Thursday, 6 December 2012

Tar tank level

Rosemount® Guided Wave Radar diagnostics identify potential degradation of signal in challenging tar tank level application

Red Arrow Products Company LLC has replaced unreliable capacitance-based level measurement devices with Guided Wave Radar (GWR) transmitters from Emerson Process Management. The Rosemount® 5300 Series GWR is used to monitor the level of wood oil in a process tank and features advanced diagnostics that continuously monitor the GWR probe for signal degradation caused by product build-up. The accurate and reliable data provided has enabled Red Arrow to schedule its maintenance to clean the probe, reducing costs and increasing throughput by avoiding unexpected shutdowns.
Red Arrow produces natural smoke condensates and flavourings at its manufacturing facility in Manitowoc, (WIS USA)

"In the past, occasional unplanned shutdowns due to probe failures or coating issues would upset our process – reducing product throughput and increasing energy use," said Barry Schardt, Red Arrow Equipment Manager/Electrical Engineer. "Since we installed Emerson’s Guided Wave Radar transmitters about one year ago, we have not had premature shutdowns during a production run due to level probe failure."

Red Arrow produces natural smoke condensates and flavourings at its manufacturing facility in Manitowoc, Wisconsin, USA. The wood oil is held in a 1.5-meter-tall collection tank that must maintain a constant level in an evaporation process. The level in the tank was being measured using a sensor based on capacitance technology. Although this technology usually performs well in applications that operate at high temperatures and with viscous/sticky products, coating issues were causing unreliable level measurements that resulted in unplanned shutdowns.

This is a particularly challenging level application, as the tank operates under vacuum conditions and the measurement device is subject to vapours and mist that normally cause level measurement problems. Red Arrow also had concerns about the problem of build-up of a sticky tar-like substance on the probe in the tank, which could cause signal degradation.

To address these issues, Red Arrow upgraded the capacitance-based device to a Rosemount 5300 GWR with a single rigid probe and Signal Quality Metrics (SQM). GWR devices are unaffected by changes in pressure and vapour space conditions, and SQM provides diagnostic information that relates directly to the coating on the probe and to changing surface conditions. These values can be assigned as process variables and tracked over time.

Red Arrow personnel can track the Signal Quality Metrics and use the data to maintain ideal operating conditions, improving product quality over extended continuous run periods. The reliable level measurements have reduced operational costs by minimising the risk of unscheduled shutdowns or equipment damage caused by inaccurate level measurements. Maintenance costs have also been reduced by enabling a preventive maintenance programme that extends the period between shutdowns to carry out cleaning of the probe.

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