Method for evaluating heat consumption characteristics of a cogeneration unit

Abstract

本申请提出一种评价热电联产机组能耗特性的方法，包括将汽轮机组和锅炉调整到待测定热耗的工况A，高压给水的流量为q1s1，发电机组功率为Ps1，抽汽处的对外抽汽量为q5s1，乏汽的出口压力为p6s1，冷凝液的温度为t7s1计算锅炉内水侧吸热量Qs1；工况B中保持q5s1，p6s1，t7s1调整高压给水的流量为q1s1+Δq，发电机组功率为Ps1+ΔP，锅炉内水侧吸热量为Qs2，发电机组热耗Ls2；工况C中保持q5s1，p6s1，t7s1调整高压给水的流量为q1s1‑Δq，发电机组功率为Ps1‑ΔP，锅炉内水侧吸热量为Qs3，发电机组热耗Ls3；工况A下热电联产机组热耗为L＝(Ls2+Ls3) / 2。

Description

Technical Field

[0001] This application relates to the field of thermal power generation technology, and in particular to a method for evaluating the heat consumption characteristics of combined heat and power units. Background Technology

[0002] Combined heat and power (CHP) technology refers to a thermal power generating unit that simultaneously outputs electrical energy and heat energy. Specifically, high-temperature, high-pressure steam first drives a turbine to output useful work, and then the low-pressure steam is used for external heating, fully utilizing the latent heat of steam and reducing cold source losses. CHP is an excellent energy-saving technology for achieving cascaded energy utilization, possessing high overall energy efficiency. Currently, heating steam extraction from coal-fired units, industrial steam extraction, and back-pressure turbines all fall under the category of CHP, with a very wide range of applications.

[0003] Cogeneration (CHP) technology enables the cascade utilization of steam heat energy. A portion of the heat energy is converted into useful work or electricity, while the majority is directly output as heat. However, electricity and heat are two different forms of energy and cannot be directly compared quantitatively. This has led to considerable controversy regarding the heat consumption evaluation of CHP units, with two diametrically opposed evaluation methods: "benefit attributed to electricity" and "benefit attributed to heat." The former converts all externally supplied heat into standard coal equivalent and directly subtracts this portion from the calculation of power generation coal consumption, resulting in an underestimation of power generation coal consumption, which is particularly noticeable when the steam extraction rate is high. The latter considers steam waste heat as an additional byproduct of power generation, representing extra revenue and having no impact on the original coal consumption calculation of thermal power units. This results in an overestimation of power generation coal consumption, which is more pronounced with higher extraction steam pressure and larger extraction rates. Overall, the "benefit attributed to electricity" method overestimates the power generation capacity of extracted steam, while the "benefit attributed to heat" method ignores the power generation capacity of extracted steam. Both methods have their drawbacks. Currently, the "benefit attributed to electricity" method is more widely used, which means that the calculated coal consumption value can no longer reflect the true thermal performance of the generator unit. The coal consumption of cogeneration units is significantly lower than that of pure condensing units, but this does not prove their superiority. At present, there is a lack of methods that can objectively evaluate the heat consumption characteristics of cogeneration units. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art.

[0005] Therefore, the purpose of this application is to propose a method for evaluating the energy consumption characteristics of combined heat and power (CHP) units, comprising the following steps:

[0006] Multiple steam performance measurement points are set up within the combined heat and power (CHP) unit; the CHP unit includes a boiler, a turbine unit, and a generator unit; high-pressure feedwater enters the boiler to generate high-temperature main steam, which then enters the turbine unit to drive the generator unit to generate electricity; the exhaust steam from the turbine unit is cooled to condensate, which is then pressurized and heated before being transported to the boiler; each steam performance measurement point includes at least the measurement of temperature and pressure data, and some of the steam performance measurement points also include the measurement of flow rate data.

