JP2003227349A - Biomass gasification generating set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve energy efficiency of biomass. <P>SOLUTION: This generating set comprises a thermal decomposition furnace 13 for thermal decomposing biomass; gas turbine generators 7, 9 driven by the combustion gas generated by performing burning by air discharged from a compressor 1 with thermal decomposed gas generated in the thermal decomposition furnace 13 as main fuel; and vapor turbine generators 23, 25 driven by vapor generated by burning char generated in the thermal decomposition furnace 13 with a boiler 17. Exhaust gas of the gas turbine 9 is utilized for a heat source 15 of the thermal decomposition furnace 13, and the exhaust gas after used as the heat source is used as air for burning in the boiler 17. Therefore, it is possible to save energy for heating the air for combustion to a combustion temperature of the boiler 17, resulting in improvement of energy efficiency of biomass. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biomass gasification power generation device that pyrolyzes biomass and generates electricity by the pyrolysis products.

[0002]

2. Description of the Related Art As a biomass gasification power generation device, there is known a device for thermally decomposing organic biomass such as wood-based materials, food residues, livestock manure, etc., and using the pyrolysis gas obtained thereby as fuel. In such a biomass gasification power generation device, conventionally, a method of using exhaust gas from a gas turbine that uses, for example, city gas as a fuel, has been proposed as a heat source for thermal decomposition. Further, a method is known in which exhaust gas after being used as a heat source for pyrolysis is guided to a waste heat boiler to recover the amount of heat.

[0003]

However, the conventional biomass gasification power generator has a point to be improved in energy efficiency as a whole.

Therefore, an object of the present invention is to improve the energy efficiency of biomass gasification power generation.

[0005]

In order to solve the above-mentioned problems, a biomass gasification power generator of the present invention uses a pyrolysis furnace for pyrolyzing biomass and a pyrolysis gas produced in the pyrolysis furnace as a main fuel. As a result, the gas discharged from the compressor is combusted, and the gas turbine generator driven by the generated combustion gas and the char generated in the pyrolysis furnace are combusted in the boiler.
With a steam turbine generator driven by the generated steam,
The exhaust gas of the gas turbine generator is used as the heat source of the pyrolysis furnace, and the exhaust gas after being used as the heat source is used as combustion air for the boiler.

That is, the present invention pays attention to the fact that the exhaust gas of a gas turbine after being used as a heat source for pyrolysis has a relatively high oxygen concentration and a high temperature (for example, 600 to 800 ° C.). The exhaust gas is used as combustion air for burning char in the boiler. This makes it possible to save energy for heating the combustion air to a temperature equal to or higher than the preheating air temperature of the boiler, as compared with the conventional preheating method in which the combustion air is preheated to about 250 ° C. with the exhaust gas of the boiler. Energy efficiency is improved.

When the pyrolysis gas generated in the pyrolysis furnace is left over, it can be used as fuel for the boiler.
Needless to say, when the amount of oxygen required by the boiler is insufficient, air is separately supplied. On the other hand, it is known that the ratio of pyrolysis gas generated by pyrolysis to char changes depending on the pyrolysis temperature. Therefore, the pyrolysis temperature is controlled and adjusted according to the required amount of pyrolysis gas and the amount of char.

The pyrolysis temperature at which biomass is pyrolyzed is usually 600 to 800 ° C. On the other hand, since the exhaust gas discharged from the gas turbine has a temperature of about 500 ° C., it is not possible to raise the temperature to the thermal decomposition temperature only by the heat quantity of the exhaust gas. Therefore, an additional heating burner for heating the exhaust gas supplied to the pyrolysis furnace is provided to compensate for the lack of heat of the exhaust gas.
In this case, it is preferable that the reburning burner uses the pyrolysis gas as a fuel and the exhaust gas as a pyrolysis temperature. This makes it possible to save energy by using the exhaust gas of the pyrolysis furnace as combustion air for the boiler.

Further, it is preferable to provide a regenerator for heating the air discharged from the compressor by the exhaust gas of the gas turbine. As a result, the amount of oxygen consumed for combustion is reduced, and the oxygen concentration of the exhaust gas supplied to the boiler can be increased.

By the way, the composition of the pyrolysis gas obtained by pyrolyzing the biomass, and the ratio of the pyrolysis gas and the char are determined by the type of biomass, the temperature in the pyrolysis furnace, and the time during which the biomass stays in the furnace. It is known to depend on Therefore, the biomass in the pyrolysis furnace is sent forward,
Further, it is preferable to provide a progressive feeding device capable of varying the progressive feeding speed, and change the feeding speed of the biomass according to the type of biomass.

