Gas Turbine Steam Generator With Intercooler Heat Recovery
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Solution Overview
Problem
Current steam injection gas turbine systems face inefficiencies in thermal management, water consumption, and plume formation, with conventional HRSGs leading to reduced thermal efficiency, increased costs, and public perception issues due to visible steam plumes.
Innovation Solution
A gas turbine engine system incorporating a Once-Through Steam Generator (OTSG) with a bypass damper and condenser for efficient steam recovery and reuse, allowing for dry-run capability and flexible steam injection, along with a condenser to minimize water consumption and plume formation, and an intercooler for heat absorption and plume suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If water flow rate through the intercooler is reduced to match steam injection rate, then water consumption is reduced, but thermal efficiency deteriorates because heat from the intercooler is lost
Solution Approach 1:
The patent recovers heat from the intercooler by routing it to preheat feedwater for the steam generator, converting what would be wasted heat into a useful function. This resolves the contradiction by recovering energy that would otherwise be lost when reducing intercooler water flow rate.
Solution Approach 2:
The intercooler water serves multiple functions: cooling the compressor discharge air and simultaneously preheating steam generator feedwater. This multi-functionality allows the system to maintain thermal efficiency while reducing overall water consumption.
2Loss of energy
If final steam temperature from HRSG is increased to improve thermal efficiency, then thermal efficiency is improved, but HRSG size and cost increase due to reduced mean temperature difference
Solution Approach 1:
The intercooler preheats the feedwater before it enters the steam generator, performing a preliminary heating action. This reduces the heating burden on the HRSG, allowing it to operate more efficiently at smaller sizes while still achieving the required steam temperatures.
Solution Approach 2:
The intercooler acts as an intermediary heat exchange device between the compressor cooling system and the steam generator. It transfers heat from the intercooler water to the feedwater, improving the overall thermal efficiency without requiring excessive HRSG capacity.
3Power
If steam is injected into the gas turbine cycle, then power output and mass flow are increased, but water consumption increases and plume formation occurs
Solution Approach 1:
The system recovers water from the exhaust stream using a condenser and returns it to the steam generator for reuse. This closed-loop water management reduces net water consumption while maintaining the steam injection necessary for power output enhancement.
Solution Approach 2:
The condenser utilizes phase transition of water vapor in the exhaust to liquid water, enabling water recovery from the exhaust stream. This phase change process allows the system to reclaim water that would otherwise be lost and continue the water cycle.
4Reliability
If conventional HRSG is used with water on secondary side, then steam can be generated, but water must be continuously present to avoid thermal shock and damage
Solution Approach 1:
The system dynamically controls the feedwater flow to the steam generator during start-up, allowing temporary dry operation to protect against thermal shock while maintaining operational flexibility. The bypass damper provides dynamic control over exhaust gas flow to manage heating rates.
Solution Approach 2:
The bypass damper provides a protective mechanism during start-up by controlling the amount of hot exhaust gas that reaches the steam generator, cushioning against thermal shock before it occurs. This allows controlled heating that protects the system while enabling faster start-up.
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 system enhances thermal efficiency, reduces water consumption, eliminates visible plumes, and offers cost-effective and environmentally friendly operation with improved start-up times and power generation capabilities.
Implementation Method 1
a condenser for condensing condensable fluid from the working fluid
Implementation Method 2
a vapour generating means downstream of the turbine having a first operating side for containment of the working fluid and a second operating side for containment of a fluid to be vapourised in the vapour generating means by heat transfer with the working fluid
Implementation Method 3
an intercooler for heat absorption and plume suppression
Data Source
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AI summary
A steam injection gas turbine engine having a once-through steam generator (OTSG). A condenser is provided downstream of the OTSG to capture water and is protected from hot flue gasses during startup by a bypass circuit. Optionally, heating the exhaust downstream of the condenser using coolant taken from an intercooler provides plume suppression.