Showing papers by "Adam Harvey published in 2003"

Process intensification of biodiesel production using a continuous oscillatory flow reactor

Abstract: Oscillatory flow reactors (OFRs) are a novel type of continuous reactor, consisting of tubes containing equally spaced orifice plate baffles. An oscillatory motion is superimposed upon the net flow of the process fluid, creating flow patterns conducive to efficient heat and mass transfer, whilst maintaining plug flow. Unlike conventional plug flow reactors, where a minimum Reynolds number must be maintained, the degree of mixing is independent of the net flow, allowing long residence times to be achieved in a reactor of greatly reduced length-to-diameter ratio. Many long residence time processes are currently performed in batch, as conventional designs of plug flow reactor prove to be impractical due to their high length-to-diameter ratios, which lead to problems such as high capital cost, large 'footprint', high pumping costs and, also control is difficult. The OFR allows these processes to be converted to continuous, thereby intensifying the process. The transesterification of various natural oils to form 'biodiesel' is a 'long' reaction, usually performed in batch. Conversion to continuous processing should improve the economics of the process, as the improved mixing should generate a better product (rendering the downstream separation processes easier), at lower residence time (reduction in reactor volume). These improvements can decrease the price of 'biodiesel', making it a more realistic competitor to 'petrodiesel'. This paper shows that it is feasible to perform this reaction in an OFR at a lower residence time. The reaction was performed in a pilot-scale plant, using rapeseed oil and methanol as the feedstocks, and NaOH as the catalyst. # 2003 Society of Chemical Industry

Mixing Through Oscillations and Pulsations—A Guide to Achieving Process Enhancements in the Chemical and Process Industries

Abstract: In this article we review the concepts and key developments of mixing enhancement through pulsation and oscillation. We focus on more recent research using oscillations in baffled tubes or columns, which generate discrete vortices as distinct from the more random type of flow produced by the well-established pulsed plate and reciprocating plate column devices. The scope of this review ranges from the basic chemical engineering concepts and key findings from recent research projects, including heat/mass transfer and residence time distribution (RTD); to applications and case studies involving specific reactions, e.g. polymerization and process intensification. We hope that this review will enable the reader to identify additional potential and perhaps an unexpectedly wide range of applications for the oscillatory baffled flow technology.

Fluid mixing and particle suspension in a novel microreactor

Abstract: On catalysis and reaction engineering, new reactor designs at a micro scale are desirable, which could guarantee a scale-down of the production of high valuable products, decreasing the reagents needs and the industrial unit space requirements. Thus, a new reactor design should guarantee a good fluid mixing for applications on the manufacture of specialty chemicals but also be able to keep particles suspended, with a high range of densities for several industrial purposes such as combinatorial (homogenous or heterogeneous) and high-throughput screening catalysis. Furthermore, sequential reactions are of frequent use in these kinds of industries and a single reactor volume able to perform different reactions would be very useful. A novel continuous reactor composed of micro scaled tubes and based on oscillatory flow technology is presented as a new solution for those industrial applications. Since the early 1990s, studies have shown that periodically spaced orifice baffles along the length of a tube, with a net flow coupled with a reversing oscillatory component of the correct magnitude, give high fluid mixing and narrow residence time distribution (Brunold