Thermal power generating unit output quantitative analysis method based on auxiliary machine operation state

Abstract

The invention discloses a thermal power generating unit output quantitative analysis method based on an auxiliary machine operation state, and belongs to the field of coal power unit performance state monitoring and diagnosis, and the method comprises the following steps: calculating the coal grinding output variation based on the air volume change of a primary fan; calculating a main steam flow variable quantity based on the coal grinding output variable quantity and the boiler efficiency variable quantity; calculating the power generation power variation of the unit based on the main steam flow variation and the steam ratio internal work variation of the steam turbine; wherein the boiler efficiency variable quantity is calculated through the exhaust gas temperature variable quantity caused by the change of the air volume of a primary air fan, and the steam ratio internal work variable quantity of the steam turbine is calculated through steam parameters of the steam turbine after the air volume of the primary air fan is changed.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired power unit performance status monitoring and diagnosis technology, and particularly relates to a method for quantitative analysis of power output of thermal power units based on the operating status of auxiliary equipment. Background Technology

[0002] Coal mills and fans are important auxiliary equipment in boilers, and the operational reliability of these auxiliary equipment has a significant impact on the output of coal-fired power plants. For example, a decrease in the efficiency of the primary air fan reduces the amount of air fed into the coal mill, which, given a fixed air-to-coal ratio, affects the amount of fuel supplied to the boiler. Furthermore, a decrease in primary air fan efficiency leads to a reduction in the amount of air supplied to the air preheater, affecting the boiler's flue gas temperature and thermal efficiency, which in turn affects the overall boiler thermal efficiency. However, there is currently no quantitative method to assess the impact of reduced primary air fan efficiency on the output of coal-fired power units. Therefore, this invention proposes a quantitative analysis method for the output of thermal power units based on the operating status of auxiliary equipment. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a quantitative analysis method for thermal power unit output based on auxiliary machine operating status, thereby resolving the issues present in the prior art.

[0004] To achieve the above objectives, the present invention provides a method for quantitative analysis of thermal power unit output based on auxiliary equipment status, comprising: Calculate the change in coal mill output based on the change in primary fan air volume; The change in main steam flow rate is calculated based on the changes in coal mill output and boiler efficiency. The change in main steam flow rate and the change in turbine steam specific internal work are used to calculate the change in generator power; wherein, the change in boiler efficiency is calculated by the change in flue gas temperature caused by the change in primary air fan flow rate, and the change in turbine steam specific internal work is calculated by the turbine steam parameters after the change in primary air fan flow rate.

[0005] Optionally, the process of calculating the change in coal mill output includes: obtaining the change in coal mill output by differentiating the functional relationship between the change in coal mill output and the total air volume of the primary air blower; The calculation expression for the change in coal mill output is as follows: ; In the formula, This represents the change in coal mill output, expressed in t / h. This represents the change in coal mill output when the primary blower air volume changes by one unit. This represents the volumetric change in the total air volume of the primary air fan, expressed in cubic meters (m³). 3 / h.

[0006] Optionally, the process of calculating the change in main steam flow includes: using the full differential of the functional relationship between main steam flow and coal mill output and boiler efficiency to obtain the change in main steam flow; The expression for calculating the change in main steam flow rate is as follows: ; In the formula, This refers to the change in main steam flow rate for every unit change in coal mill output; This represents the unit change in coal mill output, expressed in t / h. This represents the change in main steam flow rate for each unit change in boiler efficiency. The change in boiler efficiency is expressed as % . This refers to the unit change in the main steam flow rate.

[0007] Optionally, the process of calculating the change in the power generation of the computer unit includes: based on the change in the main steam flow rate and the change in the steam specific internal work of the turbine, the change in the power generation of the unit is obtained by full differential processing of the functional relationship between the power generation and the main steam flow rate and the steam specific internal work of the turbine. The expression for the change in the power generation of the computer group is as follows: ; In the formula, The change in the effective power of the generator set when the main steam flow rate changes by a unit amount; The unit change in main steam flow rate, expressed in t / h; This represents the change in the effective power of the generator set when the power coefficient inside the steam turbine changes by a unit amount. This represents the unit change in the power coefficient within the steam turbine; This represents the change in the generating power of the unit.

[0008] Optionally, the process of calculating the boiler efficiency change includes: processing the boiler efficiency change based on the flue gas temperature change using the boiler thermal efficiency inverse balance calculation equation.

