Emission proof heat exchanger

Abstract

An emission-proof heat exchanger comprising a shell-side assembly and a tube-side assembly: a shell (30) welded to said channel (20), directly; an internal cylinder (21) between said tubesheet (10) and an internal sleeve (24); a thread lock ring (15) coaxial to said internal cylinder (21) and ensconced within a co-axial, concentric, shrink ring (60); a first set of fastening mechanisms (22a), mounted on said thread lock ring (15), configured to hold said shell-side gasket (11) in its position by compressing said shell-side gasket (11) held between said tubesheet (10) and the shoulder of the shell; a second set of fastening mechanisms (22b), mounted on said thread lock ring (15), to hold said tube-side gasket (13) in its position by compressing said tube-side gasket (13) held between said thread lock ring (15) and a shoulder on said channel (20) through an outer compression ring (32) and a diaphragm (34).

Description

[0001] EMISSION PROOF HEAT EXCHANGER

[0002] FIELD OF INVENTION:

[0003] This invention relates to the field of mechanical engineering.

[0004] Particularly, this invention relates to heat exchangers.

[0005] Specifically, this invention relates to emission-proof heat exchangers.

[0006] BACKGROUND OF THE INVENTION:

[0007] Shell and tube type heat exchangers are used in numerous applications such as oil refineries, petrochemical plants, pharmaceutical, fertilizer, power plants etc., for heat exchange between the two different fluids primarily for improving the thermal efficiency of the process / plant, by recovering the heat.

[0008] In a shell and tube type heat exchanger, one fluid is circulated outside the tube which is termed as the shell side of the heat exchanger, and the other fluid is circulated inside the tube which is termed as the tube side of the heat exchanger. Heat exchange takes place between these two fluids through a tube metal. Hence, it is of prime importance that there is no mixing between the two fluids to avoid any damage to the desired quality of the output product of the process.

[0009] There are some heat exchangers which need to be designed for for low to high-pressure and temperature conditions, particularly in corrosive, hazardous, and dirty service environments.

[0010] In clean services, i.e., where the fluids being circulated through the heat exchangers are clean i.e., does not leave any residue / deposit / fouling on the inside of the heat exchanger, hence, there is no cleaning or maintenance needed for these heat exchangers. The tube bundle is not required to be removed from the heat exchanger and, hence, the tubesheet is welded to the shell as well as the channel [Refer Figure 1]. Since the tubesheet is welded, there is no leakage of internal fluid to the atmosphere.

[0011] In fouling / dirty services, the fluids being circulated inside the heat exchanger causes residue and sludges being deposited on the internal parts of the heat exchanger. These depositions impact thermal performance of the heat exchanger, that results in reduction of heat transfer and thereby the thermal efficiency of the heat exchanger. Hence, it becomes imperative to remove the tube bundle from the exchanger for cleaning of the depositions and other maintenance activities to restore the desired thermal efficiency / output of the heat exchanger. This forces a gasketed joint between the tubesheet channel girth flange (14) and shell / channel girth flange (12) [Refer Figure 2], so that the girth flanges can be de-bolted, and the tube bundle can be removed from the heat exchanger.

[0012] Figure 2 represents a conventional [prior art] U tube type conventional [prior art] shell and tube type heat exchanger that has a tubesheet (10) held (sandwiched) between the shell side girth flange (12) and tube side girth flange (14).

[0013] Figure 3 represents a conventional [prior art] floating tubesheet type (straight tube) shell and tube heat exchanger that too has its stationary tubesheet (10) held (sandwiched) between the shell side girth flange (12) and tube side girth flange (14).

