Method for controlling a rotary screw compressor
AssigneeGardner Denver Deutschland GmbH
InventorUlrich Thomes
Life of this patent
Estimating the term…
Abstract
The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.
Claims13
A method for controlling a rotary screw compressor with a first air-end and a second air-end, wherein the first air-end compresses a gaseous medium and leads to the second air-end, which further compresses the medium, the method comprising:
- detecting a flow of the compressed gaseous medium at the outlet of the second air-end;
- adjusting a rotation speed of the first air-end when the flow fluctuates in a range between a maximum value and a predetermined minimum value, while maintaining a predetermined outlet pressure;
- adjusting a rotational speed of the second air-end when the flow fluctuates in the range between the maximum value and the predetermined minimum value, while maintaining the predetermined outlet pressure;
- and
- reducing the rotational speed of the first air-end to a predetermined idling speed when the flow falls below the predetermined minimum value to reduce the flow delivered by the first air-end to the second air-end, wherein a speed ratio between the second air-end and the first air-end when the flow taken at the outlet of the second air-end fluctuates in a range between the maximum value and the predetermined minimum value is different than the speed ratio between the second air-end and the first air-end when the flow taken at the outlet of the second air-end falls below the predetermined minimum value.
A method for controlling a rotary screw compressor with a first air-end and a second air-end, wherein the first air-end compresses a gaseous medium and leads to the second air-end, which further compresses the medium, and wherein both air-ends are driven separately and speed controlled, the method comprising:
- cooling the compressed gaseous medium from the first air-end via an inter-stage cooler prior to directing the cooled, compressed gaseous medium to the second air-end;
- detecting a flow of the compressed gaseous medium at the outlet of the second air-end;
- adjusting a rotation speed of the first air-end when the flow fluctuates in a range between a maximum value and a predetermined minimum value, while maintaining a predetermined outlet pressure;
- adjusting a rotational speed of the second air-end when the flow fluctuates in the range between the maximum value and the predetermined minimum value, while maintaining the predetermined outlet pressure;
- reducing the speed of the first air-end to a first predetermined idling speed when the flow falls below the predetermined minimum value;
- and
- reducing the speed of the second air-end to a second predetermined idling speed when the flow falls below the predetermined minimum value,
- wherein a speed ratio between the second air-end and the first air-end in response to the flow being above the predetermined minimum value differs from the ratio of the second predetermined idling speed to the first predetermined idling speed.
Dependencies are inferred from the claim text.