JP3602167B2 - Operation control device for power plant - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a power plant (hereinafter, referred to as a BTG plant) equipped with a steam generating facility and a steam turbine, particularly combining an additionally installed steam turbine with good controllability and a steam generator with high fuel efficiency but poor controllability. The present invention relates to an operation control device for a BTG plant.
[0002]
[Prior art]
Recently, in this type of BTG plant, more and more steam generating equipment and turbine equipment have been added in order to respond to an increase in demand for electric power and steam used as the production volume of the factory increases.
[0003]
FIG. 5 is a configuration diagram illustrating an example of a BTG plant.
In FIG. 5, reference numeral 1 denotes an existing oil boiler (OB), and steam generated from the oil boiler 1 is supplied to a low-pressure side steam header (LH) 2. Reference numeral 3 denotes an existing low-pressure steam turbine (ST1) that rotates by the steam pressure flowing from the low-pressure side steam header 2 through the governor 4 to drive the generator 5, and is extracted from the low-pressure steam turbine 3. The steam is supplied to a load gas supply header (DH) 7 via a bleed control valve 6, and the steam exhausted from the low-pressure steam turbine 3 is condensed by a condenser 8.
[0004]
On the other hand, reference numeral 9 denotes a newly installed coal boiler (CB), and steam generated from the coal boiler 9 is supplied to a high-pressure side steam header (HH) 10. Reference numeral 11 denotes a newly installed high-pressure steam turbine (ST2) that rotates by the steam pressure flowing from the high-pressure side steam header 10 through the governor 12 to drive the generator 13, and is extracted from the high-pressure steam turbine 11. The steam is sent to a load air supply header (DH) 7 via a bleed control valve 14, and the steam exhausted from the high-pressure steam turbine 11 is condensed by a condenser 15.
[0005]
The high-pressure side steam header 10 and the low-pressure side steam header 2 are connected via a pressure reducing valve (RPV) 16, and the load air supply header 7 discharges excess steam that cannot be consumed by the factory load to the outside. The discharge valve (EXV) 17 is connected.
[0006]
By the way, in such a BTG plant, there are devices such as coal boilers that have high fuel efficiency but do not have good controllability. However, generally speaking, new equipment is a state-of-the-art equipment with high temperature, high pressure and large capacity, whereas existing equipment is often low temperature, low pressure and small dose equipment, and the controllability is generally higher for new equipment. Is good.
[0007]
Therefore, in a BTG plant that has been expanded, new equipment is often used to absorb steam load fluctuations because it is easier to control and the equipment capacity is large and the adjustment range is large. .
[0008]
Conventionally, the operation control device of the above-mentioned BTG plant operates an existing device and a newly installed device in a control configuration as shown in FIG.
In FIG. 6, reference numeral 18 denotes a bleed controller which detects the steam pressure of the load gas supply header 7 by the pressure detector 19 and controls the bleed control valve 6 of the existing low-pressure steam turbine 3. The bleed controller controls the bleed control valve 14 of the newly installed high-pressure steam turbine 11 by detecting the steam pressure by the pressure detector 21.
[0009]
Reference numeral 22 denotes a high pressure steam generation amount controller which detects the steam pressure of the high pressure side steam header 10 by a pressure detector 23 to adjust the fuel of the coal boiler 9 and controls the amount of generated steam, and 24 denotes a low pressure side steam header. 2 is a steam header controller that detects the steam pressure by the pressure detector 25 to control the pressure reducing valve 16 to control the amount of steam flowing from the high-pressure steam header 10 to the low-pressure steam header 2. This is a steam release control device that controls the steam release valve 17 by detecting the steam pressure of 10 with a pressure detector 27.
[0010]
Further, reference numeral 28 denotes a power generation controller which detects the power generation of the generator 5 driven by the existing low-pressure steam turbine 3 and controls the governor 4, and 29 denotes the power generation of the generator 13 driven by the newly installed steam turbine 11. This is a power generation amount controller that controls the governor 12 by detecting the amount.
