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Claims  |
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I claim:
1. A desilter for drilling muds comprising a common inlet manifold conduit
and a plurality of hydrocyclone separators arranged in two parallel rows
in series along said conduit and connected thereto,
each of said hydrocyclone separators comprising a hollow, enclosed vessel,
having an upper, large casing portion with a tangential side inlet opening
and conduit extending therefrom and an outlet conduit extending out
through the upper wall thereof, and a lower casing portion tapering
downwardly from said upper casing portion and defining a downwardly
extending conical chamber having a bottom outlet for discharge of
separated materials therefrom,
supporting means for said separators,
said inlet manifold conduit being supported on said supporting means and
having a plurality of conduit means positioned serially thereon connecting
the same to respective tangential inlet conduits on said separators,
at least one collection trough open to atmosphere at the top and positioned
below said separators to receive the discharge of material from the bottom
outlets therefrom, and
individual syphon conduits for each of said outlet conduits having outlet
ends discharging separately to a collection point at atmospheric pressure.
2. A desilter according to claim 1 in which
said separators are supported in a line in decreasing elevation,
said inlet manifold conduit is supported on a slope substantially the same
as said separators, and
said collection trough is supported on a slope substantially the same as
said separators and with the bottom ends of said separators extending into
the upper top portion thereof.
3. A desilter according to claim 2 in which
said supporting means is a rectangular open frame, and
said syphon conduits are positioned with the outlet ends thereof extending
inside the open central portion of said frame and terminating just below
the upper edge thereof.
4. A desilter according to claim 1 in which
said syphon conduits each have effective syphon lengths predetermined for
optimum separation efficiency.
5. A desilter for drilling muds comprising
a plurality of hydrocyclone separators,
each of said hydrocyclone separators comprising a hollow, enclosed vessel,
having an upper, large casing portion with a tangential side inlet opening
and conduit extending therefrom and an outlet conduit extending out
through the upper wall thereof, and a lower casing portion tapering
downwardly from said upper casing portion and defining a downwardly
extending conical chamber having a bottom outlet for discharge of
separated materials therefrom,
supporting means for said separators,
an inlet manifold conduit supported on said supporting means and having
conduit means connecting the same to respective tangential inlet conduits
on said separators,
at least one collection trough open to atmosphere at the top and positioned
below said separators to receive the discharge of material from the bottom
outlets therefrom,
individual syphon conduits for each of said outlet conduits having outlet
ends discharging separately to a collection point at atmospheric pressure,
and
said syphon conduits being separately adjustable in effective syphon length
for independent adjustment of said separators.
6. A desilter according to claim 5 in which
said syphon conduits include means to vary the effective syphon length
thereof.
7. A desilter according to claim 6 in which
said syphon conduit length-varying means comprises an adjustably movable
conduit having one end open to atmosphere and the other end positioned
movably inside said syphon conduit.
8. A desilter according to claim 7 in which
said syphon conduit comprises an elbow secured on said outlet conduit from
said separator and a straight, downwardly extending conduit extending
substantially below the outlet end of said separator,
said elbow having an opening aligned with said downwardly extending
conduit,
a conduit secured on said elbow at said opening and aligned with said
downwardly extending conduit,
a cap secured on said elbow conduit and having a centrally located opening,
and
said adjustably movable conduit being positioned with one end outside said
cap and extending therethrough and into said downwardly extending conduit
and movable longitudinally therein to vary the syphon length thereof.
9. A desilter for drilling muds comprising,
a plurality of hydrocyclone separators supported in a line in decreasing
elevation,
each of said hydrocyclone separators comprising a hollow, enclosed vessel,
having an upper, large casing portion with a tangential side inlet opening
and conduit extending therefrom and an outlet conduit extending out
through the upper wall thereof, and a lower casing portion tapering
downwardly from said upper casing portion and defining a downwardly
extending conical chamber having a bottom outlet for discharge of
separated materials therefrom,
supporting means for said separators,
an inlet manifold conduit supported on said supporting means on a slope
substantially the same as said separators and having conduit means
connecting the same to respective tangential inlet conduits on said
separators,
at least one collection trough open to atmosphere at the top and positioned
below said separators to receive the discharge of material from the bottom
outlets therefrom,
said collection trough being supported on a slope substantially the same as
said separators and with the bottom ends of said separators extending into
the upper top portion thereof,
individual syphon conduits for each of said outlet conduits having outlet
ends discharging separately to a collection point at atmospheric pressure,
and
said syphon conduits each having effective syphon lengths predetermined for
optimum separation efficiency.
