Open Access Journal Journal of Power Technologies 92 (1) (2012) 27–33 journal homepage:papers.itc.pw.edu.pl Distribution of solids concentration and temperature in the combustion chamber of the SC-OTU CFB boiler ✩ Artur Blaszczuk ∗ , Maciej Komorowski, Wojciech Nowak Environmental Protection and Engineering, Czestochowa University of Technology 69 Dąbrowskiego Street, 42-201 Częstochowa, Poland Abstract One of the main parameters inﬂuencing heat transfer in a circulating ﬂuidized bed boiler is the dis- tribution of the bed’s solids concentration within the contour of the boiler’s combustion chamber. This paper contains an analysis of the impact of the solids concentration in a ﬂuidized bed on the vertical temperature proﬁle in the combustion chamber of a SC-OTU CFB boiler. Investigations were conducted at diﬀerent loads of nominal generator power: 100%, 80%, 60% and 40%. Solids concen- tration was determined through pressure sensor measurements. Pressure measurements were taken at 11 measuring ports situated on the front wall of the combustion chamber. The vertical temperature proﬁle was produced on the basis of temperature measurements from various furnace elevations. The combustion process was carried out at various primary to secondary air ratios with a constant excess air coeﬃcient. Keywords: temperature distribution, solids concentration, CFB boiler, bed pressure, unit loads 1. Introduction Solids concentration in the contour of the com- bustion chamber has a signiﬁcant impact on the work of the whole CFB unit. The solids concen- tration is aﬀected by the particle size diameter of materials fed to the boiler: limestone, bed ma- terial – make-up sand, fuel supply, re-circulated ﬂy ash/bottom ash and internal material recircu- lation depending on the eﬃciency of the separa- ✩ Paper presented at the 10 th International Conference on Research & Development in Power Engineering 2011, Warsaw, Poland ∗ Corresponding author Email addresses: ablaszczuk@is.pcz.czest.pl (Artur Błaszczuk ∗ ), mkomorowski@fluid.is.pcz.pl (Maciej Komorowski), wnowak@is.pcz.czest.pl (Wojciech Nowak) tor. The particle size distribution of the mate- rials supplied to the combustion chamber aﬀects the course of the combustion process, but is neg- ligible from both the hydrodynamic point of view and the economics side [1]. The wide range of particle size distribution af- fects the segregation of solids, which is seen in the situation when light particles, i.e. recirculated ﬂy ash, are elutriated by the ﬂuidization gas even in small ﬂuidization velocities and coarse parti- cles sink to form a dense phase in CFB boilers. Also the relative amount of very light materials supplied (having a very small d 50 ) can lead to a situation where even in mid-range ﬂuidization velocities, bigger particles are transported to the higher levels of the combustion chamber by clus- ters of ﬁne particles. Hence, the proportion of