Coriolis flowmeters help meet regulatory requirements & reduce annual costs!

An RHI Normag AS plant in Porsgrunn, Norway, has reduced maintenance costs, minimised plant downtime and improved the accuracy of energy-use measurement by using Micro Motion® Coriolis flowmeters.

Six Micro Motion CMF Series flowmeters measure the mass flow of natural gas and recycled fuel oil used in kilns that produce magnesium oxide refractory material. The highly accurate measurements are used for the fiscal transfer of gas and oil, and are also submitted to KLIF, Norway’s national environmental agency, to ensure compliance with environmental regulations.

"Our plant is a large energy-user, so accurate measurements of gas and oil are critical to our operations," said Merethe Pepevnik, Technical Manager, RHI Normag AS. "Since our process is continuous, reliability is very important. Interruptions to recalibrate or refurbish measurement devices are both inconvenient and costly. We chose Emerson’s Micro Motion Coriolis mass flowmeters because they are reliable, accurate and simple."

The RHI Normag plant produces raw materials for refractory material, to be used in a wide range of industries. In the past, turbine flow meters with a density measurement system 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, due to wear and tear over the years, the measurement system’s accuracy was poor and it 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.

To reduce maintenance costs, minimise plant downtime and accurately measure energy usage, RHI needed a measurement system that would be acceptable to KLIF, provide accurate data for custody transfer, and require minimal maintenance.

The first four mass flowmeters 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. 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, these flowmeters comfortably meet the requirements of KLIF.

RHI uses Emerson’s Smart Meter Verification to regularly check the meters’ health and performance. This easy-to-use, automatic diagnostic tool quickly verifies the measuring tube integrity and electronics (sensor, drive and signal processing) without interrupting the flow measurement – reducing downtime and eliminating the need for twice-yearly maintenance/calibration.

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. It also records if the meter zero was changed relative to the factory zero, or to the last successfully established zero on site. These reports are retained for yearly audit by the authorities and support regulatory compliance.

"Emerson’s Micro Motion Coriolis flowmeters have been proven in use over several years in our plant," added Pepevnik. "Even the first meter installed in 2009 has not required adjustment. 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 6 months."