JP6209846B2 - Gas engine cogeneration system - Google Patents

Description

  The present invention relates to a gas engine cogeneration apparatus including a gas engine and an exhaust gas boiler that recovers heat of exhaust gas discharged from the gas engine to generate steam.

  Conventionally, a gas engine, an exhaust gas boiler that recovers heat of exhaust gas discharged from the gas engine and generates steam, and a gas engine and an exhaust gas boiler connected to each other, and exhaust gas discharged from the gas engine is supplied to the exhaust gas boiler. A gas engine cogeneration apparatus including an exhaust duct has been proposed. In order to further improve the thermal efficiency of the cogeneration apparatus, a cogeneration apparatus in which a reheating burner for burning fuel gas using exhaust gas as combustion air is disposed in an exhaust duct has been proposed (for example, Patent Document 1). reference).

Japanese Patent Laid-Open No. 8-200474

  In a cogeneration apparatus having a reheating burner as proposed in Patent Document 1, a portion of the exhaust duct located in the vicinity of the reheating burner is caused by the radiant heat of the flame generated by the combustion of the fuel gas by the reheating burner. It becomes easy to damage. Therefore, it is necessary to configure the exhaust duct with a material having excellent heat resistance, which increases the manufacturing cost of the cogeneration apparatus.

  Therefore, an object of the present invention is to provide a cogeneration apparatus in which a reheating burner can be disposed inside an exhaust duct without improving the heat resistance of the exhaust duct.

  The present invention relates to a gas engine, an exhaust gas boiler that recovers heat of exhaust gas discharged from the gas engine to generate steam, an exhaust duct that connects the gas engine and the exhaust gas boiler, and an interior of the exhaust duct A gas engine cogeneration apparatus comprising: a reheating burner that uses exhaust gas flowing through the exhaust duct as combustion air, and a fuel supply device that supplies fuel gas to the reheating burner, wherein the exhaust gas The boiler has an exhaust gas introduction chamber into which exhaust gas is introduced, an exhaust gas introduction port provided at an upper portion of the exhaust gas introduction chamber, and heat recovery from the exhaust gas that is disposed on the side of the exhaust gas introduction chamber and introduced into the exhaust gas introduction chamber. A heat exchanging chamber, wherein the exhaust duct is connected to the exhaust gas inlet and has a vertical duct extending in the vertical direction. The reheating burner ejects fuel gas downward in the vertical direction, and the vertical duct portion is arranged such that the central axis of the reheating burner coincides with the central axis of the vertical duct portion. The present invention relates to a gas engine cogeneration system arranged in

  Moreover, it is preferable that the said vertical duct part is comprised by a cylindrical shape.

  The reheating burner includes a nozzle that ejects fuel gas downward in the vertical direction, and a cone that has a base end connected to the nozzle and a tip that expands toward the downstream side in the exhaust gas flow direction. It is preferable to include a trapezoidal inner cylinder part, a plurality of through holes formed in the peripheral surface of the inner cylinder part, and a cylindrical outer cylinder part arranged outside the inner cylinder part.

  The gas engine cogeneration apparatus includes a control unit that controls the fuel supply apparatus so that the amount of fuel gas supplied to the reheating burner is 4% or less of the amount of exhaust gas discharged from the gas engine. It is preferable to further provide.

  According to the gas engine cogeneration apparatus of the present invention, the reheating burner can be disposed inside the exhaust duct without improving the heat resistance of the exhaust duct.

It is a figure which shows the structure of the gas engine cogeneration apparatus which concerns on 1st Embodiment of this invention. It is an enlarged view which shows the structure of the reheating burner of the gas engine cogeneration apparatus of 1st Embodiment. It is the figure which looked at the reheating burner in the arrow A direction of FIG. It is a figure which shows the structure of the gas engine cogeneration apparatus which concerns on 2nd Embodiment of this invention.

Hereinafter, preferred embodiments of a gas engine cogeneration apparatus (hereinafter also referred to as a cogeneration apparatus) of the present invention will be described with reference to the drawings.
First, the whole structure of the cogeneration apparatus 1 of 1st Embodiment is demonstrated, referring FIGS. 1-3.

