模拟城市垃圾焚烧中硫化合物对重金属Cd迁移分布的影响

The effect of sulfur compounds （including sulfur, sulfide, sulfite and sulfate）, initial concentration of heavy metal and operating conditions on Cd emission in municipal solid waste （MSW） incineration were investi-gated using a simulated tubular furnace and simulated MSW spiked with Cd. The concentration of Cd was meas-ured by inductively coupled plasma-atomic emission spectrometry （ICP-AES） after digesting the samples including bottom ash, fly ash and flue gas according to related USEPA methods. The results show that S and Na2S tend to in- crease Cd partitioning in bottom ash, whereas Na2SO3 and Na2SO4 tend to reduce Cd partitioning in bottom ash. The effect of sulfur compounds on Cd partitioning in bottom ash was in the sequence of Na2S〉S〉Na2SO3〉 Na2SO4. chemical equilibrium analysis is also performed to determine the effect of sorbents on Cd adsorption. The calculations show that S presents strong affinity for Cd and restrains Cd adsorption by SiO2, whereas when temperature rises to between 830℃ and 1030℃, Cd adsorption efficiency of SiO2 is over 80% and the efficiency of Al2O3 is up to 85%.     

升温升压过程对聚丙烯在超临界水中降解的影响

The effect of increasing course of temperature and pressure on polypropylene （PP） degradation in supercritical water was investigated for developing a process of recycling waste plastic. A group of experiments was carded out in a reaction system at a pressure of 26MPa, temperature of 380℃ or 400℃ for 30min, 70min, and 120min by Course One （the increasing course of temperature and pressure is via gaseous regions to supercritical regions）, and the other group was carried out at corresponding holding conditions by Course Two （the increasing course of temperature and pressure is via liquid regions to supercritical regions）. The time of the increasing courses was about 30min. Products were analyzed by Ostward-type viscometer, gaseous chromatography, and mass spectrometers （GC/MS）. Characterization results suggested that different increasing courses of temperature and pressure would give rise to different results, although they were treated under the similar holding conditions. It was also found that Course Two was more effective on PP degradation in supercritical water.     

Experimental study on the effects of drying methods on the stabilities of lignite

The drying processes are always applied prior to the transportation or utilization of lignite, and result in notable changes in the stabilities of lignite. In this paper, the study on the effects of nitrogen and MTE drying process on the physico-chemical properties and stabilities of Zhaotong lignite was carried out. The briquettes produced by MTE drying in this study were 150 mm in dimension, and so had a much larger particle size than nitrogendried samples. Nitrogen adsorption, mercury intrusion porosimetry and scanning electron microscopy all suggested that drying was accompanied by the transformation of larger pores into smaller ones. Compared to nitrogen drying, the pore structures could be stabilized by the MTE process. The soluble salts were removed during MTE drying which resulted in the decrease in ash and the concentrations of some of the major metals.The removal of water enhanced the hydrophilicity of nitrogen dried samples, but did not affect the hydrophilicity of MTE dried samples. The moisture holding capacity of MTE dried samples reduced faster than nitrogen dried samples with the decrease of residual moisture content. Themoisture readsorption processes of MTE dried sampleswere strongly inhibited due to themuch larger particle size of sample produced byMTE drying than nitrogen drying. The susceptibility to spontaneous combustion, indicated by cross point temperature and self-heating tests, of nitrogen and MTE dried samples increased with the decrease of residual moisture content. The MTE dried samples are more liable to spontaneous combustion than nitrogen dried samples with the same residual moisture and particle size. However, the larger particle size of the MTE product made it more stable with respect to spontaneous combustion and also moisture readsorption.     

