CN102620774A - Method for calibrating secondary air volume of coal-fired boiler on line - Google Patents

Method for calibrating secondary air volume of coal-fired boiler on line Download PDF

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CN102620774A
CN102620774A CN201210049597XA CN201210049597A CN102620774A CN 102620774 A CN102620774 A CN 102620774A CN 201210049597X A CN201210049597X A CN 201210049597XA CN 201210049597 A CN201210049597 A CN 201210049597A CN 102620774 A CN102620774 A CN 102620774A
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boiler
air
air flow
measurement
flow
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CN201210049597XA
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CN102620774B (en
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田亮
刘鑫屏
赵亮宇
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华北电力大学(保定)
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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

Coal-burning boiler secondary air flow online calibration method
Technical field
The present invention relates to a kind of method that can under the coal-burning boiler normal operating condition, accurately demarcate, belong to the boiler technology field its secondary air flow.
Background technology
Coal-air ratio has determined the efficient of coal-burning boiler to a great extent in the boiler technology.When air quantity was bigger than normal, the boiler exhaust gas loss boiler efficiency that causes bigger than normal reduced; When air quantity was less than normal, the imperfect combustion loss of the boiler boiler efficiency that also can cause bigger than normal reduced, and there is the coal-air ratio of an optimum in coal-burning boiler.Adopt excess air coefficient to describe this notion in the engineering, 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 many zirconia oxygen analyzers measurement flue gas oxygen amounts in the left and right sides flue before the air preheater behind economizer at present; And regulate the boiler secondary air amount through the oxygen amount control system flue gas oxygen amount is maintained near the certain value, 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, and in fact in whole combustion process, wind is sent into stage by stage: the main effect of a wind is the burning of carrying coal particle and supporting fugitive constituent in the coal; The main effect of secondary air is the burning of supporting coke grain in the coal; The main effect of burnt wind is to guarantee the coal after-flame and oxidizing atmosphere is provided.Burnt wind is the part in the secondary air on the principle, its purpose of separating be the combustion intensity that reduces boiler master combustion zone with oxygen concentration with minimizing NO XGeneration.A large amount of theory and experimental studies prove whether each stage air quantity dispensing of burning rationally can influence boiler NO to a great extent XDischarge capacity and unburned carbon in flue dust, and then boiler operatiopn economy, the feature of environmental protection exerted an influence.
The big bellows structure of the many employings of large coal-fired boiler at present; The secondary air of each layer burner and burnt wind all have separately independently control gear and measurement mechanism; Can implement accurately control to the air distribution amount in each stage in the combustion process in theory, the accuracy of its control depends primarily on the accuracy of air measuring.But on-the-spot often the appearance measures inaccurately because of secondary air flow, causes the air flow rate proportioning deterioration in accuracy and then influences the situation of boiler combustion.As certain air measuring value depart from obviously that normal value influences that this loop is dropped into automatically, the total blast volume substantial deviation design load that obtains after the summation of each item air measuring value and be not inconsistent or the like with practical operation situation.
Cause the air measuring reasons of error to comprise: (1) secondary air flow measurement mechanism is the nonstandardized technique measurement mechanism, and the accuracy of on-site proving error occurred in calibration process when its accuracy of measurement depended on boiler cold-state; (2) the secondary air temperature surpasses 300 ℃ during boiler operatiopn, and apparatus for measuring air quantity produces thermal deformation, and perhaps apparatus for measuring air quantity produces distortion after the boiler long-time running, causes coefficient of flow to change; (3) secondary air pipeline cross section is a rectangle and thicker, and straight length can not satisfy measurement requirement before and after the measurement mechanism installation site, increases measuring error; (4) flying dust in the boiler smoke is deposited in the boiler air preheater and is carried by secondary air, causes apparatus for measuring air quantity to produce wearing and tearing or local the obstruction, causes big measuring error.
