Quantitative analysis method and system for influence of feed water flow disturbance on steam pressure and steam temperature

Abstract

The invention discloses a quantitative analysis method and system for the influence of feed water flow disturbance on steam pressure and steam temperature, and belongs to the technical field of thermal equipment performance state diagnosis. According to the method, the energy balance equation is established, the equivalent relation between the feed water flow and the steam flow is introduced, differential increment derivation is conducted, dependence of traditional variable working condition calculation on a large number of boiler structure parameters is avoided, and the calculation process is greatly simplified; the steam enthalpy value change equation, the temperature-pressure differential relation and the steam turbine flow formula are combined, a simple quantitative calculation formula is obtained through derivation, the disturbance influence can be rapidly calculated only through basic operation parameters without relying on tedious test data, and therefore the analysis efficiency is improved, and the method is suitable for large-scale popularization and application. A power station operation engineer is helped to rapidly predict and evaluate the quantitative influence of the feed water flow change on the steam pressure and the steam temperature of the once-through furnace, so that effective adjustment measures can be taken in time, and safe, stable and efficient operation of a unit is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal equipment performance status diagnosis, and in particular to a quantitative analysis method and system for the influence of feedwater flow disturbance on steam pressure and steam temperature. Background Art

[0002] In supercritical coal-fired power plants, the regulation of main steam temperature and pressure in once-through boilers is highly dependent on the precise matching of the coal-to-water ratio. Feedwater flow, the core control variable of this ratio, has a dynamic impact on the boiler's energy balance and fluid flow characteristics, which in turn affects the stability of main steam temperature and pressure, as well as intermediate point temperatures and pressures. Therefore, establishing a quantitative analysis method for the impact of feedwater flow changes on steam temperature and pressure is a key technical prerequisite for designing efficient control strategies and ensuring safe and economical unit operation.

[0003] Current quantitative analysis of the effects of feedwater flow disturbances on steam temperature and pressure in once-through boilers primarily relies on variable-operating-condition thermodynamic calculations and field testing. However, these methods suffer from the following drawbacks: They rely on boiler structural parameters (such as heating surface area and fluid flow resistance), thermodynamic properties, and multivariable coupling relationships. The computational complexity makes it difficult to quickly generate effective conclusions, thus failing to meet the needs of on-site operators for real-time operating condition analysis. Complex calculations make it difficult for operators to quickly diagnose and adjust boiler performance changes. This often leads to delayed responses, resulting in coal-water ratio imbalances, missed optimal adjustment opportunities, and increased unit operational risks. In actual projects, some precise structural parameters (such as the local flow resistance coefficient and the dynamic heat transfer coefficient) are difficult to obtain in real time or are subject to measurement errors, causing calculation results to deviate from actual operating conditions and resulting in a waste of human and material resources. In summary, the lack of efficient and accurate quantitative analysis methods currently available cannot meet the needs for real-time monitoring and rapid control of steam temperature and pressure during once-through boiler operation, and makes in-depth diagnosis of boiler performance even more difficult.

[0004] Therefore, how to break through the limitations of traditional methods and provide an efficient, accurate and rapid quantitative analysis method 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 quantitative analysis method and system for the impact of feedwater flow disturbance on steam pressure and steam temperature, so as to overcome the problems of insufficient real-time performance and limited analysis accuracy caused by the existing technology relying on complex variable operating condition calculations and experiments.

[0006] The present invention solves the above technical problems through the following technical solutions: A quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature comprises the following steps: Based on the energy balance principle, an energy balance equation is established, introducing the equivalent relationship between feedwater flow and steam flow, and deriving the steam enthalpy change equation through differential increment. The steam enthalpy value is processed as a temperature-pressure function, and the steam temperature change equation is derived through differential increment. A formula for the reduced temperature of steam before the turbine regulating valve is constructed, and combined with the turbine critical operating flow approximate formula, the feedwater flow disturbance equation is derived through differential increment. The steam enthalpy change equation, steam temperature change equation and feedwater flow disturbance equation are derived and simplified to obtain the first quantitative calculation formula for the effect of feedwater flow disturbance on the steam temperature at the outlet of the once-through boiler and the second quantitative calculation formula for the effect of feedwater flow disturbance on the steam pressure at the outlet of the once-through boiler. By analyzing the pressure change transmission characteristics caused by the feedwater flow disturbance, and combining the first and second quantitative calculation formulas, we derive the third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the DC boiler, and the fourth quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the midpoint of the DC boiler. Collect unit operation data, and implement quantitative analysis by combining the first quantitative calculation formula, the second quantitative calculation formula, the third quantitative calculation formula, and the fourth quantitative calculation formula.

