JP2013092065A - Complex type thermal power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system that can effectively use COand CO generated in a fuel combustion step in a thermal power house to suppress discharge them at the same time.SOLUTION: The system includes the thermal power house (1), a water-splitting photocatalyst hydrogen manufacturing facility (2), and a chemical synthesis facility (3). In the chemical synthesis facility (3), COand CO discharged from the thermal power house (1) and hydrogen generated in the water-splitting photocatalyst hydrogen manufacturing facility (2) are utilized as a source to elaborate an organic matter.

Description

The present invention relates to a combined power generation system capable of reducing emissions of CO ₂ that is a greenhouse gas generated in a thermal power generation facility and highly toxic CO into the atmosphere.

In thermal power plants, oil and the combustion of fossil fuels such as coal as a fuel, it is known to discharge the CO ₂ and CO (Non-Patent Document 1).

From the viewpoint of preventing global warming, it is desired that the emission of CO ₂ , which is a greenhouse gas, is suppressed, and the emission of CO is also desired to be suppressed due to its strong toxicity.

“Evolution of coal utility value and method”, [online], [October 24, 2011 search], Internet <URL: http://www.sekitanland.com/hg/index.htm>

If carbon dioxide gas (CO ₂ , CO) discharged from a thermal power generation facility can be effectively used as a raw material, it is possible to suppress the discharge of carbon dioxide gas at the same time, so such a system is ideal. .

Therefore, an object of the present invention is to provide a system that can effectively use CO ₂ and CO generated in a fuel combustion process of a thermal power generation facility and simultaneously suppress these emissions.

In order to solve the above problems, a combined thermal power generation system according to the present invention includes a thermal power generation facility, a water-splitting photocatalytic hydrogen production facility, CO ₂ and CO discharged from the thermal power generation facility, and the water-splitting photocatalyst production facility. It has a chemical synthesis facility for synthesizing organic substances using generated hydrogen as a raw material.

By making such a combined thermal power generation system, CO ₂ and CO discharged from the thermal power generation facility can be used as raw materials for organic matter synthesis such as methanol, and CO ₂ that is a greenhouse gas (or A clean combined power generation system that does not emit highly toxic CO) can be formed.

  Further, the combined thermal power generation system of the present invention makes it possible to obtain industrially useful organic matter such as methanol and reusable water that are effectively used as chemical energy.

  Preferably, the combined thermal power generation system further includes a seawater desalination facility using steam discharged from the thermal power generation facility as a heat source, and the fresh water produced by the seawater desalination facility is the water splitting photocatalyst manufacturing facility. To be supplied.

  Preferably, oxygen by-produced in the water splitting photocatalytic hydrogen production facility is supplied to the thermal power generation facility.

  Preferably, the organic substance is an alcohol or an alkane.

  Preferably, water by-produced in the chemical synthesis facility is supplied to the water splitting photocatalytic hydrogen production facility.

According to the present invention, an organic substance (methanol or the like) is produced by effectively using as a raw material the total amount of CO ₂ and CO discharged from a thermal power generation facility and the hydrogen gas generated in the water splitting photocatalytic hydrogen production facility. Organic substances such as methanol are stored and transported and used effectively separately. Thereby, carbon neutral can be achieved in the combined power generation system of the present invention.

Differences in CO ₂ and CO emissions due to differences in the fuel used in thermal power generation facilities (LNG, coal) can be dealt with by changing the scale of the power generation facility, and the amount of C emissions must be changed to organic matter. Is possible.

  In addition, water produced as a by-product in the chemical synthesis facility is supplied to the water-splitting photocatalytic hydrogen production facility and is effectively reused.

  Depending on the case (equipment environment), a seawater desalination facility is not required, and the facility can be made compact.

  In addition, it is possible to reduce the amount of input air for fuel combustion by using the oxygen by-produced in the water-splitting photocatalyst production facility to cover the fuel combustion field in the thermal power generation facility. ), And as a result, the amount of nitrogen oxide NOx generated from the thermal power generation facility is reduced.

