HRSG Component Preheating via Pressure Differential Heat Recovery
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Solution Overview
Problem
Heat recovery steam generators (HRSGs) face thermal stress issues during startup due to temperature differences, leading to potential degradation of pressurized components, and existing preheating methods like electrical heat tracing and auxiliary steam are costly and inefficient.
Innovation Solution
A system utilizing a heat-transferring conduit that connects high-pressure and low-pressure sections of the HRSG flow path, leveraging a pressure differential to direct a heat-containing medium for preheating components, reducing thermal stresses without the need for auxiliary heat sources or expensive hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical heat tracing is used to preheat pressure parts, then thermal stress is reduced and component lifespan is extended, but hardware cost and power consumption increase significantly
Solution Approach 1:
The system uses the HRSG's own heat-containing medium (flue gas or steam) to preheat the pressure parts, eliminating the need for external power sources or auxiliary boilers. The heat is recovered from the medium that would otherwise be wasted, making the system self-sufficient and energy-efficient
Solution Approach 2:
The invention recovers thermal energy from the heat-containing medium (flue gas or steam) that would otherwise be discarded or underutilized. By extracting heat from this medium during startup, the system converts waste thermal energy into useful preheating capacity, reducing the need for additional fuel consumption
2Productivity
If auxiliary steam preheating is used to preheat pressure parts, then thermal stress is reduced and startup time is minimized, but capital equipment cost and operating costs increase
Solution Approach 1:
The heat-transferring conduit serves multiple functions: it acts as a preheating device during startup, a heat recovery device during operation, and a thermal coupling element between different pressure parts. This multi-functionality eliminates the need for separate auxiliary preheating equipment
Solution Approach 2:
The invention merges the preheating function with the existing heat recovery system by integrating the heat-transferring conduit into the flow path. This combines the startup preheating requirement with the ongoing heat recovery operation, eliminating the need for separate auxiliary equipment
3Strength
If thick walled components and dissimilar metal welds are used to withstand thermal stress, then component strength is improved, but startup time must be extended to prevent damage
Solution Approach 1:
The system performs preliminary heating of the pressure parts using the heat-transferring conduit before full steam production begins. This gradual preheating prepares the thick-walled components and dissimilar metal welds for thermal stress, allowing faster subsequent startup without compromising component integrity
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 effectively reduces thermal stresses and extends the lifespan of HRSG components by uniformly preheating them before steam production, reducing startup time and operational costs, while avoiding the expenses associated with auxiliary heating systems.
Implementation Method 1
The heat-transferring conduit is further configured to heat the one or more components of the heat recovery steam generator via directing the heat-containing medium to be in heating contact with the one or more components
Implementation Method 2
the heat-containing medium flows through the heat-transferring conduit via a pressure differential between a first pressure of the heat-containing medium at the high-pressure section and a second pressure of the heat-containing medium at the low-pressure section
Data Source
AI summary
A system for heating one or more components of a heat recovery steam generator that includes a heat-transferring conduit that fluidly connects a high-pressure section of a flow path to a low-pressure section of the flow path. The flow path is defined by a housing of the heat recovery steam generator and configured to direct a heat-containing medium. The heat-transferring conduit is configured to receive the heat-containing medium from the flow path such that the heat-containing medium flows through the heat-transferring conduit via a pressure differential between a first pressure of the heat-containing medium at the high-pressure section and a second pressure of the heat-containing medium at the low-pressure section. The heat-transferring conduit is further configured to heat the one or more components of the heat recovery steam generator via directing the heat-containing medium to be in heating contact with the one or more components.