B&W - Combustion Grates
Our grates provide waste flow that ensures drying, ignition, combustion, energy release and complete burn-out before the bottom ash outlet.
In a waste-to-energy plant, the grate is where waste is converted into energy – the heart of the system. The combustion grate plays a vital role. As such, grates are a significant focus area for us. Over the past 80 years we have supplied more than 500 combustion grates worldwide. Many of our older grates are still in operation, running efficiently and living up to current environmental standards.
We offer two distinctly reliable choices
Today, we offer two combustion grates: the DynaGrate® and the Vølund grate. Each grate is available in both water-cooled and air-cooled designs. The DynaGrate® and the Vølund grate were developed to provide reliable transport of waste through the furnace. This ensures drying, ignition, combustion, energy release, and complete burn-out before the bottom ash outlet.
THE DYNAGRATE®: The most advanced combustion grate on the market
Our state-of-the-art combustion grate, the DynaGrate®, is one of the most advanced combustion grates on the waste-to-energy market. It is based on 40 years of research and development of the renowned Bruun & Sørensen technology, which we acquired in 2001. The DynaGrate® provides excellent performance with low maintenance costs due to a design technology that causes little wear and tear.
With the DynaGrate® technology we are able to meet tomorrow's demands for waste-fired CHPs, which require a high level of accessibility, fuel flexibility, and energy recovery, under environmentally sound conditions.
Our DynaGrate® is renowned for:
- Its unique movement: A strong agitation of the fuel bed results in an excellent burn out of the waste fuel
- Its unique design: There is no contact between the grate bars. This design ensures minimum impact of mechanical forces and minimizes the need for spare parts
- Its unique cooling system: A fully integrated water cooling system ensures a stable operation and high availability of the combustion system.
Capacity of up to 44 metric tons with our modular DynaGrate®
For our latest addition we have developed a six-meter-wide grate module, which allows us to supply grates with a capacity of up to 44 metric tons of waste per hour. It’s designed for a wide array of waste types, with extreme variations in calorific values.
Individual combustion sections means more control
The DynaGrate comes in either 1 or 2 combustion lanes, depending on the capacity of the plant. There are four separate combustion sections in each lane, making it possible to control the speed and the excess air in each of them individually. This means control of a total of four or eight individual grate sections.
DynaGrate provides optimal agitation of the fuel bed
The grate resembles a staircase. The individual steps -- the grate bars -- are alternately placed horizontally and vertically. These grate bars are mounted on shafts. As the grate bars of one shaft interfere with the bars of the adjoining shaft, a continuous grate carpet is formed. When the shaft turns 60º in opposite directions the steps change from vertical to horizontal and from horizontal to vertical. This produces a wave-like longitudinal movement, which in turn produces optimal turnover of the fuel bed.
Ideal for the combustion of all types of waste, even cans and metals
Our DynaGrate can handle all types of waste. A unique feature is that it can process waste containing large amounts of metals and still operate efficiently, a significant financial benefit. The DynaGrate® features a very high combustion efficiency obtained with greater energy recovery for the production of electricity and/or heat while limiting environmental pollution.
Features and benefits for DynaGrate®
- Combustion of all types of untreated waste which saves 15 Euros per ton.
- Possibility of biomass co-firing
- Uniform and efficient combustion, typical less than ¼ % of total organic carbon in ash content
- Unique combustion control and fast stoker response
- No contact between the grate bares and side liners:
- Limits the wear-and-tear
- Reduces the mechanical forces to which the grate is exposed during operation
- No problem with fusion of metals – as seen on classical forward/backward acting grates
- Capacity is 4 – 44 t/h
Water-cooled DynaGrate® for high calorific waste
Our patented, water-cooled DynaGrate® provides superior grate durability for combusting high calorific waste, which can cause high thermal stresses in the grate. The cooling for the combustion grate is independent of primary air.
Mechanically, the air-cooled and water-cooled versions are comparable. The movement pattern works similarly and they have the same process advantages. The grate bar is machined as a hollow section with channels designed to convey cooling water to the areas with the highest heat load.
Additional features and benefits of the water-cooled DynaGrate®
- Large variation in fuel compositions and heating values
- Suitable for high calorific waste up to 25 MJ/kg
- Operation at low excess air number mean that:
- Cooling for the combustion grate is independent of primary air
- High thermal efficiency
- Low NOx formation
- Minimal grate siftings and less metal in air hoppers
- Combination of water-cooled and air-cooled grates
- Long lifetime, less wear and tear on parts, and lower maintenance costs
THE VØLUND GRATE: Our classic grate – still going strong
The Vølund grate is still one of the industry’s most dependable grates. It has been keeping systems running smoothly for more than 80 years. And even though our Vølund grate has been well-proven and robust, we continue to conduct research and improve the technology.
This includes our knowledge on types of steel and alloys. Throughout the years we have developed our heat cast grates to withstand very high temperatures and to increase lifetime.
New Vølund grate plates mean lower maintenance cost
We developed a new type of grate plate that makes a tremendous difference for the plant operator as large amounts of grate siftings are avoided. Before, large chunks of fused, melted aluminium could get stuck in hoppers under the grates. If not cleaned regularly, melted aluminium would close them. Cleaning them is an unpleasant job which requires a great deal of manpower and also requires that the plant run at reduced load while the work is performed.
Minimum emission of harmful substances and maximum energy recovery
The traditional Vølund air-cooled combustion grate is a thoroughly proven design, highly suitable for continuous high-efficiency combustion of mixed household and bulk industrial waste with minimal emission of harmful substances and maximum energy recovery.
High availability and operational reliability
The Vølund grate is manufactured from a rigid design. The design was specially developed for heavy-duty and high-temperature operation with a high availability and operational reliability. This ensures minimal shutdown for routine maintenance and cleaning.
A good air distribution and minimal power consumption
The grate movement is like a 'walking floor' and is unique in its simplicity. The combustion air is blown in and up through many small gaps, ensuring perfect air distribution. This results in combustion of the waste with minimal power consumption for air injection and grate movement. Inspection and maintenance during the planned yearly stoppages are also simple because all servicing of grate bars, grate blocks, grate girders, and rollers takes place in the furnace above the grate with hand tools only. There is therefore no need to work below the grate.
A solid, reliable design
The grate is divided into feeding section with pusher, combustion grate, and burn-out grate. Our grate has four sections, two of which form the combustion grate at an angle of 15º while two sections form the burn-out grate at an angle of 7.5º. A one-metre-high vertical grate transition between the combustion grate and the burn-out grate ensures that waste lumps are broken up and burned.
The grate sections are integrated into a unit, and all sections are operated and controlled individually. This means that each section has its own grate drive and control system for combustion air.
High reliability with minimal downtime
The individual components used in the grate design are specially developed for highly variable loads and high temperatures. The result is high reliability with minimal downtime.
Simplicity and robust grate design suitable for waste with low calorific value
The Vølund grate’s simplicity and robustness makes it a very popular choice for waste of low calorific value as in some Asian countries. Indeed, it is very suitable for heavy duty plants.