A catalyst-filled plate-fin heat exchanger

Abstract

This invention discloses a catalyst-filled plate-fin heat exchanger, belonging to the field of energy equipment. The heat exchanger includes a catalyst loading tube, a plate-fin heat exchanger core, an upper head, and a lower head. The catalyst loading tube is mounted on the upper head via a detachable sealing device and is inclined inwards. A hydrogen inlet pipe and a hydrogen outlet pipe are respectively installed inside the upper and lower heads. Both the hydrogen inlet and outlet pipes have uniformly distributed pipes with downward-facing jet holes evenly distributed on them. The plate-fin heat exchanger core consists of several fins and baffles. Adjacent pairs of baffles are connected by sealing strips on both sides, and fins are arranged between the pairs of baffles to form a medium channel. The fins are recessed in height relative to the baffles, creating a height difference between the fins and the sealing strips on both sides that facilitates the entry of catalyst into the medium channel. The plate-fin heat exchanger provided by this invention solves the problems of uneven catalyst filling and gas flow deviation caused by full catalyst filling.

Description

Technical Field

[0001] This invention belongs to the field of energy equipment, and specifically relates to a plate-fin heat exchanger filled with catalyst. Background Technology

[0002] In the hydrogen liquefaction process, the hydrogen gas first needs to be pre-cooled using an external refrigerant, such as liquid nitrogen or liquefied natural gas. The pre-cooled hydrogen then undergoes a catalytic conversion process to achieve ortho- and para-hydrogenation. After the conversion is complete, it is liquefied in a condenser using an ultra-low temperature refrigerant.

[0003] Plate-fin heat exchangers are widely used in low-temperature heat exchange fields such as air separation, petrochemicals, and hydrogen liquefaction due to their advantages of good heat exchange efficiency, compact structure, and strong adaptability. Currently, in the hydrogen liquefaction process, hydrogen undergoes ortho- and para-hydrogen conversion in a plate-fin heat exchanger, and a refrigerant is introduced into another channel for cooling. In other words, the catalytic reaction of hydrogen is completed in the plate-fin heat exchanger while heat exchange and cooling occur simultaneously.

[0004] Plate-fin heat exchangers are brazed products. The baffles are coated with brazing filler metal, which is first melted at high temperature to fill the gaps between the internal fins and the seals and baffles. Then, after cooling and solidification, the parts are welded together. Therefore, the catalyst can only be filled after the plate-fin heat exchanger has been manufactured.

[0005] Chinese invention patent application number 202111364804.6 discloses a vacuum brazed aluminum plate-fin heat exchanger for continuous catalytic conversion of ortho- and para-hydrogen. The heat exchanger's shell contains alternating baffles and plate fins, forming non-communicating hydrogen and cooling medium channels between the shell, plate fins, and baffles. Catalytic conversion agent is filled between the shell and plate fins, inside the end cap at the hydrogen inlet, and inside the end cap at the hydrogen outlet. This patented plate-fin heat exchanger directly fills the catalyst through the upper end cap, with the lower opening confirming whether the catalyst completely fills the internal space of the heat exchanger. Typically, such equipment has the following problems: (1) Due to the small opening of the plate-fin heat exchanger and the fact that the channels are not straight, dead corners are likely to exist, making it difficult for the catalyst to be filled evenly; (2) The catalyst cannot be replaced without cutting the end cap; (3) After the catalyst fills the end cap, the gas enters the end cap directly, and the flow resistance of the channel directly facing the process gas inlet and the channels on both sides of the end cap is large, which will cause flow deviation; (4) If the catalyst is not effectively screened and is filled irregularly, it is easy for some channels to form flow deviation due to excessive resistance, thereby reducing the performance of the heat exchanger.

[0006] Therefore, there is an urgent need to develop a plate-fin heat exchanger that can uniformly fill the catalyst and still maintain the heat transfer performance of the plate-fin heat exchanger after the catalyst is filled. Summary of the Invention

[0007] The purpose of this invention is to solve the problem of uneven catalyst filling in plate-fin heat exchangers in the prior art, as well as the problem of gas flow deviation caused by the catalyst filling the end cap, and to provide a plate-fin heat exchanger filled with catalyst.

[0008] The specific technical solution adopted in this invention is as follows:

[0009] The present invention provides a catalyst-filled plate-fin heat exchanger, comprising a catalyst packing tube, a plate-fin heat exchanger core, an upper end cap, and a lower end cap.

