NL2024895A - System.and method for assessing fire hazard of typical oil in wind turbine nacelle - Google Patents
System.and method for assessing fire hazard of typical oil in wind turbine nacelle Download PDFInfo
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- NL2024895A NL2024895A NL2024895A NL2024895A NL2024895A NL 2024895 A NL2024895 A NL 2024895A NL 2024895 A NL2024895 A NL 2024895A NL 2024895 A NL2024895 A NL 2024895A NL 2024895 A NL2024895 A NL 2024895A
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- wind turbine
- oil
- nacelle
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- 238000000034 method Methods 0.000 title claims abstract description 47
- 239000003921 oil Substances 0.000 claims abstract description 118
- 238000011161 development Methods 0.000 claims abstract description 29
- 230000004907 flux Effects 0.000 claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 22
- 238000000197 pyrolysis Methods 0.000 claims abstract description 20
- 238000002485 combustion reaction Methods 0.000 claims abstract description 19
- 230000008569 process Effects 0.000 claims abstract description 18
- 238000012360 testing method Methods 0.000 claims description 54
- 239000000779 smoke Substances 0.000 claims description 37
- 238000004458 analytical method Methods 0.000 claims description 17
- 239000000446 fuel Substances 0.000 claims description 10
- 230000008033 biological extinction Effects 0.000 claims description 9
- 230000002265 prevention Effects 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- 238000012935 Averaging Methods 0.000 claims description 5
- 230000015556 catabolic process Effects 0.000 claims description 5
- 238000006731 degradation reaction Methods 0.000 claims description 5
- 239000012943 hotmelt Substances 0.000 claims description 4
- 238000012546 transfer Methods 0.000 claims description 4
- 238000009423 ventilation Methods 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- 239000011159 matrix material Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 7
- 238000000354 decomposition reaction Methods 0.000 claims 2
- 230000000977 initiatory effect Effects 0.000 claims 2
- 230000000903 blocking effect Effects 0.000 claims 1
- 230000008030 elimination Effects 0.000 claims 1
- 238000003379 elimination reaction Methods 0.000 claims 1
- 238000000605 extraction Methods 0.000 claims 1
- 230000017525 heat dissipation Effects 0.000 claims 1
- 238000009413 insulation Methods 0.000 claims 1
- 238000002955 isolation Methods 0.000 claims 1
- 230000003449 preventive effect Effects 0.000 claims 1
- 230000001629 suppression Effects 0.000 claims 1
- 238000002411 thermogravimetry Methods 0.000 claims 1
- 238000011160 research Methods 0.000 abstract description 5
- 238000013459 approach Methods 0.000 abstract description 2
- 239000007787 solid Substances 0.000 abstract description 2
- 239000004519 grease Substances 0.000 description 13
- 230000005855 radiation Effects 0.000 description 9
- 230000000875 corresponding effect Effects 0.000 description 6
- 239000010720 hydraulic oil Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000005094 computer simulation Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- RLQJEEJISHYWON-UHFFFAOYSA-N flonicamid Chemical compound FC(F)(F)C1=CC=NC=C1C(=O)NCC#N RLQJEEJISHYWON-UHFFFAOYSA-N 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 239000002937 thermal insulation foam Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D17/00—Monitoring or testing of wind motors, e.g. diagnostics
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
- F03D80/70—Bearing or lubricating arrangements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/50—Investigating or analyzing materials by the use of thermal means by investigating flash-point; by investigating explosibility
- G01N25/52—Investigating or analyzing materials by the use of thermal means by investigating flash-point; by investigating explosibility by determining flash-point of liquids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2260/00—Function
- F05B2260/80—Diagnostics
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2260/00—Function
- F05B2260/98—Lubrication
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
Abstract
The present invention relates to a system and method for assessing the fire hazards of typical oils in a wind turbine nacelle. A thermogravimetric analyzer is used to obtain key pyrolysis characteristic parameters of oils used in the wind turbine nacelle at<iifferent.heating'rates ineuiair atmosphere, and a cone calorimeter is used to obtain reaction—to—fire characteristic parameters and derived parameters under different radiant heat fluxes. The development process of a wind turbine nacelle fire is divided into five stages of ignition, growth, flashover, full development, and decay. Based.on the characteristics of different stages, such as the ignitionandpwrolysischaracteristics,heatandsmokerelease capabilities,andheatandsmokehazardcharacteristicsofoils, a three—layer structure system of fire hazard assessment is established.Thepresentinventioncharacterizesthepyrolysis and reaction—to—fire characteristics of main and typical fire loads (four oils) in the nacelle, and proposes a holistic approach to multi—scale correlations between pyrolysis and combustion. The present invention realizes the multiple assessment methods for the potential fire hazards throughout the whole operation process of a wind turbine. The present invention has a solid theoretical foundation as well as the advantages of simple<dperation, reliable results anclexcellent repeatability. The present invention provides a basis for the research and application of intrinsic safety in the wind turbine nacelle.
