Method and system for adjusting heat absorption deviation on both sides of a screen superheater of a tangentially fired boiler

Abstract

The application discloses a kind of adjustment method and system for the heat absorption deviation of opposite sides of screen superheater of opposed firing boiler, method includes collecting the initial state data of boiler burner and the secondary air door pull rod in overfire air;In low load operating condition, the heat absorption parameters of the two sides of screen superheater are obtained, and the heat absorption deviation of the two sides of screen superheater is calculated;Based on the heat absorption deviation of the two sides of screen superheater, according to the influencing factors of the heat absorption parameters of the two sides of screen superheater, a boiler burner and overfire air secondary air adjustment model is established;The position of the burner and the secondary air door pull rod in overfire air is determined by the adjustment model.Based on the heat absorption deviation of the two sides of screen superheater, according to the influencing factors of the heat absorption parameters of the two sides of screen superheater, a boiler burner and overfire air secondary air adjustment model is established, and then the position of the burner and the secondary air door pull rod in overfire air is determined by the adjustment model, the combustion and air distribution state in each furnace is changed, and the problem of heat absorption deviation of the two sides of screen superheater under low load condition is improved from the source.

Description

Technical Field

[0001] This invention belongs to the field of boiler technology for thermal power plants, and relates to a method for adjusting the heat absorption deviation on both sides of a screen-type superheater in a counter-firing boiler. Background Technology

[0002] Currently, a large number of opposed-flow combustion boilers of varying capacities are used in thermal power generation, most of which are large coal-fired units ranging from 600 to 1000 MW. The swirl burners in opposed-flow combustion boilers are mostly arranged with opposing flow at the front and rear walls, with one layer of burners corresponding to each coal mill. In some opposed-flow combustion boilers operating at low loads with four coal mills running, there is a problem of excessive heat absorption deviation on both sides of the screen-type superheater. This not only limits the increase in main steam temperature but also, in severe cases, causes the screen-type superheater wall temperature to exceed the limit, affecting the boiler's operational safety.

[0003] To address the issue of excessive heat absorption deviation on both sides of the superheater under low boiler load, power plant operators typically try to mitigate this by adjusting the opening of the burnout air damper – opening the burnout air damper wider reduces the heat absorption of the superheater on the corresponding side. However, this method has limited effectiveness, often resulting in situations where the heat absorption deviation remains significant even with one side's burnout air damper fully open and the other side's damper closed to 10%. Faced with this problem, operators often lack adjustment tools and can only control the wall temperature by reducing the temperature with desuperheating water and operating at lower parameters, causing significant disruption to daily boiler operation. Summary of the Invention

[0004] The purpose of this invention is to solve the problem in the prior art that the excessive heat absorption deviation on both sides of the screen-type superheater under low boiler load limits the increase of main steam temperature and may cause the screen-type superheater wall temperature to exceed the limit, affecting the safe operation of the boiler. The invention provides a method and system for adjusting the heat absorption deviation on both sides of the screen-type superheater in a counter-firing boiler.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] The method for adjusting the heat absorption deviation on both sides of the screen-type superheater in a counter-firing boiler includes the following steps:

[0007] Collect initial state data of the boiler burner and the secondary damper rods inside the burnout air chamber;

[0008] Under low-load operating conditions, obtain the heat absorption parameters on both sides of the screen-type superheater and calculate the heat absorption deviation on both sides of the screen-type superheater.

[0009] Based on the heat absorption deviation on both sides of the screen-type superheater, and according to the influencing factors of the heat absorption parameters on both sides of the screen-type superheater, an adjustment model for the boiler burner and the secondary air inside the burnout air is established.

[0010] The position of the burner and the secondary air damper rod inside the burnout air chamber is determined by adjusting the model.

[0011] A further improvement of the present invention is that:

[0012] After collecting the initial state data of the boiler burner and the secondary damper rod in the burnout air, the process also includes checking and verifying the burner and the secondary damper rod in the burnout air.

