Title: Rotating surface of revolution reactor with feed and collection mechanisms
Abstract: A reactor including a rotatable disc (3) having a trough (13) in an upper surface (5) thereof. Reactant (15) is supplied to the trough (13) by way or a feed (4), the disc (3) is rotated at high speed, and the reactant (15) spills out of the trough (13) so as to form a film (17) on the surface (5). As the reactant (15) traverses the surface (5) of the disc (3), it undergoes chemical or physical process before being thrown from the periphery of the disc (3) into collector means (7).
Patent Number: 6,858,189 Issued on 02/22/2005 to Ramshaw, et al.
| Inventors:
|
Ramshaw; Colin (Ponteland, GB);
Jachuck; Roshan Jeet Jee (Abbey Farm, GB);
Jones; Michael (Royston, GB);
Henderson; Ian (Stokesley, GB)
|
| Assignee:
|
Protensive Limited (a company incorporated in England) (Cambridge, GB)
|
| Appl. No.:
|
913902 |
| Filed:
|
January 23, 2002 |
| PCT Filed:
|
February 17, 2000
|
| PCT NO:
|
PCT/GB00/00521
|
| 371 Date:
|
January 23, 2002
|
| 102(e) Date:
|
January 23, 2002
|
| PCT PUB.NO.:
|
WO00/48729 |
| PCT PUB. Date:
|
August 24, 2000 |
Foreign Application Priority Data
| Current U.S. Class: |
422/186; 118/52; 118/53; 118/620; 118/641; 422/136 |
| Intern'l Class: |
B01J 019//08 |
| Field of Search: |
422/186,136
118/52,53,620,641
|
References Cited [Referenced By]
U.S. Patent Documents
| 3831907 | Aug., 1974 | Claes.
| |
| 4311570 | Jan., 1982 | Cowen et al.
| |
| 4343750 | Aug., 1982 | Holiday et al.
| |
| 4356133 | Oct., 1982 | Cowen et al.
| |
| 4511414 | Apr., 1985 | Matsui et al.
| |
| 4549998 | Oct., 1985 | Porter et al.
| |
| 4627803 | Dec., 1986 | Umetsu.
| |
| 5624999 | Apr., 1997 | Lombardi et al.
| |
| Foreign Patent Documents |
| 0 020 055 | Dec., 1980 | EP.
| |
| 0 499 361 | Aug., 1992 | EP.
| |
| 0 810 633 | Dec., 1997 | EP.
| |
| 328410 | May., 1930 | GB.
| |
| 1080863 | Aug., 1967 | GB.
| |
| 1600708 | Oct., 1981 | GB.
| |
| 2108407 | May., 1983 | GB.
| |
| WO 96/00189 | Jan., 1996 | WO.
| |
Primary Examiner: Mayekar; Kishor
Attorney, Agent or Firm: Garvey, Smith, Nehrbass & Doody, L.L.C., Nehrbass; Seth M., North; Brett A.
Claims
What is claimed is:
1. A reactor apparatus including a support element adapted to be rotatable
about an axis, the support element having a surface, feed means for
supplying at least one reactant to the surface of the support element and
collector means for collecting product from the surface of the support
element, wherein the surface includes an undercut trough into which the at
least one reactant is directly supplied by the feed means, and in that,
upon rotation of the support element, the at least one reactant forms a
generally annular film within the at least one undercut trough and passes
therefrom across the surface of the support element, further including a
plurality of support elements wherein the plurality of support elements is
mounted on a plurality of axes of rotation and wherein a processing unit
is provided between the collector means of the first support member and
the feed means of the second support member.
2. A reactor as claimed in claim 1, wherein the processing unit is a pump,
an extruder, a heater or a heat exchanger.
3. A reactor apparatus including a support element adapted to be rotatable
about an axis, the support element having a surface, feed means for
supplying at least one reactant to the surface of the support element and
collector means for collecting product from the surface of the support
element, wherein the surface includes an undercut trough into which the at
least one reactant is directly supplied by the feed means, and in that,
upon rotation of the support element, the at least one reactant forms a
generally annular film within the at least one undercut trough and passes
therefrom across the surface of the support element, wherein there is
further provided a rotary impeller mounted close to the surface and
operable to generate a gaseous flow from a periphery of the surface
towards a central region thereof, this flow being counter-current to a
flow of reactant on the surface.
Description
This application is a 35 USC 371 National Stage of PCT/GB/00/00521 filed
Feb. 17, 2000.
The present invention relates to a rotating surface of revolution reactor
provided with various feed and collection mechanisms for input and output
products.
The invention makes use of rotating surfaces of revolution technology
(hereinafter RSORT) (commonly known as spinning disc technology).
