AU2018270018B2

AU2018270018B2 - Boiler combustion control system and boiler combustion control method

Info

Publication number: AU2018270018B2
Application number: AU2018270018A
Authority: AU
Inventors: Nobuhiro KASHIMA; Kazuki MASUHARA; Hiroaki Nishiyama; Yuji Okamura; Kenichiro SUTOH; Kazunori Taniguchi; Toru Yamashita
Original assignee: Idemitsu Kosan Co Ltd; Nippon Yusen KK; NYK Trading Corp
Current assignee: Idemitsu Kosan Co Ltd; Nippon Yusen KK; NYK Trading Corp
Priority date: 2017-05-16
Filing date: 2018-05-16
Publication date: 2023-04-06
Anticipated expiration: 2038-05-16
Also published as: CN110832250B; MY197403A; WO2018212224A1; JP6894503B2; WO2018211598A1; JPWO2018212224A1; AU2018270018A1; TWI672469B; CN110832250A; TW201901083A; KR102422056B1; KR20200029383A

Abstract

Disclosed is a boiler combustion control system that outputs a fuel correction coefficient for correcting a load demand amount after feedback correction. This system comprises: a fuel correction coefficient computation unit that calculates a fuel correction coefficient on the basis of a ratio between load demand amounts before and after feedback correction, and an initial value and a fine adjustment function that define an initial value of a relationship between the load demand amount and a fuel supply amount; and a reference curve correction unit that outputs a reference curve correction coefficient for correcting the initial value and the fine adjustment function. The reference curve correction unit includes: a deviation determination unit that calculates the deviation between a measured main steam pressure and a setting main steam pressure; a period determination unit that acquires a period related to the fluctuation of the deviation; an amplitude determination unit that acquires amplitude; a reference curve correction coefficient output unit that calculates and outputs the reference curve correction coefficient on the basis of a reference curve correction function; and a reference curve correction determination unit that corrects the reference curve correction function in cases where the combination of the period and the amplitude satisfies a predetermined condition.

Description

SPECIFICATION TITLE OF THE INVENTION BOILER COMBUSTION CONTROL SYSTEM AND BOILER COMBUSTION CONTROL METHOD TECHNICAL FIELD

[0001]

The present invention relates to a technique to control

combustion of a boiler, and more specifically, the present invention

relates to a technique that is effective for applying a boiler

combustion control system and a boiler combustion control method

for determining a fuel charging amount to a boiler on the basis of

a load demand of the boiler.

BACKGROUND ART

[0002]

For example, in a case where a boiler facility is used to

acquire energy, fuel (solid fuel, liquid fuel, or gas fuel) is

supplied to a boiler (or a furnace) to burn, and its heat is absorbed

by aheat exchanger to cause steam to be generated, thereby obtaining

thermal energy. The generated steam is supplied to a steam turbine

to be converted from the thermal energy into rotary motion, thereby

beingusedforpower generationby anelectricgenerator, forexample.

A fuel charging amount to the boiler is determined by a fuel function

FX. The fuel function FX is a relational expression between a load

demand (for example, power generation demandMWD (MegaWatt Demand);

hereinafter, referred to also as a "load demand MWD") and the fuel

charging amount to the boiler (hereinafter, referred to also as a

"boiler input command value BID (Boiler Input Demand)").

[0003]

Here, variation in an operation state of the boiler, in

particular, variation in a main steam pressure may occur due to an

influence by factors related to a boiler facility, for example, a

fuel property or heat quantity, furnace grime, soot blower, air and

water temperature, or the like. Therefore, a control in which fuel

related to a fuel charging amount found by the fuel function FX is

supplied to the boiler, the generatedmain steampressure ismeasured,

a feedback correction amount is found by a PID

(Proportional-Integral-Differential) control on the basis of a

difference between this measured pressure and amain steampressure

set in advance, and the fuel charging amount to the boiler is

corrected by adding this feedback correction amount to a load demand

has been executed generally.

[0004]

Asa technique related to this, forexample, JapanesePatent

No. 4,522,326 (Patent document 1) describes that a plurality of

ratios or differences between values before and after feedback

correction is executed are recorded while updating them in turn,

a fuel correction factor is found from the plurality of recorded

values, and a value after the feedback correction is corrected by

this fuel correction factor. This makes it possible to correct a

fuel charging amount into proper one in view of a change in thermal

efficiency of a boiler due to an influence of factors.

[0005]

Moreover, for example, Japanese Patent No. 4791269 (Patent

Document 2) describes that, in a mixed combustion boiler for plural

kinds of fuels, by subdividing a fuel correction factor for

correcting a value after feedback correction into three elements,

a fuel charging amount to the boiler is corrected so as to address

a difference ofunit heat quantity of fuel and a difference ofboiler

thermal efficiency with a change in a mixed fuel combustion ratio.

RELATED ART DOCUMENTS PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent No. 4522326

Patent Document 2: Japanese Patent No. 4791269

SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0007]

For example, according to the conventional technologies of

Patent document 1 or 2, by always comparing and measuring values

of a load demand MWD before and after feedback correction (or other

control values) with respect to a change in thermal efficiency of

the boiler due to an influence ofthe factors, this canbe determined,

and a value of a correction factor for further correcting and

optimizing the value after the feedback correction on the basis of

a determination result can be acquired by self-learning.

[0008]

On the other hand, a fuel function FX that defines a

relationship between the load demand MWD and a boiler input command

value BID corresponding thereto as a function (or a curved line)

is set so as to property ofaboiler. In the conventionaltechnology,

it is set as a fixed value that is calculated in advance on the basis

of accumulation of past actual measurement data and the like.

