Baffle, heat transfer conduit assembly, heat transfer section, and heat exchanger

Abstract

The present disclosure relates to a solid particle medium heat exchanger baffle. The baffle either is disk-shaped or ring-shaped and includes a support portion and a heat transfer portion. The support portion is configured to support guard rods of a heat transfer section of a heat exchanger. The support portion either has through holes into which the guard rods are insertable and in which the guard rods can rest against the baffle or ring-type members coupled to adjacent guard rods. The heat transfer portion is configured as heat transfer conduits inside the support section in a loose manner or in an open manner. The heat transfer conduits are configured to exchange heat with the solid particle medium. The heat transfer portion has at least one opening configured to accommodate at least one of the heat transfer conduits.

Description

[0001] BAFFLE, HEAT TRANSFER CONDUIT ASSEMBLY, HEAT TRANSFER SECTION, AND HEAT EXCHANGER

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Patent Application Nos. 63 / 537,423 and 63 / 544,597 filed on September 8, 2023, and October 17, 2023, respectively, both of which are incorporated herein by reference in their entirety.

[0004] TECHNICAL FIELD

[0005] The present disclosure relates to a baffle, a heat transfer conduit assembly, a heat transfer section, and a heat exchanger. Preferably, the baffle, the heat transfer conduit assembly, the heat transfer section, and the heat exchanger can be used in a fluidized bed application, more preferably in a reformer.

[0006] BACKGROUND

[0007] In some heat transfer applications, conduits transporting a heating medium can be surrounded by a medium to be heated that includes solid particles. Sometimes, the solid particles can damage the conduits, e.g., by abrasion caused by the solid particles and movements of the conduits relative to the surrounding medium. A breached conduit can cause the surrounding medium to enter the conduit. This can result in a heat transfer system shutdown and outage.

[0008] SUMMARY

[0009] Some examples of a heat exchanger according to the present disclosure can be any type of heat exchanger to be utilized in a fluidized bed environment - fired or unfired heaters, heat exchangers with electric heating rods or elements, pulse combustion heaters, steam superheaters, boiling heat exchangers, etc.

[0010] One example of a heat exchanger according to the present disclosure is a pulse combustion heat exchanger. This kind of heat exchanger is used, for example, in a steam reformer to provide heat input - a device used to gasify trash and other municipal solid waste and turn it into a gas known as “syngas” (synthesis gas that is a mixture of hydrogen and carbon monoxide).

[0011] Generally, reformers use a fluidized bed in which a solid substrate, for example sand, is heated until it resembles a fluid. In other words, a fluidized bed is a physical phenomenon that occurs when a solid particulate substance is under certain conditions so that it behaves like a fluid. The usual way to achieve a fluidized bed is to pump pressurized fluid into the particles. The resulting medium then has many properties and characteristics of normal fluids, such as the ability to free- flow under gravity, or to be pumped using fluid technologies.

[0012] Generally, a pulse combustion heat exchanger includes a heating section, a heat transfer section and a decoupler section. In the heating section, an oxidant and a fuel are mixed, for example, by using aerovalves that basically correspond to a convergent-divergent nozzle that the oxidant enters upstream of the convergent part and is mixed with the fuel in the divergent part.

[0013] Downstream of the aerovalve, the oxidant-fuel mixture is ignited by an igniter to generate a combustion stream that flows into the heat transfer section. The heat transfer section usually includes an assembly, such as a bundle, of conduits (for example, pipes or tubes) that is surrounded by a large vessel that accommodates the fluidized bed. When flowing through the conduits, the hot combustion stream transfers heat via the walls of the conduits (by heat conduction) to the fluidized bed (by heat convection). Accordingly, the heat exchanger transfers heat from a combustion process to the fluidized bed. After having transferred heat to the fluidized bed, the combustion stream flows into the decoupler section and exits the pulse combustion heat exchanger.

[0014] Generally, as mentioned above, the heat transfer section includes or is a bundle of conduits surrounded by the fluidized bed medium including solid particles.

[0015] The conduits used for the heat transfer (heat transfer conduits) are usually held together and in place by plates (solid disks) or so-called baffles spaced apart along the heat transfer conduits. In other words, the heat transfer conduits are passed through holes in the baffles and are thus supported by the baffles (they rest on the baffles).

[0016] To further improve the mechanical strength of the bundle of heat transfer conduits, support members are used. The support members are rod-shaped elements (so-called guard rods) that are typically solid (i.e. that are not tubes or pipes), and therefore have a high mechanical strength. The guard rods do not necessarily have to be solid as long as they have a higher mechanical strength than the heat transfer conduits.

[0017] Therefore, in conventionally designed heat exchangers, the assembly of the heat transfer conduits (heat transfer conduit assembly) includes, in addition to the heat transfer conduits, the baffles and the guard rods that are also passed through holes in the baffles and are thus supported by the baffles. Typically, the guard rods are arranged radially outside (or generally outside in a direction substantially perpendicular to the longitudinal direction of the assembly or the heat transfer conduits) the heat transfer conduits to provide a high stability or mechanical strength to the assembly.

[0018] The temperatures during operation of the heat exchangers can be very high. For example, pulse combustion heat exchangers tubes typically operate in a temperature range of 1100 to 1600 °F (corresponding to approximately 593 to 871 °C).

