November 2016  
2016 Process Control and Safety Symposium
and Exhibition

Houston Marriott Westchase
2900 Briarpark Drive, Houston, TX 77042 USA
On November 8, 2016 (Tuesday) at 11:30am,
CTO, George Cheng Ph.D., will present a tutorial session:

Model-Free Adaptive (MFA) Control for Industrial Flares
and pH Processes to Comply with EPA Regulations

Most refinery and chemical plants operate flares to burn off waste gas for operational and safety reasons. The vent gas heating value of a flare must be monitored and controlled to meet EPA regulations. For steam-assisted or air-assisted flares, the net heating value of the gas being combusted must be 300 Btu/scf or greater. When the waste gas heating value is below this limit, supplemental gas, such as natural gas, must be added to assure sufficient combustion and minimal emission.

There are online calorimeters on the market for heating value measurement. However, adding a heating value (HV) control loop can be a challenging task due to the following reasons: (1) There are large and varying time delays in the HV control loop; (2) The HV process is nonlinear in different operating conditions; (3) Multiple waste gas streams in a plant are sent to the flare stack, where stream flows can vary widely causing big disturbances to the heating value; (4) The HV of each waste gas stream may change widely under operating condition changes; and (5) Nitrogen is often used as purge gas to keep positive pressure in the vent pipe, making the process more complex. The flare process is difficult to control using conventional PID controllers. Model-based control can be costly to develop and maintain due to the complexity and uncertainties of the flare process.

In this presentation, we will show the behavior of a typical flare process by running a real-time flare heating value process model. We will compare the control performance of different control methods by running control simulations. Lastly, we will present the results of a flare heating value control system using Model-Free Adaptive (MFA) control technology in a petrochemical plant. The system has been running for about 2 years and is able to effectively control the vent gas heating value above 300 Btu/scf without over-supplying natural gas to achieve economic benefits.

How does MFA work? Why is a no-model approach possible? We will answer these questions in this session. We will also discuss the control applications where MFA has been used to help customers achieve significant technical and economical benefits.

Real-time software demonstrations will compare MFA and PID head to head with no parameter tuning, including:
  • MFA and PID controlling processes with changing dynamics,
  • MFA and PID controlling extremely nonlinear processes,
  • MFA and PID controlling pH processes,
  • MFA and PID controlling processes with large and varying time delays,
  • MFA and PID controlling pH processes with large time delays, and
  • A 2x2 MFA controller controlling a distillation column process.
In the Q&A session, we can discuss: (1) new EPA regulations relating to steam or air over-assisting problems, which are commonly seen in refineries where vent gas may have high heating values, and (2) implementation of MFA control systems.
  Dr. George Cheng is the CTO of CyboSoft, General Cybernation Group Inc. and CyboEnergy, Inc. The inventor of 30 U.S. patents, he is the primary developer of Model-Free Adaptive (MFA) control technology and scalable power inverters.

Dr. Cheng and his CyboEnergy team developed CyboInverter, the world's first solar power Mini-Inverter. He is a Fellow of ISA (International Society of Automation) and an IEEE senior member.
Visit ISA's website for more information.
  September 2016 - Solar Power International  
Click here to visit the Solar Power International Website

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