[0011]
Next, a control operation by such a control configuration will be described with reference to FIG.
When the factory load increases, the steam pressure of the load air supply header 7 decreases, and when the factory load decreases, the steam pressure of the load air supply header 7 increases. 3. The extraction pressure control of the high-pressure steam turbine 11 operates.
[0012]
Now, a case in which the load fluctuation is absorbed on the newly-installed turbine (ST2) having good controllability will be described. As shown in FIG. 7, the load header pressure detection unit A detects the steam pressure of the load air supply header 7 and performs the bleed control. When the bleed control valve 14 is controlled in the part B, the bleed amount of the high-pressure steam turbine 11 changes. Then, the power generation controller C controls the governor 12 to keep the output of the generator 13 constant, and the amount of main steam flowing from the high-pressure steam header 10 into the high-pressure steam turbine 11 changes. Changes the vapor pressure.
[0013]
At this time, the high pressure steam generation amount control unit D detects the steam pressure of the high pressure side steam header 10, adjusts the fuel of the coal boiler 9, and controls the generated steam amount.
Further, the steam pressure of the high-pressure side steam header 10 is checked by the high-pressure header pressure check unit E, and the steam discharge control unit F opens the steam release valve 17 only when the steam header pressure becomes abnormally high.
[0014]
Further, the pressure reducing valve 16 is controlled so that the steam pressure of the low-pressure side steam header 2 becomes constant.
Here, assuming that the steam load of the factory is reduced as shown in FIG. 8, the steam extraction amounts of the high-pressure steam turbine ST2 and the low-pressure steam turbine ST1 change over time as shown in FIG. That is, the steam extraction amount of the high-pressure steam turbine ST2 changes according to the decrease in the steam load of the factory, but the steam extraction amount of the low-pressure steam turbine ST1 changes in a substantially constant state.
[0015]
Further, at this time, when the amount of extracted air in the high-pressure steam turbine ST2 decreases, the governor is narrowed down by the power generation amount constant control, so that the steam pressure of the high-pressure side steam header 10 increases. Therefore, the fuel of the newly installed coal boiler 9 is adjusted, and the amount of generated steam is controlled to be reduced.
[0016]
At this time, the amount of steam generated from the coal boiler 9 and the oil boiler 1 changes as shown in FIG. That is, although the amount of steam generated from the coal boiler 9 changes depending on the fuel adjustment, the amount of steam generated from the oil boiler 1 is constant, and the total amount of generated steam is as shown in FIG.
[0017]
[Problems to be solved by the invention]
However, such a conventional operation control device for a BTG plant has the following problems.
(1) When the steam load at the factory decreases, we would like to operate a newly installed high-pressure steam turbine with high fuel efficiency at a high load factor and an existing low-pressure steam turbine with low fuel efficiency at a low load factor. As shown in FIG. 11, since the amount of steam generated from the coal boiler 9 having good fuel efficiency is reduced, the load ratio is low.
[0018]
Also, regarding the amount of bleed air from the steam turbine, it is originally desired to reduce the amount of bleed air from the turbine with low fuel efficiency. However, as can be seen from FIG. 9, the amount of bleed air from the newly installed high-pressure steam turbine with good fuel efficiency is reduced, and the efficiency of fuel efficiency is reduced. The extraction amount of the bad low-pressure steam turbine is constant.
[0019]
For these reasons, there is a problem that the operation efficiency of the entire plant is reduced.
(2) Since the newly installed coal boiler 9 having poor controllability cannot follow a sudden change in the steam load of the factory, the boiler or turbine trips due to an abnormal rise in the steam pressure of the high-pressure steam header 10, and the plant operates. It becomes difficult to continue.
[0020]
Therefore, in order to avoid such a situation, the steam release valve 17 is controlled to release steam to the atmosphere, or the amount of steam exhausted from the turbine is increased and returned to water by a condenser. Is continued until the amount of steam generated by the boiler matches the load, and the energy loss due to the steam emission during that time is as shown by the hatched portion in FIG. 11, and it is impossible to operate with high fuel efficiency.
