JP2016186286A - Biogas power generation facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biogas power generation facility which is not subject to limitations on power generation output caused by composition variations of a biogas without using fuels other than the biogas.SOLUTION: A biogas power generation facility includes: a fermentation tank 2; a power generator 3; a main path L1 which supplies a biogas from the fermentation tank 2 to the power generator 3; and a sub path L2 which is branched from the main path L1, takes out part of the biogas from the main path L1, is joined to the main path L1, and returns the concentrated biogas to the main path L1; and a concentrator 4 which is provided at the sub path L2 and concentrates components in the biogas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a biogas power generation facility.

  In recent years, carbon dioxide generated by the combustion of fossil fuels has become a problem as one of the causes of global warming, and energy problems are being emphasized in connection with this. Therefore, digestion gas (hereinafter referred to as “biogas”) generated when fermenting organic waste such as sewage sludge, manure, livestock dung, agricultural waste, and food waste with anaerobic bacteria is referred to as a gas turbine for power generation. Biogas power generation equipment that is highly utilized for driving gas is attracting attention.

  By the way, typical biogas contains 60 volume% methane and 40 volume% carbon dioxide as main components, and further contains a small amount of nitrogen, oxygen, hydrogen sulfide, water vapor, and the like. However, the amount of biogas generated and its composition fluctuate on a daily basis due to the input of waste other than the prescribed, troubles in temperature control of the fermenter, the frequency of waste input and the temperature of the waste depending on the season, etc. was there.

  That is, in the conventional biogas power generation equipment, since the operation of the power generation apparatus becomes unstable due to daily composition variation of the biogas, there is a problem that the power generation output is restricted.

  For example, Patent Document 1 is known as a method for solving such a problem. In Patent Document 1, as a gas turbine power generation apparatus using biogas as fuel, a high-calorie fuel (liquefied natural gas, liquefied petroleum gas, kerosene, or heavy oil) is used as a biogas as a fuel in order to stabilize the power generation output. Etc.) is disclosed.

JP 2003-065084 A

  However, the biobus power generation facility described in Patent Document 1 requires the use of fossil fuel in addition to biogas, and thus has a problem that the reduction of the load is insufficient for the environment.

  The present invention has been made in view of the above circumstances, and provides a biogas power generation facility that is not subject to restrictions on power generation output due to variations in the composition of biogas without using fuel other than biogas. Let it be an issue.

In order to solve this problem, the present invention has the following configuration.
That is, the invention according to claim 1 is a fermenter that generates biogas, a generator that generates power using the biogas as fuel, a main path that supplies the biogas from the fermenter to the generator, A sub-route for branching from the main route, separating a part of the biogas from the main route, joining the main route, and returning the concentrated biogas to the main route; and the sub-route And a concentrating device for concentrating the components in the biogas.

  The invention according to claim 2 is the biogas power generation facility according to claim 1, further comprising concentration measuring means provided in the main path.

  According to a third aspect of the present invention, there is provided the first flow rate adjusting means provided between a branch point of the main route with the sub route and a junction of the sub route, and the concentrating device of the sub route. The biogas power generation facility according to claim 1, further comprising: a second flow rate adjusting unit provided on the secondary side of the first gas flow rate adjusting unit.

  The invention according to claim 4 is the biogas concentration control connected by the concentration measuring means, the concentrating device, the first flow rate adjusting means, the second flow rate adjusting means, and an electric communication path for transmitting and receiving electrical signals. It is a biogas power generation equipment of Claim 3 provided with a means.

  The invention according to claim 5 is provided on a primary side of the concentrator of the first compressor provided in the main path between the branch point and the first flow rate adjusting means, and the sub path. The biogas power generation facility according to claim 3, further comprising a second compressor.

  The invention according to claim 6 is the biogas power generation facility according to any one of claims 3 to 5, wherein a mixing means is provided at the junction.

  The invention according to claim 7 is the biogas power generation facility according to any one of claims 1 to 6, wherein a buffer tank is provided on a primary side of the generator in the main path.

  The invention according to claim 8 is any one of claims 1 to 7, wherein the concentrator is one of a pressure fluctuation adsorption method, a membrane separation method, a high-pressure water absorption method, and an amine absorption method. The biogas power generation facility according to item.

  The biogas power generation facility of the present invention is provided with a concentrating device in a sub route branched from a main route for supplying biogas from a fermenter to a generator, and returns the concentrated biogas from the sub route to the main route. Since it is configured, there is no restriction on the power generation output due to the composition variation of the biogas without using any fuel other than the biogas. Therefore, the biogas power generation facility can be stably operated.

