| Design Element |
Challenges |
Simulation Benefits |
|
Pulverizers and Classifiers
|
- Control product fineness for low carbon loss, minimal NOx
- Balance competing forces of mill
- Efficiency
- Throughput
- Power consumption
|
- Reduce design time by:
- Understanding flow patterns to improve design
- Predicting performance and erosion behavior for varying designs
- Predicting dynamic behavior, stress, strain for rotating parts
|
|
Burners
|
- NOx reduction
- Unburned carbon (LOI)
- Fatigue and creep from thermal stresses in coal nozzle
|
- Reduce design effort and field tests by
- Predicting temperature, NOx, and LOI with varying fuel, load, swirl
- Predicting thermal loads and stresses for different designs
|
|
Furnaces
|
- Maintaining stable flame under varying load conditions
- Pollutant formation control
- Maintaining proper radiation and convection properties with retrofitted low NOx burners
- Optimizing retrofitted air staging
- Minimizing water wall corrosion
- Designing optimal spray system for Selective Non-Catalytic Reduction (SNCR)
|
- Ensuring retrofit success by predicting
- Flame shape and thermal loads
- Impact of various air staging methods
- Corrosion prone regions
- SNCR local NOx reduction
- Avoiding further downtime in a trial-and-error approach
|
|
Fluidized Beds
|
- Erosion
- Maximizing gas-solid contact
- Avoiding channeling
- Maximizing heat transfer to immersed tubes
- Creep and fatigue due to thermal stresses
|
- Avoid costly problems after manufacture
- Predict erosion in virtual prototypes
- Predict channeling problems
- Predict thermal stresses
- Optimize heat transfer
|
|
Gasification
|
- Ensuring complete reaction
- Varying fuels, loads
- Thermal stresses and heat transfer
- Carbon capture
|
- Gasifier design
- Impact of inlet positions and flow rates on performance
- Impact of fuel changes
- Calculate and design for scale-up effects
|
|
Economizers
|
- Minimizing erosion and fly-ash build-up
- Optimizing heat transfer to incoming water
|
- Determine areas of likely erosion and fly-ash build-up early in design phase
- Make flow distribution modifications that will resolve problems before manufacture
|
|
Flue Ducts
|
- Uneven flow distribution impacting pollution control equipment performance
- Air leakage
- Sagging and deformation
|
- Optimize vanes and turns for flow distribution prior to manufacturing
- Ensure deformations will be within limits by testing/optimizing design specs
|
|
Selective Catalytic Reduction Systems
|
- Poor ammonia/NOx mixing
- Ammonia slip
- Hopper flyash capture efficiency
- Plugged catalysts
- Thermal stresses within catalyst beds
|
- Retrofit to improve poorly performing existing SCR units without resorting to a trial-and-error approach with physical prototypes. Predict:
- Ammonia spray distribution, evaporation, and mixing
- Flow distribution into the catalyst beds
- Local NOx concentrations
- Overall system performance
- Ash and particulate distribution, and hopper performance
- Thermal stresses
- Reduce the design cost and increase the performance of new SCR designs
|
|
Sulfur Dioxide Scrubbers
|
- Poor distribution of spray and/or flue gas
- Designing spray nozzle placement
|
- Improve retrofit and new scrubber performance by using virtual prototyping, predicting:
- Air and spray droplet flow distribution throughout the scrubber
- Local sulfur absoprtion and concentration
- Droplet-wall interaction
|
|
Particulate Control
|
- Short life of systems and components
- High cleaning frequency
- Often caused by:
- Uneven flow distribution
- Uneven loading of baghouses, filters, and electrostatic precipitators
|
- Determine expected loadings prior to field implementation
- Determine stresses on components
- Use results to optimize ducts and turning vanes
- Few shut-downs
- Shorter cleaning frequencies
- Longer bag and plate life
|
