Dynamics of movement and heat transfer for biomass particles in downdraft gasifier - Experimental measurements with the use of radiographic methods

• Published in: Fuel processing technology 2020-12, Vol.210, p.106555, Article 106555
• Main Authors: Kazimierski, Paweł, Hercel, Paulina, Kardaś, Dariusz
• Format: Article
• Language: English
• Subjects: Bed movements; Bed settling; Biomass; Downdraft; Gasification; Heat transfer; Heating rate; Nozzles; Nuclear fuels; Oxidation; Pyrolysis; Radiography
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2020.106555

This paper investigates the time and space dependent dynamics of the movement and heat transfer of the bed inside the reactor during the biomass gasification process in a downdraft system. Measurement technology that uses radiographic methods is proposed and described. In general, the rate of bed subsidence decreases with time. However, the bed movement is highly diversified in the air nozzle area. In this region, the mean velocity of the bed is slightly faster than at the beginning of the process due to high temperatures and intensive oxidation in the burning zone. Unexpectedly, the radiographic markers (representing the motion of fuel particles) can be visibly separated into two groups: the center region group and the wall region group. This is likely to be the effect of limited air coverage in the center region of the gasifier. The velocity difference of the two groups amounted to 10:1 at the air nozzle level, with the wall region group being faster. Determination of particle velocity combined with temperature measurements allows us to estimate the heating rate in the gasifying system work conditions. The actual heating rate for the investigated installation was roughly estimated to be 130 °C/min in the wall region of the gasifier. [Display omitted] •Experimental method for bed motion during gasification is presented.•Presented method is non-invasive for the fuel movement inside the gasifier.•Three dimensional experimental analysis on the bed motion is presented.•The fuel motion is characterized by unexpectedly fast changing dynamics.