JPH10141601A - Exhaust gas re-burning type combined cycle facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the reverse flow of the exhaust gas to a bypass flue of a induced draft fan. SOLUTION: A gas turbine 32 and a boiler 35 are connected to each other through a turbine side air passage, a flue 41 provided with an induced draft fan 42 and a induced draft fan bypass flue 43 provided with an induced draft fan bypass damper 44 are connected in parallel between an exhaust gas outlet 39 of the boiler 35 and a stock 40, the induced draft fan 42 is controlled by the fan drive command 65 from a control part 66. A switching relay 56 to output the high gain value 53 to be generated by a signal generator 52 when the induced draft fan bypass damper 44 is closed, and to output the low gain value 55 to be generated by a signal generator 54 in other cases than the case when the induced draft fan bypass damper 44 is closed, is provided on the control part 66.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation type combined cycle facility. More specifically, the present invention relates to an exhaust gas recirculation type combined cycle facility that can minimize the backflow of exhaust gas to an induced draft fan bypass flue when driving an induced draft fan.

[0002]

2. Description of the Related Art Exhaust gas recirculation type combined cycle equipment for obtaining high thermal efficiency by utilizing the exhaust gas of a gas turbine as combustion air for a boiler has been studied.

[0003] As shown in FIG. 2, an exhaust-refueling combined cycle facility currently under study connects an exhaust port 3 of a gas turbine 2 connected to a generator 1 to a boiler 5 through a turbine-side wind path 4. It is connected to the combustion air inlet 6.

[0004] In the middle of the turbine side air path 4, a ventilator side air path 8 provided with a forced air ventilator 7 is connected.

[0005] An induction ventilator 12 is provided in a flue 11 connecting the exhaust gas outlet 9 of the boiler 5 and the chimney 10, and an induction ventilator bypass flue 13 is provided between the entrance and exit of the induction ventilator 12 of the flue 11.
Are connected to each other, and an induction ventilator bypass damper 14 is provided in the induction ventilator bypass flue 13.

Further, a pressure detector 15 is attached to the exhaust gas outlet 9 of the boiler 5, and a pressure detection signal 1 from the pressure detector 15 is provided.
6 is provided with a subtractor 19 for taking a deviation from the reference pressure 18 set in the setting device 17, and a multiplier 23 for multiplying a differential pressure 20 from the subtractor 19 by a gain 22 generated by the signal generator 21 is provided. A proportional integral controller 25 for performing proportional integral control based on the control gain 24 output from the ventilator 23. The ventilator driving force correction signal 26 generated by the proportional integral controller 25 is supplied to the ventilator reference drive set in the setter 27. An adder 29 for adding the force 28 is provided so that the driving force of the induced draft fan 12 can be controlled and adjusted based on the draft drive command 30 generated by the adder 29.

According to this configuration, first, when the boiler 5 is operated independently, the push-in ventilator 7 is driven to send air for combustion to the boiler 5 through the ventilator-side air passage 8, and the combustion air is supplied to the boiler 5. The fuel is burned by the air, and the boiler 5 is started.

The exhaust gas generated by combustion in the boiler 5 is
The induction ventilator 12 is stopped, and the induction ventilator bypass damper 1 is stopped.
By fully opening 4, the air is discharged from the chimney 10 via the induced draft fan bypass damper 14.

When the gas turbine 2 is operated while the boiler 5 is in operation, the exhaust gas of the gas turbine 2 is sent to the boiler 5 via the turbine-side wind path 4, and the exhaust gas of the gas turbine 2 is supplied to the boiler 5. By being burned, high thermal efficiency can be obtained.

Here, when the gas turbine 2 is operated,
If the pressure on the exhaust side is high, the gas turbine 2 cannot exhaust, so it is necessary to reduce the pressure on the exhaust side.

Therefore, the induction ventilator bypass damper 14
And the intake ventilator 12 is driven to forcibly exhaust air from the flue 11.

At this time, the pressure at the exhaust gas outlet 9 of the boiler 5 is detected by the pressure detector 15 attached to the exhaust gas outlet 9 of the boiler 5, and the pressure detection signal 16 from the pressure detector 15 and the setting of the setting device 17 are set. Subtractor 19 subtracts the deviation from reference pressure 18
, A differential pressure 20 is obtained, a multiplier 23 multiplies the differential pressure 20 from the subtractor 19 by a gain 22 generated by the signal generator 21 to obtain a control gain 24, and a proportional-integral controller 25 calculates
Proportional integration control is performed based on the control gain 24 output from the multiplier 23 to output a ventilation drive force correction signal 26, and the adder 29 converts the ventilation drive force correction signal 26 generated by the proportional integration controller 25 into: By adding the ventilator reference driving force 28 set in the setter 27, based on the ventilator driving command 30 generated by the adder 29, the driving force of the induction ventilator 12 is changed according to the pressure of the exhaust gas outlet 9 of the boiler 5. Adjust it.

[0013]

However, the exhaust refueling combined cycle facility under study has the following problems.

