Two modes of regulating the water quality of experimental ponds in indoor raceway culture of Litopenaeus vannamei were evaluated using simple water treatment facilities. A self-made water purifying net, aeration stone...Two modes of regulating the water quality of experimental ponds in indoor raceway culture of Litopenaeus vannamei were evaluated using simple water treatment facilities. A self-made water purifying net, aeration stone, composite microbe preparation, and Ceratophyllum demersum were placed in the experimental ponds and the culture water was circulated along the raceway inside the pond using a paddle wheel aerator. In addition, the water quality in the experimental pond was improved by draining effluent from the pipeline at the bottom of ponds 7 and 8 （mode I） and exchanging the circulating water in pond 10 （mode Ⅱ） with the reservoir water in pond 9 using a pump and pipeline. The water quality in the experimental ponds was similar in response to regulation using mode Ⅰ or mode Ⅱ. Water quality parameters in the experimental ponds were controlled within a suitable range by simple facilities during culture period without using any chemical treatments. The rich content of dissolved oxygen was maintained by the circular flow and continuous aeration of the pond water. The respective average values of the main water parameters in experimental ponds 7 and 10 in response to regulation of the water quality using modes Ⅰ and Ⅱwere as follows： pH 8.17 and 7.99; DO 5.16 mg/L and 5.97 mg/L; CODMn18.45 and 12.61 mg/L; TAN （NH3-N） 0.854 mg/L （0.087 mg/L） and 0.427 mg/L （0.012 mg/L）; NO2-N 0.489 mg/L and 0.337 mg/L. Moreover, the average body length and body weight of harvested shrimp of pond 7 and pond l0 were 7.56 cm and 8.99 cm, 5.10 g and 8.33 g, respectively. Furthermore, the survival rate, average biomass yield and average condition factor of the shrimp harvested were 70% and 60%, 2.54 kg/m2 and 2.14 kg/m2, and 0.675 g/cm and 0.927 g/cm, respectively. Linear equations describing the relationship between body length and culture time and cubic or power functions describing the relationship between body weight and body length were obtained based on evaluation of the growth data of shrimps throughout the culture period.展开更多
As the two most important indexes of bearing raceway, surface roughness and roundness have significant influence on bearing noise. Some researchers have carried out studies in this field, however, reason and extent of...As the two most important indexes of bearing raceway, surface roughness and roundness have significant influence on bearing noise. Some researchers have carried out studies in this field, however, reason and extent of the influence of raceway surface geometric characteristics on bearing running noise are not perfectly clear up to now. In this paper, the raceway of 6309 type bearing＇s inner and outer ring is machined by floating abrasive polishing adopting soft abrasive pad. Surface roughness parameters, arithmetical mean deviation of the profile Ra, the point height of irregularities Rz, maximum height of the profile Rmax and roundness fof raceways, are measured before and after machining, and the change rules of the measured results are studied. The study results show that the floating abrasive polishing can reduce the surface geometric errors of bearing raceway evidently. The roundness error is reduced by 25%, Rm^x value is reduced by 35.5%, Rz value is reduced by 22% and Ra value is reduced by 5%. By analyzing the change of the geometrical parameters and the shape difference of the raceway before and after machining, it is found that the floating abrasive polishing method can affect the roundness error mainly by modifying the local deviation of the raceway＇s surface profile. Bearings with different raceway surface geometrical parameter value are assembled and the running noise is tested. The test results show that Ra has a little, Rmax and Rz have a measurable, and the roundness error has a significant influence on the running noise. From the viewpoint of controlling bearings＇ running noise, raceway roundness error should be strictly controlled, and for the surface roughness parameters, R,n^x and Rz should be mainly controlled. This paper proposes an effective method to obtain the low noise bearing by machining the raceway with floating abrasive polishing after super finishing.展开更多
The relationship between two-dimensional radiant image and three-dimensional radiant energy in blast furnace raceway was studied by numerical simulation of combustion process. Taking radiant image as radiant boundary ...The relationship between two-dimensional radiant image and three-dimensional radiant energy in blast furnace raceway was studied by numerical simulation of combustion process. Taking radiant image as radiant boundary for numerical simulation of combustion process, the uneven radiation parameter can be calculated. A method to examine three-dimensional temperature distribution in blast furnace raceway was put forward by radiant image processing. The numeral temperature field matching the real combustion can be obtained by proposed numeric image processing technique.展开更多
In order to establish correlativity between pulverized coal combustion in a blast furnace raceway and its radiant image, we investigated the relationships between two dimensional radiant images and three dimensional r...In order to establish correlativity between pulverized coal combustion in a blast furnace raceway and its radiant image, we investigated the relationships between two dimensional radiant images and three dimensional radiant energy in a blast furnace raceway, focusing on the correlativity of the numerical simulation of combustion processes with the connection of radiant images information and space temperature distribution. We calculated the uneven radiate characteristic parameterby taking radiant images as a kind of radiative boundary for numerical simulation of combustion processes, and put fonward a method to examine three-dimensional temperatures distribution in blast furnace raceway by radiant image processing. The numeral temperature fields matching the real combustion can be got by the numeric image processing technique.展开更多
