Presentation by Dr. George Cheng
Flare Control System Design to Comply with EPA RSR-63.670 Rules
Date: February 6, 2019 (Wednesday)
Time: 12:30 PM - 1:00 PM
Place: Hilton Austin
500 East 4th Street, Austin, TX 78701
Oil refineries must comply with EPA RSR-63.670 rules and chemical plants will need to meet similar regulations in future. Flares must maintain a minimum combustion zone net heating value of 270 Btu/scf. In addition, for air assisted flares, the combustion zone net heating value dilution parameter must be above 22 Btu/sq.ft. In order to achieve these goals, flare control systems are critical.
Technically, flare control is very difficult because: (1) The vent gas flow can change widely; (2) The heating value in vent gas can change widely and quickly; (3) Nitrogen is often used as purge gas to maintain positive pressure in the vent pipe, making the process more complex; (4) There are large and varying time delays in the heating value control loops, and (5) The heating value process is extremely nonlinear in different operating conditions. Flares are difficult to control using conventional PID controllers. Model-based control can be costly to develop and maintain.
CyboSoft is offering a field-proven flare control solution with its CyboCon Model-Free Adaptive (MFA) control software. In this presentation, we will show how to design control systems for a steam assisted flare and an air assisted flare. We will run real-time control simulations to compare the performance when controlling combustion zone net heating value with different methods under varying operating conditions.
CyboSoft’s Flare Process Modeling and Control Simulation Software will be used to demonstrate the following results: (1) A flare process is under good control where the combustion zone net heating value is above 270 But/scf under varying operating conditions; (2) A flare process may not meet the 270 But/scf requirement due to poor steam control; and (3) A flare process is not controlled well due to slow GC data.
In the Q&A session, we can discuss: (1) Flare control system design considerations, (2) Vent gas heating value measurement, (3) 15-min data block calculations, and (4) How to integrate a flare control system with an existing DCS.