Model-Free Adaptive Control
of Oil Refinery Furnaces
|• Tightly controls furnace outlet temperature
and minimizes deviations of zone temperatures.
||• Achieves smoother operations, higher yield,
and energy savings.
|• Decouples loop interactions and minimizes
chain reactions among the columns and furnaces.
||• Avoids potential vicious cycles, plant
upsets, and accidents.
|• Improves feed throughput and minimizes
||• Return on investment within a few months.
MFA Control Solution for Oil Refinery Furnaces
Process: An oil refinery
consists of a series of distillation towers and furnaces.
Crude oil is piped through hot furnaces and resulting
liquids and vapors are discharged into distillation
towers to be separated into comp onents or fractions
by weight and boiling point. Gasoline, liquid petroleum
gas, kerosene, diesel oil, and intermediate streams
Goals: Refinery furnaces consume so
much energy that it contributes to a high percentage
of operating costs. It is desirable to tightly control
furnace temperatures and other process variables to
optimize separation, minimize energy consumption, and
Challenges: A typical refinery furnace
consists of multiple passes of oil pipes. It is naturally
a multivariable process with multi-zone temperature
control problems. It is difficult to tightly control
the oil temperatures of each pass and outlet due to
interactions between the passes and changing operating
conditions. The distillation tower level and furnace
combustion are also critical but difficult to control.
Solution: CyboSoft offers effective
Model-Free Adaptive (MFA) control solutions for controlling
critical process variables without the need to build
furnace process models and retune controller parameters.
Tower Level Control: Use a Robust
MFA to smoothly control the distillation
tower level and minimize outlet flow variation to reduce
potential vicious cycles in the distillation tower-furnace
chain. User-selectable bounds on level PV protect the
level from running too high or too low.
Furnace Temperatures: By using a
MIMO MFA controller
to manipulate the oil flow of each pass, interactions
between the temperatures are decoupled so effective
temperature control can be achieved. An MFA controller
is able to tightly control the Outlet Temp. Anti-delay
MFA features may be enabled to handle
the large time delays.
Combustion Control: Use a MIMO
MFA to control the intake and exhaust
fans. MFA can decouple the interactions of these 2 fans
so that the fuel-air ratio can be effectively adjusted
to achieve better combustion efficiency.
Application Story: SINOPEC has deployed
an MFA control system for its vacuum furnace and distillation
tower and achieved the following success:
• Outlet oil temp is controlled within +/- 1 °C
• Temp deviations between 4 passes are minimized;
• Better combustion and level control;
• Improved production safety, separation efficiency,