Ammonia-Based Metal Oxide Reduction with Top Gas Recycling
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Solution Overview
Problem
The challenge lies in efficiently reducing metal oxide-containing materials using ammonia-derived reducing gases while managing energy supply and utilizing the nitrogen byproduct in industrial processes, as existing methods face issues with energy conservation and resource efficiency.
Innovation Solution
The method involves using reducing gases obtained from ammonia, where a subset of the top gas from the reduction reactor is recycled and processed to prepare the reducing gas, allowing for the utilization of residual reducing power and heat content, and nitrogen is used as a heat transfer medium to conserve energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If ammonia is used as a reducing agent to replace natural gas, then CO2 emissions are reduced, but significant amounts of nitrogen are produced as a byproduct that need to be managed
Solution Approach 1:
The patent converts the harmful nitrogen byproduct from ammonia decomposition into a beneficial heat transfer medium. The nitrogen is used to transport heat from the reduction zone to the decomposition zone, enabling endothermic ammonia decomposition without external energy input and improving overall process efficiency while maintaining low CO2 emissions
2Productivity
If top gas is discharged from the reduction reactor, then the reduction process continues, but residual reducing power and heat content are wasted
Solution Approach 1:
The patent implements a feedback loop where top gas containing residual reducing power and heat is recirculated back to the reduction reactor. This feedback mechanism allows the top gas to participate in further reduction reactions and transfer its thermal energy to incoming fresh reducing gas, thereby eliminating waste and improving energy efficiency
Solution Approach 2:
The patent ensures continuous useful action by recirculating top gas back into the reduction process. The residual reducing power and heat in the top gas continue to contribute to reduction reactions and thermal energy transfer, maintaining productive action throughout the system rather than allowing energy dissipation
3Object-generated harmful factors
If hydrogen is used as a reducing gas to reduce CO2 emissions, then environmental impact is reduced, but storage and transport become problematic due to physical properties
Solution Approach 1:
The patent uses ammonia as an intermediary carrier substance that solves the storage and transport problems of hydrogen. Ammonia can be easily stored and transported in liquid form, and when decomposed, it releases hydrogen for reduction reactions. This intermediary approach maintains the environmental benefits of hydrogen-based reduction while eliminating its logistical challenges
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 energy efficiency and resource conservation by leveraging the residual reducing power and heat in the top gas, reducing the need for external energy input and minimizing the use of expensive reducing agents like hydrogen and hydrocarbons.
Implementation Method 1
Ammonia can be split into nitrogen and hydrogen 2 NH 3 → N 2 + 3 H 2
Implementation Method 2
Hydrogen H 2 can react as a reducing agent with the metal oxides, for example iron oxides: 3 Fe 2 O 3 + H 2 → 2 Fe 3 O 4 + H 2 O
Implementation Method 3
Ammonia can also act as a reducing agent itself: 9 Fe 2 O 3 + 2 NH 3 → 6 Fe 3 O 4 + N 2 + 3 H 2 O
Implementation Method 4
Such reduction reactions to produce metallic iron Fe with hydrogen H 2 and with ammonia NH 3, as well as the splitting of ammonia into nitrogen N 2 and hydrogen H 2, are endothermic
Data Source
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AI summary
A process for the reduction of metal oxide-containing material (2), wherein reducing gas obtained using ammonia (NH3) is employed, and wherein the reducing gas is fed to a reduction reactor (2) containing the metal oxide-containing material, and a top gas is discharged from the reduction reactor. At least a portion of the top gas is used as a component in the preparation of the reducing gas, optionally after processing of the top gas. A device (1) for the reduction of metal oxide-containing material (3) comprises a reduction reactor (2), a top gas discharge (4) for discharge of top gas from the reduction reactor (2), at least one supply line for an ammonia contribution (7), a preparation plant (6) for the preparation of reducing gas, into which at least one supply line for an ammonia contribution (7) opens, and a feed line (8) for supplying reducing gas and/or a precursor of the reducing gas to the reduction reactor (2).The top gas outlet (5) leads into the preparation plant (6).