[0019] Under such conditions, thermal expansion can be challenging for the operating life of the heat exchanger. For example, it has been observed by the inventors that, in conventional heat transfer sections of heat exchangers, thermal expansion of the heat transfer conduits and the guard rods as well as the baffles differs during operation of the heat exchanger. The different thermal expansion of the components results in a situation where gaps are generated between the edges of the through holes of the baffles and the heat transfer conduits or guard rods that are inserted into the through holes and supported by the edges under low temperature conditions. In other words, under high temperature conditions, a loose fit of the heat transfer conduits and guard rods can be generated in the through holes of the baffles. In reformers using a fluidized bed (or in any other apparatuses in which a heat exchanger, such as a pulse combustion heat exchanger, transfers heat to a medium including solid particles, for example, a fluid including solid contaminations or deposits), solid particles can enter the gaps due to the loose fit caused by thermal expansion and damage the inserted heat transfer conduits and guard rods. The damage can be caused by abrasion caused by the solid particles and movements of the heat transfer conduits and / or guard rods within the through holes of the baffles. The movements can result from the fluidization dynamics i.e., flow and impact of bubbles and solids.

[0020] Due to the higher mechanical strength of the guard rods and unfired or passive role of the guard rods, the abrasion of the guard rods caused by the solid particles usually is not critical. However, the abrasion of the heat transfer conduits which are actively providing heat input to the fluidized bed and have a relatively low mechanical strength can cause the heat transfer conduits to be breached. A breached heat transfer conduit causes the surrounding medium to enter the heat exchanger which can result in system shutdown and outage.

[0021] To avoid such failure, regular control and maintenance of the heat transfer conduits would be necessary in conventional heat exchangers which would result in downtimes of the reformers (or any other apparatuses in which the heat exchangers are used). Alternatively, backup heat exchangers had to be used to avoid the downtimes. All the measures would increase costs and lower the profitability of the reformers.

[0022] It would be advantageous to: (i) protect the fired tubes or active tubes (heat transfer conduits) from the impact of relatively large bubbles and solids due to their momentum and the resulting periodic movement of the active tubes, and (ii) avoid fretting or grinding of the active tubes and local tube wall thinning due to the relative movement and / or thermal expansion of the baffles. Approaches envisioned include: (i) annular baffle design such that there is no baffle to active tube contact, and (ii) elimination of baffles with a cage-type design wherein guard tubes are connected circumferentially to collectively withstand and resist the impact of the relatively large bubbles and solids, breakup the bubbles into smaller bubbles and slow the momentum.

[0023] According to the present disclosure, “to support or supported” means that the guard rods rest on the edges of the through holes of the baffles under non-operating conditions of the heat exchanger (i.e. in a normal or low temperature environment). During operation of the heat exchanger, a loose fit can be generated between the guard rods and the baffles.

[0024] According to the present disclosure, “loosely inserted” means that the heat transfer conduits do not rest on the edges of the through holes of the baffles under non-operating conditions and under operating conditions of the heat exchanger. The loosely inserted state of the heat transfer conduits, however, does not exclude unintentional and occasional contact of the heat transfer conduits and the baffles due to movements caused by the combustion process or by the surrounding medium during operation of the heat exchanger.

[0025] According to the present disclosure, “disk-shaped” includes “ring-shaped” as well as the shape of an annulus or a torus. The disk-shape includes any shape of the baffles that have dimensions in two directions that are significantly larger than a dimension in a third (thickness) direction.

[0026] According to the present disclosure, the conventional baffles have been redesigned to generally correspond rather to a ring-shaped disc (annulus) than to a solid disk. The annulus includes through holes for supporting the guard rods and openings for loosely inserting the heat transfer conduits (and optionally some additional guard rods).

[0027] The (radially) outer and inner edges of the annulus can have any geometrical shape.

[0028] The through holes and the openings can also have any geometrical shape. Different shapes among the through holes and / or the openings are also possible in one baffle.

[0029] Generally, the present disclosure relates to a solid particle medium heat exchanger baffle. The baffle either is disk-shaped or ring-shaped and includes a support portion and a heat transfer portion. The support portion is configured to support guard rods of a heat transfer section of a heat exchanger. The support portion either has through holes into which the guard rods are insertable and in which the guard rods can rest against the baffle or ringtype members coupled to adjacent guard rods. The heat transfer portion is configured to pass through heat transfer conduits of the heat transfer section in a loose manner or in an open manner. The heat transfer conduits are configured to exchange heat with the solid particle medium. The heat transfer portion has at least one opening configured to accommodate at least one of the heat transfer conduits.

[0030] All features and embodiments disclosed herein can be combined with other features and embodiments disclosed herein as long as the combination is not obviously impossible.

[0031] Example embodiments of the baffle, the heat transfer conduit assembly, the heat transfer section, and the heat exchanger according to the present disclosure will be discussed in the following in connection with the figures.

[0032] BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 shows an exemplary heat exchanger being a pulse combustion heat exchanger.

[0034] Fig. 2 shows a part of an exemplary heat transfer section of an exemplary heat exchanger.

[0035] Figs. 3 to 14 show exemplary baffles according to the present disclosure.

[0036] Fig. 15A shows a side view of a portion of an exemplary heat exchanger with a circumferential baffle.