[0014] Since the tubesheet (10) is gasketed with the shell / channel flange (20c), same bolts are used for compressing two gaskets (13) to ensure leak tightness of two different pressurized chambers i.e., shell side / tube side. Hence, there is bound to be some leakage to the atmosphere after a few months of service. Leakages in the case of hazardous fluids can cause damage to the environment, and leakage of toxic gases can be lethal to living organisms. Besides, these leakages also reduce the efficiency of the heat exchanger. Leakages through the gasket may require replacement of the gasket. This may lead to an unplanned shutdown of the heat exchanger / overall plant, which in turn will lead to production losses.

[0015] Further, having a conventional flanged / gasketed joint assembly between the tubesheet to shell / channel flange requires large bolt sizes to seat the gasket properly. This, in turn, leads to larger diameters of tubesheet / shell flange / channel flange. Larger diameters mean higher weight of these components and thereby higher costs of these heat exchangers.

[0016] Additionally, in prior arts (Figure 3a) of screw plug design, bolts were internal and on the cover. In such prior arts, groove, in channel barrel, which is a high-stress concentration zone leads to fissures and cracks leading to leakages. Furthermore, these internal bolts had to be far away from gaskets (13), and load on gaskets (13) had to be transferred through internal cylinder (21) and internal flange (21) which was because of the dimension limitations. The applied load was not only further away from the shell side gasket (13), but also the point of application of this load was away from the centreline of the shell side gasket. Owing to large distances, there was difficulty in transmitting the load effectively.

[0017] Therefore, there is a need to address these problems.

[0018] OBJECTS OF THE INVENTION:

[0019] An object of the invention is to achieve emission proof heat exchangers.

[0020] Another object of the invention is to achieve an improved shell and tube type heat exchanger that offers zero carbon emissions, improved performance, cost-effectiveness, and reliability for applications requiring a shell and tube exchanger in challenging operating conditions.

[0021] Yet another object of the invention is to achieve an improved shell and tube type heat exchanger such that there is no leakage of internal fluid to the atmosphere, thereby preventing any release of toxic fluids / flammable fluids that can prove hazardous to the property as well as humans / living organisms.

[0022] Still another object of the invention is to achieve an improved shell and tube type heat exchanger such that there is improvement in thermal efficiency of the heat exchanger by reducing the leakages of fluid to the atmosphere.

[0023] An additional object of the invention is to achieve an improved shell and tube type heat exchanger such that there is provided a compact design of the tubesheet to shell / channel assembly that not only reduces the weight of the heat exchanger, but also the cost of the heat exchanger.

[0024] Another additional object of the invention is to achieve an improved shell and tube type heat exchanger such that there is provided a compact design of the heat exchanger that can be easily maintained, i.e., without the need to cut any weld joint, which makes maintenance very complicated / cumbersome and time-consuming activity. Yet another additional object of the invention is to achieve an improved shell and tube type heat exchanger such that its tube bundle can be removed from the heat exchanger for maintenance without the need for dismantling the nozzle to pipe joints.

[0025] Still another additional object of the invention is to achieve an improved shell and tube type heat exchanger such that it enables conversion of nozzle to pipe joints of welded type from a flange type joint construction; thereby, reducing potential leak paths - thereby, ensuring highest efficiency.

[0026] SUMMARY OF THE INVENTION:

[0027] According to this invention, there is provided an emission-proof heat exchanger comprising a shell-side assembly and a tube-side assembly: a tubesheet, and an internal cylinder, with gaskets, said tubesheet located inside a shell, characterized in that, said exchanger consisting, essentially, of: said shell being welded to said channel barrel, directly; an internal cylinder configured to be located between said tubesheet and an internal sleeve by means of inner push bolts on a thread lock ring; a thread lock ring having external threads that are engaged with internal threads provided on an inside at an end of said channel barrel, said thread lock ring being configured to be coaxial to said internal cylinder and ensconced within a co-axial, concentric, shrink ring located at an end of said channel, said thread lock ring being located closer to a centre of said tubesheet gasket; a first set of fastening mechanisms being inner push bolts, mounted on said thread lock ring, configured to hold said shell-side gasket in its position by compressing said shellside gasket held between said tubesheet and the shoulder of the shell; a second set of fastening mechanisms being external push bolts, mounted on said thread lock ring, configured to hold said tube-side gasket in its position by compressing said tube-side gasket held between said thread lock ring and a shoulder on said channel through an outer compression ring and a diaphragm; o said tubesheet compressing said shell-side gasket against a shoulder on said shell by means of said inner push bolts through an internal cylinder, a sleeve, a diaphragm, and inner compression ring, all co-axially aligned; and o said tube side gasket configured to retain tube-side fluid inside said channel and being held against said shoulder in said channel by means of said outer push bolts though an outer compression ring and said diaphragm.