Based on numerical simulation, the influences of outer raceway curvature radii on some EHL properties of deep groove ball bearing were studied in detail. It was found that the second peak film pressure value decreases...Based on numerical simulation, the influences of outer raceway curvature radii on some EHL properties of deep groove ball bearing were studied in detail. It was found that the second peak film pressure value decreases with the increase of curvature radius Ry. The minimal film thickness increases at first and then decreases with the increase of curvature radius Ry. The minimum film thickness reaches the maximal value when curvature radius Ry is about 1.7r. Film thickness becomes thinner with the increase of Rx with keeping other parameters constant. The conclusions obtained in this paper are very helpful to practical design of ball bearings.展开更多
The goal of this study was to develop a self-settling microalgal consortium in raceway pond reactor (RPR). Experiments were carried out with cultures that developed without additional seeding, but naturally promoted b...The goal of this study was to develop a self-settling microalgal consortium in raceway pond reactor (RPR). Experiments were carried out with cultures that developed without additional seeding, but naturally promoted by process conditions in a raceway pond reactor. The changes in microalgal communities and total biomass under nitrogen and phosphorous limitations were studied in both batch and continuous systems. At the steady state batch had the population of 46% Euglena sp., 16% Closterium sp., 14% Chlorella sp., 14% Scenedesmus sp. and 10% Ankistrodesmus sp. with a maximum biomass of 900 mg/L. In order to get self-settling microalgal consortium, the operation was changed to continuous continuous mode with the aid of a specially designed settler for daily harvest and recycling of the biomass. Grazing fauna could be controlled by managing reduced liquid and solid retention time. At steady-state condition, an autofloculating and self-settling consortium was developed which had mainly Fragilaria sp., Scenedesmus sp., and filamentous Ulothrix sp. The maximum biomass concentration obtained was 140 mg/L. The presence of neutral lipid droplets in the consortium was identified by staining with Nile Red. Development of the lipid rich consortium could be a suitable method for producing biofuel.展开更多
Serial reuse raceways in fish hatcheries typically use dam boards and screens to separate each raceway unit in the series. This paper describes a novel raceway splash plate constructed of aluminum plate and angle, whi...Serial reuse raceways in fish hatcheries typically use dam boards and screens to separate each raceway unit in the series. This paper describes a novel raceway splash plate constructed of aluminum plate and angle, which eliminates the need for screens when mounted on top of raceway dam boards. In addition to reducing the labor required to remove and replace, and clean screens, the splash plate increased the amount of available rearing space. Incoming water dissolved oxygen concentrations were also increased. These splash plates are relatively easy and inexpensive to fabricate, and their use can lead to increased efficiencies during hatchery rearing.展开更多
This paper presents a method by which the maximum possible rate of pulverized coal injection (PCI) in </span><span style="font-family:Verdana;">blast</span> <span style="font-family...This paper presents a method by which the maximum possible rate of pulverized coal injection (PCI) in </span><span style="font-family:Verdana;">blast</span> <span style="font-family:Verdana;">furnace</span><span style="font-family:Verdana;"> can be predicted. The method is based on a two-step approach. First, a </span><span style="font-family:Verdana;">first principle</span><span style="font-family:Verdana;"> simulation model of the blast furnace is used to generate data sets for the development of a linear model of pulverized coal injection rate. The data has been generated randomly in MATLAB software within the range of operating parameters (constraints) of the blast furnace. After </span><span style="font-family:Verdana;">that</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the coefficients of the function have been determined. The inputs and the resulting outputs formed the data on which the linear optimization model was developed. Next, the linear model was used for maximizing the pulverized coal rate injection by optimizing the other variables. Two operating Indian Blast Furnaces have been chosen to validate the optimization model.展开更多
In this study,the gas-solid flow process in the blast furnace raceway is numerically simulated using coupled computational fluid dynamics and the discrete element method(CFD-DEM).The coke reaction kinetics data are im...In this study,the gas-solid flow process in the blast furnace raceway is numerically simulated using coupled computational fluid dynamics and the discrete element method(CFD-DEM).The coke reaction kinetics data are imported into the DEM model to reproduce the consumption process of each coke particle.The effects of inlet gas velocity and angle on the morphology of the raceway,coke consumption rate,coke bed temperature,and particle size distribution in the blast process are systematically investigated and analyzed.The results show that the consumption of coke particles promotes the formation of raceways during the blast process.At the same time,a coke mixture layer is produced at the edge of the raceway.The higher the inlet gas velocity,the thicker the coke mixture layer in the middle and upper parts of the raceway region,and the larger the proportion of small particles in the coke mixture layer.The effect of the inlet gas angle on the raceway region is less than the inlet gas velocity.However,with the increase in the inlet gas angle,the high-temperature region of the coke bed extends downward gradually,which is conducive to activating the hearth.展开更多
