JP3080228B2 - Power plant control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for controlling a power plant. More specifically, the present invention relates to a power plant control method capable of operating each boiler in an optimal state in a power plant having a plurality of boilers and a plurality of steam turbines.

[0002]

2. Description of the Related Art Conventionally, a power plant has a configuration in which a plurality of boilers and a plurality of steam turbines are combined. Various methods of controlling a power plant having such a configuration have been proposed, but most of them have a boiler B and a steam turbine T arranged adjacent to each other, as shown in FIG. The feedback control of the boiler B is performed by the pressure of the common main pipe (for example, JP-A-3-158601, JP-A-4-55601, JP-A-4-229212, etc.).

[0003] However, recently, construction of a new power plant is difficult due to a problem such as lack of a suitable location, and therefore, a boiler B and a steam turbine T are often added to an existing power plant. ing. In this case, the boiler B and the steam turbine T that are added due to the relationship with the existing equipment are often installed at a location separated from the existing boiler B and the steam turbine T. for that reason,
When the feedback control of the boiler B is performed by the pressure of the common main pipe as shown in FIG. 7, that is, the representative pressure of the boiler B is measured by the main pipe, and the amount of fuel required to maintain the pressure at a predetermined value. When calculating the (heat generation base) and distributing the fuel amount to each of the boilers B, the load distribution of each of the boilers B is performed. In some cases, the pressure of the boiler B installed at the location cannot be maintained at a predetermined pressure.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is intended to solve the problems of each of the boilers even if the plurality of boilers and the plurality of steam turbines are installed at separate places. It is an object of the present invention to provide a power plant control method capable of maintaining a pressure at a predetermined pressure.

[0005]

A method for controlling a power plant according to the present invention is a method for controlling a power plant including a required number of boilers and a required number of steam turbines. steam supplies distribution ratio and sets the generated steam distribution ratio for each boiler, then set the configuration蒸圧force reference boiler, accordingly later steam supply distribution ratio, generating the conduit on the basis of the steam generated distribution ratio and the boiler between flow rate
The required line pressure of each boiler other than the reference boiler is calculated using the pipeline resistance to be set and the set steam pressure, and the set steam pressure is set.
The reference boiler is controlled by force , and each boiler is controlled by the calculated required pressure of each boiler.

In the power plant control method of the present invention, for example, the required pressure of each boiler is calculated by the following equation.

[0007]

(Equation 2)

In the power plant control method of the present invention, when the line resistance of each adjacent boiler is negligible, the control is performed with the pressure of the steam line connecting each of the boilers as the required pressure of the same boiler. In this case, the amount of fuel in the boiler group for which the pipeline resistance is considered negligible is controlled by the generated steam distribution ratio.

Further, when bleeding is performed in the steam turbine, the amount of steam at the inlet of the steam turbine is measured, and the supply steam distribution ratio is set based on the measured value.

[0010]

According to the present invention, as described above, in a power plant including a plurality of boilers and a plurality of steam turbines, the pressure of each boiler can be reduced even if the pipeline resistance cannot be ignored. The pressure can be controlled to correspond to the generated steam distribution.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to only such embodiments.

Embodiment 1 FIG. 1 is a block diagram showing a power plant to which a method for controlling a power plant according to Embodiment 1 of the present invention is applied. In FIG. 1, reference symbol P denotes a boiler outlet pressure, B denotes a boiler, T
Amount of fuel steam turbine, f _F is, f _B is a boiler generating steam amount, f _T is the turbine supply steam amount, f _P is extracted amount, C _B boiler master controller, C _T is the power generation amount controlling unit, W is Power,
R indicates the pipeline resistance, and the arrows indicate the forward direction (positive direction) of the flow, respectively.

[0013] As shown in FIG.
It comprises m boilers B, m steam turbines T, a steam line connecting these boilers B and the steam turbine T, and a fuel line as main components. In this power plant, power demand (power demand)
The amount of steam to be supplied to each steam turbine T is determined based on the power load distribution according to the following, and then the load distribution of the boiler B, that is, the amount of generated steam, is determined according to the supplied steam amount.
After that, each boiler B to secure the generated steam amount
(Required pressure) is calculated.

