Direct Reduced Iron Carbon Content via Liquid Injection
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Solution Overview
Problem
Current DRI manufacturing methods face challenges in maintaining carbon content in the DRI product while reducing the carbon footprint, as increasing hydrogen content in the reducing gas reduces carbon content and injecting hydrocarbons increases the carbon footprint.
Innovation Solution
Injecting a carbon-bearing liquid, such as biofuel or liquid hydrocarbons, below the reduction zone in a direct reduction furnace to increase the carbon content of the DRI product, while using a reducing gas with a high hydrogen content produced by electrolysis powered by renewable energy, and separating the top reduction gas to capture and utilize hydrogen and CO2-rich streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the hydrogen content in the reducing gas is increased to reduce CO2 emissions, then the carbon footprint is reduced, but the carbon content in the DRI product decreases
Solution Approach 1:
The direct reduction shaft is divided into distinct zones (reduction zone, transition zone, cooling zone) with different functions. Carbon-bearing liquid is specifically injected into the transition zone and/or cooling zone, separating the carbon addition function from the reduction function, allowing independent control of carbon content and CO2 emissions.
Solution Approach 2:
A carbon-bearing liquid (such as biofuel or liquid hydrocarbons) is introduced as an intermediary substance to transfer carbon to the DRI product. This liquid is injected below the reduction zone and vaporizes in the transition zone, providing carbon through cracking reactions without requiring hydrocarbon injection into the reduction zone, thus maintaining low CO2 emissions while increasing product carbon content.
2Quantity of substance
If hydrocarbons are injected into the shaft to increase carbon content, then the DRI product carbon content increases, but the carbon footprint increases
Solution Approach 1:
The invention changes the physical state of the carbon source from gaseous hydrocarbons (high carbon footprint) to liquid carbon-bearing substances (lower carbon footprint). The liquid is injected and vaporized in the transition zone, changing the process parameters to achieve carbon transfer with reduced environmental impact.
Solution Approach 2:
The invention converts the potentially harmful effect of carbon injection (increased carbon footprint) into a benefit by using carbon-bearing liquids that can be derived from renewable sources (biofuels). The carbon is transferred to the product without the associated greenhouse gas emissions of traditional hydrocarbon injection.
3Quantity of substance
If carbon-bearing liquid is injected below the reduction zone, then the carbon content of DRI product increases, but the process complexity increases
Solution Approach 1:
The injected carbon-bearing liquid utilizes the existing thermal field in the transition zone for vaporization and cracking. The hot metallized product provides the necessary heat to vaporize the liquid and drive the cracking reactions, eliminating the need for separate heating systems or complex process control.
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 method effectively increases the carbon content of the DRI product to enhance its transportability and combustion potential while significantly reducing the carbon footprint of the process by utilizing renewable energy and capturing CO2.
Implementation Method 1
Oxygen contained in ores and pellets is removed in stepwise reduction of iron oxides in counter-current reaction between gases and oxide
Implementation Method 2
Injection of natural gas in the transition zone is using sensible heat of the metallized product in the transition zone to promote hydrocarbon cracking and carbon deposition
Implementation Method 3
In this section carburization of the metallized product happens. Carburization is the process of increasing the carbon content of the metallized product inside the reduction furnace
Implementation Method 4
using a reducing gas with a high hydrogen content produced by electrolysis powered by renewable energy
Data Source
AI summary
A method for manufacturing direct reduced iron wherein oxidized iron is reduced in a direct reduction furnace by a reducing gas, the direct reduction furnace including a reduction zone, a transition zone and a cooling zone, a carbon-bearing liquid being injected below the reduction zone.