Approximate calculation method for influence of once-through boiler fuel quantity disturbance on steam temperature quantification and related device

Abstract

The invention belongs to the technical field of thermal equipment performance state monitoring and diagnosis, and discloses an approximate calculation method for influence of once-through boiler fuel quantity disturbance on steam temperature quantification and a related device. The approximate calculation method for the influence of fuel quantity disturbance of the once-through boiler on steam temperature quantification comprises the steps that differential processing is carried out on a heat balance equation, the influence of fuel quantity change on a main steam working medium enthalpy value is deduced, and then a reduced temperature empirical equation of the main steam working medium temperature and a steam turbine critical working condition flow approximate calculation equation are combined; the specific influence of the fuel quantity change on the main steam working medium temperature is calculated, and finally, a calculation model is further obtained and optimized by correcting the boiler heat efficiency variable quantity; the method can overcome the defect that the temperature of the main steam working medium of the boiler cannot be conveniently and accurately calculated and quantitatively analyzed according to the fuel quantity change, the calculation steps are greatly simplified, the operation efficiency of the boiler is optimized, and the power generation coal consumption rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of performance state monitoring and diagnosis of thermal equipment, and particularly relates to an approximate calculation method for quantitatively influencing the steam temperature by fuel quantity disturbance of a once-through boiler and a related device. Background Art

[0002] It is very difficult for the operating units and thermal systems to work completely under the designed conditions, because it is very difficult for the operating systems, equipment, loads and various parameters to be all in the designed states. In this sense, off-design conditions are the main operating conditions. Therefore, it has become a very necessary and important topic to study the states of units and systems under off-design conditions and their safety and economy under off-design conditions.

[0003] Performing off-design calculations on the thermal system is the basic method to understand off-design conditions and an important means to explore the safety and economy of the thermal system. Without exaggeration, in-depth analysis and research on the economy of any unit thermal system cannot do without off-design calculations. The main steam pressure and temperature of the boiler are important technical parameters that are key monitored in coal-fired units. Usually, as the boiler combustion rate increases, the main steam temperature of the coal-fired unit changes, which also affects the boiler thermal efficiency and the turbine heat consumption rate, and further affects the power generation coal consumption rate and the power supply coal consumption rate of the unit.

[0004] The existing methods for analyzing the influence of fuel quantity change on the main steam temperature of the boiler mainly rely on the off-design thermal calculation method of the boiler unit. Usually, the off-design calculation of the boiler is to perform detailed thermal calculations for each heating surface one by one. However, the calculation often requires hundreds of complex formulas and numerous heating surface structure parameters. It can be seen that the calculation is very complicated and requires a large amount of original data. Although using computerized calculation will make this calculation more convenient, it is still heavy compared with the tasks of thermal system calculation. Sometimes, due to insufficient original data, the calculation cannot be carried out, resulting in the actual situation that often requires the operating personnel to analyze the influence of the combustion rate change of the unit on the main steam temperature without effectively obtaining the detailed structure data of the boiler heating surface. At this time, it is necessary to construct an approximate calculation model for quantitatively influencing the main steam temperature of the boiler by fuel quantity change with relatively high accuracy. Summary of the Invention

[0005] The object of the present invention is to provide an approximate calculation method and related device for the quantitative influence of fuel quantity disturbance on steam temperature in a once-through boiler, so as to overcome the problems existing in the prior art. The present invention establishes an approximate calculation model for the quantitative influence of boiler fuel quantity disturbance on the main steam working medium temperature of the boiler. Under the condition of variable operating conditions of the boiler unit, it is only necessary to accurately analyze and calculate the quantitative influence of the change in boiler fuel quantity on the main steam working medium temperature of the boiler according to the parameters in the reference operating condition data; the present invention provides a precise method for more static and dynamic analysis of the influence of the change in boiler fuel quantity on the main steam working medium temperature of the boiler and the control of the main steam working medium temperature of the once-through boiler, so as to make up for the defect of a large amount of structural data required in the existing method for calculation.