[0007] The steam transmission pipeline within the turbine unit forms an extraction boundary, and an extraction point is set on the extraction boundary. The turbine unit and the boiler are adjusted to operating condition A, where the heat consumption to be measured is under operating condition A. Under operating condition A, the flow rate of high-pressure feedwater is q1. s1 The generator set has a power of P. s1 The external steam extraction rate at the extraction point is q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7. s1 Calculate the heat absorption Q on the water side of the boiler. s1 ;

[0008] In operating condition B, the external steam extraction rate at the extraction point is maintained at q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7. s1 And adjust the flow rate q1 of the high-pressure water supply. s2 For q1 s1 +Δq, the power of the generator set increases to P s1 +ΔP, the heat absorption on the water side of the boiler is Q. s2 Calculate the heat consumption L of the generator set. s2 ;

[0009] In operating condition C, the external steam extraction rate at the extraction point is maintained at q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7. s1 Adjust the flow rate q1 of the high-pressure water supply in operating condition C. s3 For q1 s1 -Δq, the generator set power is reduced to P s1 -ΔP, the heat absorption on the water side of the boiler is Q. s3 Calculate the heat consumption L of the generator set. s3 ;

[0010] Under operating condition A, the heat consumption of the combined heat and power (CHP) unit is L, where the value of L is inversely related to the thermodynamic performance of the CHP unit, and the calculation formula for the heat consumption L of the CHP unit is as follows: L = (L s2 +L s3) / 2.

[0011] In some embodiments, the turbine unit includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder respectively connected to the generator unit; high-pressure feedwater enters the boiler to generate high-temperature main steam; the high-temperature main steam enters the high-pressure cylinder and performs work to generate cold reheat steam, which is then fed into the boiler to form reheat steam; the reheat steam is fed into the intermediate-pressure cylinder and performs work before flowing into the low-pressure cylinder to perform work; the exhaust steam after performing work in the low-pressure cylinder is cooled into condensate, which is then pressurized and heated before being sent to the boiler.

[0012] In some embodiments, the cogeneration unit further includes auxiliary components; the auxiliary components include a condenser, a condensate pump and a regenerator connected in sequence according to the flow direction of the exhaust steam output from the low-pressure cylinder, for cooling the exhaust steam into the condensate, and generating the high-pressure feedwater after pressurization and heating and then supplying it to the boiler.

[0013] In some embodiments, multiple steam performance measurement points are respectively distributed at the high-pressure feedwater inlet, the high-temperature main steam outlet, the cold reheat steam inlet, and the reheat steam outlet of the boiler; as well as at the extraction steam outlet, the low-pressure cylinder outlet, and the condenser outlet.

[0014] In some embodiments, the flow rate data measured at the steam performance measuring points of the high-pressure feedwater inlet and / or the high-temperature main steam outlet; the flow rate data measured at the steam performance measuring points of the cold reheat steam inlet and / or the reheat steam outlet; and the flow rate data measured at the steam performance measuring points of the extraction steam outlet.

[0015] In some embodiments, where Q s1 The calculation formula is as follows:

[0016] Q s1 =[q1*(h2-h1)+q3*(h4-h3)] s1 ;

[0017] Where q1 s1 q3 represents the flow rate of high-pressure water supply under operating condition A, in kg / s. s1 The cold resteam flow rate under operating condition A is kg / s; h1 s1 The enthalpy of the high-pressure water supply under operating condition A is expressed in kJ / kg; h2 s1 The enthalpy of the high-temperature main steam under operating condition A is expressed in kJ / kg; h3 s1 The enthalpy of the cold revapor under operating condition A is expressed in kJ / kg; h⁴ s1 The enthalpy of the reheat steam under operating condition A is expressed in kJ / kg.

[0018] In some embodiments, the combined heat and power unit operates under condition B Q s2 The calculation formula is as follows:

[0019] Q s2 =[q1*(h2-h1)+q3*(h4-h3)] s2 ;

[0020] Where q1 s2 q3 represents the flow rate of high-pressure water supply under operating condition B, in kg / s. s2 The cold resteam flow rate under operating condition B is kg / s; h1 s2 The enthalpy of the high-pressure water supply under operating condition B is expressed in kJ / kg; h2 s2 The enthalpy of the high-temperature main steam under operating condition B is given in kJ / kg; h3 s2 The enthalpy of the cold revapor described under operating condition B is expressed in kJ / kg; h⁴ s2 The enthalpy of the reheat steam under operating condition B is expressed in kJ / kg.

