CN102620774B - Method for calibrating secondary air volume of coal-fired boiler on line - Google Patents
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Abstract
A method for calibrating a secondary air volume of a coal-fired boiler on line comprises the following steps: performing an adjustment experiment on each secondary air volume in turns under a certain stable load point, and establishing a multivariate linear equation set through a balance relationship between experimental data and a total air volume of the boiler; obtaining a flow coefficient of each secondary air volume measuring device by solving the equation set; and during measurement of an actual air volume, obtaining an accurate air amount through the calculated flow coefficient, thus achieving the online calibration of the secondary air volume. According to the online calibration method, the shutdown of the boiler is not required and the secondary air volume adjust experiment can be performed in a stable load section in the running process of the boiler at any time, so that the normal operation of the boiler is basically not affected and the loss caused by the shutdown and the startup of the boiler can be avoided; additional measuring equipment is not required to be installed inside and detached from an air duct of the boiler; the calibration process is simple; equipment and human resources are saved; and the calibration cost is far lower than that in the conventional calibration method.
Description
Technical field
The present invention relates to a kind ofly can under coal-burning boiler normal operating condition, to its secondary air flow, carry out the method for accurate calibration, belong to boiler technology field.
Background technology
In boiler technology, coal-air ratio has determined the efficiency of coal-burning boiler to a great extent.When air quantity is bigger than normal, the boiler exhaust gas loss boiler efficiency that causes bigger than normal reduces; When air quantity is less than normal, loss that boiler the is imperfect combustion boiler efficiency that also can cause bigger than normal reduces, and coal-burning boiler exists an optimum coal-air ratio.In engineering, adopt excess air coefficient to describe this concept, the physical significance of excess air coefficient is to send into the actual dry air amount of boiler furnace with the ratio of sending into the needed theoretical air requirement of coal perfect combustion of burner hearth.Excess air coefficient exists definite funtcional relationship with flue gas oxygen content, boiler is respectively installed one or more zirconia oxygen analyzer and is measured Oxygen Amount in Flue Gas after economizer in the flue of air preheater front left right side at present, and regulate boiler secondary air quantity that Oxygen Amount in Flue Gas is maintained near certain value by oxygen content control system, and then guarantee that excess air coefficient is near optimal value.
But such control system only can guarantee that wind coal total amount proportioning reaches optimum, in fact, in whole combustion process, wind is sent into stage by stage: the Main Function of a wind is the burning of carrying coal particle and supporting fugitive constituent in coal; The Main Function of Secondary Air is the burning of supporting coke grain in coal; The Main Function of burnt wind is guarantee coal after-flame and oxidizing atmosphere is provided.In principle, burnt wind is the part in Secondary Air, and its object of separating is to reduce the combustion intensity of boiler main combustion zone and oxygen concentration to reduce NO
xgeneration.A large amount of theory and experimental studies prove, whether each stage air quantity dispensing of burning rationally can affect boiler NO to a great extent
xdischarge capacity and unburned carbon in flue dust, and then Boiler Economical Operation, the feature of environmental protection are exerted an influence.
The large bellows structure of the many employings of large coal-fired boiler at present, the Secondary Air of each grate firing burner and burnt wind have separately independently control gear and measurement mechanism, can implement accurately to control to the air distribution amount in each stage in combustion process in theory, the accuracy of its control depends primarily on the accuracy of air measuring.But on-the-spot often appearance measures inaccurately because of secondary air flow, causes air flow rate proportioning deterioration in accuracy and then affects the situation of boiler combustion.As certain air measuring value obviously departs from normal value, affect the total blast volume substantial deviation design load that drop into automatically in this loop, every air measuring value obtains after suing for peace and be not inconsistent etc. with practical operation situation.
Cause the reason of air measuring error to comprise: (1) secondary air flow measurement mechanism is nonstandardized technique measurement mechanism, and when its accuracy of measurement depends on boiler cold-state, the accuracy of on-site proving, occurs error in calibration process; (2) Secondary Air temperature surpasses 300 ℃ during boiler operatiopn, and apparatus for measuring air quantity produces thermal deformation, or after boiler long-time running, apparatus for measuring air quantity produces distortion, causes coefficient of flow to change; (3) Secondary Air pipeline cross section is rectangle and thicker, and before and after measurement mechanism installation site, straight length can not meet measurement requirement, increases measuring error; (4) flying dust in boiler smoke is deposited in boiler air preheater and is carried by Secondary Air, causes apparatus for measuring air quantity to produce wearing and tearing or local obstruction, causes larger measuring error.
