CN105709570B - A hydrogen separator with an expansion joint - Google Patents

Abstract

A hydrogen separator with an expansion joint comprises a cavity, a conical sealing element, a compression ring, a sealing material and a metal elastic sheet; an expansion joint is arranged in the middle of the cavity, and locking nuts matched with the conical sealing elements are arranged at two ends of the cavity; a sealing cavity and a divergent tube type gas buffer cavity are arranged in the conical sealing element, and an inclined plane is arranged at the bottom of the sealing cavity; inserting one end of the tubular hydrogen separation material into a sealing cavity of the conical sealing element, so as to define an annular gap between the sealing cavity and the hydrogen separation material, and filling a sealing material in the annular gap; the tubular hydrogen separation material is positioned on the axis of the conical sealing element, the conical sealing element is connected with the tubular hydrogen separation material through a sealing material, a compression ring and a metal elastic sheet, and the tubular hydrogen separation material is encapsulated in the cavity through threaded connection with locking nuts at two ends of the cavity. The invention solves the problem of tension force between the tubular hydrogen separation material and the stainless steel separator cavity caused by different thermal expansion coefficients in the high-temperature or temperature rise and fall process, eliminates the damage of thermal expansion to the sealing performance in the high-temperature use process, and keeps the stability of the sealing performance.

Description

A hydrogen separator with an expansion joint

technical field

The invention relates to a hydrogen separator with an expansion joint. Specifically, a tubular ceramic-based hydrogen separation material is sheathed in a cavity with an expansion joint, and the two ends of the tubular ceramic-based hydrogen separation material are respectively sheathed with metal shrapnel, pressed Tight ring, graphite gasket; two conical seals are screwed together to encapsulate the tubular ceramic-based hydrogen separation material in the chamber to form a hydrogen separator. The separator has tubular hydrogen separation materials that are easy to replace, simple in structure, and easy to operate. , cost saving and other advantages, especially suitable for small and medium scale hydrogen separation and purification.

Background technique

With the rapid development of industries such as electronic information, semiconductor and LED manufacturing, the demand for ultra-pure hydrogen (purity>99.9999%) is increasing (Chen Zili et al., Source and purification of hydrogen in polysilicon production, low temperature and special gas ,30(2012)21-23), and put forward higher requirements for hydrogen separation and purification technology. Hydrogen separation and purification technologies mainly include pressure swing adsorption (PSA), temperature swing adsorption (TSA), cryogenic separation and membrane separation. Compared with pressure swing adsorption, temperature swing adsorption and cryogenic separation, membrane separation is widely used because of its advantages of less investment, simple equipment, low energy consumption, easy operation, and no environmental pollution. This technology is especially suitable for small and medium-scale hydrogen separation with purification. Membrane materials that can be used for hydrogen separation and purification include polymer membranes, molecular sieve membranes, carbon membranes, zirconium dioxide membranes, titanium dioxide membranes, metal palladium and its alloy membranes, etc. Among them, metal palladium and its alloy membranes have good hydrogen permeability, The characteristics of high selectivity and high temperature resistance have attracted much attention in the application of hydrogen separation and purification.

At present, almost all of the commercialized ultra-pure hydrogen production technologies are metal palladium and its alloy membrane purification technology. Due to the limitation of mechanical strength, the palladium membrane thickness is generally about 100 μm, not only the hydrogen permeability is small, but also the manufacturing cost is high. In order to overcome this shortcoming, people propose the technical route (S.Uemiya, APalladium/Porous-Glass Composite Membrane for Hydrogen Separation. Chemistry Letters, 17 (1988) 1687-1690) that metallic palladium membrane is loaded on the porous support body surface, this The palladium composite membrane can maintain a high mechanical strength, and the thickness of the palladium membrane can be reduced to 5-10 μm, so the hydrogen permeability has been greatly improved, and the manufacturing cost of the palladium membrane has been significantly reduced. Materials used as supports include porous metals, porous ceramics and porous glass, and porous ceramics are the most widely used because of their excellent chemical stability, thermal stability and wide market sources.

