Note: Descriptions are shown in the official language in which they were submitted.
l~'ZZ905
Backyround of the Invention. The present invention re-
lates to the art of drilling fluid processing, and more particular-
ly to a system for degassing drilling muds. The present invention
provides a centrifugal pump system for pumping gas laden drilling
fluids while restricting the flow of gases removed from such liq-
uids to conduits by which they are carried to safe disposal areas.
Such a centrifugal pump system is desirable for the transfer of
such gas laden fluids into degassing or deaerating vessels, or out
of such vessels during periods of incomplete degassing.
In drilling a well for oil, gas and the like, the drill-
ing bit i9 supported in the well bore by tubing. The tubing is
hollow pipe composed of a plurality of individual lengths of pipe
connected together. The tubing carries drilling fluid in its ih-
terior down to and through the drilling bit. The drilling fluid
at the bottom of the well bore passes upwardly in the annulus be-
tween the exterior surface of the tubing and the interior surface
of the well bore to the surface of the earth and then through a
return pipe to storage pits on the surface of the earth commonly
referred to as mud pits.
The drilling mud is ordinarily an aqueous suspension of
solid matter generally containing minerals such as bentonite and
barite. The drilling mud lubricates and cools the drill bit and
serves as a carrier to withdraw drill cuttings and debris from the
well for disposal. The drilling mud also provides a pressure seal
in the well bore to prevent the escape of gases from the well. The
pressure exerted by the column of drilling mud normally is greater
than the pressure which may be released upon encountering gas pock-
ets as the well is drilled. The column of drilling mud counteracts
gas pressure and prevents blowouts but very often becomes contami-
nated with the gases encountered during the drilling operation.
Under many circumstances it is desirable and in fact
often absolutely essential that the gases-be removed from the
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drilling mud and transmitted to a disposal area. Since it is
economically unfeasihle to discard the contaminated drilling mud
and because of the danger o~ the gases in the mud being released
into the atmosphere in large quantities creating dangerous condi-
tions at the drill site, it is necessary to process the mud to re-
move the gases and recirculate the degassed drilling mud through
the borehole. The contaminating gases may be poisonous or highly
explosive and the release of such gases into the atmosphere would
present a substantial risk to personnel in the drilling area. The
presence of gases in the drilling mud decreases its weight and af-
fects its viscosity often rendering it unsuitable for recircula-
tion through the borehole. When gases are contained in the drill-
ing mud being circulated through the borehole, it increases the
danger of a blowout in the well.
A "Notice to Lessees and Operators of Federal Oil and
Gas Leases in the Outer Continental Shelf, Gulf of Mexico Area"
was released May 7, 1974 by the United States Department of the
Interior Geological Survey, Gulf of Mexico Area, relating to hy-
drogen sulfide in drilling operations. The notice outlines re-
quirements for drilling opera~ions when there is a possibility or
probability of penetrating reservoirs known or expected to contain
hydrogen sulfide. Section 3. f. provides that "drilling mud con-
taining H2S gas shall be degassed at the optimum location for the
particular rig configuration employed. The gases so removed shall
be piped into a closed flare system and burned at a suitable re-
mote stack."
The prior art shows examples of systems for the degasifi-
cation of drilling mud, many of which utilize a vacuum tank and
some sort of baffle arrangement which exposes the drilling mud to
vacuum environment, thus causing the entrapped gas to be removed.
This is only part of the task however for serious problems are
encountered in the handling of drilling muds, particularly in
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evacuating the drilling mud from the vacuum tank to return it as
degassed mud to the well head. Precise control of the rates at
which drilling mud enters the vacuum tank, degassed mud leaves the
vacuum tank, and gases are evacuated from the tank, is necessary
in order to produce an acceptable product at the necessary rate.
Some systems of the prior art use a separate vacuum pump
and often expose this apparatus to the possibility of ingestion of
drilling muds, a situation which normally damages the pumping mech-
anism and, at the very least, forces the entire system to be shut
down for cleaning. Prior art devices have also exhibited problems
in matching the vacuum pulled on the vacuum tank with the flow re-
quirements of the entire system, which may be continually changing.
