Grate area
The main differences between boilers with a grate surface with cast iron grates and with a grate surface made of steel tubes.
Unlike some competing boilers on the market, which have a grate surface made of steel tubes filled with water, and this design solution is unsuitable, our boilers have a grate surface made of solid cast iron grates with a long service life in the lower part of the flue gas space, together with a fitting made of fireclay or refractory concrete.
The main, functionally significant difference is in the grate surface. ZEUS VU has a grate surface made of segmented robust cast iron grates and from 30 KW output, ZEUS VU boilers also have a fireclay bed in the rear part of the grate surface.
Some boilers on the market have a grate surface made of steel tubes, which are part of the water jacket, /water-cooled/, sometimes also called a flooded tube grate. This solution is cheaper, but it is completely unsuitable for any type of wood combustion.
On the grate surface at the place of combustion - burning wood, it is desirable and necessary for high-quality and efficient combustion that the wood is not in direct contact with the water environment, since water is an undesirable coolant. Wood, due to its chemical composition, consists of 80% of flammable, volatile substances, especially gases, which require a temperature of at least 300°C for combustion and for perfect combustion and burnout, these gases need a temperature of 700-1200°C. Boiler water may have a standard maximum operating temperature of up to 90°C. Since water-cooled tube grates are always part of the boiler water, there is undesirable cooling of the combustion process. In practice, this means that during combustion, the use of the energy value of wood decreases, i.e., heating costs increase, not to mention the deterioration of emissions coming from the chimney.
In addition, there may be a risk of condensation on such a water grate surface, which may lead to a reduction in the service life of the boiler.
A suitable grate surface is made of a material capable of accumulating heat. This material is refractory concrete, fireclay, cast iron, as is the case in our ZEUS VU boilers.
In addition, ZEUS VU boilers can be equipped with a LacFire 1550/30 refractory concrete bed with a monolithic grate and protection of all water walls of the boiler in the combustion zone with refractory concrete blocks.
High-quality gasification boilers, in order to achieve the lowest possible emissions and the highest possible efficiency in accordance with EN 303.5, usually have 50-80 kg of refractory concrete in the combustion chamber. This is also the case with our current gasification boilers PYROGAS and PYROSTAR Duo, which can also be equipped with a lambda probe and automatic air supply control using a servo drive with continuous fan speed control.
