A method for distinguishing the power of gas turbine and steam turbine in a single-shaft combined cycle unit

Abstract

The present invention discloses a method for distinguishing the power of a gas turbine and a steam turbine in a single-shaft combined cycle unit. The method first calculates the power of the steam turbine and then calculates the power of the gas turbine. The method allows users to easily and relatively accurately and reliably distinguish the power of the gas turbine and the steam turbine that cannot be directly measured in a single-shaft combined cycle unit even without comprehensive data support from gas turbine manufacturers and without relying on foreign commercial software. The method is suitable for online or offline performance analysis and diagnosis of combined cycle units.

Description

Technical Field

[0001] The invention belongs to the field of thermal power engineering, and in particular relates to a method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit. Background Art

[0002] Gas-steam combined cycle units (referred to as combined cycle units) have the characteristics and advantages of clean and low carbon, flexible operation and fuel diversity. They are one of the indispensable and important power generation methods for building a new power system with new energy as the main body. The key host equipment of the combined cycle unit is usually composed of gas turbines, steam turbines, generators, waste heat boilers, etc. According to the different shaft system arrangements, the combined cycle unit is usually divided into single-shaft combined cycle units and split-shaft combined cycle units, among which: the gas turbine, steam turbine, and generator of the single-shaft combined cycle unit are connected in series on the same shaft system, and the output power of the gas turbine and steam turbine is output by the same generator; the shaft system of the split-shaft combined cycle unit is independently composed of the gas turbine-generator shaft system and the steam turbine-generator shaft system, and the output power of the gas turbine and steam turbine is output by separate generators. Since the output power of the gas turbine and steam turbine of the single-shaft combined cycle unit is output by the same generator, it is impossible to measure the output power of the gas turbine and steam turbine separately, making it impossible for operating personnel to judge the operating performance and degradation of the gas turbine and steam turbine, which increases the difficulty and risk of operation management.

[0003] How to accurately distinguish the output power of gas turbines and steam turbines in single-shaft combined cycle units by calculation or estimation is one of the technical difficulties in operation and maintenance in the field of combined cycle power generation. There are generally two ways to distinguish the output power of gas turbines and steam turbines in single-shaft combined cycle units by calculation or estimation, among which: the first way is to first calculate the output power of the gas turbine, and then obtain the output power of the steam turbine by the difference between the total power of the combined cycle unit and the output power of the gas turbine; the second way is to first calculate and determine the output power of the steam turbine, and then obtain the output power of the gas turbine by the difference between the total power of the combined cycle unit and the output power of the steam turbine. Because the first way requires the establishment of a gas turbine performance calculation model before calculating the output power of the gas turbine, the performance characteristics of the components (compressor, turbine, combustion chamber) and the design parameters such as turbine cooling flow distribution that must be known to establish the gas turbine performance calculation model are strictly confidential by the gas turbine manufacturer and are difficult to obtain. Therefore, the process of establishing a gas turbine performance calculation model is complicated and the accuracy is difficult to guarantee. In view of this, in the absence of comprehensive data support from gas turbine manufacturers, the second method is a more feasible way for users to distinguish between the output power of gas turbines and steam turbines in single-shaft combined cycle units.

[0004] At present, there is no publicly published method for distinguishing the power of gas turbines and steam turbines in single-shaft combined cycle units that can be easily implemented by users and is relatively accurate and reliable without comprehensive data support from gas turbine manufacturers and without relying on foreign commercial software. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit comprises the following steps:

[0008] S1. According to the steam turbine design thermal parameters of the combined cycle unit, a functional relationship between the design efficiency of the steam turbine low-pressure cylinder and the thermal design parameters related to the low-pressure cylinder is obtained by fitting;

[0009] S2. According to the design thermal parameters of the steam turbine of the combined cycle unit, a functional relationship between the design leakage of each cylinder of the steam turbine and the thermal design parameters related to each cylinder is obtained by fitting;

[0010] S3. According to the design parameters of the combined cycle unit generator, a functional relationship between the generator efficiency and the relevant design and operation parameters of the generator is obtained by fitting;

[0011] S4. Calculate the low-pressure cylinder efficiency of the steam turbine under actual operating conditions based on the measured parameters of the combined cycle unit;

[0012] S5. Calculate the actual enthalpy drop power of each cylinder of the steam turbine based on the measured parameters of the combined cycle unit;

[0013] S6. The actual power generation of the steam turbine is calculated by multiplying the sum of the actual enthalpy drop power of each cylinder of the steam turbine by the product of the mechanical efficiency and the generator efficiency;

[0014] S7. Subtract the total power generation of the combined cycle unit from the power of the steam turbine generator to obtain the actual power generation of the gas turbine.