Next, the calculation of the required pressure of each boiler B will be described.

In the power plant shown in FIG. 1, the distribution of the amount of steam supplied to the steam turbine T determined from the distribution of electric power: f _{T (i)} = α _{T (i)} · f _all , and the amount of generated steam as the boiler load distribution Allocation: fB _(i) = αB _(i) · _fall is set.

Where, f _all : total steam amount α _{T (i)} : supply steam distribution ratio (Σα _{T (i)} = 1 (i = 1 to
m)) α _{B (i)} : generated steam distribution ratio (Σα _{B (i)} = 1 (i = 1 to
m))

Using the above relationship, each boiler B, B
Flow rate f_{(i) (i + 1)}Is from a well-known algebraic relationship
It is represented by the following equation (1). Note that the subscript (i) (i +
1) is from the (i) th boiler B (i) to the (i + 1) th boiler
Indicates that steam is flowing to boiler B (i + 1). f_{(i) (i + 1)}= (Σ (α_{B (k)}−α_{T (k)})) ・ F_all (I
= 1 to m-1) (1) In addition, the above equation (1) is used.
Then, the required pressure P of each boiler B_{B (i)}Is, for example, the first boy
(I = 1), and the pressure loss ΔP is squared.
(ΔP = sgn (f) ・ R ・ f ^Two) Is given by the following equation (2).
Is represented.

[0018]

(Equation 3)

In the equation (2), the pipe resistance R
_{Since B (i)} and R _{(i) (i + 1)} can be calculated by various known methods, the supply steam distribution ratio: α _{T (i)} and the generated steam distribution ratio: α _{B (i)} Required pressure P in each boiler B
_{B (i)} can be calculated. Here, the subscript (i) of the pipe resistance R
(I + 1) is the (i) th boiler B (i) and (i + 1)
This indicates that the pipeline resistance R is between the boilers B (i + 1). In the above equation (2), the first boiler B (1) is used as the reference boiler B, but the reference boiler B can be any boiler.

As described above, according to the first embodiment, the plurality of boilers B are installed at distant locations, and the plurality of steam turbines T are also installed at distant locations. Even if the loss is not negligible, the required pressure of each boiler B can be calculated. Therefore, by controlling the boiler B so that the pressure becomes equal to the required pressure, for example, by controlling the fuel amount f _F , the generation according to the predetermined load distribution The amount of steam can be secured.

Embodiment 2 The control method of a power plant according to Embodiment 2 of the present invention is applied.
FIG. 2 is a block diagram showing the power plant that is being used. Said
Equation (2) is used to determine the amount of generated evaporation of each boiler B.
For this purpose, the steam line between the adjacent boilers B
The condition that the pipeline resistance R exists (R_{(i-1) (i)}+ R
_{B (i-1)}+ R_{B (i)}> 0) is required, so that adjacent
La and B are close to each other, and the pipeline resistance R between them is negligible.
(In the example shown in FIG. 2, the pipe of the first boiler B (1)
Road resistance R₍₁₎And the pipeline resistance R of the second boiler B (2)₍₂₎You
And between the first boiler B (1) and the second boiler B (2)
Pipe resistance R_{(1) (2)}Is ignorable. )
Can calculate the required pressure of those boilers B
However, the amount of generated evaporation of the boiler B cannot be determined.
Therefore, in the second embodiment, the steam line between
It is treated as a separate mother tube. That is, next to
Each boiler in contact (first boiler and second boiler in the example shown)
The embodiment in which the required pressure of B is represented by the pressure of the main pipe
Calculate in the same way as 1 and calculate the pressure of boiler B by the pressure.
And the generated steam distribution ratio: α _{B (i)}In response to the
Each boiler (boiler) whose pipeline resistance R is considered negligible
Group) fuel amount f of B_FGenerated steam distribution ratio α_{B (i)}Controlled by
Control.