Further, it is preferable to adjust the temperature in the pyrolysis furnace by adjusting the additional heating burner.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a biomass gasification power generator to which the present invention is applied will be described below with reference to FIG. FIG. 1 is a diagram showing a configuration of an embodiment of a biomass gasification power generation device to which the present invention is applied.

As shown in FIG. 1, the gas passage 2 on the discharge side of the compressor 1 for compressing air is connected to a combustor 5 via a regenerator 3.
It is connected to the. Pyrolysis gas is supplied to the combustor 5, and the combustion gas is combusted to drive the gas turbine 9, for example, 1000 ° C.
It is designed to generate combustion gases. Also,
The combustor 5 can also supply fuel (not shown) such as city gas. The discharge side of the combustor 5 is connected to the suction side of the gas turbine 9 that drives the generator 7. The rotating shaft of the gas turbine 9 is connected to the rotating shaft of the compressor 1, and when the gas turbine 9 is driven, the compressor 1 is also driven.

Gas passage 10 on the discharge side of gas turbine 9
Is connected to the additional heating burner 11 via the regenerator 3. The regenerator 3 is formed so as to exchange heat between the air flowing through the gas passage 2 and the exhaust gas discharged from the gas turbine 9. The additional combustion burner 11 is configured to be supplied with pyrolysis gas, and is configured to burn the pyrolysis gas using exhaust gas as combustion air. The discharge side of the additional heating burner 11 is connected to the input side of the heat exchanger 15. The heat exchanger 15 is provided in the pyrolysis furnace 13 and configured to exchange heat between the biomass and the exhaust gas, and the outlet side of the heat exchanger 15 is connected to the combustion chamber of the boiler 17.

Char is supplied to the combustion chamber of the boiler 17, and heat generated by burning the char heats the water flowing through the heat transfer tube 21 to generate steam. Has been formed. The exhaust gas generated by this combustion passes through a dust collector (not shown) or the like to the chimney 1.
9 is released into the atmosphere. The heat transfer tube 21 is connected to the suction side of the steam turbine 25 that drives the generator 23, and is formed to drive the steam turbine 25. The discharge side of the steam turbine 25 is connected to the heat transfer pipe 21 via a condenser (not shown) or the like, and returns steam to water for circulation.

The pyrolysis furnace 13 is a slightly inclined drum type furnace (for example, kiln type), and the drum is provided with a heat exchanger 15 for exchanging heat between the biomass inside and the exhaust gas. By rotating this drum, the biomass introduced into the furnace is sent to the sorting device 27. The rotation speed of the drum can be adjusted by a control device (not shown). The separation device 27 is configured to separate the pyrolysis gas and the char by a known separation method such as a comb. The conveying path 28 to which the char separated by the separating device 27 is guided is connected to the combustion chamber of the boiler 17. On the other hand, the gas flow path 30 through which the pyrolysis gas separated by the separation device 27 is guided is connected to the boiler 17
Connected to the suction side of a gas compressor 33 that compresses the pyrolysis gas via a boiler feedwater heater 29 that heat-exchanges the water and the pyrolysis gas that are supplied to the Has been done. The discharge side of the gas compressor 33 is branched and connected to the combustor 5 and the additional burner 11 to supply the pyrolysis gas as fuel.

Next, the operation of the biomass gasification power generator having such a configuration will be described. During the operation of the biomass gasification power generator, the air compressed by the compressor 1 that compresses air flows through the regenerator 3 and is guided to the combustor 5,
The fuel such as city gas or pyrolysis gas that is supplied to is burned. The combustion gas of, for example, 1000 ° C. discharged from the combustor 5 is guided to the gas turbine 9 that drives the generator 7, is driven after driving the gas turbine 9, and is then discharged. For example, the oxygen concentration discharged from the gas turbine 9 is 15 to 18
%, The exhaust gas having a temperature of 500 to 550 ° C. is introduced into the regenerator 3 and exchanges heat with the air flowing through the regenerator 3 to preheat the air. As a result, the amount of oxygen consumed for burning the pyrolysis gas or the like can be reduced, and the oxygen concentration of the exhaust gas sent to the downstream can be increased by, for example, 3%.

The exhaust gas, which has been cooled to 350 to 400 ° C. by exchanging heat with the air, is introduced into the additional heating burner 11 as combustion air and burns the pyrolysis gas to, for example, 600 to 800 ° C. The temperature is raised to the pyrolysis temperature. In this way, by using the exhaust gas as the combustion air, it is possible to save energy for heating the combustion air to the pyrolysis temperature as compared with the case of using room temperature air as the combustion air. Energy efficiency can be improved.

