Direct Steam Injection for Heat Exchanger Cleaning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current chemical cleaning methods for nuclear pressurized water reactor (PWR) steam generators are either complex and labor-intensive, requiring significant equipment setup and time for off-line processes, or lack effective monitoring and risk excessive corrosion during on-line processes.
Innovation Solution
The method involves direct steam injection into the steam generators for heating, allowing for simplified equipment setup, real-time corrosion monitoring, and efficient cleaning without the need for extensive external connections, using a system with temporary adapters and controlled steam injection to maintain optimal temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If off-line chemical cleaning processes are used, then cleaning effectiveness and safety are improved, but equipment complexity and setup time increase significantly
Solution Approach 1:
The patent extracts the heating function from complex external heating equipment and relocates it directly into the steam generator through steam injection. This eliminates the need for extensive external heating equipment while maintaining the cleaning effectiveness of off-line processes.
Solution Approach 2:
The steam injection system serves multiple functions: heating the cleaning solution, providing agitation through steam condensation, and enabling corrosion monitoring. This multi-functionality reduces the need for separate equipment while maintaining cleaning safety and effectiveness.
2Loss of time
If on-line chemical cleaning processes are used, then equipment setup time is reduced, but process monitoring capability and corrosion control deteriorate
Solution Approach 1:
The patent installs corrosion monitoring equipment and corrosion coupons inside the steam generator before the cleaning process begins. This preliminary action enables continuous monitoring throughout the cleaning process while maintaining the time efficiency of on-line procedures.
Solution Approach 2:
The patent uses steam as an intermediary to transfer heat directly into the steam generator. This indirect heating method allows the primary system to remain operational while enabling process monitoring, bridging the gap between on-line efficiency and off-line monitoring capability.
3Temperature
If external heating equipment is used for off-line cleaning, then temperature control is improved, but setup complexity and demobilization time increase
Solution Approach 1:
The steam injection system utilizes the plant's existing steam supply to heat the cleaning solution directly within the steam generator. This self-service approach eliminates the need for external heating equipment setup and demobilization while maintaining precise temperature control through steam flow regulation.
4Productivity
If complex external cleaning systems are installed, then cleaning effectiveness is improved, but access requirements and operational complexity increase
Solution Approach 1:
The patent merges the heating, agitation, and temperature control functions into a single steam injection system. This integration maintains the cleaning effectiveness of complex systems while dramatically simplifying operation through a single control mechanism.
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 approach reduces setup and demobilization times, minimizes equipment complexity, enables in-situ corrosion monitoring, and prevents mechanical damage to vessel internals, while maintaining effective cleaning efficiency and safety.
Implementation Method 1
injecting steam through the temporary adapter and into the secondary side of the heat exchanger, wherein the injected steam heats the heat exchanger and residual fluid to a target cleaning temperature range
Implementation Method 2
the injected steam heats the heat exchanger and residual fluid to a target cleaning temperature range
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Disclosed are methods and apparatus for cleaning heat exchangers and similar vessels by introducing chemical cleaning solutions and/or solvents while maintaining a target temperature range by direct steam injection into the cleaning solution. The steam may be injected directly into the heat exchanger or into a temporary side stream loop for recirculating the cleaning solution or admixed with fluids being injected to the heat exchanger. The disclosed methods are suitable for removing metallic oxides from a heat exchanger under chemically reducing conditions or metallic species such as copper under chemically oxidizing conditions. In order to further enhance the heat transfer efficiency of heating cleaning solvents by direct steam injection, mixing on the secondary side of the heat exchanger can be enhanced by gas sparging or by transferring liquid between heat exchangers when more than one heat exchanger is being cleaned at the same time.