Crystallization technology
DTB Crystallizers
A crystallizer designed to produce coarse crystals with a narrow size distribution – limited secondary nucleation and an efficient fines destruction promoting crystal growth.
DTB Crystallizers have been studied widely in crystallization theory and can be modelled with accuracy. Its distinct zones of growth and clarified mother liquor make it possible to define in terms of kinetic parameters and thus, growth and nucleation rates can be determined.
These features make the DTB crystallizer very suitable to mathematical description and subject to good operating control.
Particular features:
- Low secondary nucleation due to low mechanical energy input (internal circulation)
- Removing of fines (d < dcritical) from the internal baffle
- Efficient fines destruction due to heating and/or dilution
- Production of large size crystals (up to 3mm)
- No or little heat make-up (fine dissolution)
- Controlled residence time for optimal growth
- Long operating cycle with limited encrustation
- Appropriate for vacuum cooling (no external loop) and evaporative crystallization (moderate capacities)
- Compact arrangement
Working Principle
Working Principle of DTB CrystallizersThe Draft Tube Baffle Crystallizer (DTB) consists of five basic elements:
- The crystallizer vessel. Provides most of the active volume dictated by the residence time requirements and enables a proper disengagement of process vapors.
- The bottom-flanged impeller pump. Provides sufficient internal circulation rate along the draft-tube to operate the crystallizer under optimal supersaturation conditions. Reduced mechanical energy input leads to minimized secondary nucleation by crystal attrition.
- The baffle. Controls the crystal population by separating fine crystals (to be dissolved by heating or dilution) from coarse crystals (to further growth).
- The circulation pump. Provides sufficient external circulation rate to operate the crystallizer under optimal superheating conditions for fines redissolution. Typically, axial-flow propeller pumps are used.
- The heat exchanger. Supplies the required thermal energy to the crystallizer for the desired evaporation rate. Designed to minimize encrustations.
It is specially designed to produce coarse crystals with narrow size distribution. The DTB can produce large size particles (up to 3mm) due to its gentle agitation of growing crystals with very limited breakage. It has a controlled residence time for optimal growth and a long operating cycle with limited encrustations.
Slurry of a desired solid density is circulated within the draft tube crystallizer impulsed by a bottom-flanged impeller pump. A DTB Crystallizer´s mechanical energy input is lower than that of a FC crystallizer thanks to a reduced pressure drop that limits attrition and therefore, secondary nucleation.
Crystals of a smaller and specific size are withdrawn from the baffle zone and are dissolved in the external circulation loop because of the clarified solution´s superheating.
Said superheating is relieved through evaporation and the evolving supersaturation leads to the growth of the suspended crystals. The evaporated solvent is either conducted to the subsequent process steps or reused by applying a recompression system of choice.
Heating options for thermal separation plants
Downloads
Related Products
Forced Circulation Crystallizers
Simple in design and robust in operation. The working horse for industrial solution crystallization.
Oslo Crystallizers
Fluidized bed crystallizer with the ability to grow the largest crystals at elevated retention time.
Crystallization Test Centers
Available for product and feasibility trials with real samples and under real parameters. Either in GEA centers of excellence for crystallization or onsite thanks to our mobile units.
COMPACRYST®
Process and mechanical innovation. Compact and Monoblock Forced Circulation Crystallizer.
GEA Insights
The next era of food production with GEA NEXUS
Climate change and a growing world population put increased pressure on the energy-intensive food industry to feed more people without further impacting the planet. George Shepherd, GEA’s Global Technical Sustainability Manager, explains how GEA uses its engineering know-how to help processors produce more sustainably yet increase productivity.
Making milk production more sustainable for a growing world
The world's population is growing and with it demand for milk. Dairy is an essential component of many global diets. However, its production can be resource-intensive and impact the environment. GEA’s Christian Müller, Senior Director Sustainability Farm Technologies, sheds light on how technological innovations powered by GEA make milk production more efficient and profitable.
Clean machines safe food: The power of hygienic design
Every safe beverage and bite of food is a victory against invisible microbial threats – a battle shaped by a century of hygienic process design. With more than 100 years of engineering and hygienic design know-how, GEA sets the industry standard for processing equipment that protects food and saves lives.
