Centrifugal separator system

A centrifugal separator system for use in purifying drilling mud comprises a generally conical centrifugal separator into which drilling mud to be cleaned is introduced under pressure tangentially to cause centrifugal material flow. A vacuum generated within the center of the separator in response to centrifugal material movement draws lighter cleaned mud and drilling fluid upwardly to a discharge pipe which may lead to a remote drilling mud location. Heavier solids cleansed from the mud drop to the bottom of the centrifuge, settling on an output orifice closure valve. The valve is pivotally connected to the centrifuge whereby to close the output orifice until a preselected weight of material accumulates thereon. In order to prevent deleterious effects from suction variance, a single venting vacuum locking slot of a predetermined width is defined within the body of the orifice closure valve. The valve height is between one fourth and one half of the valve base diameter, and preferably the cone angle is thirty-three degrees. The slot width is between one thirtieth and one sixteenth of the valve base diameter, and preferably the slot length is between 0.3 and 0.6 of said valve base diameter.

BACKGROUND OF THE INVENTION 
This invention relates broadly to an improved system for cleaning drilling 
muds. More particularly, the present invention relates to an improved 
vacuum vent system for use with the valve member in conical separator 
systems. 
In the prior art it is known to provide centrifuge systems for cleaning 
drilling mud used in oil drilling operations. For example, this technology 
is generally discussed in U.S. Pat. Nos. 3,243,043 issued Mar. 29, 1966 
and 3,213,879 issued on Oct. 26, 1965. 
Basically the rotary drilling process employs a drilling mud to bring 
cuttings recovered during drilling to the surface of the well. Recovered 
solids include sand, shale, cuttings, and heavy materials, which must be 
separated from the drilling mud so that the mud may be reused. Drilling 
mud is comprised of a variety of materials and is extremely expensive, so 
that reuse is mandated. 
In order to separate solids, primarily sand, and other undesireable 
materials from drilling mud it is known to provide a centrifuge wherein 
dirty drilling mud is introduced at the top of a conical member under 
pressure. The mud is introduced tangentially within the upper confines of 
the generally conical interior, and it is forced into a centrifugal 
movement. This centrifugal movement creates an interior vacuum, which 
vacuum draws the cleansed material upwardly out of the apparatus for 
subsequent delivery to a drilling mud reservoir. Heavier materials drop 
down to the bottom of the centrifuge, where they may collect on an orifice 
closure member. 
As discussed in the aforementioned patents, the orifice closure member may 
be biased through a counterweight to yieldably occlude the output until 
sufficient weight of recovered solids is accumulated so as to open the 
output and dump the solids. Unless the output is regulated properly vacuum 
will be destroyed and cleansed mud will drop through the centrifuge and be 
lost. Therefore, proper regulation of the outflow of solids is necessary 
to prevent the loss of expensive drilling mud. However, with many known 
prior art devices blocking or lock-up of the output orifice can occur 
where surges of vacuum are created during outputting of the purified 
drilling mud. One approach aimed at solving the vacuum lock-up problem is 
illustrated by U.S. Pat. No. 2,806,599 issued to Patrick on Sept. 17, 
1957. The device described therein includes a vented valve closure member 
which constantly counteracts vacuum. Practical experience and 
experimentation with such devices has indicated that an alternative design 
is necessary. Where, for example, the separator is processing fluids where 
the sand has substantially been removed, cone lock-up may still occur when 
the vent becomes blocked in response to build-up of debris. 
SUMMARY OF THE INVENTION 
The present invention comprises a centrifuge system for cleaning drilling 
mud, which system incorporates a generally conically shaped housing having 
an input and two outputs. Dirty drilling mud to be cleansed is introduced 
under pressure tangentially, resulting in centrifugal motion within the 
conical interior. The motion of the solids creates a vacuum at the center 
of the apparatus, which vacuum suction draws lighter material, including 
the cleansed drilling mud, upwardly outwardly from the apparatus through a 
discharge pipe. Subsequently, cleansed mud may be recycled from an 
adjacent recovery reservoir. 
