Rotary-Grate Solid Fuel Combustion System
The rotary grate solid fuel combustion system is an automatic combustion unit mounted beneath the pre-furnace of a water-tube steam boiler that burns coal and biomass with high efficiency. Thanks to the heat-resistant, special-alloy chain grate, helical feeder, and guillotine rake, the fuel is distributed evenly, ensuring clean combustion with controlled airflow. The ash produced at the end of combustion is automatically discharged via the ash hopper and screw conveyor. Sized according to fuel characteristics, the system offers an economical solution with high combustion efficiency and low emission levels.
Rotary-Grate Solid Fuel Combustion System
The rotary-grate solid fuel combustion system is an automatic firing unit mounted beneath the pre-furnace system at the front of a water-tube steam boiler, enabling solid fuels such as coal and biomass to be burned with high efficiency and low emissions. The rotary grate, the heart of the system, is manufactured from a special heat-resistant alloy and designed with a chain system. Thanks to the air passage provided between the cast plates, the air required for efficient combustion of the fuel is adjusted to the desired level, keeping combustion under control.
The operating principle is fully automatic: the distribution screw conveyor inside the coal hopper spreads the incoming fuel evenly over the grate bed. The thickness of the spread fuel layer is set by an automatic level detection system; the guillotine rake opens gaps in the fuel so that more air can penetrate, and initial combustion takes place with the minimum air supplied from beneath the grate. As the fuel enters the pre-furnace, it first gives off its moisture under the effect of radiant heat; as the temperature rises, gasification and the release of volatile combustible hydrocarbons begin, and fixed carbon combustion is completed in the later section of the grate. Having released all of its energy to the boiler, the fuel reaches the end of the grate as fully burned ash and is automatically discharged into the slag hopper and from there out of the boiler by a screw conveyor.
Efficient and clean operation of the system depends on its being designed for the properties of the fuel to be burned. The width and length of the grate system, the fuel bed thickness and the amount of air to be supplied are calculated by taking into account the fuel’s calorific value, ash content, moisture content, volatility and melting point. This achieves high combustion efficiency, saves fuel and minimizes flue gas emissions.
Technical Specifications
- Combustion unit mounted beneath the pre-furnace system of a water-tube steam boiler
- A chain-driven rotary grate made of heat-resistant special alloy cast plates
- Adjustable combustion via controlled airflow through the cast plates
- Homogeneous, automatic fuel feeding via a coal bunker and distribution screw
- Adjustable fuel bed thickness via an automatic level detection system
- Fuel loosening and increased air penetration via a guillotine rake
- Automatic ash discharge via a slag hopper and screw conveyor
- Custom sizing based on fuel properties (calorific value, ash content, moisture, volatility, melting point)
- High combustion efficiency and low emission levels
- Fully automatic, continuous, and balanced combustion control
Fuel Properties:
- In the standard system, the desired emission levels are achieved using washed pulverized coal with a particle size of 0.5–10 mm and a calorific value of 3,500 kcal
- Capability to operate with biomass fuels (rice husks, wood shavings, wood chips, various agricultural waste)
Optional Equipment:
- Economizer or recuperator (flue gas heat recovery system)
- Coal level and moisture sensors
- Thermocouple / PT100 temperature measurement equipment
- Automatic ash and slag discharge screw
- Fuel storage bunker and feed screw
- Automatic combustion system mounted beneath the pre-furnace and integrated into the boiler
- Heat-resistant, special-alloy chain-driven rotary grate
- Homogeneous combustion with automatic screw feeder + guillotine rake
- Automatic ash and slag discharge
- Multi-fuel flexibility with coal and biomass
- High efficiency and low emissions thanks to fuel-specific design
The solid-fuel combustion system with a rotary grate operates in conjunction with water-tube steam boilers and is used in all industrial facilities with continuous steam consumption where solid fuel is cost-effective:
Food and Beverage: Dairy products, canned goods, tomato paste, and oil production—pasteurization, sterilization, and cooking processes
Textiles and Dyeing: Dyeing, finishing, drying, and printing processes
Energy and Process Plants: Continuous, high-capacity steam/heat production
Chemical and Pharmaceutical: Reaction heating, distillation, and sterilization processes
Lumber, Wood, and Particleboard: Drying kilns and steam generation — utilizing their own biomass waste as fuel
Agricultural Processing and Feed: Pelletizing, drying, and processing facilities
It offers a significant fuel cost advantage over natural gas, particularly in regions where coal and biomass are inexpensive and readily available.
Companies we have delivered this boiler to
- Queen Tarımİzmir · 3 × 5,000,000 kcal/h
- Uysal MadencilikTekirdağ · 3,500,000 kcal/h
Frequently Asked Questions
A rotary grate is a combustion surface made of cast plates in a special heat-resistant alloy that advances slowly by means of a chain system. By carrying the fuel along the grate, it ensures automatic and complete combustion of coal and biomass.
In addition to suitably sized coal, biomass fuels such as sawdust, olive pomace, hazelnut shells and sunflower husks can be burned.
Yes. Mounted in front of an existing natural gas- or liquid fuel-fired boiler together with a burner-type pre-furnace, it converts the boiler to solid fuel.
A rotary grate is preferred for medium- and high-capacity boilers in continuous operation, while a stoker, which is more economical, is preferred for small and medium capacities. You can find the details in our rotary-grate steam boiler guide.
Rotary-Grate Solid Fuel Combustion System — let’s size it together
Our engineers plan capacity, pressure and fuel choice for your needs.