However, behavior of a main steam pressure based on the property

of the boiler is different depending on an individual boiler.

Moreover, even in one boiler, the behavior may vary due to update

of a boiler facility or the like. Namely, very small deviation may

occur between actual behavior of the main steam pressure and an

appropriate value (or an optimum value), which is supposed in the

fuel function FX. This deviation causes deviation from the optimum

value of the fuel charging amount, whereby a combustion control

process of the boiler becomes unstable, and as a result, loss of energy may occur.

[0009] It is thus an object of the present invention to provide a

boiler combustion control system and a boiler combustion control

method capable of detecting deviation from an optimum value, which

is supposed by a fuel function FX in behavior of a main steampressure,

and revising the fuel function FX autonomously and in a

self-contained manner.

[0010]

The foregoing and other objects, and new features of the

present invention will become more apparent from description of the

present specification and the appending drawings.

MEANS FOR SOLVING THE PROBLEM

[0011]

An outline of representative invention of the present

invention disclosed in the present application and the like will

briefly be explained as follows.

[0012]

A boiler combustion control system according to a

representative embodiment of the present invention is a boiler

combustion control system configured to: supply fuel related to a

fuel charging amount to a boiler to the boiler, the fuel charging

amount being calculated on a basis of a predetermined fuel function

for a load demand; find a feedback correction amount on a basis of

a measured main steam pressure and a set main steam pressure, the

measured main steam pressure being a main steam pressure of the

boiler that is measured, the set main steam pressure being a main

steam pressure for the boiler that is set in advance; and output

a fuel correction factor for correcting the load demand or the fuel

charging amount to a plant after feedback correction, the plant

correcting the load demand or the fuel charging amount on a basis

of the feedback correction amount. The boiler combustion control system includes: a fuel correction factor arithmetic unit configured to calculate the fuel correction factor on a basis of a ratio of the load demand before and after the feedback correction, and an initial value/fine adjustment function that defines an initial value of a relationship between the load demand and the fuel charging amount with respect to the boiler; and a reference curve correcting unit configured to output a reference curve correction factor for correcting the initial value/fine adjustment function.

[0013]

In this case, the reference curve correcting unit includes:

a deviation determining unit configured to calculate a deviation

between the measured main steam pressure and the set main steam

pressure; a cycle determining unit configured to acquire and record

a cycle related to variation in the deviation; an amplitude

determining unit configured to acquire and record amplitude related

to the variation in the deviation; a reference curve correction

factor output unit configured to calculate the reference curve

correction factor on a basis of a predetermined reference curve

correction function and output the calculated reference curve

correction factor; and a reference curve correction determining

unit configured to determine whether a combination of the cycle and

the amplitude satisfies a predetermined condition or not, the

reference curve correction determining unit configured to correct

the reference curve correction function on a basis of a control state

for the boiler in a case where the reference curve correction

determining unit determines that the combination satisfies the

predetermined condition.

EFFECTS OF THE INVENTION

[0014]

Effects obtained by representative invention of the present

invention disclosed in the present application will briefly be

explained as follows.

[0015]

Namely, according to the representative embodiment of the

present invention, it becomes possible to detect deviation from an

optimum value, which is supposed by a fuel function FX in behavior

of a main steam pressure, and revise the fuel function FX

autonomously and in a self-contained manner.

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0016]

FIG. 1 is a view illustrating an outline of a configuration

example of a boiler combustion control system according to a first

embodiment of the present invention.

FIG. 2 is a view illustrating an outline of an example of

a configuration of a reference curve correcting unit according to

the first embodiment of the present invention.

FIG. 3 is a flow diagram illustrating an example of a flow

for correcting an initial value/fine adjustment function according

to the first embodiment of the present invention.

FIG. 4 is a view illustrating an outline of an example of

behavior of a main steam pressure.

FIG. 5 is a view illustrating an outline of a configuration

example of a boiler combustion control system according to a second

embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0017]

Hereinafter, embodiments of the present invention will be

described in detail with reference to the drawings. Note that in

allofthe drawings for explainingthe embodiment, the same reference

numeral is generally assigned to the same unit, and its repeated

explanation will be omitted. On the other hand, a component has

been explained in a certain drawing while applying a reference numeral thereto is not illustrated again when another drawing is to be explained, but the element may be referred to by applying the same reference numeral thereto.

[0018]

(First Embodiment)

In a case where a boiler facility is used to acquire energy

as described above, a fuel (for example, such as coal or biomass

fuel) charging amount (a boiler input command value BID)

corresponding to a steam demand of a boiler (a load demand MWD) is

determined by using the fuel function FX. At this time, the load

demand MWD is controlled to execute feedback correction so that a

main steampressure ofthe boiler approaches adesired setmain steam

pressure.

[0019]

In contrast, in the conventional technology as disclosed in

Patent documents 1 and 2 described above, in order to further improve

accuracy of control, there is a mechanism to find a fuel correction

factor by self-learning on the basis of a ratio of the load demand

MWD before and after the feedback correction is executed, that is,

an index indicating an operation degree of the feedback correction

for the main steam pressure, and further correct the load demand

MWD (or the boiler input command value BID) by this fuel correction

factor. It may be said that this correction is substantially

equivalent to correction of the fuel function FX.

