CN111550820A - Boiler over-fire air adjusting method based on power moment - Google Patents

Boiler over-fire air adjusting method based on power moment Download PDF

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Publication number
CN111550820A
CN111550820A CN202010448247.5A CN202010448247A CN111550820A CN 111550820 A CN111550820 A CN 111550820A CN 202010448247 A CN202010448247 A CN 202010448247A CN 111550820 A CN111550820 A CN 111550820A
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wind
reverse
air
over
boiler
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CN111550820B (en
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李有信
王磊
蓝晓村
程金武
安敬学
姬亚
许贺
廖彭伟
孔禹
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China Datang Corp Science and Technology Research Institute Co Ltd
Zhongnan Electric Power Test and Research Institute of China Datang Group Science and Technology Research Institute Co Ltd
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Huazhong Electric Power Test Research Institute China of Datang Corp Science and Technology Research Institute Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L1/00—Passages or apertures for delivering primary air for combustion 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N3/00—Regulating air supply or draught

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  • Combustion & Propulsion (AREA)
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Abstract

The invention relates to a boiler over-fire air adjusting method based on power moment, which adopts the technical scheme that the momentum moments of burners with opposite rotating directions of a main combustion area are summed to form inverse tangent power moment; summing the momentum moments of the burners with the same rotation direction of the main combustion area to obtain a tangent wind momentum moment; the method has the advantages that the ratio of the sum of the reverse cut wind moment and the sum of the tangent wind moment is carried out, the reverse cut angle of the over fire air is adjusted through the over fire air adjusting mechanism until the ratio is 0.8-1.2, the hot state adjusting effect is achieved through a cold state test, the working process and the working amount are simplified, the working efficiency is greatly improved, the cut-rotation effect of the over fire air is improved through the adjustment of the over fire air of the boiler, the residual rotation of the boiler is eliminated, the smoke gas of the horizontal flue of the boiler is uniformly distributed, the ash deposition of the horizontal flue is uniform finally, the ash falling has no influence on the disturbance of the boiler, the negative pressure does not fluctuate greatly any more, the smoke temperature deviation and the steam temperature deviation of the horizontal flue are reduced, and the safe operation of the boiler.

Description

Boiler over-fire air adjusting method based on power moment
Technical Field
The invention relates to a power moment-based boiler over-fire air adjusting method.
Background
The coal-fired generating set is the main force of the existing electric power, the tangential firing boilers at four corners in the coal-fired generating set are widely applied, in order to improve the stable firing performance of low load of the boiler and the burnout performance of pulverized coal, primary and secondary co-rotating firing is mostly adopted in a main firing zone, and a small number of layers of reverse deflection air are arranged in the main firing zone to reduce the coking performance of a hearth of the main firing zone, but the rotating direction of the main firing zone cannot be changed. Over-fire air is arranged on the upper portion of the hearth, has a left-right swinging function and can be adjusted through a left-right adjusting mechanism of the over-fire air, and an adjusting angle is displayed on the adjusting mechanism to eliminate the residual rotation effect of boiler tangential circle. In the actual operation of the boiler, in order to reduce NOx emission, the boiler is operated in a staged combustion mode. The main burning area keeps a small opening degree through a secondary air door, and the over-fire air keeps a large opening degree. Therefore, the adjustment of the left and right inverse cutting swing angle of the over-fired air is important, the aim of reducing NOx emission can be achieved, and the flue gas distribution of the upper heating surface of the boiler can be balanced. If the back cut angle of the over-fire air is not properly adjusted, the boiler often has various problems of large deviation of smoke temperature at two sides, large deviation of steam temperature, easy overrun of wall temperature, serious dust deposition at one side, large deviation of wall temperature of a heating surface and the like.
