US2084484A - Apparatus for discharging acid from a centrifuge - Google Patents

Description

June 22, 1937. D. F. EDWARDS ET AL 2,084,434

API ARATUS FOR DISCHARGING ACID FROM A CENTRIFUGE Filed Nov. 22, 1935 allll v I m Patented June 22, 1937 UNITED STATES PATENT OFFICE APPARATUS FOR DISCHARGING ACID FROM A CENTRIFUGE David F. Edwards, Elizabeth, and Arthur M. Wilson, Cranford, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application November 22, 1935,v Serial No. 51,094

3 Claims.

This invention relates to a means for withdrawing liquids from a centrifuge and especially to an improved acid discharge device therefor where an acid is separated in the centrifuging operation as a third layer in a normally twolayer separation of acid treated petroleum oils from acid sludge. The invention will be fully understood from the following description read in connection with the accompanying drawing,

Fig. I is a vertical section through the device; and

Fig. II is a vertical section through a centrifuge with the device in place in the centrifuge bowl.

In the refining of petroleum oils, it is common practice to treat the stock with sulfuric acid and to remove the sludge formed by such treatment by settling or by means of a centrifuge. There are certain advantages to be gained by the rapid separation of sludge by centrifuging but when the reaction mixture is subjected to the high centrifugal force required to separate the sludge and oil, a certain amount of free acid is also separated from the sludge. This acid, being heavier than either the oil or the sludge, is thrown to the outer periphery of the bowl resulting in a three-layer separation consisting of oil, sludge and acid. The heavy acid layer must be removed by special means or, as it does not discharge readily with the sludge, it soon closes off congestion of the sludge discharge port and stops the operation of the centrifuge.

One method of removing the acid layer has been by the use of a special acid discharge outlet member screwed into the shell of the centrifuge bowl, forming an opening to a special discharge line in the casing surrounding the shell. The outlet member referred to consists of a nipple exteriorly threaded at one end to engage an opening in the shell of the centrifuge bowl and threaded interiorly at the other to provide engagement for a threaded orifice member, both the nipple and the orifice member being assembled 45 by means of wrenches manipulated from outside of the bowl through a passageway in the nipple. When the rate of flow through a device of this type is to be changed, the orifice member is removed and replaced by one of the size required.

However, in view of the fact that the threads on the orifice member and within the inner end of the nipple are necessarily finely machined, the

type of alloys which will resist acid erosion and corrosion cannot be used as they do not readily 55 lend themselves to the machining operations required. As a result materials which can be read.- ily worked are used and due to their nature severe corrosion and erosion result within 12 to 48 hours of operation and replacement of the nipples and orifice members is found to be necessary at frequent intervals. Due to this corrosion and erosion which takes place, it is necessary in most instances to drill the parts from the bowl in order to make any replacements or adjustments.

The device to which the present invention relates not only simplifies'the manufacture of the parts required but also makes possible the use of very hard, acid resisting alloys in the orifice member resulting in reduced corrosion and erosion of the various parts as well as a reduction of "time required to change or replace the orifice member.

Referring first to Fig. I of the drawing reference numeral i denotes an orifice assembly, comprising a tubular nipple or valve body 2, an orifice member 3 and a casing 4 for the assembly. The tubular nipple 2 bears a flanged portion 5 adjacent one end, screw threads 6 between the flanged portion and the end of the nipple 2, and is provided at the opposite end with an interiorly disposed outwardly facing shoulder I, the surface of which is machined to form the seat 8. The orifice member 3 is generally cylindrical in shape and adapted to fit loosely within the tubular nippie 2. It is provided at one end with an enlarged portion 9 forming an inwardly or downwardly facing shoulder in exteriorly of the member, having a machined surface adapted to engage the seat 8 disposed within the nipple 2 through the gasket II. The orifice member 3is formed with a centrally disposed passageway I2 throughout 1 its length to a point adjacent the enlarged por-' tion 9, and communicates with a sized orifice I3 extending from that point to the end of the member 3 within the enlarged portion 9.

The casing 4 is adapted to enclose the assembled nipple 2 and orifice member 3 in such manner as to provide an annular passageway l4 between the inner wall of the casing 6 and the outer wall of the nipple 2, communicating through the space provided between the closed end of the casing and the inner end of the orifice member 3 with the orifice I3. The lower end of the casing 4 is provided with notches l5, forming openings communicating with the passageway It in the manner above described.

