1. Process Objective
Extract crude flaxseed oil from cleaned, conditioned flaxseed at a sustained throughput of 500 kg/hr (seed-in) while maintaining oil temperature ≤ 40 °C to preserve omega-3 (ALA) integrity and prevent oxidative degradation. The line combines mechanical cold pressing with solvent extraction of the press cake to maximise total oil yield (≥ 98 % recovery). This station is designated CCP-2 (Critical Control Point — Oil Quality & Solvent Safety).
2. Equipment Configuration & Flow Diagram
Flaxseed (cleaned)
│
▼
[ Pre-heat Conditioner ] ────→ [ SP-300 Screw Press ] ────→ Crude Oil (cold pressed)
│ │
▼ ▼
Press Cake ──────────────→ [ Flaker / Cake Breaker ] [ Plate Filter (30 µm) ]
│ │
▼ ▼
[ Hexane Extraction Vessel ] [ Polish Filter (5 µm) ]
│ │
▼ ▼
[ Miscella (oil+hexane) ] ──→ [ Evaporator ] ──→ [ Stripper ] ──→ Crude Oil to Holding
│ │
▼ ▼
[ Desolventiser / Toaster ] ──→ Meal (≤ 500 ppm hexane) [ N₂ Blanket Storage ]
3. Equipment Specifications
3.1 Pre-Heat Conditioner
| Parameter |
Value |
| Type |
Steam-jacketed screw, gentle |
| Throughput |
600 kg/hr (peak) |
| Temp. range |
35 – 55 °C (target 45 °C) |
| Residence time |
8 – 12 min |
| Heating medium |
Saturated steam @ 2 bar(g) |
| Material |
SS304 contact surfaces |
3.2 Screw Press — SP-300 (Cold Press)
| Parameter |
Value |
| Model |
SP-300 (or equivalent) |
| Rated capacity |
500 kg/hr (seed) |
| Motor power |
15 kW (TEFC, IE3) |
| Screw speed |
20 – 40 rpm (VFD controlled) |
| Oil temperature |
< 40 °C (CCP-2 limit) |
| Cake residual oil |
≤ 18 % (w/w) |
| Pressure at choke |
50 – 80 MPa |
| Cage bars |
Hardened alloy steel (52 HRC) |
| Gearbox |
Helical, oil-flooded |
| Nozzle / choke |
Hydraulic adjustable |
3.3 Flaker / Cake Breaker
| Parameter |
Value |
| Roll diameter |
300 mm |
| Roll length |
600 mm |
| Gap setting |
0.3 – 0.8 mm |
| Capacity |
350 kg/hr (cake in) |
| Motor |
5.5 kW |
| Parameter |
Value |
| Extractor type |
Perforated-belt / shallow-bed |
| Capacity |
350 kg/hr (cake/flake) |
| Solvent |
Commercial hexane (BP 65–70 °C) |
| Solvent-to-solid ratio |
1.0 – 1.2 : 1 (w/w) |
| Extraction temp. |
50 – 60 °C |
| Miscella conc. |
20 – 25 % oil |
| Residual oil in meal |
≤ 1.0 % (w/w) |
| Material |
SS304 (all wetted parts) |
3.5 Evaporator (Oil Recovery)
| Parameter |
Value |
| Type |
Falling-film evaporator |
| Heating surface |
12 m² |
| Steam consumption |
180 kg/hr @ 3 bar(g) |
| Vacuum level |
−0.85 bar(g) |
| Hexane in oil out |
≤ 1 000 ppm (to stripper) |
3.6 Stripper (Final Desolventising)
| Parameter |
Value |
| Type |
Packed column + reboiler |
| Vacuum level |
−0.92 bar(g) |
| Steam sparge |
Live steam, 15 kg/hr |
| Hexane in crude oil |
≤ 50 ppm (food grade) |
| Oil temp. out |
60 – 70 °C → cooled to 35 °C |
3.7 Desolventiser / Toaster (Meal)
| Parameter |
Value |
| Type |
DTDC (Desolventiser-Toaster-Dryer-Cooler) |
| Capacity |
250 kg/hr meal |
| Residual hexane |
≤ 500 ppm |
| Steam injection |
100 kg/hr @ 3 bar(g) |
| Meal temp. out |
≤ 50 °C (after cooling) |
3.8 Plate Filter (Cold Press Oil)
| Parameter |
Value |
| Type |
Horizontal plate & frame |
| Filtration area |
8 m² |
| Mesh size |
30 µm (primary) |
| Max pressure |
6 bar |
| Material |
SS304 plates, food-gaskets |
| Capacity |
250 L/hr (oil) |
3.9 Polish Filter
| Parameter |
Value |
| Type |
Bag / cartridge (5 µm) |
| Housing |
SS304, 2 × 7-element |
| Capacity |
250 L/hr |
| Design pressure |
10 bar |
3.10 Nitrogen Generator (Blanket & Purging)
| Parameter |
Value |
| Technology |
PSA (Pressure Swing Adsorption) |
| Purity |
