KR101962996B1 - Modular plate and shell heat exchanger - Google Patents

Abstract

Modular plates and shell heat exchangers are provided in which pairs of welded heat transfer plates are spaced apart and coupled between the inlet and outlet conduits to form a heat transfer assembly. The heat transfer assembly is disposed within the shell to transfer heat from the second fluid to the first fluid. The modules of the one or more heat transfer plates are releasably connected to the inlet and outlet conduits connected to the first fluid inlet and the first fluid outlet nozzle using a gasket. The heat transfer assembly is supported by a structure that leans against an inner track attached to the shell to enable separation of the heat transfer plate. The modular plate and shell heat exchanger has a detachable head integrally formed in the shell for detachment of the heat transfer plate for inspection, maintenance and replacement.

Description

[0001] MODULAR PLATE AND SHELL HEAT EXCHANGER [0002]

The present invention relates generally to the modularization of heat exchangers and, in particular, stacked plate heat exchangers.

The feedwater for the steam generator in the reactor plant is typically pre-heated before being introduced into the secondary side of the steam generator. Similarly, the feedwater is pre-heated before being introduced into the boiler for non-nuclear power plant applications. For this purpose, a water heat exchanger is generally used. Traditionally, the heat exchanger design has been divided into two types: a heat exchanger having a plate structure and a heat exchanger having a tube and shell structure. With respect to both construction and heat exchangers, the major difference between these two types is that the heat exchanger surface is primarily a plate in one structure and a tube in the other.

The tube and shell heat exchangers in many feedwater heater applications employ horizontal or vertical tubular shells having hemispherical or flat ends. The inside of the horizontal shell is divided into sections by a tube sheet perpendicular to the axis of the shell. More specifically, at one end of the shell, a water chamber section including a water inlet chamber having a water inlet opening and a water outlet chamber having a water outlet opening is provided on one side of the tube sheet Defined. Within the U-tube and shell heat exchangers, a plurality of heat transfer tubes are bent in a U-shape at its central portion and extend from the other side of the tubesheet along the axis of the shell. These tubes are fixed to the tubesheet at both ends such that one end of each tube opens into the water inlet chamber while the other end opens into the water outlet chamber. Another type of tube and shell heat exchanger employs a straight tube having an inlet chamber and an outlet chamber at opposite ends of the tube, respectively. The heat transfer tube is supported by a plurality of tube support plates and is spaced at a suitable pitch in the longitudinal direction of the tube. The steam inlet opening, the drain inlet and the outlet are formed in the shell at the portion where the tube extends.

In operation, the incoming water from the water inlet chamber into the feedwater heater flows through the U-shaped heat transfer tube and absorbs heat from the heating steam entering the feedwater heater at the steam inlet opening to condense the steam. The condensate is collected at the bottom of the shell and discharged to the outside through the drain in the bottom of the shell. Due to the cylindrical shape of the heat exchanger tubes and shells, this structure is very suitable as a pressure vessel, and thus tube and shell heat exchangers have been used in very high pressure applications.

The biggest disadvantage of tube and shell heat exchangers is that they weigh more than the surface area of the heat transfer surface. As a result, tube and shell heat exchangers are typically large in size. Also, it is difficult to design and manufacture tube and shell heat exchangers when considering heat transfer, flow characteristics and cost.

Typical plate heat exchangers consist of rectangular, ribbed or grooved plates, which are pressed against one another by an end plate which in turn is fitted with tension rods or tension screws ) To the end of the plate laminate. The gaps between the plates are closed and sealed with banded seals on the outer perimeter of these gaps, and the seal is also used in the flow channel. Since the bearing capacity of the sleek plates is weak, these plates are reinforced with grooves arranged in a staggered arrangement in adjacent plates, and these grooves are also formed when ridges of grooves are supported by each other Thereby improving pressure durability of the structure. However, a more important aspect is the importance of the grooves for heat transfer, and the shape of the grooves and the angle of the grooves with respect to the flow affect the heat transfer and the pressure loss. In a conventional plate heat exchanger, the heat supply medium flows through every one gap in the gap between the plates, and the heat receiving medium flows through the remaining gap. In an alternating pair of plates, this flow is guided through the holes arranged near the corners of the plate. Each gap between the plates in the alternating pairs of plates always includes two holes with closed rims and two other holes which serve as inlet channels and outlet channels for the gaps between the plates. When a small, lightweight structure is desired, the plate heat exchanger typically consists of a relatively thin plate. Because the plate is profiled in any desired shape, it can produce heat transfer characteristics that are suitable for almost all types of applications. A major disadvantage of conventional plate heat exchangers is that they limit the pressure and temperature durability of the heat exchanger. In some cases, the seal has limited the possibility of using corrosive media for heat supply or heat reception.

