CN113339782B - Adjustment method for metal wall temperature deviation of high-temperature reheater of hedging coal-fired boiler - Google Patents
Adjustment method for metal wall temperature deviation of high-temperature reheater of hedging coal-fired boiler Download PDFInfo
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- CN113339782B CN113339782B CN202110558918.8A CN202110558918A CN113339782B CN 113339782 B CN113339782 B CN 113339782B CN 202110558918 A CN202110558918 A CN 202110558918A CN 113339782 B CN113339782 B CN 113339782B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G5/00—Controlling superheat temperature
- F22G5/02—Applications of combustion-control devices, e.g. tangential-firing burners, tilting burners
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G5/00—Controlling superheat temperature
- F22G5/04—Controlling superheat temperature by regulating flue gas flow, e.g. by proportioning or diverting
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G5/00—Controlling superheat temperature
- F22G5/20—Controlling superheat temperature by combined controlling procedures
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
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Abstract
The invention provides a method for adjusting the metal wall temperature deviation of a high-temperature reheater of a hedging coal-fired boiler, which comprises the following steps: collecting flue gas components of the cross section of an inlet flue of the SCR system and metal wall temperature data of a high-temperature reheater; flue gas composition testing of the SCR System Inlet flue section, O 2 The opposite-impact burner in the opposite-impact combustion group at the corresponding position with low amount and high CO amount is at the position with insufficient combustion in the hearth, and the opening degree of the external secondary air door is increased; o is 2 The opposite-impact burner in the opposite-impact combustion group at the corresponding position with high CO content and low CO content is at the full combustion position in the hearth, and the opening degree of the external secondary air door is reduced; and acquiring a hedging over-fire air burner in a hedging over-fire air group corresponding to a metal wall temperature over-temperature point or a high point of the high-temperature reheater, and opening the opening degree of a secondary air door in the hedging over-fire air burner and opening the opening degree of a central air in the hedging over-fire air burner. The adjusting method provided by the invention adjusts and controls the positions of the metal wall temperature overtemperature point and the high point of the heating surface of the high-temperature reheater, reduces the heat load deviation of the heating surface and increases the temperature of reheated steam.
Description
Technical Field
The invention belongs to the field of boilers, and particularly relates to a method for adjusting metal wall temperature deviation of a high-temperature reheater of a hedging coal-fired boiler.
Background
The opposed coal-fired boiler is widely applied to domestic 600MW and 1000MW units by virtue of the advantages of the opposed coal-fired boiler in the aspects of heating surface arrangement, combustion economy and the like. With the large-scale transformation of low-nitrogen burners of domestic coal-fired power plants, the problems of upward movement of a hearth flame center, combustion lag, rise of smoke temperature of a horizontal flue and the like caused by a deep staged combustion technology of the low-nitrogen burners lead to the increase of heat absorption capacity of heating surfaces of a high-temperature superheater, a high-temperature reheater and the like of the horizontal flue of a boiler and the rise of metal wall temperature of the heating surfaces. Particularly, under high load, along with the increase of coal feeding quantity, the adaptability of combustion air powder in the boiler is poor, the uneven and insufficient degree of combustion in the boiler is intensified, the deviation of the heat absorption capacity of the heating surface of the horizontal flue is increased, the temperature point of a specific metal wall is over-temperature, and further, the tube burst of the heating surface tube is caused, and the safe operation of a unit is threatened.
Aiming at the problem that the temperature of individual metal wall points of metal pipe walls at the positions of a high-temperature superheater, a high-temperature reheater and the like is over-heated, an operator can only reduce single-side steam temperature parameters integrally in a mode of increasing single-side reduced temperature water flow to achieve the purpose of reducing the wall temperature of the whole metal pipe, the local pipe wall temperature safety is guaranteed, the steam parameters are reduced, the reduced temperature water flow is increased, particularly the reduced temperature water flow of the reheater is increased, the efficiency of a steam turbine is reduced, and the economical efficiency of unit operation is directly influenced.