  The cogeneration apparatus 1 according to the first embodiment includes a gas engine 10, an exhaust gas boiler 20, an exhaust duct 30 that connects the gas engine 10 and the exhaust gas boiler 20, and a reheating disposed inside the exhaust duct 30. A burner 40, a fuel supply device 50 that supplies fuel gas to the reheating burner 40, and a control unit 60 that controls operations of these devices are provided.

  The gas engine 10 is driven by burning fuel gas to generate electric power. From this gas engine 10, combustion gas generated by burning fuel gas is discharged as exhaust gas.

The exhaust gas boiler 20 recovers the heat of the exhaust gas discharged from the gas engine 10 and generates steam. The exhaust gas boiler 20 includes an exhaust gas introduction chamber 21, a heat exchange chamber 22, and an exhaust gas discharge chamber 23.
In the present embodiment, the outer shape of the exhaust gas boiler 20 is mainly composed of a box-shaped housing, and the exhaust gas introduction chamber 21, the heat exchange chamber 22, and the exhaust gas discharge chamber 23 are arranged side by side in the horizontal direction (horizontal direction). The
The exhaust gas discharged from the gas engine 10 is introduced into the exhaust gas introduction chamber 21. More specifically, an exhaust gas inlet 211 into which exhaust gas is introduced is formed in the upper part of the exhaust gas introduction chamber 21, and the exhaust gas is introduced downward from the exhaust gas inlet 211.

  The heat exchange chamber 22 is disposed on the side (downstream side) of the exhaust gas introduction chamber 21. The heat exchange chamber 22 includes a steam generation unit 222 in which a plurality of water pipes 221 are disposed, and a feed water preheating unit 224 that is located downstream of the steam generation unit 222 and in which a feed water heating pipe 223 is disposed. In the steam generation unit 222, heat is exchanged between the heat of the exhaust gas introduced from the exhaust gas introduction chamber 21 and the water supplied into the plurality of water pipes 221 to generate steam. In the feed water preheating unit 224, heat exchange is performed between the exhaust gas subjected to heat exchange in the steam generation unit 222 and the feed water flowing through the feed water heating pipe 223, and the feed water supplied to the plurality of water pipes 221 is preheated. Is done.

  The exhaust gas outlet chamber 23 is disposed on the downstream side of the heat exchange chamber 22. The exhaust gas discharged from the heat exchange chamber 22 is introduced into the exhaust gas outlet chamber 23. The exhaust gas introduced into the exhaust gas discharge chamber 23 is discharged from the exhaust gas discharge port 231 formed on the upper surface of the exhaust gas discharge chamber 23 to the exhaust pipe 24 connected to the exhaust gas discharge port 231 and then discharged to the outside. .

  The exhaust duct 30 has a proximal end connected to an exhaust port (not shown) of the gas engine 10 and a distal end connected to an exhaust gas inlet 211 of the exhaust gas boiler 20. The exhaust duct 30 supplies the exhaust gas discharged from the gas engine 10 to the exhaust gas boiler 20. In the present embodiment, the exhaust duct 30 is configured in a cylindrical shape. And the exhaust duct 30 is arrange | positioned in the connection part with the exhaust gas inlet 211, and has the vertical cylinder part 31 as a vertical duct part extended in a perpendicular direction.

  As shown in FIGS. 1 to 3, the reheating burner 40 is disposed in the vertical cylindrical portion 31 in the exhaust duct 30. More specifically, the reheating burner 40 is disposed in the lower portion (near the exhaust gas boiler 20) in the vertical cylindrical portion 31. The reheating burner 40 burns fuel gas using the exhaust gas flowing through the exhaust duct 30 as combustion air, and raises the temperature of the exhaust gas introduced into the exhaust gas boiler 20. The reheating burner 40 includes a nozzle 41, a flame holding cylinder 42 as an inner cylinder part, an air register 43 as an outer cylinder part, and a pilot burner 44.

  The nozzle 41 is formed in a thin cylindrical shape, and is arranged with the tip portion facing downward. From the nozzle 41, fuel gas is ejected downward in the vertical direction, which is the flow direction of exhaust gas in the exhaust duct 30 (vertical cylinder portion 31).