[0028] The verification of the soundness of the tube to tubesheet joint can be carried out by pressurising the shell side, with the tubesheet and shell side gasket in position, following by the internal cylinder, internal sleeve, inner compression ring and inner push bolts fitted in the thread lock ring. During this test, the channel cover and diaphragm, outer compression ring.

[0029] In at least an embodiment, said first set of fastening mechanisms being inner bolts.

[0030] In at least an embodiment, said second set of fastening mechanisms being outer bolts.

[0031] In at least an embodiment, said internal cylinder configured to be co-axial and in communication with said shell-side gasket on one of its axial sides and configured to be coaxial and in communication with said tube-side gasket on its other axial side.

[0032] In at least an embodiment, said exchanger comprising an inner compression ring acting as a load transfer medium from the inner push bolts to the shell side gasket through the diaphragm, sleeve, internal cylinder, and tubesheet in order to distribute bolt loads uniformly across the width of the diaphragm.

[0033] In at least an embodiment, said exchanger comprising a sleeve acting as a distance piece between a diaphragm and said internal cylinder in order to transfer load from the inner push bolts to the shell side gasket.

[0034] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

[0035] Figure 1 represents a heat exchanger where tubesheet is welded to the shell as well as the channel;

[0036] Figure 2 represents a conventional U tube type conventional [Prior art] shell and tube type heat exchanger that has a tubesheet held (sandwiched) between the shell side girth flange and tube side girth flange; Figure 3 represents a conventional floating tubesheet type (straight tube) shell and tube heat exchanger that too has its stationary tubesheet held (sandwiched) between the shell side girth flange and tube side girth flange; and

[0037] Figure 3a illustrates prior art heat exchanger’s split ring, split ring groove, internal flange, and internal set screws.

[0038] The invention will now be described in relation to the accompanying drawings, in which:

[0039] FIGURE 4 illustrates a heat exchanger which incorporates this invention’s tubesheet to the shell / channel joint assembly;

[0040] FIGURE 5 illustrates an exploded view of the emission-proof heat exchanger; and

[0041] FIGURE 6 illustrates a zoomed-in view of a portion of the emission-proof heat exchanger.

[0042] DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

[0043] Figure 1 represents a heat exchanger where tubesheet is welded to the shell as well as the channel;

[0044] Figure 2 represents a conventional U tube type conventional [Prior art] shell and tube type heat exchanger that has a tubesheet held (sandwiched) between the shell side girth flange and tube side girth flange; and

[0045] Figure 3 represents a conventional floating tubesheet type (straight tube) shell and tube heat exchanger that too has its stationary tubesheet held (sandwiched) between the shell side girth flange and tube side girth flange.

[0046] Figure 3a illustrates prior art heat exchanger’s split ring, split ring groove, internal flange, and internal set screws.

[0047] In the prior art [Refer Figure 2], the shell flange (12) is assembled to the tubesheet (10) and the channel flanges (14) through gasket (11, 13) and bolts (23). Here, the gasketed joint forms path for potential leak. In prior arts, to remove the tube bundle (10), the channel (20) has to dismantled and the piping connected to the channel (20) has to be removed, making it time consuming and nozzle flange to piping as potential leak path for leak to atmosphere.

