dc.description.abstract |
The orifice meter is still commonly used for natural gas measurement despite its
many limitations. Considerable efforts in recent years have resulted in improved
knowledge of factors such as installation effects and the value of discharge coefficient
but a serious problem still remains with the measurement of differential pressure since,
when line static pressures are as high as 200 bar, differential pressures of 500mbar have
to be measured. Furthermore, the flow is never absolutely steady and the performance of
the pressure transducers under such conditions is not yet fully understood. This thesis
demonstrates the need to apply modern signal processing and analysis techniques to
enhance the performance of process instrumentation systems. The use of two static
pressure transducers of resonance type upstream and downstream the orifice meter, with
a high frequency response, can offer the ability, by using spectral analysis and spectrum
estimation methods, to extract additional information regarding the meter’s performance
as well as diagnostic information about the whole process plant. It also demonstrates a
method to check and, at the same time, to safeguard the flow information obtained from
an orifice meter with the use of a third pressure transducer upstream of a Mitsubishi flow
conditioner. Furthemore, information about the performance of the package orifice -
conditioner using the discharge coefficient (Cd) and the amplitude spectrum from the
three pressure transducers can be obtained. |
en_UK |