Gas turbine bleed air anti-icing system and anti-icing method

Abstract

The invention provides a gas turbine bleed air anti-icing system and an anti-icing method, and relates to the field of marine gas turbines.According to the method, energy conservation is utilized, the inlet temperature of a gas compressor is calculated in real time according to the air inflow of the gas turbine in the whole running process and under all working conditions, and the inlet humidity of the gas compressor is calculated according to the air humidity actually measured after a filter cartridge; and when the humidity of the inlet of the air compressor reaches 100% and the temperature of the inlet of the air compressor is lower than 0 DEG C, and the icing condition is met, an air-entraining anti-icing system is put into use. And through an energy equation, the lowest temperature at which the air compressor is not frozen is calculated, and then the needed hot air flow is obtained. According to the anti-icing system, the required amount of hot air is input by adjusting the opening degree of the electric valve. According to the method, the freezing condition of the inlet of the gas compressor under the full working conditions of the gas turbine can be accurately pre-warned, meanwhile, unnecessary efficiency reduction of the gas turbine caused by premature investment can be avoided, and the method has important significance on stable and efficient operation of the gas turbine.

Description

Technical Field

[0001] The invention relates to the technical field of marine gas turbines, in particular to a gas turbine bleed air anti-icing system and an anti-icing method. Background Art

[0002] As a power source, gas turbines are widely used in ship power and offshore platforms. During the use of gas turbines, the sharp change in the intake speed at the gas turbine inlet will cause a large change in the intake temperature, and the internal energy of the air will be converted into the kinetic energy of the air. Due to the reduction of the cross-section and the increase of the air flow rate at the gas turbine compressor inlet, the intake temperature decreases; part of the water vapor in the air will condense into water; the condensed water will freeze when it is below the freezing point, and the compressor inlet is in a high speed and is in a safety factor. When it is running for a long time, it is not suitable to measure the local relative humidity of the air.

[0003] Gas turbines generally use bleed air from the middle stage of the compressor to introduce high-temperature and high-pressure air into the inlet duct to heat the air and prevent icing. However, bleed air causes the gas turbine efficiency to decrease, and accurate early warning is required: whether the real-time operating conditions require the bleed air anti-icing system to be activated to prevent unnecessary efficiency reduction of the gas turbine caused by premature activation. Summary of the invention

[0004] In view of the shortcomings in the above-mentioned existing production technology, the applicant provides a gas turbine bleed air anti-icing system and anti-icing method, which accurately warns of icing conditions at the compressor inlet, prevents the bleed air anti-icing system from being put into use too early or too late, and ensures efficient and stable operation of the gas turbine.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A gas turbine bleed air anti-icing method determines the bleed air time node by measuring and calculating the hot air flow and corresponding valve opening required for anti-icing according to the compressor inlet icing conditions of the gas turbine under all working conditions.

[0007] The specific steps include:

[0008] Step 1: Measure the compressor inlet static pressure and air intake volume under multiple operating conditions during the process of the gas turbine from slow running to rated operating conditions.

[0009] Step 2: The gas turbine operates stably under the specified working conditions, and the humidity, air static pressure, and air temperature at the outlet of the air inlet filter cartridge under the current working conditions are measured in real time.

[0010] Using the energy conservation equation, the compressor inlet temperature is calculated.

[0011] Calculate the temperature difference between the air temperature at the outlet of the air inlet filter and the compressor inlet temperature.

[0012] Step 3: Calculate the saturated vapor pressure of the air after the filter cartridge and at the compressor inlet, and the current vapor pressure of the air after the filter cartridge.

[0013] Step 4: When the ratio of the current vapor pressure of the air after the filter cartridge to the saturated vapor pressure of the compressor inlet air is greater than or equal to 1 and the compressor inlet temperature is less than or equal to 273.15K, an anti-icing warning is issued. At this time, hot air should be introduced immediately.

[0014] Step 5: Calculate the temperature of the mixed air after adding hot air;

[0015] The calculation method takes the compressor inlet temperature as the starting temperature, and records the compressor inlet correction temperature every 1°C increase.

[0016] When the corrected temperature at the compressor inlet is less than or equal to 273.15K, calculate the saturated vapor pressure of the current compressor inlet air. When the ratio of the current vapor pressure of the air after the filter cartridge to the saturated vapor pressure of the compressor inlet air is less than 1, the mixed air temperature is the sum of the corrected temperature at the compressor inlet and the temperature difference obtained in step 2.

