JP2010266161A - Combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein the second combustion gas is leaked out into a secondary air route, when a clearance exists in a route for supplying the second combustion gas, to be exhausted together with secondary air under the state one part of the second combustion gas leaked out into a secondary air passage is not burnt yet. <P>SOLUTION: This combustion device is constituted to make internal pressure of a route for supplying the secondary air higher than internal pressure of a route for supplying the second combustion gas. The second combustion gas is prevented from leaked into a secondary air supply route of higher pressure, even when the clearance or a hole exists in the route supplied with the second combustion gas, because the internal pressure of the route for supplying the secondary air is higher than the internal pressure of the route for supplying the second combustion gas. The second combustion gas is thereby prevented from being exhausted under the state the second combustion gas is not burnt yet, and a required manufacturing cost therefor is also restrained. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a combustion apparatus for burning two types of fuel, a first combustion gas and a second combustion gas, and particularly a reforming device for generating a reformed gas mainly composed of hydrogen to be supplied to a fuel cell. It is used for heating the device.

  A hydrogen supply device for supplying hydrogen to a fuel cell includes a reformer that generates a reformed gas mainly composed of hydrogen from a hydrogen raw material by a reforming reaction, and a combustion device that heats the reformer. When kerosene is used as a raw material, the reformer needs an operating temperature of about 800 ° C. Therefore, a combustion device for heating the reformer for the purpose of maintaining the operating temperature at the start-up of the fuel cell and during the power generation operation is indispensable.

  This combustion device raises the temperature of the reformer by burning a mixed gas for combustion (first combustion gas) in which vaporized gas obtained by vaporizing kerosene and primary air is mixed when the fuel cell is started, and fuel is generated during power generation operation. The reformer is maintained at a predetermined temperature by burning the exhaust gas (second combustion gas) discharged from the hydrogen electrode of the battery as fuel.

  In other words, this combustion device is required to be able to burn two types of fuel, the first combustion gas and the second combustion gas, and at the same time, shortening the ignition time that directly affects the fuel cell startup time. In addition, the environmental load is reduced by reducing the amount of NOx / CO2 emission, and further, a high level of safety and durability is required in a compact and inexpensive manner.

  Therefore, conventionally, the present applicant has developed a combustion apparatus as shown in Patent Document 1. This combustion apparatus includes a mixing chamber that mixes a combustion gas obtained by vaporizing liquid fuel and primary air to form a mixed gas for combustion, an exhaust gas chamber that is attached to the outer periphery of the mixing chamber and that stores exhaust gas from a fuel cell, and The exhaust gas chamber is provided with an exhaust gas supply pipe for supplying exhaust gas from the fuel cell, and the first combustion gas and the second combustion gas are ejected from the ejection holes provided in the flame plate and burned on the same surface. It is made to let you. This configuration not only makes it possible to reduce the size of the apparatus, but the exhaust gas chamber is kept airtight if the top opening and bottom hole are welded and sealed to the flame plate and the mixing chamber, respectively. Therefore, it is possible to prevent the exhaust gas from leaking out with a simple configuration compared to the conventional one, and the combustion apparatus is excellent in terms of safety.

JP 2007-120856 A

  However, even if it is the above-mentioned composition, since it is the structure where a plurality of parts were assembled by means, such as welding and fitting, in the first place, a gap and a hole may not occur in an assembly process. Furthermore, since the exhaust gas chamber is exposed to high temperatures during combustion, even if it is completely sealed at the time of manufacture, there is a possibility that the parts will be distorted by heat due to use and a gap will be created in the fitting part. There is also. Then, the second combustion gas leaks out from the slight gap into the secondary air passage.

  Although the secondary air is supplied to the flame downstream of the flame plate, not all the secondary air contributes to combustion because of the structure supplied from the outside of the flame. Therefore, a part of the second combustion gas leaking into the secondary air passage is exhausted together with the secondary air without being burned.

  In order to solve such a problem, it is necessary to have a structure that can withstand high temperatures so that the second combustion gas does not leak, but the manufacturing cost is extremely high.

  The present invention is for solving the above-described problems, and an object of the present invention is to provide a combustion apparatus that prevents the unburned second combustion gas from being discharged without increasing the manufacturing cost. .