Referring now to Fig. II, numeral I6 denotes a centrifuge adapted for the centrifugal separation of sludge from acid treated petroleum oils having a discharge outlet ll' for the separated charge chamber surrounding the bowl.

oil and a discharge outlet H! for the acid sludge, and the acid orifice assembly I illustrated by Fig. I.'

As shown, the centrifuge bowl I9 is provided with a threaded opening 20 in its outer wall and with an oppositely disposed opening 2| in the upwardly extending portion of the bottom of the bowl. A tubular member 22 is disposed within the opening 2| in fluid-tight engagement with the surrounding wall and extends into the bowl of the centrifuge I9 to a point adjacent the upper wall thereof concentric with the opening 20 and outwardly from the bowl of the centrifuge to an intermediate point in the space formed beneath the centrifuge bowl I!) by. the upwardly extending portion of the bottom thereof. This tubular member 22 is provided at its outer end with cap 23 adapted for threaded engagement therewith.

In assembling the apparatus as shown in Fig. II, the cap 23 is removed from the tubular member-22 and the nipple 2 is inserted through the tubular member 22 and threaded into the opening 20 in the centrifuge bowl IS. The orifice member 3 is introduced in like fashion and inserted in the nipple 2 into engagement with the gasket ll, carried by the interiorly disposed shoulder l of the nipple 2. The casing 4 is then placed over the nipple 2 and orifice member 3 .to complete the assembly and the cap 23 replaced.

In operating the centrifuge for the separation of acid treated oil from sludge, the free acid separated from the sludge layer in the centrifuge bowl moves to the periphery of the bowl and passes from the notches 15 in the valve casing and by means of passageway l4 into the space adjacent the orifice member 3. This movement of the acid is relatively slow inthat it is moving toward the center of rotation and against the centrifugal force exerted by the spinning bowl and consequently little or no erosion of the nipple or casing takes place. From the innermost point of discharge orifice l3, however, the acid is forcibly discharged through the orifice member 3, passing through the passageway l2 to a dis- Due to the construction of the valve, the member 3 can be made long enough to shield the nipple 2 from the corrosive and erosive effects of the acid when discharging at a high rate of speed. Likewise the member 3' may be made of alloys which are highly acid resistant, while the nipple 2 may be formed of metals which are not so highly resistant to acid attack as those used for the construction of the member 3.

This invention is not to be limited by the particular details disclosed for the purpose of a better understanding thereof, but only by the following claims in which it is desired to claim all novelty inherent in the invention as broadly as the prior art permits.

We claim:

1. An orifice assembly comprising a tubular nipple exteriorly threaded at one end and having an outwardly facing machined seat interiorly disposed adjacent its other end, an orifice member telescopically associated with said nipple throughout its length and having an inwardly facing machined shoulder adjacent one end adapted to engage the seat within the nipple by means of an interposed gasket, a casing for the assembly tubular in form, open at one end and. closed at the other, adapted to enclose the nipple and orifice member in such manner as to form a passageway between the nipple and the casing, which passageway communicates with the orifice in said orifice member, openings in the side walls of the open end of the casing communicating with said passageway.

2. In an acid discharge device for a centrifuge having an elongated tubular body portion of non-acid resistant material and containing an inwardly disposed seat at one end, an orifice member comprising an elongated cylinder of highly acid-resistant material having an enlarged portion at one end forming a shoulder on said member, a sized orifice in said enlarged portion communicating with a centrally disposed passageway within the cylinder opening through the opposite end of said member, said orifice member being adapted to be telescopically disposed within the elongated body portion with the shoulder on the orifice member in fluidtight engagement with the seat within the elongated body portion whereby the interior of said body portion is protected from contact with the liquid discharged from the centrifuge.

3. In combination with a centrifuge having a discharge outlet in the lower portion of the outer wall of the centrifuge bow1, an orifice assembly for said outlet, comprising an elongated nipple threaded into the outlet and extending inwardly into the bowl, said nipple being adapted to freely and telescopically receive an orifice member of substantially the same length as the nipple, having a sized orifice in its inner end communicating with an enlarged passageway in said mem ber extending outwardly into communication with a discharge chamber surrounding the bowl,

the orifice end of said member having an enlarged portion adapted to engage a shoulder within the inner end of the nipple to be held in fluid tight engagement therewith by cen-

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