JP5636079B2 - Fuel cell power generation system - Google Patents

Description

The present invention relates to a fuel cell power generation system that includes a desulfurizer and a reformer and a fuel cell.

In recent years, a fuel cell power generation system that uses raw fuel gas such as city gas or LPG as a hydrogen raw material and generates electricity by an electrochemical reaction between the hydrogen raw material and oxygen in the air has attracted attention in terms of energy saving and environmental protection. ing. That is, in such a fuel cell power generation system, the chemical energy of the raw fuel gas is directly converted into electric energy by an electrochemical reaction, so that there is little loss caused by energy conversion and high power generation efficiency can be obtained. . In addition, water is the only substance produced with power generation, and the amount of nitrogen oxides (NOx) that cause air pollution is almost zero, and unit power generation compared to conventional thermal power generation The amount of carbon dioxide (CO ₂ ) emitted per hit can be reduced. Furthermore, the overall energy efficiency can be improved by effectively utilizing the exhaust heat accompanying power generation. Therefore, it is expected that fuel cell power generation systems will be widely used in the future.

  Incidentally, raw fuel gases such as city gas and LPG contain hydrocarbons such as methane and propane as main components. Therefore, when such raw fuel gas is used as a hydrogen raw material, the raw fuel gas is subjected to steam reforming by passing it through a reformer configured with a reforming catalyst such as ruthenium, for example. It is usual to obtain a simple gas. However, in general, a sulfur compound such as dimethyl sulfide (DMS) is mixed in city gas or LPG at a certain concentration as an odorant. Since such sulfur compounds as odorants degrade the performance by poisoning the reforming catalyst, the sulfur compounds are removed and reduced to the ppb order before the raw fuel gas flows into the reformer. There is a need. Therefore, the fuel cell power generation system includes a desulfurization device for removing the sulfur compound. The desulfurization apparatus is provided with a desulfurization agent that can adsorb and remove sulfur compounds such as zeolite.

  As an example of such a desulfurizing agent, Patent Document 1 below describes a desulfurizing adsorbent (hereinafter referred to as a silver zeolite adsorbent) in which silver is supported on a Y-type zeolite. In general, zeolite adsorbs moisture together with sulfur compounds. Therefore, when the moisture level (dew point) contained in the raw fuel gas increases, there is a problem that the performance of removing sulfur compounds by zeolite decreases. The silver zeolite adsorbent described in Patent Document 1 solves such a problem, and even if the moisture level contained in the raw fuel gas becomes high, it is possible to ensure the removal performance of the sulfur compound. Has been. Moreover, a desulfurization adsorbent containing zeolite as a main component, such as a silver zeolite adsorbent, is generally a room temperature desulfurization agent having an ability to adsorb sulfur compounds even at room temperature. Therefore, if a silver zeolite adsorbent as described in Patent Document 1 is used in the fuel cell power generation system, sulfur compounds in the raw fuel gas can be effectively removed by the desulfurization device at or near the normal temperature. As a result, the reforming apparatus, and thus the entire fuel cell power generation system, can be maintained in a good state simply and at low cost.

Japanese Patent Application Laid-Open No. 2002-066633

  However, although Patent Document 1 suggests that the silver zeolite adsorbent exhibits excellent desulfurization performance even when the moisture level contained in the raw fuel gas is high, basically the silver zeolite adsorbent itself. Is assumed to be in a state of being unsaturated and capable of exhibiting such desulfurization performance.

  On the other hand, today, a fuel cell power generation system is installed in each household and is operated so as to cover electric power demand and heat demand in the household. Such a fuel cell power generation system installed in each household naturally has a lifetime. And it is preferable that a desulfurization apparatus can be used for the lifetime, without replacing | exchanging a desulfurization agent if possible. Alternatively, it is preferable that the desired desulfurization capacity is maintained in the desulfurization apparatus by exchanging the desulfurization agent several times during the lifetime. In this respect, for example, if the vessel of the desulfurization apparatus is enlarged and a large amount of the desulfurization agent is accommodated in the vessel, it can be said that the number of exchanges can be suppressed as much as possible. However, for example, in a household fuel cell power generation system, there is a limit to the volume that can be occupied.

  These problems ultimately result in the problem of how high the performance of the desulfurizing agent can be maintained. However, for example, when considering a fuel cell power generation system used for home use, a substantially effective measure for solving the above problem has not been found so far.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a fuel cell power generation system in which the replacement of the desulfurization agent is unnecessary or can be performed a limited number of times over a predetermined lifetime. to.

According to the present invention, a desulfurization apparatus for removing sulfur compounds from a raw fuel gas containing a sulfur compound, and reforming of the raw fuel gas desulfurized by the desulfurization apparatus so as to contain hydrogen as a main component A characteristic configuration of a fuel cell power generation system including a reformer that generates gas and a fuel cell that generates power using the reformed gas supplied from the reformer as a fuel, the desulfurizer includes the original A desulfurization agent that adsorbs a sulfur compound is accommodated in a vessel provided with a fuel gas passing therethrough, and the desulfurization agent in the vessel when the raw fuel gas to be desulfurized flows is 50 ° C. A heating means for heating so as to obtain a heating state of ˜200 ° C., a moisture detection means provided on the upstream side of the container, for detecting a moisture level contained in the raw fuel gas flowing into the container, and the moisture detection To the means Ri and a heating control means for controlling the operation of said heating means in response to the moisture level detected, the desulfurizing agent is that it is zeolite-based adsorbent composed mainly of zeolite.

  As a desulfurization agent used in a desulfurization apparatus provided in a fuel cell power generation system, a desulfurization agent (hereinafter sometimes referred to as a normal temperature desulfurization agent) that can be used at normal temperature (for example, 0 ° C. to 30 ° C.) is known. Yes. Such a room temperature desulfurizing agent is preferably used in order to simplify the configuration of the entire fuel cell power generation system and to reduce the cost. By the way, at present, such a room temperature desulfurizing agent is often provided in the same casing as the fuel cell power generation system, and the temperature of the room temperature desulfurization agent during operation of the fuel cell power generation system may rise to about 40 ° C. Furthermore, depending on the relationship with the outside temperature, the temperature may be higher. However, it has not been considered to actively maintain the operating temperature of the room temperature desulfurization agent within a certain range.

  When using such a desulfurizing agent, the present inventors have clarified that such a room temperature desulfurizing agent has a unique temperature characteristic, and based on this, the present invention has been completed. Specifically, as a result of various studies, the present inventors have found that the desulfurization performance is significantly improved as the temperature of the room-temperature desulfurization agent is higher, particularly in a state where the moisture level contained in the raw fuel gas is high. I caught it. In addition, when the moisture level contained in the raw fuel gas is relatively low, the desulfurization performance is substantially constant, or even if the desulfurization performance decreases somewhat as the temperature of the room temperature desulfurization agent increases, the extent of the decrease is I found out that it was slight.

According to said characteristic structure, the desulfurization agent which can be normally used at normal temperature is positively heated with a heating means, and is made into the heating state of 50 to 200 degreeC. Therefore, even when the moisture level contained in the raw fuel gas is high, the desulfurization performance by the desulfurizing agent can be greatly improved. Note that when the moisture level contained in the raw fuel gas is relatively low, the desulfurization performance is substantially constant, or even if it is lowered, the degree of the reduction is slight. Therefore, comprehensively, the desulfurization performance by the desulfurizing agent can be improved. Further, since the desulfurization performance is improved, when the amount of the desulfurization agent accommodated in the container of the desulfurization apparatus is constant, the period during which the high desulfurization performance is maintained can be extended by that much.
In addition, when the desulfurizing agent is a zeolite-based adsorbent containing zeolite as a main component, a normal temperature desulfurizing agent capable of adsorbing a sulfur compound at normal temperature can be used simply and appropriately.
Accordingly, it is possible to provide a fuel cell power generation system that can replace the desulfurizing agent over a predetermined life period or can perform a limited number of times.