For pure palladium/ceramic composite membranes, hydrogen embrittlement will occur in contact with H ₂ at temperatures lower than 300°C, which will damage the palladium membrane. It involves the high temperature sealing problem of palladium/ceramic composite membrane. Usually, the more commonly used connection method between ceramic pipe fittings and metal pipelines is mechanical connection (Gu Yuxi et al., The connection between ceramics and metals, Chemical Industry Press, 2010), that is, ceramic pipe fittings are realized through joints, threads, flanges, ferrules, etc. The sealing and connection with other parts have the advantages of simple operation, low cost and convenient disassembly. However, the coefficient of thermal expansion of ceramic materials is low, and the coefficient of thermal expansion at 25-700 ° C is about 7 to 8×10 ^-6 K ^-1 (Handbook of Electrical and Electronic Insulation Technology, Mechanical Industry Press, 2008, P482); stainless steel is at 25 The coefficient of thermal expansion at -700°C is 18.6×10 ^-6 K ^-1 (Handbook of Metallic Materials, Chemical Industry Press, 2009). The thermal expansion coefficients of the two are very different. When the ceramic material is directly sealed with stainless steel by mechanical connection, In the process of high temperature or temperature rise and fall, the problem of thermal expansion mismatch will inevitably occur.

In order to slow down the difference in thermal expansion caused by ceramic pipe fittings and metal seals when used at high temperatures, various methods have been proposed, such as: Huang et al. , 01, 2006) adopt ferrule sealing method to seal both ends of the ceramic material respectively, and then connect one end to the sealer, and the other end is free to expand and contract. This method can eliminate the difference in thermal expansion, but the structure is not compact enough and needs three times. Sealed connection increases the chance of gas leakage; Xu et al. (Xu Hengyong, Li Chunlin, Tang Chunhua, a multi-channel metal palladium or palladium alloy composite membrane hydrogen separator, Chinese patent CN101642684A, 02.2010; Xu Hengyong, Tang Chunhua, set preheating and heat exchange An integrated multi-channel metal-palladium composite membrane hydrogen separation device, Chinese utility model patent, CN203379783U, 01.2014) is connected to one end of the palladium membrane assembly by using a metal elbow, etc., and then the palladium membrane assembly is sealed in the separator cavity by welding , through the expansion and contraction of metal elbows, etc., the stress generated by the thermal expansion of the palladium/ceramic composite membrane tube and the metal seal is effectively buffered. The structure of the separator ensures the airtightness of the interface, but it also leads to the relatively / The ceramic composite membrane is not easy to replace, and the separator cavity cannot be used repeatedly. Huang et al. (Huang Yan, Zha Qinlai, Hu Xiaojuan. A high-temperature sealer for ceramic pipe fittings, Chinese invention patent, CN102979981A, 03.2013) used a constant expansion alloy material with a thermal expansion coefficient close to that of ceramic materials to manufacture the sealer cavity, combined with a clamp The sleeve method is used to seal the ceramic pipe fittings, which effectively solves the problem of thermal expansion stress generated between the ceramic seal cavities in high temperature or frequent temperature rise and fall environments, but because of the high cost of constant expansion alloy materials, this will inevitably lead to increase in manufacturing costs. Combining the metal expansion joint with the separator cavity will be a feasible method to solve the thermal expansion stress release.

Contents of the invention

The purpose of the present invention is to overcome the defects existing in the existing hydrogen separator when it is used at high temperature, and provide a hydrogen separator with expansion joint, which encapsulates the tubular hydrogen separation material in the separator cavity with expansion joint, and adopts The tubular hydrogen separation material is sealed and connected by the ferrule method. At high temperatures, the thermal expansion difference between the separator cavity and the tubular hydrogen separation material is eliminated through the expansion joint, thereby ensuring that the tubular hydrogen separation material maintains stable performance at high temperatures or during heating and cooling. .

