JP2022177773A - Hydrogen production system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen production system capable of generating hydrogen economically by electrolysis using plant wastewater from a combustion furnace plant.

SOLUTION: A hydrogen production system 1 comprises: a boiler-equipped combustion system 10 that is used in a combustion furnace plant and includes at least a combustion furnace and a boiler that generates steam using heat from combustion performed in the combustion furnace; an electrolysis system 50 that at least includes an ion elimination device 52 that generates, from boiler blow water F1 discharged from the boiler, separated water F2 by introducing at least a portion of the boiler blow water and removing unnecessary ions therefrom, and removed water F3 that contains the unnecessary ions, and a water electrolysis device 53 that generates hydrogen by electrolyzing the separated water; and a wastewater processing system 30 that includes at least an inorganic wastewater processing facility 32 for performing inorganic water processing on plant wastewater containing the remainder of the boiler blow water and generated in the combustion furnace plant.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a hydrogen production system that produces hydrogen using a combustion furnace such as a refuse incinerator equipped with a boiler.

In recent years, decarbonization as a countermeasure against global warming is gaining momentum worldwide, and attention is being focused on technologies for reducing carbon dioxide emissions and hydrogen production technologies that do not emit carbon dioxide. In Japan, the Ministry of the Environment has declared that the emission of greenhouse gases will be substantially zero by 2050 (carbon neutral). In response to this, domestic companies are promoting various initiatives to achieve the target.

For example, a methane fermentation apparatus that decomposes organic waste to produce biogas emits carbon dioxide together with methane gas. The ratio of carbon dioxide in the total biogas produced by the methane fermentation apparatus is about two-thirds by weight, although it depends on the composition of the organic waste. Specifically, when about 2 tons of methane gas is produced, about 4 tons of carbon dioxide are produced at the same time. Therefore, in order to reduce the amount of carbon dioxide emissions, technologies such as separating carbon dioxide from biogas and using it in plant factories, and technology to mix ash from waste incinerators with carbon dioxide and make it into cement materials are being developed. has been developed (see Patent Document 1).
In addition, the carbon dioxide produced by the methane fermentation and the hydrogen produced by the water electrolyzer are used for methanation (methane synthesis), and the produced methane is used as city gas, and as a fuel for gas engines, etc. A technique utilizing methane has also been developed (see Patent Document 2).
Furthermore, a technology has been developed in which a water electrolyzer is installed in a waste incinerator plant, ammonia is synthesized from the hydrogen produced by the water electrolyzer and nitrogen in the air, and the ammonia is used as fuel for gas engines, etc. (See Patent Document 3).

JP-A-2006-212524 Japanese Patent Application Laid-Open No. 2019-090084 Japanese Patent Application Laid-Open No. 2019-216501

The amount of carbon dioxide used in the plant factory and cement synthesis described in Patent Literature 1 is not large enough to consume all the carbon dioxide generated in the methane fermentation. On the other hand, according to the methanation described in Patent Document 2, a large amount of carbon dioxide can be converted into high-demand methane, which is commercially beneficial. On the other hand, a large amount of electric power and water are required to generate hydrogen for methanation in a water electrolyzer. Therefore, as described in Patent Document 3, the power generated by the steam turbine and generator of the boiler provided in the waste incineration plant and the cooling waste water of the desuperheating tower for reducing the temperature of the exhaust gas are used to It is conceivable to implement nationalization.
However, in order to efficiently generate hydrogen in a water electrolyzer, it is necessary to use water containing no impurities. Regarding this point, in the technique of Patent Literature 3, a temperature reduction tower, which is a so-called scrubber, is installed upstream of the dust collector, and cooling wastewater after temperature reduction is supplied to the water electrolysis device. However, since this cooling wastewater contains fly ash, heavy metals, and chemicals for exhaust gas treatment, it cannot be directly supplied to the water electrolysis apparatus.

On the other hand, the wastewater from the waste incinerator plant consists of wastewater from washing the platform for throwing the waste collected by the waste collection truck into the waste pit, wastewater from the waste stored in the waste pit, and bottom ash from the waste incinerator. There is also waste water from an ash extruder that cools and discharges. However, the wastewater from the platform and the waste pit contains organic components, and the wastewater from the ash extruder contains inorganic components.

Therefore, when a water electrolyzer is installed in a waste incinerator plant, which is a kind of combustion furnace plant, and the wastewater generated in the plant (plant wastewater) is used for the water electrolyzer, the general wastewater treatment that the plant generally has It is common practice to combine all plant wastewater, such as wastewater from platforms and waste pits, and wastewater from ash extruders, into the system, and use the water that has been treated to remove organic and inorganic components in the water electrolysis system. It was technical common sense of a trader.
The integrated wastewater treatment system is also installed in plants other than waste incinerator plants, such as thermal power plants and chemical plants, as long as it is a combustion furnace plant equipped with a combustion furnace and a boiler.

The present invention has been devised in view of the above problems, and reduces the load of water treatment of a comprehensive wastewater treatment system, and economically by electrolysis using plant wastewater generated in a combustion furnace plant. An object of the present invention is to provide a hydrogen production system capable of producing hydrogen.

The hydrogen production system of the present invention is applied to a combustion furnace plant,
a boiler-equipped combustion system comprising at least a combustion furnace and a boiler that generates steam from heat burned in the combustion furnace;
an ion removing device for generating separated water from which unnecessary ions are removed by introducing at least a portion of the boiler blow water discharged from the boiler and water to be separated containing the unnecessary ions; an electrolysis system comprising at least a water electrolyzer that generates hydrogen by electrolyzing water;
and a waste water treatment system including at least an inorganic waste water treatment facility that performs inorganic water treatment on plant waste water generated in the combustion furnace plant and containing the remainder of the boiler blow water.

According to the hydrogen production system of the present invention, water electrolysis is performed using part of the boiler blow water, which is particularly clean although it contains low-concentration chemicals, among the plant wastewater generated in the combustion furnace plant. At least a part of the boiler blow water subjected to water electrolysis does not enter the waste water treatment system, so the load of water treatment in the waste water treatment system can be reduced.
Therefore, it is possible to provide a hydrogen production system that can reduce the water treatment load of the waste water treatment system and can economically produce hydrogen by electrolysis using plant waste water generated in the combustion furnace plant.

