HRSG Preheating System Simplification via Recirculation Control
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Solution Overview
Problem
Existing preheating systems for Combined Cycle Power Plants (CCPP) require multiple control units and complex recirculation circuits, which can reduce efficiency and increase heat loss, while also failing to effectively prevent corrosion from flue gas condensation in Heat Recovery Steam Generators (HRSG).
Innovation Solution
A simplified preheating system with a feed line and recirculation line, featuring a single control arrangement and temperature control circuit to maintain the fluid medium at a set temperature, optionally including a bypass line and heat shift configuration to optimize heat gain and reduce corrosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple control units and complex recirculation circuits are used in preheating systems, then the fluid medium temperature can be maintained, but the system efficiency decreases and heat loss increases
Solution Approach 1:
The patent extracts and eliminates unnecessary control units (second and third control elements) from the system, retaining only the essential first control element. This simplification reduces the system's complexity and associated heat losses while maintaining the core preheating function through the recirculation line and economizer coil.
Solution Approach 2:
The patent merges the control function into a single integrated control element that regulates the recirculation flow directly. This consolidation eliminates the need for separate control units and reduces the overall complexity of the control system, thereby minimizing heat loss and improving system efficiency.
2Temperature
If multiple control units are used to regulate recirculation mass flow, then the fluid medium temperature can be controlled, but the device complexity increases
Solution Approach 1:
The patent removes the second and third control elements from the system, extracting only the necessary control function into a single first control element. This reduces the number of components and simplifies the overall system architecture while maintaining temperature control capability.
Solution Approach 2:
The patent combines the temperature control function into a single integrated control element that regulates recirculation mass flow. This merging of control functions reduces device complexity by eliminating multiple separate control units and their associated instrumentation and control logic.
3Temperature
If regularized recirculation is used to maintain fixed temperature, then the HRSG can operate at minimum temperature, but the CCPP efficiency is constantly affected
Solution Approach 1:
The patent implements dynamic control of the recirculation mass flow through a single control element that can adjust flow rates in real-time. This dynamic regulation allows the system to optimize the balance between maintaining minimum HRSG temperature and maximizing CCPP efficiency, rather than relying on fixed, regularized recirculation patterns.
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 improved system maximizes efficiency by reducing control units, minimizing heat loss, and preventing corrosion in HRSG, while being convenient and economical to operate.
Implementation Method 1
The recirculation line is adapted to be connected between the outlet and the inlet of the LPE and being arranged parallel to LPE to recirculate the fluid medium to the LPE
Implementation Method 2
a Low Pressure Economizer (LPE) of the HRSG... to preheat the fluid medium
Data Source
AI summary
A preheating system for preheating fluid medium to be fed into the HRSG is disclosed. The system includes a feed line and a recirculation line. The feed line is adapted to feed the fluid medium to a Low Pressure Economizer (LPE) of the HRSG. The feed line is adapted to be adjoined to an inlet of the LPE, and an outlet of the LPE enables therefrom the flow of the fluid medium in further portion of the HRSG. The recirculation line is adapted to be connected between the outlet and the inlet of the LPE, in parallel to LPE to recirculate the fluid medium to the LPE. A particular method of preheating using such a system is equally disclosed.