Modeling and Simulation of Liquid Pulsed Particulate Fluidized Beds

Pulsed fluidization is of considerable interest in process engineering for improving fluidization quality. Quantitative understanding of the pulsed two-phase flow behaviors is very important for proper design and optimum operation of such contactors. The

Numerical Simulation of Pulsed Liquid Fluidized Bed and Its Experimental Validation

The pulsed liquid fluidized bed was studied using numerical simulation and experimental methods, The area-averaged two-fluid model (TFM) was used to simulate the pulsed fluidization. The bed expansion and collapse processes were simulated first and the phenomena obtained from the calculation were consistent with our previous experiments and observations. In the pulsed fluidization, the variation of bed height, the variations of particle velocity and concentration distribution were obtained and analyzed. Experiments were carried out to validate the simulation results. The pressure variation with time at different locations was measured using pressure transducers and compared with the simulated results. The variations of bed height and particle concentration distribution were recorded using a digital video camera recorder. The results were consistent with the simulation results as a whole.

Novel experimental phenomena of fine-particle fluidized beds

The dynamic response of bed height and concentration waves in liquid-solid fluidized beds to a step change in the fluidization velocity is considered. We experimentally study the liquid-solid fluidized beds, spherical beadings, with sizes ranging from 230 to 270 mesh and the inner diameter of columns made from glass is 2.4 mm. Experimental results find that under certain conditions, fine particles with large Richardson-Zaki exponent n display different dynamic behavior from usual particles with smaller n during expansion and collapse of the fluidized state. (c) 2007 Elsevier Inc. All rights reserved.

Operational characteristics of a 1.2-MW biomass gasification and power generation plant

In this study, we analyzed the operational characteristics of a 1.2-MW rice husk gasification and power generation plant located in Changxing, Zhejiang province, China. The influences of gasification temperature, equivalence ratio (ER), feeding rate and rice husk water content on the gasification characteristics in a fluidized bed gasifier were investigated. The axial temperature profile in the dense phase of the gasifier showed that inadequate fluidization occurred inside the bed, and that the temperature was closely related to changes in ER and feeding rate. The bed temperature increased linearly with increasing ER when the feeding rate was kept constant, while a higher feeding rate corresponded to a lower bed temperature at fixed ER. The gas heating value decreased with increasing temperature, while the feeding rate had little effect. When the gasification temperature was 700-800C, the gas heating value ranged from 5450-6400kJ/Nm3. The water content of the rice husk had an obvious influence on the operation of the gasifier: increases in water content up to 15% resulted in increasing ER and gas yield, while water contents above 15% caused aberrant temperature fluctuations. The problems in this plant are discussed in the light of operational experience of MW-scale biomass gasification and power generation plants.

Study on biomass circulation and gasification performance in a clapboard-type internal circulating fluidized bed gasifier

We investigated the solid particle flow characteristics and biomass gasification in a clapboard-type internal circulating fluidized bed reactor. The effect of fluidization velocity on particle circulation rate and pressure distribution in the bed showed that fluidization velocities in the high and low velocity zones were the main operational parameters controlling particle circulation. The maximum internal circulation rates in the low velocity zone came almost within the range of velocities in the high velocity zone, when uH/umf = 2.2-2.4 for rice husk and uH/umf = 3.5-4.5 for quartz sand. In the gasification experiment, the air equvalence ratio (ER) was the main controlling parameter. Rice husk gasification gas had a maximum heating value of around 5000 kJ/m3 when ER = 0.22-0.26, and sawdust gasification gas reached around 6000-6500 kJ/m3 when ER = 0.175-0.24. The gasification efficiency of rice husk reached a maximum of 77% at ER = 0.28, while the gasification efficiency of sawdust reached a maximum of 81% at ER = 0.25.

The design and operation of a new clapboard-type internal circulating fluidized-bed gasifier

The design and operation of a new clapboard-type internal circulating fluidized-bed gasifier is proposed in this article. By arranging the clapboard in the bed, the gasifier is thus divided into two regions, which are characterized by different fluidization velocities. The bed structure is designed so that it can guide the circulating flow passing through the two regions, and therefore the feedstock particles entrained in the flow experience longer residence time. The experimental results based on the present new design, operating in the temperature range of 790 degrees C-850 degrees C, indicate that the gas yield is from 1.6-1.9 Nm(3)/kg feedstock, the gas enthalpies are 5,345 kJ/Nm(3) for wood chip and 4,875 kJ/m(3) for rice husk, and a gasification efficiency up to 75% can be obtained.

