用超声技术测水煤浆中煤浓度的试探

开展水煤浆应用的研究,对于解决我国煤炭运输以及煤代替燃料油以至解决环境污染等问题都有极其重要的意义。在水煤浆的制备、管道输送等过程中,在线监测其中的煤浓度是必不可少的。例如,在考察水煤浆制备的重复性,燃烧的热效率,雾化质量,以及输送管道中水煤浆的流变特性等方面提供的原始数据,对保障整个应用水煤浆的工艺系统高效、安全、可靠的运行是非常有用的。     

水煤浆超声流速仪的研制

测量水煤浆流速,对于计量水煤浆流量,研究水煤浆在输送管道里的流变特性和雾化质量以及燃烧特性等都具有重要意义。应用超声多普勒效应测量流体流速虽已发表过文章,但将这种方法用于工业测试方面的研究则尚未很好进行。我们用超声多普勒效应测定水煤浆流速,取得了较好的效果。     

氧碳原子比和水煤浆质量分数对水煤浆气化影响的数值模拟

用数值方法模拟了水煤浆气化过程中氧碳原子比和水煤浆质量分数对气化过程和出口煤气成分以及碳转化率的影响规律。总结了在具有复杂化学反应的高温、高压容器中，对水煤浆气化过程的数值模拟时经常遇到的问题和解决方法。得到了气化炉内的温度场、流场、浓度场以及出口粗煤气成分，其结果与工程实际相比非常接近；并利用得到的结果分析了影响水煤浆气化过程和出口煤气成分的主要因素：氧碳原子比、水煤浆质量分数等，提出了提高出口煤气有效成分（CO+H2）的方法。     

煤及水煤浆沸腾燃烧过程中 NO_x 的生成及脱硫的研究

试验是在两个沸腾燃烧试验台架上进行的,测定了沸腾燃烧煤和水煤浆时NO沿床高的变化规律。沸腾燃烧属低温燃烧,试验证明其NO_x 排放量比火炬燃烧时低一半,而烧水煤浆时比烧煤还低20%。结果还表明,在沸腾炉中加入石灰石脱硫的最佳炉温为850°—900℃,Ca/S 比在2—3之间。由于沸腾燃烧水煤浆时出现结团现象,故不但燃烧效率较高,而且加石灰石脱硫效率也比烧煤时高20%,因此水煤浆是一种有前途的清洁代用流体燃料。     

黑液水煤浆主要矿物元素在炉内的迁移和沉积行为研究

为了研究黑液水煤浆的灰沉积机理，采用沿烟气行程从实验炉不同部位抽取空间灰粒和提取相应位置炉壁灰渣样相结合的方法，并与常规水煤浆相对比，研究了各主要矿物元素（Na、K、Si、Al、Fe、Ca）在烟气流中的迁移趋势和沉积特性。并且通过X射线衍射（XRD）和扫描电镜（SEM）等分析从微观角度进行了验证。结果表明，与常规水煤浆不同的是，Na、Si、Al的迁移和沉积是引起黑液水煤浆沾污结渣的主要矿物元素，灰沉积物中主要包括无水芒硝、霞石等低熔融温度富Na物相，而Fe的沉积是次要因素。     

聚对苯乙烯磺酸钠添加剂的分子量对水煤浆浆体性质的影响

选用了变质程度不同的八种煤和三种不同分子量的聚对苯乙烯磺酸钠（PSS）添加剂，详细考查了该添加剂的分子量对水煤浆浆体性质的影响。结果发现，在考查PSS相对分子量的范围内（质均分子量为5.34×104～33.39×104），八种煤的水煤浆成浆性随着分子量的增大而增加，水煤浆成浆性与PSS添加剂的平均分子量的关系可归因于添加剂在煤粒上的吸附，分子量小的PSS在煤粒上的吸附量大于分子量大的PSS；PSS分子量的增加有利于水煤浆的流变性由胀性向假塑性转变；PSS分子量的增加使水煤浆的静态稳定性得到显著的改善。     

煤孔结构特性对水煤浆性质的影响分析

通过三种不同的方法(CO2吸附法、N2吸附法和压汞法)测试了不同变质程度煤的孔结构性质，分析了煤的孔结构特性与水煤浆性质之间的关系。结果表明，煤的孔结构特性对水煤浆性质的影响较为复杂，主要是煤的大孔结构对煤浆成浆性的影响。在相近的孔体积和孔径分布下，煤的成浆性差别较大。孔结构特性本身作为一个独立的因素不能完全体现出对水煤浆性质的影响程度，与煤的表面性质如含氧官能团性质、煤表面的疏水性以及煤的吸水性等密切相关，共同影响着水煤浆的性质。     

超声波强化水煤浆制备方法的研究

本文研究用超声波技术强化高浓度水煤浆的制备方法，选择适当的处理条件和设备，经超声波处理的水煤浆，煤粉级配明显向细的方向转化，不仅表观粘度大幅度降低，而且浆体静态稳定性和流变特性也得以显著改善。     

Combustion of sludge coal water slurry and emission property of contaminants

在3.2MW卧式炉中对污泥水煤浆和大同烟煤水煤浆进行了对比燃烧实验,分别研究了煤浆的着火、燃烧、结渣及污染物排放特性.结果表明,掺混10％污泥的水煤浆着火容易,燃烧稳定,炉膛火焰分布均匀,燃烧和结渣特性均优于大同烟煤水煤浆.污泥的添加使水煤浆燃烧烟气中SO2和NOx的浓度偏高,实际应用中可通过加入固硫剂等方式缓解.污泥水煤浆在卧式炉中的燃烧状况较理想,为城市污泥资源化利用提供了一条可行的新途径.     