It is a block diagram showing an example of a hydrogen production system of the present invention. FIG. 4 is a block diagram showing a first modified example of the hydrogen production system of the present invention; 4 is a block diagram showing an example of a carbon dioxide separator 60. FIG. FIG. 4 is a block diagram showing part of a second modified example of the hydrogen production system of the present invention; FIG. 11 is a block diagram showing part of a third modified example of the hydrogen production system of the present invention;

Hereinafter, hydrogen production systems of embodiments and modified examples (first, second and third modified examples) will be described with reference to FIGS. 1 to 5. FIG. In the figure, numerals only represent physical elements such as devices, parts, and parts related to the hydrogen production system. Also, a symbol combining an alphabetic character F and a number represents a fluid such as a liquid or a gas generated in the hydrogen production system.

The examples and modifications shown below are merely examples, and are not intended to exclude various modifications and application of techniques that are not explicitly stated. Each configuration described below can be modified in various ways without departing from the scope of the invention. In addition, each of the following configurations can be selected or discarded as required except for the configurations essential to the present invention, or can be combined with known configurations.

[1. Example and first modified example]
FIG. 1 is an embodiment of the invention, and FIG. 2 is a first modification of the invention. The hydrogen production system 1 of the embodiment and the first modification includes a combustion system 10 with a boiler, a waste water treatment system (comprehensive waste water treatment system) 30, a high-purity carbon dioxide generation system 40, and an electrolysis system 50 (first modification 50') and a methanation system 72.
Since the embodiment and the first modification differ only in the configuration of the electrolysis systems 50, 50' provided in the hydrogen production system 1, the embodiment and the first modification will be described simultaneously.
These systems 10, 30, 40, 50 (50'), and 72 may all be installed in one building, or may be installed in individual buildings corresponding to each system. Also, all of these systems may be located at the same site, or may be located at separate sites, eg, sites remote from each other. When each system is installed on a site far away from each other, each system may be appropriately connected by a pipeline, car transportation, or the like.

[A. Basic configuration]
First, the five systems 10, 30, 40, 50 (50'), and 72 described above will be outlined, and then the specific configuration and effect of each system will be described in detail.
The boiler-equipped combustion system 10 is a system that includes at least a combustion furnace and a boiler that generates steam from the heat of combustion in the combustion furnace. The combustion furnace plant to which the hydrogen production system 1 is applied is diverse, such as a garbage incinerator plant, a thermal power plant, and a chemical plant, depending on the fuel (waste, coal, etc.) burned in the combustion furnace and its purpose. .
Since the boiler-equipped combustion system 10 includes the boiler 20, boiler blow water F1, which will be described later, is always discharged.
In addition, in the embodiment and the first modified example, the boiler-equipped combustion system 10 includes the refuse incinerator 13 as an example of a combustion furnace.

The wastewater treatment system 30 is the integrated wastewater treatment system described in [Problems to be Solved by the Invention]. An organic wastewater treatment facility 31 that treats organic components contained in plant wastewater by biological treatment or the like, and an inorganic wastewater treatment plant 32 that treats inorganic components contained in plant wastewater after the organic components are treated. and In the wastewater treatment system 30, water treatment is performed to purify the wastewater to the extent that it can be discharged to the outside of the combustion furnace plant. The plant wastewater treated by the wastewater treatment system 30 may be used in the combustion furnace plant as reused water F14, which will be described later, or may be discharged outside the combustion furnace plant if there is a surplus.
Since the hydrogen production system 1 of the embodiment and the first modification shows an example applied to a waste incinerator plant, which is a kind of combustion furnace plant, the wastewater treatment system 30 is an organic wastewater treatment facility 31. Both inorganic wastewater treatment facilities 32 are provided. However, in a combustion furnace plant in which organic components are not contained in the plant wastewater, such as a thermal power plant, the wastewater treatment system 30 may not include the organic wastewater treatment facility 31 and may only include the inorganic wastewater treatment facility 32. .

The high-purity carbon dioxide generation system 40 is a system that generates high-purity carbon dioxide without a special concentration process. As described in [Background Art], a large amount of high-purity carbon dioxide is generated during methane fermentation, so the high-purity carbon dioxide generation system 40 of FIGS. 42 at least.
In addition to the methane fermentation device 42, the high-purity carbon dioxide generation system 40 includes an alcohol fermentation device 66 (described later using FIG. 4 as a second modification), a gasification furnace 69 for gasifying woody biomass (a third modification) (described later with reference to FIG. 5) may be included at least.

The methanation system 72 uses as raw materials at least carbon dioxide F7 produced by the high-purity carbon dioxide production system 40 and hydrogen F4 produced by the water electrolysis device 53 of the electrolysis system 50 described later, and methanation is performed by the methanation device 46. and produce methane F12.

The electrolysis system 50 is a system that generates hydrogen F4 by electrolysis using boiler blow water F1. The electrolysis system 50 includes at least an ion removal device 52 that removes unnecessary ions from the boiler blow water F1 and a water electrolysis device 53 .
Although the water supplied to the boiler 20 is pure water F15, for example, chemicals such as a boiler agent, anticorrosive agent (oxygen absorber), and scale inhibitor are added at a low concentration, and water stored in the boiler 20 is added. is adjusted to be slightly alkaline. For this reason, the boiler blow water F1 has conventionally been mixed with other plant wastewater containing a large amount of impurities such as high-concentration chemicals and ash, and treated in general wastewater treatment facilities.
However, the water stored in the boiler 20 is pure water F15 to which a low-concentration chemical is added, does not contain ash or heavy metals, and is different from other plant waste water in a plant equipped with a combustion furnace. Therefore, if the boiler blow water F1 discharged from the boiler 20 at any time is used in the water electrolysis device 53 that requires the pure water F15, hydrogen F4 can be efficiently and economically produced. The inventor thought that it could be done.
Therefore, based on the configuration in which the boiler blow water F1 is used to generate hydrogen F4 in the water electrolysis device 53, the hydrogen F4 generated in the water electrolysis device 53 can be used to generate valuable substances such as methane F12. We invented a hydrogen production system 1 that can reduce carbon dioxide F18 emitted from a combustion furnace plant, in other words, a hydrogen production system 1 that enables the realization of a decarbonized society, which is a recent global environmental issue.
The outlines of the five systems 10, 30, 40, 50 (50'), and 72 provided in the embodiment and the first modification have been described above. Therefore, the configuration and effect of each system will be described in detail below.

