ANSYS-2011-Cameron Thermal Oxidizer CFD Simulation-3

© 2011 ANSYS, Inc. April 10, 20231

Thermal Oxidizer Modeling Using Combustion CFD Analysis

Jagadeesh UnnamCAMERON Process SystemsTechnology Center

© 2011 ANSYS, Inc. April 10, 20232

Agenda

• Introduction to CAMERON Thermal Oxidizer

• Motivation for CFD Simulation

• Modeling process

• Parameter variations

• Results used towards product development

© 2011 ANSYS, Inc. April 10, 20233

• Emission control device– Designed for > 99.9 % DRE

(Destruction Removal Efficiency)

• Primary applications: – Glycol dehydration off gases

• Other applications:– Tank vapors, Amine unit off gases,

Casing gases

• Non-assisted, natural draft combustion chamber

• Designed to provide the three essential T’s

– Temperature– Time– Turbulence

CAMERON Thermal Oxidizer(SHV Combustor)

Inline Arrestor

Air Damper (secondary & Tertiary)

Liquid Drip Pot

Fuel gas

Air Inlet (Flame Arrestor)

Burner Nozzle

Shield

Chamber

Pilot

Eductor

Sample Ports

To blowcase

Waste gas from SHE

© 2011 ANSYS, Inc. April 10, 20234

• Verification of theoretical assumptions and test data

• Observation of performance– Temperature profile• Combustion zone• Wall

– Hydrocarbon concentrations– Flow dynamics of air inlet & exhaust flue gases

• Optimization of combustion air flow

• Air dampener adjustments

• Chamber size reduction

• Chamber wall Insulation

Motivation for CFD Simulation

© 2011 ANSYS, Inc. April 10, 20235

• Sizing basis from existing filed operated unit

– 66” x 30’ external chamber– SA 516-70 (Material)

– 32” x 12’ Internal shield– 309 SS (Material)

• CAMERON SHV® Eductor & Burner Design

• Adjustable air inlets– Primary– Secondary– Tertiary

• Flame Arrestors

Geometric Details

© 2011 ANSYS, Inc. April 10, 20236

• Simulation case based on field operating unit

• Gas Properties:– Flow rate : 2.6 lb/min (constant)– Gas Inlet Temp : 275 F– Gas velocity out of the nozzle: 30 fps

• Assumptions – Constant gas flow inlet– Gas as 100% methane– Ambient atmosphere – Constant convective heat transfer

Flow Conditions and Fluid Properties

© 2011 ANSYS, Inc. April 10, 20237

Solver Settings

• 2D axis symmetric, Steady Sate

Models used

• Standard k- model

• Discrete Ordinates (DO) Radiation Model

• Eddy-Dissipation model

Mesh Size

• 143,232

Modeling Details

© 2011 ANSYS, Inc. April 10, 20238

• Temperature

• Velocity

• Flow vectors

• Hydrocarbon concentration

• Air dampener opening

• Wall temperature profiles

• Effects of external chamber size reduction

Type of Analysis & Optimization

© 2011 ANSYS, Inc. April 10, 20239

Cases Studied - Variations in air dampener setting

(lb/m

in)

% S

toic

.

(lb/m

in)

% S

toic

.

(lb/m

in)

% S

toic

.

Shei

ld

Cham

ber

Shei

ld

Cham

ber

ppm

1. with FA (Sec. 50%, Ter 50%) 5 17% 91 282% 92 284% 3100 1600 810 499 22. with FA (Sec. 50%, Ter 25%) 5 17% 99 305% 80 248% 3100 1600 792 506 23. with FA (Sec. 50%, Ter 12.5%) 6 17% 106 327% 62 192% 3100 1600 764 525 24. with FA (Sec. 50%, Ter 6.25%) 6 17% 114 351% 42 129% 3100 1600 749 550 35. FA Closed 4 12% 17 53% 18 55% 700 2000 580 1062 2361

Avg. CH4

Mass Pri. Air Sec. Air Ter. Air

Estimated Peak Temp. (F)