[0020]

In order to further improve accuracy with respect to the

conventional technology described above, the boiler combustion

control system according to the first embodiment of the present

invention causes AI (Artificial Intelligence) to correct a

reference curve that becomes a base or a starting point of

self-learning. This reference curve indicates an initial value of

a relationship between the load demand MWD and the boiler input command value BID, which are defined for a target boiler. In the conventional technology, this reference curve was set as a fixed value that is calculated in advance on the basis of accumulation of past actual measurement data in the similar manner to that of the fuel function FX. In this case, behavior of the main steam pressure may slightly be deviated from an optimum value, which is supposed in the fuel function FX after correction by a fuel correction factor due to facility update of the boiler or change in other state, whereby a combustion control process of the boiler may become unstable and this may cause efficiency thereof to be lowered.

[0021]

In contrast, the boiler combustion control system according

to the present embodiment always analyzes and determines behavior

and state transition of the main steam pressure of the boiler on

the basis of past data, and adjusts the reference curve described

above on the basis of a determination result, thereby corrects small

deviation that occurs in the fuel function FX. In the present

embodiment, this series of processes is executed autonomously and

in real time by a self-contained processing loop.

[0022]

FIG. 1 is a view illustrating an outline of a configuration

example of a boiler combustion control system according to the first

embodiment of the present invention. As described above, a boiler

combustion control system 1 is an apparatus that adjusts a reference

curve by using an initial value/fine adjustment function FXAI so

that a fuel charging amount to a boiler 2 in a plant becomes optimum

to determine a fuel correction factor K, and outputs, as control

information, the fuel correction factor K to an existing circuit

that executes fuel charge to the boiler 2 (that is, combustion of

the boiler 2 is controlled by substantially correcting the fuel function FX).

[0023]

The boiler combustion control system 1 may be configured,

for example, as an apparatus implemented by hardware that consists

of a semiconductor circuit, a microcomputer, or the like (not

illustrated in the drawings), which executes processes related to

respective functions (willbe described later). Alternatively, the

boiler combustion control system 1 may be configured by

general-purpose server equipment or a virtual server built on cloud

computing service, and may execute processes related to the

respective functions (will be described later) by executing

middleware such as an OS (Operating System), which is developed onto

a memory from a recording device such as a HDD (Hard Disk Drive)

by aCPU (CentralProcessingUnit) (not illustratedin the drawings),

or software that operates thereon.

[0024]

Further, the boiler combustion control system 1 may be

configured by appropriately combining implementation by the

hardware and implementation by the software. Further, it is not

limited to a configuration in which the whole is implemented in one

housing. It may be configured so that a part of the functions is

implemented in another housing and these housings are mutually

connected to each other by a communication cable or the like. Namely,

the embodiments of the boiler combustion control system 1 are not

limited particularly, and can be appropriately configured flexibly

in accordance with an environment or the like of the plant.

[0025]

As illustrated in FIG. 1, the boiler combustion control

system 1 includes, for example, respective units such as a divider

11, a reference curve correcting unit 12, a multiplier 13, or a fuel

correction factor arithmetic unit 14, each of which is implemented

by hardware or software. Further, the boiler combustion control system1has data such as the initialvalue/fine adjustment function

FXAI, each of which is implemented as a file or a table recorded

in the memory or the HDD.

[0026]

In the plant, a main steam generated in the boiler 2 on the

basis of information on the fuel charging amount (in FIG. 1, the

boiler input command value BID) by causing the fuel to burn is

supplied to a steam turbine 3, for example, to use power generation

or the like by an electric generator (not illustrated in the

drawings). A load demand MWD (that is, an input steam demand) of

the boiler 2 corresponding to an output by the electric generator

is inputted by an operation panel (not illustrated in the drawings)

in the boiler 2, for example, and is also inputted to the boiler

combustion control system 1.

[0027]

On the other hand, for example, a pressure of the main steam

generated in the boiler 2 is measured by a pressure meter (not

illustrated in the drawings) provided in the boiler 2, and a

measurement value is inputtedinto amain steampressure transmitter

PX. A measured main steam pressure PV transmitted from the main

steam pressure transmitter PX is inputted into a PID control unit

4, and comparison between the measured main steam pressure PV and

a set main steam pressure SV is executed by the PID control unit

4. The set main steampressure SVis an originalmain steampressure.

At this time, for example, if the fuel charging amount is determined

by using the fuel function FX that is obtained in a condition in

which a state of the boiler 2 (such as grime of a furnace), a fuel

property, andthe other factors are maintained, a difference between

the measured main steam pressure PV and the set main steam pressure

SV is hardly generated, and a desired load (an electric generator

output) can be obtained by the fuel function FX. However, as

described above, for example, a pressure difference between the measured main steam pressure PV and the set main steam pressure SV may be generated with the state transition of the boiler 2, or a change in the fuel property or the other factors.

[0028]

In a case where the pressure difference between the measured

main steampressure PVandthe setmain steampressure SVis detected,

the PID control unit 4 calculates a feedback correction amount, that

is, deviation (or an error amount) of the main steam pressure

generated by fuel shortage (or excess) by using a known PID control

method, and sends this to an adder 5. The adder 5 adds the feedback

correction amount sent from the PID control unit 4 to the load demand

MWD also inputted into the boiler combustion control system 1, and

outputs a load demand MWD' after feedback correction (a boiler input

command value BID') (the PID control unit 4 and the adder 5 may be

referred to as a "feedback control unit").

[0029]

In the boiler combustion control system 1 according to the

present embodiment, as described above, similarly to the

conventional technology of Patent document 1 or 2, the divider 11

finds an index indicating an operation degree of the feedback

correction by the feedback control unit (including the PID control

unit 4 and the adder 5), that is, a ratio between the load demand

MWD and the load demand MWD' (the boiler input command value BID')

in order to follow the deviation from the optimum value with a change

in a property such as efficiency of the boiler 2. The load demand

MWD and the load demand MWD' are command values before and after

the feedback correction. Then, by using this index as an input,

the fuel correction factor arithmetic unit 14 calculates the fuel

correction factor K by self-learning, and outputs it.

