Since the first batch of 350-MW supercritical utility boilers was put into operation, the exhaust flue gas temperature of the boilers has always been higher than the designed value. The main reason is that the heat ab...Since the first batch of 350-MW supercritical utility boilers was put into operation, the exhaust flue gas temperature of the boilers has always been higher than the designed value. The main reason is that the heat absorbed by the air heater is not sufficient. In Huaneng Dongfang Power Plant, the exhaust flue gas temperature is lowered through modifications to the economizer and the air heater. The experimental results reveal that every year, each boiler could save 3 850 tons of standard coal and reduce 85 tons of SO2 and 9 000 tons of CO2 respectively after retrofit.展开更多
<span style="font-family:Verdana;">The objective of this study was to investigate performance characteristics of a spark ignition engine, particularly, the correlation between performance, exhaust gas ...<span style="font-family:Verdana;">The objective of this study was to investigate performance characteristics of a spark ignition engine, particularly, the correlation between performance, exhaust gas temperature and speed, using Kiva4. Test data to validate kiva4 si</span><span style="font-family:Verdana;">mulation</span><span style="font-family:Verdana;"> results were conducted on a 3-cylinder, four-stroke Volkswagen (</span><span style="font-family:Verdana;">VW) Polo 6 TSI 1.2 gasoline engine. Three different tests were, therefore, carried out. In one set, variations in exhaust gas temperature were studied by varying the engine load, while keeping the engine speed constant. In another test, exhaust gas temperature variations were studied by keeping the engine at idling whilst varying the speeds. A third test involved studying variations in exhaust gas temperature under a constant load with variable engine speeds. To study </span><span style="font-family:Verdana;">variations in exhaust gas temperatures under test conditions, a basic grid/</span><span style="font-family:Verdana;">mesh generator, K3PREP, was employed to write an itape17 file comprising of a 45</span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">°</span><span> <span style="font-family:Verdana;">asymmetrical mesh. This was based on the symmetry of the combustion ch</span><span style="font-family:Verdana;">amber of </span><span style="font-family:Verdana;">the engine used in carrying out experimental tests. Simulati</span><span style="font-family:Verdana;">ons were therefore p</span><span style="font-family:Verdana;">erformed based on the input parameters established in</span><span style="font-family:Verdana;"> the conducted tests. Simulations with the kiva4 code showed a significant predictability of the performance characteristics of the engine. This was evident in the appreciable agreement obtained in the simulation results when compared </span><span style="font-family:Verdana;">with the test data, under the considered test conditions. A percentage error, be</span><span style="font-family:Verdana;">tween experimental results and results from simulations with the kiva4 code of only between 2% to 3% was observed.</span></span></span></span></span>展开更多
The prediction of Exhaust Gas Temperature Margin(EGTM)after washing aeroengines can provide a theoretical basis for airlines not only to evaluate the energy-saving effect and emission reduction,but also to formulate r...The prediction of Exhaust Gas Temperature Margin(EGTM)after washing aeroengines can provide a theoretical basis for airlines not only to evaluate the energy-saving effect and emission reduction,but also to formulate reasonable maintenance plans.However,the EGTM encounters step changes after washing aeroengines,while,in the traditional models,a persistence tendency exists between the prediction results and the previous data,resulting in low accuracy in prediction.In order to solve the problem,this paper develops a step parameters prediction model based on Transfer Process Neural Networks(TPNN).Especially,“step parameters”represent the parameters that can reflect EGTM step changes.They are analyzed in this study,and thus the model concentrates on the prediction of step changes rather than the extension of data trends.Transfer learning is used to handle the problem that few cleaning records result in few step changes for model learning.In comparison with Long Short-Term Memory(LSTM)and Kernel Extreme Learning Machine(KELM)models,the effectiveness of the proposed method is verified on CFM56-5B engine data.展开更多
The main technologies for reducing flue gas heat loss of pulverized coal-fired boilers are introduced, and the suitability of these technologies for boiler operation and the principles for selection of these technolog...The main technologies for reducing flue gas heat loss of pulverized coal-fired boilers are introduced, and the suitability of these technologies for boiler operation and the principles for selection of these technologies are explored. The main conclusions are: 1) the non-equilibrium control over flue gas flow rates at the inlet of the air heater and the reversal rotation of the air heater rotator should be popularized as regular technologies in large boilers; 2) increasing the area of the air heater to reduce the flue gas heat loss in pulverized coal-fired boilers should be the top option and increasing the area of the economizer be the next choice; 3) low- pressure economizer technology could save energy under special conditions and should be compared with the technology of increasing economizer area in terms of technical economics when the latter is feasible; 4) the hot primary air heater is only suitable to the pnlvefizing system with a large amount of cold air mixed.展开更多
