JP7771666B2 - Fuel Gas Reformer - Google Patents

Description

The present invention relates to a fuel gas reformer.

A conventional fuel gas reformer is known, for example, from the technology described in Patent Document 1. The reformer described in Patent Document 1 is a device that supplies ammonia and an oxygen-containing gas and produces hydrogen through a reforming reaction. The reformer uses a honeycomb catalyst that promotes the autothermal reforming (ATR) reaction.

Patent Document 2 also describes an ammonia reforming catalyst. In Patent Document 2, ammonia and oxygen-containing gas pass through a reactor carrying the ammonia reforming catalyst from the inlet to the outlet, making it easier for a combustion reaction to occur near the inlet. As a result, the temperature near the inlet is about 200°C higher than near the outlet.

JP 2015-188820 A Japanese Patent Application Laid-Open No. 2010-214225

The technology described in Patent Document 2 aims to control the temperature rise in the catalyst layer and prevent damage to the reformer and catalyst degradation, but there is still a temperature difference of around 200°C in the reformer, which means that damage and degradation to the reformer cannot be sufficiently prevented. Lowering the reformer temperature could be considered to solve the above problem, but in this case, the temperature near the reactor outlet would be low, resulting in a deterioration in reforming efficiency. Furthermore, the technology disclosed in Patent Document 1 makes no mention of preventing damage and degradation to the reformer caused by temperature differences.

The present invention was made in consideration of the above problems, and its object is to provide a fuel gas reforming device that can minimize the temperature difference caused by the reaction in the honeycomb support.

In order to solve the above problems, the present invention provides a fuel gas reforming device comprising: a porous honeycomb support having inflow cells that are open at their upstream ends and plugged at their downstream ends, outflow cells that are open at their downstream ends and plugged at their upstream ends, and partition walls separating the inflow cells and the outflow cells; and an ATR catalyst supported on the honeycomb support and including a combustion catalyst for combusting fuel gas and a reforming catalyst for reforming the fuel gas into hydrogen , wherein the partition walls have inflow cell side walls facing the inflow cells, outflow cell side walls facing the outflow cells, and an inner wall portion sandwiched between the inflow cell side walls and the outflow cell side walls , and the ATR catalyst comprises an ATR catalyst layer supported on the surface of the inflow cell side walls, a first catalyst-impregnated portion impregnated in the inflow cell side walls, and a second catalyst-impregnated portion impregnated in the inner wall portion, and the outflow cell side walls are provided with a catalyst-non-impregnated portion.

In this type of reformer, fuel gas flows into the inlet cells, passes through the partition walls, and flows out into the outlet cells. By arranging the inlet cells, partition walls, and outlet cells, the location through which the fuel gas passes is less likely to be biased within the partition walls. This is because the pressure loss through the partition walls is high, so the fuel gas spreads throughout the entire space of the inlet cells before passing through almost the entire partition wall. The partition walls are loaded with an ATR catalyst. By preventing the location through which the fuel gas passes through the partition walls from being biased, the temperature difference in the partition walls can be minimized.

Furthermore , since the ATR catalyst is supported on the side wall of the inflow cell, even if an ATR catalyst that may peel off is used, the peeled powder will not flow into the outflow cell.

In addition , since the ATR catalyst is supported inside the partition walls , the amount of the ATR catalyst can be further increased, and therefore the reforming efficiency can be further improved.

The present invention provides a fuel gas reforming device that can minimize the temperature difference caused by the reaction in the honeycomb support.

1 is a perspective view schematically showing an ammonia gas reforming apparatus according to a first embodiment. FIG. 2 is a front view showing the upstream end of the ammonia gas reformer. 3 is a view taken along the line AA in FIG. 2. 4A is an enlarged view of FIG. 2, and FIG. 4B is a view taken along the line AA in FIG. 4A. 1 is a graph showing the change in temperature from the inlet side to the outlet side of the ammonia gas reformer. 6A is a cross-sectional view showing a layer structure according to the second embodiment, and FIG. 6B is a view taken along the line CC in FIG. 6A. 7A is a cross-sectional view showing a layer structure according to the third embodiment, and FIG. 7B is a view taken along the line DD in FIG. 7A. 8A is a cross-sectional view showing a layer structure according to the fourth embodiment, and FIG. 8B is a view taken along the line EE in FIG. 8A. 9A is a cross-sectional view showing a layer structure according to the fifth embodiment, and FIG. 9B is a view taken along line GG in FIG. 9A.