The aim of this study is to investigate the influence of the angle of the pulverized coal (PC) injection lance on the combustion characteristics of fuel in the raceway of blast furnace tuyeres. Using FLUENT software, ...The aim of this study is to investigate the influence of the angle of the pulverized coal (PC) injection lance on the combustion characteristics of fuel in the raceway of blast furnace tuyeres. Using FLUENT software, a Euler-Lagrange three-dimensional numerical model was constructed to analyze the influence of different positions of blast furnace tuyere coal powder injection lance (coaxial and cross-axis) on key parameters such as temperature distribution, gas flow, and combustion efficiency. The results demonstrate that adjusting the angle of the injection lance significantly modifies the average and peak temperatures in the raceway, while the composition of gas components remains relatively stable. When the injection lance angle is 10°, the average temperature and peak temperature in the raceway are 2294 K and 2747 K, respectively. When the injection lance angle is 12°, the combustion efficiency of the PC reaches 80.8%. This study reveals the significant impact of the injection lance angle on the combustion process. Especially at an angle of 12°, the combustion efficiency of the blast furnace significantly improves. With coaxial injection, the combustion rate increases as the distance between the injection lance tip and the tuyere increases. This paper is instructive for the optimization of the blast furnace combustion system, which improve fuel utilization efficiency and reduce environmental emissions. This paper provides practical recommendations for adjusting blast furnace operational parameters, offering insights for achieving more efficient and environmentally friendly industrial production.展开更多
Based on dynamic analysis of rolling bearings, the nonlinear dynamic differential equations of a cylindrical roller bearing with a trilobe-raceway were established and solved by the GSTIFF（gear stiff） integer algori...Based on dynamic analysis of rolling bearings, the nonlinear dynamic differential equations of a cylindrical roller bearing with a trilobe-raceway were established and solved by the GSTIFF（gear stiff） integer algorithm with a variable step. The influences of structural parameters and the tolerance of the trilobe-raceway, working conditions of the bearing, and the outer ring installation method on cage slip characteristics were investigated. The results show that：（i） The cage slip ratio and bearing rating life of a cylindrical roller bearing with a trilobe-raceway would reduce when the low-radius（radius of the outer raceway contour at the lowest point） and D-value（difference value between the high and low points of the outer raceway contour） decrease, and the former（low-radius） contributes more significantly.（ii） The cage slip ratio of a cylindrical roller bearing with a trilobe-raceway rises with the increase of the bearing speed, and decreases with the increase of the radial force; the variation range increases with the increase of the low-radius.（iii） When the installation angle of the outer ring increases in a period, the cage slip ratio remains unchanged while the bearing rating life rises up a little. Therefore, when installing a cylindrical roller bearing with a trilobe-raceway, the location of the maximum radius shall be under that of the radial force to improve the bearing rating life.（iv） With the increase of the roundness of the base circle where the radius of the lowest points of the trilobe-raceway contour locates, the cage slip ratio rises gradually and the bearing rating life decreases.展开更多
The two-dimensional steady-state discrete phase mathematical model is developed to analyze gas-particle flow and combustion characteristics of coal particles, as well as components concentration and temperature distri...The two-dimensional steady-state discrete phase mathematical model is developed to analyze gas-particle flow and combustion characteristics of coal particles, as well as components concentration and temperature distribu- tion of coal gas in the process of pulverized coal injection of blast furnace raceway. The results show that a great deal of coal gas discharges on the top of raceway away from the tuyere, and the residence time of coal particles in the re- gion of blowpipe and tuyere is 20 ms or so and 50 ms when it reaches raceway boundary. The pressure is the highest at the bottom of raceway and the maximal temperature is about 2 423 K. The char combustion is mainly carried out in the raceway and the maximum of char burn-out rate attains 3× 10-4 kg/s.展开更多
