Advanced Process Control A Real World Example Jim English UT Graduate, ChE ‘04 April 27, 2006

Introduction Who am I? Who is Air Liquide?

Why am I here? “Real World” example Some notes from industry

So what’s the story? HyCO = Hydrogen + Carbon Monoxide How does the HyCO work? (Go to PFD)Go to PFD Amine System (Go to Amine)Go to Amine

HyCO Process Flow Dryers PSA Cold Box Cold Box Membranes Reformer (Reactions) CO Hydrogen Natural Gas + Steam Amine System Amine System (Details)

~60’ Reformer Reactions Natural Gas Reforming: –CH 4 + H 2 O ↔ 3H 2 + CO Water Shift Reaction –CO + H 2 O ↔ H 2 + CO 2 Back to PFD

Amine System Absorber Stripper Reboiler Heat Exchanger Process Gas Inlet Process Gas Outlet CO 2 (Inside) Amine System Amine System

Pictures Inside Stripper X Reboiler Top Wall Re- boiler

Downcomer Tray Pictures Inside Stripper X Missing Clips Re- boiler

Pictures Inside Stripper X Steam Deflector Plate Re- boiler

So What Next?

Form the Team Research & Development Engineering & Design Process Control Experts Plant Operations HyCO Personnel

What’s our Goal? Reduce corrosion in the stripper… While maintaining absorber’s CO 2 removal

But Why? If we have to replace stripper packing… –$50,000 for packing –Plant shutdown = lost product revenue –Packing degradation ruined 2 pumps ($$$)

What’s Important?... Constraint Variables Manipulated Variables Disturbance Variables

Which Allows Us To… MVPC Controller MVPC Controller CV Target CV Value MV History DV History MV Setpoint

Amine System Revisited Absorber Stripper Reboiler Heat Exchanger Process Gas Inlet Process Gas Outlet CO 2 CV MV DV

Stripper ReboilerAmine RecircTotal CO 2 Flow Stripper Ovhd Temp??? CO 2 Slip??? Rich Liquid Loading??? Stripper Top DP??? Stripper Bottom DP??? Absorber DP??? How do these guys interact? MVs CVs

Next came the tough part Test & collect process reaction curves Import to Excel & Matlab Fit First Order plus Time Delay models

Example Step Response G = 0.5 τ = 4.5 θ = 3.0 (7.5)(3.0) (0.5) θ τ

Stripper ReboilerAmine RecircTotal CO 2 Flow Stripper Ovhd Temp CO 2 SlipModeled Rich Liquid Loading Stripper Top DP Stripper Bottom DP Absorber DP Modeled Now we Know MVs CVs

Inserting Models into MVPC…

Overall Results Post Implementation T avg = 225 ± 10°F T avg = 220 ± 4°F 5°FReduced average temperature by 5°F (225°F to 220°F) 60%Decreased standard deviation by 60% (10°F to 4°F) Corrision Temperature

Miscellaneous Project Updates Tools used Tasks performed

Conclusions Important Factors: –ENTIRE team –We reduced the risk of corrosion! –Project’s success is leading to further MVPC around the plant’s reformer

Thanks! Questions?