JP6661564B2 - Power generation system - Google Patents

Description

  The present invention relates to a power generation system.

  In recent years, carbon-neutral biofuels have attracted attention as an alternative to petroleum fuels. Among biofuels, biomass ethanol is produced from corn, sugar cane, rice, organic waste, and the like as raw materials through a saccharification step, a fermentation step, a distillation step, and a dehydration step.

  When biomass ethanol is used as an engine fuel, the concentration is generally increased to 99.5% by mass or more. To concentrate, an aqueous ethanol solution (hydrous ethanol) produced in the fermentation step is usually subjected to a distillation step and a dehydration step to produce high-purity ethanol. However, a large amount of energy is consumed in these steps. For this reason, particularly in a small-scale ethanol production facility, production cost is disadvantageous.

  In view of this point, an aqueous ethanol solution produced by simplifying the distillation step and the dehydration step has attracted attention. If an aqueous ethanol solution is used, the production cost will be low, and its use as an alternative fuel is expected. On the other hand, an aqueous ethanol solution is disadvantageous in terms of thermal efficiency from the viewpoint of difficulty in burning. Therefore, in order to improve the thermal efficiency, a fuel reforming technique for reforming an aqueous ethanol solution and using a reformed gas containing hydrogen as a fuel is being studied.

  Patent Document 1 discloses a storage tank for an aqueous ethanol solution, a first supply device for supplying the aqueous ethanol solution in the storage tank to a reformer, and cooling of a mixed gas containing a reformed gas sent from the reformer. , A separation device that condenses water vapor contained in the mixed gas to separate gas and liquid, a reformed gas supply device that supplies the reformed gas separated by the separation device to the engine, and a recovered liquid separated by the separation device A recovery tank for supplying the recovered liquid in the recovery tank to the reformer, or a second recovered liquid supply apparatus for supplying the recovered liquid in the recovery tank to the combustion chamber of the engine. An ethanol engine system is described.

JP 2015-218676 A

  In the technology described in Patent Literature 1, an aqueous ethanol solution stored in a storage tank is sent to each of an engine and a reformer (see, for example, FIG. 1 of Patent Literature 1). That is, in this technique, an aqueous ethanol solution having the same ethanol concentration is sent to each of the engine and the reformer. However, since the ethanol aqueous solution is less likely to burn than high-purity ethanol, if the ethanol concentration in the ethanol aqueous solution is too low, the ethanol aqueous solution becomes more difficult to burn. As a result, the power generation efficiency of the engine decreases.

  On the other hand, if the ethanol concentration is too high, the amount of ethanol supplied to the reformer becomes stoichiometrically excessive. As a result, ethanol remains in the reformer. Then, it is more advantageous from the viewpoint of thermal efficiency to supply the engine as it is than to reform it. Therefore, thermal unnecessary reforming is performed, so that the thermal efficiency of the entire power generation system is reduced.

  In the technology described in Patent Document 1, heat generated in the engine is recovered, and the recovered heat is supplied to the reformer (see, for example, Paragraph 0022 of Patent Document 1). However, if the heat generated by the engine is excessive, excessive heat will be supplied to the reformer. Then, excess heat among the supplied heat is discharged to the outside. Therefore, from the viewpoint of thermal efficiency, the technique described in Patent Document 1 still has room for improvement.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a power generation system in which the thermal efficiency and the power generation efficiency are higher than before.

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, have found the following findings and completed the present invention. That is, the present invention relates to a fermentation apparatus for producing an aqueous ethanol solution by fermentation of biomass, a distillation apparatus for increasing the ethanol concentration in the aqueous ethanol solution by distilling the aqueous ethanol solution obtained in the fermentation apparatus, and an ethanol concentration in the distillation apparatus. An engine that burns an aqueous ethanol solution with increased power, a power generation device that generates power using power generated by the engine, an aqueous ethanol solution manufactured in the fermentation device, and an increased ethanol concentration in the distillation device. A reformer for producing a reformed gas containing hydrogen by reforming at least one of an aqueous ethanol solution, and a reformed gas supply for supplying the reformed gas produced in the reformer to the power generation device System, and supplying the waste heat from the power generation device to the distillation device, An engine exhaust heat first supply system for performing distillation in the distillation apparatus using the exhaust heat in the power generation apparatus, and supplying the exhaust heat in the power generation apparatus to the reformer. An engine exhaust heat second supply system for performing reforming, a reformed gas dehumidifier for removing moisture in the reformed gas produced in the reformer , and a supply of moisture removed by the reformed gas dehumidifier. And a removed water supply system for performing fermentation using water supplied in the fermentation apparatus .

  Advantageous Effects of Invention According to the present invention, it is possible to provide a power generation system in which thermal efficiency and power generation efficiency are higher than before.

It is a system diagram of a power generation system of a first embodiment. 4 is a graph showing the relationship between the concentration of ethanol in an aqueous ethanol solution and the temperature of the aqueous ethanol solution at which a reforming reaction can proceed with only the amount of heat held by the aqueous ethanol solution. FIG. 2 is a system diagram near an ethanol aqueous solution distillation column and an engine in the power generation system according to the first embodiment. It is a flow which shows the procedure until it produces a low concentration ethanol aqueous solution from a raw material. It is a flow which shows the operation method of an ethanol aqueous solution distillation column and an engine performed immediately after starting of a power generation system. It is a system diagram of a power generation system of a second embodiment. It is a system diagram of a power generation system of a third embodiment. FIG. 10 is a system diagram near an ethanol aqueous solution distillation column and an engine in the power generation system according to the third embodiment. It is a system diagram of a power generation system of a fourth embodiment. FIG. 13 is a system diagram near an ethanol aqueous solution distillation column and an engine in a power generation system according to a fourth embodiment.

  Hereinafter, a mode for carrying out the present invention (this embodiment) will be described with reference to the drawings as appropriate. In each of the drawings, common components are denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a system diagram of a power generation system 100 according to the first embodiment. The power generation system 100 uses an aqueous ethanol solution obtained by fermenting a raw material to increase the power generation efficiency of an engine. In particular, in the power generation system 100, the generated ethanol aqueous solution is supplied to the reformer or supplied to the engine according to the concentration of the aqueous ethanol solution (the concentration of ethanol in water (% by mass), the same applies hereinafter). .

  The power generation system 100 shown in FIG. 1 includes a saccharification fermenter 1, a solid-liquid separator 2, a low concentration ethanol aqueous solution tank 3, an ethanol aqueous solution distillation column 4, a high concentration ethanol aqueous solution tank 5, an engine 6, a generator 7, an ethanol concentration The apparatus includes an adjusting device 8, heat exchangers 9, 10, a reformer 11, a gas-liquid separator 12, a surplus water tank 13, an ethanol concentration adjusting device 14, and an arithmetic control unit 101. In FIG. 1, solid arrows indicate pipes through which substances such as an aqueous ethanol solution, reformed gas, and exhaust gas flow, and a flow direction of the pipes, though not shown. Further, the double arrow indicates the transmission direction of power and energy. Further, although not shown, facilities such as pipes, valves, and pumps are appropriately installed for mass transfer between the devices shown in FIG.

  The saccharification and fermentation tank 1 uses a raw material (biomass) to be fermented, an enzyme, yeast, and, if necessary, water for concentration adjustment, and agitates the inside to produce ethanol fermentation. Is to produce. The fermentation broth includes an aqueous ethanol solution (a low-concentration aqueous ethanol solution containing ethanol and water). Raw materials include corn, sugar cane, rice, organic waste, and the like, and enzymes and yeasts are selected according to the raw materials. For example, glucose (sugar) is generated by causing cellulase (enzyme) to act on corn. Then, by causing yeast to act on this glucose, ethanol is produced.

  As the water for concentration adjustment used in the saccharification and fermentation tank 1, surplus water (mainly water) stored in a surplus water tank 13 (described later) and supplied from a surplus water supply system 55 is used. Further, the water used in the saccharification and fermentation tank 1 may be, for example, tap water supplied from the outside as necessary.

  The saccharification and fermentation tank 1 may be constituted by a single tank, or may be constituted by a plurality of tanks. When a plurality of raw materials can be used, the saccharification and fermentation tank 1 may be configured to perform saccharification and fermentation using a plurality of tanks according to the raw materials. In addition, in order to optimize the operating conditions of each step of saccharification and fermentation, the saccharification and fermentation tank 1 is configured to use a plurality of tanks for each step, such as a saccharification tank and a fermentation tank that are separately configured. Is also good.