[0010] The plate-fin heat exchanger core is equipped with an upper head and a lower head, which are internally connected. A catalyst loading tube is installed on the upper head via a removable sealing device, and the catalyst loading tube is inclined inwards. A hydrogen inlet pipe and a hydrogen outlet pipe are respectively installed inside the upper and lower heads. A uniformly distributed pipe is installed inside the hydrogen inlet and outlet pipes, and jet holes are evenly distributed on the uniformly distributed pipes. The jet holes face towards the bottom of the plate-fin heat exchanger core. Filters are installed inside the hydrogen inlet and outlet pipes. A catalyst discharge port is located at the bottom of the lower head via a removable sealing device.

[0011] The plate-fin heat exchanger core consists of several fins and baffles. Adjacent pairs of baffles are connected by seals on both sides. Fins are positioned between the baffles to form a medium channel. The fins are recessed relative to the baffle height, creating a height difference between the fins and the seals on both sides that facilitates catalyst loading into the medium channel. The medium channel, upper head, and lower head are all filled with catalyst for the conversion of n- and para-hydrogen.

[0012] The plate-fin heat exchanger core has a heat inlet and a refrigerant inlet on one side via an aluminum end cap, and a refrigerant outlet and a heat outlet on the other side via an aluminum end cap. The directions of the heat inlet, refrigerant inlet, refrigerant outlet, and heat outlet are perpendicular to the directions of the hydrogen inlet pipe and hydrogen outlet pipe.

[0013] Preferably, the fins are straight fins or porous fins.

[0014] Furthermore, the pitch between the above-mentioned straight fins or porous fins is 1 to 6 mm.

[0015] Furthermore, the distance by which the above-mentioned straight fins or porous fins are recessed relative to the height of the partition plate is 1 to 5 mm.

[0016] Preferably, the aforementioned detachable sealing device is a flange cover.

[0017] Preferably, both the upper and lower end caps are aluminum end caps, and the upper and lower end caps are fixedly connected to the top and bottom of the plate-fin heat exchanger core by welding.

[0018] Preferably, the upper end cap is provided with two catalyst loading tubes, and the catalyst loading tubes are inclined inward at an angle of 15 to 60°.

[0019] As a preferred option, both the hydrogen inlet pipe and the hydrogen outlet pipe mentioned above are made of thick-walled pipes.

[0020] Preferably, the filter has a mesh size of 20 to 100.

[0021] Preferably, the catalyst is a secondary hydrogen conversion catalyst, which is obtained by grinding and screening. The catalyst is spherical and the particle diameter is in the range of 0.5 to 3 mm.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The upper end cap provided by the present invention is provided with two inwardly inclined catalyst filling pipes, which facilitates the uniform filling of the catalyst into the plate-fin heat exchanger and the end cap, avoiding the problem of uneven catalyst filling; and the internal channel of the plate-fin heat exchanger is vertical and without corners, avoiding dead corners during catalyst filling.

[0024] (2) The hydrogen inlet pipe and hydrogen outlet pipe provided by the present invention are equipped with uniform distribution pipes, which can evenly distribute hydrogen to the cross section of the seal when the head is filled with catalyst, thus avoiding the problem of gas flow deviation.

[0025] (3) The catalyst loading pipe and discharge port provided by the present invention are respectively sealed to the upper end and the lower end through a detachable flange cover. The catalyst loading pipe and discharge port are independent of the process pipeline of the heat exchanger equipment. When the equipment is shut down for maintenance, there is no need to cut the process pipeline. The catalyst can be replaced by removing and installing the flange cover.

[0026] (4) The catalyst used in this invention is polished and screened, and the particles are large and close to round, which makes the catalyst flow well and is not easy to form dead corners; and the regular catalyst is easy to form regular gaps after filling, preventing local blockage of the channel, forming flow deviation and causing a large resistance drop. Attached Figure Description

[0027] Figure 1 This is a front view of the catalyst-filled plate-fin heat exchanger provided in this embodiment;

[0028] Figure 2 This is a side view of the catalyst-filled plate-fin heat exchanger provided in this embodiment;

[0029] Figure 3 This is a schematic diagram of the straight fins provided in this embodiment;

[0030] In the diagram: 1. Catalyst filling pipe; 2. Hydrogen inlet pipe; 3. Plate-fin heat exchanger core; 4. Hydrogen outlet pipe; 5. Discharge port; 6. Upper end cap; and 7. Lower end cap. Detailed Implementation

[0031] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the present invention can be combined accordingly without mutual conflict.

[0032] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0033] To address the issues of uneven catalyst loading and gas flow deviation caused by the catalyst filling the end caps in existing plate-fin heat exchangers, this embodiment provides a preferred embodiment of a catalyst-filled plate-fin heat exchanger. The device includes a catalyst loading tube 1, a plate-fin heat exchanger core 3, an upper end cap 6, and a lower end cap 7. The specific connection methods of each component are as follows... Figure 1 and Figure 2 As shown.