[0037] Fig. 15B is a perspective view of a portion of a circumferential baffle depicted in Fig. 15A.

[0038] Fig. 15C is a perspective view of guard rods in the heat exchanger of Fig. 15A coupled to an exhaust-side tubesheet of the heat exchanger. Fig. 15D depicts linear portions of a circumferential baffle coupled to guard rods.

[0039] DETAILED DESCRIPTION

[0040] Figure 1 shows an exemplary heat exchanger as a pulse combustion heat exchanger 1. The heat exchanger 1 is coupled to a vessel 2 of a reformer. The vessel includes a fluidized bed 3 including solid particles 4.

[0041] The heat exchanger 1 transfers heat to the fluidized bed 3.

[0042] The heat exchanger 1 includes a heating section 100, a heat transfer section 200 and a decoupler section 300. In the heating section 100, an oxidant O and a fuel F are mixed by using aerovalves A. In Fig. 1, only one aerovalve A is depicted. However, more than one aerovalve A may be used. The oxidant O flows into a convergent part of the aerovalve A and then into a divergent part of the aerovalve A. In the divergent part, the fuel F enters the aerovalve A and mixes with the oxidant O. In a combustion chamber 101 downstream of the aerovalve A, the oxidant-fuel mixture is ignited by an igniter (not shown) protruding into the chamber 101 to generate a combustion stream that flows into the heat transfer section 200.

[0043] The heat transfer section 200 is a bundle (an assembly) of guard rods 201, 202, heat transfer conduits 203, and baffles 204, 205 that is surrounded by the vessel 2 that accommodates the fluidized bed 3. The combustion stream enters the heat transfer conduits 203 from the combustion chamber 101 and flows through the heat transfer conduits 203 until it exits the heat transfer conduits 203 in the decoupler section 300. The cooled combustion stream exits the heat exchanger 1 via the decoupler section 300.

[0044] While flowing through the heat transfer conduits 203, the combustion stream transfers heat to the fluidized bed 3 in the vessel 2, thereby heating the fluidized bed 3.

[0045] In the direction perpendicular to the longitudinal axis L of the heat exchanger 1, the guard rods 201, 202 are exemplarily arranged on the outside. In other words, the guard rods 201, 202 enclose the heat transfer conduits 203 that are arranged inside relative to the guard rods 201, 202 in the direction perpendicular to the longitudinal axis L. By this kind of arrangement, a higher stability of the assembly can be achieved.

[0046] In the assembly, each guard rod 201, 202 and each heat transfer conduit 203 passes through at least one baffle 204, 205 (two in the example of Fig. 1). The number of the baffles 204, 205 can be one, two or any higher number.

[0047] Each baffle 204, 205 has through holes 210, into which the guard rods 201, 202 are inserted and in which the guard rods 201, 202 are supported. The guard rods 201, 202 rest on the baffles 204, 205 inside the through holes 210 (they rest on the edges of the through holes 210).

[0048] Each baffle 204, 205 further has at least one opening 220 through which at least one heat transfer conduit 203 is loosely (freely) inserted. It is desirable that more than one heat transfer conduit 203 is inserted into one opening 220. Although the heat transfer conduit 203 can occasionally and unintentionally contact the baffle 204, 205, the heat transfer conduit 203 is generally not supported by the baffle 204, 205 (it does not rest on the baffle 204, 205 inside the opening 220). In other words, the heat transfer conduit 203 has a strength that is sufficient to be arranged in the heat transfer section (in the assembly) without intermediate support between sidewalls 206 of the heat transfer section 200.

[0049] Fig. 2 shows a part of an exemplary structure of the heat transfer conduit assembly within the heat transfer section 200.

[0050] In the presented example, the guard rods 201, 202 (in Fig. 2 two guard rods are shown, however a plurality of guard rods can be used) and the heat transfer conduit 203 (in Fig. 2 only one heat transfer conduit is shown, however, it is desired to use a plurality of heat transfer conduits for optimizing heat transfer) are arranged between two sidewalls 206 of the heat transfer section 200 (only one of the sidewalls 206 is shown in Fig. 2).

[0051] One of the guard rods 201 is supported by the sidewall 206 in a cantilever manner. The other of the guard rods 202 is supported by the other sidewall (not shown) in a cantilever manner. The two exemplary guard rods 201, 202 extend in opposite directions from the sidewalls 206 towards the inner of the heat transfer section 200 parallel to the longitudinal axis L.

[0052] On their proximal sides (towards the outside of the heat transfer section 200 in the longitudinal direction along the longitudinal axis L), the guard rods 201, 202 are each supported by the sidewalls 206. On their distal sides (towards the inside of the heat transfer section 200 in the longitudinal direction) the guard rods 201, 202 are each supported by the baffles 204, 205.

[0053] In Fig. 2 the guard rods 201, 202 do not extend substantially over the whole length of the heat transfer section 200, but only from their supporting sidewall 206 to the most distal baffle 204, 205. In other words, in Fig. 2, each of the guard rods 201, 202 is inserted into all of the baffles 204, 205, but is only supported by one of the sidewalls 206.

