CLAIM OF PRIORITY

[0001] This application claims priority to U.S. Patent Application No.

15/997,591 filed on June 4, 2018, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

[0002] This disclosure relates to heat transfer apparatuses for cooling fluid flowing through pipelines in oil and gas applications.

BACKGROUND

[0003] Heat pipes are used for cooling flowing fluids in various applications

(for example, such as electronics, oil and gas, space craft heat removal systems, solar systems, and heating, ventilation, and air conditioning systems) that require heat dissipation for maintaining the mechanical integrity of surrounding system

components. Heat pipes typically have a high thermal conductivity and can rely on changes between liquid and vapor phases of heat transfer fluids for operation. In some examples, cooling a high temperature fluid flowing in oil and gas pipelines may be desirable for reducing the temperature to one that is safe for pipelines made of certain materials. Such cooling aspects can also affect associated manufacturing approaches, installation of cooling systems, and operational costs. SUMMARY

[0004] This disclosure relates to heat transfer apparatuses used for cooling fluid flowing through pipelines in various oil and gas contexts. An example heat transfer apparatus is provided as a pipe segment (for example, such as a pipe spool) that carries multiple pipe elements (for example, such as heat pipes). The pipe elements extend radially outward from a centerline of the pipe segment such that the pipe elements span a wall of the pipe segment. Therefore, a portion of each pipe element is disposed internal to the pipe segment and contacts a fluid flowing axially through the pipe segment, while a portion of each pipe element is disposed external to the pipe segment. The pipe elements are arranged in an axial array along the wall of the pipe segment and contain a working fluid. The working fluid absorbs heat from the fluid flowing through the pipe segment and releases heat through the pipe element to an external environment that surrounds the pipe segment. An internal flow obstruction is arranged coaxially with the pipe segment and diverts the fluid flowing axially through the pipe segment in a radially outward direction to maximize contact between the fluid and the pipe elements for improving an efficiency of the heat transfer between the fluid and the pipe elements.

[0005] In one aspect, a heat transfer apparatus includes a tubular wall defining a lumen and multiple pipe elements arranged about a circumference of the tubular wall and passing through the tubular wall. The lumen is configured such that fluid flows through the lumen of the heat transfer apparatus. Each pipe element of the multiple pipe elements includes an interior portion located within the lumen of the tubular wall and configured to absorb heat from the fluid that flows through the lumen and includes an exterior portion located exterior to the tubular wall and configured to release at least a portion of the heat absorbed at the interior portion to an ambient environment.

[0006] Embodiments may provide one or more of the following features.

[0007] In some embodiments, each pipe element of a subset of the multiple pipe elements is arranged in a circumferential row at a same axial position along the tubular wall.

[0008] In some embodiments, the multiple pipe elements include multiple circumferential rows of pipe elements arranged at different axial positions along the tubular wall.

[0009] In some embodiments, each pipe element of the multiple pipe elements includes a working fluid that evaporates upon absorbing heat from the fluid flowing through the lumen of the tubular wall along the interior portion of the pipe element and that condenses upon releasing heat along the exterior portion of the pipe element to the ambient environment.

[0010] In some embodiments, each pipe element of the multiple pipe elements is configured such that the working fluid flows in a gas phase from the interior portion to the exterior portion upon absorbing heat from the fluid flowing through the lumen of the tubular wall.

[0011] In some embodiments, each pipe element of the multiple pipe elements is configured such that the working fluid flows in a liquid phase from the exterior portion to the interior portion upon releasing heat to the ambient environment. [0012] In some embodiments, each pipe element of the multiple pipe elements further includes a layer of material that facilitates flow of the fluid in the liquid phase via capillary action.

[0013] In some embodiments, each pipe element of the multiple pipe elements includes an adiabatic portion that spans the tubular wall between the interior and exterior portions.

[0014] In some embodiments, each pipe element of the multiple pipe elements includes multiple fins that facilitate heat transfer from the pipe element to the ambient environment.

