TOPOLOGICAL CRITERIA FOR SAFE OPTIMIZATION OF POTENTIALLY RUNAWAY PROCESSES

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1 DIPARTIMENTO DI CHIMICA, MATERIALI ED INGEGNERIA CHIMICA "Giulio NATTA INNOVHUB STAZIONI SPERIMENTALI PER L INDUSTRIA Divisione Stazione Sperimentale per i Combustibili Seminario Aspetti innovativi in materia di rischi di incidenti rilevanti Varese, 14 Novembre 2011 TOPOLOGICAL CRITERIA FOR SAFE OPTIMIZATION OF POTENTIALLY RUNAWAY PROCESSES *, Marco Derudi*, Renato Rota*, Angelo Lunghi**, Christian Pasturenzi** *Politecnico di Milano - Dip. di Chimica, Materiali e Ingegneria Chimica G. Natta - CFALab via Mancinelli Milano Italy **INNOVHUB STAZIONI SPERIMENTALI PER L INDUSTRIA - Divisione Stazione Sperimentale per i Combustibili viale De Gasperi S. Donato Milanese, Italy

2 ACCIDENTS IN CHEMICAL INDUSTRIES Over 100 accidents per year occur in a typical European country in chemical industries. CAUSES 36% Chemical incompatibility 35% Runaway reactions 10% Instable substances 19% Unidentified A statistical analysis, performed by U.S. Chemical Safety and Hazard Investigation Board, shows that a large amount of accidents occurs in exothermic chemical reactors during desired synthesis runs. 2

3 THE PROBLEM RUNAWAY EXOTHERMIC PHENOMENON caused by a temperature loss of control 3

4 RUNAWAY DYNAMICS: PREVIEW T ( C) Desired Reaction Secondary Reaction T max MTSR MAT T p MTSR > MAT Q r /C p,mix =ΔT ad T p : process temperature MTSR: Maximum Temperature due to Synthesis Reaction in adiabatic conditions MAT: Maximum Allowable Temperature T max : Maximum temperature due to secondary reaction TMR: Time to Maximum Rate of temperature increase T amb Reaction carried out in adiabatic conditions Thermal loss of control TMR t 4

5 T2 LABORATORIES ACCIDENT 5

6 T2 LABORATORIES ACCIDENT T2 plant after reactor explosion 6

7 T2 LABORATORIES ACCIDENT Control room 7

8 T2 LABORATORIES ACCIDENT A nearby factory 8

9 T2 LABORATORIES ACCIDENT On the road 9

10 T2 LABORATORIES ACCIDENT Runaway reaction Production of MCMT Metalation Reaction (reactants: MCPD dimer, Na - solvent: diglyme) Substitution Reaction Carbonylation Reaction 10

11 T2 LABORATORIES ACCIDENT Reactor Layout and Control System Software View 11

12 RUNAWAY DYNAMICS T ( C) Desired Reaction Secondary Reaction T max MTSR MAT T p MTSR > MAT Q r /C p,mix =ΔT ad T p : process temperature MTSR: Maximum Temperature due to Synthesis Reaction in adiabatic conditions MAT: Maximum Allowable Temperature T max : Maximum temperature due to secondary reaction TMR: Time to Maximum Rate of temperature increase T amb Reaction carried out in adiabatic conditions Thermal loss of control TMR t 12

13 STATE OF THE ART In order to face the runaway problem : 1- Studies aimed to determine the MARGINAL IGNITION boundary set of operating conditions at which RUNAWAY occurs - Methods based on PARAMETRIC SENSITIVITY (e.g. Morbidelli et al., Parametric Sensitivity in Chemical Systems, 1999) - Methods based on CHAOS THEORY (e.g. Zaldivar et al., A general criterion to define runaway limits in chemical reactors, 2003) 2- Studies aimed to determine the QFS operating region high safety and productivity - Methods based on CO-REACTANT ACCUMULATION MINIMIZATION (e.g. Molga and Westerterp, No More Runaways in Fine Chemical Reactors, 2004) 13

14 THE LIMITS - Limits of the methods belonging to first group: They are not able to detect safe and productive operating conditions (QFS) - Limits of the methods belonging to the second group: They are able to treat only systems involving a single reaction 14

15 ENTERPRISES REQUIREMENTS Chemical enterprises treat complex reacting systems and want to achieve these goals: 1- High productivity 2- Safe conditions 3- Low kinetic and thermo-chemical investigation costs SAFE PROCESS OPTIMIZATION A problem not be faced yet 15

16 MAIN AIM OF THE WORK Development of safe, reliable and low-cost OPTIMIZATION PROCEDURES able to treat COMPLEX REACTING SYSTEMS (e.g. multiple and chain reactions) for ISOPERIBOLIC SEMIBATCH REACTORS 16

17 WORK OUTLINE 1- Development of a TOPOLOGICAL THEORY and a non-arbitrary definition of high productive operating conditions for both simple and complex reacting systems 2- EXPERIMENTAL VALIDATION of the topological method 3- Development of a generalized OPTIMIZATION PROCEDURE based on the topological theory 4- Development of an EXPERIMENTAL topological OPTIMIZATION PROCEDURE 5- CONCLUSIONS 17

