JP2016023107A - Reformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reformer that can reduce the amount of steam to be fed without causing carbon deposition due to decrease in S/C.SOLUTION: In a reformer 10, a source gas is fed into a case 100 through a plurality of openings OP2, OP3 located at different positions along the steam flowing direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reformer that generates a hydrogen-containing gas by steam reforming.

  The fuel cell device is provided with a reformer for generating a hydrogen-containing gas that is a fuel gas. Various types of reformers are known as such reformers. Among them, a reformer configured to generate hydrogen from a hydrocarbon by steam reforming can generate hydrogen with relatively high efficiency, and is therefore often used particularly in a solid oxide fuel cell device.

  In the steam reforming, hydrocarbon (methane) and steam are reacted under a high-temperature reforming catalyst, and hydrogen is generated by the reaction. In order to continue such steam reforming in the reformer, it is necessary to supply steam to the reformer. For this reason, an evaporator that heats water to generate water vapor and supplies the water vapor to the reformer is generally provided together with or integrally with the reformer (the following patents). Reference 1).

  If the amount of water vapor supplied to the reformer is insufficient and the hydrocarbons are relatively excessive, carbon deposition occurs on the surface of the reforming catalyst, preventing the production of hydrogen. It has been known. In order to prevent such a phenomenon, more steam than the minimum amount of steam necessary for steam reforming is often supplied from the evaporator to the reformer. Specifically, the steam (and hydrocarbons) to the reformer so that the stoichiometric ratio (so-called “S / C”) of steam and hydrocarbons is in the range of 2.5 to 3.0. Is often set.

JP 2007-5133 A

  In the evaporator, water vapor is generated by heating and boiling water. Here, when the amount of water vapor generated is large, that is, when a large amount of water is boiled, there is a high possibility that the amount of water vapor generated is not constant and fluctuates due to the generation of large bubbles or bumping. Become. As a result, the amount of steam supplied to the reformer also fluctuates, and there is a high possibility that carbon will temporarily precipitate due to a shortage of steam.

  In view of stably generating steam in the evaporator and suppressing fluctuations in the amount of steam supplied to the reformer, the evaporator is miniaturized as much as possible, and the amount of steam generated in the evaporator (water to be boiled) It is desirable to reduce the amount). However, since the amount of hydrogen required for power generation is determined, the amount of hydrocarbons supplied to the reformer cannot be reduced. Therefore, in the conventional reformer as described in Patent Document 1, if the evaporator is downsized and the amount of steam supplied is reduced, the S / C is lowered and carbon deposition occurs. The possibility increases. For this reason, it has been difficult to downsize the evaporator and reduce the amount of water vapor supplied to the reformer.

  This invention is made | formed in view of such a subject, The objective is the reformer which can reduce the quantity of the water vapor | steam supplied, without producing the carbon precipitation by the fall of S / C. It is to provide.

  In order to solve the above-described problems, a reformer according to the present invention is a reformer that generates a hydrogen-containing gas by steam reforming, and contains a reforming catalyst (RC1, RC2) inside (100). 100A), source gas supply means (GS1, GS2, 32, 42) for supplying source gas into the case, steam supply means (EV, 22) for supplying steam into the case, and steam reforming reaction And a discharge means (51) for discharging the generated hydrogen-containing gas out of the case. The source gas supply means is characterized in that source gas is supplied to the case from a plurality of supply locations (OP2, OP3) whose positions are different from each other along the direction in which water vapor flows.

  In the reformer according to the present invention, the supply of the raw material gas (hydrocarbon) to the case is not performed from only one location on the upstream side, but a plurality of locations (supply) that are different from each other along the direction in which the steam flows. From place). If the supply amount of the raw material gas to the entire reformer is the same as the conventional amount, the supply amount of the raw material gas at each supply point becomes smaller than the conventional amount.

  In this case, the supply amount of the source gas at the most upstream supply location is also reduced as compared with the conventional case. Therefore, even if the supply amount of water vapor is reduced in accordance with this, at least the S / C value in the vicinity of the supply location can be maintained in an appropriate range (for example, 2.5 to 3.0).

  Here, when the supply amount of water vapor is reduced as described above, the water vapor is insufficient in the vicinity of the supply point on the downstream side (the raw material gas becomes relatively excessive). It also seems that the value of C will be smaller than the appropriate range. That is, it seems that the S / C value is appropriate in the upstream portion of the interior of the reformer (case), while the S / C value is excessively lowered in the downstream portion. .