In addition , according to the study by the present inventors, in a state where the moisture level contained in the raw fuel gas is relatively low, even if the room-temperature desulfurization agent is continuously used at room temperature, the desulfurization is excellent enough for a long period of time. Performance can be demonstrated. Therefore, it is not necessary to heat the desulfurizing agent to make it warm. On the other hand, when the moisture level contained in the raw fuel gas is relatively high, if the room temperature desulfurizing agent is continuously used at room temperature as described above, it may not be possible to exhibit excellent desulfurization performance over a long period of time. Therefore, it can be said that it is highly necessary to heat the desulfurizing agent to make it warm.
According to this configuration, the heating control unit determines whether or not it is necessary to heat the desulfurizing agent based on the moisture level detected by the moisture detecting unit and to make the heating state, and according to the necessity or not. The operation of the heating means (presence or absence of heating) can be appropriately controlled.

  More specifically, the heating control means stops heating by the heating means when the moisture level detected by the moisture detection means is in a low humidity state lower than a predetermined reference level set in advance. When the moisture level detected by the moisture detection unit is in a high humidity state that is equal to or higher than a predetermined reference level set in advance, the heating unit is preferably configured to perform heating. is there.

According to this configuration, execution and stop of heating by the heating unit can be appropriately switched based on a predetermined reference level set in advance and a moisture level detected by the moisture detection unit.
Note that the predetermined reference level in this case can be set to a moisture level of 1000 to 4000 ppm (dew point is -20 to -5 ° C.) based on the experimental results, for example. Here, it is more preferable that the predetermined reference level is set to the minimum value of the moisture level range in which remarkable temperature characteristics appear in the room temperature desulfurization agent. Specifically, it is preferable to set the predetermined reference level to, for example, a moisture level of 4000 ppm (dew point is −5 ° C.).

  Here, it is preferable that the heating unit is configured to be able to heat the desulfurizing agent using exhaust heat discharged from the fuel cell as a heat source.

  According to this configuration, the desulfurization agent can be quickly and appropriately heated using the exhaust heat discharged from the fuel cell. Further, the exhaust heat exhausted from the fuel cell can be effectively used as a heat source for the heating means to heat the desulfurizing agent. Therefore, it is not necessary to separately install a heat source for heating the desulfurizing agent, so that the energy efficiency of the entire fuel cell power generation system can be improved.

  Preferably, the heating means includes a heat storage mechanism that recovers the exhaust heat and stores the recovered heat, and a heat supply mechanism that supplies heat stored by the heat storage mechanism to the container. It is.

  According to this configuration, depending on whether or not the desulfurizing agent needs to be heated, it is possible to appropriately switch between heat storage of exhaust heat discharged from the fuel cell and heating of the desulfurization agent using the stored heat. it can. That is, by storing the exhaust heat from the fuel cell in the heat storage device, the desulfurization agent can be quickly and appropriately heated using the stored heat as necessary.

  In addition, it is preferable that the fuel cell includes a non-power generation heating control unit that controls the heating unit to heat the desulfurization agent for a certain period of time after the fuel cell starts power generation or after power generation is stopped. is there.

According to this configuration, the desulfurizing agent can be heated by the heating unit and the temperature of the desulfurizing agent can be increased by the command from the non-power generation heating control unit before the fuel cell starts power generation. Therefore, before the reformer reforms the raw fuel gas to generate the reformed gas, a state in which the desulfurizing agent can exhibit high desulfurization performance can be created early. Even if the sulfur compound is desorbed while the temperature of the desulfurizing agent is decreasing after the fuel cell stops generating power, it is re-adsorbed and removed by the desulfurizing agent in the heated state. It becomes easy. Therefore, it is possible to suppress the sulfur compound in the raw fuel gas from reaching the reformer and the fuel cell as much as possible at the start of operation of the fuel cell power generation system.
Similarly, the desulfurizing agent can be heated by the heating unit even after the fuel cell has stopped generating power according to a command from the non-power generation heating control unit, and the temperature of the desulfurizing agent can be maintained in a warmed state for a certain period of time. . By the way, when the fuel cell power generation system is stopped, it is usually performed that gas is filled in the fuel cell in a state where power generation by the fuel cell is stopped, and the fuel cell is sealed in that state. At this time, even when the gas is supplied for sealing from the upstream side of the fuel cell power generation system by heating the desulfurization agent for a certain period of time and maintaining the heated state after the power generation stop by the fuel cell as described above. The desulfurization agent can be maintained in a state where high desulfurization performance can be exhibited. Therefore, when the power generation of the fuel cell is stopped, it is possible to suppress the sulfur compound from reaching the reformer and the fuel cell as much as possible.

  And a temperature detecting means for detecting the temperature of the desulfurizing agent; and after the heating by the heating means, the fuel cell after the desulfurizing agent is in the warmed state based on the temperature detected by the temperature detecting means. It is preferable to further include an activation control means for starting the power generation.

  According to this configuration, the heating control unit, the pre-power generation heating control unit, and the activation control unit cooperate to ensure that the desulfurization agent is warmed before the fuel cell starts power generation. Can do. Therefore, the fuel cell power generation system can be operated in a state where the desulfurization agent always maintains high desulfurization performance. Therefore, the state of the reformer and the fuel cell can be reliably maintained in a good state over a long period of time, and stable power generation can be performed.

  Further, the desulfurizing agent is preferably a silver zeolite adsorbent in which Y-type zeolite is a main component and silver is supported on the Y-type zeolite.

  According to this configuration, a room temperature desulfurization agent capable of adsorbing a sulfur compound at room temperature even when the moisture level contained in the raw fuel gas is high can be used simply and appropriately.

1 is a schematic configuration diagram of a fuel cell power generation system according to a first embodiment. It is a schematic block diagram of the heating means which concerns on 1st embodiment. It is a figure which shows the relationship between the dew point of raw fuel gas, and the relative adsorption amount of the sulfur compound by a desulfurization agent. It is a figure which shows the time-dependent change of the detection amount of the sulfur compound in the downstream of a desulfurizer. It is a figure which shows the relationship between the dew point of raw fuel gas, and the required amount of desulfurization agents. It is a flowchart which shows the process sequence of the starting control process which concerns on 1st embodiment. It is a flowchart which shows the process sequence of the heating control process which concerns on 1st embodiment. It is a schematic block diagram of the heating means which concerns on 2nd embodiment.

[First embodiment]
A first embodiment of the present invention will be described with reference to the drawings. The fuel cell power generation system S according to the present embodiment reforms the desulfurization apparatus D for removing sulfur compounds from the raw fuel gas P containing sulfur compounds, and the raw fuel gas P desulfurized by the desulfurization apparatus D. The reformer 3 that generates the reformed gas R containing hydrogen as a main component and the fuel cell 6 that generates electric power using the reformed gas R supplied from the reformer 3 as fuel are provided. In such a configuration, in the fuel cell power generation system S according to the present embodiment, the desulfurization apparatus D accommodates the desulfurization agent 1a that adsorbs the sulfur compound in the container C provided so that the raw fuel gas P can pass therethrough. And a heating means 21 for heating the desulfurization agent 1a in the container C so as to be in a heated state of 50 ° C to 200 ° C. Thereby, it is possible to make the replacement of the desulfurizing agent 1a unnecessary or limited over a predetermined lifetime. Hereinafter, the configuration of each part of the fuel cell power generation system S according to the present embodiment will be described in detail.

