DTB — Draft Tube Baffle Crystallizer
Product quality first. An internal draft tube directs circulation while a baffle separates the growth zone from a fines-removal zone — classified-fines destruction produces large crystals (0.5–2 mm) with a narrow distribution that centrifuges easily and carries little mother liquor.
Four Numbers That Define DTB
Reference ranges under typical operating conditions on inorganic salt systems.
Grow Inside the Draft Tube, Remove Fines at the Baffle
Two zones, two jobs: the draft tube circulates the growing crystal population; the baffle annuity classifies it — fines leave, product stays.
Simplified DTB Flow Diagram
Slurry → Draft tube (1–2 m/s growth circulation) → Baffle annulus (0.5–1 m/s fines elutriation) → Fines dissolved/removed → Product crystals to discharge
Fines removed at the baffle are dissolved and recycled — the crystal population that remains grows into the narrow, large-crystal distribution DTB is known for.
Draft Tube Circulation
The internal draft tube directs flow at a controlled 1–2 m/s — the growing population stays suspended and mixed.
Growth Zone
Inside the draft tube, crystals grow under controlled supersaturation delivered by the Dimension C method of the plant.
Fines Removal Zone
The baffle annulus runs at 0.5–1 m/s: fine crystals are elutriated out, dissolved and returned — keeping them out of the product.
Classified Discharge
Product crystals leave at 0.5–2 mm — narrow PSD, easy centrifugation, little mother-liquor carryover.
FC vs. DTB vs. Oslo
Three vessel configurations, three priorities: FC puts engineering reliability first, DTB puts product quality first, Oslo puts crystal quality first.
d50 ranges reflect typical operating distributions on inorganic salt systems; actual PSD depends on residence time, fines management, seed control and the cooling/evaporation profile.
Where DTB Is the Standard Configuration
Chemical systems where large crystals with narrow PSD justify classified growth.
Chemical-configuration mapping from the crystallizer-type technical reference; final selection requires solubility data, impurity profiling and crystallization trials.
When to Pick DTB — and When Not To
DTB is the answer when product spec (PSD, centrifuge yield, mother-liquor carryover) is the priority and the feed is not extreme.
DTB is a Dimension D crystal growth configuration — the selection logic is explicit: product quality first, with stable crystal size, easy centrifugation and minimal mother-liquor carryover. It pairs with any Dimension C supersaturation method (evaporative, cooling, vacuum cooling). d50 and PSD outcomes depend on residence time, fines-management settings, slurry density (15–30 wt% band) and the driving-force profile. All figures are indicative ranges for preliminary screening, not a process guarantee.
DTB Crystallizer Questions We Answer Most
Recurring questions from engineers choosing a growth configuration.
It creates a low-velocity annulus (0.5–1 m/s) where fine crystals are elutriated out of the growth zone, dissolved and recycled. Removing fines continuously is what keeps the product distribution narrow — without it, the fines compete for solute and the PSD widens.
DTB delivers 0.5–2 mm with classified-fines removal — preferred when downstream centrifugation throughput is the priority. Oslo produces larger crystals (1–5 mm) with very low fines — preferred when crystal size and purity matter most. Both reach high purity; the choice depends on which downstream property you value.
Good but not FC-grade. DTB tolerates moderate scaling tendency; on high-TDS, heavily scaling mixed-salt liquors, FC's high-velocity loop is the reliable choice. Putting classified equipment on an unstable feed trades availability for PSD you may never collect.
The 15–30 wt% band is a primary size lever — higher slurry density gives more crystal surface area, lower per-crystal supersaturation and larger product. It is one of the main operating variables, tuned against the fines-removal rate.
Screening a DTB Configuration?
Send us the chemical system, target PSD and purity, and feed conditions. We will return a preliminary DTB vs. FC vs. Oslo screening with indicative crystal size — not a brochure.