  However, since the steam reforming reaction proceeds inside the reformer, the amount of the raw material gas supplied from the most upstream supply point gradually decreases as it flows toward the downstream side. On the other hand, of the steam supplied to the reformer, the steam corresponding to the amount additionally supplied to prevent carbon deposition (exceeding the minimum supply required for steam reforming) is steam reforming. Even if the reaction proceeds, the amount does not decrease and flows directly downstream. For this reason, the S / C value in the downstream portion of the reformer tends to be higher than the S / C value in the upstream portion. As a result, since the value of S / C exceeds an appropriate range (2.5 to 3.0) in the downstream portion, even if hydrocarbons are supplied from the supply location of the portion, S / C The value never drops too much. Rather, since the source gas is additionally supplied toward the downstream portion where the S / C value is high, it is possible to keep the S / C value within an appropriate range in almost the entire interior of the reformer. It becomes.

  As described above, the present invention has been made based on the knowledge that the S / C value increases in the reformer as it goes downstream. By dividing the supply point of hydrocarbons to the reformer into a plurality, it becomes possible to prevent the occurrence of carbon deposition due to the decrease in S / C while reducing the amount of steam supplied to the reformer.

  ADVANTAGE OF THE INVENTION According to this invention, the reformer which can reduce the quantity of the water vapor | steam supplied can be provided, without producing the carbon precipitation by the fall of S / C.

It is a schematic diagram which shows the structure of the fuel cell apparatus provided with the reformer which concerns on 1st Embodiment of this invention. It is a graph which shows distribution of the water vapor | steam and raw material gas in the inside of the modifier shown by FIG. It is a schematic diagram which shows the structure of the fuel cell apparatus provided with the reformer which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the structure of the fuel cell apparatus provided with the reformer which concerns on the comparative example of this invention. It is a graph which shows distribution of the water vapor | steam and raw material gas in the inside of the modifier shown by FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  As schematically shown in FIG. 1, the fuel cell device FC includes a cell stack CS (fuel cell stack), a reformer 10, an evaporator EV, a first fuel supply device GS1, and a second fuel supply. A device GS2 and a control device CU are provided.

  The cell stack CS is an assembly of a plurality of fuel cells (not shown). Each fuel cell is a solid oxide fuel cell (SOFC), and a fuel electrode (anode) is formed on one surface of a flat solid electrolyte, and the other surface. In this configuration, an air electrode (cathode) is formed. These fuel electrode and air electrode are both porous bodies formed of conductive ceramics. In the cell stack CS, all the fuel cells are stacked in the vertical direction, and these are electrically connected in series. The cell stack CS generates power by receiving supply of fuel gas from the reformer 10 and supply of air from a blower (not shown).

  The reformer 10 generates a hydrogen-containing gas by a steam reforming reaction, and supplies the hydrogen-containing gas to the cell stack CS as a fuel gas. The reformer 10 includes reforming catalysts RC1 and RC2 and a case 100 that stores them inside.

  The reforming catalysts RC1 and RC2 are obtained by supporting a catalytic metal such as nickel on the surface of an alumina sphere. The reforming catalysts RC1 and RC2 are the same. Since these are housed in different positions in the case 100, different reference numerals (RC1, RC2) are given for convenience of explanation.

  Case 100 is a heat-resistant container formed of stainless steel. The internal space of the case 100 is partitioned by four partition plates (111, 112, 113, 114) arranged so as to be parallel to each other, and as a result, five spaces (SP1, SP2, SP3, SP4). , SP5). Each of the partition plates (111, 112, 113, 114) is formed with a plurality of through holes (not shown) so that water vapor or source gas can pass therethrough. The spaces SP1, SP2, SP3, SP4, and SP5 are arranged in order along the direction in which the water vapor supplied from the evaporator EV flows in the case 100 (the direction from the bottom to the top in FIG. 1).

  In the following description, the upstream side in the water vapor flow in the case 100 may be simply referred to as “upstream side”, and the downstream side in the water vapor flow may be simply referred to as “downstream side”.

  The space SP1 is a space formed on the most upstream side. As will be described later, the water vapor supplied from the evaporator EV and the raw material gas supplied from the first fuel supply device GS1 both first flow into the space SP1. The space SP1 is a relatively narrow space (the dimension along the direction in which water vapor flows is short). Further, the reforming catalysts RC1 and RC2 are not accommodated in the space SP1. The water vapor and source gas supplied to the reformer 10 are first mixed in the space SP1.

  The space SP2 is a space formed on the downstream side (upper side) of the space SP1. The space SP2 and the space SP1 are partitioned by a partition plate 111. A reforming catalyst RC1 is accommodated in the space SP2, and the reforming catalyst RC1 is supported from below by a partition plate 111. The diameters of the plurality of through holes formed in the partition plate 111 are smaller than the diameter of the reforming catalyst RC1 which is an alumina sphere. For this reason, the reforming catalyst RC1 does not pass through the through hole of the partition plate 111.

