A DTB crystallizer and an OSLO crystallizer manage circulation and crystal growth differently. Choose around the actual feed and product requirement, rather than an equipment name or a promised crystal size. MOS has separate Draft Tube Baffle (DTB) and OSLO external-circulation Product pages. Their qualitative process descriptions are a starting point for engineering review; they do not establish capacity, yield or a guaranteed size distribution for your project.
Separate the circulation path from the crystal-growth zone
The MOS DTB record identifies internal circulation through a draft tube and a settling/classification zone. The OSLO record identifies external clear-liquor circulation and a suspended crystal bed. GEA’s technical descriptions similarly distinguish a DTB arrangement from fluidized-bed growth in an OSLO design. The absence of mechanical circulation of the OSLO crystal bed does not mean the whole installation has no circulation pump. Ask the supplier to explain which stream is pumped, where crystals circulate and how fines are classified or removed.
| Decision input | DTB review | OSLO review |
|---|---|---|
| Circulation | Internal draft-tube circulation and its effect on the suspension | External liquor circuit and stable crystal-bed operation |
| Classification and fines | Baffle/settling arrangement and proposed fines handling | Bed classification, clarification and proposed fines handling |
| Product requirement | Target distribution and permitted attrition, confirmed by testing | The same target and acceptance method, not a generic size promise |
| Operating basis | Feed, solubility, temperature/pressure and control concept | The same feed/design basis and utility boundaries |
| Integration | Discharge, separation/washing, materials and cleaning access | The same downstream and maintenance requirements |
Define comparable feed and acceptance data
Provide composition, concentration and representative variability, including impurities or solids that may affect the process. Supply available solubility data over the proposed operating range, or agree how missing data will be measured. Specify whether crystallization is driven by evaporation, cooling or another confirmed route. Document available heating/cooling, pressure or vacuum conditions and utility boundaries. These are project inputs, not operating limits inferred from the catalogue.
Describe the required crystal-size distribution and how it will be measured, acceptable fines/attrition, product purity and downstream separation, washing and moisture requirements. A distribution specification is more useful than “large crystals.” Request an engineering explanation of supersaturation control, residence/classification behavior and fines treatment for the actual feed. No generic comparison establishes that one design always gives a better distribution, yield or cleaning interval.
Use pilot evidence to qualify the proposal
Agree representative feed samples, analytical and sampling methods, run duration and acceptance criteria before a trial. Review stability over the defined run, not only an attractive sample from one moment. Record feed variation and material balances so the result can support a design discussion. State how downstream separation and cleaning will be evaluated. A pilot result supports a bounded proposal; the supplier must confirm scale-up assumptions, capacity, utilities, materials and the final process guarantee for the project.
Request an engineering quotation with the process data
Begin at the DTB Product page and include the OSLO comparison page when asking for an alternative process proposal. Provide material composition and solubility data, feed/production basis, batch or continuous requirement, crystal distribution and moisture/quality targets, temperature/pressure and utilities, contact-material/corrosion requirements and cleaning needs. Include destination, installation/layout constraints and sample/pilot acceptance. Request a confirmed process basis, interface drawings and exclusions; do not treat the page as a ready-made capacity or utility specification.
Crystallizer selection FAQ
Does OSLO mean there is no circulation pump?
No. Crystal-bed growth without mechanically circulating the bed is different from eliminating the liquor-circulation pump. Verify the proposed flow arrangement.
Which design guarantees larger or more uniform crystals?
Neither equipment name provides a project guarantee. Use feed-specific engineering and an agreed sampling/pilot acceptance method to assess the target distribution.
Is feed rate enough to select the machine?
No. Composition, solubility, impurities, product distribution, process route, utilities, materials, cleaning and downstream requirements also affect the selection.
What should accompany a DTB/OSLO RFQ?
Feed and solubility data, production and operating basis, crystal/quality targets, separation and cleaning needs, contact materials, available utilities, destination/layout and an agreed sample or pilot plan.