[B. Detailed configuration]
Now, the details of the hydrogen production system 1 will be described with reference to FIGS. 1 and 2. FIG. As described above, the embodiment and the first modification are examples in which the hydrogen production system 1 of the present invention is applied to a refuse incinerator plant among combustion furnace plants.
A refuse incinerator plant is, for example, a facility for incinerating refuse such as municipal refuse and industrial waste, that is, waste. The boiler-equipped combustion system 10 includes a platform 11, which is a space where a garbage delivery vehicle (garbage truck, truck, dump truck, etc.) unloads waste, and a temporary space where waste unloaded from the garbage delivery vehicle is put. A garbage pit 12 (garbage storage tank) is provided in which the garbage is systematically stored. The waste thrown into the garbage pit 12 is transferred to the garbage incinerator 13 by a garbage crane.
Since the wastewater that washed the platform 11 (platform washing wastewater) and the wastewater that seeped out from the waste stored in the waste pit 12 (pit wastewater) generally contain organic components, the organic matter of the wastewater treatment system 30 is treated as plant wastewater. The water is treated at the system wastewater treatment facility 31 .

The refuse incinerator 13 is a furnace for incinerating waste, such as a stoker furnace or a fluidized bed furnace. The ash extrusion device 14 is a device for cooling and discharging incineration ash (main ash) remaining after incinerating waste in the refuse incinerator 13 . Wastewater discharged from the ash extruder 14 (ash extruder wastewater) is alkaline water containing ash and heavy metals, and is treated as plant wastewater in the inorganic wastewater treatment facility 32 of the wastewater treatment system 30 . The inorganic wastewater treatment facility 32 also receives and treats wastewater that has been treated in the organic wastewater treatment facility 31 .

Exhaust gas generated by the combustion of waste in the waste incinerator 13 passes through a flue 15 and flows through a cooling tower 16 that reduces the temperature of the exhaust gas, a dust remover 17 that removes fly ash from the exhaust gas, and a chimney 19 in that order. released to the outside air. Here, in the flue 15 between the dust remover 17 and the chimney 19, a carbon dioxide separation device 60 for separating low-concentration carbon dioxide F18 contained in the exhaust gas is arranged. If necessary, a denitrification device, an induced draft fan, or the like (not shown) may be installed in the flow path of the exhaust gas.

Dust (fly ash) removed by a dust remover 17 such as a bag filter is washed by a fly ash washing device 18, stored in a fly ash pit (not shown), and carried out of the plant. Wastewater (washing wastewater) discharged from the fly ash washing device 18 is alkaline water containing ash and heavy metals, and is treated as plant wastewater in the inorganic wastewater treatment facility 32 of the wastewater treatment system 30 .
In the temperature reduction tower 16, if the plant wastewater (reused water F14) that has been water-treated in the inorganic wastewater treatment facility 32 of the wastewater treatment system 30 is sprayed to reduce the temperature of the exhaust gas, tap water is sprayed. superior in terms of cost-effectiveness. Here, the cooling tower 16 is not the scrubber of Patent Document 3, but the cooling tower 16 generally used in a refuse incinerator plant. A desuperheating tower 16 in which the off-gas is substantially completely vaporized is desirable. Since substantially all of the sprayed water evaporates, plant wastewater is not discharged from the temperature reducing tower 16, and the load of water treatment in the wastewater treatment system 30 can be reduced.
In the fly ash washing device 18, if dust (fly ash) is washed with plant wastewater (recycled water F14) that has been water-treated in the inorganic wastewater treatment facility 32 of the wastewater treatment system 30, the dust (fly ash) is washed with tap water. It is superior in terms of cost-effectiveness compared to

The boiler 20 includes a water purifier 27 that produces pure water F15 from tap water, industrial water, or the like, and the pure water F15 produced by the water purifier 27 is added with a boiler agent, an anticorrosive agent (oxygen absorber), a scale inhibitor, and the like. A chemical addition device 28 that adds the chemical, a steam drum 21 that stores pure water F15 to which the chemical is added, and a heat transfer tube, a superheater tube, etc. that converts the water stored in the steam drum 21 into steam with the heat of the exhaust gas. A heat recovery device 22, a steam turbine 23 that rotates an impeller with the steam generated by the exhaust heat recovery device 22 and supplied to the steam drum 21, a power generator 24 that generates power by the rotational force of the impeller of the steam turbine 23, and a steam turbine. A condenser 25 for returning the steam (waste steam) after rotating the impeller 23 to water, a steam drum by removing dissolved gas (oxygen, carbon dioxide, etc.) from the condensate generated by the condenser 25 A deaerator 26 feeding 21 is provided.
The boiler blow water F1 is discharged as needed from the blow pipe 29 arranged below the steam drum 21 .
Since the waste steam has a high temperature, it is appropriately supplied to devices that require heating in the plant, such as the carbon dioxide separation device 60, the methanation device 46, and the pretreatment device 41 (in the case of solubilization and hydrothermal treatment), which will be described later. It is more cost-effective than using electricity purchased from an electric power company for heating.

The power generated by the generator 24 is used to operate various electric appliances (water electrolyzer 53, electrolyzer 54, methanation device 46, etc.) installed in the plant, and surplus power is supplied to the electric power company. You can sell electricity. The electric power is not sold to the electric power company, or the amount of electric power sold is small, and all or most of the electric power is appropriately designed to be supplied to various electric appliances arranged in the plant to which the hydrogen production system 1 is applied. By doing so, it is possible to construct a combustion furnace plant that is substantially power independent.
In addition, if the plant waste water (reused water F14) that has been water-treated in the inorganic waste water treatment facility 32 of the waste water treatment system 30 is supplied to the water purifier 27 and the pure water F15 is produced by the water purifier 27, tap water It is superior in terms of cost effectiveness compared to supplying

The carbon dioxide separation device 60 is, for example, a device that separates carbon dioxide using an amine solution, as shown in FIG. If it is possible in terms of design, it may have the same configuration as the carbon dioxide separation membrane 45 described later.
The carbon dioxide separator 60 of FIG. 3 has an absorber 61 , a heat exchanger 62 , a desorber 63 and a reheater 64 .

