Circulating Mass Reactor Segmented Combustion and Adiabatic Cooling
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Solution Overview
Problem
Circulating fluidized-bed reactors face challenges with poor horizontal mixing of gases, temperature control inconsistencies, and corrosion issues due to direct heat transfer surfaces, limiting fuel flexibility and increasing maintenance costs.
Innovation Solution
The reactor is designed with separate lower and upper combustion chambers, where ignition and mixing occur in the lower chamber and completion of combustion in the upper chamber, with adiabatic cooling using fluidized material outside the chambers, eliminating the need for heat transfer surfaces and allowing for flexible fuel use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat transfer surfaces are placed directly in the combustion chamber for cooling, then temperature control is improved, but corrosion increases and fuel flexibility decreases
Solution Approach 1:
The combustion chamber is divided into two separate chambers: a lower combustion chamber for ignition and mixing, and an upper combustion chamber for completion of combustion. This segmentation allows each chamber to be optimized for its specific function while avoiding the placement of heat transfer surfaces in the high-corrosion environment, thus resolving the contradiction between temperature control and corrosion resistance.
Solution Approach 2:
Fluidized material acts as an intermediary cooling medium that circulates between the combustion chambers and heat exchangers located outside the chambers. This intermediary approach allows heat transfer without direct contact between combustion gases and heat transfer surfaces, eliminating corrosion while maintaining effective temperature control.
2Productivity
If fluidized material is circulated at high velocity for efficient heat transfer, then productivity is improved, but device complexity increases due to additional cooling systems
Solution Approach 1:
The fluidized material circulation system serves multiple functions simultaneously: it acts as a cooling medium for the combustion chambers, a heat transfer medium to external heat exchangers, and a mixing medium within the combustion chambers. This multi-functionality achieves efficient heat transfer without requiring separate cooling systems, thus improving productivity while avoiding increased device complexity.
Solution Approach 2:
The fluidized material itself serves as the cooling medium, utilizing its own circulation and heat capacity to absorb heat from the combustion chambers and transfer it to external heat exchangers. This self-service approach eliminates the need for external cooling systems, maintaining high heat transfer efficiency while avoiding additional complexity.
3Temperature
If separate lower and upper combustion chambers are implemented for optimized combustion, then temperature control is improved, but device complexity increases
Solution Approach 1:
The combustion process is segmented into two distinct chambers with specific functions: the lower chamber handles ignition and mixing, while the upper chamber completes combustion. This segmentation improves temperature control by optimizing each zone for its specific purpose. The modular design allows independent optimization of each chamber while maintaining overall system coherence, thus improving performance without excessive complexity.
Solution Approach 2:
The upper combustion chamber is positioned directly above the lower combustion chamber, creating a nested vertical arrangement. This nesting approach allows compact integration of both chambers within a limited vertical space, reducing the overall footprint and structural complexity while maintaining the benefits of separate combustion zones for improved temperature control.
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 enhances fuel flexibility, reduces corrosion, and results in a more compact, cost-effective reactor with improved temperature control and reduced maintenance, maintaining efficient fluidized material circulation even at part loads.
Implementation Method 1
a part of the heat energy contained by the fluidized material passing therethrough is transferred to the heat transfer liquid circulating in the circulating mass reactor by means of heat exchangers fitted in the return conduits
Implementation Method 2
at least a part of the heat contained by the flue gases formed in the circulating mass reactor is transferred to the fluidized material arranged to circulate in the circulating mass reactor
Implementation Method 3
combustion air is supplied from the lower part of the furnace through a sand bed formed on the bottom of the combustion chamber. The fuel supplied to the furnace mixes with the help of the combustion air with the sand bed acting in an bubbling manner, where it dries and ignites
Data Source
Figure 1~4
AI summary
The object of the invention is a method for enhancing the operation of a circulating mass reactor (1), which circulating mass reactor (1) comprises a fluidized-bed chamber (8) provided with a fluidized bed (108), means for separating fluidized material (80) from the flue gases, and a return conduit system (15, 16, 19) including at least one cooled return conduit (15, 16). In the method, for the combustion of fuel taking place in the circulation mass reactor (1) is provided a lower combustion chamber (89), which comprises a fluidized-bed chamber (8), and an upper combustion chamber (11) and a flow conduit (10) connecting them. The flow conduit (10), the means for separating the fluidized material (80) from the fuel gases and the return conduit system (15, 16, 19) are arranged to be located essentially between the lower combustion chamber (89) and the upper combustion chamber (11). The lower combustion chamber (89) and the upper combustion chamber (11) are dimensioned in such a way that the combustion of the fuel can be essentially completed before the discharge of the flue gases from the combustion chamber (11), whereupon the average delay time of the flue gases in the upper combustion chamber is most preferably 0.3-3.0 seconds. The fluidized material (80) is separated from the flue gases after the upper combustion chamber (11) and guided back to the fluidized-bed chamber (8) through cooled return conduits (15, 16) and an uncooled return conduit system (19) in the desired ratio.