Combusting and Gasification Using Discrete Phase Method

Combustion Through a Chamber

BACKGROUND: Gasification and Coal Combustion

Ash Deposition

Slagging and Slag Disposal

Fouling Downstream

[McDaniel, 2002]

GOVERNING EQUATIONS

Gas Phase Equations

mSVt

xFgPVVt

ik

t

ii

j

j

i

i

jt

ii x

k

xx

u

x

u

x

u

x

ku

kC

xxx

u

x

u

x

u

kC

xu

ji

t

ii

j

j

i

i

jt

ii

2

21

Generation DestructionDiffusionConvection

Turbulent Kinetic Energy

Dissipation

GOVERNING EQUATIONS (Continue)

S

x

Tk

x

hu

t

H

t

h

ii

i

ii

i

ii

i

iii SRx

J

x

mu

t

m

,

i

i

t

tmiii x

m

ScDJ

,,

RN

kkiii RMR

1,

N

j

N

j

njkb

njkfkikiki

kjkj CkCkR1 1

,,,,,,,

Conservation of Energy

Conservation of Species

Mass Diffusion Tensor

Mass Rate

Molecular Rate of Destruction and Creation of Species

Constitutive Equations

x

p

pxpD

p FguuFt

u

44PRPP

PP TATThA

dt

dTmc

Force Momentum Balance

Heat Balance

Tp

T∞

Cd,b

Cd,s

Ck

Tem

perature

Con

cent

ratio

n

Distance

Tp

T∞

Cd,b

Cd,s

Ck

Tp

T∞

Cd,b

Cd,s

Ck

Tem

perature

Con

cent

ratio

n

Distance

productsgspeciesgassspeciessolid )(_)(_

Surface Reactions

FORMULATION OF PROBLEM USING FLUENT

Tw 0.5m

1 m

10 m

.125 m.250 m

Coal Injection: 0.1 kg/s

Air: 15 m/s 1500K

Air: 50 m/s

Symmetry Plane

Tw 0.5m

1 m

10 m

.125 m.250 m

Coal Injection: 0.1 kg/s

Air: 15 m/s 1500K

Air: 50 m/s

Symmetry Plane

Boundary Condition Secondary Air Primary Air Pressure Outlet

Velocity 15 m/s 50m/s ------------------------

Temperature 1500K 1500K 2000K

Turbulence Intensity 10% 5% 5%

Hydraulic Diameter .75 .25 1 m

Oxygen Mass Fraction .23 .23 .23

Schematic of Domain

Boundary Conditions

SOLUTION

Temperature ProfileMass Fraction of H2OMass Fraction of CO2Mass Fraction of CO

SOLUTION (CONTINUED)

Particle Residence Time

PARAMETRIC ANALYSISMole Fraction of Medium Volatile Coal at Selected Operating

Temperatures as a Function of the Duct Length

1500 K Case

PARAMETRIC ANALYSISMole Fraction of Medium Volatile Coal at Selected Operating

Temperatures as a Function of the Duct Length

1000 K Case

PARAMETRIC ANALYSISMole Fraction of Medium Volatile Coal at Selected Operating

Temperatures as a Function of the Duct Length

2000 K Case

VALIDATION: Equilibrium Equations

cbaO

baC

CObCOaCOOCO

222:

1:

5. 222

2/)1(

)1(

ac

ab

xn

xn

xn

CO

O

CO

2

22/)1(

)1(

223 xn

2

22

1

2

2

2

9

10

OCO

CO

CO

O

O

CO

P

PP PP

P

P

P

P

P

TK

TKTK

21

212/11

n

P

xx

xTK P

System of Equations Based On Stoichiometry

Equilibrium Coefficient based on Partial Pressures

VALIDATION CONTINUE

215902.82247.

177573.

82247.

0887865.2/)1(

177573.)822427.1()1(

2

2

2

CO

CO

CO

O

CO

n

n

xn

xn

xn

Values for Fractions

The ratio of CO to CO2 in Fluent was .247Difference between Calculated and Fluent is 14%

Reference

1. McDaniel, J., Tampa Electric Polk Power Station Integrated Combined Cycle Project Final Report. 2002, Tampa Electric Company: Tampa. p. 1-15-1-71.