This paper discusses the evolution regularity and the absorption characters of sulfide for bituminous briquette burned in a horizontal burning fornace. The evolution rate of sulphur is affected by some factors, such a...This paper discusses the evolution regularity and the absorption characters of sulfide for bituminous briquette burned in a horizontal burning fornace. The evolution rate of sulphur is affected by some factors, such as the sulphur content in the burning coal, burning time and the mean excess air coefficient in the furnace. With processing the experimental result, the calculation related expression has been obtained to predict the evolution rate of sulfide. The sulphur absorption efficiency of briquette is affected by tbe factors such as the character of the sulphur sorbent, the type of the coal and the operating parameters. By means of appropriately adjusting the calciumsulphur mole ratio, the mean excess air coefficient and the time-interval between pushing two layer briquettes, a high sulphur absorption efficiency (>74% ) can be obtained.展开更多
The Ontario Hydro Method （OHM） recommended by the United States Environmental Protection Agency （EPA） was used to determine mercury speciation in the combustion flue gas across wet FGD systems. Four coal-fired uni...The Ontario Hydro Method （OHM） recommended by the United States Environmental Protection Agency （EPA） was used to determine mercury speciation in the combustion flue gas across wet FGD systems. Four coal-fired units with wet FGD systems were chosen to evaluate mercury speciation and mercury removal efficiencies through these wet FGD systems. Chlorine content in coal had been suggested as a main factor that affects mercury speciation in flue gas. It is shown that the higher the chlorine concentration in coal is, the higher the percentage of oxidized mercury （Hg2＋） is removed in wet FGD systems, which can increase overall mercury removal efficiencies through wet FGD systems. The selective catalyst reduction （SCR） system has a function of oxidizing ele- mental mercury （Hg0） to oxidized mercury. A higher percentage of oxidized mercury in the total vapor mercury at the FGD inlet is observed when SCR is in service. Therefore, higher overall mercury removal efficiencies through wet FGD are attained. Because of different wet FGD operating conditions, there are different mercury removal efficiencies in different units. Elemental mercury reemission took place when a fraction of oxidized mercury absorbed in the slurry is reduced to elemental mercury, and Hg2＋ is reemitted from stack, which results in decreases in mercury removal efficiencies through wet FGD systems.展开更多
Modeling and simulation of two different microturbine （MT） models to analyze load following performance as distributed energy resource （DER） have been presented in this paper. The first model consists of speed gov...Modeling and simulation of two different microturbine （MT） models to analyze load following performance as distributed energy resource （DER） have been presented in this paper. The first model consists of speed governor, acceleration control, and temperature control blocks while the other is GAST model. The system comprises a synchronous generator and a MT coupled to it. Simulations are carried out in islanded and grid-connected mode to observe the system response when supplying variable loads. The load following characteristics is observed and validated for this MT-synchronous generator model in Matlab-Simulink environment. This is applicable with combined heat power （CHP） generators both with general fuel as well as bio-fuels. The use of bio-fuels is very much promising for generating green power preventing green house gas emissions for fighting against global warming.展开更多
New researches on serious public health problems such as respiratory disease, heart attacks, and premature deaths, show the threat of air and environmental pollution on human＇s health. Exhausting greenhouse gases for...New researches on serious public health problems such as respiratory disease, heart attacks, and premature deaths, show the threat of air and environmental pollution on human＇s health. Exhausting greenhouse gases for electrical energy production in fossil fueled power plants is one of the major reasons of environmental pollutions. Increasing energy demand has made global concerns about the environmental pollutions of fossil power plants. In this article, fossil power plant productive pollutants such as Sulfur Dioxide, Mercury, and Carbon Dioxide, are investigated. On the other hand, nuclear power plant and its produced waste are discussed as the future power generation source. In this article, fossil and nuclear power plants are compared as power sources, pollutants, and their environmental effects. First, investigations are made on fossil power plants and their effects on environment and climate changes. On the other hand, nuclear power plants are discussed as a possible replacement for fossil power plants. In this part, effects of radiation on human health and environment like important nuclear accidents are investigated. This paper summarizes several types of power plants and it is deduced that the nuclear power plant is more clean energy producer in comparison to other power plants.展开更多
Surface acoustic wave （SAW） sensors and micro-electromechanical system （MEMS） technology provide a promising solution for measurement in harsh environments such as gas turbines. In this paper, a SAW resonator （s...Surface acoustic wave （SAW） sensors and micro-electromechanical system （MEMS） technology provide a promising solution for measurement in harsh environments such as gas turbines. In this paper, a SAW resonator （size： 1107μm× 721 μm） based on the AlN/4H-SiC multilayer structure is designed and simulated. A MEMS-compatible fabrication process is employed to fabricate the resonator. The results show that highly c-axis-oriented AlN thin films deposited on the 4H-SiC substrate are obtained, with that the diffraction peak of AlN is 36.10° and the lowest full width at half maximum （FWHM） value is only 1.19°. The test results of the network analyzer are consistent with the simulation curve, which is very encouraging and indicates that our work is a significant attempt to solve the measurement problems mainly including high temperature stability of sensitive structures and the heat transmission of leads in harsh environments. It is essential to get the best performance of SAW resonator, optimize and characterize the behaviors in high temperatures in future research.展开更多
Forest fags in China are very serious in recent years. Few fires occurred formerly in Southeast Tibet, but now forest fires in this region occur frequently. This natural environment of the region is unique. Forest fir...Forest fags in China are very serious in recent years. Few fires occurred formerly in Southeast Tibet, but now forest fires in this region occur frequently. This natural environment of the region is unique. Forest fires are very easy to occur in the dry seasons due to the influence of the southwest monsoon, Because over-mature forest in this region accounts for much proportion, the forest ecosystem is frail. Once destructed by forest fags, it is very extremely difficult to restore. Fire season in this area is in winter and spring. But in the special year, forest fires can also occur in the hot summer. Fire Season lasts from October to next February, even to April in an individual arid year. Most of the fires in this area are surface fires, and crown fires can occur after long time drought.展开更多
文摘This paper discusses the evolution regularity and the absorption characters of sulfide for bituminous briquette burned in a horizontal burning fornace. The evolution rate of sulphur is affected by some factors, such as the sulphur content in the burning coal, burning time and the mean excess air coefficient in the furnace. With processing the experimental result, the calculation related expression has been obtained to predict the evolution rate of sulfide. The sulphur absorption efficiency of briquette is affected by tbe factors such as the character of the sulphur sorbent, the type of the coal and the operating parameters. By means of appropriately adjusting the calciumsulphur mole ratio, the mean excess air coefficient and the time-interval between pushing two layer briquettes, a high sulphur absorption efficiency (>74% ) can be obtained.