Corex is an alternative ironmaking process and raceway is one of the important areas to maintain the stability of the furnace. The raceway parameters are well established for blast furnace operation. But for Corex pro...Corex is an alternative ironmaking process and raceway is one of the important areas to maintain the stability of the furnace. The raceway parameters are well established for blast furnace operation. But for Corex process,it has not yet been established and optimized. Thus,a mathematical model was developed to determine various raceway parameters such as RAFT （raceway adiabatic flame temperature）,tuyere gas velocity and kinetic energy. The model provides an idea about the raceway geometry,zone temperature and kinetic energy accumulated in tuyere gas. Besides,all the raceway parameters have been analyzed to find out their effects on the Corex process. It is found that RAFT influences the gasification reaction kinetics and higher RAFT generates more CO in reduction gas,which improves the metallisation degree of the DRI in shaft. It is also found that increased gas velocity and kinetic energy generate more fines and demand more coke to maintain char bed permeability. High coke rate increases the production cost and lowers the production of hot metal.展开更多
The interaction mechanism between the combustion products of pulverized coal injected and coke in the raceway of blast furnace was studied through thermodynamic calculation and experiments.The results indicated that a...The interaction mechanism between the combustion products of pulverized coal injected and coke in the raceway of blast furnace was studied through thermodynamic calculation and experiments.The results indicated that additives significantly affected the melting property of coal ash in high temperature zone.Although the unburnt char,raw coal ash,and catalyzed coal ash failed to wet the coke surface,the wettability of the catalyzed coal ash on the coke was greater than that of the raw coal ash.Since the unburnt char had weak reaction with the coke surface,it showed little influence on the surface morphology of the coke.The interaction between the raw coal ash and the coke gave rise to the increase in the pore size on the coke surface.However,the raw coal ash only affected the coke surface and the entrances of the pores owing to its poor fluidity.After being melted,the catalyzed coal ash was expected to immerge into the inside part of the coke and then react with the coke,resulting in an expansion and increase of coke cavities.The raw coal ash and the unburnt char reduced the coke reactivity,while the catalyzed coal ash improved the coke reactivity.Thereinto,the coal ash containing Fe2O3 exhibited a larger influence on the reactivity than that containing CaO.展开更多
The particle velocity contours were obtained by tracking the tracer particles in the raceway region of the COREX melter gasifier model and the contours were irregular. According to the fractal theory, the fractal dime...The particle velocity contours were obtained by tracking the tracer particles in the raceway region of the COREX melter gasifier model and the contours were irregular. According to the fractal theory, the fractal dimen sions of different particle velocity contours were determined. Through the analysis of the fractal dimensions, a new method for precise determination of the raceway boundary was proposed. The results show that, when the velocity is less than 0.18 m/s, the particles are located in the stagnant zone and the fractal dimensions of particle velocity con- tours are almost constant as 1.41; when the velocity increases from 0.18 to 0.83 m/s, the particles are located in the rapid movement zone and the fractal dimensions decrease gradually from 1.41 to 1.05 ＇when the velocity is grea- ter than 0.83 m/s, the particles are located in the cavity zone and the fractal dimensions are again almost constant as approaching to 1.00. Therefore, the velocity contour of 0.18 m/s, which is critical to distinguish the rapid move- ment zone and stagnant zone, can be used to define the raceway boundary. Based on this method, the effect of blo wing rate on raceway size was calculated and the results show that the penetration depth and height of the raceway increase with the increase of blowing rate.展开更多
Primary distribution of coal gas in blast furnace raceway has an important effect on blast furnace ironmaking process. The coal gas component concentration distribution was studied experimentally using a three-dimensi...Primary distribution of coal gas in blast furnace raceway has an important effect on blast furnace ironmaking process. The coal gas component concentration distribution was studied experimentally using a three-dimensional cold model. The results showed that CH4 concentration diminishes along with the height increasing on vertical section of raceway, and the concentration is the highest in the bottom of raceway. CH4 concentration increases gradually along.the raceway depth with the lowest concentration value in front of the tuyere. The distribution of CH4 concentration has different characteristics in different raceway zones.展开更多
The raceway has been studied extensively both theoretically and experimentally. The raceway boundary is coarse and fragmentary,but all of previous studies are based on Euclidean geometry,which regards the dimension of...The raceway has been studied extensively both theoretically and experimentally. The raceway boundary is coarse and fragmentary,but all of previous studies are based on Euclidean geometry,which regards the dimension of raceway as an integer. The fractal method of calculating raceway size,which describes boundary with extremely irregular or fragmentary characteristic,is brought forward in physical model. The fractal theory is used to calculate the fractal dimension of raceway boundary and the precise surface area of ellipsoidal raceway boundary. The result shows that the surface area based on fractal is larger than that based on Euclidean. And the surface area increases with the rise of blowing rate.展开更多