[0054] Each guard rod 201, 202 is fixedly supported by the most distal baffle 204, 205. In other words, the guard rod 201 does not only rest inside its through hole 210 in the baffle 205 but is also connected to the baffle 205. Similarly, the guard rod 202 does not only rest inside its through hole 210 in the baffle 204 but is also connected to the baffle 204. The type of fix connection is not limited to a specific connection. It can be a permanent or a releasable connection. A releasable connection could be, for example, a threaded connection or any other releasable connection. A permanent connection could be achieved, for example, by welding, bonding, shrink fit or any other permanent connection.

[0055] Each guard rod 201, 202 is slidably inserted into its through hole 210 of any of the baffles 204, 205 that is not the corresponding most distal baffle 204, 205. In other words, the guard rod 201 is slidably inserted into a through hole 210 of the baffle 204. The guard rod 202 is slidably inserted into a through hole 210 of the baffle 205.

[0056] By the described arrangement of the guard rods 201, 202, the heat transfer conduit assembly (the heat transfer section 200) has a high mechanical strength but is also flexible enough to pick up the movements caused by the combustion process and by the fluidized bed 203.

[0057] The heat transfer conduit 203 is movably (slidably and swingably) inserted into the openings 220 of each of the baffles 204, 205. When the combustion stream flows through the heat transfer conduit 203 and heats the heat transfer conduit 203, the baffles 204, 205 and the fluidized bed 3, the heat transfer conduit 203 and the baffles 204, 205 undergo thermal expansion in a different manner.

[0058] Accordingly, in a conventional assembly, a small (undesired) gap could occur between the heat transfer conduit 203 and the baffles 204, 205 into which solid particles 4 of the fluidized bed 3 would enter and cause abrasion of the heat transfer conduit 203 that could result in a breach of the heat transfer conduit 203. In such cases, the gap is small enough for the solid particles 4 to be stuck between the heat transfer conduit 203 and the edge of the through holes of the baffle 204, 205 through which the heat transfer conduit 203 is inserted. The stuck solid particles 4 then cause frictional forces on the walls of the heat transfer conduit 203 that are large enough to damage the walls over time.

[0059] According to the present disclosure, the openings 220 of the baffles 204, 205 are large enough to accommodate the heat transfer conduit 203 such that the (desired) clearance between the heat transfer conduit 203 and the edges of the openings 220 are large enough for the solid particles 4 to freely flow in the clearance without abrading the heat transfer conduit 203 by being stuck between the heat transfer conduit 203 and the baffle 204, 205.

[0060] Figs. 3 to 12 depict examples of the baffles 204, 205 according to the present disclosure.

[0061] The baffles 204, 205 are disk-shaped. In other words, they have dimensions in two directions that are significantly larger than a dimension in a third (thickness) direction.

[0062] The baffles 204, 205 according to the present disclosure are for use in a medium including solid particles (solid particle medium).

[0063] Fig. 3 shows a ring-shaped (the shape could also be described as an annulus or could be a torus; more generally, the shape of the baffle is that of a disk having at least one opening) baffle 204, 205 having a central opening 220 that is optionally a relatively large opening. The opening is configured to accommodate the heat transfer conduits 230 (optionally all heat transfer conduits 230 of the heat transfer section 200) in a loose manner.

[0064] Therefore, the opening 220 constitutes a heat transfer portion of the baffle 204, 205.

[0065] Although it is desired that the opening 220 accommodates more than one of the heat transfer conduits 230, it is also possible, that only one heat transfer conduit 230 be inserted through the opening 220. However, a plurality of heat transfer conduits 230 enhances the heat transfer.

[0066] On the radially outside of the opening 220 (the heat transfer portion), a support portion 250 for the guard rods 201, 202 is formed. In the embodiment of Fig. 3, the support portion 250 is substantially a ring having through holes 210 into which the guard rods 201, 202 are inserted to form the heat transfer conduit assembly. When inserted in the through holes 210, the guard rods 201, 202 are supported by the support portion 250 such that they rest against the edges of the through holes 210 of the baffle 204, 205.

[0067] In the presented embodiment, the shapes of the outer edge 230 and the inner edge 240 of the support portion 250 are circular. Circular according to the present disclosure also includes substantially circular, such as oval or elliptic.

[0068] In the embodiment of Fig. 3, the through holes 210 are arranged into groups, a first group 211 and a second group 212. The groups 211, 212 of the through holes 210 in the present embodiment are constituted by through holes 210 being arranged on a virtual circle. The first group 211 is arranged on a circle having a larger radius than that of the second group. In the present embodiment, the groups 211, 212 are arranged on two concentric circles. Further, in the present embodiment, the through holes 210 of the groups 211, 212 are arranged such that the adjacent through holes 210 of the other group are always shifted in circumferential direction of the support portion 250. In other words, in the present embodiment, the maximum number of through holes 210 sectioned by a virtual (extended) radial line (radius) is one. Accordingly, the packing density of the through holes 210 can be increased without weakening the mechanical strength of the support portion 250 too much by decreasing distances between the through holes 210 too much.

[0069] Fig. 4 shows the baffle 204, 205 corresponding to that of Fig. 3 except for the shape of the inner edge 240 of the support portion 250. In the presented example, the inner edge 240 has a polygon shape. In this regard, any polygon shape can be used (e.g., triangle, rectangle, pentagon, hexagon etc.). This shape of the inner edge 240 allows adaptation of the baffle 204, 205 to the shape of the plurality of heat transfer conduits 203 inserted through the opening 220 so that the number of heat transfer conduits 203 can be maximized while still ensuring enough distance (clearance) to the inner edge 240.

