JP4922010B2 - CO2 supply device for plant growth using exhaust gas - Google Patents

Description

The present invention relates to a plant growth CO ₂ supply device using exhaust gas discharged from an internal combustion engine or a combustion device.

In recent years, cogeneration has been widely adopted, thereby improving energy efficiency and reducing CO ₂ emissions that cause global warming. Cogeneration uses electricity and heat generated at the time of power generation as energy sources. Further, there is a form called trigeneration that effectively uses CO ₂ generated at this time and discarded in the past.

Trigeneration purifies exhaust gas discharged from an internal combustion engine such as a gas engine and actively uses CO ₂ contained in the exhaust gas. Since exhaust gas contains harmful substances such as carbon monoxide (CO), unburned hydrocarbons (HC), and nitrogen oxides (NOx), at least these concentrations are required by laws and regulations such as the Air Pollution Control Law. It is necessary to discharge it after purifying it so that it is below the standard value. Moreover, although it is necessary to further purify depending on the use of CO ₂ , plant growth is promoted as such a use.

The exhaust gas purification method generally includes a method such as lean combustion or a three-way catalyst (see, for example, Patent Document 1). In the case of lean combustion, the use of CO ₂ is to promote plant growth. However, the concentration of harmful substances cannot be reduced to a concentration suitable for use.

  In the case of using a three-way catalyst, it is necessary to heat the catalyst layer at a constant temperature while keeping the balance of harmful substances to be treated constant. Therefore, if heating of the catalyst layer is performed with the retained heat of the exhaust gas, it is necessary to provide a catalyst layer in the vicinity of the internal combustion engine or combustion device that becomes the heat source, for example, in the engine package. In addition, the space for installing the piping is limited and the piping must be bent, so that a drift is likely to occur and it becomes difficult to uniformly heat the catalyst layer. Therefore, further attempts to make the catalyst layer larger would be uneconomical.

In addition, when the catalyst layer is not heated with the retained heat of the exhaust gas, heating is performed by providing a heating means such as an electric heater around the catalyst layer. When the center portion is heated to an optimum temperature, it is necessary to keep the ambient temperature at a considerably higher temperature than an appropriate temperature, resulting in an inefficient operation.
JP 2005-193175 A

The present invention has been made in view of the above, it is an object of the temperature suitable for the use temperature of the exhaust gas with reducing the concentration of harmful substances in the exhaust gas, the exhaust gas containing CO ₂ An object of the present invention is to provide a plant-growing CO ₂ supply device using exhaust gas that can efficiently purify the exhaust gas by heating the catalyst layer uniformly when supplying it to the plant to be grown.

In order to solve the above problem, in the plant growth CO ₂ supply device using exhaust gas according to claim 1, at least a part of the flow path 3 of exhaust gas discharged from the internal combustion engine 11 or the combustion device 12 is upstream. The vertical channel 31 has a lower side and an upper side on the downstream side. The vertical channel 31 is provided with an oxidation catalyst layer 5 and a heat exchanger 7 in order from the lower side.

By adopting such a configuration, carbon monoxide, unburned hydrocarbons and nitrogen oxides in the exhaust gas are reduced, and the exhaust gas containing CO ₂ is nurtured with the temperature of the exhaust gas being suitable for use. In this case, the catalyst layer can be heated uniformly to purify the exhaust gas efficiently.

  Further, in the invention according to claim 2, in the invention according to claim 1, the vertical flow path 31 is generated by the heat exchanger 7 at a position below the heat exchanger 7 and above the oxidation catalyst layer 5. The drain collecting part 6 for collecting the drain to be collected is provided.

  With such a configuration, it is possible to prevent the drain generated in the heat exchanger 7 from dropping and adhering to the lower oxidation catalyst layer 5.

  In the invention according to claim 3, in the invention according to claim 1 or 2, the heating unit 21 for heating the exhaust gas is provided upstream of the oxidation catalyst layer 5 of the exhaust gas flow path 3. It is characterized by.

  By adopting such a configuration, it is not necessary to depend on the retained heat of the exhaust gas to make the temperature of the oxidation catalyst layer 5 appropriate.

  Further, in the invention according to claim 4, in the invention according to any one of claims 1 to 3, an adsorption removal layer made of activated carbon or activated carbon fibers for adsorbing and removing nitrogen oxides in the exhaust gas flow path 3 8 is provided.

  With such a configuration, it is possible to adsorb and remove nitrogen oxides that have not been reduced in the exhaust gas.

