Modular Suspension Crystallizer Segmented Mixing and Scraping

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Solution Overview

Problem

Large suspension crystallizers face challenges in maintaining uniform scraping and mixing due to complex and costly designs, leading to issues like crystal agglomeration and poor heat transfer, making them unsuitable for high-throughput applications.

Innovation Solution

A modular sub-unit with a simple, cost-effective design featuring a central rotating axis for mechanical scraping and mixing, allowing for efficient mixing and scraping without complex equipment, and enabling easy manufacturing in various sizes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large suspension crystallizers are designed with complex mechanical systems (counter-rotating coaxial mixers, draft tubes) to improve mixing and scraping, then mixing and scraping performance is improved, but device complexity and manufacturing/maintenance costs increase steeply

Engineering Contradiction:
Improvemixing and scraping performanceVSAvoidmechanical system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The crystallizer is divided into multiple crystallization chambers (first, second, and optionally third chambers) arranged around the central axis. Each chamber can be independently controlled with its own scraper, allowing simplified individual units to achieve the overall mixing and scraping performance that previously required complex mechanical systems. The segmentation enables each chamber to function as an independent zone with optimized local conditions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from complex mechanical mixing systems to a geometric solution by arranging crystallization chambers in a radial pattern around a central axis. The multi-dimensional spatial arrangement of chambers (first chamber, second chamber, and optional third chamber) creates natural flow patterns and mixing zones without requiring complex mechanical mixers. This dimensional approach replaces mechanical complexity with geometric efficiency.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Power

If large surface area walls are used in large crystallizers to increase heat transfer capacity, then heat transfer capacity increases, but uniform scraping becomes difficult and expensive requiring custom-built large machining devices

Engineering Contradiction:
Improveheat transfer capacityVSAvoidwall machining precision
Core Design Contradiction:
PowerVSManufacturing precision

Solution Approach 1:

The total heat transfer surface is segmented into multiple smaller crystallization chambers, each with its own cooled surface. This segmentation allows each chamber to be manufactured with standard machining capabilities while maintaining high heat transfer capacity overall. The sum of the heat transfer areas of all chambers provides the required total capacity without requiring any single large surface to be precisely machined.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each crystallization chamber is designed with locally optimized dimensions and cooling surface characteristics. The first, second, and third chambers can have different geometries and cooling surface areas tailored to specific process requirements. This local optimization allows each chamber to achieve efficient heat transfer with standard manufacturing capabilities, avoiding the need for custom large-scale precision machining.

Inventive Principle:
Principle #3Local quality

3Productivity

If high concentration of crystallizing component is used in mother liquor to increase productivity, then productivity increases, but crystals strongly adhere to wall requiring perfect scraping to prevent crystal layer formation and heat transfer loss

Engineering Contradiction:
Improvecrystallization throughputVSAvoidscraping effectiveness
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The crystallizer is divided into multiple chambers (first, second, and optional third chambers) each with independent scraping capability. This segmentation ensures that crystal adhesion in one chamber does not affect others, and each chamber can be optimally scraped independently. The multiple scrapers working in parallel maintain effective crystal removal even at high concentrations where adhesion is strong.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mechanical scraping means in each chamber are designed to scrape the cooled surface before crystal layers can significantly build up and interfere with heat transfer. The continuous scraping action in each chamber prevents the formation of insulating crystal layers, maintaining efficient heat transfer even when operating at high crystallizing component concentrations that promote strong adhesion.

Inventive Principle:
Principle #10Preliminary action

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 modular sub-unit improves mixing and scraping performance, reduces crystal agglomeration, and simplifies maintenance and operation, making it suitable for larger systems and higher throughputs while minimizing manufacturing and operational costs.

Implementation Method 1

a) a cooling means (102) enabling the cooling down of the slurry at a cooled surface (1021), thereby promoting formation and growth of crystals

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 2

b) a mechanical scraping and/or mixing means (104) enabling scraping of the cooled surface (1021) and/or enabling mixing of a layer adjacent to the cooled surface (1021) together with a bulk of the slurry

Methodology Applied
Scientific EffectMechanical mixing: Stirring

Data Source

PatentEP3096852B1A modular sub-unit for a suspension crystallization system and a suspension crystallization process using said modular sub-unit
Publication Date: 2020.02.05 SULZER MANAGEMENT AG
  • EP3096852B1 patent drawingFigure 1A~1B
  • EP3096852B1 patent drawingFigure 2A~2B
  • EP3096852B1 patent drawingFigure 3

AI summary

A modular sub-unit 1 for the production of crystals in a suspension crystallization system 10 is disclosed comprising: a first crystallization segment 100, at least one further crystallization segment 110, a first mixing segment 200, optional further mixing segments 210, an inlet cap 300, an outlet cap 400, wherein the inlet cap 300 and outlet cap 400 are in fluid communication with any crystallization segments (100, 110) and any mixing segments (200, 210) present within the sub-unit 1; and a central rotating axis 500 for providing mechanical energy to the crystallization segments (100,110) and preferably the mixing segments (200, 210). The crystallization segments present in the sub-unit 1 are separated from each other by means of a mixing segment. The present invention also relates to a suspension crystallization system 10 comprising said sub-unit 1 and a suspension crystallization process making use of said sub-unit 1.