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Dual Flow Path Cooling System

IP.com Disclosure Number: IPCOM000237688D
Publication Date: 2014-Jul-02
Document File: 2 page(s) / 96K

Publishing Venue

The IP.com Prior Art Database

Abstract

High downhole temperatures have long been a determent to the life expectancy of the motor for an electrical submersible pump system. By design the motor has limited space for the internal lubricating oil and depends on forced convection flow of well fluid in the annulus of the casing for cooling. This invention helps solve both the cooling and circulation issues. It is a system that can be bolted on a standard motor to dramatically increase circulation of the lubrication oil while creating an amplified oil cooling system. This combination is estimated to increase the longevity of an electric submersible motor expected run life. It develops a dual system providing high velocity flow for the fluid in the heat exchanger and an elevated pressure for the fluid that is circulation through the motor. Thermal expansion and contraction of the lubrication oil within the motor has been handled by means of an expansion chamber referred to as Seal or Equalizer. By design the motor has limited space for the internal liberating oil and depends on forced convection, flow of well fluid in the annulus of the casing past the motor housing, as the primary source of cooling. The circulation of the motor oil within the system, across bearing surfaces etc., has also been considered inadequate; given the motor is expected to operate continuously in this environment for a number of years. The invention is a device that helps solve both the cooling and circulation issues of the internal motor oil by means of a motor cooler. The design concept is a bolt on system that communicates internally with the current motor design (with some minor modifications) which dramatically increases circulation of the lubrication oil while creating an amplified oil cooling system. The motor cooler (heat exchanger) is attached to the bottom of the motor and incorporates a small internal centrifugal pump driven by a connection with the motor shaft. The centrifugal pump is multi stage with two exit ports to create a dual path for the fluid flow. The fluid exiting through the upper exit is directed through the hollow motor shaft, lubricating bearings and circulating oil throughout the motor. The oil returns through either the air gap between the motor rotors and the stator lamination or through an external auxiliary return path. It mixes with the fluid that had flowed out through the first pump exit and together they are directed to the entrance to the internal passage of the heat exchanger pipes (coils). The outer surfaces of these cooling coils are located outside the pressure boundary of the motor housing. The coils, be they spiral, vertical or horizontal, are located inside a cylindrical chamber to protect them from damage when the unit is installed and to direct the well fluid to flow over these coils. The cylindrical has openings at the bottom to let the well fluid enter, pass over the coils and exit through similar openings above the coils. The cylinder can incorporate a restriction on its outer surface to reduce the volume of fluid flowing up the outside of the cylinder. The cooling effect is a function of the fluid flow regime. The lower section of the pump is sized to create a high velocity turbulent flow in the fluid for circulation to the heat exchanger. The fluid that does not flow out the first exit continues to build pressure as it passes through the top portion of the pump to create sufficient pressure to furnish a turbulent cooling flow through the main body of the motor.

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Dual Flow Path Cooling System

High downhole temperatures have long been a determent to the life expectancy of the motor for an electrical submersible pump system. By design the motor has limited space for the internal lubricating oil and depends on forced convection flow of well fluid in the annulus of the casing for cooling. This invention helps solve both the cooling and circulation issues. It is a system that can be bolted on a standard motor to dramatically increase circulation of the lubrication oil while creating an amplified oil cooling system. This combination is estimated to increase the longevity of an electric submersible motor expected run life. It develops a dual system providing high velocity flow for the fluid in the heat exchanger and an elevated pressure for the fluid that is circulation through the motor.

Thermal expansion and contraction of the lubrication oil within the motor has been handled by means of an expansion chamber referred to as Seal or Equalizer. By design the motor has limited space for the internal liberating oil and depends on forced convection, flow of well fluid in the annulus of the casing past the motor housing, as the primary source of cooling. The circulation of the motor oil within the system, across bearing surfaces etc., has also been considered inadequate; given the motor is expected to operate continuously in this environment for a number of years. The invention is a device that helps solve both the cooling and circulation issues of the internal motor oil by means of a motor cooler. The design concept is a bolt on system that communicates internally with the current motor design (with some minor modifications) which dramatically increases circulation of the lubrication oil while creating an amplified oil cooling system. The motor cooler (heat exchanger) is attached to the bottom of the motor and incorporates a small i...