[0015] A further improvement of the present invention is that the steam turbine type of the combined cycle unit is high, medium and low pressure separate cylinders or high and medium pressure combined cylinder and low pressure separate cylinder.

[0016] A further improvement of the present invention is that in the steps S1, S2 and S3:

[0017] Steam turbine design thermal parameters and generator design parameters include heat balance data, performance curves and data provided by the equipment manufacturer.

[0018] A further improvement of the present invention is that in step S1:

[0019] The low-pressure cylinder pressure ratio is selected as the relevant thermal design parameter of the low-pressure cylinder; the typical functional relationship between the design isentropic efficiency of the low-pressure cylinder of the steam turbine and the design pressure ratio of the low-pressure cylinder is as follows:

[0020] EFF LP0 =f(π LP0 )

[0021]

[0022] Where: EFF LP0 Design isentropic efficiency for the low pressure cylinder; π LP0 Design the pressure ratio for the low-pressure cylinder; Design steam pressure for low pressure cylinder outlet; is the design steam pressure at the low-pressure cylinder inlet; f is the functional relationship.

[0023] A further improvement of the present invention is that in step S2:

[0024] The leakage of each cylinder of the steam turbine should be determined according to the actual structure of the steam turbine. The leakage includes the leakage of the front and rear shaft seals of the cylinder and the leakage of the steam inlet valve stem. The relevant thermal design parameters of each cylinder select the steam inlet pressure of each cylinder. The typical function form of leakage and steam inlet pressure is as follows:

[0025] G LEA0 =g(P IN 0 )

[0026] Where: G LEA0 Design value for a leakage flow; P IN 0 is the design value of the inlet steam pressure of the cylinder involved in a certain leakage flow; g is a functional relationship.

[0027] A further improvement of the present invention is that in step S3:

[0028] The generator related design and operation parameters are selected as the generator active power and power factor; the typical function form of generator efficiency and generator active power and power factor is as follows:

[0029] EFF GEN0 =h(POW 0 ,PF 0 )

[0030] Where: EFF GEN0 is the design value of generator efficiency, POW 0 is the design value of the generator active power, PF 0 is the design value of generator power factor.

[0031] A further improvement of the present invention is that in step S4:

[0032] The low-pressure cylinder efficiency of the steam turbine under actual operating conditions is calculated according to the functional relationship between the low-pressure cylinder efficiency of the steam turbine and the low-pressure cylinder pressure ratio obtained by fitting in step S1. The calculation formula is as follows:

[0033] EFF LP =f(π LP )

[0034]

[0035] Where: EFF LP is the calculated actual efficiency of the low-pressure cylinder of the steam turbine; π LP is the actual pressure ratio of the low-pressure cylinder of the steam turbine; is the actual outlet pressure of the low-pressure cylinder, It is the actual inlet pressure of the low-pressure cylinder.

[0036] A further improvement of the present invention is that in step S5:

[0037] The actual enthalpy drop power of each cylinder of the turbine is calculated according to the following formula:

[0038]

[0039]

[0040]

[0041]

[0042] Where: POW ST,ENTHALPY is the enthalpy drop power of the steam turbine;

[0043] G HP , G MP , G LP It is the measured value of steam flow at the inlet of high, medium and low pressure cylinders of the steam turbine;

[0044] G HP,LEA , G MP,LEA , G LP,LEA It is the steam flow rate flowing out or in of the high, medium and low pressure cylinders of the steam turbine due to system leakage. The flow rate flowing into the cylinder is positive, and the flow rate out of the cylinder is negative.

[0045] are the steam inlet pressures of the high, medium and low pressure cylinders respectively;

[0046] is the actual steam inlet enthalpy value of the high, medium and low pressure cylinders of the steam turbine;

[0047] is the actual outlet enthalpy of the high and medium pressure cylinders of the steam turbine;

[0048] It is the actual isentropic enthalpy value at the outlet of the low-pressure cylinder of the steam turbine.

