CN113339782B - Adjustment method for metal wall temperature deviation of high-temperature reheater of hedging coal-fired boiler - Google Patents

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

A method for adjusting the metal wall temperature deviation of a high temperature reheater of a hedging coal-fired boiler

technical field

The invention belongs to the field of boilers, and in particular relates to a method for adjusting the temperature deviation of a metal wall of a high-temperature reheater of a hedging coal-fired boiler.

Background technique

Hedging coal-fired boilers are widely used in domestic 600MW and 1000MW units by virtue of their advantages in heating surface layout and combustion economy. With the large-scale transformation of low-nitrogen burners in domestic coal-fired power plants, the deep-stage combustion technology of low-nitrogen burners has caused problems such as upward movement of the furnace flame center, combustion lag, and rising flue temperature in the horizontal flue. The heat absorption of the heating surface such as the high temperature superheater and the high temperature reheater increases, and the temperature of the metal wall of the heating surface increases. Especially under high load, with the increase of coal supply, the adaptability of combustion air powder inside the boiler becomes poor, the degree of uneven and insufficient combustion in the furnace intensifies, and the deviation of heat absorption on the heating surface of the horizontal flue increases accordingly. Individual metal wall temperature points are overheated, which in turn causes the pipes on the heating surface to burst, threatening the safe operation of the unit.

In view of the problem of over-temperature of individual metal wall temperature points on the metal pipe wall of the high temperature superheater, high temperature reheater and other positions, the operator can only reduce the one-side steam temperature parameter as a whole by increasing the flow rate of one-side desuperheating water to To achieve the purpose of reducing the temperature of the entire metal tube wall, and to ensure the safety of the local tube wall temperature, but reducing the steam parameters and increasing the desuperheating water flow, especially the reheater desuperheating water flow, will reduce the efficiency of the steam turbine and directly affect the The economy of unit operation.

Over the years, research institutions and related power plants have conducted a series of studies on this issue. The Chinese patent "Control Method of Metal Wall Temperature of Thermal Power Unit Superheater", patent application number 201410324052.4, optimizes the existing DCS coordination system, taking into account the main parameters of thermal power units and the control of overheated metal wall temperature to prevent superheater tube burst accidents. The Chinese patent "A method for optimizing and adjusting the steam temperature characteristics of a straight-through pulverized coal combustion once-through furnace", patent application number 201811053563.1, through the control and optimization of the existing DCS logic, focusing on optimizing the steam temperature characteristics under the dynamic fluctuation of the boiler to ensure the operation of the boiler economy. Chinese patent "A high temperature heating surface metal wall temperature adjustment system", patent application number 202020441554.6, designed a set of flue gas circulation telescopic flue gas purging system, which is designed for flue gas purging at high temperature points of horizontal flue metal wall Cool down and control the wall temperature of the heating surface.

The above patents mainly control the metal wall temperature of the horizontal flue high temperature superheater from the perspective of DCS control logic optimization and equipment transformation. The DCS control logic optimization angle research still cannot achieve the precise control of the individual metal wall temperature over-temperature points, the equipment transformation angle research By retrofitting the equipment with a telescopic flue gas purging system, it cannot adapt to the high temperature of the horizontal flue and flue gas scouring for a long time. Wear harsh environments.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for adjusting the temperature deviation of the metal wall of the high temperature reheater of a hedging coal-fired boiler.

To achieve the above object, the technical scheme adopted in the present invention is:

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:

S1. Collect the flue gas composition at the inlet flue section of the SCR system and the metal wall temperature data of the high temperature reheater;

S2. Test the flue gas composition of the flue section at the inlet of the SCR system, and obtain the O ₂ distribution law and CO distribution law of the cross section. Then, based on the cross section O ₂ distribution law and CO distribution law, determine the position of insufficient combustion in the furnace and the furnace chamber. A fully burnt position in which:

If the counter-combustion burner in the counter-combustion group at the position corresponding to the low O ₂ content and the high CO level at the inlet section of the SCR system is the position where the combustion in the furnace is insufficient, the opening of the outer secondary air door of the counter-burner should be enlarged;

If the counter-burner in the counter-combustion group at the position corresponding to the high O ₂ content and the low CO level at the inlet section of the SCR system is the position where the combustion in the furnace is sufficient, the opening of the outer secondary air door of the counter-burner should be reduced;

S3. Based on the metal wall temperature data of the high temperature reheater, obtain the hedging burnout air burner in the hedging burnout air group corresponding to the over-temperature point or high point of the metal wall temperature of the high temperature reheater, and the execution includes: turning on the hedging burnout The opening degree of the inner secondary air door of the exhausted air burner, and the opening degree of the center air of the counteracting exhausted air burner. The over-temperature point is the temperature value greater than or equal to the preset alarm value, and the high point is close to the preset alarm value. The temperature value of the value.