污泥水煤浆燃烧和污染排放特性研究

在3.2 MW 卧式炉中对污泥水煤浆和大同烟煤水煤浆进行了对比燃烧实验,分别研究了煤浆的着火、燃烧、结渣及污染物排放特性。结果表明,掺混 10%污泥的水煤浆着火容易,燃烧稳定,炉膛火焰分布均匀,燃烧和结渣特性均优于大同烟煤水煤浆。污泥的添加使水煤浆燃烧烟气中SO₂和NO_x的浓度偏高,实际应用中可通过加入固硫剂等方式缓解。污泥水煤浆在卧式炉中的燃烧状况较理想,为城市污泥资源化利用提供了一条可行的新途径。     

煤浆浓度和颗粒分布对煤浆黏度预测的影响

采用神华煤制备煤浆,分析了颗粒粒径比λ和小颗粒体积分数ξ对双峰分布浆体黏度的影响,根据浆体黏度的关联式预测了煤浆的黏度并且与实验结果进行了比较。结果表明,采用双峰分布的颗粒制浆可以有效地降低浆体的黏度,同时可以获得较大的浆体体积分数 。在相同体积分数下,随着颗粒粒径比λ的增加,浆体的黏度迅速下降。当小颗粒体积分数ξ_dp1为35%时,浆体的黏度最小。采用Ouchiyama模型计算浆体的最大体积分数Φ_m与实验值较为吻合,而浆体的本质黏度[μ]基本保持不变。考虑λ和小颗粒体积分数ξ对双峰分布浆体的最大体积分数Φ_m的影响,可以采用单峰分布浆体的黏度关联式预测双峰分布浆体的黏度。     

煤沥青水浆的制备及影响规律的研究

以中温煤沥青为原料,经冷冻粉碎后制得具有一定粒径级配的煤沥青粉,加入适量分散剂和水在高速搅拌下制备煤沥青水浆.结果表明,JL-C01中裂乳化剂是制备煤沥青水浆的优良分散剂,在此基础上进一步考察了分散剂用量及浆体浓度对煤沥青成浆性、煤沥青水浆流变性及稳定性的影响.结果表明,最大成浆浓度为70％;在分散剂用量相同的条件下,...     

An experimental study on the rheological properties of aqueous ceria dispersions

The rheological properties of aqueous ceria dispersions are studied experimentally. In particular, the effects of particle concentration, temperature, pH, and ionic strength are discussed. If the volume fraction is below 2%, ceria slurry exhibits Newtonian behavior, and for higher volume fractions, shear-thinning behavior is observed. The effect of temperature on the behavior of ceria slurry is found to be pH-dependent. If pHIEP, the viscosity slightly increases with increased temperature. A shift of IEP to a higher value of pH was observed for ionic strength, even for indifferent electrolytes. The influence of pH on the rheological properties of ceria slurry decreases if the ionic strength is high. The pH at which viscosity and yield stress are maximum coincide with IEP only for low ionic strengths. The slopes of acidic and basic branches of viscosity against pH and yield stress against pH curves are not symmetrical at high ionic strength, and the alkaline branch deviates significantly from Hunter's theory.     

壬基酚聚氧乙烯醚聚合度对水煤浆浆体性质的影响

研究了壬基酚聚氧乙烯醚型添加剂的聚合度对变质程度不同的8种煤所制得的水煤浆浆体性质的影响规律。结果表明,壬基酚聚氧乙烯醚添加剂的聚合度对于8种煤所制得的水煤浆的成浆性、流变性以及静态稳定性均有一定的影响,存在一最佳范围。研究还发现,用壬基酚聚氧乙烯醚型添加剂制备水煤浆时,该添加剂的作用与煤的分析基水分质量分数、丝质组分质量分数以及孔体积之间存在着相关性。     

Cw-laser thermal lens spectrometry in binary mixtures of water and organic solvents: composition dependence of the steady-state and time-resolved signals

The thermal lens effect obtained in binary liquid systems composed of water and ethanol, propanol and acetonitrile has been investigated. The dependence of dn/dT upon the solvent volume fraction follows polynomials up to sixth order and cannot be precisely predicted using the additive rule. The sensitivity of the thermal lens method upon the addition of organic solvent in water varies as the temperature-dependent refractive index gradient to thermal conductivity ratio of the mixture provided that the signal is sampled correctly. Otherwise, especially when steady-state experiments are carried out, the thermally induced concentration gradient, known as the Soret effect, can change the thermo-optical properties of the solution locally in the irradiated area and produce an additional signal. This effect depends on the solvent and is maximum at low solvent composition. At the critical solvent volume fraction of 0.1-0.15, the Soret component may represent up to 25% of the pure thermal lens signal and has a time constant which is 200-400 times greater than the characteristic time constant of the thermal lens.     

