A steam temperature control method, device, equipment and readable storage medium

Abstract

The application discloses a steam temperature control method and device, equipment and a readable storage medium, and relates to the technical field of control. The method comprises the following steps: obtaining basic data of a heating surface of a superheater; calculating a comprehensive heat storage coefficient of the heating surface of the superheater and a change rate of the comprehensive heat storage coefficient according to the basic data; determining a target steam temperature at an inlet of the heating surface of the superheater according to the comprehensive heat storage coefficient and the change rate of the comprehensive heat storage coefficient; calculating a desuperheating water quantity according to the target steam temperature and a current steam temperature at the inlet of the heating surface of the superheater; and controlling a desuperheater to release the desuperheating water based on the desuperheating water quantity, so that the current steam temperature is adjusted to the target steam temperature. It can be seen that the application effectively overcomes the problems of large adjustment delay and large difference in object characteristics of the superheater under different loads and different combustion conditions in the prior art, so that the steam temperature can be controlled more accurately, and the accuracy of steam temperature control is improved.

Description

Technical Field

[0001] This application relates to the field of control technology, and more specifically, to a steam temperature control method, apparatus, device, and readable storage medium. Background Technology

[0002] Steam temperature is a crucial parameter for the safe, efficient, and economical operation of thermal power units. Therefore, the requirements for steam temperature control are quite stringent. Excessively high steam temperatures can cause damage to the superheater and high-pressure turbine cylinder due to excessive thermal stress, while excessively low steam temperatures will reduce the unit's thermal efficiency and affect economic operation. The main and reheat steam temperature control methods for coal-fired boilers primarily include desuperheating water and flue gas dampers, with desuperheating water being the primary method. Water spray desuperheating involves directly injecting water into the superheated steam; the water absorbs heat from the steam, thus reducing the steam temperature.

[0003] Traditional desuperheating water control methods widely adopt a cascade PID control strategy with main steam temperature as the primary control, desuperheating water outlet temperature as the secondary control, and unit load as the feedforward. However, this control method usually suffers from problems such as large delay, many interference factors, significant influence from combustion conditions, and large differences in superheater characteristics under different loads and combustion conditions. As a result, the control accuracy of this desuperheating water control method is low, and it cannot achieve accurate control of steam temperature. Summary of the Invention

[0004] This application provides a steam temperature control method, apparatus, device, and readable storage medium, which can control the steam temperature more accurately and improve the accuracy of steam temperature control.

[0005] In view of this, embodiments of this application provide a steam temperature control method, including:

[0006] Obtain basic data of the superheater's heating surface;

[0007] Calculate the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the aforementioned basic data;

[0008] The target steam temperature at the inlet of the superheater heating surface is determined based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient.

[0009] The desuperheating water volume is calculated based on the target steam temperature and the current steam temperature at the inlet of the superheater heating surface.

[0010] Based on the desuperheating water volume control, the desuperheater releases desuperheating water to adjust the current steam temperature to the target steam temperature.

[0011] Optionally, the step of calculating the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the basic data includes:

[0012] Calculate the steam heat storage coefficient and metal heat storage coefficient of the superheater heating surface based on the aforementioned basic data;

[0013] The comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient are calculated based on the steam working fluid heat storage coefficient and the metal heat storage coefficient of the superheater heating surface.

[0014] Optionally, the step of calculating the steam working fluid heat storage coefficient and the metal heat storage coefficient of the superheater heating surface based on the basic data specifically includes:

[0015] The heat storage coefficient of the steam working fluid on the superheater heating surface is calculated based on the aforementioned basic data, specifically as follows:

[0016]

[0017] Among them, C pin C is the specific heat capacity of the inlet steam of the superheater heating surface; pout W is the specific heat capacity of the steam at the outlet of the superheater heating surface. steam T is the steam flow rate within the superheater's heating surface. in T is the inlet steam temperature of the superheater heating surface; out is the outlet steam temperature of the superheater heating surface; L is the length of a single tube of the superheater heating surface; v is the steam velocity in the superheater heating surface.

[0018] The metal heat storage coefficient of the superheater's heating surface is calculated based on the aforementioned basic data, specifically as follows:

[0019] QS metal =C pmetal ·G metal ·T metal ;

[0020] Among them, C pmetal G represents the specific heat capacity of the metal. metal For metallic mass; T metal This refers to the pipe wall temperature.

