确定多孔介质孔结构参数的渗流网络分析法

According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore structure parameter--mean coordination number of pore network, which represents the connectivity among a great number of pores. Here the “chamber-throat“ model and the Weibull distribution are used to describe the pore geometry and the pore size distribution respectively. This method is based on the scaling law of percolation theory after both effects of sorption thermodynamics and pore size on the sorption hysteresis loops are considered. The results show that it is an effective procedure to calculate the mean coordination number for micro- and meso-porous media.     

Adsorption characteristics of construction waste for heavy metals from urban stormwater runoff☆

Stormwater runoff has become an important source of surface water pollution. Bioretention, a low impact devel-opment measure in urban stormwater management, has been proven to be effective in the removal of pol utants from stormwater runoff, with appropriate bioretention media. In this study, construction wastes were selected as bioretention media to remove heavy metals from stormwater runoff. Static and dynamic adsorption batch exper-iments were carried out to investigate the adsorption of heavy metals in simulated stormwater runoff system with construction wastes in different particle sizes. The experimental results show that the pseudo-second-order kinetic model characterizes the adsorption process and the adsorption equilibrium data are wel described by Freundlich isotherm model. The construction wastes used can remove heavy metals from stormwater runoff effectively, with their average removal rates al more than 90%. The particle size of construction wastes greatly influences the equilibrium time, rate and adsorption capacity for heavy metals.     

Occurrence,leaching behavior,and detoxification of heavy metal Cr in coal gasification slag

Coal gasification slag(CGS) is a type of solid waste produced during coal gasification, in which heavy metals severely restrict its resource utilization. In this work, the mineral occurrence and distribution of typical heavy metal Cr in CGS is investigated. The leaching behavior of Cr under different conditions is studied in detail. Acid leaching–selective oxidation–coprecipitation method is proposed based on the characteristics of Cr in CGS. The detoxification of Cr in CGS is realized, and the ...     

Industrial-scale fixed-bed coal gasification: modeling,simulation and thermodynamic analysis

We have developed a process model to simulate the behavior of an industrial-scale pressurized Lurgi fixed-bed coal gasifier using Aspen Plus and General Algebraic Modeling System （GAMS）. Reaction characteristics in the fixed-bed gasifier comprising four sequential reaction zones-drying, pyrolysis, combustion and gasification are respectively modeled. A non-linear programming （NLP） model is developed for the pyrolysis zone to estimate the products composition which includes char, coal gases and distillable liquids. A four-stage model with restricted equilibrium temperature is used to study the thermodynamic equilibrium characteristics and calculate the composi-tion of syngas in the combustion and gasification zones. The thermodynamic analysis shows that the exergetic effi-ciency of the fixed-bed gasifier is mainly determined by the oxygen/coal ratio. The exergetic efficiency of the proc-ess will reach an optimum value of 78.3%when the oxygen/coal and steam/coal mass ratios are 0.14 and 0.80, re-spectively.     

CONTINUOUS THERMODYNAMICS FOR POLYMER SOLUTIONS I.CLOSE-PACKED LATTICE MODEL

using close-packed lattice models,a continuous thermodynamic framework is presented forphase-equilibrium calculations for binary solutions with a polydisperse polymer solute.An expressionfor the Helmholtz function of mixing is based on the revised Freed model developed previously.Asize parameter c_r and an energy parameter ε are used;the former can be temperature dependent,while the latter can depend on both temperature and chain-length of the polymer.The discretemulticomponent approach is adopted to derive expressions for chemical potentials,spinodals and criti-cal points.The continuous distribution function is then used in calculations of moments occurring inthose expressions.Computation programs are established for cloud-point-curve,shadow-curve,spinodal and critical-point calculations for polymer solutions with standard distribution or arbitrarydistribution of polymer.In the latter case,the derivative method developed previously is applied.lllustrations for phase-equilibrium calculations are shown     

三水碳酸镁在Li+Na+K十NH4+Mg+Cl+H2O体系中溶解度的全组分化学模拟（英文）

A chemical model,based on Pitzer activity coefficient model,is developed with a speciation approach to describe the solubility and chemistry of nesquehonite in concentrated chloride solutions.The chemical equilibrium constants for nesquehonite and aqueous species,i.e.0 3 MgCO,3 MgHCO,and MgOH +,are precisely calculated as a function of temperature according to the Van’t Hoff equation by use of standard Gibbs free energy,standard formation enthalpy and heat capacity.The most recent solubility data are regressed to obtain new Pitzer parameters with good agreement.The predictive ability of the new model is improved significantly in comparison with previous models.The behavior of speciation chemistry for nesquehonite in various chloride media is explained through this modeling work on the basis of the 2 3 Mg /CO bearing species distribution,activity coefficient and pH changes.     