[0021]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an operation control device for a power plant that can improve the operation efficiency and fuel efficiency of the entire plant.
[0022]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a low-pressure side steam header to which steam generated from a low-pressure steam generator having good controllability is supplied and a high-pressure steam to which steam generated from a high-pressure steam generator having low fuel efficiency is supplied. A low-pressure steam turbine that communicates between the side steam headers via a pressure reducing valve and drives a generator by the steam pressure flowing from the low-pressure side steam header, and generates electricity by the steam pressure flowing from the high-pressure side steam header A high-pressure steam turbine that drives the steam generator, and supplies the steam extracted from the low-pressure steam turbine and the high-pressure steam turbine via a bleed-amount control valve to a load air supply head that supplies the steam to a steam load. A pressure reducing valve control means for controlling the pressure reducing valve such that when the steam pressure of the high pressure side steam header changes, the steam pressure becomes constant; A low-pressure steam generation amount control means for controlling the low-pressure steam generation device so that the steam pressure of the low-pressure side steam header changes when the low-pressure side steam header changes; Extraction control means for controlling the steam pressure of the low-pressure steam turbine to be constant, and distribution for controlling the extraction pressure control valve of the low-pressure steam turbine according to the distribution ratio of the extraction pressure of the low-pressure steam turbine and the extraction pressure of the high-pressure steam turbine. Control means.
[0023]
[Action]
In the operation control device of the power plant having such a configuration, when the steam pressure of the high-pressure steam header changes, the opening of the pressure reducing valve is controlled to keep the steam pressure of the high-pressure steam header constant, The steam pressure of the low-pressure side steam header is kept constant by controlling the amount of steam generated by the low-pressure steam generator with respect to the change of the steam pressure of the side steam header. The degree of opening of the bleed amount control valve of the turbine is controlled so that the vapor pressure of the load air supply header is kept within a certain range, and the degree of opening of the bleed amount control valve of the low-pressure steam turbine is gradually increased according to the bleed amount distribution ratio. The amount of bleed air is controlled so as to change, and the opening of the bleed air amount control valve of the high-pressure steam turbine is controlled in accordance with the change.
[0024]
Therefore, the pressure fluctuation of the load air supply header due to the change of the steam load is quickly absorbed by controlling the extraction amount of the high-pressure steam turbine with good controllability, and the pressure fluctuation of the high-pressure side steam header with good controllability. The pressure fluctuation of the low pressure side steam header is performed by the pressure reducing valve, and the pressure fluctuation of the low pressure side steam header is performed by the low pressure side steam generator with good controllability. By gradually changing the steam pressure of the steam header while keeping it constant, it is possible to recover the amount of bleed air from the high-pressure steam turbine and return the steam to the high-pressure steam generator with high fuel efficiency.
[0025]
【Example】
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of the configuration of an operation control device for a BTG plant according to the present invention, and the same parts as those in FIG.
[0026]
In FIG. 1, reference numeral 20 denotes a newly installed high-pressure steam turbine 11 which detects a steam pressure of the load air supply header 7 which changes due to a change in the steam load of the factory by a pressure detector 21 so that the load header steam pressure is kept constant. This is a bleed controller that controls the opening of the bleed control valve 14 on the side.
[0027]
The pressure detector 31 detects the steam pressure of the high-pressure steam header 10 that changes according to the main steam amount that changes in accordance with the change in the amount of extracted air of the high-pressure steam turbine 11, and detects the steam pressure of the high-pressure steam header 10. The pressure reducing valve controller 32 controls the opening of the pressure reducing valve 16 so as to be kept constant. The pressure detecting device 25 detects the steam pressure of the low pressure side steam header 2 changed by the control of the pressure reducing valve 16 by the pressure detector 25, This is a low-pressure steam generation amount controller that controls the fuel of the oil boiler 1 so that the steam pressure of the steam header 2 is kept constant and controls the amount of generated steam.
