Visbreaking unit

Details of three visbreaking APC training sessions follow:

(Four sessions if the attendees have not taken the wide cut fractionation course).

1. Visbreaker operation and economics (80 minutes):

• Overview – the visbreaking reaction and asphaltene suspension stability, definition of conversion.
• Feed and product: destinations, specifications and unit economics.
• Equipment configuration: Heater, soaker, main fractionator, usually also a simple gas plant.
• Key handles: feed flow, heater outlet temperature
• Fractionator handles: Top temperature, pumparound, LGO draw
• APC requirements

2. Inferential modeling (80 minutes):

(Two sessions of 100 minutes each if attendees have not taken the wide cut and narrow cut fractionation training)

• Modeling of reaction equivalent time, feed-forward of throughput changes.
• Modeling of maximum conversion, constrained by asphaltene stability.
• Fractionator product quality inferences – see wide cut fractionation.
• Product cutpoints, flashpoints, internal reflux at key points.

3. Visbreaker APC (80 minutes):

• Constraints and APC structure: CV’s, DV’s and MV’s.
• In the furnace, fractionator and gas plant sections.
• The unmeasured fuel stability constraint.
• Conversion maximization: Measured and unmeasured constraints: furnace limits, heat removal, fuel stability.