High-temperature drying with energy recovery

11.11.2021

The Abwasserzweckverband Kempten (Allgäu) operates the following at its wastewater treatment plant with a belt drying plant for dewatered sewage sludge. The drying plant is supplied with hot water from the cooling circuit of the existing combined heat and power plant. In order to dewater the entire sludge volume, the heating system of the wastewater of the sewage treatment plant was modernised. In November 2020, Sülzle Kopf GmbH was awarded the contract for the “sewage sludge/thermal oil drying” lot with the following main components: Supplementation of the existing thermal oil circuit with secondary control circuit, thermal oil boiler and exhaust gas system with air preheating, three high-temperature screw contact dryers, vapour extraction, steel construction, conveying equipment and the associated piping. The progress on the construction site is visible, as almost all of the large components are almost in place.

The pictures show the difficult insertion and installation of the dryers 1 + 2 on the steel structure. Weight of each dryer approx. 25 tons and length approx. 14 m. The three double-shaft screw contact dryers each have a drying capacity of 2000 kg/h of dewatered sludge. Dry matter content before drying: 25 – 35 % / after drying over 90 %. The next step is the connection piping and the installation of the conveying units and the pumping stations – completion is planned for summer 2022.