CA1237372A

CA1237372A - Vessel construction

Info

Publication number: CA1237372A
Application number: CA000454243A
Authority: CA
Inventors: Otto J. Seidi
Original assignee: National Tank Co
Current assignee: Cameron Solutions Inc
Priority date: 1983-05-23
Filing date: 1984-05-14
Publication date: 1988-05-31

Abstract

VESSEL CONSTRUCTION
ABSTRACT OF THE DISCLOSURE
A large vessel in which oil well fluids are received has a small subvessel mounted within it. The subvessel is mounted in the upper portion of its parent vessel, in which position the sub-vessel receives only the separated oil well fluid rising to the upper part of the parent vessel. The subvessel is formed of a cylinder welded by a first end to a wall of its parent vessel, while detachably sealed at its second end to a circular plate clamped just within the interior of the cylinder.

Description

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VESSEL CONSTRUCTION
TEC~INICAL FIELD
The present invention relates to the construction of a vessel, container, or tank. More particularly, the invention re-lates to the provision of a detachable section of the wall o-F the vessel to provide ready access to the interior.
EACKGROUND ART
In the production of oil well fluids, vessels are pro-vided to receive these fluids and provide time and structure to separate the coMponents of the produced fluids in reducing the cost of distributing and transporting the separated fluids to other processes. Representative of these vessels is the somewhat plebian free water knockout (FWK). This vessel is little more than alarge volume in the line providing enough residence time to enable the first gravity disengagement between water and oil to take place.
Water loosely bound to the oil "-Falls" freely to the bottom of the vessel, thus giving rise to the descriptive term FWK. The water and oil, roughly separated, are individually passed to downstream processing equipment. An interface is formed between the oil and water in the FWK. The height of this interface is sensed by a float for controlling a valve in the outlet conduit for water. A
subvessel is mounted in the upper portion of the parent vessel to receive the oil and control its discharge to downstream processing equipment. Little economy has been practiced in the construction of this subvessel, usually referred to as the "oil skimmer". It is common practice to weld plates together to form a box and mounting it in some convenient fashion in the upper portion of its parent vessel and providing an opening near its top through which oil spills into the interior. A level control may be provided within the skimmer and a valve in the outlet line from the skimmer is con-trolled by connection to this level sensor.

The recent tide of economy sweeping through the oil field has caused reexamination of the oil skimmer. Recogrlizing that it - 1 - ~

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is difficult to get into the present skimmer for coating, cleaning and adjustment of its level control, has stimulated this inventor.
There is need for a basic change in configuration of this vessel which will provide more ready access to its interior and an over-all economical construction.
DISCLOSURE OF THE INVENTION
The present invention contemplates a vessel basically formed by rolling a single sheet of metal into cylindrical form, bringing the adjoining edges of the sheet together along its upper length. The adjoining edges at either or both ends are not con-nected. One end of the cylinder receives a circular plate just within the interior surFace of the cylinder and oriented normal to the axis of the cylinder, the adjoining but free edges of the cylinder being secured to clamp the circular plate .as an end wall of the vessel.
The invention further contemplates an opening at the ad-joining edges of the cylinder to receive liquid, the adjoining edges attached to each other through a nut and bolt which will draw the adjoining edges toward each other and clamp the circular plate within the interior surface of the cylinder while a seal body is arranged between the edges of the circular plate and the interior surface of the cylinder walls.
Other objects, advantages and features of this invention will become apparent to one skilled in the art upon consideration of the written specification, appended claims, and attached drawings.
BRIEF DESIGNATION OF THE DRAWINGS
Fig. 1 is a sectioned elevation of a free water knockout vessel and a subvessel mounted in the upper portion of its parent vessel, having a structure embodying the present invention, and Fig. 2 is an exploded perspective of the subvessel.
BEST MODE FOR CARRYING OUT THE INVENTION
The FWK Parent Vessel In Fig. 1, the paren-t vessel, the FWK, is disclosed as a 3~:

cylindrical vessel 1 horizontally extended. The cylindrical ves-sel is, essentially, comprised of a shell 2 with heads 3 and 4 welded to the ends of shell 2. An inlet 5 is a conduit From a producing well through which a mixture of oil and water is re-ceived by the FWK. Sufficient residence time is provided by the size of FWK 1 to enable an interface 6 to form between the lower body of water 7 gravity-separated from the upper body of oil 8. A
float 9 represents any means with which to sense the interface level and control a valve 10 in a water outlet conduit 11. As the interface 6 elevates above a certain height, the valve 10 is opened and water is drawn from body 7 through outlet conduit 11.
In the fabrication oF FWK 1, the volume will be estab-lished by the expected quantity of the oil and water mixture re-ceived. The thickness and composition of the metallic walls will be determined by the pressure at which the mixture is received.
It is common to refer to these FWK's dimensionally by their diam-eter and length, followed by the working pressure which establishes their wall thickness.
Turning to the control of oil discharged from body 8, a skimmer vessel 15 is mounted in the upper part of the FWK 1 to re-ceive this oil and control its discharge. As the level of oil body ~ above the interface 6 rises, oil from the body spills~ or skims, into subvessel 15. The collection 16 of oil in skimmer 15 is withdrawn through conduit 17 under the control oF a valve 18 connected to a detector 19 sensing the level of oil in skimmer 15.
With the overall function of the FWK 1 and skimmer 15 un-derstood, attention is Focused upon the construction of skimmer 15.
Oil Skimmer 15 Both Fias. 1 and 2 may be used to follow the disclosure of the construction of skimmer 15 under the concepts of the present invention. The -Function of the oil skimmer 15 and its relation to its parent vessel is the same as prior art oil skimmers. It is the construction of this subvessel that embodies the present invention.