[0013] The inspection and calibration of the burner and the secondary air damper rod inside the burnout air chamber are carried out during boiler shutdown.

[0014] In the boiler burner and burnout air internal secondary air adjustment model, the adjustment position and direction of the burner and burnout air internal secondary air tie rods are first obtained based on the heat absorption deviation on both sides of the screen superheater; then, the burner and burnout air internal secondary air damper tie rods are adjusted by single factors respectively; finally, the position of the burner and burnout air internal secondary air tie rods is obtained.

[0015] The factors affecting the heat absorption parameters on both sides of the screen-type superheater include the inlet steam temperature of the screen-type superheater, the outlet steam temperature of the screen-type superheater, the first-stage desuperheating water volume, and the opening degree of the burnout air layer damper.

[0016] After determining the positions of the burner and the secondary air damper rods in the burnout air, the position adjustment results are verified and the adjustment effect is evaluated under low load conditions.

[0017] The verification of the position adjustment results was carried out under a load of 330MW.

[0018] The method involves adjusting the model to determine the position of the burner and the secondary damper rod inside the burnout air, thereby reducing the heat absorption deviation on both sides of the screen-type superheater to below 20°C.

[0019] The boiler burners adopt a staged combustion method with opposing front and rear walls. Low NOx swirl-type HT-NR3 pulverized coal burners are arranged in three layers on each of the front and rear walls of the furnace, with 6 burners in each layer, for a total of 36 burners.

[0020] A system for adjusting the heat absorption deviation on both sides of a screen-type superheater in a counter-firing boiler includes:

[0021] The data acquisition unit is used to acquire the initial state data of the boiler burner and the secondary damper rod inside the burnout air.

[0022] The monitoring unit is used to acquire the heat absorption parameters on both sides of the screen-type superheater and calculate the heat absorption deviation on both sides of the screen-type superheater under low load operating conditions.

[0023] The control unit establishes an adjustment model for the boiler burner and the secondary air inside the burnout air based on the heat absorption deviation on both sides of the screen-type superheater and according to the influencing factors of the heat absorption parameters on both sides of the screen-type superheater.

[0024] An adjustment unit is used to determine the position of the secondary damper rod in the burner and burnout air through an adjustment model.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention proposes a method for adjusting the heat absorption deviation on both sides of a screen-type superheater in a counter-firing boiler. Based on the heat absorption deviation on both sides of the screen-type superheater, and according to the influencing factors of the heat absorption parameters on both sides of the screen-type superheater, an adjustment model for the boiler burner and the secondary air inside the burnout air is established. Then, the position of the burner and the secondary air damper rod inside the burnout air is determined by adjusting the model, thereby changing the combustion and air distribution state in each furnace, and thus improving the problem of heat absorption deviation on both sides of the screen-type superheater under low load conditions from the source.

[0027] Furthermore, by inspecting and verifying the secondary damper rods inside the burner and burnout air, it is possible to prevent the burner and secondary damper rods inside the burnout air from being unable to adjust properly due to issues such as detachment or jamming during hot adjustments, thus affecting normal adjustment work. Each secondary damper rod inside the burner and burnout air is inspected and verified to ensure that it is flexible and adjustable. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The flowchart of the adjustment method for mitigating the heat absorption deviation on both sides of the screen-type superheater in a counter-firing boiler according to the present invention is shown below.

[0030] Figure 2 This is a structural diagram of the adjustment system for mitigating the heat absorption deviation on both sides of the screen-type superheater in a counter-firing boiler, as described in this invention.

[0031] Figure 3 This is a schematic diagram of the structure of the counter-current combustion boiler of the present invention.

[0032] Among them: 1-A side, 2-B side, 3-front wall, 4-rear wall, 5-SOFA layer. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings:

[0040] See Figure 1 The flowchart below shows the adjustment method for mitigating the heat absorption deviation on both sides of the screen-type superheater in a counter-firing boiler according to the present invention, which specifically includes the following steps:

[0041] S1, collect initial state data of the boiler burner and the secondary damper rod inside the burnout air.

