IUAPPA 2010 – September 12-16 2010

E i t l M t A d M

IUAPPA 2010 September 12 16, 2010Session 4B – Emerging Control Technologies

Control #90

Experimental Measurements And Mass Transfer/Reaction Modeling For An Industrial NO Absorption ProcessIndustrial NOx Absorption Process

Kyle LoutetProcess Engineer, NORAM Engineering

A. Mahecha-Botero, S. Buchi, T. Boyd, C. BreretonNORAM Engineering & Constructors Ltd.

1

Executive Summary• Performance data collected from

industrial scale NOx absorption columnx

• Rate-based model of NOx absorption xcolumn developed in Aspen Plus

• Validation of model with collected data

• Use of model to rate existing designs and develop innovative new designs

2

Company Background• Local, privately-owned engineering

firm founded in 1988• Business Areas

Nitrationa oSulphuric AcidElectrochemical Granville Square

Biological WastewaterPulp and PaperEnvironmental RemediationEnvironmental RemediationNew Technology Development

Annacis Island

3

Introduction – Nitration Technologies

• Specialization in engineering and technology for the production oftechnology for the production of mononitrobenzene (MNB)

12 l t d i d/ i i d t• 12 plants designed/commissioned to date (>50% of global capacity)

• Product used mainly in manufacture of polyurethane plasticpolyurethane plastic

4

Introduction – Nitration Technologies

5

Introduction – MNB Process

Benzene + Nitric Acid → MNB + Water + Byproductsyp

6

Introduction – NOx FormationAliphatics Decomposition:

C6H12 + 8 HNO3 → 3 C2H2O4 + 8 H2O + 10 NOC6H12 8 HNO3 3 C2H2O4 8 H2O 10 NO

Nitrous Acid Decomposition:C6H6 + 3 HNO3 → C6H3(NO2)2OH + 2 H2O +

HNO2

3 HNO2 → HNO3 + H2O + 2 NO~600 g NO per tonne MNB product~600 g NO per tonne MNB product → 240 tonnes NOx per year

~14,000 passenger vehicles14,000 passenger vehicles→ 500 tonnes/yr savings in nitric acid

7

Introduction – Fate of NOx• NOx separated from liquid products and

captured in NOx scrubber (2 packed beds)

Development of rate-based model of scrubber is basis for study

2 NO + 1 5 O + H O 2 HNO2 NO(g) + 1.5 O2 + H2O → 2 HNO3

2 NO(g) + 0.5 O2 + H2O → 2 HNO2

8

Experimental Methods – Data Collection

• Existing MNB plant (400,000 T/yr) in UK selected for studyT/yr) in UK selected for study

• Vent gases from NOxScr bber tested for NO NOScrubber tested for NO, NO2

• Nitric and nitrous acid levels in liquid effluent measured

• Gas flow to/from column Huntsman Polyurethanes Wilton MNB plant in Redcar, UK –

measured commissioned in 1997

9

Experimental Methods – Data Collection

• Data set created from experimentation• 17 trials performed• 17 trials performed• Due to plant factors such as safety and

environmental constraints ability to changeenvironmental constraints, ability to change conditions in the NOx column limited

• Conditions of elevated and reduced pressure and• Conditions of elevated and reduced pressure and temperature were obtained

• Data included in AppendixData included in Appendix

10

Experimental Methods – ModelingExperimental Methods - Modeling• Reaction sets identified for gas and liquid phases

Gas Phase1 Liq id Phase2Gas Phase1 Liquid Phase2

R1: 2 NO + O2 → 2 NO2 R6: 2 NO2 + H2O → HNO3 + HNO2

R2: 2 NO2 ↔ N2O4 R7: N2O3 + H2O → 2 HNO2

R3: NO + NO2 ↔ N2O3 R8: N2O4 + H2O → HNO3 + HNO2

R4: N2O3 + H2O ↔ 2 HNO2 R9: 3 HNO2 → HNO3 + H2O + 2 NO

R5: N2O4 + H2O ↔ HNO3 + HNO2

11

Experimental Methods – ModelingExperimental Methods - Modeling• Reaction set implemented into Aspen Plus

RadFrac block with RateSep add-on.RadFrac block with RateSep add on.