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As can be seen from both figures, the skimmer 15 is basically formed from a single rectangular sheet 20. Sheet 20 has been rolled into the form oF a cylinder, edges 21 and 22 adjoining each other at the top of the cylinder as the cylinder is held in a horizontal orientation. Thus, to begin with, the cumbersome welding of plates to form a square-sided box of an oil skimmer has been radically revised. In the actual reduction to practice of the invention, sheet 20 needs only to be formed from 10-gauge sheet metal.
To mount oil skimmer 15 within its parent vessel, the first end of the cylinder 20 is welded to an interior side of the FWK 1. As disclosed in Fig. 1, the interior surface of head 3 is specifically utilized for mounting the skimmer vessel. It is only necessary to shape the First end of the cylindrical skimmer so that when it is welded to the interior head 3, the resulting cylinder 20 will extend horizontally from the FWK head. The oil outlet conduit 17 is then arranged to penetrate head 3 to communi-cate with the interior of skimmer 15.
The second end of skimmer 15 is closed by a circular plate 23. This plate 23 can be made of slightly heavier gauge than that of sheet 20, sufficiently heavy to withstand buckling under the compression necessary to clamp the plate by the walls of sheet 20. A gasket or seal body 2~ is provided between the edge of plate 23 and the interior of -the wall of sheet 20 to ensure a liquid seal for the resulting container forming skimmer 15. To clamp the circular plate 23 into orientation normal the axis of the cylinder formed by sheet 20, lugs 25 and 26 are mounted on the ex-ternal surface of sheet 20 at adjoining edges 21 and '22. A bolt 27 is extended through aligned holes formed in the lugs and a nut

2~ is threaded onto the bolt to bring the lugs toward each other and thereby clamp circular plate 23 into the position disclosed.
With a wall of the FWK forming the first end of cylindri-cal skimmer 15, and clamped plate 23 Forming the second end~ an opening 30 at the adjoining edges 21 and 22 may be formed on the top of skimmer 15. This opening 30 provides a spill-over entry into the skimmer for oil as i-ts level reaches the height of open-ing 30. The withdrawal of oil from the amount collected within the skimmer -Follows the present art. However, the construction of skimmer 15 disclosed in the drawings provides ready access to its interior for any coating needed to protect it from corrosion by the fluids. Further, the nut and bolt with which plate 23 is clamped into position may be readily disconnected and plate 23 re-leased to provide access to the interior of the skimmer For subse-quent cleaning, or adjustment oF the level detector controlling discharge oF the oil from the FWK.
Concluding Observations The present invention was conceived within the womb oF
the FWK; however, now that its period of gestation is over, there is no longer need for the invention to lurk solely within the ; Stygian of the upper reaches of the FWK. The idea is ready to be brought kicking and screaming into the world.
Wherever construction is needed to produce a vessel from a rectangular sheet oF material formed into a cylinder sealed at its ends, the present invention has utility. All that is required is that parallel edges of the sheet brought -to each other as the sheet is formed into a cylinder have sufficient freedom at each end so they may be sprung apart to allow a circular plate entry in-to the end of -the cylinder. The edges can then be brought toward each other to grip the plate at its periphery and thereby complete the closure of the vessel. Of course, a seal body between the edges of the circular plate and the inner surfaces of the cylinder can be provided. The result is a vessel closure which can be re-moved by disconnecting whatever fas-tening means has been provided between the adjacent edges of the cylinder. The sole limitation is that the edges must be provided with the freedom to enable the circular plate to be positioned within the cylinder for clamping.

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Therefore, normal entry into the vessel for the oil will be through an opening at its top, preferably oriented between the edges which are adjacent to each other and which are not sealed.
From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects herein-above set forth, together with other advantages which are obvious and inherent to the apparatus.
It will be understood that certain features and subcom-binations 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 invention.
As many possible embodiments may be made oF the invention without departing from the scope thereo-F9 it is to be understood that all matter herein set forth or shown in the accompanying draw-ings is to be interpreted in an illustrative and not in a limiting sense.

Claims

HE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A free water knockout vessel, including, a first cylindrical shell horizontally extended with ends closed, a second cylindrical vessel shell mounted within the first shell and formed from a sheet by bringing opposite parallel edges toward each other as the shell is formed from the sheet, means for sealing a first end of the second cylindrical shell to the inside surface of an end closure of the first vessel, a circular plate inserted within the walls of the second cylindrical vessel, a seal body arranged about the periphery of the circular plate and between the edges of the plate and the interior of the walls of the second cylindrical vessel, means for bringing the parallel adjacent edges of the second cylindrical vessel toward each other to clamp the circular plate with the walls of the vessel, an opening formed at the juncture of the parallel edges at the upper part of the second vessel to receive oil into the vessel, and means for discharging said oil from said second cylindrical vessel.