JP5525772B2 - Biomass liquid fuel combustion system - Google Patents

Description

  The present invention relates to a combustion system for burning biomass liquid fuel in a power plant or the like.

  2. Description of the Related Art Conventionally, attempts have been made to use biogas made from biomass such as plants or waste materials thereof, livestock manure, garbage, and food waste, or liquid fuel derived from biomass in a combustion system at a power plant. When such a biomass fuel is used, it is necessary to mix with auxiliary fuel made of fossil fuel such as kerosene or city gas at the start of operation.

  For example, Patent Document 1 describes a combustion system capable of controlling the fuel mixture ratio so that the thermal efficiency is optimal when such auxiliary fuel and biomass-derived fuel are mixed.

JP 2004-156501 A

  Here, the biomass-derived liquid fuel has a higher viscosity than the fossil fuel, and in particular, when the temperature is lowered, the fluidity is greatly lowered. For this reason, when the temperature of the biomass liquid fuel is reduced when the power generation system is stopped, there is a problem in that the liquidity of the biomass liquid fuel is fixed to the piping or the like due to a decrease in fluidity, and the supply of the biomass liquid fuel cannot be performed smoothly.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent a decrease in fluidity of the biomass liquid fuel when the combustion system in a power plant or the like is stopped.

  A biomass liquid fuel combustion system according to the present invention is a biomass liquid fuel combustion system, wherein the biomass liquid fuel tank stores the biomass liquid fuel, and the biomass liquid fuel passes through the biomass liquid fuel supply pipe from the biomass liquid fuel tank. Is supplied, and the biomass liquid fuel is burned, an adjustment valve provided in the biomass liquid fuel supply pipe, and the biomass branched from the upstream side of the adjustment valve of the biomass liquid fuel supply pipe A circulation pipe that is provided so as to reach the liquid fuel tank and circulates the biomass liquid fuel from the biomass liquid fuel supply pipe to the biomass liquid fuel tank, and a line heater provided in the circulation pipe. It is characterized by.

  In the above combustion system, a biogas tank in which biomass-derived biogas is stored, and a biogas supply pipe for supplying the biogas from the biogas tank to the engine, the engine includes the biomass liquid fuel and the biogas tank. You may co-fire with biogas.

  A biogas tank storing biomass-derived biogas; and a biogas supply pipe for supplying the biogas from the biogas tank to the engine. The engine includes the biomass liquid fuel and the biogas. It may be mixed.

The engine may further include a return pipe that returns the surplus fuel to the downstream side of the regulating valve of the biomass liquid fuel supply pipe when the fuel supplied from the biomass liquid fuel supply pipe is surplus in the engine. .
The biomass liquid fuel may be a biomass-derived emulsion.

  According to the present invention, even when the engine is not driven, the biomass liquid fuel is circulated through the circulation pipe and is heated in the circulation pipe, so that the fluidity is lowered and it is possible to prevent sticking to the pipe or the like.

It is a graph which shows the power generation efficiency in conditions 1-4. Generation of temperature and NO _x of the fuel in the pump during which exclusive combustion of emulsified fuel condition 2, the amount of CO, is a graph showing the relationship between the power generation efficiency. And the temperature of the fuel at the nozzle inlet when for exclusive combustion of emulsified fuel condition 2, the amount of NO _x, the amount of CO, is a graph showing the relationship between the power generation efficiency. In conditions 5-10, it is a figure which compares the combustion rate of the methane gas in case power generation output is 1 kW, 2 kW, and 3 kW. Generation amount of the NO _x fuel injection pressure in the case of increased If and 10% was the normal pressure for condition 11 is a graph comparing the amount of generated CO. Generation amount of the NO _x in a case where the fuel injection pressure increases when the 10% was the normal pressure for condition 12 is a graph comparing the amount of generated CO. In a state where the fuel injection pressure is increased by 10%, and when earlier 3 ° the fuel injection timing is a graph showing the generation amount of the NO _x in the case of earlier 6 °, the generation amount of CO. It is a graph which shows the electric power generation efficiency and the biogas combustion rate when the fuel injection timing is advanced by 3 ° and when the fuel injection timing is advanced by 6 ° in a state where the fuel injection pressure is increased by 10%. 7 is a graph showing NO _X generation amount, CO generation amount, exhaust gas temperature, and power generation efficiency under condition 13. 7 is a graph showing NO _X generation amount, CO generation amount, exhaust gas temperature, and power generation efficiency under condition 14. 6 is a graph showing NO _X generation amount, CO generation amount, exhaust gas temperature, and power generation efficiency under condition 15. It is a figure which shows the structure of the combustion system of this embodiment.

