Mixed fuel supply device

Abstract

To provide a mixed fuel supply device capable of controlling a flow rate of secondary fuel gags so as to realize a volumetric mixing ratio closer to a target volumetric mixing ratio at a time closer to a target time.SOLUTION: A mixed fuel supply device 1 is configured to supply a mixed fuel gas G, which is obtained by mixing a main fuel gas Gm supplied to a main fuel gas pipe 11 with a secondary fuel gas Gs supplied from a secondary fuel gas pipe 13, to a mixed fuel utilization device 2. A control unit 15 calculates the flow rate Z of the secondary fuel gas Gs using a formula of Z=α / 100×A×Qm / {(1-α / 100)×Qm+α / 100×Qs}, and instructs a flow rate controller 14 on the calculated target flow rate Z of the secondary fuel gas Gs. Here, A is a main fuel gas flow rate, B is a main fuel gas flow rate after control, Z is a secondary fuel gas flow rate after control, α is a target volumetric mixing ratio of the secondary fuel gas defined by a formula of 100×Z / (B+Z), Qm is a main fuel gas calorific value, and Qs is a secondary fuel gas calorific value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a mixed fuel supply device.

Background Art

[0002] Conventionally, a mixed fuel gas in which a secondary fuel gas such as hydrogen is mixed with a main fuel gas such as city gas is supplied to a mixed fuel utilization device such as a gas engine or a burner via a mixed fuel supply device, and the mixed fuel utilization device is operated in a co-firing mode.

[0003] In addition, Patent Document 1 discloses a technique for controlling the operation of a gas engine as follows. First, a first fuel is supplied to the gas engine, and the gas engine is driven based on a first operation parameter corresponding to the first fuel. Next, while continuously decreasing the supply amount of the first fuel to the gas engine, a second fuel different from the first fuel is supplied to the gas engine based on an amount determined according to the rate of decrease in the supply amount of the first fuel to the gas engine, and the gas engine is operated based on a third operation parameter determined according to the time from the start point of the decrease in the supply amount of the first fuel to the end point of the supply of the first fuel. Next, the second fuel is supplied to the gas engine, and the gas engine is operated based on a second operation parameter corresponding to the second fuel.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a mixed fuel utilization device that performs co-firing operation with a mixed fuel gas in which a secondary fuel gas is mixed with a main fuel gas, it is important to suppress the occurrence of abnormal combustion caused by the introduction of the secondary fuel gas via the mixed fuel supply device and to be able to perform co-firing operation in a stable state.

[0006] However, conventionally, in a generally known mixed fuel supply device, even if the flow rate of the auxiliary fuel gas is controlled so that the volume mixing ratio of the auxiliary fuel gas becomes the target volume mixing ratio after a target time from the start of mixing the auxiliary fuel gas into the main fuel gas, actually, the volume mixing ratio of the auxiliary fuel gas after control becomes larger than the target volume mixing ratio, and the time to reach the target volume mixing ratio may also become earlier than the target time. Therefore, in a conventionally generally known mixed fuel supply device, there is a very high possibility that abnormal combustion of the mixed fuel gas will occur.

[0007] In contrast, an improvement can be considered in which the target flow rate of the auxiliary fuel gas is recalculated at time intervals sufficiently shorter than the target time, and the flow rate of the auxiliary fuel gas is controlled. According to this improvement, the deviation between the volume mixing ratio after control and the target volume mixing ratio can be reduced. However, even with this improvement, the problem that the target volume mixing ratio is reached earlier than the target time cannot be improved. Therefore, in the mixed fuel supply device according to this improvement plan, there is also a high possibility that abnormal combustion of the mixed fuel gas will occur.

[0008] The present invention has been made in view of such problems, and aims to provide a mixed fuel supply device capable of controlling the flow rate of the auxiliary fuel gas so that the volume mixing ratio is closer to the target volume mixing ratio at a time closer to the target time.

Means for Solving the Problems

[0009] The mixed fuel supply device according to the present invention is as follows.

[0010] [1] A mixed fuel supply device for supplying a mixed fuel gas in which an auxiliary fuel gas is mixed with a main fuel gas to a mixed fuel using device, a main fuel gas pipe to which the main fuel gas is supplied, a flow meter provided in the main fuel gas pipe for measuring the flow rate of the main fuel gas, a sub - fuel gas pipe connected to the main fuel gas pipe and to which the sub - fuel gas is supplied, A flow controller provided in the sub - fuel gas pipe for adjusting the flow rate of the sub - fuel gas to be mixed with the main fuel gas; and a control unit for controlling the flow controller, wherein the control unit calculates the target flow rate of the sub - fuel gas using at least the target volume mixing ratio of the sub - fuel gas input from the outside, the initial flow rate of the main fuel gas measured by the flow meter, the calorific value of the main fuel gas, and the calorific value of the sub - fuel gas, and is configured to instruct the calculated target flow rate of the sub - fuel gas to the flow controller. A mixed fuel supply device.