V-OUT

L-INPlug flow reactor

TRAYS

Radfrac with

reactorPACKING

TO-COLFROM-BOT

EMPTY-SP

RateSep

L-OUT

12

Results and Discussion – Upper Packed Bed

Experimental Methods - Modeling

Average discrepancy of 2.8%g y

13

Results and Discussion – Upper Packed Bed

• Well-predicted trends for temperature• Well-predicted trends for temperature and pressure

14

Results and Discussion – Lower Packed Bed

Experimental Methods - Modeling

Average discrepancy of 3.5%g y

15

Results and Discussion – Lower Packed Bed

• Well-predicted trends for temperature• Well-predicted trends for temperature and pressure

16

Model Implementation – An Example

Bleaching section preventsdissolved NOx from being circulated to upper section ppof column

17

Model Implementation – An Example

18

~2000 ppm improvement in NOx capture

ConclusionsExperimental Methods - Modeling• Effective and reliable model created in Aspen

Plus simulation environmentPlus simulation environment• Model successfully predicts NOx absorption

into water• Further work required to extent model’s

validity over full range of possible operating conditions and improve convergence

• Model is being used to design new columns, test new configurations and ultimately reduce NOx plant emissions

19

AcknowledgementsExperimental Methods - Modeling• NORAM thanks Huntsman Polyurethanes

(UK) Ltd. and their Wilton operating staff for(UK) Ltd. and their Wilton operating staff for allowing access to their facility and supplying the crucial plant data required for model validation.

20

Questions and Comments

Kyle Loutet Process EngineerKyle Loutet – Process EngineerNORAM Engineering & Constructors

Phone: 604-681-2030 ext. 221E-mail: kloutet@noram-eng.com

Address: 200 Granville St – Suite 1800Vancouver BC V6C 1S4Vancouver, BC V6C 1S4

21

Experimental Methods - Modeling

APPENDIXAPPENDIX

Experimental DataExperimental Methods - Modeling

Reaction Rate ExpressionsExperimental Methods - Modeling

Reaction Stoichiometry Rate Expression

G PhGas PhaseR1 2 NO + O2 → 2 NO2 k1/2*[NO]2*[O2]

R2 2 NO2 ↔ N2O4 k2*[NO2]2 - k2/K2*[N2O4]R3 NO + NO2 ↔ N2O3 k3*[NO][NO2] - k3/K3*[N2O3]R4 N2O3 + H2O ↔ 2 HNO2 k4*[N2O3][H2O] – k4/K4*[HNO2]2

R5 N2O4 + H2O ↔ HNO3 + HNO2 k5*[N2O4][H2O] – k5/K5*[HNO3][HNO2]Liquid PhaseR6 2 NO2 + H2O → HNO3 + HNO2 k6*[NO2]2

R7 N2O3 + H2O → 2 HNO2 k7*[N2O3]R8 N2O4 + H2O → HNO3 + HNO2 k8*[N2O4]R9 3 HNO2 → HNO3 + H2O + 2 NO k9*[HNO2]4/pNO

2

Kinetic Reaction ParametersExperimental Methods - Modeling

Reaction Kinetic Factor Units Reference

R1 (10(6521/T – 0.7356))*(RT/101,325) m6kmol-2s-1 3

R4 41,000 m3kmol-1s-1 1

R5 250 m3kmol-1s-1 1

R6 104.67209 m3kmol-1s-1 4

R7 104.23044 s-1 5

R8 10(-4139/T + 16.3415) s-1 6

R9 10(-6200/T + 20.1979) atm2m9kmol-3s-1 6

Equilibrium Reaction ParametersExperimental Methods - Modeling

Reaction Kinetic Factor Units Reference

R2 (10(2993/T – 9.223))*(RT/101,325) m3kmol-1 7

R3 (10(2072/T – 7.234))*(RT/101,325) m3kmol-1 8

R4 (10(10.83/T – 0.5012)) - 1

R5 (10(965.5/T – 1.481)) - 1

ReferencesExperimental Methods - Modeling

1. Patwardhan and Joshi (2003). AIChE J. 49, 2728-2748.

2. Hupen and Kenig (2005). Chem. Eng. Sci. 60, 6462-6471.

3. Joshi et al. (1985). Chem. Eng. Commun. 33, 1-92.

4. Lee and Schwartz (1981). J. Phys. Chem. 85, 840-848.

5 Corriveau (1971) Master’s Thesis UC Berkeley5. Corriveau (1971). Master s Thesis. UC Berkeley.

6. Wendel and Pigford (1958). AIChE J. 4, 249-256.

7. Bronsted (1922). Z. Phys. Chem. 102, 169-207.

8. Beattie and Bell (1947). J. Chem. Soc. 790-801.