Method for calculating influence of heat disturbance on steam temperature of intermediate point of once-through furnace and related product

Abstract

The invention discloses a method for calculating the influence of heat disturbance on the steam temperature of an intermediate point of a once-through furnace and a related product, and belongs to the technical field of thermal equipment performance state diagnosis. According to the method for calculating the influence of the heat disturbance on the steam temperature of the intermediate point of the once-through furnace, a reasonable relational expression is constructed on the basis of the basic principle of fluid mechanics, the first law of thermodynamics and the basic principle of differential by utilizing the function relation between the enthalpy value of a working medium and the specific volume of steam; obtaining a fifth relational expression of steam temperature change of the intermediate point of the once-through furnace under heat disturbance through step-by-step derivation; according to the method, tedious parameter collection and complex operation are not needed, the problems that a traditional method is tedious in calculation and long in consumed time are solved, quantitative influence data of heat change on the steam temperature of the intermediate point of the direct-current furnace can be rapidly and accurately calculated, an operator can rapidly diagnose the performance of the direct-current furnace according to the accurate calculation result, and the efficiency of the direct-current furnace is improved. Potential problems are found in time, unit operation parameters are adjusted, and therefore safe and stable operation of the unit is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal equipment performance status diagnosis, and in particular to a calculation method for the influence of heat disturbance on the steam temperature at the intermediate point of a direct current furnace and related products. Background Art

[0002] Direct-flow boiler units are key equipment in modern thermal power generation. They offer numerous advantages, including high efficiency and flexibility, and play a crucial role in power generation. Load changes are often accompanied by heat changes. Because direct-flow boilers lack a steam drum, these heat changes significantly impact the main steam temperature and pressure. In actual operation, the main steam temperature is often regulated by controlling the intermediate point temperature.

[0003] Traditional thermal disturbance calculations of the steam temperature at the midpoint of a DC furnace rely heavily on complex mechanism models. In actual engineering applications, these methods are unable to meet the needs of rapid and accurate diagnosis and timely regulation of the unit at the operating site due to the following limitations: First, the modeling process is time-consuming and labor-intensive, making it difficult to adjust the unit's operating parameters in a timely manner and adapting to the needs of rapid on-site analysis; second, the calculation logic is cumbersome and requires the embedding of a large number of specific structural parameters. In actual operation, some structural parameters often cannot be accurately obtained, resulting in increased calculation errors and misleading operational regulation.

[0004] Therefore, how to provide a method that can quickly and accurately quantitatively calculate the impact of thermal disturbance on the steam temperature at the midpoint of a DC furnace has become a technical problem that needs to be overcome urgently by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a calculation method and related products for the influence of thermal disturbance on the steam temperature at the intermediate point of a DC furnace, so as to overcome the problem that traditional calculation methods are difficult to meet the requirements of rapid and accurate on-site diagnosis of the unit.

[0006] The present invention solves the above technical problems through the following technical solutions: A method for calculating the effect of thermal disturbance on the steam temperature at the intermediate point of a DC furnace comprises the following steps: Based on the basic principles of fluid mechanics, a first relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last superheater of the DC furnace is constructed, and a second relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last superheater of the DC furnace and the steam flow rate in the pipeline is derived. By differentiating the second relationship and combining it with the function relationship of zero steam flow rate change in the pipeline under stable working conditions and the steam specific volume, the third relationship about the steam pressure change at the midpoint of the direct current furnace is derived. Based on the first law of thermodynamics, the fourth relationship is constructed and differentiated. Combined with the zero change in steam flow rate in the pipeline under stable working conditions and the functional relationship of the working medium enthalpy value, the fifth relationship for the change in steam temperature at the midpoint of the direct current furnace under thermal disturbance is derived. Collect the unit operation data, combine the third and fifth equations, and calculate the change in steam temperature at the midpoint of the DC boiler.

