JP2005272168A - Fuel reformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel reformer which realizes high-reforming-efficiency steam reforming by utilizing the thermal energy of a burner combustion gas to heat the secondary air. <P>SOLUTION: An air pipe 81 for feeding the secondary air from an external air feed source is connected to the upper part of a housing 10, and an exhaust hole 14 for discharging a combustion exhaust from the inside of a burner 60 is open in a manner that it penetrates a furnace tube 20, etc. The burner 60 is provided with a plurality of secondary air feed holes 64 open to the inside of the housing 10, and the secondary air fed from the air pipe 81 is fed through them into the lower part of the burner 60. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel reformer for steam reforming a hydrocarbon fuel.

In recent years, development of stationary fuel cells and fuel cells for automobiles has been promoted because carbon dioxide emissions causing global warming can be reduced and energy conversion efficiency is high. A fuel cell generates electricity by electrochemically reacting high-purity hydrogen (H ₂ ) and oxygen (O ₂ ) in the air, and is a solid oxide fuel cell (SOFC). Various types have been researched and developed, such as polymer electrolyte fuel cells (PEFCs) and polymer electrolyte fuel cells (PEFCs).

  Hydrogen used in fuel cells is manufactured by applying various treatments to hydrocarbon-based fuels (raw fuels) such as city gas, LP gas, and kerosene because there is currently no hydrogen supply infrastructure in place. . When hydrogen is produced from hydrocarbon fuels, the sulfur content in the hydrocarbon fuel is first removed by a desulfurization process (adsorption desulfurization or hydrodesulfurization), and then a reforming process (steam reforming, partial oxidation reforming, etc.) Then, the reformed gas (hydrogen-rich gas) is taken out, and CO (carbon monoxide) in the reformed gas is converted to hydrogen by the CO shift process (high temperature shift catalyst or low temperature shift catalyst), and the CO selective oxidation catalyst and oxygen are used. A small amount of CO in the reformed gas is removed by the selective oxidation process.

  As a reforming process of a hydrocarbon fuel, steam reforming in which a hydrocarbon fuel and steam are reacted in the presence of a high temperature and a catalyst is generally employed. As a fuel reformer used for steam reforming, for example, a device using a double-pipe reforming element in which a reforming catalyst is filled between an inner tube and an outer tube (see Patent Document 1) is known. It has been. In this fuel reformer, a large number of reforming elements are arranged in the cylindrical fuel reformer housing with the open ends (supply ports and discharge ports) facing upward, and the lower part of the fuel reformer housing Is provided with a heating burner desired for the reforming element. Then, a steam-mixed fuel obtained by mixing hydrocarbon-based fuel and steam is supplied from the outer tube side of the reforming element, and the closed end (lower end) of the reforming element is set at a predetermined temperature (for example, 750 ° C. to By heating to about 800 ° C., the hydrocarbon-based fuel in the steam-mixed fuel and steam are brought into contact reaction under the reforming catalyst, and the reformed gas is obtained from the inner tube side of the reforming element. The steam-mixed fuel is preheated with an external water preheater that uses the combustion gas of the burner as a heat source, and is then mixed with hydrocarbon fuel and water preheated by an external heater that uses the combustion gas of the burner as a heat source. It is obtained by heating and vaporizing.

As another fuel reforming apparatus, an apparatus using a reforming element having a double annular cross section in which an inner cylinder and an outer cylinder are filled with a reforming catalyst is disclosed (see Patent Document 2). In this fuel reformer, a combustion cylinder of a heating burner is installed in the hollow portion of the reforming element, and the combustion gas is passed from the upper part of the combustion cylinder to the outer peripheral surface of the outer cylinder via the inner peripheral surface of the inner cylinder. And an evaporator and a heat recovery unit for heat exchange between the inner cylinder and the outer cylinder. Then, hydrocarbon fuel and water are supplied from the outer cylinder side of the reforming element, and the combustion gas of the burner is introduced into the combustion gas passage so that the hydrocarbon fuel and steam react with each other under the reforming catalyst. The reformed gas is obtained from the inner cylinder side of the reforming element. At this time, the water supplied from the outer cylinder side is heat-exchanged with the high-temperature reformed gas via the evaporator to be converted into water vapor and introduced into the reforming catalyst together with the hydrocarbon fuel.
Japanese Patent Laying-Open No. 2003-321204 (paragraphs 0004 and 0005, FIG. 2) Japanese Patent Laying-Open No. 2003-40605 (paragraphs 0033 to 0044, FIG. 2)

