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Control Strategy in a Centrifugal Separation Process
KTH, School of Electrical Engineering (EES), Automatic Control.
2010 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [sv]

Ett nytt koncept för separering av jäst från öl har tagits fram på Alfa Laval i Tumba. Jästen matas nu ut kontinuerligt istället for att skjutas ut då separatorn har fyllts med för mycket jäst, konceptet gör att man kan spara öl som annars försvinner i samband med skott. För att konceptet skall vara lönsamt måste den utmatade jästen ha tillräckligt hög densitet trots att indensiteten ständigt sjunker, samtidigt som man måste ha bra separering. I det här examensarbetet har en reglerstrategi för denna höghastighets centrifugal separationsprocess utvecklats. Genom experimentella studier av systemet kunde en matematisk modell av separationsprocessen skapas. Modellen användes sedan som grund for en MPC-regulator där densiteten styrdes genom att styra flödena i processen. En implementering av styrningen genomfördes sedan i processlaboratoriet i Tumba. Separeringen antogs vara bra så länge massflödet in var relativt lågt och trycknivåerna var bra. Med MPC-regulatorn gick det att hålla densiteten över en satt gräns i laboratorieexperiment. Det visas också att en ervariabel regulator i det här fallet har fördelar över envariabla. Förutsättningar för att i ett nästa steg även reglera separeringseffektiviteten anses finnas.

Abstract [en]

A new concept for separating yeast from beer has been developed at Alfa Laval in Tumba. The yeast is now continuously fed out from the separator instead of discharged when too much yeast have collected in the separator. The concept makes it possible to save beer which otherwise would have been wasted at discharges. For the concept to be protable, the density of out yeast must be high enough even though the inlet density is steadily declining, and at the same time have good separation eency. In this thesis a control strategy has been developed for this high speed centrifugal separation process. Through experimental studies a mathematical model of the separation process could be made. This model was then used for a MPC-controller where the density was controlled by controlling the ows of the process. An implementation of the control strategy was carried out in the process laboratory in Tumba. The separation was assumed to be good as long as the mass inow was relatively low and the pressure levels were steady. With the MPC-controller it was possible to maintain the density over the set limit in laboratory experiments. It is also shown that a multivariable controller has benets compared to a single variable controller. Controlling the separation efficiency is deemed possible and is the next step.

Place, publisher, year, edition, pages
2010. , 85 p.
National Category
Control Engineering
Identifiers
URN: urn:nbn:se:kth:diva-105154OAI: oai:DiVA.org:kth-105154DiVA: diva2:570121
Subject / course
Automatic Control
Educational program
Master of Science in Engineering - Electrical Engineering
Uppsok
Technology
Examiners
Available from: 2012-12-03 Created: 2012-11-16 Last updated: 2012-12-03Bibliographically approved

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CiteExportLink to record
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Citation style
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