  In the saccharification and fermentation tank 1, optimal temperature control for saccharification and fermentation of the raw material is performed. As a method of temperature control, although not shown, a jacket installed outside the saccharification and fermentation tank 1 or a coil for temperature adjustment installed inside the saccharification and fermentation tank 1 is used. Then, cooling or heating in the saccharification and fermentation tank 1 is performed by circulating a heat medium inside the jacket or the coil using a constant-temperature heat medium circulation device (not shown) or the like.

  In the temperature control of the heat medium to be circulated, heating is performed using exhaust heat (used cooling water, exhaust gas, and the like) from the engine 6 (described later) supplied through the exhaust heat supply system 54. Done. The exhaust heat supply system 54 can be configured to include, for example, another heat medium circulating between the engine 6 and the saccharification and fermentation tank 1. Therefore, the exhaust heat of the engine 6 can be supplied to the saccharification and fermentation tank 1 via this heat medium. On the other hand, in the temperature control of the heat medium to be circulated, for cooling, for example, an electric cooler (not shown) can be used.

  The solid-liquid separator 2 separates the fermented liquor produced in the saccharification and fermentation tank 1 into a solid and a liquid by a method such as sedimentation, centrifugation, filtration, or pressing. The solids are called fermentation residues and are treated as valuables or waste depending on the fermentation feedstock. That is, the fermentation residue is effectively used as feed, fertilizer, or the like as a valuable resource, or incinerated or landfilled as waste (industrial waste).

  The solid-liquid separation device 2 may be configured to also serve as the saccharification and fermentation tank 1. Further, the solid-liquid separation device 2 may be configured by a single separation device or method, as in the case of the saccharification and fermentation tank 1, or may be configured by a plurality of separation devices or methods. In particular, when the solid-liquid separation device 2 is configured by a plurality of separation devices, these devices may be connected in series or connected in parallel.

  The low-concentration aqueous ethanol solution tank 3 stores the liquid separated by the solid-liquid separation device 2, that is, the aqueous ethanol solution. The ethanol concentration is, for example, 2% by mass to 20% by mass as the mass concentration of ethanol with respect to water.

  The ethanol aqueous solution distillation column 4 separates a high-concentration ethanol aqueous solution and an aqueous solution containing a small amount of ethanol using the low-concentration ethanol aqueous solution supplied from the low-concentration ethanol aqueous solution tank 3. That is, in the ethanol aqueous solution distillation column 4, the ethanol concentration of the low concentration ethanol aqueous solution produced in the saccharification and fermentation tank 1 is increased by distillation, and high concentration ethanol is produced.

  An aqueous solution other than the high-concentration ethanol aqueous solution produced in the ethanol aqueous solution distillation column 4, that is, an aqueous solution containing a small amount of ethanol is called a distillation residue, and is the same as the fermentation residue in the solid-liquid separation device 2 depending on the fermentation raw material. Is treated as valuables or waste. That is, the distillation residue is effectively used as a valuable material for feed, fertilizer, or the like, or is incinerated or drained as waste (industrial waste). The configuration of the ethanol aqueous solution distillation column 4 will be described in detail with reference to FIG.

  The high concentration ethanol aqueous solution tank 5 stores the high concentration ethanol aqueous solution separated in the ethanol aqueous solution distillation column 4. The ethanol concentration of the aqueous ethanol solution stored here is, for example, 40% by mass to 90% by mass. However, the upper limit is preferably less than 60% by mass from the viewpoint of easy handling and storage.

  The ethanol concentration adjusting device 14 mixes the high-concentration ethanol aqueous solution supplied from the high-concentration ethanol aqueous solution tank 5 with the water supplied from the surplus water tank 13 and adjusts the ethanol concentration to be combustible in the engine 6. . That is, here, the excess water removed by the gas-liquid separation device 12 described later is used, and the ethanol concentration of the high-concentration ethanol aqueous solution obtained in the ethanol aqueous solution distillation column 4 is adjusted. In the ethanol concentration adjusting device 14, the ethanol concentration is adjusted to about 40% by mass from the viewpoint of easiness of combustion in the engine 6 and reduction in the amount of the obtained high-concentration ethanol for long-term operation. . It should be noted that high-concentration ethanol may be supplied to the engine 6 without dilution with water (that is, the ethanol concentration is about 40% by mass or more).

  The engine 6 is driven using at least one of a high-concentration aqueous ethanol solution supplied from the ethanol concentration adjusting device 14 and a reformed gas (mainly hydrogen) supplied from the gas-liquid separation device 12 as fuel. It is. In the engine 6, air is taken in from an intake port (not shown) to burn fuel, and the energy of the obtained combustion gas is converted into power (rotational force). The combustion gas after removing the power is discharged as exhaust gas. Exhaust gas discharged here is usually, for example, about 600 ° C. and has a sufficient amount of heat. Then, this exhaust gas is supplied to the heat exchanger 10 and used for heating the low-concentration ethanol aqueous solution supplied to the reformer 11 (described later).

  In addition, cooling water for cooling the engine 6 is circulated between the engine 6 and a heat exchanger 402 (which will be described later with reference to FIG. 3) that forms the ethanol aqueous solution distillation column 4. The cooling water usually leaves the engine 6 at a temperature of, for example, about 80 ° C., and has a sufficient heat quantity due to its large flow rate. Then, the cooling water discharged from the engine 6 is supplied to the ethanol aqueous solution distillation column 4, and is used as a part of the heat energy distilled in the ethanol aqueous solution distillation column 4. The details of this point will be described with reference to FIGS.

  The engine 6 may be constituted by a single engine, or may be constituted by a plurality of engines. Further, the combustion mechanism of the engine 6 is not limited. As the engine 6, for example, various internal combustion engines such as a spark ignition engine, a diesel engine, and a gas turbine engine can be applied.

  The generator 7 generates power using the power (rotational force) generated by the engine 6 and enables power to be supplied to a power load. The power supplied to the power load is so-called “commercial power”. Therefore, according to the number of poles of the generator 7, the rotation speed of the generator 7 is set to a constant rotation speed of, for example, 1500 or 3000 rpm when the frequency of the commercial power is 50 Hz, and is set to, for example, 1800 or 3600 rpm at 60 Hz. Therefore, the rotation speed of the engine 6 is set so that the rotation speed of the generator 7 is constant. The power generated by the generator 7 may be converted to DC by a converter, and then converted to AC power of an arbitrary frequency by an inverter.

  When there are a plurality of engines, the generator 7 may be configured with one generator for one engine. In addition, a single generator may be provided for a plurality of engines by sharing the rotating shafts of the plurality of engines or connecting them by gears or the like.

  The ethanol concentration adjusting device 8 mixes (i.e., dilutes) the low-concentration ethanol aqueous solution supplied from the low-concentration ethanol aqueous solution tank 3 with water supplied from the surplus water tank 13, and forms the reformer 11 (described later). ) Is adjusted to an ethanol concentration that can be reformed. That is, here, the excess water removed by the gas-liquid separator 12 described later is used, and the concentration of the low-concentration ethanol (produced in the saccharification and fermentation tank 1) supplied to the reformer 11 is adjusted. The specific ethanol concentration will be described in the section of the reformer 11 described later.

  The heat exchanger 9 exchanges heat between the aqueous ethanol solution whose concentration has been adjusted by the ethanol concentration adjusting device 8 and the reformed gas (mainly hydrogen) reformed by the reformer 11. The heat exchanger 9 has a heat receiving side flow passage through which the aqueous ethanol solution supplied from the ethanol concentration adjusting device 8 flows. One end of the heat receiving side flow path is connected to the outlet of the ethanol concentration adjusting device 8, and the other end is connected to the inlet of the heat receiving side flow path of the heat exchanger 10. Further, the heat exchanger 9 has a heat-radiation side flow path through which the reformed gas flows. One end of the heat-radiation side flow path is connected to the outlet of the reformer 11, and the other end is connected to the inlet of the gas-liquid separator 12.

  The heat exchanger 10 exchanges heat between the aqueous ethanol solution heated by the heat exchanger 9 and the exhaust gas of the engine 6. The heat exchanger 10 has a heat receiving side flow path through which the aqueous ethanol solution flows. One end of the heat receiving flow path is connected to an outlet of the heat receiving flow path of the heat exchanger 9, and the other end is connected to an inlet of the reformer 11. Further, the heat exchanger 10 has a heat-radiation-side flow path through which exhaust gas flows. One end of the heat radiation side flow path is connected to an exhaust gas outlet of the engine 6, and the other end is connected to a heat exchanger inlet of the ethanol aqueous solution distillation column 4.