Biological CO2 sequestration by microalgae is a promising and environmentally friendly technology applied to sequester CO2. The characteristics of neutral lipid accumulation by two marine oil-rich microalgal strains,n...Biological CO2 sequestration by microalgae is a promising and environmentally friendly technology applied to sequester CO2. The characteristics of neutral lipid accumulation by two marine oil-rich microalgal strains,namely, Isochrysis galbana and Nannochloropsis sp., through CO2 enrichment cultivation were investigated in this study. The optimum culture conditions of the two microalgal strains are 10% CO2 and f medium. The maximum biomass productivity, total lipid content, maximum lipid productivity, carbon content, and CO2 fixation ability of the two microalgal strains were obtained. The corresponding parameters of the two strains were as follows：（（142.42±4.58） g/（m^2·d）,（149.92±1.80） g/（m^2·d））,（（39.95±0.77）%,（37.91±0.58）%）,（（84.47±1.56） g/（m^2·d）,（89.90±1.98） g/（m^2·d））,（（45.98±1.75）%,（46.88±2.01）%）, and（（33.74±1.65） g/（m^2·d）,（34.08±1.32） g/（m^2·d））. Results indicated that the two marine microalgal strains with high CO2 fixation ability are potential strains for marine biodiesel development coupled with CO2 emission reduction.展开更多
基金Supported by the Shanghai Commission of Science and Technology (No.063919112073919102)the Shanghai Agricultural Committee (No.2006,9-4)
文摘Two modes of regulating the water quality of experimental ponds in indoor raceway culture of Litopenaeus vannamei were evaluated using simple water treatment facilities. A self-made water purifying net, aeration stone, composite microbe preparation, and Ceratophyllum demersum were placed in the experimental ponds and the culture water was circulated along the raceway inside the pond using a paddle wheel aerator. In addition, the water quality in the experimental pond was improved by draining effluent from the pipeline at the bottom of ponds 7 and 8 （mode I） and exchanging the circulating water in pond 10 （mode Ⅱ） with the reservoir water in pond 9 using a pump and pipeline. The water quality in the experimental ponds was similar in response to regulation using mode Ⅰ or mode Ⅱ. Water quality parameters in the experimental ponds were controlled within a suitable range by simple facilities during culture period without using any chemical treatments. The rich content of dissolved oxygen was maintained by the circular flow and continuous aeration of the pond water. The respective average values of the main water parameters in experimental ponds 7 and 10 in response to regulation of the water quality using modes Ⅰ and Ⅱwere as follows： pH 8.17 and 7.99; DO 5.16 mg/L and 5.97 mg/L; CODMn18.45 and 12.61 mg/L; TAN （NH3-N） 0.854 mg/L （0.087 mg/L） and 0.427 mg/L （0.012 mg/L）; NO2-N 0.489 mg/L and 0.337 mg/L. Moreover, the average body length and body weight of harvested shrimp of pond 7 and pond l0 were 7.56 cm and 8.99 cm, 5.10 g and 8.33 g, respectively. Furthermore, the survival rate, average biomass yield and average condition factor of the shrimp harvested were 70% and 60%, 2.54 kg/m2 and 2.14 kg/m2, and 0.675 g/cm and 0.927 g/cm, respectively. Linear equations describing the relationship between body length and culture time and cubic or power functions describing the relationship between body weight and body length were obtained based on evaluation of the growth data of shrimps throughout the culture period.
基金Supported by National Natural Science Foundation of China(Grant No.51275062)Open Foundation of Tsinghua University State Key Laboratory of Tribology of China(Grant No.SKLTKF11B08)
文摘As the two most important indexes of bearing raceway, surface roughness and roundness have significant influence on bearing noise. Some researchers have carried out studies in this field, however, reason and extent of the influence of raceway surface geometric characteristics on bearing running noise are not perfectly clear up to now. In this paper, the raceway of 6309 type bearing＇s inner and outer ring is machined by floating abrasive polishing adopting soft abrasive pad. Surface roughness parameters, arithmetical mean deviation of the profile Ra, the point height of irregularities Rz, maximum height of the profile Rmax and roundness fof raceways, are measured before and after machining, and the change rules of the measured results are studied. The study results show that the floating abrasive polishing can reduce the surface geometric errors of bearing raceway evidently. The roundness error is reduced by 25%, Rm^x value is reduced by 35.5%, Rz value is reduced by 22% and Ra value is reduced by 5%. By analyzing the change of the geometrical parameters and the shape difference of the raceway before and after machining, it is found that the floating abrasive polishing method can affect the roundness error mainly by modifying the local deviation of the raceway＇s surface profile. Bearings with different raceway surface geometrical parameter value are assembled and the running noise is tested. The test results show that Ra has a little, Rmax and Rz have a measurable, and the roundness error has a significant influence on the running noise. From the viewpoint of controlling bearings＇ running noise, raceway roundness error should be strictly controlled, and for the surface roughness parameters, R,n^x and Rz should be mainly controlled. This paper proposes an effective method to obtain the low noise bearing by machining the raceway with floating abrasive polishing after super finishing.
文摘The relationship between two-dimensional radiant image and three-dimensional radiant energy in blast furnace raceway was studied by numerical simulation of combustion process. Taking radiant image as radiant boundary for numerical simulation of combustion process, the uneven radiation parameter can be calculated. A method to examine three-dimensional temperature distribution in blast furnace raceway was put forward by radiant image processing. The numeral temperature field matching the real combustion can be obtained by proposed numeric image processing technique.
基金Funded by the National Natural Science Foundation of China and Iron & Steel Unite Research Funds (50374085).