[0021] Optionally, the step of calculating the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the steam working fluid heat storage coefficient and the metal heat storage coefficient of the superheater heating surface specifically includes:

[0022] The comprehensive heat storage coefficient of the superheater heating surface is calculated based on the steam working fluid heat storage coefficient and the metal heat storage coefficient, specifically as follows:

[0023] QS syn =K1·QS steam +K2·QS metal ;

[0024] Where K1 and K2 are weighting coefficients, and K1+K2=1;

[0025] The rate of change of the comprehensive heat storage coefficient is calculated based on the comprehensive heat storage coefficient of the superheater's heating surface, specifically as follows:

[0026]

[0027] in, This represents the overall heat storage coefficient at the current time n. This represents the overall heat storage coefficient at time nk.

[0028] Optionally, determining the target steam temperature at the inlet of the superheater heating surface based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient includes:

[0029] The combined heat storage coefficient and its rate of change are input into the steam temperature prediction model to obtain the target steam temperature at the inlet of the superheater heating surface.

[0030] This application also provides a steam temperature control device, including:

[0031] The acquisition unit is used to acquire basic data of the superheater's heating surface.

[0032] The first calculation unit is used to calculate the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the basic data.

[0033] A determining unit is used to determine the target steam temperature at the inlet of the superheater heating surface based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient.

[0034] The second calculation unit is used to calculate the desuperheating water volume based on the target steam temperature and the current steam temperature at the inlet of the superheater heating surface.

[0035] The control unit is used to control the desuperheater to release desuperheating water based on the amount of desuperheating water, so as to adjust the current steam temperature to the target steam temperature.

[0036] Optionally, the first computing unit is specifically used for:

[0037] Calculate the steam heat storage coefficient and metal heat storage coefficient of the superheater heating surface based on the aforementioned basic data;

[0038] The comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient are calculated based on the steam working fluid heat storage coefficient and the metal heat storage coefficient of the superheater heating surface.

[0039] Optionally, the determining unit is specifically used for:

[0040] The combined heat storage coefficient and its rate of change are input into the steam temperature prediction model to obtain the target steam temperature at the inlet of the superheater heating surface.

[0041] This application also provides a computer device, characterized in that it includes: a memory, a processor, and a bus system;

[0042] The memory is used to store programs;

[0043] The processor is used to execute the program in the memory to implement any of the steam temperature control methods described above;

[0044] The bus system is used to connect the memory and the processor to enable communication between the memory and the processor.

[0045] This application also provides a computer-readable storage medium, characterized in that it stores instructions that, when run on a computer, cause the computer to execute any of the steam methods described above.

[0046] This application provides a steam temperature control method, comprising: acquiring basic data of the superheater heating surface; calculating the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface based on the basic data; determining the target steam temperature at the inlet of the superheater heating surface based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient; calculating the desuperheating water volume based on the target steam temperature and the current steam temperature at the inlet of the superheater heating surface; and controlling the desuperheater to release desuperheating water based on the desuperheating water volume, so as to adjust the current steam temperature to the target steam temperature. It is evident that this application, by calculating the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface, enables the target steam temperature determined based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface to comprehensively consider the condition of the superheater heating surface. This effectively overcomes the problems of large adjustment delay and large differences in the object characteristics of the superheater under different loads and combustion conditions existing in the prior art, thereby enabling more accurate control of the steam temperature and improving the accuracy of steam temperature control. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0048] Figure 1 A schematic diagram of a conventional desuperheating water control method provided in an embodiment of this application;

[0049] Figure 2 A schematic flowchart of a steam temperature control method provided in an embodiment of this application;

[0050] Figure 3 This is a schematic diagram of a steam temperature control device provided in an embodiment of this application. Detailed Implementation

[0051] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0053] Steam temperature is a crucial parameter for the safe, efficient, and economical operation of thermal power units. Therefore, the requirements for steam temperature control are quite stringent. Excessively high steam temperatures can cause damage to the superheater and high-pressure turbine cylinder due to excessive thermal stress, while excessively low steam temperatures will reduce the unit's thermal efficiency and affect economic operation. The main and reheat steam temperature control methods for coal-fired boilers primarily include desuperheating water and flue gas dampers, with desuperheating water being the primary method. Water spray desuperheating involves directly injecting water into the superheated steam; the water absorbs heat from the steam, thus reducing the steam temperature.