[0042] S2, inspect and verify the burner and the secondary air damper rod inside the burnout air chamber.

[0043] S3, under low-load operating conditions, obtain the heat absorption parameters on both sides of the screen-type superheater and calculate the heat absorption deviation on both sides of the screen-type superheater.

[0044] S4. Based on the heat absorption deviation on both sides of the screen-type superheater, and according to the influencing factors of the heat absorption parameters on both sides of the screen-type superheater, an adjustment model for the boiler burner and the secondary air inside the burnout air is established.

[0045] First, based on the heat absorption deviation on both sides of the screen-type superheater, the adjustment position and direction of the secondary damper rods inside the burner and burnout air are obtained; then, the secondary damper rods inside the burner and burnout air are adjusted using single factors respectively; finally, the positions of the secondary damper rods inside the burner and burnout air are obtained.

[0046] Factors affecting the heat absorption parameters on both sides of the screen-type superheater include the inlet steam temperature of the screen-type superheater, the outlet steam temperature of the screen-type superheater, the first-stage desuperheating water flow rate, and the opening degree of the burnout air layer damper.

[0047] S5, the position of the burner and the secondary air damper rod inside the burnout air is determined by adjusting the model.

[0048] S6 verifies the position adjustment results and evaluates the adjustment effect under low load conditions.

[0049] See Figure 2 The diagram shows the structure of the adjustment system for mitigating the heat absorption deviation on both sides of the screen-type superheater in a counter-firing boiler, as described in this invention. Specifically, it includes:

[0050] The data acquisition unit is used to acquire the initial state data of the boiler burner and the secondary damper rod inside the burnout air.

[0051] The monitoring unit is used to acquire the heat absorption parameters on both sides of the screen-type superheater and calculate the heat absorption deviation on both sides of the screen-type superheater under low load operating conditions.

[0052] The control unit establishes an adjustment model for the boiler burner and the secondary air inside the burnout air based on the heat absorption deviation on both sides of the screen-type superheater and according to the influencing factors of the heat absorption parameters on both sides of the screen-type superheater.

[0053] An adjustment unit is used to determine the position of the secondary damper rod in the burner and burnout air through an adjustment model.

[0054] Example

[0055] The embodiment of this invention is a supercritical coal-fired boiler, model DG1900 / 25.4-Ⅱ2. This boiler is a wall-mounted, counter-flow supercritical parameter variable-pressure once-through boiler with a single furnace, single reheat, balanced ventilation, open-air layout, solid slag discharge, all-steel frame, and fully suspended Π-type boiler.

[0056] The boiler adopts a positive pressure direct-fired pulverizing system, equipped with 6 HP-1003 medium-speed coal mills. Each coal mill corresponds to one layer of burners. The burners adopt a front and rear wall opposed-stage combustion technology, with low NOx swirl-type HT-NR3 pulverized coal burners arranged in three layers on each of the front and rear walls of the furnace, with 6 burners in each layer, for a total of 36 burners in the entire furnace. The burnout air nozzle (AAP) is arranged above the uppermost layer of burners.

[0057] During normal boiler operation, under the low-load ABDF mill combination operation mode, there is a significant difference in heat absorption on both sides of the boiler's screen-type superheater, with side A absorbing significantly more heat than side B. To reduce this difference, operators can only make appropriate adjustments by changing the opening of the burnout air layer damper, but the effect is limited. The only solution is to control the wall temperature with desuperheating water and operate at reduced parameters, which causes considerable inconvenience to daily boiler operation and seriously affects the safe and economical operation of the boiler.

[0058] like Figure 1 As shown in the figure, this embodiment illustrates a method for adjusting the heat absorption deviation on both sides of a screen-type superheater in a counter-firing boiler according to the present invention. The method includes the following steps:

[0059] S1 records the initial state of the secondary damper rod in the boiler burner and burnout air.

