Liquid purification or separation – Processes – Separating
Reexamination Certificate
2000-07-12
2002-07-30
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S787000, C210S188000, C210S512100, C210S512300, C209S713000, C209S715000, C209S725000, C209S730000, C494S037000, C494S045000, C055S459100
Reexamination Certificate
active
06426010
ABSTRACT:
The invention relates to a device for separating the components of a heterogeneous mixture and its uses.
In many industrial applications, we can be brought to separate at least two non miscible fluids, for example a gas and a liquid, two non miscible liquids or the phases of a ternary mixture made up of two liquids and a gas. Furthermore, often times the initial mixture contains solid particles we would prefer to introduce in one or the other of the separated fluids.
To perform this operation, several known procedures are used, among which are the following:
gravity separators. These are rather large devices in which the emulsion's residence time is of several tens of seconds. The corresponding technology is known and is part of the engineer's art. In particular, decanters equipped with internal parallel plates are used;
centrifuges. These are devices driven by a motor in which the heavy phases are centrifuged and the light phases are centripeted under the action of a rotating field of flow. The tangential velocity of the fluid in the device is proportional to the radius, which limits its efficiency.
cyclones. These are stationary devices in which the mixture is introduced around the circumference of the device tangentially to the wall farthest from the axis. This creates a flow whose tangential velocity increases as we get closer to the center of the device, or at least to the output ports. These output ports are located close to the axis of the device and the liquid passes through them following an overall axial direction. The efficiency of these devices is relatively good and they are mostly used to obtain the separation of solids and liquids, the sorting of particles based on their sizes or a liquid-liquid separation. Nevertheless, these cyclones do have certain disadvantages due to the friction of the fluid against the walls. This results in the creation of a strong internal turbulence which tends to remix the species, brake the rotation and produce significant losses of charges.
Furthermore, in a liquid-liquid separation, these traditional cyclones can only operate if their size is small, typically less than 80 mm in diameter. Therefore, it is essential they be placed side by side if we wish to have significant flows pass through. This is very limiting when we are for example trying to perform a water-oil separation at the bottom of an oil well;
the rotating separator with a longitudinal peripheral feed. This is a separator whose walls rotate around an axis like those of a centrifuge, where the separation takes place in a cylindrical chamber, and the feed of said chamber follows an axial direction through canals parallel to the rotation axis located around the circumference of the cylindrical chamber, and the separated fluid exits through cylindrical ports pierced at the extremities of the rotating chamber. Such a separator is described in the French patent number 2 592 324 filed on Jan. 2, 1986 whose inventors are Y. Lecoffre and J. Woillez. They make it possible to execute an entry in the rotating mark following an axial direction so that in the absolute mark, the fluid enters with a rotation velocity almost exactly equal to that of the cylindrical chamber. This makes it possible to strongly limit the tangential friction on the walls of the chamber. We then obtain a field of velocities in the Vortex type chamber in which the tangential velocity is inversely proportional to the radius. Therefore it increases rapidly as we get closer to the center of the device, which results in spectacularly increasing the radial migration velocities of the globules to be separated.
The device performs a very efficient separation despite the fact that the residence times are close to one second. Therefore it is particularly compact. Furthermore, and this is one of the most significant characteristics, it can operate in a wide range of flows of the entry mixture, whose ratio between the extreme flows is greater than 20. In its current versions of separation of two non miscible liquids, this separator has the following disadvantages:
the separated light liquid always contains a significant and often predominant quantity of heavy liquid;
the losses of charges on the heavy liquid are relatively significant;
the losses of charge on the light liquid are practically double the losses of charge on the heavy liquid. Thus, in certain cases, we reach losses of charge of approximately ten bars;
the device only treats mixtures that contain a small quantity of light liquid, typically in the 1 to 3% range;
the device is driven via a motor placed laterally and a belt, which strongly increases its lateral congestion and prohibits its use in pipes with small diameters, as is the case in the oil industry.
The American patent number 3 405 803 relates to a vortex separator for the clarification of a suspension that contains particles. This separator has a vortex chamber
1
with a tapered lower part, the evacuation of the clarified suspension takes place on the same side as the introduction of the suspension to be clarified. Only the heavy particles are eliminated through the extremity
3
of the vortex chamber
1
on the side opposite that of the introduction of the suspension to be clarified.
Such a separator, if it makes possible the clarification of a suspension that contains particles, does not however perform a real separation of the components of the suspension.
The application for the European patent published under number 37 347 proposes a procedure and a device for separating the particles in a fluid. The procedure requires that the suspension to be treated be introduced following a direction that is slightly oblique in relation to the longitudinal axis of the enclosure, so that is has an initial angular velocity that is greater than the angular velocity of the enclosure. The device (
FIGS. 1
,
5
,
7
8
,
9
) consists of a tapered revolution enclosure
1
that rotates around its axis, an outlet
12
,
13
of the purified suspension and the separated fractions located at the extremity opposite that of the enclosure where the inlet
8
of the suspension is located, where the outlet
12
of the heaviest fraction is located around the circumference of the enclosure, meaning that its outside diameter is equal to the inside diameter of the enclosure
1
. Furthermore, this outside diameter of the outlet
12
is even often increased by an enlargement of the enclosure at the level of this outlet
12
, as can be seen in
FIGS. 1
,
5
and
7
. These arrangements prevent the development of a cyclonic effect necessary to obtain a good separation. Furthermore, the device proposed in this application for European patent calls for an auxiliary fluid, it must have large dimensions and it operates with a low average centrifugal acceleration and a long residence time.
The object of this invention is to remedy the afore-mentioned disadvantages. Therefore it relates just as well to rotary separators with a peripheral feed as it does to stationary separators provided they operate with unusual characteristics. Therefore this invention intends to answer the following needs:
limit the losses of charge:
be able to integrate the separator in pipes with small diameters and especially an oil production well pipe;
make it possible to separate the fluids contained in liquid-liquid mixtures rich in one or the other of the components;
be able to integrate the separator to a pump shaft line in the case of a rotary separator;
be able to separate solids;
reinject the separated solids in one or the other of the liquid phases;
separate gases;
perform a separation of gases, then of the liquids and the solids in an integrated device;
integrate a finish separator on one or the other of the liquids to be separated;
implement means for regulating the flows of liquid;
implement arrangements that make it possible to limit the fluctuations of concentration at the inlet of the separator;
implement arrangements that make it possible to optimize the feeding conditions of the device.
In the existing devices, the output of the less d
Gay Jean-Claude
Lecoffre Yves
Reifsnyder David A.
Total
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