Further, the method also includes:

S4. Compare the preset temperature threshold range with the reheated steam temperature data at the outlet of the high temperature reheater after step S3. If the reheated steam temperature data does not reach the preset temperature threshold range, adjust again; if the reheated steam temperature data reaches The preset temperature threshold range does not need to be adjusted.

Further, the re-adjustment includes: maintaining the outer secondary damper of the over-burning air burner in the over-burning air group corresponding to the over-temperature point or high point of the metal wall temperature of the high-temperature reheater. The opening degree of the hedging exhaust air burner remains unchanged, close the opening degree of the inner secondary air door of the hedging exhaust air burner, and open the central air opening degree of the hedging exhaust air burner.

Further, in the re-adjustment, the opening degree of the inner secondary air door and the opening degree of the center air of the counter-overburned air burner are both 0% to 100%.

Further, compare the preset temperature threshold range with the reheated steam temperature data at the outlet of the high temperature reheater after step S4, if the reheated steam temperature data does not reach the preset temperature threshold range, repeat steps S1-S4; When the hot steam temperature data reaches the preset temperature threshold range, no adjustment is required.

Further, in step S3, the following operation is further included: the opening degree of the outer secondary air door of the counteracting overburning air burner is reduced.

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 air door of the counteracting burner is 0% to 100%.

Further, in step S3, the opening degree of the inner secondary air door and the opening degree of the center air of the over-burning air burner are both 0% to 100%.

Further, in step S1, the cross section refers to a plane at the inlet flue of the SCR system that is perpendicular to the flow direction of the flue gas, a plurality of test points are set on the cross section, and each of the hedging burners in the hedging combustion group is connected to one or more test points. Each of the counteracting overburning air burners of the counteracting overburning air group corresponds to one or more test points.

Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art: the method for adjusting the metal wall temperature deviation of the high-temperature reheater of a hedging coal-fired boiler provided by the present invention can differentially adjust the hedging combustion of each branch in the hedging burner group. The opening degree of the outer secondary air, inner secondary air and central air of each hedging exhaust air burner of the burner and the hedging exhaust air group is changed, and the air volume distribution of the corresponding outer secondary air, inner secondary air and central air is changed. In order to adjust the uneven and insufficient combustion of individual positions in the furnace, reduce the non-uniformity of the generated high-temperature flue gas flow, and realize the control of the wall temperature points of the individual over-temperature positions of the metal wall temperature of the heating surface of the high-temperature reheater. Precise adjustment and control.

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 effectively alleviate the problem of over-temperature of the individual metal wall temperature points of the high-temperature reheater encountered by the hedging coal-fired boiler, especially during high-load operation, and reduce the heat exposure. Surface heat load deviation, reduce desuperheating water flow, improve reheat steam temperature parameters, and ensure the safety and economy of boiler operation.

Description of drawings

Accompanying drawing 1 is the structural representation of the hedging coal-fired boiler of the present invention;

Accompanying drawing 2 is the structural schematic diagram of the width direction of the hedging coal-fired boiler of the present invention;

Accompanying drawing 3 is the metal wall temperature distribution diagram along the furnace width direction of the high temperature reheater before adjustment;

Accompanying drawing 4 is the O ₂ distribution regularity diagram of the SCR system inlet flue section before adjustment;

Accompanying drawing 5 is the CO distribution regularity diagram of SCR system inlet flue duct section before adjustment;

Accompanying drawing ₆ is the O distribution law diagram of the cross section of the inlet flue of the SCR system after adjustment;

Accompanying drawing 7 is the CO distribution regularity diagram of the inlet flue section of SCR system after adjustment;

Accompanying drawing 8 is the metal wall temperature distribution diagram along the furnace width direction of the high temperature reheater after adjustment;

FIG. 9 is a perspective view of the hedging coal-fired boiler of the present invention.