As described above, according to the second embodiment, even if the adjacent boilers B are close to each other and the pipeline resistance R therebetween is negligible, the required pressure and the pipeline resistance of each boiler B the generation amount of steam boilers group R is a negligible can be calculated, and controls the boiler B so that its pressure, for example by controlling the fuel amount f _F, generating steam amount according to the load distribution Can be secured.

Third Embodiment FIG. 3 is a block diagram showing a power plant to which a power plant control method according to a third embodiment of the present invention is applied. The third embodiment is a modification of the first embodiment, in which bleeding is performed in the steam turbine T. In this case, since the power load distribution and the supply steam amount distribution cannot be uniquely determined, the steam amount at the inlet of the steam turbine T is measured, and the supply steam distribution is determined based on the steam amount obtained by the measurement. It becomes. That is, α _{T (i)} = f _{T (i)} / f _all where f _all = Σf _{T (i)} (i = 1, 2, 3,...,
m)

As described above, according to the third embodiment, even when bleeding is performed in the steam turbine T, the required pressure of each boiler B in that case can be calculated. controlling the B, it can ensure the generation amount of steam in accordance with the load distribution by controlling, for example, fuel quantity f _F.

In the first to third embodiments, the number of boilers B and the number of steam turbines T are matched, but the number of boilers B and the number of steam turbines T need not necessarily match. Absent. For example, when the number of cans of the boiler B is larger than the number of steam turbines T, it can be dealt with by setting the supply steam amount distribution ratio αT _(i) to the steam turbine T at an appropriate location to zero. Conversely, when the number of cans in the boiler B is smaller than the number of steam turbines T, it can be dealt with by setting the generated steam distribution ratio αB _(i) to the boiler B at an appropriate location to zero. When so-called unit control is performed, the generated steam distribution ratio of the boiler B that is not operated: α
_This can be dealt with by setting _{B (i)} to zero and setting the supply steam distribution ratio α _{T (i)} of the steam turbine T that is not operated to zero.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically based on more specific embodiments.

Example 1 Example 1 is an embodiment of the first embodiment.
As shown in FIG. 4, a power plant is constituted by four boilers B and four steam turbines T.
The power demand of this power plant is 48 MW, and the supply steam distribution ratio of the first to fourth steam turbines T (1) to T (4) determined from the corresponding power load distribution: α
_{T (1) to} αT ₍₄₎ are 0.19, 0.23, 0.2, respectively.
Is a 7,0.31, also the first to fourth boiler B (1) ~B (4) generating steam distribution ratio determined from boiler load _{allocation: α B (1) ~α B} (4) , respectively 0.2, 0.3, 0.
3, 0.2. Therefore, the generated steam distribution of the first to fourth boilers B (1) to B (4): fB _{(1) to} fB ₍₄₎
Are 80t / h, 120t / h, 120t / h,
80 t / h, and the first to fourth steam turbines T
(1) -T (4) supply steam distribution: 76 t / h, 92 t
/ H, 108 t / h, 124 t / h, and the flow rate f _{(i) (i + 1)} between the boilers B, B is obtained from the first boiler B (1) and the second boiler B (1) according to the equation (1). The flow rate between the boilers B (2): f _{(1) (2)} becomes 4 t / h, and the second boiler B
Flow rate between (2) and third boiler B (3): f _{(2) (3)}
Is 32 t / h, and the flow rate f _{(3) (4)} between the third boiler B (3) and the fourth boiler B ₍₄₎ is 44 t / h. The pipeline resistance of the first boiler B (1): R _{B (1)} is set to 0.043 kPa / (t / h) ² , and the second boiler B (2)
Pipe resistance of RB ₍₂₎ is 0.035 kPa / (t /
h) ² , the pipeline resistance of the third boiler B (3): R _{B (3) is set} to 0.
035 kPa / (t / h) ² , pipeline resistance of the fourth boiler B (4): RB ₍₄₎ is 0.043 kPa / (t / h) ² , the first boiler B (1) and the second boiler B Pipe resistance between (2): R _{(1) (2)} is 0.112 kPa / (t / h) ² , second
Pipe resistance between the boiler B (2) and the third boiler B (3): R _{(2) (3)} is set to 0.092 kPa / (t / h) ² ,
The pipe resistance between the boiler B (3) and the fourth boiler B (4): R _{(3) (4)} is set to 0.092 kPa / (t / h) ² . The reference pressure in the above equation (2) is set to 11.7 MPa in the first boiler B (1).