[0007] A further improvement of the present invention is that the energy balance equation is specifically:

[0008] in, The heat absorbed by the DC furnace; is the feed water flow rate of the direct current boiler; is the main steam enthalpy of the once-through boiler; is the feed water enthalpy of the direct current furnace; The steam enthalpy change equation is specifically:

[0009] in, is the change in steam enthalpy; is the intermediate parameter, ; is the change in feed water flow rate of the DC boiler.

[0010] A further improvement of the present invention is that the steam temperature variation equation is specifically:

[0011] in, is the steam temperature change; is the change in steam enthalpy; is the isobaric specific heat of the working fluid; is the extraordinary coefficient, ; is the steam pressure change; The formula for the reduced temperature of the steam before the turbine regulating valve is specifically:

[0012] in, To adjust the reduced temperature of steam before the valve of the steam turbine; Adjust the steam temperature before the steam valve for the steam turbine; Adjust the steam pressure before the steam valve for the steam turbine, which is equal to the steam pressure at the outlet of the direct current boiler; is the first coefficient, ; is the second coefficient, ; Subscript 0 indicates the operating parameters of the DC furnace in steady state.

[0013] A further improvement of the present invention is that the approximate formula for the critical operating condition feedwater flow of the steam turbine is specifically:

[0014] in, is the flow coefficient.

[0015] A further improvement of the present invention is that the water flow disturbance equation is specifically:

[0016] in, is the water flow disturbance; Adjust the steam pressure change before the steam valve for the steam turbine; Adjust the change of steam temperature before the steam valve of the turbine.

[0017] A further improvement of the present invention is that the first quantitative calculation formula for the effect of the feed water flow disturbance on the steam temperature at the outlet of the direct current boiler is specifically:

[0018] in, To adjust the isobaric specific heat before the steam valve of the steam turbine.

[0019] A further improvement of the present invention is that the second quantitative calculation formula for the effect of the feed water flow disturbance on the steam pressure at the outlet of the direct current boiler is specifically:

[0020] in, is the third coefficient, .

[0021] A further improvement of the present invention is that the third quantitative calculation formula for the effect of the feed water flow disturbance on the steam temperature at the midpoint of the direct current boiler is specifically:

[0022] in, is the change in steam pressure at the midpoint of the DC furnace.

[0023] A further improvement of the present invention is that the third quantitative calculation formula for the effect of the feed water flow disturbance on the steam temperature at the midpoint of the direct current boiler is specifically:

[0024] in, is the steam temperature variation at the middle point of the DC furnace; is the constant pressure specific heat of steam at the midpoint of the direct current furnace; is the water feed enthalpy value at the midpoint; the subscript cer indicates the parameter of the midpoint.

[0025] The present invention also provides a quantitative analysis system for the effect of feedwater flow disturbance on steam pressure and steam temperature, comprising: The first module is used to establish an energy balance equation based on the energy balance principle, introduce the equivalent relationship between feedwater flow and steam flow, and derive the steam enthalpy change equation through differential increment. The steam enthalpy is processed as a temperature-pressure function and the steam temperature change equation is derived through differential increment. The reduced temperature formula of the steam before the turbine regulating valve is constructed, and combined with the turbine critical operating flow approximate formula, the feedwater flow disturbance equation is derived through differential increment. The second module is used to simultaneously establish the steam enthalpy change equation, the steam temperature change equation, and the feedwater flow disturbance equation. After derivation and simplification, the first quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the outlet of the DC boiler and the second quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the outlet of the DC boiler are obtained. The third module is used to analyze the pressure change transmission characteristics caused by the feedwater flow disturbance. By combining the first quantitative calculation formula and the second quantitative calculation formula, a third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the DC boiler and a fourth quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the midpoint of the DC boiler are derived. The fourth module is used to collect unit operation data and implement quantitative analysis by combining the first quantitative calculation formula, the second quantitative calculation formula, the third quantitative calculation formula and the fourth quantitative calculation formula.

