Multi-stage double-nozzle ejector, preparation method and anode gas circulation system

Abstract

The invention discloses a multi-stage double-nozzle ejector, a preparation method and an anode gas circulation system, the multi-stage double-nozzle ejector comprises a shell, a first injection assembly and a second injection assembly, the shell is provided with a plurality of mixing chambers and diffusion chambers, an inlet and an outlet are formed in the two ends of the shell respectively, and the mixing chambers and the diffusion chambers are connected in a staggered mode; the first mixing chamber is connected with the inlet, and the last diffusion chamber is connected with the outlet; the first spraying assembly comprises a first nozzle and a second nozzle, the first nozzle and the second nozzle are coaxially arranged in the first mixing chamber, a first flow channel is formed in the first nozzle, a gap between the first nozzle and the second nozzle forms a second flow channel, and the width of the second flow channel is smaller than that of the first flow channel so that turbulent flow can be formed at an outlet of the second flow channel; and the second spraying assembly is arranged in the remaining mixing chamber.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ejector, in particular to a multi-stage double-nozzle ejector, a preparation method and an anode gas circulation system. BACKGROUND

[0002] An ejector is a device that uses a high-speed high-energy flow to induce another low-speed low-energy flow. The role of the ejector in the anode gas circulation system of the solid oxide fuel cell mainly reflects in the circulation and recovery of the gas and the pressure regulation. The circulation and recovery of the gas is achieved by driving the high-pressure hydrogen to reabsorb the unreacted anode tail gas of the fuel cell into the circulation system, thereby improving the fuel utilization rate and preventing carbon deposition. The pressure regulation is achieved by using the Venturi effect to mix the working fluid (high-pressure fuel) and the induced fluid (low-pressure tail gas) to output the mixed gas with intermediate pressure, thereby maintaining the stable pressure on the anode side.

[0003] However, the existing ejector for the anode gas circulation system of the solid oxide fuel cell is mostly of a single-stage single-nozzle structure, which has the disadvantage of low fuel utilization rate. Moreover, the ejector of such structure often has the problem of excessively low pressure of the mixed gas, which needs to be connected with an external mechanical pump for pressure boosting to maintain the pressure on the anode side, thereby resulting in the redundancy of the anode gas circulation system and high cost. Therefore, it is urgent to improve the structure of the existing ejector to solve the above problems. SUMMARY

[0004] The present application aims to provide a multi-stage double-nozzle ejector, a preparation method and an anode gas circulation system to solve the technical problems of low fuel utilization rate and excessively low pressure of the mixed gas, which needs to be connected with an external mechanical pump to maintain the pressure on the anode side, thereby resulting in the redundancy of the system and high cost.

[0005] To achieve the above technical purposes, the present application adopts the following technical solutions: In a first aspect, the present application provides a multi-stage double-nozzle ejector, comprising: a housing having a plurality of mixing chambers and diffuser chambers, the housing being formed with an inlet and an outlet at two ends, respectively, the plurality of mixing chambers and diffuser chambers being connected alternately, and the first mixing chamber being connected with the inlet, and the last diffuser chamber being connected with the outlet; a first jet assembly comprising a first nozzle and a second nozzle, the first nozzle and the second nozzle being coaxially arranged in the first mixing chamber, the first nozzle being formed with a first flow channel inside, and the gap between the first nozzle and the second nozzle being formed with a second flow channel, the width of the second flow channel being smaller than that of the first flow channel to form a turbulent flow at the outlet of the second flow channel; a second jet assembly, the second jet assembly being arranged in the remaining mixing chambers.

[0006] In some embodiments, the housing has two mixing chambers and two diffusion chambers, the two mixing chambers being a first mixing chamber and a second mixing chamber, the two diffusion chambers being a first diffusion chamber and a second diffusion chamber, and the inlet being sequentially connected to the first mixing chamber, the first diffusion chamber, the second mixing chamber, the second diffusion chamber, and the outlet.