Reference numerals: 1- boiler body; 2- hedge burner group, 21- first offset burner, 22- second offset burner, 23- third offset burner, 24- fourth offset burner, 3- Hedge overfire air group, 31-first hedge overfire air burner, 32-second hedge overfire air burner, 33-third hedge overfire air burner, 34-fourth hedge overfire air burner, 4-screen superheater, 5-high temperature superheater, 6-high temperature reheater, 7-secondary air intake air box of hedging burner group, 8-secondary air intake air box of hedging exhaust air group, 9-SCR selectivity Catalytic reduction _NOx removal reaction device, 10-SCR system inlet flue section.

Detailed ways

The present invention will be further described below with reference to the embodiments shown in the accompanying drawings.

First, the structure of the boiler is described as follows: the boiler includes a boiler body 1, a set of counter-burning burners, a set of counter-burning air 3, a panel superheater 4, a high-temperature superheater 5, a high-temperature reheater 6, and SCR selective catalytic reduction. NO _x removal reaction device 9 . The hedging burner group 2 includes a hedging burner and a secondary air inlet box 7 of the hedging burner group, and the hedging burner group 3 includes a hedging burner and a secondary air inlet box 8 of the hedging burner group.

As shown in Fig. 1 and Fig. 9 , the set of hedging burners 2 is set in three layers, and four sets of hedging burners are evenly arranged on each floor along the front wall and the rear wall along the width direction of the boiler body 1, that is, the set of hedging burners 2 is set on both the front wall and the rear wall. , the four hedging burners on each layer of the hedging burner group 2 on the front wall are in one-to-one correspondence with the four hedging burners on each layer in the hedging burner group 2 on the rear wall; On the first floor of the boiler body 1, the front wall and the rear wall are evenly arranged with four hedging exhaust air burners. The front wall and the rear wall are equipped with a hedging exhaust air group 3, and the front wall is on the first floor of the hedging exhaust air group 3. The four hedging over-burning air burners are in one-to-one correspondence with the four hedging over-burning air burners on the first floor of the rear wall hedging over-burning air group 3 . The side seen in Figures 1 and 9 is the A side, and the invisible side 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 A side. The plane where the side is located, and the plane where the B side is located.

In FIG. 9, the front wall indicated by mark 2 is the front wall, and the side opposite to the front wall indicated by mark 2 is the rear wall.

Referring to FIG. 2 , the pulverized coal particles in the boiler body 1 start low-nitrogen staged combustion after being assisted by the secondary air from the secondary air intake box 7 of the counter-burner in the counter-burner group 2 , and are burnt out by the counter-burning air. The secondary air from the secondary air inlet box 8 enters the hedging exhaust air group 3 and is completely burned out after supplementary combustion.

The high-temperature flue gas generated by the low-nitrogen staged combustion passes through the screen superheater 4, the high-temperature superheater 5 and the high-temperature reheater 6 and other heating surfaces in turn to fully absorb heat and then enter the vertical flue and the tail flue.

Due to the deviation of the amount of pulverized coal entering the four hedging burners in the hedging burner group 2 of each layer, and the corresponding mismatch between the distribution of the secondary air entering each hedging burner and the amount of pulverized coal, resulting in the hedging of each layer Before each offset burner in the burner group, there is a deviation of combustion heat load and uneven flow of high-temperature flue gas at different positions along the width direction of the furnace. When the high-temperature flue gas passes through the high-temperature reheater, the flue gas flow through the tube screen at different positions of the heating surface in the width direction is different, which leads to the deviation of the heat absorption of the heating surface of the high-temperature reheater, causing the metal tube of the high-temperature reheater. Screen wall temperature deviation.