[0011] [2] The control unit sets the initial flow rate of the main fuel gas as A, the flow rate of the main fuel gas after control as B, the flow rate of the sub - fuel gas after control as Z, defines the target volume mixing ratio of the sub - fuel gas input from the outside to the control unit as α by the formula 100×Z / (B + Z), the calorific value of the main fuel gas as Qm, when the calorific value of the sub - fuel gas is Qs, calculates the flow rate Z of the sub - fuel gas by the formula Z = α / 100×A×Qm / {(1 - α / 100)×Qm+α / 100×Qs}. The mixed fuel supply device according to [1].

[0012] [3] The control unit further calculates the target flow rate of the sub - fuel gas using the thermal efficiency of the mixed - fuel utilization device when only the main fuel gas is supplied to the mixed - fuel utilization device and the thermal efficiency of the mixed - fuel utilization device when the sub - fuel gas is mixed with the main fuel gas and supplied at the target volume mixing ratio. The mixed fuel supply device according to [1].

[0013] [4] The control unit sets the initial flow rate of the main fuel gas as A, the flow rate of the main fuel gas after control as B, the flow rate of the auxiliary fuel gas after control as Z, defines the target volume mixing ratio α of the auxiliary fuel gas, which is input to the control unit from the outside, by the formula 100×Z / (B + Z), the calorific value of the main fuel gas as Qm, the calorific value of the auxiliary fuel gas as Qs, the thermal efficiency of the mixed fuel utilization device when only the main fuel gas is supplied to the mixed fuel utilization device as ηa, when the thermal efficiency of the mixed fuel utilization device when the auxiliary fuel gas is mixed with and supplied to the main fuel gas at the target volume mixing ratio is ηb, calculates the flow rate Z of the auxiliary fuel gas by the formula Z = ηa / ηb×α / 100×A×Qm / {(1 - α / 100)×Qm + α / 100×Qs}, The mixed fuel supply device according to [3].

Advantages of the Invention

[0014] In the mixed fuel supply device according to the above [1], the control unit is configured to calculate the target flow rate of the auxiliary fuel gas using at least the target volume mixing ratio of the auxiliary fuel gas input from the outside, the initial flow rate of the main fuel gas, the calorific value of the main fuel gas, and the calorific value of the auxiliary fuel gas, and to instruct the calculated target flow rate of the auxiliary fuel gas to the flow rate controller.

[0015] Therefore, the mixed fuel supply device according to the above [1] can reduce the deviation between the volume mixing ratio after control and the target volume mixing ratio, and can reach the target volume mixing ratio in a time closer to the target time. Therefore, according to the mixed fuel supply device according to the above [1], since the flow rate of the auxiliary fuel gas can be controlled so as to obtain a volume mixing ratio closer to the target volume mixing ratio in a time closer to the target time, more accurate control can be performed.

[0016] The hybrid fuel supply device described in [2] is the hybrid fuel supply device described in [1], wherein the control unit calculates the flow rate Z of the auxiliary fuel gas after control by the formula Z = α / 100 × A × Qm / {(1 - α / 100) × Qm + α / 100 × Qs}, and is configured to instruct the calculated target flow rate Z of the auxiliary fuel gas to the flow controller.

[0017] Therefore, the hybrid fuel supply device described in [2] can ensure the effects of the hybrid fuel supply device described in [1].

[0018] The hybrid fuel supply device described in [3] is the hybrid fuel supply device described in [1], wherein the control unit further uses the thermal efficiency of the hybrid fuel utilization device when only the main fuel gas is supplied to the hybrid fuel utilization device and the thermal efficiency of the hybrid fuel utilization device when the auxiliary fuel gas is mixed with the main fuel gas at the target volume mixing ratio and supplied to calculate the flow rate of the target auxiliary fuel gas. That is, in the hybrid fuel supply device described in [3], the flow rate of the auxiliary fuel gas is controlled in consideration of the thermal efficiency of the hybrid fuel utilization device that changes due to the mixing of the auxiliary fuel gas into the main fuel gas.

[0019] Therefore, the hybrid fuel supply device described in [3] can control the flow rate of the auxiliary fuel gas so that the volume mixing ratio is closer to the target volume mixing ratio in a time closer to the target time compared to the hybrid fuel supply device described in [1], and thus can perform more accurate control.

[0020] The hybrid fuel supply device described in [4] is the hybrid fuel supply device described in [3], wherein the control unit calculates the flow rate Z of the auxiliary fuel gas after control by the formula Z = ηa / ηb × α / 100 × A × Qm / {(1 - α / 100) × Qm + α / 100 × Qs}, and is configured to instruct the calculated target flow rate Z of the auxiliary fuel gas to the flow controller.

