PiControl Solutions

Closed-Loop System Identification Software and Technology for LNG Plant MPC (Model Predictive Control) and APC (Advanced Process Control)

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 PiControl Solutions LLC, a leader in industrial process control software, services, consulting and training has been contracted by a large USA based LNG producer for the closed-loop analysis of LNG plant data for improving MPC (model predictive control) and APC (advanced process control) models.

PiControl's closed-loop system identification technology provided in the PITOPS and COLUMBO software is the only unique software technology in the world that can identify open loop transfer function models with complete closed loop data without step tests.

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Many process control MPC software from conventional MPC and DCS vendors need step tests for model identification. Step tests are considered open loop method of model analysis. PiControl's PITOPS and COLUMBO software can identify models for ambient temperature accurately. Ambient temperature and wind directions can change anytime and getting good models from ambient temperature to the MPC controlled variables is important.

PiControl can determine accurate open loop dynamic models for ambient temperature with all important CVs (controlled variables) in an LNG plant. Another important measured disturbance in an LNG plant is the BOG flow (Boil Off Gas). BOG flow changes when an empty LNG ship comes to port to fill up with LNG. An empty LNG tanker is warm and when cold LNG liquid enters the ship's tank, a lot of liquid LNG flashes and needs to be condensed. The rate of the Boil Off Gas BOG flow depends on the temperature, how fast the valves are opened and many other factors.

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A good MPC controller for an LNG plant or a good DCS-based APC in an LNG plant needs good models between the BOG flow and all the important LNG plant-controlled variables. Current commercial MPCs (model predictive control) - Aspen DMC, Honeywell RMPCT, Profit Controller, Emerson Predict Pro, SimSci Foxboro Connoisseur etc. all need open loop step tests and have difficulty in identifying accurate open loop models for BOG flow.

PiControl closed loop system identification technology can identify open loop dynamic models even when there are no step tests in the model inputs. Variables that are changing slowly like ambient temperature, calorific value in gas, gas density or BOG boil off gas flow all can be handled very well and far better than any of the MPC tools named above. PiControl software technology is unique and different. Software from PiControl closed loop identification technology use GRG optimization method - Generalized Reduced Gradient Optimization. Contact PiControl today - www.picontrolsolutions.com

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