[0017] When the compressor inlet correction temperature is greater than 273.15K, the mixed air temperature is the sum of the compressor inlet correction temperature and the temperature difference obtained in step 2.

[0018] Step 6: Calculate the mass of hot air input according to the heat absorption formula.

[0019] Step 7: Gradually open the electric valve on the air bleed pipe and measure the real-time air bleed volume until it reaches the theoretical value of air bleed volume obtained in step 6.

[0020] At the same time, measure the real-time absolute pressure, static pressure and real-time temperature to confirm that the real-time bleed air volume can meet the bleed air anti-icing needs.

[0021] In step 2, the energy equation is:

[0022]

[0023] Flow rate after filter cartridge: Compressor flow rate: Compressor inlet temperature: Among them, A 滤筒后 , A 压气机进口 are the known inlet duct cross-sectional areas, in m 2 , compressor inlet area, m 2 ;c p is the constant pressure heat capacity of air 1005 j / (kg·k); T is the temperature in K; ρ is the air density 1.293 kg / m 3 ;m 进气is the air mass flow rate, unit is kg / s; c is the air velocity, unit is m / s; h is the air enthalpy, unit is j.

[0024] Temperature difference ΔT = T 滤筒后 -T 压气机进口 .

[0025] In step six, the heat absorption formula is:

[0026] m 混合 ×c p混合 ×T 混合 =m 引气 ×c p进气 ×T 引气 +(m 进气 -m 引气 )×c p进气 ×T 滤筒后 .

[0027] In step 7, the formula for calculating the current real-time air intake volume is as follows:

[0028]

[0029] in: q=-0.8562×Ma 2 +1.9742×Ma-0.0237

[0030] Among them, P * , P, T * The total temperature and total pressure probes measure absolute pressure (Pa), static pressure (Pa), and temperature (K) in real time; A is the cross-sectional area of ​​the pipeline (m 2 ).

[0031] A bleed air anti-icing system is suitable for the above-mentioned bleed air anti-icing method, comprising an electric valve, a bleed air flow measurement section, a bleed air pipe, a bleed air injection branch pipe, and a spiral nozzle arranged in sequence; the electric valve is connected to the air outlet of the middle stage of the compressor.

[0032] Total temperature and total pressure probes and pipeline static pressure measuring points are set on the bleed air flow measurement section.

[0033] The total temperature and total pressure probe is located at a position 10 times the diameter of the bleed air flow measurement section along the intake direction.

[0034] A length of 5 times the diameter is reserved on the side of the total temperature and total pressure probe facing the outflow direction of the airflow.

[0035] The beneficial effects of the present invention are as follows:

[0036] The present application discloses a gas turbine bleed air anti-icing system and method. The method uses the law of energy conservation to calculate the compressor inlet temperature in real time according to the intake volume of each operating condition during the entire operation of the gas turbine; and calculates the compressor inlet humidity according to the measured air humidity after the filter cartridge. When the compressor inlet humidity reaches 100% and the compressor inlet temperature is lower than 0°C, the icing condition is met, and the bleed air anti-icing system should be put into operation.

[0037] Through the energy equation, the lowest temperature at which the compressor does not freeze is calculated, and the required hot air flow rate is then obtained.

[0038] The anti-icing system releases the required amount of hot air by adjusting the opening of the electric valve.

[0039] This method can accurately warn of compressor inlet icing conditions under all operating conditions of gas turbines, and can also avoid unnecessary efficiency reduction caused by premature commissioning of gas turbines, which is of great significance to the stable and efficient operation of gas turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The figure is a flowchart of the method of the present invention.

[0041] Figure 2 It is a schematic diagram of the structure of the bleed air anti-icing system of the present invention.

[0042] Figure 3 for Figure 2 The enlarged view of part A is used to illustrate the structure of the air bleed nozzle.

[0043] Figure 4 for Figure 2 Schematic diagram of the distribution of the central airway.

[0044] Figure 5 It is a schematic diagram of the arrangement of the bleed air injection branch pipe of the present invention.

[0045] Figure 6 It is a schematic diagram of the airway pipe with the probe installed in the present invention.

[0046] Figure 7 for Figure 6 BB cross-sectional view showing the total temperature and total pressure probes and pipeline static pressure measuring points.