  The present invention is a combustion apparatus that burns a second combustion gas after burning the first combustion gas, a path for supplying the first combustion gas, a path for supplying the second combustion gas, The combustion apparatus includes a path for supplying secondary air to the flame, and the internal pressure of the path for supplying secondary air is higher than the internal pressure of the path for supplying the second combustion gas.

  In addition, a first combustion gas ejection hole is provided at the center, a second combustion gas ejection hole is provided so as to surround the first combustion gas ejection hole, and a second combustion gas ejection hole is further provided. The combustion apparatus according to claim 1, further comprising a flame plate provided with a secondary air ejection hole so as to surround it.

  By configuring as described above, the second combustion gas can be prevented from leaking to the path for supplying the secondary air even if there are gaps or holes in the path for supplying the second combustion gas. Thus, it is possible to solve the problem that the unburned second combustion gas is mixed into the exhaust gas. And the manufacturing cost for that can also be held down.

It is a front sectional view of the combustion apparatus of the present invention. It is a figure showing the flame plate of this invention.

  The preferred embodiment of the present invention will be briefly described by showing the operation of the present invention.

  The present invention is, for example, a combustion apparatus for heating a reformer for generating a reformed gas mainly composed of hydrogen to be supplied to a fuel cell, wherein the first combustion gas is supplied and burned. After that, the second combustion gas is supplied and burned.

  Specifically, when the fuel cell is started, a premixed gas (first combustion gas) obtained by mixing vaporized gas obtained by heating and vaporizing liquid fuel such as kerosene and primary air is used as the first combustion gas supply path. An ejection flame is formed through the first combustion gas ejection hole. When the reformer is heated by the combustion of the first combustion gas and the reformed gas mainly composed of hydrogen is generated by the reformer, the operation of the fuel cell is started.

  When the fuel cell starts operation, hydrogen-containing gas containing hydrogen discharged from the fuel cell (second combustion gas) passes through the second combustion gas supply path and is ejected from the second combustion gas ejection hole. To do. And it contacts and ignites by contacting with the flame of the 1st combustion gas, and combustion by both the 1st combustion gas and the 2nd combustion gas is started. Thereafter, when the operation of the fuel cell is stabilized, the combustion is mainly performed with the second combustion gas.

  Further, the air that has passed through the secondary air supply path is supplied to the flame from the secondary air ejection hole, and the flame is completely burned by taking in the secondary air.

  At this time, even if there is a gap or a hole in the path for supplying the second combustion gas, the internal pressure of the path for supplying the secondary air is higher than the internal pressure of the supply path for the second combustion gas. The second combustion gas does not leak into the secondary air supply path having a high pressure. Therefore, all the supplied second combustion gas is burned and can be used safely.

  The combustion apparatus of the present invention will be described in detail below based on the drawings.

  FIG. 1 is a front sectional view of a combustion apparatus, and includes a carburetor 1 for producing a premixed gas (first combustion gas) of combustion gas and primary air vaporized from liquid fuel, a premixed gas, and a fuel cell. Are provided with a burner section 2 for burning the hydrogen-containing gas (second combustion gas) generated in step 1 and a blower passage 3 for supplying air.

  The vaporizer 1 includes a liquid fuel supply pipe 4 that supplies liquid fuel to the vaporizer 1, a heater 5 that raises the temperature of the vaporizer 1, and an evaporation unit 6 that heats and vaporizes the liquid fuel to form a combustion gas. A vaporizing chamber 9 having a partition plate 7 provided with dropping holes 8 for dispersing and dropping liquid fuel to the evaporation section 6 and an evaporation section 6 on the inner bottom surface to mix combustion gas and primary air to form a premixed gas. And a supply chamber 10 that distributes the primary air that contains air from the blower passage 3 and mixes with the combustion gas, and the secondary air that is supplied to the flame formed by the burner section 2, and the premixed gas is ejected. This is a structure having a premixed gas ejection part 11.

  The premixed gas ejection part 11 includes an inlet 12 that communicates with the vaporization chamber 9 and into which the premixed gas flows, and an outlet 13 that ejects the premixed gas. The inlet 12 is positioned higher than the evaporation part 6. Is provided.

