Benninghoven hot-gas generator defines the state of the art for recycling technology
High recycling rates with low emissions can only be achieved with the counterflow action in the hot-gas generator. The reason: Because the used asphalt is heated, the virgin mineral does not have to be overheated when it is added to the mixing process to achieve the required temperature level, which is between 140 °C and 180 °C for warm asphalt. This means that the process reduces emissions while also saving a lot of energy.
Emissions reduced below the required TA-Luft levels
This process is made possible by the use of the Benninghoven hot-gas generator: While direct firing would tend to “burn” the recycling material coated with bitumen, the hot-gas generator simply heats it indirectly to gently raise it to the optimum application temperature. At the same time, the process lowers the emissions below the level required by the TA-Luft directive – for example with thermal treatment of a large part of the hydrocarbons contained in the exhaust gas flow. Continuous emissions measurements on the stack of the Knäble plant are used to monitor compliance with the legal limits in real time. “Compared to our previous plant, our average recycling rate has increased from 25 % to 60 %,” Myriam Knäble, wife of the Managing Director, reports proudly. “And with the new technology, we save around 770 t of CO2 per year compared to the previous plant.”
Cost savings thanks to less CO2
This is an enormous advantage, considering the CO2 prices in Germany – the market where Knäble is active. Due to recent changes, energy suppliers of fuels (except bio fuels) now have to purchase emissions allowances, also known as CO2 certificates. The costs incurred by this are increasing every year and are passed on to the customers. Companies who focus on energy efficiency and operate environmentally friendly and with low emissions will therefore have an even greater advantage in the future.