Attempts have been made to improve the plate heat exchanger structure by replacing them with solder joints or weld joints except all seals. Plate heat exchangers made by brazing or welding are typically similar to those with seals. The most noticeable difference is that there is no tension screw between the ends. However, soldered or welded structures are very difficult, if not impossible, to disassemble such a heat exchanger in a non-destructive manner for cleaning.

Attempts have been made to incorporate the advantages of tube and shell heat exchangers and plate heat exchangers in a heat exchanger having a partially similar structure to both of these basic types of heat exchangers. One such method is disclosed in U.S. Patent No. 5,088,552 wherein circular or polygonal plates are superimposed and laminated together to form a laminate of plates supported by the end plates. The plate laminate is surrounded by a shell and the sides of the shell are provided with an inlet channel and an outlet channel for the corresponding flow of the heat supply medium and the heat receiving medium. Unlike conventional plate heat exchangers, all flow into the gap between the plates is directed from the outside of the plate. When the heat exchanger according to the US patent is closed by welding, it is possible to obtain the same pressure as when using the tube and shell heat exchanger while having heat transfer characteristics of the plate heat exchanger.

International Publication No. WO 91/09262 shows an improvement over the US patent publication, which more clearly shows the typical characteristics of both the plate heat exchanger and the tube and shell heat exchanger. Circular plates are drawn together in pairs by welding them together at the edges of the holes forming the inlet and outlet channels. A closed circuit for the flow of one heat transfer medium is obtained by welding a pair of plates made together in the manner described above by the outer periphery of the plate. Unlike a conventional plate heat exchanger, this structure is welded and there are only two holes in the plate. The flow of the other heat transfer medium is directed to one additional gap between the plates by the shell surrounding the plate laminate. In order to prevent the flow from flowing between the plate laminate and the shell, a seal is used which is mainly used as a deflector for the flow. Obviously, pressure durability is not required for the deflector. Due to the structure of the laminate of the plate, it is difficult to seal. By proposing an elastic rubber gasket for sealing, it has become possible to disassemble the heat exchanger for the purpose of cleaning, for example.

Shell and tube heat exchangers currently used in nuclear power plants are the only option in an effort to minimize leakage when tube degradation occurs by closing the damaged tube which results in the loss of thermal duty Which is a common design defect. The loss of heat load in the feedwater system is large for nuclear power plants and eventually requires the replacement of shell and tube feedwater heaters. Other constraints of shell and tube design are that shell side inspection is generally limited to small hand holes and inspection ports and as a result, corrosion / erosion damage is difficult to detect. Significant erosion / erosion has been sustained due to internal disturbances, which can cause (1) flow bypass and thermal performance degradation, and (2) tube wear due to flow induced vibration can do. In addition, considerable erosion / erosion has been observed on the inner shell surfaces of shell and tube feedwater heater designs.

Thus, there is a need for a new feedwater heater design for improved long term part integrity and longer lasting heat load compared to current shell and tube feedwater heater designs. Preferably, the long term sustainable heat load can be achieved by replacing or repairing the heat transfer surface as needed, instead of requiring the heat transfer surface to be separated from the service. Also, by increasing the heat transfer capacity of the feedwater heater, it is desirable to be able to provide power plant performance ups without the replacement of the entire feedwater heater.