[0007] A further improvement of the present invention is that the first relational expression for the pressure difference between the intermediate point of the DC furnace and the outlet of the last-stage superheater of the DC furnace is specifically:

[0008] in, It is the pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater of the DC furnace; is the midpoint steam pressure; The steam pressure at the outlet of the last stage superheater of the direct current furnace; is the friction resistance coefficient; is the pipe length; is the inner diameter of the pipe; is the average steam velocity in the pipeline; is the local resistance coefficient of the pipeline; is the average density of steam in the pipe; It is the height difference between the middle point of the DC furnace and the outlet of the last stage superheater of the DC furnace; is the acceleration due to gravity.

[0009] A further improvement of the present invention is that the second relationship between the pressure difference between the intermediate point of the DC furnace and the outlet of the last-stage superheater of the DC furnace and the steam flow rate in the pipeline is specifically:

[0010] in, is the reduced resistance coefficient of the pipeline; is the steam flow rate in the pipeline; is the average specific volume of steam in the pipeline; is the flow cross-sectional area of ​​the pipe.

[0011] A further improvement of the present invention is that the third relational expression for the change in steam pressure at the intermediate point of the DC furnace is specifically:

[0012] in, is the change in steam pressure at the midpoint; is the change in steam pressure at the outlet of the last stage superheater of the direct current boiler; is the partial derivative of the average specific volume of steam in the pipeline with respect to pressure; is the partial derivative of the average specific volume of steam in the pipeline with respect to temperature; The average change in steam temperature from the intermediate point to the turbine regulating valve; The average change in steam pressure from the intermediate point to the turbine regulating valve.

[0013] A further improvement of the present invention is that the fourth relationship is specifically:

[0014] in, is the thermal efficiency of the DC furnace; is the calorific value of fuel per unit mass; is the fuel consumption of the DC furnace; The ratio of the heat absorbed from the feed water to the middle point of the DC boiler to the heat absorbed by the steam and water in the DC boiler; is the enthalpy of the working fluid at the middle point of the DC furnace; is the feed water enthalpy of the direct current boiler; is the enthalpy increase from the working fluid feed water to the midpoint of the direct current furnace.

[0015] A further improvement of the present invention is that the fifth relational expression for the change of the steam temperature at the intermediate point of the DC furnace under the thermal disturbance is specifically:

[0016] in, is the steam temperature variation at the middle point of the DC furnace; is the isobaric specific heat at the midpoint of the DC furnace; is the change in fuel consumption of the DC furnace; For thermal disturbance; is a non-constant coefficient.

[0017] A further improvement of the present invention is that the unit operation data specifically includes: the steam pressure at the outlet of the last stage superheater of the direct current furnace, the change in steam pressure at the outlet of the last stage superheater of the direct current furnace, the steam pressure at the intermediate point, the working fluid enthalpy at the intermediate point of the direct current furnace, the enthalpy of feed water of the direct current furnace, the average specific volume of steam in the pipeline, the isobaric specific heat at the intermediate point of the direct current furnace, the average change in steam temperature from the intermediate point to the turbine regulating valve, the average change in steam pressure from the intermediate point to the turbine regulating valve, the partial derivative of the average specific volume of steam in the pipeline with respect to temperature, the partial derivative of the average specific volume of steam in the pipeline with respect to pressure and the non-constant coefficient.

[0018] A further improvement of the present invention is that the value of the non-constant coefficient is 2.1.

[0019] Based on the same inventive concept, the present invention also provides a system for calculating the impact of heat disturbance on the steam temperature at the intermediate point of a DC furnace, comprising: The first module is used to construct a first relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last-stage superheater of the DC furnace based on the basic principles of fluid mechanics, and to derive a second relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last-stage superheater of the DC furnace and the steam flow rate in the pipeline; The second module is used to perform differential processing on the second relationship, and derive the third relationship about the change of steam pressure at the midpoint of the direct current furnace by combining the zero change of steam flow rate in the pipeline under stable working conditions and the functional relationship of steam specific volume; The third module is used to construct the fourth relationship based on the first law of thermodynamics, perform differential processing on the fourth relationship, and combine the zero change in steam flow rate in the pipeline under stable working conditions with the functional relationship of the enthalpy value of the working medium to derive the fifth relationship for the change in steam temperature at the intermediate point of the direct current furnace under thermal disturbance; The fourth module is used to collect the unit operation data, and calculate the change of the steam temperature at the middle point of the DC furnace by combining the third and fifth relationship equations.

