Improving the efficiency of lime firing in a rotary kiln using wood powder as fuel

Шрифт:
156

https://doi.org/10.15407/steelcast2021.01.008

Met. litʹe Ukr., 2021, Tom 29, №1, P. 8-13

S.G. Polozhaj1, PhD (Engin.), Senior Research Scientist, e-mail: s.polozhaj@mail.ru
S.V. Mazur2, PhD (Engin.), Director, e-mail: mazur@optima.com.ua
S.V. Muzychuk3, Technical Director, e-mail: tov-lvsp@ukr.net
I.M. Raykovsky3, Chief Engineer, e-mail: tov-lvsp@ukr.net

1Ukrainian State University of Chemical Technology (Dnipro, Ukraine)
2LLC “Sigma-invest” (Dnipro, Ukraine)
3LLC "Lubomyr lime-silicate enterprise" (village Nova Lubomyrka, Ukraine)

Received 19.01.2021

UDK 620.93:[666.92.041.49:662.638]](045)

The materials of publications devoted to the topic of replacing natural gas with biofuel during firing in lime kilns for metallurgical, construction and other industries are generalized. Scientific and technical solutions for the use in rotary kilns crushed wood pellets when burning lime as a fuel instead of natural gas are the most wellknown and wide-spread in industrial practice. 
This technology is used to the greatest extent at the enterprises of Sweden, Finland. Based on the analysis of the results of published studies, it is shown that a prerequisite for flare burning pellets in rotary kilns is their grinding to a fraction of less than 1 mm. Technical solutions are analyzed, which allow to replace 50–70 % of natural gas with agricultural production wastes, in particular sunflower husks, during lime firing in rotary kilns. The possibility and efficiency of substitution of natural gas in rotary kilns for burning lime with wood powder as fuel, which is obtained from the waste of the woodworking industry of the north-western region of Ukraine, is theoretically and experimentally substantiated. Data on the composition of equipment and technology of lime firing in a rotary kiln for metallurgical, construction and other industries at the Lubomyr lime-silicate enterprise located in the Rivne region are shown. The results of research performed on the industrial equipment of Lubomyr lime-silicate enterprise are presented. The basics of lime production technology when used in rotary kilns of wood powder as fuel are considered.
It is shown that wood fuel chip requires preliminary preparation before burning. The parameters of wood powder fuel required for its use in rotary kilns for burning lime are determined. The suitability of this fuel was evaluated by the completeness of its combustion, which was determined by the amount of residual carbon in the lime. Fuel requirements for moisture and degree of grinding of wood waste have been established. The efficiency of dust wood powder fuel depending on its humidity is investigated. It is shown that drying wood to a humidity of not more than 10 % is sufficient to ensure a flare temperature of 1400 °C. 
According to the results of research, a technological scheme of preparation of such fuel for use as fuel in rotary kilns during lime firing has been developed and put into practice. The parameters of the technological line with the capacity of 2.4 t/h of wood powder fuel preparation for the rotary kiln built and put into operation in 2018 at the Lubomyr lime-silicate factory are given. The implemented solution allowed replacing 90–95 % of natural gas during the firing of lime in the rotary kiln of the Lubomyr lime-silicate factory with wood powder fuel. The experience of two years of operation of the rotary kiln on wood powder fuel has shown that the company stably produces lime of the 1st and 2nd grades. Industrial practice has confirmed the correctness of scientific and technical solutions developed during research. The prospects of additional research, aimed at the implementation of the obtained scientific solutions at other industrial facilities for the purpose, to increase the use of wood powder fuel to replace natural gas are shown.

Keywords: Lime, production, rotary kiln, biofuel, wood processing waste, natural gas.

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