Intelligent algorithm for re-heater brush coating area

Abstract

The present application relates to a kind of intelligent algorithm of reheater brush coating area, by the calculation of the actual deviation temperature rise Δt sjpc Of superheated tube, reheater steam temperature rise deviation Δt, superheated tube wall temperature deviation Δt sdpc , superheated tube control temperature rise Δt kzpc , the temperature rise Δt jsws That needs to control reduction, establishes the correlation of spraying coefficient, realizes the effective calculation of brush coating area.The algorithm of the present application is based on the principle of heat conservation, since the temperature of working medium in reheater heating surface is equal to the average value of the tube wall temperature of this section heating surface, therefore, in the heating surface where superheating occurs frequently, brush coating can make the wall temperature of superheating area and the outlet steam temperature approach, so as to achieve the purpose of balancing the heat absorption of corresponding tube row.Through the calculation of brush coating area, it can effectively prevent the phenomena such as superheating of the last stage reheater and screen reheater tube wall, at the same time, save wear-resistant materials and improve economic efficiency.

Description

Technical Field

[0001] This invention belongs to the field of intelligent algorithms and relates to an intelligent algorithm for calculating the area of ​​reheater coating. Background Technology

[0002] Overheating and tube rupture of metal tubes in screen-type reheaters, high-temperature superheaters, and final-stage reheaters in thermal power generating units is a common problem that constantly threatens the safe and stable operation of the units, and has caused unscheduled shutdowns in some units.

[0003] Large coal-fired boilers have low reheat steam pressure, high temperature, and low specific heat capacity. The high-temperature reheater is highly susceptible to factors such as flue gas heat load and steam flow rate, frequently exhibiting abnormal phenomena such as large temperature deviations between the left and right sides of the reheat steam and frequent localized overheating of the tube wall. Several factors contribute to overheating of the high-temperature heating surface metal tubes. First, insufficient metal grade of the heating surface. Second, blockage by foreign objects or oxide scale buildup can lead to insufficient working fluid flow in individual tubes, resulting in overheating and tube rupture. Third, coal quality plays a role, including deviations from design values ​​or low ash melting points, coking on the furnace heating surface, increased flame center height, and poor heat transfer leading to overheating and tube rupture. Fourth, combustion control issues include excessive deviations in primary air-coal concentration, improper secondary air distribution, and inaccurate burner installation, all of which cause excessive deviations in flue gas temperature and velocity in the high-temperature superheater and final reheater areas, ultimately leading to overheating. This not only reduced the service life of the reheater, but also significantly increased the flow rate of emergency water spray in order to lower the tube wall temperature, resulting in the reheat steam temperature failing to reach the rated value and seriously affecting the unit's economy.

[0004] Therefore, how to better prevent phenomena such as reheater tube wall overheating has always been a problem that needs to be solved. The application of new insulation material spraying technology has effectively prevented these phenomena. However, there is currently no relevant formula for calculating the reheater coating area, thus the problem of inaccurately calculating the reheater coating area remains. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide an intelligent algorithm for calculating the brush coating area of ​​a reheater.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A smart algorithm for calculating the brush coating area of ​​a reheater includes the following steps:

[0008] 1) The temperature t of the outlet pipe wall of the overheating pipe b and reheater inlet steam temperature t q Calculate the actual deviation temperature rise Δt of the overheating tube. sjpc Set the reheater outlet steam temperature (t). sdck The steam temperature t is set at the reheater outlet.sdck and the actual steam temperature t at the reheater outlet sjck Calculate the reheater steam temperature rise deviation Δt; based on the actual deviation temperature rise Δt of the overheating tube. sjpc Calculate the overheat pipe wall temperature deviation Δt based on the reheater steam temperature rise deviation Δt. sdpc The calculation method is as shown in formulas (1) to (3):

[0009] Δt sjpc =t b -t q (1)

[0010] In the formula:

[0011] t b : Outlet wall temperature of the overheating tube, °C;

