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

Abstract

The application discloses a plate-fin heat exchange device and method for large-scale hydrogen liquefaction, and belongs to the field of energy equipment. The heat exchange device comprises a cylinder body and a plate-fin heat exchanger core body, and the top and bottom of the plate-fin heat exchanger core body are respectively provided with an upper ring plate and a lower ring plate. The internal cavity of the plate-fin heat exchanger core body between the upper ring plate and the lower ring plate is filled with a catalyst for catalyzing the conversion of normal hydrogen and parahydrogen. First and second holes for the inlet and outlet of hydrogen are formed in the upper ring plate and the lower ring plate, so that the hydrogen inlet of the cylinder body is connected with the hydrogen passage in the plate-fin heat exchanger core body through the first hole, and the hydrogen passage is connected with the discharge port of the cylinder body through the second hole. The plate-fin heat exchange device provided by the application can overcome the problem that the aluminum sealing head cannot be directly welded under the condition that the design pressure of the hydrogen passage is relatively high and the opening is relatively large in the large-scale hydrogen liquefaction process, and can be applied to a large-scale hydrogen treatment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of energy equipment, and particularly relates to a plate-fin heat exchange device and method for large-scale hydrogen liquefaction. BACKGROUND

[0002] In the hydrogen liquefaction process, the hydrogen gas needs to be pre-cooled by using external refrigerant, including liquid nitrogen, liquefied natural gas, etc. The pre-cooled hydrogen gas is then subjected to catalytic device to complete the conversion of normal hydrogen and para hydrogen, and then subjected to condenser liquefaction by using ultra-low temperature refrigerant.

[0003] The plate-fin heat exchanger is widely used in low-temperature heat exchange fields such as air separation, petrochemical industry and hydrogen liquefaction due to its good heat exchange effect, compact structure and strong adaptability. In the current hydrogen liquefaction process, the conversion of normal hydrogen and para hydrogen is completed in the plate-fin heat exchanger, and the cold agent is introduced into another channel for cooling, that is, the catalytic reaction of hydrogen gas is completed in the plate-fin heat exchanger, and heat exchange and cooling are simultaneously performed.

[0004] The catalytic device and the plate-fin heat exchanger need to be connected by a pipeline. However, the hydrogen gas channel pressure is usually high, and the catalytic agent needs to be filled in the full open channel. When the hydrogen gas treatment capacity is large, the opening size of the heat exchanger can reach 1500mm. If the catalytic agent is filled in the full open channel, the diameter of the head required will be very large. The head material of the plate-fin heat exchanger is usually 5083 material, which belongs to Al-Mg alloy and has weak strength, less than half of the strength of stainless steel. In addition, the head and the core body of the plate-fin heat exchanger need to be welded in a special way, and the welding coefficient can only be 0.6, resulting in an excessively thick aluminum head and manufacturing difficulty.

[0005] Therefore, there is an urgent need for a plate-fin heat exchange device that can be applied to large-scale hydrogen gas treatment capacity and ensure effective heat exchange. SUMMARY

[0006] The present application aims at the deficiencies in the prior art and provides a plate-fin heat exchange device and method for large-scale hydrogen liquefaction.

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

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

[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 body, and the diameter of the lower ring plate is smaller than the inner diameter of the cylinder body 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 normal hydrogen and parahydrogen. A receiving groove for receiving the catalyst is arranged below the lower ring plate.

[0010] The upper ring plate and the lower ring plate are both provided with first holes and second holes for the inlet and outlet of hydrogen. The hydrogen inlet of the cylinder body is connected to the hydrogen passage inside the plate-fin heat exchanger core through the first holes. The hydrogen passage inside the plate-fin heat exchanger core is connected to the discharge port of the cylinder body through the second holes. The first holes and the second holes are both provided with filter screens.

[0011] The lower surface of the upper ring plate is connected to a sealing ring plate with a hole of the same cross-sectional size as the upper surface of the plate-fin heat exchanger core through detachable connectors. 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 of the same cross-sectional size as the lower surface of the plate-fin heat exchanger core through detachable connectors.

[0012] A hot stream inlet and a coolant inlet are arranged on one side wall of the cylinder body, and a hot stream outlet and a coolant outlet are arranged on the other side wall. Connection pipes are arranged on the hot stream inlet, the coolant inlet, the hot stream outlet and the coolant outlet to allow the inside and outside of the cylinder body to communicate. The connection pipe on the hot stream inlet is connected to the connection pipe on the inlet of the hot stream passage inside the plate-fin heat exchanger core through a joint pipe. The joint pipe on the outlet of the hot stream passage is connected to the connection pipe on the hot stream outlet through a joint pipe. The joint pipe on the coolant inlet is connected to the joint pipe on the inlet of the coolant passage inside the plate-fin heat exchanger core through a joint pipe. The joint pipe on the outlet of the coolant passage is connected to the connection pipe on the coolant outlet through a joint pipe.