According to the present invention, carbon monoxide, unburned hydrocarbons, and nitrogen oxides in the exhaust gas are reduced, and the temperature of the exhaust gas is set to a temperature suitable for use, and supplied to the plant that grows the exhaust gas containing CO _2. In addition, the safety to the operator can be ensured. In this case, the exhaust gas can be purified efficiently by heating the catalyst layer uniformly.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 shows a gas block diagram of a plant for growing CO ₂ supply device 2 using the present invention, in FIG. 2, a schematic of a system using the plant growth for CO ₂ supply device 2 using the exhaust gas of the present invention An overall configuration diagram is shown.

  Reference numeral 1 in the figure denotes an exhaust gas supply source including an internal combustion engine 11 or a combustion device 12 in which various fuels such as natural gas and gasoline are burned. In the case of the internal combustion engine 11, a generator (not shown) is driven to generate power. In the case of the combustion device 12, the heated part of the heat exchange part such as a boiler (not shown) is heated. The exhaust gas discharged when combustion is performed in the internal combustion engine 11 and the combustion device 12 is purified and carbon monoxide (CO), unburned hydrocarbon (HC), nitrogen oxide (NOx) in the exhaust gas. ) And other harmful substances are discharged after being reduced. The pipe part 4 constituting the flow path 3 of the exhaust gas discharged from the internal combustion engine 11 or the combustion device 12 is at least partially formed by a vertical pipe part 41, and the flow path 3 in the vertical pipe part 41 is vertical. A mold channel 31 is formed. The vertical flow path 31 is configured such that the upstream side is the lower side and the downstream side is the upper side.

  The vertical channel 31 is provided with the oxidation catalyst layer 5 and the heat exchanger 7 in order from the lower side.

  The oxidation catalyst layer 5 is composed of a honeycomb supporting a noble metal as a catalyst, and oxidizes incomplete combustion components such as carbon monoxide and hydrocarbons such as ethylene in the exhaust gas by the catalytic action on the surface. Carbon monoxide is changed to carbon dioxide, and hydrocarbons are changed to carbon dioxide and water.

Further, nitrogen oxides in the exhaust gas may be removed by adsorption or the like. For example, an adsorption removal layer 8 filled with activated carbon, activated carbon fiber, zeolite, or the like is provided (see FIG. 4) to adsorb and remove nitrogen oxides contained in the exhaust gas. In the present embodiment, the adsorption removal layer 8 is disposed on the downstream side of the vertical flow path 31 of the exhaust gas flow path 3 or on the downstream side of the heat exchanger 7 of the vertical flow path 31. . In addition, if the plant supplying CO ₂ is a plant having resistance to acidic gas such as nitrogen oxide, the adsorption removal layer 8 may reduce the filling amount of activated carbon or activated carbon fiber, or as shown in FIG. The adsorption removal layer 8 may be eliminated and the concentration may be reduced to a certain level or less by mixing and dilution with air.

In addition, when an activated carbon fiber catalyst is used for the adsorption removal layer 8, NOx is preferentially treated, and a decrease in CO ₂ concentration due to adsorption is not seen, and exhaust gas with a stable CO ₂ concentration can be supplied. Become.

The heat exchanger 7 is disposed on the upper side (downstream side) of the vertical catalyst 31 with respect to the oxidation catalyst layer 5, collects exhaust heat of the exhaust gas, cools it, and contains CO ₂ for plant growth. It is supplied after the temperature is suitable as exhaust gas. The heat recovered by the heat exchanger 7 is used for heating the greenhouse H in which a plant supplying CO ₂ is accommodated. At this time, water vapor in the exhaust gas is condensed on the surface of the heat exchanger 7 (the surface facing the flow path 3) to generate drain (condensed water). As described above, the heat exchanger 7 is disposed in a portion above the oxidation catalyst layer 5 of the vertical flow path 31, and the drain adhering to the surface of the heat exchanger 7 falls to cause the oxidation catalyst layer. In order to prevent the liquid from adhering to the drain 5, the drain collecting section 6 that collects the drain generated by the heat exchanger 7 at a position below the heat exchanger 7 and above the oxidation catalyst layer 5 in the vertical flow path 31. Is provided. This will be described later.