Description
TECHNICAL FIELD The present invention discloses a system and method for assessing fire hazards of typical oils in a wind turbine nacelle, and belongs to the technical field of safety in wind power generation.
BACKGROUND Among all kinds of new energy, the promising wind power is regarded as the most suitable for large-scale commercial development. With low cost, wind power generation has noticeable advantages and is widely concerned by countries around the world. As a latecomer in the wind power industry, China has developed rapidly in recent years. By the end of 2017, in China newly and cumulatively installed wind power capacities were 19.66 GW and 188.39 GW, respectively, ranking first in the world. The wind turbine usually consists of a bottom of foundation, a tower, a nacelle and several blades. The nacelle is generally as high as tens or even hundreds of meters. The nacelle usually has a confined room, narrow interior and complicated structure. As the core of the wind turbine, the nacelle accommodates expensive electrical equipment such as generator, variable-frequency cabinet, control cabinet, braking system, vaw system, gearbox and hydraulic system, etc. Accordingly, the nacelle contains diverse types and phases of flammables and combustibles such as transformer oil, gearbox oil, hydraulic oil, grease and sound insulation foam, which pose great fire hazards. When a fire occurs in the nacelle, the fire will grow and spread rapidly. As there are no much effective and feasible fire prevention and control techniques at present,
it is difficult to carry out the fire extinguishing and rescue work in the nacelle in time, which often leads to the burnout of the whole nacelle or other important components. In addition, the cost of subsequent repair is very high, which is basically equivalent to that of an original wind turbine. Diverse oils as the heavy fire loads inside the nacelle are most likely to be the initial or subsequent involved combustibles in a nacelle fire. A wind turbine nacelle usually holds substantial quantities of flammable oils. For example, in a single 1.5 MW wind turbine, up to 900 L of cooling and cleaning grease is stored inside the nacelle; and a single 8 MW wind turbine can easily contain 200 L of grease, 1100 L of hydraulic oil, 2000 L of gearbox oil and 3000 kg of transformer oil. According to incomplete statistics from the British Caithness Windfarm Information Forum (Caithness Windfarm Information Forum. Summary of wind turbine accidents data to 31 December 2017. Available online: <http://www.caithnesswindfarms.co.uk/AccidentStatistics.ht m>), by the end of 2017, among the 2191 wind turbine accidents reported and confirmed worldwide, there were nearly 318 fires (14.5%), rating second after blade failure (17.2 %). As the global wind power industry is experiencing a period of booming development, there is a growing trend of wind turbine fires due to increasing mass installations of wind power equipment. Thus, the fire prevention in the wind turbine nacelle has become the most important issue that needs to be solved urgently. After all, once a fire happens in a wind turbine, it is irreversible. To prevent and extinguish the wind turbine nacelle fire effectively, the key is to predict the potential fire hazards by exploring changes in the combustion performance parameters of fuels during the development of the nacelle fire.