  In addition, exhaust heat supply systems 52 and 53 are connected to the exhaust gas outlet side of the engine 6 to a heat radiation side flow path (not shown) constituting the heat exchanger 10. Further, a reformer 11 is provided downstream of the heat-receiving-side flow passage that exchanges heat with the heat-radiating-side flow passage. Therefore, in the reformer 11, the reforming of the aqueous ethanol solution is performed using the exhaust heat of the engine 6 received by the heat exchanger 10 through the exhaust heat supply system 53.

  In addition, a waste heat supply system 52 is connected to the heat dissipation side flow path that constitutes the heat exchanger 10 on the side of the aqueous ethanol solution distillation column 4. The exhaust gas of the engine 6, which has lost heat in the heat exchanger 10, still has some heat. Then, the exhaust gas after losing heat in the heat exchanger 10 is supplied to the ethanol aqueous solution distillation column 4 through the exhaust heat supply system 52. Therefore, in the ethanol aqueous solution distillation column 4, the distillation of the low-concentration ethanol is performed by using the remaining waste heat of the exhaust gas of the engine 6 in this manner.

  The reformed gas discharged from the reformer 11 has a temperature of about 300 ° C. to 400 ° C. and has a sufficient amount of heat. Therefore, in the heat exchanger 9, the ethanol solution whose concentration has been adjusted by the ethanol concentration adjusting device 8 is heated from near room temperature to near the boiling point (about 76 ° C. to 100 ° C.) by using the calorie. On the other hand, in the heat exchanger 9, the temperature of the reformed gas is lowered by applying heat to the aqueous ethanol solution. Therefore, in the heat exchanger 9, the heat of the reformed gas is given to the aqueous ethanol solution, and the amount of heat used as the reaction heat of the reforming reaction is stored in the aqueous ethanol solution, while the temperature of the reformed gas is reduced. Water vapor contained in the raw gas is condensed and liquefied.

  The exhaust gas from the engine 6 is, for example, about 600 ° C. as described above, and has a sufficient amount of heat. Therefore, in the heat exchanger 10, the heat amount is used to raise the temperature of the aqueous ethanol solution to about 300 ° C. to 400 ° C. at which the reforming reaction occurs in the reformer 11. On the other hand, the exhaust gas gives a calorific value to the aqueous ethanol solution to lower the temperature. Therefore, in the heat exchanger 10, the heat of the exhaust gas is given to the aqueous ethanol solution, and the amount of heat used as the reaction heat of the reforming reaction is stored in the aqueous ethanol solution. Thereby, the use efficiency (thermal efficiency) of the exhaust heat of the exhaust gas of the engine 6 is enhanced.

  In the power generation system 100, heat exchangers 9 and 10 are provided before the reformer 11. By providing the two heat exchangers 9 and 10 in this way and raising the temperature of the aqueous ethanol solution step by step, the temperature of the aqueous ethanol solution is raised to a temperature that is difficult only with the heat exchanger 10. Accordingly, reforming in the reformer 11 is promoted, and the amount of reformed gas generated in the reformer 11 increases. Therefore, the amount of the reformed gas supplied to the engine 6 increases. In the heat exchangers 9 and 10, the heat of the high-temperature reformed gas is used for raising the temperature of the aqueous ethanol solution, so that the exhaust heat of the engine 6 is effectively used for fuel reforming. Then, the thermal efficiency of the engine 6 is improved by increasing the amount of recovered exhaust heat in the engine 6 and increasing the amount of reformed gas.

  The heat exchangers 9 and 10 are, for example, appropriate types of heat exchangers such as a shell and tube type, a plate type, and a fin tube type. The heat exchangers 9 and 10 may be constituted by a single heat exchanger or may be constituted by a plurality of heat exchangers. The arrangement of the plurality of heat exchangers may be in series or in parallel.

  It is preferable that the heat exchangers 9 and 10 be covered with a heat insulator. Examples of the heat insulator include a heat insulating cover and a heat insulating jacket formed of a heat insulating material such as foamed resin, glass wool, and rock wool. By covering the heat exchanger with a heat insulator, heat loss due to heat radiation is reduced, and the amount of heat used as reaction heat for the reforming reaction can be reliably stored in the ethanol aqueous solution. Further, the thermal efficiency of the power generation system 100 as a whole is also improved.

The reformer 11 reforms the aqueous ethanol solution heated in the heat exchanger 10 to generate a reformed gas containing hydrogen. The reformed gas generated here is supplied to the engine 6 through the reformed gas supply system 51. The reforming performed in the reformer 11 proceeds according to the following equations (1) and (2).
C ₂ H ₅ OH + 3H ₂ O → 2CO ₂ + 6H ₂ -217 kJ Formula (1)
C ₂ H ₅ OH + H ₂ O → 2CO + 4H ₂ −298 kJ Formula (2)

  Here, of these formulas (1) and (2), carbon monoxide generated in formula (2) quickly reacts with high-temperature water (steam) and changes to carbon dioxide and hydrogen. Therefore, in the reformer 11, it can be considered that substantially only the equation (1) proceeds.

  The reforming reactions represented by the formulas (1) and (2) are both endothermic reactions. Therefore, in order to generate a reformed gas using an aqueous ethanol solution, heat is usually given to the reaction system. However, in the power generation system 100, the ethanol aqueous solution to be reformed contains a large proportion of water having a large heat capacity. Then, as described above, the heat is stored in advance in the heat exchangers 9 and 10 as the amount of heat used as the reaction heat of the reforming reaction. Therefore, in the power generation system 100, since the ethanol aqueous solution storing the amount of heat used as the reaction heat of the reforming reaction is introduced into the reformer 11, no heat is supplied from the outside, or if the heat is supplied. Even if the supply amount is reduced, the aqueous ethanol solution is reformed.

  Here, referring to FIG. 2, the concentration of the aqueous ethanol solution supplied to the reformer 11 and the progress of the reforming without supplying heat from the outside (that is, only by the amount of heat held by the aqueous ethanol solution) can be performed. The relationship with the possible ethanol temperature (the inlet temperature of the reformer 11) will be described.

  FIG. 2 is a graph showing the relationship between the ethanol concentration in the aqueous ethanol solution and the temperature of the aqueous ethanol solution that can proceed with the reforming reaction only by the amount of heat held by the aqueous ethanol solution. FIG. 2 shows that the reforming reaction in the reformer 11 is only the above equation (1), and that the temperature of the reformed gas at the outlet of the reformer 11 (outlet temperature) is about 300 ° C. Can be reformed with only the heat used as the reaction heat of the reforming reaction (that is, only the heat held by the aqueous ethanol solution), assuming that the temperature is the minimum temperature that is normally required to complete the quality. It shows the temperature of the inlet of the ethanol aqueous solution reformer 11 (that is, the temperature of the ethanol aqueous solution supplied to the reformer 11).

  In an aqueous ethanol solution, the lower the ethanol concentration, the higher the proportion of water having a large heat capacity. That is, the lower the ethanol concentration, the lower the temperature of the ethanol aqueous solution that can be reformed only by the amount of heat held by the ethanol aqueous solution. Here, the exhaust gas temperature of the engine 6 is, for example, about 600 ° C. as described above. Therefore, the temperature of the aqueous ethanol solution supplied to the reformer 11 can be raised to at least about 500 ° C. and up to about 600 ° C. by the two-stage heating by the heat exchangers 9 and 10.

  Then, from the graph shown in FIG. 2, if the temperature of the aqueous ethanol solution is at most about 17% by mass or less, preferably about 11% by mass or less, the reforming reaction can be sufficiently caused only by the amount of heat held by the aqueous ethanol solution. It is thought that it is possible. That is, by reforming an aqueous ethanol solution having an ethanol concentration of about 17% by mass or less, it is possible to reliably store the heat required for the reforming reaction when the exhaust gas temperature of the engine 6 is 600 ° C. It is. In addition, the lower the ethanol concentration, the lower the production cost, and the lower the conversion rate due to the deposition of carbon on the reforming catalyst.

  In addition, as described above, the reforming of the aqueous ethanol solution in the reformer 11 proceeds substantially by the reaction represented by the above formula (1). Therefore, in the reformer 11, 1 mol of ethanol is converted into 6 mol of hydrogen (molecule). Here, the standard combustion heat of ethanol is 1366 kJ / mol, and the standard combustion heat of hydrogen is 285 kJ / mol. Therefore, the amount of heat (1710 kJ) generated by burning 6 mol of hydrogen obtained by reforming is larger than the amount of heat (1366 kJ) generated by burning 1 mol of ethanol in the engine 6.