Need carry out the air quantity calibration experiment when above situation occurring.The tradition calibration experiment can only carry out under the boiler shutdown state; By the experimenter pitot tube group or bourdon's tube group are installed in the air channel; The startup boiler fan makes keeps nominal air delivery in the air channel; Calculate air quantity as normal flow after adopting installation pitot tube group or bourdon's tube group to measure mean wind speed, remove to calibrate the on-the-spot coefficient of flow that the air measuring instrument is installed, make both show the air quantity unanimity.Owing to there are reasons such as error, wind flow is inhomogeneous, the hot operating mode leeward of cold conditions flow characteristics there are differences in on-the-spot straight length deficiency, pitot tube group or the installation of bourdon's tube group, the accuracy that the method is demarcated neither be very high.And narrow and small, the inclement condition in work on the spot place is installed and is removed wind speed measuring device and bothers very much, and experimental period is long, demarcation is 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 the 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; Said method is under a certain steady load point of boiler, to carry out the adjustment experiment of each secondary air flow successively; The record experimental data also utilizes the equilibrium relation of boiler total blast volume to set up polynary linear function group; Obtain the coefficient of flow of each secondary air flow measurement mechanism through finding the solution this system of equations; When actual air volume is measured, utilize the coefficient of flow that calculates can obtain accurate air quantity, thereby realize the on-line calibration to secondary air flow, concrete demarcating steps is following:
A. under a certain steady load point, carry out each secondary air flow adjustment experiment successively, and the experimental data that collates the minutes;
B. the measured value of representing each secondary air flow measurement mechanism in each secondary air flow adjustment experimentation with following formula q s:
,?
Wherein, K cBe the measurement mechanism coefficient of flow; bFor measuring the secondary air flow variable; p dBe the distinguished and admirable differential pressure (KPa) of crossing the measurement mechanism generation; p ActBe local atmospheric pressure (KPa); p sBe wind static pressure (KPa) in the pipeline; tFor wind-warm syndrome degree in the pipeline (℃);
C. the boiler total blast volume calculates
Adopt following formula to calculate the boiler total blast volume in each secondary air flow adjustment experimentation q a:
Wherein: q AgBe the dry air amount (Nm that comprises in the total blast volume 3/ s); q H2OFor comprising water vapour amount (Nm in the total blast volume 3/ s); sSpecific humidity for air; Be relative air humidity (%); S is a saturation specific humidity, Be excess air coefficient; BBe the total coal amount of boiler (Kg/s); q 0For the unit mass coal combustion needs theoretical dry air amount (Nm 3/ Kg); O 2Be flue gas oxygen amount (%); Be the fuel characteristic coefficient; C ArBe coal as received basis carbon content (%); H ArBe coal as received basis hydrogen richness (%); O ArBe coal as received basis oxygen content (%); N ArBe coal as received basis nitrogen content (%); S ArBe coal as received basis sulfur content (%); Q BBe boiler total amount of heat (MW); Q ArBe coal as received basis net calorific value (MJ/Kg); q MsBe boiler overheating steam flow (Kg/s); q RsBe boiler reheated steam flow (Kg/s); h MsBe boiler overheating steam specific enthalpy (MJ/Kg); h RsBe boiler reheated steam specific enthalpy (MJ/Kg); h FwBe boiler feed water specific enthalpy (MJ/Kg); h HsBe boiler reheater inlet steam specific enthalpy (MJ/Kg); Be boiler efficiency (%);
D. the foundation of total blast volume balance equation group and finding the solution:
Utilize the equilibrium relation of boiler total blast volume, list the air balance equation that original state under the same load point and each secondary air flow adjustment experiment obtain:
Wherein: q A0, q A1, q A2, q AnFor original state, the 1st, 2 ... Total blast volume (Nm in n the secondary air flow adjustment experimentation 3/ s); b 10, b 11, b 12, b 1nFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism 1 in the experimentation; b 20, b 21, b 22, b 2nFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism 2 in the experimentation; b N0, b N1, b N2, b NnFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism n in the experimentation; K C1, K C2, K CnBe the 1st, 2 ... N secondary air flow measurement mechanism coefficient of flow; q FaBe the total primary air flow (Nm of boiler 3/ s); q lBe burner hearth inleakage (Nm 3/ s),
Find the solution the system of equations that constitutes by above equation, obtain the coefficient of flow of each secondary air flow measurement mechanism K C1, K C2, K Cn
E. with the coefficient of flow that calculates K C1, K C2, K CnAs the coefficient of flow of each secondary air flow measurement mechanism when actual air volume is measured, accomplish 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 adjustment 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 more as each secondary air flow measurement mechanism when actual air volume is measured.
