Patent Publication Number: US-2021164735-A1

Title: Plate heat exchanger for heating or cooling bulk solids

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to heat exchangers for heating or cooling bulk solids. 
     BACKGROUND 
     Indirect-heat thermal processors for heating or cooling bulk solids may utilize hot gases for heating or drying bulk solids or cool gases for cooling the bulk solids as the bulk solids flow through the heater, cooler, or dyer. The use of such gases is inefficient as large volumes of air or other gases are utilized and waste heat in the exhaust gas is difficult to recover. 
     Heat transfer plates or tubes provide improved efficiency in heat exchangers by indirectly heating or cooling bulk solids that flow, under the force of gravity, through a heat exchanger. The heat transfer plates or tubes include a heat exchange fluid flowing through the plates or tubes and the bulk solids are heated or cooled as they flow through spaces between adjacent heat transfer plates or tubes. 
     Applications for such heat exchangers vary widely. The heat transfer systems including plates or tubes referred to above are generally useful in relatively low pressure and low temperature heat exchange applications. Such heat exchangers are unsuitable in other applications in which high temperature fluids or high pressure fluids are utilized due to limitations of the heat transfer plates and tubes. For example, applications for energy recovery and storage may involve hot bulk solids and high pressure heat exchange fluid from which heat recovery is desirable. 
     Improvements to heat exchangers are desirable. 
     SUMMARY 
     According to one aspect of an embodiment, a heat exchanger includes an inlet for receiving bulk solids, a plurality of heat transfer plate assemblies, a plurality of spacers disposed between adjacent heat transfer plate assemblies, and supports for supporting the plurality of heat transfer plate assemblies. The heat transfer plate assemblies include a first sheet having a first pair of holes extending through the first sheet and channels extending along a surface thereof, for the flow of fluid from a first of the first pair of holes, through the channels, to a second of the first pair of holes, and a second sheet bonded to the first sheet to enclose the channels between the first sheet and the second sheet, the second sheet including a second pair of holes generally aligned with the first pair of holes of the first sheet to form first through holes and second through holes to facilitate flow of the fluid through the first through holes, through the channels, and through the second through holes. The spacers are disposed between adjacent heat transfer plate assemblies to space the adjacent heat transfer plate assemblies apart to facilitate the flow of the bulk solids from the inlet, between the adjacent heat transfer plate assemblies. 
     According to another aspect of an embodiment, a heat exchanger is provided. The heat exchanger includes an inlet for receiving bulk solids, a plurality of heat transfer plate assemblies arranged in banks with the heat transfer plate assemblies of each bank arranged generally parallel to each other, a plurality of spacers disposed between adjacent heat transfer plate assemblies within each bank, and supports for supporting the banks of heat transfer plate assemblies. Each heat transfer plate assembly includes a first sheet having channels extending along a surface thereof, and a second sheet bonded to the first sheet to enclose the channels between the first sheet and the second sheet. The first sheet and the second sheet together have first through holes near a first side edge of the heat transfer plate assemblies, in fluid communication with first ends of the channels, and second through holes near a second side edge of the heat transfer plate assemblies, in fluid communication with second ends of the channels to facilitate flow of the fluid through the first through holes, through the channels, and through the second through holes. The spacers are disposed between adjacent heat transfer plate assemblies within each bank, to space the adjacent heat transfer plate assemblies apart to facilitate the flow of the bulk solids from the inlet, between the adjacent heat transfer plate assemblies, the spacers including holes extending therethrough. The heat transfer plate assemblies and spacers in each bank are coupled together such that the first through holes of the heat transfer plate assemblies and holes of the spacers form a first conduit, and the second through holes and spacers form a second conduit in each bank. 
