Direct Reduced Iron CO2 Capture via Amine Absorption
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Solution Overview
Problem
Direct reduction processes for iron ore produce significant CO2 emissions, primarily from the use of carbon-bearing fuels in reformers and heaters, which are not selectively controlled, contributing to atmospheric pollution.
Innovation Solution
Implementing a method that utilizes a chemical absorption system to extract almost pure CO2 from spent gases and switches to hydrogen as the primary fuel for burners, with additional hydrogen recovery through PSA or membrane systems, ensuring that carbon-containing gases are recycled and treated to minimize atmospheric CO2 emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon-bearing fuels are used in reformers and heaters, then energy requirements are met, but CO2 emissions increase significantly
Solution Approach 1:
The patent extracts and removes CO2 from the gas stream using chemical absorption with amine solutions, separating it from the hydrogen and carbon monoxide. This allows the CO2 to be captured and stored or utilized, while the remaining gas continues to provide energy in the form of hydrogen and carbon monoxide, thus decoupling energy production from CO2 emissions.
Solution Approach 2:
The patent changes the chemical composition parameters of the fuel gas by converting carbon-bearing fuels into hydrogen-rich gas through reforming processes. This parameter change enables the system to maintain energy content while reducing CO2 emissions, as hydrogen combustion produces water instead of CO2.
2Object-generated harmful factors
If CO2 is removed from spent reducing gas, then CO2 emissions are reduced, but system complexity increases
Solution Approach 1:
The patent introduces amine-based chemical absorbents as intermediaries to facilitate CO2 removal. These absorbents form reversible chemical complexes with CO2, enabling selective capture from the gas stream. The amine solution acts as a mediator that can be regenerated and recycled, reducing the need for complex separation systems.
Solution Approach 2:
The patent implements a self-regenerating absorption system where the amine solution is regenerated in situ using the spent reducing gas itself. The regenerated amine solution is then reused for CO2 capture, creating a self-sustaining cycle that reduces the need for external energy input and complex system configurations.
3Object-generated harmful factors
If hydrogen is used as fuel instead of carbon-bearing fuels, then CO2 emissions are minimized, but hydrogen production complexity increases
Solution Approach 1:
The patent makes the system self-sufficient by using the spent reducing gas from the iron ore reduction process itself as the feedstock for hydrogen production. The CO and other gases in the spent stream are converted to hydrogen through reforming and water-gas shift reactions, eliminating the need for external hydrogen sources and reducing overall system complexity.
Solution Approach 2:
The patent merges the CO2 capture process with the hydrogen production process by using the same spent reducing gas stream for both purposes. The amine absorption and subsequent reforming reactions occur in an integrated manner, combining what would traditionally be separate processes into a unified system that simultaneously captures CO2 and produces hydrogen.
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 approach significantly reduces CO2 emissions from direct reduction plants by maximizing selective CO2 absorption and minimizing non-selective emissions, allowing for the containment and reuse of CO2, thereby addressing environmental concerns and regulatory compliance.
Implementation Method 1
the CO2 by-product is removed from the reducing gas stream by chemical absorption in a unit where the CO2 containing gas is contacted with a liquid solution which reacts with said CO2
Implementation Method 2
CO2 can be removed from a mixture of gases by using a physical adsorption system of the PSA or VPSA type
Implementation Method 3
The reducing gas is generally obtained by reformation of natural gas in an external catalytic reformer
Implementation Method 4
Said tubes are externally heated by hot combustion products (including CO2 in significant amount) released by the burners
Data Source
AI summary
Production method and apparatus for direct reduced iron (DRI), a.k.a sponge iron, by contacting iron oxides with recycled and regenerated hot reducing gases containing H2 & CO2. This invention decreases uncontained emission of CO2 to the atmosphere from combustion of carbon-bearing fuels in the reducing-gas heater by substituting, at least partially, a gas mainly comprising hydrogen in lieu of the usual carbon-bearing fuels. The hydrogen fuel stream, depleted of CO2 by means of a physical gas separation unit (which can be a PSA/VPSA type adsorption unit, a gas separation membrane unit or a combination of both such units) is derived from at least a portion of regenerated reducing gases being recycled to the reduction reactor. The derived hydrogen fuel stream is combusted in the reducing gas heater and/or other thermal equipment in the reduction plant, thus decreasing the CO2 emissions directly to the atmosphere.