as to accommodate differential thermal expansion between the inner shell and the stationary tube sheet during high temperature operation of the heat exchanger.
(a) a pressurizable outer shell having a head attached at each end of the shell, said head at an inlet end being attached to the shell by a bolted flange type connection and the head at the opposite outlet end being welded to the shell;
(b) multiple parallel tubes provided longitudinally within said outer shell, said tubes being located outwardly from a centrally-located parallel inner shell and sealably attached at one end to an inlet end stationary tube sheet which is connected to said inlet head, said multiple tubes being sealably attached at the other end to a floating tube sheet having an attached floating head;
(c) a central pipe extended longitudinally within said inner shell, as so to provide a narrow annular space between the central pipe and the inner shell; said central pipe being attached at one end to said inlet head so that the pipe is removable from said inner shell; and (d) a metal bellows attached at one end to said inner shell and attached at the other end to said stationary tube sheet; so as to accommodate differential thermal expansion between the inner shell and the stationary tube sheet during high temperature operation of the heat exchanger.
2. The heat exchanger according to claim 1, wherein a thermal sleeve is provided within said annular space, said sleeve being attached to the outer surface of said central pipe.
3. The heat exchanger according to claim 2, wherein said thermal sleeve within said annular space is provided in multiple lengths, each length being attached to the outer surface of the central pipe
4. The heat exchanger according to claim 1, wherein said inlet head is conical-shaped and a tapered baffle is provided attached to the inner surface of the conical head so as to cause gas flowing from the tubes to flow past said bellows to effectively cool the bellows and inlet head before the gas leaves the heat exchanger.
5. The heat exchanger according to claim 1, wherein said central pipe is made of stainless steel material suitable for withstanding temperature of at least about 1000°F.
6. The heat exchanger according to claim 1, wherein ferrules are provided attached within said multiple tubes at the floating head end, so as to provide a gas pocket between the ferrule and the tube inner wall.
7. The heat exchanger according to claim 1, wherein said stationary tube sheet is connected to said inlet head by a bolted flange type joint.
8. A tube type counterflow heat exchanger arranged for high temperature service, comprising:
(a) a pressurizable outer shell having a head attached at each end of the shell, said head at an inlet end being attached to the shell by a bolted flange type connection and the head at the opposite outlet end being welded to the shell;
(b) multiple parallel tubes provided longitudinally within said outer shell, said tubes being located outwardly from a centrally-located parallel inner shell and sealably attached at one end to an inlet end stationary tube sheet which is also connected to said inlet head, said multiple tubes being sealably attached at the other end to a floating tube sheet having an attached floating head, said tubes each having a ferrule attached therein at the floating head end of the tubes so as to provide a gas pocket between the ferrule and the tube inner wall;
(c) a central pipe extended longitudinally within said inner shell, so as to provide a narrow annular space between the central pipe and the inner shell, said central pipe being attached at one end to said inlet head so that the pipe is removable from said inner shell;
(d) at least one thermal sleeve located within said annular space, said sleeve being attached to the outer surface of said central pipe; and (e) a metal bellows attached at one end to said inner shell and attached at the other end to said stationary tube sheet; so as to accommodate differential thermal expansion between the inner shell and the stationary tube sheet during high temperature operation of the heat exchanger.
(a) a pressurizable outer shell having a head attached at each end of the shell, said head at an inlet end being attached to the shell by a bolted flange type connection and the head at the opposite outlet end being welded to the shell;
(b) multiple parallel tubes provided longitudinally within said outer shell, said tubes being located outwardly from a centrally-located parallel inner shell and sealably attached at one end to an inlet end stationary tube sheet which is also connected to said inlet head, said multiple tubes being sealably attached at the other end to a floating tube sheet having an attached floating head, said tubes each having a ferrule attached therein at the floating head end of the tubes so as to provide a gas pocket between the ferrule and the tube inner wall;
(c) a central pipe extended longitudinally within said inner shell, so as to provide a narrow annular space between the central pipe and the inner shell, said central pipe being attached at one end to said inlet head so that the pipe is removable from said inner shell;
(d) at least one thermal sleeve located within said annular space, said sleeve being attached to the outer surface of said central pipe; and (e) a metal bellows attached at one end to said inner shell and attached at the other end to said stationary tube sheet; so as to accommodate differential thermal expansion between the inner shell and the stationary tube sheet during high temperature operation of the heat exchanger.
9. A heat exchanger according to claim 1, wherein said central pipe is removably attached to said inlet head assembly.
10. A heat exchanger according to claim 1, wherein said stationary tube sheet is attached to said inlet head by a bolted ring-type flange.
11. A heat exchanger according to claim 1, wherein said floating head is attached to said floating tube sheet by a bolted ring-type flange.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US48234183A | 1983-04-05 | 1983-04-05 | |
| US482,341 | 1983-04-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1249583A true CA1249583A (en) | 1989-01-31 |
Family
ID=23915669
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000451259A Expired CA1249583A (en) | 1983-04-05 | 1984-04-04 | Counterflow tubular heat exchanger having center pipe construction |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1249583A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108981427A (en) * | 2018-07-09 | 2018-12-11 | 中国核动力研究设计院 | A kind of tubular heat exchanger |
| CN109935879A (en) * | 2019-04-10 | 2019-06-25 | 武汉福赛尔新能源科技有限公司 | A kind of pile core structural of floating head type solid oxide fuel cell |
| CN113405376A (en) * | 2021-07-05 | 2021-09-17 | 南京聚拓化工科技有限公司 | Full-counterflow heat recovery device |
| US11260357B2 (en) | 2017-12-21 | 2022-03-01 | Uop Llc | Process and apparatus for fluidizing a catalyst bed |
-
1984
- 1984-04-04 CA CA000451259A patent/CA1249583A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11260357B2 (en) | 2017-12-21 | 2022-03-01 | Uop Llc | Process and apparatus for fluidizing a catalyst bed |
| CN108981427A (en) * | 2018-07-09 | 2018-12-11 | 中国核动力研究设计院 | A kind of tubular heat exchanger |
| CN109935879A (en) * | 2019-04-10 | 2019-06-25 | 武汉福赛尔新能源科技有限公司 | A kind of pile core structural of floating head type solid oxide fuel cell |
| CN109935879B (en) * | 2019-04-10 | 2024-03-15 | 福赛尔科技集团有限公司 | Pile core structure of floating head type solid oxide fuel cell |
| CN113405376A (en) * | 2021-07-05 | 2021-09-17 | 南京聚拓化工科技有限公司 | Full-counterflow heat recovery device |
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| MKEX | Expiry |