Heavier materials will drop downwardly within the conical centrifuge and 
may contact an orifice closure member which is yieldably biased against an 
output orifice by a counter balanced pivot arm. As the weight of the 
solids increases, the orifice closure member may be deflected from the 
output orifice so as to discharge solids. However, because of the 
conditions encountered in normal operations, high vacuum within the 
apparatus may maintain the orifice closure member permanently closed. 
Therefore, a vacuum slot is defined within the orifice closure member to 
prevent inadvertent jamming or "vacuum lock". Because of the geometrical 
configuration of the slot and the valve member in which it is defined, the 
valve member resists particle buildup, and jamming of the slot is avoided. 
Hence the problem of vacuum lock is remedied as reliable self-cleaning 
suction venting has been achieved. 
Thus, an object of this invention is to prevent blocking of a centrifuge 
drilling mud cleaner. 
Another object of this invention is to increase the reliabilityof a 
centrifuge drilling mud cleaner by making it less susceptible to vacuum 
induced jamming. 
Still another object of the invention is to provide a centrifuge cleaning 
system which will function reliably during a drilling operation 
notwithstanding operator misuse of the vacuum valve normally employed on 
the cleansed drilling mud output lines leading to the reservoir tank. 
Another object of the invention is to provide an improved centrifuge system 
for cleaning drilling mud which is equipped with means for preventing 
deterioration of the expensive liner required therein. 
Yet another object of this invention is to provide a centrifugal separator 
system in conjunction with which drilling mud losses will be minimized. 
A still further object of this invention is to increase the reliability of 
centrifugal separator systems for recovering drilling mud. 
Another object is to prevent vacuum lock in centrifuge drilling mud 
cleaners. 
A further object is to provide a balanced discharge cone valve with a self 
cleaning vacuum venting arrangement. 
These and other objects and advantages of this invention, along with 
features of novelty appurtenant thereto, will appear or become apparent in 
the course of the following descriptive sections.

DETAILED DESCRIPTION OF THE DRAWINGS 
With reference now to the appended drawings, a centrifuge constructed in 
accordance with the teachings of this invention is generally designated by 
the reference numeral 10. When cleansed, drilling mud 11 will be deposited 
in a remote reservoir 12 via an output pipe 14. 
It will be observed that the apparatus 10, shown in FIG. 1, comprises a 
generally conical hopper 16, the diameter of which decreases toward the 
bottom thereof, and an upper, generally cylindrical top portion 18. In 
practice centrifuge 10 will be comprised of a plurality of flangeably 
interconnected sections. For example, the upper cylindrical top portion 19 
is flangeably interconnected to the lower portion thereof 19A through 
flanges 21A, 21B coupled together with a plurality of conventional bolts 
23. Similarly, flange coupling structure 24 rigidly couples hopper 
sub-sections 16A and 16B together. Flange structure 25 couples hopper 
portion 16B to the lowermost segment 16C. Through the construction 
disclosed, the conical hopper may be quickly disassembled to enable 
changing of the internal, preferably rubber or plastic liner 30 disposed 
therein. 
The uppermost portion 19 of the hopper is integral with an arcuate pipe 31 
which terminates in a flange 32 coupled to flange 33 of output pipe 14. 
With reference to FIG. 2, dirty drilling fluid is inputted into the upper 
confines of the apparatus via a tangentially coupled input pipe 36, which 
delivers dirty mud and the like under pressure to the upper confines of 
the apparatus. Flange coupling 37 facilitates conventional coupling to 
external pipes or conduits. 
