Flow Distribution Channels To Control Flow in Process Channels

Abstract

The invention describes features that can be used to control flow to an array of microchannels. The invention also describes methods in which a process stream is distributed to plural microchannels.

Description

RELATED APPLICATIONS [0001] In accordance with 35 U.S.C. sect. 119(e), this application claims priority to provisional patent application Ser. No. 60 / 745,614 filed 25 Apr. 2006.GOVERNMENT RIGHTS [0002] This invention was made with Government support under contract DE-FE36-04GO14271 awarded by the United States Department of Energy. The government has certain rights in the invention.FIELD OF THE INVENTION [0003] This invention relates to flow control in microchannel devices. INTRODUCTION [0004] Many microchannel devices contain numerous planar, parallel process microchannels. Controlling flow from a manifold or manifolds into these parallel process microchannels has been a major challenge of scaling up microchannel devices. Examples of techniques to control flow (and typically to equalize flow) in parallel process microchannels have been described by Fitzgerald et al. in U.S. Published Patent Application Nos. 2005 / 0087767 and 2006 / 0275185, both of which applications are incorporated ...

AI Technical Summary

Benefits of technology

[0006] Flow distribution in microchannel reactors, separators, and other unit operations may require sufficiently uniform flow distribution for many tens, or hundreds, or thousands of channels. To achieve this sufficiently uniform flow distribution, that is typically characterized by a quality index less than 30%, or less than 20%, or more preferably less than 10%, or most preferably less than 5 or even 1% or less, flow distribution features (also called flow distribution channels (FDCs)) are used to distribute flow. In some flow distribution features, frictional losses can be the primary cause of pressure drop (for example, more than 50%, preferably 70%, more than 90% of losses through the features can be frictional losses). In this invention, orifices and porous plugs are not flow distribution features. Flow distribution channels are introduced either upstream or downstream, but preferably upstream, of connecting microchannels where a unit operation is performed. The flow distribution channels utilize a pressure drop that is higher than the pressure drop in the connecting channels (that is, over the entire length of the connecting channels), preferably by at least 25%, or 50%, or more preferably 2× or 4× or higher. The instability in time and / or variation in pressure drop in the connecting channels where the unit operation is occurring is mitigated from affecting the overall flow distribution to many parallel microchannels.

[0019] The inventive features can also serve to reduce the volume in the headers and or footers of a system. By this manner they serve to reduce the dead volume for applications that require fast transient response such as adsorption or others that are required to respond to transient changes in input parameters in a fast manner. The features also serve to reduce dead volume that may act to increase dispersion in a process such as that which broadens a residence time distribution for the formation of products from selective reactions including oxidations, nitrations, hydrogenations, solids forming reactions, emulsion formation devices and others.

Problems solved by technology

Controlling flow from a manifold or manifolds into these parallel process microchannels has been a major challenge of scaling up microchannel devices.

These patents do not provide suitable means for controlling flow from a manifold in to an array of parallel process channels.

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