<abstract xmlns="http://www.w3.org/1999/xhtml">

This study evaluates the common process and set-up design of a static compost bioreactor for heat recovery. A technology, which fits the goal of a sustainable, growing bioeconomy which combines the utilization of compost heat and compost material. Interest on this technology has been growing the last years but precise data of pilot scale reactors is rare. Data is required to adjust the process for custom needs and further technical development. Therefore, lignin-cellulose based biomass was composted in unaerated cylindrical compost reactors size 20 to 70 m3 for 140 days. The biomass comes with C:N ratio of about 25:1, water content of 43-48 %, organic matter content of 40.6 % d.m. and calorific value of 8.3 MJ/kg d.m. Spatial distribution of temperature and gas concentration (oxygen, carbon dioxide, methane) within the reactor shows methane production of the anaerobic core area. Maximum thermal power of 5.2 kW from a 63 m3 reactor with average temperature of heating flow about 40 °C was reached. Maximum recovered heating power of 4.8 MJ/kg d.m. was calculated for an operation of 6 month. This corresponds to 50 % of the measured calorific value. Biggest influence factors detected on the recovered heating power of the pilot scale reactor has been the size of reactor, the set up quality and the control of heat exchanger. The spatial correlation between heat production and aerobic digestion suggests a technical development in terms of aeration.
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This study evaluates the common process and set-up design of a static compost bioreactor for heat recovery. A technology, which fits the goal of a sustainable, growing bioeconomy which combines the utilization of compost heat and compost material. Interest on this technology has been growing the last years but precise data of pilot scale reactors is rare. Data is required to adjust the process for custom needs and further technical development. Therefore, lignin-cellulose based biomass was composted in unaerated cylindrical compost reactors size 20 to 70 m3 for 140 days. The biomass comes with C:N ratio of about 25:1, water content of 43-48 %, organic matter content of 40.6 % d.m. and calorific value of 8.3 MJ/kg d.m. Spatial distribution of temperature and gas concentration (oxygen, carbon dioxide, methane) within the reactor shows methane production of the anaerobic core area. Maximum thermal power of 5.2 kW from a 63 m3 reactor with average temperature of heating flow about 40 °C was reached. Maximum recovered heating power of 4.8 MJ/kg d.m. was calculated for an operation of 6 month. This corresponds to 50 % of the measured calorific value. Biggest influence factors detected on the recovered heating power of the pilot scale reactor has been the size of reactor, the set up quality and the control of heat exchanger. The spatial correlation between heat production and aerobic digestion suggests a technical development in terms of aeration.

Heat Recovery of Compost Reactors: Field Study of Operational Behaviour, Heating Power and Influence Factors

Deutsches Biomasseforschungszentrum, Bioenergy Systems Department, Working Group Biomass in the Energy System

Ecological Chemistry and Engineering S

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

This study evaluates the common process and set-up design of a static compost bioreactor for heat recovery. A technology, which fits the goal of a sustainable,...

Heat Recovery of Compost Reactors: Field Study of Operational Behaviour, Heating Power and Influence Factors

Published Online: Jul 23, 2021

Page range: 201 - 217

DOI: https://doi.org/10.2478/eces-2021-0015

Keywords
biomass energy, composting, passive aeration, heat exchanger, gas concentration

© 2021 Nele Jaschke et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Supplementary Material Details

Heat Recovery of Compost Reactors: Field Study of Operational Behaviour, Heating Power and Influence Factors

Published Online: Jul 23, 2021

Page range: 201 - 217

DOI: https://doi.org/10.2478/eces-2021-0015

Keywordsbiomass energy, composting, passive aeration, heat exchanger, gas concentration

© 2021 Nele Jaschke et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Supplementary Material Details

Keywords
biomass energy, composting, passive aeration, heat exchanger, gas concentration