1. First, the overall configuration of the fuel cell power generation system S according to the present embodiment will be described. As shown in FIG. 1, the fuel cell power generation system S includes a desulfurization device D, a steam generator 2, a reformer 3, a carbon monoxide converter 4, a carbon monoxide remover 5, and a fuel cell 6. And as a main component.

  The desulfurization apparatus D removes sulfur compounds from the raw fuel gas P containing sulfur compounds. A raw fuel gas P mainly composed of hydrocarbons such as methane and propane is supplied to the desulfurization apparatus D. In the present embodiment, methane, propane or the like used as the raw fuel gas P is supplied in the form of city gas, LPG, or the like. City gas, LPG, and the like generally contain a sulfur compound such as dimethyl sulfide (DMS) as an odorant. The raw fuel gas P flows into the desulfurization device D through a gas flow rate adjusting valve 11 that adjusts the flow rate and a pump 13 that energizes the flow of the raw fuel gas P. The sulfur compound contained in the raw fuel gas P is adsorbed and removed by the desulfurization agent 1a provided in the desulfurization apparatus D. Thereby, the raw fuel gas P is desulfurized when passing through the desulfurization apparatus D. The raw fuel gas P desulfurized by the desulfurization apparatus D is supplied to the reformer 3. Details of the desulfurization apparatus D will be described later.

  The reformer 3 reforms the raw fuel gas P desulfurized by the desulfurization apparatus D to generate a reformed gas R mainly composed of hydrogen. In the present embodiment, the reformer 3 corresponds to the “reformer” in the present invention. The reformer 3 has a reforming catalyst (not shown) such as ruthenium, nickel, or platinum. Further, the reformer 3 is supplied in a form in which the steam generated by the steam generator 2 is mixed with the raw fuel gas P after the desulfurization treatment. The amount of water vapor mixed with the raw fuel gas P is adjusted by the water vapor flow rate control valve 12. The reformer 3 reforms the raw fuel gas P into a reformed gas R containing hydrogen, carbon monoxide, and carbon dioxide. When the raw fuel gas P is a gas mainly composed of methane, methane and water vapor are reformed by the following reaction formula to be reformed gas R containing hydrogen, carbon monoxide, and carbon dioxide. Quality processed.

[Chemical formula 1]
CH ₄ + H ₂ O → CO + 3H ₂
[Chemical formula 2]
CH ₄ + 2H ₂ O → CO ₂ + 4H ₂
The reformed gas R reformed by the reformer 3 is supplied to the carbon monoxide converter 4.

  The carbon monoxide converter 4 performs processing so as to reduce carbon monoxide contained in the reformed gas R reformed by the reformer 3. The carbon monoxide converter 4 includes a carbon monoxide conversion catalyst (not shown) such as iron-chromium or copper-zinc. In the carbon monoxide converter 4, the carbon monoxide and water vapor remaining in the reformed gas R generated in the reformer 3 are, for example, about 200 ° C. to 300 ° C. due to the catalytic action of the carbon monoxide conversion catalyst. The carbon monoxide is converted to carbon dioxide by the conversion reaction at the reaction temperature of the following reaction formula.

[Chemical formula 3]
CO + H ₂ O → CO ₂ + H ₂
The reformed gas R modified by the carbon monoxide transformer 4 is supplied to the carbon monoxide remover 5.

  The carbon monoxide remover 5 selectively oxidizes and removes carbon monoxide remaining in the reformed gas R that has been subjected to the transformation treatment by the carbon monoxide transformer 4. The carbon monoxide remover 5 has a carbon monoxide removal catalyst (not shown) such as ruthenium, platinum, palladium, or rhodium. In the carbon monoxide remover 5, the carbon monoxide remaining in the reformed gas R at the reaction temperature of about 100 ° C. to 200 ° C. is added in the air to which the carbon monoxide is removed by the catalytic action of the carbon monoxide removal catalyst. It is selectively oxidized by oxygen. As a result, a reformed gas R (fuel gas) rich in hydrogen monoxide having a low carbon monoxide concentration (for example, 10 ppm or less) is generated. The generated hydrogen-rich reformed gas R is supplied to the fuel cell 6.

  The fuel cell 6 generates power using the reformed gas R supplied from the reformer 3 as fuel. In the present embodiment, as described above, the reformed gas R supplied from the reformer 3 is in a hydrogen-rich state through the carbon monoxide converter 4 and the carbon monoxide remover 5. 6 performs power generation using the hydrogen-rich reformed gas R as a fuel. Such a fuel cell 6 includes various types such as a polymer electrolyte fuel cell (PEFC), a solid oxide fuel cell (SOFC), a phosphoric acid fuel cell (PAFC), and a molten carbonate fuel cell (MCFC). The system can be adopted. The fuel cell 6 is operated at a temperature higher than room temperature according to each method. In the present embodiment, a polymer electrolyte fuel cell (PEFC) is employed as the fuel cell 6, and the fuel cell 6 is operated at a temperature of 80 to 100 ° C. In the fuel cell 6 according to this embodiment, in the presence of a platinum catalyst, a reaction between the hydrogen-rich reformed gas R supplied from the carbon monoxide remover 5 and oxygen (air) supplied from the blower 14, DC power DC is taken out.

  The DC power DC generated and taken out by the fuel cell 6 is sent to the power converter 7. The power converter 7 converts the DC power DC into AC power AC having a predetermined frequency. The AC power AC is configured to be connected to a commercial power system and supplied to a power load (not shown) such as an electric device.

2. Configuration of Desulfurization Device Next, the configuration of the desulfurization device D will be described. The desulfurization apparatus D according to this embodiment includes a desulfurizer 1 and a heating means 21. The desulfurizer 1 performs a central function for removing sulfur compounds from the raw fuel gas P containing sulfur compounds. The desulfurizer 1 includes a container C (see FIG. 2), and a desulfurizing agent 1a that adsorbs a sulfur compound is accommodated in the container C. The container C is provided so that the raw fuel gas P can pass therethrough.

  In the present embodiment, the desulfurizing agent 1a is a zeolite-based adsorbent whose main component is zeolite. For example, X-type zeolite, Y-type zeolite and the like can be used. Such a zeolitic adsorbent is a kind of room temperature desulfurization agent that exhibits excellent adsorption performance for sulfur compounds at room temperature. Further, in the present embodiment, the desulfurizing agent 1a is a silver zeolite adsorbent in which Y-type zeolite is a main component and silver is supported on the Y-type zeolite. Even if such a silver zeolite adsorbent has a relatively high moisture level in the raw fuel gas P (dew point of the raw fuel gas P, the same applies hereinafter) (for example, a dew point of about −20 ° C.) Exhibits excellent adsorption performance for sulfur compounds.

  FIG. 3 is a graph showing the relative adsorption amount of the sulfur compound by the dew point of the raw fuel gas P and the desulfurizing agent 1a. As shown in this figure, the desulfurizing agent 1a is 100% of the sulfur compound contained in the raw fuel gas P when the moisture level contained in the raw fuel gas P is low (for example, when the dew point is -70 ° C). It has the ability to adsorb nearby. At this time, the desulfurization agent 1a is in a state where the performance can be sufficiently exhibited (that is, a state in which the amount of raw fuel gas P that can be desulfurized is large). However, the relative adsorption amount of the sulfur compound by the desulfurizing agent 1a has a relationship that decreases as the moisture level contained in the raw fuel gas P increases (the dew point increases). That is, when the moisture level contained in the raw fuel gas P increases, the amount of raw fuel gas P that can be desulfurized by the desulfurizing agent 1a decreases.