(First embodiment)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the accompanying drawings. In this embodiment, an ammonia gas reformer will be described as a fuel gas reformer that uses ammonia gas as fuel gas.

As shown in FIG. 1, the ammonia gas reforming apparatus 11 of this embodiment has a honeycomb carrier 12 formed from porous ceramic having a honeycomb structure. The honeycomb carrier 12 has a first end face 13, which is one end face, a second end face 14, which is the other end face, and a cylindrical outer wall 15.

As shown in Figures 1 and 2, the honeycomb support 12 has a plurality of inlet cells 16, a plurality of outlet cells 17, and partition walls 18. As shown in Figure 3, the inlet cells 16 are arranged inside the outer peripheral wall 15 and extend from the first end face 13 to the second end face 14, with the openings at the second end face 14 being plugged with outlet plugs 19. The outlet cells 17 are adjacent to the inlet cells 16 and extend from the first end face 13 to the second end face 14, with the openings at the first end face 13 being plugged with inlet plugs 20.

The partition walls 18 define a plurality of inlet cells 16 and outlet cells 17. The plurality of inlet cells 16 and outlet cells 17 are arranged in a lattice pattern by being defined by the partition walls 18. Therefore, as shown in FIG. 2, the inlet cells 16 and outlet cells 17 are arranged alternately in a checkerboard pattern on the first end surface 13. The partition walls 18 are surrounded by the cylindrical outer wall 15, so the honeycomb support 12 is formed in a cylindrical shape. The honeycomb support 12 of this embodiment is a wall-flow type honeycomb support in which fluid flows from the inlet cells 16 to the outlet cells 17. In FIG. 3, the flow of ammonia gas is indicated by arrow F.

As shown in Figure 4, the partition wall 18 has an inflow cell side wall portion 22 including a surface 21 on the inflow cell 16 side, an outflow cell side wall portion 24 including a surface 23 on the outflow cell 17 side, and an inner wall portion 25 excluding the inflow cell side wall portion 22 and the outflow cell side wall portion 24.

In this embodiment, the honeycomb support 12 is formed from porous ceramics. However, other ceramics with excellent heat resistance, such as cordierite, mullite, and silicon nitride, may also be used, or a combination of multiple ceramics may be used. The material for the honeycomb support 12 preferably contains at least one material selected from the group consisting of cordierite, silicon carbide, silicon nitride, and mullite. More specifically, the material preferably contains 20% by mass or more of a material listed in this group, more preferably 30% by mass or more, and particularly preferably 50% by mass or more. The honeycomb support 12 is obtained by extruding a ceramic material kneaded with water and a binder using an extruder, cutting and drying the extruded body, and firing it after drying.

The ammonia gas reformer 11 includes a honeycomb support 12 and an ATR catalyst supported on the honeycomb support 12. The ATR catalyst reforms ammonia gas in an autothermal reformer (ATR). The ATR catalyst burns ammonia gas in a temperature range of, for example, approximately 200°C to 400°C, and reforms the ammonia gas in a temperature range higher than the combustion temperature of ammonia gas (for example, approximately 250°C to 500°C). The system includes a combustion catalyst that burns ammonia gas and a reforming catalyst that reforms ammonia gas into hydrogen. The catalytic metals that can be used for the combustion catalyst include V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Ag, W, Re, Os, Ir, and Pt. In addition, the catalytic metals that can be used for the reforming catalyst include V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Ag, W, Re, Os, Ir, and Pt.

As shown in Figure 4, the ATR catalyst in this embodiment is supported as an ATR catalyst layer 26 on the inlet cell side wall 22. The required amount of ATR catalyst is supported by applying catalyst slurry to the inlet cell side wall 22 using a washcoat method, removing excess ATR catalyst with an air blow, and drying the ATR catalyst at 120°C. The application and drying of the catalyst slurry is repeated. The honeycomb support 12 is then fired, and the ATR catalyst layer 26 is formed by performing a reduction treatment after firing.