不敏变换鲁棒Kalman滤波器在发酵过程中的应用(英文)

State estimation is the precondition and foundation of a bioprocess monitoring and optimal control. However, there are many difficulties in dealing with a non-linear system, such as the instability of process, un-modeled dynamics, parameter sensitivity, etc. This paper discusses the principles and characteristics of three different approaches, extended Kalman filters, strong tracking filters and unscented transformation based Kalman filters. By introducing the unscented transformation method and a sub-optimal fading factor to correct the prediction error covariance, an improved Kalman filter, unscented transformation based robust Kalman filter, is proposed. The performance of the algorithm is compared with the strong tracking filter and unscented transformation based Kalman filter and illustrated in a typical case study for glutathione fermentation process. The results show that the proposed algorithm presents better accuracy and stability on the state estimation in numerical calculations.     

基于多场协同理论的渗透蒸发传质模型

Toprovide a theoretical basis for optimizing the pervaporation procedure, a mass transfer model for pervaporation for binary mixtures was developed basedon the multi-fields synergy theory. This model used the mechanism of sorption-diffusion-desorption and introduced a diffusion coefficient, which was dependent on the feed concentration and temperature. Regarding the strong coupling effect in the mass transfer, the concentration distribution in membrane was predicted using the Flory-Huggins thermodynamic theory. The batch experiments and other experiments with constant composition-were conducted-using a modified chitosan pervaporatioffmembrane to separate tert-butyl alcohol （TBA）-water mixtures. The parameters of the mass transfer model were obtained from the flux of the experiments with a constant composition and the activity coefficients available through phase equilibrium equation, using the Willson equation in the feed side and the Flory-Huggins thermodynamic theory within the membrane The simulation results of the experiments .are in good agreement with the results, of the experiments.     

Prediction of Swelling Behavior of AT-Isopropylacrylamide Hydrogels in Aqueous Solution of Sodium Chloride

In this paper, a model is presented to correlate and predict the swelling behavior of hydrogels in aqueous solutions of electrolytes. The model is a combination of VERS-model, "phantom network" theory and "free-volume" contribution. The VERS-model is used to calculate Gibbs excess energy; "phantom network" theory to describe the elastic properties of polymer network, and "free-volume" contribution to account for additional difference in the size of the species. To test the model, a series of N-isopropylacrylamide based hydrogels are synthesized by free radical polymerization in oxygen-free, deionized water at 25℃ under nitrogen atmosphere. Then, the degree of swelling of all investigated gels as well as the partition of the solute between the gel phase and the surrounding coexisting liquid phase are measured in aqueous solution of sodium chloride. The model test demonstrates that the swelling behavior correlated and predicted by the model agrees with the experimental data within the experimental uncert     

费-托合成鼓泡浆态反应器的湍流区双气泡模型

A model for a bubble column slurry reactor is developed based on the experiment of Rhenpreuszen-Koppers demonstration plant for slurry phase Fischer-Tropsch synthesis reported by Koelble et al. This model is applicable to the operation in the churn-turbulent regime and incorporates the information on the bubble size. The axial dispersion model is adopted to describe the flow characteristics of the Fischer-Tropsch slurry reactor. With the model developed, simulations are performed to identify the steady state behavior of a Fischer-Tropsch slurry reactor of commercial size. Predictions of the two-bubble class model is compared with that of the conventional single- bubble class model. The results show that under a variety of conditions, the two-bubble class model gives results different from those for the single-bubble class model.     