  FIG. 4 is a diagram showing temporal changes in the detected amount of sulfur compounds on the downstream side of the desulfurizer 1. As shown in this figure, when the moisture level contained in the raw fuel gas P is low (for example, when the dew point is −70 ° C.), the detected amount of sulfur compounds on the downstream side of the desulfurizer 1 is very small. The condition continues for a long time. On the other hand, when the moisture level contained in the raw fuel gas P increases (dew point increases), the performance of the desulfurizer 1 decreases in a very short period.

  FIG. 5 is a diagram showing the relationship between the dew point of the raw fuel gas P and the required amount of the desulfurizing agent 1a. As shown in this figure, the lower the moisture level contained in the raw fuel gas P (the lower the dew point), the smaller the required amount of the desulfurizing agent 1a, and the higher the moisture level contained in the raw fuel gas P (the higher the dew point). The required amount of desulfurization agent 1a increases. Here, paying attention to the fact that the desulfurization agent 1a used in the present embodiment is a silver zeolite adsorbent that exhibits excellent adsorption performance for sulfur compounds even at room temperature, normal temperature (here, Paying particular attention to the relationship between the dew point of the raw fuel gas P at 25 ° C. and the required amount of the desulfurizing agent 1a, when the dew point of the raw fuel gas P is less than −5 ° C., the dew point of the raw fuel gas P increases. It can be seen that the required amount of the desulfurizing agent 1a is gradually increased. On the other hand, when the dew point of the raw fuel gas P is −5 ° C. or higher, which is also a state in which the contained moisture level is very high, the required amount of the desulfurizing agent 1a increases rapidly as the dew point of the raw fuel gas P increases. It can be seen that it has increased. This is when the dew point of the raw fuel gas P is around −5 ° C. (the water level contained in the raw fuel gas P is about 4000 ppm) as a boundary and the state beyond the boundary value is continued for a long period of time. Means that the performance of the desulfurizer 1 may deteriorate in a relatively short period of time under the condition that the amount of the desulfurizing agent 1a provided in the desulfurizer 1 is constant.

  On the other hand, FIG. 5 shows the temperature of the desulfurizer 1 (that is, the temperature of the desulfurizing agent 1a) in addition to the relationship between the dew point of the raw fuel gas P and the required amount of the desulfurizing agent 1a at room temperature (here, 25 ° C.). The relationship between the dew point of the raw fuel gas P and the required amount of the desulfurizing agent 1a when the fuel is heated to a predetermined temperature is shown. Here, the temperature of the desulfurizing agent 1a is heated to 40 ° C., 50 ° C., 60 ° C., or 70 ° C. In FIG. 5, when the dew point of the raw fuel gas P is −40 ° C. and the temperature of the desulfurizing agent 1a is 25 ° C., the required amount of the desulfurizing agent 1a is “100”, and the desulfurizing agent in each state The required amount of 1a is calculated. In the case where the temperature of the desulfurization agent 1a was set to 70 ° C., only the case where the dew point of the raw fuel gas P was 20 ° C. was examined.

  As shown in this figure, it was found that the required amount of the desulfurizing agent 1a decreases as the temperature of the desulfurizing agent 1a increases. In other words, the higher the temperature of the desulfurizing agent 1a, the more greatly the desulfurizing performance of the desulfurizing agent 1a is improved. In particular, when the dew point of the raw fuel gas P increases rapidly as the dew point of the raw fuel gas P increases under normal temperature conditions, the dew point of the raw fuel gas P is in a state of −5 ° C. or higher. It has been found that the required amount of the desulfurizing agent 1a can be effectively reduced (the desulfurizing performance of the desulfurizing agent 1a can be greatly improved) as the temperature of the desulfurizing agent 1a is increased. On the other hand, when the dew point of the raw fuel gas P is less than −5 ° C., the required amount of the desulfurizing agent 1a slightly increases or becomes substantially constant as the temperature of the desulfurizing agent 1a is increased. I understood. Although the detailed mechanism is unknown, such a remarkable difference occurs when the dew point of the raw fuel gas P is around −5 ° C. The physical adsorption is dominant when the dew point is less than −5 ° C. On the other hand, it is considered that the chemical adsorption is dominant when the dew point is −5 ° C. or higher.

  In summary of these studies, when the dew point of the raw fuel gas P is at −5 ° C. or higher, the required amount of the desulfurizing agent 1a can increase rapidly as the dew point of the raw fuel gas P increases. It can be said that by increasing the temperature of the desulfurizing agent 1a, it is possible to keep the increase width relatively small. On the other hand, when the dew point of the raw fuel gas P is less than −5 ° C., the required amount of the desulfurizing agent 1a may increase as the temperature of the desulfurizing agent 1a is increased, but the increase width is slight. Therefore, it can be said that there is almost no problem from the viewpoint of performance deterioration of the desulfurizing agent 1a. Note that the present inventors consider that the volume of the container C is at an acceptable level and that the operation of the fuel cell power generation system S can be continued for a certain period (for example, 10 years) without replacing the desulfurizing agent 1a. An example of the necessary amount of the agent 1a is shown by a thin two-dot chain line in FIG. This corresponds to a level of about “1100”, where the necessary amount of the desulfurizing agent 1a when the dew point of the raw fuel gas P is −40 ° C. and the temperature of the desulfurizing agent 1a is 25 ° C. is “100”.

  Therefore, in the present application, the desulfurization apparatus D is configured to include the heating means 21. The heating means 21 heats the desulfurizing agent 1a accommodated in the container C. In the present embodiment, as described above, a silver zeolite adsorbent capable of adsorbing a sulfur compound at room temperature is employed as the desulfurizing agent 1a. Such a desulfurizing agent 1a is usually used at normal temperature (for example, 0 ° C. to 30 ° C.), but the heating means 21 is used to heat the desulfurizing agent 1a in the container C to a “warming state” of 50 ° C. to 200 ° C. Heat positively so that As a result, as is clear from the above examination, when the moisture level contained in the raw fuel gas P is high (the dew point of the raw fuel gas P is high), the required amount of the desulfurizing agent 1a is effectively reduced. Can do. Or when the quantity of the desulfurization agent 1a accommodated in the container C is made constant, the desulfurization performance can be maintained over a long period of time.

  Here, the reason why the desulfurization agent 1a in the container C is heated to 50 ° C. or higher is that the amount of the desulfurization agent 1a accommodated in the container C can be understood with reference to FIG. This is because it can be expected that the desulfurization agent 1a having a sufficient length can maintain a high desulfurization performance in view of the relationship between the long-term durability and the long-term durability. Referring to FIG. 5, it can be read that the desulfurization performance of the desulfurization agent 1 a can be greatly improved by heating the desulfurization agent 1 a to 60 ° C. or higher. It can be seen that 1a can maintain high desulfurization performance. Furthermore, it can be read that the desulfurization performance of the desulfurization agent 1a can be further greatly improved by heating the desulfurization agent 1a to 70 ° C. or higher. It can be seen that the performance can be maintained.

  On the other hand, the upper limit of the temperature for heating the desulfurizing agent 1a in the container C is set to 200 ° C. The reason why the zeolite which is the main component of the desulfurizing agent 1a in this embodiment is 200 ° C. or higher may cause thermal deterioration. Because there is sex. In the present embodiment, a polymer electrolyte fuel cell (PEFC) is adopted as the fuel cell 6 as described above, and the fuel cell 6 is operated at a temperature of 80 to 100 ° C. As will be described later, the heating means 21 heats the desulfurization agent 1a using the exhaust heat exhausted from the fuel cell 6 as a heat source. Therefore, in the present embodiment, the heating means 21 can heat the desulfurizing agent 1a to a temperature not higher than the operating temperature of the fuel cell 6, and actually the desulfurizing agent 1a is heated to 50 ° C to 80 ° C. Heat to warm.