[0060] Specifically, during boiler shutdown, the initial state of the burner and the secondary air damper rods in the local area were recorded. The positions of the secondary air damper rods are shown in Table 1.

[0061] Table 1 Initial State of Burner and Secondary Air Pull Rod

[0062]

[0063]

[0064] S2. Inspect and verify each of the burner and the secondary air damper rods inside the burnout air chamber to ensure that they are flexible and adjustable.

[0065] Specifically, during boiler shutdown, the secondary air damper rods of the burners and burnout air were inspected and calibrated one by one. The inspection revealed that the secondary air damper rods of burners A1, B5, D2, and E6 were stuck and could not be adjusted due to a long period of inactivity. Maintenance personnel entered the secondary air box and rectified the problem, ensuring that all internal secondary air damper rods were flexible and adjustable.

[0066] S3. Under low-load operating conditions, conduct a boiler baseline test to determine the heat absorption deviation on both sides of the screen-type superheater.

[0067] Specifically, during boiler hot operation, a boiler baseline test was conducted under a 330MW load ABDF mill combination operation mode. Under the test conditions, the heat absorption on both sides of the boiler's screen-type superheater showed a significant difference, with side A absorbing significantly more heat than side B. Even with the burnout air layer damper on side A fully open and side B at 10% opening, the temperature rise on side A of the screen-type superheater was still 62℃ higher than on side B. At this point, the primary desuperheating water on side A was fully open, while side B was almost completely closed. Excluding the influence of the burnout air layer damper, the heat absorption difference on both sides of the screen-type superheater was even greater.

[0068] Table 2. Heat absorption deviation of the screen-type superheater under the 330MW load baseline condition.

[0069]

[0070] S4. Conduct a single-item adjustment test of the burner and the secondary air inside the burnout air to determine the appropriate position of the burner and the secondary air damper rod inside the burnout air.

[0071] Specifically, given that the heat absorption on side A of the boiler's screen-type superheater is significantly higher than that on side B, it was initially determined that the secondary air tie rods of burnout air No. 5 and No. 6 on side B of the boiler should be reduced, and the secondary air tie rods of burners No. 1, No. 2, No. 5 and No. 6 should be appropriately reduced. Individual adjustment tests were conducted, and finally, suitable burner and burnout air secondary air tie rod positions were obtained.

[0072] Table 3. Temperature rise deviation of screen-type superheater before and after adjustment in 330MW load single test

[0073]

[0074] The above adjustments show that after the secondary air dampers in burnout air compartments 5 and 6 were closed slightly, the temperature rise deviation on both sides of the screen-type superheater decreased from 62℃ to 22℃; after the secondary air dampers in the burner were appropriately closed, the temperature rise deviation on both sides of the screen-type superheater decreased from 49℃ to 18℃. The heat absorption deviation on both sides of the screen-type superheater has significantly improved.

[0075] S5, conduct comprehensive optimization tests to verify and evaluate the adjustment effects.

[0076] After adjusting the burnout air and the secondary air damper rods in the burner to their optimal state, a comprehensive optimization test was conducted under the ABDF mill combination at a load of 330MW. After multiple verifications, the temperature rise deviation on both sides of the screen-type superheater can be basically kept within 20℃. Moreover, after adjustment, the opening of the burnout air layer dampers on both sides retains a large adjustment margin, the combustion state in the furnace is greatly improved, and the steam temperature characteristics are significantly improved.

[0077] Table 4. Temperature rise deviation of screen-type superheater before and after adjustment in the 330MW load comprehensive optimization test.