[0028]
Further, a distribution control 30 detects the steam pressure of the load air supply header 7 by the pressure detector 19 and controls the extraction amount of the low-pressure steam turbine 3 based on the distribution ratio between the low-pressure steam turbine extraction amount and the high-pressure steam turbine extraction amount. It is a vessel.
[0029]
On the other hand, reference numeral 26 denotes a steam pressure control device that detects the steam pressure of the low pressure side steam header 2 by the pressure detector 33 and controls the opening of the steam pressure relief valve 17 when the pressure becomes equal to or higher than a predetermined value.
[0030]
Further, reference numeral 28 denotes a power generation controller which detects the power generation of the generator 5 driven by the existing low-pressure steam turbine 3 and controls the governor 4, and 29 denotes the power generation of the generator 13 driven by the newly installed steam turbine 11. This is a power generation amount controller that controls the governor 12 by detecting the amount.
[0031]
Next, the operation of the operation control device of the BTG plant configured as described above will be described with reference to FIG.
Now, in FIG. 2, when the steam load of the factory decreases, the load header pressure detecting section A detects the steam pressure of the load air supply header 7, and the bleed control section B on the high pressure steam turbine 11 opens the bleed control valve 14. The degree is controlled to decrease, and the amount of bleed air from the high-pressure steam turbine 11 decreases. The amount of bleed air at this time is detected by the high-pressure steam turbine bleed air amount detection unit G, and the distribution control unit H controls the low-pressure steam turbine 3 based on the distribution ratio between the bleed air amount of the high-pressure steam turbine 11 and the low-pressure steam turbine 3. The amount of extracted air is controlled.
[0032]
The power generation control unit C controls the governor 12 to keep the output of the generator 13 constant, and the amount of main steam flowing into the high-pressure steam turbine 11 from the high-pressure steam header 10 decreases. Vapor pressure rises. When the steam pressure of the high-pressure steam header 10 is detected by the pressure detector, the opening of the pressure-reducing valve 16 is controlled by the pressure-reducing valve control unit I so that the opening degree of the pressure-reducing valve 16 increases. Steam flows to the low-pressure steam header 2 so as to be constant.
[0033]
Then, the steam pressure of the low-pressure side steam header 2 increases, and when the steam pressure is detected by the pressure detector, the fuel of the oil boiler 1 is adjusted by the low-pressure steam generation amount control unit J to control the steam generation amount. .
[0034]
At this time, the steam pressure of the low-pressure side steam header 2 is monitored by the low-pressure header pressure check unit K. When the steam pressure exceeds a predetermined value, the steam discharge pressure control unit L opens the steam discharge valve 17 to load the load gas supply header 7. Part of the steam is released to the outside.
[0035]
Here, assuming that the steam load of the factory is reduced as shown in FIG. 8, the steam extraction amounts of the high-pressure steam turbine ST2 and the low-pressure steam turbine ST1 change over time as shown in FIG. That is, the steam extraction amount of the high-pressure steam turbine ST2 increases to the maximum value within a operable range immediately after absorbing the steam load fluctuation of the factory, and the steam extraction amount of the low-pressure steam turbine ST1 with low fuel efficiency is operable. It can be seen that it decreases to the minimum value within a certain range.
[0036]
At this time, the amount of steam generated from the coal boiler 9 and the oil boiler 1 is as shown in FIG. That is, the amount of steam generated from the newly installed coal boiler 9 is controlled to be substantially constant because the amount of steam extracted from the high-pressure steam turbine ST2 temporarily returns to its original state after being temporarily reduced. Since the amount of generated steam is controlled by the fuel adjustment with good load following ability, it follows the load fluctuation in a short time, and a small amount of energy loss is required as shown by the hatched portion in the figure.