  The flame-holding cylinder 42 is formed in a truncated cone shape that gradually increases in diameter from the proximal end portion toward the distal end portion and is open at the proximal end portion and the distal end portion. The flame holding cylinder 42 is connected to the tip end of the nozzle 41 at the base end. As a result, the flame-holding cylinder 42 expands in diameter toward the lower side, which is the downstream side in the exhaust gas flow direction. A plurality of through holes 421 are formed on the peripheral surface of the flame holding cylinder 42. The size (diameter) of the plurality of through holes 421 is formed so as to gradually increase from the proximal end side to the distal end side of the flame-holding cylinder 42.

  The air register 43 is formed in a cylindrical shape with both ends opened, and is disposed outside the flame holding cylinder 42. More specifically, the inner diameter D <b> 1 of the air register 43 is configured to be slightly larger than the outer diameter D <b> 2 of the tip portion of the flame holding cylinder 42. As a result, a gap is formed between the outer peripheral surface of the flame holding cylinder 42 and the inner peripheral surface of the air register 43. Further, the length L1 of the air register 43 is configured to be longer than the length L2 of the flame holder 42. And the position of the front-end | tip part (lower end part) of the air register 43 is arrange | positioned in the position lower than the position of the front-end | tip part (lower end part) of the flame-holding cylinder 42. FIG.

  The gap formed between the outer peripheral surface of the flame holding cylinder 42 and the inner peripheral surface of the air register 43 is the air register 43 from the viewpoint of suitably maintaining the combustion state (flame holding property) of the fuel gas in the reheating burner 40. It is preferable that it is a magnitude | size of the grade which 8-12% of the waste gas introduce | transduced into the inside passes.

  Further, the distance L3 between the front end portion (lower end portion) of the air register 43 and the front end portion (lower end portion) of the flame holding cylinder 42 is suitable for the combustion state (flame holding property) of the fuel gas in the reheating burner 40. From the standpoint of maintaining the air resistance, it is preferably 30% to 100% of the outer diameter D3 of the air register 43.

  Further, the outer diameter D3 of the air register 43 is 30% to 50% of the inner diameter D4 of the exhaust duct 30 (vertical cylinder portion 31) from the viewpoint of suitably maintaining the combustion state (flame holding property) of the fuel gas in the reheating burner 40. % Is preferred.

  In the reheating burner 40 described above, the central axes of the nozzle 41, the flame holding cylinder 42, and the air register 43 are arranged at positions that coincide with the central axis of the vertical cylinder portion 31 (see FIG. 3).

  Thus, by positioning the central axes of the nozzle 41, the flame holding cylinder 42 and the air register 43 at a position substantially coincident with the central axis of the vertical cylinder portion 31, the reheating burner 40 is removed from the wall surface of the exhaust duct 30. It can be arranged at a spaced position. Further, since the flame generated in the reheating burner 40 is formed downward in the vertical direction along the direction of gravity, it is possible to prevent the flame from coming into contact with the vertical cylinder portion 31, and the outside of the air register 43 and the exhaust duct 30. A layer through which exhaust gas that has not been reheated by the reheating burner 40 circulates can be formed. Therefore, since the temperature rise of the exhaust duct 30 (vertical cylinder part 31) by arranging the reheating burner 40 can be reduced, it is not necessary to give special heat insulation or the like to the exhaust duct 30.

  The air register 43 and the nozzle 41 are fixed by a stay 45 (see FIG. 2). The stays 45 are provided, for example, at three places at 120 degree intervals or at four places at 90 degree intervals. The air register 43 is also fixed to the vertical cylinder portion 31 by a stay (not shown).

  The pilot burner 44 supplies a seed fire when the reheating burner 40 is ignited. The pilot burner 44 is inserted so as to penetrate the exhaust duct 30 (vertical cylinder portion 31), the air register 43, and the flame holding cylinder. The tip of the pilot burner 44 is located at a position that substantially matches the inner peripheral surface of the flame-holding cylinder 42.

  In addition, a flame detection means is provided in the exhaust duct 30 (vertical cylinder part 31) in the position where the reheating burner 40 is disposed. The flame detection means electrically detects the presence or absence of flame in the reheating burner 40.

The fuel supply device 50 includes a fuel gas supply line 51 that supplies fuel gas to a reheating burner 40 (nozzle 41) from a fuel gas supply source (not shown), and a flow rate adjustment valve provided in the fuel gas supply line 51. 52.
As the fuel gas, natural gas (city gas), propane gas, digestion gas, or the like is used.
The flow rate adjustment valve 52 is constituted by, for example, a motor valve, and adjusts the flow rate of the fuel gas supplied to the reheating burner 40.