[0007] In some embodiments, the first injection assembly is disposed in the first mixing chamber, and the second injection assembly is disposed in the second mixing chamber; The first nozzle and the second nozzle are coaxially disposed in the first mixing chamber, and the first nozzle and the second nozzle are respectively connected to the inlet.

[0008] In some embodiments, the second injection assembly includes a third nozzle disposed on the central axis of the second mixing chamber and connected to the first diffuser chamber.

[0009] In some embodiments, the volume of the first mixing chamber is greater than the volume of the second mixing chamber.

[0010] In some embodiments, the length of the first diffuser chamber is equal to the length of the second diffuser chamber, and the height of the first diffuser chamber is greater than the height of the second diffuser chamber.

[0011] In some embodiments, the height of the first mixing chamber near the inlet is greater than its height away from the inlet, and a first jet inlet is also formed on one side of the first mixing chamber.

[0012] In some embodiments, the height of the second mixing chamber near the first diffuser chamber is greater than the height of the side away from the first diffuser chamber, and a second jet inlet is also formed on one side of the second mixing chamber.

[0013] Secondly, the present invention provides a method for preparing a multi-stage dual-nozzle ejector, wherein the method is to manufacture the multi-stage dual-nozzle ejector described in the first aspect of the present invention using 3D printing technology.

[0014] Thirdly, the present invention also provides an anode gas circulation system for a solid oxide fuel cell, the gas circulation system comprising at least one multi-stage dual-nozzle ejector as described in the first aspect of the present invention.

[0015] Compared with the prior art, the beneficial effects of the present invention mainly include: The multi-stage dual-nozzle ejector provided by this invention comprises a first nozzle assembly consisting of a first nozzle and a second nozzle arranged coaxially. The width of the first flow channel formed inside the first nozzle is greater than the width of the second flow channel formed by the gap between the first and second nozzles. Thus, when the same main fluid enters the first and second flow channels respectively, turbulent gas is formed at the outlet of the second flow channel due to its smaller width. This turbulent gas promotes mixing with the ejector flow, improves mixing efficiency, and thus enhances fuel utilization. Simultaneously, this invention includes multiple mixing chambers and diffuser chambers, which can pressurize the thoroughly mixed gas through the second injection assembly to reach the required pressure before ejecting it from the outlet. This ensures the pressure at the ejector outlet without the need for an additional mechanical pump for pressurization, thereby simplifying the system and control program and reducing the cost of the ejector. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the multi-stage dual-nozzle ejector described in this invention.

[0017] Figure 2 This is a process flow diagram of the preparation method of the multi-stage dual-nozzle ejector described in this invention.

[0018] Explanation of reference numerals in the attached figures: 100. Outer shell; 101. Mixing chamber; 101a. First mixing chamber; 101b. Second mixing chamber; 102. Diffuser chamber; 102a. First diffuser chamber; 102b. Second diffuser chamber; 103. Inlet; 104. Outlet; 105. First jet inlet; 106. Second jet inlet. 200, First injection assembly; 201, First flow channel; 202, Second flow channel; 210, First nozzle; 220, Second nozzle; 300. Second injection assembly; 310. Third nozzle. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] To address the shortcomings of existing single-stage single-nozzle reflectors, such as low fuel utilization and low pressure of the mixed gas, requiring an external mechanical pump, this invention designs a multi-stage dual-nozzle ejector, a method for preparing the multi-stage dual-nozzle ejector, and a solid oxide fuel cell anode gas circulation system with the multi-stage dual-nozzle ejector, which can improve fuel utilization and simplify the structure.

[0021] like Figure 1As shown, in a first aspect, the present invention relates to a multi-stage dual-nozzle ejector, comprising a housing 100, a first injection assembly 200, and a second injection assembly 300. The housing 100 has a plurality of mixing chambers 101 and a plurality of diffuser chambers 102 inside. An inlet 103 and an outlet 104 are respectively formed at both ends of the housing 100. The plurality of mixing chambers 101 and diffuser chambers 102 are staggered and connected. The first mixing chamber 101 is connected to the inlet 103, and the last diffuser chamber 102 is connected to the outlet 104. The first injection assembly 200 includes a first nozzle 210 and a second nozzle 220. The first nozzle 210 and the second nozzle 220 are coaxially disposed in the first mixing chamber 101. A first flow channel 201 is formed inside the first nozzle 210. The gap between the first nozzle 210 and the second nozzle 220 forms a second flow channel 202. The width of the second flow channel 202 is smaller than the width of the first flow channel 201. The second injection assembly 300 is disposed in the remaining mixing chambers 101.

