Rotary Screw Compressor Idle Control Without Throttle Valves
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Solution Overview
Problem
Existing rotary screw compressors face high energy consumption and design complexity during idle mode operation, particularly in multi-stage systems, without providing efficient energy savings or simplified control methods.
Innovation Solution
A method for controlling rotary twin screw compressors with separate and speed-controlled air-ends, utilizing direct drives and eliminating throttle valves, and employing a pressure-relief valve to manage idle mode by reducing rotational speeds and maintaining pressure balance, thereby optimizing energy use and simplifying the system design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a throttle valve is closed in the suction line and a bypass is supplied to the first air-end in idle mode, then the delivery of additional medium is adjusted to avoid pressure increase, but the energy consumption becomes relatively high and the design complexity increases
Solution Approach 1:
The patent removes the throttle valve and bypass from the idle mode control system. Instead of using these additional components to regulate flow, the invention directly controls the speed of the drive means to match the actual demand for compressed air, thereby eliminating the energy waste associated with throttling and bypass operations.
Solution Approach 2:
The patent implements dynamic speed control of the drive means based on actual compressed air demand. The control unit continuously adjusts the rotational speed of the air-ends to match the required delivery rate, allowing the system to operate efficiently across varying load conditions without requiring static throttle valves or bypass arrangements.
2Adaptability or versatility
If a throttle valve is closed in the suction line and a bypass is supplied to the first air-end in idle mode, then the delivery of additional medium is adjusted to avoid pressure increase, but the design complexity increases
Solution Approach 1:
The patent eliminates the intake regulator and its associated throttle valve and bypass components entirely. The idle mode operation is achieved purely through speed control of the drive means, which simplifies the mechanical design and reduces the number of moving parts requiring maintenance and control.
Solution Approach 2:
The patent replaces the mechanical throttle valve and bypass system with an electronic control system that adjusts the speed of the drive means. This substitution of mechanical flow control with electronic speed control reduces mechanical complexity while maintaining the ability to operate in idle mode.
3Reliability
If the compressor is not switched off completely during idle mode, then compressed air can be rapidly re-supplied when needed, but energy consumption remains high
Solution Approach 1:
The patent implements dynamic speed control that allows the compressor to operate at very low speeds during idle mode rather than being completely shut off. This maintains the system in a ready state capable of rapid response when compressed air is needed, while consuming minimal energy during periods of low or no demand.
Solution Approach 2:
The patent changes the operating parameter of the drive means from complete shutdown to variable speed operation. By adjusting the speed parameter to match actual demand, the system maintains readiness for rapid re-supply while avoiding the high energy consumption associated with running at full speed during idle periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly reduces energy consumption and design complexity, allowing rapid transition between idle and load modes while preventing undesirable temperature drops and condensation, thus enhancing operational efficiency and reducing manufacturing costs.
Implementation Method 1
a first rotary screw compressor (201) compresses a gaseous medium (203)
Data Source
AI summary
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.