Large-scale plate-fin heat exchange device and method for hydrogen liquefaction

Abstract

The invention discloses a large plate-fin heat exchange device and method for hydrogen liquefaction, and belongs to the field of energy equipment. The heat exchange device comprises a barrel and a plate-fin heat exchanger core, and an upper annular plate and a lower annular plate are arranged at the top and the bottom of the plate-fin heat exchanger core respectively. And a cavity in the plate-fin heat exchanger core between the upper annular plate and the lower annular plate is filled with a catalyst for catalyzing ortho-parahydrogen conversion of hydrogen. The upper annular plate and the lower annular plate are each provided with a first hole and a second hole which are used for allowing hydrogen to enter and exit, so that the hydrogen inlet of the cylinder communicates with a hydrogen channel in a core of the plate-fin heat exchanger through the first hole, and the hydrogen channel communicates with the discharge outlet of the cylinder through the second hole. The plate-fin heat exchange device provided by the invention overcomes the problem that an aluminum seal head cannot be directly welded under the conditions that the design pressure of a hydrogen channel is relatively high and an opening is relatively large in a large-scale hydrogen liquefaction process, and can be applied to relatively large-scale hydrogen treatment capacity.

Description

Technical Field

[0001] The invention belongs to the field of energy equipment, and in particular relates to a plate-fin heat exchange device and method for large-scale hydrogen liquefaction. Background Art

[0002] In the hydrogen liquefaction process, the hydrogen needs to be pre-cooled with an external refrigerant, such as liquid nitrogen, liquefied natural gas, etc. The pre-cooled hydrogen is then converted to ortho-para-hydrogen through a catalytic device. After the conversion is completed, it is liquefied in a condenser through 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 good heat exchange effect, compact structure, and strong adaptability. In the current hydrogen liquefaction process, hydrogen is converted into normal and para-hydrogen in a plate-fin heat exchanger, and a refrigerant is introduced into another channel for cooling, that is, the catalytic reaction of hydrogen is completed in the plate-fin heat exchanger, and heat exchange and cooling are performed at the same time.

[0004] The catalytic device and the plate-fin heat exchanger need to be connected by a pipeline. However, the hydrogen channel pressure is usually high, and a fully open channel needs to be used to fill the catalyst. When the hydrogen processing volume is large, the opening size of the heat exchanger will reach 1500mm. If a fully open channel is used to fill the catalyst, the required head diameter will be very large. The head material of the plate-fin heat exchanger is usually 5083 material, which belongs to the Al-Mg alloy. Its strength is weak, less than half of the strength of stainless steel. In addition, a special welding method is required for the head and the core of the plate-fin heat exchanger, and the welding coefficient can only be 0.6, which makes the aluminum head too thick and difficult to manufacture.

[0005] Therefore, there is an urgent need for a plate-fin heat exchanger that can be applied to larger-scale hydrogen processing and ensure effective heat exchange. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a plate-fin heat exchange device and method for large-scale hydrogen liquefaction.

[0007] The specific technical solutions adopted by the present invention are as follows:

[0008] In a first aspect, the present invention provides a large-scale plate-fin heat exchange device for hydrogen liquefaction, comprising a cylinder and a plate-fin heat exchanger core. The cylinder is provided with a hydrogen inlet, and the plate-fin heat exchanger core is fixed in the cylinder through a plate-fin heat exchanger lug.

[0009] The top and bottom of the plate-fin heat exchanger core are respectively provided with an upper ring plate and a lower ring plate. The diameter of the upper ring plate is equal to the inner diameter of the cylinder, and the diameter of the lower ring plate is smaller than the inner diameter of the cylinder and larger than the outer diameter of the plate-fin heat exchanger core. The internal cavity of the plate-fin heat exchanger core between the upper ring plate and the lower ring plate is filled with a catalyst for catalyzing the conversion of hydrogen into normal and para hydrogen. A receiving tank for receiving the catalyst is provided below the lower ring plate.

