A boiler soot blowing operation method and system suitable for deep peak regulation and AGC mode

Abstract

The present invention discloses a boiler sootblowing operation method and system suitable for deep peak regulation and AGC mode. On the basis of not increasing the boiler measuring points, by collecting the boiler historical and real-time operation data, an overall boiler sootblowing operation scheme covering all heating surfaces is established based on four evaluation parameters, namely, the real-time deviation of heat loss of different heating surfaces, the cumulative deviation, the ash accumulation time and the boiler exhaust temperature. The present invention can avoid the serious problem of molten ash and slagging on the high-temperature heating surface due to the monitoring index failing to reach the critical value for a long time during deep peak regulation, and can solve the problem of sootblowing operation misjudgment caused by multi-frequency and large-scale fluctuations of instantaneous monitoring indicators when the load changes too fast in the AGC mode, thereby ensuring that the sootblowing operation instructions are more accurate, more comprehensive and more suitable for the actual operation of the boiler.

Description

Technical Field

[0001] The invention relates to a boiler soot blowing operation method and system suitable for deep peak regulation and AGC mode, belonging to the technical field of power station boiler operation optimization. Background Art

[0002] The ash and slag accumulation on the heating surfaces of coal-fired boilers will seriously affect the heat transfer efficiency of the boilers, and even cause safety problems such as shutdown and local over-temperature tube burst. Although the boilers are equipped with various soot blowers such as steam, gas and sonic for ash and slag removal operations, due to the lack of monitoring data, operators cannot obtain the ash accumulation status of the heating surfaces in real time, or soot blowing is not timely, resulting in a decrease in the heat transfer performance of the boiler, or soot blowing is excessive, resulting in meaningless waste of soot blower energy.

[0003] The combustion space inside the boiler is filled with flue gas with high temperature, complex composition and a large number of ash particles. The measurement environment is harsh and the degree of ash accumulation and slagging cannot be directly observed. At present, most of the soft measurement or monitoring models commonly used in engineering define cleanliness factor or pollution rate as indicators for online monitoring of ash accumulation. On the one hand, due to the need for deep peak regulation, the monitoring index may not reach the critical value for a long time under low load, which will extend the soot blowing interval, resulting in the formation of a slag layer that is difficult to remove due to the molten ash accumulation on the high-temperature heating surface; on the other hand, with the addition of the AGC (Auto Generation Control) system, the boiler load is more variable. The cleanliness factor or pollution rate is an instantaneous value reflecting the ash state of the heating surface. This type of monitoring indicator is obtained through the principle of thermal balance and is greatly disturbed under variable load conditions. Its multiple frequencies and large-scale fluctuations will lead to misjudgment of soot blowing operations. Therefore, in the context of energy conservation and emission reduction and the dual carbon strategy, it is extremely important to establish a soot blowing operation method and system for the boiler heating surface that can be applied to deep peak regulation and AGC mode. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a boiler sootblowing operation method and system suitable for deep peak regulation and AGC mode. An overall sootblowing operation plan is formulated based on four evaluation parameters: real-time deviation of heat loss of each heating surface, cumulative deviation, ash accumulation time and boiler exhaust temperature. This provides staff with more accurate, comprehensive and more suitable sootblowing timing and duration operation instructions for actual boiler operation.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides a boiler sootblowing operation method applicable to deep peak load regulation and AGC mode, comprising:

[0007] Obtain the pre-collected historical operation data of different heating surfaces of the boiler, calculate the real-time deviation of heat loss of different heating surfaces, and form a real-time deviation history curve of heat loss according to time distribution;

[0008] The heat loss real-time deviation historical curve is selected and classified according to the soot accumulation time period and the soot blowing time period to obtain the heat loss real-time deviation reference curves of different heating surfaces, and then obtain the heat loss real-time deviation reference formulas of different heating surfaces;

[0009] Based on the heat loss real-time deviation reference formula, calculate the heat loss real-time deviation critical value, heat loss cumulative deviation critical value and dust accumulation time critical value of each heating surface;

[0010] Calculation steps: obtaining the real-time operating parameters of different heating surfaces collected in advance, and calculating the current value of the real-time deviation of heat loss, the current value of the cumulative deviation of heat loss and the current value of the dust accumulation time of each heating surface;

[0011] A first comparison step: comparing the current value of the heat loss cumulative deviation with the critical value of the heat loss cumulative deviation, and if the current value of the heat loss cumulative deviation is less than the critical value of the heat loss cumulative deviation, performing a second comparison step, otherwise performing a soot blowing operation step;

[0012] A second comparison step: comparing the current value of the heat loss real-time deviation with the heat loss real-time deviation critical value, and if the current value of the heat loss real-time deviation is less than the heat loss real-time deviation critical value, performing a fourth comparison step, otherwise performing a third comparison step;

[0013] A third comparison step: comparing the current value of the heat loss cumulative deviation with 75% of the heat loss cumulative deviation critical value, and if the current value of the heat loss cumulative deviation is greater than or equal to 75% of the heat loss cumulative deviation critical value, performing a soot blowing operation step, otherwise performing a fourth comparison step;

[0014] Fourth comparison step: comparing the current value of the dust accumulation time with twice the critical value of the dust accumulation time, if the current value of the dust accumulation time is greater than or equal to twice the critical value of the dust accumulation time, performing a soot blowing operation step, otherwise performing a judgment step;

[0015] Judgment step: judge the boiler exhaust gas temperature. If the exhaust gas temperature exceeds the exhaust gas temperature assessment value by 30K or more and the ratio of the current value of the heat loss cumulative deviation to the critical value of the heat loss cumulative deviation is greater than or equal to 50%, then the soot blowing operation step is performed on the heating surface with the highest current value of the heat loss cumulative deviation / critical value of the heat loss cumulative deviation, otherwise the calculation step is performed;

[0016] Sootblowing operation steps: calculate the recommended sootblowing time for the heating surface that meets the sootblowing conditions, perform the sootblowing operation, and ensure that the sootblowing time is within the limited working time range of the sootblower and there is only one sootblowing heating surface, and then return to the calculation step for the next calculation.