In fire science research the two most important methods of physical model test and numerical simulation experiments are developed. Currently, in terms of multiple problems involved in the wind turbine nacelle, such as heavy fire loads, various types of fuels, and complex ventilation and space structure, etc., it is difficult to conduct the full-scale experimentaltest. There are also many other problems which reguire solutions. Full-scale tests of simulated and approximate wind turbine nacelles have been conducted by Tianjin Fire Research Institute and Taiwan Police College in China early, to investigate the fire characteristics of the wind turbine nacelle and corresponding fire protection system. However, in their experiments, the simple layout inside the nacelle and design of the fire source were used, which differ greatly with those in the real fire scenarios. These full-scale tests are also very expensive and difficult to carry out. The computer simulation of fire development has received greater attention in recent years, which has unique advantages of saving time and costs, and obtaining the details of physical parameters, etc. Nevertheless, due to the complexity, non-linearity and randomness in the real fire processes, the accurate simulations of the combustion processes have not been completely realized by using current techniques.
SUMMARY The present invention proposes a system and method for assessing fire hazards of typical oils in a wind turbine nacelle. The combustion of different phases of oils is the most probable and harmful fire hazard of a wind turbine nacelle, but there is no effective simulation, warning and prevention technique to deal with a fire cause by oil. For this reason, the present invention proposes a method for comprehensively assessing a fire hazard of a typical-phase oil in a wind turbine nacelle by testing a parameter of fire development by a thermogravimetric analyzer and a cone calorimeter.
The present invention has the following technical solutions.
A system for assessing fire hazards of typical oils in a wind turbine nacelle, including a thermogravimetric characteristic assessment unit and a reaction-to-fire characteristic assessment unit, where the thermogravimetric characteristic assessment unit includes a thermogravimetric analyzer, which is used to obtain an important pyrolysisparameter of an oil sample at different heating rates, such as an onset degradation temperature T ser” a maximum mass loss rate MLRuax, a corresponding maximum temperature Tas and a mass fraction of residue at different end pyrolysis temperatures; 3 the reaction-to-fire characteristic assessment unit includes a cone calorimeter, which is used to obtain a combustion characteristic parameter of the oil sample under different radiant heat fluxes, such as a time to ignition tig, a heat release rate HRR, a mass loss rate MLR, a specific extinction area SEA and a smoke release rate SRR; the fire hazard of the typical-phase oil in the wind turbine nacelle can be comprehensively assessed by the obtained data.
A method for assessing fire hazards of typical oils in a wind turbine nacelle by using the above system, including the following steps: (a) preparation of oil: preparing different types of oil samples from the wind turbine nacelle, and simulating a development process of a wind turbine nacelle fire at different heating rates and different external thermal radiant heat fluxes; {(b) test and analysis of thermogravimetric behavior and characteristic: testing a thermogravimetric behavior and characteristic of four oil samples at different heating rates in an air atmosphere by a thermogravimetric analyzer, and analyzing a thermogravimetric = differential thermogravimetric (TG-DTG) curve to obtain an onset degradation temperature Toner” a maximum mass loss rate MLRmax, a corresponding maximum temperature Tax? a mass fraction of residue at different end pyrolysis temperatures, a heat release rate HRR, a mass loss rate MLR, a specific extinction area SEA and a smoke release rate HRR of the four oil samples at different heating rates; (c) test and analysis of fire reaction-to-fire behavior and characteristic: testing a fire reaction-to-fire behavior andcharacteristic of the four oil samples under different external thermal radiant heat fluxes by a cone calorimeter according to the ISO 5660-1 standard, and obtaining a time to ignition tig; a heat release rate HRR, a mass loss rate MLR, a specific 9 extinction area SEA and a smoke release rate SRR of the four oil samples under different radiant heat fluxes; and (d) comprehensive analysis: dividing the simulated development process of the wind turbine nacelle fire into different stages, establishing a scientific and effective fire hazard assessment indicator system according to a principle and characteristic of fire development at each stage, and obtaining a result of comprehensive analysis of the fire hazard of the typical oil in the wind turbine nacelle based on the assessment indicator system, specifically including: (1) division of fire development stages; (2) establishment of fire protection function assessment indicator system; and (3) fire hazard assessment.