[0034] The end cap is a crucial component ensuring the airtightness of a pressure vessel. It is typically connected to the vessel body by welding and is non-removable, serving a sealing function. Compared to other common end caps, aluminum end caps offer advantages such as strong corrosion resistance, good thermal conductivity, and lightweight material. Therefore, in this embodiment, an upper aluminum end cap 6 and a lower aluminum end cap 7 are fixedly connected to the top and bottom of the plate-fin heat exchanger core 3 by welding, respectively, allowing internal communication between the upper end cap 6, the plate-fin heat exchanger core 3, and the lower end cap 7.

[0035] The ortho- and para-hydrogen conversion is a slow, exothermic process involving the conversion of two quantum states into isomers. To avoid vaporization of liquid hydrogen products caused by the heat of ortho- and para-hydrogen conversion in the container and to reduce the energy consumption for reliquefaction, an ortho- and para-hydrogen conversion catalyst is used in this embodiment to accelerate the reaction rate of the ortho- and para-hydrogen conversion.

[0036] To ensure uniform catalyst filling within the plate-fin heat exchanger and head, and to avoid uneven catalyst filling, in this embodiment, two inwardly inclined catalyst loading pipes 1 are provided on the upper head 6. The inward inclination angle of the catalyst loading pipes 1 can be within the range of 15° to 60°, and the specific inclination angle can be determined based on factors such as the size of the catalyst particles to be loaded and the size of the plate-fin heat exchanger.

[0037] The catalyst loading pipe 1 and the upper end cap 6 are connected by a detachable sealing flange cover, replacing the connection method of using an end cap seal in the prior art.

[0038] A hydrogen inlet pipe 2 is horizontally installed inside the upper head 6, and a hydrogen outlet pipe 4 is horizontally installed inside the lower head. Both the hydrogen inlet pipe 2 and the hydrogen outlet pipe 4 are thick-walled pipes. A uniformly distributed pipe is installed inside both the hydrogen inlet pipe 2 and the hydrogen outlet pipe 4. The uniformly distributed pipe has evenly spaced jet holes along the length of the head to ensure that even after the head is filled with catalyst, the gas can still be evenly distributed into all channels of the heat exchanger. Furthermore, the jet holes on the uniformly distributed pipe are all oriented downwards to prevent catalyst particles from entering the pipes with the hydrogen flow.

[0039] The connection between the thick-walled pipe and the external pipe is thinned, and a filter is installed inside the thick-walled pipe. The filter mesh size can be in the range of 20 to 100 mesh.

[0040] The bottom of the lower head 7 is provided with a discharge port 5 for discharging the catalyst, and the discharge port 5 and the lower head 7 are connected by a detachable sealing flange cover. In this embodiment, the discharge port 5 is located directly below the lower head 7, which can ensure that the catalyst can be completely discharged from the equipment when the catalyst is replaced.

[0041] The plate-fin heat exchanger core 3 includes several fins, baffles, guide vanes, and seals. Adjacent pairs of baffles are connected by seals on both sides, and fins and guide vanes are arranged between the baffles, forming a sealed medium channel. The fins are recessed relative to the baffles, creating a height difference between the fins and the seals on both sides that facilitates catalyst loading into the medium channel.

[0042] The medium channel, upper head 6, and lower head 7 are all filled with catalyst. To ensure uniform catalyst filling, straight or porous fins can be used for both the guide vanes and heat exchange fins to reduce dead zones for catalyst accumulation. A pitch of 1–6 mm between the straight or porous fins is acceptable.

[0043] like Figure 3 As shown, in this embodiment, straight fins are selected, and the fin height is recessed by a distance of 1 to 5 mm relative to the partition height.

[0044] One side of the plate-fin heat exchanger core 3 has a heat inlet and a refrigerant inlet connected by an aluminum end cap, while the other side has a refrigerant outlet and a heat outlet connected by an aluminum end cap. The directions of the heat inlet, refrigerant inlet, refrigerant outlet, and heat outlet are perpendicular to the directions of the hydrogen inlet pipe 2 and the hydrogen outlet pipe 4, which can increase the contact area between the hot and cold media.

[0045] In this embodiment, the catalyst selected after grinding and screening is spherical with a particle diameter ranging from 0.5 to 3 mm. The screened catalyst particles are relatively large and nearly spherical. The particles have good flowability and are less prone to forming dead zones. Furthermore, the regularly shaped catalyst, once filled, easily forms regular voids, preventing localized channel blockage, flow deviation, and significant resistance drop.