文摘In order to establish correlativity between pulverized coal combustion in a blast furnace raceway and its radiant image, we investigated the relationships between two dimensional radiant images and three dimensional radiant energy in a blast furnace raceway, focusing on the correlativity of the numerical simulation of combustion processes with the connection of radiant images information and space temperature distribution. We calculated the uneven radiate characteristic parameterby taking radiant images as a kind of radiative boundary for numerical simulation of combustion processes, and put fonward a method to examine three-dimensional temperatures distribution in blast furnace raceway by radiant image processing. The numeral temperature fields matching the real combustion can be got by the numeric image processing technique.
文摘Based on numerical simulation, the influences of outer raceway curvature radii on some EHL properties of deep groove ball bearing were studied in detail. It was found that the second peak film pressure value decreases with the increase of curvature radius Ry. The minimal film thickness increases at first and then decreases with the increase of curvature radius Ry. The minimum film thickness reaches the maximal value when curvature radius Ry is about 1.7r. Film thickness becomes thinner with the increase of Rx with keeping other parameters constant. The conclusions obtained in this paper are very helpful to practical design of ball bearings.
文摘The goal of this study was to develop a self-settling microalgal consortium in raceway pond reactor (RPR). Experiments were carried out with cultures that developed without additional seeding, but naturally promoted by process conditions in a raceway pond reactor. The changes in microalgal communities and total biomass under nitrogen and phosphorous limitations were studied in both batch and continuous systems. At the steady state batch had the population of 46% Euglena sp., 16% Closterium sp., 14% Chlorella sp., 14% Scenedesmus sp. and 10% Ankistrodesmus sp. with a maximum biomass of 900 mg/L. In order to get self-settling microalgal consortium, the operation was changed to continuous continuous mode with the aid of a specially designed settler for daily harvest and recycling of the biomass. Grazing fauna could be controlled by managing reduced liquid and solid retention time. At steady-state condition, an autofloculating and self-settling consortium was developed which had mainly Fragilaria sp., Scenedesmus sp., and filamentous Ulothrix sp. The maximum biomass concentration obtained was 140 mg/L. The presence of neutral lipid droplets in the consortium was identified by staining with Nile Red. Development of the lipid rich consortium could be a suitable method for producing biofuel.
文摘Serial reuse raceways in fish hatcheries typically use dam boards and screens to separate each raceway unit in the series. This paper describes a novel raceway splash plate constructed of aluminum plate and angle, which eliminates the need for screens when mounted on top of raceway dam boards. In addition to reducing the labor required to remove and replace, and clean screens, the splash plate increased the amount of available rearing space. Incoming water dissolved oxygen concentrations were also increased. These splash plates are relatively easy and inexpensive to fabricate, and their use can lead to increased efficiencies during hatchery rearing.
文摘This paper presents a method by which the maximum possible rate of pulverized coal injection (PCI) in </span><span style="font-family:Verdana;">blast</span> <span style="font-family:Verdana;">furnace</span><span style="font-family:Verdana;"> can be predicted. The method is based on a two-step approach. First, a </span><span style="font-family:Verdana;">first principle</span><span style="font-family:Verdana;"> simulation model of the blast furnace is used to generate data sets for the development of a linear model of pulverized coal injection rate. The data has been generated randomly in MATLAB software within the range of operating parameters (constraints) of the blast furnace. After </span><span style="font-family:Verdana;">that</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the coefficients of the function have been determined. The inputs and the resulting outputs formed the data on which the linear optimization model was developed. Next, the linear model was used for maximizing the pulverized coal rate injection by optimizing the other variables. Two operating Indian Blast Furnaces have been chosen to validate the optimization model.
基金support by the National Natural Science Foundation of China(grant Nos.51874171,52074150,51974154).
文摘In this study,the gas-solid flow process in the blast furnace raceway is numerically simulated using coupled computational fluid dynamics and the discrete element method(CFD-DEM).The coke reaction kinetics data are imported into the DEM model to reproduce the consumption process of each coke particle.The effects of inlet gas velocity and angle on the morphology of the raceway,coke consumption rate,coke bed temperature,and particle size distribution in the blast process are systematically investigated and analyzed.The results show that the consumption of coke particles promotes the formation of raceways during the blast process.At the same time,a coke mixture layer is produced at the edge of the raceway.The higher the inlet gas velocity,the thicker the coke mixture layer in the middle and upper parts of the raceway region,and the larger the proportion of small particles in the coke mixture layer.The effect of the inlet gas angle on the raceway region is less than the inlet gas velocity.However,with the increase in the inlet gas angle,the high-temperature region of the coke bed extends downward gradually,which is conducive to activating the hearth.
基金support of this research on the mechanism of enhancing the performance of composite pellets_made from limonite(Project No.KKS0202152010,202101AT070083)National Natural Science Foundation of China(No.52104351)+1 种基金the Yunnan Fundamental Research Projects(No.202301AT070795,202101AU070088)the author Lei Gao would like to acknowledge Yunnan Province Xingdian Talent Support Plan Project.
