CFD modelling of multiphase flows in oil and gas,

chemical and process industries

Simon Lo 13/09/2011

simon.lo@cd-adapco.com

Contents

• Shell-&-tube heat exchanger – flow, thermal & stress

• T-junction, thermal sleeve – thermal stripping, FSI

• Gas-liquid flow in pipeline and riser – sever slugging

• STAR-OLGA coupling – 1D + 3D modelling

• Offshore platform – wave impact, lifeboat launch

• Process equipment – mixing vessel, particle conveying

EGR (Exhaust Gas Recirculation) cooler

EGR cooler: Conjugate Heat Transfer Model

• 148 tubes

• 3.5 million cells model

Steel

570,000 cells

Tube-side:

EGR Gas

1.8 million cells

Shell-side:

Coolant

1.2 million cells

Computed Mass Flux Through the EGR Tubes

0.509 0.521 0.531 0.507

0.540 0.545 0.519 0.514 0.522 0.505 0.480

0.558 0.571 0.558 0.587 0.575 0.554 0.526 0.478 0.478 0.461

0.560 0.594 0.568 0.681 0.722 0.732 0.686 0.595 0.503 0.456 0.449

0.601 0.636 0.692 0.857 0.876 0.854 0.794 0.656 0.504 0.439 0.445

0.567 0.659 0.773 0.883 0.916 0.926 0.915 0.892 0.816 0.674 0.433 0.428 0.435

0.641 0.782 0.886 0.940 0.941 0.940 0.928 0.896 0.819 0.396 0.433

0.608 0.711 0.868 0.920 0.943 0.951 0.935 0.921 0.881 0.786 0.597 0.444 0.440

0.648 0.795 0.896 0.935 0.945 0.935 0.928 0.904 0.848 0.703 0.525 0.439

0.566 0.687 0.826 0.910 0.928 0.935 0.927 0.907 0.867 0.764 0.594 0.453 0.443

0.578 0.687 0.827 0.887 0.901 0.911 0.901 0.863 0.780 0.628 0.474 0.442

0.569 0.648 0.779 0.836 0.860 0.827 0.771 0.632 0.493 0.450

0.512 0.596 0.688 0.705 0.723 0.748 0.702 0.572 0.478 0.437

0.527 0.604 0.638 0.622 0.580 0.509 0.454

0.509 0.510 0.496 0.476

Total Mass Flow: 0.244944 kg/secPercent of Total Flow

Coolant Pressure & Temperature Contours

Pressure

Temperature

Coolant Temperature & Heat Transfer Coefficient

Heat transfer coefficient

Temperature

Coolant Boiling Areas

Exhaust Gas Pressure & Temperature Contours

Pressure

Temperature

Metal Temperature Contours

Key Results: Coolant Boiling

• Two regions where boiling of

the coolant might occur

(Shown as red regions).

1. Close to the fire plate, due

to high metal temperatures

and lack of circulation.

2. Behind the first baffle, due

to lack of circulation.

Design Assessment of an EGR Cooler

Integrated CFD/FEA Methodology

• CFD Analysis Used to Determine:

• Heat Transfer Coefficients

• Core Pressure Drop Characteristics

• Flow Distributions in Manifolds and Core

• FEA Analysis Used To Determine:

• Transient Temperatures

• Transient Thermal Stresses

• Vibratory Stress

• CFD Analyses performed using STAR-CD

• FEA Analyses performed using ANSYS

CFD Coolant Flow Model

Coolant model used to

develop heat transfer

boundary conditions.

CFD Exhaust Gas Models

Exhaust Gas model used to

develop manifold heat transfer

boundary conditions, and

develop mass flow split in

core. Detailed tube model

captures local effects.

FEA Thermal Analysis – Gas Boundary Conditions

Start of Spiral

End of Spiral

Entrance Effect

CFD

FEA

Gas BC‟s mapped from CFD to FEA.

Detailed pipe model results used for

tube surfaces. Mass flow split

obtained from CFD as well. Core

gas temperatures developed through

use of pipe flow network

FEA Thermal Analysis Coolant Boundary Conditions

Coolant BC‟s mapped from CFD to FEA.

Boiling effects considered in FEA.

FEACFD

FEA Model

Overall Model

Detailed Tube Model

Thermal Analysis Transient Temperatures

Transient thermal run simulates

test cycle. These temperatures

provide the basis for the thermal

stress analysis.