The regulation of the existing over-fire air has no theoretical calculation basis, mostly, the regulation is groped on site at the unit operation stage, because the number of over-fire air layers is more, about 3 layers of over-fire air nozzles are arranged in a 300MW level boiler, about 6 layers of over-fire air nozzles are arranged in a 600MW level boiler, about 8 layers of over-fire air nozzles are arranged in a 1000MW level boiler, the regulation is complicated and the time is longer, and the over-fire air burner is usually jammed due to thermal expansion under the thermal state condition, and the problem of unable regulation can not be solved. The safe and stable operation of the boiler is seriously influenced.
Disclosure of Invention
In view of the above situation, the present invention provides a method for adjusting the over fire air of a boiler based on power moment, which can effectively solve the problem of adjusting the over fire air of the boiler.
The technical scheme of the invention is as follows:
a method for adjusting the over-fire air of boiler based on power moment includes such steps as burning the boiler by tangential circles at four corners to form clockwise or anticlockwise burning tangent circle in burning region, removing residual rotation by over-fire air to form anticlockwise or clockwise reverse tangent circle,
summing the momentum moments of the burners opposite to the rotation direction of the main combustion area to obtain a counter-tangential wind momentum moment; summing the momentum moments of the burners with the same rotation direction of the main combustion area to obtain a tangent wind momentum moment;
the ratio of the sum of the reverse tangent wind momentum moments to the sum of the tangent wind momentum moments is as follows:
Figure BDA0002506738850000011
in the formula, MInverse directionFor each counter-tangential air burner moment of momentum, MIs justThe moment of momentum of each tangential wind burner; k is the ratio of the sum of the inverse tangent wind momentum moments to the sum of the tangent wind momentum moments;
if the value of the ratio K is 0.8-1.2, the residual rotation in the boiler is small, the rotation cutting effect of the over-fire air is good, and the over-fire air reverse cutting angle does not need to be adjusted;
if the value of the ratio K is not 0.8-1.2, calculating the back cut adjustment angle of the over-fire air by the following two methods:
method A, the adjustment angle of the reverse cut angle of the over-fire air can be calculated by the following formula:
Figure BDA0002506738850000021
in the formula: beta is the reverse cut angle adjustment angle of the over-fire air;
alpha is the design angle of the boiler, degree;
l is the design length of the boiler, m;
k is the ratio of the sum of the inverse tangent wind momentum moments to the sum of the tangent wind momentum moments;
ρ2is the jet density of secondary air in kg/m3；
v2The secondary air nozzle speed is m/s;
A2is the area of the secondary air nozzle, m2；
R2Is the secondary wind tangential radius, m.
ρ1Is the nozzle density of primary air in kg/m3；
v1Is the primary air jet velocity, m/s.
A1Is the area of a wind nozzle, m2；
R1Is the primary wind tangential radius, m;
mu is the mass concentration of the primary air fuel, kg/kg;
k is a coefficient considering the difference between the pulverized coal flow velocity and the wind speed;
ρ2 reverseIs the nozzle density of the reverse cutting secondary air, kg/m3；
v2 reverseThe jet speed of the secondary air is reverse cut, m/s;
A2 reverseIs the area of a nozzle with reverse cut secondary air, m2；
The method B comprises the following steps: according to different opening degrees of all loads of the over-fire air, the back-cut adjusting angle of each layer of over-fire air is preset in advance, and the radius R of a back-cut air tangent circle is calculated according to the following formula2 reverse：
R2 reverse＝Lsin(β-α)
In the formula: l is defined by the design length of the boiler, m;
alpha is the design angle of the boiler, degree;
beta is the reverse cut adjustment angle of the over-fire air;
R2 reverseThe radius of a circle is cut by secondary wind in a reverse cutting mode, m;
by the obtained inverse tangential wind tangent circle radius R2 reverseCalculating the sum of the momentum moments of each strand of reverse tangential wind, carrying out ratio on the sum of the momentum moments of the reverse tangential wind and the sum of the tangential wind momentum moments to obtain a ratio K of the sum of the momentum moments of the reverse tangential wind and the sum of the tangential wind momentum moments, if K is not between 0.8 and 1.2, presetting the reverse cutting adjustment angle of the over-fire wind again, calculating again until the ratio K is between 0.8 and 1.2, and then presetting the reverse cutting adjustment angle of the over-fire wind at this moment as the actual adjustment angle of the reverse cutting angle of the over-fire wind in the subsequent step.