  The space SP3 is a space formed on the downstream side (upper side) of the space SP2. The space SP3 and the space SP2 are partitioned by a partition plate 112. The space SP3 is a relatively narrow space (the dimension along the direction in which water vapor flows is short) like the space SP1. Further, the reforming catalysts RC1 and RC2 are not accommodated in the space SP3. As will be described later, the space SP3 is a space into which the raw material gas supplied from the second fuel supply device GS2 flows first.

  The space SP4 is a space formed on the downstream side (upper side) of the space SP3. The space SP4 and the space SP3 are partitioned by a partition plate 113. A reforming catalyst RC2 is accommodated in the space SP3, and the reforming catalyst RC2 is supported from below by a partition plate 113. The diameters of the plurality of through holes formed in the partition plate 113 are smaller than the diameter of the reforming catalyst RC2, which is an alumina sphere. For this reason, the reforming catalyst RC2 does not pass through the through hole of the partition plate 113.

  The space SP5 is a space formed on the downstream side (upper side) of the space SP4. That is, the space formed on the most downstream side. The space SP5 and the space SP4 are partitioned by a partition plate 114. The space SP5 is a relatively narrow space (the dimension along the direction in which water vapor flows is short) like the spaces SP1 and SP3. Further, the reforming catalysts RC1 and RC2 are not accommodated in the space SP5. As will be described later, the space SP5 is a space in which the hydrogen-containing gas generated as a result of the steam reforming reaction, that is, the fuel gas immediately before being supplied to the cell stack CS flows in and is mixed finally.

  The evaporator EV generates steam necessary for steam reforming and supplies the steam to the reformer 10. A pipe 21 and a pipe 22 are connected to the evaporator EV. The pipe 21 is a pipe for supplying water to the evaporator EV from an external water supply source. A water supply pump (not shown) is provided in the middle of the pipe 21, and water sent out by the water supply pump is supplied to the evaporator EV through the pipe 21.

  The water supplied through the pipe 21 is heated and boiled inside the evaporator EV and becomes water vapor. In addition, as heat for heating water, for example, heat generated by a power generation reaction in the cell stack CS can be used. Alternatively, the remaining fuel gas discharged from the cell stack CS without being used for power generation may be burned by a burner, and water may be heated using the heat generated by the combustion.

  The pipe 22 is a pipe for supplying water vapor generated in the evaporator EV to the reformer 10. One end of the pipe 22 is connected to the evaporator EV, and the other end is connected to a lower end of the case 100, that is, a portion that divides the space SP1. An opening OP1 is formed in a portion of the case 100 to which the pipe 22 is connected (the lower end portion in the present embodiment). The water vapor generated in the evaporator EV reaches the reformer 10 through the pipe 22, and first flows into the space SP1 through the opening OP1.

  The first fuel supply device GS1 is a device for adjusting the supply amount of the raw material gas to the reformer 10. A pipe 31 and a pipe 32 are connected to the first fuel supply device GS1. The pipe 31 is a pipe for supplying a raw material gas from an external gas source to the first fuel supply device GS1. In this embodiment, city gas is used as source gas. The first fuel supply device GS1 includes an opening degree adjustment valve (not shown) that operates by control from the outside. The supply amount of the raw material gas to the reformer 10 is adjusted by the opening of the opening adjustment valve. Switching between the supply and stop of the source gas and the adjustment of the supply amount are controlled by the control unit CU.

  The pipe 32 is a pipe for supplying the raw material gas from the first fuel supply device GS1 to the reformer 10. One end of the pipe 32 is connected to the opening adjustment valve of the first fuel supply device GS1, and the other end is connected to the lower end of the case 100, that is, a portion that divides the space SP1. An opening OP <b> 2 is formed in a portion of the case 100 to which the pipe 32 is connected (a lower end portion in the present embodiment). The raw material gas that has passed through the opening adjustment valve of the first fuel supply device GS1 reaches the reformer 10 through the pipe 32, and first flows into the space SP1 through the opening OP2.

  Similar to the first fuel supply device GS1, the second fuel supply device GS2 is a device for adjusting the supply amount of the raw material gas to the reformer 10. A pipe 41 and a pipe 42 are connected to the second fuel supply device GS2. The pipe 41 is a pipe for supplying the source gas from the external gas source to the second fuel supply device GS2. The second fuel supply device GS2 includes an opening degree adjustment valve (not shown) that operates by external control. The supply amount of the raw material gas to the reformer 10 is adjusted by the opening of the opening adjustment valve. Switching between the supply and stop of the source gas and the adjustment of the supply amount are controlled by the control unit CU.

  The pipe 42 is a pipe for supplying the raw material gas from the second fuel supply device GS2 to the reformer 10. One end of the pipe 42 is connected to the opening adjustment valve of the second fuel supply device GS2, and the other end is connected to a side surface of the case 100, specifically, a portion that divides the space SP3. An opening OP3 is formed in a portion of the case 100 to which the pipe 42 is connected. The raw material gas that has passed through the opening adjustment valve of the second fuel supply device GS2 reaches the reformer 10 through the pipe 42, and first flows into the space SP3 through the opening OP3.