[0021] Therefore, the hybrid fuel supply device described in [4] above can ensure the effects of the hybrid fuel supply device described in [3].

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0023] (Embodiment 1) The hybrid fuel supply device according to Embodiment 1 will be described with reference to FIGS. 1 to 7. First, the schematic device configuration of the hybrid fuel supply device 1 according to Embodiment 1 will be described.

[0024] As illustrated in FIG. 1, the mixed fuel supply device 1 of Embodiment 1 is a device for supplying a mixed fuel gas G obtained by mixing an auxiliary fuel gas Gs with a main fuel gas Gm to a mixed fuel utilization device 2.

[0025] Examples of the main fuel gas Gm include, for example, city gas, propane gas, etc. Examples of the auxiliary fuel gas Gs include hydrogen, ammonia, biogas (digested gas) generated by fermenting organic waste (such as livestock manure, food waste, organic residues, sewage sludge, etc.). Examples of the mixed fuel utilization device 2 include, for example, combustion devices such as gas engines and gas burners. The combustion device may be one possessed by a combustion device system.

[0026] In Embodiment 1, the case where the main fuel gas Gm is city gas (such as 13A), the auxiliary fuel gas Gs is hydrogen, and the mixed fuel utilization device 2 is the gas engine 21 possessed by the combustion device system 20 will be used as an example for explanation, but it is not limited thereto. Examples of the combustion device system 20 having the gas engine 21 include, for example, a gas engine power generation system.

[0027] The combustion device system 20 has a gas engine 21 as the mixed fuel utilization device 2. The gas engine 21 is configured to generate power by burning the mixed fuel gas G obtained by mixing the auxiliary fuel gas Gs with the main fuel gas Gm, or by burning the main fuel gas Gm. In the combustion device system 20, the mixed fuel gas G supplied through the main fuel gas pipe 11 (described later) extending from the mixed fuel supply device 1 is supplied to the gas engine 21 via the system-side flow controller 210. The system-side flow controller 210 adjusts the flow rate of the mixed fuel gas G supplied to the gas engine 21 in accordance with an instruction from a system-side control unit (not shown) of the combustion device system 20. In FIG. 1, the case where the mixed fuel gas G is supplied from the mixed fuel supply device 1 to the gas engine 21 is shown, but when the auxiliary fuel gas Gs is not mixed with the main fuel gas Gm, the main fuel gas Gm is supplied from the mixed fuel supply device 1 to the gas engine 21.

[0028] The hybrid fuel supply device 1 includes a main fuel gas pipe 11, a flow meter 12, a sub-fuel gas pipe 13, a flow controller 14, and a control unit 15.

[0029] The main fuel gas pipe 11 is supplied with main fuel gas Gm from an external main fuel gas source (not shown). Further, the main fuel gas pipe 11 is provided with a flow meter 12 for measuring the flow rate of the main fuel gas Gm.

[0030] The sub-fuel gas pipe 13 is connected to the main fuel gas pipe 11 and is supplied with sub-fuel gas Gs from an external sub-fuel gas source (not shown). The sub-fuel gas pipe 13 is provided with a flow controller 14, and the flow controller 14 adjusts the flow rate of the sub-fuel gas Gs to be mixed with the main fuel gas Gm. An instruction for adjusting the flow rate of the sub-fuel gas Gs is input from the control unit 15 to the flow controller 14 (arrow 15c). The flow controller 14 adjusts the flow rate of the sub-fuel gas Gs in response to the instruction from the control unit 15. Specifically, a mass flow controller can be used as the flow controller 14.

[0031] The control unit 15 is configured to be able to control the flow controller 14. Here, the control unit 15 is configured using a computer. The control unit 15 is capable of performing sequence control, and specifically, a sequence control device (sequencer) can be used.

[0032] The flow rate of the main fuel gas Gm measured by the flow meter 12 is input to the control unit 15 (arrow 15a). At least the target volume mixing ratio (vol%) which is the target volume mixing ratio of the auxiliary fuel gas Gs to be achieved by control is input to the control unit 15 (arrow 15b). Further, the control unit 15 instructs (outputs) the flow rate of the target auxiliary fuel gas Gs to the flow rate controller 14 (arrow 15c). In addition, other information such as an instruction to start mixing of the auxiliary fuel gas Gs, an instruction to end mixing of the auxiliary fuel gas Gs, and failure information of the combustion equipment system 20 for emergency stop of mixing of the auxiliary fuel Gs may be input to the control unit 15 from the combustion equipment system 20.

[0033] Next, the control by the control unit 15 of the mixed fuel supply device 1 of Embodiment 1 will be described while comparing it with the control by the control units of the mixed fuel supply device of Comparative Form 1 and the mixed fuel supply device of Comparative Form 2. Note that the mixed fuel supply device of Comparative Form 1 and the mixed fuel supply device of Comparative Form 2 have the same schematic device configuration as the mixed fuel supply device 1 of Embodiment 1, but the control method of the auxiliary fuel gas Gs by the control unit is different.