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

[0007] In the first aspect, the present invention provides an approximate calculation method for the quantitative influence of fuel quantity disturbance on steam temperature in a once-through boiler, including the following steps:

[0008] According to the boiler heat balance equation and combining differential theory, a function expression between the enthalpy value of the main steam working medium, the boiler fuel quantity and the boiler thermal efficiency is obtained. Then, by differentiating the enthalpy value of the main steam working medium, a function expression between the change in the main steam working medium temperature and the change in the enthalpy value is obtained;

[0009] According to the approximate calculation equation of the critical condition flow rate of the steam turbine and the empirical equation of the reduced temperature of the main steam working medium, a function expression between the main steam working medium pressure and the main steam working medium temperature is obtained. Combining the function expression between the main steam working medium pressure and the main steam working medium temperature, the function expression between the enthalpy value of the main steam working medium, the boiler fuel quantity and the boiler thermal efficiency obtained above, and the function expression between the change in the main steam working medium temperature and the change in the enthalpy value, a function expression between the main steam working medium temperature, the change in the boiler fuel quantity and the change in the boiler thermal efficiency is obtained;

[0010] Establish a relationship equation between the furnace outlet flue gas temperature and the boiler fuel quantity and perform differentiation. The relationship equation between the differentiated furnace outlet flue gas temperature and the boiler fuel quantity is obtained as the expression of the change in the boiler flue gas exhaust temperature through a correction method. Then, according to the expression of the change in the boiler thermal efficiency, the function expression between the main steam working medium temperature, the change in the boiler fuel quantity and the change in the boiler thermal efficiency obtained above, the relationship equation between the differentiated furnace outlet flue gas temperature and the boiler fuel quantity, and the expression of the change in the boiler flue gas exhaust temperature, an approximate calculation model for the quantitative influence of boiler fuel quantity disturbance on steam temperature is obtained, and the change in the main steam working medium temperature Δθ′ is obtained through the approximate calculation model for the quantitative influence of boiler fuel quantity disturbance on steam temperature T ;

[0011] Further, the specific functional expression between the enthalpy value of the main steam working medium, the boiler fuel quantity, and the boiler thermal efficiency is as follows:

[0012]

[0013] In the formula, h′ T is the enthalpy value of the main steam working medium, with the unit of kJ / kg; δh ∑ is the total enthalpy increase of the working medium after passing through the boiler, with the unit of kJ / kg; B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate, with the unit of kg / s; η is the boiler efficiency, with the unit of %.

[0014] Further, the specific functional expression between the temperature change amount of the main steam working medium and the enthalpy change amount is as follows:

[0015]

[0016] In the formula, θ′ T is the temperature of the main steam working medium, with the unit of °C; h′ T is the enthalpy value of the main steam working medium, with the unit of kJ / kg; c P is the isobaric specific heat of the working medium, with the unit of kJ / (kg·°C); k θ is a non-constant coefficient, p′ T is the pressure of the main steam working medium, with the unit of MPa;

[0017] Further, the approximate calculation equation for the critical condition flow rate of the steam turbine is specifically as follows:

[0018]

[0019] The empirical equation for the reduced temperature of the main steam working medium is specifically as follows:

[0020]

[0021] The functional expression between the pressure of the main steam working medium and the temperature of the main steam working medium is specifically as follows:

[0022]

[0023] In the formula, D is the steam flow rate, with the unit of kg / s; K is the flow coefficient; p′ T is the pressure of the main steam working medium, with the unit of MPa; is the reduced temperature of the main steam working medium, with the unit of °C; θ′ T is the temperature of the main steam working medium, with the unit of °C; Footnote 0 represents the parameters at the original steady state;

[0024] Furthermore, the functional expression of the main steam working medium temperature with respect to the change in boiler fuel quantity and the change in boiler thermal efficiency is specifically:

[0025]