The above-mentioned object is achieved by a modular plate and a shell feedwater heater in which a pair of welded heat transfer plates are arranged in the shell for transferring heat from the drain flow and the extraction steam to the feedwater in the nuclear power plant. The heat transfer plate pairs, or a group of heat transfer plate pairs welded or otherwise coupled, i.e., heat transfer plate pairs, are arranged side by side and at least some of the modules are connected in parallel using common gas inlet conduits and / The inlet conduit and the outlet conduit are each connected to a feed inlet nozzle and a water outlet nozzle. The inlet and outlet conduits and the pair of heat transfer plates form a heat transfer assembly which is placed on an inner track attached to the interior of the shell and supported by a structure movable along the track, . The modular plate and shell feedwater heater has a removable head integral with the shell for separation of the heat transfer plate for inspection, repair or replacement. Preferably, the inlet and outlet nozzles are sealed to and extend through the removable head.

Preferably, the heat exchanger provided herein includes means for increasing the heat exchange capacity of the unit per hour to provide upratings of the plant in which the heat exchanger is mounted. In one embodiment, the inlet and outlet conduits comprise a number of additional attachment points for a pair of heat transfer plates, which are initially plugged. In other embodiments, the inlet and outlet conduits may be expandable by attachment of additional heat transfer plate pairs or modules. In the latter embodiment, the heat exchanger may initially be provided with a spacer module having a heat capacity of no or relatively negligible heat capacity, which is supported in parallel with the heat transfer plate module. The heat transfer plate module may later be replaced with a spacer module to increase the heat transfer capacity of the heat exchanger. Preferably, at least a portion of the coupling between the pairs of heat transfer plates, or between the modules of the coupled pair of heat transfer plates, is detachable for ease of repair and replacement. Preferably, in an embodiment having a rod connecting the modules and an inlet and an outlet conduit extending between the modules, the tie rod has a pressure seal at the interface of the conduit segment of the interfacing module To form a tight seal.

Preferably, the heat transfer assembly is removed from a shell having a removable head. Alternatively, a manway for access to the interior of the shell may be provided in the shell to separate the feed inlet nozzle from the feed inlet conduit and to separate the feed outlet hair conduit from the feed outlet nozzle, All of the options may be provided.

Preferably, the module has a support panel between each end where the tie rod extends. The pair of heat transfer plates is sandwiched between the support panels, and in one embodiment, the primary fluid inlet and the first fluid outlet conduit pass through the module. Preferably, the support panel is thicker than the heat transfer plate. In one embodiment, the heat transfer plates between the support panels are welded together to the support panel, and the adjacent support panels are mechanically connected to one another.

The present invention also relates to a method of manufacturing a pressure vessel comprising the steps of approaching the interior of a pressure vessel shell, separating at least a pair of heat transfer plates from a heat transfer assembly of the heat transfer plate, And reconnecting the pair of cleaned, repaired or replaced heat transfer plates to the heat transfer assembly. Preferably, the step of approaching the interior of the pressure vessel shell comprises separating the detachable head, wherein separating the at least one pair of heat transfer plates comprises providing a pair of heat transfer plates to the water inlet conduit and the water outlet And separating from the conduit.

The present invention further encompasses a method of repairing, inspecting, cleaning, or upgrading a water heater with a pressure vessel having a removable head. The method comprising the steps of separating the detachable head or approaching the interior of the pressure vessel shell, and connecting the water inlet conduit and the water outlet conduit from the water inlet nozzle and the water outlet nozzle respectively, while the heat transfer assembly is in the pressure vessel And releasing it. The method further includes upgrading the feedwater heater by increasing the number of pairs of heat transfer plates after the water heater is disposed in service, as well as replacing the pair of defective heat transfer plates.

1 is a front view of a water heater according to an embodiment of the present invention.
2 is a plan view of the water heater shown in Fig.
Figure 3 is a perspective view of another embodiment of a feedwater heater of the present invention having a heat transfer assembly that is divided into modules and partially separated from the shell.
Figure 4 is a perspective view of one of the end module of the pair of heat transfer plates of the embodiment shown in Figure 3;
Figure 5 is a perspective view of a portion of the heat transfer assembly partially shown in Figures 3 and 4;
FIG. 6 is a schematic view illustrating the flow of the first fluid through the embodiment of the feedwater heater shown in FIGS. 3 to 5. FIG.
Figure 7 is a side view of a pair of heat transfer plates.
8 is a schematic view of one embodiment of a heat transfer plate module described hereinafter.
9 is a schematic view of a second embodiment of a heat transfer plate module as described hereinafter.
10 is a sectional view of the spacer module described later.
11 is a side view showing a partial cross-section of a tie rod portion that may be employed coupled to two heat transfer plate modules.

