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Numerical investigation of biomass fast pyrolysis in a free fall reactor

Bieniek Artur, Jerzak Wojciech, Magdziarz Aneta

Archives of Thermodynamics

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2021

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Vol. 42, no 3

173--196

EN

This work presents two-dimensional numerical investigations of fast pyrolysis of red oak in a free fall reactor. The Euler–Lagrange approach of multiphase flow theory was proposed in order to describe the behaviour of solid particles in the gaseous domain. The main goal of this study was to examine the impact of the flow rate of inert gas on the pyrolysis process. Calculation domain of the reactor was made according to data found in the literature review. Volume flow rates were 3, 9, 18, and 25 l/min, respectively. Nitrogen was selected as an inert gas. Biomass pyrolysis was conducted at 550◦C with a constant mass flow rate of biomass particles equal to 1 kg/h. A parallel multistage reaction mechanism was applied for the thermal conversion of red oak particles. The composition of biomass was represented by three main pseudo-components: cellulose, hemicellulose and lignin. The received products of pyrolysis were designated into three groups: solid residue (char and unreacted particles), primary tars and noncondensable gases. In this work the impact of the volume flow rate on the heating time of solid particle, temperature distribution, yields and char mass fraction has been analysed. The numerical solutions were verified according to the literature results when the flow of nitrogen was set at 18 l/min. The calculated results showed that biomass particles could be heated for longer when the flow rate of nitrogen was reduced, allowing for a greater concentration of volatile matter.

2

Combusting fuel formed from waste. Reduction in emission of chromium, nickel and lead

Król D., Poskrobko S.

Environment Protection Engineering

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2017

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Vol. 43, nr 1

101--112

EN

Thermal waste treatment processes dramatically reduce their volume and mass. Unfortunately, they also cause environmental nuisance associated with emissions of harmful substances. The emissions of toxic heavy metals into the air are of particular interest. Low effectiveness of dust extraction equipment for submicron size particles does not provide ecological safety. The paper presents the results of heavy metal (chromium, nickel and lead) emissions from fuel formed from waste combustion. It presents the possibility of reducing that emission by binding heavy metals in the residue scraper. As immobilising metal additives, substances such as: V2O5 and Na2B4O7 were used. Obtained reduction of heavy metal emission was of up to tens percent. In a series of studies, where in addition to Na2B4O7 and V2O5, CaCO3 was added, an additional effect of metal retention in the residue scraper was obtained. Chalk binds chlorine released from the fuel combustible material, which in turn prevents the transformation of heavy metals to form chlorides. Binding of hydrogen chloride from the gas atmosphere of the boiler to calcium chloride, eliminates the ability to create heavy metal chlorides. Addition of chalk reduces also its HCl emission and thus minimizes corrosion of the boiler components.

3

Effect of operating parameters on production of bio-oil from fast pyrolysis of maize stalk in bubbling fluidized bed reactor

Ali N., Saleem M., Shahzad K., Hussain S., Chughtai A.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 3

88--96

EN

The yield and composition of pyrolysis products depend on the characteristics of feed stock and process operating parameters. Effect of particle size, reaction temperature and carrier gas flow rate on the yield of bio-oil from fast pyrolysis of Pakistani maize stalk was investigated. Pyrolysis experiments were performed at temperature range of 360-540°C, feed particle size of 1-2 mm and carrier gas flow rate of 7.0-13.0 m3/h (0.61.1 m/s superficial velocity). Bio-oil yield increased with the increase of temperature followed by a decreasing trend. The maximum yield of bio-oil obtained was 42 wt% at a temperature of 490°C with the particle size of around 1.0 mm and carrier gas flow rate of 11.0 m3/h (0.9 m/s superficial velocity). High temperatures resulted in the higher ratios of char and non-condensable gas.

4

Pyrolysis of biomass and refuse-derived fuel performance in laboratory scale batch reactor

Kluska J., Klein M., Kazimierski P., Kardaś D.

Archives of Thermodynamics

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2014

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Vol. 35, no. 1

141--152

EN

The results of pyrolysis of pine chips and refuse derived fuel fractions are presented. The experiments were carried out in a pilot pyrolysis reactor. The feedstock was analyzed by an elemental analyzer and the X-ray fluorescence spectrometer to determine the elemental composition. To find out optimum conditions for pyrolysis and mass loss as a function of temperature the thermogravimetric analysis was applied. Gases from the thermogravimetric analysis were directed to the infrared spectrometer using gas-flow cuvette to online analysis of gas composition. Chemical composition of the produced gas was measured using gas chromatography with a thermal conductivity detector and a flame ionization detector. The product analysis also took into account the mass balance of individual products.

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Przewidywanie formowania płomienia pyłowego w warunkach szybkiej pirolizy na przykładzie palnika strumieniowego stabilizowanego plazmą

Świątkowski B.

Systems : journal of transdisciplinary systems science

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2004

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Vol. 9, Sp. 2/2

954-963

PL

W referacie przedstawiono wyniki obliczeń procesu formowania płomienia pyłowego dla modeli odgazowania: jedno-reakcyjnego, oraz, liniowego opracowanego w IFRF W pracy wykorzystano wyniki prac laboratoryjnych na stanowisku do badań zapłonu i stabilizacji płomieni pyłowych za pomocą plazmy. Z uwagi na gwałtowny przebieg spalania pyłu stanowisko to posłużyło do weryfikacji obliczeń procesu spalania w warunkach szybkiej pirolizy. Wyniki pracy potwierdziły tezę, że brakuje uniwersalnego modelu odgazowania słusznego dla szerokich zastosowań.

EN

Modelling of coal combustion process is a very difficult phenomenon because coal has very compound structure, which, during the combustion process, passes through complicated physical and chemical transformations. Moreover that these processes are going with different intensity practically at the same time (fast heating, thermal decomposition, mixing with oxidizer, heat transfer, ignition etc.) 'The real simulation of these Iran s formations are not possible, therefore the models arc simplified significantly. Prediction of combustion process strongly depends on application of exact dcvolatelization model. This paper presents numerical simulation of pulverized coal flame formation under condition of fast pyrolysis. In the calculations two devolatelizarion models were examined - Single Kinetic Rate Model and linear one step IFRF Model. In order to verify calculation a results from laboratory stand for pulverized coal flame ignition and stabilization by plasma were used. Outcomes of the investigation confirmed there is not universal devolatelixntion model proper for different flame conditions.