[0009] Optionally, the process of calculating the change in exhaust gas temperature includes: processing the change in the total air volume of the primary air fan using a heat balance equation to obtain the change in exhaust gas temperature; The expression for calculating the change in flue gas temperature is as follows: ; In the formula, The mass flow rate of exhaust gas is expressed in kg / s. The total mass flow rate of the wind is expressed in kg / s. Specific heat at constant pressure of air, expressed in kJ / (kg·℃); The outlet temperature of the primary air is expressed in °C. This refers to the ambient temperature, expressed in °C. This refers to the change in flue gas temperature. This refers to the specific heat capacity of the flue gas at constant pressure, expressed in kJ / (kg·℃).

[0010] Optionally, the process of calculating the change in the steam turbine specific internal work includes: calculating the steam turbine specific internal work using the steam parameters after the change in the primary fan air volume, and obtaining the change in the steam turbine specific internal work by subtracting the steam turbine specific internal work from the steam turbine specific internal work before the change.

[0011] Compared with the prior art, the present invention has the following advantages and technical effects: This invention discloses a quantitative analysis method for thermal power unit output based on auxiliary equipment operating status. By establishing a quantitative correlation model between primary air fan volume changes and coal mill output, boiler efficiency, and turbine steam parameters, it achieves a precise quantitative assessment of the impact of auxiliary equipment operating status on unit output. This method can accurately calculate the changes in coal mill output, flue gas temperature, boiler efficiency, and turbine steam specific work caused by a decrease in primary air fan efficiency or changes in air volume, ultimately deriving the specific numerical impact on power generation. Compared with traditional qualitative assessments, this method provides a scientific quantitative analysis tool, offering reliable data support for thermal power unit operation optimization, auxiliary equipment condition monitoring, and maintenance decisions, thus contributing to improved unit operation economy and reliability. Attached Figure Description

[0012] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram illustrating the algorithm principle for solving the unit change in power generation in an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the change in primary fan air volume according to an embodiment of the present invention; Figure 3 The flowchart below shows the algorithm for solving the unit change in power generation in an embodiment of the present invention. Detailed Implementation

[0013] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0014] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0015] Example 1 This invention addresses the impact of primary fan efficiency reduction on coal mill airflow, which in turn affects fuel consumption. Furthermore, this reduction leads to changes in air preheater airflow, ultimately impacting boiler flue gas temperature. The invention constructs a quantitative model of the influence of primary fan efficiency changes on the electrical load output of coal-fired power units. This invention further clarifies the quantitative assessment of the impact of auxiliary equipment operating conditions on the output of thermal power units, laying a significant theoretical foundation for accurately evaluating the influence of auxiliary equipment such as fans on the output of thermal power units.

[0016] To address the current difficulty in quantitatively determining the impact of reduced wind turbine efficiency on the power output of generating units, this invention proposes a quantitative analysis method for the power output of thermal power units based on the power balance formula and thermal balance principle of generator systems, combined with the law of conservation of energy.

[0017] The concept of a quantitative analysis method for thermal power unit output based on auxiliary machine operating status includes: 1. The change in unit power generation is influenced by the boiler-side characteristics. Specifically, the change is determined by the interlocking effects of the total primary air volume through the coal mill output and main steam flow, as well as the interlocking effects of flue gas temperature, flue gas heat loss, boiler efficiency, and main steam flow. Specifically, it is the change in coal mill output per unit change in the total primary air volume, combined with the change in main steam flow per unit change in coal mill output; and simultaneously, the change in flue gas temperature per unit change in the total primary air volume, combined with the change in flue gas heat loss per unit change in flue gas temperature. The changes in boiler efficiency and main steam flow rate, along with the changes in power generation per unit change in main steam flow rate, constitute the influence of this path. On the other hand, it is also affected by the turbine-side correlation characteristics. The turbine steam specific internal work, correlated with the primary air fan flow rate, determines another part of the power change through the correlation effect of exhaust enthalpy. That is, the change in exhaust enthalpy per unit change in turbine steam specific internal work, along with the changes in power generation per unit change in exhaust enthalpy, constitute the influence of this path.

[0018] 2. Based on the multipath decomposition equation of the unit's power generation change, the power generation change caused by the boiler-side path can be obtained by using the known change in the total primary air volume and the partial derivative parameters of each link (such as the partial derivative of the primary air volume on the coal mill output, the partial derivative of the flue gas heat loss on the boiler efficiency, etc.). The change in power generation caused by the turbine-side path can be obtained by using a functional relationship formed by parameters such as the rate of change of the turbine's steam specific internal work with respect to the exhaust enthalpy. This allows for further determination of changes in the primary airflow, such as... Figure 2 As shown, this represents the total change in the unit's power generation.