  Since the fuel reforming apparatus requires a large amount of heat when performing the reforming reaction of the fuel, a structure in which the reforming element is always heated by the burner is employed. However, in a conventional fuel reformer, a large amount of heat (heat loss) is released to the outside in the form of exhaust gas or radiant heat, so a large amount of heat (that is, to the burner) is performed in order to perform operation (reforming) without delay. The fuel generation efficiency is inevitably reduced.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a fuel reformer capable of extremely reducing heat loss.

  In order to solve the above-mentioned problem, the fuel reforming apparatus according to claim 1 is a fuel reforming apparatus used in a steam reforming process for extracting hydrogen from a hydrocarbon-based raw fuel, wherein the reforming section is provided on the first side. And a reformer body having a heating burner part on the second side opposite to the first side, and the reforming part is installed outside the reforming part and surrounded by the reformer part. A furnace tube through which combustion gas from the burner part circulates, and the reformer main body is installed outside the furnace tube so as to surround the furnace tube, and between the furnace tube and the reformer main body Further, an introduction path for combustion air supplied to the burner portion is formed.

  In the fuel reformer of claim 1, the secondary air supplied to the first side of the reformer main body by the secondary air supply means passes through the introduction path between the reformer main body and the furnace tube. After being heated by receiving heat from the furnace tube, it is introduced into the combustion tube through the secondary air introduction hole.

The fuel reformer according to claim 2 is the fuel reformer according to claim 1, wherein a heat insulating material is provided on the outer periphery or the inner periphery of the furnace tube.
In the fuel reforming apparatus according to the second aspect, the heat of the furnace tube is blocked by the heat insulating material and is not easily released to the outside, and the reforming section is more effectively heated.

The fuel reformer according to claim 3 is the fuel reformer according to claim 1 or 2, wherein the fuel reformer uses a liquid hydrocarbon fuel as a raw fuel, and the burner portion is the fuel reformer. Vaporization means used for vaporization of liquid hydrocarbon fuel is provided, and the vaporization means is installed in a flow path of combustion air introduced from the introduction path.
In the fuel reforming apparatus according to the third aspect, vaporization of the liquid hydrocarbon fuel supplied into the vaporization means is promoted by heating the vaporization means to the combustion air and raising the temperature.

  According to the fuel reforming apparatus of the present invention, heat loss is extremely reduced because the heat released from the fuel reforming apparatus is recovered by the combustion air, and the amount of input heat (burning amount in the burner) is reduced. This improves the overall power generation efficiency.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a longitudinal sectional view showing a fuel reforming apparatus according to an embodiment, FIG. 2 is an enlarged view of a portion A in FIG. 1, and FIG. 3 is an enlarged view of a portion B in FIG.

≪Configuration of fuel reformer≫
As shown in FIG. 1, the fuel reformer 1 includes a cylindrical housing (reformer main body) 10 that forms an outer shell of the device, a cylindrical furnace tube 20 disposed inside the housing 10, and a furnace tube. The reforming cylinder 30 having an annular cross-sectional shape disposed inside 20, the bottomed cylindrical evaporation cylinder 40 disposed inside the reforming cylinder 30, the reforming cylinder 30, and the upper part of the evaporation cylinder 40 (first side) ) Disposed in the lower portion (second side) of the furnace tube 20, a connection for connecting the reforming tube 30, the evaporation tube 40, and the mixing tube 50. The block 70 is a main structural member. These structural members are obtained by processing a stainless steel cylindrical member, a plate member, and a block member, and are assembled mainly by welding.