The absorber 61 is a device for causing the amine solution to absorb the carbon dioxide F18 in the exhaust gas. Inside the absorber 61, a relatively cold amine solution is injected toward the exhaust gas. The amine solution that has absorbed carbon dioxide F18 falls downward inside the absorber 61 and is introduced into the heat exchanger 62 . Further, the exhaust gas from which the carbon dioxide F18 has been removed flows out from above the absorber 61 and is discharged from the chimney 19 into the atmosphere.
The heat exchanger 62 is a device for raising the temperature of the amine solution discharged from the absorber 61 . A relatively high-temperature amine solution discharged from a desorber 63, which will be described later, is introduced into the heat exchanger 62 as a heat source. The heat in the hot amine solution is transferred inside heat exchanger 62 to the cold amine solution. The temperature-raised amine solution (amine solution containing carbon dioxide F18) is introduced into the desorber 63 .
The desorber 63 is a device for desorbing carbon dioxide F18 from the amine solution. The amine solution introduced into the desorber 63 is sprayed inside the desorber 63 . As a result, the carbon dioxide F18 absorbed in the amine solution is desorbed, flows out from above the desorber 63 and is retained in the carbon dioxide retention tank 49 .
The desorber 63 is provided with a reheater 64 for heating the introduced amine solution while circulating it. In the reheater 64, for example, waste steam from the steam turbine 23 may be used to raise the temperature of the amine solution.
The carbon dioxide separation device 60 and the carbon dioxide storage tank 49 can significantly reduce the amount of carbon dioxide F18 in the exhaust gas discharged to the outside of the combustion furnace plant.

Each configuration of the boiler-equipped combustion system 10 has been described in detail above. Each component of the wastewater treatment system 30 has already been explained in the description of the outline, so the explanation will be omitted.
Now, each configuration of the high-purity carbon dioxide generation system 40 will be described in detail.
In the hydrogen production system 1 of the embodiment and the first modified example, the high-purity carbon dioxide generation system 40 will be described as a system that generates high-purity carbon dioxide F7 by methane fermentation. In particular, organic matter contained in the waste delivered to the refuse incinerator plant is used here as raw material for methane fermentation. Since the organic matter contained in the waste is used as the raw material, there is no need for raw material costs, and it is excellent from the viewpoint of cost effectiveness.
The pretreatment device 41 is a device that performs pretreatment (for example, crushing, solubilization, hydrothermal treatment, etc.) for removing substances unsuitable for fermentation from raw materials and adjusting the properties of the substances suitable for fermentation. The raw material is transferred from, for example, the garbage pit 12 .
The raw material that has been appropriately pretreated by the pretreatment device 41 is introduced into the methane fermentation device 42 .

The methane fermentation device 42 is a device for methane fermentation of the raw material pretreated by the pretreatment device 41 to generate a biogas F8 and discharge a fermentation residue F9. The fermentation method of methane fermentation may be dry or wet.
The biogas F8 contains at least two kinds of methane F6 (CH ₄ ) and carbon dioxide F7 (CO ₂ ) as major components of the biogas F8.
The biogas F8 produced by the methane fermentation device 42 is introduced into the carbon dioxide separation membrane 45, and the fermentation residue F9 is transferred to the dehydrator 43. The dehydrator 43 is, for example, a trommel.
The dehydrator 43 is a device that dehydrates the fermentation residue F9 and separates it into a filtrate F10 and a residue (dehydrated sludge). The filtrate F10 separated here is transferred to the water treatment device 51 of the electrolysis system 50, 50'. Further, the residue (dewatered sludge) is transferred to the refuse pit 12 by the conveyor 44 and incinerated by the refuse incinerator 13 .

The carbon dioxide separation membrane 45 is a device incorporating a separation membrane that separates carbon dioxide F7 from biogas F8. Polymer membranes such as hollow fiber membranes, dendrimer membranes, polyethylene glycol membranes, and polyvinyl alcohol membranes can be used as separation membranes.
The carbon dioxide F7 separated by the carbon dioxide separation membrane 45 does not contain nitrogen oxides or particulate matter like exhaust gas from a combustion furnace or an internal combustion engine, and is high-purity carbon dioxide that does not contain impurities. F7, in other words extremely clean carbon dioxide F7. Therefore, carbon dioxide F7 can be used directly without purification or filtering as a feedstock for the methanation device 46 of the methanation system 72 or as a feedstock for plant photosynthesis in the plant growth facility 48. . The carbon dioxide F7 may be stored in the carbon dioxide storage tank 49 .

In the embodiment and the first modified example, carbon dioxide generated by methane fermentation in the methane fermentation device 42 is stored in the carbon dioxide storage tank 49 or used as a raw material for the methanation device 46 and the plant growing facility 48. The emission of carbon dioxide F7 to the outside of the combustion furnace plant can be greatly reduced.
The plant growing facility 48 includes a storage facility (a carbon dioxide tank, a carbon dioxide cylinder) that stores carbon dioxide F7, and a building and facility (plant factories, greenhouses for cultivation, tanks for cultivation, etc.). For example, algae, flowers, vegetables, fruits and vegetables, foliage plants, succulents, and trees can be grown in the plant growing facility 48 .

On the other hand, the residual gas from which the carbon dioxide F7 has been separated by the carbon dioxide separation membrane 45 is substantially methane F6 (“second methane” in the claims). The methane F6 is stored in a gas cylinder or the like, or supplied to the methane gas utilization facility 47 for use. Examples of the methane gas utilization equipment 47 include equipment for introducing city gas into gas pipes (gas pipe introduction equipment), gas water heaters and gas heaters that burn city gas to supply hot water, gas engines (gas power generators), and the like. homes, businesses, or factories where
Exhaust gas generated when methane F6 is burned in a gas engine is introduced into the waste incinerator 13 as gas for EGR (exhaust gas recirculation), and nitrogen oxides (NOx ) may be reduced. Further, when power is generated by a gas engine using methane F6 as fuel, it can be used as power to operate the methanation device 46, the water electrolysis device 53, the electrolysis device 54, etc., in the same way as the power generated by the steam turbine 23 and the power generator 24. .
The residual gas from which the carbon dioxide F7 has been separated by the carbon dioxide separation membrane 45 is substantially methane F6, but may contain a small amount of sulfur and the like. Therefore, in this case, an impure gas remover such as a desulfurization device (not shown) may be used to remove impure gases other than methane F6 from the residual gas to obtain methane F6.