BACKGROUND
The spinning disc concept is an attempt to apply process intensification
methods within the fields of heat and mass transfer. The technology
operates by the use of high gravity fields created by rotation of a disc
surface causing fluid introduced to the dire surface at its axis to flow
radially outward under the influence of centrifugal acceleration in the
form of thin often wavy films. Such thin films have been shown to
significantly improve the heat and mass transfer rates and mixing. The
technology was developed for typical heat and mass transfer operations
such as heat exchanging, heating, cooling and mixing, blending and the
like, for example as disclosed in R J J Jachuck and C Ramshaw, "Process
Intensification: Heat transfer characteristics of tailored rotating
surfaces", Heat Recovery Systems & CHP, Vol. 14, No 5, p475-491, 1994.
More recently the technology has been adapted for use as a reacting surface
for systems which are heat and mass transfer limited, for example for the
reaction of substrates which are highly viscous during at least a stage of
the reaction and cause problems in achieving good mixing and product
yields.
Boodhoo, Jachuck & Ramshaw disclose in "Process Intensification: Spinning
Disc Polymeriser for the Manufacture of Polystyrene" the use of a spinning
disc apparatus in which monomer and initiator is reacted by conventional
means to provide a pre-polymer which is then passed across the surface of
a spinning disc at elevated temperature providing a conversion product in
the form of polymerised styrene.
EP 0 499 363 (Tioxide Group Services Limited) discloses another use for
spinning disc technology in photo catalytic degradation of organic
materials such a hydrocarbons. A solution of salicylic acid and titanium
dioxide catalyst was passed across the surface of a rotating disc and
irradiated with ultra violet light.
These publications therefore disclose the use of spinning disc technology
for heating and mass transfer in inert and reactive systems.
GB 9903474.6 (University of Newcastle), firm which the present application
claims priority and the disclosure of which is hereby incorporated into
the present application by reference, describes the use of RSORT in the
conversion of a fluid phase substrate by dynamic heterogeneous contact
with an agent. In this application, it is described how it has
surprisingly been found that spinning disc technology may be further
adapted to apply process intensification methods not only within the
fields of heat and mass tar but also within the field of heterogeneous
contacting. Furthermore, it is described how it has surprisingly been
found that the quality of the product obtained is of higher quality than
that obtained by conventional processing having, for example, a higher
purity or, in polymers, a narrower molecular distribution.
In addition to this, spinning disc technology can be used to obtain
products not readily obtainable by other technology.
According to the present invention, there is provided a reactor apparatus
including a support element adapted to be rotatable about an axis, the
support element having a surface, feed means for supplying at least one
reactant to the surface of the support element and collector means for
collecting product from the surface of the support element, characterised
in that the surface includes an undercut trough into which the at least
one reactant is directly supplied by the feed means when the reactor
apparatus is in use, and in that, upon rotation of the support element,
the at least one reactant forms a generally annular film within the at
least one undercut trough and passes therefrom across the surface of the
support element.
SUMMARY
It is to be understood that the term "reactant" is not limited to
substances which are intended to undergo chemical reaction on the surface
of the support element, but also includes substances which are intended to
undergo physical or other processes such as mixing or heating. Similarly,
the term "product" is intended to denote the substance or substances which
are collected from the surface of the support element, whether these have
undergone chemical or physical processing or both. In addition, although
it is envisaged that most reactants and products will be in the liquid
phase, the apparatus can be used with any suitable fluid phase reactants
and products, including combinations of liquid, solid and gaseous
reactants and product. For example, solid phase substances in
substantially free-flowing particulate form can have macroscopic fluid
flow properties.
The depth of the trough may be selected in accordance with reaction
requirements. For example, for photochemical reactions in which UV light
is shone onto the reactant, it is preferred for the trough to be
relatively shallow, for example having a depth of the same order of
magnitude or within one order of magnitude as the expected thickness of a
film of reactant formed across the surface of the support element when
rotating at an appropriate speed.
An RSORT apparatus (commonly known as a spinning disc reactor) generally
includes within a conversion chamber a rotating surface or an assembly of
a plurality of these which is rid about an axis to effect transfer of one
or more reactants from the axis preferably radially across the rotating
surface.
An RSORT apparatus as hereinbefore defined comprising a rotating surface as
hereinbefore defined has a number of advantageous constructional features
according to the present invention.
The axis of rotation of the rotating surface or support member may be
substantially vertical, in which cals gravity tends to pull reactants
downwardly with respect to the surface or support member. This may be
advantageous with less viscous reactants. Alternatively, the axis of
rotation may be generally horizontal, which can achieve improved mixing of
reactants provided that these are appropriately retained on the surface of
the support member.