In this embodiment, an ammonia supplier (not shown) for storing ammonia and an air supplier (not shown) for supplying air are arranged upstream of the ammonia gas reformer 11. Furthermore, downstream of the ammonia gas reformer 11 is provided a reformed gas utilization device (not shown) that utilizes the reformed gas reformed by the ammonia gas reformer 11. Therefore, ammonia gas obtained by mixing ammonia and air is supplied to the ammonia gas reformer 11, which reforms the ammonia gas to produce reformed gas. The produced reformed gas is utilized by the reformed gas utilization device.

Next, we will explain the reforming of ammonia gas using the ammonia gas reformer 11 according to this embodiment. First, ammonia gas, a mixture of ammonia and air, is supplied from the upstream side of the ammonia gas reformer 11 toward the ammonia gas reformer 11. Therefore, the ammonia gas supplied to the ammonia gas reformer 11 flows into the inlet cells 16 through the openings of the inlet cells 16 on the first end face 13 of the honeycomb support 12.

Ammonia gas that flows into the inlet cell 16 flows out into the outlet cell 17 through the ATR catalyst layer 26 and the partition wall 18. The ATR catalyst layer 26 combusts a portion of the ammonia gas passing through the ATR catalyst layer 26, and reforms the remaining ammonia gas that passes through the ATR catalyst layer 26 using the heat from the combustion of the ammonia gas. As a result, reformed gas flows into the outlet cell 17 and flows out from the outlet cell 17. Although ammonia gas passes through the partition wall 18, the pressure loss of the ammonia gas due to the partition wall 18 is high, so the ammonia gas passes through the entire space of the inlet cell 16 only after it has spread throughout the space. Therefore, the ammonia gas that has spread throughout the entire space of the inlet cell 16 passes through the partition wall 18 evenly without any unevenness.

Because ammonia gas passes through the partition walls 18 evenly without bias, the combustion reaction does not become excessively biased in the longitudinal direction of the honeycomb support 12 from the first end face 13 to the second end face 14. In other words, the combustion reaction is less likely to become biased in the longitudinal direction of the honeycomb support 12. Specifically, as shown by the solid line graph in Figure 5, in this embodiment, the temperature difference between the upstream and downstream of the honeycomb support 12 in the ammonia gas reformer 11 is suppressed. Note that the dotted line graph in Figure 5 shows a comparative example using a flow-through type honeycomb support. The temperature difference in this embodiment is smaller than in the comparative example.

Furthermore, because ammonia gas reforming using an ATR catalyst is an endothermic reaction, a decrease in the temperature of the ammonia gas reduces the reforming efficiency. As shown in the graph in Figure 5, if T1 is the lower limit temperature at which ammonia gas is efficiently reformed and T2 is the upper limit temperature at which the honeycomb support 12 is not damaged or deteriorated, the temperature in the ammonia gas reformer 11 of this embodiment is above T1 and below T2. Incidentally, in the comparative example, because the honeycomb support 12 is a flow-through type, the fuel gas passes through the cell space from the inlet to the outlet, and the combustion reaction is concentrated upstream of the honeycomb support. Therefore, the temperature upstream of the honeycomb support in the comparative example exceeds T2, which may damage or deteriorate the honeycomb support 12. Furthermore, the temperature downstream of the honeycomb support in the comparative example is below T1, reducing the ammonia gas reforming efficiency.

The ammonia gas reforming device 11 according to this embodiment has the following advantages.
(1) Ammonia gas flows into the inflow cells 16, passes through the partition walls 18, and flows out into the outflow cells 17. By arranging the inflow cells 16, the partition walls 18, and the outflow cells 17, the ammonia gas is less likely to pass through unevenly within the partition walls 18. This is because the pressure loss through the partition walls 18 is high, so the ammonia gas spreads throughout the entire space of the inflow cells 16 and then passes through almost the entire partition walls 18. The partition walls 18 are supported with an ATR catalyst as the ATR catalyst layer 26. Since the fuel gas is less likely to pass unevenly through the partition walls 18, the temperature difference in the partition walls 18 can be minimized. As a result, damage and deterioration of the ammonia gas reformer 11 can be prevented, and the efficiency of reforming ammonia by the ATR catalyst can be improved.