That is, when the gas turbine 2 is operated,
When the induction ventilator 12 is driven with the induction ventilator bypass damper 14 opened, the exhaust in the flue 11 flows back to the induction ventilator bypass flue 13 side, reducing the exhaust efficiency, and reducing the pressure in the boiler 5. May be unstable.

The present invention has been made in view of the above-mentioned circumstances, and provides an exhaust gas reburning combined cycle facility capable of minimizing the backflow of exhaust gas to the induction ventilator bypass flue when driving the induction ventilator. The purpose is to do so.

[0016]

According to the present invention, a gas turbine 32 and a boiler 35 are connected by a turbine side air passage 34, and a gas exhaust port 39 of the boiler 35 and a
The flue 41 provided with the induced ventilator 42 and the induced ventilator bypass flue 43 provided with the induced ventilator bypass damper 44 are connected in parallel, and the induced ventilator 42 operates the ventilator drive command 65 from the control unit 66. And outputs a high gain value 53 generated by the signal generator 52 to the control unit 66 when the induction ventilator bypass damper 44 is closed, and outputs a signal when the induction ventilator bypass damper 44 is not closed. Switching relay 5 for outputting low gain value 55 generated by generator 54
6 relating to an exhaust gas refueling type combined cycle facility.

According to the above means, the following effects can be obtained.

First, when the boiler 35 is operated alone, the exhaust gas generated by the combustion in the boiler 35 stops the induction ventilator 42 and fully opens the induction ventilator bypass damper 44, thereby causing the induction ventilator bypass. The fuel is discharged from the chimney 40 via the damper 44.

Then, with the boiler 35 operated,
When the gas turbine 32 is operated, exhaust gas from the gas turbine 32 is sent to a boiler 35 via a turbine-side wind path 34,
Since the exhaust gas of the gas turbine 32 is burned in the boiler 35, high thermal efficiency can be obtained.

Here, when the gas turbine 32 is operated, if the pressure on the exhaust side is high, the gas turbine 32 cannot be exhausted. Therefore, it is necessary to reduce the pressure on the exhaust side.

Therefore, the induction ventilator bypass damper 44
And the control unit 66 drives the induction ventilator 42 to forcibly exhaust air from the flue 41.

At this time, the high ventilation value 53 is used when the induction ventilator bypass damper 44 is closed, and the low gain value 55 is used when the induction ventilator bypass damper 44 is not closed. When the mechanical bypass damper 44 is closed, the driving force of the induction ventilator 42 is increased.
Since the driving force of the induction ventilator 42 can be switched in accordance with the open / close state of the induction ventilator bypass damper 44 such that the driving force of Step 2 is weakened, even if the induction ventilator bypass damper 44 is opened, In addition, the exhaust gas in the flue 41 flows back to the side of the induction ventilator bypass flue 43 to reduce the exhaust efficiency and prevent the pressure in the boiler 35 from becoming unstable.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

Gas turbine 32 connected to generator 31
Is connected to a combustion air inlet 36 of a boiler 35 via a turbine side wind path 34.

Then, in the middle of the turbine side air path 34, a ventilator side air path 38 provided with a forced air vent 37 is connected.

The exhaust gas outlet 39 of the boiler 35 and the chimney 4
In the flue 41 connecting to the flue 41, an induction ventilator 42 is provided.
An induction ventilator bypass flue 43 is connected between the entrance and exit sides of the induction ventilator 42, and an induction ventilator bypass damper 44 is provided in the induction ventilator bypass flue 43.

Further, a pressure detector 45 is attached to an exhaust gas outlet 39 of the boiler 35, and a subtractor 49 for obtaining a deviation between a pressure detection signal 46 from the pressure detector 45 and a reference pressure 48 set in a setting unit 47 is provided. .

When the induction fan bypass damper 44 is closed, a signal generator 52 is provided based on the opening signal 51 from the damper driving device 50 of the induction fan bypass damper 44 and the like.
Is generated, and the signal generator is generated when the induction ventilator bypass damper 44 is not closed (the same applies when fully opened or intermediately opened, or when it is not fully opened or fully closed). There is provided a switching relay 56 for outputting a low gain value 55 generated by 54.

Further, a multiplier 58 for multiplying the differential pressure 57 from the subtractor 49 by one of the high gain value 53 and the low gain value 55 output from the switching relay 56 is provided, and a control gain 59 output from the multiplier 58 is provided. A proportional integral controller 60 for performing a proportional integral control based on the fan drive force correction signal 61 generated by the proportional integral controller 60; and an adder 64 for adding the ventilator reference drive force 63 set in the setter 62. The control unit 66 controls the driving force of the induction ventilator 42 based on the ventilator driving command 65 generated by the adder 64.
Is configured.

Next, the operation will be described.

First, when the boiler 35 is operated independently, the push-in ventilator 37 is driven to send combustion air to the boiler 35 through the ventilator-side air passage 38, and the fuel is burned by the combustion air. Then, the boiler 35 is started.