The technical solution adopted in the present invention is: a hydrogen separator with an expansion joint, including a cavity, a conical seal, a compression ring, a sealing material and a metal shrapnel, the cavity is a cylindrical structure with two ends open, and The inner wall surface of the opening end expands radially outwards to form a ring-shaped interface with internal threads. The radial cross-sectional area of the ring-shaped interface is larger than the radial cross-sectional area of the middle of the cavity. The connection between the interface and the cavity forms an annular plane; one end of the conical seal is a hollow truncated conical expander with two ends open, and the other end of the conical seal is a cylindrical seal with two ends open and external thread cavity, the radial cross-sectional area of the sealing cavity is greater than the area of the lower bottom surface of the expanding tube, the lower bottom surface of the expanding tube is connected to an opening end of the sealing cavity through a truncated conical sealing cavity, and the upper bottom surface of the sealing cavity is fixed to the expanding tube The area of the lower bottom surface of the sealed cavity is equal, the lower bottom surface of the sealed cavity is equal to the radial cross-sectional area of the sealed cavity; the tubular hydrogen separation material is sleeved in the cavity, and the tubular hydrogen separation material is coaxial with the cavity; the two ends of the tubular hydrogen separation material The ring-shaped metal shrapnel, the compression ring, and the ring-shaped sealing material are respectively threaded in turn; the cylindrical sealing chambers of the two conical seals are connected to the two ring-shaped interfaces of the cavity by thread screwing; the metal shrapnel It is in contact with the annular plane, and the annular sealing material is in contact with the truncated conical sealing cavity; a bellows expansion joint is arranged in the middle of the cavity; the bellows expansion joint divides the cavity into left and right parts, and the bellows expansion joint and the cavity body coaxial.

The invention encapsulates the tubular hydrogen separation material in the separator cavity with expansion joints. At high temperature, the thermal expansion difference between the separator cavity and the tubular hydrogen separation material is eliminated through the expansion joint, so that the hydrogen separation material can be used at high temperature or Maintain stable performance during heating and cooling.

The expansion joint set in the middle of the separator cavity is a single axial expansion joint, the material is stainless steel, the number of bellows of the expansion joint is 2 to 40, preferably 2 to 10, and the interface size of the expansion joint depends on the size of the separator cavity Determined by the outer diameter, the expansion joint is connected to the separator cavity by welding.

The length and inner diameter of the separator cavity can be determined according to the length and outer diameter of the tubular hydrogen separation material. The proper length of the separator cavity is 100-2000 mm, preferably 100-1000 mm, and the outer diameter of the separator cavity is 10-2000 mm. 60mm, the wall thickness is 2-5mm, determined by the operating environment, the material of the separator cavity is ordinary stainless steel or special alloy material.

The operating temperature of the separator is 20-620°C, preferably 100-500°C.

The sealing material is a preformed annular flexible high-purity graphite gasket.

The ring-shaped metal shrapnel is a metal spring washer, which is a ring-shaped metal shrapnel with a notch, and the notch breaks a gap in the axial direction of the side wall of the ring-shaped metal shrapnel. The thickness of the metal spring washer is 2-8 mm, and the quantity can be 1 piece or more than 2 pieces.

The lower base angle of the trapezoidal axial section of the truncated conical sealing chamber provided in the conical seal is 10°-80°, that is, the inclination angle of the inclined plane is 10°-80°, preferably 25°-35°. When the conical seal and the lock nuts at both ends of the cavity are screwed together, the lock nuts at both ends of the cavity squeeze the metal shrapnel and the compression ring, and the compression ring pushes the sealing material radially along the forward direction The extruded sealing material converts the radial driving force into the pressure on the tubular hydrogen separation material in the vertical direction through the inclined surface of the sealing cavity, so as to realize the sealed connection between the conical seal and the tubular hydrogen separation material.

