Dual Fuel Adiabatic Reactor for Oxyfuel Deoxidation
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Solution Overview
Problem
Existing methods for catalytic deoxidation in oxyfuel processes face challenges such as restricted oxygen conversion per pass, high capital costs, and safety issues due to the use of single fuels in adiabatic reactors, especially when dealing with high oxygen concentrations.
Innovation Solution
A dual fuel approach is implemented using a series of adiabatic reactors with a first auxiliary fuel having a low ignition temperature (like hydrogen) and a second auxiliary fuel with high heat of reaction (like natural gas), allowing for efficient oxygen removal and heat recovery while controlling temperatures and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single auxiliary fuel is used in adiabatic reactors for catalytic deoxidation, then the device complexity is reduced, but the oxygen conversion efficiency per pass is restricted and safety issues arise due to runaway reactions
Solution Approach 1:
The deoxidation process is segmented into multiple adiabatic reactor stages arranged in series. Each stage performs partial oxygen conversion, preventing runaway reactions while achieving high overall conversion efficiency. The segmentation allows the system to handle high oxygen concentrations safely by distributing the conversion across multiple controlled steps.
Solution Approach 2:
The patent combines multiple auxiliary fuels (hydrogen and natural gas) in a dual-fuel approach within the segmented reactor system. Hydrogen provides low-temperature ignition capability to start the reaction, while natural gas contributes high heat of reaction for efficient oxygen conversion. This merging of fuel properties resolves the contradiction between safety and efficiency.
2Ease of operation
If hydrogen is used as auxiliary fuel due to its low ignition temperature, then the ease of operation is improved, but the heat of reaction and overall energy efficiency are reduced
Solution Approach 1:
The reactor system segments the fuel utilization process: hydrogen is used in early stages where low ignition temperature is needed to initiate combustion and operate easily, while natural gas is introduced in subsequent stages to provide high heat of reaction for efficient oxygen conversion. This segmentation allows both fuel types to发挥 their respective advantages.
Solution Approach 2:
The system dynamically adjusts fuel composition and flow rates across different reactor stages based on temperature and oxygen concentration profiles. This dynamic approach allows the system to leverage hydrogen's ease of ignition when needed and natural gas's high energy content when temperature and conversion efficiency are priorities.
3Use of energy by moving object
If natural gas is used as auxiliary fuel due to its high heat of reaction, then the energy efficiency is improved, but the ignition temperature requirement increases operational difficulty
Solution Approach 1:
Hydrogen is used in preliminary reactor stages to ignite the combustion process and raise the temperature to levels where natural gas can effectively participate. This preliminary action by hydrogen removes the ignition temperature barrier for natural gas, allowing natural gas to then provide its high heat of reaction in subsequent stages without operational difficulty.
4Device complexity
If adiabatic reactors are used to simplify the device structure, then the capital cost is reduced, but temperature control becomes difficult and safety risks increase
Solution Approach 1:
The adiabatic reactor system is segmented into multiple stages in series. Each individual reactor remains simple and adiabatic (without active cooling), maintaining low device complexity and capital cost. However, the series arrangement of multiple stages inherently controls temperature by allowing heat dissipation between stages, preventing runaway reactions and improving safety without requiring complex active temperature control in each reactor.
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 dual fuel system enhances oxygen conversion efficiency, reduces capital costs, and prevents runaway reactions by leveraging the lower ignition temperature of hydrogen and the higher reaction heat of natural gas, improving the overall efficiency and safety of the deoxidation process.
Implementation Method 1
a first auxiliary fuel, in particular hydrogen, and a second auxiliary fuel, in particular natural gas, are catalytically combusted with a part of the oxygen
Implementation Method 2
catalytically combusted with a part of the oxygen contained in the secondary gas mixture
Implementation Method 3
a first auxiliary fuel, in particular hydrogen, and a second auxiliary fuel, in particular natural gas, are catalytically combusted with a part of the oxygen contained in the secondary gas mixture
Implementation Method 4
wherein effluents from the reactors are, prior to being passed into the next reactor, cooled by intercoolers
Data Source
AI summary
A method is provided for producing carbon dioxide by combusting a carbonaceous fuel with oxygen or with a gas mixture containing more than 25 mol % of oxygen obtaining a flue gas mixture, wherein the flue gas mixture is processed obtaining a secondary gas mixture containing carbon dioxide and oxygen, and wherein a part of the oxygen contained in the secondary gas mixture is catalytically reacted with a first auxiliary fuel in a reactor system comprising a series of multiple reactors, obtaining further carbon dioxide and water. A further part of the oxygen contained in the secondary gas mixture is catalytically reacted with a second auxiliary fuel in the reactor system. A corresponding apparatus is also described herein.