10. A desilter according to claim 9 in which
said syphon conduits are separately adjustable in effective syphon length
for independent adjustment of said separators.
11. A desilter according to claim 10 in which
said syphon conduits include means to vary the effective syphon length
thereof.
12. A desilter according to claim 11 in which
said syphon conduit length-varying means comprises an adjustably movable
conduit having one end open to atmosphere and the other end positioned
movably inside said syphon conduit.
13. A desilter according to claim 12 in which
said syphon conduit comprises an elbow secured on said outlet conduit from
said separator and a straight, downwardly extending conduit extending
substantially below the outlet end of said separator,
said elbow having an opening aligned with said downwardly extending
conduit,
a conduit secured on said elbow at said opening and aligned with said
downwardly extending conduit,
a cap secured on said elbow conduit and having a centrally located opening,
and
said adjustably movable conduit being positioned with one end outside said
cap and extending therethrough and into said downwardly extending conduit
and movable longitudinally therein to vary the syphon length thereof.
14. A hydrocyclone separator comprising,
a hollow elongated enclosed vessel,
said vessel having an upper large casing portion with a tangential side
opening and a centrally located top opening,
an inlet conduit connected to said upper casing portion at said tangential
inlet opening,
an overflow conduit extending concentrically of said upper casing portion
through said top opening and having one end open inside said upper casing
portion at a point below said tangential inlet opening and another end
extending outside said top opening.
a lower casing portion secured to said upper casing portion and tapering
downward therefrom to provide a downwardly extending conical chamber and
having a bottom opening for discharge of separated material therefrom, and
a syphon conduit, adjustable in effective syphon length, connected to and
secured on the outside end of said overflow conduit.
15. A hydrocyclone separator according to claim 14 in which
said syphon conduit includes means to adjust the syphon length thereof.
16. A hydrocyclone separator according to claim 15 in which
said syphon conduit length-varying means comprises an adjustably movable
conduit having one end open to atmosphere and the other end positioned
movably inside said syphon conduit.
17. A hydrocyclone separator according to claim 16 in which
said syphon conduit comprises an elbow secured on said outlet conduit from
said separator and a straight, downwardly extending conduit extending
substantially below the outlet end of said separator,
said elbow having an opening aligned with said downwardly extending
conduit,
a conduit secured on said elbow at said opening and aligned with said
downwardly extending conduit,
a cap secured on said elbow conduit and having a centrally located opening,
and
said adjustably movable conduit being positioned with one end outside said
cap and extending therethrough and into said downwardly extending conduit
and movable longitudinally therein to vary the syphon length thereof. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to new and useful improvements in desilters for
drilling muds and more particularly to improve hydrocyclones for
separating large particles from drilling muds.
2. Brief Description of the Prior Art
Desilting of drilling muds is a necessary step in the preparation of
satisfactory muds for the drilling of oil and gas wells. Desilting
consists of removing coarse or large particles from a drilling mud so that
the remainder of the mud is of a more uniform particle size. The need for
desilting and some of the methods of desilting are set forth in papers by
George S. Ormsby entitled, "How Proper Desilting Helps in Unweighted Mud
Drilling", and "Correction of Common Errors in Drilled Solids Removal
Systems."
Desilting, or removal of coarse or large size particles, of drilling muds
is commonly accomplished by the use of hydrocyclone separators. Some basic
theory on design and operation of hydrocyclones is set forth in "Theory,
Applications and Practical Operation of Hydrocyclones", Trawinski,
E-MJ-September, 1976; and "Solid-Liquid/Liquid-Liquid Separation
Equipment--Centrifuges, Cyclones, Settlers", paper presented at the
National AICHE Meeting/Petrochemical and Refining Exposition, Houston,
Tex.--Mar. 1-4, 1971.