A further understanding of the invention may be obtained when reading the following description of the preferred embodiments together with the accompanying drawings.

Current water heater designs employed within nuclear power plants utilize shell and tube heat exchanger devices. Another common type of heat exchanger that has existed since 1923 is plate and frame heat exchangers. The latter heat exchanger features a compact design, high heat transfer coefficient, high hydraulic drop within the plate, and is generally limited to low pressure liquids. The embodiment described herein is a simple yet serviceable and easily replaceable, combined and optimized side of conventional plate and frame heat exchangers and conventional shell and tube type heat exchangers, In which the plate and shell feedwater heaters can be increased.

The water heater 10 according to an embodiment of the present invention is shown in a front view in FIG. 1 and a plan view in FIG. Two heat transfer plates (12, 14) are welded together to form a welded plate pair (16), between which a flow channel for water supply fluid such as in a conventional plate heat exchanger is formed. In one embodiment, the heat transfer plate pair 16, together with, for example, gasket 18 and bolted flange joints 20, is welded at one end of welded heat transfer plate pair 16 to inlet header pipe 22 And is connected to the outlet header pipe 24 at the other end of the welded pair of heat transfer plates 16. [ A plurality of these welded heat transfer plate pairs 16 are stacked in a spaced series arrangement and are each connected between the inlet header and the outlet header to form a heat transfer assembly having a parallel flow path. Such an arrangement is shown in Fig. Optionally, the plurality of heat transfer plate pairs 16 may be arranged in series, and the ends of the series arrangement are detachably attached to the inlet header pipe 22 and the outlet header pipe 24 in a similar manner I have to understand. In either embodiment, the ends of the pair of heat transfer plates 16 are connected directly or indirectly to the inlet header pipe 22 and the outlet header pipe 24. The inlet header pipe 22 and the outlet header pipe 24 are connected to a pair of heat transfer plates 16 for the inlet header pipe 22 and the outlet header pipe 24 using bolted fasteners with gaskets , It is to be understood that other detachable attachment means may be used, although it is to be understood that they may be connected to the feed inlet nozzle 26 and the feed water outlet nozzle 28, respectively,

In the embodiment shown in Figures 1 and 2, the header pipes 22 and 24 are connected to an inner track 32 attached to the bottom of a cylindrical shell 34 forming a pressure vessel surrounding the heat transfer plate assembly 36 Lt; / RTI > is supported by the underlying frame structure 30. The track 32 and wheel 33 on the frame structure 30 facilitate separation of the heat transfer plate assembly from the shell for repair, cleaning or performance up. In one embodiment, the shell includes a cylindrical shell 34, a hemispherical end 38, and a removable head 40 having an integral hemispherical end 38 at one side and a removable hemispherical head 40 at the other side. Lt; RTI ID = 0.0 > 36 < / RTI > It should be understood that the end need not necessarily be hemispherical in order to use the present invention, but the hemispherical end is preferred in the field where high pressure is applied. The removable head 40 has a water inlet nozzle 26 and a water outlet nozzle 28 which extend through the removable head 40 as shown in Figs. Optionally, instead of the head 40, the hemispherical end 38 may be configured to be detachable, or in order to increase flexibility in accessing the interior of the shell 34 and serving the heat transfer plate assembly 36, Both of which may be connected to the shell 34 by bolted flange connections. The shell 34 also has an extraction steam inlet 42, drain inlets 44 and 46, and drain outlets 48 and 50.

In operation, the inlet feedwater passes through inlet nozzle 26, inlet header pipe 22, welded welded heat transfer plate pair 16, outlet header pipe 24 and outlet pipe 28, Heated by the drain flow and the extraction vapor in the heat transfer plate pair (16). The extracted steam is distributed by the steam impingement plate 52 when entering the feedwater heater through the extraction steam inlet 42 and passes through an upper shell region that mixes with the drain flow entering the drain flow inlet nozzles 44 and 46 do. The extracted vapor and drain flows are then passed between the welded heat transfer plate pairs 16 where they are cooled by the feed water and condensed into the lower shell region in which the drain flow outlet nozzles 48, .