While there is above situation, need to carry out air flow calibration experiment.Tradition calibration experiment can only carry out under boiler shutdown state, pitot tube group or bourdon's tube group are installed in air channel by experimenter, start boiler fan and make to maintain in air channel nominal air delivery, after adopting installation pitot tube group or bourdon's tube group to measure mean wind speed, calculate air quantity as normal flow, remove to calibrate the on-the-spot coefficient of flow that air measuring instrument is installed, make both show that air quantity is consistent.Because on-the-spot straight length deficiency, pitot tube group or the installation of bourdon's tube group exist the reasons such as error, wind flow is inhomogeneous, the hot operating mode leeward of cold conditions flow characteristics there are differences, the accuracy that the method is demarcated neither be very high.And work on the spot narrow field, inclement condition, install and remove wind speed measuring device and bother very much, and experimental period is grown, demarcates costly.
Summary of the invention
The object of the present invention is to provide a kind of coal-burning boiler secondary air flow online calibration method, when guaranteeing calibration accuracy, shorten experimental period, reduce demarcation expense.
The alleged problem of the present invention realizes with following technical proposals:
A kind of coal-burning boiler secondary air flow online calibration method, described method is to carry out successively the regulation experiment of each secondary air flow under a certain steady load point of boiler, record experimental data and utilize the equilibrium relation of boiler total blast volume to set up multi head linear equation group, by solving this system of equations, obtain the coefficient of flow of each secondary air flow measurement mechanism, when measuring, actual air volume utilize the coefficient of flow calculating can obtain accurate air quantity, thereby realize the on-line calibration to secondary air flow, concrete demarcating steps is as follows:
A. under a certain steady load point, carry out successively each secondary air flow regulation experiment, and the experimental data that collates the minutes;
B. with following formula, represent the measured value of each secondary air flow measurement mechanism in each secondary air flow regulation experiment process
q s:
Wherein,
k cfor measurement mechanism coefficient of flow;
bfor measuring secondary air flow variable;
p dfor the distinguished and admirable differential pressure (KPa) of crossing measurement mechanism generation;
p actfor local atmospheric pressure (KPa);
p sfor wind static pressure (KPa) in pipeline;
tfor air temperature in pipeline (℃);
C. boiler total blast volume calculates
Adopt following formula to calculate the boiler total blast volume in each secondary air flow regulation experiment process
q a:
，
，
Wherein:
q agfor the dry air amount (Nm comprising in total blast volume
3/ s);
q h2Ofor comprising water vapour amount (Nm in total blast volume
3/ s);
sspecific humidity for air;
for relative air humidity (%); S is saturation specific humidity,
for excess air coefficient;
bfor the total coal amount of boiler (Kg/s);
q 0for unit mass coal combustion needs theoretical dry air amount (Nm
3/ Kg); O
2for Oxygen Amount in Flue Gas (%);
for greenhouse gas; C
arfor coal as received basis carbon content (%); H
arfor coal as received basis hydrogen richness (%); O
arfor coal as received basis oxygen content (%); N
arfor coal as received basis nitrogen content (%); S
arfor coal as received basis sulfur content (%);
q bfor boiler total amount of heat (MW); Q
arfor coal as received basis net calorific value (MJ/Kg);
q msfor boiler overheating steam flow (Kg/s);
q rsfor boiler reheated steam flow (Kg/s);
h msfor boiler overheating steam specific enthalpy (MJ/Kg);
h rsfor boiler reheated steam specific enthalpy (MJ/Kg);
h fwfor boiler feed water specific enthalpy (MJ/Kg);
h hsfor boiler reheater inlet steam specific enthalpy (MJ/Kg);
for boiler efficiency (%);
D. the foundation of total blast volume balance equation group and solving:
Utilize the equilibrium relation of boiler total blast volume, list the air balance equation that under same load point, original state and each secondary air flow regulation experiment obtain:
，
…
Wherein:
q a0,
q a1,
q a2,
q anfor original state, the 1st, 2 ... total blast volume (Nm in n secondary air flow regulation experiment process
3/ s);
b 10,
b 11,
b 12,
b 1nfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism 1 in n Secondary Air regulation experiment process;
b 20,
b 21,
b 22,
b 2nfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism 2 in n Secondary Air regulation experiment process;
b n0,
b n1,
b n2,
b nnfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism n in n Secondary Air regulation experiment process;
k c1,
k c2,
k cnbe the 1st, 2 ... n secondary air flow measurement mechanism coefficient of flow;
q fafor the total primary air flow (Nm of boiler
3/ s);
q lfor burner hearth inleakage (Nm
3/ s),
Solve the system of equations being formed by above equation, obtain the coefficient of flow of each secondary air flow measurement mechanism
k c1,
k c2,
k cn;
E. by the coefficient of flow calculating
k c1,
k c2,
k cncoefficient of flow as each secondary air flow measurement mechanism when actual air volume is measured, completes the demarcation of secondary air flow.