不同粒径城市垃圾焚烧飞灰中重金属的浸出规律研究

集中焚烧法已经逐渐成为我国城市生活垃圾处理的主要方式,但其中的重金属在焚烧过程中不会被破坏,最终主要集中在垃圾焚烧飞灰中排出。在垃圾焚烧飞灰的安全填埋过程中由于受到环境因素的影响,例如酸雨,其中的重金属会逐渐的发生迁移,从而影响环境。文章对不同粒径的垃圾焚烧飞灰中的重金属浸出特性进行了研究,实验结果表明：小粒径垃圾焚烧飞灰所占比例较大。不同粒径对重金属的浸出特性比较复杂,浸出浓度均不相同,其中除尘器飞灰中的重金属浸出浓度远高于其他三种飞灰,属于有浸出毒性的危险废物。     

Prediction of gaseous pollutants and heavy metals during fluidized bed incineration of dye sludge

This research provides an equilibrium model for predicting both the emission of gaseous pollutants and the fate of heavy metals during incineration of biologically treated dye sludge in a bench-scale fluidized bed incinerator. Major gaseous pollutants and hazardous trace heavy metals have been also measured under various operating conditions. The predicted values, which were derived by using a thermodynamic equilibrium model, can be used to determine the optimum operating parameters and the risk associated with hazardous waste incineration by means of verifying experimental data. However, prediction of NO_x emission using a thermodynamic equilibrium model during incineration of waste was not simple. The reason is that the variation of NO_x emission during incineration of waste was affected by the various operating parameters, such as air-fuel ratio(λ _T ), primary air factor(λ ₁ /λ _T ), combustor geometry, method of heat release, and preheating of combustion air. According to the distributions of Cr and Pb simulated by the equilibrium model, all of the Cr in the feed was retained in the ash as the solid phase of Cr₂CO₃. However, most Pb was retained in the ash during incineration as the solid phase of PbSO₄, or heterogeneously deposited onto the fly ash as PbO(g) when the combustion gas becomes cool. Presented at the Int’/Sym. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his retirement from Korea University.     

城市生活垃圾焚烧飞灰组成特性及重金属熔融固化处理技术研究进展

近年来,我国城市生活垃圾清运量以每年5%左右的增速发展,垃圾焚烧处理能力不断提升,而垃圾焚烧过程会产生占焚烧总量3%~5%的垃圾焚烧飞灰。随着垃圾焚烧处理能力的不断提升,垃圾飞灰产量逐年增加,飞灰处置压力越来越大。城市生活垃圾焚烧飞灰作为一种高重金属浸出毒性的危险废弃物,对环境存在较大危害。论述了城市生活垃圾焚烧飞灰的组成特性及重金属的分布和性质,从飞灰熔融过程原理、重金属转化特性、重金属固化影响因素等方面阐述了熔融处理垃圾飞灰技术的研究进展,探究了飞灰组分和熔融条件对熔融过程及重金属固化效果的影响。论述了等离子熔融技术和熔融固化重金属的效果,最后对飞灰复配熔融及冷却过程优化处理给出参考性建议,并指出飞灰熔融处理技术未来发展方向。垃圾焚烧飞灰中重金属主要以其氧化物、氯化物、硫酸盐形式存在,熔融处理可以改变飞灰组分及相态,使飞灰发生多晶转变和熔融相变过程,重金属离子发生同晶置换反应,被固化在硅酸盐的Si—O四面体晶格结构中,很大程度上降低了飞灰的浸出毒性并实现熔渣资源化利用。熔融处理过程中,熔融气氛、时间及飞灰组分对过程特性和重金属的迁移转化影响较大,冷却方式不同会影响玻璃体熔渣的物理性质。根据重金属的熔点和沸点特性,在熔融处理后,烟气和二次飞灰中会携带部分挥发性强、沸点低的重金属。在今后研究中需要对烟气和二次飞灰进行冷却或二次捕集处理,并对烟气成分进行探究。由于熔融处理过程耗能大、投资高、关键设备研发难攻关,我国垃圾焚烧飞灰熔融处理技术仍处于技术研发阶段,尚无稳定化工业运行实例,但已有部分中试研究试验。熔融处理前,应先分析飞灰组成成分,根据飞灰组成进行预处理。通过添加助熔剂、调节飞灰碱度对飞灰进行复配熔融处理,降低熔融处理的能耗,高效稳定处理重金属。在实验室稳定有效试验的基础上,可以对等离子体熔融处理装置进行技术改进和创新,提高等离子火焰稳定性,实现熔渣的高效分离,提升装置耐久性。     