2 is a flow sheet for explaining the combined thermal power generation system of the first embodiment. It is an internal schematic diagram explaining a combined cycle thermal power generation facility. It is the schematic which shows a water splitting photocatalyst hydrogen production equipment. 3 is a flow sheet for explaining a combined thermal power generation system according to a second embodiment. 6 is a flow sheet for explaining a combined thermal power generation system according to a third embodiment. It is an internal schematic diagram explaining thermal power generation equipment using a steam power generation system. 6 is a flow sheet for explaining a combined thermal power generation system according to a fourth embodiment.

  Hereinafter, the combined thermal power generation system of the present invention will be described in detail.

(Embodiment 1)
FIG. 1 is a flow sheet illustrating the combined thermal power generation system according to the first embodiment.

The combined thermal power generation system of Embodiment 1 includes a thermal power generation facility (1), a water splitting photocatalytic hydrogen production facility (2), and a chemical synthesis facility (3). The organic matter is synthesized using CO ₂ and CO discharged from the thermal power generation facility (1) and hydrogen generated in the water-splitting photocatalyst production facility (2) as raw materials.

As the thermal power generation facility (1), for example, a combined cycle thermal power generation including a gas turbine that rotates a turbine with a gas combusted with fuel and a steam turbine that rotates the turbine with steam generated by an exhaust heat recovery boiler for fuel combustion Is mentioned. Unlike the following Embodiments 2 to 4, the present Embodiment 1 is configured to use only CO ₂ and CO discharged from the thermal power generation facility (1) and the generated electric power. The use of steam in the facility is not essential.

  FIG. 2 is an internal schematic diagram illustrating a combined cycle thermal power generation facility.

The combined cycle thermal power generation system includes a generator (11), a gas turbine (12), and a steam turbine (13). The gas turbine (12) includes compressed air from an air compressor (14). Fuel (for example, LNG, petroleum, etc.) is introduced, and the gas turbine (12) rotates by the combustion of the fuel, and the generator (11) generates electric power by this rotation. Exhaust gas from the gas turbine (12) generated after fuel combustion is sent to an exhaust heat recovery boiler (15) where it is cooled by heat exchange with seawater or the like separately taken and sent to a denitration / desulfurization device (16). And then exhausted from the power generation facility. This exhaust contains CO ₂ and CO. Further, water such as seawater supplied to the exhaust heat recovery boiler (15) is converted into steam by heat exchange and sent to the steam turbine (13) to rotate the steam turbine (13), and then in the state of steam. Get out of the power generation facility.

  The water splitting photocatalytic hydrogen production facility (2) is a facility that decomposes water into hydrogen and oxygen by the action of sunlight and a photocatalyst.

  FIG. 3 is a schematic view showing a water-splitting photocatalytic hydrogen production facility.

The water-splitting photocatalytic hydrogen production facility (2) includes an upper anode chamber (21) and a lower cathode chamber (22) connected to the anode chamber (21) at one end side. The anode chamber (21), the anode photocatalyst having a catalytic action to produce oxygen by sunlight _{(e.g., TaON, Ta 3 N 5,} TiO 2-x N x, etc. BiVO _4, WO ₃₎ (23) is an anode The cathode chamber (22) is provided with a cathode catalyst (for example, Pt) (24) having a catalytic action for generating hydrogen as a cathode.

  Water is introduced into the anode chamber (21) from the upper end on one end side, passes from the communication path on one end side to the cathode chamber (22), and exits from the water splitting photocatalytic hydrogen production facility (2) via the lower end on the other end side.

  When electric power from the thermal power generation facility (1) is supplied to the power source (25) and irradiated with sunlight, oxygen is generated by the catalytic action of the anode photocatalyst (23). The generated oxygen is discharged from a vent hole (26) provided at the upper center of the anode chamber (21). In the cathode chamber (22), hydrogen is generated by the catalytic action of the cathode catalyst (24). The generated hydrogen is discharged from the other end side of the cathode chamber (22) through a section (27) provided in a predetermined section at the center of the cathode chamber (22).