[0020] Based on the same inventive concept, the present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the calculation method for the influence of heat disturbance on the steam temperature at the intermediate point of a DC furnace are implemented as described above.

[0021] Compared with the prior art, the present invention has the following positive effects: The calculation method for the influence of heat disturbance on the steam temperature at the midpoint of a DC furnace provided by the present invention is based on the basic principles of fluid mechanics, the first law of thermodynamics and the basic principles of differentials, and uses the functional relationship between the enthalpy of the working fluid and the specific volume of steam to construct a reasonable relationship. By step-by-step deduction, the fifth relationship for the change of the steam temperature at the midpoint of a DC furnace under heat disturbance is obtained. This method does not require lengthy parameter collection and complex calculations, overcomes the problems of cumbersome and time-consuming calculations of traditional methods, and can quickly and accurately calculate the quantitative impact data of heat changes on the steam temperature at the midpoint of a DC furnace, so that operating personnel can quickly diagnose the performance of the DC furnace based on accurate calculation results, promptly discover potential problems and adjust the operating parameters of the unit, thereby ensuring the safe and stable operation of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 The present invention is a flow chart of a method for calculating the influence of heat disturbance on the steam temperature at the midpoint of a DC furnace. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0025] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0026] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0027] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0028] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it.

[0030] See also Figure 1 The present invention provides a method for calculating the influence of heat disturbance on the steam temperature at the intermediate point of a DC furnace, comprising the following steps: Based on the basic principles of fluid mechanics, a first relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last superheater of the DC furnace is constructed, and a second relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last superheater of the DC furnace and the steam flow rate in the pipeline is derived. By differentiating the second relationship and combining it with the function relationship of zero steam flow rate change in the pipeline under stable working conditions and the steam specific volume, the third relationship about the steam pressure change at the midpoint of the direct current furnace is derived. Based on the first law of thermodynamics, the fourth relationship is constructed and differentiated. Combined with the zero change in steam flow rate in the pipeline under stable working conditions and the functional relationship of the working medium enthalpy value, the fifth relationship for the change in steam temperature at the midpoint of the direct current furnace under thermal disturbance is derived. Collect the unit operation data, combine the third and fifth equations, and calculate the change in steam temperature at the midpoint of the DC boiler.

[0031] The present invention is based on the basic principles of fluid mechanics. According to the analysis of the flow resistance loss of steam in the pipeline, a first relationship between the pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater of the DC furnace is constructed. The gravity pressure drop of the steam is ignored to determine the second relationship between the pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater of the DC furnace and the steam flow in the pipeline. By differentiating the second relationship between the pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater of the DC furnace and the steam flow in the pipeline, a third relationship between the steam pressure change at the middle point of the DC furnace is obtained. According to the energy conservation equation of steam, a fourth relationship is constructed, and the fifth relationship between the steam temperature change at the middle point of the DC furnace under heat disturbance is derived through differential processing. The problem that the calculation of the influence of the parameters of the DC furnace unit under heat disturbance is complicated and time-consuming is solved. Through a reasonable simplified formula, the quantitative influence of heat change on the steam temperature at the middle point of the DC furnace can be obtained quickly and more accurately, which can help operating personnel optimize operations and ensure stable and economical operation of the unit.

[0032] Specifically, the first relational expression for the pressure difference between the intermediate point of the DC furnace and the outlet of the last-stage superheater of the DC furnace is:

[0033] in, It is the pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater of the DC furnace; is the midpoint steam pressure; The steam pressure at the outlet of the last stage superheater of the direct current furnace; is the friction resistance coefficient; is the pipe length; is the inner diameter of the pipe; is the average steam velocity in the pipeline; is the local resistance coefficient of the pipeline; is the average density of steam in the pipe; It is the height difference between the middle point of the DC furnace and the outlet of the last stage superheater of the DC furnace; is the acceleration due to gravity.