[0015] In some embodiments, each pipe element of the multiple pipe elements extends in a radial direction with respect to a central axis of the tubular wall.

[0016] In some embodiments, the multiple pipe elements are configured such that an exit temperature of the fluid flowing out of the heat transfer apparatus is about 30°C to about 70°C cooler than an entry temperature of the fluid flowing into the heat transfer apparatus.

[0017] In some embodiments, the multiple pipe elements are made of one or more materials including coated carbon steel, copper, and alloys.

[0018] In some embodiments, the working fluid includes water, methanol, or acetone.

[0019] In some embodiments, the heat transfer apparatus further includes a flow obstruction arranged coaxially with the tubular wall.

[0020] In some embodiments, the flow obstruction is configured to divert fluid flowing through the heat transfer apparatus radially outward towards the multiple pipe elements.

[0021] In some embodiments, the lumen has a substantially annular cross- sectional shape.

[0022] In some embodiments, a cross-sectional area of the lumen is equal to a cross-sectional area of a flow line to which the heat transfer apparatus is installed.

[0023] In some embodiments, the flow obstruction has a smooth surface profile that prevents a pressure drop in the fluid as the fluid flows through the tubular wall.

[0024] In another aspect, a fluid management system includes a heat transfer apparatus configured to be installed to a first fluid flow line, a second fluid flow line by which fluid flowing through the first fluid flow line can bypass the heat transfer apparatus, a third fluid flow line by which fluid can be drained from the heat transfer apparatus, and multiple valves by which fluid can be managed with respect to the heat transfer apparatus, the first fluid flow line, the second fluid flow line, and the third fluid flow line. The second fluid flow line is configured to be installed to the first fluid flow line in parallel with the heat transfer apparatus. The third fluid flow line is configured to be installed to the heat transfer apparatus. The heat transfer apparatus includes a tubular wall defining a lumen and multiple pipe elements arranged about a circumference of the tubular wall and passing through the tubular wall. The lumen is configured such that fluid flows through the lumen of the heat transfer apparatus.

Each pipe element of the multiple pipe elements includes an interior portion located within the lumen of the tubular wall and configured to absorb heat from the fluid that flows through the lumen and includes an exterior portion located exterior to the tubular wall and configured to release at least a portion of the heat absorbed at the interior portion to an ambient environment.

[0025] In another aspect, a method of cooling a fluid flowing through a heat transfer apparatus includes flowing the fluid through a lumen of a tubular wall carrying multiple pipe elements arranged about a circumference of the tubular wall and passing through the tubular wall, absorbing heat from the fluid along interior portions of the multiple pipe elements that are located within the lumen as the fluid flows through the lumen, and releasing heat from exterior portions of the multiple pipe elements that are located exterior to the tubular wall as the fluid flows through the lumen.

[0026] The details of one or more embodiments are set forth in the

accompanying drawings and description. Other features, aspects, and advantages of the embodiments will become apparent from the description, drawings, and claims.

DESCRIPTION OF DRAWINGS

[0027] FIG. 1 is a perspective view of an example pipe segment used to transfer heat out of fluid flowing through a well flow line.

[0028] FIG. 2 is front view of the pipe segment of FIG. 1.

[0029] FIG. 3 is front cross-sectional view of the pipe segment of FIG. 1. [0030] FIG. 4 is side cross-sectional view of a central wall of the pipe segment of FIG. 1.

[0031] FIG. 5 is a cross-sectional view of one of multiple example pipe elements carried by the central wall of the pipe segment of FIG. 1.

[0032] FIG. 6 is a graph showing an example temperature drop across the pipe segment of FIG. 1.

[0033] FIG. 7 is a flow chart illustrating an example method of cooling a fluid flowing through the pipe segment of FIG. 1.

[0034] FIG. 8 is a schematic diagram of an example fluid management system that includes the pipe segment of FIG. 1.