     According to yet another embodiment, there is provided a bank of heat transfer plate assemblies for use in a heat exchanger. The bank of heat transfer plate assemblies includes a plurality of heat transfer plate assemblies arranged generally parallel to each other. The heat transfer plate assemblies include a first sheet having channels extending along a surface thereof, and a second sheet bonded to the first sheet to enclose the channels between the first sheet and the second sheet, the first sheet and the second sheet together having first through holes near a first side edge of the heat transfer plate assemblies and in fluid communication with first ends of the channels, and second through holes near a second side edge of the heat transfer plate assemblies and in fluid communication with second ends of the channels to facilitate flow of the fluid through the first through holes, through the channels, and through the second through holes. The bank also includes a plurality of spacers disposed between adjacent heat transfer plate assemblies to space the adjacent heat transfer plate assemblies apart to facilitate the flow of the bulk solids between the adjacent heat transfer plate assemblies, the spacers including holes extending therethrough. The heat transfer plate assemblies and spacers in the bank are coupled together such that the first through holes of the heat transfer plate assemblies and holes of the spacers form a first conduit, and the second through holes and spacers form a second conduit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will be described, by way of example, with reference to the drawings and to the following description, in which: 
         FIG. 1  is a perspective view of a heat exchanger in accordance with an embodiment; 
         FIG. 2  is a side view of the heat exchanger of  FIG. 1 ; 
         FIG. 3  is a front view of the heat exchanger of  FIG. 1 ; 
         FIG. 4  is a front view of a sheet of a heat transfer plate assembly in accordance with an embodiment; 
         FIG. 5  is a view of spacers utilized between heat transfer plate assemblies in a bank in accordance with an embodiment; 
         FIG. 6  is an exploded perspective view of a bank of heat transfer plate assemblies in accordance with an embodiment; 
         FIG. 7  is a perspective view of a bank of heat transfer plate assemblies in accordance with an embodiment; 
         FIG. 8  is a top view of the heat exchanger of  FIG. 1 ; 
         FIG. 9  is a top view of the heat exchanger of  FIG. 1 , with the inlet removed; 
         FIG. 10  is a top view of the portion of the heat exchanger of  FIG. 9 , drawn to a larger scale. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For simplicity and clarity of illustration, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Numerous details are set forth to provide an understanding of the embodiments described herein. The embodiments may be practiced without these details. In other instances, well-known methods, procedures, and components have not been described in detail to avoid obscuring the embodiments described. The description is not to be considered as limited to the scope of the embodiments described herein. 
     The disclosure generally relates to heat exchangers for heating or cooling bulk solids, and the corresponding cooling or heating of the heat transfer fluid. The heat exchanger includes an inlet for receiving bulk solids, a plurality of heat transfer plate assemblies, a plurality of spacers disposed between adjacent heat transfer plate assemblies, and supports for supporting the plurality of heat transfer plate assemblies. The heat transfer plate assemblies include a first sheet having a first pair of holes extending through the first sheet and channels extending along a surface thereof, for the flow of fluid from a first of the first pair of holes, through the channels, to a second of the first pair of holes, and a second sheet bonded to the first sheet to enclose the channels between the first sheet and the second sheet, the second sheet including a second pair of holes generally aligned with the first pair of holes of the first sheet to form first through holes and second through holes to facilitate flow of the fluid through the first through holes, through the channels, and through the second through holes. The spacers are disposed between adjacent heat transfer plate assemblies to space the adjacent heat transfer plate assemblies apart to facilitate the flow of the bulk solids from the inlet, between the adjacent heat transfer plate assemblies. 
       FIG. 1  through  FIG. 3  show views of an embodiment of a heat exchanger  100 , which in this example is utilized for cooling bulk solids. The heat exchanger  100  includes an inlet  102  in a top of an inlet housing  104  at the top of the heat exchanger  100 , for introducing bulk solids into the heat exchanger  100 . The bulk solids may be any suitable flowable solids such as ceramic beads, sand, sintered bauxite, or any other suitable flowable solid. The inlet housing  104  provides an inlet hopper  106 . The inlet hopper  106  facilitates distribution of bulk solids that flow from the inlet  102 , as a result of the force of gravity by disbursing the bulk solids over substantially the whole cross-section of the heat exchanger  100 . 