  The upper end of the housing 10 is fastened to the upper end plate 12 via the mixing cylinder support plate 11, and the lower end thereof is joined to the burner portion 60 via the connecting ring 13. An air pipe 81 for introducing secondary air from an external air supply source is connected to the upper portion of the housing 10, and an exhaust hole 14 for discharging combustion exhaust gas from the inside of the burner portion 60 is a furnace cylinder described later. It opens in the form of 20 or so. Further, a viewing hole 15 for observing the combustion state in the burner portion 60 is provided in the lower part of the housing 10 so as to penetrate the furnace tube 20 and the like described later, and a viewing window 16 using heat-resistant glass is viewed. It is attached in the form of closing the hole 15. An annular space between the housing 10 and the furnace tube 20 serves as an introduction path 17 for introducing secondary air that is combustion air.

  The upper end of the furnace tube 20 is joined to the housing 10 via the connection ring 21, and the lower end thereof is joined to the upper end of the burner portion 60 via the connection ring 22. A heat insulating material 23 made of glass wool, ceramic wool, rock wool or the like is adhered to the inner surface of the furnace tube 20 with an adhesive, a rivet, a screw or the like except for the exhaust hole 14 and the viewing hole 15. Is provided.

  The reforming cylinder 30 is manufactured by joining the outer cylinder 31 and the inner cylinder 32 via the bottom plate 33, and the upper ends of the outer cylinder 31 and the inner cylinder 32 are joined to the connecting block 70. The reforming cylinder 30 is filled with a reforming catalyst 34 in the lower 3/4 thereof and filled with a small-diameter ceramic ball 35 in the upper 1/4. The bottom of the reforming cylinder 30 is located directly above the burner unit 60.

  The evaporation cylinder 40 is joined to the connection block 70 with the upper part protruding into the mixing cylinder 50. The evaporation cylinder 40 is filled with ceramic balls 35. The bottom of the evaporation cylinder 40 is positioned substantially at the center of the reforming cylinder 30 in the vertical direction.

  The mixing cylinder 50 has an upper end joined to the mixing cylinder support plate 11 and a lower end joined to the connecting block 70. The mixing cylinder 50 is filled with ceramic balls 35 and its outer peripheral surface is in contact with the combustion gas that has heated the reforming cylinder 30 and the evaporation cylinder 40.

  As described above, the burner portion 60 is joined to the housing 10 via the connection ring 13, and is joined to the furnace tube 20 via the connection ring 22. As shown in FIG. 3, the burner unit 60 has a bottomed cylindrical vaporizing cylinder 60a which is a vaporizing means for vaporizing kerosene as a fuel, and a burner head 60b provided at the upper end of the vaporizing cylinder 60a. The vaporizing heater 60c is provided on the outer periphery of the bottom of the vaporizing cylinder 60a, and kerosene, which is fuel, is heated to a temperature capable of vaporizing in the vaporizing cylinder 60a by the heat of the vaporizing heater 60c. Further, a burner fuel supply pipe 60d for supplying kerosene as fuel and an air supply pipe 60e for supplying primary air are connected to the vaporizing cylinder 60a. The kerosene supplied from the burner fuel supply pipe 60d is heated and vaporized in the vaporizing cylinder 60a, and then mixed with the primary air supplied from the supplied air supply pipe 60e, and from the burner head 60b to the combustion space. Ejects and burns. Also, the burner portion 60 is provided with a plurality of secondary air introduction holes 64 that open into the housing 10, and the secondary air supplied from the air pipe 81 flows from the lower portion of the burner portion 60 to the burner head. Introduced around 60b. An ignition electrode 60f for igniting a mixed gas of kerosene and primary air is attached to the burner head 60b.

  As shown in FIG. 4 (perspective view) and FIG. 5 (longitudinal sectional view), the connecting block 70 has a short cylindrical shape with a flange 71 at the lower end, and is drilled in the axis at the upper end to be an evaporation cylinder. 40 has a holding hole 72 in which 40 is fitted, and a hollow part 73 which is a cylindrical space formed in the lower part of the holding hole 72. As shown in FIG. 6 (C-C cross-sectional view in FIG. 5), three combustion gas flows are formed in the connecting block 70 radially from the hollow portion 73 at an angular interval of 120 ° and open to the outer peripheral surface. A hole 74 and three communication holes 75 having a broad bean cross-sectional shape penetrating in the vertical direction provided at an angular interval of 120 ° so as to avoid the combustion gas circulation hole 74 are formed.