And (4) adjusting the reverse cut angle of the over-fire air through the over-fire air adjusting mechanism according to the reverse cut angle adjusting angle of the over-fire air obtained in the step A or the step B, so that the cyclone cutting effect of the over-fire air can be improved, the residual rotation of the boiler is eliminated, and the smoke distribution of the horizontal flue of the boiler is uniform.
The method is simple, the hot state adjusting effect is realized through a cold state test, the working process and the workload are simplified, the working efficiency is greatly improved, the disrotatory effect of the over-fire air is improved through the adjustment of the over-fire air of the boiler, the residual rotation of the boiler is eliminated, the smoke gas of the horizontal flue of the boiler is uniformly distributed, the ash deposition of the horizontal flue is uniform finally, the falling ash has no influence on the disturbance of the boiler, the negative pressure does not fluctuate greatly any more, the smoke temperature deviation and the steam temperature deviation of the horizontal flue are reduced, the safe operation of the boiler is improved, the use is convenient, the effect is good, the method is an innovation of the hot state adjusting technology of the boiler, and good social and economic benefits are realized.
Drawings
FIG. 1 is a schematic diagram of an embodiment of the present invention.
FIG. 2 is a thermal state characteristic curve of No. 1 secondary air angle of an AA layer of a certain boiler.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples.
A method for adjusting the over-fire air of boiler based on power moment includes such steps as burning the boiler by tangential circles at four corners to form clockwise or anticlockwise burning tangent circle in burning region, removing residual rotation by over-fire air to form anticlockwise or clockwise reverse tangent circle,
summing the momentum moments of the burners opposite to the rotation direction of the main combustion area to obtain a counter-tangential wind momentum moment; summing the momentum moments of the burners with the same rotation direction of the main combustion area to obtain a tangent wind momentum moment;
the ratio of the sum of the reverse tangent wind momentum moments to the sum of the tangent wind momentum moments is as follows:
Figure BDA0002506738850000031
in the formula, MInverse directionFor each counter-tangential air burner moment of momentum, MIs justThe moment of momentum of each tangential wind burner; k is the ratio of the sum of the inverse tangent wind momentum moments to the sum of the tangent wind momentum moments;
if the value of the ratio K is 0.8-1.2, the residual rotation in the boiler is small, the rotation cutting effect of the over-fire air is good, and the over-fire air reverse cutting angle does not need to be adjusted;
if the value of the ratio K is not 0.8-1.2, calculating the back cut adjustment angle of the over-fire air by the following two methods:
method A, the adjustment angle of the reverse cut angle of the over-fire air can be calculated by the following formula:
Figure BDA0002506738850000032
in the formula: beta is the reverse cut angle adjustment angle of the over-fire air;
alpha is the design angle of the boiler, degree;
l is the design length of the boiler, m;
k is the ratio of the sum of the inverse tangent wind momentum moments to the sum of the tangent wind momentum moments;
ρ2is the jet density of secondary air in kg/m3；
v2The secondary air nozzle speed is m/s;
A2is the area of the secondary air nozzle, m2；
R2Is the secondary wind tangential radius, m.
ρ1Is the nozzle density of primary air in kg/m3；
v1Is the primary air jet velocity, m/s.
