This work presents a methodology to perform the scale-up of a solid fuel furnace to a higher heat output with maintaining or improving the burn-out quality. As basis to derive the scale-up concept, an example of a 35 kW screw burner for biomass fuels is investigated. Based on the Pi-theorem, the relevant dimensionless parameters are derived and similarity rules for the scale-up are proposed as follows: As initial conditions, the height to diameter ratio of the combustion chamber, the mean Reynolds number in the combustion chamber and the mean square velocity through the combustion chamber shall be kept constant or in the case of the Reynolds number may also increase. Additionally the effective momentum flux ratio between the secondary air injected in the combustion chamber and the gases from the pyrolysis and gasification section also shall be kept constant to maintain the mixing conditions between combustible gases and secondary air. Finally the thermal surface load on the screw also shall be kept constant. The influence of different scale-up approaches on thermal surface load, gas velocity, pressure losses, Reynolds number and height-to-diameter ratio are compared and discussed and a scaling approach to increase the heat output from 35 kW to 150 kW is described. For a theoretical validation of the scale-up, CFD simulations are performed to investigate the predicted pollutant emissions and the pressure loss for the scaled 150 kW furnace.

这项工作提出了一种方法，可以在保持或改善燃尽质量的同时，将固体燃料炉按比例放大至更高的热量输出。作为推导放大概念的基础，研究了用于生物质燃料的35 kW螺旋燃烧器的示例。基于Pi定理，推导了相关的无量纲参数，并提出了按比例放大的相似性规则，如下所示：作为初始条件，燃烧室的高度与直径之比，燃烧室中的平均雷诺数和通过燃烧室的平均速度应保持恒定，否则雷诺数也可能增加。另外，燃烧室中注入的二次空气与热解气化段的气体之间的有效动量通量比也应保持恒定，以保持可燃气体和二次空气之间的混合条件。最后，螺钉上的热表面载荷也应保持恒定。比较并讨论了不同放大方法对表面热负荷，气体速度，压力损失，雷诺数和高径比的影响，并描述了将热量输出从35 kW增加到150 kW的缩放方法。为了对规模放大进行理论验证，执行了CFD模拟以研究规模化150 kW炉子的预测污染物排放和压力损失。