The test and analysis of thermogravimetric behavior and characteristic in step (b) further includes: comparing a TG curve with a corresponding DTG curve at different heating rates, and observing whether the maximum mass loss rates on the DTG curve coincides; indicating that apyrolysis process is clearly distinguished if the maximum mass loss rates are staggered, and choosing an onset degradation temperature 1 at the highest heating rate, a maximum mass loss rate MIR, a corresponding maximum temperature T and a mass fraction of residue at different end pyrolysis temperatures as parameters to develop an assessment indicator system.
The test and analysis of fire reaction-to-fire behavior and characteristic in step (c) further includes: obtaining a time to ignition of the four oil samples under different radiant heat fluxes, and applying the following equations to obtain a critical radiant heat flux q. a thermal inertia ApC andan ignition temperature TZ, of the oil samples.
0.55 or ApC q,=q. | 1+0.73| —=— (1) pO _ 4 gd der - H, (7, T,)+o (I; T, ) (2) In the equations, q. is an external radiant heat flux, h, is a heat transfer coefficient of an ignition surface, H, is a convection heat transfer coefficient, T is an ambient temperature, and O is a Stefan-Boltzmann constant, 5.67 x 107% kW/m2 * K*, The test and analysis of fire reaction-to-fire behavior and characteristic in step (¢) further includes: pletting a time-varying curve of a heat release rate HRR, a mass loss rate MLR, a specific extinction area SEA and a smoke release rate HRR of the four oil samples under different radiant heat fluxes; averaging the parameters by an integral averaging method, and substituting the average into equations (3) to (6) to further obtain a reaction-to-fire characteristic derived parameter such as an effective combustion heat AH, gy @n average smoke yield Y, and a smoke point height SPH of the oil samples. Equations (3) to (6) are as follows: AH, _9 (3) €, Am —_— . -3 ¥,=0.0994x 10° SEA, (4)
0.084(S+1) SPH= JL 5) Ys Mey =3 (6) S+1 In the equations, 0 is a total heat release rate; Am isa total mass loss of the sample; SEA, is an average SEA; and § is a stoichiometric mass air to fuel ratio.
The division of fire development stages in step (1) includes: setting a fire scenario based on fire dynamics and 3 characteristics of different stages in the development process of a wind turbine nacelle fire, and qualitatively dividing the wind turbine nacelle fire into five stages from the perspective of fire protection countermeasures according to a change in an average temperature and heat release rate over time in a confined ignition space in the nacelle before and after a nacelle material reaches a fire resistance rating.
The five stages include an incipient stage, a growth stage, a flashover stage, a full development stage and a decay stage.
The incipient stage features low overall heat release rate, low average temperature in the nacelle and local high temperature near an ignition object.
In the growth stage, the fire expands to ignite a surrounding combustible, and the average temperature in the nacelle increases rapidly from the ambient temperature to several hundred degrees Celsius.
During the flashover stage, the surface of all combustibles in the nacelle is burned, the average temperature usually rises above 600°C, and the flame basically fills the global space.
In the full development stage, the heat release rate in the nacelle gradually reaches the maximum, and the average temperature usually rises above 800°C.
The combustion is controlled by ventilation.
The overall bearing capacity of the nacelle structure is sharply reduced, and the nacelle can be burned through.
The fire can burn and spread at the same time inside and outside the nacelle, and may cause collapse in severe cases.
In the decay stage, the overall heat release rate gradually decreases, the combustibles inside and outside the nacelle are reduced until they are depleted, and the temperature begins to drop to the ambient temperature, The decay stage is generally considered to start from the average temperature in the nacelle which decreases to about 80% of a peak temperature.