文摘The aim of this study is to investigate the influence of the angle of the pulverized coal (PC) injection lance on the combustion characteristics of fuel in the raceway of blast furnace tuyeres. Using FLUENT software, a Euler-Lagrange three-dimensional numerical model was constructed to analyze the influence of different positions of blast furnace tuyere coal powder injection lance (coaxial and cross-axis) on key parameters such as temperature distribution, gas flow, and combustion efficiency. The results demonstrate that adjusting the angle of the injection lance significantly modifies the average and peak temperatures in the raceway, while the composition of gas components remains relatively stable. When the injection lance angle is 10°, the average temperature and peak temperature in the raceway are 2294 K and 2747 K, respectively. When the injection lance angle is 12°, the combustion efficiency of the PC reaches 80.8%. This study reveals the significant impact of the injection lance angle on the combustion process. Especially at an angle of 12°, the combustion efficiency of the blast furnace significantly improves. With coaxial injection, the combustion rate increases as the distance between the injection lance tip and the tuyere increases. This paper is instructive for the optimization of the blast furnace combustion system, which improve fuel utilization efficiency and reduce environmental emissions. This paper provides practical recommendations for adjusting blast furnace operational parameters, offering insights for achieving more efficient and environmentally friendly industrial production.
基金financially co-supported by the National Natural Science Foundation of China (U1404514)Henan Outstanding Person Foundation in China (144200510020)the Collaborative Innovation Center of Major Machine Manufacturing in Liaoning, China
文摘Based on dynamic analysis of rolling bearings, the nonlinear dynamic differential equations of a cylindrical roller bearing with a trilobe-raceway were established and solved by the GSTIFF（gear stiff） integer algorithm with a variable step. The influences of structural parameters and the tolerance of the trilobe-raceway, working conditions of the bearing, and the outer ring installation method on cage slip characteristics were investigated. The results show that：（i） The cage slip ratio and bearing rating life of a cylindrical roller bearing with a trilobe-raceway would reduce when the low-radius（radius of the outer raceway contour at the lowest point） and D-value（difference value between the high and low points of the outer raceway contour） decrease, and the former（low-radius） contributes more significantly.（ii） The cage slip ratio of a cylindrical roller bearing with a trilobe-raceway rises with the increase of the bearing speed, and decreases with the increase of the radial force; the variation range increases with the increase of the low-radius.（iii） When the installation angle of the outer ring increases in a period, the cage slip ratio remains unchanged while the bearing rating life rises up a little. Therefore, when installing a cylindrical roller bearing with a trilobe-raceway, the location of the maximum radius shall be under that of the radial force to improve the bearing rating life.（iv） With the increase of the roundness of the base circle where the radius of the lowest points of the trilobe-raceway contour locates, the cage slip ratio rises gradually and the bearing rating life decreases.
基金Item Sponsored by National Natural Science Foundation of China and Shanghai Baosteel Group Co Ltd United Research Foundation(50374085)
文摘The two-dimensional steady-state discrete phase mathematical model is developed to analyze gas-particle flow and combustion characteristics of coal particles, as well as components concentration and temperature distribu- tion of coal gas in the process of pulverized coal injection of blast furnace raceway. The results show that a great deal of coal gas discharges on the top of raceway away from the tuyere, and the residence time of coal particles in the re- gion of blowpipe and tuyere is 20 ms or so and 50 ms when it reaches raceway boundary. The pressure is the highest at the bottom of raceway and the maximal temperature is about 2 423 K. The char combustion is mainly carried out in the raceway and the maximum of char burn-out rate attains 3× 10-4 kg/s.
文摘Corex is an alternative ironmaking process and raceway is one of the important areas to maintain the stability of the furnace. The raceway parameters are well established for blast furnace operation. But for Corex process,it has not yet been established and optimized. Thus,a mathematical model was developed to determine various raceway parameters such as RAFT （raceway adiabatic flame temperature）,tuyere gas velocity and kinetic energy. The model provides an idea about the raceway geometry,zone temperature and kinetic energy accumulated in tuyere gas. Besides,all the raceway parameters have been analyzed to find out their effects on the Corex process. It is found that RAFT influences the gasification reaction kinetics and higher RAFT generates more CO in reduction gas,which improves the metallisation degree of the DRI in shaft. It is also found that increased gas velocity and kinetic energy generate more fines and demand more coke to maintain char bed permeability. High coke rate increases the production cost and lowers the production of hot metal.
