Can Process Analyzers become part of the control loop?

Transcription

1 Can Process Analyzers become part of the control loop? Cees Didden Workgroup Process Analyzers March 21th 2013

2 THE ANSWER IS YES End of this lecture? From : G. Stephanopoulos, Chemical Process Control, Prentice Hall, 1984 Page 1

3 Requirements : Controllability w y set point + x Controller - Process y + e y measure Measurement Controllability r is a product of the controllability of the process and the measurability: r = r p. m d. m a. m n r p :The controllability as a result of the dead time of the process T dp ; m d :The measurability as a result of the dead time of the analyzer T dm ; m a :The measurability as a result of the time between two samples T a ; m n : The measurability as a result of the reproducibility of the analysis. Page 2

4 Example r 2 σ = 2 w σ σ 2 w 2 ε σ w = standard deviation of the process fluctuations before control σ ε = standard deviation of the process fluctuations after control Parameter symbol continuous analyzer discontinuous analyzer lab. analyzer dead time process (h) 0,25 0,25 0,25 dead time measurement (h) 0,0 0,2 1 disturbance 1,0 1,0 1,0 autocorrelation time (h) precision measurement 0,5 0,3 0,01 autocorrelation time meas.(h) 0,2 0,5 1 sampling time (h) 0 0,5 1 controllability process rp 0,88 0,88 0,88 measurability md 1,00 0,90 0,61 measurability ma 1,00 0,89 0,80 measurability mn 0,92 0,96 1,00 total measurability m 0,92 0,77 0,48 total controllability r 0,81 0,68 0,43 Page 3

5 Transformation of analysis Needs are changing Analysis and sampling time are of major importance to improve controllability Smaller sampling systems (NESSI) Closer to the process to reduce sampling time Decrease analysis time Page 4

6 Transformation of analysis - sampling Page 5

7 Transformation of analysis - instruments Analysis time 4-8 minutes analysis time 1-2 minutes Page 6

8 Transformation of the workgroup Needs are changing Past : Workgroup QMI Focus on instruments Large projects and studies Instrument testing Members mainly from the Petrochemical Industry Limited exchange of experience Today : Workgroup Process Analyzers PAT Focus on exchange of experience between members Small projects dedicated to difficult applications Only desktop studies on instruments Members are from a wide variety of industries Page 7

9 Old days Date: Venue: 69 th QMI WORKING PARTY MEETING 07-March-2002 WIB Office, The Hague Present: G.van Unnik - DuPont de Nemours ( Chairman) J. Duisings - DSM R.Oprel - Exxon Mobil (Chemical) G. Thomas - AKZO Nobel Engineering H. Overbeek - KEMA P.v/d Laak - KEMA ( Student) A. van Adrichem - Exxon Mobil (Ref. and Supply) K.Y. Wong - Shell Gl. Solutions Int. A.E. Kuperij - WIB Office (minutes) Not present: J.G. Welmink - AKZO NOBEL Chemicals BV ( has sent action updates for discussion by mail) E. Engelen - DOW P. van Wesenbeeck - Gasunie Page 8

10 Old days 1. Opening 2 Confirmation of draft Minutes of Meeting (13 December-2001) 3 Confirmation of the Agenda 4 Current projects VS-1 Review and Update of WIB QMI spec VA Survey of Diode Array Spectrometers: XU Assessment of moisture analysis techniques (Desk study) 6 Shopping list VQ Ion Mobility Spectrometer VS Bartec; Fibre Optics Reflections Moisture Analyser WX Survey of Electrode less /Inductive Conductivity meters XE-2 Update cycle renewal of desk survey of GC s: XF Laser Raman analysers ( F/R, ThIS other makes??) 7 Pre-shopping List XK Synspec Process GC. XX Serial interfaces survey for multi-component analysers- 8 Round table: Trace mercury in natural gas: Laws and rulings on stack-gas emission quantifications? Oxygen analysers: KNCV werkgroep inaugural meeting (Dutch) 9 Experience exchange 11 Confirmation Meetings in 2002 Page 9

11 Present Page 10

12 Present AGENDA: 1- Arrival and Opening, Introductions, safety; 2- Confirmation of the A&A from the 108 -th meeting (March ) 3- Lectures/knowledge sharing and discussions: 3.1 Cees Didden: ( DSM): DSM resolve- Radiation services; Test of the new Berthold detector for radio isotope measurements 3.2 Tanja Masseurs-Bol: (Shell NLChemie): TDLAS based oxygen and CO measurements on Ethylene cracking furnaces 3.3 Neil Breton ( Solvay): IMTEC-2012-Paris--Towards full integration of PAT using NESSI/ASTUTE modular systems 4- Round-table: Exchange of experience 5- Action items and Current projects 5.1 ph: project definition (AnneV) 5.2 NEC/IEC 65 ( Arno vadr) 6- New project proposals 6.1 TDLS review and possible testing of Yokogawa 6.2 Dissolved Oxygen in water, 1 ppb 6.3 Data bus systems for field located PAT 7- AOB, Next meeting, meeting close ( Afternoon: ) Servomex presentations and Demo s Page 11

13 Page 12

14