[0021] In some embodiments, the heat consumption L of the generator set under the combined heat and power unit operating condition B is... s2 The calculation formula is as follows:

[0022] L s2 =(Q s2 -Q s1 )*3.6 / ΔP / ζ;

[0023] ζ=1+(h5 s2 -h5 s1 ) / (h5 s1 -h6 s1 );

[0024] Wherein, the L s2 The unit is kJ / (kW.h); ΔP is the increase in generator power (MW) after increasing the flow rate of the high-pressure feedwater under operating condition A by Δq; h5 s2 The steam enthalpy at the extraction point under operating condition B is expressed in kJ / kg; h5 s1 h6 s1 These are the steam enthalpy at the extraction point and the exhaust steam enthalpy, respectively, under operating condition A, in kJ / kg.

[0025] In some embodiments, the combined heat and power unit operates under condition CQ s3 The calculation formula is as follows:

[0026] Q s3 =[q1*(h2-h1)+q3*(h4-h3)] s3 ;

[0027] Where q1 s3 q3 represents the flow rate of high-pressure water supply under operating condition C, in kg / s. s3The cold resteam flow rate under operating condition C is kg / s; h1 s3 The enthalpy of the high-pressure feedwater under operating condition C is expressed in kJ / kg; h2 s3 The enthalpy of the high-temperature main steam under operating condition C is expressed in kJ / kg; h3 s3 The enthalpy of the cold revapor under operating condition C is given in kJ / kg; h⁴ s3 The enthalpy of the reheat steam under operating condition C is expressed in kJ / kg.

[0028] In some embodiments, the heat consumption L of the generator set under the combined heat and power unit operating condition C s3 The calculation formula is as follows:

[0029] L s3 =(Q s1 -Q s3 )*3.6 / ΔP / ζ;

[0030] ζ=1+(h5 s3 -h5 s1 ) / (h5 s1 -h6 s1 );

[0031] Wherein, the L s3 The unit is kJ / (kW·h); ΔP is the power reduction of the generator set after reducing the flow rate of the high-pressure feedwater under operating condition A by Δq, in MW; h5 s3 The steam enthalpy at the extraction point under operating condition C is expressed in kJ / kg; h5 s1 h6 s1 These are the steam enthalpy at the extraction point and the exhaust steam enthalpy, respectively, under operating condition A, in kJ / kg.

[0032] Compared with the prior art, this application has the following advantages: This application overcomes the defects of the existing cogeneration unit heat consumption calculation method, eliminates the influence of parameters such as extraction steam volume and extraction steam pressure on heat consumption calculation, and this method can more objectively evaluate the thermal performance of cogeneration units and provide data support for energy saving and consumption reduction of units.

[0033] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0034] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 This is a schematic diagram of the structure of a combined heat and power unit according to an embodiment of this application;

[0036] Figure 2 This is a schematic diagram of the structure of a combined heat and power unit according to an embodiment of this application;

[0037] Figure 3 This is a schematic diagram of the structure of a combined heat and power unit according to an embodiment of this application;

[0038] Figure 4 This is a flowchart of a method for evaluating the energy consumption characteristics of a combined heat and power unit proposed in an embodiment of this application.

[0039] In the diagram, 1-7 are steam performance measurement points; 8 is power measurement point; 9 is boiler; 10 is high-pressure cylinder; 11 is medium-pressure cylinder; 12 is low-pressure cylinder; 13 is condenser; 14 is generator set; 15 is steam user; 16 is condensate pump; 17 is control valve group; and 18 is extraction steam boundary. Detailed Implementation

[0040] Embodiments of this application are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0041] See Figure 1 To achieve the above objectives, this application proposes a method for evaluating the energy consumption characteristics of combined heat and power (CHP) units, comprising the following steps:

[0042] S0: Multiple steam performance measurement points are set up in the cogeneration unit; the cogeneration unit includes a boiler 9, a turbine unit and a generator unit 14; high-pressure feedwater enters the boiler 9 to generate high-temperature main steam, which then enters the turbine unit to do work and drive the generator unit 14 to generate electricity; the exhaust steam after the turbine unit does work is cooled into condensate, which is then pumped to the boiler 9 after being pressurized and heated; all steam performance measurement points include at least the measurement of temperature and pressure data, and some steam performance measurement points also include the measurement of flow rate data.