[0030]

A multiplier 6 multiplies the load demand MWD' by the

outputted fuel correction factor K (the boiler input command value

BID'). By using this load demand MWD" after correction (a boiler

input command value BID") as an input, a fuel charging amount

arithmetic unit 7 converts this into the boiler input command value

BID by means of the fuel function FX. Charge of fuel to the boiler

2 is controlled on the basis of this boiler input command value BID.

[0031]

Note that with respect to a method of calculating the fuel

correction factor K by the fuel correction factor arithmetic unit

14 of the boiler combustion control system 1, for example, a method

similar to those described in Patent documents 1 and 2 can be used

appropriately. Thus, repeated detailed description herein may be

omitted. Further, as disclosed in Patent documents 1 and 2, a

relation of connection of the respective units including the boiler

combustion controlsystem1in the plant andprocessingorder thereof

is not limited to those illustratedin FIG.1. Aconfiguration based

on any of various kinds of variations can be adopted appropriately

within a scope of the similar idea. For example, in the example

illustrated in FIG. 1, the load demand MWD' after the feedback

correction is correctedby multiplyingby the fuelcorrection factor

K. However, it may be configured so as to correct the boiler input

command value BID found by the fuel charging amount arithmetic unit

7 by multiplying by the fuel correction factor K. Further, it may

be configured so as to directly correct the fuel function FX.

[0032]

As described above, in the determination of the fuel

correction factor K, the self-learning is executed by using the

reference curve as a starting point. However, in the conventional

technology, a fixed value set in advance has been used for the

reference curve. In this case, this reference curve may also be

deviated lightly from the optimum value with a change in property

such as the efficiency of the boiler 2, whereby the combustion

control process of the boiler 2 may become unstable and this may cause the efficiency thereof to be lowered. For this reason, in the present embodiment, the reference curve correcting unit 12 always executes comparison and measurement between the measured main steampressure PV ofthe boiler 2 and the set main steampressure

SV that is an original setting value; analyzes and determines a

change in the behavior of the main steam pressure of the boiler 2;

and sets a reference curve correction factor KP on the basis of a

determination result. Then, the multiplier 13 multiplies the

initial value/fine adjustment function FXAI by this factor to

correct an initial value of the reference curve defined in the

initial value/fine adjustment function FXAI in real time.

[0033]

FIG. 4 is a view illustrating an outline of an example of

the behavior of the main steam pressure. Each stage of the FIG.

4 illustrates, by a curved line, an example of variation in the

measured main steam pressure PV with a lapse of time, and also

illustrates, by a straight line, the set main steam pressure SV.

An upper stage ofFIG. 4 indicates a case where a degree ofcorrection

(correction by the fuel correction factor K and integral correction

by PID control) is set tobe strong, andillustrates that the measured

main steam pressure PV greatly varies so as to stride across the

set main steam pressure SV. In contrast, a middle stage of FIG.

4 indicates a case where the degree of correction is optimum, and

illustrates that the measured main steam pressure PV varies in the

vicinity of the set main steam pressure SV. On the other hand, a

lower stage of FIG. 4 indicates a case where the degree of correction

is set to be weak, and illustrates that the measured main steam

pressure PV greatly varies slowly so as to stride across the set

main steam pressure SV as a whole while repeating small variation.

[0034]

Here, the boiler combustion control system 1 according to

the present embodiment grasps the behavior of the main steampressure by oscillation of the measured main steam pressure PV based on the setmain steampressure SV, thatis, an amplitude andacycle centered on the set main steam pressure SV (an interval of timing when the measured main steam pressure PV intersects with the set main steam pressure S). A state where the main steam pressure (the measured main steam pressure PV) is optimum basically specifies a state where the amplitude is small and the cycle is short as illustrated in the middle stage of FIG. 4. Note that a state where the cycle is long means that a state where the measured main steam pressure PV is apart from the set main steam pressure SV continues for a long time as illustrated in the lower stage of FIG. 4.

[0035]

As described above, for example, if the fuel charging amount

is determined by using the fuel function FX that is obtained in the

condition in which the state of the boiler 2, the fuel property,

and the other factors are maintained, the difference between the

measured main steam pressure PV and the set main steam pressure SV

is hardly generated. In fact, for example, as illustrated in the

middle stage of FIG. 4, the measured main steam pressure PV

oscillates with a small amplitude centered on the set main steam

pressure SV. However, the pressure difference (or the deviation)

between the measured main steam pressure PV and the set main steam

pressure SV may be generated with the state transition of the boiler

2, or the change in the fuel property and the other factors. In

the present embodiment, this deviation is measured; timing when to

become a state where the measured main steam pressure PV is optimum,

that is, when to become a state where values of the amplitude and

the cycle are smallis detected; and a correction factor with respect

to the fuel function FX(in the present embodiment, the fuel

correction factor K with respect to the initial value/fine

adjustment function FXAI) is calculated on the basis of the state

at that time.

[0036] FIG. 2 is a view illustrating an outline of a configuration

example of the reference curve correcting unit 12 according to the

present embodiment. For example, the reference curve correcting

unit 12 further includes, as its components, respective units such

as a deviation determining unit 121, a cycle determining unit 122,

an amplitude determining unit 123, a reference curve correction

determining unit 124, or a reference curve correction factor output

unit 125, which are implemented by hardware or software. Further,

the reference curve correcting unit 12 has respective data such as

a cycle history 126, an amplitude history 127, optimum value

information 128, or a reference curve correction function VFX, each

of which is implemented as a file or a table recorded in the memory

or the HDD.