     The heat transfer plate assemblies are arranged in rows. In the present example, the heat transfer plate assemblies  108  are arranged in eight rows, referred to as banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124 , each including a plurality of the heat transfer plate assemblies  108 . The heat transfer plate assemblies  108  in the first bank  110  are generally parallel to each other and are spaced apart to leave passageways between adjacent heat transfer plate assemblies  108  for the flow of bulk solids. Similarly, the heat transfer plate assemblies  108  of the subsequent banks  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124  are generally parallel to each other and are spaced apart to leave passageways between the adjacent heat transfer plate assemblies  108  of each of the banks for the flow of bulk solids. 
     The banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124  are arranged generally vertically with the first bank  110  at the top, followed by the second bank  112 , the third bank  114 , the fourth bank  116 , the fifth bank  118 , the sixth bank  120 , the seventh bank  122 , and the eight, or bottom bank  124 . 
     The banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124  are supported on support rails  126  that extend under the bottom bank  124  of heat transfer plate assemblies  108 . Further support rails may also be utilized, for example, between banks. Alternatively or in addition, supports may extend above one or more banks for supporting the banks from above. Although the heat exchanger  100  of  FIG. 1  includes eight banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124  of heat transfer plate assemblies  108 , other suitable numbers heat transfer plate assemblies  108  may be utilized and any suitable number of heat transfer plate assemblies  108  may be utilized in each bank. 
     The bulk solids flow through the spaces between the heat transfer plate assemblies  108 , which spaces provide the passageways through the banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124  of the heat transfer plate assemblies  108 . The bulk solids that contact the heat transfer plate assemblies  108  are deflected into the passageways. 
     The bulk solids then flow from the passageways and are discharged, for example, through a discharge hopper  148  in which the bulk solids are discharged under a “choked” flow to control the rate of flow through the heat exchanger  100 , and out of the heat exchanger  100 . In the example shown in  FIG. 1 , the discharge hopper  148  is a cone hopper. Other discharge devices and geometries may be successfully implemented, however. 
     Reference is now made to  FIG. 4 , which shows a front view of a portion of a heat transfer plate assembly  108 . A heat transfer plate assembly  108  of the heat exchanger  100  includes at least two thin sheets  402  of, for example, an alloy such as Inconel, a stainless steel, or any other suitable alloy. In the present example, the heat transfer plate assembly  108  includes four thin sheets of about 0.060 inches in thickness (1.524 mm). The sheets in the present embodiment are generally rectangular, including long edges  404  and shorter side edges  406 . The sheets  402  may be any suitable shape and size, however. In the present example, the long edges  404  are about 26 inches (66.0 cm) and the short edges are about 8 inches (20.3 cm) long. 
     Each of the sheets include a pair of holes  408 ,  410  extending through the thickness of the sheets, with a first one of the holes  408  near a first side edge  406  and the second hole  410  near the opposing side edge  406 . 
     Three of the sheets  402  include channels  412  therein. The channels  412  may be selectively etched in each sheet, for example, by photoetching to create channels  412  in a face of the sheet  402 , with the channels  412  extending continuously from the first hole  408  to the second hole  410 . The channels  412  do not extend through the entire thickness of the sheet  402 . The channels  412  are spaced from each other and are distributed between the long edges  404  of the sheet. In the present example, 13 channels  412  are shown extending from the first hole  408  to the second hole  410 . Any suitable number of channels  412  may be successfully employed, however. As indicated, the channels  412  may be formed by selectively photoetching the sheets  402 . The resulting channels  412  are generally half-circular in cross section as a result of the selective etching process. 
