Method and device for introducing protective gas into a receiver tube
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Solution Overview
Problem
Solar thermal power plants face efficiency decline due to hydrogen permeation in the annular space of receiver tubes, leading to increased thermal conductivity and reduced service life, as existing solutions like getter materials and noble gas filling are either limited or require costly and complex retrofitting processes.
Innovation Solution
A method and device for introducing a protective gas into the annular space of receiver tubes, allowing for subsequent filling of the space using laser drilling and welding to create and close openings, enabling efficient filling without additional tanks or complex fabrication, and allowing for retrofitting of existing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the annular space is evacuated to minimize heat losses, then thermal conductivity is minimized and efficiency is maximized, but hydrogen permeation from the thermal oil increases the partial pressure and thermal conductivity over time
Solution Approach 1:
The patent applies preliminary action by pre-filling the annular space with protective gas (such as nitrogen or argon) before the receiver tube is put into service. This proactive measure ensures that when hydrogen permeation occurs during operation, the protective gas already present buffers the pressure increase and maintains thermal insulation performance, thereby extending service life without requiring later interventions.
Solution Approach 2:
The patent changes the physical parameter of the annular space by introducing protective gas at a controlled partial pressure (e.g., 0.1 to 10 bar). This parameter change creates a pressure buffer that counteracts hydrogen permeation effects. The protective gas maintains the total pressure in the annular space, preventing hydrogen from significantly increasing the partial pressure and thereby maintaining low thermal conductivity over the service life of the receiver tube.
2Reliability
If getter materials are used to bind hydrogen in the annular space, then hydrogen concentration is reduced, but the absorption capacity is limited and pressure increases once maximum capacity is attained
Solution Approach 1:
The patent changes the fundamental approach from chemical binding (getter materials) to physical pressure buffering. By introducing protective gas at elevated partial pressure, the system creates a pressure reservoir that passively counteracts hydrogen permeation. This parameter change from chemical to physical mechanism provides unlimited capacity as long as the protective gas reservoir maintains pressure, eliminating the capacity limitation of getter materials.
3Loss of energy
If noble gas is filled in the annular space from the very start, then thermal conductivity is reduced compared to hydrogen, but the annular space cannot achieve optimal evacuated efficiency initially
Solution Approach 1:
The patent applies partial action by filling the annular space with protective gas at controlled partial pressures rather than completely evacuating it. The protective gas is introduced at levels (0.1 to 10 bar) that provide sufficient pressure buffering against hydrogen permeation while minimizing the thermal conductivity impact. This partial filling approach achieves a compromise between initial efficiency and long-term stability.
4Adaptability or versatility
If laser drilling and welding are used to create and close openings for gas filling, then retrofitting of existing equipment becomes feasible, but additional fabrication steps are required
Solution Approach 1:
The patent replaces traditional mechanical drilling and welding equipment with laser-based systems. Laser drilling creates precise openings through the cladding tube and wall without mechanical contact, and laser welding closes the openings with high precision. This substitution enables retrofitting of existing receiver tubes while maintaining structural integrity and minimizing additional fabrication complexity through the versatility and precision of laser technology.
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 method allows for maximum efficiency at the start of use and extends the service life of receiver tubes by preventing further efficiency drops, reducing costs and environmental impact through flexible and cost-effective gas filling of existing equipment.
Implementation Method 1
an opening that penetrates the cladding tube or the wall is produced
Implementation Method 2
protective gas is introduced through the opening into the annular space
Implementation Method 3
the opening is subsequently closed again
Implementation Method 4
By permeation, the released hydrogen enters the evacuated annular space
Implementation Method 5
an opening that penetrates the cladding tube or the wall is produced
Data Source
AI summary
A method for introducing a protective gas into an annular space of a receiver tube, in particular for solar collectors, is provided where the annular space is formed at least by one outer cladding tube and an inner absorber tube of the receiver tube and the outer cladding tube is connected to the absorber tube by a wall. The method includes producing an opening that penetrates the cladding tube or the wall, introducing protective gas through the opening into the annular space, and subsequently closing the opening.