[0026] In the formula, θ′ T is the main steam working medium temperature, with the unit of °C; δh ∑ is the total enthalpy increase of the working medium after passing through the boiler, with the unit of kJ / kg; c P is the isobaric specific heat of the working medium, with the unit of kJ / (kg·°C); B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate, with the unit of kg / s; η is the boiler efficiency, with the unit of %;

[0027] Furthermore, the relationship equation between the differentiated furnace outlet flue gas temperature and the boiler fuel quantity is specifically:

[0028]

[0029] In the formula, T1′ t is the flue gas temperature at the furnace outlet, with the unit of °C; T a is the theoretical combustion temperature, with the unit of °C; the subscript 0 represents the reference condition or the condition before the change in fuel quantity; B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate, with the unit of kg / s;

[0030] Furthermore, the expression for the change in the boiler's flue gas temperature is specifically:

[0031]

[0032] In the formula, θ py is the boiler's flue gas temperature, with the unit of °C; ζ is a correction factor less than 1; T1′ t is the flue gas temperature at the furnace outlet, with the unit of °C;

[0033] Furthermore, the approximate calculation model for the quantitative influence of the boiler fuel quantity disturbance on the steam temperature is specifically:

[0034]

[0035] In the formula, θ′ T is the main steam working medium temperature, with the unit of °C; δh ∑ is the total enthalpy increase of the working medium after passing through the boiler, with the unit of kJ / kg; c P is the isobaric specific heat of the working medium, with the unit of kJ / (kg·°C); T a is the theoretical combustion temperature, with the unit of °C; T1′ tis the flue gas temperature at the furnace outlet, in °C; ζ is a correction factor less than 1; q2 is the heat loss due to boiler flue gas exhaust, in %; θ py is the flue gas exhaust temperature of the boiler, in °C; t0 is the ambient temperature, in °C; η is the boiler efficiency, in %; the subscript 0 represents the reference condition or the condition before the fuel flow rate changes; B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate, in kg / s.

[0036] In a second aspect, the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above approximate calculation method for the quantitative impact of fuel quantity disturbance on steam temperature in a once-through boiler are implemented;

[0037] In a third aspect, the present invention also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the steps of the above approximate calculation method for the quantitative impact of fuel quantity disturbance on steam temperature in a once-through boiler are implemented.

[0038] The above technical solutions have the following advantages or beneficial effects:

[0039] In a first aspect, the present invention provides an approximate calculation method for the quantitative impact of fuel quantity disturbance on steam temperature in a once-through boiler. By determining the heat balance relationship at the static state of the boiler, differentiating the heat balance equation, and deriving the impact of fuel quantity change on the enthalpy value of the main steam working medium, and then combining the reduced temperature empirical equation of the main steam working medium temperature and the approximate calculation equation of the critical condition flow rate of the steam turbine, the specific impact of fuel quantity change on the main steam working medium temperature is calculated. Finally, by correcting the change in boiler thermal efficiency, the calculation model is further obtained and optimized. Only based on the parameters in the reference condition operation data, it is possible to accurately analyze and calculate the quantitative impact of boiler fuel quantity change on the main steam working medium temperature of the boiler, greatly simplifying the calculation steps, optimizing the boiler operation efficiency, reducing the power generation coal consumption rate, and making the calculation more accurate and scientific, realizing the accurate calculation and analysis of the quantitative impact of fuel quantity disturbance on steam temperature in a once-through boiler, and overcoming the defect that it is impossible to conveniently and accurately calculate and quantitatively analyze the impact of fuel quantity change on the main steam working medium temperature of the boiler; secondly, the present invention is not only applicable to units without reheating, but also applicable to units with reheating, providing theoretical guidance for boiler operation personnel and having significant economic and social benefits.

[0040] In a second aspect, the present invention also provides a computer device. By executing a specific computer program through a processor, the steps of an approximate calculation method for the quantitative influence of fuel quantity disturbance on steam temperature in a once-through boiler according to the present invention can be efficiently implemented. When the computer device executes data processing tasks, it can accurately perform numerical calculations and logical judgments, avoiding errors caused by human factors. At the same time, due to the high stability and reliability of the computer program, the accuracy and consistency of the data processing results can be ensured.