[0054] Please see Figure 1 Traditional desuperheating water control methods widely employ a cascade PID control strategy, with main steam temperature as the primary regulator, desuperheating water outlet temperature as the secondary regulator, and unit load as the feedforward. This strategy controls the steam temperature after the desuperheater (also known as the "lead temperature") by controlling the desuperheating water flow rate, and then controls the steam temperature after the superheater heating surface by controlling the lead temperature setpoint. The main regulating loop's parameter is the superheated steam temperature after the superheater heating surface, while the secondary regulating loop's parameter is the steam temperature after desuperheating via water spray. Structurally, the cascade control forms two closed loops. The inner loop performs "fine-tuning," adjusting the lead temperature to the lead temperature setpoint by regulating the desuperheating water flow rate. The outer loop performs "coarse-tuning," adjusting the steam temperature to the steam temperature setpoint by regulating the lead temperature setpoint. However, this control method faces challenges such as large delays, numerous disturbances, and nonlinearity in steam temperature control systems. The common approach is to add feedforward control to the outer loop of the cascade control strategy. Variables that can be used for feedforward control include pre-cooling steam temperature, unit load, heat exchanger metal tube wall temperature, total air volume, total coal volume, and flue gas temperature. However, the effects of these feedforward variables on the control system are difficult to quantify. Coupled with the influence of nonlinearity of the controlled object and inaccurate measurement points, the debugging is very difficult, the control effect is poor, and the accuracy of steam temperature control is low, making it impossible to achieve accurate control of steam temperature.

[0055] Therefore, to address the above-mentioned problems, this application provides a steam temperature control method, apparatus, device, and readable storage medium, which can control the steam temperature more accurately and improve the accuracy of steam temperature control.

[0056] Please see Figure 2 The security authentication method provided in this application includes the following steps.

[0057] S201. Obtain basic data of the superheater heating surface.

[0058] In this embodiment, basic data of the superheater heating surface can be obtained first. It is understood that the basic data of the superheater heating surface may include the inlet steam specific heat capacity, outlet steam specific heat capacity, steam flow rate within the superheater heating surface, inlet steam temperature, outlet steam temperature, steam flow rate, length of a single tube in the superheater heating surface, steam velocity within the superheater heating surface, and the metal specific heat capacity of the superheater heating surface. The superheater heating surface refers to the superheater heating surface arranged after the desuperheater according to the steam-water flow path. For a first-stage desuperheater, it refers to a screen-type superheater; for a second-stage desuperheater, it refers to a high-temperature superheater.

[0059] Specifically, the power plant's DCS system can first obtain data such as the current desuperheating water volume of the boiler, the current steam temperature after desuperheating by the desuperheater, the current outlet steam temperature of the superheater heating surface, the boiler feedwater mass flow rate, steam pressure, and tube wall temperature. Then, based on this data, the basic data of the superheater heating surface can be further calculated.

[0060] S202. Calculate the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the basic data.

[0061] In this embodiment, after obtaining the basic data of the superheater heating surface, the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient can be calculated based on this data. It can be understood that the comprehensive heat storage coefficient of the superheater heating surface characterizes the inertia of the steam in the superheater. When the comprehensive heat storage coefficient increases, it indicates that the inertia of the steam in the superheater increases; when the comprehensive heat storage coefficient decreases, it indicates that the inertia of the steam in the superheater decreases, and the corresponding control parameters also need to be adjusted. The rate of change of the comprehensive heat storage coefficient characterizes the rate of steam reaction in the superheater. When the rate of change of the comprehensive heat storage coefficient increases, it indicates that the rate of steam reaction in the superheater increases; when the rate of change of the comprehensive heat storage coefficient decreases, it indicates that the rate of steam reaction in the superheater decreases, and the corresponding adjustment parameters also need to be adjusted.

[0062] In one possible implementation, the steam heat storage coefficient and the metal heat storage coefficient of the superheater heating surface can be calculated based on the basic data of the superheater heating surface; the overall heat storage coefficient and the rate of change of the overall heat storage coefficient of the superheater can then be calculated based on the steam heat storage coefficient and the metal heat storage coefficient of the superheater heating surface. It is understood that the steam heat storage coefficient of the superheater heating surface reflects the steam flow rate through the superheater heating surface, while the metal heat storage coefficient reflects the material of the metal surface in the superheater and its heating conditions.

