Grate Bar Cooling via Internal Heat Transfer Loop
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Solution Overview
Problem
Conventional cooling methods for grate bars in waste-to-energy plants, such as air-cooled and water-cooled systems, are inadequate for high thermal loads, leading to wear, thermal degradation, and increased costs, especially when dealing with fuels with high net caloric values.
Innovation Solution
A cooling system utilizing a gaseous cooling fluid, independent of primary combustion air, circulates through a heat transfer loop within the grate bars, extracting heat and preventing thermal overload, and can be part of an open-loop or closed-loop system, including forced draft air or saturated steam, to increase thermal load capacity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If air-cooled grate bars are used, then the system is simple and cost-effective, but the thermal load capacity is limited to about 1 MW/m²
Solution Approach 1:
The patent employs a hydraulic cooling system where water is circulated through channels within the grate bars to remove excess heat. This hydraulic approach enables the grate bars to withstand thermal loads exceeding 1 MW/m², overcoming the limitations of air-cooled systems while maintaining structural integrity under high thermal stress.
2Temperature
If water-cooled grate bars are used, then the thermal load capacity increases, but the system complexity and cost increase
Solution Approach 1:
The patent integrates the cooling function directly into the grate bar structure by embedding water channels within the bars themselves. This merging of cooling pathways with the structural components eliminates the need for separate cooling apparatus, reducing overall system complexity while maintaining high thermal load capacity.
Solution Approach 2:
The water-cooled grate bars serve multiple functions simultaneously: they provide structural support for the waste bed, enable mechanical pushing and turning of waste, and conduct heat removal through internal water circulation. This multi-functionality reduces the need for additional dedicated cooling equipment, simplifying the overall system.
3Use of energy by moving object
If primary air is used for cooling, then the air is pre-warmed for combustion, but the cooling effectiveness is insufficient for high NCV waste
Solution Approach 1:
The patent extracts the cooling function from the primary combustion air system by implementing a dedicated water-cooling circuit within the grate bars. This separation allows the primary air to be optimized for combustion while the water cooling system independently manages thermal loads, ensuring adequate cooling effectiveness even for high NCV waste materials.
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
The system effectively increases the thermal load capacity beyond existing air-cooled systems, reduces wear and degradation, and is more cost-effective than water-cooled systems, allowing for higher caloric value fuels and improved combustion efficiency by re-introducing extracted heat into the combustion process.
Implementation Method 1
a cooling system utilizing a gaseous cooling fluid, independent of primary combustion air, circulates through a heat transfer loop within the grate bars, extracting heat
Implementation Method 2
The forced draft blower forces air through the cooling loop
Implementation Method 3
including forced draft air or saturated steam
Data Source
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AI summary
A cooling system for a feed grate (10) of an incinerator of solid materials is described. The feed grate (10) includes a plurality of grate bars (100), at least one of the grate bars (100) including a body (116) having a top surface (118), a bottom surface (120), a first end (122) and a second end (124). The cooling system includes a first aperture (134) in the body (116) and a second aperture (136) in the body (116). An internal passageway (142) is defined within the body (116) and fluidly connects the first aperture (134) to the second aperture (136). The first aperture (134) is fluidly connected to a gas supply (150) and arranged to receive a gas from the gas supply (150) therethrough into the body (116). The second aperture (136) is arranged to provide an egress for the gas out of the body (116). A manifold duct (152) is fluidly coupled to the second aperture (134) for receiving the gas from the second aperture (134). The gas from the gas supply (150) is independent of the primary combustion air (160) of the incinerator. A heat exchanger is fluidly is connected to the manifold duct (152) and forms a closed loop with the internal passageway (142) in the body (116) of the grate bar (100).