CFB Boiler Heat Exchanger Arrangement with Independent Chambers
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Solution Overview
Problem
Large circulating fluidized bed boilers face challenges in positioning and feeding devices due to unfavorable wall surface area to volume ratios, leading to space constraints and increased complexity in heat exchanger arrangements, which results in inefficient use of space and higher costs.
Innovation Solution
A novel heat exchanger arrangement for CFB boilers with a smaller, lighter lower heat exchange chamber that allows for closer positioning to the furnace wall, eliminating the need for a return channel from the upper to the lower chamber, and enabling separate support and temperature control for each chamber, reducing the need for bellows and simplifying the arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional heat exchanger arrangement with upper and lower chambers is used, then heat exchange functionality is provided, but the lower chamber requires a return channel from the upper chamber increasing structural complexity and space requirements
Solution Approach 1:
The patent extracts and eliminates the return channel from the upper heat exchange chamber to the lower chamber, simplifying the overall structure. The lower chamber is designed to receive hot solids directly from the furnace through a separate inlet channel, making the return channel unnecessary and reducing structural complexity while maintaining heat exchange functionality.
Solution Approach 2:
The heat exchanger arrangement is segmented into independent upper and lower chambers, each with separate inlet and outlet channels. The upper chamber receives solids from the separator and the lower chamber receives solids from the furnace, allowing independent operation and simplifying the connection between chambers.
2Volume of moving object
If the lower heat exchange chamber is made smaller and lighter, then equipment placement flexibility is improved and space constraints are reduced, but the chamber requires separate support and temperature control systems
Solution Approach 1:
The patent applies local quality by providing separate support structures and temperature control systems specifically for the lower heat exchange chamber, tailored to its reduced size and specific functional requirements. This localized approach allows the chamber to be smaller while maintaining necessary support and control capabilities.
3Area of stationary object
If heat exchangers are positioned closer to the furnace wall, then space utilization is improved, but positioning and support become more difficult
Solution Approach 1:
The patent positions the lower heat exchange chamber adjacent to the furnace wall in a different spatial arrangement, utilizing the available space more effectively. The chamber is supported by the furnace wall structure, allowing close positioning without compromising manufacturing or support requirements.
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 provides more flexibility in equipment placement, reduces space constraints, lowers construction costs, and improves operational efficiency by allowing for independent temperature control and reduced complexity in the heat exchanger setup.
Implementation Method 1
a first fluidized bed heat exchange chamber arranged downstream of the gas seal and having internal heat exchange surfaces, a second fluidized bed heat exchange chamber arranged adjacent to a lower sidewall of the furnace and having internal heat exchange surfaces
Implementation Method 2
a first lift channel, having a lower end connected to a bottom portion of the first fluidized bed heat exchange chamber
Data Source
AI summary
A circulating fluidized bed boiler includes a furnace for combusting solid carbonaceous fuel in a fast fluidized bed. A solids separator is adjacent to a sidewall of the furnace and separates solids entrained with exhaust gas discharged via an outlet channel. A gas seal conveys at least a portion of the separated solids to a first fluidized bed heat exchange chamber that is arranged downstream of the gas seal and has internal heat exchange surfaces. A first lift channel has a lower end connected to a bottom portion of the first fluidized bed heat exchange chamber and an upper end connected to an upper end of a first return channel for discharging solids from the first fluidized bed heat exchange chamber and taking the cooled solids to a lower portion of the furnace. A second fluidized bed heat exchange chamber is arranged adjacent to a lower sidewall of the furnace.