DETAILED DESCRIPTION

[0035] FIGS. 1-4 illustrate multiple views of a pipe segment 100 (for example, such as a pipe spool) that is designed to be installed in-line with a well flow line (for example, such as an oil, gas, or water well flow line) for cooling fluid that flows through the well flow line in various oil and gas applications. The pipe segment 100 includes a central wall 102, multiple pipe elements 104 disposed across the central wall 102, a flow diversion component 106 (for example, such as a flow obstruction), arranged coaxially with the central wall 102, and rims 108 located at opposite ends 110, 112 of the central wall 102 for installation of the pipe segment 100 to a well flow line.

[0036] The central wall 102 is generally cylindrical in shape and defines multiple openings 114 through which the pipe elements 104 respectively pass. The central wall 102 and the flow diversion component 106 together define a lumen 118. The lumen 118 is centered along a central axis 116 of the pipe segment 100 (for example, such as of the central wall 102) such that the lumen 118 has a generally annular cross-sectional shape, as provided by the coaxial arrangement of the flow diversion component 106 within the central wall 102 and accounting for minor deviations from the annular shape owing to extension of the pipe elements 104 into the lumen 118. The flow diversion component 106 is a solid mass that serves as an obstruction to flow through the lumen 118. The flow diversion component is radially symmetric with respect to the central axis 116 and extends the length of the central wall 102. The flow diversion component 106 includes a central portion 120 of constant diameter and two rounded, generally semi-ellipsoidal shaped end portions 122. Accordingly, the flow diversion component 106 has a general structure of a solid, closed pipe or tube. Fluid enters the lumen 118 at the first end 110 of the central wall 102, flows in a direction 124 around the flow diversion component 106 upon encountering a first end portion 122 so that the fluid is cooled by the pipe elements 104, and exits the lumen 118 at the second end 112 of the central wall 102, as will be discussed in more detail below.

[0037] The central wall 102 typically has an inner diameter of about 0.1 meters

(m) to about 1.6 m, a wall thickness of about 0.2 millimeters (mm) to about 60 mm, and a length in a range of about 1 m to about 5 m. The central portion 120 of the flow diversion component 106 typically has a diameter of about 0.05 m to about 1.3 m. The rims 108 at the ends 110, 112 of the central wall 102 are formed to interface with components (for example, such as flange ends or welded joints) of the well flow line for installation of the pipe segment 100 to the well flow line. The rims 108 typically have an outer diameter of about 30 mm to about 1,300 mm and an inner diameter that is about equal to the inner diameter of the central wall 102. In some embodiments, the central wall 102, the rims 108, and the flow diversion component 106 are made of one or more materials that are corrosion and erosion resistant and that can withstand fluid and ambient temperatures of up to about 120 degrees Centigrade (°C), as well as a fluid pressure of up to about 20.7 megapascals (MPa). Example materials from which the central wall 102, the rims 108, and the flow diversion component 106 are typically made include carbon steel and stainless steel. The wall 102, the rims 108, and the component 106 may be made of the same one or more materials or from different materials.

[0038] Still referring to FIGS. 1-4, the pipe elements 104 (for example, such as heat pipes) are co-located with the openings 114 in the central wall 102 and are arranged in an array that surrounds and extends along a portion of the central axis 116. The pipe elements 104 span the central wall 102 (for example, such as pass through the openings 114) and extend radially outward with respect to the central axis 116. Therefore, a portion of each pipe element 104 is disposed internal to the central wall 102 and contacts the fluid flowing axially therethrough, while a portion of each pipe element 104 is disposed external to the central wall 102 and exposed to the ambient environment 14. [0039] Referring to FIG. 5, the pipe elements 104 are heat dissipating elements that are designed to transfer heat from a fluid of a relatively hot temperature flowing through the pipe segment 100 to an ambient environment 142 of a relatively cold temperature (for example, such as air) external to the pipe segment 100. Each pipe element 104 includes a housing 126 containing a wick material 148 and a working fluid 128 (for example, such as a heat transfer fluid) that continuously flows within the housing 126 as fluid flows through the lumen 118 of the pipe segment 100. The wick material 148 is a thin layer of material disposed along an inner surface of the housing 126 and facilitates fluid flow along the inner surface via capillary action. Spanning the central wall 102 with fluid flowing through the lumen 118, each pipe element 104 includes an evaporator section 130 located within the lumen 118, an adiabatic section 132 that passes through the central wall 102, and a condenser section 134 located external to the central wall 102. Each pipe element 104 also includes multiple fins 150 arranged along the condenser section 134 to facilitate heat transfer between the pipe element 104 and the ambient environment 142.

