Perforated tubular methanol solid oxide fuel cell with closed end

Abstract

The invention discloses a porous tubular methanol solid oxide fuel cell with a closed end, the fuel cell is a tubular solid oxide fuel cell (SOFC) stack, and the tubular SOFC stack comprises a plurality of tubular SOFC single cells; in the moving direction of fuel in the inner tube, the bottom end of the inner tube of the tubular SOFC single cell is open, the top end of the inner tube of the tubular SOFC single cell is closed, and a plurality of sections of closed areas and a plurality of sections of perforated areas are arranged on the tube wall of the inner tube and are sequentially and alternately arranged. According to the inner tube structure of the tubular SOFC single cell, the distribution uniformity of methanol on the surface of the anode of the solid oxide fuel cell can be effectively improved, so that the problem of serious carbon deposition caused by non-uniform distribution of methanol on the surface of the anode of the solid oxide fuel cell is effectively solved.

Description

Technical Field

[0001] The invention relates to a porous tubular methanol solid oxide fuel cell with closed ends. Background Art

[0002] Solid oxide fuel cell (SOFC) is an environmentally friendly power generation device that converts the chemical energy of reactants into electrical energy through electrochemical reactions. Due to the high operating temperature, solid oxide fuel cells can use a variety of fuels, such as methane, methanol, ethanol, ammonia, vegetable oil, sugar, glucose, propane, etc. Methanol is widely available and is liquid at room temperature. It has become one of the most ideal fuels for solid oxide fuel cells. Studies have shown that although methanol itself does not produce carbon deposits, CO produced by methanol cracking can cause carbon deposits in solid oxide fuel cells. In traditional methanol tubular solid oxide fuel cells, methanol flows along the inner tube to the top of the anode, and then flows from the top to the bottom along the outside of the inner tube. Therefore, the methanol concentration at the top of the anode is the highest, the pyrolysis is the fastest, and the carbon deposits are the most serious (the manifestation of serious carbon deposits is that carbon is generated on the surface of the anode active component, covering the surface of the anode active component, and the covered active component surface is no longer active, which leads to the attenuation of fuel cell performance). In response to the above problems, the prior art proposes a porous inner tube design, in which some methanol can enter the anode through the porous area to participate in the reaction, but most of the methanol flows along the inner tube to the top of the anode, and then flows from the top to the bottom along the outside of the inner tube. Although the carbon deposit on the top of the anode is reduced by the above method, it is still not negligible. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a solid oxide fuel cell that can effectively alleviate the problem of carbon deposition on the anode of methanol SOFC, thereby solving the problem of performance degradation of methanol solid oxide fuel cells due to carbon deposition, thereby shortening the battery life.

[0004] Technical solution: The methanol solid oxide fuel cell described in the present invention is a tubular SOFC cell stack, and the tubular SOFC cell stack contains a plurality of tubular SOFC single cells; along the movement direction of the fuel in the inner tube, the bottom end of the inner tube of the tubular SOFC single cell is open and the top end is closed, and the wall of the inner tube is provided with multiple closed areas and multiple open areas, and the multiple closed areas and the multiple open areas are arranged alternately in sequence; wherein, the open area is near the top, and the closed area is near the bottom.

[0005] A catalyst layer is disposed outside the tube wall corresponding to each section of the opening area, and the material selected for the catalyst layer is the anode material of the solid oxide fuel cell, such as Ni / YSZ or Ni / BZCY catalyst layer.

[0006] Wherein, the thickness of the catalyst layer is 550-600 μm.

[0007] Wherein, the multi-section open area includes a first open area near the top, a third open area near the bottom, and a second open area located between the first open area and the third open area; wherein the porosity of the first open area is 0.3-0.5, the porosity of the second open area is 0.3-1.0, and the porosity of the third open area is 0.5-0.6.

[0008] Wherein, the diameter of the holes in the multi-section open areas is not less than 1 μm.

[0009] The length of the first opening area is 11-25% of the total length of the inner tube, the length of the second opening area is 8-12% of the total length of the inner tube, and the length of the third opening area is 11-14% of the total length of the inner tube.

[0010] The multi-stage closed area includes a first closed area close to the bottom end, a second closed area between the second opening area and the third opening area, and a third closed area between the first opening area and the second opening area.

[0011] Wherein, the lengths of the first closed area, the second closed area and the third closed area are 17-23% of the total length of the inner tube.

[0012] Wherein, the wall thickness of the inner tube is 0.9-1.1 mm; the inner radius of the inner tube is 1.5-2.0 mm, and the inner radius of the anode tube is 4-6 mm.

