REACTOR

Reactor includes: first-flow-passage formed in band-shape to extend in length-direction and width-direction and in spiral-shape centered on vertical-axis parallel to width-direction and having open upper-end-surface; second-flow-passage formed in spiral-shape to be radially arranged alternately with first-flow-passage on vertical-cross-section including vertical-axis and having open upper-end-surface to communicate with upper-end-surface of first-flow-passage; reaction-liquid-supplying-flow-passage through which reaction-liquid is supplied to supplying-portion provided at lower-end of maximum-outer-diameter-portion of first-flow-passage; reaction-liquid-discharging-flow-passage through which reaction-liquid is discharged from discharging-portion provided at maximum-outer-diameter-portion of second-flow-passage; and return-flow-passage connecting first-connecting-portion provided at lower-end of maximum-outer-diameter-portion of first-flow-passage and second-connecting-portion provided at maximum-outer-diameter-portion of second-flow-passage. Height of upper-end-surface of first-flow-passage and height of upper-end-surface of second-flow-passage are substantially same as each other all over in radial direction. Lower-end-surface of second-flow-passage is positioned above lower-end-surface of first-flow-passage all over in radial direction and is formed to be inclined downward toward radial outer side.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2023-142252 filed on Sep. 1, 2023, the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a reactor.

Description of the Related Art

In the related art, reactors configured to reform fuel are known. A reactor described in JP 2022-112890 A is configured as a double-pipe reactor having a reaction field between an outer pipe member and an inner pipe member, which are provided coaxially, and circulates a heat carrier through the side at the inner circumference of the inner pipe member and circulates fuel through the reaction field to be reformed.

In this type of reactor, it is necessary to increase the volume of the reaction field in order to increase the amount of the reformed fuel generated. However, in the double-pipe reactor described in JP 2022-112890 A, in order to increase the volume of the reaction field, the total length becomes longer proportionally, and it is difficult to efficiently increase the volume of the reaction field.

SUMMARY OF THE INVENTION

An aspect of the present invention is a reactor, including: a first flow passage formed in a band shape to extend in a length direction and a width direction and formed in a spiral shape centered on a vertical axis parallel to the width direction and having an open upper end surface; a second flow passage formed in a spiral shape centered on the vertical axis to be radially arranged alternately with the first flow passage on a vertical cross section including the vertical axis and having an open upper end surface to communicate with the upper end surface of the first flow passage; a reaction liquid supplying flow passage through which reaction liquid is supplied to a supplying portion provided at a lower end of a maximum outer diameter portion of the first flow passage centered on the vertical axis; a reaction liquid discharging flow passage through which the reaction liquid is discharged from a discharging portion provided at a maximum outer diameter portion of the second flow passage centered on the vertical axis; and a return flow passage connecting a first connecting portion provided at the lower end of the maximum outer diameter portion of the first flow passage and a second connecting portion provided at the maximum outer diameter portion of the second flow passage. A height of the upper end surface of the first flow passage and a height of the upper end surface of the second flow passage are substantially same as each other all over in a radial direction centered on the vertical axis. A lower end surface of the second flow passage is positioned above a lower end surface of the first flow passage all over in the radial direction and is formed to be inclined downward toward a radial outer side centered on the vertical axis.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference toFIGS.1to11. A reactor according to the embodiments of the present invention is a flow reactor in which a reaction liquid is circulated to perform a reaction. Hereinafter, in particular, a reforming reactor that is applied to a compression ignition engine mounted to a vehicle and reforms fuel supplied from a fuel tank to the engine by causing an oxidation reaction of the fuel will be described.

The average global temperature is maintained in a warm state suitable for living things by greenhouse gases in the atmosphere. To be specific, heat radiated from the ground surface that has been heated by sunlight to outer space is partially absorbed by the greenhouse gases, and is re-radiated to the ground surface, and the atmosphere is maintained in a warm state. Increasing concentrations of greenhouse gases in the atmosphere cause an increase in average global temperature (global warming). Carbon dioxide is a greenhouse gas that greatly contributes to global warming, and its concentration in the atmosphere depends on the balance between carbon fixed on or in the ground in the form of plants or fossil fuels and carbon present in the atmosphere in the form of carbon dioxide. For example, the carbon dioxide in the atmosphere is absorbed through photosynthesis in the growth process of plants, causing a decrease in carbon dioxide concentration in the atmosphere. The carbon dioxide is also released into the atmosphere through combustion of fossil fuels, causing an increase in the carbon dioxide concentration in the atmosphere. In order to mitigate global warming, it is necessary to reduce carbon emissions by replacing fossil fuels with a renewable energy source such as sunlight or wind power, or renewable fuel derived from biomass.