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 the oxygen content measurement error, when adopting portable oxygen amount meter representative point method to measure the oxygen amount, air quantity demarcate 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 satisfy on-the-spot air quantity adjustment requirement.In addition, primary air flow measuring error and burner hearth leak out can not demarcate secondary air flow and exert an influence.Demarcating the back secondary air flow simultaneously can be consistent with burnings such as boiler total blast volume, secondary air flow ratio, boiler load, the flue gas oxygen amount monitoring parameter displayed value of being correlated with, favourable to raising boiler operatiopn status monitoring and procedure parameter controlling level.
The present invention is an online calibration method, does not need blowing out, carries out at any time in can be in the boiler running process stable load section of secondary air flow adjustment experiment; Basically not influencing boiler normally moves; The loss that can avoid blowing out and startup to bring, and scaling method of the present invention need not install in the boiler air channel and dismantle extra measuring equipment, and calibration process is simple; Saving equipment and human resources, calibration cost are far smaller than traditional scaling method.
Each symbol is in the literary composition of the present invention: q sMeasured value (Nm for the secondary air flow measurement mechanism 3/ s); K cBe the measurement mechanism coefficient of flow; p dBe the distinguished and admirable differential pressure (KPa) of crossing the measurement mechanism generation; p ActBe local atmospheric pressure (KPa); p sBe wind static pressure (KPa) in the pipeline; tFor wind-warm syndrome degree in the pipeline (℃); q aBe the boiler total blast volume; q AgBe the dry air amount (Nm that comprises in the total blast volume 3/ s); q H2OFor comprising water vapour amount (Nm in the total blast volume 3/ s); sSpecific humidity for air; Be relative air humidity (%); S is a saturation specific humidity; Be excess air coefficient; BBe the total coal amount of boiler (Kg/s); q 0For the unit mass coal combustion needs theoretical dry air amount (Nm 3/ Kg); O 2Be flue gas oxygen amount (%); Be the fuel characteristic coefficient; C ArBe coal as received basis carbon content (%); H ArBe coal as received basis hydrogen richness (%); O ArBe coal as received basis oxygen content (%); N ArBe coal as received basis nitrogen content (%); S ArBe coal as received basis sulfur content (%); Q BBe boiler total amount of heat (MW); Q ArBe coal as received basis net calorific value (MJ/Kg); q MsBe boiler overheating steam flow (Kg/s); q RsBe boiler reheated steam flow (Kg/s); h MsBe boiler overheating steam specific enthalpy (MJ/Kg); h RsBe boiler reheated steam specific enthalpy (MJ/Kg); h FwBe boiler feed water specific enthalpy (MJ/Kg); h HsBe boiler reheater inlet steam specific enthalpy (MJ/Kg); Be boiler efficiency (%); q A0, q A1, q A2, q AnFor original state, the 1st, 2 ... Total blast volume (Nm in n the secondary air flow adjustment experimentation 3/ s); bFor measuring the secondary air flow variable; b 10, b 11, b 12, b 1nFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism 1 in the experimentation; b 20, b 21, b 22, b 2nFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism 2 in the experimentation; b N0, b N1, b N2, b NnFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism n in the experimentation; K C1, K C2, K CnBe the 1st, 2 ... N secondary air flow measurement mechanism coefficient of flow; q FaBe the total primary air flow (Nm of boiler 3/ s); q S1Be secondary air flow 1 (Nm 3/ s); q S2Be secondary air flow 2 (Nm 3/ s); q SnBe secondary air flow n (Nm 3/ s); q lBe burner hearth inleakage (Nm 3/ s).
Embodiment
Technical scheme of the present invention:
(1) calibrating parameters explanation
The boiler apparatus for measuring air quantity comprises airfoil type air volume meter and double-venturi pipe air volume meter, and its measure equation is identical, for:
(1)
Wherein: q sFor measuring air quantity (Nm 3/ s); K cBe the measurement mechanism coefficient of flow; p dBe the distinguished and admirable differential pressure (KPa) of crossing the measurement mechanism generation; p ActBe local atmospheric pressure (KPa); p sBe wind static pressure (KPa) in the pipeline; tFor wind-warm syndrome degree in the pipeline (℃).In measure equation, coefficient of flow K cDemarcate inaccurate or change and cause air measuring to have the principal element of systematic error with being, the key that secondary air flow is demarcated is promptly to confirm that each secondary air flow measurement mechanism is correct K c
(2) the boiler total blast volume calculates
The boiler total blast volume adopts following formula to calculate:
(2)
Wherein: q aBe boiler total blast volume (Nm 3/ s); q AgBe the dry air amount (Nm that comprises in the total blast volume 3/ s); q H2OFor comprising water vapour amount (Nm in the total blast volume 3/ s); sSpecific humidity for air.