介观尺度多孔介质燃烧室内火焰分布的电容层析成像(英文)

This study was conducted to investigate the characteristics of meso-scale combustion.The technique of electrical capacitance tomography(ECT) was used to locate flame position and monitor the effect corresponding to varied air/fuel ratio in a meso-scale combustor.Combustion phenomena including igniting,quenching and unsteady combustion have been visualized using ECT.The method of metallization protecting ECT sensor from high temperature damage and the novel calibration method adapted to ECT monitoring of unknown permittivity flame have been shown to be successful.At the same time,electrical nature of combustion and dielectric characteristics of hy-drocarbon flame were studied.The relationship between flame permittivity and state parameters of combustion gas was demonstrated preliminarily.     

乙烯裂解炉中温度的分布

Abstract A good understanding of the detailed temperature distribution in the furnace plays an important role in the implementation of operation optimization and design improvement of ethylene pyrolyzer. Numerical simulation of the turbulent flow, combustion and heat transfer was carried out to investigate the temperature distribution in industrial furnace. Inhomogeneities of the flue-gas temperature distribution were observed in X, Y, and Z direction of the furnace from the simulated results. Along the height of the furnace, the average flue-gas temperature increased initially and decreased afterward, and reached its peak at the height of 5m. The reactor tube skin temperature varied not only along the height of the furnace, but also around the circumference of the tube. The heat flux profiles from the furnace towards the reactor tubes followed the shape of the average flue-gas temperature profile. The heat flux of the inlet tubes was constantly higher than that of the outlet tubes at the same height in the furnace.     

Extraction of potassium from K-feldspar via the CaCl2 calcination route☆

The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-feldspar ore and particle size of the K-feldspar ore. The results demonstrated that a competing high-temperature hydrolysis reaction of calcium chloride with moisture in a damp atmosphere occurred concurrently with the conversion reaction of K-feldspar with CaCl2, thus reducing the amount of potassium extracted. The conversion reaction started at approximately 600 °C and accelerated with increasing temperature. When the temperature rose above 900 °C, the extraction of potassium gradually decreased due to the volatilization of the product, KCl. As much as approximately 41%of the potassium was volatilized in 40 min at 1100 °C. The mass ratio of CaCl2/K-feldspar ore significantly affected the extraction. At a mass ratio of 1.15 and 900 °C, the potassium extraction reached 91%in 40 min, while the extraction was reduced to only 22%at the theoretical mass ratio of 0.2. Optimal process conditions are as follows:ore particle size of 50–75μm, tablet forming pressure of 3 MPa, dry nitrogen atmosphere, mass ratio of CaCl2/ore 1.15:1, calcination temperature of 900 °C, and calcination time of 40 min. The XRD analysis revealed that a complex phase transition of the product SiO2 was also accompanied by the con-version reaction of K-feldspar/CaCl2. The SiO2 product formed at the initial stage was in the quartz phase at 900 °C and was gradually transformed into cristobalite after 30 min.     

染料残渣焚烧过程中微量元素的形态转化及其迁移分配的预测

The release of heavy metals from the combustion of hazardous wastes is an environmental issue of increasing concern. The species transformation characteristics of toxic heavy metals and their distribution are considered to be a complex problem of mechanism. The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication. Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free energy minimization. The results show that Ni, Zn, Mn, and Cr are more enriched in dyestuff residue incineration than other heavy metals （Hg, As, and Se） subjected to volatilization. The thermodynamic model calculation is used for explaining the experiment data at 800℃ and analyzing species transformation of heavy metals. These results of species transformation are used to predict the distribution and emission characteristics of trace elements. Although most trace element predictions are validated by the measurements, cautions are in order due to the complexity of incineration systems.     

固定化金属离子亲和分配用的亚胺二乙酸-聚乙二醇偶联物的制备

The synthesis route was investigated and optimized for the preparation of iminodiacetic acid polyethylene glycol (IDA-PEG) for immobilized metal ion affinity partitioning in aqueous two-phaze systems. IDA PEG was synthesized from PEG in two steps by the reaction of iminodiacetic acid with a monosubetituted derivative of epichlorohydrin-activated PEG. The Cu2+ content combined with IDA-PEG was determined by atomic absorp tion spectrometry as 0.5 mol.mol-1 (PEG). Furthermore, the affinity partitioning behavior of lactate dehydrogenase in polyethylene glycol/hydroxypropyl starch aqueous two-phaze systems was studied to clarify the affinity effect of the Cu(Ⅱ)-IDA-PEG.     