  The burner unit 2 communicates with the premixed gas burner 14 that burns the premixed gas, the hydrogen-containing gas burner 15 that burns the hydrogen-containing gas, and the supply chamber 10 and supplies the secondary air to the flame formed by the burner unit 2. And a flame plate 17 provided with a plurality of through-holes, and is provided below the vaporizer 1 in the vertical direction.

  The premixed gas burner 14 includes a cylindrical premixed gas passage 18 that is a supply path of the premixed gas, and a premixed gas outlet 21 described later, and the premixed gas burner 14 is injected from the ejection port 13 of the premixed gas ejection unit 11. The mixed gas is supplied to the premixed gas passage 18.

  The hydrogen-containing gas burner 15 includes a hydrogen-containing gas supply pipe 19 that supplies hydrogen-containing gas generated in the fuel cell, a hydrogen-containing gas chamber 20 that is connected to the downstream end of the hydrogen-containing gas supply pipe 19, and a hydrogen-containing gas that will be described later. The gas outlet 22 is configured. The hydrogen-containing gas supply pipe 19 and the hydrogen-containing gas chamber 20 form a hydrogen-containing gas supply path, and the hydrogen-containing gas discharged from the hydrogen electrode of the fuel cell passes through the hydrogen-containing gas supply pipe 19. To the hydrogen-containing gas chamber 20.

  The premixed gas passage 18, the hydrogen-containing gas chamber 20 and the secondary air passage 16 are connected to a flame plate 17 provided with a plurality of through-holes as shown in FIG. Thus, the burner part 2 is closed.

  Among the ejection holes provided in the flame plate 17, a premixed gas ejection hole (first combustion gas ejection hole) 17 a provided in the center of the flame plate 17 communicates with the premixed gas passage 18. These flame holes are configured as a premixed gas deriving unit 21 for deriving the premixed gas, and the combustion mixed gas ejected from the premixed gas deriving unit 21 is ignited by an ignition device (not shown) to start combustion.

  A hydrogen-containing gas ejection hole (second combustion gas ejection hole) 17b provided around the premixed gas ejection hole 17a communicates with the hydrogen-containing gas chamber 20, and contains a hydrogen-containing gas for deriving the hydrogen-containing gas. The gas outlet 22 is configured.

  Further, a secondary air ejection hole 17 c is provided at the peripheral edge of the flame plate 17 so as to surround the periphery of the hydrogen-containing gas ejection hole 17 b, and the secondary air ejection hole 17 c communicates with the secondary air passage 16. Therefore, the secondary air deriving unit 23 is configured to derive secondary air.

  The hydrogen-containing gas is supplied so that the internal pressure of the passage for supplying the hydrogen-containing gas (hydrogen-containing gas supply pipe 19 and hydrogen-containing gas chamber 20) is smaller than the internal pressure of the passage for supplying secondary air (secondary air passage 16). The diameter of the gas ejection hole 17b and the diameter of the secondary air ejection hole 17c are determined.

  Specifically, a value obtained by dividing the flow rate of the gas flowing through each supply path by the total area of the ejection holes is defined as a flow rate (flow rate = flow rate / total area of the holes), and the secondary air flow rate is greater than the flow rate of the hydrogen-containing gas. The hole diameter is set so as to be larger.

  For example, in this embodiment, when the number of hydrogen-containing gas ejection holes 17b and the number of secondary air ejection holes 17c is 8, the diameter of the secondary air ejection holes 17c is φc2.0, and the combustion amount is 1000 kcal / h. When the flow rate of the gas flowing through the supply path was measured, the hydrogen-containing gas was 1.76 × 10 −4 m 3 / s and the secondary air was 1.83 × 10 −4 m 3 / s. At this time, in order to make the flow rate of the secondary air larger than the flow rate of the hydrogen-containing gas, the hole diameter of the hydrogen-containing gas ejection hole 17b needs to be φb 1.96 or more. Therefore, in this embodiment, the hole diameter of the hydrogen-containing gas ejection hole 17b is set to φb2.0.