[0037]

The measured main steam pressure PV and the set main steam

pressure SV inputted into the reference curve correcting unit 12

are firstinputtedinto the deviation determiningunit121, andtheir

difference (or deviation) is calculated. The calculated difference

is inputted into each of the cycle determining unit 122 and the

amplitude determining unit 123, and a cycle and an amplitude of the

variation are respectively calculated as information

characterizing behavior of the measured main steam pressure PV.

Note that, as described above, the behavior of the measured main

steam pressure PV is not constant, but varies from moment to moment.

Therefore, the cycle and the amplitude are to be calculated as a

moving average for a long time (for example, for 30 minutes). For

this reason, information on the calculated cycle and the calculated

amplitude is respectively recorded in the memory or the HDD as the

cycle history 126 and the amplitude history 127.

[0038]

Values of the calculated cycle and the calculated amplitude are inputted into the reference curve correction determining unit

124. The reference curve correction determining unit 124

determines whether each of the values of the cycle and the amplitude

is an optimum value (including a suitable value within a certain

range, which is equivalent to this) or not. Information related

to the optimum value is recorded in the memory or the HDD as the

optimum value information 128, for example. Then, in a case where

it is determined that each of the cycle and the amplitude is in an

optimum state, a value of the reference curve correction function

VFX, which is set as a variable function, is moved until any of them

falls outside the corresponding optimum state.

[0039]

On the basis of this reference curve correction function VFX,

the reference curve correction factor output unit 125 acquires and

outputs the reference curve correction factor KP corresponding to

the load demand MWD. This reference curve correction factor KP is

multiplied by the initial value/fine adjustment function FXAI,

thereby correcting the initialvalue/fine adjustment function FXAI.

[0040]

<Correction Processing for Initial Value/Fine Adjustment

Function FXAI>

FIG. 3 is a flow diagram illustrating an example of a flow

of processing to correct the initial value/fine adjustment function

according to the present embodiment. Here, the flow of processing

until the reference curve correction function VFX is set in the

reference curve correction determining unit 124 of the reference

curve correcting unit 12 is illustrated in FIG. 3. Thereafter, the

reference curve correction factor output unit 125 of the reference

curve correcting unit 12 acquires and outputs the reference curve

correction factor KP corresponding to the load demand MWD on the

basis of the reference curve correction function VFX thus set.

[0041]

In the reference curve correcting unit 12, the deviation

determining unit 121 first acquires the set main steam pressure SV

(SO1). As illustrated in FIG. 1, the set main steam pressure SV

may be set in advance inside the system as a fixed number, or may

be acquired from the boiler 2 or the like as an external input. The

deviation determiningunit 121then acquires the measuredmain steam

pressure PV transmitted from the main steam pressure transmitter

PX (S02). The processingorder describedabove ismerely one example,

and the processing may be executed in the inverse order, or may be

executed in parallel. When the set main steam pressure SV and the

measured main steam pressure PV are acquired, deviation processing

to find a difference between them is executed (S03). The deviation

determining unit 121 inputs information on the calculated

difference into each of the cycle determining unit 122 and the

amplitude determining unit 123. Then, the deviation determining

unit121causes the processingflow toreturn to Step SOlandcontinue

the same processing.

[0042]

The cycle determining unit 122 measures, on the basis of the

information on the difference of the main steam pressure acquired

from the deviation determining unit 121, a cycle of variation in

the measured main steam pressure PV based on the set main steam

pressure SV (S11). For example, timingwhen a sign of the difference

is inverted is grasped on the basis of history information on past

differences accumulated in the memory or the like (not illustrated

in the drawings), and its time interval is set as the cycle. As

described above, the behavior of the measured main steam pressure

PV is not constant, but varies from moment to moment. Therefore,

the cycle is calculated as a moving average based on a past history

for a long time (for example, for 30 minutes). Then, the cycle

determiningunit 122 determines whether the measured cycle is normal

or not (for example, whether it is an abnormal value such as a minus value or not) (S12). In a case where it is determined that the measured cycle is not normal (for example, it is the abnormal value)

(S12: N), the cycle determining unit 122 causes the processing flow

to return to Step Sl and continue the process for cycle measurement.

[0043]

Further, the amplitude determining unit 123 similarly

measures, on the basis of the information on the difference of the

main steam pressure acquired from the deviation determining unit

121, an amplitude of the variation in the measured main steam

pressure PV based on the set main steam pressure SV (S21). For

example, an absolute value of the difference is grasped as the

amplitude. The amplitude is also calculated as a moving average

of past history information for a long time (for example, for 30

minutes). The amplitude determining unit 123 then determines

whether the measured amplitude is normal or not (S22). In a case

where it is determined that the measured amplitude is not normal

(S22: N), the amplitude determining unit 123 causes the processing

flow to return to Step S21 and continue the process for amplitude

measurement.

[0044]

In a case where it is determined that the values of both of

the cycle and the amplitude are normal (S12: Y, and S22: Y), the

values of the calculated cycle and the calculated amplitude are

inputted into the reference curve correction determining unit 124.

The reference curve correction determining unit 124 acquires

transition of the cycle in a past fixed time range (for example,

for five minutes) (S31), and determines whether each cycle falls

within a predetermined range or not (S32). In a case where it is

determined that any cycle does not fall within the predetermined

range (S32: N), the reference curve correction determining unit 124

does not execute anything or terminates the correction processing

in a case where the correction processing for the reference curve correction function VFX has already been executed (S38). Herewith, the reference curve correction factor output unit 125 in the latter stage acquires and outputs the reference curve correction factor

KP on the basis of the reference curve correction function VFX at

this point.