[0041] In a third aspect, the present invention also provides a computer-readable storage medium. By programming the steps of an approximate calculation method for the quantitative influence of fuel quantity disturbance on steam temperature in a once-through boiler according to the present invention into a computer program and storing it on the computer-readable storage medium, users can easily load these programs onto any compatible computer device and execute them without having to rewrite or convert the code, greatly improving the convenience and flexibility of program execution. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic flow chart of an approximate calculation method for the quantitative influence of fuel quantity disturbance on steam temperature in a once-through boiler according to the present invention;

[0043] Figure 2 It is a schematic diagram of the influence of fuel quantity change on main steam parameters and boiler thermal efficiency;

[0044] Figure 3 It is a schematic structural diagram of the computer device according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following further elaborates on the present invention in detail with reference to specific embodiments, which is an explanation rather than a limitation of the present invention.

[0046] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0048] Embodiment:

[0049] See Figure 1 , the present invention provides an approximate calculation method for the quantitative influence of the fuel quantity disturbance on the steam temperature of a once-through boiler, including the following steps:

[0050] Step 1: According to the boiler heat balance equation and combining with differential theory, obtain the function expression between the enthalpy value of the main steam working medium, the boiler fuel quantity and the boiler thermal efficiency. Then, by differentiating the enthalpy value of the main steam working medium, obtain the function expression between the change in the main steam working medium temperature and the change in the enthalpy value;

[0051] In the embodiment of the present invention, Step 1 is specifically as follows:

[0052] For a non-reheat unit, the heat absorption of the boiler at static state is equal to the heat carried away by the working medium, that is, the boiler heat balance equation is:

[0053] Q Σ = D(h' T - h W ) = Dδh Σ = ηqB (1);

[0054] In the formula, Q ∑ is the total heat absorption of each heating surface of the boiler, with the unit of kJ / kg; D is the steam flow rate, with the unit of kg / s; h' T is the enthalpy value of the main steam working medium, which can also be called the enthalpy value of the working medium in front of the steam turbine, approximately equal to the enthalpy value of the working medium at the boiler outlet, with the unit of kJ / kg; h w is the feed water enthalpy value, with the unit of kJ / kg; δh ∑ is the total enthalpy increase of the working medium after passing through the boiler, δh ∑ = h' T - h w, with the unit of kJ / kg; η is the boiler thermal efficiency, with the unit of %; q is the calorific value of unit mass fuel, with the unit of kJ / kg; B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate, with the unit of kg / s;

[0055] Taking the natural logarithm of Equation (1) gives:

[0056] lnD + ln(h' T -h w ) = lnη + lnq + lnB (2);

[0057] Taking the increment on both sides of Equation (2) and assuming that the calorific value q of the fuel remains unchanged, we get:

[0058]

[0059] When there is a heat disturbance, assuming that the feed water and spray water flow rates remain unchanged, the steam flow rate will ultimately remain unchanged, that is, △D = 0. Since the enthalpy value of the feed water remains unchanged, then h w = 0. Therefore, Equation (3) can be simplified to obtain the function expression between the enthalpy value of the main steam working medium, the boiler fuel quantity, and the boiler thermal efficiency as:

[0060]

[0061] Since the enthalpy value of the working medium is a function of temperature and pressure, that is, h′ T = f(θ′ T , p′ T ), taking the differential increment of the main steam enthalpy value, we obtain the change amount Δh′ T expression of the main steam working medium enthalpy value:

[0062]

[0063] In the formula: θ′ T is the temperature of the main steam working medium, which can also be called the steam temperature before the turbine governing valve, with the unit of °C; p′ T is the pressure of the main steam working medium, which can also be called the steam pressure before the turbine governing valve, with the unit of MPa; c P is the isobaric specific heat of the working medium, with the unit of kJ / (kg·°C); k θ is a non - constant coefficient,