Especially under high load, the amount of pulverized coal entering the furnace increases, which aggravates the non-uniformity of combustion inside the boiler and the deviation of high-temperature flue gas flow. When the temperature of the wall temperature point is too high, the operator is forced to reduce the temperature of the reheated steam by throwing in desuperheated water to ensure the safety of the local wall temperature. At this time, the metal wall temperature distribution of the high temperature reheater along the width direction of the furnace is shown in Figure 3 (before adjustment, a and b in the figure are the tube panels for reheating steam, and the high temperature reheater a tube panel and b The tube panel is used as the research object of the metal wall temperature distribution of the high temperature reheater section. The steam temperature is high, and the tube panel wall temperature is high). As can be seen from Figure 3, there have been over-temperature and high points of the metal wall temperature, and the alarm condition has been reached. The reheated steam temperature at the outlet of the high temperature reheater before adjustment is 557°C, the preset temperature threshold is 571°C, and the reheated steam temperature does not reach the preset temperature threshold range (preset temperature threshold ±3°C), the reheated steam temperature It is an indicator of the normal operation of the unit. If the reheated steam temperature does not reach the preset temperature threshold range, the normal operation of the unit will be affected. Therefore, it is necessary to precisely adjust the metal wall temperature of the high temperature reheater, reduce the heat load deviation of the heating surface, and improve the reheat steam temperature parameters to ensure the safety and economy of the boiler operation.

Based on this, the present invention provides a method for adjusting the metal wall temperature deviation of a high-temperature reheater of a hedging coal-fired boiler. The method includes the following steps:

S1. Collect the flue gas composition and the metal wall temperature data of the high temperature reheater at the inlet flue section 10 of the SCR system;

Referring to FIG. 9 , section 10 refers to a plane at the inlet flue of the SCR system that is perpendicular to the flow direction of the flue gas, a plurality of test points are set on section 10, and each counter-burner in the counter-combustion group 2 corresponds to one or more test points , each of the hedging overburning air burners of the hedging overburning air group 3 corresponds to one or more test points.

S2. Test the flue gas composition of the SCR system inlet flue section 10, and obtain the O ₂ distribution law and CO distribution law of the section, and then judge the position of insufficient combustion in the furnace based on the O ₂ distribution law and CO distribution law of the section. The position of sufficient combustion in the furnace is convenient for adjusting the rush burner group 2 and the hedging exhaust air group 3, wherein:

The counter-burner in the counter-combustion group at the position corresponding to the low O ₂ content and the high CO content at the inlet section of the SCR system is the position where the combustion in the furnace is not sufficient, so open the outer secondary damper of the counter-burner to reduce ventilation. Resistance, increase the amount of secondary air intake outside the hedging burner at this position; when the combustion in the furnace is insufficient, the metal wall temperature of the heating surface of the high temperature reheater appears over-temperature and high points, which need to be adjusted.

The hedging burner in the hedging combustion group in the position corresponding to the high O ₂ content and the low CO content at the inlet section of the SCR system is the position where the combustion is sufficient in the furnace. Reduce the secondary air intake air volume outside the hedging burner at this position.

In FIG. 1 and FIG. 2 , each layer of the hedging burner group 2 is sequentially provided with a first hedging burner 21 , a second hedging burner 22 , a third hedging burner 23 and a fourth hedging burner 24 . The hedging burners of each layer of group 2 correspond one by one.

In FIG. 4 , A1, A2, A3, and A4 correspond to the first hedging burner 21, A5, A6, A7, A8, and A9 correspond to the second hedging burner 22, and B1, B2, B3, and B4 correspond to the third hedging burner 23 , B5 , B6 , B7 , B8 , and B9 correspond to the fourth hedging burner 24 .

In Figure 5, A1, A2, A3, and A4 correspond to No. 21 hedging burners; A5, A6, A7, A8, and A9 correspond to No. 22 hedging burners; B1, B2, B3, and B4 correspond to No. 23 hedging burners; B5, B6, B7, B8, B9 correspond to No. 24 hedging burners.

It can be seen from Fig. 4 and Fig. 5 that the hedging burners in the hedging combustion group at the positions corresponding to the low O ₂ amount and the high CO amount at the inlet cross-section of the SCR system are the first offset burner 21 and the fourth hedge burner 24. The offset burner 21 and the fourth offset burner 24 are adjusted accordingly. During the adjustment, the first offset burner 21 and the fourth offset burner 24 in the offset combustion group 2 on the front wall and the first offset burner 24 in the offset combustion group 2 on the rear wall The offset burner 21 and the fourth offset burner 24 are adjusted synchronously.

The counteracting burners in the counteracting combustion group at the positions corresponding to the high O ₂ content and the low CO amount at the inlet section of the SCR system are the second countering burner 22 and the third countering The burners 23 are adjusted accordingly. During the adjustment, the second and third hedging burners 22 and 23 in the hedging combustion group 2 of the front wall are opposed to the second and third hedging burners 22 and 23 in the hedging and burning group 2 of the rear wall. The burners 23 are adjusted synchronously.

