Staged Pressurized Boilers for Efficient CO2 Capture
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Solution Overview
Problem
Conventional oxy-combustion systems for power generation are costly and inefficient due to the need for oxygen production and CO2 compression, and they suffer from power plant efficiency losses from flue gas recycling, which is used to prevent heat exchanger damage from excess gas temperatures.
Innovation Solution
A series of pressurized boilers with staged fuel delivery and oxidizer use, where oxygen is introduced in the first boiler and flue gas from previous boilers is used as oxidizer in subsequent boilers, along with a direct contact cooler for SO2 and NOx removal, reducing the need for flue gas recycling and enhancing heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flue gas is recycled to cool the heat exchanger, then the heat exchanger is protected from damage due to excess gas temperatures, but power plant efficiency is reduced
Solution Approach 1:
The patent introduces a flow distributor as an intermediary device that mediates between the hot flue gas and the heat exchanger tubes. The flow distributor creates a controlled flow pattern that distributes the thermal energy uniformly across the heat exchanger surface, preventing localized overheating and tube damage while allowing higher overall gas temperatures to be utilized for power generation, thereby eliminating the need for flue gas recycling for cooling purposes.
Solution Approach 2:
The patent changes the flow distribution parameters of the flue gas through the heat exchanger by using a flow distributor. This creates a more uniform velocity and temperature distribution across the heat transfer surface, enabling the system to operate at higher gas temperatures without exceeding safe operating conditions in any localized area, thus improving efficiency while maintaining reliability.
2Object-generated harmful factors
If conventional oxy-combustion is used at atmospheric pressure, then CO2 emissions are reduced, but operating costs increase due to oxygen production and CO2 compression requirements
Solution Approach 1:
The patent changes the pressure parameter of the combustion process from atmospheric pressure to elevated pressure (e.g., 10-50 bar). This pressure increase enables the system to achieve both CO2 emission reduction and eliminates the need for complex oxygen production and CO2 compression equipment, as the high pressure facilitates direct CO2 capture and utilization without additional compression stages.
3Loss of energy
If flue gas temperature is increased to improve heat transfer, then power plant efficiency increases, but heat exchanger tubes are damaged due to excess temperatures
Solution Approach 1:
The patent applies local quality by creating a non-uniform flow distribution pattern through the flow distributor. The distributor ensures that different regions of the heat exchanger receive appropriately distributed flue gas flow, preventing localized hot spots and tube overheating while maintaining high overall heat transfer efficiency. This local optimization allows the system to operate at higher temperatures without compromising tube integrity.
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 reduces operating costs, increases power plant efficiency, and allows for effective capture and purification of CO2, while minimizing equipment size and heat loss, and enables the use of low-rank fuels by maintaining controlled heat transfer rates and high CO2 concentrations.
Implementation Method 1
with a ratio of circular momentum to axial momentum of less than about 0.2
Implementation Method 2
The tubes in the heat exchanger carrying the working fluid are separated from the burning fuel so the working fluid is not radiantly heated by the flame
Implementation Method 3
heating a working fluid, such as water to produce steam
Implementation Method 4
along with a direct contact cooler for SO2 and NOx removal
Data Source
AI summary
A boiler system having a series of boilers. Each boiler includes a shell having an upstream end, a downstream end, and a hollow interior. The boilers also have an oxidizer inlet entering the hollow interior adjacent the upstream end of the shell and a fuel nozzle positioned adjacent the upstream end of the shell for introducing fuel into the hollow interior of the shell. Each boiler includes a flue duct connected to the shell adjacent the downstream end for transporting flue gas from the hollow interior. Oxygen is delivered to the oxidizer inlet of the first boiler in the series. Flue gas from the immediately preceding boiler in the series is delivered through the oxidizer inlet of each boiler subsequent to the first boiler in the series.