Above-mentioned coal-burning boiler secondary air flow online calibration method, in order to reduce stochastic error, can under a plurality of boiler loads working point, carry out secondary air flow regulation experiment, obtain the coefficient of flow of many group secondary air flow measurement mechanisms, and will organize the coefficient of flow of the mean value of coefficient of flow as each secondary air flow measurement mechanism when actual air volume is measured more.
The main source of error of scaling method of the present invention is the total blast volume error of calculation, and what total blast volume was had the greatest impact is oxygen content measurement error, when adopting portable oxygen amount meter representative point method to measure oxygen amount, air flow calibration relative error can be controlled at ± 2% in; Adopt that boiler is original demarcates the timing of rear oxidation zirconium oxygen amount through calibrating gas, relative error can be controlled at ± 5% in, scaling method stated accuracy of the present invention can meet on-the-spot air quantity and adjust requirement.In addition, primary air measuring error and burner hearth leak out and can secondary air flow do not demarcated and be exerted an influence.After demarcating, secondary air flow can be consistent with burning associated monitoring parameter display values such as boiler total blast volume, secondary air flow ratio, boiler load, Oxygen Amount in Flue Gas simultaneously, favourable to raising boiler operatiopn status monitoring and procedure parameter level of control.
The present invention is online calibration method, do not need blowing out, secondary air flow regulation experiment can carry out in load section stable in boiler running process at any time, substantially not affecting boiler normally moves, the loss that can avoid blowing out and startup to bring, and scaling method of the present invention need to not install and dismantle extra measuring equipment in boiler air duct, and calibration process is simple, saving equipment and human resources, calibration cost is far smaller than traditional scaling method.
In literary composition of the present invention, each symbol is:
q smeasured value (Nm for secondary air flow measurement mechanism
3/ s);
k cfor measurement mechanism coefficient of flow;
p dfor the distinguished and admirable differential pressure (KPa) of crossing measurement mechanism generation;
p actfor local atmospheric pressure (KPa);
p sfor wind static pressure (KPa) in pipeline;
tfor air temperature in pipeline (℃);
q afor boiler total blast volume;
q agfor the dry air amount (Nm comprising in total blast volume
3/ s);
q h2Ofor comprising water vapour amount (Nm in total blast volume
3/ s);
sspecific humidity for air;
for relative air humidity (%); S is saturation specific humidity;
for excess air coefficient;
bfor the total coal amount of boiler (Kg/s);
q 0for unit mass coal combustion needs theoretical dry air amount (Nm
3/ Kg); O
2for Oxygen Amount in Flue Gas (%);
for greenhouse gas; C
arfor coal as received basis carbon content (%); H
arfor coal as received basis hydrogen richness (%); O
arfor coal as received basis oxygen content (%); N
arfor coal as received basis nitrogen content (%); S
arfor coal as received basis sulfur content (%);
q bfor boiler total amount of heat (MW); Q
arfor coal as received basis net calorific value (MJ/Kg);
q msfor boiler overheating steam flow (Kg/s);
q rsfor boiler reheated steam flow (Kg/s);
h msfor boiler overheating steam specific enthalpy (MJ/Kg);
h rsfor boiler reheated steam specific enthalpy (MJ/Kg);
h fwfor boiler feed water specific enthalpy (MJ/Kg);
h hsfor boiler reheater inlet steam specific enthalpy (MJ/Kg);
for boiler efficiency (%);
q a0,
q a1,
q a2,
q anfor original state, the 1st, 2 ... total blast volume (Nm in n secondary air flow regulation experiment process
3/ s);
bfor measuring secondary air flow variable;
b 10,
b 11,
b 12,
b 1nfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism 1 in n Secondary Air regulation experiment process;
b 20,
b 21,
b 22,
b 2nfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism 2 in n Secondary Air regulation experiment process;
b n0,
b n1,
b n2,
b nnfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism n in n Secondary Air regulation experiment process;
k c1,
k c2,
k cnbe the 1st, 2 ... n secondary air flow measurement mechanism coefficient of flow;
q fafor the total primary air flow (Nm of boiler
3/ s);
q s1for secondary air flow 1(Nm
3/ s);
q s2for secondary air flow 2(Nm
3/ s);
q snfor secondary air flow n(Nm
3/ s);
q lfor burner hearth inleakage (Nm
3/ s).