[0064] Therefore, from Equation (5), the function expression between the change amount of the main steam working medium temperature and the change amount of the enthalpy value can be obtained, which can also be called the change amount expression of the steam working medium temperature at the boiler outlet:

[0065]

[0066] Step 2: Obtain the functional expression between the main steam working medium pressure and the main steam working medium temperature according to the approximate calculation equation of the steam turbine critical condition flow rate and the reduced temperature empirical equation of the main steam working medium temperature. Combine the functional expression between the main steam working medium pressure and the main steam working medium temperature with the functional expressions obtained above between the main steam working medium enthalpy value and the boiler fuel quantity and the boiler thermal efficiency, and between the main steam working medium temperature change amount and the enthalpy value change amount, to obtain the functional expression between the main steam working medium temperature and the boiler fuel quantity change and the boiler thermal efficiency change;

[0067] In the embodiment of the present invention, Step 2 is specifically as follows:

[0068] According to the approximate calculation equation of the steam turbine critical condition flow rate:

[0069]

[0070] In the formula, K is the flow coefficient; is the reduced temperature of the main steam working medium, which can also be called the reduced temperature of the steam before the steam turbine governing valve, with the unit of °C;

[0071] The reduced temperature empirical equation of the main steam working medium temperature, which can also be called the empirical equation of the reduced temperature of the steam before the steam turbine governing valve, can be expressed as:

[0072]

[0073] In the formula, Footnote 0 represents the parameters at the original steady state;

[0074] Take the natural logarithm of Equation (7), combine it with (8), and then take its increment to obtain:

[0075]

[0076] When the unit is operating in a steady state, the steam flow rate remains unchanged, △D = 0. After Equation (9) is sorted out, the functional expression between the main steam working medium pressure and the main steam working medium temperature is obtained:

[0077]

[0078] In the formula:

[0079] Combine Equations (4), (6) and (10) to obtain the functional expression between the main steam working medium temperature and the boiler fuel quantity change and the boiler thermal efficiency change, which can also be called the functional expression of the working medium temperature and steam pressure change at the turbine inlet or approximately at the boiler outlet under fuel quantity disturbance:

[0080]

[0081] Generally speaking, can be ignored. Therefore, Equation (11), that is, the functional expression of the main steam working medium temperature with respect to the changes in boiler fuel quantity and boiler thermal efficiency, can be approximately expressed as:

[0082]

[0083] Step 3: Establish the relationship equation between the flue gas temperature at the furnace outlet and the boiler fuel quantity and perform differentiation. The relationship equation between the flue gas temperature at the furnace outlet and the boiler fuel quantity after differentiation is obtained by a correction method to get the expression of the change in the boiler flue gas temperature. Then, according to the expression of the change in boiler thermal efficiency, the functional expression of the main steam working medium temperature with respect to the changes in boiler fuel quantity and boiler thermal efficiency obtained above, the relationship equation between the flue gas temperature at the furnace outlet and the boiler fuel quantity after differentiation, and the expression of the change in the boiler flue gas temperature, an approximate calculation model for the quantitative influence of boiler fuel quantity disturbance on steam temperature is obtained. The change in the main steam working medium temperature Δθ′ is obtained through the approximate calculation model for the quantitative influence of boiler fuel quantity disturbance on steam temperature T ;

[0084] In the embodiment of the present invention, Step 3 is specifically as follows:

[0085] When the fuel quantity changes, the flue gas temperature at the furnace outlet changes, and further causes the change in the boiler flue gas temperature. For the calculation equation of the flue gas temperature at the furnace outlet, differentiation is performed, and the relationship equation between the flue gas temperature at the furnace outlet and the boiler fuel quantity after differentiation can be obtained:

[0086]

[0087] In the formula, T1′ t is the flue gas temperature at the furnace outlet, with the unit of °C; T a is the theoretical combustion temperature, with the unit of °C; the subscript 0 represents the reference condition or the condition before the fuel quantity change;

