BURN PIT AND REFRACTORY BRICK FOR THE BURN PIT

Description

BACKGROUND

In the oil and gas industry, hydrocarbon processing or separation facilities are used to separate components of produced fluids or further process separated components. Ground flares are used at these facilities to burn off any excess gas that is a byproduct of separating or processing hydrocarbons. Ground flares may also be used in drilling or workover operations to manage associated gas that may enter the drilling mud from a reservoir. Ground flares need to be reliable to ensure proper handling of the excess/associated gas which, in turn, affects the safety of people and the environment. One of the primary challenges with ground flares is flame deflection due to wind. Specifically, wind deflects the flames from the ground flares into and behind the refractory wall. The flames then may damage the components that make up the ground flare and the burn pit.

SUMMARY

This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

In one aspect, embodiments disclosed herein relate to a burn pit. The burn pit may include a burn pit basin, a refractory passage, a burner shaft, and a refractory sleeve. The burn pit basin is delineated by at least a first side wall, a refractory wall, and a second side wall. The refractory passage extends from the burn pit basin through the refractory wall. The burner shaft is disposed within the refractory passage and is configured to deliver a combustible gas to a flare tip structure at the burn pit basin. The flare tip structure ignites the combustible gas to create a flame directed towards the burn pit basin. The refractory sleeve surrounds at least a portion of the burner shaft and is configured to protect the burner shaft from damage caused by the flame.

In another aspect, embodiments disclosed herein relate to a method. The method may include forming a burn pit basin by building a first side wall, a refractory wall, and a second side wall; extending a refractory passage from the burn pit basin through the refractory wall; surrounding at least a portion of a burner shaft with a refractory sleeve; extending the burner shaft having the refractory sleeve through the refractory passage. The method may further include transporting a combustible gas through the burner shaft to a flare tip structure at the burn pit basin and igniting the combustible gas using the flare tip structure to create a flame directed towards the burn pit basin; and protecting the burner shaft from damage caused by the flame using the refractory sleeve.

Other aspects and advantages will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

Specific embodiments of the disclosed technology will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency.

FIG. 1 shows a schematic diagram top view of a burn pit in accordance with one or more embodiments.

FIG. 2 shows a schematic diagram angled side view of a refractory sleeve in accordance with one or more embodiments.

FIG. 3A shows a schematic diagram side view of the burn pit in accordance with one or more embodiments.

FIG. 3B shows a schematic diagram side view of the burn pit in accordance with one or more embodiments with a stainless steel backing plate.

FIG. 4 shows a schematic diagram of a passage formed by the concrete boxes in accordance with one or more embodiments.

FIG. 5A shows a schematic angled side view of a concrete box in accordance with one or more embodiments.

FIG. 5B shows a schematic side view of the concrete box in accordance with one or more embodiments.

FIG. 6A shows a schematic diagram of the refractory bricks in accordance with one or more embodiments.

FIG. 6B is a schematic cross-sectional diagram taken in the B-B direction of FIG. 6A.

FIG. 7 shows a flowchart in accordance with one or more embodiments.

DETAILED DESCRIPTION

In the following detailed description of embodiments of the disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to one of ordinary skill in the art that the disclosure may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

Throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as an adjective for an element (i.e., any noun in the application). The use of ordinal numbers is not to imply or create any particular ordering of the elements nor to limit any element to being only a single element unless expressly disclosed, such as using the terms “before”, “after”, “single”, and other such terminology. Rather, the use of ordinal numbers is to distinguish between the elements. By way of an example, a first element is distinct from a second element, and the first element may encompass more than one element and succeed (or precede) the second element in an ordering of elements.

In the following description of FIGS. 1-7, any component described with regard to a figure, in various embodiments disclosed herein, may be equivalent to one or more like-named components described with regard to any other figure. For brevity, descriptions of these components will not be repeated with regard to each figure. Thus, each and every embodiment of the components of each figure is incorporated by reference and assumed to be optionally present within every other figure having one or more like-named components. Additionally, in accordance with various embodiments disclosed herein, any description of the components of a figure is to be interpreted as an optional embodiment which may be implemented in addition to, in conjunction with, or in place of the embodiments described with regard to a corresponding like-named component in any other figure.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a circuit breaker” includes reference to one or more of such circuit breakers.

Terms such as “approximately,” “substantially,” etc., mean that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

It is to be understood that one or more of the steps shown in the flowcharts may be omitted, repeated, and/or performed in a different order than the order shown. Accordingly, the scope disclosed herein should not be considered limited to the specific arrangement of steps shown in the flowcharts.