As such a renewable fuel, low-octane gasoline obtained by Fischer-Tropsch (FT) synthesis is becoming widespread. Low-octane gasoline has high ignitability and can be applied to a compression ignition engine. However, low-octane gasoline is still in the stage of becoming widespread and is not yet sold in some areas. On the other hand, regular octane gasoline for a spark ignition engine, which is currently widespread, has low ignitability, and cannot be applied to a compression ignition engine as it is.

By placing a reforming reactor in a fuel supply path from a fuel tank to an injector of an engine and reforming the fuel as necessary, both low-octane gasoline and regular octane gasoline can be compression-ignited in a single engine. Thus, in this embodiment, the reactor is configured as below such that mountability to the vehicle can be improved by efficiently increasing the volume of the reaction field.

FIG.1is an assembled perspective view illustrating a partially cut-out reactor100according to an embodiment of the present invention.FIG.2is a cross-sectional view of the reactor100taken along line II-II inFIG.1.FIG.3is a cross-sectional view of the reactor100taken along line III-III inFIG.2.FIG.4is a cross-sectional view of the reactor100taken along line IV-IV inFIG.2. Hereinafter, a direction radially extending from a vertical axis C is defined as a radial direction, and a direction along a circumference of a circle centered on the vertical axis C is defined as a circumferential direction.

As illustrated inFIG.1, the reactor100has an upper piece100A and a lower piece100B formed using a metal material having high thermal conductivity. For example, in a case where the reactor100is formed by additive manufacturing (AM) or the like, a partition wall or the like separating flow passages can be thinned, and the entire reactor100can be reduced in size. As illustrated inFIGS.1and2, the upper piece100A and the lower piece100B are configured to be detachably attached to each other via a seal ring (not illustrated) with a bolt and a nut (not illustrated). Consequently, maintainability of the inside of the reactor100is improved.

In the lower piece100B of the reactor100, a reaction flow passage10through which fuel as a reaction liquid circulates and a heat carrier flow passage20through which a heat carrier circulates are formed. As illustrated inFIGS.1to4, the reaction flow passage10and the heat carrier flow passage20are configured to have a band shape to extend in a width direction parallel to the vertical axis C and a length direction perpendicular to the width direction, respectively, and are configured to have a helical or spiral shape centered on the vertical axis C, and are alternately arranged in the radial direction. By making the reactor100helical or spiral, the volume of the reaction field can be efficiently increased.

As illustrated inFIGS.1and2, an upper end surface and a lower end surface of the reaction flow passage10are open, and an upper end surface and a lower end surface of the heat carrier flow passage20are closed. A bottom surface of the reactor100(lower piece100B) in which the reaction flow passage10and the heat carrier flow passage20are formed is closed by a closing plate30. The closing plate30is provided with an opening31, and air (gas) is supplied from an air pump (not illustrated) to the reactor100(the reaction flow passage10) via the opening31. A check valve is provided in the air supply passage from the air pump to the opening31, and the outflow of the fuel through the opening31is prevented.

A filter40made of a metal fine-pore mesh material or a porous material such as a sintered body or a foam and having homogeneous pores is interposed between the lower end surface of the reaction flow passage10(and the heat carrier flow passage20) and the closing plate30. The fuel circulating in the reaction flow passage10also fills a space between the lower piece100B and the closing plate30of the reactor100including the filter40.

FIG.5is a view for describing the reaction flow passage10. As illustrated inFIGS.1,2, and5, a height of the upper end surface of the reaction flow passage10is uniform all over in the radial direction. As illustrated inFIGS.1and5, in the lower piece100B of the reactor100, further, a reaction liquid supplying flow passage11for supplying the unreformed fuel to a supplying portion10a(FIG.4) provided at the lower end of the maximum outer diameter portion of the reaction flow passage10is formed. As illustrated inFIG.1, the reaction liquid supplying flow passage11includes a vertical flow passage11a, a horizontal flow passage11b, and an inclined flow passage11c.