[0026] Compared with the prior art, the present invention has the following positive effects: The quantitative analysis method of the influence of feedwater flow disturbance on steam pressure and steam temperature provided by the present invention establishes an energy balance equation, introduces the equivalent relationship between feedwater flow and steam flow and performs differential increment derivation, thereby avoiding the dependence of traditional variable operating condition calculations on a large number of boiler structural parameters and greatly simplifying the calculation process; by combining the steam enthalpy change equation, the temperature-pressure differential relationship and the turbine flow formula, a concise quantitative calculation formula is derived, which does not need to rely on cumbersome experimental data and only requires basic operating parameters to quickly calculate the disturbance influence, thereby improving analysis efficiency and helping power station operation engineers to quickly predict and evaluate the quantitative influence of feedwater flow changes on the steam pressure and steam temperature of the direct current boiler, so as to take effective adjustment measures in time to ensure the safe, stable and efficient operation of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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.

[0028] Figure 1 The figure is a flow chart of a quantitative analysis method for the influence of feedwater flow disturbance on steam pressure and steam temperature according to the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] 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.

[0031] See also Figure 1 A quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature comprises the following steps: Based on the energy balance principle, an energy balance equation is established, introducing the equivalent relationship between feedwater flow and steam flow, and deriving the steam enthalpy change equation through differential increment. The steam enthalpy value is processed as a temperature-pressure function, and the steam temperature change equation is derived through differential increment. A formula for the reduced temperature of steam before the turbine regulating valve is constructed, and combined with the turbine critical operating flow approximate formula, the feedwater flow disturbance equation is derived through differential increment. The steam enthalpy change equation, steam temperature change equation and feedwater flow disturbance equation are derived and simplified to obtain the first quantitative calculation formula for the effect of feedwater flow disturbance on the steam temperature at the outlet of the once-through boiler and the second quantitative calculation formula for the effect of feedwater flow disturbance on the steam pressure at the outlet of the once-through boiler. By analyzing the pressure change transmission characteristics caused by the feedwater flow disturbance, and combining the first and second quantitative calculation formulas, we derive the third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the DC boiler, and the fourth quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the midpoint of the DC boiler. Collect unit operation data, and implement quantitative analysis by combining the first quantitative calculation formula, the second quantitative calculation formula, the third quantitative calculation formula, and the fourth quantitative calculation formula.

[0032] The quantitative analysis method of the influence of feed water flow disturbance on steam pressure and steam temperature provided by the present invention establishes an energy balance equation, introduces the equivalent relationship between feed water flow and steam flow and performs differential increment derivation, thereby avoiding the dependence of traditional variable operating condition calculations on a large number of boiler structural parameters and greatly simplifying the calculation process; by combining the steam enthalpy change equation, the temperature-pressure differential relationship and the turbine flow formula, a concise quantitative calculation formula is derived, which does not need to rely on cumbersome experimental data and only requires basic operating parameters to quickly calculate the disturbance impact, thereby improving analysis efficiency and meeting monitoring needs.

[0033] Specifically, the energy balance equation is:

[0034] in, The heat absorbed by the DC furnace; is the feed water flow rate of the direct current boiler; is the main steam enthalpy of the once-through boiler; is the feed water enthalpy of the direct current furnace; The steam enthalpy change equation is specifically:

[0035] in, is the change in steam enthalpy; is the intermediate parameter, ; is the change in feed water flow rate of the DC boiler.

