GB2560545A

GB2560545A - A method and apparatus for separate supply of microwave and mechanical energies to liquid reagents in coaxial rotating chemical reactors

Info

Publication number: GB2560545A
Application number: GB1704095.7A
Authority: GB
Inventors: Kouzaev Guennadi
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-03-15
Filing date: 2017-03-15
Publication date: 2018-09-19
Also published as: GB201704095D0

Abstract

Disclosed is a method and geometrically-transformable apparatus for separate supply of microwave and rotating mechanical energies to liquid reagents in coaxial rotating chemical reactors. The method consists in connecting a microwave source current, to only the stator elements 3, 4 of the coaxial vessel, while the rotor 10, 11 installed inside the coaxial shield 1 and partly surrounding the central conductor of coaxial vessel is made of a dielectric transparent to the electromagnetic field. The apparatus is transformable to the Taylor-Couette, Taylor-Couette-Kolmogorov and cavitation reactors. The reactor is a thermally insulated coaxial vessel with an open end central conductor whose other end is connected through a hermetically sealed matching section 5, to a microwave source.

Description

(54) Title of the Invention: A method and apparatus for separate supply of microwave and mechanical energies to liquid reagents in coaxial rotating chemical reactors

Abstract Title: The separate supply of microwave and mechanical energies to liquid reagents in coaxial rotating chemical reactors.

(57) Disclosed is a method and geometrically-transformable apparatus for separate supply of microwave and rotating mechanical energies to liquid reagents in coaxial rotating chemical reactors. The method consists in connecting a microwave source current, to only the stator elements 3, 4 of the coaxial vessel, while the rotor 10, 11 installed inside the coaxial shield 1 and partly surrounding the central conductor of coaxial vessel is made of a dielectric transparent to the electromagnetic field. The apparatus is transformable to the Taylor-Couette, Taylor-CouetteKolmogorov and cavitation reactors. The reactor is a thermally insulated coaxial vessel with an open end central conductor whose other end is connected through a hermetically sealed matching section 5, to a microwave source.

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A METHOD AND APPARATUS FOR SEPARATE SUPPLY OF MICROWAVE AND MECHANICAL ENERGIES TO LIQUID REAGENTS IN COAXIAL ROTATING CHEMICAL REACTORS

BACKGROUND OF THE INVENTION

The present disclosure relates to the reactors for microwave-assisted continuous-flow chemistry, where the mechanical rotational energy is employed for better mixing of reagents to accelerate chemical reactions and increase the reactor's yield.

Microwave heating is a widely known means to accelerate chemical reactions due to volumetrically delivery of heating energy to a mix of polar/unipolar or/and electric conducting reagents. Unfortunately, microwaves have limited penetration depth outside of which the field has negligible magnitude. To avoid the effect of non-homogeneous heating, the vials with liquid reagents are rotating in microwave ovens, or rotating stirrers are placed inside batches placed in microwave resonators. Then, this hardware is used mostly in research and low-volume production laboratories. Several industrial companies manufacturing this equipment are known.

Another way to increase the production volume is the use of continuous-flow chemistry, according to which the reagent liquid moves along the narrow glass-made pipes placed in highpower microwave field of a resonator or waveguide (A. De La Hoz and A. Loupy, Microwaves in Organic Synthesis, Springer Sci., 2012, A.C. Metaxas and RJ. Meredith, Industrial Microwave Heating, IET Press, 2008). In micrometric-size pipes, the diffusion effect prevail in mixing of reagents; in larger-size reactor pipes, the turbulence helps in accelerating of chemical reactions, although it decreases the predictability of yield volume. Additionally, ultrasonification provides an additional means for better mixing of reagents.

On another hand, there are some non-microwave-assisted continuous-flow reactors known, where special-shape stirrers generate turbulence of a certain prescribed type at high rotating speed in the range of 1 000-40 000 rpm, and the residence time of many reactions is decreased down to ten seconds due to better mixing of heated and pressurized liquid or multi-phase reagents (F. Visscher, et al., Rotating reactors - a review, Chem. Eng. Res. Design, vol. 91, pp. 1923-1940 2013, below F. Visscher, 2013).