[0017] Furthermore, the real-time deviation of heat loss of different heating surfaces is calculated using the following formula:

[0018] Heat loss real-time deviation:

[0019] Heat loss: q L-i =q t-i -q a-i ;

[0020] The actual amount of heat absorbed by each heating surface: q a-i =m i (h″ i -h′ i );

[0021] Convection heating surface clean heat absorption:

[0022] Semi-radiant heating surface clean heat absorption:

[0023] Heat absorption of furnace cleaning: The average flame temperature

[0024] In the above formula, the subscript i is the type of heating surface, X is convection, Y is semi-radiation, and Z is the furnace; Δq L-i is the real-time deviation of heat loss of type i heating surface (kW); q L-i is the heat loss of type i heating surface (kW); is the initial heat loss of type i heating surface (kW); q t-i is the clean heat absorption of type i heating surface (kW); q a-i is the actual heat absorption of type i heating surface (kW); m i is the working fluid flow rate of type i heating surface (kg / s); h i ′、h i ″ are the inlet and outlet enthalpy values ​​of the i-type heating surface (kJ / kg); q t-X ,q t-Y and q t-Z are convection, semi-radiation and clean heat absorption of furnace heating surface (kW); H X , H Y and H Z Convection, semi-radiation and furnace heating surface areas (m 2 );ΔT X , ΔT Yare the heat transfer temperature differences of convection and semi-radiation heating surfaces (K); α 1-X , α 1-Y are the heat release coefficients of the convective and semi-radiative flue gas sides (kW / (m 2 ·K)); α 2-X , α 2-Y are the heat absorption coefficients of the convection and semi-radiation working fluid sides (kW / (m 2 ·K));r Y k is the ratio of the heat absorbed by the semi-radiant heating surface to the heat absorbed by convection; Y is the ratio of the radiation at the furnace outlet absorbed by the semi-radiant heating surface; ψ p,f Obtain the furnace direct radiation heat effectiveness coefficient for the furnace outlet heating surface; ε f is the furnace blackness; T f ″ is the flue gas temperature at the furnace outlet (K); A f is the cross-sectional area of ​​the furnace outlet smoke window (m 2 );σ0 is the Boltzmann constant, usually 5.67×10 - 11 kW / (m 2 ·K 4 );ψ0 is the thermal efficiency coefficient of the clean water-cooled wall; T fl is the average flame temperature (K); M is the relative center of the flame; T th is the theoretical combustion temperature of the furnace (K).

[0025] Furthermore, the method for obtaining the heat loss real-time deviation reference curve and the heat loss real-time deviation reference formula includes:

[0026] Arrange all real-time deviation history curves of heat loss under different loads, and separate the soot accumulation period and soot blowing period;

[0027] Calculate the average change of all curves in each sampling time period;

[0028] The average change in each sampling time period is accumulated along the time growth to obtain the real-time deviation reference curve;

[0029] The reference formula for the soot accumulation time period and the soot blowing time period is obtained by data fitting. The fitting formula is as follows:

[0030] Real-time deviation fitting of heat loss during dust accumulation period:

[0031] Real-time deviation fitting of heat loss during sootblowing period:

[0032] In the above formula, are the real-time deviation of heat loss during the soot accumulation period and the soot blowing period (kW); tf is the dust accumulation time (s); t s is the soot blowing time (s); A, B, C, D, E are all fitting parameters.

[0033] Furthermore, the calculation of the critical value of the real-time deviation of heat loss of each heating surface, the critical value of the cumulative deviation of heat loss and the critical value of the dust accumulation time includes:

[0034] Net gain through maximum sootblowing:

[0035]

[0036] The following parameters are calculated:

[0037] Critical value of dust accumulation time: t fopt

[0038] Heat loss real-time deviation critical value:

[0039] Heat loss cumulative deviation critical value:

[0040] In the above formula, Q Bnet is the net soot blowing benefit (kJ); q s is the soot blowing energy loss per unit time (kW); t smin and t smax are the minimum and maximum sootblowing time (s) limited by the sootblower; t fopt It is the critical value of dust accumulation time.

[0041] Furthermore, the calculation formula for the current value of the heat loss cumulative deviation is: Where Δt is the data collection interval (s); the formula for calculating the recommended soot blowing time for the heated surface to meet the soot blowing conditions is: where t sopt This is the recommended soot blowing time.

[0042] In a second aspect, the present invention provides a boiler soot blowing operation system suitable for deep peak regulation and AGC mode, comprising:

[0043] A heat loss real-time deviation history curve acquisition unit is used to acquire the pre-collected historical operation data of different heating surfaces of the boiler, calculate the real-time deviation of heat loss of different heating surfaces, and form a heat loss real-time deviation history curve according to time distribution;

[0044] A heat loss real-time deviation reference formula acquisition unit is used to select and classify the heat loss real-time deviation historical curve according to the soot accumulation time period and the soot blowing time period, obtain the heat loss real-time deviation reference curves of different heating surfaces, and then obtain the heat loss real-time deviation reference formulas of different heating surfaces;

[0045] A first calculation unit is used to calculate the critical value of heat loss real-time deviation, the critical value of heat loss cumulative deviation and the critical value of dust accumulation time of each heating surface based on the heat loss real-time deviation reference formula;

[0046] The second calculation unit is used to obtain the real-time operating parameters of different heating surfaces collected in advance, and calculate the current value of the real-time deviation of heat loss of each heating surface, the current value of the cumulative deviation of heat loss and the current value of the dust accumulation time;

[0047] A first comparison unit is used to compare the current value of the heat loss cumulative deviation with the critical value of the heat loss cumulative deviation, and if the current value of the heat loss cumulative deviation is less than the critical value of the heat loss cumulative deviation, enter the second comparison unit, otherwise enter the soot blowing operation unit;

[0048] A second comparison unit is used to compare the current value of the heat loss real-time deviation with the heat loss real-time deviation critical value, and if the current value of the heat loss real-time deviation is less than the heat loss real-time deviation critical value, enter the fourth comparison unit, otherwise enter the third comparison unit;