Several U.S. patents disclose hydrocyclone separators having certain
controlled features.
Trawinski, U.S. Pat. No. 3,817,388, discloses hydrocyclone separators
having valves controlling the input to the hydrocyclones from a central
reservoir and having separate collection systems for the overflow and
underflow from the separator.
Zemanek, U.S. Pat. No. 3,764,005, discloses a hydrocyclone separator for
pulp in which there are provided valves controlling the input flow and the
overflow and a valve controlling the introduction of air into the outlet
zone from the separator.
Carr, U.S. Pat. No. 3,568,847, discloses a hydrocyclone separator having an
inflatable restriction in the overflow line to control the overflow from
the hydrocyclone.
SUMMARY OF THE INVENTION
One of the objects of this invention is to provide a new and improved
hydrocyclone apparatus for desilting drilling muds.
Another object of this invention is to provide an improved hydrocyclone
desilter for drilling muds having substantially improved separation
efficiency for removal of large or coarse particles from such drilling
muds.
Still another object of this invention is to provide an improved drilling
mud desilter hydrocyclone having an improved controllable overflow which
improves substantially separation efficiency.
Still another object of this invention is to provide a new and improved
drilling mud desilter hydrocyclone having a controllable syphon effect in
the overflow line.
Still another object of this invention is to provide an improved drilling
mud desilter apparatus, including a plurality of hydrocyclones
interconnected by an inlet manifold and having underflow and overflow
outlets discharging into separate open collector systems.
Other objects of this invention will become apparent from time to time
throughout the specification and the claims as hereinafter related.
An improved desilter for drilling muds, carrying out the above objectives,
consists of one or more hydrocyclones with certain features providing for
the better separation of large particles from the mud. Drilling muds used
in drilling oil wells and the like give substantially improved performance
when the larger or coarser particles are removed therefrom and the mud
consists of fine particles having a narrow range of particle size.
An improved hydrocyclone for removing coarser or larger particles from the
drilling mud has overflow and underflow outlets which discharge openly
rather than into collection manifolds. The overflow outlet is in the form
of a controllable syphon which may be adjusted in size and length or which
may include means to adjust the effective length of the syphon leg. The
adjustment of the syphon leg controls the overflow of the thin, more
uniform mud and effects a superior separation of the larger particles from
the mud.
A third desilter apparatus comprises a plurality of hydrocyclones, as
described, interconnected by an inlet manifold and having an underflow and
overflow outlets, respectively, for discharge of large or coarse particles
and of a thin mud of uniform small particle size to separate open
collection systems.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in side elevation of a bank of hydrocyclones comprising a
desilter apparatus which is a preferred embodiment of this invention.
FIG. 2 is a plan view of the desilter apparatus shown in FIG. 1.
FIG. 3 is a view in left elevation of the desilter apparatus shown in FIG.
1.
FIG. 4 is a view in right elevation of the desilter apparatus shown in FIG.
1.
FIG. 5 is an isometric, detail view of one of the hydrocyclones
illustrating the flow of materials.
FIG. 6 is a detail view, partially in section, of the adjustable syphon on
the overflow line from the various hydrocyclones.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the drawing, there is shown a desilter apparatus for desilting drilling
muds which is a preferred embodiment of this invention and which
represents the best mode known to applicant for carrying out the
invention. The apparatus consists of a plurality of hydrocyclone
separators, of novel design, which are interconnected to provide a highly
efficient separation of large or coarse particles from a drilling mud. In
the drawing, there is shown a bank of twelve hydrocyclone separators, six
on each side of a common feed manifold. The apparatus will function with
one or more of the novel hydrocyclone separators and the particular number
selected for use in the apparatus is a matter of choice or design
depending upon the design requirements for the mud system where the
desilter is to be used.