  In the present embodiment, a heating unit 21 for heating the exhaust gas is provided at a portion upstream of the oxidation catalyst layer 5 of the exhaust gas flow path 3. The heating unit 21 is not particularly limited, such as a combustion burner 21a as shown in FIG. 1 or an electric heater 21b as shown in FIG. In order to set the oxidation catalyst layer 5 to an appropriate temperature of 200 ° C. to 300 ° C., the heating unit 21 heats the exhaust gas passing through the oxidation catalyst layer 5 to a high temperature, thereby heating the oxidation catalyst layer 5 to the appropriate temperature. To do. Depending on the type of the oxidation catalyst layer 5, a temperature in the vicinity of 400 ° C. to 500 ° C. and other temperature ranges may be appropriate temperatures.

As described above, a part of the flow path 3 of the exhaust gas discharged from the internal combustion engine 11 or the combustion device 12 is a vertical flow path 31, and heat exchange with the oxidation catalyst layer 5 is sequentially performed in the vertical flow path 31 from the lower side. In addition to reducing the harmful carbon monoxide and unburned hydrocarbons in the exhaust gas by the oxidation catalyst layer 5, the heat exchanger 7 makes the temperature of the exhaust gas suitable for use as a temperature suitable for use. Can be supplied to plants that grow exhaust gas containing ₂ (at least at a higher concentration than air), and can also ensure safety for workers in the greenhouse in which the plant supplying CO ₂ is housed it can. In this case, the exhaust gas can be purified efficiently by heating the catalyst layer uniformly.

Further, since the CO ₂ supply device 2 is provided independently of the internal combustion engine 11 or the combustion device 12, exhaust gas from the facilities of the plurality of internal combustion engines 11 or the combustion devices 12 can be comprehensively processed. The amount of exhaust gas can be increased or decreased by changing the amount of catalyst in the oxidation catalyst layer 5.

Further, the flow path 3 that accommodates the oxidation catalyst layer 5 and the heat exchanger 7 (and the drain recovery unit 6), which are the main components of the present CO ₂ supply device 2, is configured by the vertical vertical pipe portion 41, and thus the plane It can be made compact by reducing the installation area in view.

  Actually, a test using an actual machine in which an activated carbon fiber catalyst was provided in the oxidation catalyst layer and the adsorption layer was performed, and the results are shown in Table 1.

From these results, it was confirmed that both CO and NO _{2 as} harmful substances could be sufficiently reduced, and that CO ₂ maintained a high concentration.

  Hereinafter, the drain collecting unit 6 will be described with reference to FIG.

  The drain collecting part 6 is mainly composed of an upper receiving part 61, a lower receiving part 62, and a drainage part 63, and is attached to a cylindrical casing 60 forming an outer shell in this embodiment. The upper receiving portion 61 is disposed below the heat exchanger 7, and its upper surface serves as a receiving surface (referred to as an “upper receiving surface 61 a” for convenience) that receives the drain falling from the surface of the heat exchanger 7. By tilting the upper receiving surface 61a, the drain received by the upper receiving surface 61a flows down to the lower end portion 61b of the upper receiving surface 61a. The upper receiving surface 61a is disposed in a part of the cross section of the vertical flow path 31, and the remaining portion becomes the exhaust gas flow path 3. In the present embodiment, two plate portions having a substantially rectangular shape when viewed from the flow direction are formed in the vertical flow channel 31 in the vertical tube portion 41, and a gap serving as the exhaust gas flow channel 3 is formed in the central portion. In this way, they are arranged on both sides, inclined so that the end on the center side becomes the lower end 61b, and are arranged in a substantially inverted C shape when viewed from the direction orthogonal to the flow direction. In the present embodiment, the outer shell of the drain collecting unit 6 is constituted by the cylindrical casing 60, and the edge portions of the two plate portions that become the upper receiving portions 61 are fixed to the cylindrical casing 60.

  The lower receiving portion 62 is disposed below the upper receiving portion 61, and the upper surface of the lower receiving portion 62 receives a drain falling from the surface of the heat exchanger 7 and a drain falling from the upper receiving portion 61 (for convenience, the “lower receiving surface 62 a "). By tilting the lower receiving surface 62a, the drain received by the lower receiving surface 62a flows down to the lower end portion 62b of the lower receiving surface 62a. The lower receiving surface 62a is disposed in a part of the cross section of the vertical flow path 31, and the remaining portion becomes the exhaust gas flow path 3. In the present embodiment, the receiving portion 62 has a substantially rectangular shape when viewed from the flow direction in the vertical flow path 31 in the vertical tube portion 41 and is substantially V-shaped when viewed from a direction orthogonal to the flow direction. It consists of a plate-like part, and is arranged so that the lower receiving surface 62a is located below the exhaust gas flow path 3 formed between the plate parts of the upper receiving part 61, and both sides of the lower receiving part 62 are exhausted. It becomes the flow path 3. As a result, the exhaust gas flow path 3 is closed by the upper receiving portion 61 and the lower receiving portion 62 in plan view, and the drain that falls vertically downward from the heat exchanger 7 is either the upper receiving portion 61 or the lower receiving portion 62. Can be received at the receiving surface.