A1Is the area of a wind nozzle, m2；
R1Is the primary wind tangential radius, m;
mu is the mass concentration of the primary air fuel, kg/kg;
k is a coefficient (which can be 0.8) considering the difference between the pulverized coal flow rate and the wind speed;
ρ2 reverseIs the nozzle density of the reverse cutting secondary air, kg/m3；
v2 reverseThe jet speed of the secondary air is reverse cut, m/s;
A2 reverseIs the area of a nozzle with reverse cut secondary air, m2；
The method B comprises the following steps: according to different opening degrees of all loads of the over-fire air, the back-cut adjusting angle of each layer of over-fire air is preset in advance, and the radius R of a back-cut air tangent circle is calculated according to the following formula2 reverse：
R2 reverse＝Lsin(β-α)
In the formula: l is defined by the design length of the boiler, m;
alpha is the design angle of the boiler, degree;
beta is the reverse cut adjustment angle of the over-fire air;
R2 reverseThe radius of a circle is cut by secondary wind in a reverse cutting mode, m;
by the obtained inverse tangential wind tangent circle radius R2 reverseCalculating the sum of the momentum moments of each strand of reverse tangential wind, carrying out ratio on the sum of the momentum moments of the reverse tangential wind and the sum of the tangential wind momentum moments to obtain a ratio K of the sum of the momentum moments of the reverse tangential wind and the sum of the tangential wind momentum moments, if K is not between 0.8 and 1.2, presetting the reverse cutting adjustment angle of the over-fire wind again, calculating again until the ratio K is between 0.8 and 1.2, and then presetting the reverse cutting adjustment angle of the over-fire wind at this moment as the actual adjustment angle of the reverse cutting angle of the over-fire wind in the subsequent step.
And (4) adjusting the reverse cut angle of the over-fire air through the over-fire air adjusting mechanism according to the reverse cut angle adjusting angle of the over-fire air obtained in the step A or the step B, so that the cyclone cutting effect of the over-fire air can be improved, the residual rotation of the boiler is eliminated, and the smoke distribution of the horizontal flue of the boiler is uniform.
Moment of momentum M of each tangential wind burnerIs justThe following equation is used to obtain:
Mis just＝M1+M2
In the formula: m1Is the secondary wind moment of tangent burner, kgm2/s；
M2Is the primary wind moment of tangent burner, kgm2/s；
The secondary wind moment of the tangent burner is calculated by the following formula:
Figure BDA0002506738850000051
in the formula: rho2Is the jet density of secondary air in kg/m3；v2The secondary air nozzle speed is m/s; a. the2Is the area of the secondary air nozzle, m2；R2Is the secondary wind tangential radius, m;
the primary wind moment of the tangent burner is calculated by the following formula:
Figure BDA0002506738850000052
in the formula: rho1Is the nozzle density of primary air in kg/m3；v1The primary air nozzle speed is m/s; a. the1Is the area of a wind nozzle, m2；R1Is the primary wind tangential radius, m; mu is the mass concentration of the primary air fuel, kg/kg; and k is a coefficient (which can be 0.8) considering the difference between the pulverized coal flow velocity and the wind speed.
Each counter tangential air burner momentum moment MInverse directionThe following equation is used to obtain:
Figure BDA0002506738850000053
in the formula: rho2 reverseIs the nozzle density of the reverse cutting secondary air, kg/m3；v2 reverseThe jet speed of the secondary air is reverse cut, m/s; a. the2 reverseIs the area of a nozzle with reverse cut secondary air, m2；R2 reverseThe radius of the circle is cut by the reverse secondary wind.
On the basis of the thermal state design temperature and the design secondary air speed of the boiler, the air speed of the air door in the cold state when the air door is fully opened is calculated in a simulation mode, the air speeds of 0%, 25%, 50%, 75% and 100% of the opening degree of the secondary air door baffle are measured at the nozzle one by one under the condition that the working condition of the cold state is kept unchanged, then the air speeds of 0%, 25%, 50%, 75% and 100% of the opening degree of the secondary air door baffle in the thermal state are calculated in a simulation mode, and a characteristic curve of the thermal state secondary; specifically, the opening degree of the air door is used as an abscissa, the air speed of a nozzle is used as an ordinate, and a thermal-state secondary air door baffle characteristic curve can be formulated through office software excle;
calculating the momentum moment of each combustor according to the opening degree of the thermal state secondary air door in common operation, the corresponding wind speed in the characteristic curve, the design radius of the main combustion zone combustor and the thermal state air flow density;
taking fig. 1 as an example, the combustion area is a tangent circle in a clockwise direction, and the overfire air is a reverse tangent circle in a counterclockwise direction, and the source and the calculation method of each numerical value are performed.