[0043] S1: The steam transmission pipeline within the turbine unit forms an extraction boundary 18. An extraction point is set on the extraction boundary 18. The turbine unit and boiler 9 are adjusted to operating condition A, where the heat consumption to be measured is to be determined. Under operating condition A, the flow rate of high-pressure feedwater is q1. s1 The power of generator set 14 is P s1 The external steam extraction rate at the extraction point is q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7 s1 Calculate the heat absorption Q on the water side of boiler 9. s1 ;

[0044] S2: In operating condition B, the external steam extraction rate at the extraction point is maintained at q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7 s1 And adjust the flow rate q1 of the high-pressure water supply. s2 For q1 s1 +Δq, the power of generator set 14 increases to P s1 +ΔP, the heat absorption on the water side of boiler 9 is Q. s2 Calculate the heat consumption of generator set 14 L. s2 ;

[0045] Under operating condition C, the external steam extraction rate at the extraction point is maintained at q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7 s1 Adjust the flow rate q1 of the high-pressure water supply in operating condition C. s3 For q1 s1 -Δq, generator set 14 power reduced to P s1 -ΔP, the heat absorption on the water side of boiler 9 is Q. s3 Calculate the heat consumption of generator set 14 L. s3 ;

[0046] S3: The heat consumption of the cogeneration unit under operating condition A is L, where the value of L is inversely related to the thermodynamic performance of the cogeneration unit, and the calculation formula for the heat consumption L of the cogeneration unit is as follows:

[0047] L=(L s2 +L s3 ) / 2.

[0048] One system for improving the load response speed of a combined heat and power (CHP) unit includes a boiler 9, a turbine unit, and a generator set 14. High-pressure feedwater enters the boiler 9 to generate high-temperature main steam, which then enters the turbine unit to drive the generator set 14 to generate electricity. The exhaust steam from the turbine unit after it has done work is cooled into condensate, which is then pressurized and heated before being transported back to the boiler 9. The turbine unit includes a high-pressure cylinder 10, an intermediate-pressure cylinder 11, and a low-pressure cylinder 12, which are respectively connected to the generator set 14. The high-temperature main steam enters the high-pressure cylinder 10 to generate cold reheat steam, which is then fed into the boiler 9 to form reheat steam. The reheat steam is fed into the intermediate-pressure cylinder 11, and the outlet steam of the intermediate-pressure cylinder 11 is connected to the low-pressure cylinder 12.

[0049] In other words, the cogeneration unit in this embodiment is an existing cogeneration unit in the art, including a boiler 9, a steam turbine unit and a generator set 14; the steam turbine unit includes a high-pressure cylinder 10, a medium-pressure cylinder 11 and a low-pressure cylinder 12 respectively connected to the generator set 14, and the steam generated by the boiler 9 enters the high-pressure cylinder 10, the medium-pressure cylinder 11 and the low-pressure cylinder 12 to do work and drive the generator set 14 to generate electricity. In this embodiment, high-pressure feedwater enters the boiler 9 through the inlet of the boiler 9 to absorb heat and generate high-temperature main steam. The boiler 9 includes a first outlet for outputting high-temperature main steam. The first outlet of the boiler 9 is connected to the inlet of the high-pressure cylinder 10. After the high-temperature main steam enters the high-pressure cylinder 10 and performs work, it discharges cold reheat steam. The outlet of the high-pressure cylinder 10 is connected to the air inlet of the boiler 9, which transports the cold reheat steam into the boiler 9 to absorb heat and form reheat steam. The reheat steam is output through the second outlet of the boiler 9. The second outlet of the boiler 9 is connected to the inlet of the intermediate-pressure cylinder 11. The steam from the outlet of the intermediate-pressure cylinder 11 enters the inlet of the low-pressure cylinder 12 through its outlet. The exhaust steam from the low-pressure cylinder 12 after performing work is output and is cooled into condensate by an auxiliary component connected to the outlet of the low-pressure cylinder 12. After being pressurized and heated, the condensate is generated and transported to the boiler 9. The auxiliary components include a condenser 13, a condensate pump 16, and a regenerator connected in sequence according to the flow direction of the exhaust steam output from the low-pressure cylinder 12. After the exhaust steam is cooled and condensed into liquid by the condenser 13, it is pressurized by the condensate pump 16 and enters the regenerator to absorb heat and increase its temperature, and finally forms high-pressure feedwater that re-enters the boiler 9 to absorb heat.

[0050] In addition, the steam transmission pipeline in the steam turbine unit forms an extraction boundary 18, and an extraction point is set on the extraction boundary 18. A certain amount of steam is extracted through the extraction point and sent to the steam user 15 through the control valve group 17.

