In this paper,the combustion conditions in the boiler furnace of a 660 MWtangential fired pulverized coal boiler are numerically simulated at 15%and 20%rated loads,to study the flexibility of coal-fired power units on...In this paper,the combustion conditions in the boiler furnace of a 660 MWtangential fired pulverized coal boiler are numerically simulated at 15%and 20%rated loads,to study the flexibility of coal-fired power units on ultra-low load operation.The numerical results show that the boiler can operate safely at 15%and 20%ultra-low loads,and the combustion condition in the furnace is better at 20%load,and the tangent circles formed by each characteristic section in the furnace are better,and when the boiler load is decreased to 15%,the tangent circles in the furnace begin to deteriorate.The average flue gas temperature of different areas of the furnace shows that when the boiler furnace operates under ultra-low load conditions,the average smoke temperature of the cold ash hopper at 20%load is basically the same as the average smoke temperature at 15%load;in the burner area,the average smoke temperature of the cold ash hopper at 20%load is about 50 K higher than that at 15%load;in the burned out area,the average smoke temperature of the cold ash hopper at 20%load is slightly higher than that at 15%load.The average temperature of flue gas in the furnace showed a tendency to increase rapidly with the height of the furnace,then slow down and fluctuate the temperature in the burner area,and finally increase slightly in the burnout area due to the further combustion of combustible components to release heat,and then began to decrease.展开更多
For capturing and recycling of CO2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techni...For capturing and recycling of CO2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techniques of spraying water in the cylinder and optimizing the ignition advance angle. However, due to the water spray nozzle need to be installed on the cylinder, which increases the cylinder head design difficulty and makes the combustion conditions become more complicated. In this paper, a new method is presented to carry out the closing inlet and exhaust system for internal combustion engines. The proposed new method uses liquid oxygen to solidify part of cooled CO2 from exhaust system into dry ice and the liquid oxygen turns into gas oxygen which is sent to inlet system. The other part of CO2 is sent to inlet system and mixed with oxygen, which can reduce the oxygen-enriched combustion detonation tendency and make combustion stable. Computing grid of the IP52FMI single-cylinder four-stroke gasoline-engine is established according to the actual shape of the combustion chamber using KIVA-3V program. The effects of exhaust gas recirculation (EGR) rate are analyzed on the temperatures, the pressures and the instantaneous heat release rates when the EGR rate is more than 8%. The possibility of enclosing intake and exhaust system for engine is verified. The carbon dioxide trapping device is designed and the IP52FMI engine is transformed and the CO2 capture experiment is carried out. The experimental results show that when the EGR rate is 36% for the optimum EGR rate. When the liquid oxygen of 35.80-437.40 g is imported into the device and last 1-20 min, respectively, 21.50-701.30 g dry ice is obtained. This research proposes a new design method which can capture CO2 for vehicular internal combustion engine.展开更多
The rare earth composite ceramic materials were prepared using rare earths and far infrared natural mineral. The effects of the as-prepared ceramic materials on the oil consumption and air pollutants emissions of oil-...The rare earth composite ceramic materials were prepared using rare earths and far infrared natural mineral. The effects of the as-prepared ceramic materials on the oil consumption and air pollutants emissions of oil-burning boiler were investigated. The results show that the composite ceramic materials can radiate higher intensity of far infrared. The molecular movement is strengthened and the chemical bonds of the molecules are easily ruptured when the diesel oil is dealt with the composite materials. The oil-saving rate of the RBS·VH-1 .5 boiler dealt with the rare earth composite ceramic materials is 3.49%, and the reducing rates of CO and NO in the exhaust gas are 25.4% and 9.7%, respectively.展开更多
To improve the thermal efficiency and reduce nitrogen oxides (NOx ) emissions in a power plant for energy conservation and environment protection, based on the reconstructed section temperature field and other relat...To improve the thermal efficiency and reduce nitrogen oxides (NOx ) emissions in a power plant for energy conservation and environment protection, based on the reconstructed section temperature field and other related parameters, dynamic radial basis function (RBF) artificial neural network (ANN) models for forecasting unburned carbon in fly ash and NO, emissions in flue gas ware developed in this paper, together with a multi-objective optimization system utilizing particle swarm optimization and Powell (PSO-Powell) algorithm. To validate the proposed approach, a series of field tests were conducted in a 350 MW power plant. The results indicate that PSO-Powell algorithm can improve the capability to search optimization solution of PSO algorithm, and the effectiveness of system. Its prospective application in the optimization of a pulverized coal ( PC ) fired boiler is presented as well.展开更多
