Gradient Flow Pump Stroke Control for Compositional Noise
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Solution Overview
Problem
High pressure gradient liquid chromatography systems face compositional noise due to refilling of pump heads, leading to deviations in desired gradient composition and changing noise frequency characteristics.
Innovation Solution
A method and system where multiple pumps generate pump strokes with initiation times and volume contributions controlled to maintain a constant sum of liquid volumes between consecutive initiations, ensuring a constant compositional noise frequency throughout the gradient duration, independent of individual pump flow rates and frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pump heads are periodically refilled to maintain constant fluid flow, then fluid flow is maintained, but compositional noise is generated causing deviation from desired gradient composition
Solution Approach 1:
The patent divides the pumping system into multiple independent pump heads (first pump, second pump, third pump) that operate in parallel. Each pump head can be refilled independently at different times, allowing the system to maintain continuous flow while managing compositional noise through coordinated segmentation of the refilling operations across multiple pumps.
Solution Approach 2:
The patent implements preliminary action by coordinating the refilling operations of multiple pump heads in advance. The control system manages the refilling timing and sequence of different pump heads to ensure that compositional noise from refilling operations is minimized and does not deviate from the desired gradient composition, while maintaining continuous fluid flow.
2Stability of the object's composition
If pump strokes are controlled to maintain constant sum of volume contributions, then compositional noise frequency is stabilized, but pump stroke volume relationships become complex
Solution Approach 1:
The patent employs feedback control where the control system continuously monitors the pump stroke operations and adjusts the volume contributions of each pump head based on real-time conditions. This feedback mechanism stabilizes the compositional noise frequency by ensuring the sum of volume contributions from all pump strokes remains constant, while the control system automatically manages the complexity of coordinating multiple pumps.
Data Source
AI summary
Described is a method of generating a flow having a composition gradient. A plurality of pump strokes is generated for each pump in a plurality of pumps. Each pump stroke has an initiation time and provides a volume contribution of a liquid to be mixed in the flow according to the composition gradient for the flow. The pump strokes of the pumps are controlled so that a sum of the volume contributions of the liquids that occurs between consecutive initiations of one of the pumps is maintained at a constant value throughout the duration of the flow. For each pump, the flow rates and the times between stroke initiations can change as long as the sum of all volumes contributed between the consecutive initiations of one of the pumps is held constant. Advantageously, the method achieves a constant compositional noise characteristic throughout the duration of the flow.