Peak wall temp. (F)

Cases (w.r.t FA - Flame Arrestors orientation)

Flow Rate

Note: Due to orientation of the dampener plates, 50% open equals the maximum achievable opening

© 2011 ANSYS, Inc. April 10, 202310

Chamber Temperature Profile – Variations in air dampener setting

Case 1: Sec. – 50% Ter. – 50%

Case 2: Sec. – 50% Ter. – 25%

Case 3: Sec. – 50% Ter. – 12.5%

Case 4: Sec. – 50% Ter. – 6.3%

Case 5 : FA’s ClosedCase 5: Sec. – 50% Ter. – 50%

© 2011 ANSYS, Inc. April 10, 202311

Wall Temperature Profile – Variations in air dampener setting

© 2011 ANSYS, Inc. April 10, 202312

• As reduced air damper setting resulted in acceptable performance, a new sizing basis was simulated for confirmation

• Reduced external chamber: 52”x 30’

• 21% reduction in diameter

• Adjustment to air inlet orientation

Chamber Size Reduction

Inline Arrestor

Air Damper (secondary & Tertiary)

Liquid Drip Pot

Fuel gas

Air Inlet (Flame Arrestor)

Burner Nozzle

Shield

Chamber

Pilot

Eductor

Sample Ports

To blowcase

Waste gas from SHE

52”

30”

30’

© 2011 ANSYS, Inc. April 10, 202313

Chamber Size Reduction

0 5 10 15 20 25 300

100200300400500600700800900

1000

Reduced Chamber Dia. (Non-Insulated)

Chamber Wall

Sheild Wall

Height, ft

Wal

l Tem

p., F

© 2011 ANSYS, Inc. April 10, 202314

Temperature Contours

Chamber Size Reduction - Performance

Velocity Contours Velocity Vectors

© 2011 ANSYS, Inc. April 10, 202315


6. Uninsulated Outer Chamber 6 19% 140 431% 173 533% 3100 1600 755 515 27. Insulated Outer Chamber 6 20% 142 438% 181 558% 3100 1600 889 884 2

Reduced Chamber Cases (with FA's Sec. 50%, Ter. 50%)

(lb/m

in)

% S

toic

.

(lb/m

in)

% S

toic

.

(lb/m

in)

% S

toic

.

Shei

ld

Cham

ber

Shei

ld

Cham

ber

ppm


Avg. CH4



Peak wall temp. (F)


Flow Rate

© 2011 ANSYS, Inc. April 10, 202316


Hydrocarbon Contours

• Verification of the three T’s

• Velocity vectors enable to optimize air inlets & avoid recirculation

• High combustion efficiency

0-100% 0-5%

© 2011 ANSYS, Inc. April 10, 202317

Chamber Wall – Non-Insulated vs. Insulated

0 5 10 15 20 25 300

100

200

300

400

500

600

700

800

900

1000

Chamber Wall Temperature (Insulated & Non-Insulated)

Non-Insulated InsulatedHeight, ft

Wal

l Tem

p., F

Non-Insulated Insulated

© 2011 ANSYS, Inc. April 10, 202318

6. Uninsulated Outer Chamber 6 19% 140 431% 173 533% 3100 1600 755 515 27. Insulated Outer Chamber 6 20% 142 438% 181 558% 3100 1600 889 884 2

Reduced Chamber Cases (with FA's Sec. 50%, Ter. 50%)

(lb/m

in)

% S

toic

.

(lb/m

in)

% S

toic

.

(lb/m

in)

% S

toic

.

Shei

ld

Cham

ber

Shei

ld

Cham

ber

ppm


Avg. CH4



Peak wall temp. (F)


Flow Rate

Chamber Wall – Non-Insulated vs. Insulated

© 2011 ANSYS, Inc. April 10, 202319

• Able to study performance & system limitations

• Incorporated both flow & combustion models

• Results in accordance with filed data

• Size reduction to standard models

• Wall insulation effects

Conclusions

ANSYS-2011-Cameron Thermal Oxidizer CFD Simulation-3

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