ρ1，ρ2，ρ2 reverseCan be calculated according to the temperature and the pressure of the air box in the hot state.
A1，A2，A2 reverseThe design area for the burner;
R1，R2a design tangent radius for the burner;
v2the data simulation method can be calculated according to the cold test result, and the specific method is as follows:
according to the hot state design wind speed and the design temperature, under the condition that the air quantity of each nozzle is kept unchanged, the cold state nozzle wind speed is calculated according to a formula:
νcold＝(273+TCold)νIs provided with/(273+TIs provided with)
In the formula: t isColdThe air temperature is the air temperature in the cold test; c
vColdThe wind speed is the wind speed in the cold test; m/s
TIs provided withThe design is the wind temperature; c
vIs provided withWind speed designed for thermal state; m/s
vColdAnd (3) performing wind speed tests on 0%, 25%, 50%, 75% and 100% characteristic opening degrees of the secondary air small air door baffles one by one as secondary wind speed when the secondary air baffles are fully opened.
According to the formula
ν＝(273+THeat generation)νCold 1/(273+TCold)
In the formula: t isColdThe temperature of the air in the cold test is measured at DEG C;
vcold 1The wind speed is 0%, 0%, 25%, 50%, 75% and 100% of the wind speed of the secondary air door in the cold test; m/s
v is the wind speed of 0%, 0%, 25%, 50%, 75% and 100% of the thermal secondary air door; m/s
THeat generationThe air temperature is the actual running air temperature; c
And (5) formulating a thermal-state secondary air door baffle characteristic curve.
Specifically, the opening degree of the air door is used as an abscissa, the air speed of a nozzle is used as an ordinate, and a thermal-state secondary air door baffle plate characteristic curve is formulated by common office software excle; . FIG. 2 shows the thermal state characteristic curve of the secondary air No. 1 corner of the AA layer of a certain boiler.
According to the characteristic curve of the secondary air door baffle in the thermal state and according to the opening degree of the air door in the thermal state, finding out the air speed under the corresponding opening degree, namely v2Wind speed (secondary air jet speed). Reverse cutting secondary air nozzle velocity v in the same way2 reverseCan pass through the velocity v of the secondary air nozzle2The method is calculated.
The technology of the invention obtains good effect through practical application, and the specific conditions are as follows:
a certain newly-built 600MW unit boiler is a single-hearth four-corner tangential round II-shaped boiler, a main combustion area rotates clockwise, three layers of high-level over-fire air and three layers of low-level over-fire air are arranged, the over-fire air can swing left and right for 25 degrees, and in the initial stage of trial run, the over-fire air is adjusted to be reversely cut for 5 degrees in order to eliminate residual rotation. After the unit is started, the unit operates at 300 MW-400 MW load, and has the following problems:
(1) the horizontal flue collapse ash phenomenon occurs for many times in the period, and the negative pressure of the boiler is disturbed in different degrees. Inspecting the horizontal flue at the opportunity of blowing out the furnace, and finding that a large amount of accumulated dust exists on the right side of the horizontal flue, wherein the depth reaches 2-3 m; the left side has less deposited dust and the depth is less than 1 meter. The ash deposition on the right side of the horizontal flue is more, and the ash deposition balance is broken due to disturbance, so that the ash collapse is caused, and the safe operation of the boiler is influenced;
(2) the left side of the horizontal flue gas temperature is higher, the right side is lower, and the deviation reaches 56.5;
(3) the left side of the steam temperature is higher, the right side is lower, and the deviation reaches 15 ℃.
The moment of momentum of the boiler was calculated at 350MW load and the data is as follows:
TABLE 1 boiler momentum moment calculation data
Figure BDA0002506738850000071
It can be seen that: under the working condition, the ratio K of the momentum moment of the reverse-cut nozzle to the momentum moment of the tangent nozzle is 0.088, which indicates that the swirling action of the over-fired air of the boiler is weak.
