JP2007165239A - Evaporative emission generating device, and fuel cell using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaporative emission generating apparatus with a simple structure, maintaining the amount of evaporative emitted within a prescribed range. <P>SOLUTION: The evaporative emission generating apparatus is constituted of a container body (1); a supply tube (2) supplying liquid in the container body, having an opening at lower part of the container body; a gas supply tube (3) introducing carrier gas in the liquid supplied inside the container body; a heating means (5) evaporating the liquid, arranged on or outside of the container body; an exhaust tube (4) exhausting the carrier gas and the evaporative emission: a large number of heat-conducting members (11), filled in the container body from lower part up to at least the upper part of an interface between the liquid and the vaporized gas, having liquid flow passages between them; and a level control means for maintaining the interface (I) between the gas and the evaporative emission in the container body within a prescribed range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an evaporative gas generator, and more particularly to a water vapor generator suitably used when reforming a reforming raw material gas in a small fuel cell.

Conventionally, in a fuel cell, when methane gas or the like supplied as city gas is used as a raw material for fuel gas, a reformer for reforming the raw material gas and taking out hydrogen has been used.
This reformer mixes the steam supplied from the steam generating section and the reforming raw material gas, and further generates hydrogen by reacting both in a high temperature atmosphere of about 350 ° C. or higher. .

That is, in the reformer, first, a hydrocarbon such as methane, which is a reforming raw material gas, reacts with steam to generate hydrogen and carbon monoxide, and then the carbon monoxide and steam react. As a result, hydrogen is generated together with oxygen dioxide.
An example of methane as a reaction formula is as follows.
CH ₄ + H ₂ O (g) → 3H ₂ + CO
CO + H ₂ O (g) → H ₂ + CO ₂

  By the way, in recent years, with the progress of the development of fuel cells, there is a strong demand for downsizing. In order to reduce the size of the fuel cell, it is necessary to stably supply a small amount of hydrogen gas as the fuel gas.

On the other hand, as a conventional reformer, as shown in, for example, Patent Document 1, there are various types in which a steam generator is integrated.
As shown in FIG. 2, the reformer includes a reforming section 8 filled with a reforming catalyst 8a and a fuel section 9 filled with a combustion catalyst 9a from left to right in the drawing. And the steam generator 10 are sequentially arranged opposite to each other.

  In the reformer composed of the upper part, the fuel is supplied to the fuel unit 9 and supplied to the steam generation unit 10 using the combustion heat obtained by burning a part of the fuel with the combustion catalyst 9a. The water is evaporated to obtain water vapor, and the water vapor and the raw material gas are mixed and supplied to the reforming unit 8 to generate hydrogen as the fuel gas as described above.

  However, in the above-described conventional reformer, first, steam is generated from water, and the obtained steam and raw material gas are mixed and supplied to the reforming unit 8. If is changed absolutely or relatively, there is a problem that the amount of water vapor generated is likely to fluctuate. And the fluctuation | variation of this water vapor generation amount and raw material gas supply amount also has a problem that the mixture ratio of the mixed gas supplied to the reforming part 8 also changes, and it becomes difficult to stably supply a small amount of hydrogen gas.

  Further, since the generated water vapor and the raw material gas are mixed and supplied to the reforming section 8, there is no problem when the flow rates of both are large, but the supply flow rate of the water vapor and the raw material gas is reduced. However, there is also a problem that it is difficult to generate a certain amount of hydrogen gas smoothly and surely because of an uneven mixing of the two.

JP 2003-63803 A

  Therefore, an object of the present invention is to provide an evaporative gas generator having a simple structure and stably supplying a certain amount of vapor gas.

  According to the first aspect of the present invention, there is provided a container main body, a supply pipe that opens at a lower portion of the container main body and supplies a liquid therein, and a carrier gas in the liquid supplied to the inside of the container main body. A gas supply pipe to be introduced; a heating means disposed on or outside the container main body for evaporating the liquid; a discharge pipe for discharging the carrier gas and the evaporating gas; and at least a liquid from a lower portion in the container main body. A large number of heat transfer members that are filled up to a position above the interface between the gas and the evaporative gas and in which the liquid flow path is formed, and the interface between the liquid and the evaporative gas in the container body is within a certain range The evaporative gas generator is provided with level control means for holding the gas.

  According to a second aspect of the present invention, in the evaporative gas generator according to the first aspect, the level control means includes a temperature sensor that measures the temperature of the inside or the side surface of the container body, and the temperature sensor measures the temperature sensor. And a heat radiation amount control means for adjusting the heat radiation amount of the heating means so that the temperature falls within a certain range.