[0049] A third comparison unit is used to compare the current value of the heat loss cumulative deviation with 75% of the heat loss cumulative deviation critical value, and if the current value of the heat loss cumulative deviation is greater than or equal to 75% of the heat loss cumulative deviation critical value, enter the soot blowing operation unit, otherwise enter the fourth comparison unit;

[0050] A fourth comparison unit, used for comparing the current value of the dust accumulation time with twice the critical value of the dust accumulation time, and if the current value of the dust accumulation time is greater than or equal to twice the critical value of the dust accumulation time, entering the soot blowing operation unit, otherwise entering the judgment unit;

[0051] A judgment unit is used to judge the exhaust gas temperature of the boiler. If the exhaust gas temperature exceeds the exhaust gas temperature assessment value by 30K or more and the ratio of the current value of the heat loss cumulative deviation to the critical value of the heat loss cumulative deviation is greater than or equal to 50%, the heating surface with the highest current value of the heat loss cumulative deviation to the critical value of the heat loss cumulative deviation enters the soot blowing operation unit, otherwise it enters the second calculation unit;

[0052] The sootblowing operation unit is used to calculate the recommended sootblowing time for the heating surface that meets the sootblowing conditions, perform sootblowing operations, and ensure that the sootblowing time is within the limited working time range of the sootblower and there is only one sootblowing heating surface, and then return to the second calculation unit for the next calculation.

[0053] Furthermore, in the heat loss real-time deviation history curve acquisition unit, the heat loss real-time deviation of different heating surfaces is calculated, and the formula is as follows:

[0054] Heat loss real-time deviation:

[0055] Heat loss: q L-i =q t-i -q a-i ;

[0056] The actual amount of heat absorbed by each heating surface: q a-i =m i (h″ i -h′ i );

[0057] Convection heating surface clean heat absorption:

[0058] Semi-radiant heating surface clean heat absorption:

[0059] Heat absorption of furnace cleaning: The average flame temperature

[0060] In the above formula, the subscript i is the type of heating surface, X is convection, Y is semi-radiation, and Z is the furnace; Δq L-i is the real-time deviation of heat loss of type i heating surface (kW); q L-i is the heat loss of type i heating surface (kW); is the initial heat loss of type i heating surface (kW); q t-i is the clean heat absorption of type i heating surface (kW); q a-i is the actual heat absorption of type i heating surface (kW); m i is the working fluid flow rate of type i heating surface (kg / s); h i ′、h i ″ are the inlet and outlet enthalpy values ​​of the i-type heating surface (kJ / kg); q t-X ,q t-Y and q t-Z are convection, semi-radiation and clean heat absorption of furnace heating surface (kW); H X , H Y and H Z Convection, semi-radiation and furnace heating surface areas (m 2 );ΔT X , ΔT Y are the heat transfer temperature differences of convection and semi-radiation heating surfaces (K); α 1-X , α 1-Y are the heat release coefficients of the convective and semi-radiative flue gas sides (kW / (m 2 ·K)); α 2-X , α 2-Y are the heat absorption coefficients of the convection and semi-radiation working fluid sides (kW / (m 2 ·K));r Yk is the ratio of the heat absorbed by the semi-radiant heating surface to the heat absorbed by convection; Y is the ratio of the radiation at the furnace outlet absorbed by the semi-radiant heating surface; ψ p,f Obtain the furnace direct radiation heat effectiveness coefficient for the furnace outlet heating surface; ε f is the furnace blackness; T f ″ is the flue gas temperature at the furnace outlet (K); A f is the cross-sectional area of ​​the furnace outlet smoke window (m 2 );σ0 is the Boltzmann constant, usually 5.67×10 - 11 kW / (m 2 ·K 4 );ψ0 is the thermal efficiency coefficient of the clean water-cooled wall; T fl is the average flame temperature (K); M is the relative center of the flame; T th is the theoretical combustion temperature of the furnace (K).

[0061] Furthermore, the heat loss real-time deviation reference formula acquisition unit includes:

[0062] The sorting module is used to sort out all real-time deviation history curves of heat loss under different loads and separate the soot accumulation time period and soot blowing time period;

[0063] The average change calculation module is used to calculate the average change of all curves in each sampling time period;

[0064] A real-time deviation reference curve acquisition module is used to accumulate the average change in each sampling time period along the time growth to obtain a real-time deviation reference curve;

[0065] The data fitting module is used to perform data fitting to obtain the reference formula for the dust accumulation time period and the dust blowing time period. The fitting formula is as follows:

[0066] Real-time deviation fitting of heat loss during dust accumulation period:

[0067] Real-time deviation fitting of heat loss during sootblowing period:

[0068] In the above formula, are the real-time deviation of heat loss during the soot accumulation period and the soot blowing period (kW); t f is the dust accumulation time (s); t s is the soot blowing time (s); A, B, C, D, E are all fitting parameters.

[0069] Furthermore, in the first calculation unit, the calculation of the critical value of the real-time deviation of heat loss of each heating surface, the critical value of the cumulative deviation of heat loss and the critical value of the dust accumulation time includes:

[0070] Net gain through maximum sootblowing:

[0071]

[0072] The following parameters are calculated:

[0073] Critical value of dust accumulation time: t fopt

[0074] Heat loss real-time deviation critical value:

[0075] Heat loss cumulative deviation critical value:

[0076] In the above formula, Q Bnet is the net soot blowing benefit (kJ); q s is the soot blowing energy loss per unit time (kW); t smin and t smax are the minimum and maximum sootblowing time (s) limited by the sootblower; t fopt It is the critical value of dust accumulation time.

