This document relates to a centrifugal separation apparatus, and more particularly to a centrifugal separation apparatus for separating fluids having different specific gravities.
Many oil wells may produce an effluent containing oil, water and gas components. For many years, the fluids and other well effluent produced from a well have been passed through dewatering tanks to separate the gas, oil and water components of the effluent. Such tanks are typically provided with baffles and compartments through which the well effluent is passed. Oil with a typical density of 0.75 to 0.85 being lighter than water with a density of 1.0, is expected to rise to the top of the effluent and be drawn off from a compartment to which the upper part of the effluent is permitted to pass, while the denser water may be drawn off from the bottom portion of the tank.
Centrifugal separation apparatuses for performing oil and water separation by centripetal force are known in the art. In particular, a centrifugal separation apparatus may include a stationary housing in which is centrally disposed for rotation therein a central chamber assembly. The central chamber assembly may include an upper chamber adapted to separate oil from the effluent and a lower chamber for the storage of water separated from the effluent. In one embodiment, the centrifugal separation apparatus may include plurality of U-tube assemblies that extend outwardly in a radial direction from the central chamber assembly that communicate through one of a plurality of tubular return sections that collectively define an outer tube that surrounds the central chamber assembly. A motive force is provided that rotates the central chamber assembly and the U-tube assemblies about a central vertical axis that applies an artificial gravity to the effluent entering the centrifugal separation apparatus in order to separate the oil and water components of the effluent by use of centripetal force. This centripetal force can apply a great amount of stress to the U-tube assemblies, especially along the joints where each U-tube assembly engages the central chamber assembly.
As noted above, operation of the centrifugal separation apparatus rotates the central chamber assembly at a fast rate of speed to generate the artificial gravity necessary to separate liquids having different specific gravities. As such, the centripetal force applied to the effluent that enters the central chamber assembly will begin to separate the lighter oil from the heavier water; however, if the amount of effluent and its component water or oil in the U-tube assemblies or the outer tube is not spread generally even among these components, the rotational forces generated by the centrifugal separation apparatus can cause the apparatus to excessively vibrate due to the unbalanced load of the effluent and its components. In some instances, this unbalanced state of the effluent and the excessive vibrations imparted to the structural elements of the centrifugal separation apparatus can cause the catastrophic failure of the apparatus as the U-tube assemblies and outer tube break apart.
As such, there is a need in the art for a centrifugal separation apparatus that prevents centripetal forces applied to the U-tube assemblies and related components from applying excessive force to the U-tube assemblies. There is also a need in the art for a mechanism that prevents the catastrophic failure of the centrifugal separation apparatus due to an unbalanced load of effluent in the apparatus that may cause the apparatus to excessively vibrate.
In an embodiment, a centrifugal separation apparatus is provided for separating oil and water from a stream of fluid whose components include oil and water. The apparatus may include a hollow vessel having an inlet tube through which the stream of fluid may enter the vessel. A rotatable chamber assembly is centrally disposed in the vessel for rotation about a vertical axis wherein the rotatable chamber assembly includes an upper chamber and a lower chamber for the collection of separated oil. The upper chamber is in fluid communication with the inlet tube to receive the stream of fluid therefrom and one or more nipples that extend a predetermined distance into the upper chamber for collecting oil separated from the stream of fluid. In addition, the apparatus may further include one or more U-tube assemblies that extend outwardly from the rotatable chamber assembly in a radial direction with each U-tube assembly having at least one upper tube and at least one lower tube in fluid flow communication with a connecting outer tube.
A strain retaining plate may be engaged to the outer tube and said chamber assembly for providing structural support to the plurality of U-tube assemblies. A rotatable main shaft is in operative engagement with the rotatable chamber assembly for rotating the chamber assembly about the vertical axis at a predetermined speed in which the stream of fluid entering the upper chamber is subjected to centripetal forces which in combination with gravitational forces cause oil and water in the stream of fluid to separate into different components. During operation of the apparatus, the separated water passes through at least one upper tube, the connecting outer tube, and at least one lower tube for collection in the lower chamber such that water may exit through a water outlet tube in communication with the lower chamber. Simultaneously, the separated oil may flow through the upper tubes to the outer tube and back the upper tube such that the separated oil exits the upper chamber through one or more of the nipples.