[0037]
As described above, in the present embodiment, the absorption of the pressure fluctuation of the load air supply header 7 due to the change of the steam load is promptly performed by controlling the extraction amount of the high-pressure steam turbine 11 having good controllability. Pressure fluctuation is performed by the pressure control valve 16 having good controllability, and the pressure fluctuation of the low-pressure side steam header 2 is performed by the oil boiler 1 having good controllability. Is gradually changed while keeping the vapor pressure of the load air supply header 7 constant, to recover the amount of bleed air from the high-pressure steam turbine 11 and return to the fuel-efficient coal boiler 9 side.
[0038]
Accordingly, it is possible to contribute to the recovery of the deviation of the extraction amount distribution from the efficient operation point caused by the fluctuation of the steam load and to reduce the unnecessary steam release amount, so that the operation with high fuel efficiency can be performed.
[0039]
【The invention's effect】
As described above, according to the present invention, it is possible to improve the operation efficiency and fuel efficiency of the entire plant, and to provide an operation control device for a power plant.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing one embodiment of an operation control device of a BTG plant according to the present invention.
FIG. 2 is a functional block diagram for explaining the operation of the embodiment.
FIG. 3 is a curve diagram showing changes in the amount of steam extracted by the high-pressure steam turbine and the low-pressure steam turbine in the embodiment.
FIG. 4 is a curve diagram showing a change in the amount of steam generated from a coal boiler and an oil boiler in the embodiment.
FIG. 5 is a configuration diagram showing an example of an entire BTG plant.
FIG. 6 is a configuration diagram showing a conventional operation control device for a BTG plant.
FIG. 7 is a functional block diagram for explaining the operation of the operation control device.
FIG. 8 is a curve diagram showing a steam load fluctuation state of a factory.
FIG. 9 is a curve diagram showing changes in the amount of steam extracted from the high-pressure steam turbine and the low-pressure steam turbine by the operation control device.
FIG. 10 is a diagram showing the total amount of steam generated from the coal boiler and the oil boiler by the operation control device.
FIG. 11 is a curve diagram showing a change in the amount of steam generated from a coal boiler and an oil boiler by the operation control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Oil boiler, 2 ... Low pressure side steam head, 3 ... Low pressure steam turbine, 4, 12 ... Governor, 5, 13 ... Generator, 6, 14 ... Bleed control valve, 7 ... Load transmission Gas header, 8, 15 condenser, 9 coal boiler, 10 high pressure side steam head, 11 high pressure steam turbine, 16 pressure reducing valve, 17 steam discharge valve, 19, 21, 23, 25, 33 ... pressure detector, 20 ... bleeding controller, 26 ... steam release control device, 28, 29 ... power generation amount controller, 30 ... distribution controller, 31 ... pressure reducing valve controller , 32 ... Low-pressure steam generation amount controller.

Claims (1)

Via a pressure-reducing valve, a connection is made between a low-pressure steam header supplied with steam generated from a low-pressure steam generator with good controllability and a high-pressure steam header supplied with steam generated from a high-pressure steam generator with low fuel efficiency. Operating a low-pressure steam turbine that drives a generator with the steam pressure flowing from the low-pressure steam header, and drives a high-pressure steam turbine that drives the generator with the steam pressure flowing from the high-pressure steam header, In a power plant configured to supply the steam extracted from the low-pressure steam turbine and the high-pressure steam turbine via a bleed-amount control valve to a load air supply header that supplies a steam load,
Pressure reducing valve control means for controlling the pressure reducing valve so that the steam pressure of the high pressure side steam header changes when the steam pressure of the high pressure side steam header changes, and the steam pressure becomes constant when the steam pressure of the low pressure side steam header changes A low-pressure steam generation amount control means for controlling the low-pressure steam generation device, and a bleed control means for controlling a bleed amount control valve of the high-pressure steam turbine so that the steam pressure of the low-pressure side steam header becomes constant. An operation control device for a power plant, comprising: a distribution control unit that controls a bleed amount control valve of a low-pressure steam turbine according to a ration ratio between the bleed amount of the low-pressure steam turbine and the bleed amount of the high-pressure steam turbine. .

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