The tubular _hydrogen separation material includes palladium and palladium alloy membranes, dense molecular sieve membranes, dense _SiO2 membranes or dense ZrO2, etc. with porous ceramics as the substrate. Any position in the interval is provided with grooves or slopes. For details, see Chinese patent (Xu Hengyong, Li Chunlin, Tang Chunhua, a multi-channel metal palladium or palladium alloy composite membrane hydrogen separator, Chinese patent CN101642684A, 02.2010), the number of channels of the ceramic substrate and The shape is not limited.

The invention provides a hydrogen separator with an expansion joint, which solves the tension problem caused by the difference in thermal expansion coefficient between the porous ceramic-based tubular hydrogen separation material and the separator cavity during the process of high temperature or temperature rise and fall, and eliminates the problem of high temperature In the process of use, thermal expansion will damage the sealing performance, keep the sealing performance stable, simple in structure, convenient in operation and cost saving.

Description of drawings

Figure 1. Schematic diagram of the hydrogen separator with expansion joints.

Fig. 2. Cross-sectional view of multi-channel Al ₂ O ₃ ceramic-based palladium composite membrane.

Fig. 3. Schematic diagram of the structure of multi-channel Al ₂ O ₃ ceramic-based palladium composite membrane.

Figure 4. Schematic diagram of the multi-channel Al ₂ O ₃ ceramic-based palladium composite membrane (with grooves). For clarity, the depth of the grooves in the figure is enlarged.

Figure 5. Schematic diagram of the structure of the multi-channel Al ₂ O ₃ ceramic-based palladium composite membrane (with a slope). For the sake of clarity, the gradient of the slope in the figure is enlarged.

Detailed ways

The technical details of the present invention about the hydrogen separator with expansion joints are described in detail by the following examples. It should be noted that the examples cited are only used to further illustrate the technical features of the present invention, rather than to limit the present invention.

Example 1

The tubular hydrogen separation material is a multi-channel Al ₂ O ₃ ceramic-based palladium composite membrane 6 with a length of 330 mm and a diameter of 30 mm. The multi-channel Al ₂ O ₃ ceramic tube is composed of 19 channels with a diameter of 4 mm. Its cross-sectional schematic diagram See Figure 2. Adopt conventional electroless plating method, form continuous palladium film on the inner surface of multi-channel ceramic tube 6, the cross-section of two ends, and the outer surface of distance 30mm from the end, the thickness of palladium film is about 5 microns, and its section is as shown in Figure 3 . A hydrogen separator 9 with an expansion joint as shown in Fig. 1 is used to seal the multi-channel Al ₂ O ₃ ceramic-based palladium composite membrane 6, and the expansion joint includes two bellows. Put the multi-channel ceramic-based palladium composite membrane 6 into the hydrogen separator 9 with an expansion joint 8 in the middle, wrap the metal shrapnel 4, the compression ring 3 and the graphite gasket 2 around one end of the multi-channel ceramic-based palladium composite membrane 6 in sequence, and put The conical seal 1 is threaded into the lock nut 5 and tightened, first sealing this end, and simultaneously fixing the multi-channel ceramic-based palladium composite membrane 6 in the hydrogen separator 9 . Similarly, the other end of the multi-channel ceramic-based palladium composite membrane 6 is sequentially inserted into the metal shrapnel 4, the compression ring 3 and the graphite gasket 2, and the conical seal 1 is threaded into the lock nut 5 and tightened, then Complete the sealing connection between the multi-channel ceramic-based palladium composite membrane 6 and the hydrogen separator 9 with expansion joints.