[0088] When the fuel quantity changes, the flue gas temperature at the furnace outlet changes, and further causes the change in the boiler flue gas temperature. However, due to the "self-restoring characteristic" of convective heat transfer, the change in the flue gas temperature is less than the change in the flue gas temperature at the furnace outlet. Therefore, the influence of fuel quantity change on the boiler flue gas temperature can be calculated by multiplying the flue gas temperature at the furnace outlet by a correction coefficient; thus, the expression of the change in the boiler flue gas temperature can be expressed as:

[0089]

[0090] In the formula: θ py is the boiler flue gas temperature, with the unit of °C; ζ is a correction coefficient less than 1, which can be obtained through experiments;

[0091] When the fuel quantity changes and the change in unburned carbon is ignored, the change in the boiler thermal efficiency is mainly related to the flue gas temperature of the boiler. Therefore, the change in the boiler thermal efficiency can be expressed as:

[0092]

[0093] In the formula, q2 is the heat loss of the boiler flue gas, with the unit of %; t0 is the ambient temperature, with the unit of °C;

[0094] Combining formulas (12)-(15), an approximate calculation model for the quantitative influence of boiler fuel quantity disturbance on steam temperature can be obtained, which can also be called the calculation model for the quantitative influence of the change in boiler fuel quantity on the main steam temperature of a once-through boiler:

[0095]

[0096] Formula (16) is applicable to both units with and without reheat.

[0097] In an embodiment of the present invention, taking the 100% BMCR operating condition parameters of a certain 600MW supercritical pressure pulverized coal boiler as an example, an approximate calculation method for the quantitative influence of once-through boiler fuel quantity disturbance on steam temperature is described. The collected data of the unit operating parameters are shown in Table 1.

[0098] Table 1 Operating parameter table of the reference condition

[0099]

[0100]

[0101] The change in the main steam working medium temperature Δθ′ T is:

[0102]

[0103] See Figure 3, in an embodiment of the present invention, a computer device is provided. The computer device includes a processor and a memory. The memory is used to store a computer program, and the computer program includes program instructions. The processor is used to execute the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function. The processor described in the embodiment of the present invention can be used for the operation of the approximate calculation method for the quantitative influence of the fuel quantity disturbance of a once-through boiler on the steam temperature.

[0104] In an embodiment of the present invention, a computer-readable storage medium is provided, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in the computer device and is used to store programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and, of course, the extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, and the operating system of the terminal is stored in this storage space. And, one or more instructions suitable for being loaded and executed by the processor are also stored in this storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. One or more instructions stored in the computer-readable storage medium can be loaded and executed by the processor to implement the corresponding steps of the approximate calculation method for the quantitative influence of the fuel quantity disturbance of a once-through boiler on the steam temperature in the embodiment.

[0105] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0106] The present invention is described with reference to the flowcharts and / or block diagrams of methods and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0107] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means implement the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0108] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0109] See Figure 2 , in an embodiment of the present invention, the concept and principle of an approximate calculation method for the quantitative influence of fuel quantity disturbance on steam temperature in a once-through boiler of the present invention are explained:

[0110] When the fuel quantity of the boiler changes, the enthalpy value of the main steam working medium of the boiler changes, which in turn affects the boiler thermal efficiency. Assuming that the feed water enthalpy value remains unchanged, the change in the enthalpy value of the main steam working medium can reflect the change in the temperature of the main steam working medium;

[0111] The reduced temperature of the main steam working medium, which can also be called the reduced temperature of the steam before the steam turbine governing valve, is a function of the main steam working medium pressure and temperature of the boiler. The functional expression of the main steam working medium temperature of the boiler with respect to the changes in the boiler fuel quantity and the boiler thermal efficiency can be obtained by means of the empirical equation of the reduced temperature of the main steam working medium and the approximate calculation equation of the steam turbine critical condition flow rate;

[0112] When the boiler fuel quantity changes, the flue gas temperature at the boiler furnace outlet changes, and then the boiler exhaust gas temperature changes. The change in the boiler exhaust gas temperature can be corrected through the change in the flue gas temperature at the furnace outlet. Assuming that the unburned carbon content in the boiler remains unchanged, the change in the boiler thermal efficiency can be obtained;

[0113] The boiler thermal efficiency can also usually be expressed as a functional relationship with respect to the change in the fuel quantity. Therefore, through further calculation and arrangement, the functional expression between the main steam working medium temperature and the boiler fuel quantity can be obtained, that is, the approximate calculation model for the quantitative influence of the boiler fuel quantity disturbance on the steam temperature.