The air specific humidity adopts following formula to calculate:
(3)
Wherein: is relative air humidity (%); S is a saturation specific humidity, can combine the water and steam thermodynamic properties to calculate by current air themperature and atmospheric pressure.
The dry air amount adopts following formula to calculate:
(4)
Wherein: Be excess air coefficient; BBe the total coal amount of boiler (Kg/s); q 0For the unit mass coal combustion needs theoretical dry air amount (Nm 3/ Kg).
Excess air coefficient adopts following formula to calculate:
(5)
Wherein: O 2Be flue gas oxygen amount (%); Be the fuel characteristic coefficient, adopt following formula to calculate:
(6)
The 1Kg coal combustion needs theoretical dry air amount computing formula to be:
(7)
In the formula 6,7: C ArBe coal as received basis carbon content (%); H ArBe coal as received basis hydrogen richness (%); O ArBe coal as received basis oxygen content (%); N ArBe coal as received basis nitrogen content (%); S ArBe coal as received basis sulfur content (%).
Total coal-supplying amount adopts following formula to calculate:
(8)
Wherein: Q BBe boiler total amount of heat (MW); Q ArBe coal as received basis net calorific value (MJ/Kg).
The boiler total amount of heat adopts following formula to calculate:
(9)
Wherein: q MsBe boiler overheating steam flow (Kg/s); q RsBe boiler reheated steam flow (Kg/s); h MsBe boiler overheating steam specific enthalpy (MJ/Kg); h RsBe boiler reheated steam specific enthalpy (MJ/Kg); h FwBe boiler feed water specific enthalpy (MJ/Kg); h HsBe boiler reheater inlet steam specific enthalpy (MJ/Kg), above specific enthalpy all can adopt temperature, the pressure of steam to utilize water and steam thermodynamic properties formula to calculate; Be boiler efficiency (%) heating power experimental data when adopting boiler acceptance.
(3) the total blast volume balance equation is set up upright and is found the solution
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 constitutes.Because burnt wind is in essence with the 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 the boiler total blast volume is like this:
(10)
Wherein: q FaBe the total primary air flow (Nm of boiler 3/ s); q S1Be secondary air flow 1 (Nm 3/ s); q S2Be secondary air flow 2 (Nm 3/ s); q SnBe secondary air flow n (Nm 3/ s); q lBe burner hearth inleakage (Nm 3/ s).
In secondary air flow computing formula 1, order:
(11)
Claim bFor measuring the secondary air flow variable.
Boiler is under the load operation point of confirming, it is stable constant to guarantee boiler load and main steam pressure to keep coal-supplying amount and primary air flow, and it is stable constant to guarantee the burner hearth inleakage to keep furnace pressure.At this moment according to the air balance principle, the polynary linear function of a benchmark is arranged.
(12)
The adjustment respective execution mechanisms to be changing some secondary air flows, when air quantity reach stable after, correlation parameter can obtain another polynary linear function.All n secondary air flow topworks all adjusted, then can obtain n polynary linear function group:
(13)
(14)
(15)
Wherein: q A0, q A1, q A2, q AnFor original state, the 1st, 2 ... Total blast volume (Nm in n the secondary air flow adjustment experimentation 3/ s); b 10, b 11, b 12, b 1nFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism 1 in the experimentation; b 20, b 21, b 22, b 2nFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism 2 in the experimentation; b N0, b N1, b N2, b NnFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism n in the experimentation; K C1, K C2, K CnBe the 1st, 2 ... N secondary air flow measurement mechanism coefficient of flow.
In the system of equations, n+2 known variables arranged, is respectively: q Fa, K C1, K C2..., K Cn, q lBut can find that through observing system of equations only has n+1 independence and freedom variable, q FaWith q lSum constitutes an independence and freedom variable.Like this, there is unique solution in system of equations.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 after the solving equation group.
