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US 11,686,310 B2Granted
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 (V1L) to reduce the volumetric flow delivered by the first to the second air-end.
Claims20
A rotary screw compressor, comprising:
- a first air-end configured to compress a gaseous medium;
- a second air-end configured to further compress the gaseous medium;
- a first variable speed drive configured to drive the first air-end;
- a second variable speed drive configured to drive the second air-end;
- and
- a control unit communicatively coupled with each of the first variable speed drive and the second variable speed drive, the control unit configured to
- determine a flow of the compressed gaseous medium at an outlet of the second air-end;
- adjust a rotation speed of the first air-end with the first variable speed drive when the flow fluctuates in a range between a maximum value and a predetermined minimum value, while maintaining a predetermined outlet pressure;
- adjust a rotational speed of the second air-end with the second variable speed drive when the flow fluctuates in the range between the maximum value and the predetermined minimum value, while maintaining the predetermined outlet pressure;
- and
- reduce the rotational speed of the first air-end to a predetermined idling speed via the first variable speed drive 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 determined 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 determined at the outlet of the second air-end falls below the predetermined minimum value.
8 more elements
A rotary screw compressor, comprising:
- a first air-end configured to compress a gaseous medium;
- a second air-end configured to further compress the gaseous medium;
- a first variable speed drive configured to drive the first air-end;
- a second variable speed drive configured to drive the second air-end;
- a pressure-relief valve in fluid communication with an outlet of the second air-end;
- and
- a control unit communicatively coupled with the first variable speed drive, the second variable speed drive, and the pressure-relief valve, the control unit configured to
- determine a flow of the compressed gaseous medium at the outlet of the second air-end;
- adjust a rotation speed of the first air-end with the first variable speed drive when the flow fluctuates in a range between a maximum value and a predetermined minimum value;
- adjust a rotational speed of the second air-end with the second variable speed drive when the flow fluctuates in the range between the maximum value and the predetermined minimum value;
- and
- reduce the rotational speed of the first air-end to a predetermined idling speed via the first variable speed drive 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 determined 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 determined at the outlet of the second air-end falls below the predetermined minimum value.
9 more elements
A rotary screw compressor, comprising:
- a first air-end and a second air-end, the first air-end configured to compress a gaseous medium, the second air-end configured to further compress the gaseous medium, wherein each of the first air-end and the second air-end is driven separately and speed controllable;
- a pressure-relief valve in fluid communication with an outlet of the second air-end;
- and
- a control unit configured to
- determine a flow of the compressed gaseous medium at an outlet of the second air-end;
- adjust 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;
- adjust 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;
- open the pressure-relief valve when the flow falls below the predetermined minimum value to at least partially discharge compressed gaseous medium delivered by the second air-end via the pressure-relief valve;
- and
- reduce 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 determined 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 determined at the outlet of the second air-end falls below the predetermined minimum value.
7 more elements
Dependencies are inferred from the claim text.