H2 solubility and mass transfer in anthraquinone working solution:Experimental and modeling study

This work was focused on the measurement of the solubility of hydrogen(H_2) in anthraquinone working solution at temperatures of 30.0–80.0 °C and pressures of 0.2–3.0 MPa by the method of experimental and COSMO-RS model study. The influence of various factors, i.e., including pressure, temperature and solvent volume ratio, on H_2 solubility was investigated. According to the experimental results, H_2 solubility in anthraquinone working solution increases with the increase of pressure. At low pressures, the temperature had little effect on H_2 solubility while under high pressures H_2 solubility increases with increasing temperature. Henry's constant lnH has a good linear relationship with 1/T(lnH =- 1319.1/T + 9.91). The effect of volume ratio of trioctyl phosphate to trimethylbenzene on the solubility of hydrogen was studied and the results showed that increasing the amount of trimethylbenzene was conducive to the dissolution of hydrogen. In addition, there is a linear relationship between ln((P0- Pe) /(Pt- Pe)) and the time t. Gas–liquid mass transfer coefficient was obtained by calculating the slope of the line.     

氯代烷烃对气相缩合法合成苯基三氯硅烷的影响(英文)

To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis was studied based on the product distribution from a tubular reactor. The promoting effect of chloralkane addition was mainly caused by the chloralkane radicals generated by the dissociation of C–Cl bond. The promoting effect of the chloromethane with more chlorine atoms was better than those with less chlorine atoms. Intermediates detected from the reactions with isoprene and bromobenzene demonstrated that both trichlorosilyl radical and dichlorosilylene existed in the reaction system in the presence of chloralkanes. A detailed reaction scheme was proposed.     

On the fate of heavy metals in municipal solid waste combustion Part I: devolatilisation of heavy metals on the grate

The aim of this study has been to investigate the chemistry and volatility of the heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn on the grate of a MSW fired furnace, using equilibrium calculations. Focus has been on the influence of varying MSW composition and operational parameters such as air/fuel ratio and temperature. Equilibrium distributions at 950–1600 K, under reducing and oxidising conditions on the grate, showed that Cd, Hg and Pb are fully volatilised. However, Cr is found to be stable in solid phase, in the entire temperature range. The volatile behaviour of Cd, Cr, Hg and Pb show no significant influence, while As, Cu, Ni and Zn are strongly influenced by one or more of the parameters; temperature, fuel/air and chlorine/metal ratios.     

添加剂对污泥焚烧过程中重金属迁移特性的影响

利用管式炉研究了Cl、S、P对重金属迁移特性的影响,研究结果表明：C促进了重金属Cd、Pb、Zn、Cu的挥发,而对重金属Ni、Cr的挥发特性影响不大;S对重金属的挥发特性影响不大,在一定程度上抑制霞金属Zn、Cd、Ni的挥发,而对重金属Pb则促进其挥发;P对不同重金属的挥发特性影响不同,随着P含量的增加,重金属Cr和Ni的挥发的挥发率逐渐增大,而重金属Cd、Pb和Zn的挥发率逐渐降低。     

固体吸附剂对油页岩半焦燃烧过程中重金属元素的影响

通过对桦甸油页岩半焦进行燃烧实验,研究了不同终温下部分重金属元素的挥发特性及吸附剂的吸附效果,研究表明：随着温度的增加,各元素的挥发率均呈现出增大的趋势,且当温度为650℃时,元素Cd、Te、Co、Sn、Pb、Sb的挥发率呈现出明显的增大趋势;相对而言,各温度段下元素Cd、Te的挥发率较大,元素Mn、Y、W的挥发率较低。添加吸附剂CaO和高岭土后,大部分元素在页岩灰中的含量均明显增加,表明吸附剂对大部分重金属元素具有良好的吸附效果;通过吸附率可以看出,吸附剂CaO除元素W、Te未发现吸附效果外,对其他所研究的重金属元素均有较强的吸附效果,尤其是元素Co、Mn、Cu、Y、Sn、Cd;而高岭土除对元素Pb、Te未发现吸附效果外,对其他元素均具有一定的吸附效果,尤其是元素Co、Mn。相比而言,CaO对重金属元素的吸附效果要比高岭土强。     