The sugarcane bagasse fuel is an energetic deposit opportunity for thermal and electricity generation in sugar society.Combustion behaviors,essential for effective operation of these devices are a necessity.A 3D numer...The sugarcane bagasse fuel is an energetic deposit opportunity for thermal and electricity generation in sugar society.Combustion behaviors,essential for effective operation of these devices are a necessity.A 3D numerical model has been developed in the commercial software Ansys Fluent.According to the fuel density and particle variable,this model took into account both suspension and grate model combustion.The realizable k-ε turbulent model with the P-1 model shows its advantage of describing such king problems and has been applied on the numerical model.The contour of the temperature,spices and the particle trajectory provided a clear understanding of bagasse fuel combustion in the furnace as well,bagasse particle goes through from initial heating to char combustion and its conversion to ash.The results obtained were in accordance with those of the literature.These results could be used to analyze this inexpensive combustion process for looking for the effect of design parameter change on the furnace performance.展开更多
The control of 3-D temperature distribution in a utility boiler furnace is essential for the safe, economic and clean operation of pc-fired furnace with multi-burner system. The development of the visualization of 3-...The control of 3-D temperature distribution in a utility boiler furnace is essential for the safe, economic and clean operation of pc-fired furnace with multi-burner system. The development of the visualization of 3-D temperature distributions in pc-fired furnaces makes it possible for a new combustion control strategy directly with the furnace temperature as its goal to improve the control quality for the combustion processes. Studied in this paper is such a new strategy that the whole furnace is divided into several parts in the vertical direction, and the average temperature and its bias from the center in every cross section can be extracted from the visualization results of the 3-D temperature distributions. In the simulation stage, a computational fluid dynamics(CFD) code served to calculate the 3-D temperature distributions in a furnace, then a linear model was set up to relate the features of the temperature distributions with the input of the combustion processes, such as the flow rates of fuel and air fed into the furnaces through all the burners. The adaptive genetic algorithm was adopted to find the optimal combination of the whole input parameters which ensure to form an optimal 3-D temperature field in the furnace desired for the operation of boiler. Simulation results showed that the strategy could soon find the factors making the temperature distribution apart from the optimal state and give correct adjusting suggestions.展开更多
By the end of 1997, totally ten 300 MW grade W-flame double arch boilers, firing anthracite or meager coal, were operating in China. These W-flame boilers were designed and supplied separately by four different manufa...By the end of 1997, totally ten 300 MW grade W-flame double arch boilers, firing anthracite or meager coal, were operating in China. These W-flame boilers were designed and supplied separately by four different manufacturers in the world, using either their own technology or foreign patent. It is shown by a recent survey that all these boilers are having a normal operation. However, there is still some room to be improved, such as boiler furnace configuration. Also, for raising the burnout rate and avoiding local slagging, furnace volume and burner layout need to be deliberated. And the tineness of pulverized coal and the air / coal ratio need to be improved. Some suggestions are made in this paper for optimizing the boiler design, Test data for the minimum stable combustion load and NOx emission are given too.展开更多
Coal-fired plants are under pressure to reduce their carbon-intensity. Available options include co-firing CO2-neutral biomass, oxy-fuel-combustion as part of a carbon capture process or a combination of both to give...Coal-fired plants are under pressure to reduce their carbon-intensity. Available options include co-firing CO2-neutral biomass, oxy-fuel-combustion as part of a carbon capture process or a combination of both to give a “CO2-negative” power plant. BioCCS, the combination of CO2 Capture and Storage (CCS) with sustainable biomass conversion, is the only large-scale technology that can achieve net negative emissions. Combining, developing and demonstrating the oxy-combustion of high ratios of sustainable biomass with coal in flexible circulating fluidized bed (CFB) boiler will bring significant advances in the reduction of greenhouse gases (GHG) emissions. Areas addressed include possibilities for: biomass characterization;handling and feeding;co-firing ratios definition;CFB oxy-co-combustion studies;combustion performance;boiler flexibility in fuel and load;main emissions analysis;slaging, fouling and agglomeration;corrosion and erosion;and implications on plant operation and associated costs. The article will detail a comprehensive understanding on sustainable biomass supply, co-firing ratios and how direct biomass co-combustion under oxy-fuel conditions can be implemented. It seeks to push biomass co-combustion in future large-scale oxy-fuel CFB power stations to high thermal shares while enhancing the power plants’ operational flexibility, economic competitiveness and give operational procedures. There will be a need to consider the public acceptance of power production from coal and coal sustainability, by its combination with renewable sources of energy (biomass).展开更多