[0070] Fig. 5 shows the baffle 204, 205 corresponding to that of Fig. 3 except for the shape of the outer edge 230 of the support portion 250. In the presented example, the outer edge 230 has a polygon shape. In this regard, any polygon shape can be used (e.g., triangle, rectangle, pentagon, hexagon etc.). This shape of the outer edge 230 allows adaptation of the baffle 204, 205 to the shape of the vessel 2 and / or the other elements of the heat transfer section 200.

[0071] Fig. 6 shows the baffle 204, 205 corresponding to that of Fig. 3 except for the shape of the outer edge 230 and the inner edge 240 of the support portion 250. In the presented example, the outer edge 230 and the inner edge 240 have a polygon shape. In this regard, any polygon shape can be used (e.g., triangle, rectangle, pentagon, hexagon etc.). This shape of the outer edge 230 and the inner edge 240 combines the advantages of the embodiments shown in Figs. 4 and 5.

[0072] Fig. 7 shows the baffle 204, 205 corresponding to that of Fig. 3 except for the shape of the outer edge 230 and the inner edge 240 of the support portion 250. In the presented example, the outer edge 230 and the inner edge 240 have a triangular shape. This shape of the inner edge 240 allows adaptation of the baffle 204, 205 to the shape of the plurality of heat transfer conduits 203 inserted through the opening 220 so that the number of heat transfer conduits 203 can be maximized while still ensuring enough distance (clearance) to the inner edge 240. Further, this shape of the outer edge 230 allows adaptation of the baffle 204, 205 to the shape of the vessel 2 and / or the other elements of the heat transfer section 200.

[0073] Fig. 8 shows the baffle 204, 205 corresponding to that of Fig. 3 except for the support section 250. In the presented embodiment, the support section 250 includes an outer support section 251 and an inner support section 252 that are integrally formed. The outer support section 251 is ring-shaped. The inner support section 252 is cross-shaped. A further, similar support section 250 could be achieved with an inner support section 252 having more than four arms and corresponding, for example, to a spoked wheel (not shown in the figures).

[0074] In the embodiment of Fig. 8, the through holes 210 are arranged throughout the support section 250. However, the through holes 210 could only be arranged in the outer support section 251 (not shown in the figures). In this case, the cross-shaped inner support section 252 could be used for stiffening the structure of the baffle 204, 205. In another embodiment, the through holes 210 could only be arranged in the inner support section 252 (not shown in the figures). In this case, the outer guard rods 201, 202 that are more susceptible to damage could be left out, and only the inner guard rods 201, 202 would be inserted through the baffle 204, 205 to support the mechanical strength of the heat transfer conduits assembly.

[0075] In the embodiment of Fig. 8, a plurality of openings 220 is shown. More (for example, in case of the arrangement corresponding to a spoked wheel; in case of using more than 4 arms of the inner support section 252) or less (for example, two or three) openings 220 could be used.

[0076] Fig. 9 shows the baffle 204, 205 corresponding to that of Fig. 8 except for the shape of the inner support section 252. In the presented embodiment, the inner support section 252 has only one crossbar / arm (corresponding to two connected arms of the embodiment of Fig. 8). Depending on how the baffle 204, 205 is rotated, the arm of the inner support section 252 can have any orientation, such as vertical (as shown in the figure), horizontal, or oblique / diagonal.

[0077] In the embodiment of Fig. 9, the plurality of openings 220 includes two openings 220.

[0078] In the embodiment of Fig. 9, the through holes 210 can be arranged in the inner support section 252 and / or the outer support section 251 as in the embodiment of Fig. 8.

[0079] Fig. 10 shows the baffle 204, 205 as a specific case of the baffle 204, 205 of Fig. 6. In the embodiment shown in Fig. 10, the outer edge 230 and the inner edge 240 has a rectangular shape (or even a square shape) as specific examples of polygon shapes.

[0080] Fig. 11 shows the baffle 204, 205 corresponding to that of Fig. 10 except for the support section 250. In the presented embodiment, the support section 250 includes an outer support section 251 and an inner support section 252 that are integrally formed. The outer support section 251 has a (hollow) rectangular shape. The inner support section 252 is shaped as a crossbar / arm. The crossbar can have any orientation, such as vertical, horizontal, or oblique / diagonal (as shown in the figure).

[0081] In the embodiment of Fig. 11, the through holes 210 can be arranged in the inner support section 252 and / or the outer support section 251 as in the embodiments of Figs. 8 and 9.

[0082] In the embodiment of Fig. 11, the plurality of openings 220 includes two openings 220.

[0083] Fig. 12 shows the baffle 204, 205 corresponding to that of Fig. 11 except for the shape of the inner support section 252. In the presented embodiment, the inner support section 252 is cross- shaped. A further, similar support section 250 could be achieved with an inner support section 252 having more than four arms and corresponding, for example, to a spoked wheel (not shown in the figures), however, with an outer support section 251 having a (hollow) rectangular shape.

