A steam distillation unit co-distils heat-sensitive high-boiling organic compounds with water by injecting steam directly into the heated still pot enabling distillation at temperatures of 70–95°C (below 100°C at atmospheric pressure) because the mixture boils when the sum of partial vapour pressures equals atmospheric pressure. Processing 20–5,000 L batches, it is the standard isolation method for essential oils, aromatic compounds, and pharmaceutical herbs where direct high-temperature heating would cause thermal degradation of the target product.
Steam (0.5–2 bar saturated) is injected through a sparger ring at the still pot base the steam-organic mixture in the pot establishes a combined vapour pressure exceeding atmospheric at temperatures below 100°C. Both steam and organic vapour rise together to the condenser; the heterogeneous condensate (two immiscible phases organic oil and water) separates by density in a Florentine flask or decanter. The lighter essential oil layer overflows as the product fraction; separated water is either discarded or recirculated as cohobation water to recover dissolved organics. Yield is 0.5–5% oil from dry herb weight.
Challenges
Steam Consumption Exceeding Process Thermal Need
Direct steam injection dilutes still contents with condensate excessive water generation.
Foam Formation on Steam Injection into Herb Mass
Direct steam injection through herb bed generates persistent foam condenser flooding.
Condenser Capacity for High Steam Flow Rate
Large steam flow rate generates high condenser heat duty under sizing causes vapour breakthrough.
Oil-Water Emulsion in Florentine Flask
Some essential oils form partial emulsions clean oil/water phase separation not achieved.
Still Pot Fouling from Herb Residue and Charring
Extended distillation chars herb residue on heated still pot surfaces difficult cleaning.
Solutions
- Indirect Steam Heating Option (Jacketed Still Pot): Jacket steam heats through the pot wall no direct steam dilution of contents.
- Anti-Foam Additive (Food-Grade Silicone at 50 ppm): Pre-addition to herb mash prevents foam formation on steam injection start-up.
- Oversized Shell-and-Tube Condenser (1.5× Peak Steam Load): Excess condenser area handles maximum steam rate without vapour breakthrough.
- Inline Static Separator + Molecular Sieve Water Removal: Static separator removes bulk water; molecular sieve removes residual dissolved water from oil.
- Stainless Distillation Basket for Herb Loading and Removal: Perforated SS basket holds herb charge rapid removal and cleaning between batches.
Applications
- Food & Beverage: Essential oil extraction from coriander, fennel, clove, and food-grade herbs.
- Pharmaceutical: Medicinal herb active fraction isolation, camphor and menthol distillation.
- Cosmetics & Fragrance: Rose oil, lavender, eucalyptus, and peppermint essential oil production.
- Nutraceuticals: Plant-derived bioactive oil isolation, herbal extract aromatic fraction recovery.
- Aromatherapy: High-purity essential oil production for therapeutic and spa applications.
Models & Capacities
11C — Steam Distillation Unit (STD) — 20 L Lab to 5,000 L Large Production — 70–95°C — Steam 0.5–2 bar — Oil Yield 0.5–5% — Essential Oils & Heat-Sensitive Organics | |||||||||
Model | Scale | Still Pot Vol [L] | Steam Rate [kg/h] | Condenser Area [m²] | Op. Temp [°C] | Distillation Time [h/batch] | Oil Yield [%] | L × W × H [mm] | Weight [kg] |
STD-LAB-20 | Lab | 20 | 5 – 15 | 0.2 | 70 – 95 | 1 – 4 | 0.5 – 5 | 800 × 500 × 1,500 | 80 |
STD-PIL-100 | Pilot | 100 | 20 – 50 | 0.5 | 70 – 95 | 1 – 6 | 0.5 – 5 | 1,200 × 700 × 2,000 | 180 |
STD-PIL-500 | Pilot | 500 | 80 – 200 | 2.0 | 70 – 95 | 2 – 8 | 0.5 – 5 | 2,000 × 1,200 × 2,800 | 480 |
STD-PRD-1000 | Production | 1,000 | 150 – 400 | 4.0 | 70 – 95 | 2 – 8 | 0.5 – 5 | 2,800 × 1,500 × 3,500 | 950 |
STD-PRD-3000 | Production | 3,000 | 400 – 1,000 | 8.0 | 70 – 95 | 3 – 10 | 0.5 – 5 | 4,000 × 2,000 × 4,500 | 2,200 |
STD-LP-5000 | Large Prod | 5,000 | 600 – 1,500 | 12 | 70 – 95 | 4 – 12 | 0.5 – 5 | 5,500 × 2,500 × 5,000 | 4,500 |