[0051] In step S0, in this embodiment, multiple steam performance measurement points are respectively distributed at the high-pressure feedwater inlet, high-temperature main steam outlet, cold reheat steam inlet and reheat steam outlet of boiler 9, extraction steam outlet, low-pressure cylinder 12 outlet and condenser 13 outlet.

[0052] The high-pressure feedwater inlet, high-temperature main steam outlet, cold reheat steam inlet, and reheat steam outlet are all located on the boiler, specifically the boiler's water inlet, first outlet, air inlet, and second outlet, respectively. In this application, the steam performance measuring points at the high-pressure feedwater inlet and / or high-temperature main steam outlet measure flow rate data; the steam performance measuring points at the cold reheat steam inlet and / or reheat steam outlet measure flow rate data; and the steam performance measuring point at the extraction steam outlet measures flow rate data. In other words, all steam performance measuring points can measure the temperature and pressure data of the steam at that location, but at least one steam performance measuring point at the high-pressure feedwater inlet and high-temperature main steam outlet can detect the flow rate data of the steam at that location; similarly, at least one steam performance measuring point at the cold reheat steam inlet and reheat steam outlet can detect the flow rate data of the steam at that location; furthermore, the steam performance measuring point at the extraction steam outlet can also measure flow rate data.

[0053] It should be noted that in this embodiment, the flow rate of high-pressure feedwater entering the boiler's high-pressure feedwater inlet is equal to the flow rate of high-temperature main steam output from the high-temperature main steam outlet; at the same time, the flow rate of cold reheat steam entering the cold reheat steam inlet is equal to the flow rate of reheat steam output from the reheat steam outlet.

[0054] For example, the temperature, pressure, enthalpy, and flow rate at each steam performance measuring point are represented by t, p, h, and q, respectively, with units of ℃, MPa, kJ / kg, and kg / s. Subscripts indicate the location of the measuring point, and superscripts indicate the data at that point in a specific step. For instance, the steam performance measuring points are numbered as follows: the high-pressure feedwater inlet of boiler 9 is numbered 1; the high-temperature main steam outlet of boiler 9 is numbered 2; the cold reheat steam inlet of boiler 9 is numbered 3; the reheat steam outlet of boiler 9 is numbered 4; the extraction steam point is numbered 5; the outlet of low-pressure cylinder 12 is numbered 6; and the outlet of condenser 13 is numbered 7. Additionally, a power measuring point 8 is set at the output terminal of generator set 14 and numbered 8, with power represented by P. The rated power output of the cogeneration unit is P. e The unit is MW. In the example, t1, p1, and q1 represent the temperature, pressure, and flow rate at measuring point 1, respectively. (t1, p1, q1) sn This represents the temperature, pressure, and flow rate data at measuring point 1 in step Sn; h(t1, p1) represents the specific enthalpy of water at measuring point 1, the value of which is obtained from the database based on the temperature and pressure. Other steam performance measuring points are similar and will not be elaborated further.

[0055] S1: Adjust the turbine unit and boiler 9 to operating condition A where heat consumption needs to be measured. At this time, the power of generator unit 14 is P. s1 The flow rate of the high-pressure water supply is q1 s1 The steam extraction rate at measuring point 5 is q5. s1 The temperature and pressure at measuring point 5 are t5. s1 p5 s1 The pressure at measuring point 6 is p6. s1 The temperature at measuring point 7 is t7. s1 The heat absorption Q on the water side of boiler 9 s1 The calculation formula is as follows:

[0056] Q s1 =[q1*(h2-h1)+q3*(h4-h3)] s1 ;

[0057] Among them, q1 s1 q3 represents the flow rate of high-pressure water supply under operating condition A, in kg / s. s1 The cold resteam flow rate under operating condition A is kg / s; h1 s1 The enthalpy of high-pressure feedwater under operating condition A is expressed in kJ / kg; h2 s1The enthalpy of the high-temperature main steam under operating condition A is expressed in kJ / kg; h3 s1 Here is the enthalpy of the cold reheat steam under operating condition A, in kJ / kg; h⁴ s1 Δ is the enthalpy of reheat steam under operating condition A, in kJ / kg.