In step S2, the opening degree of the outer secondary air door of the counteracting burner is 0% to 100%, wherein 0% is fully closed and 100% is fully open.

Through step S2, the combustion uniformity adjustment along the width direction of the furnace is realized.

S3. Based on the metal wall temperature data of the high temperature reheater, obtain the hedging burnout air burner in the hedging burnout air group corresponding to the over-temperature point or high point of the metal wall temperature of the high temperature reheater, and the execution includes: turning on the hedging burnout The opening of the inner secondary air door of the exhausted air burner reduces the ventilation resistance of the inner secondary air and increases the air volume of the inner secondary air; open the central air opening of the hedging exhaust air burner to reduce the ventilation resistance of the central air , increase the central air volume, and use the internal secondary air and central air as the DC cooling air to accurately adjust and control the position of the over-temperature and high points of the metal wall temperature of the high-temperature reheater. During the adjustment, the counteracting overfire air burners in the counteracting overfire air group of the front wall and the counteracting overburning air burners in the counteracting overfire air group of the corresponding rear wall are adjusted synchronously.

The over-temperature point is a temperature value greater than or equal to the preset alarm value, the high point is a temperature value close to the preset alarm value, and the high point is preferably 95%-100% of the preset alarm value.

The hedging overfire air group 3 includes a first hedging overburning air burner 31 , a second hedging overburning air burner 32 , a third hedging overburning air burner 33 , and a fourth hedging overburning air burner 34 , which are arranged in sequence. The four counter-burnout burners of the counter-burnout air group 3 on the front wall are in one-to-one correspondence with the four counter-fire-out burners of the counter-fire air group 3 on the rear wall. In FIG. 3 , 3 pieces of high re-outlet to 20 pieces of high re-outlet correspond to the first hedging overfire air burner 31 , 23 pieces of high re-outlet to 41 pieces of high re-outlet correspond to the second hedging overfire air burner 32 , and high re-outlet 43 The 59 slices to the high re-outlet correspond to the third hedging overfire air burner 33 , and the 63 slices to the high re-exit 79 slices correspond to the fourth hedging overfire air burner 34 . It can be seen from FIG. 3 that the high temperature of the metal wall appears in the first counter-overfire burner 31 and the fourth counter-overflow burner 34, so these two counter-overflow burners are adjusted. The first counter-overfire burner 31 and the fourth counter-overfire burner 34 of the counter-overflow air group 3 of the wall, and the first counter-over-fire air burner 31 and the fourth counter-overflow burner 34 of the counter-overflow group 3 of the rear wall. The four-hedged overburning air burners 3 are synchronously adjusted.

In step S3, the opening degree of the inner secondary air valve and the opening degree of the center air of the counter-overfire air burner are both 0% to 100%, wherein 0% is fully closed and 100% is fully open.

Optionally, in step S3, the following operations are further included: reducing the opening of the outer secondary air door of the hedging overburning air burner, increasing the ventilation resistance of the outer secondary air, and reducing the air volume of the outer secondary air.

In step S3, each of the hedging overburning air burners of the overburning overheating group 3 is used as the main means for accurately adjusting the metal wall temperature of the high temperature reheater.

Further, the method also includes the following:

S4. Compare the preset temperature threshold range with the reheated steam temperature data at the outlet of the high temperature reheater after step S3. If the reheated steam temperature data does not reach the preset temperature threshold range, adjust again; if the reheated steam temperature data reaches The preset temperature threshold range does not need to be adjusted. Preferably, the preset temperature threshold range is the preset temperature threshold ±3°C.

Specifically, the readjustment includes: maintaining the outer secondary air damper of the overfire air burner in the overfire air group corresponding to the over-temperature point or high point of the metal wall temperature of the high-temperature reheater, maintaining the overfire air burner. The opening of the hedging exhaust air burner remains unchanged, close the opening of the inner secondary air door of the hedging exhaust air burner, increase the ventilation resistance of the inner secondary air door, and reduce the inner secondary air volume; and open the hedging exhaust air burner. The opening of the central air reduces the ventilation resistance of the central air, continues to increase the air volume of the central air, and uses the central air with stronger cooling air effect to precisely adjust and control the temperature of the over-temperature point of the metal wall temperature of the high-temperature reheater.