[0077] Furthermore, in the first comparison unit, the calculation formula for the current value of the heat loss cumulative deviation is: Where Δt is the data collection interval (s); in the sootblowing operation unit, the formula for calculating the recommended sootblowing time for the heating surface to reach the sootblowing condition is: where t sopt This is the recommended soot blowing time.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] 1. The present invention uses the cumulative deviation of heat loss on the heating surface as the main parameter for evaluating the degree of dust accumulation. The cumulative deviation can be considered as a process quantity, which avoids the problem of misjudgment of soot blowing operation caused by multiple and wide fluctuations of instantaneous quantities such as cleaning factor and contamination rate when the load changes too fast in the AGC mode;

[0080] 2. On the basis of the heat loss cumulative deviation as the main evaluation parameter, the soot blowing operation scheme of the present invention also introduces the heat loss real-time deviation and the dust accumulation time. On the one hand, the heat loss real-time deviation can reflect the real-time state of dust accumulation, while the cumulative deviation more reflects the impact on the overall heat exchange of the boiler. The introduction of the real-time deviation makes the evaluation result of the dust accumulation impact more accurate, avoids the single evaluation parameter being greatly affected in the multi-disturbance process, and ensures that the proposed soot blowing operation scheme is more suitable for the actual operation of the boiler. On the other hand, the introduction of the dust accumulation time can avoid the serious problem of fusible dust accumulation and slagging on the high-temperature heating surface due to the monitoring index failing to reach the critical value for a long time during deep peak regulation;

[0081] 3. Considering the operation assessment of the power plant, the present invention also introduces the exhaust gas temperature as an evaluation parameter, making the soot blowing operation scheme proposed by the present invention more comprehensive;

[0082] 4. The present invention does not require additional measuring points in the power plant, is applicable to different coal-fired boiler types and any type of soot blower, and has strong versatility and popularization. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 It is a flow chart of a boiler soot blowing operation method applicable to deep peak regulation and AGC mode provided by an embodiment of the present invention;

[0084] Figure 2 is the result of determining the timing and duration of soot blowing in Example 1 of the present invention;

[0085] Figure 3 This is the result of determining the timing and duration of sootblowing in Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0086] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0087] The implementation case selected a 650MW supercritical boiler platen superheater, a typical semi-radiant heating surface, equipped with 10 steam soot blowers (two opened at a time).

[0088] Example 1

[0089] According to the boiler soot blowing operation method applicable to deep peak load regulation and AGC mode provided by the present invention, the application process of this embodiment specifically involves the following steps:

[0090] Step (1): collecting historical operating data of the boiler platen superheater, calculating the real-time deviation of heat loss under different operating conditions, and forming a curve according to time distribution;

[0091] Heat loss real-time deviation:

[0092] Heat loss: q L-Y =q t-Y -q a-Y ;

[0093] Actual heat absorption of the heating surface: q a-Y =m Y (h″ Y -h′ Y );

[0094] Heating surface clean heat absorption:

[0095] Step (2): a large number of heat loss real-time deviation historical curves calculated in step (1) are selected and classified according to the soot accumulation time period and the soot blowing time period, and the heat loss real-time deviation reference curves and reference formulas for different heating surfaces are determined;

[0096] After calculating the data in steps (1) and (2), the reference formula for the platen superheater in this case is as follows:

[0097] Dust accumulation time period: (t≥0, unit: s)

[0098] Sootblowing time period: (t f ≤t≤t f +t s , unit s)

[0099] Step (3): Based on the heat loss real-time deviation reference formula obtained in step (2) and the principle of maximum net sootblowing benefit, calculate the heat loss real-time deviation critical value, cumulative deviation critical value and soot accumulation time critical value of each heating surface;

[0100] Heat loss real-time deviation critical value:

[0101] Heat loss cumulative deviation critical value:

[0102] Critical value of dust accumulation time: t fopt =30122s

[0103] Step (4): collecting real-time operating parameters of different heating surfaces, and calculating the current values ​​of the real-time deviation and cumulative deviation of heat loss of each heating surface;

[0104] Step (5): contrast If the current value of the heat loss cumulative deviation is less than the critical value, proceed to step (6); if the current value of the heat loss cumulative deviation is greater than or equal to the critical value, proceed to step (10);

[0105] Step (6): Δq L-Y contrast If the current value of the heat loss real-time deviation is less than the critical value, proceed to step (8); if the current value of the heat loss real-time deviation is greater than or equal to the critical value, proceed to step (7);

[0106] Step (7): contrast If the current value of the heat loss cumulative deviation is greater than or equal to 75% of the critical value, proceed to step (10); otherwise, proceed to step (8);

[0107] Step (8): t f Compare 2t fopt , if the current value of the dust accumulation time is greater than or equal to twice the critical value, proceed to step (10), otherwise proceed to step (9);

[0108] Step (9): Determine the boiler exhaust temperature. In case 1, the boiler exhaust temperature overtemperature in the load section is less than 30K, so this judgment condition can be skipped.

[0109] Step (10): Calculate the recommended sootblowing time for the heating surface that meets the sootblowing conditions (distribute to each sootblower), perform the sootblowing operation, and ensure that the sootblowing time is within the limited working time range of the sootblower and there is only one sootblowing heating surface (different heating surfaces meet the sootblowing conditions at the same time, and the one with a higher cumulative deviation of heat loss), and then return to step (4) for the next calculation;

[0110] As attached Figure 2 After calculation, it is found that if the traditional instantaneous value judgment method is used under the load of Case 1, more disturbance results will appear, which greatly interferes with the operator's soot blowing judgment; if the scheme proposed by the present invention is adopted, since the overall change trend of the heat loss cumulative deviation is monotonically increasing and almost no fluctuation, on the basis of the heat loss cumulative deviation as the main judgment parameter, the heat loss real-time deviation is introduced to reflect the real-time change of dust accumulation. Case 1 is best to perform soot blowing when step (6) and step (7) are met at the same time (that is, the heat loss real-time deviation reaches the critical value, and the heat loss cumulative deviation reaches 75% of the critical value). The dust accumulation time is 27300s, and the recommended soot blowing time is 4500s (cannot exceed the soot blower time limit). The soot blowing time of each pair of soot blowers (2 at the same time) is 900s.

[0111] Example 2

[0112] This embodiment adopts the platen superheater of Case 1, and the specific steps are as follows:

[0113] Since the heating surface is the same and the historical data is exactly the same, the historical reference curve, reference formula, dust accumulation time critical value, heat loss real-time deviation critical value and heat loss cumulative deviation critical value calculated in steps (1) to (3) in Example 2 are exactly the same as those in Example 1. The following description starts from step (4).

