Oxygen-Enriched Combustion for Heating Devices Under Air Flow Limits
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Solution Overview
Problem
Conventional methods of combusting fuel in air for heating devices in chemical production processes are limited by mechanical constraints and require significant capital expenditure for pure O2 combustion, leading to inefficient heat and fuel usage.
Innovation Solution
Utilizing membrane-based separation modules to produce oxygen-enriched air (>21 vol. % O2) for combustion, with a countercurrent sweep across the membrane module to enhance energy efficiency and reduce energy consumption, and injecting the enriched oxygen upstream via diffusers for improved mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pure O2 combustion is used to increase fuel efficiency, then energy efficiency is improved, but capital expenditure increases due to availability cost of O2 and furnace modification costs
Solution Approach 1:
The patent applies partial action by using oxygen-enriched air (21-40 vol% O2) instead of pure oxygen combustion. The membrane separation unit produces oxygen-enriched air at moderate concentrations that are sufficient to improve fuel efficiency without requiring complete system redesign. This partial enrichment approach achieves energy efficiency improvements while avoiding the high capital costs associated with pure oxygen combustion systems.
Solution Approach 2:
The membrane separation unit acts as an intermediary device that produces oxygen-enriched air from ambient air. This intermediary solution provides the benefits of oxygen-enriched combustion without requiring direct connection to oxygen supply systems or extensive furnace modifications. The membrane unit serves as a bridge between conventional air combustion and pure oxygen combustion, offering a cost-effective intermediate solution.
2Productivity
If combustion air flow capacity is increased to support higher fuel firing rates, then productivity is improved, but mechanical flow limitation and combustion air flow capacity constraints are reached
Solution Approach 1:
The patent changes the composition parameter of the combustion gas by enriching air with additional oxygen from the membrane separation unit. This parameter change allows the system to burn more fuel per unit of combustion air, effectively increasing productivity without needing to increase combustion air flow capacity. The oxygen enrichment modifies the combustion stoichiometry, enabling higher fuel firing rates within existing air flow constraints.
3Loss of energy
If a second air stream is flowed counter-currently through the membrane module to improve energy efficiency, then energy consumption is reduced, but device complexity increases
Solution Approach 1:
The counter-current sweeping air stream continuously removes oxygen from the permeate side of the membrane, maintaining a concentration gradient that drives continuous oxygen separation. This continuous action prevents oxygen buildup on the permeate side, which would otherwise reduce separation efficiency and increase energy consumption. The sweeping air is subsequently used as combustion air, making the process energetically beneficial despite the added complexity.
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
Increases fuel efficiency and maintains heat distribution while reducing capital expenditure and energy consumption, compared to conventional methods.
Implementation Method 1
flowing a first air stream through a membrane module
Implementation Method 2
using membrane based separation modules to produce an oxygen enriched air (>21 vol. % O2) as a combustion gas
Implementation Method 3
flowing a second air stream counter-currently to the first air stream through a separate air inlet to generate a countercurrent sweep of air across a permeate side of the membrane module
Implementation Method 4
injecting oxygen enriched air upstream of the heating device (e.g., steam cracking furnace) via diffusors, resulting in improved mixing efficiency of oxygen and the fuel
Implementation Method 5
combusting a fuel in the oxygen enriched combustion gas stream to produce heat
Data Source
AI summary
Systems and methods for operating a heating device are disclosed. An oxygen containing stream is first processed to produce an oxygen stream that comprises more than 25 vol. % oxygen. The oxygen stream is then mixed with an air stream to produce a combustion gas stream comprising 21.5 to 27 vol. % oxygen. A fuel is combusted in the combustion gas stream to provide heat for a heating device.