The establishment of fire protection function assessmentindicator system in step (2) includes: developing an assessment indicator system of fire protection function throughout the whole process of the wind turbine fire, as follows: 1) indicators of ignition and thermal performance of oil, including a critical radiant heat flux q.. a thermal inertia ApC, an ignition temperature Te an effective combustion heat AH jp and a stoichiometric mass air to fuel ratio §; 2) indicators of heat and smoke release capability of oil, including a hot melt Rockwell hardness C (HRC), an average smoke yield y and a smoke point height SPH, where the hot melt HRC is calculated as follows: HRC = —| — —= 7) M, dt max B where, M, is an initial mass of the oil sample in a dm thermogravimetric test; is a maximum mass loss rate dt max of the oil sample in the thermogravimetric test; p is a heating rate of the oil sample in the thermogravimetric test; and 3) combined indicators of fire and smoke hazards during the fire spread, including a fire hazard parameter (FHP) and a smoke parameter (SP), which are calculated as follows:
HRR FHP — Max (8) Í, 2
SEA SRR SP = —— eeen (3) AH, HRR tabulating or plotting with the assessment indicators calculated above to obtain a result of comprehensive assessment of the fire hazard of the typical-phase oil in the wind turbine nacelle.
The present invention has the following beneficial effects: 1) The present invention overcomes shortcomings like high cost, long cycle, great workload and low accuracy in the experimental tests, computer simulation and other traditional fire research methods. The present invention characterizes the pyrolysis and reaction-to-fire characteristics of main and typical fire loads (four oils) in the wind turbine nacelle by means of the material characterizations, which realizes the potential fire hazards throughout the whole operation process of a wind turbine. The present invention has solid theoretical foundations as well as the advantages of low costs, fast and simple operations, reliable results and excellent repeatability. 2) The conventional fire hazard assessment method for polymer materials has an apparent problem, namely it relies only on a single indicator of reaction-to-fire characteristics, such as the peak heat release rate (PkHRR) or very few combined indicators, such as the fire performance index (FPI). The present invention enriches the assessment indicators and includes the parameters of critical heat flux for ignition, thermal inertia and ignition temperature. The present invention combines the derived parameters of reaction-to-fire characteristic like the effective combustion heat, the average smoke yield and the smoke point height with the pyrolysis characteristic parameters. In this way, the present invention proposes a holistic approach to multi-scale correlations between pyrolysis and combustion in the whole development process of a wind turbine nacelle fire, and amulti-dimensional and diversified assessment indicator system is established. 3) The present invention provides a basis for the research and application of intrinsic safety in the wind turbine nacelle, and enhances overall safety protection for the long-term healthy development of wind power industry.
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a flowchart of a method for assessing fire hazards of typical oils in a wind turbine nacelle.
FIG. 2 is a structural diagram of a system for assessing fire hazards of typical cils in a wind turbine nacelle.
FIG. 3 is a diagram showing a development stage of a wind turbine nacelle fire and a major fire characteristic parameter involved in fire prevention and disposal.
FIG. 4 shows a thermogravimetric - differential thermogravimetric (TG-DTG) curve of four test oils at different heating rates.
FIG. 5 shows a fitting relationship between ry and a radiation intensity of four test oils.
FIG. 6 shows a heat and smoke-combined hazard indicator.
DETAILED DESCRIPTION The technical solutions of the present invention are described in further detail below with reference to the accompanying drawings.
As shown in FIG. 1 and FIG. 2, the present invention provides a method and system for comprehensively assessing a fire hazard of a typical-phase oil in a wind turbine nacelle based on a pyrolysis characteristic parameter and a reaction-to-fire characteristic parameter c¢btained by a thermogravimetric analyzer and a cone calorimeter.
An on-site investigation was carried out, and a transformer oil, a hydraulic oil, a gearbox oil and a grease were collected from a nacelle of an 850 kW wind turbine in a wind farm as representative oil samples. The basic physical properties of the four test oils are shown in Table 2. Table 2 Physical properties of four test oils Gearbox Transformer Hydraulic Grease oil oil oil Phase Liquid Liquid Liquid Semisolid Density 860 kg/m: ££ 895 kg/m? 875 kg/m? 860-980 (15°C), (20°Cy, (15°C) kg/m? ASTM D4052 GB/T 1884-1885
Boiling > 316°C 192°C > 280°C > 400°C point Flash 242°C 159°C 208°C > 300°C point {Cleveland open cup COC) A pyrolysis characteristic test of the four oil samples was performed in an air atmosphere by a thermogravimetric characteristic assessment unit, namely a Q5000 IR-type thermogravimetric analyzer (TA Corporation, the USA). Before the test, a 10.0-30.0 mg oil sample was weighed with an electronic balance and dropped into an aluminum crucible through a pipette. During the test, a heating rate was set to 5°C/min, 10°C/min, 20°C/min and 40°C/min, and a heating temperature ranged from room temperature to 800°C.
