Material Gas Concentration Control via Tank Pressure Feedback
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Solution Overview
Problem
Existing material gas concentration control systems face challenges in achieving high accuracy and responsiveness due to fluctuations in evaporation rate and liquid level, leading to deviations in desired concentration and prolonged stabilization times, especially when the liquid level decreases, and require additional sensors like liquid volume meters, increasing costs and complexity.
Innovation Solution
A system that controls the concentration of material gas by measuring and adjusting the pressure in the tank using a first valve in the outlet line, with a concentration measuring part and a pressure measuring part, allowing for real-time adjustment to maintain the desired concentration without altering the carrier gas flow, and estimates the material amount based on pressure changes without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tank temperature is kept constant by a constant temperature bath to maintain saturated vapor pressure, then the partial pressure of material gas is considered constant, but the concentration deviates from desired concentration due to temperature drop from heat of vaporization and changes in material liquid amount
Solution Approach 1:
The patent changes the control parameter from temperature (which has slow response and is affected by heat of vaporization) to total pressure (which responds quickly and directly reflects concentration changes). By controlling total pressure via the outlet valve while independently measuring partial pressure of material gas, the system achieves accurate concentration control without being affected by temperature fluctuations.
Solution Approach 2:
The patent implements feedback control by continuously measuring the total pressure in the tank and comparing it with the target total pressure calculated from the desired concentration and measured partial pressure. The outlet valve is adjusted based on this feedback to maintain the correct concentration, compensating for changes in material liquid amount and evaporation rate.
2Adaptability or versatility
If the temperature in the tank is changed to adjust the saturated vapor pressure for changing material gas concentration, then the concentration can be changed, but the responsiveness becomes slow due to the long time required to change temperature
Solution Approach 1:
The patent changes the control parameter from temperature (slow response) to total pressure (fast response). By adjusting the total pressure through the outlet valve rather than changing temperature, the system can rapidly adjust material gas concentration to match demand changes, achieving both adaptability and high responsiveness.
3Loss of time
If the flow of carrier gas is increased to shorten gas substituting time and reduce setting time, then the responsiveness improves, but the flow of material gas or total flow changes, making it impossible to keep the flow constant
Solution Approach 1:
The patent implements feedback control by continuously measuring total pressure and adjusting the outlet valve to maintain the target total pressure. This ensures that when carrier gas flow changes, the system automatically compensates by adjusting the outlet flow to maintain both constant concentration and constant total flow, achieving both responsiveness and flow stability.
Solution Approach 2:
The patent makes the outlet valve dynamically adjustable based on real-time pressure measurements. When carrier gas flow increases or decreases, the outlet valve automatically opens or closes to maintain constant total flow and concentration, enabling the system to adapt dynamically to flow changes without sacrificing productivity or stability.
4Measurement precision
If additional sensors like liquid volume meters are added to detect material liquid amount and control concentration, then the measurement accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The patent makes the existing pressure sensor serve dual purposes: measuring both the partial pressure of material gas (for concentration calculation) and the total pressure (for flow control and concentration verification). This eliminates the need for additional sensors like liquid volume meters, reducing device complexity and cost while maintaining measurement accuracy.
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 enables high responsiveness and accurate control of material gas concentration, reducing stabilization time and eliminating the need for additional sensors, thereby improving process throughput and reducing costs.
Implementation Method 1
a pressure measuring part to measure a pressure in the tank
Implementation Method 2
the concentration measuring part comprises a pressure measuring part that measures a pressure in the tank
Implementation Method 3
a first valve control part that controls an open degree of the first valve so as to make a measured pressure measured by the pressure measuring part become the set pressure
Implementation Method 4
evaporates the material liquid constantly at a saturated vapor pressure with a temperature of the material liquid kept constant
Implementation Method 5
the saturated vapor pressure changes due to the drop of the temperature because of the heat of vaporization
Data Source
AI summary
A material gas concentration control system for keeping a concentration of a material gas in a mixed gas constant comprising a tank to accommodate the material, an inlet line to input a carrier gas for evaporating the accommodated material into the tank, and an outlet line to output the mixed gas consisting of the material gas evaporated in the tank and the carrier gas, and further comprising a first valve arranged in the inlet line, a concentration measuring part that measures the concentration of the material gas in the mixed gas, and a concentration control part that controls an open degree of the first valve so as to make the measured concentration of the material gas measured by the concentration measuring part become the previously determined set concentration.