Coal Ash Fusibility Furnace

The introduction of the Carbolite Coal Ash Fusibility test furnace has revolutionised coal sample testing where time and accuacy are both critical.

Where previously an operator's time was dedicated to the continuous monitoring of a test with only 1 or 2 samples, the CAF furnace allows up to 12 samples to be tested at any one time. Continuous image recording allows laboratory technicians to carry out other tasks while the test is in progress.

The latest addition to this product is the capture of test images via a computer. This new option gives both accurate and rapid analysis of tests.

The computer is used to automatically generate a test report for the furance once the relevant fusion temperatures have been identified by quickly scrolling through the stored images.

Coal Ash Fusibility Testing

At high temperatures, the heat from burning coal is often sufficient to melt its own ash which when cooled solidifies into clinker.

In industrial coal burning applications, clinkers can be extremely large and can cause both disposal problems and operation downtime. Coal ash fusibility testing is therefore required by users to determine the ash fusibility characteristics of the fuel.

The published standards require that the ash fusion temperature furnace is measured and recorded at 4 points: the initial rounding of the cone tip, when the cone has softened, when melted to a hemisphere and finally when it flows into a puddle.

The Furnace

The Coal Ash Fusibility furnace is designed to heat coal ash samples up to a maximum of 1600°C in a controlled atmosphere and visually record the fusion of the samples for analysis.

The furnace work tube is sealed and has a 'fail safe' gas control system for safety when testing with toxic and flammable gases. A sliding and rotating door mechanism provides unrestricted access to the work tube, allowing easy loading and unloading of the test samples using the sample loading tool provided.

The large diameter work tube can accept up to 12 samples at any one time. The use of lightweight insulation allows the furnace to cool quickly, permitting multiple tests to be completed during the day.

The start and finish temperatures can be pre-set and the rate of temperature rise is adjustable within the parameters of the relevant published standards. Independent overtemperature protection is provided by a separate temperature controller using its own thermocouple and contactor to override the heating circuit.

Gas Controls

A 'fail-safe' gas system is incorporated into the furnace. Oxidising or reducing gases are automatically introduced into the work tube during a coal ash fusibility test. The flow rate and required atmosphere are controlled from the furnace control panel.

To ensure operator safety, the following features are included:

 safety purge of the work tube prior to and after carrying out a coal ash fusibility test

 'Purge Gas Failure' audible and visual alarm

 safety purge of the work tube in the event of of a power failure during a test

 test in progress indicator to warn the operator that oxidising or reducing gases are present within the work tube

 'gas tight' work tube for furnaces