18 WORK OUTLINE 1- Development of a TOPOLOGICAL THEORY and a non-arbitrary definition of high productive operating conditions for both simple and complex reacting systems 2- EXPERIMENTAL VALIDATION of the topological method 3- Development of a generalized OPTIMIZATION PROCEDURE based on the topological theory 4- Development of an EXPERIMENTAL topological OPTIMIZATION PROCEDURE 5- CONCLUSIONS 18

19 TOPOLOGICAL APPROACH What is TOPOLOGY? Topology studies the base properties of n- dimensional objects called manifolds, namely the properties that depend only on the fold; distances, which are fundamental to study the geometry of an object, are ignored. Möbius Strip Klein Bottle Umbilic Torus 19

20 TOPOLOGICAL APPROACH How can TOPOLOGY be useful for safe process optimization? 20

21 21 TOPOLOGICAL CRITERION THEORY Let us consider the following system of ODEs that describes a generic isoperibolic SB process: R B X D Desired Product M P Dosed Reactant 0 0, , 1 1 0, 0. 1,2,...,,,,, cool i i eff cool NR j j ad j NR j j j j i C I N i d d d d d d d d f RE Da d d exo i

22 TOPOLOGICAL CRITERION THEORY The solution is a monodimensional variety called: TRAJECTORY Phase Space 2 It is not important how many dependent variables 1 define a point of the trajectory because a trajectory is always a finite lenght line... and all finite lines are homeomorphic each other 22

23 TOPOLOGICAL APPROACH How a TRAJECTORY evolves changing one system constitutive parameter (as t dos ) or initial condition (as T cool )? It evolves exhibiting the same limited set of physical phenomena 23

24 TOPOLOGICAL CRITERION THEORY Let us generate the phase portraits (PPs) corresponding to this ODEs system when T cool (or t dos ) is varied and a consecutive reactions (or an emulsion polymerization) scheme is implemented. T cool t dos 24

25 TOPOLOGICAL APPROACH No NOTABLE PROPERTIES can be detected observing such PPs... We need a MATHEMATICAL TRICK 25

26 TOPOLOGICAL CRITERION THEORY Considering that our aims are: - System Thermal Characterization - Maximization of reactor productivity we can decide to explore the trajectory evolution only looking for: - Temperature - Conversion with respect to the desired product and we can generate a 2D-chart called X-space 26

27 TOPOLOGICAL CURVE... which reports the maximum of each trajectory with respect to temperature as a function of the X-conversion at such a maximum. T cool t dos 27

28 TOPOLOGICAL APPROACH TOPOLOGICAL CURVES for the following reacting schemes have been generated: 1- Single Reaction with autocatalytic behavior 2- Single Reaction without autocatalytic behavior 3- Two Consecutive Reactions (the first with autocatalytic behavior) 4- Chain Reactions (solution and emulsion homopolymerizations) 5- Autocatalytic Catalyzed Reactions 28

29 CHARACTER OF THE INVERSION POINTS T cool Topological Curve t dos Topological Curve 1- Transition RW before t dos 1- Transition RW after t dos RW after t dos RW before t dos RW before t dos RW before t dos 2- QFS 2- QFS QFS QFS RW after t dos QFS 3- Runaway QFS 3- Starving STV 29

30 QFS TOPOLOGICAL CRITERION THEOREM Theorem: Independently on which is the topological curve generating parameter Whenever an inversion of the topological curve with a concavity towards right is observed a QFS boundary is detected Corollary: The QFS inversion represents an intrinsic behavior of the system 30

31 THEORETICAL VALIDATION of the COROLLARY Topological Criterion intrinsicity validation through parametric sensitivity Two consecutive reactions: nitric acid oxidation of 2-octanol to 2-octanone 31

32 WORK OUTLINE 1- Development of a TOPOLOGICAL THEORY and a non-arbitrary definition of high productive operating conditions for both simple and complex reacting systems 2- EXPERIMENTAL VALIDATION of the topological method 3- Development of a generalized OPTIMIZATION PROCEDURE based on the topological theory 4- Development of an EXPERIMENTAL topological OPTIMIZATION PROCEDURE 5- CONCLUSIONS 32

33 EXPERIMENTAL VALIDATION of the THEOREM CASE STUDY n 1: Emulsion Homopolymerization of Vinyl Acetate thermally initiated by KPS DSC characterization KPS SLS PVA MAT parameter Laboratory tests (50 ml) at different monomer dosing rates Minimum Boiling Point: EMAT = 83 C 33

34 EXPERIMENTAL VALIDATION of the THEOREM CASE STUDY n 1: Emulsion Homopolymerization of Vinyl Acetate thermally initiated by KPS Kinetics and other parameters Determination of kinetic and constitutive model parameters through fitting of T vs. t isoperibolic RC1 data (test at t dos = 10 min) 34