[0012] t q Reheater inlet steam temperature, °C;

[0013] Δt sjpc Actual temperature rise deviation of the overheating tube, in °C;

[0014] Δt=t sdck -t sjck (2)

[0015] In the formula:

[0016] t sdck Reheater outlet set steam temperature, °C;

[0017] t sjck Actual steam temperature at reheater outlet, °C;

[0018] Δt: Reheater steam temperature rise deviation, °C;

[0019] Δt sdpc =Δt sjpc +Δt (3)

[0020] In the formula:

[0021] Δt sdpc Overheating pipe wall temperature deviation, °C;

[0022] 2) Set the reheater outlet control wall temperature t sdcb The wall temperature t is controlled by the reheater outlet. sdcb and reheater inlet steam temperature t q Calculate the temperature rise Δt of the overheat control tube. kzpc The calculation method is as shown in formula (4):

[0023] Δt kzpc =t sdcb -t q (4)

[0024] In the formula:

[0025] t sdcb Reheater outlet control wall temperature, °C;

[0026] Δt kzpc The overheating tube controls the temperature rise, in °C.

[0027] 3) The temperature deviation Δt of the pipe wall due to overheating sdpc and the temperature rise Δt controlled by the overheat tube kzpc Calculate the temperature rise Δt that needs to be reduced. jsws The calculation method is as shown in formula (5):

[0028] Δt jsws =Δt sdpc -Δt kzpc (5)

[0029] In the formula:

[0030] Δt jsws The temperature rise needs to be controlled and reduced, in °C.

[0031] 4) Based on the temperature deviation Δt of the overheated pipe wall sdpc The temperature rise Δt needs to be controlled and reduced. jsws Calculate the blackness ω of the coating material and the coating coefficient k.

[0032] 5) Based on the pipe length h gq 1. Brushing coefficient k, calculate brushing length h pt , coating area s pt .

[0033] The brush coating coefficient k is calculated using formula (6):

[0034]

[0035] In the formula:

[0036] ω: Blackness, %.

[0037] The brushing length h pt The calculation formula is as shown in formula (7):

[0038] h pt =kh gq (7)

[0039] In the formula:

[0040] h gq Pipe length, in meters;

[0041] h pt : Brushing length, m.

[0042] The area s of the brushing pt The calculation formula is as shown in formula (8):

[0043] s pt =2×П×r×h pt (8)

[0044] In the formula:

[0045] s pt Area to be painted, square meters;

[0046] r: Pipe radius, m.

[0047] The area to be coated is the tube ring side area of ​​the reheater heating surface that needs to be coated; the coating thickness is 1 mm.

[0048] Beneficial effects of this invention:

[0049] The reheater coating area calculation method of this invention is based on the principle of heat conservation. By calculating the actual deviation temperature rise of the overheating tube, the deviation of the reheater steam temperature rise, the deviation of the overheating tube wall temperature, the controlled temperature rise of the overheating tube, and the temperature rise that needs to be controlled and reduced, the correlation of the coating coefficient is established, thus realizing the effective calculation of the coating area.

[0050] This invention's algorithm is based on the principle of heat conservation. Since the average temperature of the working fluid within the reheater's heating surface is equal to the average temperature of the tube wall in that section, brushing the coating onto the heating surface where overheating frequently occurs can bring the wall temperature in the overheated area closer to the outlet steam temperature, thereby achieving the goal of balancing the heat absorption of the corresponding tube bank. By calculating the coating area, overheating of the tube walls in the final stage reheater and the screen-type reheater can be effectively prevented, while also saving wear-resistant materials and improving economic efficiency. Attached Figure Description

[0051] Figure 1 The calculation flowchart of the intelligent algorithm for brush coating area of ​​this invention. Detailed Implementation

[0052] The specific embodiments of the present invention will be further described in detail below with reference to examples.