Next, the methanation system 72 will be described in detail.
The methanation device 46 provided in the methanation system 72 is a device that synthesizes carbon dioxide F7 and hydrogen F4 generated by a water electrolysis device 53 described below to generate methane F12 (“first methane” in the claims). be. Here, for example, methane F12 and pure water F13 are synthesized from carbon dioxide F7 and hydrogen F4 by a methanation reaction or a Sabatier reaction via a co-electrolytic reaction (this synthesis technique is called methanation). The methanation device 46 is provided with a reactor (catalyst container) containing a catalyst for methane synthesis, and methane F
12 is generated. The temperature and pressure in the reactor are controlled within a range in which catalytic activity suitable for the desired reaction can be obtained, for example, about 250° C. and about 20 to 30 atmospheres. Waste steam from the steam turbine 23 can be used to heat and pressurize the methanation device 46 .
Since about 20 to 30 atmospheres is a relatively high pressure, the methanation device 46 has recently been developed to reduce the pressure so that methanation can be performed at a pressure lower than this.

Electric power for operating the methanation device 46 can use electric power generated by the steam turbine 23 and generator 24 or the gas engine, as described above.
The methane F12 synthesized in the methanation device 46 is supplied to the methane gas utilization facility 47 and used or stored. Further, the pure water F13 generated by the methanation device 46 may be directly introduced into the steam drum 21 without passing through the water purifying device 27 .
As a result, the operating cost of the combustion furnace plant can be reduced in terms of power for operating the device and production of pure water.

Chemical reaction formulas relating to methane synthesis in the methanation device 46 are exemplified below.
Co-electrolytic reaction: _CO2 + _3H2O →CO+ _3H2 + _2O2
Methanation reaction: CO+ _3H2 → _CH4 + _H2O
Sabatier reaction: _CO2 + _4H2 → _CH4 + _2H2O

Finally, the electrolysis system 50, 50' will be detailed. The electrolysis system 50, 50' electrolyzes the filtrate F11 biologically treated by the water treatment device 51 in the water electrolysis device 53 or in the electrolysis device 54 different from the water electrolysis device 53, thereby producing a sodium hypochlorite solution F16. , F17.
Since the electrolysis systems 50 and 50' have different configurations between the embodiment and the first modification, the electrolysis system 50 in the embodiment will be described first, and then the electrolysis system 50' in the first modification will be described.
The electrolysis system 50 in the embodiment has a water treatment device 51 , an ion removal device 52 , a water electrolysis device 53 and an electrolysis device 54 .
The water treatment device 51 is an organic water treatment device 51 (biological treatment device) that biologically treats the filtrate F10 separated by the dehydrator 43 of the high-purity carbon dioxide generation system 40 and containing organic components.
The water treatment equipment 51 performs biological treatment in the same manner as the organic wastewater treatment facility 31 of the wastewater treatment system 30, but the amount of filtrate F10 is small compared to the amount of plant wastewater treated by the organic wastewater treatment facility 31. . Therefore, the water treatment device 51 is much smaller and less expensive than the organic wastewater treatment facility 31 . Filtrate F11 that has been biologically treated in the water treatment device 51 is introduced into the ion removal device 52 .

The ion removing device 52 is supplied with at least a part of the boiler blow water F1 discharged from the steam drum 21 at any time, and separates the separated water F2 (pure water) containing no unnecessary ions from the separated water F2 containing unnecessary ions. It is a device for separating into separated water F3. Since the boiler blow water F1 and the filtrate F11 biologically treated by the water treatment device 51 are introduced into the ion removal device 52 shown in FIG. be done.
The filtrate F11 contains sodium ions (Na ⁺ ) and chloride ions (Cl ⁻ ) that are not removed by the biological treatment of the water treatment device 51 . On the other hand, when the anticorrosive added by the chemical addition device 28 contains a phosphoric acid-based chemical, the boiler blow water F1 contains phosphate ions (PO ₄ ³⁻ ).
Therefore, when the mixed liquid is supplied to the ion removing device 52, the water to be separated F3 containing sodium ions (Na ⁺ ), chloride ions (Cl ⁻ ), phosphate ions (PO ₄ ³⁻ ), These unnecessary ions are removed to produce separated water F2, which is pure water.

The rest of the boiler blow water F1 not supplied to the ion removing device 52 is introduced into the inorganic wastewater treatment facility 32 of the wastewater treatment system 30 and subjected to inorganic water treatment.
The reused water F14 that has undergone water treatment in the inorganic wastewater treatment facility 32 of the wastewater treatment system 30 is sprayed by an important device in the plant, for example, the cooling tower 16 for cooling the exhaust gas, so it can be reused. It is desirable to introduce a part of the boiler blow water F1 into the ion removal device 52 instead of the whole amount so as not to cause a shortage of the water F14. However, if it is possible in terms of design, the entire amount of the boiler blow water F1 discharged from the steam drum 21 may be supplied to the ion removing device 52 instead of the part of the boiler blow water F1 to be used as a raw material for hydrogen production. In this case, the "remainder of the boiler blow water F1" is naturally zero, the boiler blow water F1 is not supplied to the waste water treatment system 30, and the entire amount of the boiler blow water F1 is supplied to the ion removal device 52, and is used as a raw material for hydrogen production. used as

The ion remover 52 incorporates, for example, an RO membrane (reverse osmosis membrane) or an ion exchange resin. The RO membrane is a membrane that allows hydrogen ions (H ⁺ ) and hydroxide ions (OH ⁻ ) in water to pass through and blocks other unwanted ions from passing through. The ion exchange resin is a gel-like synthetic resin bead that replaces unnecessary ions in water with hydrogen ions or hydroxide ions.
The separated water F2 is supplied to the water electrolysis device 53, and the water to be separated F3 is supplied to the electrolysis device 54 different from the water electrolysis device 53.