(2) The partition wall 18 has an inlet cell side wall 22 facing the inlet cell 16 and an outlet cell side wall 24 facing the outlet cell 17, and the ATR catalyst as the ATR catalyst layer 26 is supported on the inlet cell side wall 22. Therefore, even if an ATR catalyst that may peel off is used in the ATR catalyst layer 26 on the inlet cell 16 side, the peeled powder from the peeled ATR catalyst remains in the inlet cell 16 and does not flow into the outlet cell 17. Therefore, the peeled powder from the ATR catalyst does not adversely affect the reformed gas utilization device located downstream of the ammonia gas reformer 11.

Second Embodiment
Next, an ammonia gas reforming apparatus according to a second embodiment will be described. This embodiment is an example in which an ATR catalyst layer is supported in the inlet cells of a honeycomb support, but differs from the first embodiment in that the ATR catalyst layer is a reforming catalyst layer supported on the side walls of the inlet cells, and a combustion catalyst is laminated on the reforming catalyst layer. In this embodiment, the same components as those in the first embodiment will be referred to and the same reference numerals will be used.

As shown in Figures 6(a) and 6(b), in an ammonia gas reformer 31 according to this embodiment, an ATR catalyst layer 32 is supported on the inlet cell side wall portion 22 of the honeycomb support 12. The ATR catalyst layer 32 includes a reforming catalyst layer 34 supported on the inlet cell side wall portion 22 and a combustion catalyst layer 33 supported so as to cover the reforming catalyst layer 34. In other words, the ATR catalyst layer 32 has a layered structure in which the combustion catalyst layer 33 and the reforming catalyst layer 34 are not mixed but are stacked on top of each other.

In this embodiment, ammonia gas supplied to the honeycomb support 12 flows into the inlet cells 16 through the openings of the inlet cells 16 on the first end surface 13 of the honeycomb support 12. The ammonia gas that flows into the inlet cells 16 passes through the combustion catalyst layer 33 on the surface side of the ATR catalyst layer 32, then passes through the reforming catalyst layer 34 on the partition wall 18 side, and then flows out to the outlet cells 17 through the partition wall 18. The combustion catalyst layer 33 combusts a portion of the ammonia gas that passes through the combustion catalyst layer 33, and the reforming catalyst layer 34 reforms the ammonia gas that passes through the reforming catalyst using the heat generated by the combustion of the ammonia gas.

In this embodiment, the ATR catalyst layer 32 supported on the inlet cell sidewall 22 has the combustion catalyst layer 33 laminated on the reforming catalyst layer 34, allowing the catalytic function of the ATR catalyst to be separated. For example, the reaction as an ATR catalyst can be easily controlled by separately adjusting the amounts of combustion catalyst and reforming catalyst. In addition, because ammonia gas passes through the combustion catalyst layer 33 before passing through the reforming catalyst layer 34, the heat required for reforming ammonia can be easily secured through combustion. Furthermore, because the ATR catalyst is not supported on the outlet cell sidewall 24, even if an ATR catalyst that may peel off is used, peeled powder will not be sent downstream of the honeycomb support 12.

(Third embodiment)
Next, an ammonia gas reforming apparatus according to a third embodiment will be described. This embodiment differs from the first embodiment in that the ATR catalyst is supported on the honeycomb support body not only on the inlet cell side but also on the outlet cell side. In this embodiment, the same components as those in the first embodiment will be referred to and the same reference numerals will be used.

As shown in Figures 7(a) and 7(b), in an ammonia gas reforming apparatus 41 according to this embodiment, an ATR catalyst layer 26 is supported on the inlet cell side wall portion 22 of the honeycomb support 12, and an ATR catalyst layer 42 is supported on the outlet cell side wall portion 24. The ATR catalyst layer 26 supported on the inlet cell side wall portion 22 and the ATR catalyst layer 42 supported on the outlet cell side wall portion 24 are composed of catalysts having the same composition.

In this embodiment, ammonia gas supplied to the honeycomb support 12 flows into the inlet cells 16 through openings of the inlet cells 16 on the first end face 13 of the honeycomb support 12. The ammonia gas that flows into the inlet cells 16 flows through the ATR catalyst layer 26, the partition walls 18, and the ATR catalyst layer 32 and flows out to the outlet cells 17. The ATR catalyst layers 26, 42 combust a portion of the ammonia gas passing through the ATR catalyst layers 26, 42, and reform the remaining ammonia gas using the heat from the combustion of the ammonia gas.