[0063] Specifically, the heat storage coefficient of the steam working fluid of the superheater is calculated based on the basic data of the superheater heating surface. This can be:

[0064]

[0065] Among them, C pin C represents the specific heat capacity of the inlet steam at the superheater's heating surface. The specific heat capacity of superheated steam depends only on pressure and temperature, and its unit is kJ / kg·K. pout W is the specific heat capacity of the steam at the outlet of the superheater heating surface, expressed in kJ / kg·K. steam T represents the steam flow rate within the superheater's heating surface, expressed in kg / s. in T represents the inlet steam temperature of the superheater heating surface, expressed in °C. outt is the outlet steam temperature of the superheater heating surface, in °C; L is the length of a single tube of the superheater heating surface, in m; v is the steam velocity in the superheater heating surface, in m / s.

[0066] The metal heat storage coefficient of the superheater heating surface is calculated based on the basic data of the superheater heating surface. Specifically, it can be:

[0067] QS metal =C pmetal ·G metal ·T metal ;

[0068] Among them, C pmetal For the specific heat capacity of a metal, the high-temperature region can be approximated as a first-order linear function of time, with units of kJ / kg·K; G metal T represents the mass of a metal, measured in kg. metal The value is the tube wall temperature, calculated as the average value of the measuring points at the outlet of the heated surface, in °C.

[0069] After calculating the heat storage coefficients of the steam working fluid and the metal on the superheater heating surface, the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient are calculated based on these coefficients. Specifically:

[0070] QS syn =K1·QS steam +K2·QS metal ;

[0071] Where K1 and K2 are weighting coefficients, and K1+K2=1.

[0072] After calculating the overall heat storage coefficient of the superheater's heating surface, the rate of change of the overall heat storage coefficient can be calculated based on the overall heat storage coefficient of the superheater's heating surface, specifically:

[0073]

[0074] in, This represents the overall heat storage coefficient at the current time n. This represents the overall heat storage coefficient at time nk.

[0075] S203. Determine the target steam temperature at the inlet of the superheater heating surface based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient.

[0076] In this embodiment, after calculating the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface, the target steam temperature at the inlet of the superheater heating surface can be determined based on these two parameters. This is the temperature value that the current steam temperature at the inlet of the superheater heating surface needs to reach. It is understood that the target steam temperature determined based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface can comprehensively consider the condition of the superheater heating surface, effectively overcoming the problems of large adjustment delay and significant differences in the characteristics of the superheater under different loads and combustion conditions in the prior art. Therefore, it can control the steam temperature more accurately and improve the accuracy of steam temperature control.

[0077] In one possible implementation, the comprehensive heat storage coefficient and its rate of change can be input into the steam temperature prediction model to obtain the target steam temperature at the superheater inlet, as output by the model. It is understood that the steam temperature prediction model can be pre-trained based on a neural network model, historical comprehensive heat storage coefficients, and historical target steam temperatures at the superheater inlet; alternatively, an existing prediction model from the control system can be used as the steam temperature prediction model.

[0078] S204. Calculate the desuperheating water volume based on the target steam temperature and the current steam temperature at the inlet of the superheater heating surface.

[0079] In this embodiment, after determining the target steam temperature at the inlet of the superheater heating surface, the desuperheating water volume can be calculated based on the target steam temperature and the current steam temperature at the inlet of the superheater heating surface. Specifically, the difference between the target steam temperature and the current steam temperature can be calculated first, and then the desuperheating water volume required to adjust the current steam temperature to the target steam temperature can be calculated based on the correspondence between the difference and the desuperheating water volume. It can be understood that the current steam temperature can be the steam temperature before it passes through the superheater at the current moment, i.e., the actual value of the inlet temperature at the current moment; the target steam temperature can be the temperature that the current steam temperature needs to be adjusted to, i.e., the inlet temperature setpoint.

[0080] S205. Based on the desuperheating water volume control, the desuperheater releases desuperheating water to adjust the current steam temperature to the target steam temperature.

[0081] In this embodiment, after determining the desuperheating water volume, the desuperheater can be controlled to release desuperheating water based on the volume, thereby adjusting the current steam temperature to the target steam temperature. It is understood that the amount of desuperheating water released by the desuperheater can be controlled to reach the target volume, so that the current steam temperature at the inlet of the superheater's heating surface can be adjusted to the target steam temperature by the action of the desuperheating water. The desuperheater can be a multi-hole nozzle type, with many small holes on the nozzle. The desuperheating water is sprayed out of the small holes and atomized, mixing with the steam flowing in the same direction to achieve the purpose of reducing the steam temperature.