[0048] Similarly, considering the channel flange (20c) to cover (20d) joint, in order to arrest these leaks, more bolt load is needed, for which higher bolt sizes are needed. The flange (20d, 14, 12, 30b) outside diameters being larger, resulting in higher weights and thereby the cost of the exchanger.

[0049] Typically, shell side gasket (11) held between the tubesheet (10) and the shoulder of shell (30). This helps in containing the shell side fluid and prevents any inter-mixing between the shell side fluid and the tube side fluid.

[0050] Typically, all the tubes are welded to the tubesheet (10). This tubesheet (10) acts as a common element between the channel (20) and the shell assembly. This tubesheet (10) separates the shell side fluid and the tube side fluid. It prevents inter-mixing between the shell side fluid and the tube side fluid.

[0051] Typically, shell (30) contains the shell side fluid. This fluid on the outside of the tubes (10).

[0052] Typically, the tube side fluid is circulated in the channel (20).

[0053] Typically, internal cylinder (21) houses a pass partition plate assembly that divides the channel (20) into a number of sections so that the tube side fluid can be circulated through the tubes based on the number of passes desired by the thermal design for higher thermal efficiency. The internal cylinder (21) also acts as a load transfer medium. The bolt load of the inner push bolts (22a) is transmitted to the shell side gasket (11) through the tubesheet internal cylinder and the sleeve.

[0054] Typically, tube side gasket (13) acts as seal for containing the tube side fluid inside the channel assembly. This tube side gasket is compressed by the outer push bolts (22B), through the outer compression ring (32) and diaphragm (34).

[0055] Typically, outer compression ring (32) acts as a load transfer medium from the outer push bolts (22b) to the tube side gasket (13). It distributes the bolt loads uniformly across the width of the tube side gasket (13).

[0056] Typically, thread lock ring (15) houses the outer push bolts(22B), inner push bolts (22A), inner compression ring (31), outer compression ring (31). The thread lock ring (15) has external ACME threads that engage with the internal threads on the channel barrel (20). The entire force owing to tube side internal pressure and the bolting tightening loads of inner push bolts (22a) and external push bolts (22b) are withstood by the thread lock ring (15).

[0057] Typically, channel cover (16) resists the force exerted by the tube side fluid pressure. The force acting on the channel cover (16) is then transferred to the thread lock ring (15).

[0058] Typically, inner compression ring (31) acts as a load transfer medium from the inner push bolts (22A) to the shell side gasket (11) through the diaphragm (34), sleeve (24), internal cylinder (21), and tubesheet (10). It distributes the bolt loads uniformly across the width of the diaphragm (34).

[0059] Typically, inner push bolts (22a) are used to compress the shell side gasket (11). The force exerted by tightening the inner push bolts (22a) is used to contain the shell side fluid pressure.

[0060] Typically, shrink ring (60) is fitted on the outside diameter of the threaded end of the channel barrel (20) by shrink fitting. This shrink fitting process exerts additional compressive stress on the threaded end of the channel barrel which helps in minimizing the deformation / deflection of the threaded end of the channel barrel (20). The tapered threads of thread lock ring (15) cause flaring / bending of the threaded end of the channel barrel (20) in radially outward direction, commonly known as bell mouthing. This shrink ring (60) prevents bell mouthing of the threaded end of the channel barrel (20) and thereby ensuring positive engagement between the external threads on the thread lock ring (15) and the internal threads on the channel barrel (20).

[0061] Typically, diaphragm (34) is a flexible sheet that helps in containing the tube side fluid with the help of tube side gasket (13). This diaphragm (34) is supported by the channel cover (36) and the thread lock ring (15).

[0062] Typically, internal sleeve (24) acts as a distance piece between the diaphragm (34) and the internal cylinder (21). It helps in transferring the load from the inner push bolts (22a) to the shell side gasket (11).