  In the present embodiment, the heating means 21 is configured to be able to heat the desulfurizing agent 1a using the exhaust heat discharged from the fuel cell 6 as a heat source. In order to enable such a configuration, the fuel cell power generation system S includes an exhaust heat recovery mechanism 22 that recovers exhaust heat exhausted from the fuel cell 6, as shown in FIG. The exhaust heat recovery mechanism 22 is a mechanism for recovering exhaust heat exhausted from the fuel cell 6 and supplying the recovered heat to the desulfurization agent 1a. The exhaust heat recovery mechanism 22 includes a heat exchanger 23 for causing heat exchange between the exhaust gas from the fuel cell 6 and the exhaust heat recovery water flowing through the exhaust heat recovery circuit 27. By operating the pump 25, the exhaust heat recovery water flowing through the exhaust heat recovery circuit 27 exchanges heat with the exhaust gas from the fuel cell 6 in the heat exchanger 23. The exhaust heat recovery water heated when passing through the heat exchanger 23 is supplied to the desulfurizer 1 (desulfurizing agent 1a in the container C) to heat the desulfurizing agent 1a. The exhaust heat recovery water after heating the desulfurizing agent 1 a is stored in the hot water storage tank 24. That is, the recovered heat is stored in the form of the amount of heat that the exhaust heat recovery water stored in the hot water storage tank 24 has.

  The hot water storage tank 24 is configured as a so-called temperature stratification type in which hot water is stored in a form in which high temperature hot water stays in the upper part and low temperature hot water stays in the lower part of the high temperature layer. In the present embodiment, the relatively high temperature exhaust heat recovery water after heating the desulfurizing agent 1 a is supplied in the vicinity of the upper end of the hot water storage tank 24. When the pump 25 is operated, relatively high-temperature hot water is supplied to the heat exchanger 23 as exhaust heat recovery water from the high-temperature layer staying at the upper end of the hot water storage tank 24. By repeating the above operation, it is possible to recover the exhaust heat discharged from the fuel cell 6 and to heat the desulfurizing agent 1a. Even before the fuel cell 6 starts power generation, the desulfurizing agent 1a is heated by supplying relatively high-temperature hot water staying at the upper end of the hot water storage tank 24 to the desulfurizing agent 1a in the container C. Is possible. That is, the heat stored in the form of the amount of heat of the exhaust heat recovery water in the hot water storage tank 24 is supplied to the desulfurization agent 1a in the container C. Therefore, in the present embodiment, the exhaust heat recovery mechanism 22 functions as both the “heat storage mechanism” and the “heat supply mechanism” in the present invention.

  In this embodiment, the recovered heat is further supplied to the heat load 26. That is, the relatively high temperature hot water staying at the upper end of the hot water storage tank 24 is further supplied to the heat load 26. Thus, the overall energy efficiency of the fuel cell power generation system S is improved by effectively using the exhaust heat accompanying the power generation of the fuel cell 6. The exhaust heat recovery mechanism 22 is also preferably configured to include a backup heater for heating the hot water supplied from the hot water storage tank 24. In this way, when hot water is supplied from the hot water storage tank 24 to the desulfurizing agent 1a and the heat load 26, the hot water is not supplied to the temperature required by the desulfurizing agent 1a and the heat load 26. It can be heated appropriately.

  In the desulfurization apparatus D according to the present embodiment, the desulfurization agent 1a accommodated in the container C is heated to 50 ° C. to 200 ° C. by the heating means 21 as described above. Thereby, it is possible to maintain the desulfurization performance satisfactorily for a long time in the desulfurization agent 1a. As a result, it is possible to make the replacement of the desulfurizing agent 1a unnecessary or limited over a predetermined lifetime.

  In addition, since the desulfurization performance of the desulfurization agent 1a is maintained well over a long period of time, the reforming catalyst of the reformer 3 provided in the fuel cell power generation system S in which the desulfurization device D is incorporated is, for example, DMS. It is also possible to effectively suppress the deterioration due to poisoning by the sulfur compound over a long period of time. Therefore, since the state of the reformer 3 and the fuel cell 6 is maintained in a good state for a long time, the fuel cell power generation system S according to the present embodiment can stably generate power for a long time. It is possible.

3. Next, the configuration of the control device 30 will be described. As shown in FIG. 1, the control device 30 provided in the fuel cell power generation system S functions as a core member that controls the operation of each part of the fuel cell power generation system S. The desulfurization control unit 31, the system control unit 36, Each functional part is configured. In the present embodiment, the desulfurization control unit 31 includes a heating control unit 32, and the system control unit 36 includes a pre-power generation heating control unit 37, a startup control unit 38, and a post-stop heating control unit 39. Further, the control device 30 includes an arithmetic processing unit such as a CPU as a core member, and from a RAM (random access memory) configured to be able to read and write data from the arithmetic processing unit, and an arithmetic processing unit. It has a storage device such as a ROM (Read Only Memory) configured to be able to read data (not shown). Each functional unit of the control device 30 is configured by software (program) stored in a ROM or the like, hardware such as a separately provided arithmetic circuit, or both. Each functional unit is configured to be able to exchange information with each other.

  In addition, the fuel cell power generation system S includes a plurality of sensors, specifically a dew point sensor Se1 and a temperature sensor Se2, provided in each part in the system. The dew point sensor Se <b> 1 is provided in the supply path of the raw fuel gas P on the upstream side of the container C. The dew point sensor Se1 is a sensor that detects the dew point of the raw fuel gas P flowing into the container C, and can be realized using, for example, a capacitance type dew point meter. The dew point of the raw fuel gas P is information representing the moisture level contained in the raw fuel gas P. Therefore, in the present embodiment, the dew point sensor Se1 corresponds to the “moisture detection means” in the present invention. The temperature sensor Se2 is provided in the vicinity of the container C. This temperature sensor Se2 is a sensor that detects the temperature of the desulfurizing agent 1a accommodated in the container C, and uses a non-contact thermometer such as a radiation thermometer, a contact thermometer such as a surface thermometer, and the like. realizable. In the present embodiment, the temperature sensor Se2 corresponds to the “temperature detection means” in the present invention. Information indicating the detection results by the dew point sensor Se1 and the temperature sensor Se2 is output to the control device 30. Below, the detail of each function part of the control apparatus 30 is demonstrated.

The desulfurization control unit 31 is a functional unit that controls the operation of the desulfurization device D provided in the fuel cell power generation system S. The desulfurization control unit 31 further includes a heating control unit 32 as a lower functional unit. The heating control unit 32 is a functional unit that controls the operation of the heating unit 21. In the present embodiment, the heating control unit 32 is configured to control the operation of the heating unit 21 according to the dew point of the raw fuel gas P detected by the dew point sensor Se1. More specifically, the heating control unit 32 determines whether the raw fuel gas P is in a low humidity state or a high humidity state based on the dew point of the raw fuel gas P detected by the dew point sensor Se1. The operation of the heating means 21 is controlled according to the state of the raw fuel gas P (low humidity state or high humidity state).

  Here, when determining the state of the raw fuel gas P, a predetermined reference temperature Ts is set in advance. When the dew point detected by the dew point sensor Se1 is lower than the reference temperature Ts, the raw fuel gas P is assumed to be in a “low humidity state”, while the dew point detected by the dew point sensor Se1 is the reference temperature. When the temperature is equal to or higher than Ts, the raw fuel gas P is assumed to be in a “high humidity state”. Such a predetermined reference temperature Ts can be set to a moisture level such as 1000 to 4000 ppm (dew point is −20 to −5 ° C.) based on the experimental results described above. In the present embodiment, the required amount of the desulfurizing agent 1a increases rapidly as the dew point of the raw fuel gas P increases under such conditions that the temperature of the desulfurizing agent 1a is normal temperature as the predetermined reference temperature Ts. The boundary temperature “−5 ° C.” is set (see FIG. 5).

