Predicting Ash Effects
Application of the
CRC Ash Effect Predictor
Extensive research performed by the CCSD and its predecessor has resulted
in the production of the Ash Effect Predictor models. These are predictive models
that use standard and advanced coal characterisation techniques as inputs in
order to assess the relative behaviour of coals in terms of deposition and erosion
potential.
Do you find conventional indices unreliable?
- Advanced analytical techniques investigated by the centre provide useful
practical information.
- Mathematical models developed by the centre aid in interpreting ash effects.
- Characterisation of a suite of reference coals by the centre provides a
database for comparison of coals.
Describing the Effect of Ash During Combustion
An indication of the relative difference between coals and blends in terms
of ash behaviour can be obtained using a mechanistic approach developed at the
centre. This approach combines standard and advanced coal analysis with an ash
formation model.
The output from the Ash Effect Predictor is a comparison of conventional indices
and advanced indices based on:
- Thermo-Mechanical Analysis (TMA),
- Computer Controlled Scanning Electron Microscopy (CCESM).
This type of information provides a fundamental basis for predicting the propensity
for a given coal. The predictor also presents a comparison ash to deposition
of erosion.
Examples for the advanced erosion and deposition indices determined for a range
of coals are shown in Figures 1 and 2 respectively.
Figure 1: Advanced Erosion Indices
Figure 2: Advanced Fouling and Slagging Index
Quantifying the Effect of Ash Behaviour
The Ash Effect Predictor can also be used to quantify the effects of ash in
a combustion system. For this case the Ash Effect Predictor uses:
- Coal analyses (advanced and standard methods)
- Boiler characteristics (such as geometry and gas velocity)
- an ash formation model
- an ash transportation model
- an ash retention model
- a heat transfer model.
This approach provides an assessment of relative:
- ash deposition and deposit growth rates
- erosion/wear rates (Figure 3)
- thermal performance.
Figure 3: Prediction of relative erosion/wear rates
For more information contact:
Prof Terry Wall
Program Leader
University of Newcastle
Please Note: This site was archived in August 2008 and therefore the information contained in these pages may no longer be current.
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