[0034] <Control method in Comparative Form 1> The control of the auxiliary fuel gas Gs by the control unit of the mixed fuel supply device of Comparative Form 1 which is a conventional general mixed fuel supply device is basically performed as follows.

[0035] As shown in FIG. 2, in the mixed fuel supply device of Comparative Form 1, the sequence control for mixing the secondary fuel gas Gs is started (U1). The control unit in the mixed fuel supply device of Comparative Form 1 calculates the target flow rate of the secondary fuel gas Gs from the target volume mixing ratio of the secondary fuel gas Gs input from the outside and the current flow rate of the main fuel gas Gm measured by the flow meter 12, that is, the initial flow rate of the main fuel gas Gm (U2). Next, the control unit in the mixed fuel supply device of Comparative Form 1 instructs the calculated target flow rate of the secondary fuel gas Gs to the flow controller 14 (U3). The flow controller 14 that has received the instruction from the control unit adjusts the flow rate of the secondary fuel gas Gs. Thereby, the mixed fuel gas G in which the secondary fuel gas Gs is mixed with the main fuel gas Gm at a predetermined volume mixing ratio is supplied to the gas engine 21 of the combustion equipment system 20. After the above instruction to the flow controller 14, the control by the control unit in the mixed fuel supply device of Comparative Form 1 shifts to control for maintaining, increasing, or stopping the flow rate of the secondary fuel gas Gs (U4).

[0036] The control of the secondary fuel gas Gs by the control unit of this mixed fuel supply device of Comparative Form 1 will be described in more detail with reference to FIG. 3.

[0037] As shown in FIG. 3, in Comparative Form 1, let A be the flow rate of the initial main fuel gas Gm, B1 be the flow rate of the main fuel gas Gm after control, X be the flow rate of the secondary fuel gas Gs after control, α be the target volume mixing ratio of the secondary fuel gas Gs when mixing the secondary fuel gas Gs with the main fuel gas Gm, and β1 be the volume mixing ratio of the secondary fuel gas Gs after control.

[0038] In Comparative Form 1, α = 100×X / (A + X) ··· (Equation C1-1) From the relationship of X = A×α / (100 - α) ··· (Equation C1-2) is obtained. In the conventional control, α is calculated from Equation C1-1, that is, the denominator of Equation C1-1 is set to (A + X) because the flow rate of the main fuel gas Gm after control is unknown. Therefore, the control unit of the hybrid fuel supply device in Comparative Form 1 sends a command X calculated by Equation C1-2 to the flow controller 14. At this time, in combustion equipment such as the gas engine 21, if the gas composition changes suddenly, combustion is likely to become unstable. Therefore, usually, control is performed so that the volume mixing ratio of the sub-fuel gas Gs gradually changes and becomes the target volume mixing ratio after a predetermined target time T.

[0039] However, in actual combustion equipment, when the sub-fuel gas Gs is introduced, as shown in FIG. 3, the flow rate A of the main fuel gas Gm decreases by the amount of heat covered by the sub-fuel gas Gs. Therefore, when the flow rate of the sub-fuel gas Gs is controlled using Equation C1-1, since the flow rate of the main fuel gas Gm after reduction (after control) is B1, the actual volume mixing ratio β1 of the sub-fuel gas Gs after control is β1 = 100×X / (B1 + X) ··· (Equation C1-3) Here, since B1 + X and A + X satisfy the relationship B1 + X < A + X, as shown in FIG. 3, the actual volume mixing ratio β1 of the sub-fuel gas Gs after control is larger than the target volume mixing ratio α of the sub-fuel gas Gs, that is, β1 deviates greatly from α.

[0040] Substituting specific numerical values, it becomes as follows. In Comparative Form 1, when A = 100 (m 3 / min) and α = 10 (vol%), from Equation C1-2, X = 100×10 / (100 - 10) = 11.11 (m 3 / min) It becomes. Also, assuming the heat quantity ratio of the main fuel gas Gm to the sub-fuel gas Gs is 4:1, since the main fuel gas Gm decreases by the amount of heat covered by the sub-fuel gas Gs, the flow rate B1 of the main fuel gas Gm after control is B1 = 100 - 11.11×1 / 4 = 97.22 (m 3 / min) It becomes. That is, the volume mixing ratio β1 of the sub-fuel gas Gs after control is, from Equation C1-3, β1 = 100×11.11 / (97.22 + 11.1) = 10.26 (vol%) Therefore, α < β1, which causes a problem.

[0041] In addition, the time T1 to reach the target volume mixing ratio α becomes shorter than the target time T. As a result, in the mixed fuel supply device of the conventionally generally known comparative form 1, there is a very high possibility of abnormal combustion of the mixed fuel gas G occurring.