[0053] Example

[0054] A smart algorithm for calculating the brush coating area of ​​a reheater includes the following steps:

[0055] 1) The temperature t of the outlet pipe wall of the overheating pipe b and reheater inlet steam temperature t q Calculate the actual deviation temperature rise Δt of the overheating tube. sjpc Set the reheater outlet steam temperature (t). sdck The steam temperature t is set at the reheater outlet. sdck and the actual steam temperature t at the reheater outlet sjckCalculate the reheater steam temperature rise deviation Δt; based on the actual deviation temperature rise Δt of the overheating tube. sjpc Calculate the overheat pipe wall temperature deviation Δt based on the reheater steam temperature rise deviation Δt. sdpc The calculation formulas are as follows: (1) to (3):

[0056] Δt sjpc =t b -t q (1)

[0057] In the formula:

[0058] t b : Outlet wall temperature of the overheating tube, °C;

[0059] t q Reheater inlet steam temperature, °C;

[0060] Δt sjpc Actual temperature rise deviation of the overheating tube, in °C;

[0061] Δt=t sdck -t sjck (2)

[0062] In the formula:

[0063] t sdck Reheater outlet set steam temperature, °C;

[0064] t sjck Actual steam temperature at reheater outlet, °C;

[0065] Δt: Reheater steam temperature rise deviation, °C;

[0066] Δt sdpc =Δt sjpc +Δt (3)

[0067] In the formula:

[0068] Δt sdpc Overheating pipe wall temperature deviation, °C;

[0069] 2) Set the reheater outlet control wall temperature t sdcb The wall temperature t is controlled by the reheater outlet. sdcb and reheater inlet steam temperature t q Calculate the temperature rise Δt of the overheat control tube. kzpc The calculation formula is as shown in formula (4):

[0070] Δt kzpc =t sdcb -t q (4)

[0071] In the formula:

[0072] t sdcb Reheater outlet control wall temperature, °C;

[0073] Δt kzpc The overheating tube controls the temperature rise, in °C.

[0074] 3) The temperature deviation Δt of the pipe wall due to overheating sdpc and the temperature rise Δt controlled by the overheat tube kzpc Calculate the temperature rise Δt that needs to be reduced. jsws The calculation formula is as shown in formula (5):

[0075] Δt jsws =Δt sdpc -Δt kzpc (5)

[0076] In the formula:

[0077] Δt jsws The temperature rise needs to be controlled and reduced, in °C.

[0078] 4) Based on the temperature deviation Δt of the overheated pipe wall sdpc The temperature rise Δt needs to be controlled and reduced. jsws 1. Calculate the blackness ω of the coating material and the coating coefficient k; the calculation formula is as shown in formula (6):

[0079]

[0080] In the formula:

[0081] ω: Blackness, %;

[0082] 5) Based on the pipe length h gq 1. Brushing coefficient k, calculate brushing length h pt and the area S of the brushing pt The calculation formulas are as follows: (7) and (8):

[0083] h pt =kh gq (7)

[0084] In the formula:

[0085] h gq Pipe length, in meters;

[0086] h pt : Brushing length, m.

[0087] s pt =2×П×r×h pt (8)

[0088] In the formula:

[0089] s ptArea to be painted, square meters;

[0090] r: Pipe radius, m.

[0091] The coating area is the tube ring side area of ​​the reheater heating surface that needs to be coated; the coating thickness is 1mm; the coating is applied around the reheater tube ring.

[0092] Application examples

[0093] During low-load operation, the No. 1 boiler of Datang Xuchang Longgang Power Generation Co., Ltd. has long experienced overheating of the reheater outlet wall. The combustion adjustment by the operators has not been effective. In order to ensure the safe operation of the unit, it is planned to adopt a brush coating method on the heating surface tube wall, and to brush the heating surface where overheating occurs to balance the heat absorption of the corresponding tube bank.