[0114] Step (4): collecting real-time operating parameters of different heating surfaces, and calculating the current values ​​of the real-time deviation and cumulative deviation of heat loss of each heating surface;

[0115] Step (5): contrast If the current value of the heat loss cumulative deviation is less than the critical value, proceed to step (6); if the current value of the heat loss cumulative deviation is greater than or equal to the critical value, proceed to step (10);

[0116] Step (6): Δq L-Y contrast If the current value of the heat loss real-time deviation is less than the critical value, proceed to step (8); if the current value of the heat loss real-time deviation is greater than or equal to the critical value, proceed to step (7);

[0117] Step (7): contrast If the current value of the heat loss cumulative deviation is greater than or equal to 75% of the critical value, proceed to step (10); otherwise, proceed to step (8);

[0118] Step (8): t f Compare 2t fopt , if the current value of the dust accumulation time is greater than or equal to twice the critical value, proceed to step (10), otherwise proceed to step (9);

[0119] Step (9): Determine the boiler exhaust temperature. The boiler exhaust temperature overtemperature in the load section of Case 2 is less than 30K, so this evaluation condition can be skipped.

[0120] Step (10): Calculate the recommended sootblowing time for the heating surface that meets the sootblowing conditions (distribute to each sootblower), perform the sootblowing operation, and ensure that the sootblowing time is within the limited working time range of the sootblower and there is only one sootblowing heating surface (different heating surfaces meet the sootblowing conditions at the same time, and the one with a higher cumulative deviation of heat loss), and then return to step (4) for the next calculation;

[0121] As attached Figure 3 After calculation, it is found that if the traditional instantaneous value judgment method is used under the load of Case 2, the real-time deviation of heat loss under this load will not reach the critical value for a long time, resulting in too long dust accumulation time, which will cause serious risk of molten dust accumulation and slagging; if the scheme proposed in the present invention is adopted, then Case 2 is best to perform soot blowing when step (5) (that is, the cumulative deviation of heat loss reaches the critical value), the dust accumulation time is 41880s, the recommended soot blowing time is 2100s (not less than the soot blowing time limit), and the soot blowing time of each pair of soot blowers (2 at the same time) is 420s.

[0122] Example 3

[0123] This embodiment provides a boiler soot blowing operation system suitable for deep peak regulation and AGC mode, including:

[0124] A heat loss real-time deviation history curve acquisition unit is used to acquire the pre-collected historical operation data of different heating surfaces of the boiler, calculate the real-time deviation of heat loss of different heating surfaces, and form a heat loss real-time deviation history curve according to time distribution;

[0125] A heat loss real-time deviation reference formula acquisition unit is used to select and classify the heat loss real-time deviation historical curve according to the soot accumulation time period and the soot blowing time period, obtain the heat loss real-time deviation reference curves of different heating surfaces, and then obtain the heat loss real-time deviation reference formulas of different heating surfaces;

[0126] A first calculation unit is used to calculate the critical value of heat loss real-time deviation, the critical value of heat loss cumulative deviation and the critical value of dust accumulation time of each heating surface based on the heat loss real-time deviation reference formula;

[0127] The second calculation unit is used to obtain the real-time operating parameters of different heating surfaces collected in advance, and calculate the current value of the real-time deviation of heat loss of each heating surface, the current value of the cumulative deviation of heat loss and the current value of the dust accumulation time;

[0128] A first comparison unit is used to compare the current value of the heat loss cumulative deviation with the critical value of the heat loss cumulative deviation, and if the current value of the heat loss cumulative deviation is less than the critical value of the heat loss cumulative deviation, enter the second comparison unit, otherwise enter the soot blowing operation unit;

[0129] A second comparison unit is used to compare the current value of the heat loss real-time deviation with the heat loss real-time deviation critical value, and if the current value of the heat loss real-time deviation is less than the heat loss real-time deviation critical value, enter the fourth comparison unit, otherwise enter the third comparison unit;

[0130] A third comparison unit is used to compare the current value of the heat loss cumulative deviation with 75% of the heat loss cumulative deviation critical value, and if the current value of the heat loss cumulative deviation is greater than or equal to 75% of the heat loss cumulative deviation critical value, enter the soot blowing operation unit, otherwise enter the fourth comparison unit;

[0131] A fourth comparison unit, used for comparing the current value of the dust accumulation time with twice the critical value of the dust accumulation time, and if the current value of the dust accumulation time is greater than or equal to twice the critical value of the dust accumulation time, entering the soot blowing operation unit, otherwise entering the judgment unit;

[0132] A judgment unit is used to judge the exhaust gas temperature of the boiler. If the exhaust gas temperature exceeds the exhaust gas temperature assessment value by 30K or more and the ratio of the current value of the heat loss cumulative deviation to the critical value of the heat loss cumulative deviation is greater than or equal to 50%, the heating surface with the highest current value of the heat loss cumulative deviation to the critical value of the heat loss cumulative deviation enters the soot blowing operation unit, otherwise it enters the second calculation unit;

[0133] The sootblowing operation unit is used to calculate the recommended sootblowing time for the heating surface that meets the sootblowing conditions, perform sootblowing operations, and ensure that the sootblowing time is within the limited working time range of the sootblower and there is only one sootblowing heating surface, and then return to the second calculation unit for the next calculation.