Therefore, from the above equation (2), the pressure P _{B (2)} of the second boiler _{B (2)} is 11.93 MPa, the pressure P _{B (3)} of the third boiler _{B (3)} is 11.84 MPa, The pressure P _{B (4)} of the fourth boiler B (4) becomes 11.43 MPa. That is, the pressure P _{B (1)} of the first boiler B (1) is increased to 11.7M.
Pa, the pressure P _{B (2)} of the second boiler B (2) is set to 11.93M.
Pa, the pressure P _{B (3)} of the third boiler B (3) is set to 11.84M.
Pa, the pressure P _{B (4)} of the fourth boiler B (4) is set to 11.43M.
By controlling to be Pa, a desired amount of generated steam can be obtained in the first to fourth boilers B (1) to B (4).

Example 2 This example 2 is a specific example of the second embodiment.
As shown in FIG. 5, a power plant is composed of four boilers B and four steam turbines T, and the first boiler B
The pipeline resistance R _{(1) of (1)} , the pipeline resistance R _{(2) of} the second boiler B (2), and the first boiler B (1) and the second boiler B
The line resistances R _{(1) and (2)} between (2) and ₍₂₎ are each made zero. The power demand of this power plant is set to 48 MW, and the supply steam distribution ratio of the first to fourth steam turbines T (1) to T (4) determined from the corresponding power load distribution: α _{T (1) to} α _{T (4)} is 0.19,
0.23, 0.27, 0.31 and the first to fourth boilers B (1) to B (1) to B determined from the boiler load distribution.
The generated steam distribution ratios of (4): α _{B (1) to} α _{B (4)} are 0.2, 0.3, 0.3, and 0.2, respectively. Therefore, the generated steam distributions of the first to fourth boilers B (1) to B (4): fB _{(1) to} fB ₍₄₎ are 80 t / h and 120 t, respectively.
/ H, 120 t / h, 80 t / h, and the supply steam distribution of the first to fourth steam turbines T (1) to T (4): 7
6t / h, 92t / h, 108t / h, 124t / h, and the flow rate between the boilers B, B: f _{(i) (i + 1)} is
From the above equation (1), the flow rate f _{(1) (2)} between the first boiler B (1) and the second boiler B ₍₂₎ is 4 t / h, and the second boiler B (2) and the third boiler Flow rate between B (3):
f _{(2) (3)} is 32 t / h, and the flow rate between the third boiler B (3) and the fourth boiler B (4): f _{(3) (4)} is 44 t / h.
/ H. Then, the pipeline resistance of the first boiler B (1):
RB _{(1 )} is set to 0.0 kPa / (t / h) ² and the second boiler B
Pipe resistance of ₍₂₎ : RB ₍₂₎ is 0.0 kPa / (t / h)
^2. Pipe resistance of the third boiler B (3): RB ₍₃₎ is 0.03
5 kPa / (t / h) ² , pipeline resistance of the fourth boiler B (4): RB ₍₄₎ is 0.043 kPa / (t / h) ² , the first boiler B (1) and the second boiler B Pipe resistance between (2):
R _{(1) (2)} is set to 0.0 kPa / (t / h) ² , and the second boiler B
Pipe resistance between (2) and the third boiler: R _{(2) (3)} is 0.092 kPa / (t / h) ² , and the third boiler B (3)
And the pipeline resistance between the fourth boiler B (4): R _{(3) (4)} is 0.092 kPa / (t / h) ² . Further, the reference pressure in the above equation (2) is set to 11.7 MPa in the common mother pipe of the first boiler B (1) and the second boiler B (2).