  In the present embodiment, when the raw fuel gas P is in a low humidity state, the heating control unit 32 controls to stop the heating of the desulfurizing agent 1a by the heating means 21. This is because when the raw fuel gas P is in a low humidity state, even if the temperature of the desulfurizing agent 1a is increased by heating the desulfurizing agent 1a by the heating means 21, the desulfurization performance by the desulfurizing agent 1a hardly changes. Rather, it may decrease slightly. On the other hand, when the raw fuel gas P is in a high humidity state, the heating control unit 32 performs control so that the heating of the desulfurizing agent 1a by the heating unit 21 is performed. This is because when the raw fuel gas P is in a high humidity state, the desulfurizing agent 1a is heated by the heating means 21 to raise the temperature of the desulfurizing agent 1a, thereby greatly improving the desulfurizing performance of the desulfurizing agent 1a. Because it can. By greatly improving the desulfurization performance of the desulfurizing agent 1a, the required amount of the desulfurizing agent 1a can be effectively reduced. Or when the quantity of the desulfurization agent 1a accommodated in the container C is made constant, the desulfurization performance can be maintained over a long period of time. As a result, the desulfurization agent 1a does not need to be replaced over a predetermined life period or can be replaced a limited number of times, and the fuel cell power generation system S can stably generate power over a long period of time.

  As described above, in the present embodiment, the fuel cell power generation system S includes the exhaust heat recovery mechanism 22 that recovers exhaust heat exhausted from the fuel cell 6, and a hot water storage tank provided in the exhaust heat recovery mechanism 22. The high temperature hot water stored in 24 is supplied to the desulfurization agent 1a in the container C, so that the desulfurization agent 1a can be heated. Therefore, in the present embodiment, the heating control unit 32 switches the operation of the pump 25 (on / off of the pump 25) provided in the exhaust heat recovery circuit 27 of the exhaust heat recovery mechanism 22 to thereby heat the desulfurizing agent 1a. Control execution or stop switching. In the present embodiment, the heating control unit 32 corresponds to the “heating control means” in the present invention.

  In the present embodiment, the exhaust heat recovery mechanism 22 is configured to recover the exhaust heat discharged from the fuel cell 6 regardless of the dew point of the raw fuel gas P. Therefore, with the exhaust heat recovery operation by the exhaust heat recovery mechanism 22, the desulfurization agent 1a may be heated regardless of the dew point of the raw fuel gas P. However, it should be noted that such operation is not due to the “heating control means” of the present invention.

The system control unit 36 is a functional unit that controls the operation of the entire fuel cell power generation system S in cooperation with the desulfurization control unit 3 1. The system control unit 36 further includes a pre-power generation heating control unit 37, an activation control unit 38, and a post-stop heating control unit 39 as subordinate functional units.

  The pre-power generation heating control unit 37 is a functional unit that controls the operation of the heating unit 21 before the fuel cell 6 starts power generation. The pre-power generation heating control unit 37 controls the heating means 21 to heat the desulfurizing agent 1a for a certain time before the fuel cell 6 starts power generation. As the “certain time” at this time, an arbitrary time can be set, for example, 1 to 10 [minutes] or the like. Or it is good also as time until the temperature of the desulfurization agent 1a becomes more than predetermined temperature, for example, without setting it as fixed time. In the present embodiment, the latter is adopted. In the present embodiment, the pre-power generation heating control unit 37 heats the desulfurizing agent 1 a by operating the pump 25 provided in the exhaust heat recovery circuit 27 of the exhaust heat recovery mechanism 22. In the present embodiment, the pre-power generation heating control unit 37 constitutes a part of the “non-power generation heating control means” in the present invention.

  The activation control unit 38 is a functional unit that controls the activation operation of the fuel cell 6. The activation control unit 38 controls the fuel cell 6 to start power generation after the desulfurizing agent 1a is heated based on the detection result of the temperature sensor Se2 after heating by the heating unit 21. Here, as already explained above, in this embodiment, the “warming state” of the desulfurizing agent 1a means that the temperature of the desulfurizing agent 1a is in a state of 50 ° C. to 200 ° C. Therefore, the start control unit 38 gradually increases the temperature of the desulfurization agent 1a by the cooperation of the pre-power generation heating control unit 37 and the heating means 21 before the fuel cell 6 starts power generation, and the temperature sensor Se2. When the detected temperature of the desulfurizing agent 1a eventually reaches 50 ° C., an activation signal is output to the fuel cell 6 to cause the fuel cell 6 to start power generation. In the present embodiment, the activation control unit 38 corresponds to “activation control means” in the present invention.

  The post-stop heating control unit 39 is a functional unit that controls the operation of the heating means 21 after the fuel cell 6 stops power generation. The post-stop heating control unit 39 controls the heating means 21 to heat the desulfurizing agent 1a for a predetermined time based on the detection result of the temperature sensor Se2 after the power generation by the fuel cell 6 is stopped. As the “certain time” at this time, an arbitrary time can be set, for example, 1 to 30 [minutes] or the like. Or it is good also as time until the temperature of the desulfurization agent 1a becomes below predetermined temperature, for example, without setting it as fixed time. In the present embodiment, the post-stop heating control unit 39 heats the desulfurizing agent 1 a by operating the pump 25 provided in the exhaust heat recovery circuit 27 of the exhaust heat recovery mechanism 22. In the present embodiment, the post-stop heating control unit 39 constitutes a part of the “non-power generation heating control means” in the present invention.

  In the present embodiment, by providing the pre-power generation heating control unit 37, the temperature of the desulfurization agent 1a can be increased before the fuel cell 6 starts power generation. Therefore, before the reformer 3 reforms the raw fuel gas P to generate the reformed gas R, the desulfurization agent 1a provided in the desulfurization apparatus D can be in a state where it can exhibit high desulfurization performance at an early stage. Can be produced. Even if the sulfur compound is desorbed while the fuel cell 6 stops generating power and the temperature of the desulfurizing agent 1a is decreasing, it is re-adsorbed by the heated desulfurizing agent 1a. It becomes easy to remove. Therefore, in the fuel cell power generation system S according to the present embodiment, the reforming catalyst provided in the reformer 3 is poisoned by sulfur compounds such as DMS contained in the raw fuel gas P and causes performance deterioration. It can be suppressed more effectively.

  Furthermore, in the present embodiment, since the start control unit 38 is provided, the start control unit 38, the pre-power generation heating control unit 37, and the heating means 21 cooperate to cause the fuel cell 6 to start power generation. Before, the desulfurization agent 1a with which the desulfurization apparatus D was equipped can be reliably made into the heating state of 50 degreeC or more. Therefore, the fuel cell power generation system S can be operated in a state where the desulfurizing agent 1a always maintains high desulfurization performance. Accordingly, the fuel cell power generation system S can stably generate power by reliably maintaining the reformer 3 and the fuel cell 6 in a good state over a long period of time.

  Further, in the present embodiment, by providing the post-stop heating control unit 39, the temperature of the desulfurization agent 1a can be maintained at a relatively high state for a certain period of time even after the fuel cell 6 stops power generation. . By the way, when the fuel cell power generation system S is stopped, it is usually performed to fill the fuel cell 6 with gas while the power generation by the fuel cell 6 is stopped, and to seal the fuel cell 6 in that state. At this time, the gas is supplied for sealing from the upstream side of the fuel cell power generation system S by heating the desulfurizing agent 1a for a certain period of time and maintaining the heated state after the power generation is stopped by the fuel cell 6 as described above. Even in this case, the desulfurization agent 1a can be maintained in a state where high desulfurization performance can be exhibited. Therefore, it is possible to suppress the sulfur compound from reaching the reformer 3 and the fuel cell 6 as much as possible when the power generation of the fuel cell 6 is stopped.