[0082] Therefore, this application provides a steam temperature control method, including: acquiring basic data of the superheater heating surface; calculating the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface based on the basic data; determining the target steam temperature at the inlet of the superheater heating surface based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient; calculating the desuperheating water volume based on the target steam temperature and the current steam temperature at the inlet of the superheater heating surface; and controlling the desuperheater to release desuperheating water based on the desuperheating water volume, so that the current steam temperature is adjusted to the target steam temperature. It is evident that this application, by calculating the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface, allows the target steam temperature determined based on these coefficients to comprehensively consider the condition of the superheater heating surface. This effectively overcomes the problems of large adjustment delays and significant differences in the characteristics of the superheater under different loads and combustion conditions in the prior art, thereby enabling more accurate steam temperature control and improving the accuracy of steam temperature control.

[0083] The following analysis will be conducted in specific scenarios:

[0084] The boiler is a 350MW supercritical boiler. The boiler steam temperature regulation uses a two-stage desuperheating water system; the two-stage desuperheating water system will be used as an example. The two-stage desuperheating water system is located before the high-temperature superheater (referred to as "high-temperature superheater"). Steam enters the high-temperature superheater outlet header after being heated through a serpentine tube system from the inlet header. The serpentine tube screen of the high-temperature superheater is located above the flame deflector, with 31 sections arranged along the width of the furnace. Each section consists of 20 tubes wound in parallel. The outermost tubes at the inlet and outlet ends are Φ50.8×9 (outer diameter × wall thickness), made of SA-213TP347H material. The remaining tubes are Φ45×8.5, made of SA-213T91 material. SA-213TP347H and SA-213T91 stainless steel seamless pipes are mainly used to manufacture components such as high-temperature superheaters, high-temperature reheaters, the high-temperature sections of screen-type superheaters, and various high-pressure fittings. According to the boiler drawings, the average length of a single tube in the high-temperature superheater serpentine tube is approximately 26.8m. Historical data at 1m intervals are shown in Table 1 below.

[0085] Table 1. Partial Historical Basic Data of the Boiler

[0086]

[0087]

[0088] 1) Calculation of the heat storage coefficient of the steam working fluid on the heating surface

[0089] Formula for calculating the heat storage coefficient of steam working fluid above the heating surface:

[0090]

[0091] The specific heat capacity of the outlet steam at constant pressure, C pout C is related to the pressure and temperature of the steam. pout =f(T) out P out (), higher than the outlet steam pressure P out It is 19.283 MPa, which is higher than the outlet steam temperature T. out =573.094℃. Based on the calculation formula IAPWS-IF97 for the physical properties of water and water vapor, the specific heat capacity C above the outlet isobaric pressure is obtained. pout = 2.83 kJ / kg·K.

[0092] The specific heat capacity of the inlet steam at constant pressure, C pin The temperature is related to the steam pressure and temperature, but there is no corresponding measuring point for the inlet steam temperature. It can be estimated based on the boiler thermal calculation sheet, according to the feedwater flow rate W and the high pressure drop ΔP. gg Based on the design values, data fitting is performed to obtain the corresponding functional relationship, as shown in the following formula:

[0093] ΔP gg =1.03×10 -7 W 2 +3.466×10 -5 W-0.003796;

[0094] When the feedwater flow rate is 914.355 t / h, the pressure drop above the heating surface is 0.114 MPa, and the pressure above the inlet steam pressure P is... in The pressure is 19.283 + 0.114 = 19.397 MPa, which is higher than the inlet steam temperature. This is the steam temperature after the right-side secondary desuperheater. The measured value is T. in =492.448℃. Based on the calculation formula IAPWS-IF97 for the physical properties of water and water vapor, the specific heat capacity C above the inlet isobaric pressure is obtained. pin = 3.3 kJ / kg·K.

[0095] Steam flow rate W above the heating surface steam Water supply flow rate W gs Primary cooling water volume Wjw1 Secondary cooling water volume W jw2 The composition, and its calculation formula are as follows:

[0096] W steam =W gs +W jw1 +W jw2 ;

[0097] The measured feedwater flow rate was 914.355 t / h, the first-stage desuperheating water flow rate was 29.957 + 39.206 = 69.163 t / h, the second-stage desuperheating water flow rate was 9.936 + 0.839 = 10.775 t / h, and the superheated steam flow rate was W. steam =914.355+69.163+10.775=994.273t / h.

