How poultry waste incinerators work
Poultry waste incinerators handle farm mortalities, hatchery waste such as unhatched eggs, shells and dead chicks, and processing plant offal and feathers. Small farm units are batch-loaded two-chamber incinerators. Larger units at hatcheries and processing plants are often continuously fed by ram or screw into a primary chamber at about 800°C, with a secondary chamber at about 1,000°C. The waste is wet and fatty, and eggshell adds calcium carbonate, so the ash is lime-rich. Feathers and down are light and entrained easily. Gas leaves the secondary chamber, is cooled in a heat exchanger or by tempering air, passes a cyclone and sometimes a bag filter, and the ID fan delivers it to the stack. A combustion air blower supplies both chambers.
Where the ID fan sits
- Feed ram
- Primary chamber
- Secondary chamber
- Heat exchanger
- Cyclone
- ID fan
- Stack
The fan sits after the heat exchanger and cyclone, near the stack. It works against both chambers, the exchanger and the cyclone, typically 120 to 250 mmWC, more where a bag filter is added. On continuously fed units it must hold the primary chamber negative as each ram stroke pushes in wet waste, which releases steam and gas in pulses.
Gas at the ID fan
| Gas temperature, normal | 200 to 260°C after the heat exchanger |
| Maximum or upset | Up to 350°C with a fouled exchanger |
| Dust at the fan | Fine lime and phosphate ash and charred feather fragments; a few hundred mg/Nm³ after a cyclone |
| Moisture and dew point | High water vapour from wet waste; dew point well below the gas temperature |
| Deposits | Potassium and sodium salts with ash can become sticky on cooler surfaces |
| Density at the design temperature | About 0.71 kg/m³ at 230°C, 59% of standard air. Pressure developed and power drawn scale with density, so the fan is selected at this condition and the motor is checked at the coldest operating or start-up condition. |
ID Fan selection for poultry waste incinerators
| Blade form | Radial tipped or open radial for dust and deposit tolerance |
| Material of construction | Mild steel casing; impeller in heat-resisting or wear-resistant steel |
| Drive and arrangement | Belt drive or direct coupled |
| Bearings and cooling | Pedestal bearings with cooling disc |
| Flow control | Variable speed drive on primary chamber pressure |
| Also specified | Cleaning doors, casing drain, and vibration monitoring |
What this ID fan has to cope with
Feather and fluff carry-over
Feathers and down lift easily from the feed and can pass the secondary chamber before burning out. Partly burnt fragments reach the cyclone and fan and build up. Feeding feathers wetted or compacted, and keeping secondary air high, reduce this.
Sticky salt and ash deposits
Poultry waste is rich in potassium and phosphorus. Salts condense on cooler surfaces of the exchanger and fan, collect ash and harden. Keeping gas temperature above the condensation range and regular cleaning keep the fan balanced.
Pulsed load from ram feeding
Each ram stroke pushes wet waste into a hot chamber and causes a pressure pulse. A fan with pressure margin and a drive on chamber pressure keep the chamber negative, avoiding smoke at the feed hopper.
Energy and control
Continuously fed poultry incinerators run through the day with feed rate following the farm or plant waste. A variable speed ID fan on chamber pressure follows the feed. Heat recovery from the exchanger, for example to heat water or brooder houses, lowers gas temperature at the fan and reduces its volume.
ID fan and FD fan in poultry waste incinerators
| ID fan | FD fan | |
|---|---|---|
| Position | After heat exchanger and cyclone | Beside the incinerator, feeding both chambers |
| What it handles | Hot gas with feather char and lime-rich ash | Ambient combustion air |
| Temperature at the fan | 200 to 260°C, up to 350°C upset | Ambient, 25 to 45°C |
| Main design concern | Dust and sticky deposits | Low primary velocity to limit carry-over |
| Control | Primary chamber pressure | Chamber temperatures and oxygen |
See also the Forced Draft (FD) Fan for poultry waste incinerators.
Questions buyers ask
Why do feathers cause problems in a poultry incinerator?
Feathers are light and are carried by the gas before they burn completely. Charred fragments reach the cyclone and ID fan and build up. Compacting or wetting feathers before feeding and good secondary air distribution help.
What blade type suits an ID fan on a poultry waste incinerator?
A radial tipped or open radial impeller tolerates dust and deposits better than a backward curved one. Where the gas is well cleaned by a bag filter, a backward curved wheel can be used for better efficiency.
How hot is the gas at the ID fan on a poultry incinerator?
After a heat exchanger it is typically 200 to 260°C, rising to around 350°C if the exchanger fouls. Without heat recovery, tempering air is used to bring it below the fan's design limit.
Information needed to quote an ID fan for poultry waste incinerators
- Duty point. Gas volume in m³/h or Am³/h at the fan inlet and the static pressure the fan must develop, with the margin you want on each.
- Gas condition. Normal and maximum gas temperature at the fan, dust loading after the collector, moisture and any acid gases such as SO₂ or HCl.
- System. Boiler or furnace capacity and fuel, collector type and its pressure drop, and the existing fan curve or nameplate if this is a replacement.
- Mechanical. Drive arrangement, flow control (damper, inlet vanes or variable speed drive), rotation and discharge orientation, and a layout drawing or site photograph.
- Waste mix. Share of mortalities, hatchery waste, feathers and offal, and feed method.
- Heat recovery. Whether a heat exchanger is fitted and its gas outlet temperature.
Built and tested in Chennai
Adroit Fantech Engineers has designed and manufactured industrial fans at Ayanambakkam, Chennai since 2004. Each impeller, casing and shaft is built for the gas and temperature it will see, performance tested as per IS 4894 or BS 848 Part I, and balanced to grade G 6.3 or G 2.5 as per ISO 21940-11, with the records supplied with the fan. We also replace rotors and retrofit existing fans of any make.