05 Moser

Transcription

05 Moser

DBFZ Leipzig Fachtagung Prozesssimulation in der Energietechnik Sep. 2014
Siemens
Gasification Technology
Moser / Pieloth
Unrestricted / © Siemens AG 2014
Contents
Siemens
Flugstromvergaser
Simulation der Abtrennung von
Restflugasche im Rohgas am Beispiel
einer Tauchquenchung
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Siemens Fuel Gasification Technology
overview
3
Quench principles
7
Theoretical background
and validation
8
Numerical models
20
Results
23
Summery & Outlook
25
DE / E P / GT / FG
Siemens Fuel Gasification Technology overview
Siemens offers gasifier types for every feedstock
Feedstock's with more
than 4 wt% ash content
Feedstock's with less
than 4 wt% ash content
Lignite's, Sub-bituminous and
Bituminous coals, Hard coals,…
Petroleum coke, Bitumen, Tars,
Oils, Asphaltenes, Biomass,…
Cooling Screen Design
Refractory Wall Design
Fuel
Oxygen, steam
Pressurized
water inlet
Burner insert
Pressurized water
outlet
Burner
Cooling wall
Refractory
lining
Cooling
screen
Reactor
1300 to
1800°C
SiC layer
Cooling water
Cooled
reactor outlet
Quench water
Quench
water
Total quench
Gas outlet
Quench
Gas outlet
Granulated slag
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Cooling Screen Type Gasifier
SFG Gasifier (> 4 wt % ash)
Feedstock
Pressurized
water inlet
O2
H2O
Features
Fuel flexibility
Pressurized
water outlet
• Lignite, bituminous and sub-bituminous coal,
hard coal,…
Dry feeding
Burner
Cooling
screen
• high efficiency (>80%)
• high carbon conversion rate (>98%)
Cooling screen
Reactor
1300 –
1800°C
• short start-up/shut-down (~2h)
• Significantly higher lifetime/high availability
Full quench
Qunech
water inlet
Qunech
water inlet
Quench
Syn-Gas outlet
• simple and reliable
• ideal for CO sour shift
Single main burner with integrated
pilot burner
• Automatic start up without removal of start burner
• Modular concept for simplified maintenance
• Pilot burner secures hot stand by under full
pressure
Granulated slag
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Features SFG-500
• Length: 18 meters
• Outside diameter (incl. flanges): 4.3 meters
• Weight: 220 tons
• Capacity: ~ 2,000 tons of coal daily
• Syngas output: ~ 3.0 mio Nm3/day
SFG-500 Gasifier
for NCPP Project/China
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Burner
Reaction Chamber
Cooling Screen
Quench Nozzles
Quencher
Syngas Outlet
Slag discharge
Operating Pressure:
up to 42 bar
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Quench principles
Full quench
Partial quench
Scrubber quench
Tin ~ 2000 K
Tout ~ 500K
proven & reliable desgin
SFGT technology
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Technical study
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Technical study
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Theory
•
Fakultät Bio- und Chemieingenieurwesen
Lehrstuhl Mechanische Verfahrenstechnik
technische
universität dortmund
Löffler model of particle deposition on droplets
Deposition of dust particles on a droplet due to inertia
Cleaning of a raw gas stream can be resolved into three sub processes:
a) Particle deposition on a single droplet
b) Cleaning of a volume of a single droplet
c) Change of dust concentration through the summation
of cleaning volumes of all droplets
The deposition efficiency of particles on a droplet is defined as the
product of collision efficiency and adhesion efficiency h:
h
Wet scrubbers:
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Theory
technische
Particle deposition on a single droplet:
Map between
and
The Stokes parameter
b
(Stokes parameter):