  As shown in FIG. 2, at the center of the upper end plate 12, there is a joint 85 connecting a fuel pipe 82 for supplying kerosene as raw fuel and a water pipe 83 for supplying water (pure water) as a water vapor source. It is attached via a pipe connector 86. The pipe connector 86 includes a relatively large-diameter fuel supply pipe 87 that opens to the top of the evaporation cylinder 40 and a relatively small-diameter water introduction pipe 88 that is coaxial with the fuel supply pipe 87 and opens to the lower end of the evaporation cylinder 40. The kerosene from the fuel pipe 82 is supplied to the upper part of the evaporation cylinder 40 via the fuel supply pipe 87, and the water from the water pipe 83 is supplied to the lower end portion of the evaporation cylinder 40 via the water introduction pipe 88. Supplied.

  The upper end plate 12 has two reformed gas pipes 89 (only one is shown in FIGS. 1 and 2) for conveying the reformed gas generated in the fuel reformer 1 to the shift reactor. It is attached via a pipe connector 90. The pipe connector 90 includes a reformed gas outlet pipe 91 that is piped into the mixing cylinder 50 and the reforming cylinder 30 and opens to the lower end portion of the reforming cylinder 30, and the reforming generated in the reforming cylinder 30. The gas flows into the reformed gas pipe 89 through the reformed gas outlet pipe 91. As shown in FIG. 6, the reformed gas outlet pipe 91 passes through the two communication holes 75 of the connection block 70.

  As shown in FIG. 3, a fuel pipe 92 for supplying kerosene as burner fuel is attached to the lower end plate 63 via a connector 93, and an air pipe 94 for supplying primary air is attached via a connector 95. It has been. The connector 93 is connected to the burner fuel supply pipe 60d of the burner section 60, and kerosene from the fuel pipe 92 is supplied to the vaporizing cylinder 60a via the burner fuel supply pipe 60d. The connector 95 is connected to the air supply pipe 60e of the burner unit 60, and primary air from the air pipe 94 is supplied to the vaporizing cylinder 60a via the air supply pipe 60e.

≪Operation of fuel reformer≫
Hereinafter, the operation (operation mode) of the fuel reformer 1 will be described. In the case of the present embodiment, the fuel reformer 1 is controlled by a control device (not shown) based on detection results of temperature sensors installed in the respective parts.

<Burner combustion>
When the operation of the fuel reformer 1 is started, first, kerosene from a combustion kerosene supply source (not shown) is supplied to the vaporizing cylinder 60a of the burner unit 60 through a fuel pipe 92 and a burner fuel supply pipe 60d. On the other hand, primary air from a primary air supply source (not shown) is supplied through an air pipe 94 and an air supply pipe 60e. The kerosene supplied to the vaporizing cylinder 60a is vaporized in the vaporizing cylinder 60a and mixed with the primary air, and then jetted from the burner head 60b to the combustion space below the furnace cylinder 20 as an excess fuel mixture. The air-fuel mixture is ignited by the ignition electrode 60f and starts partial combustion in the furnace tube 20.

  When primary combustion in the furnace tube 20 is started, secondary air from an air supply source is supplied into the housing 10 via the air pipe 81, and this secondary air is introduced into the introduction path 17 and the secondary air. It is introduced into the burner part 60 through the hole 64. The introduced secondary air is heated to a predetermined temperature (for example, 220 ° C.) by the vaporizing heater 60 c at the start of operation (during cooling) and then comes into contact with the excess fuel flame. As a result, a wide range of secondary combustion (complete combustion) is started in the furnace cylinder 20, and the combustion gas flows around the reforming cylinder 30, the evaporation cylinder 40, and the mixing cylinder 50 to rapidly increase their temperatures.

