Modeling and Experiments of Biomass Combustion in a Large-scale Grate Boiler
Grate furnaces are currently a main workhorse in large-scale firing of biomass for heat and power production. A biomass grate fired furnace can be interpreted as a cross-flow reactor, where biomass is fed in a thick layer perpendicular to the primary air flow. The bottom of the biomass bed is exposed to preheated inlet air while the top of the bed resides within the furnace. Mathematical modeling is an efficient way to understand and improve the operation and design of combustion systems. Compared to modeling of pulverized fuel furnaces, CFD modeling of biomass-fired grate furnaces is inherently more difficult due to the complexity of the solid biomass fuel bed on the grate, the turbulent reacting flow in the combustion chamber and the intensive interaction between them. This paper presents the CFD validation efforts for a modern large-scale biomass-fired grate boiler. Modeling and experiments are both done for the grate boiler. The comparison between them shows an overall acceptable agreement in tendency. However at some measuring ports, big discrepancies between the modeling and the experiments are observed, mainly because the modeling-based boundary conditions (BCs) could differ quite much with the conditions in the real furnace. Combustion instabilities in the fuel bed impose big challenges to give reliable grate inlet BCs for the CFD modeling; the deposits formed on furnace walls and air nozzles make it difficult to define precisely the wall BCs and air jet BCs that a reliable CFD needs. The CFD results show reasonably the mixing and combustion performance in the furnace based on the design drawings; while the measurement results reflect reliably the combustion performance in the real furnace in operation.
Biomass combustion Grate boiler Combustion instabilities CFD Water-cooled vibrating grate CO2 emission
Chungen Yin Lasse Rosendahl Soren K. Kser Henrik Sorensen Sonnik Clausen Torben Hille Soren L. Hvid
Institute of Energy Technology, Aalborg University, DK-9220 Aalborg East, Denmark Riso Research Center, Roskilde, Denmark DONG Energy, Kraftvaeksvej 53, DK-7000 Fredericia, Denmark
国际会议
2007杭州国际动力工程会议(The International Conference on Power Engineering 2007)
杭州
英文
2007-10-23（万方平台首次上网日期，不代表论文的发表时间）