  According to a third aspect of the present invention, in the evaporative gas generator according to the first or second aspect, the heat transfer member is a ceramic bead.

  According to a fourth aspect of the present invention, in the evaporative gas generator according to any one of the first to third aspects, the liquid is water, and the carrier gas is a reforming raw material gas. Features.

  According to a fifth aspect of the present invention, there is provided a fuel cell comprising the evaporative gas generating device according to the fourth aspect.

  A sixth aspect of the present invention is the fuel cell according to the fifth aspect of the present invention, comprising a reformer having a multi-stage configuration in which each is connected in series, and at least the foremost reformer includes a large number of power generation cells. It is characterized in that it is disposed away from the last-stage reformer from the stacked fuel cell stack.

  According to the first aspect of the present invention, the liquid is supplied from the supply pipe opened at the lower part of the container body, and the carrier gas is supplied from the gas supply pipe into the liquid, and the heat transfer member is filled by the heating means. The liquid is evaporated in the container body, and the evaporated gas is discharged from the discharge pipe together with the carrier gas.

  At that time, since the liquid is evaporated in the container body filled with a large number of heat transfer members from the lower part to at least the position above the interface between the liquid and the vapor gas, the evaporated gas can be obtained efficiently. Further, since the carrier gas is introduced into the liquid, the carrier gas is easily and uniformly mixed in the liquid and the evaporated gas in parallel with the evaporation of the liquid in the process of passing through the flow path between the heat transfer members. be able to.

In addition, since it has a level control means for maintaining the interface between the evaporative gas and the carrier gas in a certain range, the liquid supply amount from the discharge pipe and the discharge amount of the evaporative gas from the discharge pipe are matched, A constant amount of evaporative gas can be stably supplied at all times. In particular, the supply amount of the liquid and the carrier gas is set in advance to a value corresponding to the desired mixing ratio of the liquid and the carrier gas, and without separately adjusting the supply flow rates of the liquid and the carrier gas, It is possible to reliably supply evaporating gas having a predetermined mixing ratio.
As a result, with a simple structure, a very small amount of evaporative gas can be stably supplied together with the carrier gas.

In this case, in the invention according to claim 2, the temperature sensor for measuring the temperature of the inside or the side surface of the container body matches the supply amount of the liquid from the supply pipe with the discharge amount of the evaporated gas from the discharge pipe. When a temperature lower than the set temperature is detected, the interface between the liquid and the evaporative gas rises gradually. Similarly, when the temperature sensor detects a temperature higher than the set temperature, the liquid and the evaporative gas The interface of descents gradually.
For this reason, even when the interface cannot be directly grasped, the temperature of the inside or the side surface of the container body measured by the temperature sensor is indirectly adjusted by adjusting the temperature to be within a certain range centered on the predetermined temperature. In addition, the interface between the liquid and the evaporating gas can be maintained within a certain range.

  The above heat transfer member has a wide heat transfer area and communicates with each other so that the liquid or the vaporized gas and the carrier gas are meandered and mixed in the vertical and horizontal directions. In order to form a channel, ceramic beads are preferred as in the invention described in claim 3.

  The evaporative gas generator described above is suitable for a steam generator for a reformer for a small fuel cell. Therefore, as in the invention described in claim 4, water is used as the liquid, and a reforming raw material gas is used as the carrier gas. In this case, since the steam and the carrier gas are uniformly mixed and discharged, if the conditions such as the temperature and the arrangement of the reforming catalyst are separately set, the steam generator can be easily changed to the reformer. It is possible to reduce the size of the reformer and supply a small amount of hydrogen gas stably.

  Thus, when the evaporative gas generator is used in a steam generator for a fuel cell, the front-stage reformer is disposed farther away from the fuel cell stack than the last-stage reformer. By combining with the reformer of the configuration, the fuel cell stack can be cooled by the endothermic action of the reformer to avoid the inconvenience of lowering the power generation performance, and steam generation using the exhaust heat of the fuel cell stack Since a high temperature exhaust gas can always be introduced into the apparatus, a stable amount of water vapor can be generated.

Hereinafter, a water vapor generator for a fuel cell, which is an embodiment of the evaporative gas generator of the present invention, will be described with reference to FIG.
The steam generator in the present embodiment supplies a container main body 1, a supply pipe 2 for supplying water (liquid) connected so as to have an opening in the lower portion of the container main body 1, and a reforming raw material gas (carrier gas). A gas supply pipe 3 for heating, a heating means 5 for evaporating water, a discharge pipe 4 for discharging the reforming raw material gas and water vapor, and a level control means for maintaining the interface I between water and water vapor in a certain range. It is configured.