  The control device 30 is also configured to control the opening of the gas flow rate control valve 11 and the steam flow rate control valve 12, the operation of the pump 13, the operation of the blower 14, the operation of the power converter 7, and the like. .

4). Procedure of Control Process of Fuel Cell Power Generation System Next, the content of the control process of the fuel cell power generation system S by the control device 30 according to the present embodiment will be described. In the following, a startup control process that is a control process before the fuel cell 6 provided in the fuel cell power generation system S starts power generation, and a heating control that is a control process for the desulfurization apparatus D provided in the fuel cell power generation system S. The process will be described separately. The procedure of the startup control process and the heating control process described below is executed by each functional unit of the control device 30.

4-1. Processing procedure of activation control processing First, the processing procedure of activation control processing will be described. FIG. 6 is a flowchart showing a processing procedure of the startup control process in the fuel cell power generation system S according to the present embodiment. In the startup control process, when there is a power generation request for the fuel cell 6 (step # 01: Yes), the pre-power generation heating control unit 37 first causes the heating means 21 to heat the desulfurizing agent 1a (step # 02). . In the present embodiment, the pre-power generation heating control unit 37 operates the pump 25 provided in the exhaust heat recovery circuit 27 of the exhaust heat recovery mechanism 22 to supply hot water stored in the hot water storage tank 24 to the container C. The desulfurizing agent 1a is heated by heat exchange between the hot water and the desulfurizing agent 1a. Next, the activation control unit 38 acquires the temperature of the desulfurizing agent 1a detected by the temperature sensor Se2 (step # 03). The activation control unit 38 determines whether or not the desulfurizing agent 1a is in a heated state based on the acquired temperature of the desulfurizing agent 1a (step # 04).

  When it is determined that the desulfurizing agent 1a has not reached the warmed state, that is, when it is determined that the temperature of the desulfurizing agent 1a is less than 50 ° C. (step # 04: No), the heating means 21 continues. The desulfurizing agent 1a is heated, and the process of step # 04 is performed again. Eventually, when it is determined that the desulfurizing agent 1a has reached the warmed state, in this example, when it is determined that the temperature of the desulfurizing agent 1a has reached 50 ° C. or higher (step # 04: Yes), the activation control unit 38 Then, the fuel cell 6 is caused to start power generation (step # 05). Thus, the activation control process ends.

4-2. Processing procedure of heating control process Next, a processing procedure of the heating control process will be described. FIG. 7 is a flowchart showing the procedure of the heating control process in the fuel cell power generation system S according to this embodiment. In the heating control process, first, the heating control unit 32 acquires the dew point of the raw fuel gas P detected by the dew point sensor Se1 (step # 21). The heating control unit 32 determines whether or not the raw fuel gas P is in a high humidity state based on the acquired dew point of the raw fuel gas P (step # 22).

  When it is determined that the raw fuel gas P is in a high humidity state, that is, when it is determined that the dew point of the raw fuel gas P is equal to or higher than a preset reference temperature Ts (−5 ° C. in this example). (Step # 22: Yes), the heating controller 32 causes the heating means 21 to heat the desulfurizing agent 1a (Step # 23). In the present embodiment, the heating control unit 32 heats the desulfurizing agent 1 a by operating the pump 25 provided in the exhaust heat recovery circuit 27 of the exhaust heat recovery mechanism 22, similarly to the pre-power generation heating control unit 37. On the other hand, when it is determined that the raw fuel gas P is in a low humidity state, that is, when it is determined that the dew point of the raw fuel gas P is lower than a preset reference temperature Ts (in this example, −5 ° C.). (Step # 22: No), the heating control unit 32 stops the heating of the desulfurizing agent 1a by the heating means 21 (Step # 24). In the present embodiment, the heating control unit 32 stops the heating of the desulfurizing agent 1 a by stopping the pump 25. The processes of steps # 21 to # 24 described above are sequentially repeated while power generation by the fuel cell 6 is being performed (step # 25: No).

  When the power generation by the fuel cell 6 is stopped (step # 25: Yes), the post-stop heating control unit 39 is based on the dew point of the raw fuel gas P acquired at the latest step # 21, and the raw fuel at that time It is determined whether or not the gas P is in a high humidity state (step # 26). Specific determination contents are the same as those in step # 22. When it is determined that the raw fuel gas P is in a low humidity state (step # 26: No), since the heating of the desulfurizing agent 1a by the heating means 21 has already been stopped in step # 24, the heating control process is performed as it is. finish. On the other hand, when it is determined that the raw fuel gas P is in a high humidity state (step # 26: Yes), the heating of the desulfurizing agent 1a by the heating means 21 executed in step # 23 is continued and after the stop The heating control unit 39 determines whether or not a predetermined time has elapsed (step # 27). Thereafter, when a predetermined time has elapsed (step # 27: Yes), the post-stop heating control unit 39 stops heating the desulfurizing agent 1a by the heating means 21 (step # 28). In the present embodiment, the post-stop heating control unit 39 stops the heating of the desulfurizing agent 1a by stopping the pump 25 provided in the exhaust heat recovery circuit 27 of the exhaust heat recovery mechanism 22. Above, a heating control process is complete | finished.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the configuration of the heating means 21 provided in the desulfurization device D of the fuel cell power generation system S is partially different from the configuration of the heating means 21 in the first embodiment. Other configurations are the same as those in the first embodiment. Hereinafter, the fuel cell power generation system S according to the present embodiment will be described mainly focusing on differences from the first embodiment.

  As in the first embodiment, the heating means 21 is configured to be able to heat the desulfurizing agent 1a using exhaust heat discharged from the fuel cell 6 as a heat source. However, in the present embodiment, the desulfurization agent 1a is indirectly installed through the exhaust heat recovery water circulating in the exhaust heat recovery mechanism 22 in that the desulfurization agent 1a is installed so as to be able to exchange heat directly with the fuel cell 6. The desulfurizing agent 1a is different from the first embodiment in which heat exchange with the fuel cell 6 is possible. That is, in the present embodiment, as shown in FIG. 8, the container C that stores the desulfurizing agent 1 a and the main body of the fuel cell 6 are installed in a state where they face each other close to each other, The desulfurization agent 1a can be heated only through the container C by the heat of the main body of the fuel cell 6. In this case, it is preferable that the container C is configured using a material having high thermal conductivity. In the present embodiment, a polymer electrolyte fuel cell (PEFC) is adopted as the fuel cell 6, and the main body of the fuel cell 6 can reach its operating temperature of 80 to 100 ° C. Accordingly, the desulfurizing agent 1a can be heated to at least about 80 ° C. Therefore, the heating means 21 according to the present embodiment brings the desulfurizing agent 1a to a relatively high temperature of 70 to 80 ° C. during the steady operation of the fuel cell 6. Such a temperature is considerably high when viewed from room temperature.

  By the way, in this embodiment, since the container C and the main body of the fuel cell 6 are only installed in a state of being close to each other and facing each other, the fuel cell 6 is continuously generating electric power during steady operation. The desulfurizing agent 1a can be easily heated via the container C, but the main body is sufficiently warmed before the fuel cell 6 generates power or immediately after the fuel cell 6 starts generating power. In some cases, the desulfurizing agent 1a cannot be heated sufficiently. Therefore, in the present embodiment, the heating means 21 is further provided with an electric heater (not shown) for directly heating the desulfurizing agent 1a accommodated in the container C. In the start-up control process, the pre-power generation heating control unit 37 (see FIG. 1) controls the electric heater so that the desulfurizing agent 1a is heated by the electric heater for a certain period of time before the fuel cell 6 starts generating electric power. To do.

