A regional light crude pipeline operator in the US was looking for an economical, accurate method to measure crude inventory flow within its pumping stations. The company specialises in transporting partially processed crude to other lines or main terminals.
Accurate flow measurement is essential to the cost-effective operation of pipelines. While highly precise, and often expensive, flowmeters are required to perform custody-transfer measurements for payment purposes, there are also intermediate process measurement points within pumping stations, for example, that can be served with less expensive technology.
When oil is moved over distances via pipelines, pumping stations maintain product throughout as it travels. The flow rate and volume must be monitored (metered) to optimise pump operation and throughput to the end destination at a terminal, refinery or point of custody transfer as well as serve as early warning for leak detection. The pipeline pumping stations are located in proximity to equipment or facilities or where there are mountain ranges and long valleys.
The challenge
The company’s process engineers were searching for a low cost, but accurate flow measurement solution for internal inventory monitoring at its pump stations. There were no custody-transfer requirements and so a flowmeter with an accuracy of 0,5% was deemed suitable.
The light crude in the pipeline had already had passed through heaters and main separators, which left it devoid of gases, water or other constituents that would disturb the specific gravity (SG) of the oil. In this region, the oil has an API gravity rating of 40 or above.
The engineering team reviewed several flowmeter technologies, including Coriolis, differential pressure (dP), positive displacement (PD) and turbine. While all the technologies do measure flow, the team needed to find the specific one that would be the best fit in the crowded pumping station environment. They also needed to look at installation requirements, maintenance instrument life and total life-cycle cost to find the optimum solution.
The solution
When the pipeline engineering team contacted McCrometer, the company’s applications group suggested the V-Cone flowmeter. Their no moving parts, high reliability design offers safe, stable measurement with several decades of proven service and the standard global agency approvals required for use worldwide.
The advanced meters offer significant cost savings in light crude pipeline pumping station applications with complex or crowded equipment layouts. It utilises a centrally located intrusion that redirects the flow to the outside of the pipe and conditions it by reshaping the velocity profile, all but eliminating the need for straight pipe runs.
The V-Cone is a differential pressure (dP) type flowmeter. The low permanent head loss results from the shape of the cone itself, which minimises energy losses commonly caused by areas of low flow, cavitation and erratic flows. Each meter is sized to meet desired application requirements and may be specifically designed to have high or low head loss. Regardless, the overall energy consumed is minimised because of its inherently efficient design characteristics.
Conclusion
With its self-conditioning, no-moving parts differential pressure (dP) sensing technology, McCrometer’s V-Cone flowmeter is now installed in a wide variety of oil production, refining and pipeline applications around the world. The versatile devices offer low installed cost, low maintenance and highly reliable measurement for most industrial application.
Engineers in the oil industry have relied for several decades on the V-Cone to remain accurate in the toughest applications. Increasingly engineers are recognising the benefits and relying on it in applications traditionally held by the old guard dP technologies such as Venturi tubes.and Orifice plates, as well as turbine and PD. Its low-maintenance, no-moving-parts design is proven to remain accurate and all but eliminates the need to shut down production for calibrations, inspections or regular primary element replacement needed for an orifice plate. It saves money by increasing production up-time and reducing labour costs.
For more information contact Stuart Brown, UIC Instrumentation, +27 (0)31 468 2561, [email protected], www.uic.co.za
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