First, the inventors will confirm that combustion of biomass liquid fuel and biogas is possible through combustion experiments, which will be described.
<Experiment 1>
In this experiment, a combustion experiment was conducted by using a small diesel generator DA-3506 manufactured by Denyo Co., Ltd. under the following conditions, with the fuel output set to 1 kW, 2 kW, and 3 kW. Moreover, the temperature in the pump which supplies light oil and emulsified fuel at this time was measured.
Condition 1: Light oil exclusive firing Condition 2: Emulsified fuel (biomass liquid fuel) exclusive firing Condition 3: Light oil / biogas (50%) mixed firing Condition 4: Emulsified fuel / biogas (50%) mixed firing

  As the emulsified fuel, an emulsion having a water content of 5% obtained by emulsifying waste cooking oil was used. As the gas, a gas having a chemical composition close to that of biogas, which is a mixture of 60% methane gas and 40% carbon dioxide, is used.

  FIG. 1 is a graph showing the power generation efficiency under conditions 1 to 4. As shown in the figure, it can be seen that even when the co-firing of the emulsified fuel and the biogas is performed, the same power generation efficiency as in the case of the light oil combustion is obtained. It can also be seen that the power generation efficiency is high at high output (2 kW, 3 kW) and low at low output (1 kW).

Also, FIG. 2, the amount of temperature and NO _x fuel emulsified fuel condition 2 in a pump at the time of the single fuel combustion, the amount of CO, and is a graph showing the relationship between the power generation efficiency. As shown in the figure, when the fuel temperature at the pump is 40 ° C., the power generation efficiency is low and the amount of CO generated is large. On the other hand, when the temperature of the fuel at the pump reaches 48 ° C., the power generation efficiency is improved and the CO generation amount is also reduced. This shows that emulsified fuel (biomass liquid fuel) cannot obtain sufficient power generation efficiency at low temperatures.

Further, FIG. 3, the temperature of the fuel in the nozzle inlet when for exclusive combustion of emulsified fuel condition 2, the amount of NO _x, the amount of CO, is a graph showing the relationship between the power generation efficiency. As shown in the figure, when the fuel temperature at the nozzle inlet exceeds 80 ° C., the power generation efficiency decreases, and the amount of NO _X generated increases. From this, it can be said that it is desirable that the temperature of the fuel at the nozzle inlet does not exceed 80 ° C.

<Experiment 2>
Next, the inventors conducted an experiment similar to the experiment 1 for the following conditions 5 to 10 in order to examine the co-firing ratio of the biogas and the output of the generator.
Condition 5: Light oil / biogas (mixed firing rate 30%)
Condition 6: Light oil / biogas (mixed firing rate 50%)
Condition 7: Light oil / biogas (mixed firing rate 70%)
Condition 8: Emulsified fuel / biogas (mixed firing rate 30%)
Condition 9: Emulsified fuel / biogas (mixed firing rate 50%)
Condition 10: Emulsified fuel / biogas (mixed firing rate 70%)

  During the experiment, under the condition 10, when the 3 kW operation was performed, the fuel control became unstable, and the CO concentration exceeded 2000 ppm. For this reason, it turns out that it is desirable for the co-firing rate of biogas to be 50% or less.

  FIG. 4 is a diagram comparing the combustion rates of methane gas when the power generation output is 1 kW, 2 kW, and 3 kW under conditions 5 to 10. As shown in FIG. 4, it can be seen that the combustion rate of methane gas at the time of gas co-firing is high at high output (2 kW, 3 kW) and low at low output (1 kW). For this reason, when performing co-firing with biogas, it turns out that it is desirable to carry out at the time of high output.