During shutdown of the plant, the following steps may be used to conduct inspection of the heat transfer plate and shell inner surface. First, the shell end 38 is unbolted in the flange 54 and released. The header pipes 22 and 24 are then disconnected from the inlet and outlet nozzles 26 and 28. The passages 56 on the head 40 can be used to access the connections between the inlet and outlet header pipes 22 and 24 and the inlet and outlet nozzles 26 and 28. Optionally, when the head 40 is detached from the flange 58, the head 40 can move and the heat transfer assembly 36 can be moved between the inlet and outlet header pipes 22, 24 and the water inlet and outlet nozzles 26, 28) of the track (32). Before moving the head 40, spool piping (not shown) needs to be separated from the inlet and outlet nozzles 26, 28. Next, the heat transfer plate assembly 36 is mounted on a track (not shown) disposed at the bottom of the shell 34 to a position where it can inspect for damage to the interior of each heat transfer plate 12,14 and shell 34 32). Each heat transfer plate pair 16 can then be cleaned or repaired or replaced as needed. When repair or replacement is required, the pair of heat transfer plates 16 that need to be treated are unbolted from the inlet header pipe 22 and the outlet header pipe 24 to form a new or repaired heat transfer plate pair (16). In addition, the outlet header pipe 24 and the inlet header pipe 22 are provided with one or more additional openings 60 that are initially sealed by plugs. These additional openings may be unsealed to accommodate additional pairs of heat transfer plates 16 if performance ups are required later.

The detachable plate design allows replacement of the heat transfer surface, and mass production of the heat transfer plate and gasket results in relatively low cost for critical spare parts. By employing this design, the number of plates and the heat transfer area associated therewith can be increased to provide improved power generation performance and provide an improved shell side inspection.

While specific embodiments of the invention have been described in detail, those skilled in the art will readily appreciate that many modifications and alternatives to those embodiments may be included in light of the overall teachings of the disclosure. For example, although separate inlet and outlet header pipes or conduits are shown in the embodiment of FIGS. 1 and 2, any other structure that performs the functions described above may be used without departing from the spirit of the present invention. For example, an embodiment of the heat transfer assembly 36 shown in FIGS. 3-5 illustrates portions of the inlet and outlet conduits 22, 24 as integral parts of the pair of heat transfer plates 16. 3 to 5 corresponding to the components shown in Figs. 1 and 2 are given like reference numerals. In the embodiment shown in Figs. 3-5, the heat transfer plate assembly 36 is formed of a plurality of heat transfer plate modules 17. Four such heat transfer plate modules are shown in FIG. Each such module 17 is formed from a plurality of side-by-side spaced apart heat transfer plate pairs 16 joined together in an integrated unit. Each of the modules 17 shown in Figures 3-5 has about ten such heat transfer plate pairs, but the more heat transfer plate pairs 16 in the module 17, the more expensive the modules to be replaced It will be appreciated that any number of such heat transfer plate pairs 16 may be used under the results. Optionally, the more modules, the more gasket and closure hardware will be written. The optimal range of plate count per module can be determined on a concrete basis of the application under economical considerations. In addition, the number of modules 17 in the heat transfer assembly 36 may vary depending upon the number of heat transfer plate pairs 16 per module and the heat transfer requirements of the application in which the heat exchanger will be employed.

3 to 5, the outer surfaces (i.e., front and rear) of each heat transfer plate pair 16 have two openings on each side with corresponding openings substantially aligned with one another, and the inlet and outlet conduits 22 The incremental portion 23 of the heat transfer plate pairs 24,24 is substantially rigid and is substantially unaffected by the fluid flowing in and around the inlet and outlet conduits 22, For example, welded, soldered, or any suitable combination to form a durable joint. The increased portion of the inlet and outlet conduits 22, 24 that pass between the pair of heat transfer plates 16 and the outer surfaces of the adjacent pair of heat transfer plates 16 are located between the pairs of heat transfer plates 16 for vapor discharge Provide the flow path and draw the flow through. The outer ends 23 of the portions of the inlet and outlet conduits 22, 24 formed through each module 17 preferably have corresponding flanges on the flanges to which the adjacent heat transfer plate module portions 23 can be connected And preferably has a gasket which is pressed between the flanges. Thereafter, the outer portion 23 on each module 17 is joined to the corresponding portion 23 on the outer side of the adjacent module with a gasket therebetween, using the tie rod 64 shown in Figures 3-5 But other types of mechanical attachments may be used instead of tie rods. In the embodiment shown in Figs. 3-5, the module 17 is held in position by the front and rear frames or plates 62 taken out by the tie rods 64. Fig. The plate 62 on the front side of the heat transfer plate has openings for the inlet and outlet conduits 22 and 24 so that the flanges on the outer portion 23 are aligned with the inlet and outlet nozzles 26 and 28 Respectively. Both outlets and outlets on the rear heat transfer plate at the outer portion 23, i.e., at the end 80 of the heat transfer assembly 36, are plugged to close the water flow loop, or the rear heat transfer plate is free of inlet and outlet openings Respectively.