Numerous efforts have previously been made to eliminate
the use of a mud jet for effecting the flow of mud such as sub-
lS stituting a centrifugal pump for the mud jet. However, such pre-
vious efforts have not been entirely successful inasmuch as a pump
tends to become air-locked when the supply of mud to the tank is
insufficient, or when vortexing of mud in the tank permits air or
gas to enter the pump or when air or gas is present in the mud for
any reason. Even when self-priming centrifugal pumps are used,
several minutes may elapse before the pump resumes effective pump-
ing action and during that period the efficiency of the degassing
operation in the tank is materially affected. Previous attempts
to provide vapor-vented centrifugal pumps include that disclosed
in U.S. Patent 3,815,717 which is not practical in abrasive fluids
such as drilling muds because of rapid wear on its seals. A de-
sign disclosed by U.S. Patent 3,769,779 avoids the abrasion of
seals but requires the freed gas to flow counter to the incoming
fluid at one or more points.
Description of Prior Art. In U.S. Patent No. 3,769,779
to Walter E. Liljestrand, patented November 6, 1973, an apparatus
is shown for degassing fluidst particularly drilling muds, com-
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prising a vessel having an inlet and an outlet for the intake and
discharge of the fluid to be treated, a centrifugal pump connected
to the vessel for circulating the fluid through the vessel and
means for removing gas from the region of the impeller means in
the centrifugal pump. The invention also includes a centrifugal
pump designed for handling gas laden fluids, the pump having a
means for removing gas from the region of the pump impeller. The
invention further includes a centrifugal pump for handling corro-
sive and/or abrasive fluids wherein said fluids are prevented from
contacting the pump seal by means of a gas pressuriæed compartment
adjacent the seal.
In U.S. Patent No. 3,616,599 to Gerald E. Burnham,
patented November 2, 1971, a drilling mud degasification apparatus
is shown having baffle plates in a vacuum tank over which thin films
of mud are degassed as they flow downward to a receiving area of
the tank. Venturi-type dual ejectcr apparatus is located in a sump
in the tank to remove degassed mud and to draw a vacuum on the up-
per portion of the tank.
In U.S. Patent No. 3,241,295 to Phil H. Griffin, III et
at, patented March 22, 1966, a mud degasser apparatus combination
is shown with a mud degasser vacuum tank having a mud inlet and a
mud outlet for continuous flow of mud through the tank, means for
maintaining the interior of said tank at sub-atmospheric pressure,
valve means provided in said mud inlet for controlling the rate of
flow of mud into the tank, means responsive to variations of level
of mud in said tank for varying the sub-atmospheric pressure in the
tank, and means responsive to variations of pressure in the tank
for opening and closing said valve means.
In U.S. Patent No. 3,249,227 to Alfred B. Long, patented
May 3, 1966, a centrifugal separator is shown for the treating
(mechanical processi~g) of slurries, and for the classification by
specific gravity of solids in slurries and muds, of components of
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emulsions, and also for the degasification of drilling
muds. It is suitable for use in the chemical, mining
and petroleum industries.
In the publication "A Degasser You Can Understand"
by Walter E. Liljestrand, presented at IA~C Rotary Drilling
Conference in March 1974, a description of mud degassing is
set out. A degasser is one of several important components
necessary on a rig to handle gas in mud. This paper gives
perspective to the whole problem. The atmospheric degasser
described is entirely new in concept. The flow is controlled
by the liquid and the pump.
Summary of the Invention. This application is a division
of Canadian Application Serial No. 292,031 filed November
29, 1977 for a "Mud Degasser Trough", and is rela-ted to
two other divisional applications of the same assignee for
"Degasification System" and "~egasser Spray Vessel", both of
which are filed concurrently herewith.
The parent application is generally related to a
system for the degasification of drilling mud in a continuous
manner as the mud is circulated to and from a well head. That
system is capable of pumping gas laden liquids, including
drilling fluids, while restricting the flow of gases removed
from such liquids to conduits by which they are carried to
safe disposal areas. Such a system includes the transfer- of
such gas laden fluids into degassing or deaerating vessels
or out of such vessels during periods of incomplete degassing.
The present invention is particularly related to a
mud degasser trough which may be used in the system of the
parent application. Broadly speaking the present invention
provides a degassing trough for removing gas bubbles entrain-
ed in viscuous fluids such as drilling mud, the trough compris-
ing: an enclosed inlet section having an inlet opening therein;
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a flow section connected to the inlet section and being
relatively airtight; a restricted flow opening between
the inlet and flow sections arranged to maintain a liquid
barrier against open communication of gas between the two
sections; gas discharge means in the flow section; and,
fluid discharge means in the flow section.
The foregoing and other objects and advantages
of the present invention will become apparent from a con-
sideration of the following detailed description of the
0 invention when taken in conjunction with the accompanying
drawings.