[0022] In the above technical solution of the present invention, the first injection assembly 200 is composed of a first nozzle 210 and a second nozzle 220 arranged coaxially inside and outside, and coaxial with the axis of the mixing chamber 101. The internal space of the first nozzle 210 forms the first flow channel 201 of the mainstream fluid (fresh fuel), and the gap between the first nozzle 210 and the second nozzle 220 forms the second flow channel 202 of the mainstream fluid (fresh fuel). The width of the second flow channel 202 is designed to be smaller than the width of the first flow channel 201. Under the condition that the mainstream fluid medium is the same, turbulence will be formed at the outlet of the second flow channel 202 relative to the first flow channel. The turbulent fluid can promote the full mixing with the ejector fluid. Therefore, the coaxial dual-nozzle structure designed in the present invention can improve the fuel utilization rate compared with the existing single-nozzle structure.

[0023] Meanwhile, the present invention provides multiple mixing chambers 101 and diffuser chambers 102, which can pressurize the fully mixed gas through the second injection component 300 to reach the required pressure before being ejected through the outlet. In this way, the pressure at the ejector outlet can be guaranteed without the need for an additional mechanical pump to increase the pressure. Therefore, the system and control program are simplified, and the cost of the ejector is reduced.

[0024] In fluid mechanics, the Reynolds number Re is a dimensionless quantity that describes the properties of fluid flow (laminar or turbulent) under different conditions by measuring the ratio of fluid inertia to viscous force. In this embodiment, since the width of the second channel 202 is smaller than the width of the first channel 201, the flow velocity of the same mainstream flow pattern in the second channel 202 is greater than that in the first channel 201. Therefore, the Reynolds number of the second channel 202 is greater than that of the first channel 201. That is, turbulence, also known as disturbance, is formed in the second channel 202. The main function of turbulence is to promote the mixing of fluids. By enhancing the random motion of fluid particles, it significantly improves the exchange efficiency of momentum, heat, and mass. For example, in a combustion system, turbulence can accelerate fuel evaporation, diffusion, and air mixing, shorten the combustion delay period, improve combustion efficiency, and reduce pollutant emissions. Therefore, based on this principle, this invention can form turbulence at the outlet of the second channel 202 to fully mix with the ejector fluid, thereby achieving the purpose of complete fuel combustion and improving fuel utilization.

[0025] It should be noted that the present invention provides multiple mixing chambers 101 and multiple diffuser chambers 102. The first injection assembly 200 has a dual-nozzle structure and is disposed in the first mixing chamber 101 connected to the inlet 103. The second injection assembly 300 can be disposed in other mixing chambers 101 to increase the pressure of the mixed gas. However, in practical applications, it is not necessarily better to have more mixing chambers 101 and diffuser chambers 102. Too many mixing chambers 101 and diffuser chambers 102 will lead to a redundant system. Therefore, the present invention preferably provides two mixing chambers 101 and two diffuser chambers 102. In other embodiments, three, four, five or more mixing chambers 101 and diffuser chambers 102 may be provided as needed.

[0026] In one embodiment, combined Figure 1 As shown, the outer casing 100 has two mixing chambers 101 and two diffuser chambers 102. The two mixing chambers are a first mixing chamber 101a and a second mixing chamber 101b, and the two diffuser chambers 102 are a first diffuser chamber 102a and a second diffuser chamber 102b, respectively. The inlet 103 is sequentially connected to the first mixing chamber 101a, the first diffuser chamber 102a, the second mixing chamber 101b, the second diffuser chamber 102b, and the outlet 104.

[0027] In one embodiment, the first injection assembly 200 is disposed in the first mixing chamber 101a, and the second injection assembly 300 is disposed in the second mixing chamber 101b.