1 is a system diagram showing a biogas power generation facility that is an embodiment to which the present invention is applied.

  Hereinafter, a biogas power generation facility which is an embodiment to which the present invention is applied will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

First, the structure of the biogas power generation equipment which is one embodiment to which the present invention is applied will be described.
FIG. 1 is a system diagram showing biogas power generation as an embodiment to which the present invention is applied. As shown in FIG. 1, the biogas power generation facility 1 of the present embodiment includes a fermenter 2, a generator 3, a main path L1 for supplying biogas from the fermenter 2 to the generator 3, and a main path L1. a pathway L2 merging at the merging point P ₂ in the main path L1 while branched from the branch point P _1, is schematically configured to include a concentrator 4 provided in the sub path L2, the. The biogas power generation facility 1 is a facility for generating power by supplying the biogas generated in the fermenter 2 to the generator 3.

The fermenter 2 is a facility for generating biogas. Specifically, for example, biogas is generated by anaerobic fermentation of sewage sludge, food waste, livestock manure, and the like. In this fermenter 2, the amount and composition of biogas generated are generally changed by the input of waste other than a predetermined amount, the temperature change of the fermenter, or the temperature fluctuation around the fermenter. Here, the composition of the biogas generally has a methane gas (CH ₄ ) concentration of about 60% by volume and a carbon dioxide (CO ₂ ) concentration of about 40% by volume.

  The generator 3 is a facility that generates power using biogas as fuel. Specifically, the generator 3 includes, for example, an unillustrated compressor, combustor, gas turbine, and generator.

The main path L <b> 1 is a biogas supply pipe provided between the fermenter 2 and the power generator 3 in order to supply biogas from the fermenter 2 to the power generator 3. The main path L1, along branches pathway L2 at the branch point P _1, rejoin the alternative pathway L2 at the confluence P ₂ on the secondary side of the branch point P _1. The main path L1 includes, in order from the primary side (that is, the fermenter 2 side), a densitometer (concentration measuring means) 5, a main path compressor (first compressor) 6, and a main path flow control valve (first). 1 flow rate adjusting means) 7, mixing equipment (mixing means) 8, buffer tank 9, and mixed gas flow rate adjusting valve 10 are provided.

The concentration meter 5 is provided on the primary side of the branch point P ₁ in order to measure the composition of biogas (that is, the above-described methane gas concentration and carbon dioxide concentration). The densitometer 5 is not particularly limited as long as it has a function capable of measuring the composition of biogas. Specific examples of such a concentration meter include an infrared absorption method and a gas chromatograph method.

The main path compressor 6 is provided on the secondary side of the branch point P ₁ in order to increase the pressure of the biogas supplied from the fermenter 2. The main path compressor 6 is not particularly limited as long as the compressor can pump gas. As such a compressor, specifically, for example, a compressor that compresses gas by a rotary motion of a rotor or a reciprocating motion of a piston, a compressor, a rotary pump, or the like can be used.

  In general, the biogas generated in the fermenter 2 is low pressure (for example, about 0.002 MPaG (gauge pressure, the same applies hereinafter)) and cannot be directly supplied to the generator 3. Therefore, the main path compressor 6 is provided in the main path L1, and is supplied to the generator 3 after being boosted to about 0.01 MPaG, for example.

Main path flow control valve 7, the biogas boosted by the main path compressor 6 for feeding to the generator 3 at a predetermined flow rate, between the main route compressor 6 of the main path L1 and the confluence P ₂ Is provided. The main path flow rate adjusting valve 7 is not particularly limited as long as it has a function of controlling the flow rate of the biogas boosted by the main path compressor 6. Specifically, for example, a mass flow controller or a needle valve can be used.

  By providing this main path flow rate adjusting valve 7 on the secondary side of the main path compressor 6 and controlling the flow rate of the biogas supplied from the main path L1 to a predetermined flow rate, the mixing equipment 8 in the subsequent stage is efficiently biotreated. Gas can be supplied.

Pathway L2 is branched from the main path L1 at a branch point P _1, the main path L1 while preparative portion of biogas min, joins the main path L1 at the confluence P _2, concentrated biogas ( Hereinafter, it is a supply pipe for returning the concentrated gas) to the main path L1. This sub path L2, the primary side (i.e., the branch point P ₁ side) in order from the alternative pathway compressor (the second compressor) 11, a concentrator 4, the sub path flow rate control valve (second flow rate control means ) 12.