  The control unit CU is a computer system that includes a CPU, a ROM, a RAM, and an input / output interface, and is a device for controlling the overall operation of the fuel cell apparatus FC. As already described, the control unit CU adjusts the supply amount of the raw material gas to the space SP1 by controlling the first fuel supply unit GS1. Similarly, the supply amount of the raw material gas to the space SP3 is adjusted by controlling the second fuel supply device GS2. Further, the amount of water sent out toward the evaporator EV is adjusted by controlling the operation of a water supply pump (not shown). That is, the supply amount of water vapor from the evaporator EV to the space SP1 is adjusted.

  Other configurations will be described. A temperature sensor TS for detecting the temperature of the reforming catalyst RC1 is arranged in the space SP2. The temperature sensor TS and the control unit CU are connected by a signal line CB. The temperature of the reforming catalyst RC1 detected by the temperature sensor TS is transmitted to the control unit CU through the signal line CB. As will be described later, the control unit CU controls the supply timing of the raw material gas to the reformer 10 based on the temperature of the transferred reforming catalyst RC1.

  The reformer 10 and the cell stack CS are connected by a pipe 51. The pipe 51 is a pipe for supplying the fuel gas (hydrogen-containing gas) generated in the reformer 10 to the cell stack CS. One end of the pipe 51 is connected to the cell stack CS, and the other end is connected to the upper end of the case 100, that is, a portion that partitions the space SP5. An opening OP4 is formed in a portion of the case 100 to which the pipe 51 is connected (the upper end portion in the present embodiment). The fuel gas generated in the reformer 10 flows out of the case 100 through the opening OP4, and is supplied to the cell stack CS through the pipe 51.

The steam reforming reaction that occurs in the reformer 10 will be described. The steam reforming reaction is a reaction in which raw material gas (methane) and steam react with each other under a high temperature reforming catalyst to generate hydrogen. Such a steam reforming reaction is represented by the following formula (1).
CH ₄ + H ₂ O → 3H ₂ + CO (1)

In the reformer 10, CO generated by the steam reforming reaction reacts with the steam, and as a result, more hydrogen is generated. Such a reaction is referred to as a so-called “shift reaction” and is represented by the following formula (2).
CO + H ₂ O → CO ₂ + H ₂ (2)

Summarizing the above formulas 1 and 2, the overall reaction occurring inside the reformer 10 is expressed by the following formula (3).
CH ₄ + 2H ₂ O → 4H ₂ + CO ₂ (3)

  In the reformer 10, the steam reforming reaction as expressed by the formula (1) does not always occur in all of the supplied source gases, and some of the source gases do not contribute to the steam reforming reaction ( (Methane remains) Similarly, not all of the CO generated by the steam reforming reaction causes the shift reaction as shown in the formula (2), and some CO may be discharged without contributing to the shift reaction.

  As represented by the formula (3), in the reformer 10, a maximum of 2 mol of water is consumed for 1 mol of methane. In other words, when the stoichiometric ratio of steam and hydrocarbons supplied to the reformer 10 (so-called “S / C”) is smaller than 2, steam is insufficient and methane is relatively excessive. It will become. When excess methane touches the high-temperature reforming catalysts RC1 and RC2, carbon deposition occurs on the surfaces of the reforming catalysts RC1 and RC2, and it is known that hydrogen generation in the reformer 10 is hindered. It has been. Therefore, in the reformer 10 according to this embodiment, the supply amounts of water vapor and source gas are set so that the value of S / C is 3.0. That is, it can be said that 50% of steam is additionally supplied with respect to the minimum supply amount necessary for steam reforming.

  The reaction occurring inside the reformer 10 will be specifically described with reference to FIGS. The horizontal axis of the graph shown in FIG. 2 indicates the position inside the case 100. In FIG. 2, the position on the most upstream side along the direction in which the water vapor flows is denoted as P0, and the position on the most downstream side is denoted as P10. That is, the position P0 indicates a position having the same height as the opening OP1 and the opening OP2 in FIG. A position P10 indicates a position having the same height as the opening OP4 in FIG. Further, a position P1 between the position P0 and the position P10 indicates a position having the same height as the opening OP3 in FIG.

  In FIG. 2, a line G <b> 10 indicates the distribution of the amount of water vapor at each position of the case 100. A line G20 indicates the distribution of the amount of methane at each position of the case 100. A line G30 indicates a distribution of S / C values at each position of the case 100.

  The reformer 10 is supplied with water vapor from the evaporator EV and raw material gas from the first fuel supply device GS1, and these flow into the space SP1 and are mixed. The ratio between the supplied water vapor and the source gas is set so that the value of S / C in the space SP1 is 3. In the following description, a gas obtained by mixing water vapor and source gas is also referred to as “mixed gas”.