  The combustion gas flowing outside the reforming cylinder 30 flows to the upper part of the furnace cylinder 20 after heating the outer cylinder 31 of the reforming cylinder 30, and is discharged from the exhaust hole 14 as combustion exhaust gas. The combustion gas that has flowed into the reforming cylinder 30 heats the inner cylinder 32 and the evaporation cylinder 40 of the reforming cylinder 30, and then passes through the combustion gas circulation holes 74 formed in the connection block 70. It flows into the upper part and is discharged from the exhaust hole 14 as combustion exhaust gas. At this time, since the heat insulating material 23 is adhered to the inner surface of the furnace tube 20, the heat of the furnace tube 20 is blocked by the heat insulating material 23 and is not easily released to the outside, and the heating of the reforming tube 30 is more effective. To be done.

<Generation of water vapor>
When the secondary combustion in the furnace tube 20 is stabilized, water from the water pipe 83 is supplied to the lower end portion of the evaporation cylinder 40 via the water introduction pipe 88 as shown in FIG. In the case of the present embodiment, the temperature at the lower end of the evaporation cylinder 40 is about 150 ° C. in the state where the secondary combustion is proceeding in the furnace cylinder 20. Therefore, the supplied water is instantaneously evaporated together with the heat transfer effect of the ceramic balls 35 filled in the evaporation cylinder 40 to become high-temperature water vapor, and the inside of the evaporation cylinder 40 is directed toward the mixing cylinder 50. Rise.

<Generation of steam mixed fuel>
On the other hand, simultaneously with the supply of water from the water pipe 83 to the evaporation cylinder 40, kerosene from the fuel pipe 82 is supplied to the upper part of the evaporation cylinder 40 via the fuel supply pipe 87 as shown in FIG. 8. In the case of this embodiment, the temperature of the upper part of the evaporation cylinder 40 is about 200 ° C. in the state where the secondary combustion is proceeding in the furnace cylinder 20. Therefore, in addition to the heat transfer effect of the ceramic balls 35 filled in the evaporation cylinder 40, the supplied kerosene comes into contact with the high-temperature steam rising from the lower end of the evaporation cylinder 40, and the evaporation temperature thereof decreases. Together, it evaporates all at once. The evaporated kerosene is stirred by the ceramic balls 35 while rising toward the mixing cylinder 50, and becomes a steam mixed fuel that is uniformly mixed with water vapor in the mixing cylinder 50, and is modified through the communication hole of the connection block 70. It flows into the material cylinder 30.

<Production of hydrogen-rich gas>
The steam mixed fuel that has flowed into the reforming cylinder 30 is further stirred by the ceramic balls 35 filled in the upper portion, and then contacts the reforming catalyst 34 filled below the ceramic balls 35. In the case of the present embodiment, in the state where the secondary combustion is proceeding in the furnace tube 20, the temperature of the reforming cylinder 30 is 500 ° C. or higher, and is about 750 ° C. at the lower end facing the burner portion 60. . Therefore, the ambient temperature increases as it flows down in the reforming cylinder 30, the contact reaction of the steam-mixed fuel that has flowed through the reforming catalyst 34 for a relatively long distance proceeds rapidly, and the quality is high (the composition ratio of methane is small). ) Reformed gas (hydrogen rich gas) is generated.

  As shown in FIG. 9, the generated reformed gas flows into the reformed gas outlet pipe 91 opened at the lower end of the reforming cylinder 30 and passes through the reformed gas pipe 89 (see FIG. 1). Delivered to shift reactor. The reformed gas has a relatively high temperature (about 500 ° C.) when it flows into the reformed gas outlet pipe 91. However, in the present embodiment, the reformed gas outlet pipe 91 is provided in the mixing cylinder 50, so that the reformed gas passes through the tube wall of the reformed gas outlet pipe 91 and the ceramic balls 35. Heat exchange with kerosene and water vapor is performed, and the temperature drops to about 200-300 ° C. As a result, the load of the shift reactor into which the reformed gas flows is reduced, and at the same time, the evaporation of kerosene in the mixing cylinder 50 is promoted.

<Heating of secondary air>
In the case of this embodiment, as shown in FIGS. 2 and 3, the secondary air is supplied to the upper portion of the introduction path 17 between the housing 10 and the furnace tube 20 from the air pipe 81, and then the It flows downward along the outer periphery and flows into the lower part of the burner part 60 from the secondary air introduction hole 64 formed in the burner part 60.