[0098] The calculation for the area exceeding the total flow cross-sectional area is as follows:

[0099]

[0100] Where D is the inner diameter of the pipe, calculated as Φ45×8.5, the inner diameter D=0.028m, the number of parallel pipes exceeding the single screen n1=20, and the number of pipe rows exceeding the screen n2=31. The calculated total cross-sectional area exceeding the screen is 0.38m2.

[0101] The formula for calculating the average flow velocity v of the medium inside the pipe is as follows:

[0102]

[0103] Where ρ ave The average density of steam is calculated using the formula IAPWS-IF97, which calculates the steam density based on the steam temperature and pressure above the average inlet and outlet temperatures, and according to the physical property parameters of water and steam. The calculated ρ... ave =60.16kg / m3, which is higher than the flow velocity of the medium inside the pipe v=12m / s.

[0104] Therefore, the heat storage coefficient of the steam working fluid above the heating surface can be obtained as QS. steam =1.007×10 6 .

[0105] 2) Calculation of heat storage in the heated surface metal

[0106] Specific heat capacity C of metal pmetal In the high-temperature region, the variation is relatively small, and it can be approximated as a linear relationship with temperature, using the following fitting formula:

[0107] C pmetal =0.43+0.00031357T metal ;

[0108] Where Tmetal This is the temperature above the average outlet pipe wall temperature, expressed in °C. The measured value is 573.8 °C.

[0109] The calculated specific heat capacity of the metal at constant pressure, C pmetal = 0.61 kJ / kg·K.

[0110] The mass of the metal above the heated surface is calculated as follows:

[0111]

[0112] Wherein, the metal density ρ metal Take 7.9 × 10 3 The single tube length L of the serpentine tube in the high-temperature superheater is 26.8m, De is the outer diameter of the tube, taken as 0.045m, and the inner diameter D is taken as 0.028m. The calculated metal mass G metal It weighs 127,877.75 kg.

[0113] The formula for calculating the heat storage coefficient of the heated surface metal is as follows:

[0114] QS metal =C pmetal ·G metal ·T metal ;

[0115] The calculated heat storage coefficient of the heated surface metal is QS metal =44.7×10 6 .

[0116] 3) Calculation of comprehensive heat storage coefficient and rate of change

[0117] The formula for calculating the overall heat storage coefficient of the heated surface is as follows:

[0118] QS syn =(K1·QS) steam +K2·QS metal ) / 10 7 ;

[0119] Where K1 and K2 are weighting coefficients, and K1+K2=1, take K1=0.93.

[0120] The obtained comprehensive heat storage coefficient is processed by first-order hysteresis filtering, and the basic formula is as follows:

[0121] Y(n)=α·X(n)+(1-α)·Y(n-1);

[0122] Where α is the filter coefficient, with a value range of 0-1, Y(n) is the current filtering result, X(n) is the current sample value, and Y(n-1) is the previous filtering result.

[0123] The formula for calculating the rate of change of the overall heat storage coefficient of the heated surface is as follows:

[0124]

[0125] in, This represents the overall heat storage coefficient at the current time n; This represents the overall heat storage coefficient at time nk.

[0126] 4) Combine the overall heat storage coefficient of the heating surface with the desuperheating water cascade control strategy.

[0127] Model predictive control (MMC) is an advanced control algorithm developed for industrial applications, characterized by predictive control, rolling optimization, and feedback correction. When using Dynamic Matrix Control (DMC), the main tuning parameters for the MMC include: modeling time domain N, optimization time domain P, control time domain M, error weight Q, increment weight R, and correction coefficient h. The modeling time domain N affects the length of the model involved in the calculation, typically needing to include most of the transfer function information. To avoid excessive computation, a suitable sampling period is usually used. The optimization time domain P affects the controller's prediction duration. The control time domain M represents the number of control increments; a smaller M results in poorer control performance, while a larger M increases computational complexity and reduces stability and robustness. The error weight Q suppresses prediction errors; a larger error weight improves the control system's speed but decreases stability. The increment weight R suppresses changes in the control quantity; a larger increment weight improves stability but decreases sensitivity. The correction coefficient h corrects for deviations between predicted and actual values; a larger h results in stronger correction but reduces robustness.

[0128] The comprehensive heat storage coefficient, calculated using the current boiler operating parameters, characterizes the inertia of the desuperheating water control object. An increase in the comprehensive heat storage coefficient indicates increased inertia, while a decrease indicates decreased inertia, necessitating adjustments to the corresponding control parameters. For model predictive controllers, an increase in the comprehensive heat storage coefficient can increase the delay time of the "preheater temperature setpoint - heat exchanger outlet steam temperature" model, thus decreasing its model gain; conversely, a decrease in the comprehensive heat storage coefficient can decrease the model delay time, increasing the model gain. For PID controllers, the integral parameter I of the "preheater temperature setpoint - heat exchanger outlet steam temperature" loop can be adjusted. Specific parameter changes require on-site testing and determination.