The sub path compressor 11 is provided on the secondary side of the branch point P ₁ in order to increase the pressure of the biogas fractionated from the main path L1. The sub-path compressor 11 is not particularly limited as long as it is a compressor that can pump gas. As such a compressor, the same thing as the main path compressor 6 mentioned above can be used.

The sub path compressor 11 can increase the pressure of the biogas in the sub path L2 to, for example, about 0.1 MPaG.
Further, by providing the compressors 6 and 11 in the main route L1 and the sub route L2, respectively, the pressure of the biogas in the branched route can be controlled independently.

The concentrator 4 is equipment for concentrating components in the biogas that has been pressurized by the sub-path compressor 11. The concentration device 4 is not particularly limited as long as it can concentrate the methane gas (CH ₄ ) concentration by removing the carbon dioxide component in the biogas. Specifically, as equipment capable of removing carbon dioxide in biogas, for example, pressure fluctuation adsorption system, membrane separation system, high pressure water absorption system, and amine absorption system concentration equipment can be used.

According to the concentrating device 4, the methane gas (CH ₄ ) concentration is, for example, about 90 to 98% by volume, and the carbon dioxide (CO ₂ ) concentration is, for example, about 2 to 10% by volume. Can be generated and fed to the secondary side.

Pathway flow control valve 12, the biogas is concentrated by concentrator 4 (i.e., enriched gas) to be supplied to the mixing equipment 8 at a predetermined flow rate, it is provided on the primary side of the merging point P _2. As the auxiliary path flow rate adjustment valve 12, the same one as the main path flow rate adjustment valve 7 can be used. By providing this sub-path flow rate adjusting valve 12 on the secondary side of the concentrating device 4 and controlling the flow rate of the concentrated gas to a predetermined flow rate, the concentrated gas can be efficiently supplied to the subsequent mixing equipment 8.

Mixing equipment 8, the biogas from the main route L1, in order to mix the concentrated gas from the sub path L2, which is provided with a main path L1 to the converging point P ₂ of the alternative pathway L2 facilities. The mixing facility 8 is not particularly limited as long as it can mix gases having different components. Specifically, for example, a static mixer or the like can be used.

  Even if the components of the biogas supplied from the main path L1 fluctuate due to the mixing equipment 8, the composition can be adjusted by appropriately mixing the concentrated gas supplied from the subpath L2, so that the combustion Biogas mixed in a composition suitable for (operation) (hereinafter sometimes referred to as “mixed gas”) can be stably supplied to the generator 3.

  The buffer tank 9 is a storage facility provided on the secondary side of the mixing facility 8 and on the primary side of the generator 3 in order to temporarily store the mixed gas supplied from the mixing facility 8. The buffer tank 9 is not particularly limited as long as it is a facility capable of storing gas. The capacity of the buffer tank 9 is not particularly limited, and can be appropriately selected according to the scale of the biogas power generation facility 1, the output of the generator 3, and the like.

  By providing the buffer tank 9 in the main path L1, a certain amount of the mixed gas adjusted to a predetermined composition by the mixing facility 8 can be stored, so that the amount and composition of biogas generated in the fermenter 2 are Even if it fluctuates, a mixed gas having a predetermined composition can be stably supplied to the generator 3.

  The mixed gas flow rate adjusting valve 10 is provided on the primary side of the generator 3 in order to control the supply amount of the fuel gas supplied to the generator 3, that is, the mixed gas whose components are adjusted. The mixed gas flow rate control valve 10 is not particularly limited, and the same gas flow rate control valve 7 as described above can be used.

  The biogas power generation facility 1 of this embodiment includes a concentration control unit (biogas concentration control means) 13. The concentration control unit 13 includes a computer (CPU), a programmable logic controller (PLC), and the like. The concentration device 4, the concentration meter 5, the main path flow rate adjustment valve 7, and the auxiliary path flow rate adjustment valve 12 described above, They are electrically connected by a wired or wireless telecommunication line that transmits and receives electrical signals.

