Chemical Engineering & Technology

An optimization technology for the computer-aided molecular design of environmentally friendly solvents with desirable physicochemical and environmental properties is presented. The approach combines a stochastic optimization method and group contribution methods. The methodology is illustrated with several examples of industrial separations.

The optimal flowsheet structures for integrated GTL processes were selected for iron and cobalt-based catalysts. For the cobalt-based catalyst, the full conversion concept without CO₂ removal from the FT tail gas is optimal. The once-through concept with two series reactors and CO₂ removal from raw syngas is considered optimal for the iron-based catalyst.

A high-pressure fluidized-bed coal gasifier for H₂ production with in situ fixation of CO₂ is simulated by a comprehensive 2D model. The Eddy Dissipation Concept (EDC) model is used to simultaneously describe the turbulent mixing and detailed chemical kinetics. The developed model is verified with experimental results.

A theoretical model based on the recently developed two-equation method is proposed to predict the axial mixing behavior in a structured packed column. The process of tracer injection experiment for determining the axial back-mixing coefficient of structured packing can be simulated. In addition, the axial Bo number can be calculated.

A k–ϵ–k_p–ϵ_p model considering the turbulence interaction between the gas and particle phase was incorporated into the two-fluid model based on the kinetic theory of granular flow to simulate three-dimensional steady state flow behavior. The predictions of the pressure gradient are in good agreement with the experimental data.

An experimental study on particle holdup and average residence time in the cyclone is conducted in a cold CFB apparatus. An approximately linear relationship is found between particle holdup and solid circulating rate for various fluidizing air velocities and initial bed heights.

In an effort to better understand the homogeneity of heat treatment of foodstuffs in holding tubes, the cumulative residence time distribution function is derived for a Herschel-Bulkley fluid from fully developed laminar flow in a straight circular tube under isothermal conditions when diffusional effects are negligible. An analytical solution is proposed.

The CO₂ capture capacity for CaO modified with ethanol/water solution is investigated over long-term calcination/carbonation cycles, as an effective technique for capturing CO₂ from combustion processes. CaO modified with ethanol/water solution can act as a new and promising type of calcium-based regenerable CO₂ sorbent for industrial applications.

A simple-to-use correlation is developed to predict the solubility of CO₂ in aqueous solutions of DEA and MDEA as a function of the reduced partial pressure and temperature. The results from the proposed correlation are compared with the reported experimental data and it is found that there is a good agreement between the observed data and the model predictions.

The fuzzy goal attainment method is applied to design a multiple-stage extractive fermentation including cell recycling for producing lactic acid. The fermentation processes including cell recycling enable a higher dilution rate so that the overall productivity is ca. thirteen-fold higher compared to the continuous fermentation process without cell recycling.

A lipase from Burkholderia sp. GXU56 is purified, investigated and its catalytic activity for the enantioselective resolution of (R,S)-methyl mandelate to (R)-mandelic acid is demonstrated. After optimizing the cultivation conditions, the lipase production from Burkholderia sp. GXU56 increases by 4 times.

Heat exchanger networks (HENs) synthesis plays an important role in controlling energy consumption and costs. Recent years have witnessed a rapid development in this field. A new method is proposed to calculate the exergy consumption in the process of heat transfer in HENs more accurately.

For the development and implementation of process-intensive measures, it is expedient to perform a complete analysis of the process of interest. This approach is demonstrated using a size reduction process for a particulate active substance as an example.

A flexible design for a pilot-scale reactor of uniform diameter is presented for the steam cracking coils of olefin furnaces. This pilot plant will be capable of approximating various commercial configurations.

Scale-up equations are developed for the oxygen transfer coefficient, k, and the power number, P_O, of unbaffled circular tank surface aerators under geometrically similar conditions. It is found that that smaller sized aerators are more energy efficient and economical when compared to bigger sized tanks, while aerating the same volume of water.

There are a number of possible geometries for jet injection systems in a cylindrical chamber. The choice among the potential designs may depend on the desired mixing characteristics and power limitations. This paper considers the influence of double row radial jet injection on the quality of mixing in comparison with single row injection.

The influence of the addition of NaCl on the temperature-induced phase separation of 3-methoxypropionitrile and water is investigated experimentally and theoretically. The phase separation of two liquids could be enhanced by addition of a modifier in order to tune the miscibility gap or the operating temperature to a more economically feasible region.

Ceramic sponges are investigated as a new material for different applications and Magnetic Resonance Imaging is used to obtain their structure. Measurements of the specific surface area and the pore diameter are presented. Different methods for image analysis are compared with each other as well as with conventionally obtained data and literature models.

A new approach for a successful prediction of the mass transfer coefficients in the churn-turbulent regime was introduced. Following a definition of the gas-liquid contact time, the classical penetration theory was applied separately to both small and large bubbles. A unique correction factor was introduced and experimental k_La values were predicted reasonably well.