[0047] Among them: 1. Electric valve; 2. Bleed air flow measurement section; 3. Bleed air pipe; 4. Bleed air injection branch pipe; 5. Spiral nozzle; 6. Bracket; 7. Total temperature and total pressure probe; 8. Pipeline static pressure measuring point. DETAILED DESCRIPTION

[0048] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0049] The present invention provides a gas turbine bleed air anti-icing system, which guides the high-temperature and high-pressure gas of the compressor middle stage to the compressor mouth, mixes it with the filtered high-humidity cold air, and then enters the gas turbine again for operation.

[0050] The bleed air anti-icing system is arranged in sequence along the flow path of high temperature and high pressure gas: Figure 2-Figure 4 As shown, it includes an electric valve 1 connected to the air outlet of the middle stage of the compressor, a bleed air flow measurement section 2, a bleed air pipe 3, a bleed air injection branch pipe 4, and a spiral nozzle 5. A bracket 6 is arranged on the rigid wall between the compressor inlet and the filter on the intake pipe, and the bleed air injection branch pipe 4 and the spiral nozzle 5 are installed on the bracket 6. The air outlet direction of the spiral nozzle 5 is toward the compressor inlet.

[0051] like Figure 5 As shown, a plurality of bleed air injection branch pipes 4 are provided.

[0052] like Figure 6 and Figure 7 As shown, in the bleed air flow measurement section 2, a total temperature and total pressure probe 7 and a measuring pipeline static pressure measuring point 8 are installed at a position 10 times the diameter along the length of the intake direction; on the output side of the total temperature and total pressure probe 7 along the air flow direction, the bleed air measurement section has a length of 5 times the diameter.

[0053] The method for determining the time node for the above-mentioned bleed air anti-icing system to be put into use comprises the following steps:

[0054] Step 1: A gas turbine is tested in horizontal air intake mode to measure the static pressure p at the compressor inlet of each operating condition from slow to rated condition. 压气机进口 The intake volume m 进气 Each 10% increment is one level. For example, under the 0.9 working condition, p 压气机进口 =97300pa, air intake volume m 进气 =80kg / s.

[0055] Step 2: The gas turbine adopts the box-mounted upper air intake mode, continues to operate stably under the 0.9 working condition, and measures the humidity behind the air intake filter cartridge under the current working condition in real time Air static pressure p 滤筒后 =101200pa, air humidity T 滤筒后 =274K.

[0056] Using the energy conservation equation, calculate the compressor inlet temperature T 压气机进口 :

[0057]

[0058] h=c p ×T

[0059] Flow rate after filter cartridge:

[0060] Compressor flow rate:

[0061] Compressor inlet temperature:

[0062] Among them, A 滤筒后 , A 压气机进口 are the known inlet duct cross-sectional areas, in m 2 , compressor inlet area, m 2 ;c p is the constant pressure heat capacity of air 1005 j / (kg·k); T is the temperature in K; ρ is the air density 1.293 kg / m 3 ;m 进气 is the air mass flow rate, unit is kg / s; c is the air velocity, unit is m / s; h is the air enthalpy, unit is j.

[0063]

[0064] ΔT=T 滤筒后 -T 压气机进口 =274-268.05=5.95K

[0065] Step 3: Calculate the saturated vapor pressure of the air at the compressor inlet after the filter cartridge, as follows:

[0066] P s滤筒后 =-0.000006070589347×274 5 +0.007858791850406×

[0067] 274 4 -4.051931526060180×274 3 +1040.745120439270000×274 2 -133236.532196521000000×274+6803973.83805504=646.64pa

[0068] P s压气机进口 =-0.000006070589347×268.05 5 +0.007858791850406×

[0069] 268.05 4 -4.051931526060180×268.05 3 +1040.745120439270000×268.05 2-133236.532196521000000×268.05+6803973.83805504=268.05pa

[0070] Calculate the current vapor pressure of the air after the filter cartridge as follows:

[0071]

[0072] Step 4: When

[0073]

[0074] An anti-icing warning should be issued and the bleed air anti-icing system should be put into use in a timely manner.

[0075] The data used in the above steps are from Shen Weidao, Tong Jungeng. "Engineering Thermodynamics" [M]. Beijing: Higher Education Press, 2016. The corresponding relationship between temperature and saturated vapor pressure and the fitting formula are disclosed.