The water electrolysis device 53 is a device that electrolyzes the separated water F2 (pure water). Since the water electrolysis device 53 is a device for electrolyzing pure water, although not shown, in addition to the separated water F2, the pure water F13 generated by the methanation device 46 is supplied to the water electrolysis device 53, and the amount of hydrogen produced is may be increased. When the water electrolyzer 53 produces a predetermined amount of hydrogen F4, if the separated water F2 made from the boiler blow water F1 is insufficient, pure water F13 produced by the methanation device 46, Pure water F13 and F15 other than the separated water F2, such as pure water F15 produced by the water purifier 27, may be mixed and supplied to the water electrolysis device 53.
Here, in general, a water electrolysis apparatus is equipped with a heating device for heating room-temperature pure water in order to perform electrolysis efficiently. However, the water electrolysis device 53 in the embodiment or modified example does not need to be equipped with a heating device. This is because the boiler blow water F1, which is the raw material for hydrogen production in the water electrolysis device 53, is at a high temperature, so the separated water F2 separated by the ion removal device 52 can be adjusted to a higher temperature (approximately 70° C. to 90° C.) than normal temperature. is. Therefore, not only when pure water other than the separated water F2 is mixed, but also when the filtrate F11 is mixed with the separated water F2 (the electrolysis system 50′ in the first modified example described later), the water electrolysis device 53 can electrolyze pure water and liquid mixtures at temperatures higher than room temperature. Therefore, the water electrolysis device 53 can efficiently produce hydrogen without the heating device, and is therefore cost-effective. Of course, even though the temperature of the pure water or the mixed liquid can be adjusted to a temperature higher than normal temperature, if the temperature is insufficient for hydrogen production, the water electrolysis device 53 may be added with the above-mentioned heating device, for example. , the waste steam may be supplied to the heating device for heating.
Electric power for operating the water electrolysis device 53 can be electric power generated by the steam turbine 23, the generator 24, or the gas engine described above. In addition, since the separated water F2 supplied to the water electrolysis device 53 is generated from the boiler blow water F1, which is plant waste water, it is free of raw material cost and does not need to be separately purchased. Therefore, hydrogen F4, which is a valuable resource, can be economically produced from boiler blow water F1, which is plant waste water.

In the water electrolyzer 53, the separated water F2 is electrolyzed to generate hydrogen F4 ( _H2 ) and oxygen F5 ( _O2 ). Hydrogen F4 is introduced into methanation device 46 . Further, the oxygen F5 may be released into the atmosphere, or may be mixed with the combustion air supplied to the inside of the refuse incinerator 13 to promote combustion of the waste.
In addition, since at least a part of the boiler blow water F1 is used as a raw material for the water electrolysis device 53, compared to the conventional method in which the entire amount of the boiler blow water F1 is introduced into the inorganic waste water treatment facility 32 of the waste water treatment system 30, the inorganic waste water The load of water treatment in the wastewater treatment facility 32 can be reduced.

The electrolyzer 54 is a device that electrolyzes the water to be separated F3, and uses sodium ions and chloride ions contained in the water to be separated F3 to generate a sodium hypochlorite solution F16 (NaClO solution). can be done.
Electric power for operating the electrolytic device 54 can be electric power generated by the steam turbine 23, the generator 24, or the aforementioned gas engine.
The sodium hypochlorite solution F16 generated by the electrolyzer 54 may be sprayed as a sterilizing agent for the platform 11 of a refuse incinerator plant, which is a combustion furnace plant, and roads, for example, or as a disinfectant for rooms in the plant. For sterilization cleaning of equipment, you can pour it into a container such as a bucket or a plastic bottle so that you can carry it and use it.
Both the filtrate F10 of the methane fermentation device 42 and the boiler blow water F1 are plant waste water, and the sodium hypochlorite solution F16 is produced in the electrolytic device 54 using these plant waste water as raw materials without the need for raw material costs, so it is excellent in terms of cost effectiveness. . In addition, the economically produced sodium hypochlorite solution F16 can maintain good sanitary conditions in the combustion furnace plant and improve the working environment.

An example of a chemical reaction formula for generating sodium hypochlorite is shown below.
Anode: 2Cl ⁻ → Cl ₂ +2e
Cathode: 2Na ⁺ +2H ₂ O+2e → 2NaOH+H ₂
In liquid: Cl ₂ + 2NaOH → NaClO + NaCl + H ₂ O

Since the electrolysis system 50 in the embodiment has been described above, the electrolysis system 50' in the first modification will now be described.
A major difference of the electrolysis system 50 ′ from the electrolysis system 50 is that the electrolysis system 50 ′ does not have the electrolyzer 54 and the filtrate F 11 is directly supplied to the water electrolyzer 53 . In the electrolysis system 50 ′, only the boiler blow water F 1 is supplied to the ion removal device 52 , and the separated water F 2 produced by the ion removal device 52 is supplied to the water electrolysis device 53 . In addition, the water to be separated F3 is supplied to the inorganic wastewater treatment facility 32 of the wastewater treatment system 30 and subjected to water treatment.
Since the separated water F2 and the filtrate F11 are mixed and introduced into the water electrolysis device 53 of the electrolysis system 50′, the electrolysis in the water electrolysis device 53 produces hydrogen F4 and sodium hypochlorite solution F17. be.
Like the electrolysis system 50, the electrolysis system 50' can also economically produce the sodium hypochlorite solution F17. The sodium hypochlorite solution F17 produced economically can maintain good sanitary conditions in the combustion furnace plant and improve the working environment.

The embodiment and the first modified example have been described above.
In the hydrogen production system 1 of the embodiment or the first modification, for example, when about 30 tons of organic matter is input to the methane fermentation device 42, the amount of methane F6 produced is about 1.9 tons, and carbon dioxide F7 is produced. The production amount is about 3.5 tons. Here, when the recovery rate of methane F6 in the carbon dioxide separation membrane 45 is, for example, about 92% (performance varies depending on the type of carbon dioxide separation membrane 45, etc.), the entire amount of carbon dioxide F7 is introduced into the methanation device 46. Assuming that, about 3.45 tons of carbon dioxide F7 and about 0.1 tons of methane component will be introduced into the methanation device 46 . Also, the amount of methane F6 separated by the carbon dioxide separation membrane 45 is approximately 1.8 tons.
On the other hand, the ion removal device 52 obtains about 5.65 tons of separated water F2 from about 6 tons of boiler blow water F1, so that the water electrolysis device 53 obtains about 0.63 tons of hydrogen F4.
When methanation is performed in the methanation device 46 using all of this hydrogen F4 and carbon dioxide F7, about 1.4 tons of methane F12 and about 2.8 tons of pure water F13 are produced.
Therefore, a total of 3.2 tons of methane F6 and F12, which are valuable materials, can be obtained from methane F6 (secondary methane) and methane F12 (first methane), and the emission of carbon dioxide F7 can be substantially reduced. can be zero.
Moreover, by providing the carbon dioxide separator 60, carbon dioxide F18 contained in the exhaust gas from the combustion furnace can also be recovered.
Further, the electric power generated by the boiler-equipped combustion system 10 can be supplied to devices requiring electric power, such as the methanation device 46 and the water electrolysis device 53 in the hydrogen production system 1 .