[0084] Fig. 13 shows the baffle 204, 205 corresponding to that of Fig. 3 except for the support section 250. In the presented embodiment, the support section 250 includes an outer support section 251 , an inner support section 252, and a land section 253 that are integrally formed. The outer support section 251 is ring-shaped. The inner support section 252 has a circular shape. The land section has lands (four in Fig. 13) that are bar shaped. The number of the lands can be two, three, five or any other number. Accordingly, the number of the openings 220 can be four (as shown in the figure), two, three, fife or any other number.

[0085] The lands of the land section 253 have a strength that is high enough to support the inner support section 252 within the outer support section 251. Optionally, the lands are thinner than the arms depicted, for example, in Figs. 8, 9, 11, and 12. More optionally, the lands are too thin to accommodate the through holes 210 (they are only as large as necessary to securely support the inner support section 252 and / or their number is only as high as to securely support the inner support section 252).

[0086] Fig. 14 shows the baffle 204, 205 corresponding to that of Fig. 13 except for the support section 250. In the presented embodiment, the support section 250 includes an outer support section 251, an inner support section 252, and a land section 253 that are integrally formed. Optionally, the support section 250 also includes an opening section 254. The outer support section 251 is ring- shaped. The inner support section 252 is also ring-shaped. The land section has lands (four in Fig. 14) that are bar shaped. The lands number of the lands can be two, three, five or any other number. Accordingly, the number of the openings 220 can be four or five (as shown in the figure), one, two, three, six or any other number. The lands correspond to those in Fig. 13.

[0087] Another modification shown in Fig. 14 as compared to Fig. 13 is that the openings 220 can optionally be used for freely inserting additional guard rods 201, 202, in addition to the guard rods 201, 202 that are inserted into the through holes 210 and rest against the baffles 204, 205. These additional guard rods 201, 202 can be passed through the openings 220 in a loose manner the same way as the heat transfer conduits 203. Each of the openings 220 can be used for freely inserting the additional guard rods 201, 202.

[0088] The embodiment of Fig. 14 can be modified by adding further lands and / or further ring- shaped elements to the inner support section 252. As a result, the shape of the support section 250 can be that of a (spider) web.

[0089] The embodiments of Figs. 13 and 14 can be realized with all the presented shapes of the outer edge 230 or the inner edge 240.

[0090] If, for example, the embodiment of Fig. 14 is modified such that the outer edge 230 and the inner edge 240 are rectangular or square, and that the support section 250 has the shape of a web, the resulting shape of the support section 250 can be that of a grid or lattice.

[0091] The examples shown in Figs. 3 to 14 are not exhausting. All the depicted features such like the shapes of the outer edge 230 or the inner edge 240 of the support portion 250, the shape of the through holes 210, the shape of the openings 220, the arrangement pattern of the through holes 210 (including the arrangement pattern of the first through holes 211 and the second through holes 212 as such and relative to each other), the arrangement pattern of the openings 220, the shapes of the outer support sections 251 , the inner support sections 252, and the land sections 253 (or the support portion as a whole) are nonlimiting and can be varied as needed. Further, these features can be mixed together to form further embodiments of the baffles 204, 205 as needed. In other words, all the features are interchangeable among the embodiments depicted in Figs. 3 to 14 as long as such combinations are not obviously impossible. Additionally, further common geometrical shapes of all the features can be added to such combinations as needed.

[0092] In the examples shown in Figs. 3 to 14, the number of the through holes 210 (and also the number of the through holes 210 within the groups of through holes 210) is only exemplary. The number could be much lower or much higher as needed.

[0093] The arrangement of the through holes 210 does not necessarily have to follow a certain pattern and / or does not necessarily have to be symmetric.

[0094] In the examples, the number of openings 220 also can be increased or decreased as needed.

[0095] Fig. 15A shows a part of an exemplary structure of the heat transfer conduit assembly within a heat transfer section of a heat exchanger, such as that depicted in Fig. 1.

[0096] In the presented example, the guard rods 500, 502 and the heat transfer conduits (not shown) are arranged between sidewalls 504, 506 of the heat transfer section.

[0097] The side of the heat transfer conduit assembly at which the sidewall 504 is arranged is the combustion side. The opposite side of the heat transfer conduit assembly along the longitudinal axis, i.e., the side at which the sidewall 506 is arranged is the exhaust side.

[0098] Guard rods 500 are supported by the sidewall 504 (e.g., on the combustion side) in a cantilever manner. Guard rods 502 are supported by the other sidewall 506 (e.g., on the exhaust side) in a cantilever manner. The guard rods 500, 502 extend in opposite directions from the sidewalls 504, 506, respectively, towards the inner region of the heat transfer section parallel to a longitudinal axis of the heat transfer section.

[0099] Guard rods 500, 502 are coupled to baffles 508, 510 around a circumference of guard rods 500, 502, respectively. Baffles 508, 510 are formed by rods (e.g., solid rods or tubes) coupled (e.g., welded) to guard rods 500, 502, respectively. Baffles 508, 510 can be of any suitable diameter and material. Examples of suitable diameters include about 2.5 cm to about 5 cm. Examples of suitable materials include Incoloy 800, 800H / HT, SS310H, HR120, RA330, RA333, Haynes 214, Haynes 230, HR160, other Inconel alloys (600, 601, 602CA, 617, 625, 693, 718, etc.), Hastelloy (X, W,S, N, C-22, C-276, etc.), Austenitic stainless steel (304, 304H, 316, 316H, 321, 321 H, 347, 347H, 309, 309S, etc.), 253MA, 353MA, RA85H, AL-6XN, AC66, Sanicro 28, Sanicro 31H / HT, Haynes 556, Nimonic (70, 75, etc.) and other elevated temperature alloys.