[0010] The upper ring plate and the lower ring plate are both provided with a first hole and a second hole for hydrogen inlet and outlet. The hydrogen inlet of the cylinder is connected to the hydrogen channel inside the plate-fin heat exchanger core through the first hole. The hydrogen channel inside the plate-fin heat exchanger core is connected to the discharge port of the cylinder through the second hole. Filters are provided on the first hole and the second hole.

[0011] The lower surface of the upper ring plate is connected to a sealing ring plate with a hole in the middle having the same cross-sectional size as the upper surface of the plate-fin heat exchanger core through a detachable connector. The sealing ring plate is fixed to the side wall at the top of the plate-fin heat exchanger core. The upper surface of the lower ring plate is connected to a fixed ring plate with a hole in the middle having the same cross-sectional size as the lower surface of the plate-fin heat exchanger core through a detachable connector.

[0012] A heat flow inlet and a refrigerant inlet are provided on one side of the cylinder wall, and a heat flow outlet and a refrigerant outlet are provided on the other side of the cylinder wall. Connecting pipes are provided on the heat flow inlet, the refrigerant inlet, the heat flow outlet and the refrigerant outlet, so that the inside and outside of the cylinder are connected. The connecting pipe on the heat flow inlet is connected to the connecting pipe on the inlet of the heat flow channel in the core of the plate-fin heat exchanger through a joint pipe fitting. The joint pipe on the outlet of the hot flow channel is connected to the connecting pipe on the heat flow outlet through a joint pipe fitting. The joint pipe on the refrigerant inlet is connected to the joint pipe on the inlet of the refrigerant channel in the core of the plate-fin heat exchanger through a joint pipe fitting. The joint pipe on the refrigerant channel outlet is connected to the connecting pipe on the refrigerant outlet through a joint pipe fitting.

[0013] Preferably, the material of the cylinder is stainless steel.

[0014] Preferably, the upper ring plate and the lower ring plate are both made of stainless steel.

[0015] Preferably, the filter screen is made of stainless steel.

[0016] Preferably, the mesh size of the filter is 40 to 100 meshes.

[0017] Preferably, the discharge port is arranged on the bottom side of the cylinder.

[0018] Preferably, the sealing ring plate and the fixing ring plate are both aluminum ring plates. The sealing ring plate and the fixing ring plate are respectively fixed to the top side wall and the bottom side wall of the plate-fin heat exchanger core by welding.

[0019] Preferably, the outer diameter of the sealing ring plate is 0.6 to 1 times the inner diameter of the cylinder.

[0020] Preferably, the connecting pipe is made of stainless steel and the joint pipe is made of aluminum.

[0021] Preferably, the connecting pipe and the joint pipe are connected by steel-aluminum joint pipe fittings.

[0022] Preferably, a sealing ring capable of withstanding a low temperature of -200°C is provided between the sealing ring plate and the upper ring plate and between the fixed ring plate and the lower ring plate.

[0023] Furthermore, the sealing ring is made of polytetrafluoroethylene.

[0024] Preferably, the difference between the diameter of the lower ring plate and the fixed ring plate and the inner diameter of the cylinder is greater than 400 mm, so that construction space is left between the bottom of the plate-fin heat exchanger core and the cylinder.

[0025] In a second aspect, the present invention provides a heat exchange method using the plate-fin heat exchange device according to the first aspect, characterized in that the specific method is as follows:

[0026] Before the heat exchange device is operated, the detachable connector between the upper ring plate and the sealing ring plate is removed, and the catalyst is loaded into the core of the plate-fin heat exchanger. After the loading is completed, the upper ring plate and the sealing ring plate are tightly connected through the detachable connector.

[0027] When the heat exchange device is working, the refrigerant enters the refrigerant channel inside the plate-fin heat exchanger core through the refrigerant inlet on the cylinder, providing cooling for the hydrogen and the remaining heat flow. The remaining heat flow enters the heat flow channel inside the plate-fin heat exchanger core through the heat flow inlet on the cylinder. After the heat exchange is completed, the remaining heat flow is discharged to the heat flow outlet through the pipeline.