[0046] According to the catalyst-filled plate-fin heat exchanger provided in this embodiment, the specific heat exchange method is as follows:

[0047] Open the flange cover on the upper head 6, and fill the catalyst into the upper head 6, the plate-fin heat exchanger core 3 and the lower head 7 through the two inwardly inclined catalyst filling pipes 1.

[0048] The refrigerant enters the refrigerant channel inside the plate-fin heat exchanger core 3 through the refrigerant inlet, providing cooling for the hydrogen and other heat flows. The other heat flows into the heat flow channel inside the plate-fin heat exchanger core 3 through the heat flow inlet. The hydrogen to be heat-exchanged enters the upper head 6 through the hydrogen inlet pipe 2 with a filter. The hydrogen is evenly distributed between the fins inside the plate-fin heat exchanger core 3 through the uniform distribution pipe inside the hydrogen inlet pipe 2 to complete the hydrogen heat exchange and catalysis. After completing the heat exchange and catalysis, the hydrogen is discharged from the plate-fin heat exchanger core 3 through the hydrogen outlet pipe 4 inside the lower head 7. The refrigerant and heat flow are discharged from the plate-fin heat exchanger core 3 through the refrigerant outlet and heat flow outlet, respectively.

[0049] Finally, the catalyst can be completely discharged by removing the flange cover below the end cap 7 and opening the discharge port 5, thus completing the catalyst replacement.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A plate-fin heat exchanger filled with a catalyst, characterized in that, It includes a catalyst packing tube (1), a plate-fin heat exchanger core (3), an upper head (6), and a lower head (7); The plate-fin heat exchanger core (3) is provided with an upper head (6) and a lower head (7) at the top and bottom respectively, and the upper head (6), the plate-fin heat exchanger core (3) and the lower head (7) are internally connected; a catalyst loading tube (1) is provided on the upper head (6) through a detachable sealing device, and the catalyst loading tube (1) is inclined inward; a hydrogen inlet pipe (2) and a hydrogen outlet pipe (4) are provided in the upper head (6) and the lower head (7) respectively; a uniform distribution pipe is provided in the hydrogen inlet pipe (2) and the hydrogen outlet pipe (4), and jet holes are evenly opened on the uniform distribution pipe; the jet holes are directed towards the bottom of the plate-fin heat exchanger core (3); a filter is provided in the hydrogen inlet pipe (2) and the hydrogen outlet pipe (4); a catalyst discharge port (5) is provided at the bottom of the lower head (7) through a detachable sealing device. The plate-fin heat exchanger core (3) is composed of several fins and partitions; adjacent pairs of partitions are connected by sealing strips on both sides, and fins are arranged between the pairs of partitions to form a medium channel; the fins are recessed in height relative to the partitions, so that there is a height difference between the fins and the sealing strips on both sides that facilitates the loading of catalyst into the medium channel; the medium channel, the upper end cap (6) and the lower end cap (7) are all filled with catalysts for the conversion of positive and negative hydrogen; The plate-fin heat exchanger core (3) has a heat flow inlet and a refrigerant inlet on one side through an aluminum end cap, and a refrigerant outlet and a heat flow outlet on the other side through an aluminum end cap; the directions of the heat flow inlet, refrigerant inlet, refrigerant outlet and heat flow outlet are perpendicular to the directions of the hydrogen inlet pipe (2) and the hydrogen outlet pipe (4); The fins are straight fins or porous fins; the pitch between the straight fins or porous fins is 1~6mm; the distance by which the straight fins or porous fins are recessed relative to the height of the partition is 1~5mm. The upper end cap (6) is provided with two catalyst loading tubes (1); the catalyst loading tubes (1) are inclined inward at an angle of 15~60°; The catalyst is a positive and negative hydrogen conversion catalyst; the catalyst is obtained by grinding and screening, and the catalyst is spherical with a particle diameter in the range of 0.5~3mm.

2. The catalyst-filled plate-fin heat exchanger according to claim 1, characterized in that, The removable sealing device is a flange cover.

3. The catalyst-filled plate-fin heat exchanger according to claim 1, characterized in that, The upper end cap (6) and the lower end cap (7) are both aluminum end caps; the upper end cap (6) and the lower end cap (7) are fixedly connected to the top and bottom of the plate-fin heat exchanger core (3) by welding.

4. The catalyst-filled plate-fin heat exchanger according to claim 1, characterized in that, Both the hydrogen inlet pipe (2) and the hydrogen outlet pipe (4) are made of thick-walled pipes.

5. The catalyst-filled plate-fin heat exchanger according to claim 1, characterized in that, The filter has a mesh size of 20 to 100.

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