Embodiment
Technical scheme of the present invention:
(1) calibrating parameters explanation
Boiler Air Measuring device comprises airfoil type air volume meter and double-venturi pipe air volume meter, and its measure equation is identical, for:
Wherein:
q sfor measuring air quantity (Nm
3/ s);
k cfor measurement mechanism coefficient of flow;
p dfor the distinguished and admirable differential pressure (KPa) of crossing measurement mechanism generation;
p actfor local atmospheric pressure (KPa);
p sfor wind static pressure (KPa) in pipeline;
tfor air temperature in pipeline (℃).In measure equation, coefficient of flow
k cdemarcate inaccurate or change and cause air measuring to have the principal element of systematic error by being, the key that secondary air flow is demarcated is to determine that each secondary air flow measurement mechanism is correct
k c.
(2) boiler total blast volume calculates
Boiler total blast volume adopts following formula to calculate:
Wherein:
q afor boiler total blast volume (Nm
3/ s);
q agfor the dry air amount (Nm comprising in total blast volume
3/ s);
q h2Ofor comprising water vapour amount (Nm in total blast volume
3/ s);
sspecific humidity for air.
Air specific humidity adopts following formula to calculate:
Wherein:
for relative air humidity (%); S is saturation specific humidity, can in conjunction with properties of water and steam, be calculated by current air themperature and atmospheric pressure.
Dry air amount adopts following formula to calculate:
Wherein:
for excess air coefficient;
bfor the total coal amount of boiler (Kg/s);
q 0for unit mass coal combustion needs theoretical dry air amount (Nm
3/ Kg).
Excess air coefficient adopts following formula to calculate:
Wherein: O
2for Oxygen Amount in Flue Gas (%);
for greenhouse gas, adopt following formula to calculate:
1Kg coal combustion needs theoretical dry air amount computing formula to be:
In formula 6,7: C
arfor coal as received basis carbon content (%); H
arfor coal as received basis hydrogen richness (%); O
arfor coal as received basis oxygen content (%); N
arfor coal as received basis nitrogen content (%); S
arfor coal as received basis sulfur content (%).
Total coal-supplying amount adopts following formula to calculate:
Wherein:
q bfor boiler total amount of heat (MW); Q
arfor coal as received basis net calorific value (MJ/Kg).
Boiler total amount of heat adopts following formula to calculate:
Wherein:
q msfor boiler overheating steam flow (Kg/s);
q rsfor boiler reheated steam flow (Kg/s);
h msfor boiler overheating steam specific enthalpy (MJ/Kg);
h rsfor boiler reheated steam specific enthalpy (MJ/Kg);
h fwfor boiler feed water specific enthalpy (MJ/Kg);
h hsfor boiler reheater inlet steam specific enthalpy (MJ/Kg), above specific enthalpy all can adopt temperature, the pressure of steam to utilize properties of water and steam formula to calculate;
for boiler efficiency (%), heating power experimental data while adopting boiler acceptance.
(3) total blast volume balance equation is set up vertical and is solved
For coal-burning boiler, total blast volume by total primary air flow, a plurality of secondary air flow, a plurality ofly burn air quantity and burner hearth inleakage sum forms.Because burnt wind is in essence with Secondary Air indifference, and both measurement mechanisms are also identical, for convenience, burnt wind are equal to Secondary Air.Boiler has n secondary air flow, and boiler total blast volume is like this:
（10）
Wherein:
q fafor the total primary air flow (Nm of boiler
3/ s);
q s1for secondary air flow 1(Nm
3/ s);
q s2for secondary air flow 2(Nm
3/ s);
q snfor secondary air flow n(Nm
3/ s);
q lfor burner hearth inleakage (Nm
3/ s).