  Further, in the configuration of the heating means 21 according to the present embodiment, since the desulfurizing agent 1a is maintained in a state in which heat exchange with the fuel cell 6 is always possible, the heating means 21 according to the dew point of the raw fuel gas P. The operation (execution or stop of heating of the desulfurizing agent 1a) cannot be switched. That is, the heating means 21 according to the present embodiment heats the desulfurizing agent 1a to be always in a warmed state regardless of the dew point of the raw fuel gas P. Therefore, the control device 30 is not provided with the heating control unit 32 as described in the first embodiment. However, even in this case, the heating means 21 can desulfurize the desulfurizing agent 1a at a relatively high temperature of 70 to 80 ° C. during the steady operation of the fuel cell 6 at least as described above. The agent 1a can maintain its desulfurization performance well over a long period of time. Therefore, also in the present embodiment, replacement of the desulfurizing agent 1a is not required or can be performed a limited number of times over a predetermined lifetime. Moreover, since the desulfurization performance of the desulfurization agent 1a is maintained well over a long period of time, the state of the reformer 3 and the fuel cell 6 is also maintained in a good state over a long period of time. Accordingly, the fuel cell power generation system S according to the present embodiment can generate power stably over a long period of time with a very simple configuration.

[Other Embodiments]
(1) In the first embodiment, the control device 30 includes the heating control unit 32, and the heating control unit 32 is configured to control the operation of the heating unit 21 according to the dew point of the raw fuel gas P. The case has been described as an example. However, the embodiment of the present invention is not limited to this. That is, in the first embodiment, as in the second embodiment, the heating means 21 always keeps the desulfurizing agent 1a in a heated state regardless of the dew point (moisture level) of the raw fuel gas P. A heating configuration is also one of the preferred embodiments of the present invention.

(2) In the first embodiment, as an example, “−5 ° C.” is set as the reference temperature Ts for determining the state (low humidity state or high humidity state) of the raw fuel gas P. explained. However, the embodiment of the present invention is not limited to this. That is, such setting of the reference level Ts is merely an example, and other temperatures such as “−20 ° C.”, “−15 ° C.”, “−10 ° C.”, etc. can be set as the reference temperature Ts. is there.

(3) In the above embodiment, the case where the heating unit 21 is configured to be able to heat the desulfurization agent 1a using the exhaust heat discharged from the fuel cell 6 as a heat source has been described as an example. However, the embodiment of the present invention is not limited to this. That is, it is also one of preferred embodiments of the present invention that the heating means 21 is constituted by a dedicated heater or the like that is unrelated to the exhaust heat discharged from the fuel cell 6, for example.

(4) In each of the above embodiments, the case where the heating unit 21 directly heats the desulfurization agent 1a in the container C has been described as an example. However, the embodiment of the present invention is not limited to this. That is, for example, a configuration in which the desulfurizing agent 1 a in the container C is indirectly heated by heating the raw fuel gas P by the heating unit 21 is also one of the preferred embodiments of the present invention.

(5) In the above embodiments, the case where a polymer electrolyte fuel cell (PEFC) is used as the fuel cell 6 has been described as an example. However, the embodiment of the present invention is not limited to this. That is, various types of systems other than this can be adopted, and it is also preferable to configure the fuel cell power generation system S using, for example, a solid oxide fuel cell (SOFC). In this case, since the fuel cell 6 is operated at a temperature of 800 to 1000 ° C., the desulfurization agent 1a is installed so as to be able to directly exchange heat with the fuel cell 6 as in the second embodiment. In the case of adopting the above-described configuration, for the purpose of preventing thermal degradation of the desulfurizing agent 1a, a configuration including a heat insulating member interposed between the container C housing the desulfurizing agent 1a and the main body of the fuel cell 6; It is preferable. In this case, the material constituting the heat insulating member, the thickness thereof, and the like are preferably set so that the temperature of the desulfurizing agent 1a can be suppressed to 200 ° C. or less even when heat is transferred from the main body of the fuel cell 6.

(6) In the above embodiment, a case where a silver zeolite adsorbent, which is a kind of room temperature desulfurization agent that exhibits excellent adsorption performance for sulfur compounds at room temperature, is used as the desulfurization agent 1a will be described as an example. did. However, the embodiment of the present invention is not limited to this. That is, any material that exhibits excellent adsorption performance for sulfur compounds at least at room temperature is suitable, and other room temperature desulfurization agents can naturally be used.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for a fuel cell power generation system in which raw fuel gas such as city gas or LPG is used as a hydrogen raw material and power is generated by an electrochemical reaction between the hydrogen raw material and oxygen in the air.

1a Room temperature desulfurization agent (desulfurization agent)
3 Reformer (reformer)
6 Fuel cell 21 Heating means 22 Waste heat recovery mechanism (heat storage mechanism, heat supply mechanism)
32 Heating control unit (heating control means)
37 Heating control unit before power generation (heating control means during non-power generation)
38 Start Control Unit (Start Control Unit)
39 Heating control unit after stopping (heating control means during non-power generation)
S Fuel cell power generation system D Desulfurization device C Container P Raw fuel gas R Reformed gas Se1 Dew point sensor (moisture detection means)
Se2 temperature sensor (temperature detection means)

Claims (7)

A desulfurizer for removing sulfur compounds from raw fuel gas containing sulfur compounds;
A reformer that reforms the raw fuel gas desulfurized by the desulfurizer to generate a reformed gas mainly composed of hydrogen;
A fuel cell power generation system comprising: a fuel cell that generates electricity using the reformed gas supplied from the reformer as a fuel;
The desulfurization apparatus accommodates a desulfurization agent that adsorbs a sulfur compound inside a container provided so that the raw fuel gas can pass therethrough,
Heating means for heating the desulfurization agent in the vessel when the raw fuel gas to be desulfurized flows into a heated state of 50 ° C to 200 ° C ;
A moisture detecting means provided on the upstream side of the container for detecting the moisture level contained in the raw fuel gas flowing into the container;
Heating control means for controlling the operation of the heating means according to the moisture level detected by the moisture detection means ,
The fuel cell power generation system, wherein the desulfurizing agent is a zeolite-based adsorbent mainly composed of zeolite. The heating control means includes
When the moisture level detected by the moisture detection means is in a low humidity state lower than a predetermined reference level set in advance, control to stop heating by the heating means,
2. The fuel cell power generation according to claim 1, wherein when the moisture level detected by the moisture detection unit is in a high humidity state that is equal to or higher than a predetermined reference level set in advance, the fuel cell power generation is controlled to perform heating by the heating unit. system. 3. The fuel cell power generation system according to claim 1, wherein the heating unit is configured to be able to heat the desulfurization agent using exhaust heat discharged from the fuel cell as a heat source. 4. The said heating means is equipped with the heat storage mechanism which collect | recovers the said exhaust heat, and stores the collect | recovered heat | fever, and the heat supply mechanism which supplies the heat | fever stored by the said heat storage mechanism to the said container. Fuel cell power generation system. 5. The non-power generation heating control means for controlling the heating means to heat the desulfurization agent for a certain period of time after the fuel cell starts power generation or after power generation is stopped. A fuel cell power generation system according to claim 1. Temperature detecting means for detecting the temperature of the desulfurizing agent;
An activation control means for causing the fuel cell to start power generation after the desulfurization agent is in the warmed state based on the temperature detected by the temperature detection means after heating by the heating means;
The fuel cell power generation system according to any one of claims 1 to 5, further comprising: The fuel cell power generation system according to any one of claims 1 to 6, wherein the desulfurization agent is a silver zeolite adsorbent in which Y-type zeolite is a main component and silver is supported on the Y-type zeolite.

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