[0100] On their proximal sides (towards the outside of the heat transfer section in the longitudinal direction along the longitudinal axis), the guard rods 500, 502 are each supported by the sidewalls 504, 506, respectively. On their distal sides (towards the inside of the heat transfer section in the longitudinal direction) the guard rods 500, 502 are each supported by the baffles 508, 510 (depicted as 508’, 510’ for clarification).

[0101] The ring type baffle 508, 510 (508’, 510’) helps distribute the impact load from the bubble dynamics to the connected guard rods 500, 502 and thereby facilitate the guard rods 500, 502 to collectively share the load and reduce the stress.

[0102] As depicted in Fig. 15A, each guard rod 500, 502 is coupled to and fixedly supported by two baffles (e.g., proximal baffle 508, 508’ and distal baffles 510, 510’). Baffles 508, 510 provide load distribution to the guard rods and add stiffness to the configuration. Advantageously, baffles 508, 510 provide minimal obstruction in the heat transfer section. Although the baffles in Fig. 15A are depicted near a midsection of the guard rods (e.g., 508, 508’) and at an end of the guard rods (e.g., 510, 510’), other embodiments can include more than two baffles (e.g., 3, 4, 5, 6 or more) coupled to guard rods at various other locations along the length of the guard rods 500, 502.

[0103] In Fig. 15A the guard rods 500, 502 do not extend substantially over the whole length of the heat transfer section, but only from their supporting sidewall 504, 506, respectively, to the most distal baffle 510, 510’, respectively. Thus, each of the guard rods 500, 502 is supported by one of the sidewalls 504, 506, respectively. In other embodiments, the guard rods 500, 502 extend over the whole length of the heat transfer section.

[0104] Using baffle 508’ as an example in in Fig. 15B, sections 512 of baffle 508’ have a radius of curvature such that the baffle 508’ is circular or substantially circular (e.g., oval, elliptical) or otherwise follows the shape of the guard rods. Sections 512 intersect the guard rods 500 and are welded (e.g., full-penetration weld plus 3 / 8” or 9.525 mm fillet weld with radius as shown, for example, by reference number 513) normal to the guard rods.

[0105] Fig. 15C depicts guard rods 500 coupled (e.g., welded) to sidewall 504. In one example, the weld is a full-penetration weld plus 3 / 8” or 9.525 mm fillet weld with radius as shown, for example, by reference number 514. By the described arrangement of the guard rods 500, 502 and baffles 508, 510, the heat transfer section has a high mechanical strength but is also flexible enough to pick up the movements caused by the combustion process and by the fluidized bed.

[0106] Fig. 15D depicts further embodiments of sections of a circumferential baffle configured to be coupled to two guard rods in a heat exchanger (e.g., guard rods 500, 502 as depicted in Fig. 15 A). In contrast to the curved sections depicted in Figs. 15A-15B, sections 520 are linear rods. In some cases, sections 520 are configured to be welded directly to each of two guard rods 500, 502 to create a circumferential baffle in the general shape of a polygon (e.g., having four or more sides). Only one exemplary weld 525 is shown in Fig. 15D. In some cases, a half coupling or coupling 522 is used to couple each end of section 520 to a guard rod 500, 505, thereby forming a circumferential baffle having linear sections. In other cases, no half couplings or couplings 522 are used and sections 520 are directly attached (e.g. welded by welds 525) to guard rods 500, 502. In some cases, sections 520 can be load distribution rods or pipes.

[0107] In some cases, more than 2 (e.g. 3, 4, 5, 6, etc.) sections 508, 510 or 508’, 510’ can be used. In some cases, these sections can be circumferential segmented / load distribution connections.

[0108] The cage-type design comprising a plurality of guard rods and a plurality of transverse circumferential baffle or ring members is intended to provide openings large enough to permit gas and solids flow through but at the same time keep the openings small enough so as to limit the impact forces on the active fire tubes. The selection of the size of the guard rods or pipes or tubes and the ring elements (rods or pipes or tubes) is to be based on the application, the operating environment, and the design life.

[0109] While some of the heat exchangers will have two side walls with guard rods attached to the opposing side walls, other heat exchangers may have just one side wall and guard rods attached only to that side wall. The annular or ring baffles will then be connecting just these guard rods.

Claims

WHAT IS CLAIMED IS:

1. Solid particle medium heat exchanger baffle, the baffle being disk-shaped or ring-shaped and including: a support portion configured to support guard rods of a heat transfer section of a heat exchanger, the support portion having through holes into which the guard rods are insertable and in which the guard rods can rest against the baffle; and a heat transfer portion configured to pass through heat transfer conduits of the heat transfer section in a loose manner, the heat transfer conduits being configured to exchange heat with the solid particle medium, the heat transfer portion having at least one opening configured to accommodate at least one of the heat transfer conduits.

2. The baffle according to claim 1, wherein the at least one opening is configured to accommodate more than one of the heat transfer conduits, and optionally multiple heat transfer conduits.