  In the concentration control unit 13, the concentration of biogas generated in the fermenter 2 can be acquired as a measurement value of the concentration meter 5. Further, the concentration control unit 13 can acquire the composition value of the concentrated gas generated by the concentrating device 4. Thereby, according to the concentration control part 13, the composition of the fuel gas supplied into the generator 3 mentioned above according to the control program recorded inside using the measured value of the concentration of biogas and the composition value of the concentrated gas. It is possible to calculate the mixing ratio of the biogas and the concentrated gas for optimizing the ratio. Furthermore, the concentration control unit 13 can transmit control signals such as an opening degree and an opening time to the main path flow rate control valve 7 and the sub path flow rate control valve 12 based on the calculation result.

  That is, according to the biogas power generation facility 1 of the present embodiment, the concentration controller 13 is electrically connected to the concentrator 4, the concentration meter 5, the main path flow rate adjustment valve 7, and the sub path flow rate adjustment valve 12. When the components of the biogas fluctuate by controlling the main flow rate control valve 7 and the sub route flow control valve 12 while measuring the concentration of the biogas generated in the fermenter 2 in real time using Even so, the mixed gas having the required composition can be automatically and stably supplied to the generator 3.

Next, the operation method of the biogas power generation facility 1 of the present embodiment will be described.
Here, when the concentration of methane gas (CH ₄ ) in the biogas generated in the fermenter 2 is within a predetermined concentration range (for example, 55% by volume or more), first, in the main path L1, the biometer is operated by the concentration meter 5. Measure the methane gas concentration in the gas. If the measured value of the methane gas concentration by the densitometer 5 is, for example, 55% by volume or more, the biogas is pumped by the main path compressor 6 and the biogas flow rate is adjusted by the main path flow rate control valve 7. Thereafter, fuel gas (that is, unadjusted biogas) is supplied to the generator 3 via the gas mixing facility 8, the buffer tank 9, and the mixed gas flow rate control valve 10. In this case, the sub route L2 is not activated.

On the other hand, when the concentration of methane gas (CH ₄ ) in the biogas generated in the fermenter 2 is outside the range of the predetermined concentration (for example, less than 55% by volume), first, the densitometer 5 To confirm the change with time of concentration fluctuation of biogas generated in At this time, when the concentration control unit 13 predicts that the biogas concentration is less than the predetermined concentration from the above-described change over time, the sub-path compressor 11 is used before the actual measurement value of the densitometer 5 reaches the predetermined concentration. And the concentration apparatus 4 is started.

  Next, when it is confirmed that the measurement value of the densitometer 5 has reached a predetermined concentration (for example, less than 55% by volume), the concentration control unit 13 sends the main path flow rate control valve 7 and the sub-path flow rate control valve 12 to each other. Control signal is transmitted. As a result, the flow rate of the biogas from the main route L1 and the flow rate of the concentrated gas from the sub route L2 are adjusted and supplied to the gas mixing facility 8. In this gas mixing equipment 8, it is automatically adjusted to become a predetermined component. The adjusted mixed gas is supplied as fuel gas to the generator 3 through the buffer tank 8 and the mixed gas flow rate control valve 10.

Next, when it is detected by the concentration meter 5 that the concentration of methane gas (CH ₄ ) in the biogas generated in the fermenter 2 has increased to 60%, the concentration control unit 13 causes the main path flow rate control valve 7 to be connected to the generator. 3 is returned to a predetermined flow rate setting value required for the third flow, the sub-path flow rate adjusting valve 12 is closed, and the operations of the sub-path compressor 11 and the concentrating device 4 are stopped.

  As described above, according to the biogas power generation facility 1 of the present embodiment, the concentrating device 4 is provided in the sub-path L2 branched from the main path L1 that supplies biogas from the fermenter 2 to the generator 3. The concentrated biogas (concentrated gas) is returned from the sub route L2 to the main route L1. For this reason, without using fuel other than biogas, there is no restriction on the power generation output due to the composition variation of biogas. Therefore, the biogas power generation facility 1 can be stably operated.

Further, according to the biogas power plant 1 of the present embodiment, a concentration meter 5 provided on the primary side of the branch point P ₁ of the main path L1, the concentrator 4, the main path flow rate provided in the main path L1 The control valve 7 and the sub-path flow rate control valve 12 provided in the sub-path L <b> 2 are electrically connected to the concentration control unit 13. For this reason, the main path flow rate control valve 7 and the sub-path flow rate control valve 12 can be controlled while measuring the concentration of the biogas generated in the fermenter 2 in real time. Therefore, even if the component of the biogas generated in the fermenter 2 fluctuates, the mixed gas having a required composition can be automatically and stably supplied to the generator 3.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the biogas power plant 1 of the above-described embodiment has described an arrangement in which concentration meter 5 is provided on the primary side of the branch point P ₁ of the main path L1 as an example, provided in the mixing equipment 8 and a buffer tank 9 It is good also as a structure. Moreover, the structure which provides multiple densitometers in the position mentioned above may be sufficient.