Brief Description of the Drawings. Figure 1 illustrates
.. . . .
a degassing system constructed in accordance with the pre-
sent invention.
Figure 2 is an enlarged view, partly in section,
showing the centri~ugal pumping means from the system shown
in Figure 1.
Figure 3 is an enlarged view, partly in section, of
the spray vessel.
Figure 4 is a partial cross-sectional side view
of the gas separation trough.
Figure 4A is an enlarged view of a portion of the
structure shown in Figure 4.
Detailed Description of the Inventlon. Referring now to the
drawings and, in particular, to Figure 1, an embodiment of a
degassing system constructed in accordance with the present
invention is illustrated. Gas contaminated drilling mud 22
from mud tank 20 is directed to a mud spray vessel 29 through
line 2~ by a pump system 14. A vacuum created in vessel 29 is
communicated by
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conduit 25 to a top cap 12 with a rotatable seal on the top end of
the hollow pump shaft of pump 14. Mud is pumped via line 24
through the wall of vessel 29 and is sprayed outward through spray
head 27 where it impinges the wall of vessel 29 and moves downward,
out the bottom discharge tube 23. From tube 23 the mud passes
into the gas separation trough 28 and flows down the trough under
a float-operated gate 58, down the return pipe 30 and back into de-
gassed mud tank 21.
The pumping system 14 of this invention provides a cen-
trifugal pump capable of pumping the gas laden drilling mud 22,
while restricting the flow of contamination gases removed from
the drilling mud to conduit 25, by which they are conveyed via
vessel 29, trough 28, and conduit 26 to safe disposal areas. The
pumping system 14 transfers the gas laden drilling mud into the
spray vessel 29.
It is well known that conventional centrifugal pumps
tend to become vapor locked which seriously reduces the volume
capacity of the pumps, limiting their effectiveness in handling
fluids. Previous attempts to provide vapor-vented centrifugal
pumps include that disclosed in U.S. Patent 2,815,717 which is not
practical in abrasive fluids such as drilling muds because of
rapid wear on its seals. The design disclosed by U.S. Patent
3,769,779 avoids the abrasion of seals but requires the freed gas
to flow counter to the incoming fluid at one or more points.
As can be better seen in Figure 2, the pumping system
14 of the present invention uses a hollow centered impeller 2
driven by a hollow shaft 3 through which the gas may be withdrawn
without having to move through a fluid filled zone. A prerotation
inlet chamber 3 and shroud 7 below the impeller 2 admit free fluid
3~ into the impeller housing 4 in a peripheral flow. Released gas
flowing from the vortices of shroud 7 and cha~ber 8 and of the imFe,ller,
2 moves upward through the hollow drive shaft 3, thence ~hrough
l~ZZ90~i
the top of the shaft into a top cap 12 which has dynamic seals 12a
therein for sealing engagement with the rotating shaft.
The centrifugal pump includes an impeller 2 rotatably
mounted on shaft 3 and made to rotate in impeller housing 4 by a
motor 5 driving the shaft 3 through a sheave 6a and belt drive 6.
A shroud section 7 and a prerotation inlet section 8 are attached
to the impeller housing 4. Fluid enters the prerotation inlet
section 8 through essentially tangential entrances 9, giving the
fluid a circular motion in the direction of rotation of impeller 2.
The fluid must then pass through the shroud section 7 to reach the
impeller and in so doing it is given additional rotational velocity
by the reduced radius, further establishing a central vortex
through which any gas escaping from the fluid will be released
toward the central longitudinal axis of the pump shaft and up the
shaft. The released gases rise through the central opening 10 in
impeller 2, through the hollow center 11 of shaft 3, to the conduit
25 in top cap 12.
Fluid under pressure from the impeller rotation exits the
impeller housing through port 19 but is also free to enter the space
between impeller 2 and the top 16 of housing 4 and into the annular
space 17 between the shaft 3 and shaft housing 15. When the impel-
ler is not in motion, the fluid level in the annulus 17 will be
that of the external fluid, but when impeller is turning the pres-
sure developed could force the fluid somewhat higher in the an-
nulus 17. To prevent such rise, a discharge tube 18 may be pro-
vided through which such pressure can be relieved by venting the
small flow of fluid which may migrate upward through space 17.
Also, a double helical vane 37 may be affixed to the outside of
the impeller shaft 3 to provide a downward impetus on any flow of
fluid up the annulus 17, or an annular dynamic seal could be lo-
cated between shaft 3 and housing 15.