[0049] The present invention has at least the following beneficial technical effects:

[0050] The present invention provides a method for distinguishing the power of gas turbines and steam turbines in a single-shaft combined cycle unit. The method can enable users to easily and relatively accurately and reliably distinguish the power of gas turbines and steam turbines that cannot be directly measured in a single-shaft combined cycle unit without comprehensive data support from gas turbine manufacturers and without relying on foreign commercial software. The method is suitable for online or offline performance analysis and diagnosis of combined cycle units. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic flow chart of a method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit according to the present invention. DETAILED DESCRIPTION

[0052] The present invention will be described in detail below with reference to the accompanying drawings and embodiments:

[0053] like Figure 1 As shown, for a certain single-shaft F-class combined cycle unit involved in this embodiment, a method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit described in the present invention comprises the following steps:

[0054] S1 According to the steam turbine design thermal parameters of a single-shaft F-class combined cycle unit, the functional relationship between the design efficiency of the low-pressure cylinder of the steam turbine and the thermal design parameters related to the low-pressure cylinder is fitted, as follows:

[0055] EFF LP0 =(-3E-05)×(π LP0 -1 ) 2 +0.0048×(π LP0 -1 )+0.7367;

[0056] Where: EFF LP0 Design isentropic efficiency for the low pressure cylinder; π LP0 Design the pressure ratio for the low-pressure cylinder;

[0057] S2 According to the turbine structure type and design thermal parameters of a single-shaft F-class combined cycle unit, the main steam leakage of the turbine is divided into two parts. The first part of the bridge steam seal leakage is leaked from the high-pressure cylinder inlet to the medium-pressure cylinder inlet, and the second part of the high-pressure cylinder outlet end steam seal leakage enters the shaft seal cooler; the fitted bridge steam seal leakage and high-pressure cylinder outlet end steam seal leakage flow rates are as follows:

[0058]

[0059]

[0060] Where: G LEA1,0 G is the design value of steam leakage of the bridge steam seal t / h; LEA2,0 The design value of steam leakage of the steam seal at the outlet end of the high-pressure cylinder t / h;

[0061] Design value of steam pressure at the high pressure cylinder inlet MPa;

[0062] S3 fits the generator design parameters of a single-shaft F-class combined cycle unit and obtains the functional relationship between the generator efficiency and the design operating parameters such as the generator active power and power factor, as follows:

[0063] LOSS GEN0 =(β(1)×PF 0 2 +β(2)×PF 0 +β(3))×POW 0 2 +(β(4)×PF 0 2 +β(5)×PF 0 +β(6))×POW 0 +β(7)

[0064]

[0065] Where: EFF GEN0 is the design value of generator efficiency (unit %), POW 0 is the design value of the generator active power (unit: MW), PF 0 is the design value of the generator power factor (unit 1), LOSS GEN0 is the generator loss (unit MW), β is the coefficient matrix, β = [0.032332709 -0.091401924 0.068049399 - 27.78408433 46.43805823 -18.79842003 1488.538006].

[0066] S4 takes the 100% load rate pure condensing design heat balance data of the combined cycle unit under the annual average, summer and ISO conditions as the operating parameters, and calculates the turbine low-pressure cylinder efficiency under the above three conditions as follows:

[0067]

[0068] S5 uses the 100% load rate pure condensing design heat balance data of the combined cycle unit under the annual average, summer, and ISO conditions as operating parameters, and calculates the enthalpy drop power of the high, medium, and low pressure cylinders under the above three conditions as follows:

[0069]

[0070] S6 takes the 100% load rate pure condensing design heat balance data of the combined cycle unit under the annual average, summer and ISO conditions as the operating parameters, and calculates the turbine power generation under the above three conditions as follows:

[0071]

[0072] S7 uses the 100% load rate pure condensing design heat balance data of the combined cycle unit under the annual average, summer and ISO conditions as the operating parameters, and calculates the gas turbine power generation under the above three conditions as follows:

[0073]

[0074] In order to verify the accuracy of the above results, the calculated annual average, winter, summer, and ISO gas turbine power generation results were compared with the gas turbine power generation results calculated by the foreign authoritative commercial software GT PRO (the software has performance data provided by the gas turbine manufacturer). The results are as follows:

[0075]

[0076] The calculation results show that the calculation results of the method for distinguishing the power of the gas turbine and the steam turbine of a single-shaft combined cycle unit involved in the present invention are comparable to those of the authoritative foreign commercial software GT PRO, and have higher calculation result accuracy, which verifies the effectiveness of the method of the present invention.