[0019] Based on the above concept, and based on the power balance formula and heat balance principle of the generator system, combined with the law of conservation of energy, this invention further proposes the principle followed in implementing the technical solution of this invention, namely: calculating the change in coal mill output based on the change in primary air fan volume; calculating the change in main steam flow based on the change in coal mill output and the change in boiler efficiency; calculating the change in generator power based on the change in main steam flow and the change in turbine steam specific internal work; wherein, the change in boiler efficiency is calculated by the change in flue gas temperature caused by the change in primary air fan volume, and the change in turbine steam specific internal work is calculated by the turbine steam parameters after the change in primary air fan volume. The specific implementation process includes: 1. Establish , and The functional relationship can be derived by taking the total differential to obtain the change in the unit's power generation. The changes in the total primary air volume cause changes in the coal mill output, which in turn cause changes in the main steam flow; changes in flue gas temperature cause changes in flue gas heat loss, which in turn cause changes in boiler efficiency, which in turn cause changes in the main steam flow. The combination of these factors leads to... Change, represented as .

[0020] 2. The change in the total air volume of the primary blower affects the steam specific internal work of the turbine, thereby influencing... The change is represented as .

[0021] 3. Combining the change in main steam flow rate caused by the change in the total air volume of the primary fan with the change in the steam specific internal work of the turbine, we get the change in power generation under the condition of a change in the total air volume of the primary fan.

[0022] The present invention provides a quantitative analysis method for the output of thermal power units based on the operating status of auxiliary equipment. This method combines the power balance formula, heat balance principle and energy conservation law of the power generation system to establish a quantitative analysis method for the output of thermal power units based on the operating status of auxiliary equipment.

[0023] like Figure 1 As shown, this embodiment provides a method for quantitative analysis of thermal power unit output based on auxiliary machine operating status, including the following steps: Assuming the primary air volume of fan A changes while the primary air volume of fan B remains constant, the power balance formula for the generator system based on the law of conservation of energy is as follows: (1) In the formula, The power output of the steam turbine is expressed in kW. Main steam flow rate, t / h; The specific internal work of the steam turbine is given by kJ / kg. The mechanical efficiency of the steam turbine is taken as 0.99; The efficiency of the generator is taken as 0.98.

[0024] Therefore, the effective power of the generator set can be obtained as follows: (2) in, (3) In the formula, Main vapor enthalpy, kJ / kg; The reheat steam coefficient; Enthalpy rise of reheated steam, kJ / kg; The sum of the extraction enthalpy of each stage of the steam turbine, kJ / kg; For the first The mass share of steam extracted at each stage; No. Enthalpy of staged extraction steam, kJ / kg; The extraction stage number is set to 8; The mass fraction of exhaust steam from the steam turbine; ν is the exhaust enthalpy of the steam turbine, in kJ / kg.

[0025] Taking the total differential of formula (2), the change in the effective power of the generator set is: (4) In the formula, The change in the effective power of the generator set when the main steam flow rate changes by a unit amount; The unit change in main steam flow rate, t / h; This represents the change in the effective power of the generator set when the power coefficient inside the steam turbine changes by a unit amount. This represents the unit change in the power coefficient within the steam turbine.

[0026] The change in effective power of the generator set for each unit change in main steam flow is: (5) For every unit change in the turbine's internal power coefficient, the change in the generator set's effective power is: (6) (a) The change in power generation for each unit change in main steam flow rate is: (7) The energy balance equation for a boiler thermal system, based on the law of conservation of energy, is as follows: (8) Therefore, the main steam flow rate is: (9) In the formula, For coal mill output, t / h; The lower heating value of the fuel is given by the received basis, in kJ / kg. Boiler efficiency, % Main vapor enthalpy, kJ / kg; Enthalpy of water supply, kJ / kg; Reheat steam flow rate, t / h; Enthalpy of reheated steam outlet ; Enthalpy of reheated steam inlet, kJ / kg.

[0027] Taking the total differential of formula (9), we can obtain the unit change in main steam flow rate under the influence of coal mill output and boiler efficiency as follows: (10) In the formula, This refers to the change in main steam flow rate for every unit change in coal mill output; The unit change in coal mill output is expressed in t / h. This represents the change in main steam flow rate for each unit change in boiler efficiency. Let be the change in boiler efficiency.

[0028] Specifically, the change in main steam flow rate for each unit change in coal mill output is: (11) Therefore, the change in main steam flow rate caused by the change in coal mill output is: (12) The change in main steam flow rate for each unit change in boiler efficiency is: (13) Therefore, the change in main steam flow caused by the change in boiler efficiency is: (14) The equation for calculating the air volume flow rate in a fuel combustion system is as follows: (15) In the formula, The total air volume of the primary fan, in m 3 / h; Air density at ambient temperature, kg / m³ 3 ; The ratio of air to coal is expressed in kg / kg.

