Direct Reduction Iron Coal Gasification Coke Oven Gas
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Solution Overview
Problem
The existing direct reduction (DR) process of iron using coke oven gas (COG) faces challenges such as energy loss due to tar and heavy hydrocarbons, sulfur contamination in the product, and inefficiencies in reforming methane, which limits the applicability of COG and requires additional capital investment and processing steps, making it economically unfeasible to scale up DR plants without significant capital expenditure.
Innovation Solution
Injecting COG directly into a coal gasification reactor, such as a fluidized bed gasifier, to generate reducing gas, allowing for optional tar and heavy hydrocarbon separation and sulfur removal, thereby eliminating the need for conventional reforming or partial oxidation processing and integrating COG with coal gasification to enhance energy efficiency and reduce capital costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If COG is used in a DR process, then reducing gas is provided, but tar and heavy hydrocarbons cause carbon deposits in ducts and heater tubes
Solution Approach 1:
The patent extracts and removes tar and heavy hydrocarbons from COG through a pretreatment facility before the gas is used in the DR process, preventing carbon deposits in ducts and heater tubes while maintaining the reducing gas supply
Solution Approach 2:
A pretreatment facility acts as an intermediary between COG and the DR process, treating the gas to remove harmful components before it enters the reduction system
2Object-affected harmful factors
If tar and heavy hydrocarbons are removed at a pretreatment facility, then carbon deposits are prevented, but energy is lost
Solution Approach 1:
The patent changes the parameters of tar and heavy hydrocarbon removal by using catalytic cracking to convert them into useful syngas components (CO and H2) rather than simply discarding them, thereby recovering energy while preventing carbon deposits
3Quantity of substance
If COG is reformed with a tubular reformer or auto-thermal reformer, then CH4 is converted to CO or H2, but sulfur affects the catalyst
Solution Approach 1:
The patent performs preliminary sulfur removal from COG before the gas enters the reformer, preventing sulfur from poisoning the catalyst while still enabling efficient CH4 conversion to CO and H2
Solution Approach 2:
A sulfur removal unit acts as an intermediary between COG and the reformer, protecting the catalyst from sulfur contamination
4Object-affected harmful factors
If a partial oxidation system is applied to COG, then tar and heavy hydrocarbons are dissociated, but product gas quality is reduced
Solution Approach 1:
The patent changes the oxidation parameters by using controlled catalytic oxidation instead of harsh partial oxidation, dissociating tar and heavy hydrocarbons while maintaining better product gas quality with higher reducibility
5Quantity of substance
If sulfur is not removed from COG, then sulfur compounds are absorbed by DRI product, but additional sulfur removal steps are required in steelmaking
Solution Approach 1:
The patent performs preliminary sulfur removal from COG before the gas contacts the DRI product in the shaft furnace, preventing sulfur absorption by the iron and eliminating the need for additional sulfur removal steps in steelmaking
6Quantity of substance
If COG is injected into a coal gasifier, then reducing gas is generated, but conventional technologies cannot process both coal and COG simultaneously
Solution Approach 1:
The patent modifies the coal gasifier to perform multiple functions: it can process both coal and COG simultaneously by adjusting operating parameters, making the system versatile enough to handle different feedstocks and optimize reducing gas production
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 enables the efficient utilization of COG energy, reduces sulfur contamination, and increases the energy efficiency of coal gasification, allowing for a more economical and scalable DR process by integrating COG and coal gasification systems, thus overcoming the limitations of conventional methods.
Implementation Method 1
generating a reducing gas in a coal gasifier using coal, oxygen, steam, and a first coke oven gas (COG) stream as inputs to the coal gasifier
Implementation Method 2
Injecting COG directly into a coal gasification reactor, such as a fluidized bed gasifier
Implementation Method 3
removing sulfur from the reducing gas prior to delivering the reducing gas to the shaft furnace
Implementation Method 4
heating the reducing gas prior to delivering the reducing gas to the shaft furnace
Data Source
AI summary
A method and apparatus for producing direct reduced iron (DRI), including: generating a reducing gas in a coal gasifier using coal, oxygen, steam, and a first coke oven gas (COG) stream as inputs to the coal gasifier; and delivering the reducing gas to a shaft furnace and exposing iron ore agglomerates to the reducing gas to form metallic iron agglomerates. The method further includes delivering a second COG stream directly to the shaft furnace.