99.9 % N₂ |
| Capacity |
20 Nm³/hr |
| Dew point |
−40 °C |
| Air connection |
6 bar(g) instrument air |
| Usage |
Headspace blanket on oil tanks + hexane system inerting |
| Metric |
Target |
Monitoring Method |
| Cold press throughput |
500 ± 25 kg/hr |
Load cell (in-feed) |
| Oil temperature (CCP-2 limit) |
≤ 40 °C |
In-line RTD (PID to VFD) |
| Cold press oil yield |
≥ 72 % |
Mass balance (seed vs oil) |
| Total oil recovery (press+extr.) |
≥ 98 % |
Mass balance |
| Residual oil in meal |
≤ 1.0 % (w/w) |
Soxhlet extraction (daily) |
| Hexane in crude oil |
≤ 50 ppm |
GC-FID (per batch) |
| Hexane in meal |
≤ 500 ppm |
GC-FID (per shift) |
| Oil clarity (cold press) |
NTU < 10 |
Turbidimeter (after polish) |
5. HACCP — CCP-2 Integration
| CCP |
Hazard |
Critical Limit |
Monitoring |
Corrective Action |
| 2a |
Oil temp. exceeds 40 °C→ ALA degradation, PV rise |
Oil outlet temp < 40 °C |
Continuous RTD, logged |
Reduce screw speed / feed rate; inspect cooling jacket |
| 2b |
Hexane leakage → fire / explosion |
LEL < 25 % in atmosphere; hexane in oil ≤ 50 ppm |
Fixed LEL gas detector (4 pts) |
Emergency vent / deluge; stop feed; evacuate |
| 2c |
Oxidation during storage |
Headspace O₂ ≤ 2 % |
O₂ analyser on tank |
Purge with N₂; inspect seal |
- Solvent safety: All electrical equipment in hexane zone rated Ex d IIB T4 (ATEX / IECEx). Bonding / grounding checked daily. Fixed LEL monitors at extractor, evaporator, and DTDC. Emergency shut-off valves (ESD) at hexane tank farm. Fire deluge system auto-activates at 20 % LEL.
6. Maintenance Schedule
| Component |
Frequency |
Activity |
| Screw press worm & cage |
Weekly |
Visual wear check; measure bar gap |
| Screw press gearbox |
2 000 hr |
Replace oil (ISO VG 460); inspect bearings |
| Plate filter |
Per cycle |
Change plates / gaskets when ΔP > 3 bar |
| Polish filter bags |
Per batch / 40 hr |
Replace 5 µm bags |
| Evaporator / Stripper |
Monthly |
Inspect tubes for fouling; clean with hot hexane |
| LEL / gas detectors |
Quarterly |
Bump-test with calibration gas |
| N₂ generator |
Semi-annual |
Replace carbon bed filters; check O₂ analyser |
| All motors |
6 months |
Grease bearings (NLGI 2), check alignment |
7. Spare Parts Inventory (Minimum Stock)
| Part |
Qty |
Supplier Reference |
| Screw press worm assembly |
1 |
SP-300-WORM (OEM) |
| Cage bars (set of 12) |
1 |
SP-300-BAR-SET |
| Plate filter gaskets (set) |
2 |
PF-8-GSK |
| Polish filter bags (5 µm, 7") |
50 |
FB-5-70 |
| Hexane pump mechanical seal |
2 |
MP-25-SEAL |
| RTD sensor (PT100, 3-wire) |
3 |
RTD-PT100-316 |
| LEL sensor head |
1 |
GD-LEL-MK4 |
| N₂ generator O₂ analyser cell |
1 |
PSA-O2-CELL |
8. Utility Requirements
| Utility |
Connection |
Peak Demand |
| Electrical |
400 V, 3-phase, 50 Hz |
55 kVA |
| Steam |
3 bar(g) saturated |
300 kg/hr |
| Cooling water |
30 °C supply, ΔT 10 °C |
5 m³/hr |
| Instrument air |
6 bar(g), oil-free |
30 Nm³/hr |
| N₂ |
4 bar(g), 99.9% |
20 Nm³/hr |
| Drainage |
Chemical-resistant |
2 m³/hr (condensate + cooling) |
9. Safety & Compliance
- ATEX Zone 1 (extractor room, hexane pump area): all Ex d IIB T4 equipment.
- Grounding: Continuous conductive floor; all equipment bonded ≤ 10 Ω earth.
- Fire: Fixed foam deluge + dry chemical extinguishers (Class B).
- Lockout/Tagout: LOTO procedure on screw press hydraulic choke and hexane pumps.
- PPE: Flame-retardant coveralls, safety glasses, hexane-resistant gloves in solvent area.
Document Owner: Process Engineering Manager
Revision: 1.0
Date: 2026-07-20
CCP-2 Validated: Production Manager / HACCP Team