[0129] Compared with existing technologies, the advantages of this application are:

[0130] 1. By characterizing the inertia of the controlled object through the comprehensive heat storage coefficient, the adaptability of the unit under different loads is improved. The inertia of the controlled object is different under high load and low load, corresponding to different adjustment parameters;

[0131] 2. Improved the ability of the desuperheating water regulation system to cope with disturbances. Due to the very complex combustion mechanism of the boiler and the numerous factors affecting the steam temperature, the instantaneous changes of the controlled object are characterized by the magnitude of the change rate of the comprehensive heat storage coefficient. By changing the commissioning parameters, the commissioning parameters of steady-state load and dynamic load are distinguished to cope with the influence of unpredictable disturbances.

[0132] Please see Figure 3 This application also provides a steam temperature control device, including:

[0133] Acquisition unit 301 is used to acquire basic data of the superheater heating surface;

[0134] The first calculation unit 302 is used to calculate the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the basic data.

[0135] Determining unit 303 is used to determine the target steam temperature based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient;

[0136] The second calculation unit 304 is used to calculate the amount of desuperheating water based on the target steam temperature and the current steam temperature.

[0137] Control unit 305 is used to control the desuperheater to release desuperheating water based on the amount of desuperheating water, so as to adjust the current steam temperature to the target steam temperature.

[0138] Optionally, the first computing unit 302 is specifically used for:

[0139] Calculate the steam heat storage coefficient and metal heat storage coefficient of the superheater heating surface based on the aforementioned basic data;

[0140] The comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient are calculated based on the steam working fluid heat storage coefficient and the metal heat storage coefficient of the superheater heating surface.

[0141] Optionally, unit 303 is specifically used for:

[0142] The target steam temperature is obtained by inputting the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient into the steam temperature prediction model.

[0143] Optionally, the first computing unit 302 is specifically used for:

[0144] The heat storage coefficient of the steam working fluid on the superheater heating surface is calculated based on the aforementioned basic data, specifically as follows:

[0145]

[0146] Among them, C pinC is the specific heat capacity of the inlet steam of the superheater heating surface; pout W is the specific heat capacity of the steam at the outlet of the superheater heating surface. steam T is the steam flow rate within the superheater's heating surface. in T is the inlet steam temperature of the superheater heating surface; out is the outlet steam temperature of the superheater heating surface; L is the length of a single tube of the superheater heating surface; v is the steam velocity in the superheater heating surface.

[0147] The metal heat storage coefficient of the superheater's heating surface is calculated based on the aforementioned basic data, specifically as follows:

[0148] QS metal =C pmetal ·G metal ·T metal ;

[0149] Among them, C pmetal G represents the specific heat capacity of the metal. metal For metallic mass; T metal This refers to the pipe wall temperature.

[0150] Optionally, the first computing unit 303 is specifically used for:

[0151] The comprehensive heat storage coefficient of the superheater heating surface is calculated based on the steam working fluid heat storage coefficient and the metal heat storage coefficient, specifically as follows:

[0152] QS syn =K1·QS steam +K2·QS metal ;

[0153] Where K1 and K2 are weighting coefficients, and K1+K2=1;

[0154] The rate of change of the comprehensive heat storage coefficient is calculated based on the comprehensive heat storage coefficient of the superheater's heating surface, specifically as follows:

[0155]

[0156] in, This represents the overall heat storage coefficient at the current time n. This represents the overall heat storage coefficient at time nk.

[0157] Therefore, the present application provides a steam temperature control device that can calculate the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface. This allows the target steam temperature determined based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient of the superheater heating surface to comprehensively consider the condition of the superheater heating surface. This effectively overcomes the problems of large adjustment delay and large differences in the object characteristics of the superheater under different loads and different combustion conditions in the prior art, thereby enabling more accurate control of the steam temperature and improving the accuracy of steam temperature control.

[0158] This application also provides a computer device, including: a memory, a processor, and a bus system;

[0159] The memory is used to store programs;

[0160] The processor is used to execute the program in the memory to implement any of the steam temperature control methods described above;

[0161] The bus system is used to connect the memory and the processor to enable communication between the memory and the processor.