35 EXPERIMENTAL VALIDATION of the THEOREM CASE STUDY n 1: Emulsion Homopolymerization of Vinyl Acetate thermally initiated by KPS Topological Evaluation Dosing times [min] Topological Classification RUN RW RUN 2 10 RW RUN RW/QFS RUN 4 15 QFS RUN 5 30 STV 35

36 EXPERIMENTAL VALIDATION of the THEOREM CASE STUDY n 1: Emulsion Homopolymerization of Vinyl Acetate thermally initiated by KPS Experimental Classification RUN 1 RW boiling foam RUN 2 RW RUN 3 RW/QFS boiling light t dos boiling RUN 4 QFS no boiling 36

37 EXPERIMENTAL VALIDATION of the THEOREM Results comparison for case n 1 Topological Classification Experimental Classification RUN 1 RW RUN 1 RW RUN 2 RW RUN 2 RW RUN 3 RW/QFS RUN 3 RW/QFS RUN 4 QFS RUN 4 QFS RUN 5 STV RUN 5 STV Experimental validation of the topological curve inversions 37

38 EXPERIMENTAL VALIDATION of the THEOREM CASE STUDY n 2: Oxidation of 2-octanol to 2-octanone by nitric acid 1) (A) OH NO (B) (C) O NO (B) 2) O NO Mixture of (C) (B) (D) carboxylic acids

39 EXPERIMENTAL VALIDATION of the THEOREM CASE STUDY n 2: Oxidation of 2-octanol to 2-octanone by nitric acid Topological Evaluation (Data from a literature case-study) C-Space T cool Topological Classification [ C] RUN 1 1 QFS C RUN 2 7 NO IGN/RW RUN 3 17 RW RUN 4 31 QFS D QFS Inversion RUN 1 Runaway Inversion Transition Inversion RUN 2 RUN 5 60 QFS D ζ c (Ψ MAX ) [-] 39

40 EXPERIMENTAL VALIDATION of the THEOREM CASE STUDY n 2: Oxidation of 2-octanol to 2-octanone by nitric acid Topological Evaluation (Data from a literature case-study) D-Space T cool [ C] Topological Classification RUN 1 1 QFS C Transition Inversion RUN 2 7 NO IGN/RW RUN 3 17 RW RUN 4 31 QFS D QFS Inversion RUN 3 RUN 4 RUN 5 RUN 5 60 QFS D 40

41 EXPERIMENTAL VALIDATION of the THEOREM CASE STUDY n 2: Oxidation of 2-octanol to 2-octanone by nitric acid T cool Experimental Classification RUN 1 QFS C RUN 3 RW RUN 5 QFS D RUN 2 NO IGN RUN 4 QFS D 41

42 EXPERIMENTAL VALIDATION of the THEOREM Results comparison for case n 2 Topological Classification Experimental Classification RUN 1 QFS C RUN 1 QFS C RUN 2 MI 2 RUN 2 MI 2 RUN 3 RW RUN 3 RW RUN 4 QFS D RUN 4 QFS D RUN 5 QFS D RUN 5 QFS D Experimental validation of the topological curve inversions 42

43 WORK OUTLINE 1- Development of a TOPOLOGICAL THEORY and a non-arbitrary definition of high productive operating conditions for both simple and complex reacting systems 2- EXPERIMENTAL VALIDATION of the topological method 3- Development of a generalized OPTIMIZATION PROCEDURE based on the topological theory 4- Development of an EXPERIMENTAL topological OPTIMIZATION PROCEDURE 5- CONCLUSIONS 43

44 TOPOLOGICAL OPTIMIZATION PROCEDURE Scheme of the optimization procedure: 1- Choose desired X-conversion; 2- Experimental determination of the MAT parameter and kinetics; 3- Choose a generating parameter: e.g. T cool 4- Choose an iterating parameter: e.g. t dos 5- Starting from a minimum t dos, search for the QFS inversion; 6- If T MAX (T cool,qfs ) < MAT and X-conversion is above the desired one, t dos,opt and T cool,opt have been determined; 7- If T MAX (T cool,qfs ) > MAT or X-conversion is under the desired one, t dos must be increased until convergence. If convergence is not reached the process can not be carried out in isoperibolic mode shift to isothermal mode. 44

45 WORK OUTLINE 1- Development of a TOPOLOGICAL THEORY and a non-arbitrary definition of high productive operating conditions for both simple and complex reacting systems 2- EXPERIMENTAL VALIDATION of the topological method 3- Development of a generalized OPTIMIZATION PROCEDURE based on the topological theory 4- Development of an EXPERIMENTAL topological OPTIMIZATION PROCEDURE 5- CONCLUSIONS 45

46 EXPERIMENTAL DESIGN OF THE CURVE CASE STUDY: Solution Homopolymerization of Butyl Acrylate in Ethyl Acetate initiated by AIBN Topological Space 46

47 WORK CONCLUSIONS 1- Development of a TOPOLOGICAL THEORY and a nonarbitrary definition of QFS conditions for both simple and complex reacting systems 2- EXPERIMENTAL VALIDATION of the topological method 3- Development of generalized OPTIMIZATION PROCEDURES based on the topological theory 4- Development of an EXPERIMENTAL based topological OPTIMIZATION PROCEDURE 47