The interested for this disclosure reactors are of a coaxial design when the rotors are the inner enclosures made of metal or a dielectric. Different turbulence effects are used to increase the mixing of reagents, including the Taylor-Couette vortices generation in the gap between the cylindrical rotor and the larger stator. The size of these cylinders is chosen to provide the condition of the mentioned vortices existence, and the diameter difference of these cylinders is in the centimeter-range (F. Visscher, 2013).

The micrometric range of this difference leads to the Kolmogorov's or molecular vortices, and it increases the yield of reaction close to 90-99 % with the residence time in order of several seconds or minutes realized in spinning tube reactors (R.A. Holl, US Pat. 7,780,927 B2 dated on 08.24.2010, EPA, 600-F111025 Aug. 2011, F. Visscher, 2013).

Some designs are with generation of Kolmogorov's vortices between two discs (one of them is rotating) placed tightly to each other and coaxially placed inside common cylindrical shell (C.M.H. Brechetelsbauer et al., US Pat. 6,482,960 BI dated on 11.19.2002, RJ. Jachuk, US Pat. Appl. 2004/0236039 Al dated on 11.25.2004, R.A. Holl, US Pat. 7,534,404 B2 dated on 05.19.2009, F. Visscher, 2013).

Another rotating reactor of the coaxial design is with a shaped rotor generating cavitation for better mixing of reagents (F. Visscher, 2013).

An analysis of all these reactors shows that they are transformable to each other varying the geometry of cylindrical inner rotors without additional elements included.

Unfortunately, the enhanced mixing of reagents being at ambivalent conditions does not provide enough acceleration of many endothermic chemical reactions, and, according to the Arrhenius law, the mix should be of increased temperature. In the known reactors of the mentioned type, the oil-based system of heating of reagents is used. For instance, hot oil is delivered directly to the channeled reactor parts through rotary joints (C.M.H. Brechtelsbauer et al., US Pat. 6,482,960 BI dated on 11.19.2002). It leads to higher cost of equipment, enlargement of hardware volume, and increased complexity of its exploitation in potentially flammable conditions.

The main idea of this disclosure is to propose a technically and economically efficient method of supply of microwave heating energy and mechanical one to the liquid or multi-phase reagents in a new coaxial rotating reactor generic for spinning tube (Fig. 2a, Taylor-Couette reactor (Fig. 2a), disk ones (Fig. 2b) based on the Kolmogorov's molecular vortices, and cavitation reactor (Fig.

2c).

A comparative analysis of known published mechanically-driven coaxial reactors (F. Visscher, 2015) and microwave-assisted coaxial one (G. Kouzaevand S. Kapranov, UK Patent Appl. GB2536485 dated on 19.03.2015) shows that direct and simple connection of a microwave generator to spinning coaxial reactor does not give effective design.

A new method of feeding these reactors by microwave and mechanical energies should be developed that can be realized in a hardware unit generic for the mentioned rotating coaxial reactors.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be described further, by way of example only, with reference to embodiments thereof illustrated in the accompanying drawings, in which:

Fig. la illustrates the longitudinal section of the invented apparatus for separate supply of microwave and rotation energies to reagents;

Fig. lb illustrates the cross-sectional view of apparatus at the plane A-A (see Fig.la);

Fig. lc illustrates the cross-sectional view of apparatus at the plane B-B (see Fig. la);

Fig. Id illustrates the cross-sectional view of apparatus at the plane C-C (see Fig.la);

Fig.2a illustrates a geometrical transformation of the generic apparatus fragment (Fig.1) into one for Taylor-Couette reactor;

Fig.2b illustrates a geometrical transformation of the generic apparatus fragment (Fig.1) into one for hybrid Taylor-Couette-Kolmogorov's vortices reactor;

Fig.2c illustrates a geometrical transformation of the generic apparatus (Fig.1) into one for cavitation reactor shown in cross-section.

DETAILED DESCRIPTION OF THE INVENTION

The proposed method for separate supply of microwave and mechanical energies to liquid reagents in coaxial rotating chemical reactors consists in feeding only the stator elements by microwave currents, while the rotor installed inside the coaxial shield and surrounding the central conductor of coaxial reactor is made of a dielectric transparent to electromagnetic field.