[0040] Heat carried by the fluid flowing through the lumen 118 of the central wall 102 is absorbed (denoted by the arrows 136) by the pipe element 104 along the evaporation section 130, thereby causing the working fluid 128 (for example, such as in a liquid phase) flowing along the wick material 148 to evaporate (denoted by the arrows 138) and flow centrally in a gas phase (for example, such as a vapor phase, denoted by arrows 140) through the adiabatic section 132 towards the condenser section 134 due to a pressure difference in the fluid between the evaporator section 130 and the condenser section 134. Once the working fluid 128 reaches the condenser section 134 in the gas phase, the ambient environment 142 external to the pipe element 104 absorbs heat (denoted by arrows 154) from the working fluid 128 through the wall of the pipe element 104, thereby causing the working fluid 128 to condense (denoted by the arrows 144) to the liquid phase along the wick material 148 and flow back (denoted by the arrows 146) towards the evaporator section 138.

[0041] The cyclical process of heat transfer to and from the working fluid 128 continues as long as fluid (for example, such as at a relatively hot temperature with respect to that of the ambient environment 142) flows through the lumen 118 of the pipe segment 100. In this manner, the fluid flowing through the lumen 118 of the pipe segment 100 serves as a heat source to the pipe element 104, while the ambient environment 142 serves as a heat sink to the pipe element 104. Along the adiabatic section 132 of the pipe segment 104, heat is neither absorbed nor lost from the working fluid 128. The temperature of fluid entering the pipe segment 100 at the first end 110 is typically in a range of about 55°C to about 1 l0°C, while the temperature of the ambient environment 142 is typically in a range of about 5°C to about 50°C. The temperature of fluid exiting the pipe segment 100 at the second end 112 is typically in a range of about 30°C to about 70°C.

[0042] The housing 126 is a closed structure with rounded end regions and typically has a length of about 5 centimeters (cm) to about 60 cm, a diameter of about 0.2 cm to about 1.0 cm, and a wall thickness of about 0.1 cm to about 0.5 cm. The wick material 148 typically has a layer thickness of about 0.1 cm to about 0.5 cm, and the working fluid 128 typically has a volume (for example, such as in a fully liquid phase) of about 10 milliliters (mL) to about 100 mL. The material formulations of the housing 126 and the wick material 148 are compatible with each other and with the working fluid 128 to ensure efficient heat transfer at the pipe element 104. For example, the housing 126 is typically made of one or more materials including aluminum, copper, steel (for example, such as coated carbon steel), or metallic alloys (for example, such as nickel). The wick material 148 typically includes one or more materials, such as metal fibers, glass fibers, or sintered powders of metals (for example, such as copper). Example working fluids 128 include water, methanol, acetone, ammonia, Rl34a, and alkali metals (for example, such as potassium and sodium). The pipe elements 104 are respectively secured to the central wall 102 at the openings 114 via an interference or shrink fit, bolts and screws, or welding.