The method is adopted to determine the angle of the over-fire air of the boiler, finally the left and right swing angles of the lowest layer of the low-level over-fire air are adjusted from 5 degrees of reverse cutting to 25 degrees of reverse cutting, the left and right swing angles of the lower two layers of the high-level over-fire air are adjusted from 5 degrees of reverse cutting to 25 degrees of reverse cutting, and the angles of other over-fire air are unchanged. The ratio K of the sum of the moments of the back-cut nozzles and the sum of the moments of the tangent nozzles of the 350MW boiler after adjustment is 0.860. The effects after adjustment are as follows:
(1) after adjustment, if the horizontal flue is operated for a long time under low load, the deposited dust still exists, the deposited dust is relatively even, and the depth is less than 1.5 meters.
The falling ash has no influence on the disturbance of the boiler, the negative pressure is not greatly fluctuated, and the safe operation of the boiler is improved.
(2) The smoke temperature deviation of the horizontal flue is reduced to 20 ℃;
(3) the steam temperature deviation is reduced to 5 ℃.
And the ratio of the sum of the moments of momentum of the high-load reverse-tangential nozzles to the sum of the moments of momentum of the tangential nozzles is verified and calculated, wherein the 600MW load is that K is 1.125.
The method only takes 1 day for adjustment, and the common conventional groping adjustment generally takes 7-10 days, so that the working efficiency is greatly improved compared with the conventional adjustment.
The multiple boilers carry out the adjustment of the boiler reverse cut air through the calculation of the kinetic moment of the method, thereby solving the practical problems of the boilers, and the following table shows that:
Figure BDA0002506738850000081
from the above situation, it can be clearly seen that the adjustment of the boiler over-fire air by the method of the invention improves the disrotatory effect of the over-fire air, eliminates the residual rotation of the boiler, makes the smoke distribution of the horizontal flue of the boiler uniform, finally presents the uniform deposition of the horizontal flue, has no influence on the disturbance of the boiler due to the falling ash, has no great fluctuation of the negative pressure, reduces the smoke temperature deviation and the steam temperature deviation of the horizontal flue, realizes the thermal state adjustment effect through the cold state test, simplifies the working flow and the workload, greatly improves the operation efficiency, improves the safe operation of the boiler, is convenient to use, has good effect, is an innovation of the thermal state adjustment technology of the boiler, and has good social and economic benefits.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (3)

1. A boiler over-fire air adjusting method based on power moment comprises a four-corner tangential firing boiler, a clockwise or anticlockwise combustion tangent circle is formed in a combustion area, an anticlockwise or clockwise reverse tangent circle is formed for eliminating residual rotation in over-fire air, and the method is characterized in that,
summing the momentum moments of the burners opposite to the rotation direction of the main combustion area to obtain a counter-tangential wind momentum moment; summing the momentum moments of the burners with the same rotation direction of the main combustion area to obtain a tangent wind momentum moment;
the ratio of the sum of the reverse tangent wind momentum moments to the sum of the tangent wind momentum moments is as follows:
Figure FDA0002506738840000011
in the formula, MInverse directionFor each counter-tangential air burner moment of momentum, MIs justThe moment of momentum of each tangential wind burner; k is the ratio of the sum of the inverse tangent wind momentum moments to the sum of the tangent wind momentum moments;
if the value of the ratio K is 0.8-1.2, the residual rotation in the boiler is small, the rotation cutting effect of the over-fire air is good, and the over-fire air reverse cutting angle does not need to be adjusted;
if the value of the ratio K is not 0.8-1.2, calculating the back cut adjustment angle of the over-fire air by the following two methods:
method A, the adjustment angle of the reverse cut angle of the over-fire air can be calculated by the following formula:
Figure FDA0002506738840000012
in the formula: beta is the reverse cut angle adjustment angle of the over-fire air;
alpha is the design angle of the boiler, degree;
l is the design length of the boiler, m;
k is the ratio of the sum of the inverse tangent wind momentum moments to the sum of the tangent wind momentum moments;
ρ2is the jet density of secondary air in kg/m3；
v2The secondary air nozzle speed is m/s;
A2is the area of the secondary air nozzle, m2；
R2Is the secondary wind tangential radius, m.