  The mixed gas flows from the space SP1 into the space SP2, and flows upward while touching the reforming catalyst RC1. The reformer 10 is heated from the outside, and the reforming catalyst RC1 is also at a high temperature. For this reason, in space SP2, the steam reforming reaction shown by said Formula (1) and the shift reaction shown by Formula (2) arise. In addition, as heat for heating the reformer 10, for example, heat generated by a power generation reaction in the cell stack CS can be used. Alternatively, the remaining fuel gas discharged from the cell stack CS without being used for power generation is burned with a burner, and the reformer 10 is heated using the heat generated by the combustion. Good.

  As shown in the range from the position P0 to the position P1 in the graph of FIG. 2, methane contained in the mixed gas is consumed by the steam reforming reaction, and thus the amount gradually decreases. In other words, the amount of methane decreases as it goes downstream. Further, since the water vapor contained in the mixed gas is consumed by the steam reforming reaction and the shift reaction, the amount thereof is gradually reduced. That is, the amount of water vapor decreases as it goes downstream.

  As it goes downstream, both methane and water vapor decrease, but the S / C value of the mixed gas increases as shown by line G30 in FIG. This is because steam corresponding to the amount additionally supplied to prevent carbon deposition flows toward the downstream side without contributing to the steam reforming reaction. For this reason, the value of S / C at the position P0 is 3, but the ratio of water vapor to the mixed gas increases toward the downstream side, so that the downstream side (closer to the position P1) becomes S. The value of / C becomes larger than 3.

  The mixed gas flows into the space SP3 with the S / C value raised as described above. The source gas from the second fuel supply device GS2 is supplied to the space SP3 and mixed with the mixed gas from the space SP2. As a result, in the space SP3, the ratio of the raw material gas to the mixed gas becomes high, so the value of S / C decreases near the position P1. However, since the value of S / C is larger than 3 as described above, the value of S / C is 3 (indicated by the dotted line DL in FIG. 2) even if the source gas is additionally supplied in the space SP3. Value).

  In this embodiment, the supply amount of the raw material gas supplied from the second fuel supply device GS2 is set to be ¼ of the supply amount of the raw material gas supplied from the first fuel supply device GS1. That is, 80% of the raw material gas required to generate the fuel gas is supplied from the first fuel supply device GS1 to the space SP1, and the remaining 20% is supplied from the second fuel supply device GS2 to the space SP3.

  Thereafter, the mixed gas flows from the space SP3 into the space SP4 and flows upward while touching the reforming catalyst RC2. In the space SP4, the steam reforming reaction and the shift reaction occur again. Also in the space SP4, the methane and water vapor contained in the mixed gas decrease as going to the downstream side, and the S / C value of the mixed gas increases again.

  The mixed gas that has passed through the space SP4 flows into the space SP5 on the most downstream side. At this time, since almost all of the methane contained in the mixed gas is consumed by the steam reforming reaction, the amount thereof is very small.

  Further, the hydrogen generated in the space SP2 and the space SP4 also flows into the space SP5 together with the mixed gas. For this reason, the space SP5 is filled with a hydrogen-rich gas, that is, a hydrogen-containing gas. This hydrogen-containing gas is supplied to the cell stack CS through the pipe 51 and used for power generation.

  In order to explain the advantages of the reformer 10 having the above-described configuration, as a comparative example of the present invention, a conventional reformer 10B having a general configuration and a fuel cell apparatus FCB including the same are described. This will be described with reference to FIGS.

  The reformer 10B has a configuration in which the partition plate 112 and the partition plate 113 are not disposed therein, and the entire space between the partition plate 111 and the partition plate 114 is filled with the reforming catalyst RC1. . That is, the space SP2, the space SP3, and the space SP4 of the reformer 10 are integrated into a space SP6, and the space SP6 is filled with the reforming catalyst RC1. Further, the opening OP3 is not formed on the side surface of the case 100B of the reformer 10B. Other configurations of the reformer 10B are the same as those of the reformer 10.

  The fuel cell device FCB is different from the fuel cell device FC in that it does not include the second fuel supply device GS2 and the piping 41 and the piping 42 connected thereto. That is, in the fuel cell device FCB, the fuel gas is supplied to the reformer 10B from only one location (opening OP2) at the lower end of the case 100B. Other configurations are the same as those of the fuel cell apparatus FC.

  FIG. 4 is a graph drawn corresponding to FIG. 2, and is a graph showing the amount of water vapor and the like inside the reformer 10 </ b> B. The horizontal axis of the graph shown in FIG. 4 indicates the position inside the case 100B. Also in FIG. 4, the position that is the most upstream side along the direction in which the water vapor flows is denoted as P0, and the position that is the most downstream side is denoted as P10.