[0043] Referring again to FIG. 2, the pipe elements 104 are distributed in an array that surrounds and extends along a portion of the central wall 102. Each row of pipe elements 104 distributed about the circumference of the central wall 102 at a same axial position may be referred to as a stage 152, such that the array includes multiple stages 152 distributed axially along the central wall 102. A defined amount of heat is lost from the fluid flowing through the pipe segment 100 at each stage 152 and depends on the number of pipe elements 104 arranged in the stage 152. That is, the amount of heat lost increases as the number of pipe elements 104 per stage 152 increases, while the amount of heat lost decreases as the number of pipe elements 104 per stage 152 decreases, such that the heat lost at each stage 152 is directly proportional to the number of pipe elements 104 within each stage 152. Accordingly, the number of pipe elements 104 per stage can be optimized, and the total number of stages 152 distributed along the axial direction can be optimized with respect to dimensions of the pipe segment 100. In some embodiments, the pipe segment 100 includes 10 to 50 pipe elements 104 per stage 152 that are spaced equidistantly apart about the circumference of the central wall 102. In some embodiments, the stages 152 are spaced about 2 cm to about 6 cm apart from one another. In some embodiments, the pipe segment 100 includes a total of 5 to 500 stages 152.

[0044] A series of stages 152 arranged axially along the central wall 102 results in a desired total heat loss across the pipe segment 100, as shown in the example graph 200 of FIG. 6. In the example graph 200, the temperature of the fluid flowing through the lumen 118 is shown qualitatively and as dimensionless, and the number of stages 152 arranged axially along the pipe segment 100 is arbitrary. As illustrated in the graph 200, the temperature of the fluid flowing through the lumen 118 is inversely related to the number of stages 152 present within the pipe segment 100. Accordingly, the heat lost from the fluid flowing through the lumen 118 is directly proportional to the number of stages 152 present within the pipe segment 100.

[0045] Referring again to FIG. 4, the pipe elements 104 are distributed about the circumference of the central wall 102. Therefore, without the presence of the flow diversion component 106, all of the fluid flowing through the lumen 118 would not have contact with the pipe elements 104 that is sufficient to achieve cooling. For example, fluid flowing past or in close proximity to the heat pipes 104 would be cooled, whereas fluid flowing in close proximity to the central axis 116 (for example, such as further away from the pipe elements 104) would not be cooled. Accordingly, the flow diversion component 106 is positioned coaxially with the central wall 102 in order to divert the fluid radially towards the pipe elements 104. Such configuration maximizes contact between all of the fluid flowing through the lumen 118 and the pipe elements 104 to provide efficient cooling of the fluid.

[0046] Referring again to FIG. 3, the end portion 122 of the flow diversion component 106 located at the entrance of the pipe segment 100 (for example, as well as the end portion 122 located at the exit of the pipe segment 100) provides a smooth surface profile that promotes a smooth, streamlined, laminar fluid flow to prevent a pressure drop across the pipe segment 100 and prevent turbulences within the lumen 118 that may otherwise occur as fluid would enter the lumen 118 along a non-smooth surface profile. In some embodiments, the flow diversion component 106 is sized (for example, such as relative to the central wall 102) such that a total cross-sectional area of the annular lumen 118 (for example, such as along the central portion 120 of the flow diversion component 106) is equal (or about equal) to a cross-sectional area of the well flow line to which the pipe segment 100 is installed. Maintaining the cross- sectional area through which the fluid flows also prevents a pressure drop across the pipe segment 100 and maintains a flow rate at which the fluid is flowing through the pipe segment 100. Fluid typically flows through the pipe segment 100 at a flow rate of about 0.9 liters per second (L/s) to about 10 L/s. On a rare occasion at which a pressure drop may occur across the pipe segment 100, a choke valve positioned upstream of the pipe segment 100 (for example, such as positioned along the fluid flow path before the pipe segment 100) can be relaxed (for example, such as opened wider) to accommodate such pressure drop.