Over the years, research institutions and related power plants have conducted a series of studies on this problem. The Chinese patent 'method for controlling the metal wall temperature of the superheater of the thermal power generating unit', patent application No. 201410324052.4, optimizes the existing DCS coordination system, gives consideration to the control of the main parameters of the thermal power generating unit and the wall temperature of the superheated metal, and prevents the accident of tube explosion of the superheater. The Chinese patent 'a method for optimizing and adjusting the steam temperature characteristic of a direct-flow boiler for direct pulverized coal combustion', patent application No. 201811053563.1, which aims at optimizing the steam temperature characteristic of the boiler under dynamic fluctuation by controlling and optimizing the existing DCS logic, ensures the economical efficiency of the boiler operation. The Chinese patent 'a high temperature heating surface metal wall temperature regulating system', patent application No. 202020441554.6, designs a set of smoke circulation telescopic smoke purging system, performs smoke purging and cooling aiming at the metal wall temperature high point of a horizontal flue, and controls the wall temperature of a heating surface.
The above patent mainly controls the metal wall temperature of the horizontal flue high-temperature superheater from the angle of DCS control logic optimization and equipment transformation. The research of DCS control logic optimization angle still can not realize the accurate control to the temperature overtemperature point of individual metal wall, and the research of equipment transformation angle can not adapt to the severe environment of horizontal flue high temperature and flue gas erosion and abrasion for a long time by additionally installing a telescopic flue gas purging system through transformation equipment.
Disclosure of Invention
The invention aims to provide a method for adjusting the metal wall temperature deviation of a high-temperature reheater of a hedging coal-fired boiler.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention provides a method for adjusting metal wall temperature deviation of a high-temperature reheater of a hedging coal-fired boiler, which comprises the following steps:
s1, collecting flue gas components of the cross section of an inlet flue of the SCR system and metal wall temperature data of a high-temperature reheater;
s2, testing smoke components of the cross section of the inlet flue of the SCR system to obtain a cross section O 2 Distribution law and CO distribution law based on section O 2 The distribution rule and the CO distribution rule judge the position where the combustion in the hearth is insufficient and the position where the combustion in the hearth is sufficient, wherein:
SCR system inlet cross-section O 2 The opposite-impact burner in the opposite-impact combustion group at the corresponding position with low amount and high CO amount is the position with insufficient combustion in the hearth, and the opening degree of an outer secondary air door of the opposite-impact burner is increased;
SCR systemCross section of mouth O 2 The opposite-impact burner in the opposite-impact combustion group at the corresponding position with high CO content and low CO content is the position with full combustion in the hearth, and the opening degree of an outer secondary air door of the opposite-impact burner is reduced;
s3, based on the metal wall temperature data of the high-temperature reheater, obtaining the opposite over-fire air burner in the opposite over-fire air group corresponding to the metal wall temperature over-temperature point or the high-temperature point of the high-temperature reheater, and executing the steps of: and opening the opening degree of an inner secondary air door of the pair of the overfire air burners and opening the opening degree of central air of the pair of the overfire air burners, wherein the overtemperature point is a temperature value which is more than or equal to a preset alarm value, and the high point is a temperature value which is close to the preset alarm value.
Further, the method further comprises:
s4, comparing the preset temperature threshold range with the reheated steam temperature data of the outlet of the high-temperature reheater after the step S3, and if the reheated steam temperature data does not reach the preset temperature threshold range, readjusting; if the reheated steam temperature data reaches the preset temperature threshold range, adjustment is not needed.
Further, the readjusting includes: aiming at the opposed over-fire air burners in the opposed over-fire air group corresponding to the metal wall temperature over-temperature point or the high point of the high-temperature reheater, keeping the opening degree of the outer secondary air door of the opposed over-fire air burners unchanged, closing the opening degree of the inner secondary air door of the opposed over-fire air burners, and opening the opening degree of the central air of the opposed over-fire air burners.
Further, in the readjustment, the opening degree of the inner secondary air door and the opening degree of the central air of the pair of the overfire air burners are both 0-100%.
Further, comparing the preset temperature threshold range with the reheated steam temperature data of the outlet of the high-temperature reheater obtained in step S4, and if the reheated steam temperature data does not reach the preset temperature threshold range, repeating steps S1-S4; if the reheated steam temperature data reaches the preset temperature threshold range, adjustment is not needed.
Further, in step S3, the method further includes the following operations: and closing the opening degree of the outer secondary air door of the pair of the over-fire air burners.