Low-NOX combustion retrofit is performed by adopting staged combustion technology for a 600 MW utility boiler with a four-corner tangential firing system. The emission data of NOX before and after retrofit are compare...Low-NOX combustion retrofit is performed by adopting staged combustion technology for a 600 MW utility boiler with a four-corner tangential firing system. The emission data of NOX before and after retrofit are compared and analyzed. The test results show that the emission concentration of NOX decreases obviously after the low-NOX retrofit. Additionally, the emission of NOX decreases by nearly 50% when the unit load is higher than 350 MW. It can also be concluded that the emission of NOX is influenced significantly by the amount of SOFA, the damper opening of auxiliary air, the differential pressure between the secondary air windbox and the furnace, and so on.展开更多
Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Com...Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Compared with conventional steam boilers,S-CO_(2) has different heat transfer characteristics,it is easy to cause the temperature of the cooling wall of the boiler to rise,which leads to higher combustion gas temperature in the furnace,higher NOX generation concentration.The adoption of flue gas recirculation has a significance impact on the combustion process of pulverized coal in the boiler,and it is the most effective ways to reduce the emission of NOX and the combustion temperature in the boiler.This paper takes 1000MW S-CO_(2) T-type coal-fired boiler as the research target to investigate the combustion and NOX generation characteristics of S-CO_(2) coal-fired boilers under flue gas recirculation condition,the influence of recirculated flue gas distribution along the furnace height on the characteristics of NOX formation and the combustion of pulverized coal.The results show that the recirculated flue gas distribution has the great impact on the concentration of NOX at the boiler outlet.When the bottom recirculation flue gas rate is gradually increased,the average temperature of the lower boiler decreases and the average temperature of the upper boiler increases slightly;The concentration of NOx at the furnace outlet increases.展开更多
Various physical parameters, including gas concentrations (O2, CO, CH4, and H2) and temperatures at dif- ferent air velocities, were determined for full scale wood fires in the Chongqing Coal Research Institute fire t...Various physical parameters, including gas concentrations (O2, CO, CH4, and H2) and temperatures at dif- ferent air velocities, were determined for full scale wood fires in the Chongqing Coal Research Institute fire test tunnel. Both experimental measurements and numerical simulations are discussed. The numer- ical analysis was performed with the computational fluid dynamics software package ''FLUENT''. The results show that the experimental data agree with the simulation results. The results verify that Roberts' theory of burning is correct. They also prove that the air velocity is the key factor that determines the type of combustion. Also, it is shown that secondary disasters are unlikely for oxygen rich combustion with a limited fire load.展开更多
This paper presents the scheme of the Fuzzy Homogeneous Combustion Control System (FHCCS) and its practical use on site. The operating results of the system show that FHCCS can not only operate normally, but also gua...This paper presents the scheme of the Fuzzy Homogeneous Combustion Control System (FHCCS) and its practical use on site. The operating results of the system show that FHCCS can not only operate normally, but also guarantee the homogeneous combustion in each level of burner and at optimal air coal ratio of each burner. Some engineering problems about FHCCS implementation are discussed in this paper.展开更多
The numerical simulation model is proposed according to the characteristics of the biomass briquette fuels, which involves two main areas of interest: the solid combustion model in the bed and the out-of-bed gas combu...The numerical simulation model is proposed according to the characteristics of the biomass briquette fuels, which involves two main areas of interest: the solid combustion model in the bed and the out-of-bed gas combustion model. The contents and characteristics of 3 kinds of biomass and coals were experimentally tested. The biomass fuels compared with the coal fuel have the following characteristics: 1) Higher volatile content, lower fixed carbon content and calorific value;2) Lower carbon content, higher oxygen content;3) Lower ignition temperature, faster burning velocity. The discredited equations were established by the finite element analysis method, which analyzed the fuel endothermic process on the grate, while the out-of-bed gas combustion process was simulated by CFD. These two processes are strongly coupled. The results of the numerical simulation contain the steady state temperature distribution, oxygen distribution, carbon dioxide distribution and so on, which are used to judge burning effect and provide the correct furnace transformation method.展开更多