[0045]

On the other hand, in a case where it is determined that the

cycle in the past fixed time range falls within the predetermined

range (S32: Y), the reference curve correction determining unit 124

determines whether each of the measured cycle and the measured

amplitude is the minimum value in the corresponding past history

of variation so far or not (S33). Information on the minimum value

so far may be recorded in the optimum value information 128, for

example. Note that the reference curve correction determining unit

124 determines whether the cycle is within the predetermined range

at Step S32 and is the minimum value or not. In a case where it

is determined that at least one of the cycle or the amplitude is

not the corresponding minimum value (S33: N), the reference curve

correction determining unit 124 does not execute anything or

terminates the correction processing in a case where the correction

processing for the reference curve correction function VFX has

already been executed (S38).

[0046]

On the other hand, in a case where it is determined that each

of the measured cycle and amplitude is the corresponding minimum

value (S33: Y), the reference curve correction determining unit 124

acquires, from the optimum value information 128, information on

the cycle andthe amplitude relatedto the optimumvalue so far (S34),

and determines, on the basis of comparison with this, whether a

combination of the measured cycle and the measured amplitude is an

optimum value or not (S35). As a method of determining whether any

of them is an optimum value, an appropriate method can be used such that a case where a value of the amplitude falls within a predetermined range and a cycle is smaller is determined to be optimum, for example. In a case where it is determined that the combination of the measured cycle and the measured amplitude is not optimum value (S35: N), the reference curve correction determining unit 124 does not execute anything or terminates the correction processing in a case where the correction processing for the reference curve correction function VFX has already been executed

(S38).

[0047]

On the other hand, in a case where it is determined that the

combination of the measured cycle and the measured amplitude is the

optimum value (S35: Y), the reference curve correction determining

unit 124 updates the content of the optimum value information 128

on the basis of this combination (S36), and starts the correction

processing for the reference curve correction function VFX (S37).

The reference curve correction function VFX is set as a variable

function that defines a curved line of a correspondence relation

between the loaddemandMWD andthe reference curve correction factor

KP, which is the correction factor with respect to the initial

value/fine adjustment function FXAI, and the initial value/fine

adjustment function FXAI is corrected by moving this curved line

by a predetermined amount. This correction is continued until any

of the measured cycle and the measured amplitude falls outside the

corresponding optimum state, for example. Note that such a

correcting method is merely one example. For example, a method of

correcting the reference curve correction function VFX (or the

initial value/fine adjustment function FXAI) by using another index

such as the boiler input command value BID in a control state when

the combination of the measured cycle and the measured amplitude

is the optimum value may be used.

[0048]

As explained above, according to the boiler combustion

control system 1 of the first embodiment of the present invention,

deviation of the variation in the measured main steam pressure PV

with respect to the set main steam pressure SV is measured as the

cycle and the amplitude, and timing when each of the cycle and the

amplitude is in the optimum state is specified on the basis of their

transition for a long time. Then, the reference curve correction

factor KP for correcting the fuel function FX (specifically, the

initial value/fine adjustment function FXAI in the present

embodiment) on the basis of a state where each of the cycle and the

amplitude is optimum is outputted. Namely, it is possible to

substantially revise small deviation generated in the fuel function

FX autonomously and in a self-contained manner in real time.

[0049]

(Second Embodiment)

Next, a second embodiment will be described. Note that

hereinafter, explanation for components that overlap with those in

the embodiment described above will be omitted in principle.

[0050]

In the present embodiment, aboiler combustion controlsystem

that can be applied to a supercritical pressure once-through boiler

or an ultrasupercritical pressure once-through boiler will be

described. A fuel charging amount or a water supply amount in the

supercritical pressure once-through boiler or the

ultrasupercritical pressure once-through boiler depends on a main

steam pressure and a water-fuel ratio. The water-fuel ratio is a

value defined by a weight ratio between the water supply amount and

fuel to a boiler. This water-fuel ratio is controlled by a

water-fuel ratio master that is provided outside the boiler

combustion control system. The water-fuel ratio master adjusts the

fuel charging amount while executing integral processing based on

heat quantity (or a main steam pressure). However, conventionally, it was impossible to stabilize combustion because the fuel charging amount could not be controlled appropriately.

[0051]

Therefore, in the present embodiment, it is an object to

provide a boiler combustion control system capable of appropriately

controlling the fuel charging amount in the supercritical pressure

once-through boiler or the ultrasupercritical pressure

once-through boiler.

[0052]

FIG. 5 is a view illustrating an outline of a configuration

example ofaboiler combustion controlsystemaccording to the second

embodiment of the present invention. A configuration other than

that of a boiler combustion control system 201 according to the

present embodiment is a configuration in which a water supply master

208, a water-fuel ratio master 209, and an adder 210 are added to

the configuration illustrated in FIG. 1.

[0053]

The water-fuel ratio master 209 adjusts boiler input command

values BID, BID' (or a load demand MWD') and a water supply amount

so that a water-fuel ratio defined by a weight ratio between water

(liquid) and fuel, which are to be supplied to a boiler 2, becomes

a predetermined value (or falls within a predetermined range). On

thebasis ofthese controls, the water-fuelratiomaster 209 controls

the water supply amount, fluid temperature in a pipe, and surface

temperature of the pipe. The water-fuel ratio master 209 generates

a water-fuel ratio master signal on the basis of information on a

measurement value of a main steam pressure PV measured by a pressure

meter (not illustratedin the drawings) and the water supply amount,

and outputs the generated water-fuel ratio master signal. The

water-fuel ratio master signal is a signal regarding an increase

or a decrease in the fuelcharging amount. In case of fuel shortage,

the water-fuelratio master signalbecomes a plus signal to increase the fuel charging amount. In case of fuel excess, the water-fuel ratio master signal becomes a minus signal to decrease the fuel charging amount.