Further, in step S3, the high point is 95% -100% of the preset alarm value.
Further, in step S2, the opening degree of the outer secondary damper of the opposed burner is 0% to 100%.
Further, in step S3, the opening of the inner secondary air door and the opening of the center air door of the overfire air burner are both 0% to 100%.
Further, in step S1, the cross section refers to a plane perpendicular to the flow direction of the flue gas at the inlet flue of the SCR system, the cross section is provided with a plurality of test points, each opposed burner in the opposed combustion group corresponds to one or more test points, and each opposed air burner in the opposed air-fired group corresponds to one or more test points.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the invention provides a method for adjusting the metal wall temperature deviation of a high-temperature reheater of an offset coal-fired boiler, which is used for adjusting the opening degrees of outer secondary air, inner secondary air and central air of each offset burner in an offset burner group and each offset air-out burner in an offset air group in a differentiated manner and changing the air volume distribution characteristics of the corresponding outer secondary air, inner secondary air and central air, thereby adjusting the positions with uneven and insufficient combustion at individual positions in a hearth, reducing the nonuniformity of the flow of generated high-temperature flue gas and realizing the accurate adjustment and control of the wall temperature point of the metal wall temperature at the individual over-temperature position of the heating surface of the high-temperature reheater.
The method for adjusting the metal wall temperature deviation of the high-temperature reheater of the opposed coal-fired boiler effectively solves the problem that the temperature of the individual metal wall of the high-temperature reheater exceeds the temperature when the opposed coal-fired boiler, particularly a high-load operation runs, reduces the heat load deviation of a heating surface, reduces the flow of desuperheating water, improves the temperature parameter of reheated steam, and ensures the safety and the economical efficiency of the operation of the boiler.
Drawings
FIG. 1 is a schematic structural view of a opposed coal-fired boiler of the present invention;
FIG. 2 is a schematic structural view in the width direction of a opposed coal-fired boiler according to the present invention;
FIG. 3 is a diagram of a metal wall temperature profile of a high temperature reheater along the width direction of a furnace before adjustment;
FIG. 4 is O of the inlet flue cross section of the SCR system before adjustment 2 A distribution rule graph;
FIG. 5 is a diagram showing the CO distribution rule of the cross section of the inlet flue of the SCR system before adjustment;
FIG. 6 is O of the cross section of the inlet flue of the SCR system after adjustment 2 A distribution rule graph;
FIG. 7 is a CO distribution rule diagram of the cross section of the inlet flue of the SCR system after adjustment;
FIG. 8 is a graph of the metal wall temperature distribution of the adjusted high temperature reheater along the width direction of the furnace;
FIG. 9 is a perspective view of the opposed coal-fired boiler of the present invention.
Reference numerals: 1-a boiler body; 2-hedging burner group, 21-first hedging burner, 22-second hedging burner, 23-third hedging burner, 24-fourth hedging burner, 3-hedging over-fire air group, 31-first hedging over-fire air burner, 32-second hedging over-fire air burner, 33-third hedging over-fire air burner, 34-fourth hedging over-fire air burner, 4-screen type superheater, 5-high temperature superheater, 6-high temperature reheater, 7-hedging burner group secondary air inlet box, 8-hedging over-fire air group secondary air inlet box, 9-SCR selective catalytic reduction NO x A desorption reaction device and a 10-SCR system inlet flue section.
Detailed Description
The invention will be further described with reference to examples of embodiments shown in the drawings to which the invention is attached.
First, the boiler structure is explained as follows: the boiler comprises a boiler body 1, a hedging burner group 2, a hedging over-fire air group 3, a platen superheater 4, a high-temperature superheater 5, a high-temperature reheater 6 and SCR selective catalytic reduction NO x The reaction device 9 is removed. The hedging burner group 2 comprises a hedging burner and a hedging burner group secondary air inlet box 7, and the hedging over-fire air group 3 comprises a hedging over-fire air burner and a hedging over-fire air group secondary air inlet box 8.
