Measurement of bed-to-tube surface heat transfer coefficient to a vertically immersed u-tube in bubbling loop seal of a CFB boiler
Journal article, 2021

Experimental measurements of bed-to-tube surface heat transfer coefficient were conducted in a 12 MWth circulating fluidized bed boiler/gasifier where a vertical U-tube was immersed into the bed. The aim was to study the influence of superficial gas velocity, solid flux of bed material, direction of the tube relative to the circulating particle flow, choice of fluidization gas, bed temperature and to compare the results with predicted values based on heat transfer correlations. The experiments displayed high heat transfer coefficients of around 550 W/(m2K) with sand and with ilmenite approximately 850 W/(m2K) when operating with air at a superficial gas velocity of 0.25 m/s. Replacing air with steam and recirculated flue gas as fluidization gas increased the heat transfer by more than 40% with both steam and flue gas. Having the U-tube oriented parallel to the circulating particle flow reduced the heat transfer by around 8% compared to a perpendicular orientation.

Fluidized bed heat exchanger

Fluidized bed

Heat transfer coefficient

Vertical U-tube

Circulating fluidized bed

Heat transfer

Author

Viktor Stenberg

Chalmers, Space, Earth and Environment, Energy Technology, Energy Technology 3

Fredrik Lind

Chalmers, Space, Earth and Environment, Energy Technology

Magnus Rydén

Chalmers, Space, Earth and Environment, Energy Technology

Powder Technology

0032-5910 (ISSN)

Vol. 381 652-664

Förbränning av biomassa med Oxygen Carrier Aided Combustion (OCAC)

Swedish Research Council (VR), 2018-01-01 -- 2021-12-31.

Subject Categories

Energy Engineering

Chemical Process Engineering

Bioenergy

DOI

10.1016/j.powtec.2020.11.046

More information

Latest update

1/20/2021