Six block-type thermal power sta- tions are located on the premises of Bioenergie Aerzen and the other four stations operate in the town centre. They work at an overall efficiency of 84 %. For the production of biogas (methane), first of all, cattle manure is heated up to 38 °C, and then mixed with corn silage and dung. The metabolic end product, methane gas, develops from the methane bacteria contained in the manure. The gas is gath- ered in a closed reservoir and then cooled back, dried, desulphurised again and sup- plied to the gas motors of the block-type thermal power stations.
The gas motors deliver the heat arising during compression to the cooling water as well as the waste heat of the hot exhaust gases. Then, the hot water can be fed into the forerun of external heating systems via an external circuit and an additional heat exchanger. It can then be used, based on demand, as base load or as overall supply. The water cooled back in the external heat exchanger goes back into the block-type thermal power station via a “never-ending” cycle.
The methane gas required for the operation of the four block-type thermal power stations in the town centre enters the plants via 2.8 km of piping on the factory premises of Bioenergie Aerzen. An Aerzen positive displacement blower of type Delta Blower (type GM 15 L) increases the gas pressure prior to entry into the pip- ing to 300 mbar, in order to compensate for the pressure loss in the piping and to ensure the necessary minimum pressure of 30 mbar upon entry of the gas in the four block-type thermal power stations. A pressure sensor at power input determines the pressure in the network and delivers it to the frequency converter of the positive displacement blower via computer. The frequency converter controls the speed-con- trolled drive motor of the blower, so that the stipulated inlet pressure of 300 mbar can be constantly maintained.“As a matter of principle, we use only those components that work with highest efficiency, but also with the highest reliability. Thanks to Aerzen positive displacement blowers this concept works entirely without trouble. A failure of this blower would lead immediately to an interruption of the gas and heat supply from the four external block-type thermal power stations in Aerzen’s town centre. Initially, we had planned to use a regeneration compres- sor for the pressure increase. However, the current Aerzen positive displacement blower works in a more energy-efficient way”, explains the Managing Director of Bioenergie Aerzen GmbH & Co.