The control unit 60 controls the amount of fuel gas supplied to the reheating burner 40 so that the system efficiency of the cogeneration apparatus 1 can be improved according to the characteristics of the exhaust gas discharged from the gas engine 10.
That is, the exhaust gas discharged from the gas engine 10 has a lower temperature and oxygen concentration than the exhaust gas discharged from the gas turbine, and pulsates. Therefore, in the case where only the exhaust gas discharged from the gas engine 10 is used as combustion air and the fuel gas is burned by the reheating burner 40, the fuel gas generated by the reheating burner is used more than when only the exhaust gas from the gas turbine is used as the combustion air. It is difficult to maintain a good combustion state. That is, when only the exhaust gas discharged from the gas engine 10 is used as combustion air, an inert gas such as carbon dioxide contained in the exhaust gas becomes a disturbance and it becomes difficult to combine the fuel gas and oxygen. For this reason, unless the fuel supply amount is much lower than the oxygen concentration ratio in the exhaust gas of the gas engine 10 and the oxygen concentration ratio in the atmosphere, the flame is not stable and it is difficult to maintain a good combustion state.

  In addition, when the amount of fuel gas supplied to the reheating burner 40 is excessively increased, the temperature of the exhaust gas introduced into the exhaust gas boiler 20 is greatly increased, and the heat insulation mechanism of the exhaust duct 30 and the exhaust gas introduction chamber 21 is provided. It becomes necessary to strengthen, and the production of the cogeneration system 1 becomes complicated, and the production cost of the cogeneration system 1 increases.

  Therefore, in the present embodiment, the control unit 60 controls the fuel supply device 50 so that the amount of fuel gas supplied to the reheating burner 40 is 4% or less of the amount of exhaust gas discharged from the gas engine 10. To do. Accordingly, even when the exhaust gas of the gas engine 10 having a lower temperature and lower oxygen concentration than the exhaust gas of the gas turbine is used as combustion air, the reheating burner 40 can efficiently burn it. Thereby, since the temperature of the exhaust gas supplied to the exhaust gas boiler 20 can be reliably increased, the system efficiency of the gas engine cogeneration apparatus 1 can be effectively improved. In addition, by making the amount of fuel gas supplied to the reheating burner 40 as small as 4% or less of the amount of exhaust gas, the influence on the reheating burner 40 when the exhaust gas pulsates can be reduced, and stable combustion can be achieved. It can be carried out.

  Moreover, it is preferable that the control part 60 controls the quantity of the fuel gas supplied to the reheating burner 40 from the fuel supply apparatus 50 so that the temperature at the inlet of the exhaust gas boiler 20 does not exceed 500 ° C. Thereby, it is possible to prevent the exhaust gas temperature from excessively rising after the reheating. Therefore, since the efficiency of the exhaust gas boiler 20 can be improved without performing special heat insulation processing on the exhaust duct 30 and the exhaust gas introduction chamber 21, the cost for manufacturing (or remodeling) the cogeneration apparatus 1 can be reduced.

  The more preferable amount of fuel gas supplied to the burner burner 40 varies depending on the type of fuel gas. For example, when city gas (for example, 13A gas) is used as fuel gas, the control unit 60 determines that the amount of fuel gas supplied to the reheating burner 40 is the amount of exhaust gas discharged from the gas engine 10. It is preferably controlled to be 2% or less, more preferably controlled to be 1% or less, and still more preferably controlled to be 0.3% or less.

Next, operation | movement of the cogeneration apparatus 1 of 1st Embodiment is demonstrated.
In the cogeneration apparatus 1, first, fuel gas and combustion air are supplied to the gas engine 10, the fuel gas is burned, and power generation is performed. Combustion gas generated by burning fuel gas in the gas engine 10 is discharged to the exhaust duct 30 as exhaust gas.
The exhaust gas discharged to the exhaust duct 30 flows downward through the vertical cylinder portion 31 toward the exhaust gas boiler 20.

