Polyacrylic Acid Scale Removal in Boilers
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Solution Overview
Problem
Existing methods for removing scale in steam generation facilities during boiler operation face challenges, particularly with chelating agents causing corrosion of boiler materials, leading to productivity losses and increased cleaning costs.
Innovation Solution
Adjusting the pH of boiler water to 11.3 or more and adding polyacrylic acid or its salt, with a weight average molecular weight within a specific range, to effectively remove scale deposits without using chelating agents, thereby preventing corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chelating agents (EDTA, NTA, etc.) are added into boiler water to remove scale during operation, then scale removal efficiency is improved, but corrosion of boiler iron base material occurs
Solution Approach 1:
The patent changes the chemical parameters by replacing chelating agents with polyacrylic acid or its salts, and adjusts the pH parameter to 11.3 or higher to achieve effective scale removal without corrosion. This parameter change transforms the chemical environment to be both effective for scale removal and safe for boiler materials.
Solution Approach 2:
The patent uses polyacrylic acid or its salts as a replaceable chemical agent that can be continuously added and discharged with blow-down water, eliminating the need for expensive chemical cleaning operations and boiler shutdowns. The agent is consumed and removed with the discharged water, providing continuous scale removal capability.
2Reliability
If full blowing-down and chemical cleaning are performed to remove scale deposition, then scale is effectively removed, but boiler operation is stopped and productivity is impaired
Solution Approach 1:
The patent implements continuous scale removal by adding polyacrylic acid or its salts to the boiler water during operation. The agent continuously disperses and removes scale components as they form, maintaining continuous boiler operation without interruption for cleaning, thus preserving productivity while ensuring scale removal effectiveness.
3Reliability
If scale dispersant is added to inhibit scale deposition, then scale adhesion is prevented, but additional cleaning costs are generated and thermal efficiency reduction occurs
Solution Approach 1:
The patent changes the water chemistry parameters by adjusting pH to 11.3 or higher and using polyacrylic acid or its salts, which effectively disperse scale components and prevent adhesion. This parameter change reduces scale deposition on heating surfaces, maintaining thermal efficiency while providing scale inhibition capability.
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 method allows for efficient scale removal during boiler operation without corroding the boiler, reducing downtime and cleaning costs, while maintaining thermal efficiency and preventing scale deposition.
Implementation Method 1
a polyacrylic acid having a weight average molecular weight that is 0.70 to 2.00 times a reference weight average molecular weight as calculated from the following calculation formula (1), or a salt thereof, is added in accordance with the pH value of the boiler water during the operation of a boiler, thereby removing a scale deposited on the inside of a boiler vessel
Implementation Method 2
a pH of boiler water is adjusted to 11.3 or more, and a polyacrylic acid having a weight average molecular weight that is 0.70 to 2.00 times a reference weight average molecular weight... is added... thereby removing a scale deposited on the inside of a boiler vessel without corrosion failure of the boiler
Data Source
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AI summary
Provided is a method for removing a scale in a steam generation facility, whereby it becomes possible to remove a scale deposited on the inside of a boiler vessel during the operation of a boiler without causing corrosion of the boiler. A method for removing a scale in a steam generation facility is disclosed, wherein in the steam generation facility, a pH of boiler water is adjusted to 11.3 or more, and a polyacrylic acid having a weight average molecular weight that is 0.50 to 2.00 times a reference weight average molecular weight as calculated from the following calculation formula (1), or a salt thereof, is added in accordance with the pH value of the boiler water during the operation of a boiler, thereby removing a scale deposited on the inside of a boiler vessel: Reference weight average molecular weight=-8462×pH value-11.3+61538