Subsea Induction Heating System and Related Method

Abstract

Abstract: A subsea induction heating system (10) comprising a subsea inline heater module (14) configured for heating a subsea hydrocarbon production or processing component (7) is described. The subsea inline heater module has an induction coil (6) configured for generating a variable magnetic field in the component. The system has a subsea variable frequency drive (4) configured for energizing the induction coil to achieve a desired temperature in the component. A corresponding method is also disclosed.

Claims

1. A subsea induction heating system comprising: a subsea inline heater module configured for heating a subsea hydrocarbon production or processing component, the subsea inline heater module comprising an induction coil configured for generating a variable magnetic field in the component; and a subsea variable frequency drive configured for energizing the induction coil to achieve a desired temperature in the component.

2. The system according to claim 1, further comprising a monitoring and control sub-system configured to monitor and control the temperature of the component and provide control signals to the subsea variable frequency drive to energize the induction coil to achieve said desired temperature in the component.

3. The system according to claim 1, wherein the subsea variable frequency drive comprises a rectifier configured for receiving an AC input current from a power source, an inverter configured for outputting an AC output current to the induction coil, and a DC link arranged between the rectifier and the inverter.

4. The system according to claim 3, wherein the rectifier being is configured for receiving the AC input current from a topside platform.

5. The system according to claim 1, wherein the component is a conduit for conveying a hydrocarbon production fluid.

6. The system according to claim 2, wherein the monitoring and control sub-system comprises at least one sensor configured to monitor at least one of: a temperature, a pressure and/or a flow of the process fluid flowing in the component; a temperature on a surface of the component; and a temperature of the production fluid upstream and/or downstream of the subsea inline heater module.

7. The system according to claim 5, wherein the conduit is a component in any one of: a pipe; a cooler; and a valve.

8. The system according to claim 5, wherein the induction coil wound around the conduit.

9. The system according to claim 1, wherein the component is comprised of a ferromagnetic material.

10. A method of heating a subsea component in a subsea hydrocarbon production or processing system, the method comprising the steps of: heating the component using a subsea inline heater module comprising an induction coil configured for generating a variable magnetic field in the component; and energizing the induction coil using a subsea variable frequency drive to achieve a desired temperature in the component.

Description

DESCRIPTION OF THE DRAWINGS

[0028] Following drawings are appended to facilitate the understanding of the disclosure, wherein:

[0029] FIG. 1 schematically illustrates a subsea induction heating system; and

[0030] FIG. 2 schematically illustrates a subsea variable frequency drive in the system according to FIG. 1.

[0031] It should be understood, however, that the drawings are not intended to limit the invention exclusively to the depicted subject-matter.

DETAILED DESCRIPTION OF THE INVENTION

[0032] In the following, embodiments of a subsea induction heating system will be described in more detail with reference to the drawings.

[0033] An induction heating system 10 is energized from a platform 1 via a power umbilical 12, arriving to an umbilical termination assembly (UTA) 2. An electrical flying lead (EFL) jumper 3 connects the UTA 2 to a subsea inline heater (SIH) module 14. The SIH module 14 can be installed on any type of subsea structure where heating of a pipe may be needed, for example on a pipeline end manifold (PLEM) and a pipeline end termination (PLET). An internal EFL 16 connects a panel connector 18 for a remotely operated vehicle (ROV) to an input penetrator of a subsea variable frequency drive (S-VFD) 4. The S-VFD 4 is configured to convert an input alternate current (usually 50 Hz or 60 Hz) into an alternate current of variable frequency. An output penetrator 5 connects the S-VFD 4 to an induction coil 6. The induction coil 6 surrounds a subsea pipe 7 to be heated.

[0034] With reference to FIG. 2, the S-VFD 4 comprises a rectifier 20, a DC-link 22 and an inverter 24. The rectifier 20 comprises rectifier diodes (not shown), located in an input circuit of the S-VFD 4. The rectifier diodes are configured to rectify the AC voltage received from the platform 1. The resulting DC voltage is received by the DC-link 22 where it is filtered through a capacitor and used as an input to the inverter 24. In the inverter, the rectified DC voltage is again converted to AC voltage through switching using PWM technology.

[0035] The induction coil 6 generates a variable magnetic field, which changes direction according to the oscillating AC current outputted from the S-VFD 4. Preferably helical, the induction coil 6 comprises of a plurality of turns and is used to transfer energy generated by the S-VFD 4 to the pipe 7. The number of turns may be chosen based on the specific project design plan. The pipe section encircled by the coils may preferably be made of ferromagnetic material.

[0036] When the pipe 7 is subjected to the variable magnetic field produced by the current flowing in the coils, an alternating current is produced in the pipe by induction. This alternating current produces heat due to Joule effect losses in the pipe 7 (due to the resistivity of the pipe material). The heat will then be transferred to a fluid flowing in the pipe by thermal conduction.

[0037] The system 10 comprises a monitoring and control sub-system 18 configured to monitor and control the temperature of the production fluid flowing in the pipe 7. The sub-system 18 may comprise one or a plurality of sensors, e.g. sensors configured to monitor the temperature, the pressure and/or the flow of the process fluid flowing in the pipe 7, and/or sensors configured to monitor the temperature on the surface of the pipe 7. The number, type and position of the sensors are usually project dependent. However, the monitoring and control sub-system 18 may typically comprise sensors configured to monitor the temperature of the production fluid upstream and downstream of the SIH module 14. Signal data from the sensor or sensors may be transferred to the S-VFD 4 through an EFL jumper 8 to control the S-VFD. The pipe temperature may also be monitored to check and control the integrity of the material in the pipe 7.

[0038] In the preceding description, various aspects of the apparatus according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, are deemed to lie within the scope of the present invention as defined by the following claims.