[0134] Specifically, in the heat loss real-time deviation history curve acquisition unit, the heat loss real-time deviation of different heating surfaces is calculated according to the following formula:

[0135] Heat loss real-time deviation:

[0136] Heat loss: q L-i =q t-i -q a-i ;

[0137] The actual amount of heat absorbed by each heating surface: q a-i =m i (h″ i -h′ i );

[0138] Convection heating surface clean heat absorption:

[0139] Semi-radiant heating surface clean heat absorption:

[0140] Heat absorption of furnace cleaning: The average flame temperature

[0141] In the above formula, the subscript i is the type of heating surface, X is convection, Y is semi-radiation, and Z is the furnace; Δq L-i is the real-time deviation of heat loss of type i heating surface (kW); q L-i is the heat loss of type i heating surface (kW); is the initial heat loss of type i heating surface (kW); q t-i is the clean heat absorption of type i heating surface (kW); q a-i is the actual heat absorption of type i heating surface (kW); m i is the working fluid flow rate of type i heating surface (kg / s); h i ′、h i ″ are the inlet and outlet enthalpy values ​​of the i-type heating surface (kJ / kg); q t-X ,q t-Y and q t-Z are convection, semi-radiation and clean heat absorption of furnace heating surface (kW); H X , H Y and H Z Convection, semi-radiation and furnace heating surface areas (m 2 );ΔT X , ΔT Y are the heat transfer temperature differences of convection and semi-radiation heating surfaces (K); α 1-X , α 1-Y are the heat release coefficients of the convective and semi-radiative flue gas sides (kW / (m2 ·K)); α 2-X , α 2-Y are the heat absorption coefficients of the convection and semi-radiation working fluid sides (kW / (m 2 ·K));r Y k is the ratio of the heat absorbed by the semi-radiant heating surface to the heat absorbed by convection; Y is the ratio of the radiation at the furnace outlet absorbed by the semi-radiant heating surface; ψ p,f Obtain the furnace direct radiation heat effectiveness coefficient for the furnace outlet heating surface; ε f is the furnace blackness; T f ″ is the flue gas temperature at the furnace outlet (K); A f is the cross-sectional area of ​​the furnace outlet smoke window (m 2 );σ0 is the Boltzmann constant, usually 5.67×10 - 11 kW / (m 2 ·K 4 );ψ0 is the thermal efficiency coefficient of the clean water-cooled wall; T fl is the average flame temperature (K); M is the relative center of the flame; T th is the theoretical combustion temperature of the furnace (K).

[0142] Specifically, the heat loss real-time deviation reference formula acquisition unit includes:

[0143] The sorting module is used to sort out all real-time deviation history curves of heat loss under different loads and separate the soot accumulation time period and soot blowing time period;

[0144] The average change calculation module is used to calculate the average change of all curves in each sampling time period;

[0145] A real-time deviation reference curve acquisition module is used to accumulate the average change in each sampling time period along the time growth to obtain a real-time deviation reference curve;

[0146] The data fitting module is used to perform data fitting to obtain the reference formula for the dust accumulation time period and the dust blowing time period. The fitting formula is as follows:

[0147] Real-time deviation fitting of heat loss during dust accumulation period:

[0148] Real-time deviation fitting of heat loss during sootblowing period:

[0149] In the above formula, are the real-time deviation of heat loss during the soot accumulation period and the soot blowing period (kW); t f is the dust accumulation time (s); t sis the soot blowing time (s); A, B, C, D, E are all fitting parameters.

[0150] Specifically, in the first calculation unit, the calculation of the critical value of the real-time deviation of heat loss of each heating surface, the critical value of the cumulative deviation of heat loss and the critical value of the dust accumulation time includes:

[0151] Net gain through maximum sootblowing:

[0152]

[0153] The following parameters are calculated:

[0154] Critical value of dust accumulation time: t fopt

[0155] Heat loss real-time deviation critical value:

[0156] Heat loss cumulative deviation critical value:

[0157] In the above formula, Q Bnet is the net soot blowing benefit (kJ); q s is the soot blowing energy loss per unit time (kW); t smin and t smax are the minimum and maximum sootblowing time (s) limited by the sootblower; t fopt It is the critical value of dust accumulation time.

[0158] Specifically, in the first comparison unit, the calculation formula for the current value of the heat loss cumulative deviation is: Where Δt is the data collection interval (s); in the sootblowing operation unit, the formula for calculating the recommended sootblowing time for the heating surface to reach the sootblowing condition is: where t sopt This is the recommended soot blowing time.

[0159] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A boiler sootblowing operation method suitable for deep peak regulation and AGC mode, characterized in that: include: Obtain the pre-collected historical operation data of different heating surfaces of the boiler, calculate the real-time deviation of heat loss of different heating surfaces, and form a real-time deviation history curve of heat loss according to time distribution; The heat loss real-time deviation historical curve is selected and classified according to the soot accumulation time period and the soot blowing time period to obtain the heat loss real-time deviation reference curves of different heating surfaces, and then obtain the heat loss real-time deviation reference formulas of different heating surfaces; Based on the heat loss real-time deviation reference formula, calculate the heat loss real-time deviation critical value, heat loss cumulative deviation critical value and dust accumulation time critical value of each heating surface; Calculation steps: obtaining the real-time operating parameters of different heating surfaces collected in advance, and calculating the current value of the real-time deviation of heat loss, the current value of the cumulative deviation of heat loss and the current value of the dust accumulation time of each heating surface; A first comparison step: comparing the current value of the heat loss cumulative deviation with the critical value of the heat loss cumulative deviation, and if the current value of the heat loss cumulative deviation is less than the critical value of the heat loss cumulative deviation, performing a second comparison step, otherwise performing a soot blowing operation step; A second comparison step: comparing the current value of the heat loss real-time deviation with the heat loss real-time deviation critical value, and if the current value of the heat loss real-time deviation is less than the heat loss real-time deviation critical value, performing a fourth comparison step, otherwise performing a third comparison step; A third comparison step: comparing the current value of the heat loss cumulative deviation with 75% of the heat loss cumulative deviation critical value, and if the current value of the heat loss cumulative deviation is greater than or equal to 75% of the heat loss cumulative deviation critical value, performing a soot blowing operation step, otherwise performing a fourth comparison step; Fourth comparison step: comparing the current value of the dust accumulation time with twice the critical value of the dust accumulation time, if the current value of the dust accumulation time is greater than or equal to twice the critical value of the dust accumulation time, performing a soot blowing operation step, otherwise performing a judgment step; Judgment step: judge the boiler exhaust gas temperature. If the exhaust gas temperature exceeds the exhaust gas temperature assessment value by 30K or more and the ratio of the current value of the heat loss cumulative deviation to the critical value of the heat loss cumulative deviation is greater than or equal to 50%, then the soot blowing operation step is performed on the heating surface with the highest current value of the heat loss cumulative deviation / critical value of the heat loss cumulative deviation, otherwise the calculation step is performed; Sootblowing operation steps: calculate the recommended sootblowing time for the heating surface that meets the sootblowing conditions, perform the sootblowing operation, and ensure that the sootblowing time is within the limited working time range of the sootblower and there is only one sootblowing heating surface, and then return to the calculation step for the next calculation.