厌氧好氧一体化生物反应器处理发酵废水的中试研究

一体化反应器由于投资少、占地小、管理运行方便等优点而备受青睐。但现有的一体化反应器大都适用于处理中低浓度废水，耐受负荷普遍偏低。本课题研制出新型高效的厌氧好氧一体化生物反应器，旨在通过反应器结构优化、高效微生物载体研制、配合高效微生物菌剂技术处理中高浓度有机废水，实现高效和低耗，降低设备造价，提高反应器运行稳定性。 首先开展了菌剂对废水的适配试验。采用15种不同的微生物菌剂，以葡萄糖配水、中药提取废水、啤酒废水、氨氮配水为基质，分别测定了微生物菌剂的耗氧速率和厌氧比产甲烷速率，以其为指标比较了各菌剂对废水的适配性。根据结果选择活性高的14＃、8＃、10＃菌剂，在试验室进行了菌剂对废水的连续处理试验，取得良好的处理效果，为菌剂在厌氧好氧一体化生物反应器的小试、中试中的应用奠定了基础。 经小试研究后，又对厌氧好氧一体化生物反应器进行了处理发酵废水的中试研究。试验结果表明，反应器启动快，系统有机负荷2.72 kgCODm-3d-1时整个反应器去除率保持在84.5％～93.19％，在30多天内一次启动成功。冲击负荷试验中，系统总有机负荷最高可达到8.88 kgCODm-3d-1，系统去除率稳定在88.10％～96.88%，说明反应器处理效率高，抗冲击能力强。稳定运行期间，COD去除率可达90％以上，各项指标都能达到国家排放标准。 此外，对反应器配套系统高效菌剂、高分子复合颗粒载体进行了研究。结果显示，菌剂与反应器适配良好，各功能区形成了丰富、高活性的微生物，厌氧区颗粒污泥TS高达83.9 gL-1，VS/TS为56.9％～57.4％，比产甲烷活性为280～350 mLCH4 gvss-1d-1；好氧区固定化微生物TS高达1.921 gL-1，VS/TS为94.02～94.30％。对载体性能的研究表明，此高分子复合颗粒载体密度适中，易于流化，不易流失；粗糙多空，易于挂膜；且无生物毒害作用，稳定安全，是一种优良的生物载体。反应器各功能区对废水的降解过程分析，说明了反应器、菌剂、载体适配良好，在其协同作用下，实现了污染物的高效降解。 The integrated reactors were popular because of their characteristics such as little investment, small occupation of land, convenient of manage and running etc. But the present integrated reactors were mostly applied for treating wastewater of low concentration, the load tolerance was generally on the low side. A new type integrated anaerobic-aerobic bio-reactor was developed, which was conducted to treating organic wastewater of middle or high concentration by optimization of reactor structure, development of efficient microbe carrier and adaptation of high active microbial blends, to achieve high efficiency and low consume, reduce equipment cost, enhance running stabilization of reactor. The adaptability test of microbial blends on different wastewater was carried on firstly. Oxygen consumption rate and anaerobic specific activity of methane producing of 15 different microbial blends were measured separately taking glucose artificial wastewater, Chinese herb extracting wastewater, brewery wastewater and ammonia nitrogen artificial wastewater as substrate, by which the adaptabilities of different microbial blends to wastewater were compared. According to the results high active microbial blends 14#, 8# and 10# were selected and used in the continuous treatment of wastewater in the laboratory and had obtained good effect, which had laid a foundation for application microbial blends to small scale test and pilot test of integrated anaerobic-aerobic bio-reactor. After the small scale test, the pilot test of the integrated anaerobic-aerobic bio-reactor treating fermentation wastewater was carried on. The test results showed fast initiation of the reactor. When system organic load reached 2.72 kgCODm-3d-1the COD removal rate of the reactor was stable between 84.5%～93.19% and it initiated successfully in more than 30 days at a time. In the load shock test the maximum organic load of system could reach to 8.88 kgCODm-3d-1 and the COD removal rate could be stable between 88.10%~96.88% which indicated that the reactor was efficient for treating wastewater and had strong resistance to shock load. At stable running period the COD removal rate of the reactor was over 90% and each index of wastewater could reach to the national discharge standards. In addition, the high active microbial blends and the macromolecule compound granule carrier, the matching system of the reactor was studied. It showed that the microbial blends adapted well to the reactor and abundant and high active microbes were formed in each functional field. The TS of granule sludge in anaerobic field was as high as 83.9 gL-1, the VS/TS was 56.9%~57.4%, the specific activity of methane producing was 280~350 mLCH4 gvss-1d-1. And the TS of immobilized biological granule was as high as 1.921 gL-1, the VS/TS was 94.02%~94.30%. Study on the carrier showed that the self-made macromolecular compound granule carrier was moderate of density, easy of fluidization, unease of running off, rough and porous, easy of films fixation, no bio-toxic, stable and safe, was a kind of superior carrier. Analysis of degradation process in each functional field confirmed the reactor, microbial blends and carriers were in good adaptation and wastewater was decontaminated by their cooperation.

