Patent Application
20070077528
The present invention relates to flare stacks.
During oil and gas operations, it may be necessary to flare amounts of gas. While it is desirable to flare such gas into an existing pipeline, this may not be possible due to remote location or urgency.
When a well site is being constructed, it is often necessary to bring in a flare stack. However the size and configuration of prior art flare stacks often requires that a crane be brought in to erect the stack and dangerous conditions exist during erection wherein a free end of the stack can move unexpectedly. Furthermore, many stacks require the installation of guy wires for support, which further complicates installation.
In accordance with a broad aspect of the present invention there is provided a flare stack device including: a support chassis including transport means and a stack mounted on the support chassis, the stack including a lower stack section including a lower end and an upper end and an upper stack section including a top end and a bottom end, a first pivotal connection connecting the lower stack section to the support chassis and permitting the lower stack section to pivot relative to the support chassis and a second pivotal connection between the lower stack section and the upper stack section and permitting pivotal movement therebetween to move the upper and the lower stack sections between a folded position and an erect position creating a flare stack with the lower stack section in gas communication with the upper stack section.
In accordance with another broad aspect there is provided a self erecting flare stack device including a support chassis, a lower stack section, an upper stack section, a first pivotal connection between the support chassis and the lower section and a second pivotal connection between the lower section and the upper section, the first and second pivotal connections permitting the lower stack section and the upper stack section to move between a folded position on top of the support chassis and an erect position forming an erect flare stack mounted on the support chassis.
It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
Referring to the drawings wherein like reference numerals indicate similar parts throughout the several views, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein:
The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
Since flare stacks may be useful in emergency, remote or temporary situations, it is desirable that a flare stack device be transportable. Thus a flare stack that is associated with transport means and is sized for transport may be useful. Also, it is desirable because of the nature of use of a flare stack that the flare stack be relatively easy to erect. At the same time, for environmental and health reasons it is desirable that a flare stack can flare combustion products to heights well above the ground surface. Such a flare stack may be provided by various embodiments of a flare stack device according to the present invention.
With reference to the
Support chassis 12 can be formed in various ways for transport of the flare stack. For example, the support chassis can include a transport means such as wheels, tracks, skis, etc., a hitch, or direct connection to a vehicle and/or a skid or floor, etc. for pick up such as for transport on a trailer, train car or a shipping device. In the illustrated embodiment, for example, the support chassis is formed as a trailer including a bed 23, a hitch end 24 and a plurality of wheels 26. As such the flare stack section can be transported by towing by a vehicle such as a truck.
Stack sections 14, 16 may be formed for flaring gas and to create, when erected, an operable flare stack. In particular, when erect the stack sections may be in flare communication such that gasses entering, introduced, drawn or generated in the lower stack section are communicated to the upper stack section. As such, stack sections 14, 16, may be formed of pipe forming gas flow passages and each include an interface end 28′, 28″ formed to come together to join the stack sections into a flare stack. Interface ends 28′, 28″ can be formed in various ways to come together. For example, flanges 30, as shown, seals and/or interlocking surfaces can be used. In one embodiment, the upper stack section may be formed and configured to be axially alignable with the lower stack section and with its inner conduit directly opening into inner conduit of the lower stack.
Stack sections 14, 16 may further include other components for operation, such as a lower connector end 32 for connection of a gas feed line and an upper combustion region 34 including any or all of a shroud 35, an igniter (cannot be seen), etc.
Stack sections 14, 16 can be any desired length with consideration as to material strength and stability. It is desirable that the stack sections together are capable of forming an erect flare stack that spaces the plume created at upper combustion region 34 at a safe distance from the ground. In one embodiment, the stack sections are formed to create a stack height H of greater than 25 feet, but may be quite high such as more than 75 or 100 feet high from the ground-contacting surface of the support chassis (i.e. the bottom of the wheels) to the top of the stack. In one embodiment, a flare stack device was constructed to include two 8 inch diameter stack sections each of approximately 60 feet in length to create a 120 foot flare stack when erect that is capable, possibly with air injection, of forming an approximately 200 foot flare plume. To facilitate combustion, air supply ducting 35 and/or an injection fan can be provided along one or both of the stack sections.
Although the length of one stack section can vary relative to the other stack section, the folded length can of course be reduced as much as possible by forming stack sections 14, 16 to be of roughly equal length. Support saddles 37 may be provided to permit the folded stack sections to engage together to some degree and to support the stack sections in the folded condition.
In order to permit folding of the flare stack sections, pivotal connections are provided between the parts. In particular, the illustrated flare stack device includes first pivotal connection 18 and second pivotal connection 20. These pivotal connections permit the parts to pivot about one another to move between the folded and erect positions. The pivotal connections may be rugged to withstand the stresses arising there. In the illustrated embodiment, the first pivotal connection includes a clevis 36 mounted on the support chassis, a bracket 38 connected to the lower stack section with a pivot pin 40 connecting therebetween. Second pivotal connection 20, in the illustrated embodiment, includes a hinge between the stack sections.
Flare stack device 10 may also include other components such as auxiliary lines 42, such as for example any or all of, secondary stack pipes, a shooter tube, and/or a pilot line. Any such lines that are required to extend the full length of the erect flare stack along both stack sections can either be formed to bend or flex adjacent interface ends 28′, 28″ or may be formed in sections also including interfacing ends 44′, 44″ to permit the sections to be joined to form a continuous line when the flare stack device is erected.