Although multiple dependent claims are not introduced, it would be apparent to one of ordinary skill that the subject matter of the dependent claims of one or more embodiments may be combined with other dependent claims.

Ground flares exist in various forms, such as vertical flare stacks, enclosed/concealed flares, and burn pit flares. The disclosure herein relates to burn pit ground flares. A burn pit ground flare is a single or multi-point flare positioned horizontally over a dedicated pit. The pit often has a refractory wall protecting the operative equipment of the ground flare. A burn pit ground flare may be associated with oil and gas operations and may be used to burn off gas and handle emergency de-pressurization of systems. While ground flares are primarily used to burn off hydrocarbon gasses, a ground flare may be used to burn off any hydrocarbon (such as oil) without departing from the scope of the disclosure herein.

In view of the above, burn pit ground flares need to be reliable to protect the safety of people and the environment. One of the primary challenges with ground flares is flame deflection due to wind. Specifically, wind deflects the flames from the ground flares into/behind the refractory wall. The flames then may damage the components that make up the ground flare and the burn pit. Accordingly, the present disclosure outlines systems and methods for a burn pit ground flare that mitigates deflection of the flames and damage from the flames to the operative equipment into/behind the refractory wall.

FIG. 1 shows a schematic diagram top view of a burn pit 10 in accordance with one or more embodiments. As shown in FIG. 1, the burn pit 10 includes a burn pit basin 12. The burn pit basin 12 is delineated by four sides: a first side wall 121, a second side wall 123, a back wall 122, and a front wall 124. In accordance with one or more embodiments, the first side wall 121, the second side wall 123, the back wall 122, and the front wall 124 of the burn pit basin 12 may be a brick wall. Behind the back wall 122 of the burn pit basin 12, there is a refractory wall 16 (also known as a burner wall). In accordance with further embodiments, the refractory wall 16 itself can constitute the back wall 122 of the burn pit basin 12.

The burn pit 10 further includes two burner shafts 18. In accordance with one or more embodiments, each of the burner shafts 18 includes a pipe protected by a refractory sleeve 20. The burner shaft 18 has a first end 181 which is facing the burn pit basin 12. Start from the first end 181, the burner shaft 18 and the refractory sleeve 20 extend through the back wall 122 and the refractory wall 16, and into a refractory passage 30. The refractory passage 30 is described in detail with reference to FIGS. 3-5. In accordance with one or more embodiments, a second end of the burner shaft 18 is in hydraulic communication with a source of hydrocarbons (not shown). For example, the burner shaft 18 may connect to an outlet of a hydrocarbon processing/separation plant or the burner shaft 18 may connect to a mud system of a drilling or workover rig. A fluid (such as hydrocarbon gas) coming from the source and flowing through the burner shaft can flow into the burn pit basin.

Although there are two burner shafts 18 shown in FIG. 1, there can be more or less burner shafts 18 extending from the back wall 122 of the burn pit basin 12.

As outlined above, the burner shaft 18 is surrounded by the refractory sleeve 20. FIG. 2 shows a schematic diagram angled side view of a refractory sleeve 20 in accordance with one or more embodiments. Specifically, FIG. 2 shows a side view of the refractory sleeve 20. The refractory sleeve 20 is used to protect the burner shaft 18 from any damages caused by high heat. In accordance with one or more embodiments, the refractory sleeve 20 includes two or more sections.

FIG. 2 shows the refractory sleeve 20 being made of three sections: a first section 20A, a second section 20B, and a third section 20C. In accordance with one or more embodiments, an expansion joint is located between two adjacent sections. Specifically, a first expansion joint 21A is located between the first section 20A and the second section 20B, a second expansion joint 21B is located between the first section 20A and the third section 20C, and a third expansion joint 21C is located between the second section 20B and the third section 20C.

FIG. 2 shows the first expansion joint 21A, the second expansion joint 21B, and the third expansion joint 21C of the refractory sleeve 20 in an unexpanded position. The first expansion joint 21A, the second expansion joint 21B, and the third expansion joint 21C enable the first section 20A, second section 20B, and third section 20C to move away from one another when heat is applied to the refractory sleeve 20. Thus, the refractory sleeve 20 has a range of diameters depending on the expansion allowed by the first expansion joint 21A, the second expansion joint 21B, and the third expansion joint 21C.