[0034] Specifically, the second relationship between the pressure difference between the middle point of the DC furnace and the outlet of the last-stage superheater of the DC furnace and the steam flow rate in the pipeline is:

[0035] in, is the reduced resistance coefficient of the pipeline; is the steam flow rate in the pipeline; is the average specific volume of steam in the pipeline; is the flow cross-sectional area of ​​the pipe.

[0036] Specifically, the third relational expression for the change in steam pressure at the intermediate point of the DC furnace is:

[0037] in, is the change in steam pressure at the midpoint; is the change in steam pressure at the outlet of the last stage superheater of the direct current boiler; is the partial derivative of the average specific volume of steam in the pipeline with respect to pressure; is the partial derivative of the average specific volume of steam in the pipeline with respect to temperature; The average change in steam temperature from the intermediate point to the turbine regulating valve; The average change in steam pressure from the intermediate point to the turbine regulating valve.

[0038] Specifically, the fourth relational expression is:

[0039] in, is the thermal efficiency of the DC furnace; is the calorific value of fuel per unit mass; is the fuel consumption of the DC furnace; The ratio of the heat absorbed from the feed water to the middle point of the DC boiler to the heat absorbed by the steam and water in the DC boiler; is the enthalpy of the working fluid at the middle point of the DC furnace; is the feed water enthalpy of the direct current boiler; is the enthalpy increase from the working fluid feed water to the midpoint of the direct current furnace.

[0040] Specifically, the fifth relational expression for the change in steam temperature at the intermediate point of the DC furnace under the thermal disturbance is:

[0041] in, is the steam temperature variation at the middle point of the DC furnace; is the isobaric specific heat at the midpoint of the DC furnace; is the change in fuel consumption of the DC furnace; For thermal disturbance; is a non-constant coefficient.

[0042] Specifically, the unit operating data specifically include: the steam pressure at the outlet of the last stage superheater of the direct current furnace, the change in steam pressure at the outlet of the last stage superheater of the direct current furnace, the steam pressure at the intermediate point, the working fluid enthalpy at the intermediate point of the direct current furnace, the enthalpy of feed water of the direct current furnace, the average specific volume of steam in the pipeline, the isobaric specific heat at the intermediate point of the direct current furnace, the average change in steam temperature from the intermediate point to the turbine regulating valve, the average change in steam pressure from the intermediate point to the turbine regulating valve, the partial derivative of the average specific volume of steam in the pipeline with respect to temperature, the partial derivative of the average specific volume of steam in the pipeline with respect to pressure and the non-constant coefficient.

[0043] Specifically, the value of the non-constant coefficient is 2.1.

[0044] Based on the same inventive concept, the present invention also provides a system for calculating the impact of heat disturbance on the steam temperature at the intermediate point of a DC furnace, comprising: The first module is used to construct a first relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last-stage superheater of the DC furnace based on the basic principles of fluid mechanics, and to derive a second relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last-stage superheater of the DC furnace and the steam flow rate in the pipeline; The second module is used to perform differential processing on the second relationship, and derive the third relationship about the change of steam pressure at the midpoint of the direct current furnace by combining the zero change of steam flow rate in the pipeline under stable working conditions and the functional relationship of steam specific volume; The third module is used to construct the fourth relationship based on the first law of thermodynamics, perform differential processing on the fourth relationship, and combine the zero change in steam flow rate in the pipeline under stable working conditions with the functional relationship of the enthalpy value of the working medium to derive the fifth relationship for the change in steam temperature at the intermediate point of the direct current furnace under thermal disturbance; The fourth module is used to collect the unit operation data, and calculate the change of the steam temperature at the middle point of the DC furnace by combining the third and fifth relationship equations.