(4) repeated experiments
As satisfy the requirements, can under a plurality of boiler loads working point, carry out secondary air flow adjustment 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.
Implementation step of the present invention
(1) experiment is prepared.
Experiment need be carried out under stable load, stable ature of coal and stable atmospheric environment, need guarantee before the experiment that these conditions are satisfied.Need before the experiment to confirm or write down 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 ArLocal atmospheric pressure p ActRelative air humidity Environment temperature; Boiler efficiency
Need in the experimentation to confirm the signal non-fault of record, comprising: the boiler main steam flow q Ms, the 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, select the representative point method to measure boiler smoke oxygen amount according to the regulation of " station boiler performance test rules " (GB10184-88).After perhaps adopting calibrating gas that the zirconia oxygen analyzer of boiler erection is demarcated, measure boiler smoke oxygen amount.
(2) secondary air flow adjustment experiment.
Need to keep boiler load, main steam pressure, primary air flow, furnace pressure to stablize in the experimentation.Specific targets are: the main steam flow variation range is less than rated load ± 0.5%; Main steam temperature changes less than ± 2.5 ℃; Main steam pressure change dum boiler less than ± 0.1MPa, direct current cooker less than ± 0.15MPa; The primary air flow displayed value changes less than ± 0.5%; Furnace pressure changes 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 input is automatic; Keep the furnace pressure definite value constant, furnace pressure control system input is automatic; Keep oxygen amount definite value constant, oxygen amount control system input is automatic; The primary air flow control system is cut to manually, and the topworks that keeps in the whole experiment each control primary air flow is failure to actuate; One time the blast control system is cut to manually, keeps the topworks of a blast of each control to be failure to actuate.After parameters is stable, record original state experimental data.
Manually change the bias of a certain layer burner or a certain crosswind road secondary air plate washer opening control system, make its corresponding secondary air flow variable quantity reach 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 baffle plate and the oxygen amount returned near the 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.The stable back of oxygen amount and furnace pressure record experimental data.
Cancel the biasing of this layer burner or this crosswind road secondary air baffle opening, manually change the biasing of an other one deck burner or an other crosswind road secondary air plate washer aperture, the stable back of oxygen amount and furnace pressure record experimental data.Repeat this experimental procedure, test up to the adjustment of accomplishing the corresponding secondary air flow baffle plate of all secondary air flow measurement mechanisms institute.
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.
Calculate original state according to formula 2 to formula 9 and adjust the boiler total amount of heat under the experiment, and further calculate total blast volume with each secondary air flow.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 the mathematical statistics that it is carried out consistency check, have data to exceed fiducial interval and think that then this group experimental data is invalid.
Calculate original state according to formula 11 and test the measurement secondary air flow variable of each apparatus for measuring air quantity down with each secondary air flow adjustment.
With reference to formula 12 to formula 15, list original state and the air balance equation that each secondary air flow adjustment experiment obtains under the same load point, constitute a system of equations.Find the solution 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 many group different load points situation of experimental data is down arranged, a plurality of the separating of same apparatus for measuring air quantity coefficient of flow, total primary air flow and burner hearth inleakage sum averaged, can reduce the stochastic error influence.
According to each secondary air flow measurement mechanism coefficient of flow of result of calculation online modification, accomplish and demarcate at last.

Claims (2)

1. coal-burning boiler secondary air flow online calibration method; It is characterized in that; Said method is under a certain steady load point of boiler, to carry out the adjustment experiment of each secondary air flow successively; The record experimental data also utilizes the equilibrium relation of boiler total blast volume to set up polynary linear function group, obtains the coefficient of flow of each secondary air flow measurement mechanism through finding the solution this system of equations, and the coefficient of flow that utilization calculates when actual air volume is measured can obtain accurate air quantity; Thereby realize the on-line calibration to secondary air flow, concrete demarcating steps is following:
A. under a certain steady load point, carry out each secondary air flow adjustment experiment successively, and the experimental data that collates the minutes;
B. the measured value of representing each secondary air flow measurement mechanism in each secondary air flow adjustment experimentation with following formula q s:
,?