[0054]

The water supply master 208 adjusts a water supply amount

to the boiler 2 on the basis of a load demand MWD, a setting value

for the water-fuel ratio, and the like. The adder 210 adjusts the

boiler input command value BID outputted from a fuel charging amount

arithmetic unit 7 on the basis of the water-fuel ratio master signal

outputted from the water-fuel ratio master 209.

[0055]

Thus, the water supply amount and the fuel charging amount

are adjusted by the respective units provided around the boiler 2

on the basis of the setting value for the water-fuel ratio. In the

present embodiment, the boiler combustion control system 201 also

controls the fuel charging amount further. As illustrated in FIG.

5, the boiler combustion control system 201 has a configuration in

which an adder 215 is added to the boiler combustion control system

1illustratedinFIG.1. The adder215is connectedtothe water-fuel

ratio master 209, and adjusts a value of the boiler input command

value BID' (or the loaddemandMWD') after feedback adjustment, which

is outputted from an adder 5, on the basis of the water-fuel ratio

master signal outputted from the water-fuel ratio master 209.

[0056]

In a case where the water-fuel ratio master signal is a plus

signal, the adder 215 executes signal processing to add a

predetermined value to the boiler input command value BID'. In a

case where the water-fuel ratio master signal is a minus signal,

the adder 215 executes signalprocessing to subtract apredetermined

value from the boiler input command value BID'. The adder 215 then

outputs the boiler input command value BID' (or the load demand MWD')

after the signal processing to a divider 11.

[0057] The divider 11 calculates a ratio between the load demand

MWD and the boiler input command value BID' after the signal

processing, and outputs the ratio to a fuel correction factor

arithmetic unit 14. The fuel correction factor arithmetic unit 14

calculate, by using the ratio outputted from the divider 11 as an

input, a fuel correction factor K based on the boiler input command

value BID' after the signalprocessingby self-learning, and outputs

it. Note that processes in a reference curve correcting unit 12

and a multiplier 13 are similar to those according to the first

embodiment.

[0058]

Amultiplier 6 multiplies the load demand MWD' (or the boiler

input command value BID') by the fuel correction factor K based on

the control of the water-fuel ratio master 209. By using a load

demand MWD" (or a boiler input command value BID") after this

correction as an input, the fuel charging amount arithmetic unit

7 converts this MWD" into the boiler input command value BID by means

of the fuel function FX, and outputs this BID to the adder 210. The

processing in the adder 210 has already been described.

[0059]

According to the present embodiment, the following effects

can be obtainedin addition to the effects according to the foregoing

embodiment. According to the present embodiment, the fuel

correction factor arithmetic unit 14 calculates the fuel correction

factor K on the basis of the ratio between the load demand MWD before

the feedback correction andthe load demandMWD' (or the boiler input

commandvalue BID') after the feedback correction, whichis adjusted

on the basis of the water-fuel ratio. According to this

configuration, it is possible to calculate the fuel correction

factor K on the basis of the control of the water-fuel ratio master

209 appropriately. Therefore, it is possible to provide the boiler combustion control system or the like capable of appropriately controlling the fuel charging amount even in the supercritical pressure once-through boiler or the ultrasupercritical pressure once-through boiler.

[0060] Further, according to this configuration, it is possible to

determine an influence of the water-fuel ratio master 209 by

calculation. Therefore, it becomes possible to calculate weight

of the control by the water-fuel ratio master 209 with respect to

the boiler input command value BID, and this makes it possible to

stabilize combustion.

[0061]

As described above, the invention made by inventors of the

present application has been described specifically on the basis

of the embodiment. However, the present invention is not limited

to the embodiment described above, and it goes without saying that

the present invention may be modified into various forms without

departing from the substance thereof. For example, the embodiment

described above has been explained in detail for explaining the

present invention clearly. The present invention is not

necessarily limited to one that includes all configurations that

have been explained. Further, a part of the configuration of each

ofthe embodiments canbe addedwiththe other configuration, deleted

or replaced thereby.

[0062]

Further, a part or all of the respective configuration

described above, the functions, processing units, and processing

means may be realized by hardware that is designed by an integrated

circuit, for example. Further, the respective configuration

described above and the functions may be realized by software so

that a processor interprets programs realizing the respective

functions and execute the interpreted programs. Information on programs, tables, and files, which realize the respective functions, can be placed in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

[0063] Further, in each of the drawings described above, control

lines and information lines are illustrated so long as they are

thought to be necessary for explanation. All of the control lines

and the information lines are not necessarily illustrated on the

implementation. In fact, it may be considered that almost all of

the components are connected to each other.

INDUSTRIAL APPLICABILITY

[0064]

The present invention is usable for a boiler combustion

control system and a boiler combustion control method that

determines a fuel charging amount to a boiler on the basis of a load

demand of the boiler.

