Water Feeding System Cooling Water Injection Prevents Flashing
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Solution Overview
Problem
In combined cycle plants, sudden decreases in heat exchange between water and fuel can cause water to flash, leading to unstable operation and potential damage to equipment due to reduced water flow rates and pressure changes.
Innovation Solution
A water feeding system with a first feed water line, a second feed water line of lower pressure, a heater, a medium heat exchanger, and a cooling water injecting line that injects cooling water with a lower temperature than the heated feed water to prevent flashing and stabilize water flow rates, using non-heated feed water as cooling water when necessary, and adjusting cooling water flow rates based on temperature to maintain predetermined conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow rate of fuel suddenly decreases significantly, then the heat exchange between fuel and water in the fuel preheater decreases, but this causes water temperature to increase and pressure to drop, leading to water flashing and potential damage to equipment
Solution Approach 1:
The invention applies preliminary anti-action by introducing cooling water into the feed water line before the water enters the low-pressure region. This preemptive cooling prevents the water temperature from rising too high and eliminates the pressure drop that causes flashing, thereby preventing potential damage to equipment before it can occur.
Solution Approach 2:
The invention changes the temperature parameter of the feed water by injecting cooling water. This parameter change ensures that even when fuel flow rate decreases and heat exchange reduces, the feed water temperature remains controlled and does not rise to dangerous levels, preventing flashing and maintaining system reliability.
2Object-affected harmful factors
If the water temperature in the feed water line increases above a predetermined temperature, then water flashing is prevented, but the water flow rate suddenly decreases significantly, disrupting stable operation of the plant
Solution Approach 1:
The invention uses cooling water as an intermediary substance to transfer heat from the feed water. By introducing this intermediary cooling medium, the system can control feed water temperature and prevent flashing while maintaining continuous water flow, thus avoiding disruption to plant operation.
Solution Approach 2:
The invention extracts excess heat from the feed water by introducing cooling water that absorbs the unnecessary thermal energy. This extraction of heat allows the system to prevent water flashing while maintaining the water flow rate, as the cooling water is continuously supplied and does not cause flow disruption.
3Reliability
If cooling water is injected into the feed water line, then water temperature is controlled and flashing is prevented, but the system complexity increases with additional components and control mechanisms
Solution Approach 1:
The cooling water serving line is designed to serve multiple functions: it can be connected to various water sources (condensate, makeup water, etc.) and can be activated under different operating conditions. This multi-functionality allows the system to prevent water flashing without requiring entirely separate dedicated cooling systems, thereby limiting the increase in complexity.
Solution Approach 2:
The system employs dynamic control where the cooling water flow rate is adjusted based on real-time feed water temperature and pressure conditions. The cooling water supply can be activated or deactivated, and its flow rate can be modulated, allowing the system to adapt to varying operating conditions without requiring overly complex fixed infrastructure.
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 effectively prevents water flashing and stabilizes water flow rates even during sudden changes in heat exchange, ensuring stable operation of the plant by managing temperature and pressure within predetermined ranges.
Implementation Method 1
a medium heat exchanger that is provided in the first feed water introducing line and that causes the first heated feed water to exchange heat with a medium, thereby cooling the first heated feed water and heating the medium
Implementation Method 2
a cooling water injecting line configured to inject cooling water into the first feed water introducing line at a position located further to the second feed water line side than the medium heat exchanger, the cooling water having a lower temperature than the first heated feed water
Implementation Method 3
a first heater that heats the first feed water
Data Source
AI summary
A water feeding system provided with: a first feed water line through which first feed water flows; a second feed water line through which second feed water having a lower pressure than the first feed water flows; a first heater that heats the first feed water; a first feed water introducing line that guides first heated feed water, which is the first feed water that has been heated by the first heater, to the second feed water line; a medium heat exchanger that causes the first heated feed water to exchange heat with a medium, thereby cooling the first heated feed water and heating the medium; and a cooling water injecting line that injects cooling water having a lower temperature than the first heated feed water into the first feed water introducing line, at a position located further to the second feed water line side than the medium heat exchanger.