流化床反应室内铁矿石的临界流化特性

U型反应室是悬浮焙烧装备的核心部件,明确其内物料的临界流化特性具有理论与实践意义.为此,自行搭建了冷态试验系统,并以赤铁矿粉、氧化铝粉为原料,研究了松动风量、物料性质对物料临界流化特性的影响规律,并对原有经验公式进行了修正.结果表明:临界流化气速随物料粒度、密度的增加而增加;在松动室床层为固定床的条件下,临界流化气速随松动风量的增大而减小;修正后的过程方程与试验数据吻合较好,可用于反应室内物料流化行为的预测.研究结果利于悬浮磁化焙烧技术实体化,对该技术工业应用具有一定的指导意义.

卧式多室流化床干燥器内挡板对物料返混的影响

采用示踪粒子法研究了卧式多室流化床干燥器内挡板加入方式和挡板数日对粒子返混的影响。研究结果显示粒子在流化床表面返混最为强烈,所以挡板加在流化床表面能最有效抑制颗粒返混,改善物料在流化床中停留时间分布。

流化床干燥设备进展的研究

流化床干燥器因具有较高的热质传递速率、结构紧凑、便于操作等优点而被广泛用于化工、食品、陶瓷、制药等行业,就流化床干燥设备的种类及普遍存在的一些问题和解决方法做一简要综述。

厌氧流化床微生物燃料电池处理间甲酚废水及产电性能研究

以某水处理厂厌氧消化池活性污泥为接种体,间甲酚模拟废水为阳极液,构建了厌氧流化床单室无膜空气阴极微生物燃料电池(AFB-SMFC)。研究了开路和闭路操作条件下间甲酚的降解性能及其动力学,探讨了电化学作用与微生物降酚能力之间的关系,考察了外电阻、间甲酚浓度对AFB-SMFC降酚及产电性能的影响。结果表明:AFB-SMFC在闭路条件下的平均降酚速率为15.29 mg/(L·h),比开路条件(11.18 mg·L^(-1)·h^(-1))下提高了37%;闭路和开路条件下间甲酚降解反应均遵循零级动力学方程:-d St/dt=k;当外电阻为5 000Ω时,电池的产电性能最好,而外电阻为1 000Ω时间甲酚的去除率最高;当间甲酚初始浓度为570~630 mg/L时,AFBSMFC的产电性能和降酚效果俱佳,最大功率密度为324.4 m W/m^2,间甲酚去除率为96.2%。

芳烃吸附剂深度干燥冷却一体化技术

以某催化剂公司芳烃吸附剂干燥装置为依托,开发了一种半开放、半循环的芳烃吸附剂深度干燥、冷却一体化技术,此技术以内热式多室流化床为关键设备,其特点是系统能耗低,机械故障少,可操作性强。

Conversion of Fuel-N to N2O and NOx during Coal Combustion in Combustors of Different Scale

With focus on investigating the effect of combustor scale on the conversion of fuel-N to NOx and N20, experiments are carried out in three combustors, including single coal particle combustion test rig, laboratory scale circulating fluidized-bed boiler （CFB） and full scale CFB in this work. For single coal particle combustion, the majority of f-uel-N （65%-82%） is released as NOx, while only a little （less than 8%） fuel-N yields N20. But in labora- tory scale CFB, the conversion of fuel-N to N20 is increases, but the conversion of fuel-N to NOx is quite less than that of single coal particle combustion. This is because much char in CFB can promote the NOx reduction by in- creasing N20 formation. In full scale CFB, both of the conversion of fuel-N to NOx and the conversion of fuel-N to N20 are smaller than laboratory scale CFB.

Laboratory Research on Tahe AR Fluid Coking on Weak Acid Catalysts

Fluid coking on micro-spherical particles with acid sites on them could produce more light oils from Tahe AR.The conversion rate could increase by about 20% on the catalyst B compared to that obtained on the catalyst A and the light oil yield could increase by about 12%.The yield of gasoline and diesel was more than 50% from Tahe AR over the catalyst B.Tests on acidity of the catalyst B by pyridine FT-IR spectrometry showed that the total acid content and the ratio of weak acid number to total acid number were higher than other catalysts.

Responses of Hydrological Processes to Climate Change in the Zhujiang River Basin in the 21st Century

In this study, discharge at the outlet of Xijiang River, the biggest sub-basin of the Zhujiang River, was simulated and projected from 1961 to 2099 using the hydrological model HBV-D. The model uses precipitation and temperature data from CISRO/MK3 5, MPI/ECHAM5, and NCAR/CCSM3 under three greenhouse gas emission scenarios (SRES A2, A1B, B1). The results in water resources and flood frequency suggest that annual precipitation and annual runoff would increase after 2050 relative to the reference period of 1961-1990. In addition, increasing trends have been projected in area averaged monthly precipitation and runoff from May to October, while decreasing trends in those from December to February. More often and larger floods would occur in future. Potential increase in runoff during the low-flow season could ease the pressure of water demand until 2030, but the increase in runoff in the high-flow season, with more often and larger floods, more pressure on flood control after 2050 is expected.