  Therefore, it can be said that burning 6 mol of hydrogen generates more heat than burning 1 mol of ethanol. Therefore, by generating electricity using the amount of heat generated by burning 6 mol of hydrogen obtained by performing the reforming, the power generation efficiency of the generator 7 can be increased. Therefore, by reforming the low-concentration aqueous ethanol solution, the reforming reaction can be sufficiently caused only by the calorific value of the aqueous ethanol solution, and the power generation efficiency can be increased.

  Further, as described above, it is considered that substantially only the above-mentioned equation (1) proceeds in the reforming reaction. Therefore, considering the stoichiometric ratio derived from the formula (1), the concentration of the aqueous ethanol solution is preferably set to about 46% by mass or less. It is advantageous from the viewpoint of thermal efficiency to make the concentration of the aqueous ethanol solution about 46% by mass or less. That is, for example, if the concentration of the ethanol aqueous solution exceeds about 46% by mass, it is thermally advantageous to supply the ethanol aqueous solution as it is without reforming. Further, when the concentration of the aqueous ethanol solution is about 46% by mass or less, unreacted ethanol is formed by reacting ethanol and water at a stoichiometric ratio, assuming that the reforming reaction is only the formula (1). Can be suppressed from remaining on the surplus water side in the gas-liquid separation device 12.

  To summarize the above points, the ethanol concentration of the aqueous ethanol solution supplied to the reformer 11 is usually about 60% by mass or less from the viewpoint of simplicity in handling and storage, and preferably from the viewpoint of thermal efficiency. Is preferably about 46% by mass or less, more preferably about 17% by mass or less, and particularly preferably about 11% by mass or less, from the viewpoint of easiness of reforming only by the caloric value of the aqueous ethanol solution.

  Returning to FIG. 1, the reforming in the reformer 11 is performed using a catalyst. Examples of usable catalysts include, for example, nickel, platinum, palladium, rhodium, iridium, ruthenium, molybdenum, rhenium, tungsten, vanadium, osmium, chromium, cobalt, iron, niobium, copper, zinc, and the like, as appropriate. Composite catalyst. Further, the catalyst is usually supported on a carrier. Examples of the carrier include α-alumina, titania, zirconia, niobium oxide, silica, magnesia, ceria, and the like, and a composite carrier in which these are appropriately combined. The shape of the carrier can be, for example, a pellet, a honeycomb, a sheet, a monolith, a particle, or the like.

  It is preferable that the reformer 11 be covered with a heat insulator. Examples of the heat insulator include a heat insulating cover and a heat insulating jacket formed of a heat insulating material such as foamed resin, glass wool, and rock wool. By covering the reformer 10 with the heat insulator, heat loss due to heat radiation is reduced. As a result, the reformed gas is maintained at a high temperature near the outlet of the reformer 11 where the reforming reaction, which is an endothermic reaction, has progressed, and the amount of heat exchange in the heat exchanger 9 provided downstream of the reformer 11 is reduced. More.

  The gas-liquid separator 12 separates steam and unreacted ethanol vapor contained in the reformed gas generated in the reformer 11. The gas-liquid separator 12 is configured by, for example, a drain tank (not shown) that can store a liquid and can condense and separate steam and unreacted ethanol vapor from the cooled reformed gas.

  The vapor contained in the reformed gas and the unreacted ethanol vapor may be condensed by applying heat to the aqueous ethanol solution by heat exchange in the heat exchanger 9 or may be condensed at the environmental temperature in the gas-liquid separator 12. Is also good. Further, it may be condensed by a condenser (not shown) mounted on the gas-liquid separation device 12. Although not shown, the condenser includes an engine cooling water for cooling the engine 6, a water-cooled heat exchanger using tap water supplied from the outside, medium water, and the like, as well as a fin tube type and a shell tube type. And the like, an apparatus using an air-cooled heat exchanger, an air-cooled cooler using forced ventilation or natural ventilation, or the like.

  As described with reference to FIG. 2, when the concentration of the aqueous ethanol solution supplied to the reformer 11 (concentration at the inlet of the reformer 11) is about 46% by mass or less, the above-described formula is used as the reforming reaction. Even if it is assumed that only (1) has proceeded and that it has proceeded at the maximum yield, water remains after the reforming reaction. Therefore, if the gas-liquid separator 12 is provided downstream of the reformer 11, the water contained in the reformed gas is reliably removed regardless of the concentration of the aqueous ethanol solution. As a result, a decrease in the combustion efficiency, combustion temperature, and output of the engine 6 is prevented, and the thermal efficiency of the engine 6 is maintained at a high level.

  From this viewpoint, it is preferable that the reformed gas cooled to 100 ° C. or lower be supplied to the gas-liquid separation device 12. Thereby, the steam contained in the reformed gas can be liquefied, and water (liquid) is removed as excess water in the gas-liquid separator 12. The water removed here is sent to a surplus water tank 13 described later. On the other hand, the temperature of the reformed gas supplied to the gas-liquid separation device 12 can be, for example, 78 ° C. or higher. As a result, recovery (condensation) of unreacted ethanol is suppressed, and unreacted ethanol (gas) is easily supplied to the engine 6 as fuel.

  The temperature of the reformed gas does not need to be constant, but may be within a predetermined range depending on the specifications of the engine 6, the specifications of the reformer 11, the environmental temperature of the place where the power generation system 100 is installed, and the like. It is preferable to perform management.

  The surplus water tank 13 stores liquid such as water separated by the gas-liquid separation device 12. The liquid to be stored mainly remains as an unreacted substance in the reformer 11. Therefore, if the concentration of the aqueous ethanol solution at the inlet of the reformer 11 is 46% by mass or less, if only the above formula (1) proceeds as the reforming reaction, and if it proceeds at the maximum yield, the liquid becomes It becomes water. However, some of the hydrogen and carbon dioxide generated in the reformer 11 exist in a state of being dissolved in water.

  The surplus water stored in the surplus water tank 13 is sent to the saccharification and fermentation tank 1. Then, the sent water is mixed with a raw material for fermentation, and used for adjusting the concentration of the raw material in the saccharification and fermentation tank 1. The surplus water stored in the surplus water tank 13 is also sent to the ethanol concentration adjusting device 8. The water sent to the ethanol concentration adjusting device 8 is mixed with the low concentration ethanol aqueous solution supplied from the low concentration ethanol aqueous solution tank 3 and used for concentration adjustment. Further, the surplus water stored in the surplus water tank 13 is also sent to the ethanol concentration adjusting device 14. Then, the sent water is mixed with the high-concentration ethanol aqueous solution supplied from the high-concentration ethanol aqueous solution tank 5, and used for adjusting the concentration at which the engine 6 can burn.

  As described above, in the power generation system 100, surplus water is used for adjusting the raw material concentration and diluting the aqueous ethanol solution. As a result, the amount of water used can be reduced. Further, the surplus water is so-called "hydrogen water" in which hydrogen as a component of the reformed gas is dissolved in water. Hydrogen water is said to grow better when given to plants, so such surplus water can also be used for irrigation of crops.

  The arithmetic and control unit 101 monitors and controls the power generation system 100. Although not shown, the arithmetic and control unit 101 collects measurement data from measurement devices (such as sensors) provided at various parts of the power generation system 100. The arithmetic and control unit 101 controls control devices (pumps, valves, throttles, etc., not shown) provided at various parts of the power generation system 100 in accordance with a program stored in advance therein.

  Although not shown, the arithmetic control unit 101 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an I / F (interface), and the like. The arithmetic control unit is embodied by executing a predetermined control program stored in the ROM by the CPU.

  FIG. 3 is a system diagram near the ethanol aqueous solution distillation column 4 and the engine 6 in the power generation system 100 of the first embodiment. However, in FIG. 3, for simplification of illustration, illustration of a part of the device described with reference to FIG. 1 is omitted. In FIG. 3, solid arrows indicate pipes through which substances such as an aqueous ethanol solution, reformed gas, and exhaust gas flow, and the flow directions thereof. The broken arrows also indicate the pipes through which the substance flows and the flow directions thereof. However, in the flow in the direction indicated by the dashed arrow, the illustration of the devices arranged in the middle is partially omitted. Further, the double arrow indicates the transmission direction of power and energy as described above. A portion surrounded by a dashed line corresponds to the ethanol aqueous solution distillation column 4 and the engine 6 in FIG.