Referring now to Figure 3, ihe spray vessel is illustrated
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in cross-section. The vessel 29 generally comprises a cylindrical
upper section 29a, a frustoconical intermediate sec-tion 29b and
the bottom discharge tube 23. The mud inlet line 24 is attached
to a transmit collar 32 which is sealably secured in the wall of
vessel 29. A top cover plate 33 is sealingly secured to the upper
section 29a b~ means such as bolts 34 passing through flange 35.
An upper discharge pipe 36 communicates with an opening in plate
33 and has connected thereto the gas flow conduit 25.
The spray assembly 27 is suspended in a generally central
location inside vessel 29 by means of an inlet conduit 40 which in
turn is attached to collar 32 in coaxial alignment therein. As-
sembly 27 generally comprises an outer annular flow bowl 38 which
generally includes a double-walled cylindrical member closed at
the bottom and open at the top. The enclosed area 39 formed by
the two walls and bottom of bowl 38 is in fluid communication with
flow line 24 via collar 32 and inlet conduit 40.
A deflector plate 41 is located directly above annular
space 39 and in close proximity to bowl 38. The location of plate
41 with respect to bowl 38 forms a relatively narrow spray gap 44
therebetween. Plate 41 preferably is of a larger diameter than
bowl 38 to prevent fluid spray from going upward in vessel 29.
The plate has a central opening in which is secured a cylindrical
center spool 42 which in turn fits in relatively close-fitting re-
lationship inside the central space of bowl 38.
Center spool 42 has an open passageway 43 passing there-
through. me deflector plate and spool arrangement is supported by a
threaded bolt member 45 which is threadably engaged at its lower
end in a cross member support 46 and at its upper end in a similar
cross member support 47~ Cross member 47 extends across bore 43
and is attached to plate 41 at each end of the cross member by
means such as welding or bolts. Likewise, cross member 46 extends
across opening 43 and is attached at each end to the bottom of bowl
l~Z~905
38 by means such as welding.
Adjustment of spray gap ~4 is obtained by rotating plate
41 clockwise ~o narrow gap ~4 or counterclockwise to widen gap 44.
The rotation of plate 41 also rotates threaded cross member 47
which moves the plate and cross member up and down on the threaded
bolt 45.
Figure 4 is an enlarged cross-section of the gas separa-
tion trough 28. This primarily consists of an elongated enclosed
flow trough 50 connected to an inlet cabinet 51. The inlet cabi-
net has at the top an inlet conduit 52 having an annular flange 53
at the top thereof. A corresponding matching flange 48 is located
at the bottom of the discharge tube 23 of vessel 29.
The mating flanges 48 and 53 allow placement of vessel
29 atop trough 28 where it may be attached by means such as bolts
passing through the complementary flanges. The inlet tube 52 is
in coaxial alignment with discharge conduit 23 and extends through
a substantial portion of cabinet 51 to a point near the bottom
thereof. An alternate location for conduit 52 is drawn in phantom
at 55 for configurations where height of the assembly is limited.
A vertical baffle plate 54 is attached to the bottom of
cabinet 51 and extends entirely across the cabinet from one side
to the other. A second plate 72 extends downward from the top of
the trough to a point above the bottom of the trough, forming a
flow space thereunder. A peaked roof 56 is hingedly attached to
channel section 50 and completely closes this section of the trough.
The inlet cabinet 51 is also completely closed. A dis-
charge port 57 is located near the end of channel section 50 and
is in communication with mud return pipe 30. A flow control plate
5~ is secured to float arm 61 which is hingedly attached at 59 to
the far end 60 of the trough. The plate extends substantially
across the width of the trough and is located forward of port 57.
A float member 62 is secured to the opposite end of arm
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61 from connection 59. An enclosure plate 66 is secured to the
back 60 of the trough and extends forward over discharge opening
57. A downward extending front plate 67 is attached to the front
edge of plate 66 in close sliding relationship with control plate
58. Plates 58, 66, and 67 preferably extend substantially across
the width of trough 28. A checkvalve 68, which can be of any of
the many known one-way valves, may be provided on plate 66 to allow
discharge of gas trapped therebelow.
Figure 4a illustrates one type of checkvalve which can be
ln used in plate 66. In this instance, a hinged damper valve 69 is
pinned to plate 66 by pin 70 such that it is arranged to rest in a
closing position on port 71 which passes through plate 66. Gas
pressure below plate 66 can move upward through port 71, lifting
valve 69, and moving into the upper portion of trough 28. Gas or
fluid flow downward through port 71 is prevented by the closing of
damper 69.