[0042] <Control method in Comparative Form 2> Next, the mixed fuel supply device of Comparative Form 2 is an improvement of the mixed fuel supply device of Comparative Form 1 described above, which recalculates the target flow rate of the auxiliary fuel gas Gs at time intervals sufficiently shorter than the target time, and controls the flow rate of the auxiliary fuel gas Gs. The control of the auxiliary fuel gas Gs by the control unit of this mixed fuel supply device of Comparative Form 2 is basically performed as follows.

[0043] As shown in FIG. 4, in the mixed fuel supply device of Comparative Form 2, the sequence control for mixing the secondary fuel gas Gs is started (V1). The control unit in the mixed fuel supply device of Comparative Form 2 calculates the target flow rate of the secondary fuel gas Gs from the target volume mixing ratio of the secondary fuel gas Gs input from the outside and the current flow rate of the main fuel gas Gm measured by the flow meter 12, that is, the initial flow rate of the main fuel gas Gm (V2). Next, the control unit in the mixed fuel supply device of Comparative Form 2 instructs the calculated target flow rate of the secondary fuel gas Gs to the flow controller 14 (V3). Next, after a certain time period that is sufficiently shorter than the target time, the control unit in the mixed fuel supply device of Comparative Form 2 calculates the target flow rate of the secondary fuel gas Gs again from the target volume mixing ratio of the secondary fuel gas Gs and the current flow rate of the main fuel gas Gm measured by the flow meter 12 (V4). Next, the control unit in the mixed fuel supply device of Comparative Form 2 determines whether the target time T has elapsed. And when the target time T has not elapsed, the control unit in the mixed fuel supply device of Comparative Form 2 instructs the recalculated target flow rate of the secondary fuel gas Gs to the flow controller 14 (V5, arrow NO). On the other hand, when the target time T has elapsed, the control unit in the mixed fuel supply device of Comparative Form 2 moves to the next step (V5, arrow YES) and shifts to the control of maintaining, increasing, or stopping the flow rate of the secondary fuel gas Gs (V6).

[0044] The control of the secondary fuel gas Gs by the control unit of this mixed fuel supply device of Comparative Form 2 will be described in more detail with reference to FIG. 5.

[0045] As shown in FIG. 5, in Comparative Form 2, let A be the initial flow rate of the main fuel gas Gm, B2 be the flow rate of the main fuel gas Gm after control, Y1 be the initial target flow rate of the secondary fuel gas Gs, Y2 be the target flow rate of the secondary fuel gas Gs after recalculation, Y3 be the target flow rate of the secondary fuel gas Gs after repeated recalculation, Z2 be the flow rate of the secondary fuel gas Gs after control, α be the target volume mixing ratio of the secondary fuel gas Gs when mixing the secondary fuel gas Gs with the main fuel gas Gm, and β2 be the volume mixing ratio of the secondary fuel gas Gs after control.

[0046] In Comparative Form 2, the recalculation of the target flow rate of the secondary fuel gas Gs is performed at time intervals that are sufficiently shorter than the target time T. Then, as shown in FIG. 5, in accordance with the decreasing main fuel gas Gm, the target flow rate Y2 of the recalculated secondary fuel gas Gs, the target flow rate Y3 of the re-recalculated secondary fuel gas Gs, and so on, gradually decrease. Therefore, the flow rate supply device of Comparative Form 2 can reduce the deviation between the actual volume mixing ratio β2 of the secondary fuel gas Gs after control and the target volume mixing ratio α of the secondary fuel gas Gs, as compared with the flow rate supply device of Comparative Form 1.

[0047] Substituting specific numerical values, it becomes as follows. In Comparative Form 2, when A = 100 (m 3 / min) and α = 10 (vol%), the initial target flow rate Y1 of the secondary fuel gas Gs is, from Equation C1-2 described above in Comparative Form 1, Y1 = 100×10 / (100−10) = 11.11 (m 3 / min) and it becomes. Assume that the target time T from the start of control to the end of control is T = 6 (sec), and the recalculation period is 2 (sec). That is, here, consider the case where the secondary fuel gas Gs reaches the final target flow rate in the third cycle. In this case, at 2 (sec) in the first cycle, the flow rate Z of the secondary fuel gas Gs I is Z I = 11.11×2 / 6 = 3.71 (m 3 / min) and it becomes. At this time, the flow rate A1 of the main fuel gas Gm is A1 = 100−3.71×1 / 4 = 99.07 (m 3 / min) and it becomes. Also, the target flow rate Y2 of the secondary fuel gas Gs in the second cycle is, from Equation C1-2, Y2 = 99.07×10 / (100−10) = 11.01 (m 3 / min) and it becomes. At 2 (sec) in the second cycle, the flow rate Z of the secondary fuel gas Gs II is Z II=3.71 + 11.01×2 / 6 = 7.38 (m 3 / min) This results in. At this time, the flow rate A2 of the main fuel gas Gm is A2 = 100 - 7.83×1 / 4 = 98.04 (m 3 / min) This results in. Calculating in the same way, the target flow rate Y3 of the auxiliary fuel gas Gs in the third cycle is Y3 = 10.91 (m 3 / min) This results in. The flow rate Z of the auxiliary fuel gas after control III is Z III = 11.01 (m 3 / min) This results in. The flow rate A3 of the main fuel gas Gm at this time, that is, the flow rate B2 of the main fuel gas Gm after control, is A3 = B2 = 97.25 (m 3 / min) This results in. Therefore, the volume mixing ratio β2 of the auxiliary fuel gas Gs after control is, from Equation C1 - 3 described above in Comparative Form 1 β2 = 100×10.91 / (97.25 + 11.01) = 10.17 (vol%) This results in. Thus, it can be seen that the flow rate supply device of Comparative Form 2 can reduce the deviation between the actual volume mixing ratio β2 of the auxiliary fuel gas Gs after control and the target volume mixing ratio α of the auxiliary fuel gas Gs compared to the flow rate supply device of Comparative Form 1. However, there is a slight deviation between the two volume mixing ratios.