The chemical synthesis facility (3) is supplied with carbon dioxide gas (CO ₂ , CO) and electric power from the thermal power generation facility (1), and supplied with hydrogen from the water-splitting photocatalytic hydrogen production facility (2). As a result, organic substances are synthesized.

  An example of the organic substance to be synthesized is methanol. In this case, methanol is produced according to the following formula using a Cu / ZnO-based catalyst.

CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O (1)
CO + 2H ₂ → CH ₃ OH (2)
Water that is a by-product in this reaction may be reused in the water-splitting photocatalytic hydrogen production facility (2).

  Next, the case where the combined thermal power generation system of the first embodiment is used will be specifically described as Example 1.

Example 1
A combined cycle thermal power generation facility was used as the thermal power generation facility (1). The power generation efficiency based on the higher heating value (HHV standard) was 50%, and liquefied natural gas (LNG), petroleum, etc. were used as the thermal power generation fuel. The power generation scale (output) was 250 MW.

Regarding the water-splitting photocatalytic hydrogen production facility (2), the solar energy conversion efficiency is 4%, the facility (photocatalytic electrode) area is 28,000 m ² (for example, 5 km × 5.6 km), and the power consumption in the field is 2 × 10 ⁶ kWh / Day, hydrogen production scale (output): 350 t / day-H ₂ .

Assuming that the sunshine duration is 8 h and a certain degree of solar radiation intensity (6 kWh / m ² / day) is obtained, 3200 t of fresh water in the daytime is decomposed into hydrogen (350 t) and oxygen by the water splitting photocatalyst facility (2). At that time, the amount of power consumed in the field is estimated to be 2,000 MWh / day mainly by an auxiliary power amount for promoting the reaction.

The chemical synthesis facility (3) is a methanol synthesis facility, the reaction temperature is 250 ° C., the reaction pressure is 5 MPa, and the synthesis catalyst is Cu / ZnO / (oxide). Here, the oxide _is one or more combinations of such _{Al 2 O 3, ZrO 2,} Ga 2 O 3, Cr 2 O 3. The methanol production capacity in this facility is 1,800 t / day-CH ₃ OH.

  Based on the above conditions, the amount of power generation per day of the thermal power generation facility (1) is 6,000 MWh / day. For this reason, the required input fuel energy is 12,000 MWh considering the power generation efficiency of 50%. / Day.

Assuming liquefied natural gas (LNG) as the fuel, the unit calorific value is 55 MJ / kg (ie 15 kWh / kg) (http://www.ecofukuoka.jp/image/custom/data/santei/hatunetu. pdf), the required input fuel is 800 t / day. The main component of LNG is methane (C: 75%), and its C component is considered to be about 80%. Therefore, assuming that the C component is completely converted into CO ₂ and CO by combustion, the generated CO ₂ The total number of moles of CO and CO is expected to be 53 × 10 ⁶ mol / day. As shown in the above formulas (1) and (2), when methanol synthesis is carried out, the number of moles of methanol produced is equivalent to the total number of moles of CO ₂ and CO, 53 × 10 ⁶ mol / day (1700 t / day). ). The amount of hydrogen gas required for this reaction is estimated to be 107 × 10 ^{6 to} 160 × 10 ⁶ mol / day (210 to 320 t / day), and the amount of hydrogen produced by the chemical synthesis facility (3) should be sufficient. I understand. That is, by using this system, it is suggested that CO ₂ and CO discharged from the thermal power generation facility can be completely converted into methanol.

(Embodiment 2)
FIG. 4 is a flow sheet for explaining the combined thermal power generation system of the second embodiment.

