Sludge Lance Alignment for Steam Generator Tube Cleaning
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Solution Overview
Problem
In pressurized water nuclear reactor steam generators, the narrow space between the divider plate and the inner row of tubes restricts effective sludge cleaning, making it difficult to align cleaning jets with the tube gaps for deep penetration and efficient removal of sludge deposits, which can lead to tube thinning and corrosion due to accumulated sludge.
Innovation Solution
A sludge lance with a mounting assembly and nozzle assembly that allows travel down the tube lane between the divider plate and the first row of tubes, featuring a reciprocally movable plunger to maintain position against the divider plate and an alignment tool for precise angular and linear alignment with the tube gaps, ensuring effective cleaning without recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spray nozzles are introduced along the center of the U-tubes to move sediment outward, then sediment can be transported to a suction port for disposal, but the narrow space between the divider plate and the inner row of tubes restricts effective sludge cleaning and makes it difficult to align cleaning jets with tube gaps
Solution Approach 1:
The sludge lance is designed with a movable and adjustable structure that allows it to be positioned and aligned dynamically within the narrow space between the divider plate and tubes. The lance can be reciprocated and angularly adjusted to maintain proper alignment with tube gaps during the cleaning operation, rather than being fixed in a static position.
Solution Approach 2:
The cleaning approach transitions from introducing nozzles along the center of U-tubes to using a lance that accesses the tube lane from the annular chamber side. This dimensional change in access approach allows the lance to engage tubes from a different spatial perspective, enabling alignment with tube gaps despite the narrow clearance constraints.
2Productivity
If high pressure fluid is applied for deep penetration into tube gaps, then sludge deposits can be effectively removed, but the reaction force from the spray may cause movement or misalignment of the nozzle
Solution Approach 1:
The sludge lance incorporates a reaction force counterbalancing mechanism where the high pressure fluid is directed against a counterwall or support surface that provides an opposing reaction force. This counterforce balances the spray reaction, preventing the nozzle from moving or becoming misaligned during operation while maintaining the high pressure needed for effective sludge removal.
Solution Approach 2:
A counterwall or support structure serves as an intermediary element between the high pressure fluid spray and the lance structure. This intermediary absorbs and redirects the reaction force, protecting the nozzle alignment while enabling deep penetration cleaning of tube gaps.
3Volume of moving object
If the lance is positioned close to the divider plate for access, then the narrow space can be utilized, but precise alignment with tube gaps becomes more difficult
Solution Approach 1:
The lance includes adjustable positioning mechanisms that allow fine-tuning of its angular and linear position. This dynamic adjustability enables precise alignment with tube gaps even when operating from the constrained space near the divider plate, as the lance can be calibrated to account for the limited access geometry.
Solution Approach 2:
The lance system incorporates alignment tools and adjustable parameters that allow operators to precisely control the lance's angular orientation and position. By changing these geometric parameters, the system achieves accurate alignment with tube gaps despite the restricted access space imposed by the divider plate proximity.
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
Enables efficient removal of sludge deposits by maintaining alignment and stability during high-pressure fluid application, preventing tube thinning and corrosion, and allowing for precise positioning of cleaning jets within the limited access space.
Implementation Method 1
a nozzle assembly positioned to direct a spray of high pressure fluid onto the tube sheet
Implementation Method 2
high pressure fluid emanating from the nozzle jets
Data Source
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AI summary
A sludge lance for a tube and shell steam generator that has a central divider plate that extends substantially the length of a central tube lane substantially bisecting a hand hole through which the tube lane can be accessed. The sludge lance has a nozzle with a spring biased, reciprocally movable plunger that extends against the divider plate and is locked in position by a stream of high pressure cleaning fluid that traverses the nozzle and exits through jets to clean sludge from between the tubes. An alignment tool with a swing arm indexes the jets to assure they are properly aligned with the tube rows and spaced from the divider plate.