  Moreover, in the biogas power generation facility 1 of the above-described embodiment, the configuration in which the concentrated gas generated by the concentrator 4 is directly supplied to the mixing facility 8 has been described as an example. However, the concentrator 4 and the sub-route flow rate of the sub-path L2 A buffer tank for storing the concentrated gas may be provided between the control valve 12 and the control valve 12. Thereby, when the component of the biogas generated in the fermenter 2 fluctuates, the concentrated gas can be immediately supplied to the main path L1, so that the response speed can be improved.

A specific example is shown below.
As the biogas power generation facility of the present invention, the facility having the configuration shown in FIG. 1 was used.

Example 1
The biogas power generation facility of the present invention was operated. First, the composition of biogas generated in the fermentor was measured by a densitometer, and the methane gas concentration in the biogas was 55% by volume, and the carbon dioxide concentration was 45% by volume.

Next, in the main path, the main path compressor was operated to increase the pressure to 0.01 MPaG, and biogas was supplied to the mixing facility at a flow rate of 128 m ³ / h by the main path flow rate control valve.

On the other hand, biogas was fractionated from the main route to the sub route at a flow rate of 40 m ³ / h, and the pressure was increased to 0.1 MPaG by the sub route compressor, and then supplied to the concentrator. With this concentrator, a concentrated gas having a methane gas concentration of 90% by volume and a carbon dioxide concentration of 10% by volume was obtained.

Next, the obtained concentrated gas was supplied to the mixing facility at a flow rate of 22 m ³ / h by a sub-path flow rate control valve.

Next, in the mixing facility, methane gas from the main route and concentrated gas from the sub route were mixed. As a result, a mixed gas having a methane gas concentration of 60.1% by volume and a carbon dioxide concentration of 39.9% by volume was obtained at a flow rate of 150 m ³ / h.

DESCRIPTION OF SYMBOLS 1 ... Biogas power generation equipment, 2 ... Fermenter, 3 ... Generator, 4 ... Concentrator, 5 ... Densitometer (concentration measuring means), 6 ... Main path compressor (1st compressor), 7 ... Main path flow rate Control valve (first flow rate adjusting means), 8 ... mixing equipment (mixing means), 9 ... buffer tank, 10 ... mixed gas flow rate adjusting valve, 11 ... sub-path compressor (second compressor), 12 ... sub-path flow rate Control valve (second flow rate adjusting means), 13 ... concentration control unit (biogas concentration control means), L1 ... main path, L2 ... sub-path, P ₁ ... branch point, P ₂ ... confluence

Claims (8)

A fermentor that generates biogas;
A generator for generating electricity using the biogas as fuel;
A main path for supplying the biogas from the fermentor to the generator;
A sub-route for branching from the main route, separating a portion of the biogas from the main route, joining the main route, and returning the concentrated biogas to the main route;
A biogas power generation facility comprising: a concentrator for concentrating components in the biogas provided in the sub-path.   The biogas power generation facility according to claim 1, further comprising concentration measuring means provided in the main path. First flow rate adjusting means provided between a branch point of the main route with the sub route and a junction with the sub route;
The biogas power generation facility according to claim 1, further comprising: a second flow rate adjusting unit provided on a secondary side of the concentrating device in the sub path.   The apparatus according to claim 3, further comprising a biogas concentration control unit connected by the concentration measuring unit, the concentrating device, the first flow rate adjusting unit, the second flow rate adjusting unit, and an electric communication line for transmitting and receiving an electric signal. The biogas power generation facility described. A first compressor provided between the branch point of the main path and the first flow rate adjusting means;
The biogas power generation facility according to claim 3 or 4, further comprising: a second compressor provided on a primary side of the concentrator in the sub route.   The biogas power generation facility according to any one of claims 3 to 5, wherein a mixing means is provided at the junction.   The biogas power generation facility according to any one of claims 1 to 6, wherein a buffer tank is provided on a primary side of the generator in the main path.   The biogas power generation facility according to any one of claims 1 to 7, wherein the concentrating device is any one of a pressure fluctuation adsorption method, a membrane separation method, a high-pressure water absorption method, and an amine absorption method. .

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