The combined thermal power generation system according to Embodiment 2 includes a thermal power generation facility (1), a water-splitting photocatalytic hydrogen production facility (2), a chemical synthesis facility (3), and a desalination facility (4). The chemical synthesis facility (3) synthesizes organic substances using CO ₂ and CO discharged from the thermal power generation facility (1) and hydrogen generated in the water-splitting photocatalyst production facility (2) as raw materials. The desalination facility (4) uses the steam discharged from the thermal power generation facility (1) as a heat source, and the fresh water produced by the desalination facility (4) is supplied to the water-splitting photocatalyst production facility (2). .

  Since the thermal power generation facility (1), the water-splitting photocatalytic hydrogen production facility (2), and the chemical synthesis facility (3) are the same as those in the first embodiment, detailed description thereof is omitted.

  The desalination facility (4) is not particularly limited as long as it can produce fresh water from seawater using steam from the thermal power generation facility (1) as a heat source. For example, the multi-stage flash method, the multi-effect method Equipment using such as. Moreover, the electric power for driving the desalination facility (4) is supplied from the thermal power generation facility (1).

  The fresh water produced by the desalination facility (4) is supplied to the water splitting photocatalytic hydrogen production facility (2).

  While fresh water generated in the daytime is supplied to the water-splitting photocatalytic hydrogen production facility (2) and used for hydrogen production, fresh water generated at night is effectively used as domestic water for drinks and industrial water. .

  Next, the case where the combined thermal power generation system of the second embodiment is used will be specifically described as Example 2.

(Example 2)
Since the thermal power generation facility (1), the water-splitting photocatalytic hydrogen production facility (2) and the chemical synthesis facility (3) are the same as those in the first embodiment, detailed description thereof will be omitted.

The desalination facility (4) is a multi-stage flash (MSF) seawater desalination facility. Water production ratio: 6 to 10 (about 8), on-site power consumption: 4 kWh / m ³ -production fresh water, fresh water production scale (output): 400 t / h.

  The required amount of steam in the desalination system (introduction temperature 200 ° C.) is 40 to 67 t / h from the water production ratio, and it is possible to consider the amount (450 t / h) derived from the thermal power generation facility (1). . In addition, the amount of power consumed in the field when producing fresh water (9,600 t / day) is estimated to be 38.4 MWh / day.

  Based on the above conditions, the amount of power generation per day of the thermal power generation facility (1) is 6,000 MWh / day. For this reason, the required input fuel energy is 12,000 MWh considering the power generation efficiency of 50%. / Day.

Assuming liquefied natural gas (LNG) as the fuel, the unit calorific value is 55 MJ / kg (ie 15 kWh / kg) (http://www.ecofukuoka.jp/image/custom/data/santei/hatunetu. pdf), the required input fuel is 800 t / day. The main component of LNG is methane (C: 75%), and its C component is considered to be about 80%. Therefore, assuming that the C component is completely converted into CO ₂ and CO by combustion, the generated CO ₂ The total number of moles of CO and CO is expected to be 53 × 10 ⁶ mol / day. As shown in the above formulas (1) and (2), when methanol synthesis is carried out, the number of moles of methanol produced is equivalent to the total number of moles of CO ₂ and CO, 53 × 10 ⁶ mol / day (1700 t / day). ). The amount of hydrogen gas required for this reaction is estimated to be 107 × 10 ^{6 to} 160 × 10 ⁶ mol / day (210 to 320 t / day), and the amount of hydrogen produced by the chemical synthesis facility (3) should be sufficient. I understand. That is, by using this system, it is suggested that CO ₂ and CO discharged from the thermal power generation facility can be completely converted into methanol.

(Embodiment 3)
FIG. 5 is a flow sheet for explaining the combined thermal power generation system of the third embodiment.

  In the third embodiment, coal is used as fuel for the thermal power generation facility (1 '), and accordingly, a steam power generation system is used.

  Since other configurations are the same as those of the second embodiment, detailed description thereof is omitted.

  FIG. 6 is an internal schematic diagram illustrating a thermal power generation facility (1 ′) using a steam power generation system.

