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Companies like ABB (Havre, Stornes et al. 2000), Statoil and Total have all
researched prevention of slugging and built installations at offshore locations. Statoil
completed in 2001 their first slug control installation at the Heidrun oil platform.
Siemens is also involved in slugging research and funds a PhD program, which this
thesisisconnectto.
Intheanti‐slugcontrolsystem,itisveryimportantthatthecontrollersarefine
tuned. Otherwise, the control system is not robust in practice and the closed‐loop
systembecomesunstableafteraplantchange.Thesluggingsystemishighlynonlinear
sincethegainchangesat differentoperatingpoints.Forsuchasystemthecontrollers
needtoberetunedateachoperatingpoint.
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Scopeofthethesis
Inthisthesisthreedifferenttuningmethodswillbetestedwithexperimentsand
simulations to find the most robust solution for anti‐slug control system. High
robustnesswillbeobtainedifthesystemcanmaintainstabilityatlargedeviationsfrom
openloopconditions.Thismeanslargechokevalveopenings.Thetuningmethodsare
systematicandhavebeendevelopedveryrecently(ShamsuzzohaandSkogestad2010;
JahanshahiandSkogestad2013).
TheexperimentsofthisthesiswillbecarriedoutatthedepartmentofEnergyand
ProcessEngineering.Twoseriesofexperimentswillberunusingamedium‐scaletwo‐
phase flow S‐riser loop. The difference between the two series is the type of choke
valve.Theaimistoinvestigatetheeffectofcontrolvalvedynamicsonperformanceof
the control system in addition to robustness of the tuning methods. Possibility of
differentcontrolstructureswillbealsoinvestigated.
The experiments will be simulated in multiphase flow simulator, OLGA, and the
same control tests will be performed. Finally the simulated and experimental results
willbecompared.
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