[0045] Example 1 The middle point of a DC furnace is generally the outlet of the steam-water separator. The water-cooled wall outlet header can be used to replace the middle point header. The pressure in the middle point header is considered to be , the pressure in the last stage superheater header is , ignoring the changing characteristics of the pressure distribution in the header, from the middle point of the DC furnace to the outlet of the DC furnace superheater, it is necessary to overcome the flow pressure drop and the gravity pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater. By ignoring the distribution changes of its pressure in the inlet and outlet headers, the pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater of the DC furnace is obtained as (1) in: is the pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater of the DC furnace, Pa; is the friction resistance coefficient, which is a dimensionless coefficient and is related to the Reynolds number and the roughness of the pipe wall; is the length of the pipeline, m; is the inner diameter of the pipe, m; is the average steam velocity in the pipeline, m / s; is the local resistance coefficient of the pipeline, which is a dimensionless coefficient and is related to the pipeline structure; is the average density of steam in the pipe, kg / m 3 ; is the height difference between the middle point of the DC furnace and the outlet of the last stage superheater of the DC furnace, m; is the acceleration due to gravity, m / (kgs 2 ); Since the steam from the middle point of the direct current boiler to the turbine inlet is all superheated steam, its gravity pressure drop can be ignored, so formula (1) can be further expressed as: (2)

[0046] in: is the steam flow rate in the pipeline, kg / s; is the average specific volume of steam in the pipeline, m 3 / kg; is the flow cross-sectional area of ​​the pipe, m 2 ; is the reduced resistance coefficient of the pipeline, so the relationship between the steam flow rate and pressure drop in the pipeline from the middle point of the once-through furnace to the superheater can be expressed as: (3) in: is the average specific volume of steam, m 3 / kg; is a constant, .

[0047] Differentiate formula (3), specifically take the logarithm and then take its increment, and we can get: (4) Under stable operating conditions, the steam-water flow rate flowing through the middle point of the DC furnace can be considered to be ,Right now: (5) Due to the specific volume of steam is pressure ( ) and temperature ( ), so the change of the average specific volume of steam in formula (5) can be expressed as: (6) in: is the average temperature of steam, °C; is the average specific volume of steam, m 3 / kg, approximately 、 The specific volume under the parameter can be expressed as follows by substituting formula (6) into formula (5): (7) The heat absorbed from the feed water to the midpoint of the DC boiler at static state is equal to the heat taken away by the working fluid, which can be expressed as: (8) in: The ratio of the heat absorbed from the DC boiler feed water to the DC boiler midpoint to the heat absorbed by the DC boiler steam and water. Under uniform load, this ratio can be assumed to be constant. is the enthalpy of the working fluid at the middle point of the DC furnace, kJ / kg; is the feed water enthalpy of the direct current furnace, kJ / kg; is the enthalpy increase from the working fluid feed water to the midpoint of the direct current furnace, kJ / kg, ; is the thermal efficiency of the DC furnace; is the calorific value of fuel per unit mass, kJ / kg; is the fuel consumption of the DC furnace, kg / s; Differentiate formula (8), specifically: take the natural logarithm, and then take the increment. Assume that the thermal efficiency of the DC furnace is and the low calorific value of coal remains unchanged. At the same time, when the heat is disturbed, the steam flow rate will eventually remain unchanged because the feed water and spray water flow rates remain unchanged, that is, =0, assuming the enthalpy of feed water remains unchanged, =0, we can get: (9) Since the enthalpy of the working fluid is a function of temperature and pressure, taking its increment we can get: (10) in: is the isobaric specific heat of the working fluid, kJ / (kg⋅℃), , is a non-constant coefficient, ; Substituting formula (9) into formula (10), we can obtain the calculation formula for the change of steam temperature at the middle point of the DC furnace under heat disturbance: (11) in: is the isobaric specific heat at the midpoint of the DC furnace, MPa.

[0048] Taking a 600MW supercritical coal-fired power unit as an example, according to the relevant thermodynamic charts and the relevant data collected from the unit operation, as shown in Table 1, a 1% thermal disturbance (i.e. ), quantitatively calculate the impact of heat disturbance on the steam temperature at the midpoint of the DC furnace.