以一起V2500-A5发动机排气温度(Exhaust Gas Temperature,EGT)的真实超限故障为切入点,阐述了影响发动机EGT的因素,以及发动机各主要部件对EGT的影响程度。通过发动机监控系统和原理分析锁定故障源,以期为同类故障的快速处置和排除提供...以一起V2500-A5发动机排气温度(Exhaust Gas Temperature,EGT)的真实超限故障为切入点,阐述了影响发动机EGT的因素,以及发动机各主要部件对EGT的影响程度。通过发动机监控系统和原理分析锁定故障源,以期为同类故障的快速处置和排除提供参考。展开更多
In this study, n-butanol-diesel blends were burned in a turbo-charged, direct injection diesel engine where the brake thermal efficiency, (BTE) or brake specific fuel consumption, (BSFC) was compared with that of etha...In this study, n-butanol-diesel blends were burned in a turbo-charged, direct injection diesel engine where the brake thermal efficiency, (BTE) or brake specific fuel consumption, (BSFC) was compared with that of ethanol-diesel or methanol-diesel blends in another study by other authors. The test blends used were B5, B10 and B20 (where B5 is 5% n-butanol by volume and 95% diesel fuel-DF). In this study, the BTE was higher and the BSFC improved more than in the other study. Because of improved BTE with increasing brake mean effective pressure, BMEP, the BSFC reduced, however the increased shared volume of n-butanol in DF increased BSFC. Adding n-butanol in DF slightly derated the torque, brake power output with increasing speed, and caused a fall in exhaust gas temperatures, (EGT) which improves the volumetric efficiency and reduces compression work. Therefore, a small-shared volume of n-butanol in DF fired in a turbo-charged diesel engine performs better in terms of BTE and BSFC than that of ethanol or methanol blending in DF.展开更多
This work evaluates the performance optimization of heat recovery steam generator system in Afam VI power plant, Rivers State. Nigeria. Steady state monitoring and direct collection of data from the plant was performe...This work evaluates the performance optimization of heat recovery steam generator system in Afam VI power plant, Rivers State. Nigeria. Steady state monitoring and direct collection of data from the plant was performed including logged data for a period of 12 months. The data were analysed using various energy equations. Hysys software was used to model the temperature across the heating surfaces, and MATLAB software was used to determine the heat transfer coefficient, heat duties, steam flow, effectiveness of the HRSG. The optimization technique was carried out by varying the exhaust gas flow, exhaust gas temperature, steam pressure and the theoretical introduction of duct burner for supplementary firing. The results show that between 490℃ and 526℃, the percentage increase in the overall heat absorbed in the HRSG is 37.39%. It also show that for an increase in the exhaust gas mass flow by 80 kg/s, the steam generation increase by 19.29% and 18.18% for the low and high pressure levels respectively. The overall result indicates an improvement in the HRSG energy efficiency and steam generation. As the exhaust gas mass flow and temperature increases, the steam generation and system effectiveness greatly improved under the various considerations, which satisfy the research objective.展开更多
The reasons of introducing cold air into pulverizer are analyzed for boilers with large capacity and high parameters. The temperature rises of the exhaust gas are calculated when varying the amount of the cold air. Th...The reasons of introducing cold air into pulverizer are analyzed for boilers with large capacity and high parameters. The temperature rises of the exhaust gas are calculated when varying the amount of the cold air. The hot primary air heater, a new technology, is developed to eliminate the cold air from the pulverized coal system. The applications, advantages and disadvantages are introduced in detail for the new device and system. It is concluded that introducing cold air into pulverizer is one of the major factors that causes the exhaust gas temperature of boilers with large capacity to be high. The amount of the cold air could be reduced signif icantly, even to zero in some cases by adopting the hot primary air heater, which drops the exhaust gas temperature of the boiler effectively. The hot primary air heater, which could play part roles of the steam-air heater or the hot air recirculation system, could also be used to adjust the exhaust gas temperature within the range of 20 ℃ by controlling the flow rate of the cooling medium. Moreover, the startup period of the steam-air heater or the hot air recirculation system will be shortened, which is a unique advantage of the hot primary air heater among the measures to drop the exhaust gas temperature.展开更多