As shown in fig. 1 and 9, the opposed burner group 2 is provided with three layers, four opposed burners are uniformly arranged on each layer of the front wall and the rear wall along the width direction of the boiler body 1, namely, the opposed burner group 2 is arranged on the front wall and the rear wall, and the four opposed burners on each layer of the opposed burner group 2 on the front wall correspond to the four opposed burners on each layer of the opposed burner group 2 on the rear wall one by one; the opposed over-fire air group 3 is provided with one layer, four opposed over-fire air burners are respectively and evenly arranged on the rear wall of the front wall along the width direction of the boiler body 1, the front wall and the rear wall are provided with the opposed over-fire air group 3, and the four opposed over-fire air burners of the one layer of the opposed over-fire air group 3 on the front wall are in one-to-one correspondence with the four opposed over-fire burners of the one layer of the opposed over-fire air group 3 on the rear wall. The plane seen in fig. 1 and 9 is the a side and the plane not seen is the B side, the width direction of the boiler body 1 refers to the direction of the plane between the a side and the B side, and the width direction of the boiler body 1 is perpendicular to the plane of the a side and the plane of the B side.
In fig. 9, reference numeral 2 denotes a front wall, and a side opposite to the front wall to which reference numeral 2 denotes a rear wall.
Referring to fig. 2, pulverized coal particles in the boiler body 1 start low-nitrogen staged combustion after being supported by secondary air from a secondary air inlet box 7 of the opposed burner in the opposed burner group 2, and are completely burned out after supplementing the secondary air entering the opposed over-fired air group 3 through an opposed over-fired air inlet box 8.
High-temperature flue gas generated after low-nitrogen staged combustion fully absorbs heat through heating surfaces such as a platen superheater 4, a high-temperature superheater 5, a high-temperature reheater 6 and the like in sequence and then enters a vertical flue and a tail flue.
Due to the fact that the amount of the pulverized coal entering the four opposite-direction burners in each layer of opposite-direction burner group 2 is deviated, and the matching of the distribution of the secondary air entering each opposite-direction burner and the amount of the pulverized coal is deviated, combustion heat load deviation exists before each opposite-direction burner of each layer of opposite-direction burner group and high-temperature flue gas flow at different positions in the width direction of the hearth is uneven. When high-temperature flue gas passes through the high-temperature reheater, flue gas flow rates passing through pipe panels at different positions of the heating surface in the width direction are different, so that deviation of heat absorption capacity of the heating surface of the high-temperature reheater is caused, and deviation of wall temperature of a metal pipe panel of the high-temperature reheater is caused.
Especially under the high load, the buggy volume that gets into the furnace burning increases, and this aggravates the inside unevenness of burning of boiler and high temperature flue gas flow's deviation, and high temperature reheater metal tube screen wall temperature deviation further increases, and individual metal wall temperature point temperature overtemperature, the operation personnel are compelled to reduce reheat steam temperature with the mode of throwing the desuperheating water, guarantee local wall temperature safety. At this time, the metal wall temperature distribution of the high-temperature reheater along the width direction of the hearth is shown in fig. 3 (before adjustment, a and b in the drawing are tube panels through which reheat steam is introduced, and a tube panel of the high-temperature reheater are used as research objects of the metal wall temperature distribution of the section of the high-temperature reheater, and the temperature of the steam is high, and the temperature of the tube panel wall is high), as can be known from fig. 3, when a metal wall temperature over-temperature point and a high point are found, an alarm condition is reached, the reheat steam temperature at the outlet of the high-temperature reheater before adjustment is 557 ℃, the preset temperature threshold value is 571 ℃, the reheat steam temperature does not reach the preset temperature threshold value range (the preset temperature threshold value is ± 3 ℃), and the reheat steam temperature is an index of normal operation of the unit, and if the reheat steam temperature does not reach the preset temperature threshold value range, the normal operation of the unit is affected. Therefore, the metal wall temperature of the high-temperature reheater needs to be accurately adjusted, the heat load deviation of a heating surface is reduced, and the reheated steam temperature parameter is improved, so that the safety and the economical efficiency of boiler operation are guaranteed.
Based on the above, the invention provides a method for adjusting the metal wall temperature deviation of a high-temperature reheater of a hedging coal-fired boiler, which comprises the following steps: which comprises the following steps:
s1, collecting flue gas components of the inlet flue section 10 of the SCR system and metal wall temperature data of a high-temperature reheater;
referring to fig. 9, a cross section 10 refers to a plane perpendicular to a flow direction of flue gas at an inlet flue of the SCR system, a plurality of test points are arranged on the cross section 10, each opposed burner in the opposed combustion group 2 corresponds to one or more test points, and each opposed air-over burner in the opposed air-over group 3 corresponds to one or more test points.