[0028] The hydrogen to be liquefied enters the cylinder through the hydrogen inlet, and enters the hydrogen channel in the plate-fin heat exchanger core through the first hole with a filter. The hydrogen passes through the catalyst between the upper ring plate and the lower ring plate to complete the conversion of normal and para hydrogen and heat exchange. Then it is discharged to the discharge port of the cylinder through the second hole with a filter.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention arranges the plate-fin heat exchanger inside the stainless steel cylinder, which overcomes the problem that the aluminum head cannot be directly welded in the large-scale hydrogen liquefaction process due to the high design pressure of the hydrogen channel and the large opening;

[0031] (2) The hydrogen channel of the present invention is not provided with an aluminum head, and the operator can enter the interior through the manhole on the stainless steel cylinder to load the catalyst; and, since the hydrogen channel is a fully open channel, the operator can directly observe the filling status of the catalyst;

[0032] (3) The plate-fin heat exchanger provided by the present invention does not have a head filled with catalyst, and the hydrogen entering the hydrogen channel of the plate-fin heat exchanger is more evenly distributed; compared with the conventional plate-fin heat exchanger, the pressure drop caused by the hydrogen in the present invention flowing into the hydrogen channel through the stainless steel cylinder is much smaller than the resistance of flowing into the hydrogen channel through the head filled with catalyst, so the present invention can reduce the energy consumption of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a large-scale plate-fin heat exchange device for hydrogen liquefaction provided in this embodiment;

[0034] In the figure: cylinder 1, upper ring plate 2, plate-fin heat exchanger core 3, lower ring plate 4, receiving groove 5, sealing ring plate 6, plate-fin heat exchanger lug 7 and fixed ring plate 8. DETAILED DESCRIPTION

[0035] The present invention is further described and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0036] In order to solve the problem of difficulty in manufacturing welding materials between the heat exchanger core and the head during the liquefaction of a large volume of hydrogen, a preferred embodiment of the present invention provides a Figure 1 The large-scale plate-fin heat exchange device for hydrogen liquefaction is shown. The device comprises a cylinder 1 and a plate-fin heat exchanger core 3 disposed in the cylinder 1. The plate-fin heat exchanger core 3 is fixed to the inside of the cylinder 1 through the plate-fin heat exchanger lug 7. A hydrogen inlet is provided on the cylinder 1. It should be noted that in actual large-scale hydrogen liquefaction devices, a stainless steel cylinder is often used as the cylinder 1, and of course cylinders of other materials may also be used.

[0037] There is no head between the hydrogen inlet and the plate-fin heat exchanger core 3, but a fully open opening is adopted. An upper ring plate 2 made of stainless steel is arranged on the top of the plate-fin heat exchanger core 3. A first hole is provided on the upper ring plate 2 for the liquefied hydrogen to enter the plate-fin heat exchanger core 3, so that the hydrogen inlet on the stainless steel cylinder can be connected with the hydrogen channel inside the plate-fin heat exchanger core 3 through the first hole, forming a fully open opening. A lower ring plate 4 made of stainless steel is arranged at the bottom of the plate-fin heat exchanger core 3. A second hole is provided on the lower ring plate 4 for hydrogen to be discharged from the plate-fin heat exchanger core 3, so that the hydrogen channel inside the plate-fin heat exchanger core 3 can be connected with the discharge port on the stainless steel cylinder through the second hole, forming a fully open opening.

[0038] The cavity inside the plate-fin heat exchanger core 3 between the upper ring plate 2 and the lower ring plate 4 is filled with a catalyst for catalyzing the conversion of hydrogen into normal and para hydrogen. A receiving tank 5 for receiving the catalyst is provided below the lower ring plate 4, and is used to collect the finely crushed catalyst particles discharged from the plate-fin heat exchanger core 3 by hydrogen or the catalyst particles dropped when workers replace the catalyst filler.