The vertical flow passage11aextends in a vertical direction from the vicinity of an upper end to the vicinity of a lower end of the lower piece100B on a side further outward from the maximum outer diameter portions of the reaction flow passage10and the heat carrier flow passage20. The horizontal flow passage11bextends in a horizontal direction to allow an upper end of the vertical flow passage11ato communicate with the external space. The inclined flow passage11cextends to be inclined downward toward the radial inner side to allow a lower end of the vertical flow passage11ato communicate with the supplying portion10aof the reaction flow passage10. In other words, a lower end surface of the reaction liquid supplying flow passage11is formed to be inclined downward toward the radial inner side.

Consequently, unreformed fuel is supplied to the reaction flow passage10from a fuel tank (not illustrated) via the reaction liquid supplying flow passage11. The fuel supplied from above via the reaction liquid supplying flow passage11including the vertical flow passage11aand the inclined flow passage11cflows radially inward in the length direction of the reaction flow passage10and flows upward in the width direction together with air supplied from below. Since the lower end surface of the reaction liquid supplying flow passage11is formed to be inclined downward toward the radial inner side, the flow of the fuel toward the radial inner side is promoted, and the fuel can be uniformly circulated in the reaction flow passage10all over in the radial direction.

The air supplied via the opening31of the closing plate30passes through the filter40to become homogeneous fine bubbles and is supplied to the reaction flow passage10. Consequently, the fine-bubble-shaped air (bubbles) is supplied to the reaction flow passage10from below all over in the radial direction. The bubbles supplied to the reaction flow passage10flow to rise in the width direction of the reaction flow passage10. The air bubbles disappear overtime, but since the length of the reaction flow passage10in the width direction is relatively short, for example, the air bubbles can be reliably maintained in a range from the lower end surface to the upper end surface even in case where the air bubbles are relatively large and the period until the air bubbles disappear is short.

A fuel containing hydrocarbons as a main component is oxidatively reformed using a catalyst such as N-hydroxyphthalimide (NHPI) to produce a peroxide, so that ignitability thereof can be improved. Specifically, with NHPI, a hydrogen atom is easily extracted using an oxygen molecule to produce a phthalimide-N-oxyl (PINO) radical. With the PINO radical, a hydrogen atom is extracted from a hydrocarbon (RH) contained in the fuel to produce an alkyl radical (R−). The alkyl radical bonds to an oxygen molecule to produce an alkyl peroxy radical (ROO−). With the alkyl peroxy radical, a hydrogen atom is extracted from a hydrocarbon contained in the fuel to produce an alkyl hydroperoxide (ROOH), which is a peroxide.

The reaction flow passage10functions as a reactor (reaction field) in which the fuel and oxygen in the air react (oxidation reaction, fuel reforming reaction) to generate reformed fuel. In the reaction flow passage10, a catalyst such as a powdery or wall-supported NHPI catalyst or the like is provided. The fuel supplied to the reaction flow passage10is brought into contact with oxygen contained in air (bubbles) supplied from below and the catalyst all over in the radial direction. Consequently, an oxidation reforming reaction of the fuel is promoted all over the reaction flow passage10in the radial direction.

In a case where the reactor100is formed by additive manufacturing, unevenness can be easily formed on an inner wall surface of the reaction flow passage10, and a surface area of a wall surface on which the reactant and the catalyst are in contact with each other can be increased. The inner wall surface of the reaction flow passage10is plated with a material that does not affect the reforming reaction, such as nickel. The reactor100itself may be formed using a material that does not affect the reforming reaction, such as nickel.

Note that, instead of a fixed bed type in which the catalyst is provided in the reaction flow passage10through which the reactant flows, a fluidized bed type may be used in which a catalyst solution obtained by mixing a catalyst (powder) with an appropriate solvent is supplied to the reaction flow passage10together with the fuel and caused to flow. In this case, the particle size of the catalyst (powder) is reduced, and thus the reaction efficiency can be improved. The NHPI catalyst does not need to be separated from the reformed fuel and can be directly supplied to the engine.

As illustrated inFIG.3, a gap g1between inner wall surfaces of the reaction flow passage10, more specifically, between an inner end surface and an outer end surface of the reaction flow passage10in the radial direction, is formed to be equal to or smaller than twice a quenching distance. Consequently, since an inner wall surface of the reaction flow passage10is always present in a range within the quenching distance from a reactant, the safety of the reactor100can be enhanced. In a case where the safety is further increased, the reactor100may be formed such that the gap g1is equal to or smaller than the maximum safety gap. By configuring the reaction flow passage10, which is a reaction field in which the oxidation reaction of the fuel proceeds, with the maximum safety gap, for example, the flame is immediately extinguished even in a case where a flame enters from an adjacent device, and thus the safety of the reactor100can be further enhanced.

