Process Intensification by Miniaturization

Abstract

The progress of basic research in chemical engineering has led to a better understanding of elementary phenomena, and it is now possible to imagine new operating modes of equipment or design novel equipment based on scientific principles. Process intensification refers to complex technologies that replace large, expensive, energy-intensive equipment or processes with smaller, less costly, more efficient plants, or plants that combine multiple operations into a single apparatus or into fewer devices. Process Intensification using New Operating ModesThe intensification of processes may be obtained by new modes of production which are based on scientific principles. New operating modes have been studied in the laboratory and/or pilot stages: reversed flow for reaction-regeneration, unsteady operations, cyclic processes, extreme conditions, pultrusion, low-frequency vibrations to improve gas-liquid contacting in bubble columns, high temperature and high pressure technologies, and supercritical media are now seriously considered for practical applications. Reactors can be operated advantageously with moving thermal fronts created by periodic flow reversal. Low level contaminants or waste products such as volatile organic compounds can be efficiently removed in adiabatic fixed beds with periodic reversal by taking advantage of higher outlet temperatures generated in earlier cycles to accelerate exothermic reactions. Energy and cost savings are generated by this substitution of internal heat transfer for external exchange [1].Some attractive options for improved catalytic reactor performance via novel modes of operation are periodic (symmetric) operation of packed beds with exothermic reactions, coupling of an exothermic and endothermic reaction in a periodically operated (asymmetric) packed-bed, and induced pulsing liquid flow in trickle beds to improve liquidsolid contacting at low liquid mass velocities in the co-current down flow mode. Also, when high conversions are required and the gaseous by-product of the reaction is known to inhibit the rate, as in hydrodesulfurization or selective hydrogenation, counter-current flow operation of traditional trickle beds is now preferred [2]. Furthemore, improvement of product selectivity in a parallel-series reaction by feeding one reactant through the reactor by stagewise reactant dosing can be achieved [3]. The use of ultrasonic and microwave technologies to enhance the rates and improve the selectivity of catalytic reactions [4] should also be mentioned.Another strong development is related to process intensification via miniaturization. Process Intensification using Microengineering and MicrotechnologyCurrent production modes will be increasingly challenged by decentralization, modularization and miniaturization. Microtechnologies developed, especially in Germany (i.e., IMM, Mainz, and Forschnungszentrum Karlsruhe) and the USA (i.e., MIT and DuPont), lead to microreactors, micromixers, microseparators, micro-heat-exchangers and microanalyzers, allowing for accurate control...

Cassava processing wastewater as a platform for third generation biodiesel production

“…In addition, microalgae are considered to have the potential to be used as biocatalysts in an integrated bioprocess (Charpentier, 2005). According to Maroneze et al (2014), these features enable the use of agro-industrial waste as a carbon source, making it economically feasible while contributing to agroindustrial waste management.…”

Microstructured Catalytic Hollow Fiber Reactor for Methane Steam Reforming

“…[7][8][9][10] All these features come at lower capital and operating costs. 11 The micro-reactor configuration provides mostly a laminar (1< Re< 1000), directed and highly symmetric hydrodynamic flow and reduces the interparticle mass transfer resistance, allowing a better and faster contact between reactants and catalyst. 12,13 Meanwhile, short diffusion lengths for heat and mass transfer contribute to the small temperature and concentration profiles inside micro-reactors.…”

Sustainable Chemical Technologies – Development Trends and Tools

“…Among the reviews published recently are those dealing with green chemistry [7], renewable raw materials [8], C 1 chemistry and methane [9,10], clean fuels [11], syngas [12], trends in catalysis [13,14], nanotechnology [15], miniaturization [16], separation [17], innovations for sustainability [18,19], and others. Certain general and detailed opinions were also expressed in previous papers by the author [1-3, 20, 21].…”