     The four sheets  402  that together make up the heat transfer plate assembly  108 , are stacked together such that each face  414  that includes the channels  412 , abuts an adjacent sheet  402  to enclose the channels between sheets  402 . The stack of sheets  402  is heated in a vacuum furnace with mechanical pressure applied, to cause diffusion of the sheets  402  into each other. The diffusion results in a single heat transfer plate assembly of about 0.240 inches thickness (6.096 mm) that includes the stacked sheets  402  that are diffusion bonded together. 
     In the example shown in  FIG. 4 , the channels  412  extend across the sheet  402  from the first hole  408  to the second hole  410 . Each channel  412  extends across the sheet  402  once. Alternatively, each channel may extend across the sheet more than once, such that each channel extends from the first hole, and across the sheet  402  in multiple passes before joining the second hole. The second hole may optionally be on a same side of the sheets such that both holes are near the same side edge  406  and each channel extends across the sheet  402  in an even number of passes from the first hole to the second hole. Optionally, the channels may include portions that extend generally vertically or the channels, and thus the heat transfer plate assemblies may be configured such that the channels flow substantially vertically. 
     Diffusion bonding may be carried out on several stacks of sheets  402  to create several diffusion bonded plates at a time. The diffusion bonded plates may be maintained separate by including a sheet or plate of dissimilar material that does not diffusion bond with the material of the sheets  402 , between each stack of the sheets  402  that form a single heat transfer plate assembly  108 . 
     In the above description, each sheet  402  is described as including the first hole  408  and the second hole  410 . Alternatively, the sheets may be selectively etched as described and diffusion bonded prior to creating the holes through the resulting heat transfer plate assembly  108 . 
     Referring to  FIG. 5 , spacers  502  are shown. The spacers  502  are utilized to space the heat transfer plate assemblies  108  apart in the heat exchanger  100 , to facilitate the flow of bulk solids between the heat transfer plate assemblies  108 . The spacers  502  are generally rectangular in the present example, and each spacer  502  includes a hole  504  extending therethrough. For the purpose of the present example, a side edge  506  of the spacers  502  is about the length of a side edge  406  of the sheets  402 . The top and bottom edges  508  of the spacers  502 , however, have a length that is significantly shorter than the long edges  404  of the sheets  402 . The holes  504  extending through the spacers are similar in size to the holes in the sheets  402 . The spacers  502  may be any suitable thickness to provide suitable spacing between the heat transfer plate assemblies  108  for the flow of bulk solids between the heat transfer plate assemblies  108 . For example, the spacers  502  may be about 0.25 inches (6.35 mm) thick. 
     The heat transfer plate assemblies  108  are stacked with two spacers  502  disposed between each pair of adjacent heat transfer plate assemblies  108 , as illustrated in  FIG. 6 . A side edge  506  of each of the two spacers  502  is adjacent a respective side edge  406  of each adjacent heat transfer plate assembly  108 , thus providing a space, equal to the thickness of the spacers  502 , between center portions of adjacent heat transfer plate assemblies  108 . The heat transfer plate assemblies  108  and spacers  502  are joined together to provide a single bank of the heat transfer plate assemblies  108 . The heat transfer plate assemblies  108  and the spacers  502  are aligned such that the holes  504  in the spacers  502  are aligned with the holes  408 ,  410  in the sheets. 
     As illustrated in  FIG. 7 , end plates  702  are also stacked with the heat transfer plate assemblies  108  such that each bank of heat transfer plate assemblies  108  includes two end plates  702 , with one on each end of the stack. As with the sheets  402 , each end plate  702  is generally rectangular in shape and includes side edges  704  that are about the length of the side edges  406  of the sheets  402  and long edges  706  that are about the length of the long edges  404  of the sheets. The end plates  702  may be made of any suitable material, such as Inconel or other suitable alloy. The end plates  702  are spaced from the adjacent heat transfer plate assembly  108  by spacers  502  and the end plates  702  are also joined in the stack, to the adjacent spacers  502 . The end plates  702  include nozzles  708  that align with the holes  504  in the spacers  502  and with the holes  408 ,  410  in the sheets  402 . 