In accordance with one or more embodiments, the length of the first section 20A, the second section 20B, and the third section 20C each spans 120 degrees such that the first section 20A, the second section 20B, and the third section 20C can form a cylindrical pipe and the expansion joints when connected to one another. Furthermore, the edge of the first section 20A, the second section 20B, and the third section 20C along their longest direction may have a shape of Z as shown in FIG. 2. In accordance with one or more embodiments, the expansion joints 21A, 21B, 21C are formed in a corrugated ‘Z’ locking shape. This shape enables self-positioning and self-centering of sleeve pieces. The expansion joints 21A, 21B, 21C may be filled with ceramic fiber blanket cushions to enable thermal expansion and contraction. The ceramic fiber may also work as sealing agent at the expansion joints 21A, 21B, 21C.

In accordance with one or more embodiments, the first section 20A, the second section 20B, and the third section 20C may be made of a material resistant to high heat, such as high alumina content refractory material. The ability of the refractory sleeve 20 to expand and contract using the first expansion joint 21A, the second expansion joint 21B, and the third expansion joint 21C will prevent the refractory sleeve 20 from becoming deformed or damaged due to the thermal expansion caused by heat of the flames flowing through the burner shaft 18.

FIG. 3A shows a schematic diagram side view of the burn pit 10 in accordance with one or more embodiments. Components shown in FIG. 3A that are the same as or similar to the components shown in FIGS. 1-2 have not been redescribed for purposes of readability and have the same description and function as outlined above.

FIG. 3A shows two burner shafts 18 each located in a corresponding refractory sleeve 20. The burner shaft 18/refractory sleeve 20 pairs extend through a single refractory passage 30. In accordance with one or more embodiments, the refractory passage 30 may be begin behind the back wall 122 and extend into the refractory wall 16. One or more concrete boxes 130 may be located after the refractory wall 16 and/or back wall 122 to form the refractory passage 30. In accordance with one or more embodiments, a part of the refractory passage 30 can extend through both the refractory wall 16 and the back wall 122.

In accordance with one or more embodiments, there is a void 302 between the inner surface 301 of the refractory passage 30 (i.e., the inner surface of the concrete boxes 130) and the refractory sleeves 20. The refractory passage 30 is open to atmosphere at the side of the refractory passage 30 furthest from the burn pit basin 12. The refractory passage 30 being open to the environment prevents the formation of hazardous gases or the accumulation of hydrocarbon byproducts in an enclosed space and potential explosions.

In accordance with one or more embodiments, each burner shaft 18 is surrounded by the refractory sleeve 20 across the entire length of the burner shaft 18. In accordance with other embodiments, only a portion of the length of the burner shaft 18 is surrounded by the refractory sleeve 20. For example, the refractory sleeve 20 may extend predetermined meters from the first end 181 of the burner shaft 18 into the refractory passage 30.

The first end of burner shaft 18, the refractory sleeve 20 around the first end of burner shaft 18, and an ignitor 140, which is aside the first end of the burner shaft 18, constitute a burn pit flare tip structure 14. According to one or embodiments, the ignitor 140 and cables to the ignitor 140 can be protected by an ignitor pipe parallel to the burner shaft 18.

In accordance with one or more embodiments, the void 302 located in the opening of the refractory passage 30 near the refractory wall 16, may be filled with castable refractory and ceramic fiber material, not pictured, and further covered by a stainless steel backing plate 60 to ensure flame impingement protection. The stainless steel backing plate 60 is further shown in FIG. 3B.

FIG. 4 shows a schematic diagram side view of the refractory passage 30 formed by a plurality of concrete boxes 130 in accordance with one or more embodiments. FIG. 5A shows a schematic angled side view of a concrete box 130 in accordance with one or more embodiments. FIG. 5B shows a schematic side view of the concrete box 130 in accordance with one or more embodiments.

In accordance with one or more embodiments and as shown in FIG. 4, the refractory passage 30 may be formed by one or more concrete boxes 130. As shown in FIG. 5A and FIG. 5B, each concrete box 130 includes two support portions 131, two side plates 132, and a top plate 133. In accordance with one or more embodiments, the support portion 131, side plate 132, and top plate 133 each has a rectangular shape.

In accordance with one or more embodiments, the length, L, of the support portion 131 may be equal to the length of the side plate 132. The width, D, of the support portion 131 may be greater than the thickness of the side plate 132. The side plate 132 is supported on top of the support portion 131. The top plate 133 is located on top of the two side plates 132 and is, thus, supported by the two side plates 132.