In the above readjustment step, the opening degree of the inner secondary air valve and the opening degree of the center air of the counter-overfire air burner are both 0% to 100%, wherein 0% is fully closed and 100% is fully open.

After performing step S4, compare the preset temperature threshold range with the reheated steam temperature data at the outlet of the high temperature reheater after step S4, if the reheated steam temperature data does not reach the preset temperature threshold range, repeat steps S1-S4 ; If the reheat steam temperature data reaches the preset temperature threshold range, there is no need to adjust,

When repeating steps S1-S4, first compare the outer secondary air, the inner secondary air and the opening of the central air door of the hedging exhaust air burner, and then compare the metal wall temperature of the high temperature reheater with the over-temperature point or the area close to the high point. The influence of the metal wall temperature, according to the changes of other metal wall temperature points in the area, continue to make small adjustments to the outer secondary air, inner secondary air and central damper of other hedging overburner burners according to steps S1-S4 (due to After the adjustment, the high point of the metal wall temperature is expected to decrease, and the adjacent metal wall temperature point may also rise to a new high point. For the new high point, it may be necessary to adjust the phase of the originally adjusted first hedging exhaust air burner. Adjust the adjacent second hedging overfire air burner, and/or adjust the third hedging overburning air burner adjacent to the original adjusted fourth hedging overburning air burner) to achieve high temperature reheater heating The precise adjustment and control of the wall temperature points of the individual over-temperature positions of the surface metal wall temperature, and the uniformity of the metal wall temperature distribution of the entire high temperature reheater are improved.

Or when steps S1-S4 are repeated, all hedging burners and all hedging overburning air burners are adjusted according to steps S1-S4, until the adjusted high temperature reheater metal wall temperature distribution is uniform, there is no over-temperature point and high point, and the reheat steam temperature reaches the preset temperature threshold range.

After the adjustment method provided by the present invention is used to adjust the metal wall temperature deviation of the high temperature reheater of a coal-fired boiler, the flue gas composition of the inlet flue section of the SCR system and the metal wall temperature data of the high temperature reheater are collected, and the inlet flue section of the SCR system is collected. See Fig. 6 for the distribution law of O ₂ , and see Fig. 7 for the law of CO distribution at the inlet flue section of the SCR system. The distribution of the amount of O ₂ in each hedging burner is relatively uniform, the amount of CO at most measuring points is zero, and the amount of high CO The high CO content data is small, it can be seen that the hedging burner is fully burned.

The adjusted metal wall temperature distribution of the high temperature reheater along the width direction of the furnace is shown in Figure 8. In the figure, a and b are both tube panels for reheating steam, which are the same as a and b in Figure 3 respectively. , high re-exit 3 pieces to high re-exit 20 pieces correspond to the first hedge exhaust air burner 31, high re-exit 23 pieces to high re-exit 41 pieces correspond to the second hedge over-burn air burner 32, high re-exit 43 pieces to high re-exhaust air burner 32 The outlet 59 pieces correspond to the third hedge overfire burner 33 , and the high re-outlet 63 to the high re-outlet 79 correspond to the fourth hedge overfire burner 34 . It can be seen from the figure: there are no metal wall temperature over-temperature points and high points, the metal wall temperature temperature value is uniform, the reheat air temperature is 572 ℃, the preset temperature threshold is 571 ℃, and the reheat steam temperature reaches the preset temperature threshold range (preset temperature threshold). temperature threshold ±3°C), it can be seen that the hedging overburning air burner is fully burned.

The invention provides a method for adjusting the metal wall temperature deviation of a high temperature reheater of a hedging coal-fired boiler, which differentially adjusts the outer two of each hedging burner in the hedging burner group and each hedging exhaust air burner in the hedging burnout group. The opening of the secondary air, the inner secondary air and the central air changes the distribution characteristics of the corresponding outer secondary air, the inner secondary air and the central air, so as to adjust the uneven and insufficient combustion of individual positions in the furnace. Reduce the non-uniformity of the generated high-temperature flue gas flow, and realize the precise adjustment and control of the wall temperature points of the individual over-temperature positions of the metal wall temperature of the heating surface of the high-temperature reheater.

The above-mentioned embodiments are only intended to illustrate the technical concept and characteristics of the present invention, and the purpose thereof is to enable those who are familiar with the art to understand the content of the present invention and implement them accordingly, and cannot limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included 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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