After the sealing is completed, the gas outlet port (one of the chamber ports) of the hydrogen separator 8 is connected to the back pressure valve and the stop valve in sequence through the metal pipeline, and the gas inlet port (the other port of the cavity) is connected to the pressure valve in sequence through the metal pipeline. Meter, mass flow meter, one-way valve, stop valve, pipeline filter, pressure reducing valve and detection gas cylinder are connected, and the gas outlet on the side of cavity 7 of hydrogen separator 9 is connected with stop valve through metal pipeline, and sealed The outlet is blocked, and the gas outlet on the other side of the cavity 7 is connected with a soap film flowmeter through a metal pipeline for measuring the gas permeation. Feed nitrogen into the hydrogen separator 9, adjust the back pressure valve to increase the pressure in the tube of the multi-channel ceramic-based palladium composite membrane 6 in the hydrogen separator 9 to 3.0MPa, and keep the pressure outside the tube at normal pressure, measured by a soap film flowmeter The amount of nitrogen permeation under this condition is used as the basic nitrogen permeation performance, and then keep the gas flow rate and pressure constant, raise the temperature of the hydrogen separator to 500°C and keep it for 5 hours, and finally keep the gas flow rate and pressure constant , the hydrogen separator was naturally lowered to normal temperature, and after measuring the amount of nitrogen permeation, it was found that the amount of nitrogen permeation remained unchanged. Repeating the above operation 5 times, it was found that the amount of nitrogen permeation remained unchanged, indicating that the heating and cooling process has an effect on the hydrogen separator 9. Airtightness was not affected.

Example 2

Same as embodiment 1, but the multi _- channel _Al2O3 ceramic-based palladium composite membrane 5 of sealing, its length is 500mm, the number of channels is 7, the channel diameter is 6mm, and there are concave holes on the outer surface of 10mm from both ends to the ends. Groove, the width of the groove is 1.5mm, and the depth is 0.15mm. The expansion joint on the hydrogen separator 9 is composed of 3 bellows. When the conical seal is tightened, the lock nuts at both ends of the cavity squeeze the metal shrapnel and compress The compression ring produces a radial driving force along the advancing direction on the sealing material, and the extruded sealing material converts the radial driving force into vertical pressure on the tubular hydrogen separation material through the bottom surface of the sealing cavity, and a part of it is squeezed The compressively deformed sealing material fills the grooves outside the two ends of the tubular hydrogen separation material, thereby strengthening the sealing connection between the conical seal and the tubular hydrogen separation material.

As a result of the test, it was found that the airtightness of the hydrogen separator was good.

Example 3

With embodiment ₁ , but the multichannel _Al2O3 ceramic-based palladium composite membrane 5 of sealing, its length is 1000mm, and there is a slope at two ends to the outer surface of 20mm from the end, and the diameter at the end is 30.3mm, and the distance between The diameter at 20mm of the end is 30mm. The expansion joint on the hydrogen separator 9 is composed of 5 bellows. The tight ring generates a radial driving force along the advancing direction on the sealing material, and the extruded sealing material converts the radial driving force into a vertical pressure on the tubular hydrogen separation material through the bottom surface of the sealing cavity, and a part of it is squeezed and deformed The sealing material fills the slopes on the outer sides of the two ends of the tubular hydrogen separation material, thereby strengthening the sealing connection between the conical seal and the tubular hydrogen separation material.

As a result of the test, it was found that the airtightness of the hydrogen separator was good.

Example 4

Same as Example 1, but the tubular hydrogen separation material is a porous ceramic-based molecular sieve membrane with a length of 500 mm, an outer diameter of 13.2 mm, and an inner diameter of 7.5 mm. The expansion joint on the hydrogen separator 9 is composed of 5 bellows. The air outlets on both sides of the device cavity are connected to the stop valve through metal pipelines, and the outlets are blocked. Introduce nitrogen into the hydrogen separator, adjust the back pressure valve to increase the internal and external pressure of the porous ceramic-based molecular sieve membrane in the hydrogen separator to 2.0MPa, close the cylinder valve and the stop valve, and keep it for 2 hours. It is found that the value of the pressure gauge remains unchanged. Indicates that the seal is intact. Raise the temperature of the hydrogen separator to 500°C and keep it for 1 hour, then lower it to normal temperature naturally, and find that the value of the pressure gauge remains unchanged. The airtightness of device 9 has no influence.

