A prediction method for the average inlet temperature of the power turbine of a marine gas turbine based on the energy balance method

Abstract

The object of the present invention is to provide a method for predicting the average temperature at the inlet of a marine gas turbine power turbine based on the energy balance method, comprising the following steps: calculating the intake air flow rate; calculating the combustion efficiency; performing sensible heat correction on the fuel calorific value; and predicting the average temperature at the inlet of the gas turbine power turbine. The present invention obtains an accurate average temperature at the inlet of the power turbine, effectively solves the problem that the average value calculation method of the inlet temperature of the power turbine depends on the measurement results of hot end components and there are large systematic deviations, and strongly improves the performance calculation and analysis level of the gas turbine. The present invention has universality and is not limited to marine gas turbines, and is also applicable to the prediction process of the outlet temperature of gas turbine generators of various aero-engines.

Description

Technical Field

[0001] The present invention relates to a method for predicting the performance of a gas turbine, specifically a method for predicting the power turbine of a marine gas turbine. Background Art

[0002] To ensure the safe and stable operation of a marine gas turbine, it is often necessary to ensure that both the rotational speed and the temperature at the key cross-section do not exceed the limit values. The inlet temperature of the power turbine, as an important temperature limit value for the operation of the gas turbine, directly characterizes the operating state of the gas turbine. Accurately obtaining the inlet temperature state of the power turbine is of great significance for the throttle adjustment and dynamic control of the unit.

[0003] However, due to the complex flow field at the inlet of the power turbine, with large circumferential and radial non-uniformities, and large variations in the flow velocity and heat load in the measurement environment, it is difficult to accurately measure the inlet temperature of the power turbine. The existing average value calculation method for the inlet temperature of the power turbine depends on the measurement results of the hot end components and has a large systematic deviation. Therefore, it is necessary to explore and develop a more breakthrough and practical method for predicting the average inlet temperature of the power turbine of a marine gas turbine in order to effectively improve the performance calculation and analysis level of the gas turbine. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for predicting the average inlet temperature of the power turbine of a marine gas turbine based on the energy balance method, which can solve problems such as difficulties in measuring and calculating the average temperature.

[0005] The purpose of the present invention is achieved as follows:

[0006] A method for predicting the average inlet temperature of the power turbine of a marine gas turbine based on the energy balance method according to the present invention is characterized in that:

[0007] (1) Calculate the intake air flow rate;

[0008] (2) Calculate the combustion efficiency;

[0009] (3) Correct the calorific value of the fuel with sensible heat;

[0010] (4) Predict the average inlet temperature of the power turbine of the gas turbine.

[0011] The present invention may further include:

[0012] 1. The calculation process of the intake air flow rate is as follows:

[0013] Measure the cross-sectional area A of the intake air flow rate pipe, the atmospheric temperature T0, the total pressure P0 at the measurement cross-section of the flow rate pipe * the static pressure P0 at the measurement cross-section of the flow rate pipe, and the flow coefficient K of the flow rate pipe w , and calculate the intake air flow rate W:

[0014]

[0015] In the above formula, γ is the specific heat ratio and R is the gas constant.

[0016] 2. The calculation process of the combustion efficiency is as follows:

[0017] Measure the volumetric percentage concentrations of CO2, CH4, H2, CO, and UHC in the flue gas of the emissions, and calculate the combustion efficiency ηc:

[0018]

[0019] 3. The process of correcting the sensible heat of the fuel calorific value is as follows:

[0020] Correct the lower heating value LHV of the fuel according to the type and properties of the fuel used and the fuel temperature Tf,

[0021] to obtain the lower heating value LHV’ of the fuel after sensible heat correction:

[0022] LHV' = LHV + aTf

[0023] In the above formula, a is the sensible heat correction coefficient obtained based on the fuel test results.

[0024] 4. The prediction of the average temperature at the inlet of the power turbine of the gas turbine is specifically as follows:

[0025] Calculate the average temperature T at the inlet of the power turbine of the gas turbine based on the atmospheric temperature T0, the intake air flow rate W, the lower heating value LHV’ of the fuel after sensible heat correction, and the fuel flow rate Gf injected into the combustion chamber av :

[0026]

[0027] In the above formula, cp a is the specific heat at constant pressure of air; cp f is the specific heat at constant pressure of the gas.

[0028] The advantages of the present invention are as follows:

[0029] 1. Based on the idea of energy balance, the present invention determines that: (1) the average temperature at the inlet of the power turbine is independent of the air system air extraction and mixing position; (2) the average temperature at the inlet of the power turbine is independent of the power balance of the compressor turbine; (3) the average temperature at the inlet of the power turbine is only related to the intake air flow rate of the gas turbine and the total enthalpy value of the fuel.