[0078]

[0079]

[0080] The method for adjusting the heat absorption deviation on both sides of the screen-type superheater in this invention is based on the heat absorption deviation on both sides of the screen-type superheater. According to the influencing factors of the heat absorption parameters on both sides of the screen-type superheater, an adjustment model for the boiler burner and the secondary air inside the burnout air chamber is established. Then, the position of the burner and the secondary air damper rods inside the burnout air chamber is determined by adjusting the model, thereby changing the combustion and air distribution state in each furnace. This achieves the goal of fundamentally improving the problem of heat absorption deviation on both sides of the screen-type superheater under low load conditions. Furthermore, by inspecting and verifying the burner and the secondary air damper rods inside the burnout air chamber, it is prevented that the rods cannot be properly adjusted during hot adjustments due to issues such as detachment or jamming, which would affect normal adjustment work. Each burner and secondary air damper rod inside the burnout air chamber is inspected and verified individually to ensure its flexibility and adjustability.

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for adjusting the heat absorption deviation on both sides of a screen superheater of a tangentially fired boiler, characterized in that, The method comprises the following steps: Collecting initial state data of the boiler burner and the inner secondary air door pull rod of the overfire air; after the collection, checking and verifying the burner and the inner secondary air door pull rod of the overfire air during the shutdown of the boiler; Under the low load operation condition, obtaining the heat absorption parameters on both sides of the screen superheater, and calculating the heat absorption deviation on both sides of the screen superheater; Based on the heat absorption deviation on both sides of the screen superheater, according to the influencing factors of the heat absorption parameters on both sides of the screen superheater, a boiler burner and overfire air inner secondary air adjustment model is established, wherein the influencing factors of the heat absorption parameters on both sides of the screen superheater include the screen superheater inlet steam temperature, the screen superheater outlet steam temperature, the first stage desuperheating water quantity and the overfire air layer air door opening degree; in the boiler burner and overfire air inner secondary air adjustment model, firstly, the adjusting position and adjusting direction of the burner and the overfire air inner secondary air pull rod are obtained according to the heat absorption deviation on both sides of the screen superheater; then, the burner and the overfire air inner secondary air door pull rod are adjusted respectively; finally, the position of the burner and the overfire air inner secondary air pull rod is obtained; The position of the burner and the overfire air inner secondary air door pull rod is determined through the adjustment model, and the position adjustment result is verified and the adjustment effect is evaluated under the low load condition.

2. A method of adjusting the heat absorption deviation on both sides of a regenerative superheater of a tangentially fired boiler as claimed in claim 1, characterized in that, The verification of the position adjustment result is performed under the 330 MW load.

3. A method of adjusting the heat absorption deviation on both sides of a regenerative superheater of a tangentially fired boiler as claimed in claim 1, characterized in that, The heat absorption deviation on both sides of the screen superheater is reduced to below 20 DEG C through the adjustment model to determine the position of the burner and the overfire air inner secondary air door pull rod.

4. A method of adjusting the heat absorption deviation on both sides of a regenerative superheater of a tangentially fired boiler as claimed in claim 1, characterized in that, The boiler burner adopts front and back wall opposite collision staged combustion, and 36 low-NOx swirl type HT-NR3 pulverized coal burners are arranged in three layers on the front and back walls of the furnace, with 6 burners arranged in each layer.

5. A system for adjusting the heat absorption deviation on both sides of a screen superheater of a opposed firing boiler, using the method for adjusting the heat absorption deviation on both sides of a screen superheater of a opposed firing boiler according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: A data acquisition unit is arranged to collect initial state data of the boiler burner and the inner secondary air door pull rod of the overfire air; A monitoring unit is arranged to obtain the heat absorption parameters on both sides of the screen superheater under the low load operation condition, and to calculate the heat absorption deviation on both sides of the screen superheater; A control unit is arranged to establish a boiler burner and overfire air inner secondary air adjustment model based on the heat absorption deviation on both sides of the screen superheater, according to the influencing factors of the heat absorption parameters on both sides of the screen superheater; An execution adjustment unit is arranged to determine the position of the burner and the overfire air inner secondary air door pull rod through the adjustment model.

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