     The end plates  702 , spacers  502 , and heat transfer plate assemblies  108  may all be joined together in the stack by diffusion bonding, by heating in a vacuum and under mechanical pressure. Thus, the end plates  702 , the spacers  502 , and the heat transfer plate assemblies  108  are joined together to form a single, unitary bank of heat transfer plate assemblies. Alternatively, the end plates  702 , the heat transfer plate assemblies  108 , and the spacers  502  may be bonded together by brazing or utilizing any other suitable bonding technique. 
     When joined to provide the unitary bank, the nozzles  708  of the end plates  702  are in fluid communication with the holes  504  in the spacers  502  and with the holes  408 ,  410  in the sheets  402  that form the heat transfer plate assemblies  108 . Thus, the through holes of the heat transfer plate assemblies  108  in the first bank are all in fluid communication by the spacers to form a continuous conduit, utilized as a fluid manifold through the heat transfer plate assemblies  108  and spacers  502 . Two continuous fluid manifolds are thus formed through the heat transfer plate assemblies  108  and the spacers  502  in the unitary bank. 
     The nozzles  708  may be utilized as a fluid inlet and a fluid outlet to facilitate the flow of fluid into one of the fluid manifolds formed in the heat transfer plate assemblies  108  and the spacers  502 , through the channels in the sheets  402  that form the heat transfer plate assemblies  108 , and out through the other fluid manifold formed in the heat transfer plate assemblies  108 . Thus, two integral fluid manifolds are formed in the bank of heat transfer plate assemblies  108 , for use as an inlet manifold and an outlet manifold. 
     A plurality of banks are joined together in a stack as illustrated in  FIG. 1  through  FIG. 3 . As described, the present example includes eight banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124  arranged generally vertically with the first bank  110  at the top, followed by the second bank  112 , the third bank  114 , the fourth bank  116 , the fifth bank  118 , the sixth bank  120 , the seventh bank  122 , and the eight, or bottom bank  124 . 
     Referring now to  FIG. 8 , the inlet housing  104 , which has a generally a rectangular cross-section, is coupled to the top bank  110  of the heat transfer plate assemblies  108 . The inlet housing  104  provides the inlet hopper  106  for facilitating distribution of bulk solids that flow from the inlet  102 , as a result of the force of gravity. Thus, the bulk solids are disbursed over substantially the whole cross-section of the heat exchanger  100 . 
     Referring to  FIG. 9  and  FIG. 10 , the heat transfer plate assemblies  108 , and end plates  702  are illustrated. Support ribs  1002  extend generally vertically between and abutting adjacent heat transfer plate assemblies  108 . The support ribs  1002  are included to stabilize the heat transfer plate assemblies  108  over the length of the heat transfer plate assemblies  108 . The support ribs  1002  are included to reduce the deflection of the heat transfer plate assemblies  108  when in use. As shown, the heat transfer plate assemblies  108  are closely spaced and are disposed generally vertically to facilitate the flow of the bulk solids, by the force of gravity, through the spaces between the heat transfer plate assemblies of each bank, and to the outlet  150 . Thus, the spaces between the heat transfer plate assemblies  108  in each of the banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124  provide passageways for the flow of bulk solids through the heat exchanger  100 . 
     Referring again to  FIG. 1  through  FIG. 3 , the discharge hopper  148  in the present example is a generally cone-shaped housing coupled to the bottom bank  124  via the support rails  126  on which the banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124  are supported. The cone-shaped housing is utilized to establish generally uniform bulk solids mass flow through the heat exchanger  100 . The cone-shaped housing provides a “choked flow” of bulk solids exiting the heat exchanger  100 , to control the flow rate of the bulk solids through the heat exchanger. 
