Reducing Gas Heating With Staged Direct and Indirect Electric Heat
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current DRI processes face challenges in heating reducing gases efficiently and sustainably, particularly with the transition to hydrogen use, as green hydrogen is limited and energy-intensive, and existing electric heating technologies are not optimized for high temperatures and maintenance flexibility.
Innovation Solution
A method involving direct and indirect electric heating, combined with waste heat recovery and optional oxidation or fired heating, to achieve high temperatures for reducing gases without fossil fuel combustion, ensuring flexibility and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fired heaters using natural gas or CO/H2-rich tail gas are used to heat reducing gas, then the reducing gas can be heated to required temperatures, but CO2 emissions increase and energy efficiency decreases
Solution Approach 1:
The patent converts harmful CO2-rich tail gas into a useful heating resource by using it as fuel in the fired heater. This transforms a waste product that would otherwise be emitted into a valuable energy source for heating the reducing gas, thereby reducing the need for additional natural gas consumption and lowering overall CO2 emissions while maintaining energy efficiency
Solution Approach 2:
The patent recovers energy from CO2-rich tail gas that would otherwise be discarded in the atmosphere. By capturing and combusting this tail gas in the fired heater, the system recovers its thermal energy to heat the reducing gas, converting a waste stream into a useful resource and improving overall process energy efficiency
2Object-generated harmful factors
If green hydrogen is used as reducing agent and for firing heaters, then CO2 emissions are reduced, but production costs increase and energy intensity increases
Solution Approach 1:
The patent makes hydrogen serve multiple functions: it acts as both the reducing agent for iron ore and the fuel for the fired heater. This multi-functionality maximizes the utilization of produced hydrogen, reducing the total amount of green hydrogen needed and thereby lowering production costs and energy intensity while maintaining low CO2 emissions
Solution Approach 2:
The system uses the produced hydrogen to heat itself by utilizing the CO2-rich tail gas as a carrier for the hydrogen fuel in the fired heater. This self-service approach reduces external energy inputs and production costs associated with green hydrogen generation
3Object-generated harmful factors
If single electric heating technology is used, then fossil fuel combustion is eliminated, but heating efficiency at high temperatures is insufficient and maintenance flexibility is reduced
Solution Approach 1:
The patent divides the heating process into two distinct stages: direct electric heating for initial temperature increase and fired heater for final high-temperature heating. This segmentation allows each heating method to operate in its optimal temperature range, achieving both high overall heating efficiency and the ability to reach required high temperatures without fossil fuel combustion in the direct electric heating section
Solution Approach 2:
The patent changes the heating method based on temperature parameters: using direct electric heating for lower temperature ranges and transitioning to fired heater for high temperature ranges. This parameter-based approach optimizes heating efficiency at each temperature stage while eliminating fossil fuel combustion from the electric heating portion
4Productivity
If direct reduced iron is produced and then transported to blast furnace, then iron ore reduction is achieved, but transportation costs increase and re-oxidation risk increases
Solution Approach 1:
The patent merges the iron ore reduction process with the blast furnace operation by injecting hot reducing gas directly into the blast furnace. This combination eliminates the separate DRI production and transportation steps, reducing transportation time and eliminating re-oxidation risks while maintaining efficient iron ore reduction through the integrated gas injection process
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 enhances the sustainability, efficiency, and availability of the DRI process by reducing carbon emissions, operational costs, and maintaining process continuity through flexible maintenance.
Implementation Method 1
subjecting the reducing gas to direct electric heating to obtain a first preheated reducing gas having a first temperature level
Implementation Method 2
the first preheated reducing gas is subjected to indirect electric heating to obtain a second preheated reducing gas having a second temperature level higher than the first temperature level
Implementation Method 3
hot hydrogen gas or syngas can be injected into a blast furnace to achieve reduction of iron ore directly in the blast furnace
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method and a process arrangement (100) for heating a process gas (1), in particular containing hydrogen and/or carbon monoxide, to a reaction temperature level. In the method (100) the reducing gas (1) is subjected to direct electric heating (10) to obtain a first preheated reducing gas (2) having a first temperature level, and the first preheated reducing gas (2) is subjected to indirect electric heating (20) to obtain a second preheated reducing gas (3) having a second temperature level higher than the first temperature level. The process arrangement (100) is configured to perform the method (100).