  The supply pipe 2 is connected to the bottom of the container body 1 via an adjustment flow valve 21, and a porous plate 22 is provided at an opening in the container body 1. The gas supply pipe 3 is provided so as to protrude upward from the bottom of the container main body 1 with a flow rate adjustment valve 31 interposed therebetween, and a porous plate 23 is provided at an opening in the container main body 1. As the perforated plates 22 and 32, those having a mesh that does not affect the supply of water or raw material reformed gas are suitable.

The heating means 5 is preferably an electric heater (for example, 100 W), and is provided so as to surround the outer periphery of the side surface of the container body 1. The electric heater 5 is provided so as to cover the lower end portion from the upper end portion of the container body 1, and is divided at the central portion so that the upper and lower electric heaters 5 are controlled independently. Yes.
Note that the electric heater 5 is not limited to the one provided in the upper and lower parts as described above, and any electric heater can be used as long as the amount of heat radiation can be controlled separately.

  The container body 1 has a capacity for ensuring the amount of water vapor supply, and the water supplied from the supply pipe 2 evaporates by being stored in the lower part and heated by heating means, The upper part is filled with water vapor. Further, a large number of ceramic beads (heat transfer members) 11 having a particle diameter of 0.5 mm to 3 mm are filled from the lower part to the upper part, and a flow path of water and the reforming raw material gas is formed between the ceramic beads 11. It has become so.

  The ceramic beads 11 absorb heat from the electric heater 5 and perform a heat transfer function with respect to water, water vapor, and the reforming raw material. It is intended to promote mixing. Therefore, zirconia, alumina, magnesia, mullite, and aluminum nitride can be used as the ceramic beads 11. Magnesia, mullite, and aluminum nitride are preferable from the viewpoint of thermal conductivity, and zirconia and alumina are preferable from the viewpoint of strength. Used for.

On the other hand, the discharge pipe 4 is connected to the ceiling of the reaction vessel 1.
Regarding the diameters of the discharge pipe 4 and the gas supply pipe 3, for example, when the inner diameter of the discharge pipe 4 is 4 mm and the outer diameter is 6 mm, the inner diameter of the gas supply pipe 3 is 2 mm and the outer diameter is 4 mm.

  As the level control means, the temperature sensors 6a and 6b disposed on the upper and lower sides of the side surface of the container body 1, and the upper side surface of the container body 1 is at the boiling point (100 ° C.) based on the detected temperature from the temperature sensor 6a. The amount of heat released from the electric heater 5 so that the lower part of the side surface of the container body 1 becomes a set temperature (for example, 80 ° C.) below the boiling point temperature (100 ° C.) by the set temperature (for example, 200 ° C.) and the temperature detected from the temperature sensor 6b. And a heat radiation amount control means 7 for adjusting the temperature. The temperature sensors 6a and 6b can be arranged at the upper and lower parts inside the container body 1 instead of the upper and lower parts on the side surface of the container body 1, but in this case, steam and reforming raw material gas are used. In order to prevent leakage, a seal member or the like is provided at the temperature sensor inlet of the container body 1.

  Furthermore, a fuel cell can be obtained by sequentially connecting a fuel cell stack formed by laminating a large number of reformers and power generation cells downstream of the discharge pipe 4. In this case, the reformer has a multi-stage configuration in which each is connected in series, and the foremost reformer is disposed at a location (for example, an exhaust pipe) separated from the last reformer from the fuel cell stack. It is preferable that As a result, the fuel cell stack can be cooled by the endothermic action of the reformer to avoid the inconvenience of lowering the power generation performance, and for the steam generator that uses the exhaust heat of the fuel cell stack, Since high-temperature exhaust gas can be introduced, it contributes greatly to the generation of a stable amount of water vapor.

Next, the operation of the water vapor generating apparatus having the above configuration will be described with reference to FIG.
First, the flow rate adjustment valve 21 is opened, and water is supplied from the supply pipe 2 into the container body 1. At the same time, the electric heater 5 is turned on to warm the container body 1, and at the same time, the flow rate adjusting valve 31 is opened to supply the reforming raw material gas from the gas supply pipe 3 to the container body 1.
Then, the reforming raw material gas rises while meandering the gap between the ceramic beads 11 filled in the liquid phase L in the form of bubbles in the vertical and horizontal directions.