A 600 MW coal-fired boiler with a four-corner tangential combustion mode is considered here to study the combustion features and pollutant emissions at different loads for large-percentages of blending dried sludges.T...A 600 MW coal-fired boiler with a four-corner tangential combustion mode is considered here to study the combustion features and pollutant emissions at different loads for large-percentages of blending dried sludges.The influence of the over-fired air(OFA)coefficient is examined and the impact of the blending ratio on the boiler operation is explored.The results show that for low blending ratios,a slight increase in the blending ratio can improve the combustion of bituminite,whereas a further increase leads to the deterioration of the combustion of blended fuels and thus reduces the boiler efficiency.Enhancing the supporting capability of the secondary air effectively reduces the slagging degree in the bottom ash hopper and improves the burnout rate of coals.For a large-percentage blending case at full load,it is found that the OFA coefficient must be reduced appropriately,otherwise,a secondary high-temperature combustion zone can be generated in the vicinity of the furnace arches,causing high temperature slagging and superheater tube bursting.Considering the influences of combustion and pollutant emissions,the recommended OFA coefficient is 0.2.Blending dried sludge under low loads increases the flue gas temperature at the furnace exit.While reducing the flue gas temperature in the main combustion region,which is beneficial to the safe operation of the denitrification system.Increasing the blending ratio and reducing load lead to an increase in NOx concentration at the furnace exit Sludges with low nitrogen content are suggested for the practical operation of boilers.展开更多
Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminou...Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminous coal briquet, distribution of temperature field in the stove, the regularities of evolution and combustion of volatile matter, the burning rate and edi-ciency of bituminous coal briquet, characteristics of fire-sealing and sulfur-retention. The results show that, with the technique, some achievements can be obtained in combustion of bituminous coal briquet, such as lower pollution that the flue gas black degree is below 0. 5R and dust con-centration is below 90 mg/m3. The stove’s combustion efficiency reaches 90%, sulfur fixing effi-ciency is 60%, and oO concentration is decreased by 40% compared with other traditional stoves. With so many advantages, the stove can be used extensively in civil stoves and smaller industrial boilers.展开更多
Xi’an Thermal Power Research Institute (TPRI) isone of the research organizations directly under theMinistry of Energy.Its responsibility is to solve key technicalproblems occurred in thermal power plants,and to unde...Xi’an Thermal Power Research Institute (TPRI) isone of the research organizations directly under theMinistry of Energy.Its responsibility is to solve key technicalproblems occurred in thermal power plants,and to undertake therelated research and development projects.China relies heavily on coat for energy generation.The to-展开更多
The major aims combustion engineers all over the worldare striving at are conservation of energy and allevia-tion of environmental pollution,for which the monitoring and controlof the furnace process are of prime impo...The major aims combustion engineers all over the worldare striving at are conservation of energy and allevia-tion of environmental pollution,for which the monitoring and controlof the furnace process are of prime importance to attain an optimizedcondition of combustion.Oxygen content in flue gas is generallyused as an indicator of whether the right amount of combustion air issupplied.However,it cannot directly reflect the degree of perfectionof the combustion process taking place in the furnace.On the otherhand CO is a product of chemical reaction which directly reflects展开更多
文摘In this paper,the combustion conditions in the boiler furnace of a 660 MWtangential fired pulverized coal boiler are numerically simulated at 15%and 20%rated loads,to study the flexibility of coal-fired power units on ultra-low load operation.The numerical results show that the boiler can operate safely at 15%and 20%ultra-low loads,and the combustion condition in the furnace is better at 20%load,and the tangent circles formed by each characteristic section in the furnace are better,and when the boiler load is decreased to 15%,the tangent circles in the furnace begin to deteriorate.The average flue gas temperature of different areas of the furnace shows that when the boiler furnace operates under ultra-low load conditions,the average smoke temperature of the cold ash hopper at 20%load is basically the same as the average smoke temperature at 15%load;in the burner area,the average smoke temperature of the cold ash hopper at 20%load is about 50 K higher than that at 15%load;in the burned out area,the average smoke temperature of the cold ash hopper at 20%load is slightly higher than that at 15%load.The average temperature of flue gas in the furnace showed a tendency to increase rapidly with the height of the furnace,then slow down and fluctuate the temperature in the burner area,and finally increase slightly in the burnout area due to the further combustion of combustible components to release heat,and then began to decrease.