  The ethanol aqueous solution distillation column 4 is a distillation column main body 401 that performs distillation, heat exchangers 402 and 403 that are preheaters of the distillation column, a heat exchanger 404 that is a top condenser of the distillation column, and a bottom reboiler of the distillation column. A heat exchanger 405 is provided. Then, in the ethanol aqueous solution distillation column 4, the low-concentration ethanol aqueous solution from the low-concentration ethanol aqueous solution tank 3 is supplied to the heat exchangers 402 and 403. Then, in the heat exchangers 402 and 403, the supplied low-concentration ethanol is gradually heated from near room temperature to near the boiling point of the aqueous ethanol solution (about 76 ° C. to 100 ° C.). Supplied.

  The heat exchanger 402 exchanges heat between the aqueous ethanol solution from the low-concentration aqueous ethanol solution tank 3 and the used cooling water from the engine body 601. That is, in the heat exchanger 402, the low-concentration ethanol generated in the saccharification and fermentation tank 1 by the cooling water of the engine 6 (used cooling water having exhaust heat of the engine 6) supplied through the used cooling water supply system 57. Is heated.

  The heat exchanger 402 has a heat receiving side flow passage through which the low concentration ethanol aqueous solution flows. One end of the heat receiving flow path is connected to the outlet of the low concentration ethanol aqueous solution tank 3, and the other end is connected to the inlet of the heat receiving flow path of the heat exchanger 403. The heat exchanger 402 has a heat-radiation-side flow path through which the cooling water of the engine 6 flows. One end of the heat radiation side flow path is connected to the cooling water outlet of the engine body 601, and the other end is connected to the heat radiation side flow path inlet of the heat exchanger 602 which is a radiator of the engine.

  The used cooling water discharged from the engine body 601 (described later) has a sufficient calorific value because it has a temperature of about 90 ° C. and a large flow rate. Therefore, in the heat exchanger 402, the low-concentration ethanol aqueous solution is heated using the calorific value from a temperature near room temperature to a temperature near the boiling point (about 76 ° C. to 100 ° C.). On the other hand, in the heat exchanger 402, the used cooling water of the engine main body 601 gives heat to the low-concentration ethanol aqueous solution to lower the temperature.

  The heat exchanger 403 exchanges heat between the aqueous ethanol solution from the heat exchanger 402 and the exhaust gas from the heat exchanger 405. That is, in the heat exchanger 403, the low-concentration ethanol generated in the saccharification and fermentation tank 1 through the heat exchanger 402 is heated by the exhaust gas of the engine 6 supplied through the exhaust heat supply system 52 and the heat exchanger 405. .

  The heat exchanger 403 has a heat receiving side flow passage through which the low concentration ethanol aqueous solution flows. One end of the heat receiving flow path is connected to an outlet of the heat receiving flow path of the heat exchanger 402, and the other end is connected to an inlet of the distillation column main body 401. Further, the heat exchanger 403 has a heat radiation side flow passage through which the exhaust gas of the engine 6 flows. One end of the heat-dissipating channel is open to the outlet of the heat-dissipating channel of the heat exchanger 405, which is the bottom reboiler of the distillation column, and the other end is open to the atmosphere.

  Exhaust gas exhausted from the engine main body 601 (described later) and passed through the exhaust gas purifier 603 (described later) is subjected to heat exchange in the heat exchangers 10 and 405 (described later), and the temperature thereof is reduced. It has a calorific value. Therefore, in the heat exchanger 403, the low-concentration aqueous ethanol solution is heated to a temperature close to the boiling point of the low-concentration ethanol (about 76 ° C. to 100 ° C.) using the calorific value. On the other hand, the exhaust gas of the engine body 601 gives heat to the low-concentration ethanol aqueous solution to further lower the temperature.

  The heat exchanger 404 is connected to the top of the distillation column main body 401 and exchanges heat between steam extracted from the top of the distillation column main body 401 and cold water supplied from a chiller (not shown). is there. The heat exchanger 404 has a heat receiving side flow passage through which the cold water supplied from the chiller flows. One end of the heat receiving side flow path is connected to a chilled water outlet of the chiller, and the other end is connected to a chilled water inlet (chilled water return port) of the chiller. Further, the heat exchanger 404 has a heat radiation side flow passage through which steam from the top of the distillation column main body 401 flows. One end of the heat radiation side flow path is connected to the outlet of the top of the distillation column 401, and the other end is connected to the inlet of the top of the distillation column 401 and the inlet of the high concentration ethanol aqueous solution tank 5.

  The cold water (tap water, medium water, etc.) supplied to the heat exchanger 404 has a sufficient cooling capacity because it has a flow rate of about 20 ° C. and a large flow rate. Then, using the cooling capacity, in the heat exchanger 404, the vapor from the top of the distillation column main body 401 is condensed and liquefied to near the boiling point of the ethanol aqueous solution (about 76 ° C. to 100 ° C.). On the other hand, the temperature of the cold water rises in the heat exchanger 404 due to the latent heat of vaporization of the steam from the top of the tower.

  The heat exchanger 405 is connected to the bottom of the distillation column main body 401 and exchanges heat between the liquid extracted from the bottom of the distillation column main body 401 and the exhaust gas from the heat exchanger 10. That is, the liquid extracted from the bottom of the distillation column body 401 is heated in the heat exchanger 405 using the exhaust gas of the engine 6 supplied through the exhaust heat supply system 52 and the heat exchanger 405. .

  The heat exchanger 405 has a heat receiving side flow passage through which the liquid from the bottom of the distillation column main body 401 flows. One end of the heat receiving-side flow path is connected to an outlet at the bottom of the distillation column main body 401, and the other end is connected to an inlet at the bottom of the distillation column main body 401 and a flow path for extracting distillation residue. Further, the heat exchanger 405 has a heat-radiation-side flow path through which the exhaust gas of the engine 6 flows. One end of the heat radiation side flow path is connected to the outlet of the heat radiation side flow path of the heat exchanger 10, and the other end is connected to the inlet of the heat radiation side flow path of the heat exchanger 403.

  Exhaust gas exhausted from the engine main body 601 (described later) and passed through the exhaust gas purifier 603 (described later) has a sufficient amount of heat, although the heat is exchanged in the heat exchanger 10 and its temperature is lowered. . Therefore, in the heat exchanger 405, the liquid from the bottom of the column is evaporated and vaporized to near the boiling point of the aqueous ethanol solution (about 76 ° C. to 100 ° C.) by using the heat amount. Here, the evaporated and vaporized ethanol aqueous solution (a part or all of which may remain liquid) is returned to the distillation column main body 401 through the return system 56. On the other hand, the exhaust gas that has lost heat in the heat exchanger 405 further reduces the temperature by applying heat to the liquid from the bottom of the tower.

  In the ethanol aqueous solution distillation column 4 having the above-described configuration, the liquid at the bottom of the column is heated and evaporated in the heat exchanger 405 which is a bottom reboiler. Then, the vapor and the liquid come into contact with each other at a plurality of shelves provided in the distillation column main body 401. Furthermore, in the heat exchanger 404 which is a top condenser, the vapor at the top is cooled and condensed and liquefied. The liquid generated here becomes a high-concentration ethanol aqueous solution having a higher concentration than the low-concentration ethanol aqueous solution supplied to the distillation column main body 401. Then, a part of the high-concentration ethanol aqueous solution is refluxed to the distillation column main body 401, and the remainder is extracted from the ethanol aqueous solution distillation column 4 as a distillate. On the other hand, the liquid at the bottom of the column is an aqueous ethanol solution having a lower concentration than the aqueous low concentration ethanol solution supplied to the distillation column main body 401. Then, a part of the ethanol aqueous solution is heated and evaporated in the heat exchanger 405 and returned to the distillation column main body 401, and the remainder is extracted from the ethanol aqueous solution distillation column 4 as a distillation residue.

  The engine 6 that constitutes the power generation system 100 includes an engine body 601, a heat exchanger 602 that is a radiator of the engine body 601, and an exhaust gas purification device 603.

  The engine 6 drives at least one of the high-concentration ethanol aqueous solution from the high-concentration ethanol aqueous solution tank 5 and the reformed gas from the gas-liquid separation device 12 as fuel. The engine 6 is driven by taking in air required for combustion from an intake port (not shown) and burning fuel to extract power. Then, the obtained energy (power) of the combustion gas is transmitted to the generator 7 not shown in FIG. 3 and converted into electric power.