FIG.6is a view for describing the heat carrier flow passage20. As illustrated inFIGS.1,2, and6, the upper end surface of the heat carrier flow passage20is formed to be inclined upward toward a radial inner side. Further, in the lower piece100B of the reactor100, a heat carrier supplying flow passage21for supplying a heat carrier to the vicinity of the lower end of the maximum outer diameter portion of the heat carrier flow passage20is formed. The heat carrier supplying flow passage21extends to be inclined downward toward the radial inner side to allow the vicinity of the lower end of the maximum outer diameter portion of the heat carrier flow passage20to communicate with an external space. In other words, a lower end surface of the heat carrier supplying flow passage21is formed to be inclined downward toward the radial inner side.

Engine cooling water as a heat carrier is supplied from an engine (not illustrated) to the heat carrier flow passage20via the heat carrier supplying flow passage21. Since the lower end surface of the heat carrier supplying flow passage21is formed to be inclined downward toward the radial inner side, a flow of a heat carrier toward the radial inner side is promoted, and the heat carrier can be uniformly circulated in the heat carrier flow passage20all over in the radial direction. Furthermore, as illustrated inFIGS.1to3, the heat carrier flow passage20is adjacent to the reaction flow passage10via a relatively thin partition wall made of a metal material having high thermal conductivity. When the heat carrier flows through such a heat carrier flow passage20, even with the heat carrier having a relatively low temperature such as engine cooling water, the temperature of the reaction flow passage10functioning as the reaction field of the fuel reforming reaction can be efficiently increased to a catalyst activation temperature range, and the fuel reforming reaction can be suitably promoted.

In a case where the reactor100is formed by additive manufacturing, unevenness can be easily formed on an inner wall surface of the heat carrier flow passage20(and the reaction flow passage10), the surface area of the wall surface on which heat exchange is performed can be increased, and heat exchange performance can be improved. The temperature of the reaction flow passage10functioning as the reaction field of the fuel reforming reaction is sufficiently increased, and thus the fuel reforming rate can be improved. Alternatively, the number of available catalysts that can be employed can be increased.

As illustrated inFIGS.1to3and6, in the lower piece100B of the reactor100, further, a heat carrier discharging flow passage22for discharging the heat carrier from the inside diameter portion of the heat carrier flow passage20is formed. The heat carrier discharging flow passage22protrudes upward from a lower end surface of the heat carrier flow passage20and is formed in a columnar shape centered on the vertical axis C. The heat carrier flow passage20and the heat carrier discharging flow passage22provided in the heat carrier flow passage20are separated by a cylindrical partition wall23.

FIG.7is a view for describing the heat carrier discharging flow passage22, and a front view of the partition wall23. As illustrated inFIGS.1,3,6, and7, the partition wall23is provided with a plurality of (four in the illustrated example) communication holes24having different heights from each other from the lower end surface of the heat carrier flow passage20, and the heat carrier is discharged from the heat carrier flow passage20via the communication holes24and the heat carrier discharging flow passage22. The engine cooling water as the heat carrier discharged via the heat carrier discharging flow passage22is returned to the engine. The partition wall23is formed such that the plurality of communication holes24increase in size toward the lower side and decrease in size toward the upper side. Consequently, since the flow of the heat carrier in the heat carrier flow passage20becomes greater as it is directed toward the lower side, the heat exchange at the lower side of the reactor100is promoted, and the heat exchange can be performed in a balanced manner in the reactor100all over in the up-down direction. Note that a plurality of the communication holes24are provided at a plurality of locations (two locations in the illustrated example) in the circumferential direction.

As illustrated inFIGS.1and2, in the lower piece100B of the reactor100, further, a downward flow passage50in which the fuel after reforming (reformed fuel) flows is formed above the heat carrier flow passage20. In other words, the downward flow passage50is also formed in a helical or spiral shape centered on the vertical axis C, and is alternately arranged with the reaction flow passage10in the radial direction.