  Further, the outer peripheral wall of the burner portion 2 is bent toward the center downstream of the flame plate 17, and the bent portion is configured as secondary air turning means 24. Therefore, the air flowing into the air supply chamber 10 from the blower passage 3 is ejected from the secondary air outlet 23 through the secondary air passage 16, and then in the central direction of the flame plate 17 by the secondary air diverting means 24. It is turned and supplied as secondary air toward the flame formed in the burner section 2.

  Next, the operation of the combustion apparatus according to this embodiment having the above-described configuration will be described.

  First, when the operation of the fuel cell is instructed, energization to the heater 5 is started and the vaporizer 1 is heated. When a sensor (not shown) detects that the temperature of the vaporizer 1 has reached a temperature at which the liquid fuel can be vaporized, an instruction to start supplying the liquid fuel to the vaporizer 1 is issued. The fuel is supplied to the carburetor 1 through the fuel supply pipe 4.

  The liquid fuel supplied to the vaporizer 1 falls on the partition plate 7 and spreads in all directions, and drops from the dropping hole 8 to the evaporation unit 6. Then, the liquid fuel dropped onto the evaporation unit 6 is heated and vaporized to become a combustion gas, and the combustion gas diffuses into the vaporization chamber 9.

  At this time, a part of the air supplied from the air passage 3 to the air supply chamber 10 is taken as primary air into the vaporization chamber 9 from the gap of the liquid fuel supply pipe 4, so that the combustion diffused in the primary air and the vaporization chamber 9 is performed. A premixed gas is obtained by mixing with the working gas.

  The premixed gas flows from the inlet 12 into the premixed gas ejection portion 11 and is ejected from the ejection outlet 13 to the premixed gas passage 18. Since the inlet 12 is provided at a position higher than the evaporator 6, a space serving as a liquid fuel receiving tray is formed between the evaporator 6 and the inlet 12. And since sufficient time for the liquid fuel to completely vaporize can be given by retaining the unvaporized liquid fuel in this space, the fuel in the liquid state that has not evaporated is supplied to the premixed gas ejection section 11. There is no inflow. That is, the fuel contained in the premixed gas ejected from the ejection port 13 to the premixed gas passage 18 is only the completely vaporized combustion gas, and the combustion state in the burner unit 2 can be maintained satisfactorily. It is.

  Further, by providing the premixed gas ejection portion 11, the pressure inside the vaporizing chamber 9 is increased, and the pressure fluctuation inside the vaporizing chamber 9 generated by the evaporation of the liquid fuel is reduced by this pressure increase. Therefore, the fluctuation of the combustion amount is suppressed and mixing of the combustion gas and the primary air is sufficiently performed, so that the premixed gas to be ejected becomes uniform.

  In addition, in order to acquire the above-mentioned effect, the hole length of the premixed gas ejection part 11 is made larger than the diameter of the ejection port 13, and the ratio is preferably set to be twice or more.

  The premixed gas is ejected from the premixed gas outlet 21 provided at the center of the flame plate 17 through the premixed gas passage 18 and ignited by an ignition device (not shown) to burn in the premixed gas burner 14. Is started.

  At this time, secondary air is ejected from the secondary air outlet 23, and the secondary air is changed in the direction of ejection toward the center of the flame plate 17 by the secondary air diverting means 24, so that the premixing is performed. It is supplied toward the flame formed by the combustion of gas. Therefore, since the secondary air and the flame are effectively mixed, the premixed gas is completely burned.

  In this way, the reformer is heated by the combustion of the premixed gas. Then, when the temperature of the reformer rises to the operating temperature, generation of hydrogen-based reformed gas is started from kerosene as a raw fuel such as hydrocarbon, and this hydrogen-based reformed gas is supplied to the fuel cell. As a result, the fuel cell is activated and the power generation operation is performed.

  During the power generation operation of the fuel cell, not all of the hydrogen-based reformed gas supplied to the fuel cell is consumed for power generation, but a hydrogen-containing gas containing about several tens of percent of unreacted hydrogen gas. The hydrogen-containing gas is also used for combustion in the combustion device.