There may be rounded corners between the top plate 133 and the side plate 132. The width, W, of the top plate 133 may be equal to the length, L, of the side plate 132. The height, H, of side plate 132 may be greater than the diameter of the biggest refractory sleeve 20 that the refractory passage 30 accommodates.

In accordance with one or more embodiments, the support portion 131 should have a certain thickness to stably support the side plate 132 and top plate 133. In accordance with one or more embodiments, the length, L, of side plate 132 ranges from 0.8 meters to 1.2 meters.

In further embodiments and as shown in FIG. 4, each concrete box 130 in the refractory passage 30 may have one or more lifting holes 134. Though the lifting hole 134 shown in FIG. 4 is a rectangular holes, the lifting hole 134 can be any shape without departing from the scope of the disclosure herein. By using the lifting holes 134, the concrete box 130 can be easily installed and removed during maintenance activities, test and inspection. In accordance with one or more embodiments, the rear part of the burner shaft 18 is protected from heat by concrete boxes 130 arranged in row of multiple pieces. Using multiple concrete boxes 130 instead of a single concrete box along the length of the refractory passage 30 reduces weight and allows the concrete boxes 130 to be easily lifted during maintenance operations.

Turning back to FIG. 3A, a refractory brick layer 50 may be disposed on the upper surface of the concrete boxes 130, and a fire proof layer 40 may be disposed on the upper surface of the refractory brick layer 50. In further embodiments, the refractory brick layer 50 may be located around the refractory sleeve 20 in a void created between the refractory sleeve 20 and the inner surface of the refractory passage 30 (such as the inner surface of the concrete boxes 130). FIGS. 6A and 6B show the refractory brick layer 50 surrounding the refractory sleeve 20 in this manner. In this case, the fire proof layer 40 may be directly on top of the concrete boxes 130. The fire proof layer 40 material may include low density cementitious compound imbedded with fibers. The fire proof layer 40 may be sprayed upon concrete boxes to protect concrete from flame and control heat exposure so that cracks could not generate in concrete boxes.

The refractory passage 30, the fire proof layer 40 and the refractory brick layer 50 prevent deflected flames from the burn pit 10 from damaging ignitor junction boxes, metal structures, and other operative equipment located inside of or behind the refractory wall 16. Herein, the term “behind” refers to the side of the refractory wall 16 located furthest away from the flare tip structure 14.

In accordance with one or more embodiments, the burn pit flare tip structure 14 of FIG. 1, 3a, or 3b may be surrounded by self-supportive muffle blocks, and supported by refractory bricks, i.e., the refractory brick layer 50 outlined above. FIG. 6A shows a schematic diagram of the refractory bricks layer in accordance with one or more embodiments. The eight refractory blocks shown in FIG. 6A is a representation of the refractory blocks. FIG. 6B is a schematic cross-sectional diagram taken in the B-B direction of FIG. 6A.

As shown in FIG. 6A, there are eight refractory blocks which delineate an opening 80. The burner shaft 18 surrounded by the refractory sleeve 20 may be disposed within the opening 80. The eight refractory bricks include a small sized brick 81, a middle sized brick 82, and a large sized brick 83. As can be seen in FIGS. 6A and 6B, each of the block has a horizontal upper surface 801, a horizontal lower surface 802, a slope backward surface 803, a vertical front surface 804, a left side surface 805, and a vertical right side surface 806. Rear portion of muffle blocks are anchored into the wall.

The size of the lower surface 802 is larger than that of the upper surface 801. The shape and area of the upper surface 801 of the large sized brick 83 is the same as that of the lower surface 802 of the middle sized brick 82, and the shape and area of the upper surface 801 of the middle sized brick 82 is the same as that of the lower surface 802 of the small sized brick 81.

The left side surface 805 of the middle sized brick 82 has a curved shape or arc shape that corresponds with the shape of the burn pit flare tip structure 14. At the right side and the left side of the opening 80, the small sized brick 81 sits on the middle sized brick 82, and the middle sized brick 82 sits on the large sized brick 83. On the upper side of the opening 80, there is a middle sized brick 82 with the surface 805 located on the lower portion of the middle sized brick 82, i.e., closest to the opening 80. On the lower side of the opening 80, there is also a middle sized brick 82 with the surface 805 located on the upper portion of the middle sized brick 82, i.e., closest to the opening. On the middle sized brick 82, holes 807 for the ignitor pipes are formed. The holes may form a part of the surface 805. With such a self-supportive structure, the collapsing or falling of the bricks around the burn pit flare tip structure 14 can be prevented or alleviated.

