Modular Crystallisation Device Scraper Wear Reduction
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Solution Overview
Problem
Existing cooled disc column crystallizers experience downtime due to scraper wear from ice crystals forming on cooling disks, leading to reduced heat transfer and operational inefficiencies, as scrapers must be replaced frequently, disrupting the crystallization process.
Innovation Solution
A modular system with independent scraper actuators for each crystallization unit allows for selective removal and replacement of units without stopping the entire system, enabling continuous operation by keeping one unit submerged and operational while the other is serviced, and a scraper frame design that reduces deformation and wear during crystal scraping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scrapers are used to remove ice crystals from cooling disks, then heat transfer is improved, but scraper wear occurs leading to downtime
Solution Approach 1:
The system is divided into multiple independent crystallisation units (first unit and second unit), each with its own cooling disks and scrapers. This segmentation allows one unit to be serviced while the other continues operating, eliminating the need to stop the entire system for scraper replacement.
Solution Approach 2:
The scraper members are designed as replaceable components that can be individually serviced. When a scraper wears out on one crystallisation unit, it can be replaced without affecting the other units, allowing efficient recovery and continuous operation.
2Productivity
If multiple crystals form on crystallisation surface, then crystallisation efficiency is improved, but heat transfer is reduced due to ice crystal hardness
Solution Approach 1:
The scrapers continuously and periodically remove ice crystals from the cooling disks during operation. This periodic scraping action prevents excessive crystal buildup that would insulate the cooling surface, thereby maintaining heat transfer efficiency while allowing productive crystallisation to occur.
3Productivity
If scraper layer becomes too thick, then crystal formation is maintained, but scraper movement becomes impossible
Solution Approach 1:
The scrapers perform preliminary removal of ice crystals before they can accumulate to problematic thicknesses. By continuously scraping during the crystallisation process, the system prevents the formation of thick crystal layers that would impede scraper movement, maintaining both productivity and operability.
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 approach minimizes downtime and maintains continuous crystallization processes by allowing independent operation of scraper units and reducing scraper wear, thereby enhancing the efficiency and reliability of the crystallization system.
Implementation Method 1
A cooled disc column crystallizer may be used for forming ice and salt crystals in the salt-water mixture. The disks are cooled, and as such ice and salt crystals form on the outer surface of the disks.
Implementation Method 2
Crystallisation is a process in which a solid is formed, for example from a solution of salt in water. Crystallisation may be performed by heating the solution, thereby evaporating the water, or by cooling.
Implementation Method 3
a cooling fluid distribution network for circulating cooling fluid through the cooling body
Implementation Method 4
Scrapers are moved over the outer surface of the disks to prevent scaling and to improve heat transfer between the salt-water mixture and the disks.
Data Source
AI summary
A system is provided for performing crystallisation by cooling, comprising two crystallisation units, each of the two crystallisation units comprising a cooling body with a crystallisation surface for forming crystals on, and a scraper unit, comprising a scraping member arranged to be moved over the crystallisation surface for scraping crystals from the crystallisation surface and a scraper actuator for moving the scraping member over the crystallisation surface, wherein the scraper actuator of a first of the two crystallisation units can be actuated independently from a scraper actuator of a second of the two crystallisation units.