It should be noted that the action of the gate assembly
comprising float 62, arm 61, and plates 58, 66, and 67 is to en-
sure a fluidic seal between trough 28 and discharge port 57 in
order to provide a barrier to the passage of gas through port 57.
As a further means of preventing gas flow through port 57, dis-
charge conduit 30 may be extended upward a predetermined distance
past the bottom of trough 28. This distance could be selected to
locate the top of conduit 30 higher than the bottom of plate 67.
A gas discharge tube 63 passes through the peaked roof
56 and has secured thereto a gas flow line 26. One or more verti-
cal baffles 64 extend across a substantial portion of the width of
the trough 28 and extend downward into the trough towards the bot-
tom thereof. These may be welded or secured to the sides of the
trough and are open in the peaked roof section 56. Roof section
56 in one embodiment had a slope of 45 degrees with the peak being
located generally centrally along the roof section.
In typical operation, the mud gas separator assembly of
this invention may be assembled at a well drilling site and placed
on the mud tanks 20 and 21 by means such as extended cross member
pipes 65 which are of sufficient length to span the width of the
tank 20~ The motorized pump assembly may also be suspended from
the side of the tank by hanger means or other means known in the
art. The drilling fluid is pumped into the tank 20 from the drill
site preferably through a device which removes solids such as rock
cuttings and sand from the drilling mud.
The pump motor is started and fluid is drawn into the
tangential inlets 9 in chamber 8 and upward through shroud 7 where-
upon it is expelled through discharge port 19 by impellers 2.
A central vortex is formed in the center of the hollow
impeller member at 10 and gas bubbles which become separated from
the mud in the centrifugal pump are moved inwardly into area 10
by the action of the heavier mud being moved outward in response
to the centrifugal forces imposed on it by the pump impeller. The
separated gas moves upward through the hollow center 11 of shaft 3
and out through the top of the hollow shaft which is sealingly
covered by the top cap 12.
The pumped mud moves out discharge port 19 into conduit
24 and thence upward into spray vessel 29. At spray vessel 29,
the mud moves through collar 32 into the conduit 40 and the annular
space 39. The high pressure mud is forcefully emitted through nar-
row gap 44 against deflector plate 41 forming a circular spray out-
ward from plate 41 against the inside surface of the outer wall of
vessel 29. This spray of fluid forms a "doughnut" shape having an
open central portion at 43.
The action of the spray ~utward against the wall of the
vessel establishes a strong vacuum in the upper portion of the ves-
sel above the spray. The action of the fluid against plate 41
serves to place the fluid in high turbulence and shear which re-
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sults in a combining of many small entrained gas bubbles into
larger bubbles. The reason for the creation of the high vacuum in
the upper part in the chamber appears to be a result of the venturi
effect of the spray outward and the open central passage 43.
This creation of a high vacuum is very beneficial to
drawing the small bubbles in the fluid together and out of the
fluid. The vacuum is also beneficial by its effect on the cen-
trifugal pump 14. The vacuum communicates with the pump 14 through
conduit 25. This action serves to further draw off the gas sep-
arated in the pump at the central opening 10. The vacuum further
enhances the efficiency of the pump by reducing the so called vapor
lock and cavitation effects in the impeller area and by further
aiding in the intake of fluid into the pump as a result of this
vacuum.
Thus, the created vacuum in the upper portion of vessel
29 is a multi-purpose advantage. It aids in the combination of
small bubbles into large bubbles; it aids in drawing the entrapped
gas bubbles from the fluid both in the vessel 29 and in the impel-
ler area of the pump 14; and it further increases the efficiency
of the centrifugal pump in one or more ways.
The mud is emitted through spray gap 44 in a continuous
sheet and impinges on the wall of vessel 29, and flows downward
therealong until it reaches the discharge tube 23 from which it
passes into the intake 52 of the separator trough. The fluid flows
downward to the bottom of cabinet 51, back upward over the top of
flow baffle 54, and then down again under plate 72. Plates 54 and
72 prevent open communication from the upper portion of channel 50
to the vessel 29. This results in a maintenance of the high vacuum
in vessel 29.