文摘The Ontario Hydro Method （OHM） recommended by the United States Environmental Protection Agency （EPA） was used to determine mercury speciation in the combustion flue gas across wet FGD systems. Four coal-fired units with wet FGD systems were chosen to evaluate mercury speciation and mercury removal efficiencies through these wet FGD systems. Chlorine content in coal had been suggested as a main factor that affects mercury speciation in flue gas. It is shown that the higher the chlorine concentration in coal is, the higher the percentage of oxidized mercury （Hg2＋） is removed in wet FGD systems, which can increase overall mercury removal efficiencies through wet FGD systems. The selective catalyst reduction （SCR） system has a function of oxidizing ele- mental mercury （Hg0） to oxidized mercury. A higher percentage of oxidized mercury in the total vapor mercury at the FGD inlet is observed when SCR is in service. Therefore, higher overall mercury removal efficiencies through wet FGD are attained. Because of different wet FGD operating conditions, there are different mercury removal efficiencies in different units. Elemental mercury reemission took place when a fraction of oxidized mercury absorbed in the slurry is reduced to elemental mercury, and Hg2＋ is reemitted from stack, which results in decreases in mercury removal efficiencies through wet FGD systems.
文摘Modeling and simulation of two different microturbine （MT） models to analyze load following performance as distributed energy resource （DER） have been presented in this paper. The first model consists of speed governor, acceleration control, and temperature control blocks while the other is GAST model. The system comprises a synchronous generator and a MT coupled to it. Simulations are carried out in islanded and grid-connected mode to observe the system response when supplying variable loads. The load following characteristics is observed and validated for this MT-synchronous generator model in Matlab-Simulink environment. This is applicable with combined heat power （CHP） generators both with general fuel as well as bio-fuels. The use of bio-fuels is very much promising for generating green power preventing green house gas emissions for fighting against global warming.
文摘New researches on serious public health problems such as respiratory disease, heart attacks, and premature deaths, show the threat of air and environmental pollution on human＇s health. Exhausting greenhouse gases for electrical energy production in fossil fueled power plants is one of the major reasons of environmental pollutions. Increasing energy demand has made global concerns about the environmental pollutions of fossil power plants. In this article, fossil power plant productive pollutants such as Sulfur Dioxide, Mercury, and Carbon Dioxide, are investigated. On the other hand, nuclear power plant and its produced waste are discussed as the future power generation source. In this article, fossil and nuclear power plants are compared as power sources, pollutants, and their environmental effects. First, investigations are made on fossil power plants and their effects on environment and climate changes. On the other hand, nuclear power plants are discussed as a possible replacement for fossil power plants. In this part, effects of radiation on human health and environment like important nuclear accidents are investigated. This paper summarizes several types of power plants and it is deduced that the nuclear power plant is more clean energy producer in comparison to other power plants.
基金Project supported by the Tsinghua University Initiative Scientific Research Program(No.20131089351),China
文摘Surface acoustic wave （SAW） sensors and micro-electromechanical system （MEMS） technology provide a promising solution for measurement in harsh environments such as gas turbines. In this paper, a SAW resonator （size： 1107μm× 721 μm） based on the AlN/4H-SiC multilayer structure is designed and simulated. A MEMS-compatible fabrication process is employed to fabricate the resonator. The results show that highly c-axis-oriented AlN thin films deposited on the 4H-SiC substrate are obtained, with that the diffraction peak of AlN is 36.10° and the lowest full width at half maximum （FWHM） value is only 1.19°. The test results of the network analyzer are consistent with the simulation curve, which is very encouraging and indicates that our work is a significant attempt to solve the measurement problems mainly including high temperature stability of sensitive structures and the heat transmission of leads in harsh environments. It is essential to get the best performance of SAW resonator, optimize and characterize the behaviors in high temperatures in future research.
基金Supported by NSFC Project (No. 30371170) and the fund of Forest Protection Laboratory, State Forestry Administration.
文摘Forest fags in China are very serious in recent years. Few fires occurred formerly in Southeast Tibet, but now forest fires in this region occur frequently. This natural environment of the region is unique. Forest fires are very easy to occur in the dry seasons due to the influence of the southwest monsoon, Because over-mature forest in this region accounts for much proportion, the forest ecosystem is frail. Once destructed by forest fags, it is very extremely difficult to restore. Fire season in this area is in winter and spring. But in the special year, forest fires can also occur in the hot summer. Fire Season lasts from October to next February, even to April in an individual arid year. Most of the fires in this area are surface fires, and crown fires can occur after long time drought.