[0028] The first nozzle 210 and the second nozzle 220 are coaxially disposed in the first mixing chamber 101a, and the first nozzle 210 and the second nozzle 220 are respectively connected to the inlet 103.

[0029] In one embodiment, the second injection assembly 300 includes a third nozzle 310 disposed on the central axis of the second mixing chamber 101b and connected to the first diffuser chamber 102a.

[0030] In one embodiment, since the first mixing chamber 101a needs to install both the first nozzle 210 and the second nozzle 220, while the second mixing chamber 101b only needs to install the third nozzle 310, the volume of the first mixing chamber 101a is larger than the volume of the second mixing chamber 101b.

[0031] In one embodiment, the length of the first diffuser 102a is equal to the length of the second diffuser 102b, while the height of the first diffuser 102a is greater than the height of the second diffuser 102b, so as to form a high-pressure airflow in the second diffuser 102b to meet the pressure requirements.

[0032] In one embodiment, the height of the first mixing chamber 101a on the side closer to the inlet 103 is greater than the height on the side farther from the inlet 103, and a first jet inlet 105 is also formed on one side of the first mixing chamber 101a.

[0033] In one embodiment, the height of the second mixing chamber 101b on the side closer to the first diffuser chamber 102a is greater than the height on the side farther from the first diffuser chamber 102a, and a second jet inlet 106 is also formed on one side of the second mixing chamber 101b.

[0034] That is, the first mixing chamber 101a and the second mixing chamber 101b also have a reduced structure to facilitate increasing the pressure of the mixed gas.

[0035] The working principle of the multi-stage dual-nozzle ejector provided by this invention is as follows: The mainstream fluid (fresh fuel) enters the first flow channel 201 and the second flow channel 202 simultaneously from the inlet 103. Since the width of the second flow channel 202 is smaller than the width of the first flow channel 201, turbulence is formed at the outlet of the second flow channel 202, which mixes thoroughly with the ejector fluid entering from the first ejector inlet 105. The mixed airflow enters the first diffuser chamber 102a, and as the mainstream fluid of the second mixing chamber 101b, it enters the third nozzle 310. After being pressurized and ejected by the third nozzle 310, it mixes and pressurizes with the ejector fluid flowing in from the second ejector inlet 106, and finally ejects from the outlet 104.

[0036] Secondly, such as Figure 2As shown, the present invention also provides a method for manufacturing a multi-stage dual-nozzle ejector, wherein the manufacturing method is carried out by 3D printing technology, specifically including: Step 1: Select high-temperature resistant and corrosion-resistant materials as printing raw materials, such as Inconel 718 or 625 materials; Step 2: Set 3D printing parameters; specifically, this includes optimizing powder particle size (optimized to 15-45μm), selecting sintering parameters (e.g., vacuum sintering temperature of 1200-1300℃) to control grain growth and residual stress, using low energy density laser power (e.g., 200-300w) to reduce the risk of hot cracking, and milling the surface roughness of the first flow channel 201 and the second flow channel 202 (requiring Ra < 10μm). The binder spray layer thickness can be controlled between 20-50μm. Step 3: Print according to the set 3D printing parameters, including laser power of 180-220w and layer thickness of 25-35μm; deposit the conductive layer and ion-conducting layer sequentially by plasma spraying at a powder feeding rate of 20-30g / min; load the catalyst layer using the impregnation-calcination method with an impregnation solution concentration of 0.25-0.35mol / L, and perform hot isostatic pressing treatment at a pressure of 100-150MPa and a temperature of 950-1050℃ for 2-4 hours. Step 4: Post-process the printed product; specifically, this includes using a two-step degreasing process (solvent + thermal degreasing) to remove the previously added binder, combined with a continuous sintering furnace (such as the GKN solution) to achieve a density of over 98% to reduce deformation; using HIP treatment (1000℃ / 100MPa) to eliminate internal pores in the printed object; for the first flow channel 201 and the second flow channel 202, micro-drilling or electrochemical machining (ECM) can be used to refine the dimensional tolerances to ±0.05mm.

