Oxygen-Fired Steam Generator Transport Reactor
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Solution Overview
Problem
Steam generators, particularly coal-fired ones, face challenges with harmful emissions and high costs due to significant gas recirculation needed for heat transfer processes, which increases complexity and auxiliary power requirements.
Innovation Solution
A steam generator design utilizing a transport reactor with a substantially pure oxygen feed stream to maintain flow velocity, separating flue gas into end and recycled products, and using a moving or fluidized bed heat exchanger with a bypass to optimize heat transfer and reduce gas recirculation, allowing only pure oxygen to be introduced at full load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If significant gas recirculation is used to maintain mass flow through the steam generator, then heat transfer processes are supported, but device complexity and auxiliary power requirements increase
Solution Approach 1:
The patent extracts nitrogen from the combustion process by using pure oxygen instead of air, eliminating the need for gas recirculation that was previously required to maintain furnace velocities. This removes the complex recirculation system while maintaining heat transfer effectiveness through the transport reactor design.
Solution Approach 2:
The patent changes the combustion parameter from air-based combustion to pure oxygen combustion, which fundamentally alters the gas flow characteristics and eliminates the need for recirculation. This parameter change transforms the system from requiring complex recirculation to operating with simplified direct flow.
2Temperature
If substantial gas recirculation is used to maintain furnace and convective surface velocities, then heat transfer is maintained, but auxiliary power requirements increase
Solution Approach 1:
The patent removes nitrogen from the system by using pure oxygen combustion, which eliminates the bulk of the gas that would otherwise require recirculation. This extraction of the problematic component (nitrogen) removes the need for high-power recirculation fans while maintaining necessary flow velocities through the transport reactor.
Solution Approach 2:
The transport reactor design allows the combustion process itself to generate sufficient flow velocities without external recirculation assistance. The system serves itself by using the combustion products to maintain the necessary flow through the reactor, eliminating the need for auxiliary power-consuming recirculation systems.
3Temperature
If furnace area is used to control heat transfer in pulverized coal steam generators, then heat transfer control is achieved, but gas recirculation requirements increase
Solution Approach 1:
The patent extracts nitrogen from air and replaces it with pure oxygen, which fundamentally changes the combustion gas properties. This allows heat transfer control to be achieved through the transport reactor design itself rather than requiring large furnace areas combined with complex recirculation systems.
Solution Approach 2:
The patent changes from air-based to pure oxygen-based combustion, which alters the thermal and flow characteristics of the combustion process. This parameter change enables heat transfer control through the transport reactor mechanism rather than through furnace area and recirculation rate adjustments.
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 design significantly reduces the combustor furnace area by over 80% compared to air-fired systems, eliminates the need for gas recirculation, and enhances heat transfer efficiency while maintaining high flow velocities and temperatures.
Implementation Method 1
the fuel and substantially pure oxygen are combusted to generate flue gas having ash and other hot solids forming a part thereof
Implementation Method 2
Heat from the hot flue gas is transferred to a working fluid such as, but not limited to, water, water vapor or steam, forming part of the heat exchanger
Implementation Method 3
the separator is a cyclone and the transport reactor operates at a flow rate of between about 30 ft/sec. to about 50 ft/sec.
Data Source
AI summary
In a method for operating a steam generator, a transport reactor is provided. Only a substantially pure oxygen feed stream is introduced into the transport reactor in an amount sufficient to maintain the transport reactor at or above a specific system load. The specific load is the system load when only the substantially pure oxygen feed stream is provided to the transport reactor at a minimum flow velocity for operating the transport reactor. A fuel is combusted in the presence of the substantially pure oxygen feed stream to produce a flue gas, which contains solid material. The solid material is separated from the flue gas and passed to a heat exchanger. The heat exchange may be one of a moving bed heat exchanger or a fluidized bed heat exchanger. The solid material is directed to the transport reactor to contribute to the combustion process.