[0114] Based on the above concept, according to the characteristics that the boiler fuel quantity change causes simultaneous changes in the boiler thermal efficiency and the main steam temperature, and based on the boiler unit heat balance theory, combined with differential thinking, etc., the principle followed to implement the technical solution of the present invention can be further proposed, that is:

[0115] Through the boiler heat balance equation, combined with differential theory, the functional expression between the enthalpy value of the main steam working medium, the boiler fuel quantity, and the boiler thermal efficiency is obtained. Further, by differentiating the enthalpy value of the main steam working medium, the functional expression between the change in the main steam working medium temperature and the change in the enthalpy value is obtained;

[0116] By means of the empirical equation of the reduced temperature of the main steam working medium, the approximate calculation equation of the steam turbine critical condition flow rate, as well as the above-mentioned functional expression between the enthalpy value of the main steam working medium, the boiler fuel quantity, and the boiler thermal efficiency, and the functional expression between the change in the main steam working medium temperature and the change in the enthalpy value, the functional expression of the main steam working medium temperature with respect to the changes in the boiler fuel quantity and the boiler thermal efficiency is obtained;

[0117] By establishing the relationship equation between the flue gas temperature at the furnace outlet and the boiler fuel quantity, the calculation equation between the change in the boiler exhaust gas temperature and the boiler fuel quantity is obtained through a correction method. Combining the change in the boiler thermal efficiency expression and the functional expression of the main steam working medium temperature with respect to the changes in the boiler fuel quantity and the boiler thermal efficiency, the functional expression between the main steam working medium temperature and the boiler fuel quantity is obtained, that is, the approximate calculation model for the quantitative influence of the boiler fuel quantity disturbance on the steam temperature.

[0118] Based on the principle of thermal equilibrium and combined with differential theory, the present invention solves the problems of complex calculation and the need for a large amount of structural data in the existing methods by deriving the quantitative relationship between the change in fuel quantity and the main steam temperature, so as to provide theoretical guidance for the operators.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An approximate calculation method for the quantitative influence of fuel quantity disturbance on steam temperature of a once-through boiler, characterized in that: The following steps are involved: According to the boiler heat balance equation, combined with differential theory, the function expression between the main steam working medium enthalpy value and the boiler fuel amount and boiler thermal efficiency is obtained, and then the function expression between the main steam working medium temperature change and the enthalpy change is obtained by differentiating the main steam working medium enthalpy value; The function expression between the main steam working medium pressure and the main steam working medium temperature is obtained according to the approximate calculation equation of the critical condition flow of the steam turbine and the reduced temperature empirical equation of the main steam working medium temperature. The function expression between the main steam working medium pressure and the main steam working medium temperature and the function expression between the main steam working medium enthalpy value and the boiler fuel amount and the boiler thermal efficiency obtained above, and the function expression between the main steam working medium temperature change and the enthalpy change, are combined to obtain the function expression between the main steam working medium temperature and the boiler fuel amount change and the boiler thermal efficiency change. The relationship equation between the furnace outlet flue gas temperature and the boiler fuel amount is established and differentiated. The differentiated relationship equation between the furnace outlet flue gas temperature and the boiler fuel amount is modified to obtain the boiler flue gas temperature change expression. Then, according to the boiler thermal efficiency change expression and the above-obtained function expression of the main steam working medium temperature and the boiler fuel amount change and the boiler thermal efficiency change, the differentiated relationship equation between the furnace outlet flue gas temperature and the boiler fuel amount and the boiler flue gas temperature change expression, an approximate calculation model for the quantitative effect of the boiler fuel amount disturbance on the steam temperature is obtained. The change Δθ′ of the main steam working medium temperature is obtained through the approximate calculation model for the quantitative effect of the boiler fuel amount disturbance on the steam temperature. T .

