Six month payback for Coriolis flowmeters at RHI Normag 15 October 2013

An RHI Normag plant in Porsgrunn, Norway, is reporting reduced maintenance costs, minimised plant downtime and improved energy measurement accuracy since installing Coriolis flowmeters, from Emerson Process Management.

Six Micro Motion CMF flowmeters now measure mass flow of natural gas and recycled fuel oil used in kilns that produce magnesium oxide refractory material – the results being used for fiscal transfer of gas and oil, as well as submission to KLIF, Norway's national environmental agency.

"Our plant is a large energy-user, so accurate measurements of gas and oil are critical to our operations," comments Merethe Pepevnik, technical manager at RHI Normag.

"Since our process is continuous, reliability is very important," she continues, explaining that interruptions to recalibrate or refurbish measurement devices are inconvenient and costly.

"We chose Emerson's Micro Motion Coriolis mass flowmeters because they are reliable, accurate and simple," she says.

The RHI Normag plant produces raw materials for refractory material. In the past, turbine flow meters and associated density measurement systems were used for custody transfer measurement of oil and natural gas. The measurements were also used to calculate CO2 emissions for reporting to KLIF.

However, Pepevnik says that, due to wear and tear over the years, accuracy was poor and the systems needed to be calibrated twice per year to maintain performance.

This meant that four systems had to be taken out of the line for calibration/refurbishment at a cost of 25,000 euros each, incurring a total annual cost of 150,000 euros.

The first four Micro Motion Coriolis mass flowmeter replacements were installed on two kilns during the summer of 2009. One flowmeter on each kiln was used for recycled oil, and one for natural gas.

Then, in 2012, larger capacity Coriolis flowmeters were installed to measure higher gas flow rates. The flow data is used to determine the amount of gas being purchased from the supplier, removing the risk of over, or underpayment.

In addition, with their mass flow accuracy of ±0.35% for gas and ±0.1% for oil, the new flowmeters comfortably meet the requirements of KLIF.

Pepevnik says that RHI has also been using Emerson's Smart Meter Verification automatic diagnostic tool to check the meters' health and performance, without interrupting flow measurement.

Additionally, Emerson's Micro Motion ProLink configuration and diagnostic software tool is used to generate a meter health report every month, identifying any flow-tube damage that could compromise meter performance.

"Even the first meter installed in 2009 has not required adjustment," comments Pepevnik.

"Their performance has enabled us to significantly reduce our annual maintenance costs, simplify the process of meeting regulatory requirements, and be confident that we are paying for only the energy we actually use. Based on these factors our initial investment has been recovered in just six months."

Brian Tinham

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