ACARP ACARP ACARP ACARP
Technical Market Support

Slagging and Fouling in HELE plants: Assessment of Fusibility and Particle Size in Deposition

Technical Market Support » Thermal Coal

Published: May 21Project Number: C27022

Get ReportAuthor: Liza Elliott, Andrew Stanger & Terry Wall | University of Newcastle

Key markets for Australian black coal have been moving to supercritical and ultra-supercritical plants, often referred to as HELE boilers, which operate at higher steam temperatures. Increased steam temperature means increased fire-side temperatures. Additionally, most countries are encouraging the inclusion of biomass combustion in their energy mix to decrease carbon emissions and attain a more sustainable energy source. Biomass generally contains alkalis and other fluxing components which often lower the temperatures where ash sinters and begins to melt. Both increasing boiler temperatures and increasing fluxing components in the ash are expected to increase deposition in both the radiant and convective sections of the boilers.

Deposition mechanisms are associated with certain particle sizes, meaning only a portion of the ash is involved in deposition. Laboratory ash represents all the ash produced in the combustion of the coal, and is morphologically very different to the ash produced in boilers. Drop tube furnace (DTF) ash, on the other hand, is morphologically very similar, being produced at similar heating rates and forming in a flowing gas stream, as in industrial boilers.

This project explores the suitability of drop tube derived fly ash for assessing ash fusibility characteristics and deposit potential.

Industrial deposits and feed coals were collected from two power stations, while a third power station provided coal, fly ash and economiser ash. The deposits were characterised by Scanning Electron Microscopy (SEM), thermomechanical analysis (TMA) and other standard techniques. TMA has previously been used to study ash deformation and involves the measurement of linear penetration into a softening ash sample during heating. The fusibility curves produced by the deposits on the TMA were compared to curves produced by laboratory ash made from the feed coals and ash produced from combustion of the coals in a drop tube furnace. The impact of particle size of the drop tube furnace ash was also investigated.

Comparison of commercial ash fusion temperatures and TMA traces show that Ash Fusion Temperatures (AFT) overestimate deformation significantly and do not provide any valuable insight into the behaviour of coal ash during deposition.

The expected changes in deposition behaviour associated with changes in steam temperatures in HELE boilers compared to sub-critical boilers is discussed. Deposition would be expected to increase due to the higher tube wall temperatures, the higher furnace temperatures, the higher fuel loading and the higher gas velocity. Addition of biomass material would increase this further.

Underground

Health and safety, productivity and environment initiatives.

Recently Completed Projects

C27039True Triaxial Strength Of Coal Measure Rocks And Its Impact On Roadway Stability And Coal Burst Assessment

Rocks in the ground are subject to a range of stresses. The stresses...

C3063Underground Vehicle Design Standards And Statutory Implications

The Australian underground diesel vehicle fleet has evolved since di...

C3064Conveyor Belting And Lagging Shear Characteristics - Drive Drum Slip

The primary aim of this project was to investigate the relationsh...

Underground

Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C29021Assessing The Impact Of Consecutive Night Shifts On Night-Time Alertness, Daytime Sleep And Timing Of The Circadian System

In the Australian coal mining industry, most guidelines for managing...

C33037Quantifying Recharge To Groundwater Systems In The NSW Coalfields (Sydney, Gunnedah And Gloucester Basins)

The purpose of this project was to estimate the rate of diffuse rec...

C26029Geological Controls On Fluorine And Phosphorus In Bowen Basin Coals

Increasing global restrictions on fluorine in product coal prompted ...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27064Dry Beneficiation Using FGX And X-Ray Sorters

Conventional dry processing methods engage a single beneficiation de...

C26010Multi-Sloped Screening Efficiency With Changing Strokes, Frequencies, Feed Solids And Feed Rates-Pilot Plant Study

Optimising multi-sloped screens is often described as an art and the...

C28059Impact Of Water Quality In Coal Handling And Preparations Plants

The objective of this project was to deliver a concise reference do...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C23052Novel Stone Dust Looping Process For Ventilation Air Methane Abatement

This multi‐phase project is concerned with the mitigation of m...

C27054Optimisation Of A Thermal Flow Reversal Reactor For Ventilation Air Methane Mitigation

Ventilation air methane (VAM) generally accounts for 50-85% of the t...

C28076Selective Absorption Of Methane By Ionic Liquids (SAMIL) - Phase 2 Demonstration In A Packed Bed Reactor

An alternative approach to high temperature oxidation of ventilation...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community

NERDDC

National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook

NERDDC