污泥热解残渣中重金属形态分布的研究进展

目前，我国城市及工业污水产生量已达7.34×10¹⁰ t/a，对其处理产生的污泥量达7.29×10⁷ t/a。污泥的主要去向为土地利用、焚烧发电和建材利用等。在这些再利用过程中，重金属特别是Cr、Cu、Zn、Ni等对其再利用影响较大。污泥处理多采用热解处理，重金属在处理过程中会富集在热解残渣中。阐释重金属在热解残渣中的形态分布，对于其再利用过程意义重大。本文以改进的欧共体物质标准局(BCR)连续提取法为基础，总结了污泥热解残渣中重金属的形态分布，阐述了热解工况(热解温度、停留时间、催化剂)、共热解及预处理对热解残渣中重金属形态分布的影响，探讨了污泥热解残渣中重金属未来的研究趋势。     

Electroremediation of air pollution control residues in a continuous reactor

Air pollution control (APC) residue from municipal solid waste incineration is considered hazardous waste due to its alkalinity and high content of salts and mobile heavy metals. Various solutions for the handling of APC-residue exist, however most commercial solutions involve landfilling. A demand for environmental sustainable alternatives exists and electrodialysis could be such an alternative. The potential of electrodialysis for treating APC-residue is explored in this work by designing and testing a continuous-flow bench-scale reactor that can work with a high solids content feed solution. Experiments were made with raw residue, water-washed residue, acid washed residue and acid-treated residue with emphasis on reduction of heavy metal mobility. Main results indicate that the reactor successfully removes toxic elements lead, copper, cadmium and zinc from the feed stream, suggesting that the electrodialytic technique is an alternative to land deposition of APC-residues.     

Effect of Cl/S molar ratio on theoretical partitioning of heavy metals under waste combustion conditions

A simulation calculation was carried out to predict the behavior of heavy metals during waste incineration according to the variation of chlorine content by using a thermodynamic equilibrium model. To predict the behavior of heavy metals in incineration of wastes, chlorine content in wastes was changed up to 3.00 on a Cl/S molar ratio basis. Then the partitioning characteristics of heavy metals with Cl/Metal molar ratio were investigated as solid, liquid, and gas phases of metals. For analysis of emission characteristics, incineration temperature, chlorine content and air-fuel ratio (λ_r) were chosen as major operating parameters. It was found that the distribution characteristics of heavy metals were not significantly affected by air-fuel ratio, but evaporation rate of heavy metals increased with operating temperature. Most of the heavy metals remained in solid phase of metal oxides, such as CdO, CrO₃, CrO₂, CuO and ZnO, except for lead which existed as PbSO₄ in the given operating conditions (i.e., T_b=800 °C, λ_r=1.3, and Cl/S=0). It was found that most of the heavy metals in solid phase changed to gaseous Cl compounds, which have a high volatility with regard to increasing the Cl/S molar ratio under the same conditions. However, Cr compounds were almost not affected as chlorine level increased. This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University.     

重金属在水泥窑协同处置的净浆硬化体中的分布及形态

通过欧共体标准物质局（European Community Bureau of Reference）提出的一种三级4步提取法（BCR）,分析了垃圾焚烧飞灰和经水泥窑协同处置的净浆硬化体中重金属的分布和形态。探究了随水化反应的进行,其重金属形态转化的趋势。结果表明,重金属主要分布在氢氧化钙、水化硅酸钙（C-S-H）、钙矾石（AFt）和未水化的水泥熟料中。随着水化反应的进行,Zn、Cu、Cr、Cd和Mn皆有向迁移能力较强的形态转化的趋势,其中Cr和Cd的转化趋势较为明显。与垃圾焚烧飞灰相比,重金属通过水泥窑高温煅烧和水化反应,其迁移能力较强的形态占比明显减少。     

Test of electrodialytic upgrading of MSWI APC residue in pilot scale: focus on reduced metal and salt leaching

