Oxycombustion Systems with Integrated Ammonia Synthesis
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Solution Overview
Problem
Current combustion systems face challenges in achieving energy efficiency while reducing CO2 and pollutant emissions, particularly in the formation of NOx and SOx pollutants during fossil fuel combustion.
Innovation Solution
The implementation of oxycombustion systems with thermally integrated ammonia synthesis, which involves an air separation unit to produce oxygen and nitrogen streams, an ammonia synthesis unit to form ammonia from hydrogen and nitrogen, and an oxycombustion reactor to combust fuels in pure oxygen, along with thermal integrations to optimize energy use and reduce emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional combustion processes are used with air, then nitrogen is present in the flue gases, but this leads to formation of NOx pollutants and reduces energy efficiency
Solution Approach 1:
The invention extracts nitrogen from the combustion process by using pure oxygen instead of air, thereby eliminating the source of NOx formation. The air separation unit separates nitrogen from oxygen, and only pure oxygen is supplied to the combustor, removing the harmful nitrogen component that would otherwise form NOx pollutants during combustion.
Solution Approach 2:
The invention merges the air separation process with the combustion process by integrating the oxygen production system directly with the combustor. The nitrogen-rich stream from air separation is redirected to ammonia synthesis, while the pure oxygen stream is used for combustion, creating a combined system that simultaneously achieves pollutant reduction and energy efficiency.
2Object-affected harmful factors
If ammonia injection is used for post-combustion SOx removal, then SOx emissions are reduced, but external ammonia must be purchased at energy cost and monetary cost
Solution Approach 1:
The system produces its own ammonia through on-site synthesis using nitrogen from the air separation process and hydrogen from the fuel feed. This self-generated ammonia is then used for SOx removal, eliminating the need to purchase external ammonia and the associated energy and monetary costs.
Solution Approach 2:
Instead of discarding the nitrogen stream from air separation, the invention recovers and utilizes it as a feedstock for ammonia synthesis. This recovered nitrogen is combined with hydrogen to produce ammonia, which is then used for flue gas desulfurization, transforming a waste stream into a valuable reagent.
3Object-affected harmful factors
If ammonia is purchased from external sources for emissions control, then pollutant removal is achieved, but both energy cost and monetary cost increase
Solution Approach 1:
The system generates its own ammonia through integrated synthesis units that use nitrogen from air separation and hydrogen from the fuel feed. This self-produced ammonia replaces purchased ammonia for emissions control, eliminating external dependencies and associated costs.
Solution Approach 2:
The nitrogen stream serves multiple functions: it is separated from air, used as feedstock for ammonia synthesis, and the resulting ammonia is used for SOx and NOx removal. This multi-functional use of nitrogen eliminates the need for separate ammonia procurement while achieving comprehensive emissions control.
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, reduces harmful emissions of CO2, NOx, and SOx, and eliminates the need for external ammonia or urea by integrating ammonia synthesis with oxycombustion, thereby lowering the overall carbon footprint and operational costs.
Implementation Method 1
an air separation unit that separates an air feed stream into an oxygen stream and a nitrogen stream
Implementation Method 2
an ammonia synthesis unit that synthesizes ammonia from a hydrogen feed stream and the nitrogen stream from the air separation unit
Implementation Method 3
an ammonia separation unit that condenses the crude ammonia stream formed in the ammonia synthesis unit and separates the ammonia from any unreacted nitrogen and hydrogen
Implementation Method 4
an oxycombustion reactor that combusts a fuel from a fuel feed stream in the presence of the oxygen stream from the air separation unit to generate combustion heat
Implementation Method 5
at least one thermal integration is present in the oxycombustion systems. The at least one thermal integration may be chosen from a reactor thermal linkage of the ammonia synthesis unit with the oxycombustion reactor
Data Source
AI summary
Oxycombustion systems and oxycombustion methods include thermally integrated ammonia synthesis. The oxycombustion systems may include an air separation unit that separates air into an oxygen stream and a nitrogen stream. An ammonia synthesis unit synthesizes ammonia from a hydrogen feed and the nitrogen stream to form a crude ammonia stream. An ammonia separation unit condenses the crude ammonia stream and separates the ammonia from any unreacted nitrogen and hydrogen to form a purified ammonia stream. An oxycombustion reactor combusts a fuel from a fuel feed stream in the presence of the oxygen stream from the air separation unit to generate hot water or steam. At least one thermal integration may be present in the oxycombustion systems and may be chosen from a reactor thermal linkage of the ammonia synthesis unit with the oxycombustion reactor, a separator thermal linkage of the air separation unit with the ammonia separation unit, or both.