     The bottom bank  124  includes an inlet flange  130  attached to a nozzle  708  of an end plate on a first side  132  of the heat exchanger  100 , which nozzle  708  is utilized as the fluid inlet to the inlet manifold formed in the heat transfer plate assemblies  108  and spacers  502 . A heat exchange fluid source is coupled to the inlet flange  130  when the heat exchanger  100  is in use, for supplying a heat exchange fluid, such as supercritical carbon dioxide, to the heat exchanger  100 . The nozzle  708  that is coupled to the end plate on an opposing side, referred to as the second side  134 , and is in fluid communication with the outlet manifold formed in the bottom bank  124 , is fluidly coupled by a fluid line  136  to the nozzle  708  that is coupled to the inlet manifold formed in the seventh bank  122 . Thus, the fluid line  136  couples the fluid outlet manifold of the bottom bank  124  to the fluid inlet manifold of the bank above (the seventh bank  122 ). A fluid line  138  coupled to the nozzle  708  on the first side  132  of the heat exchanger  100  that is in fluid communication with the fluid outlet manifold of the seventh bank  122  is coupled to the nozzle  708  that is in fluid communication with the inlet manifold of the sixth bank  120 . The coupling of fluid outlet manifolds to fluid inlet manifolds of the bank above continues such that the fluid flows in a serpentine fashion through the heat exchanger, to the top bank  110 . Thus, the inlet manifold of each of the top, second, third, fourth, fifth, sixth, and seventh banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122  is coupled to the fluid outlet manifold of the respective bank below. The remaining nozzles  708  that are not utilized for coupling an inlet flange  130 , an outlet flange  140 , or a fluid line such as the fluid lines  136 ,  138 , are plugged to substantially seal the nozzles and thereby inhibit the flow of the heat exchange fluid out of these unutilized nozzles  708 . 
     The top bank  110  includes an outlet flange  140  attached to a nozzle  708  on an end plate on a first side  132  of the heat exchanger for coupling an outlet line thereto for the flow of the heat exchange fluid, after passing through the heat transfer plate assemblies  108  and out of the heat exchanger  100 . In the present example, 8 banks are utilized and the outlet flange  140  is attached to the nozzle  708  on the end plate on the first side  132  of the heat exchanger. Alternatively, an outlet flange may be attached to a nozzle on an end plate on the second side  134  when there are an odd number of banks of heat transfer plate assemblies  108 . 
     Thus, the heat exchange fluid is utilized for indirect heat exchange with the bulk solids as the heat exchange fluid heats the heat transfer plate assemblies  108  for the transfer of heat to the bulk solids as the bulk solids flow through the heat exchanger  100 . The heat exchange fluid, however, is separate from and not in contact with the bulk solids that are heated or cooled in the heat exchanger  100 . The heat exchange fluid may be introduced to the heat transfer plate assemblies  108  at high temperature and pressure, for example, utilizing supercritical CO 2  at a pressure of 200 bar. 
     The heat transfer plate assemblies  108  of one bank may be offset from the heat transfer plate assemblies of an adjacent bank in any suitable manner. For example, an end plate  702  on one side of a bank may be thicker than the end plate  702  on the opposing side of the bank. The banks may be assembled such that the thicker end plate  702  is one side for a first bank and is on an opposing side for the adjacent bank. Thus, the thicker end plate  702  is located on alternate sides. Utilizing this assembly including banks with the thicker end plates located on alternating sides, the heat transfer plate assemblies  108  may be laterally offset such that the heat transfer plate assemblies  108  of the banks are not all vertically aligned, facilitating heating or cooling of the bulk solids. The resulting dimensions of each bank are such that the banks are similar in size and thus, the outer surfaces of the end plates  702  of one bank are vertically aligned with the outer surfaces of the end plates  702  of a subsequent bank. 