The ammonia gas reforming apparatus 41 of this embodiment achieves the same effect as the first embodiment in terms of temperature uniformity in the honeycomb support 12. Furthermore, the ammonia gas reforming apparatus 41 of this embodiment has an ATR catalyst layer 26 supported on the inlet cell side wall 22 and an ATR catalyst layer 42 supported on the outlet cell side wall 24, so the amount of ATR catalyst in the honeycomb support 12 can be increased compared to the first embodiment. Therefore, the ammonia reforming efficiency can be improved compared to the first embodiment.

In this embodiment, the ATR catalyst layers 26, 42 have the same catalyst composition. However, the ATR catalyst layers 26, 42 may have different catalyst compositions. For example, the ATR catalyst layer 26 on the inlet cell sidewall 22 may be made of a catalyst containing at least one of a cobalt-based catalyst, a rhodium-based catalyst, a ruthenium-based catalyst, and a palladium-based catalyst. On the other hand, the ATR catalyst layer 42 on the outlet cell sidewall 24 may contain at least one of a cobalt-based catalyst, a rhodium-based catalyst, a ruthenium-based catalyst, and a palladium-based catalyst, as long as it is made of a different material from the ATR catalyst layer 26 on the inlet cell sidewall 22. In this case, appropriate catalysts can be selected for the ATR catalyst layer 26 on the inlet cell 16 side and the ATR catalyst layer 42 on the outlet cell 17 side, thereby improving the ammonia reforming efficiency.

(Fourth embodiment)
Next, an ammonia gas reforming apparatus according to a fourth embodiment will be described. This embodiment differs from the first embodiment in that a combustion catalyst is supported on the inlet cell side of the honeycomb support, and a reforming catalyst is supported on the outlet cell side. In this embodiment, the same components as those in the first embodiment will be referred to and the same reference numerals will be used.

As shown in Figures 8(a) and 8(b), the ammonia gas reformer 51 of this embodiment has a combustion catalyst layer 52 supported on the inlet cell side wall portion 22 of the honeycomb support 12, and a reforming catalyst layer 53 supported on the outlet cell side wall portion 24. The combustion catalyst of the combustion catalyst layer 52 and the reforming catalyst of the reforming catalyst layer 53 are the same as the combustion catalyst and reforming catalyst of the first embodiment.

In this embodiment, ammonia gas supplied to the honeycomb support 12 flows into the inlet cells 16 through openings of the inlet cells 16 on the first end face 13 of the honeycomb support 12. The ammonia gas that flows into the inlet cells 16 flows out to the outlet cells 17 through the combustion catalyst layer 52, the partition walls 18, and the reforming catalyst layer 53. The combustion catalyst layer 52 combusts a portion of the ammonia gas that passes through, and the reforming catalyst layer 53 reforms the remaining ammonia gas that passes through using the heat from the combustion of the ammonia gas.

In this embodiment, the combustion catalyst contained in the ATR catalyst is supported on the inlet cell side wall 22 as the combustion catalyst layer 52, and the reforming catalyst contained in the ATR catalyst is supported on the outlet cell side wall 24 as the reforming catalyst layer 53, so the catalytic functions of the ATR catalyst can be separated. For example, by adjusting the amounts of the combustion catalyst and reforming catalyst separately, it becomes easier to control the reaction as an ATR catalyst. Furthermore, in this embodiment, the heat required for reforming fuel gas can be easily obtained in the inlet cell 16, which improves the efficiency of reforming ammonia gas by the reforming catalyst layer 53 in the outlet cell 17.

Fifth Embodiment
Next, an ammonia gas reforming apparatus according to this embodiment will be described. The ammonia gas reforming apparatus of this embodiment differs from the first embodiment in that the ATR catalyst is supported on the inlet cell side walls and on the interior of the partition walls excluding the inlet cell side walls. In this embodiment, the same components as those in the first embodiment will be referred to and will be designated by the same reference numerals.

