Abstract: A safety circuit for valves actuated hydraulically via a positioning cylinder. The positioning cylinder in one embodiment is configured to be hydraulically or pneumatically depressurized in an emergency. The positioning cylinder has two cylinder chambers configured to be fluidically connected via a working line. A first and a second series-connected shut-off valve are provided in the working line. The positioning cylinder in another embodiment is configured to be hydraulically or pneumatically actuated in an emergency. The positioning cylinder has at least one first cylinder chamber configured, in an emergency, to be supplied with pressurized fluid via a first pressure medium flow path. A first and a second series-connected shut-off valve are provided in the first pressure medium flow path.

Abstract: The invention relates to a method for reclaiming biogenic mass, in particular sludge, wherein the product to be reclaimed is first dried and then thermally decomposed in a pyrolysis reactor for the purpose of creating pyrolysis gas. The method according to the invention is characterized in that the product is thermally dried in at least two drier stages arranged after one another, wherein the waste heat of the drier stage downstream of the product in the transport direction is used as process heat for the respectively upstream drier stages. The invention further relates to a system for reclaiming biogenic mass, in particular sludge.