Steam Generator Salt Bath Heat Transfer
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Solution Overview
Problem
Existing steam generators face inefficiencies due to wall losses and inability to compensate for thermal expansion, leading to suboptimal heat exchange efficiency and potential damage from fluctuating steam parameters, especially when using biomass as fuel at high pressures.
Innovation Solution
A steam generator design featuring a housing with a flow channel and a salt bath as a heat transfer medium, where the cross-section of the flow channel is larger at the inlet than the outlet, allowing for homogeneous heat transfer and preventing overheating, with a ceramic jacket at the inlet and ribs for enhanced energy input, and a preheating section in the base for efficient energy storage and transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a shell-and-tube heat exchanger is used with a surrounding casing, then heat exchange can be performed, but wall losses occur when heat exchange fluid passes between the heat exchanger and casing without flowing through the heat exchanger
Solution Approach 1:
The patent removes the surrounding casing from the heat exchanger design. Instead of having a casing that creates dead zones and wall losses, the invention uses an open structure where the heat exchange tubes are directly exposed to the combustion chamber, eliminating the energy losses associated with fluid bypassing a enclosed casing.
Solution Approach 2:
The heat exchanger is divided into multiple tube bundles with individual tube elements rather than a single enclosed shell-and-tube structure. This segmentation allows direct exposure of heat exchange surfaces to the combustion gases, preventing the formation of dead zones and reducing wall losses.
2Productivity
If high pressures and temperatures are used for efficient steam generation, then steam generation efficiency is improved, but thermal expansion and stresses in the heat exchanger material increase
Solution Approach 1:
The patent changes the operating parameters by using direct exposure to high-temperature combustion gases, allowing efficient heat transfer at high temperatures without requiring high pressures. The steam is generated at lower pressures (1-10 bar) compared to conventional high-pressure systems, reducing thermal stresses while maintaining efficiency through direct radiant and convective heat transfer.
Solution Approach 2:
Instead of using high pressure to achieve efficient steam generation, the invention inverts the approach by using direct high-temperature heat exposure through tube bundles in the combustion chamber, achieving efficient steam generation at lower pressures, thereby reducing material stress requirements.
3Stability of the object's composition
If an additional steam storage boiler is added to compensate for fluctuating energy content of biomass, then steam parameter stability is improved, but device complexity and risk of destruction increase
Solution Approach 1:
The patent incorporates a preheating section in the base of the combustion chamber that preheats the feed material before it enters the main combustion zone. This preliminary action ensures more stable and complete combustion, reducing fluctuations in energy content and steam parameters without requiring an additional storage boiler.
Solution Approach 2:
The invention removes the additional steam storage boiler from the system. Instead of adding complexity with a separate storage system, the patent achieves steam parameter stability through optimized combustion chamber design, direct heat transfer, and preheating of feed material, eliminating the need for redundant storage equipment.
4Stability of the object's composition
If the cross-section of the flow channel is larger at the inlet than at the outlet, then homogeneous heat transfer and prevention of overheating are achieved, but the device structure becomes more complex
Solution Approach 1:
The patent employs asymmetric flow channel design where the cross-section varies along the flow direction, being larger at the inlet and smaller at the outlet. This asymmetric geometry creates a flow distribution pattern that promotes homogeneous heat transfer across the tube bundle and prevents localized overheating, while the complexity is minimized by using simple geometric transitions.
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 achieves flexible and efficient steam generation across a wide pressure range, preventing overheating and decomposition, ensuring reliable operation and longevity while maintaining operational safety, and allowing for the use of fluctuating energy sources without additional storage boilers.
Implementation Method 1
a heat transfer medium, in particular a salt bath, is arranged in the housing to transfer heat from the heat exchange fluid flowing through the flow channel to the water flowing through the second heat exchange element
Implementation Method 2
a preheating section of the flow channel, which is arranged in the base, is provided. The preheating section of the flow channel is designed to transfer heat from the heat exchange fluid to the housing and/or the salt bath contained therein
Data Source
Figure 1
Figure 2
AI summary
Steam generator (1) comprising: a housing (2); a flow channel through which a heat exchange fluid, preferably flue gas, can flow from an inlet of the flow channel to an outlet of the flow channel, wherein at least one section of the flow channel is arranged as a first heat exchange element (3) in the housing (2); at least one second heat exchange element (4) arranged in the housing (2), through which water can flow for steam generation; a heat transfer medium arranged in the housing (2) to transfer heat from the heat exchange fluid flowing through the flow channel to the water flowing through the second heat exchange element (4) for steam generation, characterized in that the heat transfer medium is a salt bath, and the cross-section of the flow channel at the inlet of the flow channel is larger than at the outlet of the flow channel.