[0058] S2: Under operating condition B, the extraction steam rate is kept constant at q5. s1 The pressure at measuring point 6 is p6. s1 The temperature at measuring point 7 is t7. s1 Increase the flow rate q1 of the high-pressure water supply s2 up to q1 s1 +Δq, where Δq is recommended to be taken within 3 to 5% of q0, and q0 is the high-temperature main steam flow rate of the cogeneration unit under rated operating conditions. As the high-temperature main steam flow rate increases, the generator unit's power increases to P14. s1 +ΔP, the heat absorption on the water side of boiler 9 is Q. s2 The calculation formula is as follows:

[0059] Q s2 =[q1*(h2-h1)+q3*(h4-h3)] s2 ;

[0060] Among them, q1 s2 q3 represents the flow rate of high-pressure water supply under operating condition B, in kg / s. s2 The cold resteam flow rate under operating condition B is kg / s; h1 s2 The enthalpy of the high-pressure feedwater under operating condition B is expressed in kJ / kg; h2 s2 The enthalpy of the high-temperature main steam under operating condition B is given in kJ / kg and h3. s2 The enthalpy of cold reheat steam under operating condition B, in kJ / kg; h⁴ s2 Δ is the enthalpy of reheat steam under operating condition B, in kJ / kg.

[0061] According to the above Q s1 and Q s2 Calculate the heat consumption (L) of generator set 14 s2 ;

[0062] L s2 The calculation formula is as follows:

[0063] L s2 =(Q s2 -Q s1 )*3.6 / ΔP / ζ;

[0064] ζ=1+(h5 s2 -h5 s1 ) / (h5 s1 -h6 s1 );

[0065] Among them, Ls2 The unit is kJ / (kW.h); ΔP is the power increase of generator set 14 after increasing the high-pressure feedwater flow rate by Δq under operating condition A, in MW; h5 s2 The steam enthalpy at the extraction point under operating condition B is expressed in kJ / kg; h5 s1 h6 s1 These are the steam enthalpy at the extraction point (kJ / kg) and the exhaust steam enthalpy (kJ / kg) under operating condition A, respectively.

[0066] S3: Ensure the extraction steam rate remains constant at q5 s1 The pressure at measuring point 6 is p6. s1 The temperature at measuring point 7 is t7. s1 Reduce the flow rate q1 of the high-pressure water supply s2 up to q1 s1 -Δq, Δq is recommended to be taken within 3-5% * q0, because the generator set power is reduced to P due to the decrease in main steam flow at high temperature. s1 -ΔP, the heat absorption on the water side of boiler 9 is Q. s3 The calculation formula is as follows:

[0067] Q s3 =[q1*(h2-h1)+q3*(h4-h3)] s3 ;

[0068] Where q1 s3 q3 represents the flow rate of high-pressure water supply under operating condition C, in kg / s. s3 The cold resteam flow rate under operating condition C is kg / s; h1 s3 The enthalpy of the high-pressure feedwater under operating condition C is expressed in kJ / kg; h2 s3 The enthalpy of the high-temperature main steam under operating condition C is given in kJ / kg and h3. s3 The enthalpy of cold reheat steam under operating condition C is given in kJ / kg; h⁴ s3 Δ is the enthalpy of reheat steam under operating condition C, in kJ / kg.

[0069] Calculate the heat consumption (L) of generator set 14 s3 =(Q s1 -Q s3 )*3.6 / ΔP / ζ, the unit is kJ / (kW.h), ζ=1+(h5) s3 -h5 s1 ) / (h5 s1 -h6 s1 ).

[0070] S4: The heat consumption of the combined heat and power unit under operating condition A is L = (L s2 +L s3The smaller the value, the better the thermal performance of the cogeneration unit. For cogeneration units with the same capacity but different extraction steam rates or extraction parameters, the heat consumption values ​​should be compared under the condition that the high-temperature main steam flow rate is basically equal. For cogeneration units with different capacities, the conversion factor should be calculated based on the heat consumption of the two under rated operating conditions, and then the heat consumption should be compared under the condition that the ratio of their respective high-temperature main steam flow rate to the flow rate under rated operating conditions is the same.

[0071] In some embodiments, the heat consumption L of generator set 14 under cogeneration unit operating condition C s3 The calculation formula is as follows:

[0072] L s3 =(Q s1 -Q s3 )*3.6 / ΔP / ζ;

[0073] ζ=1+(h5 s3 -h5 s1 ) / (h5 s1 -h6 s1 );

[0074] Among them, L s3 The unit is kJ / (kW.h); ΔP is the power reduction of generator set 14 after reducing the high-pressure feedwater flow rate by Δq under operating condition A, in MW; h5 s3 The steam enthalpy at the extraction point under operating condition C is expressed in kJ / kg; h5 s1 h6 s1 These are the steam enthalpy at the extraction point (kJ / kg) and the exhaust steam enthalpy (kJ / kg) under operating condition A, respectively.