The reliability of the on-wing aircraft Auxiliary Power Unit(APU)decides the cost and the comfort of flight to a large degree.The most important function of APU is to help start main engines by providing compressed ai...The reliability of the on-wing aircraft Auxiliary Power Unit(APU)decides the cost and the comfort of flight to a large degree.The most important function of APU is to help start main engines by providing compressed air.Especially on the condition of sudden shutdown in the air,APU can offer additional thrust for landing.Therefore,its condition monitoring has drawn much attention from the academic and industrial field.Among the on-wing sensing data which can reflect its condition,Exhaust Gas Temperature(EGT)is one of the most important parameters.To ensure the reliability of EGT,one kind of data-driven anomaly detection framework for EGT sensing data is proposed based on the Gaussian Process Regression and Kernel Principal Component Analysis.The situations of one-dimensional and two-dimensional input data for EGT anomaly detection are considered,respectively.The cross-validation experiments are carried out by utilizing the real condition data of APU,which are provided by China Southern Airlines Company Limited Shenyang Maintenance Base.The anomalous stuck condition of EGT sensing data is also detected.Experimental results show that the proposed EGT sensing data anomaly detection method can achieve better performance of false positive ratio,false negative ratio and accuracy.展开更多
文摘Since the first batch of 350-MW supercritical utility boilers was put into operation, the exhaust flue gas temperature of the boilers has always been higher than the designed value. The main reason is that the heat absorbed by the air heater is not sufficient. In Huaneng Dongfang Power Plant, the exhaust flue gas temperature is lowered through modifications to the economizer and the air heater. The experimental results reveal that every year, each boiler could save 3 850 tons of standard coal and reduce 85 tons of SO2 and 9 000 tons of CO2 respectively after retrofit.
文摘<span style="font-family:Verdana;">The objective of this study was to investigate performance characteristics of a spark ignition engine, particularly, the correlation between performance, exhaust gas temperature and speed, using Kiva4. Test data to validate kiva4 si</span><span style="font-family:Verdana;">mulation</span><span style="font-family:Verdana;"> results were conducted on a 3-cylinder, four-stroke Volkswagen (</span><span style="font-family:Verdana;">VW) Polo 6 TSI 1.2 gasoline engine. Three different tests were, therefore, carried out. In one set, variations in exhaust gas temperature were studied by varying the engine load, while keeping the engine speed constant. In another test, exhaust gas temperature variations were studied by keeping the engine at idling whilst varying the speeds. A third test involved studying variations in exhaust gas temperature under a constant load with variable engine speeds. To study </span><span style="font-family:Verdana;">variations in exhaust gas temperatures under test conditions, a basic grid/</span><span style="font-family:Verdana;">mesh generator, K3PREP, was employed to write an itape17 file comprising of a 45</span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">°</span><span> <span style="font-family:Verdana;">asymmetrical mesh. This was based on the symmetry of the combustion ch</span><span style="font-family:Verdana;">amber of </span><span style="font-family:Verdana;">the engine used in carrying out experimental tests. Simulati</span><span style="font-family:Verdana;">ons were therefore p</span><span style="font-family:Verdana;">erformed based on the input parameters established in</span><span style="font-family:Verdana;"> the conducted tests. Simulations with the kiva4 code showed a significant predictability of the performance characteristics of the engine. This was evident in the appreciable agreement obtained in the simulation results when compared </span><span style="font-family:Verdana;">with the test data, under the considered test conditions. A percentage error, be</span><span style="font-family:Verdana;">tween experimental results and results from simulations with the kiva4 code of only between 2% to 3% was observed.</span></span></span></span></span>
基金supported by the National Natural Science Foundation of China(No.1733201)。
文摘The prediction of Exhaust Gas Temperature Margin(EGTM)after washing aeroengines can provide a theoretical basis for airlines not only to evaluate the energy-saving effect and emission reduction,but also to formulate reasonable maintenance plans.However,the EGTM encounters step changes after washing aeroengines,while,in the traditional models,a persistence tendency exists between the prediction results and the previous data,resulting in low accuracy in prediction.In order to solve the problem,this paper develops a step parameters prediction model based on Transfer Process Neural Networks(TPNN).Especially,“step parameters”represent the parameters that can reflect EGTM step changes.They are analyzed in this study,and thus the model concentrates on the prediction of step changes rather than the extension of data trends.Transfer learning is used to handle the problem that few cleaning records result in few step changes for model learning.In comparison with Long Short-Term Memory(LSTM)and Kernel Extreme Learning Machine(KELM)models,the effectiveness of the proposed method is verified on CFM56-5B engine data.
