Cold Water Pipe Connection for Floating OTEC Spar Integration
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Solution Overview
Problem
Ocean Thermal Energy Conversion (OTEC) power plants face low overall efficiency, high construction and operating costs, and environmental concerns due to low thermodynamic efficiency, large parasitic loads, and challenges in designing and maintaining long cold water intake pipes in dynamic ocean environments.
Innovation Solution
A floating, multi-stage heat engine OTEC power plant with a structurally integrated cold and warm water supply system, using a continuous offset staved cold water pipe and a hybrid cascading multi-stage heat exchange system to reduce parasitic loads and enhance efficiency, while minimizing environmental impact through appropriate water discharge depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a long cold water intake pipe is used to reach deep ocean water, then cold water supply is achieved, but construction and operating costs increase significantly
Solution Approach 1:
The cold water intake pipe is divided into multiple modular sections that can be assembled in stages. Each section is a manageable unit that can be manufactured, transported, and installed separately, reducing the complexity and cost of constructing a single long pipe
Solution Approach 2:
The cold water intake pipe is placed inside the floating platform structure, utilizing the existing structural space. This nesting approach protects the pipe from environmental damage, reduces the need for additional protective structures, and optimizes the use of structural materials
2Quantity of substance
If a large diameter cold water intake pipe is used to transport sufficient cold water volume, then cold water supply requirement is met, but construction costs and structural complexity increase
Solution Approach 1:
The cold water intake pipe incorporates flexible joints and expansion sections that allow the pipe to dynamically adapt to wave motion, platform movement, and thermal expansion. This dynamic design enables the use of smaller diameter sections that can flex and move, rather than requiring a single large rigid pipe
Solution Approach 2:
The pipe incorporates flexible membrane sections that can expand and contract with pressure changes and movement. These flexible sections allow the pipe to maintain structural integrity with smaller diameters while still transporting the required water volume through increased flow velocity and optimized geometry
3Stability of the object's composition
If the cold water pipe connection is made at the bottom of the floating platform, then structural integration is improved, but accessibility for maintenance and installation becomes difficult
Solution Approach 1:
The critical connection components, including flanges, coupling mechanisms, and sealing elements, are extracted as separate removable modules. This allows maintenance personnel to access and replace these components without dismantling the entire pipe or platform structure, combining structural integration with maintenance accessibility
Solution Approach 2:
An intermediary access chamber or maintenance platform is introduced between the pipe connection point and the external environment. This intermediary structure provides a protected workspace for maintenance activities while maintaining the structural integration of the pipe with the floating platform
4Productivity
If the floating platform is designed for minimal heave, then OTEC system efficiency is improved, but construction complexity and cost increase
Solution Approach 1:
Ballast tanks and weight distribution systems are pre-configured during construction to optimize the platform's stability characteristics. This preliminary arrangement of weights and buoyancy elements minimizes heave motion without requiring complex active control systems during operation
Solution Approach 2:
The platform's geometric parameters, including draft, beam, and hull form coefficients, are optimized to inherently reduce heave response to waves. By carefully selecting and adjusting these structural parameters, the platform achieves minimal heave motion through its natural hydrodynamic characteristics rather than active control
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 solution increases net efficiency, reduces construction and maintenance costs, and minimizes environmental impact by optimizing water flow and discharge, leading to a more viable and sustainable OTEC power generation system.
Implementation Method 1
the weight of the pipe balanced by the buoyancy of the pipe
Implementation Method 2
The OTEC process uses the temperature difference between surface and deep sea tropical waters to drive a heat engine
Implementation Method 3
large heat exchange surface areas are required, along with high fluid velocities
Data Source
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AI summary
An offshore structure for use with an OTEC system includes a submerged spar having a lower portion having a cold water intake. The cold water intake includes a domed terminus in fluid communication with a cold water pipe. A dry machinery space adjacent the cold water intake includes one or more cold water supply pumps and one or more cold water pipe lifting and retention winches having a lifting cable connected to the cold water pipe.