Fluidized Bed Combustion Partitions for Ash Sintering Control
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Solution Overview
Problem
Conventional fluidized bed incinerators face issues with low-melting ashes forming sintered lumps and deposits on the combustion chamber walls, leading to uncontrolled combustion and operational challenges, particularly with fuels like agricultural products and chemical sludge, which cannot be effectively managed through constant cleaning due to efficiency losses and corrosion concerns.
Innovation Solution
The incinerator design includes partitions separating the boiler's free space from the post-combustion chamber, with an ash outlet, and membrane wall construction to prevent ash melting and sintering, ensuring high temperatures in the post-combustion chamber without affecting the fluidized bed, and utilizing sub-stoichiometric combustion and specific partition arrangements to manage ash and flue gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant cleaning of the combustion chamber walls is implemented to prevent deposit growth, then deposits can be kept below critical size, but cleaning devices cannot reach every surface and corner, and constant cleaning causes efficiency loss and wall corrosion
Solution Approach 1:
The combustion chamber is divided into multiple zones using partition walls, creating separate combustion regions with different oxygen conditions. This segmentation allows different combustion processes to occur simultaneously without interfering with each other, solving the problem of uncontrolled combustion caused by ash deposits.
Solution Approach 2:
Partition walls act as intermediary structures that physically separate the combustion zones and prevent direct contact between high-temperature regions and areas prone to ash deposition. These partitions serve as mediators that control ash flow and protect critical surfaces while maintaining overall combustion efficiency.
2Use of energy by moving object
If high temperatures are maintained in the incineration plant for effective combustion, then energy efficiency is improved, but low-melting ashes form sintered lumps and deposits that impede fluidization and cause uncontrolled combustion
Solution Approach 1:
Different temperature conditions are created in different locations within the combustion chamber. The first combustion zone maintains high temperatures for efficient combustion, while the second zone provides a transition area. Partition walls create local quality variations that prevent uniform ash melting throughout the entire chamber.
Solution Approach 2:
The combustion chamber is segmented into distinct zones with different thermal conditions. This segmentation allows the system to maintain high overall temperatures for energy efficiency while creating localized cooler regions that prevent widespread ash sintering and maintain fluidization control.
3Object-affected harmful factors
If the superheater is designed to allow low-melting ashes to form a protective layer and then drip off, then wall protection is achieved, but liquid ashes drip into the fluidized bed causing sintering and uncontrolled combustion
Solution Approach 1:
The harmful liquid ash that would normally drip into the fluidized bed is extracted and redirected through the partition wall structure. The partition walls intercept and channel the liquid ash flow away from the fluidized bed, preventing sintering while still allowing the superheater to utilize the protective ash layer function.
4Reliability
If staged combustion and suitable bed materials are used to prevent ash sintering in the fluidized bed, then fluidization is maintained, but deposits still form on combustion chamber walls and detach to fall into the fluidized bed
Solution Approach 1:
Partition walls serve as intermediary structures that intercept wall deposits before they can detach and fall into the fluidized bed. These partitions create a physical barrier that captures falling ash and redirects it to appropriate discharge points, protecting the fluidization process from deposit contamination.
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 allows for the direct feeding of fuels with low-melting ashes into the fluidized bed, preventing sintering and uncontrolled combustion by ensuring complete combustion in the post-combustion chamber and preventing ash from falling into the fluidized bed, thus maintaining operational efficiency and reducing maintenance costs.
Implementation Method 1
Fluidized bed furnaces (fluidized bed furnaces) are often used for this purpose. Fluidized bed incinerators have the advantage of being able to burn a wide range of fuels due to the high storage capacity of the bed material. In addition, the excellent mixing in a fluidized bed allows very homogeneous combustion
Implementation Method 2
Sub-stoichiometric combustion conditions prevail in the free space and in the fluidized bed; in the post-combustion chamber, the unburned gases and solids are completely burned
Implementation Method 3
When incinerated, many waste materials form ashes
Implementation Method 4
The partition walls can be used to achieve a spatial and energy-related separation, which enables very high temperatures in the afterburner chamber without affecting the combustion in the fluidized bed. Furthermore, particles that fall on the partitions can be discharged from the boiler in a favorable manner
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a combustion plant for burning fuels with low-melting-point ash, comprising a boiler (1) with a fluidized bed (5). This plant is characterized in that the free space (11) of the boiler (1) above the fluidized bed (5) is separated from the afterburner chamber (13) by partitions (14, 14', 15), wherein the afterburner chamber (13) can be arranged above the free space (11) and wherein the partitions (14, 14', 15) can be arranged offset. This achieves a spatial and energy-related separation that enables very high temperatures in the afterburner chamber (13) without affecting the combustion in the fluidized bed (5).