[0076] Step 5: Calculate the temperature of the mixed air after the bleed air anti-icing system is put into use. 混合 , T 混合 In the range of (274-5.95)~274, with 268.05K as the benchmark, for every 1℃ increase, P is calculated according to the above formula. s压气机进口 Calculation of

[0077] T 压气机进口修正 =268.05+1≤273.15K, then

[0078] P s压气机进口 =-0.000006070589347×269.05 5 +0.007858791850406×269.05 4 -4.051931526060180×269.05 3 +1040.745120439270000×269.05 2 -133263.532196521000000×269.05+6803973.83805504=435.2456

[0079] at this time

[0080] Then increase by 1℃

[0081] T 压气机进口修正 =268.05+2≤273.15K, then

[0082] P s压气机进口 =-0.000006070589347×270.055 +0.007858791850406×270.05 4 -4.051931526060180×270.05 3 +1040.745120439270000×270.05 2 -133263.532196521000000×270.05+6803973.83805504=472.9411

[0083] at this time

[0084] Then increase by 1℃

[0085] T 压气机进口修正 =268.05+3≤273.15K, then

[0086] P s压气机进口 =-0.000006070589347×271.05 5 +0.007858791850406×

[0087] 271.05 4 -4.051931526060180×271.05 3 +1040.745120439270000×271.05 2 -133263.532196521000000×271.05+6803973.83805504=513.123

[0088] at this time

[0089] Then increase by 1℃

[0090] T 压气机进口修正 =268.05+4≤273.15K, then

[0091] P s压气机进口 =555.8473

[0092] at this time

[0093] Then increase by 1℃

[0094] T 压气机进口修正 =268.05+5≤273.15K, then

[0095] P s压气机进口 =601.1612

[0096] at this time Recorded as T压气机进口修正 =268.05+5=273.05K.

[0097] T 压气机进口修正 =273.05K≤273.15K, then T 混合 =T 压气机进口修正 +ΔT=273.05+5.95=279K.

[0098] Step 6:

[0099] The mass m of the hot air introduced is calculated by the following formula 引气 :

[0100] m 混合 ×c p混合 ×T 混合 =m 引气 ×c p进气 ×T 引气 +(m 进气 -m 引气 )×c p进气 ×T 滤筒后

[0101] Substitute the parameters:

[0102] 80×1.005×279=m 引气 ×1.005×(180+273.15)+(80-m 引气 )×1.005×274, where T 引气 It is the temperature of the air inlet point, unit is K; it is measured by a thermal resistor. During the air extraction operation test, this temperature can be measured in advance, or it can be measured by a total temperature and total pressure probe.

[0103] Calculate m 引气 =2.23kg / s.

[0104] Step 7: Gradually open the electric valve opening, and use the probe to measure and calculate m in real time in the air bleed measurement section. 引气实时 , until m 引气实时 =2.23kg / s.

[0105] Gradually open the electric valve, and the total temperature and total pressure probe measures the absolute pressure P in real time. * , static pressure P, temperature T * ; A is the cross-sectional area of ​​the pipe 3.14×(0.15 / 2) 2 =0.01766m 2 .

[0106]

[0107] q=-0.8562×Ma 2+1.9742×Ma-0.0237

[0108] When the valve opening reaches 20%, the air temperature T * is 180℃, total pressure P * =125098pa, static pressure P = 124485pa,

[0109] According to Tian Fu. Experimental Research Methods of Aerodynamic Performance of Turbomachinery [M]. Beijing: Tsinghua University Press, 2013. The calculation method of pipeline flow rate is calculated by calculating Mach number Ma = 0.0838; q = 0.1357; m 引气实时 =2.27kg / s, it meets the requirements of bleed air anti-icing.

[0110] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any form of modification may be made within the scope of protection of the present invention.

Claims

1. A gas turbine bleed air anti-icing method, characterized in that: According to the compressor inlet icing conditions of the gas turbine under all operating conditions, the hot air flow and corresponding valve opening required for anti-icing are obtained through measurement and calculation, and the time node for air bleed is determined.

