Flow Measurement of Highly Viscous Coker and Visbreaker Feed

Flow Measurement of Highly Viscous Coker and Visbreaker Feed

In a typical complex refinery operation, residues or other high viscosity liquid streams (VTBs) from the Vacuum Distillation Columns are fed into cokers and/or visbreakers for further processing. The flow of these hot liquids (up to 370°C) is difficult to measure and together with their viscous and sticky nature, traditionally intrusive measurement technologies are often ill-suited.

Under these very severe process conditions, impulse line clogging and vortex shedder breakdowns are frequent. High maintenance costs or even process shut downs are the consequences.

In a North American refinery, a differential pressure measurement was replaced without any process interruption with FLEXIM's non-intrusive WaveInjector, eliminating daily maintenance tasks. Furthermore, the wide dynamic range of the FLUXUS turned out to be of additional advantage. Previously, four orifice plates were necessary to cover the entire measuring range. Now a single instrument does the job.

Noteworthy here is also the implementation of a redundant mechanism. As the coker feed isn't allowed to fall below a specific threshold, two measurement channels are connected to the FLUXUS, actively averaging the measured volume flow. If one of the channels were to fail, the flow meter will continue to operate on the other channel solely and thus, the measuring never stops. Additionally, in such a case as when the coker feed falls below the limit, FLUXUS will ouput a binary alarm signal.

The need for a reliable flow measurement is critical to the refinery for the safe handling of the products and is essential for a better inventory and process control while assisting in maintaining the capacity to meet ever growing demands.

Advantages

  • No risk of impulse line or pipe clogging (unlike the former DP measuring system) 
  • No production interruption for installation
  • Reliable, maintenance free flow measurement 
  • Wide dynamic measurement range

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