A reheating burner 40 is disposed in the vertical cylinder portion 31, and the exhaust gas is reheated by the reheating burner 40.
More specifically, a part of the exhaust gas flowing through the exhaust duct 30 (vertical cylinder portion 31) is first introduced inside the air register 43. And most (about 90%) of the exhaust gas introduced inside the air register 43 is introduced into the flame holding cylinder 42 through the plurality of through holes 421. Inside the flame-holding cylinder 42, the fuel gas is ejected from the nozzle 41, and the seed fire is supplied by the pilot burner 44. The fuel gas ejected from the nozzle 41 burns with the exhaust gas supplied into the flame holding cylinder 42 through the plurality of through holes 421 as combustion air. A part of the exhaust gas introduced into the air register 43 flows downward through a gap formed between the air register 43 and the flame holding cylinder 42.

  Thus, in the present embodiment, the amount of exhaust gas that is fuel air is increased as the exhaust gas gradually goes downstream of the flame-holding cylinder 42 while limiting the amount of exhaust gas used for combustion of the fuel gas. Thus, the flame holding property of the reheating burner 40 using the exhaust gas of the gas engine 10 as combustion air is improved.

  That is, when the exhaust gas of the gas engine 10 having a low oxygen concentration and a low temperature is used as combustion air, if a large amount of exhaust gas is brought into contact with the fuel gas in the vicinity of the nozzle 41, a part of the fuel gas ejected from the nozzle 41 Although it burns, since the concentration of oxygen contained in the exhaust gas is low, the cooling of the flame with a large amount of low temperature exhaust gas has an advantage over the combustion by contact with oxygen and fuel gas, and the temperature at which it burns stably do not become.

  Therefore, the air register 43 is arranged to limit the amount of exhaust gas used for combustion of the fuel gas by the reheating burner 40, and the exhaust gas introduced into the air register 43 is passed through the plurality of through holes 421. The gas was gradually supplied to the inside of the frustoconical flame holding cylinder 42. In this way, the amount of exhaust gas as combustion air is supplied so as to gradually increase toward the downstream side of the flame-holding cylinder 42, thereby suppressing the cooling of the combustion flame and reducing the inside of the flame-holding cylinder 42. Thus, high-temperature combustion can be stably maintained.

  In the present embodiment, the reheating burner 40 is disposed near the exhaust gas boiler 20 in the vertical cylinder portion 31. Thereby, since the radiant heat of the flame which generate | occur | produced in the reheating burner 40 is transmitted to the exhaust gas boiler 20, the thermal efficiency of the exhaust gas boiler 20 can be improved further.

  The more preferable amount of fuel gas supplied to the burner burner 40 varies depending on the type of fuel gas. For example, when city gas (for example, 13A gas) is used as the fuel gas, the amount of fuel gas supplied to the reheating burner 40 is 2% or less of the amount of exhaust gas discharged from the gas engine 10. It is preferable to make it 1% or less, more preferably 0.3% or less.

  The exhaust gas that has been reheated by the reheating burner 40 and has risen in temperature flows downward and is introduced into the exhaust gas introduction chamber 21 from the exhaust gas inlet 211. Exhaust gas that has been reheated in the reheating burner 40 and whose temperature has risen (mainly exhaust gas that circulates in the center of the exhaust duct 30) and the outside of the air register 43, and is not reheated by the reheating burner 40. The exhaust gas (mainly the exhaust gas flowing outside the exhaust duct 30) is changed in the direction of flow from the exhaust gas introduction chamber 21 in a substantially horizontal direction and mixed in the process of flowing into the heat exchange chamber 22 to average the temperature. . Thereby, heat exchange is suitably performed in the heat exchange chamber 22.

  In the heat exchange chamber 22, the exhaust gas whose temperature has decreased due to heat exchange with the plurality of water pipes 221 and the feed water heating pipe 223 is introduced into the exhaust gas outlet chamber 23, and then passes through the exhaust gas outlet port 231 and the exhaust pipe 24 to the outside. Discharged.

Next, a second embodiment of the gas engine cogeneration apparatus of the present invention will be described with reference to FIG.
The cogeneration apparatus 1A of the second embodiment is different from the first embodiment in that it further includes a bypass duct 70 that connects the exhaust duct 30 and the exhaust cylinder 24, and a damper 80.