2. The boiler sootblowing operation method suitable for deep peak load regulation and AGC mode according to claim 1, characterized in that: The formula for calculating the real-time deviation of heat loss on different heating surfaces is as follows: Heat loss real-time deviation: Heat loss: q L-i =q t-i -q a-i ; The actual amount of heat absorbed by each heating surface: q a-i =m i (h″ i -h′ i ); Convection heating surface clean heat absorption: Semi-radiant heating surface clean heat absorption: Heat absorption of furnace cleaning: The average flame temperature In the above formula, the subscript i is the type of heating surface, X is convection, Y is semi-radiation, and Z is the furnace; Δq L-i is the real-time deviation of heat loss of type i heating surface (kW); q L-i is the heat loss of type i heating surface (kW); is the initial heat loss of type i heating surface (kW); q t-i is the clean heat absorption of type i heating surface (kW); q a-i is the actual heat absorption of type i heating surface (kW); m i is the working fluid flow rate of type i heating surface (kg / s); h i ′、h i ″ are the inlet and outlet enthalpy values ​​of the i-type heating surface (kJ / kg); q t-X ,q t-Y and q t-Z are convection, semi-radiation and clean heat absorption of furnace heating surface (kW); H X , H Y and H Z Convection, semi-radiation and furnace heating surface areas (m 2 );ΔT X , ΔT Y are the heat transfer temperature differences of convection and semi-radiation heating surfaces (K); α 1-X , α 1-Y are the heat release coefficients of the convective and semi-radiative flue gas sides (kW / (m 2 ·K)); α 2-X , α 2-Y are the heat absorption coefficients of the convection and semi-radiation working fluid sides (kW / (m 2 ·K));r Y k is the ratio of the heat absorbed by the semi-radiant heating surface to the heat absorbed by convection; Y is the ratio of the radiation at the furnace outlet absorbed by the semi-radiant heating surface; ψ p,f Obtain the furnace direct radiation heat effectiveness coefficient for the furnace outlet heating surface; ε f is the furnace blackness; T f ″ is the flue gas temperature at the furnace outlet (K); A f is the cross-sectional area of ​​the furnace outlet smoke window (m 2 );σ0 is the Boltzmann constant, usually 5.67×10 -11 kW / (m 2 ·K 4 );ψ0 is the thermal efficiency coefficient of the clean water-cooled wall; T fl is the average flame temperature (K); M is the relative center of the flame; T th is the theoretical combustion temperature of the furnace (K).

3. The boiler sootblowing operation method applicable to deep peak load regulation and AGC mode according to claim 1, characterized in that: The method for obtaining the heat loss real-time deviation reference curve and the heat loss real-time deviation reference formula includes: Arrange all real-time deviation history curves of heat loss under different loads, and separate the soot accumulation period and soot blowing period; Calculate the average change of all curves in each sampling time period; The average change in each sampling time period is accumulated along the time growth to obtain the real-time deviation reference curve; The reference formula for the soot accumulation time period and the soot blowing time period is obtained by data fitting. The fitting formula is as follows: Real-time deviation fitting of heat loss during dust accumulation period: Real-time deviation fitting of heat loss during sootblowing period: In the above formula, are the real-time deviation of heat loss during the soot accumulation period and the soot blowing period (kW); t f is the dust accumulation time (s); t s is the soot blowing time (s); A, B, C, D, E are all fitting parameters.

4. The boiler sootblowing operation method applicable to deep peak load regulation and AGC mode according to claim 1, characterized in that: The calculation of the critical value of heat loss real-time deviation, the critical value of heat loss cumulative deviation and the critical value of dust accumulation time of each heating surface includes: Net gain through maximum sootblowing: The following parameters are calculated: Critical value of dust accumulation time: t fopt Heat loss real-time deviation critical value: Heat loss cumulative deviation critical value: In the above formula, Q Bnet is the net soot blowing benefit (kJ); q s is the soot blowing energy loss per unit time (kW); t smin and t smax are the minimum and maximum sootblowing time (s) limited by the sootblower; t fopt It is the critical value of dust accumulation time.

5. The boiler soot blowing operation method applicable to deep peak load regulation and AGC mode according to claim 1, characterized in that: The calculation formula for the current value of the heat loss cumulative deviation is: Where Δt is the data collection interval (s); the formula for calculating the recommended soot blowing time for the heated surface to meet the soot blowing conditions is: where t sopt This is the recommended soot blowing time.