In another embodiment, a centrifugal separation apparatus for separation oil and water from a stream of fluid whose components include oil and water may include a hollow vessel having an inlet tube through which the stream of fluid may enter the vessel. A rotatable chamber assembly is centrally disposed in the vessel for rotation about a vertical axis with the chamber assembly defining an upper chamber in communication with the inlet tube for receiving the stream of fluid and a lower chamber for the storage of water separated from the stream of fluid. The centrifugal separation apparatus may further include one or more U-tube assemblies with each of the one or more U-tube assemblies having a proximal end that extends outwardly in a radial direction from the chamber assembly and a distal end that is engaged and in communication with an outer tube. A main shaft is operatively engaged to the rotatable chamber assembly for rotating the chamber assembly at a predetermined speed about the vertical axis in which the stream of fluid entering the chamber assembly is subjected to centripetal which in combination with gravitational forces cause oil and water in the stream of fluid to separate. Finally, a strain retaining plate is engaged to the outer tube and the chamber assembly for providing structural support to the one or more U-tube assemblies.
In yet another embodiment, a centrifugal separation apparatus for separating oil and water from a stream of fluid whose components include oil and water may include a hollow vessel having an inlet tube through which the stream of fluid may enter the vessel. A rotatable chamber assembly is centrally disposed in the vessel for rotation about a vertical axis with the chamber assembly defining an upper chamber in communication with the inlet tube for receiving the stream of fluid and a lower chamber for the storage of water separated from the stream of fluid. The centrifugal separation apparatus may include one or more U-tube assemblies with each of the one or more U-tube assemblies having a proximal end that extends outwardly in a radial direction from the chamber assembly and a distal end that is engaged and in communication with an outer tube. A main shaft is operatively engaged to the rotatable chamber assembly for rotating the chamber assembly at a predetermined speed about the vertical axis in which the stream of fluid entering the chamber assembly is subjected to centripetal forces which in combination with gravitational forces cause oil and water in the stream of fluid to separate. A motor is in operative engagement with the main shaft for rotating the chamber assembly with the motor being in operative association with a microprocessor controller for controlling the operation of the motor. Finally, the centrifugal separation apparatus may include a means for detecting the degree of vibrations generated by the apparatus with the means for detecting the degree of vibrations generated by the apparatus being in operative association with the microprocessor controller for terminating the operation of the centrifugal separation apparatus when the degree of vibrations exceeds a predetermined value.
Additional objectives, advantages and novel features will be set forth in the description which follows or will become apparent to those skilled in the art upon examination of the drawings and detailed description which follows.
Corresponding reference characters indicate corresponding elements among the view of the drawings. The headings used in the figures should not be interpreted to limit the scope of the claims.
Referring to the drawings, an embodiment of the centrifugal separation apparatus is illustrated and generally indicated as 10 in
The rotatable main shaft 14 defines an upper shaft portion 16 that rotates the chamber assembly 20 and a lower shaft portion 18 that freely rotates within a cartridge 22 that surrounds the lower shaft portion 18 and extends through a central opening 53 defined in the lower end of vessel 12 for operative engagement with a motor 41. The part of the lower shaft portion 18 below the vessel 12 defines a distal portion 56 having a shaft pulley 60 that is operatively engaged to a motor pulley 62 of motor 41 by a belt 66 (shown in phantom). The motor 41 includes a motor shaft 64 that drives the motor pulley 62 when the motor 41 is made operational such that the belt 66 rotates the main shaft 14. As such, rotation of the main shaft 14 concurrently rotates the chamber assembly 20 in order to generate centripetal forces that will separate the oil 7 and water 9 from the effluent 6. As shown in
Referring to
Referring to
As shown in
As further shown in
The embodiment of the centrifugal separation apparatus 10 shown in
Also projecting outwardly in a radial direction from the chamber assembly 20 are the oil outlet tubes 44 and water outlet tubes 46 that discharge oil 7 and water 9 to the inner and intermediate compartments 24 and 26, respectively. Each of the oil outlet tubes 44 communicates with the upper chamber 32 through a respective nipple 52, while each of the water outlet tubes 46 communicates directly with the lower chamber 34. In one embodiment, both the oil outlet tubes 44 and water outlet tubes 46 may be bent downwardly so that the oil outlet 68 (shown in phantom) defined at the free end of each oil outlet tube 44 and the water outlet 70 (shown in phantom) defined at the free end of each water outlet tube 46 communicate directly with the intermediate compartment 26 and inner compartment 24, respectively.