S2, testing the smoke components of the inlet flue section 10 of the SCR system to obtain a section O 2 Distribution law and CO distribution law based on section O 2 The distribution rule and the CO distribution rule are used for judging the position with insufficient combustion in the hearth and the position with sufficient combustion in the hearth, so that convenience is brought toAdjust towards combustor group 2 and to dashing over fire air group 3, wherein:
SCR system inlet cross-section O 2 If the opposed burners in the opposed combustion group at the corresponding positions with low amount and high CO amount are in insufficient combustion in the hearth, opening the outer secondary air door of the opposed burners, reducing ventilation resistance and increasing the air intake of secondary air outside the opposed burners at the positions; when insufficient combustion occurs in the hearth, the metal wall temperature of the heating surface of the high-temperature reheater has overtemperature points and high points, and the overtemperature points and the high points need to be adjusted.
SCR system inlet cross section O 2 And the opposed burners in the opposed combustion group at the corresponding positions of high CO content and low CO content are fully combusted in the hearth, the opening degree of the outer secondary air door of the opposed burners is reduced, the ventilation resistance is increased, and the air intake of the secondary air outside the opposed burners at the positions is reduced.
In fig. 1 and 2, each layer of the opposed burner group 2 is sequentially provided with a first opposed burner 21, a second opposed burner 22, a third opposed burner 23 and a fourth opposed burner 24, and the opposed burners of each layer of the opposed burner group 2 are in one-to-one correspondence from top to bottom.
In fig. 4, a1, a2, A3 and a4 correspond to the first opposed burners 21, a5, a6, a7, A8 and a9 correspond to the second opposed burners 22, B1, B2, B3 and B4 correspond to the third opposed burners 23, and B5, B6, B7, B8 and B9 correspond to the fourth opposed burners 24.
In fig. 5, a1, a2, A3 and a4 correspond to the number 21 opposed burners, a5, a6, a7, A8 and a9 correspond to the number 22 opposed burners, B1, B2, B3 and B4 correspond to the number 23 opposed burners, and B5, B6, B7, B8 and B9 correspond to the number 24 opposed burners.
As can be seen from FIGS. 4 and 5, the SCR system inlet cross-section O 2 The volume is low, the high correspondent position's of CO volume hedge combustor in the hedge combustion group is first hedge combustor 21 and fourth hedge combustor 24, need carry out corresponding adjustment to first hedge combustor 21 and fourth hedge combustor 24, during the adjustment, first hedge combustor 21 and fourth hedge combustor 24 in the hedge combustion group 2 of front wall and first hedge combustor 21 and fourth hedge combustor 24 synchronous regulation in the hedge combustion group 2 of back wall.
SCR system inlet cross-section O 2 The high, the low opposed firing combustor in the opposed firing group of corresponding position of CO volume is second opposed firing combustor 22 and third opposed firing combustor 23, need to carry out corresponding adjustment to second opposed firing combustor 22 and third opposed firing combustor 23, and during the adjustment, second opposed firing combustor 22 and third opposed firing combustor 23 in the opposed firing group 2 of front wall and second opposed firing combustor 22 and third opposed firing combustor 23 in the opposed firing group 2 of back wall synchronous control.
In step S2, the opening of the outer secondary damper of the opposed burner is 0% to 100%, where 0% is fully closed and 100% is fully open.
By step S2, the combustion uniformity adjustment in the furnace width direction is achieved.
S3, based on the metal wall temperature data of the high-temperature reheater, obtaining the opposite-burnout air burner in the opposite-burnout air group corresponding to the metal wall temperature overtemperature point or the high point of the high-temperature reheater, and executing the steps of: opening the inner secondary air door of the pair of over-fired burners to reduce the ventilation resistance of the inner secondary air and increase the air quantity of the inner secondary air; opening the central air opening of the pair of over-fired burners, reducing the ventilation resistance of the central air, increasing the air quantity of the central air, and taking the inner secondary air and the central air as direct-current cooling air to accurately adjust and control the positions of the metal wall temperature over-temperature point and the high point of the high-temperature reheater. During adjustment, the opposed over-fire air burners in the opposed over-fire air groups of the front wall and the opposed over-fire air burners in the opposed over-fire air groups of the corresponding rear wall are synchronously adjusted.