The upstream end of the bypass duct 70 is connected to the upstream side of the exhaust duct 30 from the position where the reheating burner 40 is disposed.
The damper 80 closes the upstream end of the bypass duct 70 to close the exhaust duct 30 by closing the exhaust duct 30 by closing the exhaust duct 30 to the exhaust gas boiler 20 side. The second state leading to the side can be changed.

According to the cogeneration apparatus 1A of the second embodiment, in addition to the same effects as those of the first embodiment, the following effects can be obtained.
The cogeneration apparatus 1 </ b> A includes a bypass duct 70 and a damper 80. Thereby, when the generation | occurrence | production of the vapor | steam by the exhaust gas boiler 20 is unnecessary, it can discharge | emit outside without introducing waste gas into the exhaust gas boiler 20 by making the damper 80 into a 2nd state. Therefore, the cogeneration apparatus 1A can be operated more flexibly according to the required load in the load facility where the cogeneration apparatus 1A supplies electricity and steam.

As mentioned above, although each preferred embodiment of the gas engine cogeneration device of the present invention was described, the present invention is not limited to the above-mentioned embodiment, and can be changed suitably.
For example, in the above-described embodiment, the exhaust gas introduction chamber 21, the heat exchange chamber 22, and the exhaust gas discharge chamber 23 are arranged side by side in the horizontal direction, but this is not a limitation. That is, the exhaust gas outlet chamber may be arranged along the vertical direction, and a part of the heat exchange chamber (feed water preheating part) and the exhaust gas outlet chamber may be arranged along the vertical direction.

DESCRIPTION OF SYMBOLS 1,1A Gas engine cogeneration apparatus 10 Gas engine 20 Exhaust gas boiler 21 Exhaust gas introduction chamber 22 Heat exchange chamber 30 Exhaust duct 31 Vertical cylinder part (vertical duct part)
40 Reheating burner 41 Nozzle 42 Flame holding cylinder (inner cylinder)
43 Air register (outer cylinder)
DESCRIPTION OF SYMBOLS 50 Fuel supply apparatus 60 Control part 211 Exhaust gas inlet 421 Through-hole

Claims (3)

A gas engine,
An exhaust gas boiler that generates steam by recovering heat of exhaust gas having a low temperature and oxygen concentration compared to the exhaust gas discharged from the gas turbine ;
An exhaust duct having no wind box, connected to the gas engine and the exhaust gas boiler, provided in an exhaust gas inlet of the exhaust gas boiler and configured in a cylindrical shape for circulating the exhaust gas from above to below ;
A reheating burner that is disposed inside the exhaust duct and uses only exhaust gas flowing through the exhaust duct as combustion air;
A fuel supply device for supplying fuel gas to the burner,
A control unit for controlling the fuel supply device so that the amount of fuel gas supplied to the reheating burner is 4% or less of the amount of exhaust gas discharged from the gas engine;
A gas engine cogeneration system comprising:
The exhaust gas boiler is
An exhaust gas introduction chamber into which exhaust gas is introduced;
An exhaust gas inlet provided in an upper portion of the exhaust gas introduction chamber;
A heat exchange chamber that is disposed on the side of the exhaust gas introduction chamber and performs heat recovery from the exhaust gas introduced into the exhaust gas introduction chamber,
The exhaust duct includes a vertical duct portion having a lower end connected to the exhaust gas inlet and extending in a vertical direction,
The reheating burner is disposed in the vertical duct portion so that fuel gas is ejected downward in the vertical direction, and the central axis of the reheating burner coincides with the central axis of the vertical duct portion , A gas engine cogeneration apparatus that forms a layer through which exhaust gas that has not been reheated by the reheating burner circulates in the vicinity of the wall surface of the exhaust duct .   The gas engine cogeneration apparatus according to claim 1, wherein the vertical duct portion is configured in a cylindrical shape. The scoring burner is
A nozzle that ejects fuel gas downward in the vertical direction;
A base end portion connected to the nozzle and a tip end portion of the inner cylinder portion having a truncated cone shape whose diameter increases toward the downstream side in the flow direction of the exhaust gas;
A plurality of through-holes formed in the peripheral surface of the inner cylinder part;
The gas engine cogeneration apparatus according to claim 1, further comprising: a cylindrical outer tube portion disposed outside the inner tube portion.

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