In FIGS. 1-4 it is seen that the desilter apparatus has a supporting skid 1
comprising elongated support members 2 and 3, which are shown as channel
irons, although any suitable support, such as an I beam or H beam or angle
iron could be used. Lateral support members 4 and 5 are secured to between
supports 2 and 3. These support members are channels or I beams or H beams
or angle irons and are welded to channels 2 and 3 to provide a rigid
supporting skid. The ends of channel iron 2 are cut out as indicated at 6
and 7. The ends of channel iron 3 are cut out as indicated at 8 and 9. At
the left end of supporting skid 1, a supporting rod 10 extends between
channel iron 2 and 3 and has end flanges 11 and 12. At the right end of
supporting skid 1, supporting rod 13 extends between channel irons 2 and 3
and has end flanges 14 and 15. The supporting skid is designed so that it
can be easily picked up by cables or the like secured to rods 10 and 13 or
by any other suitable lifting or transporting equipment.
Skid 1 is provided with a pair of diagonally extending braces 16 and 17
secured at their lower ends to supports 2 and 3, respectively, and at
their upper ends to support member 18.
At the other end of Skid 1, diagonal braces 19 and 20 are secured at their
lower ends to support members 2 and 3, respectively, and at their upper
ends to support member 21. Support members 18 and 21 are semi-cylindrical
in shape and support tubular manifold 22. Manifold 22 is secured on
support members 18 and 21 against movement, by spot or pack welding or the
like.
Support members 16 and 17 have supporting plate members 23 and 24 secured
thereon as by welding or the like. Support members 19 and 20 have
supporting plate members 25 and 26, respectively, secured thereon as by
welding. An open top trough member 27 is supported on plate members 23 and
25 and secured thereto by welding. Trough member 27 is open at the top and
at the bottom, discharge end, and has a wall member 28 closing the upper
end thereof. A second trough member 29 is supported on plate members 24
and 26 and secured thereon by welding. The top of trough member 29 and the
bottom or discharge end thereof are open. The upper end of trough member
29 is closed by an end wall or plate member 30.
Inlet manifold 22 has a flanged closure 31 at its lower end and an open
flanged end 32 at its upper end for connection to a pump circulating mud
from which larger or coarser particles are to be removed. Manifold 22 is
provided with a plurality of side conduits 33-44, inclusive, which support
a plurality of hydrocyclone separators which will be described more fully
hereinafter. Side conduits 33-44 terminate in snap joints 45-56 which
support one side of control valves 57-68, said valves having control
handles 69-80, respectively. The other side of control valves 57-68 is
connected by snap joints 81-92, respectively, to the inlet side of
hydrocyclones 93-104.
The several hydrocyclones 93-104 are identical in construction and are
given the same reference numerals for the various component parts thereof.
If it is necessary to refer to a particular part of one of the
hydrocyclones, it will be identified in terms of the particular
hydrocyclone in which it is located. Detailed description of the
hydrocyclones will be given with reference to hydrocyclone 104, with the
understanding that the other hydrocyclones are constructed and operate in
the same manner. Hydrocyclone 104 comprises bottom portion 105 having
conically tapered side wall terminating in bottom outlet opening 106.
Hydrocyclone 104 has a top or cover portion 107 having a tangential inlet
conduit 108 connected to snap joing 92 on control valve 68. Cover member
107 has outlet tube 109 extending outside thereof and also extending
concentrically inside to a point at or just below the level of tangential
inlet conduit 108. Outlet or overflow tube 109 is connected to snap join
110 which in turn is connected to syphon tube generally designated 111.
Syphon tube 111 includes U-shaped portion 112 and downcomer 113. U tube 112
has an opening 114 aligned substantially concentrically with downcomer leg
113. Vertically extending tube 115 extends upward from opening 114 and is
welded to U tube 112 as indicated at 116. Tube 115 is provided with a
cover member 117 threaded thereon as indicated at 118 and having a central
opening 119. At the upper end of tube 115, and positioned inside cover
member 117, is a washer 120 having a central opening 121. Hollow tubing
member 122 extends through opening 119 and cover member 117, central hole
121 in washer 120, opening 114 in U tube 112, and concentrically down a
substantial portion of the length of downcomer tube 113. Tubing member 122
is of sufficient length to extend to the bottom of downcomer leg 113,
which preferably terminates just below the upper edge of the supporting
members of supporting skid 1. The tubing member 122 is adjustable
vertically to vary the syphon effect is downcomer leg 113 and, thus,
optimize the separation of homogeneous drilling mud from coarse or leg
particles separated in the hydrocyclone.