Wherein, K cBe the measurement mechanism coefficient of flow; bFor measuring the secondary air flow variable; p dBe the distinguished and admirable differential pressure (KPa) of crossing the measurement mechanism generation; p ActBe local atmospheric pressure (KPa); p sBe wind static pressure (KPa) in the pipeline; tFor wind-warm syndrome degree in the pipeline (℃);
C. the boiler total blast volume calculates
Adopt following formula to calculate the boiler total blast volume in each secondary air flow adjustment experimentation q a:
Wherein: q AgBe the dry air amount (Nm that comprises in the total blast volume 3/ s); q H2OFor comprising water vapour amount (Nm in the total blast volume 3/ s); sSpecific humidity for air; Be relative air humidity (%); S is a saturation specific humidity; Be excess air coefficient; BBe the total coal amount of boiler (Kg/s); q 0For the unit mass coal combustion needs theoretical dry air amount (Nm 3/ Kg); O 2Be flue gas oxygen amount (%); Be the fuel characteristic coefficient; C ArBe coal as received basis carbon content (%); H ArBe coal as received basis hydrogen richness (%); O ArBe coal as received basis oxygen content (%); N ArBe coal as received basis nitrogen content (%); S ArBe coal as received basis sulfur content (%); Q BBe boiler total amount of heat (MW); Q ArBe coal as received basis net calorific value (MJ/Kg); q MsBe boiler overheating steam flow (Kg/s); q RsBe boiler reheated steam flow (Kg/s); h MsBe boiler overheating steam specific enthalpy (MJ/Kg); h RsBe boiler reheated steam specific enthalpy (MJ/Kg); h FwBe boiler feed water specific enthalpy (MJ/Kg); h HsBe boiler reheater inlet steam specific enthalpy (MJ/Kg); Be boiler efficiency (%);
D. the foundation of total blast volume balance equation group and finding the solution:
Utilize the equilibrium relation of boiler total blast volume, list the air balance equation that original state under the same load point and each secondary air flow adjustment experiment obtain:
Wherein: q A0, q A1, q A2, q AnFor original state, the 1st, 2 ... Total blast volume (Nm in n the secondary air flow adjustment experimentation 3/ s); b 10, b 11, b 12, b 1nFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism 1 in the experimentation; b 20, b 21, b 22, b 2nFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism 2 in the experimentation; b N0, b N1, b N2, b NnFor original state, the 1st, 2 ... N secondary air adjusted the measurement secondary air flow variable of secondary air flow measurement mechanism n in the experimentation; K C1, K C2, K CnBe the 1st, 2 ... N secondary air flow measurement mechanism coefficient of flow; q FaBe the total primary air flow (Nm of boiler 3/ s); q lBe burner hearth inleakage (Nm 3/ s);
Find the solution the system of equations that constitutes by above equation, obtain the coefficient of flow of each secondary air flow measurement mechanism K C1, K C2, K Cn
E. with the coefficient of flow that calculates K C1, K C2, K CnAs the coefficient of flow of each secondary air flow measurement mechanism when actual air volume is measured, accomplish the demarcation of secondary air flow.
2. according to the said coal-burning boiler secondary air flow of claim 1 online calibration method; It is characterized in that; During measurement; Under a plurality of boiler loads working point, carry out secondary air flow adjustment 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 more as each secondary air flow measurement mechanism when actual air volume is measured.
CN201210049597.XA 2012-02-29 2012-02-29 Method for calibrating secondary air volume of coal-fired boiler on line CN102620774B (en)

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CN103077305A (en) * 2012-12-30 2013-05-01 华北电力大学(保定) Large-scale coal-fired boiler smoke gas flow rate soft measuring method
CN106895434A (en) * 2017-02-06 2017-06-27 中国国电集团公司谏壁发电厂 Low nitrogen burning autocontrol method under tower-type furnace Researched of Air Staging Combustion Burning Pulverized Coal mode
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Publication number Priority date Publication date Assignee Title
CN103077305A (en) * 2012-12-30 2013-05-01 华北电力大学(保定) Large-scale coal-fired boiler smoke gas flow rate soft measuring method
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
CN106895434A (en) * 2017-02-06 2017-06-27 中国国电集团公司谏壁发电厂 Low nitrogen burning autocontrol method under tower-type furnace Researched of Air Staging Combustion Burning Pulverized Coal mode
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
CN109307573A (en) * 2018-09-26 2019-02-05 国网河北省电力有限公司电力科学研究院 Air leak rate of air preheater test method
CN110566928A (en) * 2019-09-16 2019-12-13 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

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