  In FIG. 4, a line G11 indicates the distribution of the amount of water vapor at each position of the case 100B. A line G21 indicates the distribution of the amount of methane at each position of the case 100B. A line G31 indicates the distribution of S / C values at each position of the case 100B.

  As in the case of the fuel cell device FC, the reformer 10B is supplied with the water vapor from the evaporator EV and the raw material gas from the first fuel supply device GS1. These first flow into the space SP1 and are mixed.

  The supply of the raw material gas to the reformer 10B is performed only from one place of the opening OP2. That is, all (100%) of the raw material gas necessary for generating the fuel gas is supplied from the first fuel supply device GS1 to the space SP1. For this reason, the supply amount of the raw material gas supplied to the space SP1 of the reformer 10B is larger than the supply amount (80%) of the raw material gas supplied to the space SP1 of the reformer 10.

  Also in the reformer 10B, the supply amounts of water vapor and source gas are set so that the S / C value in the space SP1 is 3.0. For this reason, as the supply amount of the raw material gas supplied to the space SP1 of the reformer 10B increases as described above, the supply amount of water vapor also increases. That is, the amount of steam supplied from the evaporator EV to the reformer 10B is larger than the amount of steam supplied from the evaporator EV to the reformer 10. It can also be said that the amount of water additionally supplied to the reformer 10B in order to prevent carbon deposition is larger than in the case of the fuel cell device FC.

  As in the case of the reformer 10, the amount of methane and water vapor decreases in the reformer 10B as it goes downstream. Further, the value of S / C is 3 at the position P0, but becomes larger than 3 as it goes downstream.

  In the reformer 10B, the source gas is not additionally supplied from the middle (position P1). For this reason, the value of S / C does not decrease in the middle and increases monotonically as it goes downstream. As a result, the value of S / C at the position P10 is very large as compared with the case of the reformer 10. This is because the amount of steam corresponding to the amount additionally supplied to prevent carbon deposition (exceeding the minimum supply amount necessary for steam reforming) is larger than in the case of the reformer 10. Thus, the additional supply water vapor reaches the downstream end almost as it is without being subjected to the steam reforming reaction and the shift reaction. That is, in the fuel cell device FCB having the conventional configuration, the ratio of water vapor that is wasted without being used for the reaction is large.

  However, if the amount of water vapor supplied from the evaporator EV is reduced, the S / C value of the mixed gas in the space SP1 may be less than 3 and may be less than 2.5. For this reason, in view of preventing carbon deposition, it is not desirable to reduce the supply amount of water vapor in the reformer 10 having the configuration shown in FIG. In other words, it is not desirable to reduce the size of the evaporator EV.

  On the other hand, in the reformer 10 described with reference to FIGS. 1 and 2, the supply of the raw material gas to the case 100 is performed at a plurality of locations (opening PT2) having different positions along the direction (vertical direction) in which water vapor flows. And the opening PT3). As a result, the supply amount of the raw material gas from the opening PT2 is smaller than that in the case of the reformer 10B.

  The amount of steam that is required to set the S / C value in the space SP1 to 3 is also smaller than in the case of the reformer 10B. For this reason, it is possible to reduce the size of the evaporator EV while maintaining the S / C value within an appropriate range (2.5 to 3.0).

  Further, in the reformer 10, the raw material gas is additionally supplied from the opening OP3 to the downstream portion where the S / C value is high and there is a lot of excess water vapor. For this reason, the excess steam is not wasted and is effectively used for the steam reforming reaction and the shift reaction. As a result, even if the evaporator EV is downsized and the supply amount of water vapor is reduced as compared with the prior art, the S / C value does not fall below 3 inside the reformer 10, and carbon deposition occurs. There is no end to it.

  By the way, attention must be paid to the timing at which the raw material gas starts to be supplied from the second fuel supply device GS2 to the reformer 10 when the fuel cell device FC is started up. If the raw material gas is supplied from the opening OP3 before the water vapor supplied from the evaporator EV passes through the partition plate 112, that is, before reaching the space SP3, the value of S / C in the space SP3 is 3 It will be less than. As a result, when the mixed gas having a small S / C value reaches the reforming catalyst RC2, carbon deposition occurs.

  In the fuel cell device FC, in order to prevent such a phenomenon, the supply timing of the raw material gas from the second fuel supply device GS2 is appropriate based on the temperature of the reforming catalyst RC1 detected by the temperature sensor TS. It is adjusted so that.

  The control device CU performs control so that the supply of the raw material gas from the second fuel supply device GS2 is started when the temperature of the reforming catalyst RC1 falls below a preset threshold value. Since the steam reforming reaction represented by the formula (1) is an endothermic reaction, when the temperature is lowered at the position of the temperature sensor TS, it can be inferred that the steam has reached the position.