The flow of the first fluid through the heat transfer plate assembly of the embodiment described above, having a parallel flow path through the pair of heat transfer plates 16, is shown in Fig. Figure 7 shows the construction of a pair of heat transfer plates. 7, a weld bead 66 extends around each incremental portion 23 of the inlet conduit 22 at a corresponding opening in the heat transfer plate 12, 14, To form a fluid tight seal. Similarly, the weld bed 68 extends around each incremental portion 23 of the outlet conduit 24 at the corresponding opening of the heat transfer plate 12, 14 to form a fluid tight seal at the interface. In addition, a girth weld 70 extends around the entire periphery of the heat transfer plate pair 16. 7, the first fluid enters the inlet conduit 22 inlet 72 of each pair of heat transfer plates 16 connecting the pair of heat transfer plates 16 to an adjacent pair or support plate . A portion of the fluid flows between the heat transfer plates 12,14 which absorb heat from the exhaust vapors to drain the flow onto the outside of the pair of heat transfer plates and exit to the outlet conduit 24 at the outlet 78, This meets the first fluid flow upstream from the other pair of heat transfer plates entering through the outlet conduit inlet 76 into the pair of heat transfer plates. Except for the last pair of heat transfer plates 16 in the end portion 80 (Figure 5) of the heat transfer plate assembly 36, the heat transfer plates 12, 14 of the given pair of heat transfer plates 16, The remainder of the first fluid entering the inlet 72 exits through the inlet conduit outlet 74 to the next pair of heat transfer plates 16. All of the first fluid that traverses the inlet conduit to the end 80 of the heat transfer plate assembly 36 travels through the remaining pair of heat transfer plates 12 and 14 and the first fluid passes through the outlet And exits through conduit 24. (As shown in FIG. 6) through the pair of heat transfer plates 16 (as shown in FIG. 6), downward flow (described herein), or side flow extends from the inlet conduit 22 to the outlet conduit 24 It is irrelevant.

8 is a schematic view of one embodiment of a heat transfer plate module 17; Although the module is shown as four heat transfer plate pairs 16, the number of heat transfer plate pairs 16 is variable, as previously described. The heat transfer plate pair 16 has a relatively thin heat transfer plate 12, 14, compared to the outer support plate 82, which is thicker than the inner heat transfer plate pair 16. The support plate 82 is referred to as a support plate and is longer than others and extends past others to accommodate the tie rods shown in Figures 3-5, but this embodiment differs from the embodiment shown in Figures 3-5 It should be understood that it may be slightly different. It should be understood, however, that the manner in which the modules are fixed relative to one another is the same, and that other means for securing the modules together, for example, continuous threaded rods, bolts, etc., may also be used. The inner heat transfer plate is welded together with a conduit increase portion 23 (shown in FIG. 4) extending therebetween and the weld extends around the circular opening in the increased portion of the inlet conduit 22 and the outlet conduit 24 , And the outer edge is present in the peripheral plate weld (70). The gasket grooves 84 are formed around the inlet conduit 22 and the outlet conduit 24 openings in the support plate 82 for gaskets to seal the openings at the interface with the corresponding support plate 82 of the adjacent module 17. [ .

A second embodiment of the heat transfer plate pair module 17 is shown in FIG. The embodiment shown in Figure 9 is similar to the embodiment of Figure 8 except that the outer heat transfer plate has a gasket retaining ring 86 around the opening in the inlet conduit 22 and the outlet conduit 24, . A single support plate is sandwiched between the modules 17 and a gasket on the retaining ring 86 seals openings 22, 24 between each support plate and the heat transfer plate. Alternatively, the grooves may be provided on either side or one side of the support plate to retain the gasket.