Combustion in the additional burner 11 reduces the oxygen concentration of the exhaust gas to, for example, 13%. Then, the exhaust gas discharged from the additional heating burner 11 is guided to the heat exchanger 15 that exchanges heat between the biomass in the thermal decomposition furnace 13 and the exhaust gas. The exhaust gas that has exchanged heat with the biomass in the heat exchanger 15 and has been cooled down is introduced into the combustion chamber of the boiler 17 and burns the char supplied to the boiler 17. Further, the exhaust gas generated by burning the char is discharged from the chimney 19 to the atmosphere via a dust collector (not shown) or the like.

Here, the water flowing through the heat transfer tube 21 of the boiler 17 is heated by the combustion of char to become steam,
It is guided to the steam turbine 25 that drives the generator 23, and drives the steam turbine 25. And the steam turbine 2
The steam discharged from 5 is returned to the water via a condenser (not shown) or the like, and is then guided to the boiler 17 again. The biomass introduced into the thermal decomposition furnace 13 is thermally decomposed by exchanging heat with the exhaust gas through the heat exchanger 15, and the biomass is transferred inside the thermal decomposition furnace 13 to separate the thermal decomposition gas and char. It is sent to the sorting device 27.

The char separated by the separating device 27 is introduced into the combustion chamber of the boiler 17 and mixed with the exhaust gas supplied as combustion air to be combusted. As a result, the energy for heating the combustion air to the preheated combustion air temperature of the boiler 17 can be saved, so that the energy efficiency of the biomass can be improved.

By the combustion in the boiler 17, the heat transfer tube 2
The water flowing in 1 is heated to steam or superheated steam. On the other hand, the pyrolysis gas separated by the separation device 27 is the boiler 1
The tar removal device 3 which is guided to the boiler feed water heater 29 for exchanging heat between the water supplied to 7 and the pyrolysis gas, preheats the water by exchanging heat with the water, and then removes the tar component of the pyrolysis gas 3
Guided to 1. The pyrolysis gas purified by the tar removal device 31 is compressed by the gas compressor 33 that compresses the pyrolysis gas, and then branched and supplied to the combustion chamber 5 and the additional heating burner 11.

As described above, according to the present embodiment, the exhaust gas after being used as a heat source is supplied as combustion air to the combustion chamber of the boiler 17, so that the energy for heating the combustion air to the combustion temperature of the boiler 17 is supplied. Since it can be saved, the energy efficiency of biomass can be improved. Further, in the reburning burner 11, the pyrolysis gas is burned by using the exhaust gas of the gas turbine 9 as the combustion air, and the pyrolysis gas is burned to heat the exhaust gas, whereby the combustion air is heated to the pyrolysis temperature. Since energy can be saved, the energy efficiency of biomass can be improved.

Further, by providing the regenerator 3, the air discharged from the compressor 1 and the exhaust gas discharged from the gas turbine 9 can be heat-exchanged. As a result, the air supplied to the combustor 5 can be preheated, the amount of oxygen consumed for burning the pyrolysis gas and the like can be reduced, and the oxygen concentration of the exhaust gas sent to the downstream can be increased. . As a result, the upper limit of the combustion temperature in the additional combustion burner 11 and the boiler 17 can be increased, that is, the combustion temperature range can be widened. Further, by varying the progressive feeding speed of the biomass in the pyrolysis furnace 13, it is possible to perform an operation according to the type of biomass and the desired composition of the pyrolysis gas. In this case, it is preferable that the additional heating burner and the regenerator are adjustable. Furthermore, the char generated by thermal decomposition can be burned in the combustion chamber of the boiler 17 and used for power generation.

Further, in the present embodiment, the pyrolysis gas is guided to the combustor 5, but instead of this, the pyrolysis gas is supplied to the combustion chamber of the boiler 17 as shown in FIG. Can be Thereby, for example, when the pyrolysis temperature is low and the amount of char produced is small, the pyrolysis gas can be supplied to the boiler as an auxiliary fuel.
In addition, because the pyrolysis gas can be used as fuel for the boiler, it is possible to abolish the water purification and purification processing equipment such as filters that were required when using the pyrolysis gas for gas turbines, reducing equipment costs. can do.

By the way, in the present embodiment, the additional burner 1
Although the exhaust gas heated in 1 flows through the heat exchanger 15 of the thermal decomposition furnace 13, instead of this, the additional heating burner and the thermal decomposition furnace may be integrally formed. Figure 3
It is sectional drawing which showed the modification of the thermal decomposition furnace of the biomass gasification power generation apparatus to which this invention is applied.