[0048] However, the flow rate supply device of Comparative Form 2 still cannot improve the problem of reaching the target volume mixing ratio α earlier than the target time T. Therefore, this mixing fuel supply device of Comparative Example 2 also has a high possibility of abnormal combustion of the mixed fuel gas G.

[0049] <Control Method in Embodiment 1> In contrast, the control of the secondary fuel gas Gs by the control unit of the hybrid fuel supply device 1 according to Embodiment 1 is basically performed as follows.

[0050] As shown in FIG. 6, in the hybrid fuel supply device 1 according to Embodiment 1, sequence control for mixing the secondary fuel gas Gs is started (S1). The control unit 15 in the hybrid fuel supply device 1 according to Embodiment 1 calculates the target flow rate of the secondary fuel gas Gs from the target volume mixing ratio of the secondary fuel gas Gs input from the outside, the current flow rate of the main fuel gas Gm measured by the flow meter 12, that is, the initial flow rate of the main fuel gas Gm, the calorific value of the main fuel gas Gm, and the calorific value of the secondary fuel gas Gs (S2). Next, the control unit 15 in the hybrid fuel supply device 1 according to Embodiment 1 instructs the calculated target flow rate of the secondary fuel gas Gs to the flow controller 14 (S3). The flow controller 14 that has received the instruction from the control unit 15 adjusts the flow rate of the secondary fuel gas Gs. As a result, the mixed fuel gas G in which the secondary fuel gas Gs is mixed with the main fuel gas Gm at a predetermined volume mixing ratio is supplied to the gas engine 21 of the combustion equipment system 20. After the above instruction to the flow controller 14, the control by the control unit 15 in the hybrid fuel supply device 1 according to Embodiment 1 shifts to control for maintaining, increasing, or stopping the flow rate of the secondary fuel gas Gs (S4).

[0051] The control of the secondary fuel gas Gs by the control unit 15 of the hybrid fuel supply device 1 according to this Embodiment 1 will be described in more detail with reference to FIG. 7. The hybrid fuel supply device 1 according to Embodiment 1 predicts the flow rate of the secondary fuel gas Gs at the target volume mixing ratio to enable more accurate control.

[0052] As shown in FIG. 7, in Embodiment 1, let A be the flow rate of the initial main fuel gas Gm, B be the flow rate of the main fuel gas Gm after control, Z be the flow rate of the secondary fuel gas Gs after control, and α be the target volume mixing ratio of the secondary fuel gas Gs when mixing the secondary fuel gas Gs with the main fuel gas Gm. In Embodiment 1, α is defined by the formula α = 100×Z / (B + Z). Also, in Embodiment 1, let Qm be the calorific value of the main fuel gas and Qs be the calorific value of the secondary fuel gas.

[0053] In Embodiment 1, since the calorific value before and after the mixing of the auxiliary fuel gas Gs into the main fuel gas Gm is the same, A × Qm = B × Qm + Z × Qs ··· (Equation 1-1) The following relationship can be obtained. Here, in Embodiment 1, the target volume mixing ratio α of the auxiliary fuel gas Gs is α = 100 × Z / (B + Z) ··· (Equation 1-2) Since it is defined in this way, substituting Equation 1-2 into Equation 1-1 and calculating gives Z = α / 100 × A × Qm / {(1 - α / 100) × Qm + α / 100 × Qs} ··· (Equation 1-3) This is the result.

