Mechanical CO2 Stripping for Water Decalcification
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Solution Overview
Problem
Current methods for decalcifying water in the paper industry are costly and inefficient, with high operational costs due to calcification of equipment and insufficient crystallisation surfaces, and existing systems require chemicals and high investments, making them unsustainable and economically unfeasible for large-scale water reuse.
Innovation Solution
A method using mechanical surface CO2 stripping in a series of reactors with seed crystals to remove CaCO3 from water, driven by an electrically powered rotor causing turbulent motion, without the use of compressed air or chemicals, which maintains low operational and investment costs and produces pure CaCO3.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If compressed air is used to contact with water for CO2 emission and CaCO3 precipitation, then decalcification is achieved, but operational costs increase due to calcification of aeration elements and tanks
Solution Approach 1:
The invention extracts the harmful function of compressed air aeration elements and tank surfaces that become calcified, replacing them with suspended seed crystals that serve as crystallisation surfaces without becoming part of the fixed infrastructure. This separates the decalcification function from surfaces that would otherwise require maintenance.
Solution Approach 2:
The seed crystals serve themselves by continuously providing crystallisation surfaces for CaCO3 precipitation. The crystals grow by accumulating CaCO3 and are then removed with the sludge, automatically regenerating the crystallisation surfaces without external intervention or maintenance.
2Quantity of substance
If conventional decalcification methods are used, then CaCO3 is removed from water, but investment and operational costs are high
Solution Approach 1:
The invention uses inexpensive seed crystals that are continuously removed with sludge, effectively replacing expensive conventional decalcification equipment with low-cost, disposable crystallisation carriers that regenerate automatically.
Solution Approach 2:
The invention changes the physical state and distribution of crystallisation surfaces from fixed (tank walls, aeration elements) to suspended particulate form, fundamentally altering how decalcification occurs and enabling lower cost implementation.
3Device complexity
If insufficient crystallisation surface is provided, then decalcification process is simplified, but CaCO3 precipitation efficiency is reduced
Solution Approach 1:
The invention creates numerous copies of crystallisation surfaces through suspended seed crystals distributed throughout the water volume, replacing the need for large fixed surfaces while maintaining high precipitation efficiency through volumetric distribution.
4Quantity of substance
If biologically purified water is reused without further treatment, then fresh water use is reduced, but calcium deposits cannot be accepted at critical points
Solution Approach 1:
The invention converts the harmful effect of dissolved CO2 (which causes CaCO3 precipitation and deposits) into a beneficial process by controlling CaCO3 crystallisation on suspended seed crystals, transforming the problem of calcium deposition into an controlled precipitation process that produces clean effluent.
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 effectively reduces calcium carbonate concentration in water, achieving high-quality softening that can replace fresh water, with low maintenance and energy requirements, and is sustainable, allowing for the reuse of biologically purified wastewater in the paper industry.
Implementation Method 1
treating water in a reactor vessel by mechanical surface CO2 stripping with an electrically driven rotor, thereby causing a turbulent motion
Implementation Method 2
introducing and maintaining a high seed crystal concentration in the water to be treated
Data Source
Figure 1A~1B
Figure 2
AI summary
The present invention concerns a method for removing lime from water, comprising the steps of: a) treating water in a reactor vessel by mechanical surface CO2 stripping; b) conducting the treated water to a next reactor vessel; c) treating the treated water with mechanical surface CO2 stripping in the next reactor vessel; and d) optionally repeating steps b) and c). Preferably, the concentration of seed crystals in the reactor(s) is kept at 5-100 g/l, preferably at 20 to 80 g/l and most preferably at 30-50 g/l. Also, the invention comprises an apparatus for carrying out such a method.