广西合山固体废弃物制备地质聚合物胶凝材料

Geopolymer gelatinous material was prepared by ferroalloy slag (signed with NKT in laboratory) and circulating fluidization bed slag (CFB slag, signed with NM in laboratory) produced from Heshan city, Guangxi zhuang autonomous region, China. The mechanical properties of the geopolymer made of high content ferroalloy slag can reach the standard of 42.5# portland blastfurnace-slag cement, and it’s processing technology is more simple and not need of mill and burn and will not produce harmful gas. By means of chemical and XRD analyses, it is concluded that NKT is a kind of acidity water-granulated slag with better activation and fit to be activated by alkali activators. Low-cost industrial gypsum (signed with NG in laboratory), analytic reagent oxide(signed with NH in laboratory) and sulfate(signed with NS in laboratory) were selected as alkali activation in the experiment. The results showed NH is a good alkali activator for NKT. Both NH and NG can activate ferroally slag’s activities, but NS can’t alone. The activation effect of superimposing activation of NH and NG excel by separateness. Based on those experiments, optimization compounds were carried out: (1) NKT: NH: NG = 80: 10: 10 and (2) NM: NKT: NS: NG: NH = 10: 70: 2: 8: 10。. The soundness of the test blocks is good by boiling examination. Through XRD, SEM, IR, NMR analyses of geopolymer, the reaction mechanism of geopolymer prepared by alkalescent activating in solid wastes was discussed in the thesis first. It is point out, there is difference in reaction mechanism between traditional geopolymer preparation and the preparation of alkalescent activating solid wastes because NG is a industry product. There is the similar process of depolymerization and reunion of Si-O bond. The latter preparation process generate new subtance but the former doesn’t. In the experiment, we found a performance of NKT that the water requirement of normal consistency of geopolymer reduces with increasing content of NKT. The result shows NKT has some ability to reduce water requirement. The performance is worthy of further research and utilization. Making use of solid wastes to prepare geopolymer, not only can settle environment problem caused by a great deal of dump of NKT, but also settle the shortage of natural resources. Moreover it could take economic, environmental and social benefits and settle thoroughly contradiction in the environment protection and regional economy development and promote circulation economy development.

山西堡子湾金矿角砾岩带控矿规律、成矿时代及隐伏矿体定位预测

The Puziwan gold deposit is located at the northern boundary of the North China platform where there are very favorable ore-forming conditions. The deposit is a medium-sized gold deposit associated with silver and copper polymetallic minerallization which were closely related to cryptoexplosive processes and fluidization and underwent multi-epoch superposition of mineralization. The mineralization consists of cryptoexplosive breccia-type, fluidizing-type, porphyry-type, quartz vein-type, etc. The ore-controlling law of ore-bearing brecciated zone is systematically studied in the paper. The shape, scale and attitude of ore bodies are dominat in the upper, the ore bodies of fluidizing breccia-type are dominant in the upper and the middle part, the porphyry-type ore bodies are dominant in the bottom. The quartz vein-type ore bodies are impenetrated in all the brecciated zone. The metallogenic epoch of Puziwan gold deposit is collated and stipulated. The Rb-Sr isochron age of quartz porphyry (wall rock) is 233 Ma, refering to the Ar-Ar age of gold-bearing quartz, excluded the former conclusion that the so-called metallogenic epoch (245.9Ma) is in Indosinian epoch. The nonage metallogenic age of Buziwan gold deposit shoule be in the Yanshanian epoch (142.5Ma). By applying the sub-specimen sampling technique, the Rb-Sr isochron age of gold-bearing pyrites in late mineralization epoch is dated to be 64 Ma. In conclusion, the metallogenetic epoch of Puziwan gold deposit is in late Yanshanian-early Himalayan epoch. On the above basis, the metallogenic model of the "train type" and new texture model of ore deposit are established. by applying the methods of geology, shallow seismic exploration, remote sensing, partial geochemical extraction and the study of inclusions in the late granite porphyry, the author has made the metallogenic progosis in the depth and the prephery of Puziwan gold deposit and eight prospecting targets are proposed.