[0039] In order to filter a small amount of impurities in the hydrogen, protect the plate-fin heat exchanger equipment to operate normally and extend its service life, it is necessary to set a stainless steel filter on the first hole on the upper ring plate 2 and the second hole on the lower ring plate 4. In actual engineering applications, a stainless steel filter with a filtration accuracy of 40 to 100 meshes can be selected.

[0040] The lower surface of the upper ring plate 2 is connected to the aluminum sealing ring plate 6 through a detachable connector. A square hole with the same cross-sectional size as the plate-fin heat exchanger core 3 is opened in the middle of the sealing ring plate 6, and the sealing ring plate 6 is fixed to the side wall at the top of the plate-fin heat exchanger core 3 by welding. The outer diameter of the sealing ring plate 6 can be adaptively adjusted according to the inner diameter of the stainless steel cylinder. Generally, an aluminum sealing ring plate 6 with a size of 0.6 to 1 times the inner diameter of the stainless steel cylinder can be selected.

[0041] In order to further enhance the sealing between the upper ring plate 2 and the sealing ring plate 6, a sealing ring capable of withstanding low temperatures of -200°C is provided between the upper ring plate 2 and the sealing ring plate 6. In this embodiment, a sealing ring made of polytetrafluoroethylene (PTFE) is selected, but sealing rings of other materials may also be used in practical applications.

[0042] The upper surface of the lower ring plate 4 is connected to the aluminum fixed ring plate 8 through a detachable connector. A square hole with the same cross-sectional size as the plate-fin heat exchanger core 3 is opened in the middle of the fixed ring plate 8, and is fixed to the side wall at the bottom of the plate-fin heat exchanger core 3 by welding. The outer diameters of the lower ring plate 4 and the fixed ring plate 8 are both smaller than the inner diameter of the stainless steel cylinder. In practical applications, the difference between the diameter of the lower ring plate 4 and the fixed ring plate 8 and the inner diameter of the stainless steel cylinder is greater than 400 mm, so that a reasonable construction space is left between the bottom of the plate-fin heat exchanger core 3 and the stainless steel cylinder.

[0043] In order to further enhance the sealing performance between the lower ring plate 4 and the fixed ring plate 8, a sealing ring capable of withstanding low temperatures of -200°C is also provided between the lower ring plate 4 and the fixed ring plate 8. In this embodiment, a sealing ring made of polytetrafluoroethylene (PTFE) is selected.

[0044] In this embodiment, bolts are selected to connect the upper ring plate and the sealing ring plate, and the lower ring plate and the fixed ring plate. It should be noted that stud connection, screw connection and other methods can also be used for detachable connection.

[0045] When filling or emptying the catalyst inside the plate-fin heat exchanger core 3, the worker only needs to enter the cylinder through the manhole on the side wall of the stainless steel cylinder, unscrew the bolts between the upper ring plate 2 and the sealing ring plate 6 and the lower ring plate 4 and the fixed ring plate 8, and remove the upper ring plate 2 or the lower ring plate 4 to fill or empty the catalyst.

[0046] like Figure 1 As shown, a heat flow inlet is opened on the upper side of the cylinder wall of one side of the stainless steel cylinder, and a refrigerant inlet is opened on the lower side, and a refrigerant outlet is opened on the upper side of the cylinder wall of the other side, and a heat flow outlet is opened on the lower side. Stainless steel pipes are arranged on the heat flow inlet, the refrigerant inlet, the heat flow outlet and the refrigerant outlet, so that the inside and outside of the stainless steel cylinder are connected.

[0047] An aluminum pipe connection needs to be provided on the plate-fin heat exchanger core 3, and a steel-aluminum interface needs to be provided between the aluminum pipe and the stainless steel pipe for connection. The stainless steel pipe on the heat flow inlet is connected to the aluminum pipe on the heat flow channel inlet in the plate-fin heat exchanger core 3 through a steel-aluminum joint. The aluminum pipe on the heat flow channel outlet is connected to the stainless steel pipe on the heat flow outlet through a steel-aluminum joint. The stainless steel pipe on the refrigerant inlet is connected to the aluminum pipe on the refrigerant channel inlet in the plate-fin heat exchanger core 3 through a steel-aluminum joint. The aluminum pipe on the refrigerant channel outlet is connected to the stainless steel pipe on the refrigerant outlet through a steel-aluminum joint.