[0063] In prior art flanges (20c, 30b, 12, 14), maintenance becomes challenging as large size bolts are required to be assembled / dismantled for overhauling. Bolts (23), on the channel cover (36), to flange (20c) are under tension. Under tension, the bolts (23) are more vulnerable to relaxation and fatigue leading to relaxation of stress on gasket (11, 13) and thereby prone to leak through gasketed joint.

[0064] Reference numeral 20a: channel / tube inlet nozzle

[0065] Reference numeral 25: pass partition plate

[0066] Reference numeral 20b: channel / tube outlet nozzle

[0067] Reference numeral 30a: shell inlet nozzle

[0068] Reference numeral 30b: shell flange

[0069] Reference numeral 30c: shell outlet nozzle

[0070] Reference numeral 30d: shell cover flange

[0071] Reference numeral 30e: shell cover

[0072] Reference numeral 33: floating tubesheet

[0073] Reference numeral 20c: channel flange

[0074] Reference numeral 20d: channel corner

[0075] Reference numeral 23: bolt + nut

[0076] FIGURE 3a illustrates prior art heat exchanger’ s split ring, split ring groove, internal flange, and internal set screws.

[0077] The screw plug closures, of prior arts are without an additional shrink ring at the threaded end of the channel barrel. Prior art exchangers, had an internal flange, split ring (27), and split ring groove (29). This split ring groove (29) causes high stress concentration in the channel barrel (20), and has potential to develop fissures and cracks. As evident from Figure 3a, the prior art design had internal flange and split ring (27), this lead to increase in the overall length of the channel barrel (20) by 350 mm to 500 mm. The point of application of the inner bolts, on the cover, is at a certain offset distance from the tubesheet gasket centre line.

[0078] In exemplary embodiments, of prior art, of tube to tubesheet joint for a corrosion resisting applications, wherein the tube is welded to the weld overlaid surface on the tubesheet, weld size resisting pressure is 1.651 x 2 = 3.302 mm According to this invention, there is provided an emission-proof heat exchanger.

[0079] FIGURE 4 illustrates a heat exchanger which incorporates this invention’s tubesheet to the shell / channel joint assembly.

[0080] FIGURE 5 illustrates an exploded view of the emission-proof heat exchanger.

[0081] FIGURE 6 illustrates a zoomed-in view of a portion of the emission-proof heat exchanger.

[0082] In at least an embodiment, the shell (30), of the heat exchanger, is welded to a channel (20). Reference numeral 40 refers to tube of the heat exchanger. Outside diameter, of the tubesheet (10), is reduced to an extent that it is completely housed / ensconced within the channel (20). The tubesheet (10) is held against the shell (30) through a shell side gasket (11). This shell side gasket (11) prevents intermixing of the shell side fluid and the tube side fluid. The channel side fluid is contained with the channel side gasket (13) / tube side gasket (13).

[0083] In at least an embodiment, fastening mechanisms (22b) hold the channel side gasket (13), in its position; the fastening mechanisms mounted on a thread lock ring (15) of the heat exchanger.

[0084] In at least an embodiment, an internal cylinder (20) is configured to be located between the channel side and the shell side of the heat exchanger. The thread lock ring (15) has, preferably two sets of fastening mechanisms (22), mounted on it. Preferably, there are inner bolts (22a) and push rods which are used to compress the shell side gasket (13) held between the tubesheet (10) and the shell though an internal sleeve (24) and an internal cylinder (20). Preferably, there are outer push bolts (22b) and push rods on the thread lock ring (15) which are used to compress the channel side gasket (13) held between the thread lock ring (15) and the channel (20) through an outer compression ring (32) and a diaphragm (34).

[0085] Owing to the constructional features, of this invention, now, external bolts (22a) is on thread lock ring (15). Split ring, and flange (30b), of the prior art, has been removed. Gasket (13) is tightened without the need of flange, split ring, and internal bolts of prior arts. Gasket (11, 13) is tightened by inner bolts + external bolts (22a, 22b).

