Automatic sampling system for substitute fuels

Cement manufacturers should regularly test substitute fuels in the laboratory to check their quality and calorific value. This is also relevant with regard to product quality of the fired cement clinker, which depends amongst other things on the burned materials.

1 Automated sampling system prepares material for laboratory analysis

In many companies, sampling is performed manually and very irregularly at different times. “Material sampled in this way is not representative and it is very inhomogeneous. This makes it very difficult to draw conclusions about the quality of the entire substitute fuel,” explains Jürgen Graf, Sales Manager at Erdwich Zerkleinerungssysteme GmbH. Therefore, it should be in a company’s own interest to replace the manual sampling with an automated system.

On the basis of the tried and tested single-shaft shredders, the shredding expert company Erdwich has designed a system that automatically takes several individual samples with a total volume of 200 to 250 litres from the substitute fuel. These are comminuted from about 150 mm to a suitable grain size of about 5 to 8 mm and are, thus, suitable for further processing by laboratory shredders. “In order for the sample material to be as representative as possible, it is subsequently mixed again and, depending on the requirements, a sample of about 0.5 to 1 l is taken as the final dispatch for delivery to the laboratory,” says Graf, explaining the process. The rest of the material is automatically returned to the fuel stream.

2 Sampling system can be adapted to operational

requirements

Erdwich offers two different solutions. On the one hand, the comminutor can be used as a stand-alone machine. Depending on the sample size, the compact models M400 for up to 30 l as well as the M600 for up to 240 l are designed for use here. The feed to the plant as well as the division after crushing are carried out manually. On the other hand, comminution with downstream division is possible. Here, the original sample with about 200 l is removed manually from the fuel stream, transported to the plant and crushed there. Subsequently, sample division is performed.

If required, the system can also be equipped with a magnetic separator to protect the subsequent laboratory mills. SF consists mainly of plastics, but contaminants such as wood, metals, mineral fractions or glass can also be present in the commercial waste. These circumstances as well as the possibly occurring high residual moisture of the material subject the knives of the shredders to considerable stress. This is why they are designed for particularly high wear resistance and are equipped with special geometry.

3 Special solutions for special operating conditions

are possible

On request, special solutions are offered, which can be adapted, for example, to particularly narrow space conditions in the enterprise. “The sampling system makes it possible to avoid human error sources and to prevent manipulation by means of the extensive process automation,” says Graf, explaining the advantages. “In addition, the samples are reproducible owing to the consistently high extraction rate and are traceable at any time as documentation is created with each extraction. As a result, the substitute fuel suppliers can also continuously check how the analysis results have been achieved,” the sales manager continued.

In addition, Erdwich is developing a special version which can be opened up and which is to be subjected to a practical test in the in-house pilot plant. Cleaning and changes of screens should be considerably simplified.

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