In secondary air flow computing formula 1, order:
Claim
bfor measuring secondary air flow variable.
Boiler, under definite load operation point, maintains coal-supplying amount and primary air flow stable constant to guarantee boiler load and main steam pressure, maintains furnace pressure stable constant to guarantee burner hearth inleakage.At this moment according to air balance principle, there is the multi head linear equation of a benchmark.
Adjust respective execution mechanisms to change some secondary air flows, when air quantity reach stable after, correlation parameter can obtain another multi head linear equation.All n secondary air flow topworks all adjusted, can obtain n multi head linear equation group:
…
Wherein:
q a0,
q a1,
q a2,
q anfor original state, the 1st, 2 ... total blast volume (Nm in n secondary air flow regulation experiment process
3/ s);
b 10,
b 11,
b 12,
b 1nfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism 1 in n Secondary Air regulation experiment process;
b 20,
b 21,
b 22,
b 2nfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism 2 in n Secondary Air regulation experiment process;
b n0,
b n1,
b n2,
b nnfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism n in n Secondary Air regulation experiment process;
k c1,
k c2,
k cnbe the 1st, 2 ... n secondary air flow measurement mechanism coefficient of flow.
In system of equations, there is n+2 known variables, be respectively:
q fa,
k c1,
k c2...,
k cn,
q l.But can find by observing, system of equations only has n+1 independence and freedom variable,
q fawith
q lsum forms an independence and freedom variable.Like this, there is unique solution in system of equations.After solving equation group, can obtain coefficient of flow and the total primary air flow of boiler and the burner hearth inleakage sum of each secondary air flow measurement mechanism.
(4) repeat experiment
As satisfy the requirements, can under a plurality of boiler loads working point, carry out secondary air flow regulation experiment, obtain coefficient of flow and the total primary air flow of boiler and the burner hearth inleakage sum of other many group secondary air flow measurement mechanisms.The method that employing is averaged can reduce stochastic error.
The invention process step
(1) Preparatory work of experiment.
Experiment need to be carried out under stable load, stable ature of coal and stable atmospheric environment, needs to guarantee that these conditions meet before experiment.Before experiment, need confirm or record following basic experimental conditions parameter, comprising: coal as received basis net calorific value Q
ar, carbon content C
ar, hydrogen richness H
ar, oxygen content O
ar, nitrogen content N
ar, sulfur content S
ar; Local atmospheric pressure
p act; Relative air humidity
; Environment temperature; Boiler efficiency
.
The signal non-fault of confirming to need in experimentation record, comprising: boiler main steam flow
q ms, reheated steam flow
q rs, main steam temperature and pressure, feed temperature and pressure, reheat steam temperature and pressure, reheater inlet steam temperature and pressure; The differential pressure of each secondary air flow measurement mechanism
p d; , static pressure
p s, temperature
t.
Adopt portable oxygen amount meter, according to the regulation of < < station boiler performance test code > > (GB10184-88), select representative point method to measure boiler smoke oxygen amount.Or after adopting calibrating gas to demarcate the zirconia oxygen analyzer of boiler erection, measure boiler smoke oxygen amount.
(2) secondary air flow regulation experiment.
In experimentation, need to keep boiler load, main steam pressure, primary air flow, furnace pressure to stablize.Specific targets are: main steam flow variation range is less than rated load ± 0.5%; Main steam temperature change be less than ± 2.5 ℃; Main steam pressure changes be less than ± 0.1MPa of dum boiler, be less than ± 0.15MPa of direct current cooker; Primary air flow displayed value change be less than ± 0.5%; Furnace pressure changes be less than ± 50Pa.Method of operating is: under a certain definite load, keep boiler load instruction definite value, main steam pressure definite value constant, boiler load-control pressurer system drops into automatically; Keep furnace pressure definite value constant, furnace pressure control system drops into automatically; Keep oxygen amount definite value constant, oxygen content control system drops into automatically; Primary air flow control system is cut to manually, and maintains in whole experimentation each topworks that controls primary air flow and be failure to actuate; Primary air pressure control system is cut to manually, keeps each topworks that controls primary air pressure to be failure to actuate.After parameters is stable, record original state experimental data.
