CBC-PROCOS S.p.A. - Research and Development Laboratory - Calorimetry. Alessandro Barozza.

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2 CBC-PROCOS S.p.A. - Research and Development Laboratory - Calorimetry Alessandro Barozza barozza@procos.it Giornata di studio sullo Sviluppo e la Sicurezza dei Processi Chimici Palazzo Turati, Milano, 21 Ottobre 2015

3 T process MTSR MTSR Safety evaluation Thermal point of view Inherenthly safe process When no disturbance whatsoever can cause an accident T critical From a thermal point of view Inherenthly safe process Lack of thermal control Temperature Critical process T process Lack of thermal control T critical Temperature

4 How about gas production Industrial process Reactor fill 70% Gas production: 5 times of reaction mixture volume Pressure increase into a closed reactor: ~ +12 bar Sol. K 2 CO 3 3.1% w/v Sol. NaBH 4 0.2% w/v

5 And gas evolution speed?

6 Lab vs. production scale

7 Lab vs. production scale

8 Consideration about gas production a safety point of view What is the quantity and rate of gas evolution? How do these vary with process deviations can pressurization occur? What is the nature of the gas? Is toxic or odorous? Will it dissolve or react? What scrubber capacity will be required and if there is heat evolved can this be dissipated? Is the rate of gas generation compatible with the rate of reaction of the gas with the scrubbing medium? Are flammable gases evolved? What are their concentrations? Is oxygen evolution a possibility? What is the effect on flammability of the vapour in the reactor head space? Barton, Rogers, Chemical reactions hazards, second edition, 1997

9 Consideration about gas production a safety point of view What is the quantity and rate of gas evolution? How do these vary with process deviations can pressurization occur? These issues are only What is the nature of the gas? Is toxic or odorous? Will it dissolve or react? related to the desired What scrubber capacity will be required and if there is heat evolved can this be dissipated? reaction!!! Is the rate of gas generation compatible with the rate of reaction of the gas with the scrubbing medium? Are flammable gases evolved? What are their concentrations? Is oxygen evolution a possibility? What is the effect on flammability of the vapour in the reactor head space? Barton, Rogers, Chemical reactions hazards, second edition, 1997

10 Undesired reaction (runaway characterization) Gas flow is calculated by examining the dp/dt signal (Pressure Flow)

11 Desired reaction How to measure gas evolution Quantitative By weight Flowmeter Mass flowmeter Turbine flowmeter ph controlled Scrubber Qualitative Chemistry knowledge Spectrometric techniques (MS, IR )

12 Desired reaction Gas measure by weight The gas is absorbed into a proper solution by bubbling and the solution+adsodbed gas is continuously weighted over a balance Issues: Is absorption quantitative? Self heating of the flask Signal is noisy because of bubbles

13 Desired reaction Gas measure by mass flow-meter FLOW (mol/time) = f(dt, Cp gas, )

14 Mass flow-meter & RC1 Thermal stability of Ca-Borohydride in EtOH Gas Flow (NmL/sec as H 2 ) Gas Flow Total Gas Total H 2 (NL) Qr Q (W) Temperature Temperature ( C) Time (hours) -20

15 Mass flow-meter & RC1 - de-boc procedure

16 Mass flow-meter & RC1 - Phenol Alkylation Temperature ( C) Temperature CO 2 Outlet Flow (NmL/sec) CO 2 Outlet Flow Total Evolved CO Total Evolved CO 2 (NmL) Time (hours)

17 Desired reaction Gas measure by mass flow-meter Pros Easy to use Very low ΔP (1-2 mbar) Direct connection to RD10 (analog) or PC (digital USB) Online reading of flow value (no correction is needed) as NLt/time Durable Can be also used for a smaller scale (Easymax 100 ml reactors) Cons Made of metal Not completely quantitative for a gas mixture of unknown composition

18 X Cable Relay ON Condenser Scrubber GAS OUT Desired reaction Auto-titrating scrubber Water Pump 1 Nitrogen 10Nlt/h RC1 Reactor Balance 1 Scrubber Tank ph electrode C1 R3 RD10 ph

