Abstract
This paper presents the design of a non-intrusive system to measure ultra-low water content in crude oil. The system is based on a capacitance to phase angle conversion method. Water content is measured with a capacitance sensor comprising two semi-cylindrical electrodes mounted on the outer side of a glass tube. The presence of water induces a capacitance change that in turn converts into a phase angle, with respect to a main oscillator. A differential sensing technique is adopted not only to ensure high immunity against temperature variation and background noise, but also to eliminate phase jitter and amplitude variation of the main oscillator that could destabilize the output. The complete capacitive sensing system was implemented in hardware and experiment results using crude oil samples demonstrated that a resolution of ±50 ppm of water content in crude oil was achieved by the proposed design.
Highlights
Determination of water content is an important issue in grading crude oil
The interface circuit is simulated using PSPICE to study the sensitivity of our sensing system at various values of Ψ
Discrete components were used future implementation of the interface circuit would be monolithic integrated circuit (IC) based
Summary
Determination of water content is an important issue in grading crude oil. Conventional industrial approaches include distillation, centrifugation and electrical dewatering [1]. There are various designs of interface circuit for capacitive sensing and they can be categorized, into the following type: Charge amplifier that converts measurements into DC voltage [15,16]. The circuit uses a compensating signal to permit a gradual phase shift in response to the change in capacitance, in place of the abrupt 180 turnover produced by the conventionally compensated charge amplifier. This enables the circuit to be sensitive even to sub-femto farad changes [21]. We will exploit this capacitance to phase conversion circuit for the application of ultra-low water content in crude oil measurement. We propose a simple phase readout mechanism to eliminate the need of an analogue-to-digital converter (ADC)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call