基金financially supported by the National Natural Science Foundation of China (No.51374166, 51574189)the Natural Science Foundation Research Project of Shaanxi,China(No.2016JQ5041)the Shaanxi Province Department of Education Fund, China(No.16JK1450)
文摘The interaction mechanism between the combustion products of pulverized coal injected and coke in the raceway of blast furnace was studied through thermodynamic calculation and experiments.The results indicated that additives significantly affected the melting property of coal ash in high temperature zone.Although the unburnt char,raw coal ash,and catalyzed coal ash failed to wet the coke surface,the wettability of the catalyzed coal ash on the coke was greater than that of the raw coal ash.Since the unburnt char had weak reaction with the coke surface,it showed little influence on the surface morphology of the coke.The interaction between the raw coal ash and the coke gave rise to the increase in the pore size on the coke surface.However,the raw coal ash only affected the coke surface and the entrances of the pores owing to its poor fluidity.After being melted,the catalyzed coal ash was expected to immerge into the inside part of the coke and then react with the coke,resulting in an expansion and increase of coke cavities.The raw coal ash and the unburnt char reduced the coke reactivity,while the catalyzed coal ash improved the coke reactivity.Thereinto,the coal ash containing Fe2O3 exhibited a larger influence on the reactivity than that containing CaO.
文摘The particle velocity contours were obtained by tracking the tracer particles in the raceway region of the COREX melter gasifier model and the contours were irregular. According to the fractal theory, the fractal dimen sions of different particle velocity contours were determined. Through the analysis of the fractal dimensions, a new method for precise determination of the raceway boundary was proposed. The results show that, when the velocity is less than 0.18 m/s, the particles are located in the stagnant zone and the fractal dimensions of particle velocity con- tours are almost constant as 1.41; when the velocity increases from 0.18 to 0.83 m/s, the particles are located in the rapid movement zone and the fractal dimensions decrease gradually from 1.41 to 1.05 ＇when the velocity is grea- ter than 0.83 m/s, the particles are located in the cavity zone and the fractal dimensions are again almost constant as approaching to 1.00. Therefore, the velocity contour of 0.18 m/s, which is critical to distinguish the rapid move- ment zone and stagnant zone, can be used to define the raceway boundary. Based on this method, the effect of blo wing rate on raceway size was calculated and the results show that the penetration depth and height of the raceway increase with the increase of blowing rate.
基金Item Sponsored by National Natural Science Foundation of China and Shanghai Baosteel Group Co Ltd United Research Foundation(50374085)
文摘Primary distribution of coal gas in blast furnace raceway has an important effect on blast furnace ironmaking process. The coal gas component concentration distribution was studied experimentally using a three-dimensional cold model. The results showed that CH4 concentration diminishes along with the height increasing on vertical section of raceway, and the concentration is the highest in the bottom of raceway. CH4 concentration increases gradually along.the raceway depth with the lowest concentration value in front of the tuyere. The distribution of CH4 concentration has different characteristics in different raceway zones.
基金Item Sponsored by Fundamental Research Funds for Central Universities of China (N090402021)
文摘The raceway has been studied extensively both theoretically and experimentally. The raceway boundary is coarse and fragmentary,but all of previous studies are based on Euclidean geometry,which regards the dimension of raceway as an integer. The fractal method of calculating raceway size,which describes boundary with extremely irregular or fragmentary characteristic,is brought forward in physical model. The fractal theory is used to calculate the fractal dimension of raceway boundary and the precise surface area of ellipsoidal raceway boundary. The result shows that the surface area based on fractal is larger than that based on Euclidean. And the surface area increases with the rise of blowing rate.
基金The Basic Scientific Fund for National Public Research Institutes of China under contract Nos 2017Q09 and2016Q02the National Natural Science Foundation of China under contract No.41776176+2 种基金the National Key Research and Development Program of China under contract No.2017YFC1404604the Shandong Provincial Natural Science Foundation under contract No.ZR2015PD003the 2012 Taishan Scholar
文摘Biological CO2 sequestration by microalgae is a promising and environmentally friendly technology applied to sequester CO2. The characteristics of neutral lipid accumulation by two marine oil-rich microalgal strains,namely, Isochrysis galbana and Nannochloropsis sp., through CO2 enrichment cultivation were investigated in this study. The optimum culture conditions of the two microalgal strains are 10% CO2 and f medium. The maximum biomass productivity, total lipid content, maximum lipid productivity, carbon content, and CO2 fixation ability of the two microalgal strains were obtained. The corresponding parameters of the two strains were as follows：（（142.42±4.58） g/（m^2·d）,（149.92±1.80） g/（m^2·d））,（（39.95±0.77）%,（37.91±0.58）%）,（（84.47±1.56） g/（m^2·d）,（89.90±1.98） g/（m^2·d））,（（45.98±1.75）%,（46.88±2.01）%）, and（（33.74±1.65） g/（m^2·d）,（34.08±1.32） g/（m^2·d））. Results indicated that the two marine microalgal strains with high CO2 fixation ability are potential strains for marine biodiesel development coupled with CO2 emission reduction.