In accordance with further embodiments, the burn pit 10 may further include a junction box and a cable connected to the junction box, not pictured. The junction box can be used to control the ignitor 140 and can be located away from the radiation zone to prevent overheating and melting. For example, the junction box may locate at a predetermined distance from the opening of the refractory passage 30 away from the refractory wall 16. The cable may be buried underground to be protected from the heat of the burn pit 10.

FIG. 7 shows a flowchart in accordance with one or more embodiments. The flowchart outlines a method of forming and operating a burn pit 10. While the various blocks in FIG. 7 are presented and described sequentially, one of ordinary skill in the art will appreciate that some or all of the blocks may be executed in different orders, may be combined or omitted, and some or all of the blocks may be executed in parallel. Furthermore, the blocks may be performed actively or passively.

In S700, a burn pit basin 12 is formed by building a first side wall 121, a refractory wall 16, and a second side wall 123. In accordance with one or more embodiments, a back wall 122 and a front wall 124 may be located between the first side wall 121 and the second side wall 123 to delineate the burn pit basin 12 and the refractory wall 16 may be located behind the back wall 122 (i.e., located adjacent to the side of the back wall that is furthest away from the burn pit basin).

In S702, a refractory passage 30 is extended from the burn pit basin 12 through the refractory wall 16. In accordance with one or more embodiments, the refractory passage 30 may be a passage way cut into the back wall 122 and/or the refractory wall 16. In other embodiments, the refractory passage 30 may be formed by one or more concrete boxes 130 located in the passage way cut into the back wall 122 and/or the refractory wall 16.

In accordance with one or more embodiments, the concrete boxes 130 may be created by forming two side plates 132 on corresponding support portions 131 in a thickness direction and forming a top plate 133 supported by the two side plates 132 in a length direction. In accordance with one or more embodiments, a length of the support portion 131 is equal to a length of the side plate 132 and a width D of the support portion 131 is greater than a thickness of the side plate 132. A lifting hole 134 may also be machined into the top plate 133.

In S704, at least a portion of a burner shaft 18 is surrounded with a refractory sleeve 20. In accordance with one or more embodiments, the refractory sleeve 20 is created using two or more sections (20A, 20B, 20C). Neighboring sections (i.e., 20A and 20B) may be connected to one another using an expansion joint (i.e., 21A) to form a cylinder. Furthermore, the edge of the sections (20A, 20B, 20C) along a longest direction of the section (20A, 20B, 20C) may be formed in a Z-like shape.

In S706, the burner shaft 18 having the refractory sleeve 20 is extended through the refractory passage 30. In accordance with one or more embodiments, extending the burner shaft 18 and the refractory sleeve 20 through the refractory passage 30 may cause a void 302 to be created between the refractory sleeve 20 and an inner surface of the refractory passage 30. At least a portion of the void 302 may be filled with castable refractory and ceramic fiber material. Furthermore, the castable refractory and ceramic fiber material may be backed by a stainless steel backing plate 60.

In accordance with one or more embodiments, the castable refractory and ceramic fiber material is located in the portion of the void 302 closest to the burn pit basin 12 and the backing plate 60 may be located behind the castable refractory and ceramic fiber material (i.e., adjacent to the end of the castable refractory and ceramic fiber material furthest away from the burn pit basin 12). In further embodiments, a refractory brick layer 50 may be formed around the refractory sleeve 20 in the void created between the refractory sleeve 20 and the inner surface of the refractory passage 30. The refractory brick layer 50 may be used to structurally support the refractory sleeve 20.

In S708, a combustible gas, not pictured, is transported through the burner shaft 18 to a flare tip structure 14 at the burn pit basin 12 and the combustible gas is ignited using the flare tip structure 14 to create a flame, not pictured, directed towards the burn pit basin 12. In S710, the burner shaft 18 is protected from damage caused by the flame using the refractory sleeve 20.

In accordance with one or more embodiments, the refractory brick layer 50 and/or the castable refractory and ceramic fiber material aids in preventing the flame from blowing back into the refractory passage 30, thus protecting the equipment behind the refractory wall 16 from being damaged by the flame. Furthermore, the refractory sleeve 20 protects the burner shaft 18 if any flames manage to flow through the refractory passage 30. The sectional make-up with expansion joints prevents the refractory sleeve 20 from being damaged by the flame because the sections may expand and contract without damaging the structure when heat is introduced to the refractory sleeve 20.

Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.