Self-Cleaning Sample Extraction System with Back-Flush Filter
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Solution Overview
Problem
Existing online sampling apparatuses face issues with sample contamination and filter clogging, leading to environmental concerns and frequent maintenance needs.
Innovation Solution
A self-contained sampling apparatus with a filter assembly that reduces clogging and facilitates cleaning by using a variable volume chamber and piston system to flush excess sample back into the process stream, along with a novel filter design featuring a cross-sectional flow-through area greater than the inlet passage and a bypass passage for back flushing, which helps dislodge and remove unwanted substances from the filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filters are used to filter sample from process stream, then undesired substances are removed from sample, but filters become clogged requiring frequent replacement and cleaning
Solution Approach 1:
The system reverses the normal flow direction periodically to clean the filter. During back-flush mode, the piston moves in reverse to push process stream fluid through the filter in the opposite direction, dislodging and removing accumulated particulates that would otherwise clog the filter during normal operation.
Solution Approach 2:
The filter cleaning is performed periodically by switching between normal sampling mode and back-flush cleaning mode. The controller automatically alternates between these two modes, with each filter element undergoing multiple back-flush cycles to maintain filtration effectiveness without continuous manual intervention.
2Reliability
If excess sample is discarded after analysis, then sample contamination is avoided, but environmental issues arise
Solution Approach 1:
Instead of discarding excess sample into waste, the system recovers it by flushing it back into the process stream. The bypass valve directs excess sample through a return line that reconnects to the process stream upstream of the sampling point, allowing the sample to be reused and preventing environmental contamination.
3Object-generated harmful factors
If sample is flushed back into process stream, then environmental impact is reduced, but sample contamination may occur
Solution Approach 1:
The system divides the filtering function into multiple independent filter elements arranged in parallel. Each filter element can be cleaned independently through back-flushing while others remain in service. The segmentation also allows separate control of filtration and back-flush paths through dedicated valves for each element.
Solution Approach 2:
The system dynamically switches between normal sampling mode and back-flush cleaning mode using electronically controlled valves. The controller monitors filter differential pressure and automatically actuates the appropriate valves to transition between modes, optimizing both sample purity and filter maintenance without manual intervention.
4Reliability
If filter cross-sectional area is increased, then particulate embedding is reduced, but device complexity increases
Solution Approach 1:
The filter assembly design integrates multiple functions into a compact unit: filtration during normal operation, back-flush cleaning capability, differential pressure monitoring, and automated valve control. This multi-functional integration achieves the benefits of increased filter area without proportionally increasing overall device complexity.
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 solution effectively reduces filter clogging, minimizes maintenance, and eliminates the need for disposing of excess sample, thereby enhancing operational efficiency and reducing environmental impact.
Implementation Method 1
an extraction cylinder including a variable volume chamber and a piston movable by an actuator back and forth in the cylinder to increase and decrease the volume of the variable volume chamber
Implementation Method 2
a filter assembly interposed between the sample probe and sampling valve for filtering undesired substances from the fresh sample
Implementation Method 3
to move the piston at a second rate greater than the first rate to decrease the variable volume chamber to flush excess sample back into the process stream and clean the filter of undesired substances filtered from the fresh sample
Data Source
AI summary
A sampling apparatus for use with a sample analyzer comprises a sample probe insertable into a process stream, and an extraction cylinder including a variable volume chamber and a piston movable by an actuator back and forth in the cylinder to increase and decrease the volume of the variable volume chamber. A sampling valve is connected between the extraction cylinder and the sample probe, with a sample line connecting the sampling valve to the sample probe, and the variable volume chamber having a capacity substantially greater than the combined volumes of the sample probe, sampling valve and sample line. A filter assembly is interposed between the sample probe and sampling valve for filtering undesired substances from the fresh sample prior to the fresh sample reaching the sampling valve, and a controller is provided for controlling the actuator and the sampling valve, first to move the piston at a first rate to increase the variable volume chamber sufficiently to draw fresh sample from the process stream and past the sampling valve, then to operate the sampling valve for injecting fresh sample into the sample analyzer, and thereafter to move the piston at a second rate greater than the first rate to decrease the variable volume chamber to flush excess sample back into the process stream and clean the filter of undesired substances filtered from the fresh sample.