The over-temperature point is a temperature value which is greater than or equal to a preset alarm value, the high point is a temperature value which is close to the preset alarm value, and the high point is preferably 95% -100% of the preset alarm value.
The opposed over-fire air group 3 comprises a first opposed over-fire air burner 31, a second opposed over-fire air burner 32, a third opposed over-fire air burner 33 and a fourth opposed over-fire air burner 34 which are sequentially arranged, and four opposed over-fire air burners of the opposed over-fire air group 3 of the front wall are in one-to-one correspondence with four opposed over-fire burners of the opposed over-fire air group 3 of the rear wall. In fig. 3, 3 high re-outlets to 20 high re-outlets correspond to the first pair of the overfire air burners 31, 23 high re-outlets to 41 high re-outlets correspond to the second pair of the overfire air burners 32, 43 high re-outlets to 59 high re-outlets correspond to the third pair of the overfire air burners 33, and 63 high re-outlets to 79 high re-outlets correspond to the fourth pair of the overfire air burners 34. As can be seen from fig. 3, the metal wall temperature high points occur in the first pair of overfire air burners 31 and the fourth pair of overfire air burners 34, and these two pairs of overfire air burners are adjusted, and at this time, the first pair of overfire air burners 31 and the fourth pair of overfire air burners 34 of the front wall opposed overfire air group 3, and the first pair of overfire air burners 31 and the fourth pair of overfire air burners 3 of the rear wall opposed overfire air group 3 are synchronously adjusted.
In step S3, the opening of the inner secondary air door and the opening of the central air of the pair of overfire air burners are both 0% to 100%, where 0% is fully closed and 100% is fully open.
Optionally, in step S3, the method further includes the following operations: the opening degree of an outer secondary air door of the pair of the overfire air burners is reduced, the ventilation resistance of the outer secondary air is increased, and the air quantity of the outer secondary air is reduced.
And step S3, taking each counter-burnout air burner of the counter-burnout air group 3 as a main means for accurately adjusting the metal wall temperature of the high-temperature reheater.
Further, the method also comprises the following steps:
s4, comparing the preset temperature threshold range with the reheated steam temperature data of the outlet of the high-temperature reheater after the step S3, and if the reheated steam temperature data does not reach the preset temperature threshold range, readjusting; if the reheated steam temperature data reaches the preset temperature threshold range, adjustment is not needed. Preferably, the preset temperature threshold range is the preset temperature threshold ± 3 ℃.
Specifically, the readjusting includes: aiming at the opposite burnout air burners in the opposite burnout air group corresponding to the metal wall temperature overtemperature point or the high point of the high-temperature reheater, keeping the opening degree of the outer secondary air door of the opposite burnout air burners unchanged, closing the opening degree of the inner secondary air door of the opposite burnout air burners, increasing the ventilation resistance of the inner secondary air door and reducing the inner secondary air quantity; and opening the central air opening of the pair of over-fire air burners, reducing the ventilation resistance of the central air, and continuously increasing the central air quantity so as to accurately adjust and control the temperature of the metal wall temperature over-temperature point of the high-temperature reheater by the central air with stronger cooling air effect.
In the readjusting step, the opening degree of the inner secondary air door and the opening degree of the central air of the pair of after-combustion air burners are both 0-100%, wherein 0% is fully closed, and 100% is fully open.