[0036] Specifically, the steam temperature variation equation is:

[0037] in, is the steam temperature change; is the change in steam enthalpy; is the isobaric specific heat of the working fluid; is the extraordinary coefficient, ; is the steam pressure change; The formula for the reduced temperature of the steam before the turbine regulating valve is specifically:

[0038] in, To adjust the reduced temperature of steam before the valve of the steam turbine; Adjust the steam temperature before the steam valve for the steam turbine; Adjust the steam pressure before the steam valve for the steam turbine, which is equal to the steam pressure at the outlet of the direct current boiler; is the first coefficient, ; is the second coefficient, ; Subscript 0 indicates the operating parameters of the DC furnace in steady state.

[0039] Specifically, the approximate formula for the critical operating condition feedwater flow of the steam turbine is:

[0040] in, is the flow coefficient.

[0041] Specifically, the water flow disturbance equation is:

[0042] in, is the water flow disturbance; Adjust the steam pressure change before the steam valve for the steam turbine; Adjust the change of steam temperature before the steam valve of the turbine.

[0043] Specifically, the first quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the outlet of the direct current boiler is:

[0044] in, To adjust the isobaric specific heat before the steam valve of the steam turbine.

[0045] Specifically, the second quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the outlet of the direct current boiler is:

[0046] in, is the third coefficient, .

[0047] Specifically, the third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the direct current boiler is:

[0048] in, is the change in steam pressure at the midpoint of the DC furnace.

[0049] Specifically, the third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the direct current boiler is:

[0050] in, is the steam temperature variation at the middle point of the DC furnace; is the constant pressure specific heat of steam at the midpoint of the direct current furnace; is the water feed enthalpy value at the midpoint; the subscript cer indicates the parameter of the midpoint.

[0051] Based on the same inventive concept, the present invention also provides a quantitative analysis system for the impact of feedwater flow disturbance on steam pressure and steam temperature, comprising: The first module is used to establish an energy balance equation based on the energy balance principle, introduce the equivalent relationship between feedwater flow and steam flow, and derive the steam enthalpy change equation through differential increment. The steam enthalpy is processed as a temperature-pressure function and the steam temperature change equation is derived through differential increment. The reduced temperature formula of the steam before the turbine regulating valve is constructed, and combined with the turbine critical operating flow approximate formula, the feedwater flow disturbance equation is derived through differential increment. The second module is used to simultaneously establish the steam enthalpy change equation, the steam temperature change equation, and the feedwater flow disturbance equation. After derivation and simplification, the first quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the outlet of the DC boiler and the second quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the outlet of the DC boiler are obtained. The third module is used to analyze the pressure change transmission characteristics caused by the feedwater flow disturbance. By combining the first quantitative calculation formula and the second quantitative calculation formula, a third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the DC boiler and a fourth quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the midpoint of the DC boiler are derived. The fourth module is used to collect unit operation data and implement quantitative analysis by combining the first quantitative calculation formula, the second quantitative calculation formula, the third quantitative calculation formula and the fourth quantitative calculation formula.

[0052] Example 1 (a) The influence of feedwater flow on the main steam outlet temperature and pressure of the once-through boiler According to the energy balance principle of DC furnace, the following calculation equation can be established: (1) Where: is the heat absorbed by the DC furnace, kW; is the feed water flow rate of the DC furnace, kg / s; is the main steam enthalpy of the direct current boiler, kJ / kg; is the feed water enthalpy of the DC furnace, kJ / kg; For a direct current boiler, ignoring the effect of water spray cooling, the feed water flow rate can be considered to be approximately equal to the steam flow rate. Therefore, taking the natural logarithm of equation (1) and then taking the increment, we obtain: (2) Where, ; The enthalpy of steam working medium is regarded as a function of temperature and pressure, that is, , taking its increment, we can get: (3) Where: is the isobaric specific heat of the working fluid, , kJ / (kg·°C); is the extraordinary coefficient, ; is the enthalpy of steam, kJ / kg; is the temperature of steam, °C; is the steam pressure, MPa; Represents the change in steam parameters; Therefore, equation (3) can be further expressed as: (4) According to the approximate formula of steam turbine critical operating flow: (5) Where: is the steam flow rate of the direct current furnace, kg / s; K is the flow coefficient; The steam pressure before the turbine regulating valve is equivalent to the steam pressure at the outlet of the once-through boiler, MPa; The reduced temperature of steam before the turbine regulating valve, °C; The reduced temperature of steam before the turbine regulating valve can be expressed as: (6) Where: Steam temperature before regulating valve for steam turbine, °C; is the first coefficient; is the second coefficient; in:

[0053]

[0054] Where: footnote 0 represents the operating parameters of the DC furnace in steady state.