Synthesis and micellar properties of 1-decyl-2,3-dimethylimidazolium bromide surfactant in water and water-ethanolamine mixtures at 298.15 K

1-Decyl-2,3-dimethylimidazolium bromide (ddmimBr) has been synthesized by the reaction of 1,2-dimethylimidazole and 1-bromodecane. Micellization of ddmimBr surfactant in water (W) and water-ethanolamine (W-EA) with the weight percent of EA changing within the range 0-39.79%, has been investigated at 298.15 K. Information about the influence of the added EA on the critical micelle concentration (CMC) was obtained through density and surface tension measurements. This last provides information about the dependence of the surface excess concentration, the minimum area per surfactant molecule and the surface pressure at the CMC on the added weight percentage of organic solvent. The effect of binary aqueous mixtures of W-EA on the apparent molar volume (phi V) of the ddmimBr has been investigated. The apparent molar volume upon aggregation (Delta phi V) shows a maximum at about 15 wt% of EA, this behavior is discussed in terms of the changes of the solvent structure. Partial specific volume data, obtained by density measurements, indicate that the fraction of solvent molecules interact with the surfactant remained roughly constant.     

Combination of RSM and NSGA-II algorithm for optimization and prediction of thermal conductivity and viscosity of bioglycol/water mixture containing SiO2 nanoparticles

The fluids containing nanoparticles have enhanced thermo-physical characteristics in comparison with conventional fluids without nanoparticles. Thermal conductivity and viscosity are thermo-physical properties that strongly determine heat transfer and momentum. In this study, the response surface method was firstly used to derive an equation for the thermal conductivity and another one for the viscosity of bioglycol/water mixture (20:80) containing silicon dioxide nanoparticles as a function of temperature as well as the volume fraction of silicon dioxide. Then, NSGA-II algorithm was used for the optimization and maximizing thermal conductivity and minimizing the nanofluid viscosity. Different fronts were implemented and 20th iteration number was selected as Pareto front. The highest thermal conductivity (0.576 W/m.K) and the lowest viscosity (0.61 mPa.s) were obtained at temperature on volume concentration of (80 °C and 2%) and (80 °C without nanoparticle) respectively. It was concluded that the optimum thermal conductivity and viscosity of nanofluid could be obtained at maximum temperature (80 °C) or a temperature close to this temperature. An increase in the volume fraction of silicon dioxide led to the enhancement of thermal conductivity but the solution viscosity was also increased. Therefore, the optimum point should be selected based on the system requirement.     

Green synthesis,crystal growth,and some physicochemical studies on an inter-molecular compound of anthranilic acid and <Emphasis Type="Italic">m</Emphasis>-nitro-benzoic acid system

Nanofluids are prepared by suspending the nanoparticles in the base fluid and can be substantially enhanced the heat transfer rate compared to the pure fluids. In this paper, experimental investigation of the effects of volume concentration and temperature on dynamic viscosity of the hybrid nanofluid of multi-walled carbon nanotubes and aluminum oxide in a mixture of water (80%) and ethylene-glycol (20%) has been presented. The nanofluid was prepared with solid volume fractions between 0.0625 and 1%, and experiments were performed in the temperature range of 25–50 °C. The measurement results at different shear rates showed that the base fluid and nanofluid samples with solid volume fractions of less than 0.5% had Newtonian behavior, while those with higher solid volume fractions (0.75 and 1%) exhibit a pseudoplastic rheological behavior with a power law index of less than unity. The results showed that viscosity has a direct relationship with solid volume fraction of the nanofluid. The value of maximum enhancement is which occurred in 25 °C. Moreover, the consistency index and power law index have been obtained by accurate curve fitting for samples with non-Newtonian behavior of nanofluids. The results also revealed that the apparent viscosity generally increases with an increase in the solid volume fraction.     

Electroosmotic transport of water and aprotic solvent in heterogeneous membranes

Electrosmotic water transport in MK-40, MA-40, and MA-41 electrodialysis membranes before and after their treatment by aprotic solvent solution and electroosmotic permeability of a MK-40/MA-40 membrane couple in water and N,N-dimethyl acetamide were studied for the first time. It is found that N,N-dimethyl acetamide produces practically no effect on the properties of the studied ion-exchange materials and its transport number through the MK-40/MA-40 membrane couple is independent both of the initial lithium chloride concentration in a desalting cell of the concentrator electrodyalizer and its volume fraction in the solution. The initial concentration of lithium chloride in the desalting cell does not affect the transport numbers of water in the studied membrane couple either. However, these depend on the volume fraction of the organic component in the solution and this dependence features an extremum. A method for estimation of electroosmotic permeability of the membrane couple in aqueous-organic solutions of electrolytes is suggested.