2. The method for approximate calculation of the quantitative influence of fuel quantity disturbance on steam temperature of a once-through boiler according to claim 1 is characterized in that: The functional expression between the main steam working medium enthalpy value, the boiler fuel amount and the boiler thermal efficiency is specifically: In the formula, h′ T δh is the enthalpy of the main steam working medium; Σ is the total enthalpy increase of the working fluid after passing through the boiler; B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate; η is the boiler efficiency.

3. The method for approximate calculation of the quantitative influence of fuel quantity disturbance on steam temperature of a once-through boiler according to claim 1 is characterized in that: The functional expression between the temperature change of the main steam working medium and the enthalpy change is specifically: In the formula, θ′ T is the main steam working medium temperature; h′ T is the enthalpy of the main steam working medium; c P is the isobaric specific heat of the working fluid, k θ is the extraordinary coefficient, p′ T Main steam working pressure.

4. The method for approximate calculation of the quantitative influence of fuel quantity disturbance on steam temperature of a once-through boiler according to claim 1 is characterized in that: The approximate calculation equation for the critical condition flow of the steam turbine is specifically: The reduced temperature empirical equation of the main steam working medium temperature is specifically: The functional expression between the main steam working medium pressure and the main steam working medium temperature is specifically: Where D is the steam flow rate; K is the flow coefficient; p' T is the main steam working medium pressure; The equivalent temperature of the main steam working medium temperature; θ′ T is the main steam working medium temperature; Subscript 0 indicates the parameters in the original steady state; 5. The method for approximate calculation of the quantitative influence of fuel quantity disturbance on steam temperature of a once-through boiler according to claim 1 is characterized in that: The functional expression of the main steam working medium temperature, the change of boiler fuel quantity and the change of boiler thermal efficiency is specifically as follows: In the formula, θ′ T is the main steam working medium temperature; δh ∑ is the total enthalpy increase of the working fluid after passing through the boiler; c P is the isobaric specific heat of the working fluid, B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate; η is the boiler efficiency.

6. The method for approximate calculation of the quantitative influence of fuel quantity disturbance on steam temperature of a once-through boiler according to claim 1 is characterized in that: The relationship equation between the furnace outlet flue gas temperature and boiler fuel quantity after differentiation is specifically: Where T1′ t is the flue gas temperature at the furnace outlet; T a is the theoretical combustion temperature; the subscript 0 represents the reference condition or the condition before the fuel amount changes; B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate.

7. The method for approximate calculation of the quantitative influence of fuel quantity disturbance on steam temperature of a once-through boiler according to claim 1 is characterized in that: The expression of the variation of the exhaust gas temperature of the boiler is specifically: In the formula, θ py is the exhaust gas temperature of the boiler; ζ is a correction coefficient less than 1; T1′ t is the flue gas temperature at the furnace outlet.

8. The method for approximate calculation of the quantitative influence of fuel quantity disturbance on steam temperature of a once-through boiler according to claim 1 is characterized in that: The approximate calculation model of the quantitative effect of the boiler fuel quantity disturbance on the steam temperature is specifically: In the formula, θ′ T is the main steam working medium temperature; δh ∑ is the total enthalpy increase of the working fluid after passing through the boiler; c P is the isobaric specific heat of the working fluid, T a is the theoretical combustion temperature; T′ 1t is the flue gas temperature at the furnace outlet; ζ is a correction coefficient less than 1; q2 is the boiler flue gas heat loss; θ py is the exhaust gas temperature of the boiler; t0 is the ambient temperature; η is the boiler efficiency; the subscript 0 indicates the baseline operating condition or the operating condition before the fuel quantity changes; B is the fuel flow rate, including the air supply volume corresponding to the fuel flow rate.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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