Abstract: A centrifugal pump including a rotor and a housing surrounding the rotor, the housing having a connection on the pressure side and another on the intake side, respectively. The housing surrounding the rotor is constructed as a composite part in which a first thin-walled layer (5) defines the inner configuration of the housing, and at least one second layer (11) provides structural stability to the housing.

Abstract: A method and an apparatus for producing biogas from organic matter including a container (1) which is charged with fermentation substrate by a delivery system (13). At least one stirring mechanism (2) is arranged in the container. The feedback value of at least one measurable variable is detected and transmitted to a control unit (4). A reference variable is also provided to the control unit. The control unit calculates the deviation of the feedback value from the reference value, and actuating variables which modify the power input of the stirring mechanism and/or the composition of the container contents and/or the flow behavior of the container contents are adjusted as a function of the deviation.

Abstract: A method and apparatus for producing biogas from organic matter including a container (1) which is charged with fermentation substrate by a delivery system (13), and at least two stirring mechanisms (2) arranged in the container, the stirring mechanisms having propellers (3) which are rotated and generate mostly horizontal currents of the fermentation substrate in the container. The propeller diameters, the propeller geometries, and the positions of the propellers in the container are selected such that a shared mixing zone of the medium is generated in the container. Data for determining the mean speed and/or the viscosity of the medium in the mixing zone are detected and transmitted to a control unit (4) which varies actuating variables which modify the power input of the stirring mechanism into the mixing zone and/or the composition and/or the flow behavior of the container contents.

Abstract: A rotor fastening arrangement, particularly for connecting a drive shaft and a rotor hub of a centrifugal pump assembly, having a fitting surface and at least one contact surface at the drive-shaft end. Respective ends of the drive-shaft (3) and the rotor hub (1a) are each provided with an internally threaded central hole. A fitting surface and at least one contact surface also are formed on the rotor hub (1a). An intermediate shaft (2) is provided between drive shaft (3) and rotor hub (1a) in order to connect the rotor hub and drive shaft. A fitting surface and at least one contact surface are formed respectively at both ends of the intermediate shaft (2) for alignment; at least one connecting member is provided for connecting the intermediate shaft (2) to the drive shaft (3) and the rotor hub (1a), and a seal is arranged on the intermediate shaft.