Movable Baffle for HRSG Coil Gap Sealing
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Solution Overview
Problem
The installation of traditional steel angle iron baffles in Heat Recovery Steam Generators (HRSGs) is time-consuming due to the need for scaffolding and welding, which increases labor costs and safety risks, and is impractical for prefabrication due to tight construction tolerances.
Innovation Solution
A baffle system where the sidewall gas baffle is mounted onto the coil module in the shop, supported by a mount and retained in a first position by ties that melt at operating temperatures, allowing the baffle to slide down and outward to bridge the construction tolerance gap, preventing exhaust gas bypass and enhancing heat exchange performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional steel angle iron baffles are installed by welding to liners after coil installation, then the baffles effectively prevent exhaust gas bypass, but the installation process is time-consuming and requires scaffolding and welding operations
Solution Approach 1:
The baffle is pre-assembled with the coil module in the shop before field installation. The mount is attached to the coil module, and the baffle is positioned and secured with retainers during shop fabrication, eliminating the need for time-consuming field welding operations while ensuring proper positioning
Solution Approach 2:
The baffle installation is merged with the coil module assembly process. Instead of installing the baffle separately after coil installation, the baffle, mount, and coil module are assembled together as an integrated unit in the shop, streamlining the overall installation process
2Adaptability or versatility
If traditional baffles are installed by welding after coil modules are lowered into the casing, then the construction tolerances are accommodated, but the process requires workers to enter the casing and erect scaffolding, increasing safety risks and labor costs
Solution Approach 1:
The baffle is pre-positioned and secured to the coil module in the shop using retainers before the coil module is lowered into the casing. This preliminary assembly ensures proper positioning that accommodates construction tolerances while eliminating the need for dangerous scaffolding operations inside the casing
Solution Approach 2:
The baffle installation operation is extracted from the field installation process and moved to the shop fabrication process. By taking out the complex welding and scaffolding operations from the field environment, the solution eliminates safety risks associated with workers entering the casing while maintaining adaptability to tolerances through precise shop assembly
3Strength
If the baffle is held in the first position by ties during installation, then the coil can be lowered through the roof without damage, but the ties must melt at operating temperatures to allow the baffle to slide to the second position
Solution Approach 1:
The retainer ties are made of material that undergoes phase transition from solid to liquid at operating temperatures. The ties hold the baffle in the first position during installation, protecting the coil, then melt when exposed to operating temperatures, allowing the baffle to automatically slide to the second position against the liner
Solution Approach 2:
The retainer mechanism is self-actuating through thermal response. The ties automatically melt at operating temperatures without external intervention, causing the baffle to self-adjust from the first position to the second position, eliminating the need for complex mechanical release mechanisms
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 efficient installation of baffles in the shop, reducing on-site labor and safety risks, while ensuring effective heat transfer by blocking exhaust gas bypass, thereby improving the overall performance of the HRSG.
Implementation Method 1
The baffle is retained in a first position relative to the mount and coil by a retainer. The retainer can be released so that the weight of the baffle will cause the baffle to slide down and outward to a second position
Implementation Method 2
the baffle to slide down and outward to a second position, bridging the construction tolerance gap to block bypass of the exhaust gap in an HRSG
Implementation Method 3
The exhaust gas that bypasses does not transfer its energy to the water in the coils
Implementation Method 4
hot gases...pass through the heat exchangers or coils
Data Source
AI summary
Disclosed is: A casing of a heat recovery steam generator has a sidewall, and heat exchanger coil located therein capable of exchanging heat from hot exhaust gas flow into the casing, with a gap between the end of the coil and a sidewall. A baffle system for closing the gap after the coil is installed in the casing comprises a mount attached to the coil near the gap, and a baffle plate associated with the mount and movably supported thereby. The configuration of the mount and baffle plate are such to allow the baffle plate to be capable of moving from a retracted position withdrawn from the sidewall, to an extended position closing the gap. A retainer can hold the plate in the retracted position. The retainer can release, for example, by being temperature sensitive. The mount can have a support that engages the coil.