[0013] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: in the tubular SOFC single cell of the present invention, methanol can only enter the anode through the porous structure of the inner tube, thereby reducing the methanol concentration at the top of the anode. Compared with the porous inner tube design, the porous inner tube with one end closed improves the uniformity of methanol distribution on the anode surface; at the same time, a catalyst layer with the same length as the porous structure area is added outside the porous structure of the porous inner tube. The addition of the catalyst layer allows methanol to be cracked before entering the anode, and the cracking products can directly enter the anode to participate in the electrochemical reaction, further reducing the occurrence of anode carbon deposition; through monitoring, it was found that the maximum methanol concentrations at the top, middle and bottom of the anode were almost the same, indicating that the uniformity of methanol distribution on the anode surface was effectively improved; the inner tube structure of the tubular SOFC single cell of the present invention can effectively improve the uniformity of methanol distribution on the anode surface of the solid oxide fuel cell, thereby effectively overcoming the serious carbon deposition problem caused by the uneven distribution of methanol on the anode surface of the solid oxide fuel cell (in areas with high methanol concentration, more CO is produced by methanol cracking, which easily leads to serious carbon deposition). BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural principle diagram of a tubular SOFC single cell of the present invention;

[0015] Figure 2 1 is a comparison diagram of the carbon deposition activity of the corresponding anodes of the porous inner tube of the prior art, the comparative example 1 and the porous inner tube with one end sealed in Example 1; a is the carbon deposition activity distribution of the porous inner tube of the prior art; b is the carbon deposition activity distribution of the porous inner tube of the comparative example 1; c is the carbon deposition activity distribution of the porous inner tube with one end sealed in Example 1;

[0016] Figure 3 Graphs showing the methanol concentration distribution on the anode surface of the porous inner tube of the prior art, the comparative example 1 and the porous inner tube with one end sealed in Example 1; a is the methanol concentration distribution on the anode surface corresponding to the porous inner tube of the prior art; b is the methanol concentration distribution on the anode surface corresponding to the porous inner tube of the comparative example 1; c is the methanol concentration distribution on the anode surface corresponding to the porous inner tube with one end sealed in Example 1;

[0017] Figure 4 1 is a carbon deposition activity of a porous inner tube with one end sealed and a distribution diagram of methanol concentration on the anode surface of Example 2; a is a carbon deposition activity of a porous inner tube with one end sealed in Example 2; b is a distribution diagram of methanol concentration on the anode surface corresponding to a porous inner tube with one end sealed in Example 2;

[0018] Figure 5 The carbon deposition activity comparison diagram of the porous inner tube with one end sealed without a catalyst layer in Example 2 and the porous inner tube with one end sealed with a catalyst layer in Example 3; a is the carbon deposition activity of the porous inner tube with one end sealed without a catalyst layer in Example 2; b is the carbon deposition activity of the porous inner tube with one end sealed with a catalyst layer in Example 3;

[0019] Figure 6 The methanol concentration distribution diagrams of the anode surface corresponding to Example 2 with a porous inner tube closed at one end and no catalyst layer and Example 3 with a porous inner tube closed at one end and a catalyst layer; a is the methanol concentration distribution of the anode surface corresponding to Example 2 with a porous inner tube closed at one end and no catalyst layer; b is the methanol concentration distribution of the anode surface corresponding to Example 3 with a porous inner tube closed at one end and a catalyst layer. DETAILED DESCRIPTION

[0020] like Figure 1As shown, the methanol solid oxide fuel cell of the present invention is a tubular SOFC cell stack, and the tubular SOFC cell stack includes a plurality of tubular SOFC single cells 1; the cell structure is an anode support layer 7, an anode functional layer 8, an electrolyte 9, a cathode functional layer 10 and a cathode support layer 11 from the inside to the outside, and the cavity 2 formed by the gap between the inner tube 3 and the anode support layer 7 is the anode reaction zone; along the moving direction of the fuel in the inner tube 3, the bottom end of the inner tube 3 of the tubular SOFC single cell is open and the top end is closed, and the wall of the inner tube 3 is provided with multiple closed areas and multiple open areas, and the multiple closed areas and the multiple open areas are arranged alternately in sequence; the fuel flows in through the opening at the bottom end of the inner tube 3, and enters the anode through the multiple open areas (the first open area 4, the second open area 5 and the third open area 6) to participate in the reaction, and the top end of the inner tube 3 is closed, and the closed top end is made of the same material as the closed section of the inner tube side wall, which can prevent the fuel from flowing into the top of the anode, thereby effectively preventing the serious carbon deposition on the top of the anode.