[0055] Taking the natural logarithm of equation (5) and then taking its increment, we can obtain: (7) Solving equation (4), equation (7) and equation (2) together, we can obtain: (8) Where: , (9) In equations (8) and (9), since, , after verification, equation (8) and equation (9) can be simplified into the following forms: (10) (11) Therefore, regardless of whether the outlet steam pressure of the DC boiler is maintained or not, the influence of the feed water flow disturbance on the outlet steam temperature is calculated according to equation (10), and the influence of the feed water flow disturbance on the outlet steam pressure can be calculated according to equation (11). It can be seen that the influence of the feed water flow disturbance on the outlet steam pressure of the DC boiler is smaller than that of the heat disturbance; the influence of the two disturbances on the outlet steam temperature of the DC boiler is not much different, but in opposite directions; the influence of the feed water flow disturbance on the steam temperature is relatively slightly smaller.

[0056] (b) The effect of feedwater flow on the steam temperature and pressure at the midpoint of the DC boiler When the water flow rate increases, the pressure difference when the working medium flows through each heating surface The pressure difference in the steam-water process will also increase, but due to the decrease in steam temperature and increase in steam pressure, the working fluid volume flow rate will decrease. Calculations have shown that the effects of the above two factors essentially cancel each other out. Therefore, when the feedwater flow is disturbed, the change in the working fluid pressure on each heating surface in the steam-water process is approximately equal to the change in the steam pressure at the outlet of the DC boiler. That is, the change in the pressure at the midpoint of the DC boiler can be expressed as: (12) Where: is the change in steam pressure at the midpoint of the DC furnace, MPa; The calculation formula for the temperature change of the working fluid at a certain intermediate point is: (13) Where: is the change of steam temperature at the middle point of the DC furnace, °C; is the specific heat of steam at the midpoint of the direct current furnace at constant pressure, kJ / (kg·°C); Equation (12) and Equation (13) are the calculation equations for the effect of feed water flow on the temperature and pressure at the intermediate point of the DC boiler. Therefore, by combining Equation (10)-Equation (13), the quantitative effect of feed water flow changes on the steam pressure and steam temperature of the DC boiler can be determined.

[0057] Calculation example: Taking a 600MW supercritical coal-fired power unit as an example, according to the thermodynamic related charts and the unit operation data, as shown in Table 1, a 5% feed water flow disturbance occurs (i.e. ) This article describes a case study on the calculation and diagnosis of the steam pressure and temperature changes at a certain point in the steam-water process of a DC boiler.

[0058] Table 1 Unit operating data

[0059] (a) The influence of feedwater flow on the main steam outlet temperature and pressure of the once-through boiler

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] That is, the impact of feed water flow disturbance on the outlet steam temperature of the DC boiler is -63.53℃, and the impact of feed water flow disturbance on the outlet steam pressure of the DC boiler is a decrease of 0.502MPa.

[0066] (b) The effect of feed water flow on the temperature and pressure at the intermediate point of the DC furnace

[0067]

[0068] That is, the change in steam pressure at the midpoint of the DC boiler caused by the feed water flow disturbance is -0.502MPa, and the change in steam temperature at the midpoint of the DC boiler caused by the feed water flow disturbance is -26.91℃.

[0069] The present invention is based on the following concepts: first, based on the steam-water energy balance equation of the direct current boiler and combined with the differential idea, the calculation equation for the change in main steam outlet enthalpy is obtained; secondly, based on the steam state equation, further differentiation is performed to obtain a method for calculating the steam temperature change; thirdly, based on the turbine critical operating flow approximate formula and combined with the differential idea, the calculation equation for the influence of feed water flow disturbance on the outlet steam temperature and pressure can be obtained; finally, based on a similar method, the calculation equation for the influence of feed water flow disturbance on the steam temperature and pressure at the midpoint of the direct current boiler can be determined.

