Variable Speed Mixer Control for Wastewater Energy Reduction
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Solution Overview
Problem
Existing wastewater treatment systems consume excessive energy during anoxic and/or anaerobic processes due to mixer machines operating at full speed, even during peak loads, which is inefficient and shortens equipment lifespan.
Innovation Solution
Implementing a variable speed drive for mixer machines to alternate between Normal Operation Mode, where the mixer operates at the highest suspension speed or process speed, and Reduced Operation Mode, where the speed is below suspension speed, allowing for energy savings without compromising treatment results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mixer machines operate at full operational speed during anoxic and/or anaerobic processes, then solid matter suspension is maintained, but energy consumption increases unreasonably
Solution Approach 1:
The patent applies dynamics by making the mixer machine's operational speed variable rather than fixed. The control system dynamically adjusts the speed between full operational speed (for suspension) and reduced speed (for energy saving) based on real-time assessment of suspension requirements, thereby resolving the contradiction between maintaining reliable suspension and reducing energy consumption.
Solution Approach 2:
The patent changes the operational parameter (speed) of the mixer machine from a constant full-speed operation to a variable speed operation. By adjusting the speed parameter between two states (full speed and reduced speed), the system maintains suspension reliability when needed while minimizing energy consumption during periods when full speed is not required.
2Productivity
If mixer machines are dimensioned for peak process load, then sufficient mixing capacity is available, but energy consumption during normal operation becomes excessive
Solution Approach 1:
The patent applies partial action by operating the mixer machine at reduced speed during normal operation, using only the portion of mixing capacity that is actually needed rather than always deploying the full capacity designed for peak loads. This resolves the contradiction by providing sufficient mixing capacity when required while avoiding excessive energy consumption during normal operation.
3Reliability
If mixer machines operate continuously at full speed, then treatment effectiveness is maintained, but equipment lifespan is reduced
Solution Approach 1:
The patent applies periodic action by alternating the mixer machine between full operational speed and reduced speed in controlled cycles. This periodic operation maintains treatment effectiveness when full speed is applied while allowing the equipment to experience reduced stress during reduced-speed periods, thereby extending equipment lifespan.
Data Source
AI summary
A method for controlling a treatment apparatus arrangement in a treatment plant, the treatment plant including a basin housing a liquid and solid matter. The operating condition in the basin is anoxic and/or anaerobic, and the treatment apparatus arrangement includes at least one mixer machine located in the basin and a variable speed drive operatively connected to the mixer machine. The variable speed drive operates the mixer machine alternately in a Normal Operation Mode, in which an operational speed of the mixer machine is at least the greater of a suspension speed and a process speed, and a Reduced Operation Mode, in which the operational speed of the mixer machine is below the suspension speed. Also described is a treatment apparatus arrangement and a treatment plant, respectively.