  The engine 6 includes a heat exchanger 602. The heat exchanger 602 has a heat receiving side flow passage through which air supplied from a fan (not shown) flows. One end of the heat-receiving-side passage is open to the air outlet of the fan, and the other end is open to the atmosphere. Further, the heat exchanger 602 has a heat-radiation-side flow path through which the cooling water of the engine 6 flows. One end of the heat radiation side flow path is connected to the heat radiation side flow path outlet of the heat exchanger 402 of the ethanol aqueous solution distillation column 4, and the other end side is connected to the cooling water inlet of the engine body 601.

  The engine main body 601 is cooled with cooling water to prevent seizure of the engine. Then, the high-temperature used cooling water (used cooling water) that has exited the engine main body 601 is supplied to the heat exchanger 402 of the ethanol aqueous solution distillation column 4. In the heat exchanger 402, heat of the high-temperature cooling water is exchanged. The temperature of the cooled cooling water is further lowered in the heat exchanger 602 which is a radiator of the engine, and is returned to the engine body 601.

  The engine body 601 discharges the combustion gas from which power has been taken out as exhaust gas. Most of the exhaust gas components are carbon dioxide and water vapor derived from the fuel, and other components include an air component supplied in excess. On the other hand, the trace components include carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM), and sulfur oxides (SOx). Since these trace components are harmful to animals and plants, harmless treatment is performed by an exhaust gas purifying device 603 such as a decomposition catalyst and an adsorbent.

  FIG. 4 is a flowchart showing a procedure until a low-concentration ethanol aqueous solution is produced from a raw material. This flow is performed by the arithmetic and control unit 101 using the saccharification and fermentation tank 1 and the solid-liquid separation device 2 shown in FIG. Then, the low-concentration ethanol produced through this flow is stored in the low-concentration ethanol aqueous solution tank 3 shown in FIG.

  First, raw materials (biomass such as sugarcane), enzymes, and water as needed are charged into the saccharification and fermentation tank 1 (step S101). Next, appropriate stirring is performed while the temperature inside the saccharification and fermentation tank 1 is adjusted to a temperature suitable for the saccharification reaction. Thereby, saccharification progresses, and production of saccharides such as monosaccharides and disaccharides is started. After that, the arithmetic and control unit 101 monitors the concentration of sugar present inside the saccharification and fermentation tank 1 using a sensor (not shown) provided in the saccharification and fermentation tank 1. Here, the sugar concentration can be calculated, for example, by measuring the absorbance of the reaction solution present inside the saccharification and fermentation tank 1.

  Then, monitoring is continued until the monitored sugar concentration exceeds a predetermined numerical value (No in step S102). When the monitored sugar concentration exceeds a predetermined numerical value, the arithmetic and control unit 101 determines that the saccharification reaction has been completed (Yes in step S102).

  After the saccharification reaction is completed, yeast is charged into the saccharification and fermentation tank 1 (step S103). Then, while the temperature inside the saccharification fermenter 1 is adjusted to a temperature suitable for fermentation, appropriate stirring is performed. In addition, when the raw material to be fermented produces ethanol without being saccharified by fermentation, the step S102 becomes unnecessary. Thereby, the fermentation proceeds, and the production of ethanol is started from the sugar produced in step S102. After that, the arithmetic and control unit 101 monitors the concentration of ethanol present inside the saccharification and fermentation tank 1 using a sensor (not shown) provided in the saccharification and fermentation tank 1. Here, the concentration of ethanol can be calculated by, for example, specific gravity analysis, gas chromatography analysis, or the like of the reaction solution present inside the saccharification and fermentation tank 1.

  Then, the monitoring is continued until the monitored ethanol concentration exceeds a predetermined numerical value (No in step S104). When the monitored ethanol concentration exceeds a predetermined numerical value, the arithmetic and control unit 101 determines that the fermentation has been completed (Yes in step S104).

  Next, the contents (reaction liquid) of the saccharification and fermentation tank 1 are supplied to the solid-liquid separation device 2 by a pump (not shown), and solid-liquid separated (step S105). The liquid separated here is a low-concentration ethanol aqueous solution containing ethanol and water. Then, the liquid (low concentration ethanol aqueous solution) is transferred to the low concentration ethanol aqueous solution tank 3 (see FIG. 1) using a pump (not shown) (step S106). In the low concentration ethanol aqueous solution tank 3, the ethanol concentration in the low concentration ethanol aqueous solution tank 3 is measured using the sensor provided in the low concentration ethanol aqueous solution tank 3 (step S107). The measurement of the ethanol concentration can be performed in the same manner as the measurement of the concentration of ethanol existing inside the saccharification and fermentation tank 1 described above. Finally, the solid (fermentation residue) separated by the solid-liquid separation device 2 is processed (step S108).

  By the above flow, a low concentration ethanol aqueous solution is produced. Next, an operation method of the ethanol aqueous solution distillation column 4 and the engine 6 performed when the power generation system 100 (see FIG. 1) is started will be described with reference to FIG. It should be noted that the names and reference numerals of the devices correspond to the names and reference numerals of the devices shown in FIGS. 1 and 3, and the following description will be made with reference to FIGS. 1 and 3 as appropriate.

  FIG. 5 is a flowchart showing a method of operating the ethanol aqueous solution distillation column 4 and the engine 6 performed immediately after the startup of the power generation system 100. This flow is also performed by the arithmetic and control unit 101 as in the flow shown in FIG.

  When the power generation system 100 is started, first, the driving of the engine 6 (see FIG. 1) is started (ie, started). For this start-up, a high-concentration ethanol aqueous solution stored in a high-concentration ethanol aqueous solution tank 5 (see FIG. 1) (which may be supplementarily supplied from the outside) is used. However, an external fuel, such as light oil or gasoline, supplied from the outside may be used supplementarily. Here, the high-concentration ethanol stored in the high-concentration ethanol aqueous solution tank 5 is used, and the engine 6 is started (step S201).

  After the engine 6 is started, the warm-up operation of the engine 6 is performed for a while. After starting the engine 6, the arithmetic and control unit 101 (see FIG. 1) uses the temperature sensor 501 to determine whether or not the heat exchanger 402 for the cooling water has been warmed up. The outlet temperature is measured (Step S202). Further, the arithmetic and control unit 101 measures the outlet temperature of the heat exchangers 10, 405, and 403 (see FIG. 3) for the exhaust gas using the temperature sensors 502, 503, and 504 (see FIG. 3) (the same). Then, the arithmetic and control unit 101 determines whether or not all of the four measured temperatures are equal to or higher than the warm-up end temperature (each of which is a preset temperature) (step S203). As a result of this determination, if any one of the four measured temperatures is lower than the warm-up end temperature (No direction), the warm-up operation of the engine 6 is continued.

  On the other hand, if all of the four measured temperatures are equal to or higher than the warm-up end temperature (Yes direction), the low-concentration ethanol stored in advance in the low-concentration ethanol aqueous solution tank 3 (even if it is supplementarily supplied from the outside). (Good) is supplied to the reformer 11 (see FIG. 1) (step S204). Thereby, in the reformer 11, reforming of low-concentration ethanol is started, and generation of reformed gas (mainly hydrogen) is started. Incidentally, the components of the reformed gas generated here may be unstable immediately after the start of the generation. Therefore, from the viewpoint of promoting combustion, the reformed gas immediately after generation is supplied to the engine 6 together with the high-concentration aqueous ethanol solution. Incidentally, at this time, the operation of the distillation column 4 has not been performed yet.

  The ethanol concentration of the low-concentration aqueous ethanol solution supplied from the three low-concentration aqueous ethanol solutions is first adjusted by the ethanol concentration adjusting device 8. This adjustment is performed using a densitometer (not shown) provided in the ethanol concentration adjusting device 8. Then, the low-concentration aqueous ethanol solution whose ethanol concentration has been adjusted is heated in a stepwise manner by the heat exchangers 9 and 10 and then supplied to the reformer 11.

  After the start of the reforming, the arithmetic and control unit 101 measures the outlet gas component of the gas-liquid separator 12 using a measuring device (not shown) provided at the outlet of the gas-liquid separator 12. Then, the arithmetic and control unit 101 determines whether or not the reforming reaction is progressing stably based on the measurement result of the outlet gas component (step S205). Specifically, for example, when the amount of each component of the outlet gas is constant (for example, there may be a fluctuation range of about 10%), the reforming reaction proceeds stably (that is, in a steady state). You can judge.