Manually change the bias of a certain grate firing burner or a certain crosswind road Secondary Air plate washer opening control system, make its corresponding secondary air flow variable quantity reach the more than 30% of its nominal air delivery.At this moment boiler smoke oxygen amount has certain fluctuation, but oxygen amount automatic control system can be adjusted the action of each secondary air damper and finally makes oxygen amount return near definite value and stable; Furnace pressure also has certain fluctuation simultaneously, but also stable near furnace pressure control system effect lower hearth pressure also will return to definite value.After oxygen amount and furnace pressure are stable, record experimental data.
Cancel the biasing of this grate firing burner or this crosswind road secondary air damper aperture, manually change the biasing of other one deck burner or an other crosswind road Secondary Air plate washer aperture, after oxygen amount and furnace pressure are stable, record experimental data.Repeat this experimental procedure, until complete all secondary air flow measurement mechanisms the regulation experiment of corresponding secondary air flow baffle plate.
In order to improve precision, can repeat above-mentioned experimentation in the different load point of boiler, obtain extra many groups experimental data.
(3) analysis of experimental data is calculated.
The boiler total amount of heat of calculating under original state and each secondary air flow regulation experiment to formula 9 according to formula 2, and further calculate total blast volume.In same load operation point experiment, the difference of boiler total amount of heat should be very little.Can adopt the fiducial interval of fiducial probability 95% in mathematical statistics to carry out consistency check to it, have data to exceed fiducial interval and think that this group experimental data is invalid.
According to formula 11, calculate the measurement secondary air flow variable of each apparatus for measuring air quantity under original state and each secondary air flow regulation experiment.
Reference formula 12, to formula 15, is listed original state and the air balance equation that each secondary air flow regulation experiment obtains under same load point, forms a system of equations.Solve the unique solution that can obtain one group of each secondary air flow measurement mechanism coefficient of flow, total primary air flow and burner hearth inleakage sum.To there being the situation of the lower experimental data of many group different load points, a plurality of solutions of same apparatus for measuring air quantity coefficient of flow, total primary air flow and burner hearth inleakage sum are averaged, can reduce stochastic error impact.
Finally, according to each secondary air flow measurement mechanism coefficient of flow of result of calculation online modification, complete demarcation.
Claims (2)
1. a coal-burning boiler secondary air flow online calibration method, it is characterized in that, described method is to carry out successively the regulation experiment of each secondary air flow under a certain steady load point of boiler, record experimental data and utilize the equilibrium relation of boiler total blast volume to set up multi head linear equation group, by solving this system of equations, obtain the coefficient of flow of each secondary air flow measurement mechanism, when measuring, actual air volume utilize the coefficient of flow calculating can obtain accurate air quantity, thereby realize the on-line calibration to secondary air flow, concrete demarcating steps is as follows:
A. under a certain steady load point, carry out successively each secondary air flow regulation experiment, and the experimental data that collates the minutes;
B. with following formula, represent the measured value of each secondary air flow measurement mechanism in each secondary air flow regulation experiment process
q s:
Wherein,
k cfor measurement mechanism coefficient of flow;
bfor measuring secondary air flow variable;
p dfor the distinguished and admirable differential pressure (KPa) of crossing measurement mechanism generation;
p actfor local atmospheric pressure (KPa);
p sfor wind static pressure (KPa) in pipeline;
tfor air temperature in pipeline (℃);
C. boiler total blast volume calculates
Adopt following formula to calculate the boiler total blast volume in each secondary air flow regulation experiment process
q a:
，
Wherein:
q agfor the dry air amount (Nm comprising in total blast volume
3/ s);
q h2Ofor comprising water vapour amount (Nm in total blast volume
3/ s);
sspecific humidity for air;
for relative air humidity (%); S is saturation specific humidity;