[0086] Axial alignment of inner bolts + external bolts (22a,) is now close to the gaskets (11). The tubesheet (10) compresses said shell-side gasket (11) against a shoulder on said shell (30) by means of said inner push bolts (22a) through an internal cylinder (21), a sleeve (24), a diaphragm (34), and inner compression ring (31), all co-axially aligned.

[0087] The tube side gasket (13) is configured to retain tube-side fluid inside said channel (20) and being held against said shoulder in said channel (20) by means of said outer push bolts (22b) though an outer compression ring (32) and said diaphragm (34).

[0088] Owing to the tapered threads on the thread lock ring (15), hydrostatic end force exerted by the pressure of tube-side fluid causes the threaded end of the channel barrel (20) to bend / flare outwards. This shrink ring (60) fitted at the end of the channel barrel (20) prevents this bending ensuring proper engagement between the threads of the thread lock ring (15) and channel barrel (20).

[0089] Owing to the invention’s constructional modifications, there is no leakage to the atmosphere through the shell side gasket. Further, even the channel gasket leak tightness is reinforced owing to multiple loads on the channel gasket induced by the outer push bolts (part of the fastening mechanism), the thread lock ring (15) and the channel cover assembly (36); wherein, most of the hydrostatic end forces are withstood by the thread lock ring (15) and the channel cover assembly (36).

[0090] Reference numeral 60: added steel / shrink ring

[0091] Reference numeral 36 cover

[0092] Reference numeral 24: sleeve

[0093] Reference numeral 66: partition cover gasket

[0094] Reference numeral 68: channel nozzles

[0095] Reference numeral 69: partition cover plate

[0096] Further, to achieve an optimal thermal design and cost reduction, the exchanger is engineered with an increased efficiency and stringent tolerance control to minimize leak paths and improve flow. This includes using lower tolerance for baffle holes to tube and shell inside diameter to baffle outside diameter clearances.

[0097] In the current invention, the shell flanges (12) and channel flanges (14) are eliminated, and the shell (30) is welded to the channel (20), thereby eliminating the path for potential leaks to the atmosphere. In the current invention, in order to remove, the tube bundle, the channel (20) is not required to be removed; hence, the channel nozzles (20b) can be directly welded to piping and, thereby, reduce the path for potential leaks. Since there are no shell flange (30b) / channel flanges (20c), weight of the exchanger is reduced and, thereby, the cost is also reduced.

[0098] In the current invention, bolts required are of smaller size and, hence, it is easy to assemble and dismantle the assembly; which makes it maintenance friendly.

[0099] In the current invention, the push bolts / rods on the channel cover (36) are under compression and, hence, offer a highly reliable and leak tight gasketed joint in comparison to prior art flange joints.

[0100] Owing to the tapered flanks of the Acme thread at channel barrel open end, whenever force is applied due to channel pressure, the tapered flanks of the Acme thread casue bending of the open end of the channel barrel causing bell mouthing. The added steel / shrink ring (60), at the threaded end of the channel barrel, prevents such kind of bending and ensures maximum engagement between the mating threads of the channel barrel and the thread lock ring. This, in turn, helps in ensuring / mainlining leak tightness of the channel gasketed joint.

[0101] In the current invention, the split ring groove has been removed.

[0102] In the current invention, there are no internal flanges and split ring and, hence, the design of the channel barrel is more impact with reduced chanenl length.

[0103] The point of application inner bolts on the thread lock ring (15) is closer to the centre of the tubesheet gasket, and hence, bolt tightening load is applied more effectively.

[0104] The bolt circle diameter of the inner push bolts being of larger, more number of bolts can be accomodated and thereby more bolt load can be applied effectively / uniformly.