     End plates  702  of different thicknesses on alternating sides is one example of a suitable assembly for achieving an offset in the heat transfer plate assemblies  108  from bank to bank. Such an offset may be realized utilizing any other suitable assembly such that the heat transfer plate assemblies  108  of one bank  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122  are not vertically aligned with the heat transfer plate assemblies  108  of a vertically adjacent bank  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122  while maintaining similar outer dimensions of the banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 . 
     Each bank  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122  of heat transfer plate assemblies  108  is sealed by the end plates  702  and the spacers  502  that, for example, are diffusion bonded together. The banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122  may be joined together in a stack, and a seal, such as a gasket disposed between vertically adjacent banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 , for example, to inhibit both dust and air from escaping from the heat exchanger  100 . The use of such gaskets may be advantageous when a pressure differential exists between the interior of the heat exchanger  100  and outside the heat exchanger  100  or when a sweep gas is utilized. Alternatively, the banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122  may be joined together in a stack in the heat exchanger  100  without additional seals such that surfaces of vertically adjacent banks  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122  of heat transfer plate assemblies abut each other to inhibit escape of particles out of the heat exchanger  100 . 
     The operation of the heat exchanger  100  will now be described with reference to  FIG. 1  through  FIG. 3 . When bulk solids are fed into the heat exchanger  100 , through the inlet  102 , the bulk solids flow downwardly as a result of the force of gravity from the inlet  102 , into and through spaces between the heat transfer plate assemblies  108 . The bulk solids that contact the heat transfer plate assemblies  108  are generally deflected into the spaces between the heat transfer plate assemblies. As the bulk solids flow between the heat transfer plate assemblies  108 , the bulk solids are heated or cooled, depending on the application. The heat exchange fluid that flows through the heat transfer plate assemblies indirectly heats the bulk solids. 
     The bulk solids then flow through out of the discharge hopper  148 , which controls the flow of bulk solids from the heat exchanger  100 , and out the outlet  150  through which the heated or cooled bulk solids are discharged from the heat exchanger  100 . 
     In the above description, the sheets  402  are etched and diffusion bonded together to form the heat transfer plate assemblies  108 . Rather than etching, followed by diffusion bonding, the heat transfer plate assemblies  108  may be 3D printed and then bonded together. Alternatively, the channels  412  may be machined or laser cut into the sheets  402  prior to assembly. The heat transfer plate assemblies may be brazed together rather than diffusion bonded. 
     As described above, the heat transfer plate assemblies  108 , the spacers  502 , and the end plates  702  are coupled together by, for example, diffusion bonding. Alternatively, the heat transfer plate assemblies  108 , the spacers  502 , and the end plates  702  may be coupled together by tie rods that extend through the entire bank to align and maintain the heat transfer plate assemblies  108 , the spacers  502 , and the end plates  702  in the bank. The entire bank may be sealed or brazed. 
     In addition, the heat transfer plate assemblies  108  are described as formed from four sheets. Any other suitable number of sheets may be utilized to form the heat transfer plate assemblies  108 . For example, two or more sheets may be utilized to form the heat transfer plate assemblies. 
     In the above-described examples, the through holes of the heat transfer plate assemblies  108  and the spacers in the first bank are all in fluid communication to form continuous conduits, utilized as fluid manifolds. The two continuous fluid manifolds are thus formed through the heat transfer plate assemblies  108  and the spacers  502  in the unitary bank. Alternatively, spacers or sheets within the heat transfer plate assemblies may include only a single hole such that heat exchange fluid travels from the inlet manifold, through more than one heat transfer plate assembly or more than one sheet, before travelling to the outlet manifold. 
     Advantageously, the heat transfer plate assemblies  108  and the spacers  502  form integral manifolds within the banks. A very high number of relatively thin heat transfer plate assemblies  108  may be employed without requiring a separate manifold coupled to each heat transfer plate assembly  108 . High temperature and high pressure heat exchange fluid may be utilized for indirect heat exchange with the bulk solids. 
     The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole. All changes that come with meaning and range of equivalency of the claims are to be embraced within their scope.