Any suitable feed means may be provided to feed the at least one reactant
onto the rotating surface. For example, the feed means may comprise a feed
distributor in the form of a "shower head", a "necklace" of outlets or a
simple, preferably adjustable, single point introduction such as a
"hose-pipe type" feet means. Preferably, the feed means comprises a feed
distributor having a plurality of uniformly spaced outlets for the at
least one reactant on to the rotating surface as hereinbefore define. The
feed means may also include means for applying UV, IR, X-ray. RF,
microwave or other types of electromagnetic radiation or energy, including
mimetic and electric fields, to the reactants as they are fed to the
trough, or may include means for applying vibration, such as ultrasonic
vibration, or heat.
The feed means may be provided at any suitable position with respect to the
rotating surface which allows feed of the reactant. For example, the feed
means may be axially aligned with the rotating surface for axial feed.
Alternatively, the feed means may be positioned such that the feed is
spaced from the axis of the rotating surface. Such a position may lead to
more turbulence and an enhanced mixing effect.
In one embodiment, feed mean may comprise a single feed to the trough which
is preferably situated on or coaxial with the axis of rotation of the
rotating surface. In this embodiment, reactant flows form the feed outlet
into the tough and is subsequently spread out of the tough on to the
rotating surface by centrifugal force. In a preferred embodiment, the
rotating element as hereinbefore defined comprises a trough situated on
the axis of rotation.
The trough as hereinbefore defined may be of any suitable shape such as
continuous or annular. For example it may have a continuous concave
surface comprising part of a sphere, such as a hemispherical surface, or
it may have an inner surface joined to the rotating by at least one
connection wall or at least two, in the case where the trough is annular.
The inner surface and connection wall may be of any form which allows the
function of a trough to be fulfilled. For example the inner surface may be
parallel to the rotating surface or concave or convex. The connection wall
may comprise a single circular or avoid wall or a plurality of straight
walls. The walls may diverge or converge towards the rotating surface.
Preferably, a single circular wall is provided which converges towards the
rotating surface to form an undercut tough. This shape generates a
reservoir which enhances a circumferential distribution of the reactant
flow. Alternative means for forming an undercut trough are also envisaged.
For example, where the trough is generally annular in shape, an outer wall
may be provided as above, and an inner wall having any suitable shape may
serve to define an inner edge to the trough. The undercut portion of the
trough should generally be provided as an outer wall so as to help prevent
uncontrolled egress of reactant from the trough to the surface under the
influence of cents force as the support element is rotated.
Advantageously, a matrix may be provided in the trough so as to help
reactant present in the trough to rotate with the support element, hereby
helping to achieve substantially uniform flow from the trough across the
surface. The matrix may be in the form of a plug of fibrous mesh, such as
metal or plastics wool, or may take the form of a plurality of projections
which are secured to an inner surface of the trough. Other matrix means
will be apparent to the skilled reader. In some embodiments, the matrix is
manufactured of a material which is inert with respect to the at least one
reactant or the product and which is not significantly affected by
temperature and other variable process conditions. Alternatively, the
matrix may be made of a material which does interact with the at least one
reactant or the product, such as a heterogeneous catalyst (e.g. nickel,
palladium or platinum or any suitable metal or alloy or compound therof).
Where the matrix is made out of an electrically conductive material, it
may be possible to supply an electric current therethrough and thus to
provide heating means for heating the at least one reactant within the
trough.
In a further embodiment, there may be provided a plurality of feeds adapted
selectively to supply one or more to a plurality of troughs formed in the
surface. For example, where the support element is generally disc-like and
has a substantially central axis of rotation, there may be provided a
first central trough centered on the axis orientation and feed means for
supplying at least one reactant to the first trough, and at least one
further trough, preferably also centered on the axis of rotation and
having an annular configuration, the at least one further trough being
provided with feed means for supplying a second reactant, which may be the
same as or different from the first reactant, to the at least one further
trough. It will be apparent to the skilled reader that a plurality of
troughs may be provided in a similar manner on support elements with
shapes other than generally disc-like.
By providing a plurality of troughs and feeds, a sequence of reactions can
be performed across the surface of the support element. For example, two
reactants may be supplied to the first trough in which some mixing and
will take place. As the support element rotates, the reactants will spread
from the first trough to the surface of the support element, where further
reaction and mixing takes place, and thence into a second annular trough
concentric with the first trough. A third reactant may then be supplied to
the second trough, and further mixing and reaction will take place as the
third reactant and the two initial reactants and any associated product
are spread from the second trough onto the surface of the support element
for further mixing and reaction. Because the direction of travel of the
reacts and products is outwards from the axis of rotation, a controlled
series of reactions can be carried out across the surface of the support
member.
