An en-masse drag chain conveyor uses a slow-moving (0.05-0.3 m/s) hardened steel or SS chain carrying transverse flight bars inside a fully enclosed rectangular casing — moving the bulk solid as a continuous en-masse slug filling the full casing cross-section rather than discrete flights. Processing 0.5-200 t/h of dry bulk solids (bulk density 100-2,000 kg/m3) over distances of 1-100 m, it provides gentle, low-attrition, dust-tight transfer for fragile pharmaceutical granules, food powders, and hygroscopic ingredients requiring zero particle breakage and zero dust emission.
The chain and flight assembly moves at 0.05-0.3 m/s; the bulk solid fills the full casing cross-section and moves forward as a mass — internal friction between particles and between the bulk and casing walls drives flow rather than flight-to-particle impact. Material enters through an inlet hopper; the filled cross-section travels to the discharge point where the chain turns around the head sprocket, releasing product by gravity. Fully enclosed casing provides dust-tight transfer with IP 54 minimum; optional pressure-tight designs handle nitrogen-blanketed or ATEX-classified powder transfer.
Challenges
Particle Attrition from Chain-to-Product Contact at Bends
Chain direction change at head/tail sprockets causes momentary impact on fragile granules.
Material Compaction in High Fill-Rate Operation
Over-feeding compacts the en-masse plug -- increases chain tension and motor load to trip point.
Chain Elongation and Tracking Drift Over Long Runs
Chain wear elongates pitch -- slack develops, chain jumps sprocket, causing conveyor stoppage.
Moisture Condensation in Enclosed Casing on Hygroscopic Powder
Temperature differential between cold casing wall and warm powder generates condensation.
CIP of Fully Enclosed Casing Cross-Section
Rectangular casing dead corners and chain assembly geometry restrict CIP spray coverage.
Solutions
- Radiused Casing Corners at Head/Tail Sprocket (R >= 3x Particle Size): Large corner radius reduces impact velocity at direction change -- granule attrition <0.5%.
- Gravimetric Feed Controller (Loss-in-Weight Feeder, +-2%): Mass-flow-controlled inlet limits fill to 85% of casing cross-section -- prevents compaction.
- Auto-Tensioning Tail Sprocket (Spring or Hydraulic, +-50 mm): Automatic tensioner compensates chain elongation -- maintains correct pitch engagement.
- Insulated Casing with Nitrogen Blanketing Port: 50 mm PUF insulation prevents condensation; N2 blanket port maintains inert atmosphere.
- Full-Bore Access Doors Every 3 m + Internal CIP Spray Bar: Hinged full-bore doors allow manual and spray access; CIP bar covers full casing length.
Applications
- Pharmaceutical: Granule transfer between FBP discharge and tablet press hopper; API intermediate transfer between floors.
- Food & Beverage: Flour, sugar, starch, instant beverage powder, and food ingredient en-masse gentle horizontal transfer.
- Nutraceuticals: Protein powder, supplement granule, and vitamin premix inter-equipment transfer.
- Chemical: Catalyst granule, fertiliser, and specialty chemical bulk solid gentle enclosed transfer.
- Dairy: Milk powder, whey powder, and lactose enclosed transfer between spray dryer and silo.
Models & Capacities
| Model | Casing W x H (mm) | Length (m) | Capacity (t/h) | Chain Speed (m/s) | Motor (kW) | Bulk Density Max (kg/m3) | Particle Size Max (mm) | Containment | Overall H (mm) | Weight (kg/m) |
|---|---|---|---|---|---|---|---|---|---|---|
| EMC-100 | 100×100 | 1-10 | 0.5-2 | 0.05-0.15 | 0.18-0.37 | 800 | 10 | Dust-tight IP 54 | 350 | 12 |
| EMC-160 | 160×120 | 1-20 | 1-6 | 0.05-0.20 | 0.25-0.55 | 1,000 | 15 | Dust-tight IP 54 | 400 | 18 |
| EMC-250 | 250×180 | 2-30 | 3-15 | 0.05-0.25 | 0.37-1.1 | 1,200 | 20 | Dust-tight IP 54 | 480 | 28 |
| EMC-320 | 320×220 | 2-50 | 6-30 | 0.05-0.25 | 0.55-2.2 | 1,500 | 25 | Dust-tight IP 54 | 550 | 42 |
| EMC-400 | 400×300 | 3-80 | 12-60 | 0.05-0.30 | 1.1-4.0 | 1,800 | 30 | Dust-tight IP 54 | 650 | 65 |
| EMC-500 | 500×380 | 3-80 | 20-100 | 0.05-0.30 | 2.2-7.5 | 1,800 | 40 | Pressure-tight opt. | 780 | 95 |
| EMC-630 | 630×480 | 5-100 | 40-150 | 0.05-0.30 | 4.0-11 | 2,000 | 50 | Pressure-tight opt. | 950 | 140 |
| EMC-800 | 800×600 | 5-100 | 80-200 | 0.05-0.25 | 7.5-18.5 | 2,000 | 60 | Pressure-tight opt. | 1,150 | 200 |