Solar Field Pipe Loop Layout for Rapid Molten Salt Emptying
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Solution Overview
Problem
Current solar power plants using molten salts as heat transfer fluids face challenges with freezing and safe emptying of the pipeline systems, particularly in long pipelines, leading to potential damage and inefficiencies due to high melting points and volume expansion issues, as well as limitations in thermal stability and operational reliability.
Innovation Solution
A solar field design with a pipe system comprising multiple independent pipeline loops connected at different geodetic heights, allowing for safe and efficient emptying by using pressurized gas to flow molten salt into drainage tanks, which are positioned strategically near collectors and distributors, and incorporating fail-safe valves and heating mechanisms to prevent solidification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If molten salts are used as heat transfer fluid to achieve higher operating temperatures, then thermal efficiency is improved, but the risk of freezing and pipeline damage increases due to high melting points and volume expansion
Solution Approach 1:
The pipeline system is divided into multiple independent loops, each equipped with its own drainage tank and fail-safe valves. This segmentation allows individual loops to be drained and isolated without affecting the entire system, reducing the freezing risk in each segment while maintaining high temperature operation in others.
Solution Approach 2:
Fail-safe valves are pre-configured to automatically open and drain pipelines when power failures or freezing conditions are detected. Drainage tanks are pre-positioned at strategic locations to receive molten salt before it freezes. This preliminary preparation ensures rapid response to freezing risks without requiring complex real-time control during emergencies.
2Reliability
If pipeline systems are designed to be emptied during downtimes to prevent freezing, then freezing damage is reduced, but emptying time is excessive and may not be completed before freezing occurs
Solution Approach 1:
By dividing the pipeline into multiple loops with separate drainage tanks, each loop can be drained independently and simultaneously. This parallel drainage approach significantly reduces the total emptying time compared to draining a single long pipeline sequentially, allowing rapid response to freezing conditions.
Solution Approach 2:
The system drains pipelines partially into distributed drainage tanks rather than requiring complete emptying into a single central tank. This partial action approach allows faster drainage of critical sections before freezing occurs, while accepting that some residual salt remains in isolated sections where freezing is prevented by insulation and heat tracing.
3Device complexity
If a single central drainage tank is used to empty pipelines, then system complexity is reduced, but emptying efficiency decreases due to long outflow paths and times
Solution Approach 1:
Instead of one central drainage tank, the system uses multiple distributed drainage tanks positioned near different sections of the solar field. This segmentation creates shorter drainage paths for each pipeline loop, enabling faster emptying speeds while maintaining relatively simple individual tank structures that are easier to manage than a single large central tank.
4Productivity
If pipeline gradients are increased to facilitate emptying into drainage tanks, then emptying efficiency is improved, but collector optical efficiency decreases
Solution Approach 1:
The pipeline system uses minimal gradients for normal operation to maintain collector optical efficiency, but incorporates local drainage sections with steeper gradients near the drainage tanks. These localized gradient sections are positioned only where needed for emptying, allowing efficient drainage without compromising the overall optical performance of the collectors during normal operation.
5Device complexity
If valves without fail-safe positions are used in pipeline systems, then device complexity is reduced, but system safety decreases during power failures
Solution Approach 1:
Fail-safe valves are equipped with spring-loaded mechanisms and position indicators that automatically return to and indicate the open/drain position without requiring external power or control signals. The valves self-service by using the failure condition (loss of power) to trigger the safe state, eliminating the need for complex powered actuators while ensuring reliability during power failures.
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 enables rapid and reliable emptying of pipeline systems during downtimes, reduces the risk of damage from freezing, and maintains operational efficiency by ensuring continuous heat transfer and energy generation, even during periods without solar radiation.
Implementation Method 1
the collector can be fed with pressurized gas and the distributor can be fed with pressurized gas
Implementation Method 2
The freezing of the molten salt can cause great economic damage in pipeline systems. The cause of the damage is, for example, the strong volume expansion of salts when they melt.
Implementation Method 3
the strong volume expansion of salts when they melt
Implementation Method 4
If the molten salt freezes, which can generally occur outside of the operating times of the solar power plant, there is a volume contraction, which can lead to a different state of solidification depending on the pipe system and operating state.
Data Source
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AI summary
The invention relates to a pipeline system comprising at least one pipeline loop (9) which is connected to a collector (7) at one end and to a distributor (5) at a second end. The collector (7) and the distributor (5) are arranged one above the other. When the collector (7) lies above the distributor, pressurized gas can be supplied to the collector, and the distributor (5) is connected to an emptying container (21); and when the distributor (5) lies above the collector, pressurized gas can be supplied to the distributor (5), and the collector (7) is connected to an emptying container (21), said emptying container (21) lying lower than the collector (7) and the distributor (5). The invention further relates to an emptying container (21) for receiving a liquid flowing through a pipeline system (3). The emptying container (21) is connected to the pipeline system (3) via an immersion pipe (33) protruding into the emptying container (21). The invention is characterized in that a siphon (41) is provided in the immersion pipe (33) between the pipeline system (3) and the emptying container (21), and the immersion pipe (33) can be heated, said siphon (41) being closed by a solidified material (43) during the operation of the pipeline system (3).