基金Supported by National Natural Science Foundation of China(Grant No.51176082)Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions of China(Grant No.CIT&TCD20140311)Beijing Municipal Natural Science Foundation of China(Grant No.SQKZ201510016004)
文摘For capturing and recycling of CO2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techniques of spraying water in the cylinder and optimizing the ignition advance angle. However, due to the water spray nozzle need to be installed on the cylinder, which increases the cylinder head design difficulty and makes the combustion conditions become more complicated. In this paper, a new method is presented to carry out the closing inlet and exhaust system for internal combustion engines. The proposed new method uses liquid oxygen to solidify part of cooled CO2 from exhaust system into dry ice and the liquid oxygen turns into gas oxygen which is sent to inlet system. The other part of CO2 is sent to inlet system and mixed with oxygen, which can reduce the oxygen-enriched combustion detonation tendency and make combustion stable. Computing grid of the IP52FMI single-cylinder four-stroke gasoline-engine is established according to the actual shape of the combustion chamber using KIVA-3V program. The effects of exhaust gas recirculation (EGR) rate are analyzed on the temperatures, the pressures and the instantaneous heat release rates when the EGR rate is more than 8%. The possibility of enclosing intake and exhaust system for engine is verified. The carbon dioxide trapping device is designed and the IP52FMI engine is transformed and the CO2 capture experiment is carried out. The experimental results show that when the EGR rate is 36% for the optimum EGR rate. When the liquid oxygen of 35.80-437.40 g is imported into the device and last 1-20 min, respectively, 21.50-701.30 g dry ice is obtained. This research proposes a new design method which can capture CO2 for vehicular internal combustion engine.
基金Project supported by the Key Technologies R & D Programme of Tianjin (06YFGZGX02400)
文摘The rare earth composite ceramic materials were prepared using rare earths and far infrared natural mineral. The effects of the as-prepared ceramic materials on the oil consumption and air pollutants emissions of oil-burning boiler were investigated. The results show that the composite ceramic materials can radiate higher intensity of far infrared. The molecular movement is strengthened and the chemical bonds of the molecules are easily ruptured when the diesel oil is dealt with the composite materials. The oil-saving rate of the RBS·VH-1 .5 boiler dealt with the rare earth composite ceramic materials is 3.49%, and the reducing rates of CO and NO in the exhaust gas are 25.4% and 9.7%, respectively.
文摘To improve the thermal efficiency and reduce nitrogen oxides (NOx ) emissions in a power plant for energy conservation and environment protection, based on the reconstructed section temperature field and other related parameters, dynamic radial basis function (RBF) artificial neural network (ANN) models for forecasting unburned carbon in fly ash and NO, emissions in flue gas ware developed in this paper, together with a multi-objective optimization system utilizing particle swarm optimization and Powell (PSO-Powell) algorithm. To validate the proposed approach, a series of field tests were conducted in a 350 MW power plant. The results indicate that PSO-Powell algorithm can improve the capability to search optimization solution of PSO algorithm, and the effectiveness of system. Its prospective application in the optimization of a pulverized coal ( PC ) fired boiler is presented as well.
文摘The sugarcane bagasse fuel is an energetic deposit opportunity for thermal and electricity generation in sugar society.Combustion behaviors,essential for effective operation of these devices are a necessity.A 3D numerical model has been developed in the commercial software Ansys Fluent.According to the fuel density and particle variable,this model took into account both suspension and grate model combustion.The realizable k-ε turbulent model with the P-1 model shows its advantage of describing such king problems and has been applied on the numerical model.The contour of the temperature,spices and the particle trajectory provided a clear understanding of bagasse fuel combustion in the furnace as well,bagasse particle goes through from initial heating to char combustion and its conversion to ash.The results obtained were in accordance with those of the literature.These results could be used to analyze this inexpensive combustion process for looking for the effect of design parameter change on the furnace performance.
