Heat Exchanger for Contaminated Fluids with Variable Heat Load
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Solution Overview
Problem
Traditional shell and tube heat exchangers are not optimal for contaminated gases with strong variable heat loads, as they can lead to occlusion of tubes, uneven heat transfer, and increased stress on welding zones due to thermal expansions, compromising the device's lifespan.
Innovation Solution
A heat exchanger design featuring a bundle of lined, independent tubes with an annular passage for fluid flow, allowing for free expansion and using a wire to maintain passage dimensions, along with corrugated profiles and sealant materials to manage thermal expansions and prevent leakage, while incorporating features like Archimedean screws for solid material elimination and flexible ducts to ensure consistent fluid speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional shell and tube heat exchanger is used for contaminated gases, then heat exchange capacity is achieved, but tube occlusion occurs and heat transfer becomes uneven
Solution Approach 1:
The heat exchanger is divided into multiple independent tubes instead of a single large channel. Each tube can be independently cleaned or replaced, and the segmented structure prevents complete occlusion from blocking the entire heat exchange path, maintaining productivity while improving reliability
Solution Approach 2:
The patent employs a filter screen within the tubes that allows gas passage while trapping contaminants. This porous filtering mechanism prevents occlusion by separating the contaminant retention function from the heat transfer function, enabling continuous operation despite contaminated gas flow
2Productivity
If tubes are subjected to strong variable heat load, then heat exchange efficiency is improved, but thermal stress on welding zones increases
Solution Approach 1:
The patent introduces expansion joints with corrugated profiles into the tube structure. These flexible sections can absorb thermal expansion and contraction movements, reducing stress transmission to the welding zones and preventing fatigue failure under strong variable heat loads while maintaining heat exchange efficiency
Solution Approach 2:
The design explicitly accounts for thermal expansion by providing expansion compensation mechanisms. The corrugated expansion joints allow the tubes to expand and contract freely with temperature changes, preventing stress accumulation that would otherwise compromise welding zone strength during efficient heat exchange operations
3Reliability
If filter screen is added to prevent occlusion, then contaminant trapping is improved, but pressure loss increases
Solution Approach 1:
The filter screen is positioned locally at specific locations within the tube rather than as a continuous obstruction. This localized filtering approach traps contaminants at critical points while maintaining open flow paths elsewhere, improving contaminant trapping efficiency without excessive pressure loss
Solution Approach 2:
The filter screen parameters (mesh size, material, positioning) are optimized to balance filtration efficiency and pressure drop. By adjusting these parameters, the system achieves effective contaminant trapping while minimizing the impact on gas flow and pressure loss
4Strength
If expansion joints are provided to accommodate thermal expansion, then welding zone stress is reduced, but device complexity increases
Solution Approach 1:
The expansion joints utilize corrugated (curved) profiles instead of straight rigid sections. These curved geometries provide natural flexibility to accommodate thermal expansion and contraction, reducing welding zone stress while adding minimal structural complexity compared to rigid straight tubes
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 heat transfer efficiency, reduces the risk of occlusion and thermal stress, and extends the useful life of the heat exchanger by maintaining consistent fluid flow and preventing leakage, even under sudden heat variations.
Implementation Method 1
a surface heat exchanger, mainly made up of a bundle of tubes arranged inside a more or less cylindrical vessel... allows the exchange of great heat quantities
Implementation Method 2
the inner tube (2) is provided with a corrugated profile (15) able to absorb the thermal expansions of the inner tube (2)
Implementation Method 3
the corrugated profile (15) able to absorb the thermal expansions
Implementation Method 4
the plenum 9, 10, 109, 110 are provided with a device 17, 117, for example an Archimedean screw for a rapid ash or other solid materials elimination provided in the contaminated gases
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Heat exchanger (100, 200) for cooling contaminated fluids and which are subjected to variable thermal load, by means of heat transfer to a receiving liquid and/or vapor fluid, said heat exchanger comprising a tube bundle consisting of a plurality of independent tubes (1), two plenums ( 9, 10, 109, 110), plates (12, 13, 112, 113), and characterized in that said independent tubes (1) comprise an inner tube (2, 102) in which the contaminated gas flows, and an outer tube (3, 103) being said inner tube (2, 102) and outer tube (3, 103) coaxial and where between the outer surface (2', 102') of the inner tube (2, 102) and the inner surface (31, 103') of the outer tube (3, 103) is defined an annular passage G in which flows the receiving fluid and in that said inner tube (2, 102) is welded to the plate (12, 112) in a gas inlet section, while a gas outlet section is guided in a corresponding hole of the plate (13, 113), so that the inner tube (2, 102) expansion in an axial direction is not constrained.