[0070] Based on the law of conservation of energy and mass, the basic principle of differentials and theories related to thermodynamics, this method proposes the principles followed in implementing the technical solution of the present invention, namely: the energy and ratio absorbed by the main steam and reheated steam of the direct current boiler can be regarded as constant. Such simplified processing can provide a method for calculating the reheated steam outlet enthalpy; the change in the reheated steam flow rate of the direct current boiler can be regarded as a function of the specific volume, that is, the change in the specific volume after the reheated steam pressure and temperature change causes the specific volume to change, and the specific volume will affect the change in the reheated steam flow rate; it can be approximately considered that the change in the reheated steam outlet temperature is only related to the temperature and pressure, and the influence of the flow change on the reheated steam temperature can be ignored.

[0071] This method solves the difficult problem of rapid and accurate quantitative analysis and calculation of the effects of feedwater disturbance changes on the steam pressure and temperature of the DC boiler. Through reasonable simplified formulas, it can quickly and relatively accurately obtain the quantitative effects of feedwater flow changes on the steam pressure and temperature of the DC boiler. This method can assist operating personnel in optimizing operations and regulating controls, thereby ensuring the safe and economical operation of the unit. It can also help power station operating engineers quickly predict and evaluate the quantitative effects of feedwater flow changes on the steam pressure and temperature of the DC boiler, so that effective adjustment measures can be taken in a timely manner to ensure the safe, stable and efficient operation of the unit.

[0072] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of the present invention. Their purpose is to clearly illustrate the concept, principles, and application of the present invention through specific examples, and is in no way intended to limit the scope of protection of the present invention to these specific embodiments. In fact, the true value of this invention lies in its technical ideas and innovations, not in its form of expression or implementation.

[0073] For ordinary technicians in the relevant technical field, after thoroughly reading and understanding the technical solutions of the present invention, they are fully capable of making various forms of changes, modifications or equivalent replacements to the specific implementation methods of the invention based on their own professional knowledge and skills. These changes may include but are not limited to: adjusting the value range of technical parameters, optimizing algorithm processes to improve efficiency, replacing some technical components to achieve better compatibility or reduce costs, etc. As long as these modified technical solutions still substantially maintain the technical features claimed for protection by the original invention, that is, they can still achieve the core functions and effects of the present invention, then these changes should be deemed to fall within the scope of protection of the pending claims of the present invention.

[0074] Furthermore, with the continuous advancement and development of technology, new technical means and methods continue to emerge, providing ample room for further improvement and perfection of the present invention. Therefore, the scope of protection of the present invention should also include reasonably foreseeable improvements and extensions based on existing technologies. As long as these improvements and extensions do not deviate from the basic principles and core concepts of the present invention, they should be considered equivalent to the present invention and equally protected by patent rights.

Claims

1. A quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature, characterized in that: The following steps are involved: Based on the energy balance principle, an energy balance equation is established, introducing the equivalent relationship between feedwater flow and steam flow, and deriving the steam enthalpy change equation through differential increment. The steam enthalpy value is processed as a temperature-pressure function, and the steam temperature change equation is derived through differential increment. A formula for the reduced temperature of steam before the turbine regulating valve is constructed, and combined with the turbine critical operating flow approximate formula, the feedwater flow disturbance equation is derived through differential increment. The steam enthalpy change equation, steam temperature change equation and feedwater flow disturbance equation are derived and simplified to obtain the first quantitative calculation formula for the effect of feedwater flow disturbance on the steam temperature at the outlet of the once-through boiler and the second quantitative calculation formula for the effect of feedwater flow disturbance on the steam pressure at the outlet of the once-through boiler. By analyzing the pressure change transmission characteristics caused by the feedwater flow disturbance, and combining the first and second quantitative calculation formulas, we derive the third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the DC boiler, and the fourth quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the midpoint of the DC boiler. Collect unit operation data, and implement quantitative analysis by combining the first quantitative calculation formula, the second quantitative calculation formula, the third quantitative calculation formula, and the fourth quantitative calculation formula.