[0021] Example 1

[0022] Among them, in this embodiment, the multi-stage opening area includes a first opening area 4 near the top, a third opening area 6 near the bottom, and a second opening area 5 located between the first opening area 4 and the third opening area 6; the multi-stage closed area includes a first closed area 13 near the bottom, a second closed area 14 located between the second opening area 5 and the third opening area 6, and a third closed area 15 located between the first opening area 4 and the second opening area 5; the lengths of the first closed area 13, the second closed area 14 and the third closed area 15 are all 20 mm, and the lengths of the first opening area 4, the second opening area 5 and the third opening area 6 are all 10 mm; and the porosity of the first opening area 4, the second opening area 5 and the third opening area 6 is ε=0.5; the inner tube wall thickness w=1 mm, the inner tube inner radius R=1.5 mm, the inner radius of the anode tube is 4 mm, and there is a certain gap between the inner tube and the anode tube of the tubular solid oxide fuel cell.

[0023] Comparative Example 1

[0024] The only difference between Comparative Example 1 and Example 1 is that the top end of the inner tube 3 is open, and the rest of the structure is exactly the same as that of the inner tube in Example 1.

[0025] The maximum carbon deposition activity and methanol concentration distribution of the anode corresponding to the structures of the prior art, comparative example 1 and embodiment 1 are as follows: Figures 2-3 As shown. Figures 2-3It can be seen that compared with the porous inner tube with two ends open (the porous inner tube in the prior art refers to the porous inner tube disclosed in application number 2021114213287, the porous layer side wall is a porous layer side wall with a porosity of 0.5, and the thickness of the porous layer side wall is 2 mm; the inner wall of the inner tube (excluding the pipe with the porous layer side wall) is coated with a methanol pyrolysis catalyst layer, and the ratio of the length of the inner tube in the battery reaction zone to the length of the pipe with the porous layer side wall is 3:1, that is, if the length of the lower half of the inner tube in the battery reaction zone is 9 cm, the length of the pipe with the porous layer side wall is 3 cm), the maximum carbon deposition activity of the anode corresponding to the porous inner tube closed at one end in Example 1 of the present invention is increased from 51.8 ( Figure 2 a) Reduced to 23.01( Figure 2 c), the maximum methanol concentration is 6.06 mol / m 3 ( Figure 3 a) Reduced to 4.15 mol / m 3 ( Figure 3 c). When the structure is changed to comparative example 1, the maximum carbon deposition activity of the anode increases, becoming 75.63 ( Figure 2 b), the maximum methanol concentration on the anode surface becomes 6.72 mol / m 3 ( Figure 3 b).

[0026] Example 2

[0027] Among them, in this embodiment, the multi-stage open area includes a first open area 4 near the top, a third open area 6 near the bottom, and a second open area 5 between the first open area 4 and the third open area 6; the multi-stage closed area includes a first closed area 13 near the bottom, a second closed area 14 between the second open area 5 and the third open area 6, and a third closed area 15 between the first open area 4 and the second open area 5; the lengths of the first closed area 13, the second closed area 14 and the third closed area 15 are all 16mm, the length of the first open area 4 is 22mm, the porosity is 0.5, the length of the second open area 5 is 8mm, the porosity is 0.3, the length of the third open area 6 is 12mm, the porosity is 0.5, the wall thickness of the inner tube 3 is w=1mm, the inner radius of the inner tube 3 is R=1.5mm, and the inner radius of the anode tube is 4mm; at this time, the corresponding maximum carbon deposition activity and methanol concentration distribution are as follows Figure 4 shown.

[0028] pass Figure 4 It can be seen that compared with Example 1, the maximum carbon deposition activity of the porous inner tube with one end closed in Example 2 increased from 23.01 ( Figure 2 c) down to 17.56 ( Figure 4 a), the maximum methanol concentration is 4.15 mol / m 3 ( Figure 3 c) reduced to 3.63 mol / m3 ( Figure 4 b).

[0029] Example 3

[0030] In this embodiment, the multi-stage open area includes a first open area 4 near the top, a third open area 6 near the bottom, and a second open area 5 between the first open area 4 and the third open area 6; the multi-stage closed area includes a first closed area 13 near the bottom, a second closed area 14 between the second open area 5 and the third open area 6, and a third closed area 15 between the first open area 4 and the second open area 5; the lengths of the first closed area 13, the second closed area 14, and the third closed area 15 are all 16 mm, the length of the first open area 4 is 22 mm, and the porosity is 0.3, the length of the second open area 5 is 8 mm, and the porosity is 1, the length of the third open area 6 is 12 mm, and the porosity is 1. The rate is 0.5, the wall thickness of the inner tube 3 is w=1mm, the inner radius of the inner tube 3 is R=1.5mm, and the inner radius of the anode tube is 4mm; a catalyst layer 12 is provided on the outside of the tube wall corresponding to the first opening area 4 and the third opening area 6, and the laying length of the catalyst layer 12 is consistent with the length of the first opening area 4 and the third opening area 6; the material selected for the catalyst layer 12 is the anode material of the solid oxide fuel cell, such as Ni / YSZ or Ni / BZCY catalyst layer; according to thickness analysis, the thickness of the catalyst layer 12 is set to 550μm, and the addition of the catalyst layer can make methanol catalyzed by the catalyst layer before flowing into the anode from the opening area, and the generated synthesis gas product can directly enter the anode area to react, thereby reducing the carbon deposition on the anode. In this embodiment, appropriately reducing the porosity of the first opening area 4 and then increasing the porosity of the second opening area 5 can help reduce carbon deposition. At this time, the maximum carbon deposition activity of the anode area is further reduced compared with that of Example 2 without a catalyst layer, see Figure 5 , and the methanol concentration distribution on the anode surface is more uniform, see Figure 6 .