With primary reference now to FIG. 3, it will be apparent that the interior 
13 of the hopper is generally of an inverted, frusto-conical shape. As 
solids are introduced under pressure at the top of the apparatus, the 
resultant swirling or centrifugal motion creates a vacuum or suction in 
the center thereof. Suction from siphon output pipe 14 draws the cleansed 
lighter particles and solids upwardly and outwardly through pipes 31, 14 
for outputting into reservoir 12. Heavier substances will fall toward an 
orifice closure member 40 disposed at the bottom 42 of the apparatus, 
which yieldably blocks an output passageway 44. In normal operation the 
output end 14B of pipe 14 should be disposed beneath the ground level 15 
and the level of the hopper 16 for proper siphoning action. Sleeve portion 
46 of the conical hopper section 16C is integral with flange structure 25, 
which includes conventional flanges 27, 27A conventionally coupled 
together with a plurality of nut and bolts 25A, 25B respectively. The 
waste output end 43 of the hopper is thus defined by sleeve like hopper 
section 16C. The lowermost, generally cylindrically reduced diameter 
portion 30B of lining 30 fits coaxially within member 16C. When in the 
"closed" position illustrated in solid lines (FIG. 3) valve member 40 will 
block the discharge of materials from passageway 44. 
It will be apparent that the closure member 40 is secured to the hooked end 
50 of a generally arcuate arm 54, the opposite end 55 of which terminates 
in a lever 56, which is coupled by pivot 58 to a downwardly depending tab 
60 integral with flange 27. Thus the closure member 40 may be deflected 
toward the moved position illustrated in dashed lines in response to 
material accumulating thereon. However, a counterweight 64 provided at the 
outermost end 66 of the arm 56 may be adjusted to alternate positions on 
grooves 70 preferably provided on the arm to vary the amount of weight 
which is required to deflect valve 40 to an "open" position. 
The closure member 40 is of generally coaxial dimensions, including a lower 
threaded stem portion 78 which is adapted to be threadably coupled to 
internally threaded segment 81 of arm 54. Compression nut 79 will secure 
stem 78 in engagement. Importantly, the valve member is provided with a 
vacuum vent slot 80 which runs at least a major portion of the length 
between closure member top 81 and periphery 82. Slot 80 provides a 
constant vacuum vent within the centrifuge interior 13. In this manner the 
apparatus will be resistant to vacuum variations encountered in operation. 
For example, while mud is being purified during transfer between two 
drilling mud tanks, vacuum lock will be avoided. It will be observed that 
the conventional valve 17 coupled to siphon output pipe 14 is included to 
prevent too much suction from developing. Suction problems can develop, 
for example, when the discharge level of the output pipe 14 is too low 
with respect to the output of the centrifuge. This valve is usually 
operated manually during operation of the centrifuge to prevent jamming 
thereof when the output pipe is too low. However, when operators misuse 
this valve, the apparatus may become jammed, resulting in semi-permanent 
closure of the valve member 40. With vent slot 80 problems relating to 
vacuum will be reduced. Consequently, the rate of deterioration of the 
liner 30 will be reduced. It will also be apparent that variations in the 
suction operating point of the apparatus because of the use of slot 80 may 
be accomodated somewhat by adjustments to counterweights 64. 
With primary reference now to FIGS. 4-7, valve slot 80 continuously 
provides a vent pathway when valve member 40 is in the "closed" position. 
The resultant velocity of the air streaming through the slot tends to 
continuously free or un-jam it, and thus waste material collecting on 
valve member 40 will not block the slot 80. The diameter "d" of valve 
closure member 40 is nominally 1.5 inches. Height "h" is nominally 
one-half inch, or approximately one-third the diameter "d". The width "w" 
of the slot 80 is approximately one twenty-fourth of the valve member 
diameter, or as illustrated, one sixteenth of an inch. Angle 83 is 
approximately thirty three degrees. The length L of slot 80 preferably 
extends at least fifty percent (50%) of the distance between top 81 and 
periphery 82. Permissible variance in dimensional ratios are as follows: 
W: one thirtieth to one sixteenth d; 
H: one fourth to one half d; 
L: 0.3 to 0.6 d; and, 
D: one to three inches. 
From the foregoing, it will be seen that this invention is one well adapted 
to obtain all the ends and objects herein set forth, together with other 
advantages which are obvious and which are inherent to the structure. 
It will be understood that certain features and subcombinations are of 
utility and may be employed without reference to other features and 
subcombinations. This is contemplated by and is within the scope of the 
claims. 
As many possible embodiments may be made of the invention without departing 
from the scope thereof, it is to be understood that all matter herein set 
forth or shown in the accompanying drawings is to be interpreted as 
illustrative and not in a limiting sense.