2. The quantitative analysis method of the effect of feedwater flow disturbance on steam pressure and steam temperature according to claim 1, characterized in that: The energy balance equation is specifically: in, The heat absorbed by the DC furnace; is the feed water flow rate of the DC boiler; is the main steam enthalpy of the once-through boiler; is the feed water enthalpy of the direct current furnace; The steam enthalpy change equation is specifically: in, is the change in steam enthalpy; is the intermediate parameter, ; is the change in feed water flow rate of the DC boiler.

3. The quantitative analysis method of the effect of feedwater flow disturbance on steam pressure and steam temperature according to claim 2, characterized in that: The steam temperature variation equation is specifically: in, is the steam temperature change; is the change in steam enthalpy; is the isobaric specific heat of the working fluid; is the extraordinary coefficient, ; is the steam pressure change; The formula for the reduced temperature of the steam before the turbine regulating valve is specifically: in, To adjust the reduced temperature of steam before the valve of the steam turbine; Adjust the steam temperature before the steam valve for the steam turbine; Adjust the steam pressure before the steam turbine valve, which is equal to the steam pressure at the outlet of the direct current boiler; is the first coefficient, ; is the second coefficient, ; Subscript 0 indicates the operating parameters of the DC furnace in steady state.

4. The quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature according to claim 3, characterized in that: The approximate formula for the critical feedwater flow rate of the steam turbine is specifically: in, is the flow coefficient.

5. The quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature according to claim 4, characterized in that: The water flow disturbance equation is specifically: in, is the water flow disturbance; Adjust the steam pressure change before the steam valve for the steam turbine; Adjust the change of steam temperature before the steam valve of the steam turbine.

6. The quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature according to claim 5, characterized in that: The first quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the outlet of the direct current boiler is: in, To adjust the isobaric specific heat before the steam valve of the steam turbine.

7. The quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature according to claim 6, characterized in that: The second quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the outlet of the direct current boiler is specifically: in, is the third coefficient, .

8. The quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature according to claim 7, characterized in that: The third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the direct current boiler is: in, is the change in steam pressure at the middle point of the DC furnace.

9. A quantitative analysis method for the effect of feedwater flow disturbance on steam pressure and steam temperature according to claim 8, characterized in that: The third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the direct current boiler is: in, is the steam temperature variation at the middle point of the DC furnace; is the constant pressure specific heat of steam at the intermediate point of the direct current furnace; is the water feed enthalpy value at the midpoint; the subscript cer indicates the parameter of the midpoint.

10. A quantitative analysis system for the effect of feedwater flow disturbance on steam pressure and steam temperature, characterized in that: include: The first module is used to establish an energy balance equation based on the energy balance principle, introduce the equivalent relationship between feedwater flow and steam flow, and derive the steam enthalpy change equation through differential increment. The steam enthalpy is processed as a temperature-pressure function and the steam temperature change equation is derived through differential increment. The reduced temperature formula of the steam before the turbine regulating valve is constructed, and combined with the turbine critical operating flow approximate formula, the feedwater flow disturbance equation is derived through differential increment. The second module is used to simultaneously establish the steam enthalpy change equation, the steam temperature change equation, and the feedwater flow disturbance equation. After derivation and simplification, the first quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the outlet of the DC boiler and the second quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the outlet of the DC boiler are obtained. The third module is used to analyze the pressure change transmission characteristics caused by the feedwater flow disturbance. By combining the first quantitative calculation formula and the second quantitative calculation formula, a third quantitative calculation formula for the effect of the feedwater flow disturbance on the steam temperature at the midpoint of the DC boiler and a fourth quantitative calculation formula for the effect of the feedwater flow disturbance on the steam pressure at the midpoint of the DC boiler are derived. The fourth module is used to collect unit operation data and implement quantitative analysis by combining the first quantitative calculation formula, the second quantitative calculation formula, the third quantitative calculation formula and the fourth quantitative calculation formula.

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