Aqueous Phase Oxidation Process Oxygen Transfer Control
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Solution Overview
Problem
Conventional aqueous phase oxidation processes face challenges such as high energy consumption, emission of noxious gases, incomplete metal recovery, and difficulties in controlling oxygen gas supply and pressure fluctuations, leading to inconsistent reaction rates and equipment oversizing.
Innovation Solution
An improved aqueous phase oxidation process that involves pre-processing feedstock to uniform particle size, using a combination of nitric and sulfuric acids, and dispersing oxygen gas from the reactor headspace into the reaction mixture to maintain consistent oxygen levels, allowing for efficient oxidation of organic and inorganic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen gas is bubbled into the aqueous phase to oxidize reduction products of nitric acid, then oxidation efficiency is improved, but oxygen gas separates and collects in the headspace requiring large amounts to be supplied
Solution Approach 1:
The patent implements a feedback control system where oxygen transfer efficiency is continuously monitored and used to adjust the oxygen supply rate. This ensures optimal oxidation efficiency while preventing excessive oxygen consumption and headspace accumulation through real-time regulation of the oxygen input based on actual transfer performance.
2Ease of operation
If oxygen gas supply is controlled based on headspace measurement, then control simplicity is improved, but measurement precision deteriorates due to tenuous relationship between headspace and aqueous phase oxygen levels
Solution Approach 1:
The patent replaces the indirect mechanical measurement approach (headspace oxygen measurement) with direct measurement of oxygen transfer efficiency into the aqueous phase. This substitution enables precise monitoring of actual oxygen availability to microorganisms, eliminating the decoupling between headspace and liquid phase oxygen levels while maintaining operational simplicity through automated control.
3Productivity
If reactor pressure is maintained high for oxidation reactions, then reaction rate is improved, but pressure fluctuations make continuous feed material introduction difficult
Solution Approach 1:
The patent employs dynamic pressure control systems that can rapidly adjust reactor pressure to accommodate continuous feed material introduction while maintaining optimal oxidation conditions. The system dynamically balances pressure stability with reaction rate requirements, enabling consistent feeding without sacrificing productivity through real-time pressure modulation during the oxidation process.
4Reliability
If residence time is extended to account for feed material inconsistencies, then oxidation completeness is improved, but equipment size must be increased
Solution Approach 1:
The patent utilizes parameter changes including temperature, pressure, and oxygen transfer rate to accelerate oxidation reactions, enabling complete oxidation within shorter residence times. By dynamically adjusting these parameters in response to feed material characteristics, the system achieves reliable oxidation completeness without requiring oversized equipment, thus reducing capital costs while maintaining treatment efficacy.
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 process achieves complete or near-complete oxidation of feedstocks with reduced energy consumption, minimal gas emissions, and improved process control, enabling efficient and cost-effective oxidation of various materials.
Implementation Method 1
The feedstock is oxidized in an aqueous reaction mixture by one or more oxidizing acids
Implementation Method 2
Oxygen gas may be supplied to the reaction mixture to reoxidize the reduction products of the oxidizing acid
Implementation Method 3
The oxygen gas was initially bubbled into the aqueous phase but quickly separated and collected in the headspace of the reactor where it was eventually removed
Data Source
AI summary
An improved oxidization process may be used to oxidize a wide variety of feedstocks. Oxidation takes place in a reactor where the feedstock is mixed with an oxidizing acid, such as nitric acid. The reaction mixture may also include a secondary oxidizing acid such as sulfuric acid as well as water and/or dissolved and mechanically mixed oxygen gas. The reactor may be maintained at an elevated pressure such as at least approximately 2070 kPa or desirably at least approximately 2800 kPa. The temperature of the reaction mixture may be maintained at no more than 210° C.