Therefore, from the above equation (2), the pressure P _{B (3)} of the third boiler _{B (3)} is 12.11 MPa, and the pressure P _{B (4)} of the fourth boiler _{B (4)} is 11.70 MPa. Become. That is, the first boiler B (1) and the second boiler B (2)
The pressure PB ₍₁₎ of the common main pipe is 11.73 MPa, the pressure PB (3) of the third boiler _{B (3)} is 11.84 MPa, and the pressure PB (4) of the fourth boiler _{B (4)} is The first boiler B (1) and the second boiler B are controlled to be 11.43 MPa.
If the fuel distribution ratio (f _{F (1)} : f _{F (2)} ) to ₍₂₎ is controlled to 2: 3, desired steam generated in the first to fourth boilers B (1) to B (4) can be obtained. The amount is obtained.

Example 3 Example 3 is an embodiment of the third embodiment.
As shown in FIG. 6, a power plant is configured by four boilers B and four steam turbines T. The power demand of this power plant is assumed to be 24 MW, the corresponding power load distribution and the amount of bleed air of the steam turbine:
f _{P (i)} is the amount of extracted air: f in the first steam turbine T (1).
_{P (1)} is 38 t / h, the amount of bleed air in the second steam turbine T (2): f _{P (2)} is 46 t / h, and the amount of bleed air in the third steam turbine T (3): f _{P (3)} is 54 t. / H, fourth steam turbine T
In (4), the amount of extracted air: f _{P (3)} is determined from 62 t / h, and is the amount of steam supplied to the first to fourth steam turbines T (1) to T (4), that is, the first to fourth steam turbines. T (1)-T
(4) Supply steam distribution: 76 t / h, 92 t / h, 10
From 8 t / h and 124 t / h, the supply steam amount distribution ratio of the first to fourth steam turbines T (1) to T (4): α _{T (1) to} α
_{T (4)} is 0.19, 0.23, 0.27, 0.3, respectively.
1, and the generated steam distribution ratio of the first to fourth boilers B (1) to B (4) determined from the boiler load distribution: α _{B (1)}
To α _{B (4)} are 0.2, 0.3, 0.3, and 0.2, respectively. Therefore, the first to fourth boilers B (1) to
Distribution of generated steam of B (4): f _{B (1) to} f _{B (4)} are each 8
0 t / h, 120 t / h, 120 t / h, 80 t / h, and the flow rate between the boilers B, B: f _{(i) (i + 1)} is
From the above equation (1), the flow rate f _{(1) (2)} between the first boiler B (1) and the second boiler B ₍₂₎ is 4 t / h, and the second boiler B (2) and the third boiler Flow rate between B (3):
f _{(2) (3)} is 32 t / h, and the flow rate between the third boiler B (3) and the fourth boiler B (4): f _{(3) (4)} is 44 t / h.
h. Then, the pipeline resistance of the first boiler B (1): R
_{B (1)} is 0.043 kPa / (t / h) ² , the second boiler B
Pipe resistance of ₍₂₎ : RB ₍₂₎ is set to 0.035 kPa / (t /
h) ² , the pipeline resistance of the third boiler B (3): R _{B (3) is set} to 0.
035 kPa / (t / h) ² , pipeline resistance of the fourth boiler B (4): R _{B (4)} is 0.043 kPa / (t / h) ² , the first boiler B (1) and the second boiler B Pipe resistance between (2): R _{(1) (2)} is 0.112 kPa / (t / h) ² ,
Pipe resistance between the boiler B (2) and the third boiler B (3): R _{(2) (3)} is set to 0.092 kPa / (t / h) ² ,
The pipe resistance between the boiler B (3) and the fourth boiler B (4): R _{(3) (4)} is set to 0.092 kPa / (t / h) ² , and the reference pressure in the above equation (2) is In the first boiler B (1), the pressure is set to 11.7 MPa.

