Reduced Iron Gas Loop Balancing for Low-CO2 Production
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Solution Overview
Problem
Existing reduced iron production methods face challenges in achieving energy conservation and reducing CO2 emissions, as they rely on external natural gas or coke oven gas, leading to fuel gas shortages and increased CO2 emissions.
Innovation Solution
A closed system is implemented where furnace gas is circulated and reused, synthesizing methane from hydrogen and a part of the furnace gas, and adjusting the amounts of furnace gas and water vapor to maintain a healthy mass balance in the system, using CO2-free hydrogen and electricity for heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural gas is used as raw material gas for reducing gas production, then reducing gas can be produced, but CO2 emissions increase and external fuel gas dependency increases
Solution Approach 1:
The patent converts the harmful CO2-rich furnace gas into a useful resource by using it as raw material for methane synthesis. The CO2 that would otherwise be emitted is transformed into methane through chemical reaction with hydrogen, which then serves as fuel for heating and reforming processes, turning a harmful emission into a beneficial energy source.
Solution Approach 2:
The system achieves self-sufficiency by producing its own reducing gas through internal processes. Furnace gas and hydrogen from the reduction process are fed into the methane synthesis unit to generate methane, which is then reformed back into reducing gas, creating a closed-loop system that eliminates external natural gas dependency.
2Quantity of substance
If coke oven gas or converter gas is diverted to reduced iron production, then reducing gas production is enhanced, but fuel gas shortage occurs in downstream processes
Solution Approach 1:
The system produces its own reducing gas using furnace gas and hydrogen from its own reduction process, eliminating the need to divert coke oven gas or converter gas from downstream processes. This self-sufficient approach ensures fuel gas availability is maintained across all plant operations.
Solution Approach 2:
The furnace gas, which would normally be used for heating or flared, is given multiple functions: it serves as raw material for methane synthesis, provides process heating, and maintains system pressure. This multi-functional use maximizes the utility of internally generated gases without compromising downstream fuel gas supply.
3Use of energy by stationary object
If furnace gas is fully used for heating and fuel gas, then heating requirements are met, but reducing gas production is insufficient
Solution Approach 1:
The furnace gas flow is segmented into different functional streams: one portion is directed to the methane synthesis unit as raw material, another portion is used for process heating, and the balance maintains system pressure. This segmentation allows simultaneous achievement of reducing gas production and heating requirements without resource conflicts.
Solution Approach 2:
Furnace gas is pre-treated and directed to the methane synthesis unit before being used for heating purposes. By performing methane synthesis first, the system maximizes reducing gas production from the available furnace gas, ensuring sufficient reducing gas is generated before the remaining gas is consumed for heating.
4Object-generated harmful factors
If a closed system with furnace gas circulation is implemented, then CO2 emissions are reduced, but system complexity increases
Solution Approach 1:
The patent merges the furnace gas handling system with the reducing gas production system by integrating the methane synthesis unit. Instead of separate systems for waste gas treatment and reducing gas generation, the furnace gas circulation loop is combined with the methane synthesis and reforming processes, reducing overall system complexity while achieving CO2 emission reduction.
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 achieves stable operation with reduced CO2 emissions by maintaining a healthy mass balance, utilizing regenerated methane for reducing gas production, and minimizing external fuel gas reliance.
Implementation Method 1
a gas containing methane as a main component is synthesized from hydrogen gas and a part of furnace gas discharged from top of the reducing furnace
Implementation Method 2
the raw material gas is heated and reformed into the reducing gas
Implementation Method 3
the raw material gas is heated and reformed into the reducing gas
Implementation Method 4
the iron oxide is reduced with the reducing gas in the reducing furnace
Data Source
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AI summary
Provided is a method that can realize energy conservation and reduction in CO2 emissions when producing reduced iron with iron oxide. The method for producing reduced iron includes an iron oxide charging process in which iron oxide is charged into a reducing furnace, a reducing gas blowing process in which reducing gas is blown into the reducing furnace, a reduction process in which the iron oxide is reduced with the reducing gas in the reducing furnace, a methane synthesis process in which a gas containing methane as a main component is synthesized from hydrogen gas and a part of furnace gas discharged from top of the reducing furnace, and a gas reforming process in which the methane gas and furnace gas excluding those supplied to the methane synthesis process are used as a raw material gas, and the raw material gas is heated and reformed into the reducing gas, where according to changes in a ratio H2/CO of Hz and CO in reducing gas blown into the reducing furnace, an amount of furnace gas V1 supplied to the methane synthesis process and an amount of water vapor Vw in furnace gas supplied to the gas reforming process are adjusted to control a mass balance in processes from the iron oxide charging process to the reduction process.