a
2
v
x
p rel p
is defined as:
a = f(Red), b = f(Red)
Droplet - Reynolds’ number:
18 l x d
v rel x d
Re d
l
l
3
2x d
RV
Specific cleaned volume:
t2
Change of dust concentration:
i
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t1
4
x d,2 i
t2
(t)vrel (t)dt
t1
d,i
(t)vrel,i (t)dt
DE / E P / GT / FG
Theory
technische
Euler-Lagrange Simulation (Two phases, each phase two* components)
Air: Euler Phase (air, dust), Droplets: Lagrange Phase (water, dust)
Process parameter (e.g. l,vrel)
v rel x d
Re d
2
v
x
p rel p
l
18 l x d
l
b
a
t2
i
t1
4
x d,2 i
*more then two, if dust polydispers
d, i
(t)v rel,i (t)dt
Re 100
100 > Re 50
50 > Re 30
30 > Re 5
5 > Re
potential flow
Re = 60; 80
Re = 40
Re = 10; 20
viscous flow
Schuch’s Parameter a and b
Change of dust concentration
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Theory
technische
•
Schuch‘s PhD thesis:
- Flow channel (0.1 m x 0.1 m cross section, air velocity v = 5, 7, 15 m/s)
- Monodisperse droplets (velocity entering flow channel w0 = 4, 7, 15 m/s)
- Monodisperse dust (xp = 1.6, 2.5, 4.0, 14.8 m)
- Measurement of dust collected by droplets
Droplet
collector
Channel
Droplet
generator
Schuch (1978)
Schuch‘s experimental setup
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Dust
v
Droplets
w0
Modellrechnungen mit ANSYS CFX
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Theory
technische
Löffler/Schuch
Specific cleaned volume RV
v = 7m/s, w0 = 7 m/s
Droplet diameter xd [µm]
Theo. calculations and exp. data
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verified
with
Matlab
ANSYS CFX numerical modeling
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Theory
Euler-Lagrange-Simulation
technische
Re d
v rel
- Droplet (rigid sphere ), Dust (Lagrange-Particles)
- Droplet - Dust - Collision
i
- Mesh ~ 2,7·106 Elements,
Re d
18
high resolution in the vicinity of droplet’s surface
- 0,1
Red
p
x p, i
g
xd
N d, i
i
100 (Step size 1), for all 0 < xp / xd < 0,15
high accuracy in adaption of
xd
g
Deposition efficiency
g
N in, i
,a,b)- und a,b(Red)-Functions
Particle
Mesh
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Droplet
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2
Theory
Re = 5
Re = 40
technische
Re = 100
Schuch
Schuch
Schuch
Comparison of - dependencies for Red = 5, 40 und 100,
with CFD calculated (
) - Values,
approximated = (Red ) CFD Values, -·- Schuch [1], -- Schmidt [2]
[1] G. Schuch, PhD thesis, Universität Karlsruhe, Karlsruhe 1978
[2] M. Schmidt, PhD thesis, Universität Karlsruhe, Karlsruhe 1993
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Theory
technische
Parameterization of
a(Red) and 1/b(Red) curves
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1
2
3
4
5,907·10-6
1,027·10-5
8,488·10-4
8,731·10-6
4,16·10-5
7,172·10-4
5
6
7
8
0,03071
0,00724
-0,2056
-0,07425
0,04945
0,007899
-0,29
-0,06784
DE / E P / GT / FG
Theory / Validation
Raw gas (NaCl particles)
Injector
Water mSalt
Salt feeder
0
Thermostat
~5m
Rotary
sprayer
Rotary sprayer
mSalt
Chamfer
Conductivity
Measurement
Chamfer
Rotary scrubber (pilot plant scale)
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technische
2014-09-10
0
Conductivity
Measurement
Clean gas
Rotary scrubber (schematic representation)
Moser / Pieloth
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Q3(x)
Q3(x)
Theory / Validation
Jet mill
technische
Cyclone screened
Salt (NaCl) powdered in a jet mill, then screened with a cyclone.
Characteristic droplet
size generated by the rotary
sprayer (LAMROT-Sprayer)
used in experimental setup.
With higher RPM the PSD
shows a smaller span value.