In some embodiments, one of the reactants may be a liquid phase component
and another may be a gaseous phase component. In these embodiment, the
rowing support member is advantageously contained within a vessel so as to
allow the concentration of the gaseous phase component in the vicinity of
the surface to be controlled. The liquid component may be fed to the
surface of the disc as described above, and the gaseous component supplied
to the vessel. A rotary impeller or fan or similar device may be mounted
close to the rotating surface and driven so as to suck the gaseous phase
component from a region surrounding the periphery of the rotating surface
towards the centre of the rotating surface while the liquid phase
component travels from the centre of the surface towards its periphery due
to the rotation of the rotating surface. Where, for example, the support
element is a disc, the impeller or fan may take the form of a generally
disc shaped structure mounted coaxially with the support element and close
thereto. A surface of the impeller or fan facing the rotating surface of
the support element may be provided with blades or vanes such that
rotation of the impeller or fan serves to suck the gaseous phase component
from a periphery of the sac and the impeller or fan towards the centre of
the surface. By providing a counter-current flow of the gaseous and liquid
phase components, heat or mass transfer between the components is much
improved, since the concentration of unreacted liquid phase reactant is
lowest at the periphery of the disc, and therefore benefits from a high
concentration of the gaseous phase component so as to ensure full
reaction.
Any suitable collection means may be provided for collection of the product
as it leaves the rotating surface at its periphery. For example, there may
be provide a receptacle in the form of a bowl or trough at least partially
surrounding the rotating element or other fixed part of the apparatus. The
collection means may additionally comprise a deflector positioned around
the periphery of the rotating surface to deflect product into the
collection means the deflector is preferably positioned at an acute angle
to the rotating surface.
The components of the collection means, such as the bowl or trough or
deflector, may be coated or otherwise provided with a heterogeneous
catalyst appropriate to the reactants being reacted on the support element
or may even consist entirely of a material which acts as a heterogeneous
catalyst. Furthermore, the components of the collection means may be
heated or cooled to a predetermined temperature so as to enable control
over reaction parameters for example by serving to halt the reaction
between reactants as these leave the surface in the form of product. Feed
means for supplying a reactant to the product leaving the surface may also
be provided. For example, there may be provided feed means for feeding a
quenching medium to product in the collection means so as to halt chemical
or other reactions between reactants when these have left the surface.
The collection mea may further comprise outlet means of any suitable form.
For example, there may be a single collection trough running around the
periphery of the disc or a collection bowl partially surrounding the
rotating element.
Outlet means may also be provided in the collection means and these may
take the form of apertures of any size and form situated at any suitable
position of the collection means to allow egress of the product. In one
preferred embodiment, the outlet means are situated to allow vertical
egress of the substrate in use.
Alternatively, the collection means may comprise an outer wall provided at
the periphery of the support element so as to prevent product from being
thrown from the surface, and at least one pilot tube which extends into
the product which is restrained at the periphery of the support element by
the outer wall. The outer wall may converge generally towards the axis of
rotation of the support member so as better to retain product while the
support element is undergoing rotation, although other wall
configurations, such as generally parallel to or divergent from the axis
of rotation may also be useful.
Embodiments of the present invention include multiple sup elements, which
may share a common axis of rotation and which may be mounted on a single
rotatable shaft, or which may be provided with individual rotatable
shafts. The collection means associated with any given support element may
be connected to the feed means associated with any other given support
element so as to link a number of support elements in series or parallel.
In this way, a reaction may be conducted across a number of support
elements in series or parallel. The collection means of a first support
member may be directly connected to the feed means of a second support
member, or may be connected by way of a processing unit such as a pump,
extruder, heater or hem exchanger or any other appropriate device. This is
especially useful when dealing with viscous products, such as those which
are obtained in polymerisation reactions, since the viscous product of a
first support element may be processed so as to acquire more favourable
physical characteristics before being used as the reactant feed for a
second support element.
For example, where the collection means comprises an outer wall on the
surface of the support element as described above, a number of support
elements may be coaxially mounted on a single rotatable shaft so as to
form a stack of support elements. A reactant fed is led to the trough of a
first support element, and a collector in the form of a pilot tube has its
tip located near the surface of the fist support element in the vicinity
of the wall so as to take up product from this region. An end of the pilot
tube remote fin the tip is led to the trough of a second support element
so as to allow the product of the first support element to serve as the
reactant for the second support element thereby allowing a number of
reactions to take place in series. Alternatively, a number of parallel
fees may supply the same at least one reactant simultaneously to the
troughs of a number of support elements and a number of parallel pilot
tube collectors may gather product from a peripheral region of each
support element, thereby allowing a reaction to take place across a number
of sort elements in parallel.
