The Şahi pulverised coal firing system is a compact combustion package offered by NEO MAKİNA ve MÜHENDİSLİK A.Ş. for firing medium-capacity steam and thermal oil boilers, dryers and kilns with pulverised coal. Consisting of mill, powder bunker, pneumatic feed and pulverised-coal burner, it is used to convert existing gas or fuel-oil boilers to economical solid fuel.
Operating Principle
1. Coal Preparation
- Crushing and milling: Coal is first reduced in a crusher, then milled to 75–100 microns.
- Drying: Moisture is removed with hot air during milling; low moisture raises flame temperature and efficiency.
- Storage: Pulverised coal is stored in an explosion-protected bunker and fed to the dosing screw.
2. Feeding and Combustion
- Pneumatic conveying: Coal powder mixed with primary air is carried to the burner.
- Pulverised-coal burner: Powder injected through purpose-designed nozzles burns in turbulent secondary air at a rate close to gaseous fuel.
- Flame supervision: Automatic ignition (gas or diesel pilot), UV flame detector and safety interlocks.
3. Heat Recovery
Combustion gases pass through the boiler tube bundle to produce steam, thermal oil or hot air; with economiser, overall efficiency exceeds 90%.
4. Flue-Gas Treatment
Particulates are captured by bag filter or electrostatic precipitator; lime dosing or SNCR is added where SO₂ and NOx limits require.
Technical Advantages
- High combustion efficiency: Fine milling gives complete combustion with minimal unburned carbon in ash.
- Fuel savings: Significantly lower fuel cost than natural gas and fuel oil; less excess air than grate systems.
- Fuel flexibility: Lignite, hard coal, anthracite; wood dust and pellet fines in blends.
- Fast load response: Low thermal inertia for quick reaction to load changes; short start-up.
- Automatic control: PLC control of feeding, air-fuel ratio and flame; remote monitoring.
Typical Application Range
- Thermal capacity: 1 – 15 MW per burner
- Coal fineness: 75 – 100 microns; dried below 10% moisture
- Applications: steam boilers, thermal oil heaters, rotary dryers, asphalt plants, lime and ceramic kilns, district heating
- Conversion: existing gas/fuel-oil boilers to pulverised coal
- Design codes: EN 12952/12953, CE, ATEX
Difference from ML34 MULTIBURN™
The Şahi system is a compact package for medium-capacity, mainly coal-fired plants. For high capacity, multi-fuel (biomass-heavy) and co-firing applications the ML34 MULTIBURN™ system is recommended.
Frequently Asked Questions
Which coals can be used?
Grades from domestic lignite to imported hard coal; mill and burner capacity are selected according to calorific value and ash content.
How long does converting a gas boiler to pulverised coal take?
After feasibility and engineering, manufacturing and installation usually take 3 – 5 months; boiler downtime is limited to a few weeks during installation.
Is there a dust-explosion risk?
The bunker and mill line are designed to ATEX principles: explosion vents, CO/temperature monitoring and inert suppression are standard.
To size a pulverised coal system for your plant and request a quotation, contact us.