加热炉富氧燃烧特性的实验及数值模拟

通过实验及数值模拟手段对120 kW级别加热炉实验装置进行了富氧助燃特性及NO_X排放特性的研究。实验装置设置单火嘴、单助燃气主管以及双助燃气副管的设计结构。分别考察了常规空气助燃、局部射流空气助燃以及局部射流富氧助燃等方式下,不同局部射流流量对燃烧烟气温度、烟气NO_X排放量的影响。参照实验设置建立数值模拟模型,考察了局部射流助燃方式下炉膛内流场、温度场的分布情况。研究结果表明,局部射流富氧助燃方式在所考察条件下可提高燃烧温度10%,降低NO_X排放90%,在保持原加热炉设计温度不变的条件下,本燃烧方式具备节能减排效果。     

新型高效台车式退火炉研制

退火炉采取小燃烧室,对工件实行侧下加热、强化绝热措施复合炉衬、二次均热风管、扩张室沉降等五项措施.目的是为了提高炉的热效率和炉温的均匀度.在耗煤量较低的情况下能保持较高的燃烧室强度.有利于强化燃烧和减少蓄散热损失.实行扩张室沉降,在不加任何除尘装置的条件下烟尘排放浓度达到了国家标准新规定的排放要求,而且大大改善了工人的劳动条件.     

汽车油罐车爆炸燃烧特性的数值模拟分析

汽车油罐车爆炸燃烧是一种发生在受限空间内的燃烧情形,研究汽车油罐车爆炸燃烧过程中湍流速度场和温度场的分布和发展对爆炸冲击波形成与传播的作用规律,对于加强汽车油罐车安全设计和防灾减灾具有积极作用。为探究汽车油罐车在爆炸燃烧时油罐内部的火焰变化情况,建立了汽车油罐车爆炸燃烧模型,通过数值模拟分析得到油罐爆炸燃烧时的温度场和燃气速度场分布情况,以此研究油罐内部爆炸燃烧的发展过程。模拟结果与已有文献试验数据存在较好的吻合性,对汽车油罐车油气爆炸燃烧特性规律的进一步研究及汽车用油罐防爆抑爆设计优化具有参考意义。     

污泥水煤浆在3.2MW卧式锅炉中的燃烧特性研究

在3.2MW卧式炉中对污泥水煤浆和大同烟煤水煤浆进行对比燃烧试验,研究了煤浆的着火、温度场及燃烧效率等特性,并考察了污泥水煤浆工业应用的可行性.结果表明,掺混10%污泥的水煤浆着火容易,炉膛主燃烧区域火焰温度可达到1200～1300℃;污泥水煤浆燃烧时炉膛火焰分布均匀,火焰充满度较好;水分析出使颗粒表面分布大量气孔,有...     

缩口模型腔表面上压力的数值分析

本文在成形过程模拟的基础上,对缩口凹模型腔表面上的压力进行了研究。分别就锥型凹模和曲母线凹模作了分析计算,得到了相应的压力分布规律,为设计模具、选择模具材料以及研究模具的寿命等提供了理论上的依据。     

硅酸铝棉对管道爆燃压力波抑制性能评价

为了研究硅酸铝棉对管道内丙烷-空气预混爆燃压力波的影响,本文通过开展丙烷-空气预混火焰在无内衬、内衬硅酸铝棉、内衬实体障碍物和非变截面硅酸铝棉壁面4种管道内的传播试验,并采用压力-冲量准则评价了火焰压力冲击波的危害程度,考察了硅酸铝棉对减轻爆燃压力冲击波危害的作用。结果表明:硅酸铝棉能够减小管道出口压力波的比冲量和DN准数,说明硅酸铝棉对压力波的传播有抑制作用,可降低管道出口处压力波的冲击破坏作用和危害性。     

巷道拐弯对瓦斯爆炸影响的数值模拟研究

基于一些基本假设,运用流体动力学软件FLUENT对均匀充满9.5%瓦斯气体浓度的不同拐角二维方形巷道进行了数值模拟研究,并对不同拐弯巷道内瓦斯爆炸过程中的火焰传播速度、压力和温度进行了对比分析。结果表明:拐弯巷道内冲击波的速度、压力和温度等参数在传播过程中会逐渐增加;在巷道拐弯处会产生复杂的流场,并在局部区域内对冲击波有激励作用。该研究结果揭示了瓦斯在拐弯巷道内爆炸传播的本质,从而可为制定防爆抑爆措施提供理论依据。     

二甲醚燃烧的甲醛生成特性实验研究

针对二甲醚平面预混火焰,实验研究了燃料当量比和燃料流量对燃烧过程中甲醛产生和排放特性的影响。实验结果表明,甲醛是二甲醚燃烧过程一个重要的中间产物,在火焰面中大量生成,但其中大部分甲醛迅速被氧化消耗;二甲醚燃烧过程中甲醛的生成受燃料当量比和火焰温度影响明显,欠氧（燃料当量比Ф〈1）预混合燃烧的甲醛生成显著高于富氧（Ф〉1）燃烧;燃料当量比一定时,随着燃料流量增加,火焰中的甲醛浓度升高。     

10kV电缆受潮缺陷模拟及其放电特征研究

针对10 kV XLPE电缆开展绝缘受潮缺陷模拟试验,根据电缆绝缘水树的等效电路,制作了两种电缆模型试样。在串联谐振耐压条件下对两种试样进行局部放电测量,通过脉冲电流法检测其局部放电信号并研究放电特征。试验结果表明:埋入盐水浸泡棉线试样的电缆绝缘水树缺陷模型,在试验条件下的局部放电图谱特征呈现双极性分布,属于沿面放电类型。     

污染源位置对气体污染物影响的数值模拟

在自然通风、置换通风和单侧送侧回式通风3种方式下,通过改变污染源位置,运用CFD软件模拟研究了办公室内苯污染物的浓度分布规律,比较得出最佳通风方式下的最合理污染源位置。结果表明,3种通风方式下污染源放置的最合理位置是点3;苯污染源处于位置3时,3种通风方式中自然通风各平面苯污染物平均浓度普遍相对最高,而单侧送侧回方式的相对最低,置换通风居于二者之间。最终确定单侧送侧回通风方式下污染源处于位置3时为最佳物理模型,在该模型下办公室内通风效果最好,能够有效地排出室内气体污染物。因此,不同污染源位置对办公室内空气品质的影响不同。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

ＲｅｍｏｖａｌｏｆｈｅａｖｙｍｅｔａｌｓｆｒｏｍｓｅｗａｇｅｓｌｕｄｇｅｂｙｌｏｗｃｏｓｔｉｎｇｃｈｅｍｉｃａｌｍｅｔｈｏｄａｎｄｒｅｃｙｃｌｉｎｇｉｎａｇｒｉｃｕｌｔｕｒｅＷｕＱｉｔａｎｇ，ＮｙｉｒａｎｄｅｇｅＰａｓｃａｓｉｅ，ＭｏＣｅｈｕｉＦ...     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Sorption of 1-naphthol by plant cuticular fractions

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.     

Seed selections for crystallization of calcium phosphate for phosphorus recovery

Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.