  As a result of this determination, when it is determined that the reforming reaction is stable (Yes direction), the arithmetic and control unit 101 reduces the supply amount of the high-concentration ethanol aqueous solution that has been started to be supplied in step S201. (Step S206). Next, the arithmetic and control unit 101 starts to supply the reformed gas generated in the reformer 11 to the engine 6 as a main fuel (same as above). That is, here, both the reformed gas as the main fuel and the high-concentration ethanol as the auxiliary fuel are supplied to the engine 6.

  Here, the meaning of “main fuel” and “auxiliary fuel” will be described. In the power generation system 100, power generation according to power demand is performed. Specifically, an output target value of the engine 6 is set according to the power demand. Therefore, the reformed gas (main fuel) generated by the reformer 11 is supplied so that the output of the engine 6 can reach this output target value. However, even if the entire amount of the reformed gas generated by the reformer 11 is supplied to the engine 6, the output of the engine 6 may not reach the output target value (that is, the possibility that the reformed gas is insufficient). There is). Further, the amount of the reformed gas generated in the reformer 11 also changes due to the output fluctuation of the engine 6, and a time lag (time) occurs between the change in the generated amount and the timing of supplying the reformed gas to the engine 6. Delay).

  Therefore, in the power generation system 100, a high-concentration ethanol aqueous solution is used as an auxiliary. As a result, stable operation can be performed even if there is a change in power demand and a change in the output target value of the engine 6. Therefore, in this specification, the “main fuel” is a fuel (here, reformed gas) whose supply amount is controlled first. On the other hand, in the present specification, the “auxiliary fuel” refers to a fuel (here, a high-concentration aqueous ethanol solution) whose supply amount is controlled when the engine 6 does not reach the output target value with the main fuel alone (or may not easily reach the output target value). ).

  The amount of heat generated by the combustion of the reformed gas and the high-concentration ethanol aqueous solution is determined by the amount of hydrogen contained in the supplied reformed gas and the amount of carbon contained in the supplied high-concentration ethanol. It can be calculated based on each. Therefore, for example, the reformed gas and the high-concentration ethanol aqueous solution may be supplied based on the calculated calorific values. Further, as long as the output target value of the engine 6 is reached in step S206, the fuel may be completely switched from high-concentration ethanol to reformed gas. Then, the warm-up operation of the engine 6 is completed by the above steps S201 to S206.

  After the warm-up operation of the engine 6 is completed, the engine 6 is driven using the reformed gas as the main fuel and the high-concentration ethanol aqueous solution as the auxiliary fuel as described above. Next, the arithmetic and control unit 101 supplies the low concentration ethanol stored in the low concentration ethanol aqueous solution tank 3 to the ethanol aqueous solution distillation column 4 (see FIG. 1) (step S207). Next, the arithmetic and control unit 101 starts the total reflux operation of the ethanol aqueous solution distillation column 4 using the heat exchangers 404 and 405 (see FIG. 3) (step S208). By using the heat exchanger 404, the vapor at the top of the distillation column main body 401 (see FIG. 3) is condensed and liquefied. Further, by using the heat exchanger 405, the liquid at the bottom of the distillation column main body 401 (see FIG. 3) is heated and vaporized.

  After starting the full reflux operation of the ethanol aqueous solution distillation column 4, the arithmetic and control unit 101 determines whether the total reflux operation is stable by monitoring the reflux amount using a liquid amount sensor (not shown) (step). S209). As a result of the determination, when it is determined that the total reflux operation of the ethanol aqueous solution distillation column 4 is not stable (No direction), the arithmetic control unit 101 performs the same determination at predetermined time intervals until the total reflux operation is stabilized.

  On the other hand, when it is determined that the total reflux operation of the ethanol aqueous solution distillation column 4 is stable (Yes direction), the arithmetic and control unit 101 stops the total reflux operation and stops the high flow from the top of the distillation column main body 401. The extraction of the distillation residue from the concentrated ethanol aqueous solution from the bottom of the distillation column main body 401 is started (step S210). The extracted high-concentration ethanol aqueous solution is supplied to the engine 6 via the high-concentration ethanol aqueous solution tank 5 (see FIG. 1) and the like. Through these steps S207 to S210, the ethanol aqueous solution distillation column 4 is started.

  As described with reference to FIGS. 1 to 5 described above, according to the power generation system 100 of the first embodiment, the power generation by the power generator 7 can be performed with little or no external fuel. Efficiency and thermal efficiency are increased. That is, a high-concentration ethanol aqueous solution or a reformed gas (mainly hydrogen) is supplied to the engine 6, and these are easily combusted. Therefore, the combustion efficiency in the engine 6 is increased, and thereby the power generation efficiency is increased as compared with the conventional case.

  In particular, an ethanol aqueous solution having a low ethanol concentration is supplied to the reformer 11, converted into a reformed gas, and then supplied to the engine 6. Since the reforming in the reformer 11 is performed using the exhaust heat of the engine 6, it is advantageous in terms of overall energy of the power generation system 10. Therefore, the heat generated in the power generation system 100 is recovered without waste, and the power generation system 100 is advantageous in terms of thermal efficiency.

  Further, since the amount of fuel supplied from the outside is small or not required at all, fuel transportation costs (transport distance, etc.) are greatly reduced. That is, according to the power generation system 100 configured by connecting the respective devices continuously, the energy efficiency is improved.

  FIG. 6 is a system diagram of the power generation system 200 according to the second embodiment. In FIG. 6, the same components as those of the power generation system 100 of the first embodiment shown in FIG. 1 are denoted by the same names and reference numerals, and redundant description will be omitted.

  In the power generation system 200 shown in FIG. 6, unlike the power generation system 100 described above, a high-concentration ethanol aqueous solution extracted from the top of the ethanol aqueous solution distillation column 4 is supplied to the ethanol concentration adjusting device 8. That is, in the power generation system 100, as shown in FIG. 1, the low-concentration aqueous ethanol solution is supplied to the ethanol-concentration adjusting device 8 by branching from between the low-concentration aqueous ethanol solution tank 3 and the ethanol-containing water distillation column 4. Was. However, in the power generation system 200 shown in FIG. 6, the high-concentration aqueous ethanol solution branches off from the high-concentration ethanol aqueous solution tank 5 and the ethanol concentration adjusting device 14 as shown by the thick arrow in FIG. 8 is supplied.

  The low-concentration aqueous ethanol solution may contain various components in addition to ethanol and water. Then, among these components, components that may affect the performance of a reforming catalyst (not shown) provided in the reformer 11 may be included. Therefore, in the power generation system 200 shown in FIG. 6, by increasing the ethanol concentration in the ethanol aqueous solution distillation column 4, a high-concentration ethanol aqueous solution having a reduced content of components other than ethanol is supplied to the reformer 11. Accordingly, components that may affect the performance of the reforming catalyst provided in the reformer 11 are prevented from reaching the reformer 11, and the performance of the reforming catalyst is maintained. Thereby, the life of the reforming catalyst is extended, and the operating cost of the power generation system 200 is reduced.

  FIG. 7 is a system diagram of a power generation system 300 according to the third embodiment. In FIG. 7, the same components as those of the power generation system 100 of the first embodiment shown in FIG. 1 are denoted by the same names and reference numerals, and redundant description will be omitted.

  In the power generation system 300 shown in FIG. 7, unlike the above-described power generation systems 100 and 200, the vapor of the high-concentration ethanol aqueous solution is extracted from the top of the ethanol aqueous solution distillation column 4 as shown by a thick arrow in FIG. It is. Then, the extracted high-concentration ethanol vapor is supplied between the heat exchanger 9 and the heat exchanger 10 (that is, immediately before the heat exchanger 10). Therefore, a mixture of the low-concentration aqueous ethanol solution passed through the ethanol concentration adjusting device 8 and the high-temperature high-concentration aqueous ethanol solution (steam) extracted from the top of the ethanol aqueous solution distillation column 4 is supplied to the heat exchanger 10. You. Then, in the reformer 10, a mixture of low-concentration ethanol and high-concentration ethanol is reformed.

  FIG. 8 is a system diagram near the ethanol aqueous solution distillation column 4 and the engine 6 in the power generation system 300 of the third embodiment. In FIG. 8 as well, the same components as those of the power generation system 100 of the first embodiment shown in FIG. 3 are denoted by the same names and reference numerals, and redundant description will be omitted.