To be self-erecting, the flare stack system may include a drive system to drive the movement of the stack sections about the pivotal connections. The drive system may include various mechanisms such as hydraulics, pneumatics, mechanical screw drives, etc. In the illustrated embodiment, the drive system includes a lower hydraulic cylinder 50 acting about first pivotal connection 18 and an upper hydraulic cylinder 52 acting about the second pivotal connection. Of course, any drive system should be selected to provide sufficient power and to withstand stresses during operation. A drive system with capability to control both folding and erecting movement about its pivotal connection is desired. A drive system with control during lifting and lowering of the stacks is desirable such that the movement of the stack is not hindered by action of gravity. One example of a drive system that may exert both push and pull about a pivotal connection is, for example, a double acting cylinder. In one example embodiment, to lift the lower stack section lower hydraulic cylinder 50 was selected to be 10 inch four stage cylinder with a double acting capability in the first stage and the upper hydraulic cylinder was selected to be a 6-inch single stage double acting cylinder. These cylinders may be powered by, for example, an engine and a control system, which may be mounted on the support chassis, if desired.
To provide strength to the flare stack device and/or to support and maintain the spacing of the various lines, a bracing arrangement 56 may be mounted along the flare stack sections. In the illustrated embodiment, bracing arrangement 56 extends along the upper and lower flare sections and acts as the connection points for first pivotal connection 18 and lower hydraulic cylinder 50.
A flare stack may require stabilization, when erect. Stabilization may be provided by guy wires, sometimes also termed guide wires, connected between the flare stack sections and ground anchors. However, where it is desired to avoid ground disturbance as much as possible, outriggers 60 may be useful. Outriggers 60 may be mounted on the support chassis and may be manually or automatically extendable outwardly, as by pivoting, telescopic extension, etc., from the support chassis. In the illustrated embodiment, four outriggers are pivotally mounted on the support chassis and are expandable by hydraulic cylinders 61. Outriggers 60 may each include a ground-engaging pad 62 attached or positionable at their outboard ends to permit operation in many unstable ground conditions.
In one embodiment, a cylinder may be provided to drive each outrigger independently such that the flare stack can be self-leveling through the outriggers.
While four outriggers are shown, it will be appreciated that fewer or more outriggers may be used for stabilization, as desired. In one embodiment, however, outriggers have been useful to stabilize an erected flare stack of greater than 75 and 100 feet in height without the need for guy wires.
If further support is desired, guy wires (not shown) may be connected between the outriggers and the stack sections, which become tightened when the outriggers are extended.
In one embodiment, the flare stack may include a high liquid level protector such as a high level shut down float that can be actuated to allow the wellhead to be shut-in if liquid migrates from a source connected at up to the flare stack.
With reference to
Of course, variations can be made to the various components of the flare stack device from those illustrated here. For example, in
A link arrangement is provided to facilitate movement about hinge 84. The link arrangement includes a pair of link connections 86a, 86b pivotally connected together at one of their ends through a main pivot pin 88. At their opposite ends, each link connection 86a, 86b is connected to a pivot pin 90a, 90b, respectively, each respectively secured to one of the stack sections. One or more drive cylinders 52b can be connected as by bearing ends 92 to exert a driving force at main pivot pin 88 to thereby drive movement of link connections 86a, 86b, through a scissor link action. By displacing pivot pin 88, cylinders 52b cause links 86a, 86b to be moved. This drives the links about their pivotal connections 88, 90a, 90b which in turn pushes or pulls on stack sections 16b, 14b to thereby drive rotation about hinge 84. Cylinders 52b are pivotally connected, as shown at bearing 93, to an anchor point on one of the stack sections in the pivotal connection, which in this illustration is stack section 14b, to permit the pivotal movement through which the cylinders will move during their operation.
To secure and stabilize connections between cylinders 52b, and link connections 86a, 86b to the stack sections, brackets 94, 96, 98 can be formed where desired. Such brackets can accommodate the pivot pins and can further stabilize and secure the stack sections 14b, 16b and auxiliary lines 42b.
In the illustrated embodiment, links 86a, 86b their associated pivots 88 and 90a, 90b and cylinders 52b are duplicated on either side of the pivotal connection, but it is to be appreciated that a similar arrangement could be configured using only a single set of parts or multiples in excess of two, if desired. Where desired, connections can be made between the duplicated parts to strengthen the parts and to coordinate their movement. For example, in the illustrated embodiment bearing tube 99a extends between links 86b and webs 99b are included to provide additional support.
Although the illustrated flare stacks show only a lower stack section and an upper stack section, the technology described herein permit the construction and operation of flare stacks including two or more stack sections, each connected in series by pivotal connections permitting them to be moved between a folded condition and an erected condition, where the stack sections are positioned one above the other all in gas communication. For example, a stack can include a lower stack section, a plurality of stack sections thereabove. The lower stack section may, at its lower end, be pivotally mounted to a support chassis and, at its upper end, be pivotally connected the first of a series of pivotally connected stack sections. Drive systems may be provided at each pivotal connection to permit the stack to be self erecting/folding.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are know or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 USC 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for”.
