Direct Reduced Iron Gas Treatment via Adsorbent Bed
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Solution Overview
Problem
Existing processes for producing direct reduced iron (DRI) using coke oven gas are limited by high costs associated with cleaning and conditioning due to sulfur compounds and BTX, which contaminate DRI and cause equipment issues, restricting the amount of coke oven gas that can be treated and leading to inefficient steel production.
Innovation Solution
A method and apparatus that utilize a vertical shaft reactor with an adsorbent material outside the reduction zone to adsorb sulfur compounds and BTX from coke oven gas, and a regenerative heater system to crack heavy hydrocarbons, allowing the treated gas to be reused as a reducing agent, thereby minimizing contamination and operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coke oven gas is used directly as reducing gas in DRI production, then production costs are reduced and gas utilization is improved, but sulfur compounds and BTX contaminate the DRI product and cause equipment damage
Solution Approach 1:
The patent applies preliminary action by treating the coke oven gas with an iron ore bed before it enters the reduction zone. The gas passes through a bed of iron ore particles that adsorb sulfur compounds and BTX beforehand, preventing contamination of the DRI product while allowing the gas to be used as reducing agent.
Solution Approach 2:
The iron ore bed acts as an intermediary between the coke oven gas and the DRI production process. It selectively removes harmful substances (sulfur compounds and BTX) from the gas stream while allowing the reducing components (CO and H2) to pass through and participate in the reduction reaction.
2Manufacturing precision
If extensive cleaning processes are applied to remove sulfur compounds and BTX from coke oven gas, then DRI product quality is improved, but operational costs increase significantly
Solution Approach 1:
The iron ore bed performs self-service by simultaneously serving dual functions: it acts as both the reducing agent source (providing CO and H2 for reduction) and the purification medium (removing sulfur compounds and BTX). This eliminates the need for separate expensive cleaning equipment and operations.
Solution Approach 2:
The iron ore bed is designed to perform multiple functions within a single unit: it serves as the reducing gas source, the purification medium, and the heat transfer medium. This multi-functionality reduces equipment complexity and operational costs while maintaining high DRI product quality.
3Device complexity
If heavy hydrocarbons in coke oven gas are not treated, then equipment complexity is reduced, but hydrocarbon deposits cause pipe plugging and equipment damage
Solution Approach 1:
The patent utilizes parameter changes by heating the coke oven gas to high temperatures (above 700°C) during its passage through the iron ore bed. This temperature change causes heavy hydrocarbons to crack into lighter compounds that do not form deposits, thereby protecting equipment without requiring additional treatment systems.
Solution Approach 2:
The heavy hydrocarbons, which would normally cause plugging and equipment damage, are converted into beneficial lighter compounds through thermal cracking. The harmful deposits are transformed into useful lighter hydrocarbons that can participate in the reduction process or be easily removed.
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 effective and cost-efficient production of high-temperature DRI with reduced sulfur contamination, allowing for increased coke oven gas utilization and improved steel production efficiency by eliminating the need for extensive cleaning processes and reducing equipment damage from hydrocarbon deposits.
Implementation Method 1
caused to flow through a bed of particles of an adsorbent material... whereby sulfur compounds and BTX are adsorbed by said adsorbent material
Implementation Method 2
whereby sulfur compounds and BTX are adsorbed by said adsorbent material and the heavy hydrocarbons are cracked into lighter compounds by contact with said adsorbent material at high temperature
Implementation Method 3
chemical reduction of iron oxides is carried out by such reducing gas... the reaction of particulate iron ores, mainly iron oxides... with a reducing gas mainly composed of hydrogen and carbon monoxide
Data Source
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AI summary
A process for producing direct reduced iron (DRI) from iron ores and reducing the cost and energy requirements of steelmaking, utilizing a gas produced from fossil fuels, containing sulfur compounds and BTX, wherein said gas is heated in a gas heater, wherein heat is transferred from a previously-heated solid material to the gas. The hot gas is caused to flow through a bed of DRI particles, iron oxides or equivalent material, outside of the reduction reactor, where said material adsorbs sulfur compounds and destroying the BTX. The gas resulting from this treatment, free from sulfur compounds and BTX, is combined with a reducing gas stream withdrawn from the reduction reactor after H20 and C02 have at least partially been removed for regenerating its reducing potential with or without undergoing a previous cleaning treatment.