Therefore, in the hydrogen production system 1 of the embodiment and the first modified example, the raw material cost of the boiler blow water F1, which is plant waste water, is zero, the carbon dioxide F7 used for methanation also has a raw material cost of zero, and the methanation device 46 , water electrolysis device 53, and the like can be substantially reduced to zero cost. Carbon dioxide F18 discharged from the plant can be reduced. In other words, the hydrogen production system 1 of the embodiment and the first modified example can be said to be a hydrogen production system 1 that enables realization of a decarbonized society, which is a recent global environmental issue.

[2. Second modification and third modification]
Then, next, the hydrogen production system 1 in which the high-purity carbon dioxide production system 40 included in the hydrogen production system 1 of the embodiment and the first modified example is replaced with a high-purity carbon dioxide production system 40', which is another example, A second modified example will be described with reference to FIG. Further, the boiler-equipped combustion system 10 included in the hydrogen production system 1 of the embodiment and the first modification is replaced with a boiler-equipped combustion system 10' as another example, and the hydrogen production system 1 of the embodiment and the first modification A hydrogen production system 1 in which the included high-purity carbon dioxide generation system 40 is a high-purity carbon dioxide generation system 40″, which is another example, will be described as a third modification using FIG.
Of the five systems 10, 30, 40, 50 (50'), and 72 in the hydrogen production systems 1 of the second and third modifications, the other systems that are not changed in the above another example are the Alternatively, it may be the same as the first modified example.
The same reference numerals are assigned to the same configurations as those described in the embodiment and the first modified example, and descriptions of the configurations and effects are omitted. In addition, regarding the same configuration as the configuration shown in the embodiment and the first modified example, the inflow and outflow of liquid or gas, the transfer of objects, etc. may be the same. omitted.

[A. Second modification]
A hydrogen production system 1 of a second modified example will be described with reference to FIG. The hydrogen production system 1 of the second modification differs from the hydrogen production system 1 of the embodiment or the first modification in the high-purity carbon dioxide generation system 40'.
The high-purity carbon dioxide generation system 40', like the high-purity carbon dioxide generation system 40, is a system that generates high-purity carbon dioxide F7 and F19 without a special concentration process. The high-purity carbon dioxide generation system 40 includes at least the methane fermentation device 42 as an example, but the high-purity carbon dioxide generation system 40' includes at least the alcohol fermentation device 66 as an example.
The high-purity carbon dioxide production system 40' of FIG. 4 produces high-purity carbon dioxide F7, F19 from both the alcohol fermentation device 66 and the methane fermentation device 42, but the methane fermentation device 42 is not necessarily provided.

A high-purity carbon dioxide production system 40' in FIG. The alcohol fermentation system 65 includes an alcohol fermentation device 66 and a solid-liquid separation device 67 that solid-liquid separates the mash F20 produced in the alcohol fermentation device 66 into alcohol F21 and residue F22. The solid-liquid separator 67 is, for example, a screw press, a belt press, or the like.
First, biomass such as waste wood and bacas (sugar cane residue) is introduced into the pretreatment device 41 . The biomass is hydrolyzed and saccharified in the pretreatment device 41 to produce glucose.
The glucose produced in the pretreatment device 41 is then introduced into the alcohol fermentation device 66 of the alcohol fermentation system 65 . Then, the yeast is supplied to the alcoholic fermentation device 66 and alcoholic fermentation is performed.
A chemical reaction formula for producing alcohol F21 (C ₂ H ₅ OH) and carbon dioxide F19 using glucose (C ₆ H ₁₂ O ₆ ) is illustrated below.
Alcoholic _fermentation : _{C6H12O6 → 2C2H5OH + 2CO2}

Moromi F20 produced in the alcohol fermentation device 66 by alcohol fermentation is separated into alcohol F21 and residue F22 by the solid-liquid separation device 67, and the residue F22 becomes the raw material of the methane fermentation device . That is, the methane fermentation device 42 performs methane fermentation using the residue F22.
The alcohol F21 is concentrated by a distillation apparatus or a dehydrator (not shown), and can be sold as valuable alcoholic beverages.

The carbon dioxide F19 discharged from the alcohol fermentation device 66 by alcohol fermentation does not contain nitrogen oxides or particulate matter unlike exhaust gas from a combustion furnace or an internal combustion engine, and is a high-purity carbon dioxide that does not contain impurities. carbon dioxide F19, in other words, extremely clean carbon dioxide F19. Therefore, carbon dioxide F19 can be used directly as a feedstock for the methanation device 46 of the methanation system 72 or as a feedstock for plant photosynthesis in the plant growth facility 48 without purification or filtering. . The carbon dioxide F19 may be stored in the carbon dioxide storage tank 49 .
In the second modification, the carbon dioxide F19 generated by alcohol fermentation in the alcohol fermentation device 66 is stored in the carbon dioxide storage tank 49 or used as a raw material for the methanation device 46 and the plant growth facility 48, so the combustion furnace The amount of carbon dioxide F19 emitted to the outside of the plant can be greatly reduced.
Although most of the gas discharged from the alcohol fermentation device 66 is carbon dioxide F19, it may contain a trace amount of impurities such as sulfur depending on the type of biomass. Therefore, in this case, the impurities may be removed using an impure gas removing device such as a desulfurization device (not shown).