[0030] 2. The present invention can accurately calculate the temperature at the key section quickly and efficiently evaluate the performance matching of the gas turbine.

[0031] 3. The present invention is applicable not only to marine gas turbines, but also to the calculation process of the outlet temperature of gas turbine generators of various aero-engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be described in more detail with reference to the accompanying drawings as follows:

[0034] Combined with Figure 1 , a method for calculating the average inlet temperature of the power turbine of a marine gas turbine based on the energy balance method of the present invention is realized through the following steps:

[0035] Step 1: Intake air flow calculation. Measure the cross-sectional area A of the intake air flow pipe, the atmospheric temperature T0, the total pressure P0 at the measurement cross-section of the flow pipe * , the static pressure P0 at the measurement cross-section of the flow pipe, and the flow coefficient K of the flow pipe w , and calculate the intake air flow W:

[0036]

[0037] In the above formula, γ is the specific heat ratio, and R is the gas constant.

[0038] Step 2: Combustion efficiency calculation. Measure the volume percentage concentrations of CO2, CH4, H2, CO, and UHC (unburned hydrocarbons) in the exhaust flue gas, and calculate the combustion efficiency ηc:

[0039]

[0040] Step 3: Fuel calorific value sensible heat correction. Correct the lower calorific value LHV of the fuel according to the type and properties of the fuel used and the fuel temperature Tf to obtain the lower calorific value LHV' of the fuel after sensible heat correction:

[0041] LHV' = LHV + aTf

[0042] In the above formula, a is the sensible heat correction coefficient obtained according to the fuel test results.

[0043] Step 4: Calculate the average inlet temperature of the power turbine of the gas turbine. Calculate the average inlet temperature T of the power turbine of the gas turbine according to the atmospheric temperature T0, the intake air flow W, the lower calorific value LHVz of the fuel after sensible heat correction, the fuel flow Gf injected into the combustion chamber, etc. av :

[0044]

[0045] In the above formula, cp a is the specific heat at constant pressure of air; cpf is the specific heat at constant pressure of the gas.

[0046] The calculation method of the average temperature at the inlet of the power turbine of a marine gas turbine based on the energy balance method proposed by the present invention is universal, not only limited to marine gas turbines, but also applicable to the calculation process of the outlet temperature of gas turbine generators of various aeroengines.

Claims

1. A method for predicting the average inlet temperature of a marine gas turbine power turbine based on the energy balance method, characterized in that: (1) Calculate the intake air flow rate; (2) Calculate the combustion efficiency; (3) Correct the fuel calorific value with sensible heat; (4) Predict the average inlet temperature of the gas turbine power turbine; The prediction of the average inlet temperature of the gas turbine power turbine is specifically as follows: Calculate the average temperature T at the inlet of the power turbine of the gas turbine based on the atmospheric temperature T0, the intake air flow rate W, the lower heating value LHV' of the fuel after sensible heat correction, and the fuel flow rate Gf injected into the combustion chamber av : In the above formula, cp a is the specific heat at constant pressure of air; cp f is the specific heat at constant pressure of fuel gas, and η c is the combustion efficiency.

2. A prediction method for the average inlet temperature of the power turbine of a marine gas turbine based on the energy balance method according to claim 1, characterized in that: The calculation process of the intake air flow rate is as follows: Measure the cross-sectional area A of the intake air flow pipe, the atmospheric temperature T0, and the total pressure P0 at the measurement cross-section of the flow pipe * 、the static pressure P0 at the measurement cross-section of the flow pipe, and the flow coefficient K of the flow pipe w , and calculate the intake air flow rate W: In the above formula, γ is the specific heat ratio and R is the gas constant.

3. A prediction method for the average inlet temperature of the power turbine of a marine gas turbine based on the energy balance method according to claim 1, characterized in that: The calculation process of the combustion efficiency is as follows; Measure the volume percentage concentrations of CO2, CH4, H2, CO, and UHC in the exhaust gas, and calculate the combustion efficiency ηc:

4. A prediction method for the average temperature at the inlet of the power turbine of a marine gas turbine based on the energy balance method according to claim 1, characterized in that: The process of correcting the fuel calorific value with sensible heat is as follows; According to the type and properties of the fuel used, correct the lower heating value LHV of the fuel with the fuel temperature Tf, to obtain the lower heating value LHV' of the fuel after sensible heat correction: LHV' = LHV + aTf In the above formula, a is the sensible heat correction coefficient obtained according to the fuel test results.

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