  Specifically, the hydrogen-containing gas discharged from the hydrogen electrode is supplied to the hydrogen-containing gas chamber 20 through the hydrogen-containing gas supply pipe 19 and is ejected from the hydrogen-containing gas outlet unit 22. Then, it comes into contact with the flame already formed in the premixed gas outlet 21 and ignites and burns, and combustion by both the premixed gas and the hydrogen-containing gas is started.

  And both flames complete combustion by taking in the secondary air supplied from the secondary air derivation part 23, and continue heating of a reformer. The premixed gas lead-out part 21 and the hydrogen-containing gas lead-out part 22 are provided on the same flame plate 17, and the distance between the two is short, so that the hydrogen-containing gas ejected from the hydrogen-containing gas lead-out part 22 is surely flame. Will ignite in contact with.

  By the way, since the hydrogen-containing gas supply pipe 19 and the hydrogen-containing gas chamber 20 which are paths for supplying the hydrogen-containing gas are assembled by fitting or welding, there is a possibility that a gap or a hole may be generated in the assembly process, or at the time of assembly. Even if it is completely sealed, there is a possibility that parts are distorted by heat and a gap is formed in the fitting portion with combustion. Then, the hydrogen-containing gas tries to leak out from the slight gap, but the internal pressure of the path for supplying the secondary air is higher than the internal pressure of the path for supplying the hydrogen-containing gas. Is not mixed into the secondary air passage 16. Therefore, it is possible to solve the problem that the hydrogen-containing gas is exhausted unburned together with the secondary air that has not contributed to the combustion.

  Since the hydrogen-containing gas supply pipe 19 and the hydrogen-containing gas chamber 20 are arranged so as to be surrounded by the secondary air passage 16, all the supplied second combustion gas does not leak to the outside, and all the burners are discharged. Since it will be burned by the part 2, it can be used more safely.

  Further, in this embodiment, the flow velocity is calculated from the flow rate of the gas flowing through the supply path and the total area of the ejection holes, and the secondary air ejection holes 17c are set so that the flow velocity of the secondary air is larger than the flow velocity of the hydrogen-containing gas. By setting the hole diameter of the hydrogen-containing gas ejection hole 17b, the internal pressure of the passage for supplying the secondary air is increased, and leakage of the hydrogen-containing gas can be effectively prevented by such a simple configuration. There is no problem that workability at the time of assembling deteriorates or the manufacturing cost increases.

  Immediately after the reformer is activated, the supply of the reformed gas containing hydrogen as a main component to the fuel cell is not stable, and the amount of hydrogen-containing gas discharged from the fuel cell is also unstable. Therefore, since it is difficult to maintain stable combustion with only the hydrogen-containing gas, the combustion with both the premixed gas and the hydrogen-containing gas is continued for a while after the operation of the reformer.

  Then, when the combustion of the hydrogen-containing gas is stabilized, the supply of the liquid fuel to the vaporizer 1 is stopped, and the process shifts to combustion with the hydrogen-containing gas alone. In addition, since the amount of the hydrogen-containing gas depends on the output of the fuel cell, when the hydrogen-containing gas burner 15 alone burns, if the output of the fuel cell is low and the discharge amount of the hydrogen-containing gas is small, the combustion amount is insufficient. The temperature required for the operation of the reformer cannot be maintained. Therefore, when the temperature of the reformer detected by a sensor (not shown) falls below a predetermined value, liquid fuel is again supplied to the vaporizer 1 to generate a premixed gas, and the premixed gas and the hydrogen-containing gas The reformer is heated by burning both.

17 Flame plate 17a Premixed gas injection hole (first combustion gas injection hole)
17b Hydrogen-containing gas ejection holes (second combustion gas ejection holes)
17c Secondary air outlet

Claims (2)

  A combustion apparatus for burning a second combustion gas after burning the first combustion gas, a path for supplying the first combustion gas, a path for supplying the second combustion gas, and a flame. A combustion apparatus comprising a path for supplying secondary air, wherein an internal pressure of a path for supplying secondary air is made higher than an internal pressure of a path for supplying a second combustion gas.   A first combustion gas ejection hole is provided in the center, a second combustion gas ejection hole is provided so as to surround the first combustion gas ejection hole, and further surrounds the second combustion gas ejection hole. The combustion apparatus according to claim 1, further comprising a flame plate provided with a secondary air ejection hole.

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