A comparative analysis showed that an adjacent thermogravimetric plateau on different TG curves was clearly distinguished. Therefore, pyrolysis characteristic data at the heating rate of 40°C/min were selected as parameters to be correlated to develop the assessment indicator system. FIG. 4 shows the TG-DTG curves of the four oil samples at the heating rate of 40°C/min.
The TG-DTG curves at the heating rate of 40°C/min were analyzed to obtain important pyrolysis parameters of the four oil samples, such as an onset degradation temperature (1. a maximum mass loss rate (MLRmax), a corresponding maximum temperature Toa and a residue mass fraction under a pyrolysis temperature 500°C, as shown in Table 3.
Table 3 Summary of pyrolysis characteristic data of four test oils Fuel Tonset (°C) MLRmax (% / °C) / Taax Residue (3%), (°C) 500°C Gearbox oil 302 0.92/350 3.79
Transformer 201 1.62/282 0.84 oil Hydraulic 293 1.59/368 1.33 oil Grease 289 0.88/471 11.10 A combustion characteristic test of the four oil samples was performed by using a reaction-to-fire characteristic assessment unit, namely a cone calorimeter (Fire Testing Technology, the UK). Before the test, a 40 ml oil sample was measured with a measuring cylinder and poured into a double oil pan.
During the test, a radiation intensity was set to 15 kW/m2, 25 kW/m?, 35 kW/m?, 50 kW/m? and 75 kW/m? in this order.
For safety, all oils were tested within a lower radiation intensity range (15-35 kW/m?), and then an oil sample resistant to high temperature radiation was tested under a higher radiation intensity (50 kW/m? and 75 kW/m?) . The test found that a suitable test radiation intensity range for the transformer oil, the hydraulic oil and the gearbox oil was 15-35 kW/m?, and a suitable test radiation intensity range for the grease resistant to high temperature radiation was 25-75 kW/m2. A time to ignition (Ly) (reaction-to-fire characteristic parameter) was substituted into equations (1) and (2) to obtain a reaction-to-fire characteristic derived parameter of the oil samples such as a critical radiant heat flux (Gi), a thermal inertia (ApC) and an ignition temperature Te). The data are shown in Table 4, Table 4 Reaction-to-fire characteristic derived parameters obtained by equations (1) and (2) Fuel qr (kW/m?) AoC (kW2e 5 / mie K2) T, (°C) Transformer 5.8 0.3 216 oil
Hydraulic 7.1 0.2 246 oil Gearbox oil 10.4 0.06 309 Grease 12.3 0.09 338 The critical radiant heat flux (qr) was obtained by plotting with ti” and the external radiation intensity, performing a linear fit, and extrapolating a fitted straight line, as shown 9 in FIG. 5.
A heat release rate (HRR), a mass loss rate (MLR) and a specific extinction area (SEA) (reaction-to-fire characteristic parameters) were substitutedinto equations (3) to (6) to obtain a reaction-to-fire characteristic derived parameter of the oil samples such as an effective combustion heat CAH, 0), an average smoke yield (V,) and a smoke point height (SPH), as shown in Table 5.
Table 5 Reaction-to-fire characteristic derived parameters obtained by equations (3) to (6) Fuel AH, S v. (9/9) SPH (mm) (kJ/g) Transformer 20.7-23.5 5.9-6.8 0.010-0.030 22-57 oil Hydraulic 13.5-18.7 3.5-5.2 0.030-0.042 9-18 oil Gearbox oil 16.9-24,0 4.6-7.0 0.023-0.027 19-25 Grease 12.0-17.7 3.0-4,9 0.028-0.045 10-12 The development process of a wind turbine nacelle fire was divided into five stages: incipient stage, growth stage, flashover stage, full development stage and decay stage. Fire characteristics, including ignitability, flammability, flame spread and heat release were extracted, which should be paid special attention in the prevention and disposal of the windturbine nacelle fire.