[0029] in, (16) In the formula, The air volume of the primary air fan on side A is in meters. 3 / h; The air volume of the primary air fan on side B, in meters. 3 / h.

[0030] Therefore, the output of the coal mill can be obtained as follows: (17) Taking the total differential of formula (17), the change in the coal mill's output is: (18) In the formula, The change in coal mill output is expressed in t / h. This represents the change in coal mill output when the primary blower air volume changes by one unit. The volumetric change in the total air volume of the primary fan (m) 3 / h.

[0031] Therefore, the change in the total air volume of the primary fan can be obtained as follows: (19) In the formula, The volumetric flow rate of the primary air fan on side A after the change, in m 3 / h; The air volume of the primary air fan on side A before the change, in meters. 3 / h.

[0032] The equation for calculating the air volume of the primary air fan on side A, based on the law of conservation of energy, is as follows: (20) In the formula, This is the adjusted compression correction factor for the blower. The changed total pressure of the fan, in Pa; The changed total pressure efficiency of the fan is % This represents the changed fan shaft power.

[0033] Therefore, the air volume of the primary fan on side A after the change is: (twenty one) The modified fan compression correction factor is: (twenty two) In the formula, The changed total pressure of the incompressible gas blower, Pa; The absolute pressure at the fan inlet, in Pa; The air insulation index. .

[0034] The changed total pressure of the incompressible gas blower is: (twenty three) In the formula, The original compression correction factor for the blower; The total pressure of the fan before the change, in Pa; The density of the medium at the fan inlet before the fan change is expressed in kg / m³. 3 ; The density of the medium at the fan inlet after the fan has changed is expressed in kg / m³. 3 ; The fan speed after the change is expressed in r / min; The fan speed before the change is expressed in r / min. The outer diameter of the impeller after the change in the fan, in meters (m); The impeller outer diameter before the fan change is in meters (m).

[0035] The changed total pressure of the fan is: (twenty four) The changed shaft power of the fan is: (25) Based on the principle of heat balance, the following inverse balance calculation equation for boiler thermal efficiency is constructed: (26) In the formula, For flue gas heat loss, % For heat loss due to incomplete chemical combustion, % For heat loss due to incomplete combustion of machinery, % For heat dissipation loss, % The physical sensible heat loss of ash and slag is %.

[0036] therefore, (27) Therefore, the change in boiler efficiency is: (28) In the formula, This represents the change in boiler efficiency. The change in boiler efficiency per unit change in flue gas heat loss; This represents the change in flue gas heat loss. This represents the change in flue gas heat loss for each unit change in flue gas temperature. The value represents the change in flue gas temperature, expressed in °C.

[0037] Since the heat loss from flue gas can be expressed by formula (29): (29) In the formula, The correction factor, which represents the coal type, can be approximated as 2.63; Excess air coefficient; is the specific heat at constant pressure of flue gas, kJ / (kg·℃); The exhaust gas temperature is ℃; The actual ambient temperature is expressed in °C.

[0038] therefore, (30) Based on the law of conservation of energy, the heat balance equation is: (31) In the formula, The mass flow rate of the exhaust gas is kg / s; The total mass flow rate of primary air is expressed in kg / s. The specific heat capacity at constant pressure of the flue gas is kJ / (kg·℃). The exhaust gas temperature is ℃; The inlet flue gas temperature of the air preheater, in °C; is the specific heat at constant pressure of air, kJ / (kg·℃); The outlet temperature of the primary air, in °C; The ambient temperature is in °C.

[0039] Therefore, the change in flue gas temperature can be obtained as follows: (32) (b) The change in the effective power of the generator set for each unit change in the internal work of the steam turbine steam ratio is: (33) in, (34) Therefore, the unit change in the effective power of the generator set can be obtained as: (35) As a specific implementation method of this embodiment, such as Figure 3 As shown in Table 1, this invention takes a 300MW thermal power unit as an example, and the specific parameters are shown in Table 1.