  Alternatively, the cylindrical casing 60 itself may be tapered so that the cross-sectional area in plan view becomes smaller as it goes downward, and the tapered surface may function in the same manner as the receiving surface.

  In the present embodiment, both end portions in the longitudinal direction of the receiving portion 62, that is, both end portions in a direction that appears to be substantially V-shaped, are fixed to the cylindrical casing 60. The lower receiving portion 62 is inclined in the longitudinal direction, and the drain received on the lower receiving surface 62a and accumulated in the substantially V-shaped valley bottom flows down toward the lower end portion 62b in the longitudinal direction. . The lower end 62 b of the lower receiving part 62 has a through hole 60 a formed in the cylindrical casing 60 so as to communicate with the outside of the cylindrical casing 60, and the lower end of the lower receiving part 62. The drain accumulated in the portion 62b is discharged out of the cylindrical casing 60 through the through hole 60a. Further, on the outside of the cylindrical casing 60, a drainage part 63 for guiding and draining the drain discharged through the through hole 60a is provided.

  In the present embodiment, a connecting rod 64 for connecting the upper receiving portion 61 and the lower receiving portion 62 is provided. This is for smoothly guiding the drain received by the upper receiving surface 61a of the upper receiving portion 61 and flowing down to the lower end portion 61b to the lower receiving surface 62a of the lower receiving portion 62. This embodiment Then, the upper ends of a plurality of (two in this embodiment) connecting rods 64 are positioned in the longitudinal direction of the lower end portions 61b of the two plate portions of the upper receiving portion 61, and the lower ends of the connecting rods 64 are It arrange | positions in contact with or close to the lower receiving surface 62a of the lower receiving part 62. FIG. As a result, the drain received by the upper receiving surface 61a of the upper receiving portion 61 and flowing down to the lower end portion 62b is smoothly and reliably transferred to the lower receiving surface 62a of the lower receiving portion 62 through the surface of the connecting rod 64. It is also possible to prevent the drained water from splashing onto the lower receiving surface 62a of the lower receiving portion 62.

  By providing the drain recovery unit 6 as described above, it is possible to prevent the drain generated by the heat exchanger 7 from dropping and adhering to the lower oxidation catalyst layer 5.

It is a block diagram of the principal part of one Embodiment of this invention. Id is a schematic overall structural view of a system using a CO ₂ supply device in the embodiment. It is a block diagram at the time of using the heating part of another example. It is a block diagram of other embodiment. A drain collection part is shown, (a) is a top view, (b) is AA sectional drawing, (c) is BB sectional drawing.

Explanation of symbols

11 internal combustion engine 12 combustion device 2 for cultivating plant CO ₂ supply device 3 the channel 31 vertical channel 5 oxidation catalyst layer 7 heat exchanger

Claims (4)

At least a part of the flow path of the exhaust gas discharged from the internal combustion engine or the combustion apparatus is a vertical flow path with the upstream side on the lower side and the downstream side on the upper side, and heat exchange with the oxidation catalyst layer in order from the lower side to the vertical flow path A plant growth CO ₂ supply device using exhaust gas, characterized by comprising a vessel. 2. The exhaust gas according to claim 1, wherein a drain recovery unit that recovers drain generated by the heat exchanger is provided at a position below the heat exchanger of the vertical flow path and above the oxidation catalyst layer. Utilized CO ₂ supply device for plant growth. The plant growth CO ₂ supply apparatus using exhaust gas according to claim 1 or 2, wherein a heating unit for heating the exhaust gas is provided upstream of the oxidation catalyst layer in the exhaust gas flow path. The plant for growing plants using exhaust gas according to any one of claims 1 to 3, wherein an adsorption removal layer made of activated carbon or activated carbon fibers for adsorbing and removing nitrogen oxides is provided in the exhaust gas flow path. CO ₂ supply device.

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