It is also envisaged that product collected from the periphery of a support
element may be recycled as feed for that support element. This is useful
for processes requiring an extended contact time for the reacts. The
product may be fully or only partially recycled, depending on
requirements.
Reference herein to a rotating surface is to any continuous or discrete
planar or three dimensional surface or assembly which rotates
approximately or truly about an axis, and preferably is reference to an
approximate or true rotating surface of revolution. An approximate
rotating surface of revolution may comprise an asymmetric axis and/or
deviation in the surface body and/or circumference creating an axially or
radially undulating surface of revolution. A discrete surface may be in
the form of a mesh, grid, corrugated surface and the like.
Reference herein to a substantially radially outward flowing film as
hereinbefore defined is to any fluid film which may be created by dynamic
contact of the fluid phase reactant and the rotating surface as
hereinbefore defined, suitably the fluid phase reactant is contacted with
the rotating sure at any one or more surface locations and caused to flow
outwardly by the action of central force. A film may be a continuous
annulus or may be a non-continuous arc at any radial location. The
substrate may provide a plurality of films in dynamic contact with a
rotating surface as hereinbefore defined.
For example processes requiring extended contact time may be carried out in
continuous manner with use of a recycle of fluid exiting at the periphery
of the rotating surface towards the axis of the rotating surface enabling
sequential passes of fluid across the surface. In continuous steady state
operation an amount of fluid exiting the surface may be drawn off as
product and an amount may be returned by recycle for further conversion
with an amount of fresh reactant feed.
The process of the invention as hereinbefore defined may operated in a
single or plural stages. A plural stage process may comprise a first
pre-process stage with further post-process or upgrading stages, and may
be carried out batchwise with use of a single rotating surface as
hereinbefore defined or may be carried out in continuous manner with
multiple rotating surfaces in series.
Second or more reactants may be added to the feed reactant as it passes
from one rotating assembly to the next or be added directly to the
rotating assembly anywhere between the axis of rotation or the exit from
the assembly. In certain cases a multi-step process may be achieved by
reactant addition or additions between the axis of rotation and the exit
of a single rotating assembly to achieve more than one process step in a
single pass. It is also possible to have different regions of the rotating
surface at different temperatures and conditions and have different
surface geometries as appropriate to the process needs.
It will be apparent that the process of the invention may be controlled
both by selection of a specific rotating surface for the support element
and by selecting process variables such as temperature, speed of rotation,
rate of reactant feed, conversion time and the like. Accordingly the
process of the invention provides enhanced flexibility in process control
including both conventional control by means of operating conditions, and
additionally control by means of rotating surface type.
The apparatus may further comprise any suitable control system. Such a
control system may regulate the temperature or contact time of reactants
by means of speed of rotation, rate of substrate feed and other process
parameters to obtain an optimum result.
The apparatus as hereinbefore defined may comprise means for optimising
process conditions. For example, means for imparting an additional
movement to the rotating surface, and thus to the reactant, may be
provided. Such movement could be in any desired plane or plurality of
planes and preferably comprises vibration. Any suitable vibration means
may be provided, such as flexible mounting of the surface or off centre
mounting, both inducing passive vibration or active vibration means, such
as a mechanical element in contact with the rotating element and vibrating
in a direction parallel to the rotating element axis. Preferably a passive
vibration means is provided in the form of off centre mounting of the
rotating element on its axis of rotation. Vibration may alternatively be
provided by an ultrasonic emitter in contact with the rotating element for
vibration in any desired plane or plurality of planes.
The rotating surface may have any shape and surface formation to optimise
process conditions. For example the rotating surface may be generally
planar or curved, frilled, corrugated or bent. The rotating surface may
form a cone or be of generally frustoconical shape.
In one preferred embodiment the rotating surface is generally planar and
preferably generally circular. The periphery of the rotating surface may
form an oval, rectangle or other shape.
In another preferred embodiment the rotating surface is provided as the
inner surface of a cone. The apparatus may comprise at least one cone and
at least one other rotating surface or at least one pair of facing cones
positioned so as to allow a two stage process with one or more reactants
fed to each cone. Preferably product exits a smaller cone (or other
surface of rotation) in a spray on to the surface of a larger cone (or
other surface of rotation) by which it is at least partially surrounded
and for the surface of which a further reactant is fed by feed means as
hereinbefore defined, to allow mix of the product and reactant on the
larger rotating surface. Preferably, means are provided such that the two
cones counter rotate. Such an arrangement enhances mixing and intimate
contact of the reactants and reduces the required physical contact time.