The spacer module 88 can be used to maintain space for later use, in addition to other heat transfer plate pair modules 17, for later performance upgrades of heat exchanger-equipped plants that require additional heat transfer capacity in the existing shell The heat transfer plate pair module 17 may be replaced with a heat exchange plate module. One embodiment of such a spacer module 88 is shown in FIG. The spacer module 88 is preferably of the same size as the standard heat transfer plate pair module 17 of the heat exchange unit 10 to be employed. The spacer module in this embodiment comprises two support plates 84 having gasket grooves 84 separated by a lower support 98 having an upper support 96 and a second fluid drain 94, 82). It should be appreciated that the upper support 96 and the lower support 98 may be part of one continuous support cylinder (although not necessarily). The embodiment shown in FIG. 10 is intended to be inserted between the heat transfer plate pair modules 17 and has a pipe 90 surrounding and welded at each support plate interface to form a sealed seal. The pipe 90 carries a first fluid between the heat transfer plate pair modules 17 and forms part of an inlet conduit 22 connecting the modules. As such, the pipe 92 seals the space between the support plates 82 of the spacer module 88 and carries the first fluid through the outlet conduit 24 across it. If a spacer is used at the end of the end portion 80 of the heat transfer plate assembly 36, an opening in the spacer module support plate 82 is unnecessary.

Figure 11 illustrates one embodiment of a tie rod arrangement that may be used to pull modules 17 and 88 together. The tie rods 64 are designed to traverse between the support plates, similar to the width between the support frames 62 shown in Fig. In the embodiment shown in FIG. 11, the tie rod 64 has one end with a reduced diameter having a circumferential thread 104. The circumferential threads 104 terminate at a bearing surface having a size adjacent to one side of the perimeter of the module support plate about the perimeter and the threads 104 extend outwardly through the other side. The other end of the tie rod 64 has an inner circumferential thread 100 of a size corresponding to the outer circumferential thread 104 on the adjacent tie rod 64, Lt; / RTI > Preferably, the outer circumference 102 around the tie rod end has an internal thread 100 that has a square or hexal contour to which torque can be readily applied.

As described above, the heat transfer plate assembly 36 has a wheel 33 running on the track 32, previously described to enable service of the heat transfer plate assembly. In order to upgrade the performance of the heat transfer plate assembly, except that the spacer module 88 is detached and instead an additional heat transfer plate module 17 is coupled, the service is described in the embodiment shown in Figures 1 and 2 .

Additionally, although a preferred embodiment is described as being applied to a feedwater heater, the present invention may be employed with similar advantages in most other types of heat exchangers. Accordingly, the specific embodiments disclosed are by way of illustration only and are not intended to limit the scope of the invention, the scope of the invention being indicated by the appended claims and any and all equivalents thereof.

Claims (20)