for excess air coefficient;
bfor the total coal amount of boiler (Kg/s);
q 0for unit mass coal combustion needs theoretical dry air amount (Nm
3/ Kg); O
2for Oxygen Amount in Flue Gas (%);
for greenhouse gas; C
arfor coal as received basis carbon content (%); H
arfor coal as received basis hydrogen richness (%); O
arfor coal as received basis oxygen content (%); N
arfor coal as received basis nitrogen content (%); S
arfor coal as received basis sulfur content (%);
q bfor boiler total amount of heat (MW); Q
arfor coal as received basis net calorific value (MJ/Kg);
q msfor boiler overheating steam flow (Kg/s);
q rsfor boiler reheated steam flow (Kg/s);
h msfor boiler overheating steam specific enthalpy (MJ/Kg);
h rsfor boiler reheated steam specific enthalpy (MJ/Kg);
h fwfor boiler feed water specific enthalpy (MJ/Kg);
h hsfor boiler reheater inlet steam specific enthalpy (MJ/Kg);
bfor boiler efficiency (%);
D. the foundation of total blast volume balance equation group and solving:
Utilize the equilibrium relation of boiler total blast volume, list the air balance equation that under same load point, original state and each secondary air flow regulation experiment obtain:
，
，
…
Wherein:
q a0,
q a1,
q a2,
q anfor original state, the 1st, 2 ... total blast volume (Nm in n secondary air flow regulation experiment process
3/ s);
b 10,
b 11,
b 12,
b 1nfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism 1 in n Secondary Air regulation experiment process;
b 20,
b 21,
b 22,
b 2nfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism 2 in n Secondary Air regulation experiment process;
b n0,
b n1,
b n2,
b nnfor original state, the 1st, 2 ... the measurement secondary air flow variable of secondary air flow measurement mechanism n in n Secondary Air regulation experiment process;
k c1,
k c2,
k cnbe the 1st, 2 ... n secondary air flow measurement mechanism coefficient of flow;
q fafor the total primary air flow (Nm of boiler
3/ s);
q lfor burner hearth inleakage (Nm
3/ s);
Solve the system of equations being formed by above equation, obtain the coefficient of flow of each secondary air flow measurement mechanism
k c1,
k c2,
k cn;
E. by the coefficient of flow calculating
k c1,
k c2,
k cncoefficient of flow as each secondary air flow measurement mechanism when actual air volume is measured, completes the demarcation of secondary air flow.
2. coal-burning boiler secondary air flow online calibration method according to claim 1, it is characterized in that, during measurement, under a plurality of boiler loads working point, carry out secondary air flow regulation experiment, obtain the coefficient of flow of many group secondary air flow measurement mechanisms, and will organize the coefficient of flow of the mean value of coefficient of flow as each secondary air flow measurement mechanism when actual air volume is measured more.
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| CN103077305B (en) * | 2012-12-30 | 2015-11-25 | 华北电力大学（保定） | Large coal-fired boiler flue gas flow flexible measurement method |
| WO2017133316A1 (en) * | 2016-02-02 | 2017-08-10 | 华北电力科学研究院有限责任公司 | Method, device, and automatic control system for determining air intake amount for opposed firing |
| CN106895434B (en) * | 2017-02-06 | 2019-02-19 | 国家能源集团谏壁发电厂 | Low nitrogen burning autocontrol method under tower-type furnace Researched of Air Staging Combustion Burning Pulverized Coal mode |
| CN108875165B (en) * | 2018-06-01 | 2022-10-21 | 清华大学 | Boiler characteristic calibration method based on operation data |
| CN109307573B (en) * | 2018-09-26 | 2021-06-29 | 国网河北省电力有限公司电力科学研究院 | Air leakage rate testing method for air preheater |
| CN109990269A (en) * | 2019-04-23 | 2019-07-09 | 西安热工研究院有限公司 | A kind of W flame boiler allocation of the amount of air regulating system |
| CN110566928B (en) * | 2019-09-16 | 2021-06-15 | 中煤科工清洁能源股份有限公司 | Automatic control method, device, equipment and medium for industrial pulverized coal boiler combustion |
| CN113406282B (en) * | 2021-06-18 | 2022-08-30 | 国网安徽省电力有限公司电力科学研究院 | Power station boiler tail flue oxygen field calibration method |
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| CN1475776A (en) * | 2002-08-16 | 2004-02-18 | 俞思元 | Cross section type flow meter |
| CN101504150B (en) * | 2009-01-19 | 2010-09-08 | 浙江中控技术股份有限公司 | Control method and apparatus for combustion of storage type pulverized coal fired boiler |
| CN101551103B (en) * | 2009-04-30 | 2010-11-10 | 东莞德永佳纺织制衣有限公司 | Automatic boiler combustion control system of circulating fluid bed |
| CN101832826B (en) * | 2010-05-10 | 2012-05-30 | 华北电力大学 | Measuring method of combustion rate signal of large-scale boiler |
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