Fluid Sand Falling Circulating Fluidized Bed Boiler with Multiple Risers
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Solution Overview
Problem
Conventional circulating fluidized bed boilers face challenges with rapid erosion and corrosion of water tubes, reduced combustion efficiency, and inflexible output control due to high fluid sand flow rates, leading to increased costs and space inefficiency.
Innovation Solution
A fluid sand falling type circulating fluidized bed boiler with multiple risers and a relay section, where fluid sand flows down in the boiler section and up in the riser section, with individually controlled oxidizer injection to manage flow rates and combustion, and includes multiple water tube sections and cyclone sections for efficient heat exchange and particle management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow rate of fluid sand is maintained at 4 to 5 m/s to continuously circulate the fluid sand, then the fluid sand circulation is continuous, but the water tube is corroded and eroded by the fluid sand rapidly transferred therein
Solution Approach 1:
The riser is divided into multiple segments with water tubes positioned at different heights and locations. This segmentation allows the system to maintain high fluid sand flow rates for continuous circulation while distributing the erosive impact across multiple tube positions, preventing concentrated damage to any single tube location.
Solution Approach 2:
Water tubes are arranged not only on the inner wall surface but also extended into the internal space of the riser at various heights. This three-dimensional arrangement moves water tubes away from the direct path of high-velocity fluid sand, reducing erosion while maintaining circulation efficiency.
2Productivity
If the flow rate of fluid sand is maintained at 4 to 5 m/s to continuously circulate the fluid sand, then the fluid sand circulation is continuous, but the time for which fuel, additives, etc. stay in the conventional circulating fluidized bed boiler is shortened, resulting in deterioration of combustion efficiency, desulfurization efficiency, and denitrification efficiency
Solution Approach 1:
The riser is divided into multiple segments with different flow characteristics. This allows zones with longer residence times for combustion reactions while maintaining overall high circulation rates, enabling both continuous fluid sand circulation and adequate fuel reaction time.
Solution Approach 2:
The system dynamically adjusts oxidizer injection rates and fluid sand flow rates in different riser zones to optimize both circulation continuity and fuel residence time. Variable speed control of fluid sand circulation enables adaptation between high-throughput mode and extended-combustion mode.
3Productivity
If a large amount of gas is used to circulate fluid sand in the conventional circulating fluidized bed boiler, then the fluid sand circulation is maintained, but it is difficult to flexibly respond to the load variation of the boiler
Solution Approach 1:
The system incorporates variable speed control for fluid sand circulation and adjustable oxidizer injection rates, enabling dynamic adaptation to different load conditions. Multiple risers with independent control allow flexible redistribution of fluid sand flow to match varying power demands.
Solution Approach 2:
Multiple independently controllable risers allow selective operation and load distribution. Each riser can be adjusted or operated independently, providing granular control over overall system output and enabling flexible response to load variations.
4Use of energy by stationary object
If the water tube is mainly installed on the inner wall surface of the riser in the conventional circulating fluidized bed boiler, then the water tube is positioned for heat exchange, but the entire equipment is very large, making it difficult to efficiently utilize space
Solution Approach 1:
Water tubes are positioned in the internal space of the riser at various heights and radial positions, not just on the inner wall surface. This three-dimensional arrangement increases heat exchange surface area within the same riser volume, improving heat transfer efficiency without increasing overall equipment footprint.
Solution Approach 2:
Water tubes are nested within the riser structure, utilizing the internal space efficiently. Multiple tubes are arranged concentrically and at different elevations, maximizing heat exchange surface area while minimizing the external dimensions of the boiler equipment.
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
Prevents erosion and corrosion of water tubes, enhances combustion efficiency, and allows flexible output control, reducing equipment size and operational costs while improving desulfurization and denitrification efficiency.
Implementation Method 1
fuel is injected from the top of the boiler section and burned while flowing down therein
Implementation Method 2
the fuel and fluid sand supplied from the boiler section are introduced from the bottom of the riser section and flow up
Implementation Method 3
a first cyclone section provided between the riser section and the relay section
Data Source
AI summary
Disclosed herein are a fluid sand falling type circulating fluidized bed boiler with a plurality of risers for preventing erosion and corrosion of water tubes and increasing combustion efficiency, and a method of operating the same. The fluid sand falling type circulating fluidized bed boiler with a plurality of risers includes a boiler section into which fuel and oxidizer are injected, a riser section connected to the boiler section so that the fuel and fluid sand supplied from the boiler section are introduced from the bottom of the riser section and flow up, and a relay section provided on the boiler section to supply the fluid sand having passed through the riser section to the boiler section, wherein the fuel is injected from the top of the boiler section and burned while flowing down therein.