2. The gas turbine bleed air anti-icing method according to claim 1, characterized in that: The specific steps include: Step 1: Measure the compressor inlet static pressure and air intake volume under multiple operating conditions during the process of the gas turbine from slow running to rated operating conditions. Step 2: The gas turbine operates stably under the specified working conditions, and the humidity, air static pressure, and air temperature at the outlet of the air inlet filter cartridge under the current working conditions are measured in real time. Using the energy conservation equation, the compressor inlet temperature is calculated. Calculate the temperature difference between the air temperature at the outlet of the air inlet filter and the compressor inlet temperature. Step 3: Calculate the saturated vapor pressure of the air after the filter cartridge and at the compressor inlet, and the current vapor pressure of the air after the filter cartridge. Step 4: When the ratio of the current vapor pressure of the air after the filter cartridge to the saturated vapor pressure of the compressor inlet air is greater than or equal to 1 and the compressor inlet temperature is less than or equal to 273.15K, an anti-icing warning is issued. At this time, hot air should be introduced immediately. Step 5: Calculate the temperature of the mixed air after adding hot air; The calculation method takes the compressor inlet temperature as the starting temperature, and records the compressor inlet correction temperature every 1°C increase. When the corrected temperature at the compressor inlet is less than or equal to 273.15K, calculate the saturated vapor pressure of the current compressor inlet air. When the ratio of the current vapor pressure of the air after the filter cartridge to the saturated vapor pressure of the compressor inlet air is less than 1, the mixed air temperature is the sum of the corrected temperature at the compressor inlet and the temperature difference obtained in step 2. When the compressor inlet correction temperature is greater than 273.15K, the mixed air temperature is the sum of the compressor inlet correction temperature and the temperature difference obtained in step 2. Step 6: Calculate the mass of hot air input according to the heat absorption formula. Step 7: Gradually open the electric valve on the air bleed pipe and measure the real-time air bleed volume until it reaches the theoretical value of air bleed volume obtained in step 6. At the same time, measure the real-time absolute pressure, static pressure and real-time temperature to confirm that the real-time bleed air volume can meet the bleed air anti-icing needs.

3. The gas turbine bleed air anti-icing method according to claim 1, characterized in that: In step 2, the energy equation is: Flow rate after filter cartridge: Compressor flow rate: Compressor inlet temperature: Among them, A 滤筒后 , A 压气机进口 are the known inlet duct cross-sectional areas, in m 2 , Compressor inlet area unit: m 2 ;c p is the constant pressure heat capacity of air 1005 j / (kg·k); T is the temperature in K; ρ is the air density 1.293 kg / m 3 ;m 进气 is the air mass flow rate in kg / s; c is the air velocity in m / s; h is the air enthalpy in j.

4. The gas turbine bleed air anti-icing method according to claim 3, characterized in that: Temperature difference ΔT = T 滤筒后 -T 压气机进口 .

5. The gas turbine bleed air anti-icing method according to claim 1, characterized in that: In step six, the heat absorption formula is: m 混合 ×c p混合 ×T 混合 =m 引气 ×c p进气 ×T 引气 +(m 进气 -m 引气 )×c p进气 ×T 滤筒后 。 6. The gas turbine bleed air anti-icing method according to claim 1, characterized in that: In step 7, the formula for calculating the current real-time air intake volume is as follows: in: q=-0.8562×Ma 2 +1.9742×Ma-0.0237 Among them, P * , P, T * The total temperature and total pressure probes measure absolute pressure (Pa), static pressure (Pa), and temperature (K) in real time; A is the cross-sectional area of ​​the pipeline (m 2 ).

7. A bleed air anti-icing system, characterized in that: The bleed air anti-icing method according to claim 1 comprises an electric valve (1), a bleed air flow measurement section (2), a bleed air pipe (3), a bleed air injection branch pipe (4), and a spiral nozzle (5) which are arranged in sequence; the electric valve (1) is connected to the air outlet of the middle stage of the compressor.

8. The bleed air anti-icing system according to claim 7, characterized in that: A total temperature and total pressure probe (7) and a pipeline static pressure measuring point (8) are arranged on the bleed air flow measurement section (2).

9. The bleed air anti-icing system according to claim 8, characterized in that: The total temperature and total pressure probe (7) is located at a position 10 times the diameter of the bleed air flow measurement section (2) along the air intake direction.

10. The bleed air anti-icing system according to claim 8, characterized in that: A length of 5 times the diameter is reserved on the side of the total temperature and total pressure probe (7) facing the outflow direction of the airflow.

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