FIG.8is a cross-sectional view of the reactor100taken along line VIII-VIII inFIG.1, andFIG.9is a cross-sectional view of the reactor100taken along line IX-IX inFIG.1. As illustrated inFIGS.1,2,8, and9, an upper end surface of the downward flow passage50is open to communicate with an upper end surface of the reaction flow passage10. A height of the upper end surface of the reaction flow passage10and a height of the upper end surface of the downward flow passage50are the same as a height of a partition wall51separating the reaction flow passage10and the downward flow passage50(and the heat carrier flow passage20), and are the same as each other all over in the radial direction. The heat carrier flow passage20and the downward flow passage50are separated by a partition wall52, and a height of the upper end surface of the heat carrier flow passage20, a height of a lower end surface of the downward flow passage50, and a height of the partition wall52are substantially the same as each other all over in the radial direction. The lower end surface of the downward flow passage50is positioned above the lower end surfaces of the reaction flow passage10and the heat carrier flow passage20all over in the radial direction, and is formed to be inclined downward toward a radial outer side.

The upper piece100A of the reactor100has a first projecting portion60and a second projecting portion70formed to project downward from an inner wall surface on an upper side of the upper piece. The first projecting portion60is formed corresponding to the reaction flow passage10and projects from the inner wall surface above the reaction flow passage10toward the reaction flow passage10all over in the radial direction. The second projecting portion70is formed corresponding to the downward flow passage50(and the heat carrier flow passage20) and projects from the inner wall surface above the downward flow passage50toward the downward flow passage50all over in the radial direction.

As illustrated inFIGS.8and9, a gap g2between the first projecting portion60and the second projecting portion70, more specifically, between an outer end surface of the first projecting portion60and an inner end surface of the second projecting portion70in the radial direction, is also formed to be equal to or smaller than twice the quenching distance or equal to or smaller than the maximum safety gap. Similarly, a gap g3between an outer end surface of the second projecting portion70and an inner end surface of the first projecting portion60is also formed to be equal to or smaller than twice the quenching distance or equal to or smaller than the maximum safety gap. Furthermore, a gap g4between the upper end surface of the reaction flow passage10and a lower end surface of the first projecting portion60and a gap g5between the lower end surface of the downward flow passage50and a lower end surface of the second projecting portion70are also formed to be equal to or smaller than twice the quenching distance or equal to or smaller than the maximum safety gap.

A liquid level (gas-liquid separation surface) L of the reformed fuel is adjusted to be located between the upper end surface of the reaction flow passage10and the downward flow passage50and the lower end surface of the first projecting portion60. A space (gas-liquid separation space) SP from the gas-liquid separation surface L to the inner wall surface on the upper side of the upper piece100A has a helical or spiral labyrinth shape due to the first projecting portion60and the second projecting portion70. Consequently, sufficient gas-liquid separation can be performed in the gas-liquid separation space SP. Therefore, it is not necessary to separately provide a gas-liquid separating device such as a separator or a condenser, and the entire configuration of the reactor100can be simplified. By dividing the reactor100into the upper piece100A and the lower piece100B, it is possible to form an internal shape in which upper end portions of the partition walls51and52and the lower end portions of the first projecting portion60and the second projecting portion70are intricately positioned.

As illustrated inFIGS.1and2, in the upper piece100A of the reactor100, further a gas discharging flow passage53for discharging the gas from the reaction flow passage10is formed. The gas discharging flow passage53communicates with the reaction flow passage10via the gas-liquid separation space SP. The air supplied to the reaction flow passage10via the opening31of the closing plate30rises in the reaction flow passage10to be subjected to the reforming reaction, is then released from the gas-liquid separation surface L into the gas-liquid separation space SP, and is discharged to the external space via the gas discharging flow passage53after the liquid is separated in the gas-liquid separation space SP. The air discharged via the gas discharging flow passage53is supplied to an intake port of the engine and sucked into a combustion chamber of the engine together with fresh air.

FIG.10is a view for describing the downward flow passage50. As illustrated inFIGS.1,2, and8to10, the lower end surface of the downward flow passage50is formed to be inclined downward toward the radial outer side. As illustrated inFIGS.1to3and8to10, in the lower piece100B of the reactor100, further, a return flow passage80for allowing the reformed fuel to be returned to a returning flow portion10b(FIG.4) provided at the lower end of the maximum outer diameter portion of the reaction flow passage10is formed. As illustrated inFIGS.8and9, a gap g6between inner wall surfaces of the return flow passage80, more specifically, between an inner end surface and an outer end surface of the return flow passage80in the radial direction, is also formed to be equal to or smaller than twice the quenching distance or equal to or smaller than the maximum safety gap.