[0075] A smaller L value indicates better thermal performance of a cogeneration unit under operating condition A. For cogeneration units with the same capacity but different extraction steam rates or parameters, the heat consumption values ​​should be compared under operating conditions where the high-temperature main steam flow rate is approximately equal. For cogeneration units with different capacities, a conversion factor should be calculated based on the heat consumption values ​​under rated operating conditions, and then the heat consumption values ​​should be compared under operating conditions where the ratio of each high-temperature main steam flow rate to the rated flow rate is the same. Therefore, this embodiment overcomes the shortcomings of existing cogeneration unit heat consumption calculation methods, eliminates the influence of parameters such as extraction steam rate and extraction steam pressure on heat consumption calculation, and provides more objective evaluation of the thermal performance of cogeneration units, providing data support for energy saving and consumption reduction.

[0076] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0077] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0078] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in at least one embodiment or example.

[0079] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for evaluating the energy consumption characteristics of a combined heat and power (CHP) unit, characterized in that, Includes the following steps: Multiple steam performance measurement points are set up within the combined heat and power (CHP) unit; the CHP unit includes a boiler, a turbine unit, and a generator unit; high-pressure feedwater enters the boiler to generate high-temperature main steam, which then enters the turbine unit to drive the generator unit to generate electricity; the exhaust steam from the turbine unit is cooled to condensate, which is then pressurized and heated before being transported to the boiler; each steam performance measurement point includes at least the measurement of temperature and pressure data, and some of the steam performance measurement points also include the measurement of flow rate data. The steam delivery pipeline within the turbine unit forms an extraction boundary, and an extraction point is set on the extraction boundary. The turbine unit and the boiler are adjusted to operating condition A, where the heat consumption to be measured is under operating condition A. Under operating condition A, the flow rate of the high-pressure feedwater is q1. s1 The generator set has a power of P. s1 The external steam extraction rate at the extraction point is q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7. s1 Calculate the heat absorption Q on the water side of the boiler. s1 ; In operating condition B, the external steam extraction rate at the extraction point is maintained at q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7. s1 And adjust the flow rate q1 of the high-pressure water supply. s2 For q1 s1 +Δq, the power of the generator set increases to P s1 +ΔP, the heat absorption on the water side of the boiler is Q. s2 Calculate the heat consumption L of the generator set. s2 The heat consumption L of the generator set under the combined heat and power unit operating condition B. s2 The calculation formula is as follows: L s2 =(Q s2 -Q s1 ) 3.6 / ΔP / ζ; ζ=1+(h5 s2 -h5 s1 ) / (h5 s1 -h6 s1 ); Wherein, the L s2 The unit is kJ / (kW.h); ΔP is the increase in generator power (MW) after increasing the flow rate of the high-pressure feedwater under operating condition A by Δq; h5 s2 The steam enthalpy at the extraction point under operating condition B is expressed in kJ / kg; h5 s1 h6 s1 The enthalpy values ​​of the steam at the extraction point and the exhaust steam, respectively, are given in kJ / kg under operating condition A. In operating condition C, the external steam extraction rate at the extraction point is maintained at q5. s1 The outlet pressure of the exhaust steam is p6. s1 The temperature of the condensate is t7. s1 Adjust the flow rate q1 of the high-pressure water supply in operating condition C. s3 For q1 s1 -Δq, the generator set power is reduced to P s1 -ΔP, the heat absorption on the water side of the boiler is Q. s3 Calculate the heat consumption L of the generator set. s3 The heat consumption L of the generator set under the operating condition C of the combined heat and power unit. s3 The calculation formula is as follows: L s3 =(Q s1 -Q s3 ) 3.6 / ΔP / ζ; ζ=1+(h5 s3 -h5 s1 ) / (h5 s1 -h6 s1 ); Wherein, the L s3 The unit is kJ / (kW.h); ΔP is the power reduction of the generator set by decreasing the flow rate of the high-pressure feedwater under operating condition A by Δq, in MW; h5 s3 The steam enthalpy at the extraction point under operating condition C is expressed in kJ / kg; h5 s1 h6 s1 The enthalpy values ​​of the steam at the extraction point and the exhaust steam, respectively, are given in kJ / kg under operating condition A. Under operating condition A, the heat consumption of the combined heat and power (CHP) unit is L, where the value of L is inversely related to the thermodynamic performance of the CHP unit, and the calculation formula for the heat consumption L of the CHP unit is as follows: L = (L s2 +L s3 ) / 2.