[0049] Table 1 Unit operating data

[0050] Combined with the third relationship, the change in steam pressure at the intermediate point is calculated as , specifically:

[0051] Combined with the fifth relationship, the change in steam temperature at the middle point of the DC furnace is calculated as

[0052]

[0053] This method is based on the basic principles of fluid mechanics, the first law of thermodynamics and the basic principles of differentials. It also uses the functional relationship between the working fluid enthalpy and the specific volume of steam to construct a reasonable relationship. By gradually deducing, the fifth relationship for the change in steam temperature at the midpoint of the DC furnace under heat disturbance is obtained. This method does not require lengthy parameter collection and complex calculations, overcomes the problems of cumbersome and time-consuming calculations in traditional methods, and can quickly and accurately calculate the quantitative impact data of heat changes on the steam temperature at the midpoint of the DC furnace, so that operating personnel can quickly diagnose the performance of the DC furnace based on accurate calculation results, promptly discover potential problems and adjust the unit operating parameters, thereby ensuring the safe and stable operation of the unit.

[0054] Based on the same inventive concept, an embodiment of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the computer-readable storage medium implements the steps of the method for calculating the impact of thermal disturbance on the steam temperature at the intermediate point of a direct current furnace. Specifically, the computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. The volatile memory may include RAM (Random Access Memory) and / or cache memory, etc. The non-volatile memory may include ROM (Read-Only Memory), a hard disk, a flash memory, an optical disk, a magnetic disk, etc.

[0055] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM (Compact Disc Read-Only Memory), optical storage, etc.) containing computer-usable program code.

[0056] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer device or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0057] These computer program instructions may also be stored in a computer readable memory that can direct a computer device or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0058] These computer program instructions can also be loaded onto a computer device or other programmable data processing device so that a series of operating steps are executed on the computer device or other programmable device to produce a process implemented by the computer device, thereby providing instructions for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0059] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0060] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for calculating the effect of thermal disturbance on the steam temperature at the intermediate point of a DC furnace, characterized in that: The following steps are involved: Based on the basic principles of fluid mechanics, a first relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last superheater of the DC furnace is constructed, and a second relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last superheater of the DC furnace and the steam flow rate in the pipeline is derived. By differentiating the second relationship and combining it with the function relationship of zero steam flow rate change in the pipeline under stable working conditions and the steam specific volume, the third relationship about the steam pressure change at the midpoint of the direct current furnace is derived. Based on the first law of thermodynamics, the fourth relationship is constructed and differentiated. Combined with the zero change in steam flow rate in the pipeline under stable working conditions and the functional relationship of the working medium enthalpy value, the fifth relationship for the change in steam temperature at the midpoint of the direct current furnace under thermal disturbance is derived. Collect the unit operation data, combine the third and fifth equations, and calculate the change in steam temperature at the midpoint of the DC boiler.

2. The method for calculating the effect of thermal disturbance on the steam temperature at the intermediate point of a DC furnace according to claim 1, characterized in that: The first relational expression for the pressure difference between the middle point of the DC furnace and the outlet of the last-stage superheater of the DC furnace is specifically: in, It is the pressure difference from the middle point of the DC furnace to the outlet of the last stage superheater of the DC furnace; is the midpoint steam pressure; The steam pressure at the outlet of the last stage superheater of the direct current furnace; is the friction resistance coefficient; is the pipe length; is the inner diameter of the pipe; is the average steam velocity in the pipeline; is the local resistance coefficient of the pipeline; is the average density of steam in the pipe; It is the height difference between the middle point of the DC furnace and the outlet of the last stage superheater of the DC furnace; is the acceleration due to gravity.

3. The method for calculating the effect of thermal disturbance on the steam temperature at the intermediate point of a DC furnace according to claim 2, characterized in that: The second relationship between the pressure difference between the middle point of the DC furnace and the outlet of the last-stage superheater of the DC furnace and the steam flow rate in the pipeline is specifically: in, is the reduced resistance coefficient of the pipeline; is the steam flow rate in the pipeline; is the average specific volume of steam in the pipeline; is the flow cross-sectional area of ​​the pipe.