[0094] The final reheater is located in the horizontal flue after the furnace deflector, between the water-cooled wall rear wall suspension tubes and the water-cooled wall tube array. There are a total of 60 sections, each consisting of 5 tube coils with a tube diameter of Φ52mm, arranged along the furnace width with a transverse pitch of 228.6mm. Table 1 lists the parameters of the overheating tube coils.

[0095] The screen-type reheater is located between the rear screen superheater and the water-cooled wall suspension tubes. There are a total of 30 panels, each consisting of 7 tube coils with a diameter of Φ52mm, arranged along the width direction with a transverse pitch of 457.2mm. Table 2 lists the parameters of the overheating tube coils.

[0096] The working fluid temperature within the reheater's heating surface is equal to the average wall temperature of that section of the heating surface. Therefore, the goal of coating the overheated heating surface is to bring the wall temperature in the overheated area close to the outlet steam temperature, without exceeding the overheat limit. Insulating materials are used to coat the overheated tube bank to reduce the heat absorption of the overheated tube bank.

[0097] (1) Calculation method for the brushed area of ​​the final stage reheater

[0098] Based on the intelligent algorithm for the reheater coating area described in the embodiment, the set steam temperature t at the outlet of the final stage reheater is set. sdck =540℃, set reheater outlet control wall temperature t sdcb =570℃.

[0099] According to the SIS operating parameters, when Unit 1 is operating at a stable load of 246MW, the inlet steam temperature (t) of the final stage reheater of Unit 1 is... q =372℃, actual steam temperature at reheater outlet t sjck =528℃, outlet wall temperature of the overheating tube t b =571℃.

[0100] The blackness of the coating material used is ω = 95%, and the radius of the tube is 0.026m.

[0101] Substituting into formulas (1) to (6), calculate the brush coating coefficient k:

[0102] Δt sjpc =571℃-372℃

[0103] =199℃

[0104] t sdck =540℃

[0105] Δt = 540℃ - 528℃

[0106] =12℃

[0107] Δt sdpc =199℃ + 12℃

[0108] =211℃

[0109] t sdcb =570℃

[0110] Δt kzpc =570℃-372℃

[0111] =198℃

[0112] Δt jsws =211℃-198℃

[0113] =13℃

[0114]

[0115] Calculate the brushing length h according to formulas (7) and (8). pt , coating area s pt Based on the calculation instructions, the coating area of ​​each superheated tube bank on the reheater surface of Boiler No. 1 was obtained. Specific calculation data are shown in Table 1 below:

[0116] Table 1. Calculation of the area of ​​the heating surface of the last stage reheater of Boiler No. 1.

[0117]

[0118] The coating area is the tube ring side area of ​​the reheater heating surface that needs to be coated; the coating thickness is 1mm; the coating is applied around the reheater tube ring.

[0119] (2) Calculation method for the coating area of ​​a screen-type reheater

[0120] According to the intelligent algorithm for the reheater brushing length described in the embodiment, the set steam temperature t at the outlet of the screen-type reheater is set. sdck =540℃, set reheater outlet control wall temperature t sdcb =570℃.

[0121] According to the SIS operating parameters, when Unit 1 is operating at a stable load of 246MW, the inlet steam temperature (t) of the No. 1 boiler screen reheater is... q =372℃, actual steam temperature at reheater outlet t sjck =528℃, outlet wall temperature of the overheating tube t b =571℃.

[0122] The blackness of the coating material used is ω = 95%, and the radius of the tube is 0.026m.

[0123] Substituting into formulas (1) to (6), calculate the brush coating coefficient k:

[0124] Δt sjpc =571℃-372℃

[0125] =199℃

[0126] t sdck =540℃

[0127] Δt = 540℃ - 528℃

[0128] =12℃

[0129] Δt sdpc =199℃ + 12℃

[0130] =211℃

[0131] t sdcb =570℃

[0132] Δt kzpc =570℃-372℃

[0133] =198℃

[0134] Δt jsws =211℃-198℃

[0135] =13℃

[0136]

[0137] Calculate the brushing length h according to formulas (7) and (8). pt , coating area s pt .