An Experimental Investigation of Fluidized Bed Gasification of Biomass Blended from Wood, Miscanthus, Straw and other Industrial Bioresidues

In order to identify potential wood substitutes for the production of energy by gasification, binary blends （wood/miscanthus, miscanthus/straw and wood/straw） and ternary blends （wood, miscanthus and organic residue） were systematic tested in a laboratory bubbling fluidized bed gasification system. The results of experiments were compared with results of wood gasification. Of the binary blends, wood and miscanthus exhibited great potential as a wood substitute in fluidized bed gasification in terms of process stability and product gas quality. Adding 10 wt. % of organic residues to form ternary blends further improved the product gas quality. Gasification of fuels blended with straw tended to agglomerate in the fluidized bed because of straw＇s low ash melting temperature. This can be counteracted by adding Ca（OH）2 to fuels. Nonetheless, fuels blended with straw with higher percentages of Ca（OH）2 need further study to establish the optimal additive ratio.

Analysis of chamber effect on intermittent pulsation

A numerical study was conducted to seek an optimized dimension of jet chamber in the pulsating impinging flow.The flow and heat transfer effect of the pulsation flow through a jet chamber was investigated.The numerical results indicate that heat transfer effective enhances near the stagnation region for the intermittent pulsed flow with jet chamber compared to that without jet chamber.Simulations of the flow through a jet chamber show that the heat transfer rate on the impingement surface is highly dependent on the velocity at the position which is really close to target surface.Examination of the velocity field suggests that the velocity exists a maximum value as the axis distance increases.In addition,the velocity at the jet hole is enlarged by the jet chamber due to the entrainment effect,and the velocity is amplified even greater as the size of the jet chamber becomes bigger.Nevertheless,the velocity declines quickly while the flow axis distance is more than a certain range,leading to poor heat transfer.Thus,intermittent pulsed flow with jet chamber is suggested as a method of improving heat transfer by employing larger dimensions of jet chamber for appropriate jet-to-surface spacing.

Numerical Study on Effects of Door-Opening on Airflow Patterns and Dynamic Cross-Contamination in an ISO Class 5 Operating Room

The contamination diffusion to the operating room when the door is open was simulated with a computational fluid dynamic(CFD) method,to give the extent of the contamination diffusion.The influence of the door-opening procedure was ignored since the door of the operating room is normally a sliding one.The flow field in the case of the 16 s course of opening the door was simulated.The simulated and the experimental results demonstrate that the extent of the contamination diffusion is around 1.5 m when there is no temperature difference between indoor and outdoor,and there is hardly any contamination diffusion when the temperature difference is 1 ℃.It can be concluded that the positive pressure difference in the operating room lost its function in preventing the contamination when the door is open.That the temperature of corridor is lower than that of operating room contributes to contamination control.Keeping 1 ℃ temperature difference between corridor and operating room and increasing positive pressure and air flow are suggested.It is more secure to set up an anteroom if persons come in or out of the operation room at the course of surgery.

Advances in Nitrogen Denitrification and N_2O Emission in Agro-ecosystem

Nitrification and denitrification are two key links of nitrogen flow cycle in soil.N2O and N2,generated from biochemical process of nitrogen,can cause not only the nitrogen losses and reduction of nitrogen use efficiency,but also the boosted concentration of greenhouse gases,severely endangering the environment.Accordingly,nitrification-denitrification has been more and more concerned from whether an agricultural view,or an environmental one.Referring to the related literatures published at home and abroad in recent years,we overviewed the denitrification-caused N loss and N2O emission in various agro-ecosystems,and based on which we put forward countermeasures to reduce the denitrification-caused N loss and N2O emission and its research prospects in the future.

Development of the Novel Grid Type Multi-stage Regeneration Technology for FCC Unit

Based on the results of cold model tests, LPEC has developed a technology for regeneration of FCC catalyst in a regenerator with novel grid type internals in order to intensify the contact between gas and solid and enhance the coke burning efficiency in the regenerator. Test results have revealed that the density change in the fluidized bed equipped with grid internals is relatively homogeneous and the bubbling fre- quency is obviously reduced with apparent improvements in the dead fluidized zone adjacent to the regen- erator wall, and this device can be applied to the intensified regeneration of catalyst in the FCC regenerator. The commercial application of this device in a 0.8 Mt/a RFCCU at the refinery A had indicated that the carbon content of regenerated catalyst was reduced to 0.03% from 0.18%, and the amount of coke burned was increased by 5% with a definite reduction in main air consumption of the regenerator and some density reduction in the dilute phase section of the regenerator.

