Oxygen Injection System for Direct Reduction Process
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Solution Overview
Problem
Conventional direct reduction processes face limitations in O2 flow rate flexibility, uniform distribution of O2, and increased complexity and cost due to water-cooling requirements, with incomplete combustion and carbon deposition issues.
Innovation Solution
The implementation of a coaxial O2 and EnNG injection system with variable flow rates and increased injection points, utilizing EnNG shroud gas for cooling and a brick orifice to enhance partial combustion, allowing for safer and more uniform distribution of O2 and EnNG, and optimizing the O2/EnNG ratio to minimize carbon deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single O2 injection pipe is used with self-cooling flow, then the system is simple, but the O2 flow rate flexibility is limited and uniform distribution is difficult to achieve
Solution Approach 1:
The single O2 injection pipe is divided into multiple separate O2 injection pipes (e.g., 4 pipes), each capable of independent flow rate control. This segmentation enables flexible adjustment of total O2 flow rate by controlling individual pipe flows, while maintaining system simplicity through using multiple basic injection units rather than a complex single-unit design.
2Object-affected harmful factors
If O2 injection pipe projects far through duct wall, then hot spot on duct wall is prevented, but pipe bending occurs and frequent replacement is required
Solution Approach 1:
A water-cooled section is introduced as an intermediary component between the O2 injection pipe and the duct wall. This water-cooled section acts as a heat sink that protects the duct wall from hot spots caused by O2 combustion, while allowing the O2 injection pipe to remain shorter and avoid bending stresses that would require frequent replacement.
3Object-affected harmful factors
If water-cooled O2 injection pipe is used, then hot spot problem is solved, but system complexity and cost increase
Solution Approach 1:
The cooling function is segmented and distributed to multiple locations: water-cooled sections are placed only at the duct wall interface points where hot spots occur, rather than cooling the entire O2 injection pipe. This localized cooling approach solves the hot spot problem while minimizing system complexity and cost by avoiding unnecessary cooling infrastructure.
4Reliability
If O2 and EnNG are injected at different locations, then stable combustion is achieved, but C deposition occurs and reductant is depleted
Solution Approach 1:
The O2 injection and EnNG injection systems are merged into a coordinated dual-injection configuration where both gases are introduced at strategically positioned locations. The system combines the stability benefit of separate injection with optimized spacing and flow rate control to prevent carbon deposition and maintain adequate reductant levels, achieving both combustion stability and preventing harmful byproducts.
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 configuration improves O2 flow rate flexibility, enables uniform distribution, reduces temperature increase, and extends the life of O2 injection pipes by preventing hot spots, while maximizing partial combustion and minimizing carbon deposition.
Implementation Method 1
cooling the O2 injection pipes using EnNG shroud gas in a coaxial EnNG/O2 injection configuration
Implementation Method 2
Combustion of the injected O2 14 with the reducing gas 10 maintains the temperature of the bustle gas at about 900 degrees C or more before entering the SF and compensates for the heat consumed by the in-situ reforming inside the SF
Implementation Method 3
the O2 14 reacts mainly with the H2 and CO in the reducing gas stream 10 to decrease the amount of reductant and maximize the temperature rise through full oxidation
Implementation Method 4
makes it possible to safely inject O2 very close to the point of EnNG injection, such that the partial combustion of the EnNG is enhanced and the temperature of the reducing gas entering the SF is reduced
Data Source
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AI summary
An oxygen injection system for a direct reduction process, including: a common circumferential gas injection header adapted to be coupled to an oxygen source and an enrichment natural gas source and adapted to deliver oxygen from the oxygen source and enrichment natural gas from the enrichment natural gas source to a reducing gas stream flowing through a conduit axially disposed within the common circumferential gas injection header through a plurality of circumferentially disposed ports to form a bustle gas stream; wherein the common circumferential gas injection header includes a circumferential oxygen injection header adapted to deliver the oxygen from the oxygen source to the reducing gas stream through the plurality of circumferentially disposed ports and a circumferential enrichment natural gas injection header adapted to deliver the enrichment natural gas from the enrichment natural gas source to the reducing gas stream through the plurality of circumferentially disposed ports.