<Experiment 3>
Next, in order to examine the fuel injection pressure during co-firing, the following conditions were compared between the case where the fuel injection pressure was a normal pressure and the case where the fuel injection pressure was increased by 10%.
Condition 11: Exclusive firing of emulsified fuel (biomass liquid fuel) Condition 12: Mixed firing of emulsified fuel / biogas (50%)

5 and 6, the amount of the NO _x fuel injection pressure in the case of increased If and 10% was the normal pressure, a graph comparing the amount of generated CO, and results for 5 conditions 11, FIG. 6 is a diagram illustrating a result regarding the condition 12.

As shown in FIG. 5, in the case of mono-fuel combustion of emulsified fuels, by increasing the fuel injection pressure 10%, the amount of the NO _x is increased, the amount of CO is reduced. In addition, as shown in FIG. 6, even when the emulsified fuel and biogas are co-fired, the amount of CO generated is reduced. This shows that it is desirable to increase the fuel injection pressure.

Further, in order to examine the fuel injection timing at the time of co-firing, the fuel injection timing was increased by 3 ° (17 ° before TDC) and 6 ° earlier (20 before TDC) with the fuel injection pressure increased by 10%. generation of °) when the NO _x, generation amount of CO, the power generation efficiency was examined combustion rate.

7, the case of early 3 ° the fuel injection timing, the amount of the NO _x in the case of earlier 6 °, a graph showing a generation amount of CO, 8, the combustion rate of the power generation efficiency and biogas It is a graph to show. As shown in these figures, at the time of co-firing, by increasing the fuel injection timing by 6 °, the NO _x generation amount increases, the CO generation amount decreases, and the power generation efficiency and the biogas combustion rate are improved. You can see that you can. Thereby, it is understood that the combustion timing is advanced by 6 ° (20 ° before TDC).

<Experiment 4>
Further, similarly to the above-described experiment, a long-term combustion / power generation experiment was performed using the small diesel generator DA-3506 manufactured by Denyo Corporation under the conditions described below.
Condition 13: Exclusive combustion of diesel oil Condition 14: Mixed combustion of emulsified fuel (25%) + diesel oil (25%) + gas (50%) Condition 15: Mixed combustion of emulsion fuel (50%) + gas (50%)

Regarding the fuel injection pressure, the fuel injection timing, etc., the standard setting is used for the condition 13, and the optimum adjustment conditions obtained by the experiment 3 (the injection pressure is increased by 10%, the timing advance is 6 °) for the conditions 14 and 15. Set to.
With respect to the above conditions 10 to 12, a combustion experiment was performed until the cumulative operation time reached 100 hours.

9 to 11 are graphs showing the NO _X generation amount, the CO generation amount, the exhaust gas temperature, and the power generation efficiency under the conditions 13 to 15, respectively. As shown in the figure, it can be seen that the operation data does not fluctuate significantly even if the operation is performed for a long time (100 hours). The condition 14 and the condition 15 as compared with the condition 13, although the amount of generated CO is increased, the generation amount of the power generation efficiency and NO _X is substantially equal values were obtained.

Furthermore, after the experiment was completed, the engine was disassembled and inspected. As a result, there was no adhesion of carbon or the like to the nozzle, and no reduction in jetting performance was observed. In addition, no abnormality was found in the piston ring, cylinder, etc.
From the above experiments, it can be said that co-firing of biomass-derived liquid fuel and biogas is possible.

From the above experimental results, the following items were confirmed.
(1) The power generation efficiency similar to the case of light oil mono-combustion can be obtained by co-firing emulsified fuel (biomass liquid fuel) and biogas.
(2) Emulsified fuel (biomass liquid fuel) cannot obtain sufficient power generation efficiency at low temperatures.
(3) It is desirable that the temperature of the fuel at the nozzle inlet does not exceed 80 ° C.
(4) The co-firing rate of biogas is desirably 50% or less.
(5) When co-firing with biogas, it is desirable to perform at high output.
(6) It is desirable to increase the fuel injection pressure and advance the combustion timing.
(7) Co-firing of emulsified fuel (biomass liquid fuel) and biogas for a long time is also possible.

Based on the above results, the inventors propose the following combustion system.
FIG. 12 is a diagram showing a configuration of the combustion system 10 of the present embodiment. As shown in the figure, the combustion system 10 of the present embodiment is for mixing the biogas, the fossil liquid fuel such as petroleum, and the biomass liquid fuel obtained by emulsifying biomass in the combustion engine 20. System.