Rapid Elimination of Black Odor in Rivers by Oxygen Aeration

Laboratory research and engineering applications demonstrated that oxygen aeration can rapidly increase the level of dissolved oxygen in the water of severely polluted rivers. This method was capable of eliminating the odorous substances from black odorous water and reducing the color shade of water, but could not remove the NH3-N, COD, TP or other common pollutants. Therefore, oxygen aeration can be implemented to rapidly eliminate black odorous from rivers, lakes and reservoirs, but cannot be used as a permanent method for treating pollution of rivers.

Experimental Study on Combustion Characteristics and NOX Emissions of Pulverized Anthracite Preheated by Circulating Fluidized Bed

A 30 kW bench-scale rig of pulverized anthracite combustion preheated by a circulating fluidized bed （CFB） was developed. The CFB riser has a diameter of 90 mm and a height of 1,500 mm. The down-fired combustion chamber （DFCC） has a diameter of 260 mm and a height of 3,000 mm. Combustion experiments were carded out using pulverized anthracite with 6.74% volatile content. This low volatile coal is difficult to ignite and burn out. Therefore, it requires longer burnout time and higher combustion temperature, which results in larger NOx emis- sions. In the current study, important factors that influence the combustion characteristics and NOx emissions were investigated such as excess air ratio, air ratio in the reducing zone, and fuel residence time in the reducing zone. Pulverized anthracite can be quickly preheated up to 800~C in CFB when the primary air is 24% of theo- retical air for combustion, and the temperature profile is uniform in DFCC. The combustion efficiency is 94.2%, which is competitive with other anthracite combustion technologies. When the excess air ratio ranges from 1.26 to 1.67, the coal-N conversion ratio is less than 32% and the NOx emission concentration is less than 371 mg/m^3 （@6% O2）. When the air ratio in the reducing zone is 0.12, the NOx concentration is 221 mg/m^3 （@6% O2）, and the coal-N conversion ratio is 21%, which is much lower than that of other boilers.

Investigation of drying characteristics of low rank coal of bubbling fluidization through experiment using lab scale

Lignite is a low rank coal which is evenly distributed throughout the world and accounts for 45% of the total coal reserves. As it has a higher moisture content, its moisture content must be reduced in order to utilize it in power plant. In the present work, experiments on lignite has been done using a lab scale fluidized-bed reactor. Drying lignite through fluidized-bed reactor has a higher drying rate because there is good contact between particles and gas in the fluidized-bed reactor. Fluidized-bed drying can use air of 1.5 times of the minimum fluidizing velocity performance at bubbling fluidized-bed. Experiments have been performed on coal particle sizes of 0.3-1 mm, 1-1.18 mm and 1.18-2.8 mm, with operating temperatures being 100℃, 125℃ and 150℃, respectively. It is found that fluidization has a higher drying rate due to the heat transfer rate through air velocity. Hence, moisture content in lignite can be dried to a desired value with a time interval of 10 rain. The experiment through fluidized-bed reactor is expected to be useful for saving money and time.

Wall sheeting diagnosis in fluidized beds based on chaos analysis of acoustic emission signals

A novel method, based on acoustic emission (AE) techniques, for detecting agglomeration in fluidized beds is presented. Particle size characteristics are determined based on the principle that AE signals with different frequency band energies are emitted when particles of different sizes impact an internal wall. By applying chaotic analysis to the AE signals, the malfunction coefficients are well defined. Agglomeration in the fluidized bed can then be detected by the sudden variation of malfunction coefficients. AE signals were investigated in a laboratory scale heated fluidized bed and an industrial polyethylene fluidized bed. Experimental data showed that the malfunction coefficients increased with the growth of agglomeration. The results indicated that agglomeration in fluidized beds can be predicted and diagnosed effectively and precisely using AE techniques based on chaotic analysis.

Effect of Swirl Cup's Secondary Swirler on Flow Field and Ignition Performance

In a gas turbine engine combustor, highly swiding combustion is usually adopted to stabilize flame and reduce pollutant emissions. Swirl cup, as an air blast atomizer, is widely used to provide a uniform presentation of fuel droplets to the combustor dome. This paper investigated the effect of secondary swirler on the flow field down- stream of the swirl cup using particle image velocimetry （PIV）. Three swirl cups＇ non-reacting flow field were studied： case A, B and C with secondary swirler vane angle 53°, 60° and 68° respectively. Detailed mean and transient velocities and vorticity in the center plane were obtained. From the PIV results, a sharp contrast flow field was obtained for case A to other two cases due to the lower secondary swirling intensity. The recirculation zone is collapsed in disorder for the case A. Ignition tests of the three cups were completed in a single cup com- bustor. In general, the ignition performance increases with the increasing of the secondary swirling intensity. For case A, the ignition performance is very unstable and has much randomness and there is no clear lean ignition boundary can be generated. This work can further understand the swirl behavior and ignition mechanism.