As illustrated inFIGS.2,3, and8to10, the return flow passage80includes a vertical flow passage80a, a horizontal flow passage80b, and an inclined flow passage80c. The vertical flow passage80aextends in a vertical direction from the vicinity of an upper end to the vicinity of a lower end of the lower piece100B on a side further outward from the maximum outer diameter portions of the reaction flow passage10and the heat carrier flow passage20, that is, the maximum outer diameter portion of the partition walls51. The horizontal flow passage80bextends in the horizontal direction on the upper end surface of the maximum outer diameter portion of the partition wall51to allow a returning flow portion50aprovided at the maximum outer diameter portion of the downward flow passage50to communicate with an upper end surface of the vertical flow passage80a. The inclined flow passage80cextends to be inclined downward toward the radial inner side to allow a lower end of the vertical flow passage80ato communicate with the returning flow portion10bprovided at the lower end of the maximum outer diameter portion of the reaction flow passage10. In other words, a lower end surface of the return flow passage80is formed to be inclined downward toward the radial inner side.

As illustrated inFIGS.1and9, in the lower piece100B of the reactor100, further, a reaction liquid discharging flow passage90for discharging a part of the reformed fuel from the returning flow portion50aof the downward flow passage50is formed. The reaction liquid discharging flow passage90extends in the horizontal direction near an upper end of the return flow passage80, more specifically, at a position slightly lower than the horizontal flow passage80b, to allow the vertical flow passage80ato communicate with the external space.

As illustrated inFIGS.5and8to10, the reformed fuel which is reformed while flowing upward in the width direction of the reaction flow passage10overflows from the upper end surface of the reaction flow passage10, flows into the downward flow passage50beyond the partition walls51, and flows radially outward in the length direction of the downward flow passage50. Since the lower end surface of the downward flow passage50is formed to be inclined downward toward the radial outer side, the flow of the reformed fuel toward the radial outer side is promoted, and the reformed fuel can be smoothly circulated.

A part of the reformed fuel that has reached the maximum outer diameter portion (the returning flow portion50a) of the downward flow passage50is discharged via the reaction liquid discharging flow passage90, and the rest thereof is returned to the lower end (the returning flow portion10b) of the maximum outer diameter portion of the reaction flow passage10via the return flow passage80. Even in a case where the fuel contains a catalyst, catalyst particles are not discharged from the reaction liquid discharging flow passage90in the horizontal direction, but are returned to the reaction flow passage10together with the reformed fuel via the return flow passage80(the vertical flow passage80a). Since the lower end surface of the return flow passage80is formed to be inclined downward toward the radial inner side, the flow of the reformed fuel toward the radial inner side is promoted, and the reformed fuel can be uniformly circulated in the reaction flow passage10all over in the radial direction.

When the reactor100is configured as described above, it is possible to efficiently increase the volume of the reaction flow passage10which is the reaction field while ensuring the safety of the reactor100, and it is possible to decrease the entire reactor100in size. Hence, it is possible to improve mountability on a vehicle. Furthermore, the band-shaped reaction flow passage10which is the reaction field is sandwiched by the similar band-shaped heat carrier flow passages20, and the temperature is efficiently increased over the entire region. Therefore, the contact reforming reaction can proceed efficiently even in a case where relatively low-temperature engine cooling water is used as the heat carrier.

Furthermore, by returning the reformed fuel into the reactor100and recirculating the reformed fuel in the reaction flow passage10, a reaction rate (reforming rate) can be improved even in certain reaction conditions (the atmospheric pressure and the engine water temperature). In other words, as the reformed fuel is repeatedly circulated in the reaction flow passage10, a substantial reaction time is lengthened, and the reaction rate is improved. In particular, by uniformly forming a height of the reaction flow passage10, the reformed fuel can uniformly overflow all over in the radial direction and in the length direction of the reaction flow passage10and the downward flow passage50, and the reformed fuel can efficiently return. Further, when the reaction liquid supplying flow passage11and the return flow passage80extend in the vertical direction and are formed so that the lower end surface is inclined downward toward the radial inner side, the flow toward the radial inner side can be promoted, and the reformed fuel can efficiently return.

According to this embodiment, the following operations and effects can be achieved.

