Liquid Supply Filtration Shutdown Pressure Control
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Solution Overview
Problem
Conventional liquid processing apparatuses face contamination of the processing liquid in the circulation line due to foreign matter passing through filters when the circulation flow is shut down, primarily due to the discharge pressure of the pump causing excessive differential pressure across the filter.
Innovation Solution
A liquid supply system with a tank, pump, filter, back pressure valve, and controller that controls the differential pressure and flow rate during shut-down and start-up processes to maintain it within predetermined thresholds, using sensors and valves to manage the pressure and flow dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump discharge pressure is high during circulation, then the circulation flow rate is sufficient for processing, but the differential pressure across the filter becomes excessive when shutting down, causing foreign matter to pass through
Solution Approach 1:
The back pressure valve is configured to dynamically adjust its opening degree based on the pump discharge pressure. During circulation, the valve maintains a closed state to ensure high flow rate, while during shutdown it gradually opens to control the differential pressure across the filter, preventing foreign matter from passing through
Solution Approach 2:
The system changes the pressure parameter dynamically by controlling the back pressure valve opening degree. When the pump discharge pressure exceeds a predetermined threshold during shutdown, the valve opens to reduce the differential pressure across the filter, thereby maintaining processing liquid cleanliness
2Reliability
If the back pressure valve opens during shutdown to reduce differential pressure, then foreign matter is prevented from passing through the filter, but the circulation flow rate decreases
Solution Approach 1:
The back pressure valve dynamically adjusts its opening degree based on real-time pump discharge pressure. During circulation, the valve remains closed to maintain high flow rate, while during shutdown it gradually opens only when discharge pressure exceeds the threshold, thus minimizing impact on circulation productivity while ensuring cleanliness
3Loss of time
If the pump stops suddenly, then the circulation flow stops immediately, but the discharge pressure causes excessive differential pressure across the filter allowing contamination
Solution Approach 1:
The back pressure valve performs preliminary action by gradually opening before the pump completely stops. This preliminary adjustment of the valve opening degree controls the differential pressure across the filter during the shutdown transition, preventing foreign matter from passing through even as the pump discharge pressure decreases
Solution Approach 2:
The system uses feedback from the pump discharge pressure to control the back pressure valve. When the discharge pressure exceeds a predetermined threshold during shutdown, the valve opens to reduce differential pressure, and closes when pressure is within the threshold, creating a closed-loop control that maintains cleanliness during shutdown
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 approach effectively suppresses contamination of the processing liquid in the circulation line by preventing excessive differential pressure and flow rates that could dislodge trapped foreign matter, ensuring the liquid remains clean during maintenance and start-up phases.
Implementation Method 1
The pump forms the circulation flow of the processing liquid in the circulation line
Implementation Method 2
The filter is provided on the downstream side of the pump in the circulation line
Implementation Method 3
The back pressure valve is provided on the downstream side of the filter in the circulation line
Data Source
AI summary
A liquid supply system includes: a tank that stores a processing liquid; a circulation line that returns the processing liquid sent from the tank, to the tank; a pump that forms a circulation flow of the processing liquid in the circulation line; a filter provided on a downstream side of the pump in the circulation line; a back pressure valve provided on a downstream side of the filter in the circulation line; and a controller that controls each unit. When stopping an operation of the pump, the controller controls the pump and the back pressure valve such that a differential pressure between an upstream side and a downstream side of the filter becomes equal to or less than a predetermined threshold value, during a period from when a discharge pressure of the pump starts to decrease until the operation of the pump is stopped.