Composite Geothermal Extraction Pipe for Deep Borehole Loads
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Solution Overview
Problem
Geothermal probe delivery tubing made of GRP double-wall elements fails to withstand stresses in deep boreholes, leading to material failure and leaks due to pressure and tensile loads during installation and removal processes.
Innovation Solution
A composite tubing with an inner heat-insulating plastic layer, such as polypropylene, and an outer metallic layer, like steel, is used, where the inner pipe sections are welded and the outer pipe sections are screwed together, with load-bearing devices spaced along the length to manage thermal expansion and buoyancy forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If GRP double-wall elements are used for conveying piping, then thermal insulation is improved, but mechanical strength and reliability deteriorate under pressure and tensile loads
Solution Approach 1:
The patent employs a composite structure consisting of an inner GRP pipe providing thermal insulation and an outer steel pipe providing mechanical strength. This composite design allows the system to simultaneously achieve good thermal insulation properties from the GRP material and high resistance to pressure and tensile loads from the steel material, resolving the contradiction between thermal insulation and mechanical reliability.
2Ease of operation
If GRP pipes are used, then ease of installation is improved, but resistance to on-site stresses in deep wells deteriorates
Solution Approach 1:
The composite structure combines the installation advantages of GRP pipes with the stress resistance of steel pipes. The outer steel pipe reinforces the overall structure to withstand deep well stresses while the inner GRP pipe maintains the ease of installation characteristics.
3Loss of energy
If polypropylene is used for the inner pipe, then thermal insulation is improved, but mechanical rigidity deteriorates
Solution Approach 1:
The patent uses polypropylene for the inner pipe to achieve excellent thermal insulation, while the outer steel pipe provides the necessary mechanical rigidity and structural support. This composite arrangement allows each material to perform its optimal function without compromising the other.
4Strength
If welded connections are used for inner pipe sections, then connection strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the conveying piping system into two separate segmented structures: an inner pipe system and an outer pipe system. This segmentation allows each system to be manufactured and assembled independently using appropriate connection methods, reducing overall manufacturing complexity while maintaining connection strength through welded joints for the inner pipe sections.
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 composite tubing provides high static and dynamic stability, optimal energy balance, and robust connections, ensuring the tubing can be easily installed and removed without material failure or leaks, while maintaining low thermal conductivity and mechanical rigidity.
Implementation Method 1
The polypropylene component has a very low heat transfer coefficient and thus ensures optimal thermal insulation
Implementation Method 2
the metal of the outer piping area is steel... the outer metal, in particular steel, tubing area, which produces the weight required for a long length of tubing and also ensures the mechanical rigidity of the assembly as a whole
Implementation Method 3
the inner pipe has a multiplicity of inner pipe sections welded to one another, which form the inner pipe run
Implementation Method 4
the outer pipe has a multiplicity of outer pipe sections screwed to one another, which form the outer pipe run
Data Source
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AI summary
The piping has an inner pipe (15) formed from a heat-insulating plastic i.e. polypropylene, and an outer pipe (16) made of metal i.e. steel. The outer pipe is provided separate from the inner pipe. The inner pipe is fixedly connected with the outer pipe in a region of ends of the piping. A thickened pipe shoe (17) is provided at an end of the outer pipe. An end of the inner pipe is fixedly connected with the pipe shoe by an adapter piece (18). A screw connection piece (21) includes a thread (22) for screwing with the pipe shoe, and an engaging region (23) for engaging in an end piece (19). An independent claim is also included for a method for installing an extraction piping in an outer borehole piping.