文摘The control of 3-D temperature distribution in a utility boiler furnace is essential for the safe, economic and clean operation of pc-fired furnace with multi-burner system. The development of the visualization of 3-D temperature distributions in pc-fired furnaces makes it possible for a new combustion control strategy directly with the furnace temperature as its goal to improve the control quality for the combustion processes. Studied in this paper is such a new strategy that the whole furnace is divided into several parts in the vertical direction, and the average temperature and its bias from the center in every cross section can be extracted from the visualization results of the 3-D temperature distributions. In the simulation stage, a computational fluid dynamics(CFD) code served to calculate the 3-D temperature distributions in a furnace, then a linear model was set up to relate the features of the temperature distributions with the input of the combustion processes, such as the flow rates of fuel and air fed into the furnaces through all the burners. The adaptive genetic algorithm was adopted to find the optimal combination of the whole input parameters which ensure to form an optimal 3-D temperature field in the furnace desired for the operation of boiler. Simulation results showed that the strategy could soon find the factors making the temperature distribution apart from the optimal state and give correct adjusting suggestions.
文摘By the end of 1997, totally ten 300 MW grade W-flame double arch boilers, firing anthracite or meager coal, were operating in China. These W-flame boilers were designed and supplied separately by four different manufacturers in the world, using either their own technology or foreign patent. It is shown by a recent survey that all these boilers are having a normal operation. However, there is still some room to be improved, such as boiler furnace configuration. Also, for raising the burnout rate and avoiding local slagging, furnace volume and burner layout need to be deliberated. And the tineness of pulverized coal and the air / coal ratio need to be improved. Some suggestions are made in this paper for optimizing the boiler design, Test data for the minimum stable combustion load and NOx emission are given too.
文摘Coal-fired plants are under pressure to reduce their carbon-intensity. Available options include co-firing CO2-neutral biomass, oxy-fuel-combustion as part of a carbon capture process or a combination of both to give a “CO2-negative” power plant. BioCCS, the combination of CO2 Capture and Storage (CCS) with sustainable biomass conversion, is the only large-scale technology that can achieve net negative emissions. Combining, developing and demonstrating the oxy-combustion of high ratios of sustainable biomass with coal in flexible circulating fluidized bed (CFB) boiler will bring significant advances in the reduction of greenhouse gases (GHG) emissions. Areas addressed include possibilities for: biomass characterization;handling and feeding;co-firing ratios definition;CFB oxy-co-combustion studies;combustion performance;boiler flexibility in fuel and load;main emissions analysis;slaging, fouling and agglomeration;corrosion and erosion;and implications on plant operation and associated costs. The article will detail a comprehensive understanding on sustainable biomass supply, co-firing ratios and how direct biomass co-combustion under oxy-fuel conditions can be implemented. It seeks to push biomass co-combustion in future large-scale oxy-fuel CFB power stations to high thermal shares while enhancing the power plants’ operational flexibility, economic competitiveness and give operational procedures. There will be a need to consider the public acceptance of power production from coal and coal sustainability, by its combination with renewable sources of energy (biomass).
文摘Low-NOX combustion retrofit is performed by adopting staged combustion technology for a 600 MW utility boiler with a four-corner tangential firing system. The emission data of NOX before and after retrofit are compared and analyzed. The test results show that the emission concentration of NOX decreases obviously after the low-NOX retrofit. Additionally, the emission of NOX decreases by nearly 50% when the unit load is higher than 350 MW. It can also be concluded that the emission of NOX is influenced significantly by the amount of SOFA, the damper opening of auxiliary air, the differential pressure between the secondary air windbox and the furnace, and so on.
基金This paper is supported by the National Key R&D Program of China(2017YFB0601805).
文摘Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Compared with conventional steam boilers,S-CO_(2) has different heat transfer characteristics,it is easy to cause the temperature of the cooling wall of the boiler to rise,which leads to higher combustion gas temperature in the furnace,higher NOX generation concentration.The adoption of flue gas recirculation has a significance impact on the combustion process of pulverized coal in the boiler,and it is the most effective ways to reduce the emission of NOX and the combustion temperature in the boiler.This paper takes 1000MW S-CO_(2) T-type coal-fired boiler as the research target to investigate the combustion and NOX generation characteristics of S-CO_(2) coal-fired boilers under flue gas recirculation condition,the influence of recirculated flue gas distribution along the furnace height on the characteristics of NOX formation and the combustion of pulverized coal.The results show that the recirculated flue gas distribution has the great impact on the concentration of NOX at the boiler outlet.When the bottom recirculation flue gas rate is gradually increased,the average temperature of the lower boiler decreases and the average temperature of the upper boiler increases slightly;The concentration of NOx at the furnace outlet increases.