ρ1Is the nozzle density of primary air in kg/m3；
v1Is the primary air jet velocity, m/s.
A1Is the area of a wind nozzle, m2；
R1Is the primary wind tangential radius, m;
mu is the mass concentration of the primary air fuel, kg/kg;
k is a coefficient considering the difference between the pulverized coal flow velocity and the wind speed;
ρ2 reverseIs the nozzle density of the reverse cutting secondary air, kg/m3；
v2 reverseThe jet speed of the secondary air is reverse cut, m/s;
A2 reverseIs the area of a nozzle with reverse cut secondary air, m2；
The method B comprises the following steps: according to different opening degrees of all loads of the over-fire air, the back-cut adjusting angle of each layer of over-fire air is preset in advance, and the radius R of a back-cut air tangent circle is calculated according to the following formula2 reverse：
R2 reverse＝Lsin(β-α)
In the formula: l is defined by the design length of the boiler, m;
alpha is the design angle of the boiler, degree;
beta is the reverse cut adjustment angle of the over-fire air;
R2 reverseThe radius of a circle is cut by secondary wind in a reverse cutting mode, m;
by the obtained inverse tangential wind tangent circle radius R2 reverseCalculating the sum of the momentum moments of each strand of reverse tangential wind, carrying out ratio on the sum of the momentum moments of the reverse tangential wind and the sum of the tangential wind momentum moments to obtain a ratio K of the sum of the momentum moments of the reverse tangential wind and the sum of the tangential wind momentum moments, if K is not between 0.8 and 1.2, presetting the reverse cutting adjustment angle of the over-fire wind again, calculating again until the ratio K is between 0.8 and 1.2, and then presetting the reverse cutting adjustment angle of the over-fire wind at this moment as the actual adjustment angle of the reverse cutting angle of the over-fire wind in the subsequent step.
And (4) adjusting the reverse cut angle of the over-fire air through the over-fire air adjusting mechanism according to the reverse cut angle adjusting angle of the over-fire air obtained in the step A or the step B, so that the cyclone cutting effect of the over-fire air can be improved, the residual rotation of the boiler is eliminated, and the smoke distribution of the horizontal flue of the boiler is uniform.
2. The method of claim 1, wherein each tangential wind burner momentum moment M is a power moment based method for adjusting the over-fire wind of the boilerIs justThe following equation is used to obtain:
Mis just＝M1+M2
In the formula: m1Is the secondary wind moment of tangent burner, kgm2/s；
M2Is the primary wind moment of tangent burner, kgm2/s；
The secondary wind moment of the tangent burner is calculated by the following formula:
Figure FDA0002506738840000021
in the formula: rho2Is the jet density of secondary air in kg/m3；v2The secondary air nozzle speed is m/s; a. the2Is the area of the secondary air nozzle, m2；R2Is the secondary wind tangential radius, m;
the primary wind moment of the tangent burner is calculated by the following formula:
Figure FDA0002506738840000022
in the formula: rho1Is the nozzle density of primary air in kg/m3；v1The primary air nozzle speed is m/s; a. the1Is the area of a wind nozzle, m2；R1Is the primary wind tangential radius, m; mu is the mass concentration of the primary air fuel, kg/kg; k is a coefficient considering the difference between the flow rate of the pulverized coal and the wind speed.
3. The power-moment-based boiler over-fire air adjustment method according to claim 1, wherein each counter-tangential-air burner momentum moment MInverse directionThe following equation is used to obtain:
Figure FDA0002506738840000031
in the formula: rho2 reverseIs the nozzle density of the reverse cutting secondary air, kg/m3；v2 reverseThe jet speed of the secondary air is reverse cut, m/s; a. the2 reverseIs the area of a nozzle with reverse cut secondary air, m2；R2 reverseThe radius of the circle is cut by the reverse secondary wind.
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