  In the power generation system 300, the steam is extracted from the top of the distillation column main body 401, and the extracted steam is supplied to the heat exchanger 404, similarly to the description of the power generation system 100. However, in this power generation system 300, in addition to the system in which the extracted steam is supplied to the heat exchanger 404, as shown by the thick arrow in FIG. A system is provided immediately before the stage 10.

  The steam extracted from the top of the distillation column main body 401 has a large amount of heat. Therefore, since the steam extracted from the top of the distillation column main body 401 is supplied immediately before the heat exchanger 10, the amount of heat used to heat the aqueous ethanol solution in the heat exchanger 10 is reduced. You. Therefore, the amount of heat of the exhaust gas supplied to the heat exchanger 10 can be reduced. As a result, the amount of heat of the exhaust gas can be used elsewhere. As a result, energy can be saved in the entire power generation system 300, and the energy efficiency of the entire power generation system 300 improves.

  Further, by extracting steam from the top of the distillation column body 401, the amount of steam extracted from the top of the column and supplied to the heat exchanger 404 also decreases. Thereby, the amount of the high-concentration aqueous ethanol solution (steam) condensed and liquefied in the heat exchanger 404 decreases, and the amount of the cold water used in the heat exchanger 404 decreases. Thereby, the power consumption of the chiller used for preparing the cold water can be reduced, and the heat exchanger 404 can sufficiently condense and liquefy even when, for example, the power generation system 300 is installed in an area with little water.

  Further, when it is desired to increase the ethanol concentration of the aqueous ethanol solution supplied to the reformer 11, the high-concentration aqueous ethanol solution in the distillation column main body 401 is supplied, so that the ethanol aqueous solution supplied to the reformer 11 becomes ethanol. The concentration is increased.

  FIG. 9 is a system diagram of a power generation system 400 according to the fourth embodiment. In FIG. 9, the same components as those of the power generation systems 100, 200, and 300 of the above-described embodiments will be denoted by the same names and reference numerals, and redundant description will be omitted.

  In the power generation system 400 shown in FIG. 9, a high-concentration ethanol aqueous solution (steam) is extracted from the top of the distillation column main body 401 as in the third embodiment (see FIG. 7). However, the high-concentration aqueous ethanol solution (steam) extracted here is supplied to the ethanol concentration adjusting device 8 as shown by a thick arrow in FIG. Then, the high-concentration aqueous ethanol solution supplied to the ethanol concentration adjusting device 8 is supplied to the reformer 11 via the heat exchangers 9 and 10. Therefore, in the reformer 11, the high-concentration ethanol aqueous solution (steam) extracted from the top of the distillation column main body 401 uses the heat of the exhaust gas of the engine 6 supplied through the exhaust heat supply system 53. , Are reformed.

  By doing so, similarly to the second embodiment, the content of impurities contained in the aqueous ethanol solution is reduced, and the life of the reforming catalyst provided in the reformer 11 is extended. Further, since the high-concentration ethanol aqueous solution (steam) extracted from the top of the distillation column main body 401 has a high temperature, the amount of heat provided by the heat exchangers 9 and 10 is reduced. Therefore, moderate heating is performed, so that the temperature of the aqueous ethanol solution supplied to the reformer 11 is easily stabilized.

  FIG. 10 is a system diagram near the ethanol aqueous solution distillation column 4 and the engine 6 in the power generation system 400 of the fourth embodiment. In FIG. 10 as well, the same components as those of the power generation system 100 of the first embodiment shown in FIG. 3 are denoted by the same names and reference numerals, and redundant description will be omitted.

  In the power generation system 400, a high-concentration ethanol aqueous solution (steam) is extracted from the top of the distillation column main body 401 as described above and as indicated by the thick arrow in FIG. The high-concentration ethanol aqueous solution (steam) has a large amount of heat. Therefore, similarly to the power generation system 300 described in the third embodiment, the amount of heat used for heating the ethanol aqueous solution in the heat exchanger 10 is reduced. Thereby, the energy efficiency of the entire power generation system 400 is improved, and furthermore, since gentle heating is performed, the temperature of the ethanol aqueous solution supplied to the reformer 11 is easily stabilized.

  As described above, the present invention has been described with reference to the four embodiments. However, the present invention is not limited to the above example. That is, the present invention can be implemented with appropriate modifications without departing from the spirit of the present invention. For example, the above embodiments can be implemented in appropriate combinations.

  Further, for example, in each of the above-described embodiments, the excess water stored in the excess water tank 13 is supplied to both of the ethanol concentration adjusting devices 8 and 14, but may be supplied to only one of them.

1 Saccharification and fermentation tank (fermentation equipment)
4 Ethanol aqueous solution distillation column (distillation device)
6. Engine (power generator)
7 generator (power generator)
8 Ethanol concentration controller 10 Heat exchanger (reformer)
11 Reformer (reformer)
12 Gas-liquid separator (reformed gas dehumidifier)
14 Ethanol concentration adjusting device 51 Reformed gas supply system 52 Exhaust heat supply system (engine exhaust heat first supply system)
53 Exhaust Heat Supply System (Engine Exhaust Heat Second Supply System)
54 Exhaust Heat Supply System (Engine Exhaust Heat Third Supply System)
55 Surplus water supply system (removed water supply system)
56 Return system 57 Used cooling water supply system (engine exhaust heat first supply system)
REFERENCE SIGNS LIST 100 Power generation system 101 Control unit 200 Power generation system 300 Power generation system 400 Power generation system 401 Distillation tower main body 402 Heat exchanger (second heat exchanger)
403 heat exchanger (second heat exchanger)
404 heat exchanger 405 heat exchanger (first heat exchanger)

Claims (7)

A fermentation apparatus that produces an aqueous ethanol solution by fermentation of biomass,
A distillation apparatus for increasing the ethanol concentration in the ethanol aqueous solution by distilling the ethanol aqueous solution obtained in the fermentation apparatus,
A power generator that includes an engine that burns an ethanol aqueous solution having an increased ethanol concentration in the distillation apparatus, and that generates power using power generated by the engine ;
An ethanol aqueous solution produced in the fermentation apparatus, and a reformer that produces a reformed gas containing hydrogen by reforming at least one of an ethanol aqueous solution having an increased ethanol concentration in the distillation apparatus.
A reformed gas supply system that supplies the reformed gas produced in the reformer to the power generator,
An engine exhaust heat first supply system that performs distillation in the distillation apparatus using the exhaust heat by supplying exhaust heat in the power generation apparatus to the distillation apparatus,
An engine exhaust heat second supply system that performs reforming in the reformer using the exhaust heat by supplying exhaust heat in the power generator to the reformer,
A reformed gas dehumidifier that removes moisture in the reformed gas produced in the reformer,
A power generation system, comprising: a removed water supply system that supplies water removed by the reformed gas dehumidifier to perform fermentation using water supplied in the fermenter . The distillation apparatus is a distillation column main body for performing distillation, a first heat exchanger connected to the bottom of the distillation column main body, and heats the liquid discharged from the column bottom of the distillation column main body, the first heat exchanger A vapor generated by being heated by the exchanger, and a return system for returning at least one of the remaining liquids to the distillation column main body,
2. The power generation system according to claim 1, wherein the heating in the first heat exchanger is performed using exhaust heat of the power generation device supplied through the engine exhaust heat first supply system. 3. . The distillation apparatus includes a second heat exchanger that heats the aqueous ethanol solution obtained in the fermentation apparatus,
The heating in the said 2nd heat exchanger is performed using the waste heat in the said electric power generator supplied through the said engine exhaust heat 1st supply system, The Claim 1 or 2 characterized by the above-mentioned. Power generation system. Using the water removed by the reformed gas dehumidifier, supplied to the reformer, the ethanol aqueous solution produced in the fermentation device, and the ethanol aqueous solution in which the ethanol concentration is increased in the distillation device of characterized in that it comprises ethanol concentration adjusting device for adjusting at least one of ethanol concentration, the power generation system of claim 1.   The system according to claim 1, further comprising an engine exhaust heat third supply system that performs fermentation in the fermentation device using the waste heat by supplying waste heat from the power generation device to the fermentation device. 3. The power generation system according to 2.   3. The power generation system according to claim 1, wherein the ethanol aqueous solution reformed by the reformer is an ethanol aqueous solution having an increased ethanol concentration in the distillation device. 4. The distillation apparatus includes a distillation column main body for performing distillation,
The vapor of the ethanol aqueous solution extracted from the top of the distillation column body is reformed in the reformer using waste heat supplied through the engine waste heat second supply system. The power generation system according to claim 1, wherein

Images