[0031] pass Figures 5-6 It can be seen that compared with the porous inner tube, the maximum methanol concentration of the porous inner tube with one end closed in Example 3 is 6.06 mol / m 3 ( Figure 3 a) Reduced to 1.48 mol / m 3 ( Figure 6 b), decreased by 75.5%; in addition, the maximum carbon deposition activity also decreased from 51.8 ( Figure 2 a) reduced to 4.91( Figure 5 b).

[0032] The tubular solid oxide fuel cell (anode tube) of the present invention is closed at one end, and the inner tube is also closed at one end; the inner tube wall is a multi-section porous structure, and the rest is a dense structure; because the top of the inner tube is closed, the fuel can only enter the anode through the porous structure of the inner tube to participate in the electrochemical reaction, and the uniformity of the methanol concentration on the anode surface can be effectively improved by matching the porosity, thickness, length, and inner radius of the inner tube opening area, thereby alleviating the serious carbon deposition problem caused by excessive methanol concentration on the anode top of the traditional tubular methanol solid oxide fuel cell, delaying the battery degradation rate, and improving the battery life. In addition, the present invention also adds a catalyst layer outside the porous structure, and the catalyst layer can catalytically crack the methanol before entering the anode, and the cracking product directly enters the anode reaction, further reducing the occurrence of carbon deposition.

Claims

1. A porous tubular methanol solid oxide fuel cell with closed ends, wherein the fuel cell is a tubular SOFC cell stack, wherein the tubular SOFC cell stack comprises a plurality of tubular SOFC single cells (1); characterized in that: Along the moving direction of the fuel in the inner tube (3), the bottom end of the inner tube of the tubular SOFC single cell (1) is open and the top end is closed, and the wall of the inner tube (3) is provided with multiple sections of closed areas and multiple sections of open areas, which are alternately arranged in sequence.

2. The porous tubular methanol solid oxide fuel cell according to claim 1, characterized in that: A catalyst layer (12) is arranged outside the tube wall corresponding to the opening area, and the catalyst layer (12) is a Ni / YSZ catalyst layer or a Ni / BZCY catalyst layer.

3. The porous tubular methanol solid oxide fuel cell according to claim 2, characterized in that: The thickness of the catalyst layer (12) is 550-600 μm.

4. The porous tubular methanol solid oxide fuel cell according to claim 1, characterized in that: The multi-stage open area comprises a first open area (4) close to the top, a third open area (6) close to the bottom, and a second open area (5) located between the first open area (4) and the third open area (6); wherein the porosity of the first open area (4) is 0.3 to 0.5, the porosity of the second open area (5) is 0.3 to 1.0, and the porosity of the third open area (6) is 0.5 to 0.

6.

5. The porous tubular methanol solid oxide fuel cell according to claim 4, characterized in that: The diameter of the holes in the multi-stage open areas is not less than 1 μm.

6. The porous tubular methanol solid oxide fuel cell according to claim 4, characterized in that: The length of the first opening zone (4) is 11 to 25% of the total length of the inner tube (3), the length of the second opening zone (5) is 8 to 12% of the total length of the inner tube (3), and the length of the third opening zone (6) is 11 to 14% of the total length of the inner tube (3).

7. The porous tubular methanol solid oxide fuel cell according to claim 1, characterized in that: The multi-stage closed area includes a first closed area (13) close to the bottom end, a second closed area (14) located between the second open area (5) and the third open area (6), and a third closed area (15) located between the first open area (4) and the second open area (5).

8. The porous tubular methanol solid oxide fuel cell according to claim 7, characterized in that: The lengths of the first closed area (13), the second closed area (14) and the third closed area (15) are 17 to 23% of the total length of the inner tube (3).

9. The porous tubular methanol solid oxide fuel cell according to claim 1, characterized in that: The wall thickness of the inner tube (3) is 0.9-1.1 mm.

10. The porous tubular methanol solid oxide fuel cell according to claim 1, characterized in that: The inner radius of the inner tube (3) is 1.5 to 2.0 mm; the inner radius of the outer anode tube of the inner tube (3) is 4 to 6 mm.

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