The several hydrocyclones 93-104 are positioned with their lower outlet
ends 106 extending into collection troughs 27 and 29, respectively. The
several downcomer legs 113, which are the overflow outlet tubes from the
hydrocyclones are positioned to discharge into the open space at the
central portion of supporting skid 1.
The hydrocyclones 93-104 are secured on conduits 33-44 from manifold tubing
or conduit 22. The overflow or downcomer tubes 111 are secured against
undesired movement or displacement by a frame consisting of angle irons
123 and 124 extending longitudinally of the apparatus and angle irons 125
and 126 extending laterally thereof. The frame is secured together by
welding of the angle irons at the four corners thereof. Angle irons 125
and 126 are spot welded to inlet manifold tube 22 as indicated at 127 and
128. Overflow tubes 111 for hydrocyclones 93-98 are welded to supporting
frame member 123 as indicated at 129. Overflow tubes 111 from
hydrocyclones 99-104 are welded to frame member 124 as indicated at 130.
The desilter apparatus operates on a drilling mud introduced into inlet
manifold conduit 22 and is separated by action of the individual
hydrocyclones 93-104. The underflow from the individual hydrocyclones
discharges into troughs 27 and 29 for removal of coarse material. The
homogeneous mud, with coarse particles removed, therefrom, is discharged
overhead through overflow conduits 111 into a mud pit or other receptacle,
not shown, located below supporting skid 1.
OPERATION
The operation of this apparatus should be generally apparent from the
description of construction and assembly thereof. It is necessary,
however, for a more thorough understanding of the invention to have a more
complete description of operation and, to some extent, an explanation of
the theory of hydrocyclone separation.
In oil and gas well drilling, drilling muds are used, and the preparation
and treatment of drilling muds has become a major industrial effort. In
the use and reuse of drilling mud, it is necessary to maintain a mud
composition which is relatively homogeneous. The removal of coarse or
large particles from drilling mud is referred to as desilting. Desilted
muds are muds which have large or coarse particles removed therefrom so
that the mud is formed of clay solids which are fine particles size and
relatively uniform in size distribution. A desilted mud is not a low
solids mud and may not be produced by mere dilution of a mud which is too
thick or has too high solids content. Coarser solids are removed from a
drilling mud in a desilting operation to give a more homogeneous and more
easily handled mud which is needed for a variety of purposes.
The separation of coarse or large particles from a drilling mud may be
accomplished by a variety of separatory techniques. Separation of coarse
particles can be accomplished to a limited extent by use of a separation
basin wherein the particles merely settle out. A more efficient separation
may be accomplished in a rotary separator such as a centrifuge. A
hydrocyclone functions somewhat similarly to a centrifuge in that the feed
stock is rotated and the particles of larger size thrown to the outside by
centrifical force.
The operation of a hydrocyclone is shown, somewhat schematically in FIG. 5
of the drawing. A pressurized slurry, i.e., drilling mud, is introduced
through tangential inlet conduit 108. The slurry circulates around the
wall of the hydrocyclone and moves downward in a spiral pattern as
indicated by lines 132. As the slurry circulates around the conical wall
of the hydrocyclone separator and moves downward in a spiral path, it
rotates faster and faster as the diameter of the hydrocyclone tapers to a
smaller and smaller amount. During this centrifical movement, the coarser
solids in the slurry, i.e., drilling mud, are thrown outward by
centrifical force to the wall of the hydrocyclone separator and move
downward with the flow of fluid. At the bottom of the separator, the flow
of circulating fluid stops and begins to move upward inside the outer
rotating fluid as indicated by lines 133. At the point of reversal of
flow, where the fluid begins to flow upward, at the bottom of the
separator, the solids drop out and fall out through opening 106 into
collection trough 27 or 29. A fluid flowing upwardly through the center of
the separator in the path indicated by lines 133 is removed overhead
through outlet tube 109. It should be noted that the upward spiraling
vortex of mud freed from the coarser particles continues its spiral
movement up into the lower end of outlet tube 109. The desilted mud is
removed from outlet tube 109 through overflow tube 111 and discharged to a
mud pit or other container or reservoir. More details on the theory of
hydrocyclone operation may be found in the papers referred to in the
BACKGROUND OF THE INVENTION.