Were plates 54 and 72 to be removed, an open communica-
tion of the vacuum area of vessel 29 would be permitted with the
discharge line 26, and the vacuum would be greatly reduce~. Thus,
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the placement of the baffles creates narrow openings at the top of
the cabinet and the bottom which generally are filled by the flow
of fluid from conduit 52, thus effectively forming a liquid seal
and so preventing open gas communication therepast.
Small gas bubbles are combined in vessel 29 to form
large bubbles which pass through conduit 52 in the drilling fluid
over baffle 54, under plate 72, and into the trough section. Al-
though the bubbles are still in the fluid, they have been enlarged
by having been combined through the turbulence and vacuum effects
in vessel 29 to the point where they have sufficient buoyancy to
rise to the top of the fluid stream in the enclosed trough section
50. The baffles 64 slow transit of the foamy upper level of fluid
containing the highest concentration of gas bubbles in order to
allow them more time to break out of the mud.
The entire operation of the degassing system depends in
large part upon combining the small entrapped gas bubbles into
larger bubbles so that their total buoyance is sufficient to over-
come the inertia and viscosity of the heavy fluid in which they are
entrapped. The operation of the present invention is advantageous
in that the discharge gas which collects at the top of the trough
section 50 is under a net positive pressure and therefore flows
freely from the trough section through hose 26 without need for
mechanical removal means such as a vacuum pump or fan.
The resulting positive gas pressure in trough section 50
apparently is a result of the hydrostatic head of the fluid in ves-
sel 29 acting through the entirely enclosed vessel 29 and trough
28. An optimum level of fluid in the trough is maintained by gate
5~ which preferably is connected to an adjustable float member 61
for maintaining the predetermined fluid level.
It should also be pointed out that one of the important
parameters involved in the gas separation process is the time of
transit of the fluid through the separation trough. A trough of
:l~ZZ90S
insufficient length for the given flow velocity of the drilling
fluid therethrough wi]l not allow sufficient time to accomplish an
acceptable gas separation rate because of the lack of time for the
smaller bubbles to overcome the fluid inertia and viscosit~ and
rise to the surface.
It was found in one particular embodiment that a trough
length of approximately eight feet provided a gas removal rate of
around 85 percent in a test slurry pumped at 400 GPM. Any addi-
tional length will provide small lncreases in the percentage of
gas removed from the fluid. Additional methods of increasing the
residence time of the fluid in the separation trough include lo-
wering the pumping rate, increasing the cross-sectional flow area
of the trough, and altering the depth of the drilling mud main-
tained in the trough.
Thus, it can be seen that with the present invention,
many advantages are obtained in the degasification of the drilling
mud. One of these advantages involves eliminating the need for a
mechanical vacuum pump or blower device to remove the possibly
dangerous gases from the separator assembly. Another advantage
obtained involves the much greater pumping efficiency of the cen-
trifugal pump arising from the application of the vacuum to the
impeller vortex area. Another advantage gained is capture of the
removed gases from the pump vortex area and the conveyance of these
gases to a section of a vessel where they can be captured and
2S flowed to a safe disposal area.
Further advantages involve the more efficient combining
of small gas bubbles into the more easily removable large bubbles
as a result of the high vacuum formed in the spray vessel and the
more effective removal of bubbles as a result of the efficient de-
sign of the separator trough. Other advantages not discussed here-
in or readily apparent from the description above are obtainable
with the practice of this invention.
~lZZ905
Although a specific preferred embodiment of the present
invention has been described in the detailed description above,
the description is not intended to limit the invention to the par-
ticular forms of em~odiments disclosed therein since they are to
be recognized as illustrative rather than restrictive and it will
be obvious to those skilled in the art that the invention is not
so limited. For instance, whereas the spray vessel 29 has been
described as a cylindrical vessel, it is obvious that one could
substitute other configurations for this vessel such as square,
rectangular, oval, etc. Also, whereas a centrifugal impeller type
pump is utilized with this invention, it is clear that other types
of fluid pumping apparatus would be workable with this invention.
Also, whereas the mud gas separator trough 28 has been described
as a rectangular vessel having an elongated flow channel with a
peaked roof, it is obvious that other cross-sectional configura-
tions of this trough could be utilized such as a U-shaped trough
or a circular trough. A further modification would involve pro-
viding a gas conduit from the upper portion of vessel 29 to the
lower portion of the vessel in lieu of communication through a
central opening 43 in spray assembly 27. Thus, the invention is
declared to cover all changes and modifications of the specific
example of the invention herein disclosed for purposes of illustra-
tion which do not constitute departure from the spirit and scope
of the invention.
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