[0054] This Equation 1-3 is stored in advance in the control unit 15 of the mixed fuel supply device 1 of Embodiment 1. In this Equation 1-3, as described above, α is input from the outside to the control unit 15. Also, Qm and Qs in Equation 1-3 are determined by the type, specifications, etc. of the mixed fuel utilization device 2 to which the mixed fuel supply device 1 is applied, and are set to predetermined values according to the main fuel gas type and the auxiliary fuel gas type. Therefore, Equation 1-3 can be stored in the control unit 15 in a form in which predetermined values of Qm and Qs determined according to the main fuel gas type and the auxiliary fuel gas type are substituted. In addition to this, Qm and Qs may also be input from the outside to the control unit 15.

[0055] Using the above Equation 1-3, the control unit 15 calculates the target flow rate Z of the auxiliary fuel gas Gs after control from the target volume mixing ratio α of the auxiliary fuel gas Gs, the current flow rate of the main fuel gas Gm, the calorific value Qm of the main fuel gas Gm, and the calorific value Qs of the auxiliary fuel gas Gs.

[0056] In the hybrid fuel supply device 1 of Embodiment 1, by the control unit 15 performing control at the target time T with the calculated Z as the target, it is possible to achieve a volume mixing ratio closer to the target volume mixing ratio α at a mixing time closer to the target time T. That is, as shown in FIG. 7, the hybrid fuel supply device 1 of Embodiment 1 can reduce the deviation between the actual volume mixing ratio of the secondary fuel gas Gs after control and the target volume mixing ratio α of the secondary fuel gas Gs, and can reach the target volume mixing ratio α at a time closer to the target time T.

[0057] Note that the control unit 15 of the hybrid fuel supply device 1 of Embodiment 1 can also apply the above control when reducing the volume mixing ratio of the secondary fuel gas Gs. Also in this case, control can be performed at a more accurate time.

[0058] (Embodiment 2) As shown in FIG. 8, the hybrid fuel supply device 1 of Embodiment 2, compared with the hybrid fuel supply device 1 of Embodiment 1 (see FIG. 6), has the control unit 15 calculate the target flow rate of the secondary fuel gas Gs from the target volume mixing ratio of the secondary fuel gas Gs input from the outside, the current flow rate of the main fuel gas Gm measured by the flow meter 12, the calorific value of the main fuel gas Gm, the calorific value of the secondary fuel gas Gs, the thermal efficiency of the hybrid fuel utilization device 2 when only the main fuel gas Gm is supplied, and the thermal efficiency of the hybrid fuel utilization device 2 when the secondary fuel gas Gs is mixed (S’2). The control of the secondary fuel gas Gs by the control unit 15 other than this is basically performed in the same manner as in Embodiment 1.

[0059] The control of the secondary fuel gas Gs by the control unit 15 of the hybrid fuel supply device 1 of this Embodiment 2 will be described in more detail.

[0060] In the hybrid fuel supply device 1 of Embodiment 2, the formula for calculating the flow rate Z of the secondary fuel gas Gs by the control unit 15 is different from that of the hybrid fuel supply device 1 of Embodiment 1.

[0061] That is, in the hybrid fuel supply device 1 of Embodiment 2, the control unit 15 Z = ηa / ηb × α / 100 × A × Qm / {(1 - α / 100) × Qm + α / 100 × Qs} ··· (Equation 2-1) The flow rate Z of the auxiliary fuel gas is calculated by this formula.

[0062] In Equation 2-1, ηa is the thermal efficiency of the mixed fuel utilization device 2 when only the main fuel gas Gs is supplied to the mixed fuel utilization device 2. Also, ηb is the thermal efficiency of the mixed fuel utilization device 2 when the main fuel gas Gm and the auxiliary fuel gas Gs are mixed and supplied to the mixed fuel utilization device 2 at the target volume mixing ratio α. In Embodiment 2, specifically, ηa is the thermal efficiency of the gas engine 21 of the combustion device system 20 when only the main fuel gas Gs is supplied to the gas engine 21, and ηb is the thermal efficiency of the gas engine 21 of the combustion device system 20 when the main fuel gas Gm and the auxiliary fuel gas Gs are mixed and supplied to the gas engine 21 at the target volume mixing ratio α. For the other α, A, Qm, and Qs, they are the same as those in Equation 1-3 described in Embodiment 1.

[0063] When the thermal efficiency changes after the input of the auxiliary fuel gas Gs to the main fuel gas Gm, such as in the case of the gas engine 21, the relationship of Equation 1-1 described in Embodiment 1 is represented by the following relationship using ηa and ηb. A × Qm × ηa = (B × Qm + Z × Qs) × ηb ··· (Equation 2-2) Then, in the same way as in Embodiment 1, substituting α = 100 × Z / (B + Z) of Equation 1-2 into this Equation 2-2 and calculating, the above-mentioned Equation 2-1 is obtained.