After the step S4, comparing the preset temperature threshold range with the reheated steam temperature data at the outlet of the high-temperature reheater after the step S4, and if the reheated steam temperature data does not reach the preset temperature threshold range, repeating the steps S1-S4; if the reheated steam temperature data reaches the preset temperature threshold range, no adjustment is needed,
when the steps S1-S4 are repeated, the external secondary air, the internal secondary air and the opening degree of the central air door of the pair of the overfire air burners are compared, then the influence on the metal wall temperature of the high-temperature reheater in the area with the excess temperature point or the similar high point is compared, according to the change condition of the temperature points of other metal walls in the area, the external secondary air, the internal secondary air and the central air door of other pairs of the overfire air burners are continuously adjusted in small scale according to the steps S1-S4 (because the metal wall temperature high point is expected to be reduced after adjustment, the temperature points of adjacent metal walls may also rise to become new high points, aiming at the new high points, the adjustment of the second pair of the overfire air burners adjacent to the originally adjusted first pair of the overfire air burners and/or the adjustment of the third pair of the overfire air burners adjacent to the originally adjusted fourth pair of the overfire air burners) are possibly required, so as to realize the precise adjustment and control of the wall temperature points at the respective excess temperature positions of the metal walls of the high-temperature reheater on the heating surfaces of the respective overfire burners, and the uniformity of the metal wall temperature distribution of the whole high-temperature reheater is improved.
Or when the steps S1-S4 are repeated, all the hedging burners and all the hedging over-fired air burners are adjusted according to the steps S1-S4 until the metal wall temperature of the adjusted high-temperature reheater is distributed uniformly without an over-temperature point and a high point, and the reheated steam temperature reaches the preset temperature threshold range.
After the adjustment is carried out by using the method for adjusting the metal wall temperature deviation of the high-temperature reheater of the opposed coal-fired boiler, the inlet smoke of the SCR system is collectedFlue gas composition of flue section, metal wall temperature data of high-temperature reheater, and flue section O of inlet of SCR system 2 Distribution law referring to FIG. 6, distribution law of CO at cross section of inlet flue of SCR system referring to FIG. 7, O of each opposed burner 2 The quantity distribution is relatively uniform, the CO quantity of most measuring points is zero, the high CO quantity is less, the high CO quantity data is smaller, and the combustion of the opposed firing burner is sufficient.
The metal wall temperature distribution of the adjusted high-temperature reheater along the width direction of the furnace is shown in fig. 8, in the figure, a and b are tube panels through which reheat steam passes, and are respectively the same as the tube panels a and b in fig. 3, 3 high-reoutput-to-high-reoutput-20 tubes correspond to the first pair of overfire air burners 31, 23 high-reoutput-to-high-reoutput-41 tubes correspond to the second pair of overfire air burners 32, 43 high-reoutput-to-59 tubes correspond to the third pair of overfire air burners 33, and 63 high-reoutput-to-high-reoutput-79 tubes correspond to the fourth pair of overfire air burners 34. As can be seen from the figure: the metal wall temperature over-temperature point and the metal wall temperature high point are not existed, the metal wall temperature value is uniform, the reheating temperature is 572 ℃, the preset temperature threshold value is 571 ℃, the reheating steam temperature reaches the preset temperature threshold value range (the preset temperature threshold value is +/-3 ℃), and the full combustion of the counter-burst air burner can be seen.
The method for adjusting the metal wall temperature deviation of the high-temperature reheater of the hedging coal-fired boiler provided by the invention can be used for differentially adjusting the opening degrees of the outer secondary air, the inner secondary air and the central air of each hedging burner in the hedging burner group and each hedging over-fired air burner in the hedging burner group, and changing the air volume distribution characteristics of the corresponding outer secondary air, inner secondary air and central air, so that the positions with uneven and insufficient combustion at certain positions in a hearth can be adjusted, the nonuniformity of the generated high-temperature flue gas flow can be reduced, and the accurate adjustment and control of the wall temperature point of the metal wall temperature at certain over-temperature positions of the heating surface of the high-temperature reheater can be realized.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (8)
1. A method for adjusting the metal wall temperature deviation of a high-temperature reheater of a hedging coal-fired boiler is characterized by comprising the following steps: the method comprises the following steps:
s1, collecting flue gas components of the cross section of an inlet flue of the SCR system and metal wall temperature data of a high-temperature reheater;