A modification of the thermal decomposition furnace of this embodiment will be described below. That is, the thermal decomposition furnace 40 shown in FIG. 3 includes a hot air generating furnace 42 through which the exhaust gas discharged from the gas turbine 9 flows, and biomass and exhaust gas which are disposed in the hot air generating furnace 42 and are sequentially fed inside. A cylindrical body 44 for heat exchange is integrally formed. A plurality of cylinders 44 are arranged in the vertical direction, and the ends of the cylinders 44 that are adjacent to each other in the vertical direction are alternately connected to each other to form one meandering forward passage 46. Biomass is supplied to the uppermost tubular body 44 from, for example, a supply device 43 including a crusher, and the lowermost tubular body 44 burns char to burn the boiler 17. For example, it is connected to a conveyance path 28 such as a screw conveyor that conveys to the chamber. Further, the cylindrical body 44 includes a screw feeder 48 therein, and the screw feeder 48 is configured to be rotated by a variable speed drive motor 49. The rotation speed of the drive motor 49 can be adjusted according to the water content of the biomass, for example. Gas pipes 50 are connected to the upper portions of the cylinders 44, respectively, and are formed so as to guide a part of the pyrolysis gas to the hot air generating furnace 42 as fuel for heating.

The hot air generating furnace 42 is formed so as to mix the exhaust gas introduced from the gas turbine 9 and the pyrolysis gas supplied through the gas pipe 50 and burn the mixture, and is heated by this combustion. The exhaust gas is configured to flow through the exhaust gas passage 52. The exhaust gas passage 52 is formed so as to include the progressive passage 46 and along the progressive passage 46, and the exhaust gas flowing inside is adapted to exchange heat with the biomass through the tubular body 44. There is. Then, the exhaust gas is discharged into the atmosphere or is guided to the hot air generating furnace 42 again.

It is preferable that the hot air generating furnace 42 has the progressive passage 46 included therein because the temperature distribution in the progressive passage 46 can be made uniform. Further, in the present embodiment, the rotation speed of the screw feeder 48 is controlled according to the moisture content of the biomass, but the rotation speed is not limited to this, and the rotation speed is adjusted so as to adjust the residence time according to the type and composition of the biomass. Can be controlled.

[0030]

According to the present invention, the energy efficiency of biomass can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a biomass gasification power generation device to which the present invention is applied.

FIG. 2 is a diagram showing a configuration of a modified example of the biomass gasification power generation device to which the present invention is applied.

FIG. 3 is a cross-sectional view showing a modified example of the pyrolysis furnace of the biomass gasification power generation device to which the present invention is applied.

[Explanation of symbols]

1 compressor 7 generator 9 gas turbine 13 Pyrolysis furnace 17 Boiler 23 generator 25 steam turbine

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) F02C 6/00 F02C 6/00 Z 6/18 6/18 Z 7/22 7/22 D F23G 5/027 ZAB F23G 5/027 ZABZ H02P 9/04 H02P 9/04 P F term (reference) 3G081 BA02 BA11 BB00 BC07 BD00 DA14 DA22 3K061 AB02 AC11 AC17 BA04 FA23 5H590 AA02 CA01 CA08 FA01

Claims (4)

[Claims] 1. A pyrolysis furnace for pyrolyzing biomass, and a gas turbine driven by the combustion gas generated by burning the pyrolysis gas produced in the pyrolysis furnace as the main fuel with air discharged from a compressor. A steam turbine generator that drives a steam generated by burning a char and a char generated in the pyrolysis furnace in a boiler is provided, and the exhaust gas of the gas turbine generator is used as a heat source of the pyrolysis furnace. At the same time, a biomass gasification power generator that uses the exhaust gas after being used as a heat source as combustion air for the boiler. 2. A pyrolysis furnace that pyrolyzes biomass, a gas turbine generator that burns fuel with air discharged from a compressor, and drives with generated combustion gas, and heat generated in the pyrolysis furnace. Combustion of decomposed gas and char in a boiler, and a steam turbine generator driven by the generated steam, and using the exhaust gas of the gas turbine generator as a heat source of the thermal decomposition furnace, after using as a heat source A biomass gasification power generator that uses exhaust gas as combustion air for the boiler. 3. A reburning burner for burning the exhaust gas of the gas turbine generator by using the exhaust gas of the gas turbine generator as combustion air to heat the exhaust gas of the gas turbine generator. Alternatively, the biomass gasification power generator according to 2. 4. A progressive feeding device for feeding the biomass to a discharge side in the pyrolysis furnace, the progressive feeding device changing a feeding speed in accordance with a type of the biomass and a desired composition of the pyrolysis gas. The biomass gasification power generation device according to any one of claims 1 to 3, characterized in that.