[0162] This application also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform any of the steam temperature control methods described above.

[0163] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0164] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A steam temperature control method, characterized in that, include: Obtain basic data of the superheater's heating surface; Calculate the steam heat storage coefficient and metal heat storage coefficient of the superheater heating surface based on the aforementioned basic data; Calculate the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the steam working fluid heat storage coefficient and the metal heat storage coefficient of the superheater heating surface; The target steam temperature at the inlet of the superheater heating surface is determined based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient. The desuperheating water volume is calculated based on the target steam temperature and the current steam temperature at the inlet of the superheater heating surface. Based on the desuperheating water volume control, the desuperheater releases desuperheating water to adjust the current steam temperature to the target steam temperature; The heat storage coefficient of the steam working fluid is calculated according to the following formula: In the formula, The specific heat capacity of the inlet steam of the superheater heating surface; The specific heat capacity of the steam at the outlet of the superheater heating surface; This refers to the steam flow rate within the superheater's heating surface. The inlet steam temperature of the superheater heating surface; is the outlet steam temperature of the superheater heating surface; L is the length of a single tube of the superheater heating surface; v is the steam velocity in the superheater heating surface. The heat storage coefficient of the metal is calculated according to the following formula: In the formula, Specific heat capacity of the metal; Metal quality; This refers to the pipe wall temperature; The overall heat storage coefficient is calculated according to the following formula: In the formula, and These are the weighting coefficients, and ; The rate of change of the comprehensive heat storage coefficient is calculated according to the following formula: In the formula, This represents the overall heat storage coefficient at the current time n. This represents the overall heat storage coefficient at time nk.

2. The method according to claim 1, characterized in that, Determining the target steam temperature at the inlet of the superheater heating surface based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient includes: The combined heat storage coefficient and its rate of change are input into the steam temperature prediction model to obtain the target steam temperature at the inlet of the superheater heating surface.

3. A steam temperature control device, characterized in that, include: The acquisition unit is used to acquire basic data of the superheater's heating surface. The first calculation unit is used to calculate the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the basic data. The first computing unit is specifically used for: Calculate the steam heat storage coefficient and metal heat storage coefficient of the superheater heating surface based on the aforementioned basic data; Calculate the comprehensive heat storage coefficient of the superheater heating surface and the rate of change of the comprehensive heat storage coefficient based on the steam working fluid heat storage coefficient and the metal heat storage coefficient of the superheater heating surface; A determining unit is used to determine the target steam temperature at the inlet of the superheater heating surface based on the comprehensive heat storage coefficient and the rate of change of the comprehensive heat storage coefficient. The second calculation unit is used to calculate the desuperheating water volume based on the target steam temperature and the current steam temperature at the inlet of the superheater heating surface. A control unit is configured to control the desuperheater to release desuperheating water based on the desuperheating water volume, so as to adjust the current steam temperature to the target steam temperature. Specifically, the first computing unit is used for: According to the formula Calculate the heat storage coefficient of the steam working fluid, where, The specific heat capacity of the inlet steam of the superheater heating surface; The specific heat capacity of the steam at the outlet of the superheater heating surface; This refers to the steam flow rate within the superheater's heating surface. The inlet steam temperature of the superheater heating surface; is the outlet steam temperature of the superheater heating surface; L is the length of a single tube of the superheater heating surface; v is the steam velocity in the superheater heating surface. According to the formula Calculate the heat storage coefficient of the metal, where, Specific heat capacity of the metal; Metal quality; This refers to the pipe wall temperature; According to the formula Calculate the comprehensive heat storage coefficient, where, and These are the weighting coefficients, and ; According to the formula Calculate the rate of change of the comprehensive heat storage coefficient, where, This represents the overall heat storage coefficient at the current time n. This represents the overall heat storage coefficient at time nk.

4. The apparatus according to claim 3, characterized in that, The determining unit is specifically used for: The combined heat storage coefficient and its rate of change are input into the steam temperature prediction model to obtain the target steam temperature at the inlet of the superheater heating surface.

5. A computer device, characterized in that, include: Memory, processor, and bus system; The memory is used to store programs; The processor is used to execute the program in the memory to implement the method of claim 1; The bus system is used to connect the memory and the processor to enable communication between the memory and the processor.

6. A computer-readable storage medium, characterized in that, The device stores instructions that, when run on a computer, cause the computer to perform the method as described in claim 1.

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