Subsea Proximity Sensor Probe for Rotating Shaft Monitoring
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Solution Overview
Problem
Proximity sensing of rotating shafts in subsea pumps or compressors is challenging due to high process fluid pressures, which require protection of electronics and precise distance measurement in harsh environments.
Innovation Solution
A subsea rotating machine with a proximity sensing system featuring a non-rotating pressure housing, a conduit for a coaxial cable, and a high-pressure penetrator forming a seal with the housing, along with a sensor probe using an eddy current coil for precise distance measurement, protected by a gas-filled body and adjustable flange for accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If proximity sensing is implemented in subsea rotating equipment, then valuable information on running conditions can be obtained, but the electronics must be protected against extreme seabed pressures of 15-20 kPsi
Solution Approach 1:
The system is divided into two separate pressure zones: a subsea pressure housing that withstands the extreme external pressure, and an atmospheric pressure environment inside the housing where the sensor electronics operate. This segmentation allows each component to be optimized for its specific pressure environment, resolving the contradiction between measurement capability and electronics protection.
Solution Approach 2:
A pressure barrier (seal) acts as an intermediary between the high-pressure subsea environment and the low-pressure sensor environment. This barrier allows the sensor to function in a protected atmospheric environment while still being able to measure the position of rotating components through the barrier structure.
2Measurement precision
If the sensor probe is positioned close to the rotating shaft for accurate measurement, then proximity sensing precision is improved, but the cable routing and sealing complexity increase under high pressure
Solution Approach 1:
The cable is integrated directly into the pressure barrier structure itself, rather than being a separate external component. This merging of the cable routing with the sealing structure eliminates the need for separate cable glands or penetration seals, reducing overall system complexity while maintaining both measurement precision and pressure integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables robust and accurate proximity sensing in high-pressure subsea environments, providing valuable information on the running conditions of subsea rotating equipment while withstanding extreme pressures and temperatures, enhancing operational reliability and precision.
Implementation Method 1
The proximity sensor probe includes an eddy current coil
Data Source
AI summary
A proximity sensing system is configured to sense proximity of a rotating component in subsea rotating equipment such as pumps, compressors and separators. A plurality of sensing probe modules are included to sense proximity at various locations of the rotating shaft. The probe modules can include a fixed length stinger that can be gas-filled to maintain atmospheric pressure. The probe modules can also be a stinger-less design were the sensor is fixed to an inner pump housing and flexible cable is run through a channel of an outer pump pressure casing to a high pressure penetrator.