Rotary sprayer
RPM [1/min]
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Theory / Validation
technische
Dust concentration:
c0
Air velocity
v = 4.98 m/s
Scrubbing
Droplet
Trajectories at
RPM = 7000
Dust concentration
c1
RV
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Theory / Validation
technische
Air velocity 4.98 m/s
RPM [1/min]
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Numerical models
Full quench
Scrubber quench
•
Complicate geometry
•
Simple geometry
•
180° model
•
45° model
•
~4 mio cells
•
~0.74 mio cells
•
High number of dpm
trecking steps requiered
•
Less dpm
trecking steps requiered
•
~16000 particles per
dpm iteration
•
~9000 particles per
dpm iteration
•
Requieres much
CPU-time
•
Less CPU-time
SFGT technology
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technische
2014-09-10
Scrubber quench choosen for numerical
study on dust absorption models
Moser / Pieloth
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Numerical models
technische
Scrubber quench study on dust absorption
for non-isothermal flow conditions
CFD code: Ansys® Fluent
3-D simulation
Steady state simulation
Turbulence model: k -sst
Discrete particle model ( DPM, Lagrange particle tracking )
4 dust particle fractions
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Numerical models
technische
for non-isothermal flow conditions
Inlet: hot raw gas and dust
Water nozzles
Water nozzles
Outlet: cooled raw gas +
water droplets
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Results
Fluid Phase
Species
inlet
outlet
diff
diff
kg/s
mass flow ->
In-out
dpm to
massfrac
massfrac
%
in-out
h2o
0,03649963
0,49938399 -2556,13% 1,06%
n2
0,01295987
0,00679880
-1,84%
h2
0,01928981
0,01011951
-1,84%
co2
0,07072929
0,03710488
-1,84%
co
0,84971148
0,44576219
-1,84%
dg1
0,00224998
0,00001987
98,29%
dg2
0,00531995
0,00010669
96,11%
dg3
0,00205998
0,00026820
74,72%
dg4
0,00117999
0,00037240
38,73%
technische
DPM Phase
absorb
Because of evaporated H2O
%
Eulerian - Langranian
mass balance for H2O
fulfilled
dd1
dd2
dd3
dd4
98,96%
97,51%
77,87%
38,31%
Increased absorptionrate
from dd4 to dd1
•
Mass balances fulfilled
•
For dust good agreement of Eulerian phase mass balance and
Langrangian phase mass balance
•
Inlet-outlet:
•
Good fulflillment of species (n2, h2, co2, co) mass balances
•
Deviation in water mass balance due to evaporation of water
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Results
technische
Analysis of dust load on particles
Dust load on water droplets usually does not exeeds the range of 10%.
Analysis of dust load on water droplets shows that almost no droplet carries
a dust load above 10%
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Numerical outcomes correspondence to
experimental findings
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Summary
technische
Study of particle absorption on scrubber quench for non isothermal flows
• Dust absorption models successful integrated in Ansys Fluent code
• Outcomes are in the range of expectations
• Smaller particles are less absorbed than larger particle
• Unrealistic high loading with dust on water droplets is negligible
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Outlook
technische
SFGT technology
Full quench
• Implementation of dust absorption models in SFGT
full quench model
• Implementation of load delimiter on water droplets
• Implementation of models for „dry particles“
(total evaporation of water)
Options:
1. Transfer for small dust particles back to
Eulerian phase
2. Creation of solid dust particle network on the
base of spray drying experience
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Disclaimer
This document contains forward-looking statements and information – that is, statements related to future, not past,
events. These statements may be identified either orally or in writing by words as “expects”, “anticipates”, “intends”,
“plans”, “believes”, “seeks”, “estimates”, “will” or words of similar meaning. Such statements are based on our current
expectations and certain assumptions, and are, therefore, subject to certain risks and uncertainties. A variety of
factors, many of which are beyond Siemens’ control, affect its operations, performance, business strategy and results
and could cause the actual results, performance or achievements of Siemens worldwide to be materially different from
any future results, performance or achievements that may be expressed or implied by such forward-looking
statements. For us, particular uncertainties arise, among others, from changes in general economic and business
conditions, changes in currency exchange rates and interest rates, introduction of competing products or technologies
by other companies, lack of acceptance of new products or services by customers targeted by Siemens worldwide,
changes in business strategy and various other factors. More detailed information about certain of these factors is
contained in Siemens’ filings with the SEC, which are available on the Siemens website, www.siemens.com and on the
SEC’s website, www.sec.gov. Should one or more of these risks or uncertainties materialize, or should underlying
assumptions prove incorrect, actual results may vary materially from those described in the relevant forward-looking
statement as anticipated, believed, estimated, expected, intended, planned or projected. Siemens does not intend or
assume any obligation to update or revise these forward-looking statements in light of developments which differ from
those anticipated.
Trademarks mentioned in this document are the property of Siemens AG, it's affiliates or their respective owners.
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05 Moser

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