  At this time, since the secondary air comes into contact with the high-temperature furnace cylinder 20 for a relatively long time in the introduction path 17, the temperature of the secondary air is relatively high when it flows into the burner unit 60 (for example, about 250 ° C.). )Become. For this reason, the entire burner section 60 is heated by the high-temperature secondary air, and further heating of the vaporizing cylinder 60a becomes unnecessary, so that the energization to the vaporizing heater 60c is stopped. Furthermore, since the heat radiated from the outer periphery of the reformer 1 is recovered in the secondary air, the thermal efficiency is improved as compared with a general device.

  Thus, in this embodiment, since the thermal energy which the combustion gas produced | generated by the burner part 60 has was utilized very efficiently, it was made to vaporize water vapor | steam or kerosene (raw fuel), and heat secondary air, It was possible to achieve steam reforming with high reforming efficiency while keeping fuel consumption at the burner section 60 low.

  The present invention is not limited to this embodiment, and can be widely modified. For example, in the above-described embodiment, the present invention is applied to a steam fuel reformer using kerosene as a raw fuel, but LP gas or the like, which is a gaseous hydrocarbon fuel, is used as a raw fuel in addition to gasoline or alcohol. Naturally, it can also be applied to a steam fuel reformer. Moreover, in the said embodiment, although kerosene was used as a fuel of a burner, you may make it use heavy oil, light oil, etc. Moreover, in the said embodiment, although secondary air was mentioned as combustion air heated with the thermal energy of combustion gas, you may make it heat primary air. In the above embodiment, the heat insulating material is provided on the inner surface of the furnace tube. However, the heat insulating material is provided on the outer surface of the furnace tube so that the heat insulating material is adhered to the furnace tube with an adhesive, rivets, screws, or band winding. Alternatively, a heat insulating material may be provided in close contact with both the inner surface and the outer surface of the furnace tube. Moreover, in the said embodiment, the 2nd side in which a burner part is provided was made into the lower side, and the 1st side was made into the upper side, but the reformer is installed upside down in FIG. 1, and the burner part is provided. The second side is the upper side, the first side is the lower side, the reformer is installed horizontally or obliquely in FIG. 1, the second side where the burner part is provided is the right side, and the first side is the left side May be. In addition, the specific structure of the fuel reformer, the operating temperature of each part, and the like can be changed as appropriate without departing from the spirit of the present invention.

It is a longitudinal section showing a fuel reformer concerning an embodiment. It is the A section enlarged view in FIG. It is the B section enlarged view in FIG. It is a perspective view of a connection block. It is a longitudinal cross-sectional view of a connection block. It is CC sectional drawing in FIG. It is a principal part enlarged view of an evaporation pipe | tube. It is a principal part enlarged view of an evaporation pipe | tube. It is a principal part enlarged view of a reforming cylinder.

Explanation of symbols

1 Fuel reformer 10 Housing (reformer body)
17 Introducing path 20 Furnace cylinder 23 Insulating material 30 Reforming cylinder (reforming part)
40 Evaporating cylinder 50 Mixing cylinder 60 Burner 60a Evaporating cylinder (vaporizing means)
64 Secondary air introduction hole 81 Air piping

Claims (3)

A fuel reformer used in a steam reforming process for extracting hydrogen from a hydrocarbon-based raw fuel,
A reformer main body having a reforming section on the first side and a burner section for heating on the second side opposite to the first side;
It is installed on the outside of the reforming section so as to surround the reforming section, and includes a furnace tube in which combustion gas from the burner section circulates,
The reformer main body is installed outside the furnace tube so as to surround the furnace tube,
A fuel reformer, wherein an introduction path for combustion air supplied to the burner portion is formed between the furnace tube and the reformer main body.   The fuel reformer according to claim 1, wherein a heat insulating material is provided on an outer periphery or an inner periphery of the furnace tube. The fuel reformer uses a liquid hydrocarbon fuel as a raw fuel,
The burner unit comprises vaporization means for vaporization of the liquid hydrocarbon fuel,
The fuel reformer according to claim 1 or 2, wherein the vaporizing means is installed in a flow path of combustion air introduced from the introduction path.

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