In the heat exchanger 10,
And an elongated pressure vessel shell (34) having an axial dimension,
The pressure vessel shell 34 includes a first fluid inlet 26, a first fluid outlet 28, a second fluid inlet 42, 44, , 46, drain outlets 48, 50, and a heat transfer assembly 36,
The heat transfer assembly (36)
A first fluid inlet conduit (22) extending from said first fluid inlet (26) into said pressure vessel shell (34);
A first fluid outlet conduit (24) extending from the first fluid outlet (28) into the pressure vessel shell (34);
A plurality of heat transfer plate modules, each heat transfer plate module comprising a plurality of heat transfer plate pairs (16) supported side by side, each pair of heat transfer plates (16) (70) around the perimeter to define a first fluid flow channel between the first heat transfer conduit (12) and the second heat transfer conduit (12, 14) Or heat transfer plate inlet opening (72) indirectly connected to said first fluid outlet plate opening (72) and a heat transfer plate outlet opening (78) directly or indirectly connected to said first fluid outlet conduit; And
A spacer module (88) configured to retain space for adding a heat transfer capacity later, the spacer module having a heat transfer capacity that is significantly smaller than the modules of the heat transfer plate pair, A second support plate 82 spaced from and opposed to the first support plate, at least one support 96, 98 extending between the first and second support plates, a first pipe 90, And a second pipe (92), each of the first and second pipes extending between the first support plate and the second support plate, the first pipe comprising a portion of the first fluid inlet conduit The second pipe forming part of the first fluid outlet conduit,
The plurality of heat transfer plate pairs 16 are arranged in a module 17 and at least one of the modules is connected by a non-destructively separable mechanical coupling 84 to an adjacent module or the first fluid inlet or And a second fluid outlet
heat transmitter.
delete The method according to claim 1,
A service access for accessing the heat transfer assembly is obtained through the detachable cap (40)
heat transmitter. The method of claim 3,
The heat transfer assembly (36) is removable from the pressure vessel shell (34) when the detachable cap (40)
heat transmitter. 5. The method of claim 4,
The heat transfer assembly 36 is configured to be slidable out of the pressure vessel shell 34 when the detachable cap 40 is open,
heat transmitter. The method according to claim 1,
The heat transfer assembly (36) is movably supported on a track (32) attached to the interior of the pressure vessel shell (34) to move the heat transfer assembly along the track such that the heat transfer assembly Lt; RTI ID = 0.0 > (40) < / RTI >
heat transmitter. The method according to claim 6,
The heat transfer assembly (36) is supported on the track (32) by a wheel (33) running on the track
heat transmitter. The method according to claim 1,
The first fluid inlet (26) and the first fluid outlet (28) extend from the detachable cap (40)
heat transmitter. delete The method according to claim 1,
The heat transfer assembly 36 has a plurality of redundant couplings 60 for attachment to additional heat transfer plate pairs 16 that are initially plugged and the heat exchanger After being placed in an operating state, the heat transfer capacity of the heat exchanger is used to further uprating the heat exchanger by unblocking at least a portion of the additional coupling and attaching a number of the additional heat transfer plate pairs
heat transmitter. The method according to claim 1,
The spacer module 88 is connected in parallel with the module 17 of the pair of heat transfer plates
heat transmitter. The method according to claim 1,
The pressure vessel shell 34 has a cylindrical shape with hemispherical ends 40,
heat transmitter. A method for maintenance of the heat exchanger (10) according to claim 1,
Accessing the interior of the pressure vessel shell (34);
Separating at least a pair of heat transfer plates (16) from the heat transfer assembly (36);
Cleaning, repairing or replacing the pair (s) 16 of separated heat transfer plates; And
(S) (16) of cleaned, repaired or replaced heat transfer plates to the heat transfer assembly (36)
Heat exchanger maintenance method. 14. The method of claim 13,
The step of approaching the interior of the pressure vessel shell 34 may include either removing the detachable cap 40 from the one end or opening the manway 56 on the pressure vessel shell ≪ / RTI &
The step of separating the at least one pair of heat transfer plates (16) includes separating the at least one pair of heat transfer plates from the first fluid inlet conduit (22) and the first fluid outlet conduit (24) doing
Heat exchanger maintenance method. A method for maintenance of the heat exchanger (10) according to claim 1,
Accessing the interior of the pressure vessel shell (34); And
Disconnecting the first fluid inlet conduit (22) and the first fluid outlet conduit (24) from the first fluid inlet (26) and the first fluid outlet (28), respectively,
Maintenance of the heat exchanger may include repair, inspection, cleaning or performance up
A method for maintenance of a heat exchanger (10). 16. The method of claim 15,
Replacing the defective heat transfer plate pair (16)
Heat exchanger maintenance method. 16. The method of claim 15,
Increasing the number of pairs of heat transfer plates (16) in the heat transfer assembly (36) after the heat exchanger (10) is placed in an operating state to upgrade the heat exchanger
Heat exchanger maintenance method. The method according to claim 1,
The heat transfer plate modules are connected to each other in a side-by-side arrangement through a welded coupling (23)
heat transmitter. The method according to claim 1,
The heat transfer plate modules (17) have a support plate (82) on the first and second ends, the heat transfer plates (12, 14) being disposed between the support plates, Thicker
heat transmitter. The method according to claim 1,
The heat transfer plate modules 17 are supported by the tie rods 64 in parallel
heat transmitter.

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