The exhaust gas generated by the combustion in the boiler 35 is discharged from the chimney 40 via the induced ventilator bypass damper 44 by stopping the induced ventilator 42 and fully opening the induced ventilator bypass damper 44.

Then, with the boiler 35 operated,
When the gas turbine 32 is operated, exhaust gas from the gas turbine 32 is sent to a boiler 35 via a turbine-side wind path 34,
Since the exhaust gas of the gas turbine 32 is burned in the boiler 35, high thermal efficiency can be obtained.

Here, when the gas turbine 32 is operated, if the pressure on the exhaust side is high, the gas turbine 32 cannot be exhausted, so it is necessary to reduce the pressure on the exhaust side.

Therefore, the induction ventilator bypass damper 44
Is throttled or closed, and the induction ventilator 42 is driven to forcibly exhaust air from the flue 41.

At this time, the pressure detector 45 attached to the exhaust gas outlet 39 of the boiler 35 detects the exhaust gas outlet 39 of the boiler 35.
Is detected, and a pressure detection signal 4 from the pressure detector 45 is detected.
The difference between 6 and the reference pressure 48 set in the setting device 47 is calculated by a subtractor 49 to obtain a differential pressure 57.

Then, based on the opening degree signal 51 from the damper driving device 50 of the induction ventilator bypass damper 44, and the like,
The switching relay 56 outputs a high gain value 53 generated by the signal generator 52 when the induction ventilator bypass damper 44 is closed, and when the induction ventilator bypass damper 44 is not closed (when the induction ventilator bypass damper 44 is fully open or at an intermediate opening, Alternatively, the same applies to a case other than the fully open or fully closed state). The low gain value 55 generated by the signal generator 54 is output.

Then, the multiplier 58 multiplies the differential pressure 57 from the subtractor 49 by one of the high gain value 53 and the low gain value 55 output from the switching relay 56 to obtain the control gain 59, and obtains the control integral 59. At 60, a proportional-integral control is performed based on the control gain 59 output from the multiplier 58 to output a ventilator driving force correction signal 61, and an adder 64 generates a ventilator driving force correction signal generated by the proportional-integral controller 60. 61, setting device 6
The drive force of the induction ventilator 42 is adjusted according to the pressure of the exhaust gas outlet 39 of the boiler 35 based on the ventilator drive command 65 generated by the adder 64 by adding the ventilator reference drive force 63 set to 2. To do.

As described above, the induction ventilator bypass damper 4
4 is closed when the high gain value 53 is used, and when the induction ventilator bypass damper 44 is not closed (when fully open or at the intermediate opening,
Alternatively, the same applies to a case other than the fully open or fully closed state), so that the low gain value 55 is used, so that when the induced ventilator bypass damper 44 is closed, the induced ventilator 42 is used.
When the induction ventilator bypass damper 44 is not closed, the driving force of the induction ventilator 42 is reduced, and the driving force of the induction ventilator 42 is reduced according to the open / close state of the induction ventilator bypass damper 44. Since the power can be switched, even if the induction ventilator bypass damper 44 is squeezed, the exhaust air in the flue 41 is not exhausted by the induction ventilator bypass flue 4.
The gas flows back to the third side to reduce the exhaust efficiency and prevent the pressure in the boiler 35 from becoming unstable.

It should be noted that the present invention is not limited only to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0042]

As described above, according to the exhaust refueling type combined cycle equipment of the present invention, the induction ventilator 42
When the air is driven, the exhaust ventilator bypass flue 43
There is an excellent effect that the backflow to the air can be minimized.

[Brief description of the drawings]

FIG. 1 is an overall schematic system diagram of an example of an embodiment of the present invention.

FIG. 2 is an overall schematic system diagram of an exhaust gas reburning combined cycle facility currently under study.

[Explanation of symbols]

 32 Gas Turbine 34 Turbine Side Wind Path 35 Boiler 39 Exhaust Gas Exit 40 Chimney 41 Chimney 42 Induction Ventilator 43 Induction Ventilator Bypass Flue 44 Induction Ventilator Bypass Damper 52 Signal Generator 53 High Gain Value 54 Signal Generator 55 Low Gain Value 56 Switching relay 65 Ventilator drive command 66 Control unit

Claims (1)

[Claims] 1. A gas turbine (32) and a boiler (35).
Are connected by a turbine side wind path (34), and between a flue gas outlet (39) of a boiler (35) and a chimney (40), a flue (41) provided with an induction ventilator (42), and an induction draft An induction ventilator bypass flue (43) provided with a ventilator bypass damper (44) is connected in parallel with the induction ventilator (4).
2) is controlled by a ventilator drive command (65) from a control unit (66), and the control unit (66) includes a signal generator (52) when the induction ventilator bypass damper (44) is closed. And a switching relay (56) for outputting a low gain value (55) generated by the signal generator (54) when the induction ventilator bypass damper (44) is not closed. Exhaust reburn type combined cycle equipment that is equipped with.