Vertical Crystallizing Tank with Concentric Cooling Coils
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Solution Overview
Problem
The nitro-phosphate process for calcium nitrate production faces inefficiencies in crystallization time, limiting process capacity and efficiency, as existing crystallization technologies do not effectively utilize multiple banks of cooling coils without clogging and reducing heat transfer efficiency.
Innovation Solution
A method and apparatus utilizing a vertical crystallizing tank with three concentric banks of cooling coils and an agitator to achieve optimal heat transfer, allowing for efficient crystallization of calcium nitrate tetrahydrate by circulating a cooling fluid at controlled temperatures and agitation speeds, thereby optimizing heat transfer and maintaining cooling fluid efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple banks of cooling coils are used to increase cooling capacity, then crystallization efficiency is improved, but heat transfer efficiency deteriorates due to clogging
Solution Approach 1:
The cooling system is divided into three separate concentric banks of cooling coils (first, second, and third banks) arranged at different radial distances from the central axis. Each bank operates independently with its own heat transfer surface, allowing the system to provide substantial cooling capacity while maintaining adequate heat transfer efficiency in each individual bank, thus preventing the clogging issues that would occur in a single large-scale cooling system
2Power
If three concentric banks of cooling coils are used, then cooling capacity is increased, but device complexity increases
Solution Approach 1:
The three banks of cooling coils are arranged concentrically, with each bank nested within the space defined by the others. The first bank is at a first radial distance, the second bank at a second radial distance, and the third bank at a third radial distance, creating a compact nested structure that maximizes cooling surface area within a limited volume while maintaining a relatively simple overall apparatus design
3Power
If cooling fluid is circulated through multiple banks of coils, then heat transfer is enhanced, but energy consumption increases
Solution Approach 1:
The cooling fluid circulation system is designed to continuously circulate cooling fluid through all three banks of cooling coils in a coordinated manner. This continuous circulation maintains optimal heat transfer efficiency throughout the crystallization process, ensuring that the enhanced cooling capacity provided by the three banks is fully utilized without unnecessary energy consumption from intermittent operation
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 enhances cooling capacity and efficiency, allowing for faster crystallization and effective reuse of cooling fluid, reducing energy consumption and enabling flexible operation of crystallizing tanks.
Implementation Method 1
circulating a cooling fluid through the banks of cooling coils
Implementation Method 2
concentric banks of cooling coils running alongside each other and parallel to the axis running through the centers of the circular cross section
Implementation Method 3
an agitator equipped with paddles fixed to its rotation axis which runs through the centers of the two circular bases of the cylindrical section, driven by an agitator motor; rotating the agitator such that a minimum heat transfer is achieved
Implementation Method 4
The mixture is cooled to a temperature range, e.g., from −20° C. to 10° C., upon which the calcium nitrate crystallizes as calcium nitrate tetrahydrate
Implementation Method 5
the calcium nitrate crystallizes as calcium nitrate tetrahydrate and can be separated from the phosphoric acid
Data Source
AI summary
A method for crystallizing calcium nitrate from an aqueous calcium nitrate composition including from 6 to 12 weight % nitric acid, from 11 to 17 weight % phosphoric acid, and from 36 to 49 weight % dissolved calcium nitrate, which aqueous composition is optionally directly obtainable from digesting phosphate rock in nitric acid. The method includes filling at least one vertical crystallizing tank through an inlet with the aqueous calcium nitrate composition. The crystallizing tank includes a vertical cylindrical section, a first inlet, a first outlet, a second inlet, three concentric banks of cooling coils, an agitator, and a temperature measurement device. The method includes circulating through the banks of cooling coils a cooling fluid, having an initial temperature ranging from −40° C. to −5° C., and rotating the agitator such that a minimum average heat transfer of 400 W/m2·K is achieved on the cooling coil the most distant from the agitator.