The steam power generation system includes a generator (17), a steam turbine (18), and a boiler (19). Air, oxygen, and fuel (coal) are introduced into the boiler (19), and the fuel burns. Steam from the boiler (19) is supplied to the steam turbine (18) to rotate the turbine. Steam supplied to the steam turbine (18) is circulated with the boiler (19). Exhaust gas generated by fuel combustion in the boiler (19) is sent to the denitration / desulfurization device (20) and then exhausted from the power generation facility. This exhaust contains CO ₂ and CO. A part of the steam circulating between the boiler (19) and the steam turbine (18) is taken out and supplied to the desalination facility (4).

  Next, the case where the combined thermal power generation system of the third embodiment is used will be specifically described as Example 3.

(Example 3)
By changing to the steam power generation system, the power generation efficiency is changed to 40%. Further, the output scale is reduced to 100 MW in consideration of the amount of C component of the exhaust gas. Since the other points are the same as those of the second embodiment, detailed description thereof is omitted.

  The power generation amount per day of the thermal power generation facility (1) is 2,400 MWh / day, and the input fuel energy necessary for this is 6,000 MWh / h in consideration of the power generation efficiency of 40%.

Assuming coal as the fuel, the unit calorific value is 27 MJ / kg (ie, 7.4 kWh / kg (see http://www.ecofukuoka.jp/image/custom/data/santei/hatunetu.pdf)) The required input fuel is 813 t / day, and the C component contained in the coal differs depending on the type of coal, and the C component in the coal types mainly used in thermal power generation (subbituminous coal, brown coal) is about Therefore, assuming that the C component is completely converted into CO ₂ and CO by combustion, the total number of moles of CO ₂ and CO generated is 47 × 10 ^{6 to} 58 × 10 ^6. When methanol synthesis is performed as shown in the above reaction formulas (1) and (2), the number of methanol produced is equivalent to the total number of moles of CO ₂ and CO, 47 × 10 ^{6 to} 58 × ¹⁰ 6 mol / day (1500 1800t is / day). Hydrogen gas amount required in this reaction is converted with ^{95 × 10 6 ~170 × 10 6} mol / day (190~350t / day), water decomposition photocatalytic hydrogen production equipment (2) In other words, it is suggested that the CO ₂ and CO discharged from the thermal power generation facility can be converted into methanol entirely by using this system.

(Embodiment 4)
FIG. 7 is a flow sheet for explaining the combined thermal power generation system of the fourth embodiment.

  In the fourth embodiment, oxygen produced as a by-product in the water-splitting photocatalytic hydrogen production facility (2) is supplied to the thermal power generation facility (1) and used in the fuel combustion process. Thereby, NOx emission reduction from a thermal power generation facility is achieved.

  Since other points are the same as those of the second embodiment, detailed description thereof is omitted.

1 Thermal power generation facility 2 Water splitting photocatalytic hydrogen production facility 3 Chemical synthesis facility

Claims (5)

A thermal power generation facility, a water-splitting photocatalytic hydrogen production facility, a chemical synthesis facility that synthesizes organic substances using CO ₂ and CO discharged from the thermal power generation facility and hydrogen generated in the water-splitting photocatalyst production facility as raw materials, A combined thermal power generation system characterized by comprising:   The seawater desalination facility that uses steam discharged from the thermal power generation facility as a heat source is further provided, and fresh water produced by the seawater desalination facility is supplied to the water splitting photocatalyst production facility. Combined thermal power generation system.   The combined thermal power generation system according to claim 1 or 2, wherein oxygen by-produced in the water-splitting photocatalytic hydrogen production facility is supplied to the thermal power generation facility.   The combined organic power generation system according to any one of claims 1 to 3, wherein the organic substance is an alcohol or an alkane.   The combined thermal power generation system according to any one of claims 1 to 4, wherein water by-produced in the chemical synthesis facility is supplied to the water-splitting photocatalytic hydrogen production facility.

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