The hydrogen separator with expansion joints of the present invention solves the tension problem caused by the difference in thermal expansion coefficient between the tubular hydrogen separation material and the stainless steel separator cavity during the process of high temperature or temperature rise and fall, and eliminates the problem of thermal expansion during high temperature use. Damage to the sealing performance, maintain the stability of the sealing performance, has the advantages of simple structure, convenient operation, cost saving, etc., and is especially suitable for small and medium-scale hydrogen separation and purification.

Claims (10)

1. a kind of hydrogen gas segregator with expansion joint, it is characterised in that：Including cavity, taper seal, compression ring, sealing material And metal clips, cavity are the cylinder-like structure of two end openings, the inner wall of open end is radially expanded, and forms one section Tapped circular ring shape interface, the radial cross-sectional area of circular ring shape interface is greater than the radial cross-sectional area in the middle part of cavity, along diameter A planar annular is formed in circular ring shape interface and cavity junction on direction；Taper seal one end be two end openings, in Empty truncated cone diffuser, the taper seal other end be two end openings, with externally threaded cylindric seal chamber, seal chamber Radial cross-sectional area be greater than the bottom surface area of diffuser, the bottom surface of diffuser and one open end of seal chamber pass through a circular cone Platform shape seal chamber is affixed, the bottom surface area equation of the affixed upper bottom surface of seal chamber and diffuser, the affixed bottom surface of seal chamber It is equal with the radial cross-sectional area of seal chamber；Tubulose hydrogen gas separation material is set in cavity, tubulose hydrogen gas separation material and chamber Body is coaxial；Circular ring metal elastic slice, compression ring, annular seal material are successively worn respectively in two end of tubulose hydrogen gas separation material Material；The cylindric seal chamber of two taper seals is connected to two circular ring shape interfaces of cavity by threads；Metal elastic Piece is contacted with planar annular, and annular seal material is contacted with truncated cone seal chamber；Wave is provided in the middle part of the cavity Line pipe expansion joint；Cavity is divided into two part of left and right by bellows expansion joint, and bellows expansion joint is coaxial with cavity.

2. separator according to claim 1, it is characterised in that：The expansion joint is single axial expansion joint.

3. separator according to claim 1 or 2, it is characterised in that：The bellows quantity of the expansion joint is 2-40.

4. separator according to claim 1, it is characterised in that：The trapezoidal axial cross section of the truncated cone seal chamber Lower base angle angle is 10 °~80 °, i.e., bevel inclination angle is 10 °~80 °.

5. separator according to claim 1, it is characterised in that：The circular ring metal elastic slice is metal spring pad Piece, for the circular ring metal elastic slice with a notch, the side wall of circular ring metal elastic slice is disconnected a seam along axial by notch Gap.

6. separator according to claim 5, it is characterised in that：The metallic spring washer with a thickness of 2-8 millimeters, Quantity is 1 or 2 or more.

7. separator according to claim 1, it is characterised in that：The separator work temperature is 20~620 DEG C.

8. separator according to claim 1, it is characterised in that：The length of the separator cavity is 100-2000mm.

9. separator according to claim 1, it is characterised in that：The cavity material is common stainless steel；Described is close Closure material is the circular ring shape flexibility high purity graphite washer of preforming.

10. separator according to claim 1, it is characterised in that：The tubulose hydrogen gas separation material is with porous pottery Porcelain is the palladium and palladium alloy membrane, dense molecular sieve membrane, densification SiO of matrix₂Film or densification ZrO₂Film, the number of active lanes of porous ceramics It is unlimited with shape.