  Since the temperature sensor TS is disposed below the partition plate 112, when the temperature of the reforming catalyst RC1 falls below the threshold, water vapor has not yet reached the space SP3. However, even if the supply of the raw material gas from the second fuel supply device GS2 is started at this time, there is a time lag until the raw material gas reaches the opening OP3 from the second fuel supply device GS2. The space SP3 is never reached first. In the present embodiment, the position of the temperature sensor TS and the threshold value are set so that the water vapor from the evaporator EV and the raw material gas from the second fuel supply device GS2 reach the space SP3 at the same time. . With such a configuration, it is possible to start supplying fuel gas to the cell stack CS at an early timing while reliably preventing carbon deposition inside the reformer 10.

  As a sensor for measuring the supply start timing of the raw material gas from the second fuel supply device GS2, various sensors (detection means for detecting the state in the case 100) can be used instead of the temperature sensor TS.

  For example, a sensor for detecting the gas flow rate or pressure in the case 100 may be disposed in the space SP2. As shown in the above equation (3), when the steam reforming reaction and the shift reaction start to occur inside the case 100, the reaction gas (hydrogen and hydrogen) rather than the volume of the introduced gas (steam and raw material gas). The volume of carbon dioxide is larger. Such a change in volume is detected as an increase in flow rate or pressure in the case. That is, when the flow rate or pressure value detected by the sensor exceeds a predetermined threshold value (supposing that water vapor has reached the sensor position), the supply of the raw material gas from the second fuel supply device GS2 is started. What is necessary is just to be comprised so that it may be carried out.

  Similarly, a sensor that detects the concentration of any one of methane, water vapor, hydrogen, carbon dioxide, and carbon monoxide may be arranged inside the case 100, and the detection result of the sensor may be input to the control unit CU. The supply gas supply start timing from the second fuel supply device GS2 can be made appropriate.

  The delay time from the start of the supply of the raw material gas by the first fuel supply device GS1 to the start of the supply of the raw material gas by the second fuel supply device GS2 is determined in advance by an experiment or the like. This may be stored in the control unit CU. In this case, for example, from the required power generation amount, the temperature measured at a place other than the reformer 10 in the fuel cell device FC, the flow rate of water supplied to the evaporator EV (operation speed of the water supply pump), etc. An appropriate delay time is selected by the control unit CU. In such a configuration, it is not necessary to arrange a temperature sensor TU or the like inside the case 100.

  In the present embodiment, the ratio of the raw material gas supplied from the first fuel supply device GS1 and the raw material gas supplied from the second fuel supply device GS2 is set to 80:20. This ratio can be changed as appropriate. However, if the ratio of the raw material gas supplied from the first fuel supply device GS1 is reduced too much, the S is increased at all locations inside the reformer 10. Note that it is impossible to set / C to 3 or more.

  That is, the total amount of raw material gas (methane) supplied to the reformer 10 is not different from the conventional one, and the minimum amount of water vapor required for the water vapor reaction and shift reaction is also the same as the conventional one. The amount cannot be drastically reduced. According to the present invention, the amount of steam supplied can be reduced as described above, but the amount of steam additionally supplied to the reformer 10B can be reduced to 0 in order to prevent carbon deposition. This is the theoretical upper limit of the reduction amount.

  For example, when the ratio is 5:95, the amount of water vapor necessary to set the S / C value in the space SP1 to 3 is 5% of the conventional amount. However, if the supply amount of water vapor is reduced to 5%, the S / C value is certainly less than 2.5 on the downstream side of the space SP1, and carbon deposition occurs.

  According to a study by the present inventors, the target value of S / C in the space SP1 is set to 3, and the shift reforming rate (the rate at which CO is consumed by the shift reforming reaction in the reformer 10) is set. If 50% is assumed, the ratio of the raw material gas supplied from the first fuel supply device GS1 can be reduced to 67%. That is, the amount of water vapor supplied from the evaporator EV can be reduced to 67% of the conventional amount.

  Next, the configuration of the reformer 10A according to the second embodiment of the present invention and the fuel cell device FCA including the reformer will be described with reference to FIG. In the reformer 10A, a portion (a portion denoted by reference numeral 130) that partitions the space SP3 in the case 100A has a reduced diameter, and the mixing promoting portions 131, 132, and 133 are disposed in the space SP3. This is different from the reformer 10 in that respect. The other configuration of the reformer 10A is the same as that of the reformer 10.

  A portion (a portion having a reduced diameter) that divides the space SP3 in the case 100A is a cylindrical pipe. For this reason, the said part is described with the "connection piping part 130" below.