3. The baffle according to claim 1 or 2, wherein the opening is large enough to accommodate the heat transfer conduit such that a clearance between the heat transfer conduit and the edges of the openings are large enough for the solid particles to freely flow in the clearance, optionally, without abrading the heat transfer conduit.

4. The baffle according to any of the preceding claims, wherein each opening is larger than each of the through holes.

5. The baffle according to any of the preceding claims, wherein the guard rods are arranged on the outside of the heat transfer conduits in a direction perpendicular to a longitudinal axis of the heat transfer conduits.

6. The baffle according to any of the preceding claims, wherein the at least one opening accommodates all heat transfer conduits of the heat transfer section.

7. The baffle according to any of the preceding claims, wherein the support portion is substantially a ring having the through holes into which the guard rods can be inserted.

8. The baffle according to any of the preceding claims, wherein an outer edge and an inner edge of the support portion in the direction perpendicular to the longitudinal axis of the heat transfer conduits, optionally in a radial direction of the baffle, can have any shape such as circular, rectangular, square, triangular, or any polygon shape, and more optionally have different shapes.

9. The baffle according to any of the preceding claims, wherein the through holes are arranged into groups, optionally in a first group and a second group; optionally, the groups are constituted by the through holes being arranged on virtual circles or any other regular virtual shapes; more optionally, the first group being arranged on a virtual circle or any other regular virtual shape having a larger radius or dimension than that of the second group; and / or the groups being arranged on two concentric virtual circles or any other regular virtual shapes; and / or the through holes of the groups being arranged such that the adjacent through holes of the other group are always shifted in a circumferential direction of the support portion.

10. The baffle according to any of the preceding claims, wherein the support section includes an outer support section and an inner support section, that optionally are integrally formed, and more optionally can have any of a circular or polygon shape; optionally, the outer support section is ring-shaped or polygon-shaped, and the inner support section is cross-shaped, arm shaped or crossbar shaped, wherein more optionally, the number of the arms or crossbars is one or more than one and / or the orientation of the arms or crossbars is vertical, horizontal, or oblique; and / or optionally, the through holes are arranged throughout the support section or only in the outer support section, or only in the inner support section.

11. The baffle according to any of the preceding claims, wherein the support section includes an outer support section, an inner support section, and a land section that optionally are integrally formed, and more optionally can have any of a circular or polygon shape; the land section has lands that are bar shaped, and optionally, a number of the lands can be two, three, four, five or any other number, and more optionally, a number of the openings can be adapted accordingly; the lands optionally have a strength that is high enough to support the inner support section within the outer support section; and / or the lands optionally are too thin to accommodate the through holes; and / or a number of the lands is optionally only as high as to securely support the inner support section; and / or the support section optionally also includes an opening section; and / or the shape of the support section is optionally that of a web or grid or lattice.

12. The baffle according to any of the preceding claims, wherein the through hole in the support portion are arranged in an irregular pattern or in a regular pattern.

13. Heat transfer assembly including: at least one baffle according to any of the preceding claims; a plurality of guard rods supported in the support portion by being inserted in the through holes and resting against the baffle; a heat transfer conduits loosely inserted in the heat transfer portion by being accommodated in the at least one opening.

14. Heat transfer section including the heat transfer assembly according to claim 13.

15. Heat exchanger including the heat transfer section according to claim 14, wherein the heat exchanger is optionally a pulse combustion heat exchanger.

116. Heat transfer assembly including : a sidewall; a plurality of guard rods coupled or attached to the sidewall; and a plurality of elongated members, each elongated member coupled to each of two adjacent guard rods in the plurality of guard rods, wherein the plurality of elongated members forms a circumferential baffle about the plurality of guard rods.

17. The heat transfer assembly of claim 16, wherein heat transfer assembly is an electrical heater, a steam superheater, a boiler, or a pulse combustion heat exchanger.

18. The heat transfer assembly of claim 16 or 17, wherein the elongated members are arcuate and the circumferential baffle is circular or substantially circular.

19. The heat transfer assembly of claim 16 or 17, wherein the elongated members are linear and the circumferential baffle is polygonal or substantially polygonal.

20. The heat transfer assembly of any one of claims 16-19, comprising at least two circumferential baffles spaced apart longitudinally.

21. The heat transfer assembly of any one of claims 16-20, further comprising: an additional sidewall opposite the sidewall; an additional plurality of guard rods coupled to the additional sidewall; and a plurality of additional elongated members, each elongated member coupled to each of two adjacent guard rods in the additional plurality of guard rods, wherein the additional plurality of elongated members forms a circumferential baffle about the additional plurality of guard rods, wherein the plurality of guard rods extends toward the additional sidewall and the plurality of additional guard rods extends toward the sidewall.

22. The heat transfer assembly of any one of claims 16-21, comprising a plurality of circumferential or ring-shaped baffles spaced apart longitudinally.

23. The heat transfer assembly of claim 21 or 22, wherein the plurality of guard rods extends into a region bounded by the plurality of additional guard rods or vice versa.

24. Heat transfer section including the heat transfer assembly according to any one of claims 16-23.

25. Heat exchanger including the heat transfer section according to claim 24, wherein the heat exchanger is optionally a pulse combustion heat exchanger.

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