4. The method for calculating the effect of thermal disturbance on the steam temperature at the intermediate point of a DC furnace according to claim 3, characterized in that: The third relational expression for the change in steam pressure at the intermediate point of the DC furnace is specifically: in, is the change in steam pressure at the midpoint; is the change in steam pressure at the outlet of the last stage superheater of the direct current boiler; is the partial derivative of the average specific volume of steam in the pipeline with respect to pressure; is the partial derivative of the average specific volume of steam in the pipeline with respect to temperature; The average change in steam temperature from the intermediate point to the turbine regulating valve; The average change in steam pressure from the intermediate point to the turbine regulating valve.

5. The method for calculating the effect of heat disturbance on the steam temperature at the intermediate point of a DC furnace according to claim 4, characterized in that: The fourth relational expression is specifically: in, is the thermal efficiency of the DC furnace; is the calorific value of fuel per unit mass; is the fuel consumption of the DC furnace; The ratio of the heat absorbed from the feed water to the middle point of the DC boiler to the heat absorbed by the steam and water in the DC boiler; is the enthalpy of the working fluid at the middle point of the DC furnace; is the feed water enthalpy of the direct current boiler; is the enthalpy increase from the working fluid feed water to the midpoint of the direct current furnace.

6. The method for calculating the effect of heat disturbance on the steam temperature at the intermediate point of a DC furnace according to claim 5, characterized in that: The fifth relational expression for the change of the steam temperature at the intermediate point of the DC furnace under the thermal disturbance is specifically: in, is the steam temperature variation at the middle point of the DC furnace; is the isobaric specific heat at the midpoint of the DC furnace; is the change in fuel consumption of the DC furnace; For thermal disturbance; is a non-constant coefficient.

7. The method for calculating the effect of heat disturbance on the steam temperature at the intermediate point of a DC furnace according to claim 1, characterized in that: The unit operation data specifically include: the steam pressure at the outlet of the last stage superheater of the direct current furnace, the change in steam pressure at the outlet of the last stage superheater of the direct current furnace, the steam pressure at the intermediate point, the working fluid enthalpy at the intermediate point of the direct current furnace, the feed water enthalpy of the direct current furnace, the average specific volume of steam in the pipeline, the isobaric specific heat at the intermediate point of the direct current furnace, the average change in steam temperature from the intermediate point to the turbine regulating valve, the average change in steam pressure from the intermediate point to the turbine regulating valve, the partial derivative of the average specific volume of steam in the pipeline with respect to temperature, the partial derivative of the average specific volume of steam in the pipeline with respect to pressure and the non-constant coefficient.

8. The method for calculating the effect of heat disturbance on the steam temperature at the intermediate point of a DC furnace according to claim 7, characterized in that: The value of the non-constant coefficient is 2.

1.

9. A system for calculating the effect of heat disturbance on the steam temperature at the intermediate point of a DC furnace, characterized in that: include: The first module is used to construct a first relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last-stage superheater of the DC furnace based on the basic principles of fluid mechanics, and to derive a second relationship between the pressure difference between the midpoint of the DC furnace and the outlet of the last-stage superheater of the DC furnace and the steam flow rate in the pipeline; The second module is used to perform differential processing on the second relationship, and derive the third relationship about the change of steam pressure at the midpoint of the direct current furnace by combining the zero change of steam flow rate in the pipeline under stable working conditions and the functional relationship of steam specific volume; The third module is used to construct the fourth relationship based on the first law of thermodynamics, perform differential processing on the fourth relationship, and combine the zero change in steam flow rate in the pipeline under stable working conditions with the functional relationship of the enthalpy value of the working medium to derive the fifth relationship for the change in steam temperature at the intermediate point of the direct current furnace under thermal disturbance; The fourth module is used to collect the unit operation data, and calculate the change of the steam temperature at the middle point of the DC furnace by combining the third and fifth relationship equations.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for calculating the influence of heat disturbance on the steam temperature at the midpoint of a DC furnace as described in any one of claims 1 to 8 are implemented.

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