  Next, the flow rate adjusting valves 21 and 31 are adjusted to a preset opening degree from a desired steam supply amount and a mixing ratio of the steam and the reforming raw material gas. At the same time, the amount of heat released from the electric heater 5 is adjusted so that the temperature sensor 6 indicates a set temperature (for example, upper 200 ° C., lower 80 ° C.) where the water supply amount and the water vapor discharge amount coincide with each other. adjust.

  Specifically, when the upper or lower temperature sensor 6 on the side surface of the container body 1 senses a temperature higher than the set temperature, the interface I between water and water vapor has dropped, so It is used to reduce the heat dissipation amount of the electric heater 5. On the other hand, when the upper or lower temperature sensor 6 senses a temperature lower than the set temperature, the interface I between water and water vapor rises, so that the heat release amount control means 7 is used to release the electric heater 5. Increase the amount of heat.

Thereby, the temperature of the upper part or the lower part on the side surface of the container body 1 is kept within a certain range, and the interface I between water and water vapor is indirectly adjusted within the certain range.
In particular, even when there is a difference in water level due to the ceramic beads 11 filled in the container body 1 and the interface I between water and water vapor cannot be measured directly, the temperature of the upper or lower part on the side surface of the container body 1 is kept within a certain range. By maintaining the inside, the interface I between water and water vapor is indirectly adjusted within a certain range.

  Then, the water supplied into the container main body 1 meanders along the gap between the ceramic beads 11 together with the reforming raw material gas in the vertical direction and the horizontal direction, rises while being uniformly mixed, and is heated by the electric heater 5 and thereby. The ceramic beads 11 are heated and evaporated. Thereby, the upper part of the container body 1 is filled with water vapor and the reforming raw material gas, and these are uniformly mixed by the ceramic beads 11. Steam is discharged together with the reforming raw material gas. Therefore, it is not necessary to separately mix the steam and the reforming raw material gas in the reformer as a post process.

As described above, a constant amount of water vapor can always be supplied to the subsequent process even in a small amount.
At that time, the opening ratio of the flow rate adjusting valve 21 and the flow rate adjusting valve 31 can be adjusted to control the mixing ratio of water and the reforming raw material gas. In addition, the amount of water vapor discharged from the discharge pipe 4 can be increased or decreased by varying the set temperature of the electric heater 5 described above.

  In particular, by setting the set temperature at the upper part to a temperature suitable for reforming and arranging a reforming catalyst separately, a small amount of hydrogen gas can be stably supplied using this steam generator, It is possible to easily change this steam generation to a small reformer.

  Note that the present invention is not limited to the above-described water vapor generating device. For example, as means for maintaining the interface I between the liquid and the evaporative gas in a certain range, the liquid and the evaporative gas are used instead of the temperature sensor 6. An interface sensor for measuring the interface I and an interface observation window may be provided. Further, the heating means 5 is not limited to an electric heater, and may be exhaust gas discharged from a fuel cell, for example.

It is a cross-sectional schematic diagram of the water vapor generator shown as one embodiment of the present invention. It is a cross-sectional schematic diagram of the water vapor generator shown as a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Container body 2 ... Supply pipe 3 ... Gas supply pipe 4 ... Discharge pipe 5 ... Heating means (electric heater)
6 ... Temperature sensor 7 ... Heat radiation control means 11 ... Heat transfer member (ceramic beads)
I ... Interface

Claims (6)

A container main body, a supply pipe that opens at a lower portion of the container main body and supplies a liquid therein, a gas supply pipe for introducing a carrier gas into the liquid supplied to the inside of the container main body, and the container main body Or a heating means disposed on the outside thereof for evaporating the liquid, a discharge pipe for discharging the carrier gas and the evaporating gas, and filling from the lower part in the container body to at least a position above the interface between the liquid and the evaporating gas. And a plurality of heat transfer members in which the liquid flow paths are formed, and level control means for maintaining the interface between the liquid and the evaporative gas in the container body within a certain range. An evaporative gas generator. The level control means includes a temperature sensor for measuring the temperature of the inside or the side surface of the container body, and a heat release amount control for adjusting the heat release amount of the heating means so that the temperature measured by the temperature sensor is within a certain range. The evaporative gas generator according to claim 1, further comprising: means. The evaporative gas generator according to claim 1, wherein the heat transfer member is a ceramic bead. 4. The evaporative gas generator according to claim 1, wherein the liquid is water, and the carrier gas is a reforming raw material gas. A fuel cell comprising the evaporative gas generator according to claim 4. Each has a multi-stage reformer connected in series, and at least the foremost reformer is farther away from the fuel cell stack formed by stacking a large number of power generation cells than the last reformer. The fuel cell according to claim 5, wherein the fuel cell is disposed.

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