[0048] This embodiment also provides a method for the plate-fin heat exchange device, and the specific method is as follows:

[0049] (1) Before the heat exchange device is operated, the detachable connecting piece between the upper ring plate (2) and the sealing ring plate (6) is removed, and the catalyst is loaded into the plate-fin heat exchanger core (3); after the loading is completed, the upper ring plate (2) and the sealing ring plate (6) are tightly connected through the detachable connecting piece;

[0050] (2) When the heat exchange device is working, the refrigerant enters the refrigerant channel inside the plate-fin heat exchanger core 3 through the refrigerant inlet on the stainless steel cylinder, providing cooling for the hydrogen and the remaining heat flow; the remaining heat flow enters the heat flow channel inside the plate-fin heat exchanger core 3 through the heat flow inlet on the stainless steel cylinder; after the heat exchange is completed, the remaining heat flow is discharged to the heat flow outlet through the pipeline;

[0051] (3) The hydrogen to be liquefied enters the stainless steel cylinder through the hydrogen inlet, and enters the hydrogen channel in the plate-fin heat exchanger core 3 through the first hole with a filter; the hydrogen passes through the catalyst between the upper ring plate 2 and the lower ring plate 4 to complete the conversion of normal and para hydrogen and heat exchange; and then is discharged to the discharge port of the stainless steel cylinder through the second hole with a filter.

[0052] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A large-scale plate-fin heat exchanger for hydrogen liquefaction, characterized in that: It comprises a cylinder (1) and a plate-fin heat exchanger core (3); the cylinder (1) is provided with a hydrogen inlet; the plate-fin heat exchanger core (3) is fixed in the cylinder (1) via a plate-fin heat exchanger support ear (7); An upper ring plate (2) and a lower ring plate (4) are respectively arranged at the top and bottom of the plate-fin heat exchanger core (3); the diameter of the upper ring plate (2) is equal to the inner diameter of the cylinder (1), and the diameter of the lower ring plate (4) is smaller than the inner diameter of the cylinder (1) and larger than the outer diameter of the plate-fin heat exchanger core (3); the internal cavity of the plate-fin heat exchanger core (3) between the upper ring plate (2) and the lower ring plate (4) is filled with a catalyst for catalyzing the conversion of hydrogen into normal and para hydrogen; a receiving groove (5) for receiving the catalyst is arranged below the lower ring plate (4); The upper ring plate (2) and the lower ring plate (4) are both provided with a first hole and a second hole for hydrogen inlet and outlet; the hydrogen inlet of the cylinder (1) is connected to the hydrogen passage inside the plate-fin heat exchanger core (3) through the first hole; the hydrogen passage inside the plate-fin heat exchanger core (3) is connected to the discharge port of the cylinder (1) through the second hole; and the first hole and the second hole are both provided with filter screens; The lower surface of the upper ring plate (2) is connected to a sealing ring plate (6) with a hole in the middle having the same cross-sectional size as the upper surface of the plate-fin heat exchanger core (3) through a detachable connecting piece; the sealing ring plate (6) is fixed to the side wall at the top of the plate-fin heat exchanger core (3); the upper surface of the lower ring plate (4) is connected to a fixing ring plate (8) with a hole in the middle having the same cross-sectional size as the lower surface of the plate-fin heat exchanger core (3) through a detachable connecting piece; A heat flow inlet and a refrigerant inlet are provided on one side wall of the cylinder (1), and a heat flow outlet and a refrigerant outlet are provided on the other side wall; the heat flow inlet, the refrigerant inlet, the heat flow outlet and the refrigerant outlet are all provided with connecting pipes, so that the inside and outside of the cylinder (1) are connected; the connecting pipe on the heat flow inlet is connected to the connecting pipe on the heat flow channel inlet in the plate-fin heat exchanger core (3) through a connecting pipe fitting; the connecting pipe on the hot flow channel outlet is connected to the connecting pipe on the heat flow outlet through a connecting pipe fitting; the connecting pipe on the refrigerant inlet is connected to the connecting pipe on the refrigerant channel inlet in the plate-fin heat exchanger core (3) through a connecting pipe fitting; the connecting pipe on the refrigerant channel outlet is connected to the connecting pipe on the refrigerant outlet through a connecting pipe fitting.