Results are tracked to obtain the

time points that produce the largest

thermal gradients.

Thermal Stress Analysis

Thermal strain ranges are calculated at each

location, and between all time points. This

determines the greatest strain range experienced

for all locations.

Zeses Karoutas et al. Westinghouse Electric Company

Top Fuel 2010, Orlando, Florida, September 26-29, 2010

AP1000 PWR - Virtual Simulators

Pipe elbows and joins

Thermal solution

Stress analysis

Erosion modeling

International Benchmark – OECD T junction

23S.T. Jayaraju, E.M.J. Komen: Nuclear Research and Consultancy Group (NRG), Petten,

The Netherlands

T-junction Benchmark Results – Blind test

Wall Resolved LES

normalized flow profiles at 2.6 diameters

downstream of the mixing zone

normalized flow profiles at 1.6 diameters

downstream of the mixing zone

S.T. Jayaraju, E.M.J. Komen: Nuclear Research and Consultancy Group (NRG), Petten, The Netherlands

Thermal sleeve failed after 40 days operation.

Vibration issues.

Fluid-structure interaction (FSI) modelling:

Structure modeled totally within STAR-CCM+

Fluid grid morphed to conform

Implicit fluid/solid coupling

Thermal Sleeve

Flow in and around a Christmas tree

Oil and gas flow in 100m pipeline

Sever slugging in riser, Uni of Cranfield, UK

4 inch riser

55 m pipeline

10.5 m

Riser top

Riser base

Riser DP = Pbase - Ptop

50 100 150 200 250 300 3500

0.2

0.4

0.6

0.8

1

Flow time t, s

Ris

er

DP

, bar

Experiment

Star-CD-1

Star-CD-2

Dynamic forces on pipe elbow in slug flow

Mass flux, velocity and density of each phase

Pressure and temperature

Flow direction

Model the long pipe

using OLGA with slug

tracking

Model pipe elbow using STAR-CCM+

Pressure variation due to slug flow pass elbow

Gas volume fraction Pressure on the outer part

Note the passing of liquid

slug in “blue”.

Note the increase in pressure as

liquid slug passes.

Resultant force and force

components on the inner part

Forces on the inner part

5 6 7 8 9 10 11 12 13 14 15-30

-20

-10

0

10

20

30

Flow time t, s

Forc

e o

n t

he inner

wall

FI,

N

5 10 150

0.2

0.4

0.6

0.8

1

Liq

uid

hold

up H

L in t

he b

end

FRI

: Resultant force of FxI

and FyI

FxI

: x component

FyI

: y component

FzI

: z component

Direction change

Comparison

Coupling model Experiment

Slug frequency (Hz) 0.5 0.5

Slug velocity (m/s)slug front: 2.8 to 3.6

slug tail: 3.0 to 3.53.6

Peak force on bend (N) 44 to 54 40 to 60

Maximum force on bend (N) 54 60

In industrial design with safety factor „2‟: maximum force 141 N

EXXON-MOBIL SLUG CATCHER

• Tanks 45 m long, 3 m diameter.

• Time scale large (2 hours)

• CFD Model: 2.2 Million cells.

Inlet

Gas Outlets

Oil Outlets

EXXON-MOBIL SLUG CATCHER (Upstream Olga Model)

(24 Km)

(200m)

EXXON-MOBIL SLUG CATCHER

Wave loading on platform

• High fidelity with multi-physics:

• Wind and wave loadings

• Stress

High fidelity, large domain, time dependent

Launching of life boat

LIFEBOAT LAUNCHING

• combined 6 DOF, overlapping mesh, VOF (compressible)

Palermo mixer: Effect of rpm on particle suspension

300 rpm

380 rpm

480 rpm39

Mixing of viscous liquids

• An example of a mixer for highly viscous liquids, with small gaps

between moving parts whose paths cross during rotation.

Gas entrainment in mixing

Discrete Element Method (DEM)

• Simple conveyor problem

– Non-spherical particles: 3 sphere composite particles

– Conveying belt: Wall velocity boundary condition

DEM – Spreading product for drying and blending

DEM – Spreading product for drying and blending

Outlook – Geometry resolution

• Size of CFD model:

– 1 billion cells => frontier

– 100 million cells => large

– 10 million cells => average

– 1 million cells => small

Outlook – Coupled physics

• Flow + heat/mass transfer + chemical reaction

• Fluid structure interaction

• Flow + thermal + stress

• Flow + electromagnetic