Plasma Abatement Nozzle With Heated Water Injection
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Solution Overview
Problem
Existing plasma abatement apparatuses have sub-optimal destruction rate efficiency for removing compounds like PFCs from effluent gas streams, particularly due to the lack of hydrogen radicals, which leads to the formation of difficult-to-scrub noxious by-products and reliance on combustible reagents.
Innovation Solution
A nozzle that conveys a plasma stream and introduces heated water vapour to generate hydrogen and oxygen radicals, improving destruction rate efficiency without using combustible materials, by delivering water vapour axially through apertures in the conduit to mix with the plasma stream, thereby enhancing the abatement process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compressed dried air (CDA) is injected as reagent before the Venturi cone, then the abatement reaction can proceed, but the destruction rate efficiency is sub-optimal and noxious by-products like COF2, SOF2, and SO2F2 are formed that are difficult to scrub
Solution Approach 1:
The patent changes the chemical composition parameter of the reagent from compressed dried air (oxygen-based) to water vapour (hydrogen-based). This parameter change transforms the reaction chemistry to produce hydrogen-containing by-products that are water-soluble, thereby improving destruction rate efficiency while eliminating difficult-to-scrub noxious by-products.
Solution Approach 2:
The patent uses water vapour as a disposable reagent that is introduced into the plasma stream, undergoes rapid chemical reactions to destroy PFC compounds, and then dissipates. Water is inexpensive and readily available, replacing the need for expensive specialized reagents while effectively converting harmful compounds into soluble by-products.
2Productivity
If water is introduced into the plasma stream, then hydrogen radicals are generated to improve destruction rate efficiency, but the plasma stream temperature decreases
Solution Approach 1:
The patent pre-heats water to generate water vapour before introducing it into the plasma stream. This preliminary heating action reduces the thermal shock to the plasma stream, minimizing temperature decrease while still enabling the generation of hydrogen radicals for improved destruction rate efficiency.
Solution Approach 2:
The patent utilizes the phase transition of water from liquid to vapour as it is heated and introduced into the plasma stream. This phase transition allows for controlled introduction of hydrogen-containing species that can generate hydrogen radicals without causing excessive cooling, as the vapour integrates more smoothly with the plasma stream.
3Productivity
If hydrogen-containing reagents like H2 or CH4 are used to generate hydrogen radicals, then destruction rate efficiency improves, but the risk of flammable conditions increases
Solution Approach 1:
The patent uses water vapour as a safe, non-flammable alternative to hydrogen-containing reagents. Water vapour is introduced into the plasma stream where it generates hydrogen radicals through plasma decomposition, achieving improved destruction rate efficiency without creating flammable conditions. The water vapour is inexpensive and eliminates safety concerns associated with combustible reagents.
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 nozzle configuration effectively improves the destruction rate efficiency of the abatement process, reducing the formation of noxious by-products and eliminating the need for combustible reagents, while maintaining plasma stream stability and reducing operational costs.
Implementation Method 1
The nozzle is thermally-conductive and arranged to receive water which is heated by the nozzle to provide water vapour
Implementation Method 2
the plasma stream being conveyed. In this way, water is introduced into the plasma stream, which generates both hydrogen and oxygen radicals that help improve the destruction rate efficiency
Data Source
Figure 1
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Figure 2b
AI summary
A nozzle for conveying a plasma stream and a method are disclosed. The nozzle is for conveying a plasma stream from a plasma generator to a reaction chamber, the nozzle comprises: a conduit extending between an inlet arranged to receive the plasma stream and an outlet arranged to fluidly couple with the reaction chamber, the plasma stream being conveyed by the conduit between the inlet and the outlet in an axial direction, wherein the nozzle is thermally-conductive and is arranged to receive water for heating by the nozzle, the nozzle having at least one aperture therein, the aperture being arranged to deliver the heated water in the axial direction for mixing with the plasma stream. In this way, water is introduced into the plasma stream within the nozzle, which generates hydrogen and oxygen radicals that help improve the destruction rate efficiency of the abatement apparatus. This provides for a particularly safe and convenient way to improve the destruction rate efficiency since no combustible materials are required to be supplied to the nozzle to generate those radicals.