2. The large-scale plate-fin heat exchange device for hydrogen liquefaction according to claim 1, characterized in that: The material of the cylinder (1) is stainless steel; the material of the upper ring plate (2) and the lower ring plate (4) are both stainless steel; and the material of the filter screen is stainless steel.

3. The large-scale plate-fin heat exchange device for hydrogen liquefaction according to claim 1, characterized in that: The mesh size of the filter is 40 to 100 meshes.

4. The large-scale plate-fin heat exchange device for hydrogen liquefaction according to claim 1, characterized in that: The discharge port is arranged on the bottom side of the cylinder (1).

5. The large-scale plate-fin heat exchange device for hydrogen liquefaction according to claim 1, characterized in that: The sealing ring plate (6) and the fixing ring plate (8) are both aluminum ring plates; the sealing ring plate (6) and the fixing ring plate (8) are respectively fixed to the top side wall and the bottom side wall of the plate-fin heat exchanger core (3) by welding.

6. The large-scale plate-fin heat exchange device for hydrogen liquefaction according to claim 1, characterized in that: The outer diameter of the sealing ring plate (6) is 0.6 to 1 times the inner diameter of the cylinder (1).

7. The large-scale plate-fin heat exchange device for hydrogen liquefaction according to claim 1, characterized in that: The connecting pipe is made of stainless steel; the joint pipe is made of aluminum; the connecting pipe and the joint pipe are connected by steel-aluminum joint pipe fittings.

8. The large-scale plate-fin heat exchange device for hydrogen liquefaction according to claim 1, characterized in that: A sealing ring capable of withstanding a low temperature of -200°C is provided between the sealing ring plate (6) and the upper ring plate (2) and between the fixed ring plate (8) and the lower ring plate (4); the sealing ring is made of polytetrafluoroethylene.

9. The large-scale plate-fin heat exchange device for hydrogen liquefaction according to claim 1, characterized in that: The difference between the diameter of the lower ring plate (4) and the fixed ring plate (8) and the inner diameter of the cylinder (1) is greater than 400 mm, so that construction space is left between the bottom of the plate-fin heat exchanger core (3) and the cylinder (1).

10. A heat exchange method using the plate-fin heat exchange device according to any one of claims 1 to 9, characterized in that: The specific method is as follows: Before the heat exchange device is put into operation, the detachable connecting piece between the upper ring plate (2) and the sealing ring plate (6) is removed, and the catalyst is loaded into the plate-fin heat exchanger core (3); after the loading is completed, the upper ring plate (2) and the sealing ring plate (6) are tightly connected through the detachable connecting piece; When the heat exchange device is in operation, the refrigerant enters the refrigerant channel inside the plate-fin heat exchanger core (3) through the refrigerant inlet on the cylinder (1), providing cooling capacity for the hydrogen and the remaining heat flow; the remaining heat flow enters the heat flow channel inside the plate-fin heat exchanger core (3) through the heat flow inlet on the cylinder (1); after the heat exchange is completed, the remaining heat flow is discharged to the heat flow outlet through the pipeline; The hydrogen to be liquefied enters the cylinder (1) through the hydrogen inlet, and enters the hydrogen channel in the plate-fin heat exchanger core (3) through the first hole with the filter screen; the hydrogen passes through the catalyst between the upper ring plate (2) and the lower ring plate (4), completing the normal-para hydrogen conversion and heat exchange; and then is discharged to the discharge port of the cylinder (1) through the second hole with the filter screen.

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