In this study a pilot plant for electrodialytic treatment of municipal solid waste incineration (MSWI) air pollution control (APC) residue was tested and proposed as a treatment method which can lead to reuse of this otherwise hazardous waste. The pilot plant was developed based on a design that is adapted from conventional electrodialysis, e.g. used in desalination of solutions. The APC residue was treated in a suspension (8 kg APC residue and 80 L tap water) and circulated through an electrodialytic (ED) stack consisting of 50 cell pairs separated by ion exchange membranes. A direct current was applied to the ED stack for removal of heavy metals (As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Zn) and salts (Cl, Na, SO₄) from the APC residue suspension. Different tank designs for mixing the APC residue suspension were tested as well as changing experimental conditions. A part of the raw experimental APC residue was carbonated by reaction with CO₂ under moist conditions prior to electrodialytic treatment. The carbonation alone reduced the leaching of some heavy metals. However, it was not sufficient to reduce the heavy metal or salt leaching to meet the Danish Category 3 guideline levels for waste material reuse and could not stand as a treatment method alone. Leaching of both heavy metals and salts were significantly reduced by the electrodialytic treatment for both the raw and carbonated APC residue. In the electrodialytically treated carbonated APC residue only Cr exceeded the Category 3 levels while in the electrodialytically treated raw APC residue both Pb and Zn leaching exceeded the Category 3. Optimization of the electrodialytic upgrading method is necessary to meet the Category 3 levels for all heavy metals. Removal of Na and SO₄ to below the Category 3 leaching levels were obtained in all the experiments. Cl removal was not sufficient in all experiments even if up to 1 kg of Cl was removed, the optimal conditions for Cl removal was a constant current of 5 A over the ED stack. The results of this study suggest that, with some optimization, electrodialytic upgrading, possibly in combination with carbonation, could be used as a treatment method for MSWI APC residue.     

Mechanisms of particle agglomeration and inhibition approach in the existence of heavy metals during fluidized bed incineration

Agglomeration occurring during fluidized bed incineration not only causes the fluidization characteristics to change and the system to unexpectedly shut down, but it also leads to the generation of secondary pollutants such as heavy metals. Accordingly, the aim of this study is to estimate the mechanisms of particle agglomeration in fluidized bed incineration. Experiments are carried out, including a pilot-scale fluidized bed test and a laboratory furnace test. Thermodynamic equilibrium simulations are also considered. In addition, the speciation of agglomerates is determined from the analysis of the laboratory furnace using X-ray diffraction (XRD), electron spectroscopy for chemical analysis (ESCA), and field emission scanning electron microscopy/energy dispersive spectrometry (FESEM–EDS). The experimental results reveal that higher concentrations of metals are emitted when defluidization occurs. When we compare the results from two different agglomeration inhibitors, the Al-based additive is shown to achieve higher levels of inhibition versus a Ca-based additive. In addition, the results from our simulation illustrate that the heavy metals Pb, Cr, and Cd have different affinities with Na, Si, Al, and Ca, which causes different emission behaviors during the agglomeration inhibition processes. Good agreement is observed among the experimental data, the agglomerate characterization, and the thermodynamic equilibrium simulations. The primary mechanisms of both particle agglomeration and the emission of heavy metals are also established.     

电弧炉熔融医疗垃圾焚烧灰的实验研究

利用处理量为2 kg的直流电弧炉对医疗垃圾焚烧的底灰、底灰与布袋飞灰的混合灰分别进行熔融实验研究,并比较了熔融前后灰和熔渣的化学成分、物相、微观形貌、浸出毒性及重金属残留率. 结果表明,底灰主要由复杂的硅酸盐晶体组成,布袋飞灰含有大量的硬石膏(CaSO4)、氯化钠(NaCl)晶体,熔融后两种熔渣均为无定形非晶态的玻璃熔岩. 底灰、混合灰熔融后减容率分别达到78%和80.5%;熔融前布袋飞灰浸出液中Pb, Cd, Zn浓度远超过危险废物填埋限值,熔融后的熔渣中重金属固化在Si-O网格中,渗沥液中浓度极低,完全符合环保要求. 熔融后2种熔渣中Pb, Cd, Zn的残留率较低,而且混合灰熔渣中重金属残留率均低于底灰熔渣.