Oil-Injected Compressor Speed Control to Prevent Condensation
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Solution Overview
Problem
Existing oil injected compressors face condensate formation issues due to corrosive effects, which can damage components and require complex and costly redesigns to address, increasing maintenance and operational challenges.
Innovation Solution
A controller unit that connects with measuring means to determine a minimum working speed of the motor based on compressor pressure, ambient temperature, and dew point temperature, adjusting the motor speed to maintain the system above the condensation point, thereby preventing condensate formation without significant structural changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flow of injected oil is controlled through a mixing valve to maintain temperature above dew point, then condensate formation is prevented, but the piping structure and overall compressor design become complex and costly
Solution Approach 1:
The patent extracts the temperature control function from the mechanical mixing valve system and transfers it to the motor speed control system. By controlling motor speed to maintain compressor discharge temperature above dew point, the need for complex oil flow mixing valves and associated piping is eliminated, resolving the contradiction between reliability and device complexity
Solution Approach 2:
The patent replaces the mechanical temperature control system (mixing valves and piping) with an electrical control system that adjusts motor speed. This substitution maintains the temperature control function while eliminating the complex mechanical infrastructure, directly addressing the contradiction
2Reliability
If a mixing valve system is implemented to control oil flow and maintain temperature, then condensate formation is avoided, but maintenance frequency and costs increase
Solution Approach 1:
The patent removes the mixing valve system from the compressor architecture and replaces its function with motor speed control. This extraction eliminates the mechanical components that require maintenance while preserving the essential temperature control function, thereby reducing maintenance frequency and costs
Solution Approach 2:
The motor speed control system automatically maintains temperature above dew point through feedback control, eliminating the need for manual intervention or maintenance of separate temperature control mechanisms. The system self-regulates without requiring the mixing valve infrastructure that would need maintenance
3Reliability
If existing compressor units are retrofitted with temperature control systems, then condensate formation can be prevented, but significant intervention and costs are required
Solution Approach 1:
The patent makes the motor speed control system multi-functional by using it for both compression control and temperature control. This universal approach allows existing compressors to prevent condensate formation without adding separate temperature control infrastructure, enabling easy retrofitting while maintaining reliability
Solution Approach 2:
The patent replaces the need for mechanical temperature control retrofits (mixing valves, piping modifications) with an electrical control solution that adjusts motor speed. This substitution significantly reduces retrofit complexity and cost while achieving the same reliability benefit of condensate prevention
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
This solution effectively prevents condensate formation, extends the lifetime of the compressor and its components, reduces maintenance costs, and improves operational efficiency by maintaining the motor speed at a minimum level necessary to keep the system above the condensation point, thus ensuring the compressor operates within a safe temperature range.
Implementation Method 1
a processing unit provided with an algorithm for determining a minimum working speed of the motor on the basis of the measured working pressure, the ambient temperature and a dew point temperature
Implementation Method 2
maintaining the temperature of the compressed gas above the dew point by setting the temperature of the lubricating and cooling oil at a desired value
Data Source
Figure 1
Figure 2
AI summary
The present invention is directed to a controller unit for controlling the speed of a motor (3) for driving an oil injected compressor (1), said controller unit (9) comprising: a data connection (12, 13, 14); a first module (17) configured to receive data through said data connection (12, 13, 14); whereby the controller unit (9) further comprises -a processing unit (18a) determining a minimum working speed (rpmmin)of the motor (3) on the basis of the measured working pressure (pw), the ambient temperature (Tambient) and a dew point temperature (Tdew point); and a comparator unit (19a) configured to compare the determined minimum working speed (rpmmin) with the retrieved working speed (rpm) of the motor (3) and, said processing unit (18a) further comprising a signal generating unit (20a) configured to send a signal to said motor for increasing the working speed (rpm) of the motor (3) to at least the determined minimum working speed (rpmmin), if said retrieved working speed (rpm) is lower than the determined minimum working speed (rpmmin).