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

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

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

[0016] Preferably, the mesh size of the filter screen is 40-100 mesh.

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

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

[0019] As preferred, the outer diameter of the sealing ring plate is 0.6-1 times of the inner diameter of the cylinder.

[0020] As preferred, the material of the connecting pipe is stainless steel. The material of the joint pipe is aluminum.

[0021] As preferred, the connecting pipe and the joint pipe are connected by a steel-aluminum joint pipe fitting.

[0022] As preferred, a sealing ring capable of bearing a low temperature of -200 DEG C is arranged between the sealing ring plate and the upper ring plate and between the fixed ring plate and the lower ring plate.

[0023] Further, the material of the sealing ring is polytetrafluoroethylene.

[0024] As preferred, 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 a construction space is left between the bottom of the plate-fin heat exchanger core and the cylinder.

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

[0026] Before the heat exchange device works, the detachable connecting piece between the upper ring plate and the sealing ring plate is removed, and the catalyst is filled into the plate-fin heat exchanger core. After the filling is completed, the upper ring plate and the sealing ring plate are tightly connected through the detachable connecting piece.

[0027] When the heat exchange device works, the coolant enters the coolant channel in the plate-fin heat exchanger core through the coolant inlet on the cylinder, and provides cold energy for hydrogen and the remaining hot stream. The remaining hot stream enters the hot stream channel in the plate-fin heat exchanger core through the hot stream inlet on the cylinder. After the heat exchange is completed, the remaining hot stream is discharged to the hot stream outlet through the pipe.

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

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

[0030] (1) The plate-fin heat exchanger is arranged in the stainless steel cylinder, which overcomes the problem that the aluminum end cover cannot be directly welded under the condition that the hydrogen channel is designed with a relatively high pressure and a large opening in the large-scale hydrogen liquefaction process.

[0031] (2) The hydrogen channel in the present application does not set an aluminum head, and the operator can enter the inside through the manhole on the stainless steel cylinder to fill the catalyst; and since the hydrogen channel is a fully open channel, the operator can directly observe the filling condition of the catalyst;

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

[0033] Figure 1 A large plate-fin heat exchanger device for hydrogen liquefaction provided in the present embodiment is shown in the figure;

[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 support ear 7, and fixed ring plate 8. DETAILED DESCRIPTION

[0035] The present application will be further described and explained in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment in the present application can be combined accordingly without conflict.

[0036] In order to solve the problem of manufacturing difficulty of the welding material between the heat exchanger core and the head in the process of liquefying a large amount of hydrogen, one of the best embodiments of the present application provides a large plate-fin heat exchanger device for hydrogen liquefaction as shown in the figure. Figure 1 The device includes a cylinder 1 and a plate-fin heat exchanger core 3 arranged in the cylinder 1. The plate-fin heat exchanger core 3 is fixed inside the cylinder 1 through a plate-fin heat exchanger support ear 7. A hydrogen inlet is formed on the cylinder 1. It should be noted that in an actual large hydrogen liquefaction device, a stainless steel cylinder is often used as the cylinder 1, and of course other materials can also be used.

[0037] The hydrogen inlet is not provided with a head between the plate-fin heat exchanger core 3, but adopts a full open type opening. The plate-fin heat exchanger core 3 is provided with a stainless steel upper ring plate 2 at the top. The upper ring plate 2 is provided with a first hole 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 passage in the plate-fin heat exchanger core 3 through the first hole, forming a full open type opening. The plate-fin heat exchanger core 3 is provided with a stainless steel lower ring plate 4 at the bottom. The lower ring plate 4 is provided with a second hole for the hydrogen to be discharged from the plate-fin heat exchanger core 3, so that the hydrogen passage in 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 full open type opening.

[0038] 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 ortho-para hydrogen. The lower ring plate 4 is provided with a receiving groove 5 below for receiving the catalyst, which is used to collect the fine catalyst particles carried out of the plate-fin heat exchanger core 3 by hydrogen or the catalyst particles falling during the process of workers replacing the catalyst filler.