To collect the water 9, oil 7 and resultant debris, referred to as sluff 8 entrained in the effluent 6, the vessel 12 defines various compartments. As noted above, the vessel 12 defines an inner compartment 24 that surrounds the cartridge 22 for collecting separated water 9. In addition, the vessel 12 includes an intermediate compartment 26 adapted for collecting separated oil 7 and an outer compartment 28 adapted for collecting the sluff 8 that contains debris, sediment, and other by-product material produced by the operation of the centrifugal separation apparatus 10. The vessel 12 further includes an oil discharge outlet 126 in communication with the intermediate compartment 26 for permitting the collected oil 9 to be transported to a storage site (not shown) outside of vessel 12. Similarly, a water discharge outlet 128 is in communication with the inner chamber 24 for allowing collected water 7 to be transported to another storage site (not shown).
As shown in
In one embodiment, the oil and water outlet tubes 44 and 46 as well as the U-tube assemblies 36 and outer tube 38 may be structurally supported by a strain retaining plate 48. The strain retaining plate 48 prevents centripetal forces generated by the rotation of the main shaft 14 from applying excessive strain to the U-tube assemblies 36, especially the joints of the U-tube assemblies 36 that engage the chamber assembly 20 at one end and the outer tube 38 at the opposite end thereof. In addition, the strain retaining plate 48 may be secured directly to the oil and water outlet tubes 44 and 46 and indirectly to the outer tube 38 as discussed below.
Referring to
To understand the operation of the centrifugal separation apparatus 10 shown in
L
0
×Q
0
×Lw×qw×Xg=L2×qw×g
Lw=L2×qw−L1×q0/dq
L2/L1=q0/qw
This shows that the ratio of the lengths of the upper oil separation tubes 40 and the lower separation tube 42 determines the maximum ratio of liquid densities that can be separated by the centrifugal separation apparatus 10. For example, If L1 is 16 inches and L2 is 15 inches, then L2 over L1=0.9375, showing that with such tube lengths oil with a density of 0.9375 or less can be separated from water having a density of 1.0. Accordingly, if oil and water flow into the upper end of the left hand column, as illustrated in
It should be noted that either one of the situations illustrated in
Referring to
As noted above, when the effluent 6 flows into the distribution cone 50 the effluent 6 is radially distributed through lower part of the upper chamber 32. As effluent 6 is rotated inside the upper chamber 32 by rotation of the main shaft 14, the effluent 6 will begin to flow through each pair of upper oil separation tubes 40 of the U-tube assembly 36 and into the tubular return section 47. However, due to gravity and the enhanced gravitational effect from the centrifugal forces generated by the centrifugal separation apparatus 10, the water 9 in the tubular return section 47 flows into the lower water separation tubes 42 for collection in the lower chamber 34, while the oil 7 returning through the upper oil separation tubes 40. As water 9 flowing from the lower water separation tubes 42 accumulates in the lower chamber 34, the water 9 overflows into the water outlet tubes 46 and into the inner chamber 24.
In contrast, the oil 7 in the effluent 6 will separate from the water 9 and tend to rise and flow back through the pair of upper oil separation tubes 40 as illustrated by U-tube assembly 36A (
Due to the centripetal forces generated by the centrifugal separation apparatus 10, there is a tendency for any sluff 8 in the effluent 6 to accumulate in the tubular return sections 47 of the outer tube 38. In one embodiment, the outer tube 38 may define apertures (not shown) sealed with plugs (not shown) that may be opened to allow water to be introduced into the outer tube 38 to flush out the sediment 8 into the outer chamber 28.
Referring back to
It should be understood from the foregoing that, while particular embodiments have been illustrated and described, various modifications can be made thereto without departing from the spirit and scope of the invention as will be apparent to those skilled in the art. Such changes and modifications are within the scope and teachings of this invention as defined in the claims appended hereto.