[0040] Table 1

[0041] The total pressure of the incompressible gas blower is: The revised compression correction factor for the blower is: The changed total pressure of the fan is: The changed shaft power of the fan is: Therefore, the air volume of the primary fan on side A after the change is: Therefore, the change in the total air volume of the primary air fan is: Therefore, the change in coal mill output is: The main steam flow rate is: The change in main steam flow rate caused by the change in coal mill output is: The total air volume of the fan after the change is: The change in flue gas temperature is: Therefore, when the flue gas temperature changes, the change in flue gas heat loss is: Therefore, the change in boiler efficiency is: The change in main steam flow rate due to boiler efficiency is: Therefore, the change in main steam flow rate is: The changed steam specific internal work is: therefore, therefore, therefore therefore, The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for quantitative analysis of power output of a thermal power generating unit based on operating states of auxiliary machines, characterized in that, The method comprises the following steps: calculating the change of the coal grinding output based on the change of the primary air flow; calculating the change of the main steam flow based on the change of the coal grinding output and the change of the boiler efficiency, wherein the change of the boiler efficiency is calculated based on the change of the exhaust gas temperature caused by the change of the primary air flow, and the change of the steam ratio internal work of the steam turbine is calculated based on the steam parameters of the steam turbine after the change of the primary air flow; calculating the change of the power generation of the unit based on the change of the main steam flow and the change of the steam ratio internal work of the steam turbine, wherein the change of the power generation of the unit is calculated based on the full differential of the function relationship between the power generation and the main steam flow and the steam ratio internal work of the steam turbine.

2. The method for quantitative analysis of the output of a thermal power generating unit based on the operating state of auxiliary machinery according to claim 1, characterized in that, The process of calculating the change of the coal grinding output comprises: obtaining the change of the coal grinding output by differentiating the function relationship between the change of the coal grinding output and the total primary air flow; The calculation expression of the change of the coal grinding output is: ； In the formula, is the change amount of the coal mill output, in t / h; is the change amount of the coal mill output when the air volume of the primary air fan changes by one unit; is the volume change amount of the total air volume of the primary air fan, in m 3 / h.

3. The method for quantitative analysis of the output of a thermal power generating unit based on the operating state of auxiliary machinery according to claim 1, characterized in that, The process of calculating the change of the main steam flow comprises: obtaining the change of the main steam flow by fully differentiating the function relationship between the main steam flow and the coal grinding output and the boiler efficiency; The calculation expression of the change of the main steam flow is: ； In the formula, is the change in main steam flow per unit change in coal mill output; is the unit change in coal mill output, in t / h; is the change in main steam flow per unit change in boiler efficiency; is the change in boiler efficiency, in %; is the unit change in main steam flow.

4. The method for quantitative analysis of the output of a thermal power generating unit based on the operating state of auxiliary machinery according to claim 1, characterized in that, The process of calculating the change of the power generation of the unit comprises: obtaining the change of the power generation of the unit by fully differentiating the function relationship between the power generation and the main steam flow and the steam ratio internal work of the steam turbine based on the change of the main steam flow and the change of the steam ratio internal work of the steam turbine; The calculation expression of the change of the power generation of the unit is: ； In the formula, is the change in the effective power of the generator unit per unit change in the main steam flow; is the unit change in the main steam flow, in t / h; is the change in the effective power of the generator unit per unit change in the power coefficient in the steam turbine; is the unit change in the power coefficient in the steam turbine; is the change in the power of the generator unit.

5. The method for quantitative analysis of the output of a thermal power generating unit based on the operating state of auxiliary machinery according to claim 1, characterized in that, The process of calculating the change of the boiler efficiency comprises: obtaining the change of the boiler efficiency by processing the inverse balance calculation equation of the boiler thermal efficiency based on the change of the exhaust gas temperature.

6. The method for quantitative analysis of the output of a thermal power generating unit based on the operating state of auxiliary machinery according to claim 5, characterized in that, The process of calculating the change of the exhaust gas temperature comprises: obtaining the change of the exhaust gas temperature by processing the total primary air flow based on the heat balance equation; The calculation expression of the change of the exhaust gas temperature is: ； In the formula, is the exhaust gas mass flow rate, in kg / s; is the total air mass flow rate, in kg / s; is the specific heat capacity of air at constant pressure, in kJ / (kg·℃); is the primary air outlet temperature, in ℃; is the ambient temperature, in ℃; is the exhaust gas temperature change amount; is the specific heat capacity of exhaust gas at constant pressure, in kJ / (kg·℃).

7. The method for quantitative analysis of the output of a thermal power generating unit based on the operating state of auxiliary machinery according to claim 1, characterized in that, The process of calculating the change of the steam ratio internal work of the steam turbine comprises: obtaining the steam ratio internal work of the steam turbine after the change of the primary air flow, and obtaining the change of the steam ratio internal work of the steam turbine by subtracting the steam ratio internal work of the steam turbine before the change from the steam ratio internal work of the steam turbine after the change.

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