Alternatively, means are provided such that the cones co-rotate or one is
stationary.
In another embodiment, there may be provided two generally planar support
elements mounted coaxially and generally parallel to each other on an axis
of rotation. The facing surfaces of the support elements may be provided
with at least one generally circular wall defined about the axis of
rotation, and preferably a plurality of concentric walls, the walls being
divergent with respect to the axis of rotation of their respective support
element. The walls on one support element are positioned out of phase with
the walls on the other support element so that the walls fit between each
other when the support elements are brought close together. Reactant may
be supplied to a region within the innermost wall on one of the support
elements. Upon rotation of the support elements, the reactant will tend to
move along an interior surface of the divergent wall towards a region
within the next wall on the opposed support element, and thence onto an
interior surface of the said next wall back towards the first support
element. The reactant may continue to move back and forth between the
support members so as to progress in a zig-zag manner in a generally
radial direction away from the axis of rotation along the interior
surfaces of the intermeshed walls towards an outer collection point as
described above. In this way, a compact reactor with a high surface area
is achieved, the surface consisting of the interior surfaces of all the
concentric walls. The support elements may rotate together in a given
direction, or may rote at different speeds in the same direction, or may
rotate at the same speed or at different speeds in opposed direction.
A rotating surface of any shape and surface formation as hereinbefore
defined may be provided with surface features which serve to promote the
desired process. For example, the surface may be micro or macro profiled,
micro or macro porous, non stick, for example may have a release coating,
may be continuos or discontinuous and may comprise elements such as mesh,
for example woven mesh, reticulate foam, pellets cloth, pins or wires, for
enhanced surface area, enhanced or reduced friction effect, enhanced or
reduced laminar flow, shear mixing of recirculation flow in axial
direction and the like.
In one preferred embodiment, mixing characteristics of the rotating surface
are enhanced by the above features or the like provided on or in the
rotating surface. These may be provided in any suitable regular or random
arrangement of grids, concentric rings, spider web or like patterns which
may be suitable for a given application.
Alternatively or additionally to any other surface feature, radially spaced
pins in the form of circles or segments of circles may be provided.
In another preferred embodiment, a porous surface coating is provided,
which aids processing of certain reacts. Such a coating may be provided in
combination with any other of the aforementioned surface features.
Surface features in the form of grooves may be concentric or may be of any
desired radially spaced form. For example, the grooves may form "wavy" or
distorted circles for maximised mixing.
Grooves may be parallel sided, or may have one or both sides which diverge
to form undercut grooves or which converge to form tapered grooves.
Preferably, the grooves are undercut to promote mixing.
Grooves may be angled to project towards or away from the axis of the
rotating surface to enhance or reduce undercut or taper.
Energy transfer means may be provided for the rotating surface or reactant
or product as hereinbefore described. For example heating means may be
provided to heat the reactant, for example, as part of the feed means.
Additionally, or alternatively heating means may be provided to heat the
rotating element in the form of radiant or other heaters positioned on the
face of the rotating element which does not comprise the rotating surface
for conversion. Preferably, radially spaced, generally circular radiant
heaters are provided.
Any preferred cooling or quenching means may be provided in a suitable
position to cool the reacted substrate. For example cooling coils or a
heat sink may provide cooling by heat exchange, or a reservoir of quench
may provide cooling or reaction termination by intimate mixing in the
collection means.
For a better understanding of the present invention and to show how it may
be carried into effect, reference shall now be made by way of example to
the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 shows a spinning disc apparatus in schematic form;
FIG. 2 shows a detail of a spinning disc having a central trough;
FIG. 3 shows a detail of a spinning disc having an annular trough;
FIG. 4 shows a number of spinning discs in schematic form and operatively
arranged in series;
FIG. 5 shows a number of spinning discs in schematic form and operatively
arranged in parallel;
FIG. 6 shows two coaxial spinning discs in schematic form and provided with
a pump unit for transferring product from one disc as feed to the second
disc;
FIG. 7 shows two rotating support elements with intermeshing concentric
circular walls; and
FIG. 8 shows a spinning disc provided with a rotary impeller;
FIG. 9 shows the spinning disc of FIG. 3 rotated at an angle;
FIG. 10 shows the spinning disc of FIG. 3 rotated at a perpendicular angle;
FIG. 11 shows a plurality of troughs provided on the surface and each
trough has associated with it a feed means; and
FIG. 12 shows a plurality of support elements mounted on a plurality of
axes of rotation.