s2, testing smoke components of the cross section of the inlet flue of the SCR system to obtain a cross section O 2 Distribution law and CO distribution law based on section O 2 The distribution rule and the CO distribution rule judge the position where the combustion in the hearth is insufficient and the position where the combustion in the hearth is sufficient, wherein:
SCR system inlet cross section O 2 The opposite-impact burner in the opposite-impact combustion group at the corresponding position with low amount and high CO amount is the position with insufficient combustion in the hearth, and the opening degree of an outer secondary air door of the opposite-impact burner is increased;
SCR system inlet cross section O 2 The opposite-impact burner in the opposite-impact combustion group at the corresponding position with high CO content and low CO content is the position with full combustion in the hearth, and the opening degree of an outer secondary air door of the opposite-impact burner is reduced;
s3, based on the metal wall temperature data of the high-temperature reheater, obtaining the opposite over-fire air burner in the opposite over-fire air group corresponding to the metal wall temperature over-temperature point or the high-temperature point of the high-temperature reheater, and executing the steps of: opening an inner secondary air door of the pair of the after-combustion air burners and opening a central air opening of the pair of the after-combustion air burners, wherein the over-temperature point is a temperature value which is more than or equal to a preset alarm value, and the high point is a temperature value which is close to the preset alarm value;
the method further comprises the following steps:
s4, comparing the preset temperature threshold range with the reheated steam temperature data of the outlet of the high-temperature reheater after the step S3, and if the reheated steam temperature data does not reach the preset temperature threshold range, readjusting; if the reheated steam temperature data reach the preset temperature threshold range, adjustment is not needed;
the readjustment includes: aiming at the opposed over-fire air burners in the opposed over-fire air group corresponding to the metal wall temperature over-temperature point or the high point of the high-temperature reheater, keeping the opening degree of the outer secondary air door of the opposed over-fire air burners unchanged, closing the opening degree of the inner secondary air door of the opposed over-fire air burners, and opening the opening degree of the central air of the opposed over-fire air burners.
2. The method for adjusting the metal wall temperature deviation of a high-temperature reheater of a opposed coal-fired boiler according to claim 1, wherein: in the readjustment, the opening degree of the inner secondary air door and the opening degree of the central air of the pair of the overfire air burners are both 0-100 percent.
3. The method for adjusting the metal wall temperature deviation of a high-temperature reheater of a opposed coal-fired boiler according to claim 1, characterized in that: comparing the preset temperature threshold range with the reheated steam temperature data of the outlet of the high-temperature reheater obtained in the step S4, and if the reheated steam temperature data does not reach the preset temperature threshold range, repeating the steps S1-S4; if the reheated steam temperature data reaches the preset temperature threshold range, adjustment is not needed.
4. The method for adjusting the metal wall temperature deviation of a high-temperature reheater of a opposed coal-fired boiler according to claim 1, characterized in that: in step S3, the method further includes the following operations: and closing the opening degree of the outer secondary air door of the pair of the over-fire air burners.
5. The method for adjusting the metal wall temperature deviation of a high-temperature reheater of a opposed coal-fired boiler according to claim 1, characterized in that: in step S3, the high point is 95% -100% of the preset alarm value.
6. The method for adjusting the metal wall temperature deviation of a high-temperature reheater of a opposed coal-fired boiler according to claim 1, wherein: in step S2, the opening of the outer secondary damper of the opposed burner is 0% to 100%.
7. The method for adjusting the metal wall temperature deviation of a high-temperature reheater of a opposed coal-fired boiler according to claim 1, characterized in that: in step S3, the opening of the inner secondary air door and the opening of the central air door of the overfire air burner are both 0% to 100%.
8. The method for adjusting the metal wall temperature deviation of a high-temperature reheater of a opposed coal-fired boiler according to claim 1, characterized in that: in step S1, the cross section is a plane perpendicular to the flow direction of the flue gas at the inlet flue of the SCR system, a plurality of test points are provided on the cross section, each opposed burner in the opposed combustion group corresponds to one or more test points, and each opposed overfire air burner in the opposed combustion group corresponds to one or more test points.
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| CN111256109A (en) * | 2020-02-20 | 2020-06-09 | 苏州西热节能环保技术有限公司 | Method for relieving temperature deviation of tube wall of opposed coal-fired boiler |
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| JPS6488005A (en) * | 1987-05-28 | 1989-04-03 | Babcock Hitachi Kk | Method of operating once-through boiler |
| JPH0626604A (en) * | 1992-07-13 | 1994-02-04 | Babcock Hitachi Kk | Boiler device having water-cooled wall temperature control means |
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