[B. Third modification]
A hydrogen production system 1 of a third modification will be described with reference to FIG. The hydrogen production system 1 of the third modification differs from the hydrogen production system 1 of the embodiment or the first modification in the boiler-equipped combustion system 10' and the high-purity carbon dioxide generation system 40''.
The boiler-equipped combustion system 10 ′ is, like the boiler-equipped combustion system 10 , at least a combustion furnace 68 and a boiler 20 that generates steam from heat burned in the combustion furnace 68 . Although the boiler-equipped combustion system 10 includes the refuse incinerator 13 as an example of the combustion furnace 68, the boiler-equipped combustion system 10' need not necessarily be the refuse incinerator 13. When the gasification furnace 69 and the combustion furnace 68 are formed as a pair as will be described later, a fluidized bed furnace is generally used as the combustion furnace 68 .
The high-purity carbon dioxide generation system 40″, like the high-purity carbon dioxide generation systems 40 and 40′, is a system that generates high-purity carbon dioxide without a special concentration process. High-purity carbon dioxide generation system 40 , 40' includes, as an example, the methane fermentation device 42 and the alcohol fermentation device 66, but the high-purity carbon dioxide generation system 40'' includes, as an example, at least a gasification furnace 69 for gasifying woody biomass.

The high-purity carbon dioxide generation system 40″ of FIG. Specifically, when woody biomass is gasified in the gasification furnace 69, the components contained in the gasification gas are approximately 15% CO ₂ and H ₂ About 35%, about 40% CO, and about 4% CH _4. The remaining components include trace amounts of sulfur and the like.

First, woody biomass such as waste wood is introduced into the pretreatment device 41 and crushed. Next, the waste wood crushed by the pretreatment device 41 is introduced into the gasification furnace 69 and gasified in the gasification furnace 69 . Since the gasification gas generated in the gasification furnace 69 contains tar, it is supplied to a tar reformer 70 that reforms or removes tar.
Then, the gasification gas from which the tar is reformed or removed by the tar reformer 70 is introduced into the desulfurization device 71 . Although not shown, at this time, other impurities may be removed using an impure gas remover.
The gasified gas from which trace amounts of sulfur and impurities have been removed by the desulfurization device 71 or the like is supplied to the methanation device 46 of the methanation system 72 as a raw material for methanation.
The pyrolysis residue generated by the gasification gas coming out of the waste wood in the gasification furnace 69 is burned in the combustion furnace 68 of the boiler-equipped combustion system 10'. Further, the heat generated by the combustion in the combustion furnace 68 heats the gasification furnace 69 to promote gasification in the gasification furnace 69 .
In the third modification, the gasification gas generated in the gasification furnace 69 is used as the raw material for the methanation device 46, so the amount of carbon dioxide emitted from the gasification furnace 69 to the outside of the combustion furnace plant is greatly reduced. can.

The embodiment and the first, second, and third modifications of the present invention have been described above. The boiler-equipped combustion systems 10, 10', electrolysis systems 50, 50', and high-purity carbon dioxide generation systems 40, 40', 40'' in the hydrogen production system 1 of these embodiments and modifications may be replaced as appropriate. , may be connected in parallel.

1 Hydrogen production system 10, 10' Combustion system with boiler 11 Platform 12 Waste pit 13 Waste incinerator 14 Ash extrusion device 15 Flue 16 Cooling tower 17 Dust removal device (bag filter, electric dust collector, etc.)
18 Fly ash cleaning device 19 Chimney 20 Boiler 21 Steam drum 22 Exhaust heat recovery device (heat transfer tube, superheater tube, etc.)
23 Steam turbine 24 Generator 25 Condenser 26 Deaerator 27 Pure water device 28 Chemical addition device 29 Blow pipe 30 Wastewater treatment system 31 Organic wastewater treatment facility (biological treatment facility, etc.)
32 inorganic wastewater treatment facility 40, 40', 40″ high-purity carbon dioxide generation system 41 pretreatment device 42 methane fermentation device 43 dehydrator (trommel, etc.)
44 conveyor 45 carbon dioxide separation membrane 46 methanation device 47 methane gas utilization equipment 48 plant growing equipment 49 carbon dioxide storage tanks 50, 50' electrolysis system 51 water treatment equipment (biological treatment equipment)
52 ion removal device 53 water electrolysis device 54 electrolysis device 60 carbon dioxide separation device 61 absorber 62 heat exchanger 63 desorption device 64 reheater 65 alcohol fermentation system 66 alcohol fermentation device 67 solid-liquid separation device (screw press, belt press Such)
68 Combustion furnace 69 Gasification furnace 70 Tar reforming device 71 Desulfurization device 72 Methanation system F1 Boiler blow water F2 Separated water F3 Water to be separated F4 Hydrogen F5 Oxygen F6 Methane (produced in the methane fermentation device 42 and separated by the carbon dioxide separation membrane 45 , secondary methane)
F7 carbon dioxide (produced in the methane fermentation device 42 and separated by the carbon dioxide separation membrane 45)
F8 Biogas F9 Fermentation residue F10 Filtrate (dehydrated by dehydrator 43)
F11 Filtrate (biologically treated in water treatment device 51)
F12 methane (produced in methanation unit 46, primary methane)
F13 pure water (produced in the methanation device 46)
F14 Recycled water F15 Pure water (produced in pure water device 27)
F16 sodium hypochlorite solution (produced in electrolyzer 54)
F17 Sodium hypochlorite solution (produced by water electrolyzer 53)
F18 carbon dioxide (separated by carbon dioxide separator 60)
F19 carbon dioxide (separated in the alcohol fermentation device 66)
F20 moromi (produced in alcohol fermentation apparatus 66)
F21 alcohol (separated by solid-liquid separator 67)
F22 residue (separated by solid-liquid separator 67)

Claims (1)

Applied in combustion furnace plant,
a boiler-equipped combustion system comprising at least a combustion furnace and a boiler that generates steam from heat burned in the combustion furnace;
an ion removing device for generating separated water from which unnecessary ions are removed by introducing at least a portion of the boiler blow water discharged from the boiler and water to be separated containing the unnecessary ions; an electrolysis system comprising at least a water electrolyzer that generates hydrogen by electrolyzing water;
and a waste water treatment system including at least an inorganic waste water treatment facility that performs inorganic water treatment on plant waste water generated in the combustion furnace plant and containing the remainder of the boiler blow water.

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