The above pyrolysis characteristic parameters, reaction-to-fire characteristic parameters and derived parameters of the four test oils were substituted into equations (7) to (9) to establish a wind turbine nacelle fire protection function assessment indicator system. The assessment indicator system covered the entire process of the wind turbine nacelle fire, and included 1) indicators of ignition and thermal performance of oil, 2) indicators of heat and smoke release capability of oil and 3) combined indicators of fire and smoke hazards during the fire spread, which are shown in Table 6, Table 7 and FIG. 6, respectively.
Table 6 Indicators of ignition and thermal performance of oil Puel dn ApC (kW? s T, IN S (kW/m?) / mie K?) (°C) (kd/q) Transformer 5.8 0.3 216 20.7-23.5 5.9-6.8 oil Hydraulic 7.1 0.2 246 13.5-18.7 3.5-5.2 oil Gearbox oil 10.4 0.06 309 16.9-24.0 4.6-7.0 Grease 12.3 0.09 338 12.0-17.7 3.0-4.9 Table 7 Heat release and smoke release indicators of oil Fuel HRC (kJ/ge*K) ¥. (9/9) SPH (mm) Transformer 0.043-0.048 0.010-0.030 22-57 oil Hydraulic 0.027-0.038 0.030-0.042 9-18 oil Gearbox oil 0.020-0.028 0.023-0.027 19-25 Grease 0.014-0.020 0.028-0.045 10-12 The original data were imported into an assessment indicator data acquisition unit and processed by equations (1) to (9)
through commercial software like Origin or matrix laboratory (MATLAB) using a first derivative method and an integral averaging method, thereby obtaining the actual data of each assessment indicator of the oil samples.
FIG. 6 shows that the transformer oil had the highest fire hazard parameter (FHP), the grease had the highest smoke parameter (SP), and the gearbox oil and the hydraulic oil had medium FHP and SP.
Therefore, the fire hazard of the transformer oil and the grease is higher in an actual fire development process, and special precautions should be taken.
Claims (10)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910118829.4A CN109781771A (en) | 2019-02-15 | 2019-02-15 | Typical oil fire hazard assessment system and its evaluation method in wind-power engine room |
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| US20020080849A1 (en) * | 2000-12-22 | 2002-06-27 | Lyon Richard E. | Heat release rate calorimeter for milligram samples |
| US20130309088A1 (en) * | 2012-05-15 | 2013-11-21 | Clipper Windpower, Llc | Method for Protecting Wind Turbine Equipment in Fire Event |
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| JPH1135950A (en) * | 1996-12-26 | 1999-02-09 | Mitsubishi Heavy Ind Ltd | Process for generation of electric power and power generation apparatus |
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| CN102879428B (en) * | 2012-09-29 | 2014-09-10 | 南京工业大学 | Combustible gas explosion venting harm effect testing device and analytical method |
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| CN107808028B (en) * | 2017-09-15 | 2022-11-18 | 中国核电工程有限公司 | Analysis method for calculating fire influence range |
| CN109187634A (en) * | 2018-08-22 | 2019-01-11 | 南京林业大学 | Bituminous pavement Thermal Decomposition Mechanism research method under a kind of fire working |
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| US20020080849A1 (en) * | 2000-12-22 | 2002-06-27 | Lyon Richard E. | Heat release rate calorimeter for milligram samples |
| US20130309088A1 (en) * | 2012-05-15 | 2013-11-21 | Clipper Windpower, Llc | Method for Protecting Wind Turbine Equipment in Fire Event |
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| SUN WEI ET AL: "Pyrolysis Properties and Kinetics of Typical Liquid Oils in Wind Turbine Nacelle", PROCEDIA ENGINEERING, ELSEVIER BV, NL, vol. 211, 7 February 2018 (2018-02-07), pages 668 - 673, XP085414100, ISSN: 1877-7058, DOI: 10.1016/J.PROENG.2017.12.062 * |
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| CN109781771A (en) | 2019-05-21 |
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