The combustion of residual waste is a complex process since the composition, heating value and ash content of the fuel varies. As a result, operators of waste-to-energy plants face an enormous challenge: Given a service life of over 30 years, the technology must also be able to function efficiently with the changing waste composition in the future.
A flexible grate-based combustion system which can be adjusted to the varying requirements of the fuels has proven to be an ideal solution to this problem. Martin Biopower's latest development, the reverse-acting grate Vario, is one of the most innovative products available globally on the market for this purpose.
It is based on the proven reverse-acting principle currently being used successfully to combust waste in more than 550 lines. The three drive zones now available with the Vario system can be controlled individually. The speed at which the fuel is fed and the combustion conditions can be optimally adjusted to the fluctuating waste quality. This makes it possible to agitate the fuel/the combustion residues in several zones without adversely affecting the residence time.
The Martin Biopower reverse-acting grate Vario is inclined in the direction of transport and comprises several stair-like grate steps. The up-and-down motion against the grate inclination of every second step constantly mixes the red hot mass with the newly fed waste and facilitates uniform and stable operation of the combustion process at temperatures sometimes exceeding 1,000 degrees Celsius.
The underfire air is supplied over five individually controlled air zones ensuring optimal reaction conditions for the fuel. The overfire air, which is injected above the fuel bed via several nozzles, efficiently mixes the flue gases and burns out completely at temperatures of up to 1,200 degrees Celsius.
It is not necessary to cool the Martin Biopower reverse-acting grate Vario even when heating values are very high. Its unique drive concept constantly maintains a stable covering on the grate and consequently the grate elements are protected from excessive thermal loads.
This new grate system is equipped for all eventualities: thanks to its consistent modular construction, it is possible to install up to eight consecutive grate runs achieving a maximum grate width of up to 20 meters.