基金Financial support for this work provided by the National"Eleventh Five-Year" Key Scientific and Technological Support[Program (No. 2007BAK22B04)2008 independent task (No.SKLCRSM08B12)
文摘Various physical parameters, including gas concentrations (O2, CO, CH4, and H2) and temperatures at dif- ferent air velocities, were determined for full scale wood fires in the Chongqing Coal Research Institute fire test tunnel. Both experimental measurements and numerical simulations are discussed. The numer- ical analysis was performed with the computational fluid dynamics software package ''FLUENT''. The results show that the experimental data agree with the simulation results. The results verify that Roberts' theory of burning is correct. They also prove that the air velocity is the key factor that determines the type of combustion. Also, it is shown that secondary disasters are unlikely for oxygen rich combustion with a limited fire load.
文摘This paper presents the scheme of the Fuzzy Homogeneous Combustion Control System (FHCCS) and its practical use on site. The operating results of the system show that FHCCS can not only operate normally, but also guarantee the homogeneous combustion in each level of burner and at optimal air coal ratio of each burner. Some engineering problems about FHCCS implementation are discussed in this paper.
文摘The numerical simulation model is proposed according to the characteristics of the biomass briquette fuels, which involves two main areas of interest: the solid combustion model in the bed and the out-of-bed gas combustion model. The contents and characteristics of 3 kinds of biomass and coals were experimentally tested. The biomass fuels compared with the coal fuel have the following characteristics: 1) Higher volatile content, lower fixed carbon content and calorific value;2) Lower carbon content, higher oxygen content;3) Lower ignition temperature, faster burning velocity. The discredited equations were established by the finite element analysis method, which analyzed the fuel endothermic process on the grate, while the out-of-bed gas combustion process was simulated by CFD. These two processes are strongly coupled. The results of the numerical simulation contain the steady state temperature distribution, oxygen distribution, carbon dioxide distribution and so on, which are used to judge burning effect and provide the correct furnace transformation method.
文摘A 600 MW coal-fired boiler with a four-corner tangential combustion mode is considered here to study the combustion features and pollutant emissions at different loads for large-percentages of blending dried sludges.The influence of the over-fired air(OFA)coefficient is examined and the impact of the blending ratio on the boiler operation is explored.The results show that for low blending ratios,a slight increase in the blending ratio can improve the combustion of bituminite,whereas a further increase leads to the deterioration of the combustion of blended fuels and thus reduces the boiler efficiency.Enhancing the supporting capability of the secondary air effectively reduces the slagging degree in the bottom ash hopper and improves the burnout rate of coals.For a large-percentage blending case at full load,it is found that the OFA coefficient must be reduced appropriately,otherwise,a secondary high-temperature combustion zone can be generated in the vicinity of the furnace arches,causing high temperature slagging and superheater tube bursting.Considering the influences of combustion and pollutant emissions,the recommended OFA coefficient is 0.2.Blending dried sludge under low loads increases the flue gas temperature at the furnace exit.While reducing the flue gas temperature in the main combustion region,which is beneficial to the safe operation of the denitrification system.Increasing the blending ratio and reducing load lead to an increase in NOx concentration at the furnace exit Sludges with low nitrogen content are suggested for the practical operation of boilers.
文摘Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminous coal briquet, distribution of temperature field in the stove, the regularities of evolution and combustion of volatile matter, the burning rate and edi-ciency of bituminous coal briquet, characteristics of fire-sealing and sulfur-retention. The results show that, with the technique, some achievements can be obtained in combustion of bituminous coal briquet, such as lower pollution that the flue gas black degree is below 0. 5R and dust con-centration is below 90 mg/m3. The stove’s combustion efficiency reaches 90%, sulfur fixing effi-ciency is 60%, and oO concentration is decreased by 40% compared with other traditional stoves. With so many advantages, the stove can be used extensively in civil stoves and smaller industrial boilers.
文摘Xi’an Thermal Power Research Institute (TPRI) isone of the research organizations directly under theMinistry of Energy.Its responsibility is to solve key technicalproblems occurred in thermal power plants,and to undertake therelated research and development projects.China relies heavily on coat for energy generation.The to-
文摘The major aims combustion engineers all over the worldare striving at are conservation of energy and allevia-tion of environmental pollution,for which the monitoring and controlof the furnace process are of prime importance to attain an optimizedcondition of combustion.Oxygen content in flue gas is generallyused as an indicator of whether the right amount of combustion air issupplied.However,it cannot directly reflect the degree of perfectionof the combustion process taking place in the furnace.On the otherhand CO is a product of chemical reaction which directly reflects