[0037] Thirdly, the present invention also provides a solid oxide fuel cell anode gas circulation system, the gas circulation system comprising at least one multi-stage dual-nozzle ejector as described in the first aspect of the present invention.

[0038] In summary, the present invention has the following beneficial effects: 1. Increased ejection ratio improves fuel utilization: Under the same mainstream fluid pressure (3 atm) and ejector fluid pressure (1 atm), the ejection ratio of a conventional ejector is 0.807, while the ejection ratio of the multi-stage dual-nozzle ejector provided by this invention can reach 2.489, thus improving the ejection ratio and thereby increasing fuel utilization.

[0039] 2. Increased total traffic: Under the same mainstream fluid conditions, the flow rate of a conventional ejector is approximately 0.1 kg / s, while the flow rate of the multi-stage dual-nozzle ejector provided by this invention is approximately 0.244 kg / s.

[0040] 3. The pressure of the mainstream fluid can be appropriately reduced: With the same mainstream fluid ejection ratio, the dual-nozzle structure (first nozzle assembly 200) has a lower pressure requirement for the mainstream fluid.

[0041] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A multi-stage dual-nozzle ejector, characterized in that, include: The housing has multiple mixing chambers and a diffuser chamber. An inlet and an outlet are formed at both ends of the housing. The multiple mixing chambers and diffuser chambers are connected in an alternating manner, with the first mixing chamber connected to the inlet and the last diffuser chamber connected to the outlet. The first injection assembly includes a first nozzle and a second nozzle, which are coaxially disposed in the first mixing chamber. A first flow channel is formed inside the first nozzle, and a second flow channel is formed by the gap between the first nozzle and the second nozzle. The width of the second flow channel is smaller than the width of the first flow channel to form turbulence at the outlet of the second flow channel. The second injection assembly is disposed in the remaining mixing chamber.

2. The multi-stage dual-nozzle ejector according to claim 1, characterized in that, The outer casing has two mixing chambers and two diffusion chambers, the two mixing chambers being a first mixing chamber and a second mixing chamber, and the two diffusion chambers being a first diffusion chamber and a second diffusion chamber, respectively. The inlet is sequentially connected to the first mixing chamber, the first diffusion chamber, the second mixing chamber, the second diffusion chamber, and the outlet.

3. The multi-stage dual-nozzle ejector according to claim 2, characterized in that, The first injection assembly is disposed in the first mixing chamber, and the second injection assembly is disposed in the second mixing chamber; The first nozzle and the second nozzle are coaxially disposed in the first mixing chamber, and the first nozzle and the second nozzle are respectively connected to the inlet.

4. The multi-stage dual-nozzle ejector according to claim 2, characterized in that, The second injection assembly includes a third nozzle, which is disposed on the central axis of the second mixing chamber and connected to the first diffuser chamber.

5. The multi-stage dual-nozzle ejector according to claim 2, characterized in that, The volume of the first mixing chamber is greater than the volume of the second mixing chamber.

6. The multi-stage dual-nozzle ejector according to claim 2, characterized in that, The length of the first diffuser chamber is equal to the length of the second diffuser chamber, and the height of the first diffuser chamber is greater than the height of the second diffuser chamber.

7. The multi-stage dual-nozzle ejector according to claim 2, characterized in that, The height of the first mixing chamber near the inlet is greater than the height of the side away from the inlet, and a first jet inlet is also formed on one side of the first mixing chamber.

8. The multi-stage dual-nozzle ejector according to claim 2, characterized in that, The height of the second mixing chamber near the first diffuser chamber is greater than the height of the side away from the first diffuser chamber, and a second jet inlet is also formed on one side of the second mixing chamber.

9. A method for preparing a multi-stage dual-nozzle ejector, characterized in that, The preparation method is to manufacture the multi-stage dual-nozzle ejector as described in any one of claims 1-8 using 3D printing technology.

10. An anode gas circulation system for a solid oxide fuel cell, characterized in that, The gas circulation system includes at least one multi-stage dual-nozzle ejector as described in any one of claims 1-8.

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