Entrained-flow Gasifier Model Development

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Entrained-flow Gasifier Model Development

• Larry Baxter, Bing Liu, Humberto Garcia

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Distinguishing Characteristcs

• Focus on refractory durability
• Chemical dissolution
• Fracturing
• Spalling
• Advanced inorganic coal chemistry
• Initial inorganic speciation
• Particle and gas dynamics
• Deposit/slag formation
• Numerically efficient
• New, rapid gas-phase convergence
• 1-D reactor profile
• 2-D slag/refractory/deposit profile

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Capabilities and Status

• Estimates transient gas and particle composition,
  temperature, velocity, and position as a function
  of axial position.
• Estimates transient slag and refractory
  thickness, composition, temperature, and phase as
  functions of both axial and radial position.
• Suitable for monitoring and supervisory control,
  either in full or in correlated form.
• Steady-state version in debug mode.
• Validated and verified model complete by end of
  CY 2007.

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Overall Concept
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Reactor Model
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Reactor Model Details
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Wall Model Details
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Mechanical Model Details
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Mechanical Model Interface
Deposit-refractory interface composition,temperatu
re,and properties
Deposit Phase
Gas and Particle Phases
Refractory / Metal Phase
Axial temperature profiles, mass flux, particle
composition
Gas and particle composition, velocity, and
temperature (axial)
Depth, phase, composition, temperature, and
flow rate (radial and axial)
Thermal mechanical stresses, fracturing/spalling
, psd of spalled particles, erosion, corrosion
Chemical dissolution
Gas-deposit interface conditions (T, e, phase, µ)
Slag absorption, spall psd, T, ?x
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Database-driven Information
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Sequence Diagrams
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Deposits Dissimilar to Fuel
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Example

• Gasifier dimensions (lengthdiameterthickness)
• Steel shell 3.01.060.03 (Unit m)
• Refractory 3.01.00.3 (Unit m)
• Coal Illinois 6
• Operating Temperature 1800 C
• Operating Pressure 40 atm

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Gas Composition Profile
dry coal, high equiv. ratio, O2 feed
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Corrosion Rate Dependencies
Corrosion flux is calculated using the falling
film diffusion model. The corrosion rate
increasing with temperature results from two
effects (1) Solute diffusion coefficient
increases exponentially with increasing
temperature (2) the saturated solute
concentration increases with increasing
temperature.
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Refractory Thickness Dynamics
?t 8
?t 100 hr
?t 50 hr
The computation is conducted at the 0.3 m from
the top of the gasifier. 1800 C syngas
temperature is used. 1/?t is the assumed
spalling frequency. The curves become flat at
long time resulting from the decreasing hot-face
temperature of the refractory with time.