Alkali Sulfite Formate Derouging Solution for Stainless Steel
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Solution Overview
Problem
Current derouging methods for stainless steel surfaces in pharmaceutical and food industry piping systems are hazardous, expensive, and environmentally harmful, with existing pH-neutral solutions often failing to completely remove rouging deposits without damaging the surface.
Innovation Solution
An aqueous cleaning solution comprising alkali sulfite and alkali formate in specific molar ratios and pH ranges, acting as a complexing reducing agent and buffering agent, respectively, effectively removes rouging deposits on stainless steel surfaces without causing harm to humans or the environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If concentrated mineral acids (sulfuric acid, hydrochloric acid) are used for derouging, then effective removal of rouging deposits is achieved, but handling dangers and corrosive effects increase significantly
Solution Approach 1:
The invention changes the pH parameter from highly acidic (concentrated mineral acids) to pH-neutral range (6.5-7.5), and changes the chemical composition from strong oxidizing acids to a combination of organic reducing agents/complexing agents and inorganic reducing agents. This parameter transformation maintains derouging effectiveness while eliminating handling dangers and corrosive effects.
Solution Approach 2:
The invention replaces expensive, hazardous concentrated mineral acids with cheaper, safer substances (organic reducing agents, inorganic reducing agents, wetting agents) that can be handled without special precautions. These alternative chemicals are less hazardous and can be disposed of more easily, reducing environmental and safety concerns.
2Object-affected harmful factors
If pH-neutral cleaning solutions are used for derouging, then safety and environmental compatibility improve, but cleaning effectiveness decreases in certain situations
Solution Approach 1:
The invention creates a composite cleaning solution combining multiple functional components: organic reducing agents (for reduction of iron oxides), complexing agents (for binding and solubilization of metal ions), inorganic reducing agents (for additional reduction capability), and wetting agents (for surface penetration and coverage). This composite formulation achieves both safety and effective cleaning by synergistic action of different substances.
Solution Approach 2:
The cleaning solution is designed to perform multiple functions simultaneously: reduction of rouging deposits, complexing with metal ions, wetting of surfaces, and buffering pH. This multi-functional approach ensures that a single pH-neutral formulation can handle various derouging situations effectively, replacing the need for multiple specialized treatments.
3Ease of operation
If existing pH-neutral derouging agents are used, then handling safety improves, but complete removal of rouging deposits without surface damage is not always achieved
Solution Approach 1:
The invention applies preliminary action by first using organic reducing agents and complexing agents to prepare the surface and convert rouging deposits into more soluble forms, then following with inorganic reducing agents to complete the reduction. This sequential preliminary treatment ensures complete removal while protecting the underlying stainless steel surface from damage.
Solution Approach 2:
The complexing agents act as intermediaries between the reducing agents and the iron oxide deposits. They bind to metal ions during the reduction process, preventing re-oxidation and facilitating complete removal of rouging while protecting the base metal surface. This intermediary action ensures controlled and complete derouging without surface damage.
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 solution provides a safe, cost-effective, and environmentally friendly method for removing rouging deposits on stainless steel surfaces, maintaining a stable electrochemical potential for effective derouging while being suitable for various steel types and process conditions.
Implementation Method 1
The first component acts as a complexing reducing agent
Implementation Method 2
The first component acts as a complexing reducing agent
Implementation Method 3
the second component acts as a buffering agent
Data Source
AI summary
An aqueous cleaning solution for removing rouging deposits on media-contacted surfaces of stainless steels comprises a first component and a second component. The first component is an alkali metal sulphite and the second component is an alkali metal formate, the concentrations thereof being such that formate is present relative to sulphite in a molar ratio of 1.5 to 4.2, and that the pH of the cleaning solution is 4.0 to 4.8. For preparation of the aqueous cleaning solution, an aqueous solution of an alkali metal hydroxide is initially charged, then a first amount of concentrated aqueous formic acid is mixed in in an excess so as to establish a pH of 3.5 to 4.5, then a second amount of solid alkali metal sulphite is mixed in according to the sulphite concentration to be established, resulting in a pH of 5.5 to 6.5, and finally a third amount of concentrated aqueous formic acid is mixed in until a pH of 4.0 to 4.8 is attained.