Direct Reduction Vent Gas Reuse for Energy Recovery

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Solution Overview

Problem

The existing direct reduction methods for metal oxides result in dust-laden vent gas, which is difficult to use and requires extensive dilution with air for de-dusting, leading to energy-intensive processes and high NOx emissions.

Innovation Solution

De-dusted vent gas is reused as an energy source in the combustion process for producing reduction gas through catalytic reforming or as a component of furnace combustion gas, reducing the need for additional energy inputs and minimizing NOx formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If vent gas is diluted with air for de-dusting, then dust content is reduced, but energy consumption increases and NOx emissions increase

Engineering Contradiction:

Improvedust contentVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent converts the harmful dust-laden vent gas into a beneficial energy source by using it as fuel for combustion in the reformer. Instead of diluting with air to remove dust, the vent gas is burned to provide heat for the endothermic reforming process, thereby eliminating the need for air dilution and associated energy consumption and NOx emissions.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the parameter of vent gas utilization from passive dilution with air to active combustion as fuel. By changing the functional parameter of the vent gas from waste product to energy source, the system eliminates the need for energy-intensive de-dusting processes.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If vent gas is diluted with air for de-dusting, then dust content is reduced, but NOx emissions increase

Engineering Contradiction:

Improvedust contentVSAvoidNOx emissions

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful vent gas into a beneficial fuel source that eliminates the need for air dilution. By burning the vent gas in the reformer combustion process, the system avoids the formation of NOx that would occur during air dilution, while still effectively managing the dust content through combustion.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If seal gas is used to flush the product discharge device, then product is protected from reoxidation, but dust-laden vent gas is generated

Engineering Contradiction:

Improveprotection from reoxidationVSAvoiddust-laden vent gas

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent recovers the vent gas that would otherwise be discarded as waste. Instead of simply venting the dust-laden gas, it is captured and used as fuel for the reformer combustion process, thereby recovering energy from what would be waste and eliminating the need for further processing.

Inventive Principle:

Principle #34Discarding and recovering

4Manufacturing precision

If de-dusting is performed on vent gas, then gas purity is improved, but process complexity increases

Engineering Contradiction:

Improvegas purityVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent converts the complex de-dusting problem into a simple combustion process. Instead of implementing complex filtration or dilution systems to remove dust, the system simply burns the vent gas, which naturally removes dust through combustion and ash formation, thereby simplifying the overall process.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 significantly reduces the volume of gas to be handled, eliminates the need for air dilution, and decreases NOx emissions, making the process more energy-efficient and environmentally friendly.

Implementation Method 1

reduction gas by catalytic reforming of gaseous hydrocarbons

Methodology Applied

Scientific EffectCatalytic reforming: Catalysis

Implementation Method 2

heat for the endothermic reforming processes which proceed during the reforming is provided at least in part by combustion of a reformer combustion gas

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 3

at least part of the de-dusted vent gas is used as an energy source during combustion for producing the reduction gas

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 4

contact with hot reduction gas in a reduction unit

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS11773459B2Method for direct reduction using vent gas

Publication Date: 2023.10.03 PRIMETALS TECH AUSTRIA GMBH

AI summary

A method for the direct reduction of feedstock, containing metal-oxide, to form metallic material, by contact with hot reduction gas in a reduction assembly (1): the product of the direct reduction process is discharged from the reduction assembly by a product discharge apparatus, which is flushed with seal gas, drawn off from the vent gas and subsequently dedusted. At least one portion of the dedusted vent gas is used as a combustion energy source during the production of the reduction gas, and/or as a component of a furnace fuel gas during a combustion process for heating the reduction gas, and/or as a component of the reduction gas. Apparatus for carrying out the method is disclosed.