Therefore, from the above equation (2), the second boy
La B (2) pressure P_{B (2)}Is 11.93MPa, 3rd boil
La B (3) pressure P_{B (3)}Is 11.83MPa, 4th boil
La B (4) pressure P_{B (4)}Becomes 11.43 MPa. You
That is, the pressure P of the first boiler B (1)_{B (1)}11.7M
Pa, pressure P of second boiler B (2)_{B (2)}11.93M
Pa, pressure P of the third boiler B (3)_{B (3)}11.84M
Pa, pressure P of the fourth boiler B (4)_{B (4)}11.43M
If the fuel pressure is controlled to be Pa, the fuel amount f _{F (1)}~ F
_{F (4)}Is controlled, the first boiler B (1) to the fourth boiler B
In (4), a desired amount of generated steam is obtained.

Although the present invention has been described based on the embodiments and the examples, the present invention is not limited to the embodiments and the examples, and various modifications are possible. For example, in Embodiment 3 and Example 3, bleeding is performed for all steam turbines, but it is not always necessary to bleed from all steam turbines. In the second embodiment, the pipe resistance of two adjacent cans is negligible, but may be three or more.

[0034]

As described in detail above, according to the present invention,
In a power plant consisting of a plurality of boilers and a plurality of steam turbines, an excellent effect that the pressure of each boiler can be controlled to a pressure corresponding to the generated steam amount distribution even when the pipeline resistance cannot be ignored. Is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power plant according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram of a power plant according to Embodiment 2 of the present invention.

FIG. 3 is a block diagram of a power plant according to Embodiment 3 of the present invention.

FIG. 4 is a block diagram of a power plant according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a power plant according to a second embodiment of the present invention.

FIG. 6 is a block diagram of a power plant according to a third embodiment of the present invention.

FIG. 7 is a block diagram of a conventional power plant.

[Explanation of symbols]

B Boiler T Steam turbine f _F Fuel amount f _B Boiler generated steam amount f _T Turbine supply steam amount f _P Bleed amount C _B Boiler master controller C _T Power generation amount controller P Boiler outlet pressure W Power R Pipe resistance

Continued on the front page (72) Inventor Toshiro Ito 2-11-1, Minamisuna, Koto-ku, Tokyo Kawasaki Heavy Industries, Ltd. Tokyo Design Office (72) Inventor Norihiko Wasada 2-1-1, Minamisuna, Koto-ku, Tokyo Kawasaki Heavy Industries, Ltd. Tokyo Design Office (72) Inventor Mitoshitoshi Hatori 2-1-1, Minamisuna, Koto-ku, Tokyo Kawasaki Heavy Industries, Ltd. Tokyo Design Office (56) References JP-A-4-55601 (JP, A) Kaihei 3-158601 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) F22B 35/00 F01D 17/00 F01D 17/24 F01K 7/38 102

Claims (5)

(57) [Claims] 1. A method for controlling a power plant including a required number of boilers and a required number of steam turbines, wherein a distribution ratio of supply steam to each steam turbine and a distribution ratio of generated steam of each boiler are determined based on an electric power demand. set, then set the configuration蒸圧force reference boiler, accordingly later steam supply distribution ratio,
Generated in pipeline based on generated steam distribution ratio and flow rate between boilers
And pipeline resistance to live, to calculate the required pressure for each boiler other than the reference boiler using said setting steam pressure, the setting steam
A control method for a power plant, wherein the reference boiler is controlled by pressure, and each boiler is controlled by the calculated required pressure of each boiler. 2. The method according to claim 1, wherein the required pressure of each boiler is calculated by the following equation. (Equation 1) 3. The power plant according to claim 1, wherein when the line resistance of each adjacent boiler is negligible, the pressure of the steam line connecting each of the boilers is set to a required pressure of the boiler. Control method. 4. The boiler's pipeline resistance and the pipeline resistance between the boilers are controlled to be negligible, and the fuel amount of the boiler group is controlled by the generated steam distribution ratio.
The control method of the power plant according to the above. 5. The steam turbine according to claim 1, wherein when bleeding is performed in the steam turbine, a steam amount at a steam turbine inlet is measured, and a supply steam distribution ratio is set based on the measured value. Power plant control method.