As shown in Figures 9(a) and 9(b), in an ammonia reformer 61 according to this embodiment, an ATR catalyst layer 26 is supported on the inlet cell side wall 22, and the ATR catalyst is impregnated in the partition 18 at a portion other than the inlet cell side wall 22. That is, the ATR catalyst is impregnated in the inner wall 25, which is the interior of the partition 18. In Figure 9(b), the portion of the partition 18 impregnated with the ATR catalyst is referred to as a catalyst-impregnated portion 62, and the portion of the partition 18 not impregnated with the ATR catalyst is referred to as a catalyst-non-impregnated portion 63. In this embodiment, part of the inner wall 25 is the catalyst-non-impregnated portion 63, and the remainder is the catalyst-impregnated portion 62.

In this embodiment, ammonia gas supplied to the honeycomb support 12 flows into the inlet cells 16 through the openings of the inlet cells 16 on the first end face 13 of the honeycomb support 12. The ammonia gas that flows into the inlet cells 16 flows through the ATR catalyst layer 26 and the partition walls 18 and into the outlet cells 17. The ATR catalyst in the catalyst-impregnated section 72 combusts a portion of the ammonia gas that passes through the partition walls 18 and reforms the remaining ammonia gas using the heat from the combustion of the ammonia gas.

This embodiment achieves the same effect as the first embodiment in terms of temperature uniformity in the honeycomb support 12. Furthermore, the ammonia reformer 61 of this embodiment can combust and reform ammonia gas passing through the partition walls 18. Furthermore, by impregnating the partition walls 18 with the ATR catalyst, the amount of ATR catalyst can be increased compared to the first embodiment, thereby further improving the efficiency of reforming ammonia gas. Furthermore, because an ATR catalyst layer is not provided on the outflow cell side, the ATR catalyst in the honeycomb support 12 can be increased without producing peeled powder of the ATR catalyst.

In this embodiment, a portion of the inner wall portion 25 is the catalyst-non-impregnated portion 63, and the remainder is the catalyst-impregnated portion 62, but this is not limited to this. For example, the entire partition wall 18 may be impregnated with the ATR catalyst. Furthermore, an ATR catalyst layer 26 may be provided on the outflow cell side wall portion 24.

The above embodiment shows one embodiment of the present invention, and the present invention is not limited to the above embodiment. Various modifications are possible within the scope of the invention, as described below.

- In the above embodiment, ammonia gas was used as an example of the fuel gas, but this is not limited to this. The fuel gas may be a hydrocarbon gas such as methane, in addition to ammonia gas. In this case, an ATR catalyst suitable for reforming the hydrocarbon gas may be selected.

11, 31, 41, 51, 61 Ammonia gas reforming device 12 Honeycomb support 13 First end face 14 Second end face 15 Outer peripheral wall 16 Inlet cell 17 Outlet cell 18 Partition wall 19 Outlet plug 20 Inlet plug 21 Surface 22 Inlet cell side wall 23 Surface 24 Outlet cell side wall 25 Inner wall 26, 32, 42 ATR catalyst layer 33, 52 Combustion catalyst layer 34, 53 Reforming catalyst layer 62 Catalyst impregnated portion 63 Catalyst non-impregnated portion F Arrow (flow of ammonia gas)

Claims (1)

a porous honeycomb support having inlet cells each having an open upstream end and a plugged downstream end, outlet cells each having an open downstream end and a plugged upstream end, and partition walls separating the inlet cells from the outlet cells;
a fuel gas reforming apparatus including an ATR catalyst supported on the honeycomb support and including a combustion catalyst for burning fuel gas and a reforming catalyst for reforming the fuel gas into hydrogen ,
The partition wall is
an inflow cell sidewall portion facing the inflow cell;
an outflow cell sidewall portion facing the outflow cell;
an inner wall portion sandwiched between the inflow cell side wall portion and the outflow cell side wall portion ;
the ATR catalyst comprises an ATR catalyst layer supported on the surface of the inlet cell side wall portion, a first catalyst-impregnated portion impregnated in the inlet cell side wall portion, and a second catalyst-impregnated portion impregnated in the inner wall portion,
A fuel gas reforming apparatus, characterized in that a catalyst-unimpregnated portion is provided on the side wall of the outflow cell.