[0039] In order to filter a small amount of impurities in the hydrogen, protect the plate-fin heat exchanger equipment to work normally and prolong its service life, a stainless steel filter screen needs to be arranged on the first hole on the upper ring plate 2 and the second hole on the lower ring plate 4. In actual engineering application, a stainless steel filter screen with a filtering precision of 40-100 meshes can be selected.

[0040] The lower surface of the upper ring plate 2 is connected with an aluminum sealing ring plate 6 through a detachable connecting piece. The sealing ring plate 6 is provided with a square hole in the middle with the same cross-sectional size as the plate-fin heat exchanger core 3, and is fixed on the side wall of 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, and generally an aluminum sealing ring plate 6 with a size of 0.6-1 times the inner diameter of the stainless steel cylinder can be selected.

[0041] In order to further strengthen the sealing between the upper ring plate 2 and the sealing ring plate 6, a sealing ring capable of resisting-200℃ low temperature is arranged between the upper ring plate 2 and the sealing ring plate 6. In this embodiment, a polytetrafluoroethylene (PTFE) sealing ring is selected, but other materials can also be used in actual application.

[0042] The upper surface of the lower ring plate 4 is connected to the aluminum fixed ring plate 8 via a removable connector. The fixed ring plate 8 has a square hole in the center that matches the cross-sectional dimensions of the plate-fin heat exchanger core 3 and is welded to the sidewall at the bottom of the plate-fin heat exchanger core 3. The outer diameters of both the lower ring plate 4 and the fixed ring plate 8 are smaller than the inner diameter of the stainless steel cylinder. In practice, the difference between the diameters 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, leaving a reasonable construction space between the bottom of the plate-fin heat exchanger core 3 and the stainless steel cylinder.

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

[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 loading or emptying the catalyst inside the plate-fin heat exchanger core 3, workers only need 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 load or empty the catalyst.

[0046] like Figure 1 As shown, one side of the stainless steel cylinder has a heat inlet at the top and a refrigerant inlet at the bottom. The other side has a refrigerant outlet at the top and a heat outlet at the bottom. Stainless steel pipes are installed at the heat inlet, refrigerant inlet, heat outlet, and refrigerant outlet, ensuring internal and external communication between the stainless steel cylinder.

[0047] Aluminum piping connections are required on the plate-fin heat exchanger core 3, and steel-aluminum joints are required between the aluminum piping and the stainless steel piping. The stainless steel piping at the heat inlet connects to the aluminum piping at the heat channel inlet within the plate-fin heat exchanger core 3 via a steel-aluminum joint. The aluminum piping at the heat channel outlet connects to the stainless steel piping at the heat channel outlet via a steel-aluminum joint. The stainless steel piping at the refrigerant inlet connects to the aluminum piping at the refrigerant channel inlet within the plate-fin heat exchanger core 3 via a steel-aluminum joint. The aluminum piping at the refrigerant channel outlet connects to the stainless steel piping at the refrigerant outlet via a steel-aluminum joint.

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

[0049] (1) Before the heat exchange device works, the detachable connecting piece between the upper ring plate (2) and the sealing ring plate (6) is disassembled, and the catalyst is filled into the plate-fin heat exchanger core (3); after the filling 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 works, the coolant enters the coolant channel in the plate-fin heat exchanger core 3 through the coolant inlet on the stainless steel cylinder, providing cold energy for hydrogen and the remaining hot flow; the remaining hot flow enters the hot flow channel in the plate-fin heat exchanger core 3 through the hot flow inlet on the stainless steel cylinder; after the heat exchange is completed, the remaining hot flow is discharged to the hot flow outlet through the pipeline;

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

[0052] The above-described embodiment is only a preferred scheme of the present application, and is not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, any technical scheme obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

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 lug (7); An upper ring plate (2) and a lower ring plate (4) are respectively provided 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 tank (5) for receiving the catalyst is provided 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 a filter screen; The lower surface of the upper ring plate (2) is connected to a sealing ring plate (6) with a hole having the same cross-sectional dimensions 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 having the same cross-sectional dimensions 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 communicated with each other; 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; the connecting pipe on the heat flow channel outlet is connected to the connecting pipe on the heat flow outlet through a connecting pipe; 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; the connecting pipe on the refrigerant channel outlet is connected to the connecting pipe on the refrigerant outlet through a connecting pipe.

2. The large-scale plate-fin heat exchanger 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 exchanger 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 exchanger 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 exchanger 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 exchanger 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 exchanger 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 exchanger 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 exchanger 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 a 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 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; 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 conversion of normal and para hydrogen 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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