6. A boiler sootblowing operating system suitable for deep peak regulation and AGC mode, characterized in that: include: A heat loss real-time deviation history curve acquisition unit is used to acquire the pre-collected historical operation data of different heating surfaces of the boiler, calculate the real-time deviation of heat loss of different heating surfaces, and form a heat loss real-time deviation history curve according to time distribution; A heat loss real-time deviation reference formula acquisition unit is used to select and classify the heat loss real-time deviation historical curve according to the soot accumulation time period and the soot blowing time period, obtain the heat loss real-time deviation reference curves of different heating surfaces, and then obtain the heat loss real-time deviation reference formulas of different heating surfaces; A first calculation unit is used to calculate the critical value of heat loss real-time deviation, the critical value of heat loss cumulative deviation and the critical value of dust accumulation time of each heating surface based on the heat loss real-time deviation reference formula; The second calculation unit is used to obtain the real-time operating parameters of different heating surfaces collected in advance, and calculate the current value of the real-time deviation of heat loss of each heating surface, the current value of the cumulative deviation of heat loss and the current value of the dust accumulation time; A first comparison unit is used to compare the current value of the heat loss cumulative deviation with the critical value of the heat loss cumulative deviation, and if the current value of the heat loss cumulative deviation is less than the critical value of the heat loss cumulative deviation, enter the second comparison unit, otherwise enter the soot blowing operation unit; A second comparison unit is used to compare the current value of the heat loss real-time deviation with the heat loss real-time deviation critical value, and if the current value of the heat loss real-time deviation is less than the heat loss real-time deviation critical value, enter the fourth comparison unit, otherwise enter the third comparison unit; A third comparison unit is used to compare the current value of the heat loss cumulative deviation with 75% of the heat loss cumulative deviation critical value, and if the current value of the heat loss cumulative deviation is greater than or equal to 75% of the heat loss cumulative deviation critical value, enter the soot blowing operation unit, otherwise enter the fourth comparison unit; A fourth comparison unit, used for comparing the current value of the dust accumulation time with twice the critical value of the dust accumulation time, and if the current value of the dust accumulation time is greater than or equal to twice the critical value of the dust accumulation time, entering the soot blowing operation unit, otherwise entering the judgment unit; A judgment unit is used to judge the exhaust gas temperature of the boiler. If the exhaust gas temperature exceeds the exhaust gas temperature assessment value by 30K or more and the ratio of the current value of the heat loss cumulative deviation to the critical value of the heat loss cumulative deviation is greater than or equal to 50%, the heating surface with the highest current value of the heat loss cumulative deviation to the critical value of the heat loss cumulative deviation enters the soot blowing operation unit, otherwise it enters the second calculation unit; The sootblowing operation unit is used to calculate the recommended sootblowing time for the heating surface that meets the sootblowing conditions, perform sootblowing operations, and ensure that the sootblowing time is within the limited working time range of the sootblower and there is only one sootblowing heating surface, and then return to the second calculation unit for the next calculation.

7. The boiler soot blowing operation system suitable for deep peak load regulation and AGC mode according to claim 6, characterized in that: In the heat loss real-time deviation history curve acquisition unit, the heat loss real-time deviation of different heating surfaces is calculated, and the formula is as follows: Heat loss real-time deviation: Heat loss: q L-i =q t-i -q a-i ; The actual amount of heat absorbed by each heating surface: q a-i =m i (h″ i -h′ i ); Convection heating surface clean heat absorption: Semi-radiant heating surface clean heat absorption: Heat absorption of furnace cleaning: The average flame temperature In the above formula, the subscript i is the type of heating surface, X is convection, Y is semi-radiation, and Z is the furnace; Δq L-i is the real-time deviation of heat loss of type i heating surface (kW); q L-i is the heat loss of type i heating surface (kW); is the initial heat loss of type i heating surface (kW); q t-i is the clean heat absorption of type i heating surface (kW); q a-i is the actual heat absorption of type i heating surface (kW); m i is the working fluid flow rate of type i heating surface (kg / s); h i ′、h i ″ are the inlet and outlet enthalpy values ​​of the i-type heating surface (kJ / kg); q t-X ,q t-Y and q t-Z are convection, semi-radiation and clean heat absorption of furnace heating surface (kW); H X , H Y and H Z Convection, semi-radiation and furnace heating surface areas (m 2 );ΔT X , ΔT Y are the heat transfer temperature differences of convection and semi-radiation heating surfaces (K); α 1-X , α 1-Y are the heat release coefficients of the convective and semi-radiative flue gas sides (kW / (m 2 ·K)); α 2-X , α 2-Y are the heat absorption coefficients of the convection and semi-radiation working fluid sides (kW / (m 2 ·K));r Y k is the ratio of the heat absorbed by the semi-radiant heating surface to the heat absorbed by convection; Y is the ratio of the radiation at the furnace outlet absorbed by the semi-radiant heating surface; ψ p,f Obtain the furnace direct radiation heat effectiveness coefficient for the furnace outlet heating surface; ε f is the furnace blackness; T f ″ is the flue gas temperature at the furnace outlet (K); A f is the cross-sectional area of ​​the furnace outlet smoke window (m 2 );σ0 is the Boltzmann constant, usually 5.67×10 -11 kW / (m 2 ·K 4 );ψ0 is the thermal efficiency coefficient of the clean water-cooled wall; T fl is the average flame temperature (K); M is the relative center of the flame; T th is the theoretical combustion temperature of the furnace (K).

8. The boiler soot blowing operation system suitable for deep peak load regulation and AGC mode according to claim 6, characterized in that: The heat loss real-time deviation reference formula acquisition unit includes: The sorting module is used to sort out all real-time deviation history curves of heat loss under different loads and separate the soot accumulation time period and soot blowing time period; The average change calculation module is used to calculate the average change of all curves in each sampling time period; A real-time deviation reference curve acquisition module is used to accumulate the average change in each sampling time period along the time growth to obtain a real-time deviation reference curve; The data fitting module is used to perform data fitting to obtain the reference formula for the dust accumulation time period and the dust blowing time period. The fitting formula is as follows: Real-time deviation fitting of heat loss during dust accumulation period: Real-time deviation fitting of heat loss during sootblowing period: In the above formula, are the real-time deviation of heat loss during the soot accumulation period and the soot blowing period (kW); t f is the dust accumulation time (s); t s is the soot blowing time (s); A, B, C, D, E are all fitting parameters.

9. The boiler soot blowing operation system suitable for deep peak load regulation and AGC mode according to claim 6, characterized in that: In the first calculation unit, the calculation of the critical value of heat loss real-time deviation, the critical value of heat loss cumulative deviation and the critical value of dust accumulation time of each heating surface includes: Net gain through maximum sootblowing: The following parameters are calculated: Critical value of dust accumulation time: t fopt Heat loss real-time deviation critical value: Heat loss cumulative deviation critical value: In the above formula, Q Bnet is the net soot blowing benefit (kJ); q s is the soot blowing energy loss per unit time (kW); t smin and t smax are the minimum and maximum sootblowing time (s) limited by the sootblower; t fopt It is the critical value of dust accumulation time.

10. According to the boiler soot blowing operation system suitable for deep peak load regulation and AGC mode according to claim 6, in the first comparison unit, the calculation formula of the current value of the heat loss cumulative deviation is: Where Δt is the data collection interval (s); in the sootblowing operation unit, the formula for calculating the recommended sootblowing time for the heating surface to reach the sootblowing condition is: where t sopt This is the recommended soot blowing time.

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