Modular Heat Exchange Unit With Maintenance Duct
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Solution Overview
Problem
Existing heat exchange units for power plants are large, cumbersome, and inefficient, leading to increased costs and space requirements, and often result in the venting of hot exhaust gas due to simple cycle operations, which are less efficient and environmentally damaging.
Innovation Solution
A heat exchange unit design featuring a gas inlet duct with a heat exchange duct of substantially perpendicular longitudinal axes, incorporating a maintenance duct for access and a heating mechanism, such as a burner, to enhance heat conversion and reduce space requirements, while improving gas flow distribution and reducing structural loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If heat exchangers are designed to be transported in component form and assembled on site, then transportation and assembly become feasible, but additional floor-space and increased transportation, assembly, testing and maintenance costs are required
Solution Approach 1:
The heat exchanger is divided into multiple modules that can be transported separately and assembled on-site. Each module contains a subset of the heat exchange tubes and support structures, allowing for manageable transportation and flexible assembly configurations to match the exhaust gas flow requirements.
Solution Approach 2:
The support structures and internal components are nested within the modular framework, with heat exchange tubes positioned within support ribs and cross-members. This nesting approach maximizes space utilization during transportation while maintaining structural integrity during assembly.
2Area of stationary object
If the heat exchanger is made more compact to reduce space requirements, then floor-space is reduced, but connection to the gas turbine and maintenance access become more difficult
Solution Approach 1:
The support structures incorporate adjustable and removable elements that allow maintenance personnel to access internal components. Cross-members and support ribs can be detached or reconfigured during maintenance operations, providing dynamic access pathways while maintaining a compact overall footprint during normal operation.
Solution Approach 2:
Access hatches and maintenance ports are introduced as intermediary structures that provide pathways to internal heat exchange components without requiring complete disassembly of the compact unit. These intermediaries allow maintenance personnel to reach tubes and supports while the unit remains in its space-efficient configuration.
3Reliability
If irregular flow distribution in exhaust gas is allowed to reduce naturally over distance, then velocity fluctuations decrease, but longer ducts with increased cross sectional area are required, resulting in inefficient use of space and increased costs
Solution Approach 1:
Flow distribution baffles and straightening sections are installed at the inlet of the heat exchanger to pre-condition the exhaust gas flow before it enters the heat exchange tubes. These preliminary flow control elements redistribute the gas evenly across all tubes, preventing velocity fluctuations and hot spots before they can cause damage, thereby eliminating the need for long ducts to naturally reduce irregularities.
4Reliability
If components are made significantly stronger and more durable to withstand excessive vibration and oscillations, then reliability under irregular flow conditions improves, but more expensive materials and manufacturing are required and weight increases
Solution Approach 1:
The support structures utilize optimized geometric parameters and material distributions that provide high vibration resistance through structural design rather than material strength alone. Support ribs and cross-members are configured with specific thicknesses, spacing, and attachment methods that naturally dampen vibrations and oscillations, allowing the use of lighter materials while maintaining reliability under irregular flow conditions.
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 design allows for more efficient heat recovery, reduced maintenance costs, and easier installation by providing a space-efficient solution that can convert simple cycle power plants to combined cycle operations, improving energy output and reducing environmental impact.
Implementation Method 1
A heat exchange array of a heat exchange system may be situated within the heat exchange duct
Implementation Method 2
a heating mechanism, such as a burner, to enhance heat conversion
Data Source
AI summary
A heat exchange unit (214) arranged to be used to recover energy from exhaust gas, the heat exchange unit (214) comprising a gas inlet duct (222) to which a heat exchange duct (216) is connected, wherein a heat exchange array (752, 754) of a heat exchange system is situated within the heat exchange duct (216) surrounding a maintenance duct and wherein the maintenance duct (226) is arranged to allow access for inspection and/or maintenance of at least part of the heat exchange system.