[0064] In the control unit 15 of the hybrid fuel supply device 1 according to the second embodiment, this Expression 2-1 is stored in advance. In this Expression 2-1, α is input from the outside to the control unit 15. Further, Qm and Qs in Expression 2-1 are determined by the type, specifications, etc. of the hybrid fuel utilization device 2 to which the hybrid fuel supply device 1 is applied, and are set to predetermined values according to the main fuel gas type and the sub-fuel gas type. Therefore, Expression 2-1 can be stored in the control unit 15 in a form in which predetermined values of Qm and Qs determined according to the main fuel gas type and the sub-fuel gas type are substituted. In addition to this, the values of Qm and Qs may be input from the outside to the control unit 15. Further, ηa and ηb in Expression 2-1 can be obtained in advance according to the type, specifications, main fuel gas type, and sub-fuel gas type of the hybrid fuel utilization device 2 to which the hybrid fuel supply device 1 is applied. Therefore, Expression 2-1 can be stored in the control unit 15 in a form in which predetermined values of ηa and ηb obtained in advance are substituted. In addition to this, the values of ηa and ηb may be input from the outside to the control unit 15.

[0065] Other configurations are basically the same as those in the first embodiment.

[0066] In the hybrid fuel supply device 1 according to the second embodiment, the flow rate of the sub-fuel gas Gs is controlled in consideration of the thermal efficiency of the hybrid fuel utilization device 2 that changes due to the mixing of the sub-fuel gas Gs into the main fuel gas Gm. Therefore, compared with the hybrid fuel supply device 1 of the first embodiment, the hybrid fuel supply device of the second embodiment can control the flow rate of the sub-fuel gas Gs so that the volume mixing ratio is closer to the target volume mixing ratio α in a time closer to the target time T, and thus more accurate control can be performed.

[0067] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof. Further, the respective configurations shown in the embodiments can be arbitrarily combined with each other.

Explanation of Reference Numerals

[0068] 1 Hybrid fuel supply device 11 Main fuel gas pipe 12 Flow meter 13 Secondary fuel gas pipe 14 Flow controller 15 Control unit 2 Mixed fuel utilization equipment Gm Main fuel gas Gs Secondary fuel gas G Mixed fuel gas

Claims

1. A mixed fuel supply device for supplying a mixed fuel gas in which a sub-fuel gas is mixed with a main fuel gas to a mixed fuel using device, a main fuel gas pipe to which the main fuel gas is supplied, a flow meter provided in the main fuel gas pipe for measuring the flow rate of the main fuel gas, a sub-fuel gas pipe connected to the main fuel gas pipe to which the sub-fuel gas is supplied, a flow controller provided in the sub-fuel gas pipe for adjusting the flow rate of the sub-fuel gas to be mixed with the main fuel gas, and a control unit for controlling the flow controller, wherein the control unit, at least uses the target volume mixing ratio of the sub-fuel gas input from the outside, the initial flow rate of the main fuel gas measured by the flow meter, the calorific value of the main fuel gas, and the calorific value of the sub-fuel gas to calculate the target flow rate of the sub-fuel gas, and is configured to instruct the calculated target flow rate of the sub-fuel gas to the flow controller. Mixed fuel supply device.

2. The control unit, sets the initial flow rate of the main fuel gas as A, the flow rate of the main fuel gas after control as B, the flow rate of the sub-fuel gas after control as Z, defines the target volume mixing ratio of the sub-fuel gas, which is input to the control unit from the outside, by the formula of 100×Z / (B + Z) as α, the calorific value of the main fuel gas as Qm, when the calorific value of the sub-fuel gas is Qs, calculates the flow rate Z of the sub-fuel gas by the formula of Z = α / 100×A×Qm / {(1 - α / 100)×Qm + α / 100×Qs}. The mixed fuel supply device according to Claim 1.

3. The control unit, further uses the thermal efficiency of the mixed fuel using device when only the main fuel gas is supplied to the mixed fuel using device and the thermal efficiency of the mixed fuel using device when the sub-fuel gas is mixed with the main fuel gas and supplied at the target volume mixing ratio to calculate the target flow rate of the sub-fuel gas. The mixed fuel supply device according to Claim 1.

4. The control unit, sets the initial flow rate of the main fuel gas as A, the flow rate of the main fuel gas after control as B, the flow rate of the sub-fuel gas after control as Z, defines the target volume mixing ratio of the sub-fuel gas, which is input to the control unit from the outside, by the formula of 100×Z / (B + Z) as α, the calorific value of the main fuel gas as Qm, the calorific value of the sub-fuel gas as Qs, the thermal efficiency of the mixed fuel using device when only the main fuel gas is supplied to the mixed fuel using device as ηa, When the thermal efficiency of the mixed fuel utilization device is ηb when the auxiliary fuel gas is mixed with and supplied to the main fuel gas at the target volume mixing ratio to the mixed fuel utilization device, The flow rate Z of the auxiliary fuel gas is calculated by the formula Z = ηa / ηb × α / 100 × A × Qm / {(1 - α / 100) × Qm + α / 100 × Qs}, The mixed fuel supply device according to claim 3.

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