The combustion engine 20 has a fuel injection pressure higher than that of a normal engine, and the combustion timing is advanced.
The biogas includes methane fermentation or supercritical gas and is stored in the gas tank 11. A gas supply fan 48 and a regulating valve 40 are provided in the supply path 31 connecting the gas tank 11 and the combustion engine 20.

The fossil liquid fuel is stored in the fossil fuel tank 12, and the biomass liquid fuel is stored in the biomass fuel tank 13. The supply passages 32 and 33 connecting the fossil fuel tank 12 and the biomass fuel tank 13 and the combustion engine 20 are provided with regulating valves 41 and 43 and check valves 42 and 44, respectively. Further, these supply paths 32 and 33 merge on the downstream side of the check valves 42 and 44, and a merged supply path 34 where these supply paths 32 and 33 merge is connected to the combustion engine 20. A fuel injection pump 47 for injecting fuel and a governor 46 for controlling the fuel supply amount are provided at the supply port of the merge supply path 34 in the combustion engine 20, and surplus fuel from the fuel injection valve is merged and supplied. A circulation pipe 35 returning to the path 34 is provided. In the merging supply path 34, the fossil liquid fuel and the biomass liquid fuel are mixed. However, since the check valves 42 and 44 are attached to the supply paths 32 and 33, the mixed fuel is supplied to the supply path. Backflow to 32 and 33 is prevented.
The adjusting valves 41 and 43 are electrically connected to the control terminal 50 and can be switched according to the liquid fuel used by the control terminal 50.

  A circulation pump 45 that always operates is provided upstream of the adjustment valve 43 in the supply path connecting the biomass fuel tank 13 and the combustion engine 20, and the circulation pump 45 and the adjustment valve 43 branch from the supply path 33. A circulation pipe 36 connected to the biomass fuel tank 13 is provided. The circulation pipe 36 is provided with a line heater 60, and the line heater 60 heats the fuel flowing through the circulation pipe 36. The line heater 60 can be controlled so that the temperature of the liquid fuel at the nozzle of the combustion engine 20 does not exceed 80 ° C.

  Therefore, even when the regulating valve 43 is closed, the biomass liquid fuel stored in the biomass fuel tank 13 circulates through the circulation pipe 36 by the circulation pump 45 and is heated by the line heater 60 in the process. Become. Thereby, biomass liquid fuel will be heated, stirring by circulation, and it can prevent that fluidity falls.

Hereinafter, a method of driving the combustion engine 20 by the combustion system 10 will be described.
Before the combustion engine 20 is driven, the adjustment valve 43 is closed and the circulation pump 45 is operated. Thereby, as described above, the biomass liquid fuel stored in the biomass fuel tank 13 circulates through the circulation pipe 36 and is heated and agitated by the line heater 60. For this reason, it can prevent that the oil component and water | moisture content which comprise biomass liquid fuel isolate | separate, and can ensure sufficient fluidity | liquidity.

  When starting the combustion system 10, first, the control valve 50 is opened by the control terminal 50, and the combustion engine 20 is driven with the adjustment valve 43 in a closed state. Then, when the preset output is reached, the adjustment valve 40 is opened to supply a predetermined amount of biogas, and the combustion engine 20 is driven while supplying fossil liquid fuel. Thus, the combustion engine 20 can be driven stably by mixing the fossil fuel and the biogas.

  After the combustion system 10 is driven (becomes a high output state), the control valve 50 is closed by the control terminal 50 and the adjustment valve 43 is opened. Thereby, biomass liquid fuel and biogas are supplied to the combustion engine 20, and the combustion engine 20 is driven by co-firing these fuels. At this time, as described above, the biomass liquid fuel circulates through the circulation pipe 36 and is heated by the line heater 60, thereby preventing separation and ensuring fluidity. be able to. The fuel flow rate of the combustion engine 20 at the time of mixed combustion may be controlled by controlling the supply amount of the biomass liquid fuel by the governor 46. The surplus fuel supplied through the merge supply path 34 is returned to the merge supply path 34 through the return pipe 35 again. At the time of co-firing, the control valve 50 is controlled by the control terminal 50 so that the co-firing ratio of biogas does not exceed 50%.