活性炭对重金属离子的吸附研究

研究了活性炭分别对铅、镉、铜及锌离子的吸附作用,研究了pH值、温度及活性炭的投加量等因素对吸附效果的影响。结果表明,当pH〉5时对四种离子的去除率均达到98％以上,能达到很好的吸附。低温有利于吸附的进行。随着活性炭的增加．重金属离子的去除率增加．而且铜离子的活性炭最佳用量是0．3000g．铅、镉和锌的活性炭最佳用量均为1．000g。随着吸附时间的增加,去除率上升。铜、铅、镉和锌离子的吸附平衡时间分别为3．5h、1h、1．5h和1．5h。铜离子的吸附符合Langmuir等温模式,而锌、铅和镉离子的吸附符合Freundlich等温模式。     

电炉镍铁渣重金属浸出研究

通过分析电炉镍铁渣的矿物成分和物相组成,考察不同粒度电炉镍铁渣的重金属含量,采用BCR(Bureau Community of Reference)连续提取方法和调节浸提剂pH值进行电炉镍铁渣的浸出测试。结果表明:粉末状电炉镍铁渣的重金属含量最高,完整电炉镍铁渣的重金属含量小于破损的重金属含量;电炉镍铁渣属于一般工业废物,不属于危险废弃物;水溶态中重金属Cd更容易浸出,重金属Cu、Ni在弱酸环境下更容易浸出,在可还原状态下重金属Cr、Pb和Mn更容易浸出,在可氧化态下Zn和Cu更容易浸出;除Cu和Pb外,pH值的降低会导致电炉镍铁渣中的重金属浸出量增大,呈L型浸出曲线,Cu在碱性环境下会加速浸出,而Pb只有在强碱环境下才会大量浸出,因此在强碱环境下要注意Pb的浸出检测。     

Trace elements (Mn,Cr, Pb,Se, Zn,Cd and Hg) in emissions from a pulverized coal boiler

The concentrations of seven trace elements (Mn, Cr, Pb, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured quantitatively in a 220 tons/h pulverized coal boiler. Factors affecting distribution of trace elements were investigated, including fly ash diameter, furnace temperature, oxygen concentration and trace elements' characteristics. Modified enrichment factors show more directly element enrichment in combustion products. The studied elements may be classified into three groups according to their emission features: Group 1: Hg, which is very volatile. Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be located between groups 1 and 2. Cr has properties of both Groups 1 and 3. The smaller the diameter of fly ash, the higher is the relative enrichment of trace elements (except Mn). Fly ash shows different adsorption mechanisms of trace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of trace elements (except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen concentration will not always improve the volatilization of trace elements. Pb forms chloride more easily than Cd during coal combustion.     

利用响应面法优化皂角苷浸提飞灰中重金属的处理条件

通过响应面法对皂角苷浸提飞灰中Cu、Zn、Pb和Cd 4种重金属的实验条件进行优化,选取pH、皂角苷浓度、离子强度、温度、时间和固液比6个因素进行中心组合设计,使用design-expert8.0软件进行数据拟合,建立了Cu、Zn、Pb和Cd去除总量的工艺数学模型,通过方差分析得到6个因素对浸提液中4种重金属去除总量的主效应关系为： pH>固液比>离子强度>皂角苷浓度>温度>时间。对重金属去除总量数据进行design-expert8.0软件优化,得到皂角苷浓度为41.2g·L^-1、时间为13.54 h、离子强度为0.64 mol·L^-1、pH为2、固液比为1%和温度为23.4℃时,重金属总去除量达最大值,Cu、Zn、Pb和Cd的去除率分别达到55.12%、6.20%、17.80%和78.11%。     