[0105] Owing to reduced weight of the channel assembly, the current invention offers, economic advantage over the prior art design. In exemplary embodiments, of the current invention, of improved tube to tubesheet joint details for a corrosion resisting application that can be applied case to case basis, wherein the tube is first welded to the CS base metal tubesheet, and space between the tubes is then filled with corrosion resistant weld metal. Here the weld size resisting the pressure = 6 mm+1.651 = 7.51 mm. Hence, this joint detail offers better mechanical reliability in comparison to the prior art method. Further, since weld deposition of corrosion resisting weld metal is carried only in the spaces between the tubes, this arrangement offers cost advantage, as the weight of the weld deposition is reduced.

[0106] One notable aspect is the internal shell to tubesheet joint, which follows the Hi-Hi type of construction, ensuring improved reliability and durability. Additionally, the channel barrel to the end cover utilizes a screw plug type construction, further enhancing efficiency.

[0107] The block emission technology implemented, in this invention, ensures a tight and secure internal seal, preventing any leaks that could result in energy wastage. By minimizing these losses, the exchanger can operate at optimal levels, maximizing heat transfer efficiency and reducing the need for additional energy consumption.

[0108] Furthermore, the applicant’s own patented and technical article published in ASME PVP 2021 regarding tube to tubesheet joints allow for dissimilar metals to be welded directly to the tubesheet followed by weld deposition on the tubesheet face limited only to the space between the tubes. This not only reduces the costs, but also enhances the overall durability and mechanical reliability of the tube to tubesheet joint and hence increased reliability and performance of the exchanger.

[0109] In this invention, the inner and outer push bolts and rods on the thread lock ring used to compress the shell side gasket and channel side gasket are under compression, whereas in case of prior art shell and tube type heat exchangers, the flange bolts are under tension. Under tension, the bolts are more vulnerable to relaxation and fatigue leading to relaxation of stress on the gasket and thereby prone to leak through the gasketed joint. Therefore, this invention’s exchangers wherein fastening mechanisms are under compression, offer a highly reliable and leak tight gasketed joint in comparison to the conventional shell and tube type heat exchanger. According to a non-limiting exemplary embodiment, a comparison was done to compare design and details / weights of a prior art shell and tube heat exchanger with that of this invention’s exchanger designed to same design pressure and temperature, size, and thermal design parameters. The following observations were made:

[0110] Shell side Design Pressure = 1.896 MPa; Shell side Design Temperature = 399 Deg. C Tube side Design Pressure = 7.171 MPa; Tubes side Design Temperature = 399 Deg. C

[0111] Size = 1 194 mm Shell ID

[0112] Weight of a conventional shell and tube type heat exchanger construction with regular gasketed tubesheet and flanges [Refer Figure 2] = 32050 Kg

[0113] Similarly, weight of an Emission-proof heat exchanger [Refer Figure 4] = 26050 Kg Therefore, the reduction in total weight of the exchanger = 32050 - 26050 = 6000 Kg

[0114] TECHNICAL ADVANTAGES:

[0115] 1. The weight of this invention’ s exchanger is much lower than the prior art shell and tube exchanger;

[0116] 2. The sizes, of fastening mechanisms, required for this invention’s heat exchanger are much lower than that required for a conventional shell and tube exchanger;

[0117] 3. Lower bolt sizes facilitate ease and quick maintenance of exchanger. Since the bolt sizes are smaller size, normal tools can be used for assembly / disassembly of bolts - special tools are not required.

[0118] 4. The heat exchanger has increased mechanical reliability and durability in comparison to the prior art’s heat exchanger.

[0119] 5. Since, there are no leakages to the atmosphere, this invention’s offers zero carbon emissions and thereby preventing any damage to the environment.

[0120] 6. There is a substantial reduction in the weight of this invention’s heat exchanger and hence the cost of the exchanger. Therefore, this invention’s heat exchanger not only offers an energy efficient exchanger but also an economical one too. This reduction in weight of this invention’s exchanger also reduces energy requirement for producing the raw material at the mill, and thus contributes to reducing the carbon emissions.