DETAILED DESCRIPTION
FIG. 1 illustrates a spinning disc apparatus of the present invention. The
apparatus is enclosed in vessel (1) having at its axis a drive shaft (2)
supporting a spinning disc (3). Feed means (4) provides reactant to an
undercut annular trough (13) provided in the surface (5) of the disc (3)
about its axis (6). Rotation of the disc (3) causes reactant to flow
radially outwards, whereby it contacts the surface (5) of the spinning
disc (3). Fluid is collected at the peripheral edges of the disc (3) by
means of collection trough (7) and may be rapidly quenched by means of
cooling coils (8). A skirt (9) prevents meniscal draw back of fluid
contaminating the drive shaft mechanism. Inlet means (10) enable
controlled environment conditions to the provided, for example a nitrogen
atmosphere. Outlet vent means (11) enable the venting of atmospheric gases
or gases evolved during operation. Observation means are provided by means
of windows (12) to observe the progress of the conversion.
The apparatus of FIG. 1 may be started up and operated as described in
Example 1 below. In the case that the process is an exothermic conversion,
cooling coils (8) may be used to quench the collected product in the
trough (7). The spinning disc (3) is provided with heating coils (not
shown) which may be used to initiate or maintain conversion. The disc (3)
or the reactor vessel (1) may be provided with a source of radiation
(100), means for applying an electric or magnetic field and the like as
described, at or above the disc surface (5) or at the wall of the reactor
vessel (1).
In FIG. 2 there is shown an axially located central trough (14) which is
continuous and forms a well situated on the axis of rotation (6) of the
rotating surface (5) of a disc (3). Rotation causes reactant (15) supplied
by the feed means (4) to flow to the wall and form an annular film (16)
within the trough (14). The annular film (16) then spills over onto the
surface (5) of the disc (3) to form a film (17) on the surface (5).
Eccentric axis of rotation (6') is also shown.
In FIG. 3 the trough (13) is annular and forms a channel co-axial about the
axis of rotation (6) of the disc (3). Rotation assisted by the trough
profile causes reactant (15) to flow into the trough (13) and to the wall
thereof and form an annular film (16) within the trough (13) before
spilling over onto the surface (S) of the disc (3) in the form of a film
(17).
FIG. 4 shows three discs (3) coaxially mounted on a drive shaft (2) which
defines an axis of rotation (6). Each disc (3) has a central trough (13)
into which reactant (15) may be fed, and a peripheral wall (18). Reactant
(15) is supplied to the trough (13) of the topmost disc (3) by way of feed
means (4), and then spreads out over the surface (5) of the disc (3).
Product (19) is collected from the vicinity of the peripheral wall (18) by
way of a pilot tube collector (20), which then feeds product (19) to the
trough (13) of the next disc (3) down on the drive shaft (2). In this way,
a process can be performed across a number of discs (3) in series. Means
for applying vibration (200) is also shown.
FIG. 5 shows three discs (3) coaxially mounted on a drive shaft (2) which
defines an axis of rotation (6). Each disc (3) has a central trough (13)
into which reactant (15) may be fed, and a peripheral wall (18). Reactant
(15) is supplied in parallel to the trough (13) of each disc (3) by way of
feed means (4), and then spreads out over the surfaces (5) of the discs
(3). Product (19) is collected from the vicinity of the peripheral walls
(18) by way of pilot tube collectors (20), which are also connected in
parallel. In this way, a process can be performed across a number of discs
(3) in parallel. Means for applying vibration (200) is also shown.
FIG. 6 shows two discs (3) coaxially mounted on a drive shaft (2) which
defines an axis of rotation (6). Each disc (3) has a central trough (13)
into which reactant (15) may be fed by feed means (4) before spilling onto
the surface (5) of each disc (3). A collector trough (21) is provided
about the periphery of each disc (3) so as to collect product (19) thrown
from the discs (3). An outlet from the upper collector trough (21) passes
through a pump or extruder (22) before leading to the trough (13) of the
lower disc (3) as feed means (4). This arrangement is suitable for use
with viscous reactants and products. Collector means 90 are also shown.
FIG. 7 shows a pair of planar rotating support elements (80, 81) coaxially
mounted on an axis of rotation (6). The facing surfaces (82, 83) of the
support elements (80, 81) are each provided with a plurality of concentric
circular walls (84, 85, 86, 87), with walls (84, 86) mounted on surface
(82) and walls (85, 87) mounted on surface (83). The walls (84, 85, 86,
87) are divergent with respect to the axis of rotation of their respective
support element (80, 81) and are positioned so that they mesh with each
other when the support elements (80, 81) are brought together as shown.