(1) The reactor100includes the reaction flow passage10that is formed in the band shape to extend in the length direction and the width direction and is formed in a helical or spiral shape centered on a vertical axis C parallel to the width direction and has an open upper end surface, the downward flow passage50that is formed in a helical or spiral shape centered on the vertical axis C to be radially arranged alternately with the reaction flow passage10on a vertical cross section including the vertical axis C and has an open upper end surface to communicate with the upper end surface of the reaction flow passage10, the reaction liquid supplying flow passage11through which unreformed fuel is supplied to the supplying portion10aprovided at the lower end of a maximum outer diameter portion of the reaction flow passage10centered on the vertical axis C, the reaction liquid discharging flow passage90through which the reformed fuel is discharged from the returning flow portion50aprovided at the maximum outer diameter portion of the downward flow passage50centered on the vertical axis C, and the return flow passage80that allows the returning flow portion10bprovided at the lower end of the maximum outer diameter portion of the reaction flow passage10to communicate with the returning flow portion50aprovided at the maximum outer diameter portion of the downward flow passage50(FIGS.1to5and8to10).

The height of the upper end surface of the reaction flow passage10and the height of the upper end surface of the downward flow passage50are substantially the same as each other all over in the radial direction centered on the vertical axis C (FIGS.1,2,8, and9). The lower end surface of the downward flow passage50is positioned above the lower end surface of the reaction flow passage10all over in the radial direction and is formed to be inclined downward toward the radial outer side centered on the vertical axis C (FIGS.1,2,8, and9).

As described above, by making the reactor100in the helical or spiral shape, the volume of the reaction field can be efficiently increased. Furthermore, the reaction rate (the reforming rate) can be improved by recirculating the reaction liquid (fuel) in the reactor100. In other words, the reaction liquid supplied from the lower end of the maximum outer diameter portion of the reaction flow passage10via the reaction liquid supplying flow passage11circulates radially inward in the length direction, circulates from below to above in the width direction, and overflows from the upper end surface of the reaction flow passage10to flow into the downward flow passage50. The reaction liquid flowing into the downward flow passage50circulates radially outward in the length direction, and when the reaction liquid reaches the maximum outer diameter portion, a part thereof is discharged via the reaction liquid discharging flow passage90, and the rest thereof is returned to the reaction flow passage10via the return flow passage80to be recirculated.

(2) The height of the upper end surface of the reaction flow passage10is uniform all over in the radial direction (FIGS.1,2,5,8, and9). Consequently, it is possible to cause the reaction liquid to uniformly overflow all over in the radial direction of the reaction flow passage10and to be efficiently circulated.

(3) The lower end surface of the reaction liquid supplying flow passage11and the lower end surface of the return flow passage80are formed to be inclined downward toward the radial inner side centered on the vertical axis C (FIGS.1,2,5, and9). Consequently, the flow of the reaction liquid toward the center is promoted, and the reaction liquid can be uniformly circulated in the reaction flow passage10all over in the radial direction.

(4) The reactor100further includes, below the downward flow passage50, a heat carrier flow passage20formed in a helical or spiral shape centered on the vertical axis C to be alternately arranged in the radial direction with the reaction flow passage10in the vertical cross section, the heat carrier supplying flow passage21through which the heat carrier is supplied to the maximum outer diameter portion of the heat carrier flow passage20centered on the vertical axis C, and the heat carrier discharging flow passage22through which the heat carrier is discharged from the central portion of the heat carrier flow passage20centered on the vertical axis C (FIGS.1to3,6,8, and9). Consequently, the reaction flow passage10through which the reaction liquid flows is sandwiched by the heat carrier flow passage20through which the heat carrier flows, and the temperature is efficiently raised over the entire region, so that the reaction can efficiently proceed even in a case where a relatively low temperature heat carrier such as the engine cooling water is used.

(5) The reactor100further includes the closing plate30having the opening31for supplying gas from the lower end of the reaction flow passage10all over in the radial direction (FIGS.1,2, and5). Consequently, it is possible to efficiently supply the necessary gas (air) to the entire region of the reaction flow passage10which is the reaction field of the gas-liquid reaction (reforming reaction) and to improve the reaction rate. Furthermore, the upward flow of the reaction liquid is promoted by the upward flow of the gas, and the reaction liquid can be efficiently circulated.

(6) The reactor100further includes the first projecting portion60that projects downward from above the reaction flow passage10toward the reaction flow passage10all over in the radial direction, and the second projecting portion70that projects downward from above the downward flow passage50toward the downward flow passage50all over in the radial direction (FIGS.1,2,8, and9).