[0121] 7. This invention’s heat exchanger, being energy efficient exchanger, reduces energy needed to run the exchanger and thereby reduce the carbon emissions released to the atmosphere. 8. This invention’s design enables to convert the nozzle to pipe joints of welded type from a flange type joint construction. This further reduces the potential leak paths in the process, thereby ensuring the highest efficiency.

[0122] The heat exchangers, of this invention, combines advantages of several improvements made through: i. improved construction of the shell and tube heat exchanger; ii. improved tube to tubesheet joint; iii. improved screw plug design; to achieve an improved shell and tube type heat exchanger that offers zero carbon emissions, improved performance, cost effectiveness, and reliability for applications requiring a shell and tube exchanger.

[0123] While this detailed description has disclosed certain specific embodiments for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Claims

CLAIMS,1. An emission-proof heat exchanger comprising a shell-side assembly and a tube-side assembly: a tubesheet (10), and an internal cylinder (21), with gaskets (11, 13), said tubesheet (10) located inside a shell (30), characterized in that, said exchanger consisting, essentially, of: said shell (30) being welded to said channel barrel (20), directly; an internal cylinder (21) configured to be located between said tubesheet (10) and an internal sleeve (24) by means of inner push bolts (22a) on a thread lock ring (15); a thread lock ring (15) having external threads that are engaged with internal threads provided on an inside at an end of said channel barrel (20), said thread lock ring being configured to be coaxial to said internal cylinder (21) and ensconced within a co-axial, concentric, shrink ring (60) located at an end of said channel (20), said thread lock ring (15) being located closer to a centre of said tubesheet gasket (13); a first set of fastening mechanisms being inner push bolts (22a), mounted on said thread lock ring (15), configured to hold said shell-side gasket (11) in its position by compressing said shell-side gasket (11) held between said tubesheet (10) and the shoulder of the shell; a second set of fastening mechanisms being external push bolts (22b), mounted on said thread lock ring (15), configured to hold said tube-side gasket (13) in its position by compressing said tube-side gasket (13) held between said thread lock ring (15) and a shoulder on said channel (20) through an outer compression ring (32) and a diaphragm (34); o said tubesheet (10) compressing said shell-side gasket (11) against a shoulder on said shell (30) by means of said inner push bolts (22a) through an internal cylinder (21), a sleeve (24), a diaphragm (34), and inner compression ring (31), all co-axially aligned; and o said tube side gasket (13) configured to retain tube-side fluid inside said channel (20) and being held against said shoulder in said channel (20) by means of said outer push bolts (22b) though an outer compression ring (32) and said diaphragm (34).

2. The emission-proof heat exchanger as claimed in claim 1 wherein, said first set of fastening mechanisms (22 A) being inner bolts.

3. The emission-proof heat exchanger as claimed in claim 1 wherein, said second set of fastening mechanisms (22B) being outer bolts.

4. The emission-proof heat exchanger as claimed in claim 1 wherein, said internal cylinder (21) configured to be co-axial and in communication with said shell-side gasket (11) on one of its axial sides and configured to be co-axial and in communication with said tube-side gasket (13) on its other axial side.

5. The emission- proof heat exchanger as claimed in claim 1 wherein, said exchanger comprising an inner compression ring (31) acting as a load transfer medium from the inner push bolts (22A) to the shell side gasket (11) through the diaphragm (34), sleeve (24), internal cylinder (21), and tubesheet (10) in order to distribute bolt (22a, 22b) loads uniformly across the width of the diaphragm (34).

6. The emission-proof heat exchanger as claimed in claim 1 wherein, said exchanger comprising a sleeve (24) acting as a distance piece between a diaphragm (34) and said internal cylinder (21) in order to transfer load from the inner push bolts (22a) to the shell side gasket (11).

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