In the past, banks of hydrocyclone separators have been constructed for use
in drilling mud desilting and for other separatory purposes. Such banks of
separators have almost always had inlet manifold conduits providing a
common feed supply to the several hydrocyclone separators. In addition,
the overflow conduits and the underflow outlets from the several
hydrocyclone separators have been connected to separate closed discharge
manifold systems. This has been considered necessary for maximum
separation efficiency.
In the development of this invention, it was found that superior separation
efficiency is obtained in a bank of hydrocyclone separators by separating
the outlet discharge connections from any common enclosed manifold
collecting system. It has been found that if the underflow outlets
discharge into a collecting system separately, with the entire system
maintained open to the atmosphere and if the overflow outlet conduits
discharge separately at atmospheric pressure directly to a collection pit
or reservoir, a substantially improved separation efficiency is obtained.
This improvement in performance is believed to be due to the need for a
balanced pressure drop through individual ones of the hydrocyclone
separators which is not possible when they are connected with the inlet
and all of the outlets opening into enclosed collection or supply
manifolds. In addition, it has been found that a substantial improvement
in separation efficiency can be obtained by an adjustment of a syphon
effect in the overflow from the individual hydrocyclone separators.
In the preferred embodiment of this invention shown in the several
drawings, it should be noted that only the inlet flow is through an
enclosed manifold system. The underflow from the outlet ends 106 of the
several hydrocyclones discharges into open collection troughs so that the
discharge is to atmospheric pressure and not to a pressure defined by the
flow characteristics in an enclosed outlet connection manifold. Likewise,
the overflow conduits are arranged to discharge directly and independently
at atmospheric pressure to an open collection reservoir. Each of the
overflow tubes 111 is provided with an adjustable syphon controlling tube
122 which may be adjusted in position to set the syphon effect at the
desired level for each individual hydrocyclone separator to obtain maximum
separating efficiency. It has been found that the maximum separating
efficiency is obtained by varying the syphon effect in the outlet tubes
111 and establishing a pre-determined value for each of the several
hydrocyclones. This results in maintaining a pre-selected desired pressure
at the inlet end of outlet tube 109 which maintains the desired rate of
centrifical movement of the slurry in the hydrocyclone separator to effect
a maximum degree of separation of coarse or large particles. The
adjustment in syphon effect could be accomplished for any particular mud
composition by experimental determination of the desired amount of
syphon-induced suction and cutting off the downcomer conduit 113 for each
hydrocyclone separator to a predetermined length producing the desired
amount of suction. This would require a pre-selected length for the
downcomer conduits 113 for each of the separate hydrocyclones and would
optimize the separating efficiency for the particular mud composition used
in the apparatus. It is obvious, however, that a desilting apparatus is
likely to be used on mud compositions which vary substantially in
composition and texture. As a result, it is desirable to have some means
for independent variation or adjustment of the syphon effect in the
downcomer legs or conduits 113. This is accomplished by the independently
adjustable tubes 122 which can be adjusted to locate their lower ends at
any selected height within the downcomer leg or conduit 113. The tubes 122
are open at their upper ends to atmospheric pressure and their lower ends
determine the point at which the syphon effect breaks in the outlet or
downcomer tubes 113. This independent adjustment of the syhon effect in
the overflow from the individual hydrocyclones makes it possible to
maximize the separation efficiency of the hydrocyclones. It has been found
in the past that banks of hydrocyclone separators used in drilling mud
desilting operate at only a 15-25% efficiency. This apparatus, constructed
and operated as described, is operated at separation efficiencies of the
order of 50-75%.
While this invention has been described fully and completely with special
emphasis upon a single preferred embodiment it should be understood that
within the scope of the appended claims, the invention may be practiced
otherwise and as specifically described herein.
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