REFERENCE SINGS LIST

[0065]

1, 201 ... boiler combustion control system, 2 ... boiler, 3 ... steam

turbine, 4 ... PID control unit, 5 ... adder, 6 ... multiplier, 7 ... fuel

charging amount arithmetic unit, 11 ... divider, 12 ... reference curve

correcting unit, 13 ... multiplier, 14 ... fuel correction factor

arithmetic unit, 121 ... deviation determining unit, 122 ... cycle

determining unit, 123 ... amplitude determining unit, 124 ... reference

curve correction determining unit, 125 ... reference curve correction

factor output unit, 126 ... cycle history, 127 ... amplitude history,

128 ... optimum value information, 215 ... adder, SV ... set main steam

pressure, PV ... measured main steam pressure, PX ... main steam pressure

transmitter, MWD, MWD', MWD" ... load demand , BID, BID', BID" ... boiler

input command value, K ... fuel correction factor, KP ... reference curve

correction factor, FX ... fuel function, FXAI ... initial value/fine adjustment function, VFX ... reference curve correction function

Claims

1. Aboiler combustion controlsystemconfigured to: supply fuel

related to a fuel charging amount to a boiler to the boiler, the

fuel charging amount being calculated on a basis of a predetermined

fuel function for a load demand; find a feedback correction amount

on a basis of a measured main steam pressure and a set main steam

pressure, the measured main steam pressure being a main steam

pressure of the boiler that is measured, the set main steam pressure

being a main steam pressure for the boiler that is set in advance;

and output a fuel correction factor for correcting the load demand

or the fuel charging amount to a plant after feedback correction,

the plant correcting the load demand or the fuel charging amount

on a basis of the feedback correction amount, the boiler combustion

control system comprising:

a fuel correction factor arithmetic unit configured to

calculate the fuel correction factor on a basis of a ratio of the

load demandbefore and after the feedback correction, and an initial

value/fine adjustment function that defines an initial value of a

relationship between the load demand and the fuel charging amount

with respect to the boiler; and

a reference curve correcting unit configured to output a

reference curve correction factor for correcting the initial

value/fine adjustment function,

wherein the reference curve correcting unit includes:

a deviation determining unit configured to calculate a

deviation between the measured main steam pressure and the set main

steam pressure;

a cycle determining unit configured to acquire and record

a cycle related to variation in the deviation;

an amplitude determining unit configured to acquire and

record amplitude related to the variation in the deviation; a reference curve correction factor output unit configured to calculate the reference curve correction factor on a basis of a predetermined reference curve correction function and output the calculated reference curve correction factor; and a reference curve correction determining unit configured to determine whether a combination of the cycle and the amplitude satisfies a predetermined condition or not, the reference curve correction determining unit configured to correct the reference curve correction function on abasis ofacontrolstate for the boiler in a case where the reference curve correction determining unit determines that the combination satisfies the predetermined condition.

2. The boiler combustion control system according to claim 1,

wherein the predetermined condition is that the amplitude

is within a predetermined range and

the cycle is smallest in a history of a past fixed time range.

3. The boiler combustion control system according to claim 1,

wherein the cycle determining unit and the amplitude

determining unit respectively acquire the cycle and the amplitude

as moving averages thereof in a past fixed time.

4. The boiler combustion control system according to claim 1,

wherein the reference curve correction function is set as

a variable function, and

wherein the reference curve correction determining unit is

configured to correct the reference curve correction function by

moving the reference curve correction function while the

combination of the cycle and the amplitude satisfies the

predetermined condition.

5. The boiler combustion control system according to claim 1,

wherein the fuel correction factor arithmetic unit is

configured to calculate the fuel correction factor on a basis of

a ration between the load demand before the feedback correction and

the load demand after the feedback correction, the load demand after

the feedback correction being adjusted on a basis of a water-fuel

ratio defined by a weight ratio between water and fuel to be supplied

to the boiler.

6. A boiler combustion control method in a boiler combustion

control system configured to: supply fuel related to a fuel charging

amount to a boiler to the boiler, the fuel charging amount being

calculated on a basis of a predetermined fuel function for a load

demand; find a feedback correction amount on a basis of a measured

main steam pressure and a set main steam pressure, the measured main

steam pressure being a main steam pressure of the boiler that is

measured, the set main steam pressure being a main steam pressure

for the boiler that is set in advance; and output a fuel correction

factor for correcting the load demand or the fuel charging amount

to a plant after feedback correction, the plant correcting the load

demand or the fuel charging amount on a basis of the feedback

correction amount, the boiler combustion controlmethod comprising:

a fuel correction factor arithmetic step of calculating the

fuel correction factor on a basis of a ratio of the load demand before

and after the feedback correction, and an initial value/fine

adjustment function that defines an initial value of a relationship

between the load demand and the fuel charging amount with respect

to the boiler; and

a reference curve correcting step of outputting a reference

curve correction factor for correcting the initial value/fine

adjustment function,

wherein the reference curve correcting step includes: a deviation determining step of calculating a deviation between the measured main steam pressure and the set main steam pressure; a cycle determining step of acquiring and recording a cycle related to variation in the deviation; an amplitude determining step of acquiring and recording amplitude related to the variation in the deviation; a reference curve correction factor output step of calculating the reference curve correction factor on a basis of a predetermined reference curve correction function and outputting the calculated reference curve correction factor; and a reference curve correction determining step of determining whether a combination of the cycle and the amplitude satisfies a predetermined condition or not, the reference curve correction function being corrected on a basis of a control state for the boiler in a case where it is determined that the combination satisfies the predetermined condition.

7. The boiler combustion control method according to claim 6,

further comprising:

before the fuel correction factor arithmetic step, a step

of adjusting the load demand after the feedback correction on a basis

of a water-fuel ratio defined by a weight ratio between water and

fuel to be supplied to the boiler, and calculating a ratio between

the load demand before the feedback correction and the load demand

after the feedback correction and adjustment,

wherein in the fuel correction factor arithmetic step, the

fuel correction factor is calculated on a basis of the ratio

calculated on a basis of the load demand after the feedback

correction and the adjustment.