2. The method according to claim 1, characterized in that, The turbine unit includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder, which are respectively connected to the generator unit. High-pressure feedwater enters the boiler to generate high-temperature main steam. The high-temperature main steam enters the high-pressure cylinder and performs work to generate cold reheat steam, which is then fed into the boiler to form reheat steam. The reheat steam enters the intermediate-pressure cylinder and performs work before flowing into the low-pressure cylinder to perform work. The exhaust steam from the low-pressure cylinder after performing work is cooled into condensate, which is then pressurized and heated before being sent to the boiler.

3. The method according to claim 2, characterized in that, The cogeneration unit also includes auxiliary components; the auxiliary components include a condenser, a condensate pump and a regenerator connected in sequence according to the flow direction of the exhaust steam output from the low-pressure cylinder, which are used to cool the exhaust steam into the condensate, and after pressurization and heating, generate the high-pressure feedwater and send it to the boiler.

4. The method according to claim 3, characterized in that, Multiple steam performance measuring points are respectively distributed at the high-pressure feedwater inlet, the high-temperature main steam outlet, the cold reheat steam inlet, and the reheat steam outlet of the boiler; as well as at the extraction steam outlet, the low-pressure cylinder outlet, and the condenser outlet.

5. The method according to claim 4, characterized in that, The flow rate data measured at the steam performance measuring points of the high-pressure feedwater inlet and / or the high-temperature main steam outlet; the flow rate data measured at the steam performance measuring points of the cold reheat steam inlet and / or the reheat steam outlet; and the flow rate data measured at the steam performance measuring points of the extraction steam outlet.

6. The method according to claim 5, characterized in that, Q s1 The calculation formula is as follows: Q s1 =[q1 (h2-h1)+ q3 (h4-h3)] s1 ; Where q1 s1 q3 represents the flow rate of high-pressure water supply under operating condition A, in kg / s. s1 The cold resteam flow rate under operating condition A is kg / s; h1 s1 The enthalpy of the high-pressure water supply under operating condition A is expressed in kJ / kg; h2 s1 The enthalpy of the high-temperature main steam under operating condition A is expressed in kJ / kg; h3 s1 The enthalpy of the cold revapor under operating condition A is expressed in kJ / kg; h⁴ s1 The enthalpy of the reheat steam under operating condition A is expressed in kJ / kg.

7. The method according to claim 5, characterized in that, The combined heat and power unit operates under condition B, Q s2 The calculation formula is as follows: Q s2 =[q1 (h2-h1)+ q3 (h4-h3)] s2 ; Where q1 s2 q3 represents the flow rate of high-pressure water supply under operating condition B, in kg / s. s2 The cold resteam flow rate under operating condition B is kg / s; h1 s2 The enthalpy of the high-pressure water supply under operating condition B is expressed in kJ / kg; h2 s2 The enthalpy of the high-temperature main steam under operating condition B is given in kJ / kg; h3 s2 The enthalpy of the cold revapor described under operating condition B is expressed in kJ / kg; h⁴ s2 The enthalpy of the reheat steam under operating condition B is expressed in kJ / kg.

8. The method according to claim 5, characterized in that, The combined heat and power unit operates under condition C Q s3 The calculation formula is as follows: Q s3 =[q1 (h2-h1)+ q3 (h4-h3)] s3 ; Where q1 s3 q3 represents the flow rate of high-pressure water supply under operating condition C, in kg / s. s3 The cold resteam flow rate under operating condition C is kg / s; h1 s3 The enthalpy of the high-pressure feedwater under operating condition C is expressed in kJ / kg; h2 s3 The enthalpy of the high-temperature main steam under operating condition C is expressed in kJ / kg; h3 s3 The enthalpy of the cold revapor under operating condition C is given in kJ / kg; h⁴ s3 The enthalpy of the reheat steam under operating condition C is expressed in kJ / kg.

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