[0047] Owing to the reduced temperature of the fluid exiting the pipe segment

100, non-metallic pipes that cannot tolerate such high entry fluid temperatures may be used downstream of the pipe segment 100 along the fluid flow path. Example materials from which the non-metallic pipes may be made include temperature-limited reinforced thermoplastic pipe (RTP) materials and reinforced thermal resin (RTR) materials. Such pipe selections can improve process safety. For example, the non- metallic materials have a temperature limitation, such that the non-metallic materials fail if the flowing fluid has a temperature higher than the thermal capability of the pipe material. Such pipe selections can also quicken tie-in activities. For example, reducing the fluid flow temperature using the pipe segment 100 can allow non-metallic pipes to be used in a manner that is safe for high temperature applications. Non- metallic pipes can be constructed more easily and more quickly than can conventional carbon steel pipes, which improves the tie-in schedule of the wells by reducing the time, costs, and efforts. Such pipe selections can also reduce other costs associated with the use of metallic piping. Furthermore, the pipe segment 100 has a compact footprint and simple design that functions without a power source, functions without rotating or other moving equipment, and is easy to install and remove from a well flow line. Other advantages provided by the pipe segment 100 include a low environmental burden in that no toxic materials or radiation is used and in that the pipe segment 100 is a closed system, such that no fluids are disposed of to the ambient environment.

The pipe segment 100 also has low manufacturing and operational costs. The design of the pipe segment 100 is also flexible in that the number of pipe elements 104 per stage 152 and the total number of stages 152 can be selected based on a desired heat transfer effect.

[0048] FIG. 7 is a flow chart illustrating an example method 300 of cooling a fluid flowing through a heat transfer apparatus (for example, such as the pipe segment 100). In some embodiments, fluid is flowed through a lumen (for example, such as the lumen 118) of a tubular wall (for example, such as the central wall 102) carrying multiple pipe elements (for example, such as the pipe elements 104) arranged about a circumference of the tubular wall and passing through the tubular wall (302). In some embodiments, heat is absorbed from the fluid along interior portions (for example, such as the evaporator sections 130) of the multiple pipe elements that are located within the lumen as the fluid flows through the lumen (304). In some embodiments, heat is released from exterior portions (for example, such as the condenser sections 134) of the multiple pipe elements that are located exterior to the tubular wall as the fluid flows through the lumen (306).

[0049] FIG. 8 is a schematic drawing illustrating a fluid management system

400 in which the pipe segment 100 is installed to a well flow line 402 with multiple isolation valves for operation. An upstream portion 404 of the well flow line 402 delivers fluid to the pipe segment 100 through an entry valve 406, and the pipe segment 100 delivers fluid to a downstream portion 408 of the well flow line 402 through an exit valve 410. For operational and maintenance flexibility, a bypass line 412 can be installed to the well flow line 402 to direct fluid flow from the upstream portion 404 to the downstream portion 408 without passing through the pipe segment 100 for cooling. A bypass valve 414 can permit or prevent flow through the bypass line 412. Additionally, a drain line 416 can be installed to the pipe segment 100 in order to drain fluid from the pipe segment 100 to a drain receptacle 418 for maintenance of the pipe segment 100. A drain valve 420 can permit or prevent flow through the drain line 412. During operation of the pipe segment 100, valves 406 and 410 are open, while valves 414 and 420 are closed. When the pipe segment 100 is to be removed from the fluid management system 400 for maintenance, valves 406 and 410 are closed, while valves 414 and 420 are open. [0050] While the above-discussed pipe segment 100 and fluid management system 400 have been described as including certain dimensions, sizes, shapes, arrangements and materials, in some embodiments, pipe segments and fluid management systems that are substantially similar in construction and function to the pipe segment 100 and the fluid management system 400 may include one or more different dimensions, sizes, shapes, arrangements, and materials.

[0051] For example, while the pipe elements 104 are described and illustrated as having a generally tubular shape, in some embodiments, pipe segments that are otherwise substantially similar in construction and function to the pipe segment 100 may include pipe segments that are of a shape different from that of the pipe elements 104. Example alternative shapes may include a non-circular cross-sectional shape (for example, such as an elliptical cross-sectional shape or another cross-sectional shape) that may enhance heat conduction from evaporator sections to condenser sections of the pipe elements and further heat release to an ambient environment without otherwise substantially affecting a behavior of the flow of fluid within a lumen of the pipe segment.

[0052] Other embodiments are also within the scope of the following claims.