(7) The gap g1between the inner end surface and the outer end surface of the reaction flow passage10, the gap g2between the outer end surface of the first projecting portion60and the inner end surface of the second projecting portion70, and the gap g3between the outer end surface of the second projecting portion70and the inner end surface of the first projecting portion60in the radial direction centered on the vertical axis C are equal to or smaller than twice the quenching distance or equal to or smaller than the maximum safety gap (FIGS.8and9). The gap g4between the upper end surface of the reaction flow passage10and the lower end surface of the first projecting portion60and the gap g5between the lower end surface of the downward flow passage50and the lower end surface of the second projecting portion70are also formed to be equal to or smaller than twice the quenching distance or equal to or smaller than the maximum safety gap (FIGS.8and9). Consequently, the volume of the reaction field can be efficiently increased while the safety of the reactor100is ensured.

(8) The reactor100further includes the closing plate30having the opening31through which the gas from the lower end of the reaction flow passage10is supplied all over in the radial direction, and the gas discharging flow passage53through which the gas from the reaction flow passage10is discharged (FIGS.1and2). The gas discharging flow passage53communicates with the reaction flow passage10via the gas-liquid separation space SP demarcated by the first projecting portion60, the second projecting portion70, and the upper end surfaces of the reaction flow passage10and the downward flow passage50(FIGS.1,2,8, and9). Consequently, the sufficient gas-liquid separation can be performed in the gas-liquid separation space SP above the reaction flow passage10and the downward flow passage50, so that it is not necessary to separately provide a gas-liquid separating device such as a separator or a condenser, and the entire configuration of the reactor100can be simplified.

(9) The reactor100includes the lower piece100B in which the reaction flow passage10, the downward flow passage50, the reaction liquid supplying flow passage11, the reaction liquid discharging flow passage90, and the return flow passage80are formed, and the upper piece100A in which the first projecting portion60and the second projecting portion70are formed (FIGS.1,2,8, and9). The lower piece100B and the upper piece100A are configured to be detachably attached to each other (FIG.1). Consequently, maintainability of the inside of the reactor100is improved.

(10) The reaction liquid is a fuel containing hydrocarbons as a main component, the gas is air, and the reaction flow passage10is configured such that the oxidation reaction of the fuel supplied via the reaction liquid supplying flow passage11is performed in the presence of the catalyst. For example, the reactor100is configured as a reforming reactor that is mounted on a vehicle and reforms in-vehicle fuel. By efficiently increasing the volume of the reaction field in the reactor100described above, mountability thereof on a vehicle can be improved.

The above embodiments can be modified into various modification examples. Hereinafter, some modification examples will be described. In the above embodiments, the example has been described in which the catalyst is provided in the reaction flow passage10, but as illustrated inFIG.11, a catalyst obtained by supporting a catalyst on a carrier12which can be inserted into and removed from the reaction flow passage10may be used. As the carrier12, a material having a large non-surface area such as a porous body can be used. In the case where the catalyst is provided in the reaction flow passage10, the catalyst may be added or replaced depending on the state of aging or the like. Since the reactor100is configured to be dividable into the upper piece100A and the lower piece100B, and the catalyst is used by being supported on the carrier12that can be inserted into and removed from the reaction flow passage10, maintainability of the reactor100can be further improved.

In the above embodiments, the example has been described in which the fuel applied to an in-vehicle compression ignition engine and supplied from the fuel tank to the engine reacts with oxygen in the air at an elevated temperature to be reformed, but the reactor is not limited thereto as long as a liquid is circulated and reacts. The presence or absence of the catalyst applied to a first flow passage, a type of catalyst, a plating treatment on an inner wall surface of the first flow passage, and the like can be appropriately selected depending on a type of chemical reaction to which the reactor is applied. When the reactor is applied to a reaction proceeding at room temperature, a third flow passage, the heat carrier supplying flow passage through which the heat carrier is supplied to the third flow passage, and the heat carrier discharging flow passage through which the heat carrier is discharged from the third flow passage can be omitted. In a case where the reactor is applied to a reaction not involving gas, the gas supplying flow passage can be omitted. In this case, the lower end surface of the first flow passage may be closed.

The above embodiment can be combined as desired with one or more of the aforesaid modifications. The modifications can also be combined with one another.

According to the present invention, it becomes possible to efficiently increase the volume of the reaction field.