  All of the mixing promotion parts 131, 132, and 133 are flat plates arranged so as to be perpendicular to the direction in which water vapor flows. The mixing promotion unit 131 is disposed on the most upstream side (partition plate 112 side), the mixing promotion unit 133 is disposed on the most downstream side (partition plate 113 side), and the mixing promotion unit 132 is connected to the mixing promotion unit 131. It arrange | positions between the mixing promotion parts 133. FIG. The mixing promoting portions 131, 132, and 133 are arranged so as to partially overlap each other when viewed from above. For this reason, the mixed gas passing through the inside of the connection pipe portion 130 (that is, the space SP3) flows from the bottom to the top while colliding with the mixing promotion portions 131, 132, and 133 in order, as indicated by the arrow AR1. It will be.

  The opening OP <b> 3 is formed at a position on the lower side (upstream side) of the mixing promoting part 131 in the connection pipe part 130. For this reason, in the connection piping part 130, the mixed gas flowing in from the space SP2 and the raw material gas flowing in from the opening OP3 both flow while colliding with the mixing promoting parts 131, 132, and 133 in order. As a result, in the mixing promotion unit 131, the mixing of water vapor and the source gas is promoted. Since a part of the source gas additionally supplied from the opening OP3 flows into the space SP4 as it is, and the S / C value is prevented from being locally below 2.5, carbon deposition in the space SP4 is prevented. Can be more reliably prevented.

  In addition, as a mechanism for promoting the future of the additionally supplied raw material gas and water vapor, various configurations can be adopted instead of the mixing promotion units 131, 132, and 133 shown in FIG. For example, a mixer that spirals the gas flow path flowing from the lower side to the upper side may be arranged inside the connection pipe part 130. Moreover, it is good also as a structure where the nozzle was connected inside the opening OP3 so that the flow of the raw material gas introduced from the opening OP3 may form a swirl (swirl flow).

  In the present embodiment, the material gas is supplied to the case 100A from two locations (opening OP2 and opening OP3). However, the embodiment of the present invention need not be limited to two places, and the supply of the source gas is performed from three or more places having different heights (from three or more places having different positions along the direction in which water vapor flows). It is good also as an aspect called. By increasing the supply locations of the source gas, it is possible to prevent the S / C value from becoming excessively large in the case 100A. That is, the value of S / C can be set to about 3 in almost the entire space in case 100A. In this case, it is desirable to reduce the supply amount of the source gas from the upstream supply point to the downstream supply point. This is because the steam reforming reaction and the shift reaction occur efficiently as a result of increasing the chance that the raw material gas contacts the reforming catalysts RC1, RC2.

  The installation position of the sensor (temperature sensor TS in the present embodiment) for making the timing for starting the additional supply of the source gas from the downstream supply location appropriate is the most upstream supply location (opening OP2 in the present embodiment). ) And a position on the upstream side of the next supply location (opening OP3 in the present embodiment) is desirable. By installing the sensor at such a position, the timing at which the raw material gas starts to flow into the case 100A from the supply location can be matched with the timing at which the water vapor reaches the vicinity of the supply location. There may be a configuration in which a plurality of sensors are used instead of one, and one sensor is always installed between adjacent supply points.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

10, 10A, 10B: Reformers 100, 100A, 100B: Cases OP1, OP2, OP3, OP4: Openings 131, 132, 133: Mixing promotion parts GS1: First fuel supply device GS2: Second fuel supply device 21, 22, 31, 32, 41, 42, 51: Piping EV: Evaporator CU: Control device TS: Temperature sensor

Claims (7)

A reformer that generates hydrogen-containing gas by steam reforming,
A case (100, 100A) for accommodating the reforming catalyst (RC1, RC2);
Source gas supply means (GS1, GS2, 32, 42) for supplying source gas into the case;
Water vapor supply means (EV, 22) for supplying water vapor into the case;
A discharge means (51) for discharging the hydrogen-containing gas generated by the steam reforming reaction to the outside of the case,
The source gas supply means includes
A reformer configured to supply a raw material gas to the case from a plurality of supply points (OP2, OP3) having different positions along a direction in which water vapor flows.   2. The reformer according to claim 1, wherein the supply amount of the raw material gas from each of the supply points decreases from the upstream side toward the downstream side.   The reformer according to claim 2, wherein a mixing space (OP3) in which the reforming catalyst does not exist is formed at a position corresponding to the supply location in the case.   The reformer according to claim 3, wherein the mixing space is provided with a mixing promotion mechanism (131, 132, 133) for promoting mixing of the introduced water vapor and the raw material gas. . Detection means (TS) for detecting a state in the case;
5. A control means (CU) for controlling supply of the source gas from a supply location based on the state in the case detected by the detection means, further comprising: a control means (CU). The reformer according to any one of the above.   The reformer according to claim 5, wherein the detection unit detects a state upstream of the supply location on the downstream side of the case.   The reformer according to claim 5 or 6, wherein the detecting means detects a temperature of the reforming catalyst.

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