大型管式加热炉燃烧传热CFD数值模拟

为了研究大型管式加热炉内部流动、传热和传质情况,采用计算流体力学的方法对石化行业中广泛应用的大型加热炉炉膛内部进行了数值模拟,用标准的k-ε湍流模型描述烟气湍流情况,非绝热的简化PDF燃烧模型计算了燃烧情况,离散坐标辐射传热模型对炉膛内辐射传热状况进行模拟。计算结果和工业运行数据吻合较好,模拟计算结果为大型加热炉优化设计提供了理论指导。     

气溶胶和氡浓度变化对氡子体影响的探讨

为了得到气溶胶变化后对氡子体产生的影响,实验通过气溶胶粒径谱仪SMPS测试氡室内不同浓度气溶胶,分析气溶胶的变化情况,根据AlphaGUARD测氡仪以及AlphaPM子体仪测试变化的氡浓度不同气溶胶下子体变化情况。实验结果表明：在两个NaCl浓度的气溶胶条件下,气溶胶的总量随着气溶胶发生器中的NaCl浓度的增大而变大,由于氡子体结合态随气溶胶浓度改变,氡子体浓度也随气溶胶浓度的增大而增大。并且在相同气溶胶浓度情况下,氡子体的浓度随着氡浓度的增大而增大。     

基于机器视觉系统测量有色溶液浓度的方法研究

在化学分析实验中,有色溶液浓度一般采用分光光度法测定。提出一种基于机器视觉系统测定有色溶液浓度的新方法,设计了基于机器视觉系统测定有色溶液浓度的实验装置,结果表明该方法可替代传统的分光光度法,且具有实验装置简单、造价低和功能扩展性强的特点。     

Mathematical modeling of reverse osmosis systems

The present investigation pertains to modeling of seawater desalination system. A simulation model was developed and verified for a small-scale reverse osmosis system. The proposed model combines material balances on the feed tank, membrane module andproduct tank with membrane mass transfer models. Finally a comprehensive simulation model has been developed incorporating the effect of mass transfer inhibition The model is non-linear differential equation representing the feed concentration as a function of operating time and space. The solution of the simultaneous differential equations was obtained using the fourth order Runge-Kutta method, due to self starting and stability. The model was verified using the experimental data from the literature [17,24]. Parameter sensitivity was carried out to select the proper step size. The simulation was run for over 1000 11 enabling a prediction of operational performance at high overall system recoveries.     

Fractionation and concentration of kraft black liquor lignin with ultrafiltration

Kraft black liquor lignin is a biofuel that is separated from the cellulose during kraft pulping. Improved technology and energy integration in paper mills have led to an energy surplus at many mills. It is therefore of great interest to extract the lignin from the pulp mill and sell it as fuel to replace fossil fuel in other furnaces. The fractionation of kraft black liquor with a total dry matter content of about 15 wt% has been studied using ultrafiltration. The flux for three polymeric membranes with different cut-offs was investigated as well as their retention of lignin and other process specific substances. The retention of lignin for the three membranes with cut-offs of 4,8 and 20 kDa was 80%, 67% and 45%, respectively. The retention of sulphur and sodium was zero for all three membranes. The purity of the final lignin fuel is of importances as the ash content preferably should be as low as possible. The flux and retention during concentration and diafiltration of the black liquor were therefore studied. The dialfiltration operation was conducted in batch and semicontinuous mode. The lignin purity was 36% in the original kraft black liquor and 78% after semi-continuous dialfiltration.     

The effects of impeller characteristics in the hydrogenation of aniline on Ru/C catalyst

Effects of impeller characteristics have been studied in the hydrogenation of aniline on Ru/C catalyst. Dual impellers were employed and the experiments were performed at 300 rpm using a lab-scale reactor. Reaction with disk turbines (DT) resulted in the higher cyclohexylamine (CHA) selectivity and higher reaction rate compared to that with pitched blade turbines (PBT). When a combination of PBT and DT impellers was employed, high product selectivity and reaction rate were obtained and the selectivity was maintained constant. Changes in the product selectivity with the impeller geometry were explained in terms of the relative rates of the side reactions depending on the hydrogen concentration in the reaction mixture.     

Partikelcharakterisierung in hochkonzentrierten Dispersionen – Grundlegende Untersuchungen zu einer neuen Ultraschallmethode

A new method for inline characterization of particles in high concentrated dispersions by ultrasonic backscattering is described, that is sensitive against particle size and concentration. Analyzing the backscattering signal yields the sound attenuation as well as a scattering intensity equivalent. The measurement can be performed without sampling and minimally invasive directly in the process.     

ANISOTROPIC MEMBRANE TRANSPORT†

Membranes consisting of two layers, one of which has a concentration-dependent permeability, may show anisotropic fluxes. In other words, the flux under a given concentration difference has a different magnitude if the direction of the concentration difference is reversed but its magnitude is unchanged. This paper develops a simple theory of this effect and verifies aspects of this theory experimentally.     

Regeneration performance of concentrated CO2-rich alkanolamine solvents: The first step study of a novel concept for reducing regeneration heat consumption by using concentration swing absorption technology

A concept called “concentration swing absorption (CSA)” was present to save CO₂ regeneration heat requirement. In this process the initial lean-CO₂ solvent is executed to form the so-called initial CO₂-rich solvent (ICRS) by absorbing CO₂, then ICRS is split into the concentrated CO₂-rich solvent (CCRS) phase and the diluted phase (mainly water). And only CCRS is regenerated in the stripper. Regeneration characteristics of CCRS were investigated as the first step study of CSA. Results showed that compared to the direct regeneration of ICRS, concentrating ICRS before regeneration cannot only improve the regeneration performance, but also reduce the regeneration temperature. Despite the increase of solvent viscosity hindering the CO₂ molecular diffusion of regeneration, ICRS should be concentrated to become the special CCRS with higher concentration beyond its unique critical concentration range. Moreover, based on the energy analysis of CSA considering the reboiler heat duty and energy required to concentrate ICRS by taking 30 wt% monoethanolamine (MEA) as an example, theoretically the overall CO₂ regeneration heat requirement may be decreased considerably to 2739.98 kJ/kg of CO₂ by about 34.78% in the future when ICRS was concentrated to 60 wt%.     

Investigation of Ozone Concentration Measurement by Visible Photo Absorption Method

The measurement of ozone concentration based on the visible photo absorption method is investigated. An LED having an emission peak at 609 nm and a photo diode sensitive at visible light frequencies are used as the light source and the photo detector, respectively. The transmittance is measured as a function of ozone concentration, which is in reasonable agreement with the Beer–Lambert relationship. The effective absorption cross-section can therefore be estimated from the fitting procedure. The concentrations determined by both the UV and visible photo absorptions agree well with each other in the range from 7.1 to 68.4 g/m³(N). The relative error in these concentrations is discussed on the basis of the Twyman–Lothian curve. The ozone measurement for the air-fed ozone generation is also investigated. The effect of photo absorption due to NOx species is unavoidable. The present results provide useful data if the ozone measurement based on the visible photo absorption method is applied to ozone monitoring instruments or used for laboratory experiments.