When stopping the combustion engine 20, the control valve 50 closes the regulating valves 40 and 43 and opens the regulating valve 41. As a result, fossil liquid fuel is supplied to the combustion engine 20. Thereby, it is possible to prevent the biomass liquid fuel from remaining and stuck inside the circulation pipe or the like.
After the fossil liquid fuel is supplied in this way, the combustion engine 20 is driven for a predetermined time, and then the regulating valve 41 is closed and the combustion engine 20 is stopped.

After the combustion engine 20 is stopped, the control valve 50 is closed by the control terminal 50 so that the biomass liquid fuel stored in the biomass fuel tank 13 circulates through the circulation pipe 36 and is heated by the line heater 60 and stirred. Is done. Thereby, it can prevent that the oil component and water | moisture content which comprise biomass liquid fuel isolate | separate, it can prevent that fluidity | liquidity falls and can prevent adhering inside piping.
Thus, according to the combustion system 20, the engine can be driven by co-firing biomass liquid fuel and biogas.

  According to the present embodiment, while the biomass liquid fuel is not supplied to the combustion engine, the biomass liquid fuel is circulated through the circulation pipe 36 and heated by the line heater 60, whereby the biomass liquid fuel is stirred and heated. The Thereby, while being able to prevent liquid fuels, such as biomass-derived emulsion, isolate | separating, the fluidity | liquidity of biomass liquid fuel falls and it can prevent adhering to piping etc.

  In the normal combustion system, the surplus fuel is directly returned to the tank, but the surplus fuel supplied from the merging supply path 34 is returned to the downstream side of the check valves 42 and 44 in the merging supply path 34 again. Therefore, the mixed fuel can be prevented from returning to the fossil fuel tank or the biomass fuel tank.

  Further, even when clogging occurs in the biomass fuel tank or the supply passage 33, the fossil liquid fuel and the biogas can be co-fired.

  In addition, although this embodiment demonstrated the case where an emulsion was used as a liquid fuel derived from biomass, not only this but liquid fuels other than an emulsion can also be used.

DESCRIPTION OF SYMBOLS 10 Combustion system 11 Gas tank 12 Fossil fuel tank 13 Biomass fuel tank 20 Combustion engine 31, 32, 33 Supply path 34 Merge supply path 35 Return pipe 36 Circulation pipe 40, 41, 43 Adjustment valve 42, 44 Check valve 45 Circulation pump 46 Governor 50 Control terminal 60 Line heater

Claims (5)

A biomass liquid fuel combustion system,
A biomass liquid fuel tank in which the biomass liquid fuel is stored;
The biomass liquid fuel is supplied from the biomass liquid fuel tank through the biomass liquid fuel supply pipe, and the engine that burns the supplied biomass liquid fuel;
A regulating valve provided in the biomass liquid fuel supply pipe;
Branched from the upstream side of the regulating valve of the biomass liquid fuel supply pipe to reach the biomass liquid fuel tank, and circulates the biomass liquid fuel from the biomass liquid fuel supply pipe to the biomass liquid fuel tank Circulating piping
A line heater provided in the circulation pipe ,
Said line heater, a combustion system of the biomass liquid fuel temperature of the biomass liquid fuel supplied to the engine is characterized that you heat so as not to temperature of 80 ℃ be at 48 ° C. or higher. The combustion system of claim 1,
A biogas tank in which biogas derived from biomass is stored;
A biogas supply pipe for supplying the biogas from the biogas tank to the engine,
The combustion engine for biomass liquid fuel, wherein the engine co-fires the biomass liquid fuel and the biogas. The combustion system according to claim 1 or 2,
A fossil liquid fuel tank storing fossil liquid fuel;
A combustion system comprising: a fossil liquid fuel supply pipe that merges from the fossil liquid fuel tank to the downstream side of the regulating valve of the biomass liquid fuel supply pipe. A combustion system according to claim 3,
Combustion characterized by comprising a return pipe for returning the surplus fuel to the downstream side of the regulating valve of the biomass liquid fuel supply pipe when the fuel supplied from the biomass liquid fuel supply pipe is surplus in the engine system. The combustion system according to any one of claims 1 to 4,
The combustion system, wherein the biomass liquid fuel is an emulsion derived from biomass.

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