[0138] Based on the calculation instructions, the coating area of ​​each superheated tube bank on the heating surface of the No. 1 furnace screen reheater was obtained. Specific calculation data are shown in Table 2 below:

[0139] Table 2 Calculation Table of Painted Area for Heating Surface of No. 1 Furnace Screen Reheater

[0140]

[0141] The coating area is the tube ring side area of ​​the reheater heating surface that needs to be coated; the coating thickness is 1mm; the coating is applied around the reheater tube ring.

Claims

1. A smart algorithm for calculating the brush coating area of ​​a reheater, characterized in that, Includes the following steps: 1) The temperature t of the outlet pipe wall of the overheating pipe b and reheater inlet steam temperature t q Calculate the actual deviation temperature rise Δt of the overheating tube. sjpc Set the reheater outlet steam temperature (t). sdck The steam temperature t is set at the reheater outlet. sdck and the actual steam temperature t at the reheater outlet sjck Calculate the reheater steam temperature rise deviation Δt; based on the actual deviation temperature rise Δt of the overheating tube. sjpc Calculate the overheat pipe wall temperature deviation Δt based on the reheater steam temperature rise deviation Δt. sdpc The calculation method is as shown in formulas (1) to (3): Δt sjpc =t b -t q (1) In the formula: t b : Outlet wall temperature of the overheating tube, °C; t q Reheater inlet steam temperature, °C; Δt sjpc Actual temperature rise deviation of the overheating tube, in °C; Δt=t sdck -t sjck (2) In the formula: t sdck Reheater outlet set steam temperature, °C; t sjck Actual steam temperature at reheater outlet, °C; Δt: Reheater steam temperature rise deviation, °C; Δt sdpc =Δt sjpc +Δt (3) In the formula: Δt sdpc Overheating pipe wall temperature deviation, °C; 2) Set the reheater outlet control wall temperature t sdcb The wall temperature t is controlled by the reheater outlet. sdcb and reheater inlet steam temperature t q Calculate the temperature rise Δt of the overheat control tube. kzpc The calculation method is as shown in formula (4): Δt kzpc =t sdcb -t q (4) In the formula: t sdcb Reheater outlet control wall temperature, °C; Δt kzpc The overheating tube controls the temperature rise, in °C. 3) The temperature deviation Δt of the pipe wall due to overheating sdpc and the temperature rise Δt controlled by the overheat tube kzpc Calculate the temperature rise Δt that needs to be reduced. jsws The calculation method is as shown in formula (5): Δt jsws =Δt sdpc -Δt kzpc (5) In the formula: Δt jsws The temperature rise needs to be controlled and reduced, in °C. 4) Based on the temperature deviation Δt of the overheated pipe wall sdpc The temperature rise Δt needs to be controlled and reduced. jsws Calculate the blackness ω of the coating material and the coating coefficient k. 5) Based on the pipe length h gq 1. Brushing coefficient k, calculate brushing length h pt , coating area s pt .

2. The intelligent algorithm for calculating the reheater coating area as described in claim 1, characterized in that, The brush coating coefficient k is calculated using formula (6): In the formula: ω: Blackness, %.

3. The intelligent algorithm for calculating the reheater coating area as described in claim 1, characterized in that, The brushing length h pt The calculation formula is as shown in formula (7): h pt =kh gq (7) In the formula: h gq Pipe length, in meters; h pt : Brushing length, m.

4. The intelligent algorithm for calculating the reheater coating area as described in claim 1, characterized in that, The area s of the brushing pt The calculation formula is as shown in formula (8): s pt =2×∏×r×h pt (8) In the formula: s pt Area to be painted, square meters; r: Pipe radius, m.

5. The intelligent algorithm for calculating the reheater coating area as described in claim 1, characterized in that, The area to be coated is the tube ring side area of ​​the reheater heating surface that needs to be coated; the coating thickness is 1 mm.

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