Fluid Analyzer Using Air Dilution for Flammable Substance Safety
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Solution Overview
Problem
Analyzers for fluids containing flammable substances face challenges in preventing explosions in potentially explosive atmospheres, particularly due to the high cost of oxygen-free diluter gases and the risk of explosion when these gases come into contact with air or oxidizers.
Innovation Solution
An analyzer that uses air as the diluter gas, with a gas source configured to deliver a flow containing an oxidizer, an injector that introduces fluid samples to maintain an average volume fraction of less than 1/2000, and a detector equipped with a micro-sensor, ensuring safe analysis by maintaining the flammable substance concentration below the explosive limit and using a flushing gas to maintain overpressure and prevent ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen-free diluter gas (such as nitrogen from cryogenic distillation or hydrogen) is used to prevent explosion, then safety is improved, but operating cost increases due to the non-negligible unit cost of these special gases
Solution Approach 1:
The invention changes the concentration parameter of the flammable substance in the gas stream by introducing it in small discrete samples (less than 1/2000 average volume fraction) into air, rather than using oxygen-free gas. This parameter change allows the use of cheap air while maintaining safety by keeping the concentration below explosive limits.
Solution Approach 2:
The injector introduces fluid samples in a periodic, discrete manner into the continuous air stream, rather than continuous mixing. This periodic injection ensures that at any given moment, the concentration remains low and safe, while allowing the use of inexpensive air as the diluter gas.
2Loss of energy
If air is used as diluter gas to reduce operating cost, then operating cost decreases, but the risk of explosion increases due to the presence of oxidizer
Solution Approach 1:
The invention controls the concentration parameter of the flammable substance to remain below the explosive limit (less than 1/2000 average volume fraction) when mixed with air containing oxidizer. This parameter control allows the use of cheap air while preventing explosion by maintaining safe concentration levels.
Solution Approach 2:
By introducing samples periodically rather than continuously, the system ensures that the concentration of flammable substance in the air stream remains low at all times, preventing the formation of explosive mixtures while still allowing effective detection.
3Measurement precision
If discrete sample injection is used to maintain low concentration, then measurement precision is improved, but device complexity increases due to the need for precise injection control
Solution Approach 1:
The injector is designed to introduce discrete samples at regular intervals, creating a periodic flow pattern. This periodic injection simplifies the control mechanism compared to continuous precise dosing, while still achieving the required low concentration levels for safe operation and accurate detection.
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 allows for safe and cost-effective analysis of flammable substances by diluting the fluid samples to concentrations below the explosive limit, reducing the risk of explosion and minimizing the use of expensive special gases, while maintaining a competitive operating cost.
Implementation Method 1
the detector comprises at least one micro-sensor for detecting the analyte
Implementation Method 2
the injector is configured to introduce into the flow of diluter gas samples of the fluid such as the average volume fraction of the fluid in the gas stream is less than 1/2000
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to an analyser 1 for analysing a fluid 3 comprising at least one substance to be analysed and at least one flammable substance, including: a gas source 9 for providing a flow of diluting gas; an injector 11 for injecting samples of the fluid into the flow of diluting gas and for producing a gas stream; and a detector 7 for analysing the gas stream; the gas source is designed such as to supply a flow of diluting gas containing an oxidiser of the flammable substance, preferably such as to supply a flow of air; the injector is configured to inject samples of the fluid into the flow of diluting gas such that the mean volumetric fraction of the fluid in the gas stream is lower than 1/2,000, preferably lower than 1/20,000; and the detector includes at least one microsensor for detecting the substance to be analysed. The invention also relates to the corresponding method.