文摘The main technologies for reducing flue gas heat loss of pulverized coal-fired boilers are introduced, and the suitability of these technologies for boiler operation and the principles for selection of these technologies are explored. The main conclusions are: 1) the non-equilibrium control over flue gas flow rates at the inlet of the air heater and the reversal rotation of the air heater rotator should be popularized as regular technologies in large boilers; 2) increasing the area of the air heater to reduce the flue gas heat loss in pulverized coal-fired boilers should be the top option and increasing the area of the economizer be the next choice; 3) low- pressure economizer technology could save energy under special conditions and should be compared with the technology of increasing economizer area in terms of technical economics when the latter is feasible; 4) the hot primary air heater is only suitable to the pnlvefizing system with a large amount of cold air mixed.
文摘In this study, n-butanol-diesel blends were burned in a turbo-charged, direct injection diesel engine where the brake thermal efficiency, (BTE) or brake specific fuel consumption, (BSFC) was compared with that of ethanol-diesel or methanol-diesel blends in another study by other authors. The test blends used were B5, B10 and B20 (where B5 is 5% n-butanol by volume and 95% diesel fuel-DF). In this study, the BTE was higher and the BSFC improved more than in the other study. Because of improved BTE with increasing brake mean effective pressure, BMEP, the BSFC reduced, however the increased shared volume of n-butanol in DF increased BSFC. Adding n-butanol in DF slightly derated the torque, brake power output with increasing speed, and caused a fall in exhaust gas temperatures, (EGT) which improves the volumetric efficiency and reduces compression work. Therefore, a small-shared volume of n-butanol in DF fired in a turbo-charged diesel engine performs better in terms of BTE and BSFC than that of ethanol or methanol blending in DF.
文摘This work evaluates the performance optimization of heat recovery steam generator system in Afam VI power plant, Rivers State. Nigeria. Steady state monitoring and direct collection of data from the plant was performed including logged data for a period of 12 months. The data were analysed using various energy equations. Hysys software was used to model the temperature across the heating surfaces, and MATLAB software was used to determine the heat transfer coefficient, heat duties, steam flow, effectiveness of the HRSG. The optimization technique was carried out by varying the exhaust gas flow, exhaust gas temperature, steam pressure and the theoretical introduction of duct burner for supplementary firing. The results show that between 490℃ and 526℃, the percentage increase in the overall heat absorbed in the HRSG is 37.39%. It also show that for an increase in the exhaust gas mass flow by 80 kg/s, the steam generation increase by 19.29% and 18.18% for the low and high pressure levels respectively. The overall result indicates an improvement in the HRSG energy efficiency and steam generation. As the exhaust gas mass flow and temperature increases, the steam generation and system effectiveness greatly improved under the various considerations, which satisfy the research objective.
文摘The reasons of introducing cold air into pulverizer are analyzed for boilers with large capacity and high parameters. The temperature rises of the exhaust gas are calculated when varying the amount of the cold air. The hot primary air heater, a new technology, is developed to eliminate the cold air from the pulverized coal system. The applications, advantages and disadvantages are introduced in detail for the new device and system. It is concluded that introducing cold air into pulverizer is one of the major factors that causes the exhaust gas temperature of boilers with large capacity to be high. The amount of the cold air could be reduced signif icantly, even to zero in some cases by adopting the hot primary air heater, which drops the exhaust gas temperature of the boiler effectively. The hot primary air heater, which could play part roles of the steam-air heater or the hot air recirculation system, could also be used to adjust the exhaust gas temperature within the range of 20 ℃ by controlling the flow rate of the cooling medium. Moreover, the startup period of the steam-air heater or the hot air recirculation system will be shortened, which is a unique advantage of the hot primary air heater among the measures to drop the exhaust gas temperature.
基金partially supported by the National Natural Science Foundation of China(No.61803121)China Postdoctoral Science Foundation(No.2019M651277).
文摘The reliability of the on-wing aircraft Auxiliary Power Unit(APU)decides the cost and the comfort of flight to a large degree.The most important function of APU is to help start main engines by providing compressed air.Especially on the condition of sudden shutdown in the air,APU can offer additional thrust for landing.Therefore,its condition monitoring has drawn much attention from the academic and industrial field.Among the on-wing sensing data which can reflect its condition,Exhaust Gas Temperature(EGT)is one of the most important parameters.To ensure the reliability of EGT,one kind of data-driven anomaly detection framework for EGT sensing data is proposed based on the Gaussian Process Regression and Kernel Principal Component Analysis.The situations of one-dimensional and two-dimensional input data for EGT anomaly detection are considered,respectively.The cross-validation experiments are carried out by utilizing the real condition data of APU,which are provided by China Southern Airlines Company Limited Shenyang Maintenance Base.The anomalous stuck condition of EGT sensing data is also detected.Experimental results show that the proposed EGT sensing data anomaly detection method can achieve better performance of false positive ratio,false negative ratio and accuracy.