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20 Auto-Titrating scrubber - HCl emission R COONa xh 2 O POCl 3 R COCl + HCl moli HCl ,6 0,5 0,4 Temperatura ( C) Tr Flusso HCl T testa mmoli HCl 0,3 0,2 0,1 0,0-0,1-0,2 Flusso HCl (mmoli/sec) ,3 Tempo (min)

21 Original data from RC1-RD10 FLOW HCl = dg NaOH/dt Assay% NaOH 100 MW NaOH L/mol

22 Desired reaction Auto-titrating scrubber Pros Measure of corrosive streams Very low ΔP Cons Complicated setup Signal elaboration procedure is time demanding Concentration gradient (problem when free volume is high) Not easily applicable for a smaller scale

23 Desired reaction Turbine Flow-meter

24 Turbine flow-meter linearity

25 Condenser Turbine flow-meter linearity Mass flow-meter Turbine flow-meter N 2 flow 2 ml/sec RC1 reactor N 2 Flow

26 Turbine flow-meter Pressure drop vs. flow mol time = P FLOW R T = f(flow) FLOW R T Transfer energy between Gas and Turbine mol time = f(flow) f(d, ɳ, T) FLOW R T

27 Reaction using PCl3

28 Reaction using Thionyl Chloride Dos Stop 5 70 Gas Flow (ml/sec) Total gas Outlet gas flow Total gas (L) Power (W) Stoichiometric Point Thermal Conversion: 82.7% Sum of masses (SOCl 2 + Alcohol) Power Reaction mass Reaction mass (g) Time (hours)

29 Desired reaction Gas measure by turbine flowmeter Pros Can be used when gas stream is very corrosive (plastic & glass made) Good precision & stability Direct connection to RD10 (analog) Cheap Cons Instrument setup is quite complex and requires some other equipments Volumetric measure We considered it as «disposable» Can t be used in a smaller scale (higher pressure drop)

30 Small scale (Easymax) Smaller tubing High pressure drop Free volume issues Carrier gas may cause a strong noise Ambient influence is relevant

31 Small scale (Easymax) Mass Flowmeter

32 EasyMax COOH activation

33 Automatic gas burette Barton, Rogers, Chemical reactions hazards, second edition, 1997

34 Calculate the final FLOW n 1 = P V R T = 1 (V free) R T n 2 = P V R T = (1 + ΔP) (ΔV + V free) R T ΔV ΔP Δn = n 2 n 1 = ΔV + V free + ΔPΔV + ΔPV free R T V free R T Δn = ΔV + ΔP(ΔV + V free) R T FLOW = Δn Δt ΔV ΔP

35 Procos automatic system - How it works Time Start Time Stop Recondition time: ~ 2s

36 Procos Automatic System

37 System Datasheet Procos Automatic System ΔV 0.3 ml Δh 15 mm (+ 2 mm ZERO ) ΔP < 1.3 mbar (medium: mineral oil) Timer resolution: 4ms Response Time FLOW: linear, first order function The system is controlled by a PC, running a home made software Flow Output on Excel file Analog Output: 0 5V prop. to meas. flow

38 Anyline to Phenol It s important that diazonium salt gives immediately the phenol, just after formation, avoiding its accumulation Temperature: 25 C Gas FLOW as direct function of dosage Analytical measure Nitrogen is not corrosive but gaseous stream may contain acidity or nitrogen oxides

39 Anyline to Phenol

40 Anyline to Phenol Acquisition rate ~ 10 samples/min 0.16Hz

41 Conclusions There is no an universal system for determining gas evolution during a calorimetric investigation but for a correct safety evaluation of a chemical process, both gas evolution during the desired reaction and during runaway has to be carefully determined

42 Giornata di studio sullo Sviluppo e la Sicurezza dei Processi Chimici Palazzo Turati, Milano, 21 Ottobre 2015 Alessandro Barozza barozza@procos.it