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Submitted:
18 January 2024
Posted:
19 January 2024
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Items | Value | |||||||
---|---|---|---|---|---|---|---|---|
ER, % | 0.25 | 0.30 | 0.35 | 0.40 | 0.45 | 0.50 | 0.55 | 0.60 |
LHV, MJ/m3 | 7.65 | 6.86 | 6.09 | 5.74 | 5.57 | 5.39 | 5.18 | 4.38 |
, % | 64~100 | 58~90 | 51~80 | 48~75 | 47~73 | 45~71 | 43~68 | 37~57 |
density of the fluid mixture mass fraction of species K in the fluid mixtures = fluctuation dilation in compressible turbulence volume force acting on species k in the j direction coordinates axes = dynamic viscosity of the mixture the i-component of the diffusion velocity of species K energy flux in the mixture total energy from chemical, potential and kinetic energies = energy flux from the outer heating source = source term for the ith (x, y, z) momentum equation = specific heat at constant pressure = net rate of production of species, i = net rate of production of species “i” by chemical reaction = specific heat = turbulence kinetic energy due to buoyancy C = linear-anisotropic phase function coefficient = latent heat of evaporation = Stefan constant, respectively. (- ) = drag force per unit particle mass. |
t = time pressure velocity components the viscus stress tensor = the tensor unit. the reaction rate of species k = user-defined source terms for k = user-defined source term for ϵ = turbulent Prandtl numbers for k = turbulent Prandtl numbers for h = sensible enthalpy H = latent heat enthalpy = reference enthalpy = reference temperature species i's average mass = volatile fraction = initial mass = absorption coefficient, = Stefan-Boltzmann constant, G = incident radiation, and A = particle surface area |
Pellet features | Value | |
---|---|---|
Proximate analysis (wt % as received, db) |
Moisture | 3.50 |
Volatile matters | 44.51 | |
Fixed carbon | 36.99 | |
Ash | 15.00 | |
Calorific value, HHV (MJ/kg) | 19.06 | |
Ultimate analysis (wt % as received, db) |
Carbon | 45.97 |
Hydrogen | 5.22 | |
Nitrogen | 0.72 | |
Sulphur | 0.21 | |
Oxygen (by difference) | 47.88 | |
Density | Apparent density (kg/m3) | 817.71 |
Bulk density (kg/m3) | 427.45 | |
Thermokinetic properties* | In combustion | |
Activation of energy, (kJ/mol) | 418.935 | |
Pre-exponential factor, (1/sec) | 1.76E+16 | |
In pyrolysis | ||
Activation of energy, (kJ/mol) | 132.868 | |
Pre-exponential factor, (1/sec) | 2.4E+4 |
Components | Computational model |
---|---|
Biomass |
|
Air |
|
Gasification |
|
Parameter | References | |
---|---|---|
Gasification agent (air) | Air flow rate: 54 kg/hr (37.87 Nm3/hr) | - |
Air velocity: 3.2 ~7.2 m/s (average 5.2) | [1] | |
Air fuel ratio: 6:1 v/m | [38] | |
Air inlet temperature: 300K | [1] | |
Pressure | Gasification pressure: 1 atm = 101325 pascal | [6] |
Outlet gauge pressure: 0 | [30] | |
Pressure outlet: 249 pascals (min) and 747 pascals (max) | - | |
Biomass | Input: Biomass (WSP) inject (Gravity feed) | - |
Gravitational acceleration: - 9.8 m/sec2 | - | |
Biomass inlet temperature: 300°K | [2] | |
Biomass flow rate: 9 kg/hr | [1] | |
Biomass moisture content: 3.5% | - | |
Temperature | Temperature-Atmospheric condition: 300K | [30] |
Operating temperature: 300 ~ 2500K | - | |
Reactor wall | Motion: stationary | [30] |
Wall shear condition: No slip | ||
Wall roughness: standard | ||
Inlet species mass fraction of O2: 0.23 | [30] | |
Inlet velocity magnitude: 0.056 m/sec | - | |
Wall (interior and exterior walls): Stainless steel | - | |
Wall thickness: 3 mm | - | |
Others | Equivalence ratio: 0.2 ~ 0.6 | [24] |
Turbulence intensity: 5% | [30] | |
Particle-specific heat: 2.5 kJ/kgK | [30] | |
Particle size in the discrete phase: 0.1 mm | [2] | |
Uniform porosity: 0.5 | [54] | |
For simulation time setup: 10 sec | [30] | |
Model run: 0 to 7200 sec |
|
Conditions/Assumptions |
|
|
|
P1: Radiation reflection at the surface is isotropic |
|
-intermittency: Include the effect of share stress transport, kinetic and its dissipation rate and the change in velocity |
|
Nonpremix combustion-non-adiabatic |
|
Euler-Lagrange (discrete phase)Particle devolatilisation model: Single kinetic rate Particle combustion: Kinetic/diffusion-limited rate |
Variable | Discretisation Scheme | Information |
---|---|---|
Pressure staggering option | PRESTO! | Pressure-based Navier-Stokes solution algorithm (the default) |
Pressure velocity coupling | SIMPLE | Governing equation |
Gradient option | Least Squares Cell-based | - |
Pressure | Second Order Upwind | Spatial discretisation |
Momentum | Second Order Upwind | Spatial discretisation |
Turbulent Kinetic Energy | Second Order Upwind | Spatial discretisation |
Turbulent Dissipation Rate | Second Order Upwind | Spatial discretisation |
Energy | Second Order Upwind | Spatial discretisation |
Mean mixture fraction | First Order Upwind | Spatial discretisation |
Mixture fraction variance | Second Order Upwind | Spatial discretisation |
Soot | Second Order Upwind | Spatial discretisation |
Others | First order Upwind | - |
Discrete ordinates | Second Order Upwind | Spatial discretisation |
Formulation | Implicit | - |
Velocity formulation | Absolute | default setting |
Porous formulation | Superficial velocity | - |
Initialisation | Hybrid | - |
Gas phase reaction | Solid particle surface reactions | ||
---|---|---|---|
Reaction | Reaction order | Reaction | Reaction order |
Volatile decomposition | Char decomposition | ||
CO Combustion: | |||
H2 Combustion: O | |||
Water-gas shift: | |||
Particulers | Value | |
---|---|---|
Mesh element size (average) | : | 1 mm |
No of nodes | : | 172677 |
No of elements | : | 171558 with a rectangular shape |
Minimum orthogonal quality | : | 0.38916 |
Maximum aspect ratio | : | 5.27929. |
Particulars | Results | ||
---|---|---|---|
Model | Experiments | ||
Temperature (k) | Combustion (Upper concentric at x = 0.25 to 0.3 m) |
900~1413 | 1250 |
Reduction (Bottom reduction at x = 0.425 m) |
1100 | 1080 | |
Gas species (% v/v) |
CO2 | 9.99 | 9.4 |
CO | 21.60 | 23.3 | |
CH4 | 0.13 | 0.051 | |
H2 | 16.81 | N/A |
Zone | Temperature range, k |
---|---|
Drying and pyrolysis | 300~856 |
Combustion | 856~1356 (Max temp. 2160) |
Reduction | 1356~974 |
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