By this technique, the complexity of feeding of reactors through rotating microwave connectors workable in the range of several tens of thousands rpm is dismissed. Besides, this dielectric rotor protects the liquid from overheating occurs at close proximity to the bare central conductor, and this dielectric shield serves as an additional element to match this reactor to the microwave generator's output impedance. The method is explained in Figs. 1 and 2 illustrate additionally the design of the invented apparatus accompanying the text. These examples are intended to illustrate the present invention, and are not to be considered as limiting invention in any way.

The invented apparatus (Fig.1) comprises a vessel with its metallic cylindrical shield 1 covered by insulation layer 2 to avoid loss of thermal energy. Inside of this shield 1, a cylindrical coaxial conductor is installed consisting of two sections 3 and 4 and comprising with the metallic vessel 1 a stepped open-end coaxial resonator.

The left side of the conductor 3 is connected to the microwave generator MW AC through mountable and sealed coaxial connector 5. Conductor 3 is covered by a cylindrical dielectric 6 with the aim to prevent overheating (may occur close to bare conductor) of a liquid mix of reagents coming to the area 7 through cylindrical pipe 8. The metallic posts 9 are for rough tuning of the input reactor's impedance to the output one of the microwave generator MW AC.

Coaxial central conductor 4 is installed inside rotor 10. This rotor made of a dielectric transparent to electromagnetic field at working frequency of the reactor. The length of this section 4 is chosen close to A(2n-l)/4 at room temperature of pumped liquid, for instance, where n is the resonance number, Λ is the wavelength of main mode of multilayered coaxial waveguide composed of cylinder shield 1, central conductor 4, rotor's dielectric 10, and liquidfilled gap between the last one and shield 1. Dielectric rod 11, which is the solid extension of the rotor, is for transfer of torque from an electromotor (is not shown in Figs).

The main chemical reaction zone is in the gap between the rotor 10 and shield 1 and in the gap between the outer rotor-end and sealed mountable cap 12.

The motion of dielectric rotor 10/11 excites the Kolmogorov's molecular vortices in narrow gaps (500-600 microns) that allows better mixing of heated by microwaves liquid reagents. In the larger-gap reactors (Fig. 2), the Taylor-Couette vortices enable mixing heated reagents as well.

The product of chemical reactions moves out of the reaction zone to the collector area 13 to which the outlet 14 is connected. Rotary seal 15 prevents non-prescribed leakage of liquid.

Harmful microwave irradiation is prevented from this reactor making pipes 8, 13, and 14 evanescent for all microwave modes of these pipes. The sharp corners of the rotor and stator are rounded to avoid the unwanted electric field concentration and associated with it liquid overheating or even microwave discharge effect near these corners. As well, this makes less distorted the liquid flow.

The described in Fig.l apparatus' geometry is generic to several types of reactors, and they are shown in Fig. 2, where simple geometrical shaping of rotor from Fig. 1 can transform this device into (a) the Taylor-Couette reactor with its large gaps; (b) hybrid design where the end zone of the reactor provides the Kolmogorov's mixing in narrow gap at the right end of the coaxial reactor additionally to the Taylor-Couette zone around the cylindrical surface of dielectric rotor; (b) cavitation reactor obtained by shaping of dielectric rotor.

To provide the optimal parameters of the listed reactors, they should be calculated taking into account the electromagnetics, heat and liquid dynamics, and the mechanics issues.

Claims

CLAIMS:

1. A method for separate supply of microwave and mechanical energies to liquid reagents in coaxial rotating chemical reactors comprising in connecting to a microwave source current only the stator elements, while rotor installed inside the coaxial shield and partly surrounding the central conductor of coaxial vessel is made of a chemically-resistant dielectric solid transparent to electromagnetic field

2. An apparatus according to Claim 1, which is transformable to the Taylor-Couette, TaylotCouette-Kolmogorov, and cavitation reactors, supplied by microwave and rotating mechanical energies according to Claim 1 and comprising a thermally-insulated coaxial vessel with an openend central conductor whose another end connected hermetically through a matching section to a microwave source using sealed connector and surrounded partly by a chemically-resistant dielectric-made rotor driven by an electromotor using the dielectric rod shaft coming to it through a rotary seal, while liquid is pumped and evacuated from the vessel using narrow pipes resistant to propagation of microwave waves at the source frequency

Intellectual

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Application No: GB1704095.7 Examiner: Mr David Maskery