矿物添加剂对煤燃烧过程中重金属的富集

在管式炉中进行了煤与矿物添加剂的燃烧实验，研究了900～1300℃的高温条件下，质量添加比分别为0、1%、3%和5%，高岭土、蒙脱石、凹凸棒土和石灰石对重金属元素Pb、Cd、Zn和Cr的富集效果。结果表明：随着添加剂比例的增加，各重金属的固留率均呈上升趋势，且添加比以5%为宜。添加剂对Pb和Cd的富集温度为900～1000℃较为适宜，该温度范围内二者的固留率保持在60%左右，对Zn富集的适宜温度为900℃，该温度下Zn的固留率接近70%，Cr为1000～1100℃，固留率可达到82.1%。当温度达到1100℃时，煤灰的结焦会导致四种重金属的固留率均有所下降，当温度升高到1200℃时固留率将大幅度下降，1300℃时各添加剂几乎完全失活，其中Pb的固留率只有大约25%，Cd和Zn的固留率降低到30%左右，Cr的固留率下降至56%以下。对比4种添加剂对Pb、Cd、Zn和Cr的富集效果而言，高岭土和凹凸棒土的性能较优，蒙脱石次之，石灰石较差。本研究能够为燃煤电厂重金属的污染控制提供理论和实验依据。     

Packed-bed columns with dye-affinity microbeads for removal of heavy metal ions from aquatic systems

A dye ligand Cibacron Blue F3GA, was covalently coupled with polyhydroxyethylmethacrylate (PHEMA) microbeads in the 150–200 μm particle size range. The sorbent carrying 22.3 μmol Cibacron Blue F3GA per gram of polymer was then used to remove Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions in a packed-bed column system. Heavy metal ion adsorption capacity of the column was investigated as a function of heavy metal ion-bearing solution flow rate and the inlet heavy metal ion concentration. The maximum metal ion uptake values found were: 80.60, 96.98, 78.36, 103.98 μmol/g polymer for Pb(II), Cd(II), Cu(II) and Zn(II), respectively. The heavy metal adsorption capacity of the microbeads decreased with an increase in the circulation rate of aqueous solution. The order of affinity based on molar uptake was Zn(II)>Cd(II)>Pb(II)>Cu(II). Removal percentages of heavy metals related to flow time were determined for different flow rates and initial metal ion concentrations. It was observed that PHEMA microbeads carrying Cibacron Blue F3GA can be regenerated by washing with a solution of nitric acid (0.05 M). The desorption ratio was as high as 98.5%.     

Behavior of heavy metals in air pollution control devices of 2,400 kg/h municipal solid waste incinerator

We analyzed the behavior of heavy metals, such as Cd, Cr, Cu, Ni, Pb, Zn, and Hg, in air pollution control devices of a municipal solid waste incinerator. For this study, a municipal solid waste incinerator with a burning capacity of 2,400 kg/h was selected. A semi-dry reactor (SDR), fabric filter, and wet scrubber were installed to serve as air pollution control devices. Flue gas was sampled upstream and downstream of each air pollution control device to determine the heavy metal concentrations therein. Ash was collected from the furnace, boiler, SDR, and fabric filter to determine the heavy metal concentration in the ash produced by each device. Each heavy metal was found to have a different fate in the incinerator and air pollution control devices. Cd and Pb were mostly present in the fabric filter ash, whereas Cr, Cu, and Ni were most prevalent in the bottom ash of the furnace and boiler, and Zn was present in the bottom and fabric filter ash at a ratio of 7: 3. However, only a few percent of Hg was identified in the ash from the furnace, boiler, SDR, and fabric filter; the majority of Hg passed through the fabric filter and existed in an oxidized form. The wet scrubber exhibited high control efficiency for oxidized mercury, and the injection of commercial activated carbon at a rate of 0.2 g/Sm³ resulted in 93.2% mercury removal efficiency.