[0077] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above-mentioned embodiment only expresses one implementation mode of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A method for distinguishing the power of a gas turbine and a steam turbine in a single-shaft combined cycle unit, characterized in that: The following steps are involved: S1. According to the steam turbine design thermal parameters of the combined cycle unit, a functional relationship between the design efficiency of the steam turbine low-pressure cylinder and the thermal design parameters related to the low-pressure cylinder is obtained by fitting; S2. According to the design thermal parameters of the steam turbine of the combined cycle unit, a functional relationship between the design leakage of each cylinder of the steam turbine and the thermal design parameters related to each cylinder is obtained by fitting; S3. According to the design parameters of the combined cycle unit generator, a functional relationship between the generator efficiency and the relevant design and operation parameters of the generator is obtained by fitting; S4. Calculate the low-pressure cylinder efficiency of the steam turbine under actual operating conditions based on the measured parameters of the combined cycle unit; S5. Calculate the actual enthalpy drop power of each cylinder of the steam turbine based on the measured parameters of the combined cycle unit; S6. The actual power generation of the steam turbine is calculated by multiplying the sum of the actual enthalpy drop power of each cylinder of the steam turbine by the product of the mechanical efficiency and the generator efficiency; S7. Subtract the total power generation of the combined cycle unit from the power of the steam turbine generator to obtain the actual power generation of the gas turbine.

2. The method for distinguishing the power of a gas turbine and a steam turbine in a single-shaft combined cycle unit according to claim 1, characterized in that: The steam turbine type of the combined cycle unit is high, medium and low pressure separate cylinders or high and medium pressure combined cylinder and low pressure separate cylinder.

3. The method for distinguishing the power of a gas turbine and a steam turbine in a single-shaft combined cycle unit according to claim 1, characterized in that: In the steps S1, S2 and S3: Steam turbine design thermal parameters and generator design parameters include heat balance data, performance curves and data provided by the equipment manufacturer.

4. The method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit according to claim 1, characterized in that: In step S1: The low-pressure cylinder pressure ratio is selected as the relevant thermal design parameter of the low-pressure cylinder; the typical functional relationship between the design isentropic efficiency of the low-pressure cylinder of the steam turbine and the design pressure ratio of the low-pressure cylinder is as follows: EFF LP0 =f(π LP0 ) Where: EFF LP0 Design isentropic efficiency for the low pressure cylinder; π LP0 Design the pressure ratio for the low-pressure cylinder; Design steam pressure for low pressure cylinder outlet; is the design steam pressure at the low-pressure cylinder inlet; f is the functional relationship.

5. The method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit according to claim 1, characterized in that: In step S2: The leakage of each cylinder of the steam turbine should be determined according to the actual structure of the steam turbine. The leakage includes the leakage of the front and rear shaft seals of the cylinder and the leakage of the steam inlet valve stem. The relevant thermal design parameters of each cylinder select the steam inlet pressure of each cylinder. The typical function form of leakage and steam inlet pressure is as follows: G LEA0 =g(P IN 0) Where: G LEA0 Design value for a leakage flow; P IN 0 is the design value of the inlet steam pressure of the cylinder involved in a certain leakage flow; g is the functional relationship.

6. A method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit according to claim 1, characterized in that: In step S3: The generator related design and operation parameters are selected as the generator active power and power factor; the typical function form of generator efficiency and generator active power and power factor is as follows: EFF GEN0 =h(POW0,PF0) Where: EFF GEN0 is the design value of generator efficiency, POW0 is the design value of generator active power, and PF0 is the design value of generator power factor.

7. A method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit according to claim 1, characterized in that: In step S4: The low-pressure cylinder efficiency of the steam turbine under actual operating conditions is calculated according to the functional relationship between the low-pressure cylinder efficiency of the steam turbine and the low-pressure cylinder pressure ratio obtained by fitting in step S1. The calculation formula is as follows: EFF LP =f(π LP ) Where: EFF LP is the calculated actual efficiency of the low-pressure cylinder of the steam turbine; π LP is the actual pressure ratio of the low-pressure cylinder of the steam turbine; is the actual outlet pressure of the low-pressure cylinder, It is the actual inlet pressure of the low-pressure cylinder.

8. The method for distinguishing the power of a gas turbine and a steam turbine of a single-shaft combined cycle unit according to claim 1, characterized in that: In step S5: The actual enthalpy drop power of each cylinder of the turbine is calculated according to the following formula: Where: POW ST,ENTHALPY is the enthalpy drop power of the steam turbine; G HP , G MP , G LP It is the measured value of steam flow at the inlet of high, medium and low pressure cylinders of the steam turbine; G HP,LEA , G MP,LEA , G LP,LEA It is the steam flow rate flowing out or in of the high, medium and low pressure cylinders of the steam turbine due to system leakage. The flow rate flowing into the cylinder is positive, and the flow rate out of the cylinder is negative. are the steam inlet pressures of the high, medium and low pressure cylinders respectively; is the actual steam inlet enthalpy value of the high, medium and low pressure cylinders of the steam turbine; is the actual outlet enthalpy of the high and medium pressure cylinders of the steam turbine; It is the actual isentropic enthalpy value at the outlet of the low-pressure cylinder of the steam turbine.

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