Reactant (15) is supplied to an interior region of wall (84) near surface
(82) by a feed (4), and then proceeds to travel along an interior surface
of wall (84) towards surface (83). When the reactant (15) reaches the top
of wall (84), it spills over onto an interior surface of wall (85) on
support element (81) and travels back towards support element (80) as
shown. This process is repeated until the reactant (15) is thrown from the
top of the outermost wall (87) into collecting means (not shown). By
providing a convoluted surface along which the reactant (15) may travel, a
very compact reactor may be obtained. The support elements (80, 81) may
co- or counter-rotate, either at the same or at different rotational
speeds.
FIG. 8 shows a spinning disc (3) with a surface (5) mounted on a drive
shaft (2) inside a vessel (1) and provided with a feed (4) for a liquid
phase reactant, such as an organic prepolymer. A rotary impeller (70) is
mounted coaxially with the disc (3) and close to the surface (5), and a
surface (71) of the impeller (70) facing the surface (5) is provided with
vanes (72). A gaseous phase reactant, such as nitrogen, is supplied to the
vessel (1) through an inlet (10). Upon rotation of the disc (3), the
liquid phase reactant moves from the centre of the surface (5) towards the
periphery thereof as described above. When the impeller (70) is
appropriately rotated on a drive shaft (74), the gaseous phase reactant is
sucked into the space (73) between the impeller (70) and the surface (5)
and moves towards the centre of the surface (5) against the flow of liquid
phase reactant, thereby improving mass and/or heat transfer
characteristics. Gaseous phase reactant and unwanted reaction by-products
may be removed from the central region of the space (73) by way of a
discharge pipe (75) to which at least a partial vacuum may be applied. A
partial seal (76) in the discharge pipe (75) may be provided so as to
control the rate of gaseous phase reactant and by-product removal.
EXAMPLE 1
Polymerisation of Ethylene Using a Catalyst Coated Disc
Phillips catalyst was coated onto the surface of a spinning disc apparatus
using methods as described hereinbefore. The coated disc was mounted in a
spinning disc apparatus.
The spinning disc apparatus used is shown in diagrammatic form in FIG. 1.
The main components of interest being:
i) Top Disc--A smooth brass disc of thickness 17 mm and diameter 500 mm
capable of rotating around a vertical axis.
ii) Liquid Distributor--A circular copper pipe of diameter 100 mm,
positioned concentrically over the disc, sprayed fluid vertically onto the
disc surface from 50 uniformly spaced holes in the underside. Flowrate was
controlled manually by a valve and monitored using a metric 18 size,
stainless steel float rotameter. A typical fluid flow rate was 31.3 cc/s.
iii) Motor--A variable speed d.c. motor capable of rotating at 3000 rpm was
used. The rotational speed was varied using a digital controller
calibrated for disc speeds between 0 and 1000 rpm. A typical rotational
speed was 50 rpm.
iv) Radiant Heaters--3 radiant heaters (each consisting of two elements)
spaced equally below the disc provided heat to the disc. The temperature
was varied using a temperature controller for each heater. Each heater
temperature could be controlled up to 400.degree. C. Triac regulators were
used to control the speed of the controller response. (These remained on
setting 10 throughout the tests).
v) Thermocouples and Datascanner--16 K-type thermocouples embedded in the
top disc gave an indication of the surface temperature profile along the
disc radius. Odd numbered thermocouples 1 to 15 inclusive were embedded
from underneath the disc to a distance 3 mm from the upper disc surface.
Even numbered thermocouples, 2 to 16 inclusive were embedded from
underneath the disc to a distance 10 mm from the upper disc surface. Each
pair of thermocouple, i.e. 1 & 2 and 3 & 4 and 5 & 6 etc., were embedded
adjacently at radial distances of 85 mm, 95 mm, 110 mm, 128 mm, 150 mm,
175 mm, 205 mm and 245 mm respectively (see FIG. 3). The thermocouples
were connected to the datascanner which transmitted and logged the data to
the PC at set intervals using the DALITE Configuration and Monitoring
Software Package.
vi) Manual Thermocouple--A hand-held K-type thermocouple was used to
measure the bulk fluid temperature on top of the disc.
The rig was used in two arrangements. In one arrangement, feed was
constantly added and the heated product was sent to the collection trough.
In an alternative arrangement the rig was assembled with a recycle.
The spinning disc apparatus of FIG. 1 was started up and temperature and
rotational speed adjusted. When steady stage was achieved gaseous ethylene
was fed to the revolving catalyst coated disc surface at it axis. Product
was withdrawn in the collection trough at the periphery of the disc.
Analysis revealed the product was high grade polyethylene.
Further advantages of the invention are apparent from the foregoing.
*
