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Research and coal combustion industry — the twain shall meet
Conference
Abstracts
devices of small dimensions and weight, that are the result of a 15 year fundamental scientific investigation. A few devices and equipment may now be produced, and may be applied in mines and in laboratories. This includes four portable pieces of equipment for sampling and investigating samples which allow their hermetization and maximum conservation of their characteristics to be assured, decreasing considerably labour consumption and the duration of various laboratory investigations. It will promote a wider application of modern methods including computer systems for coal utilization and control and optimization of the environment.
the Q values were similar for all the samples except for the semianthracite, which as in the previous case was the lowest. The reactivity of the carbonized swollen coals towards CO, was higher for those coals with the higher Q value. However, the calculated
activation energy remains constant for the chars of the same coal. These results indicate that the enhancement of reactivity is due to the higher porosity of the swollen char which allows a better contact reactive gas and the active sites in the chars.
between
the
The promoting effect in the flotation of low rank coal A. M. Saleh and J. Iskra*
A multistage three-phase mathematical coal combustors G. I/: Reddy and Sriram
model for fluidized bed Mining Department, Faculty of Engineering, Alazhar University, Cairo, Egypt * Mineral Processing Institute, Faculty of Mining and Geology, Silesian Technical University, Gliwice, Poland
Prasad
Indian School of Mines, Department Engineering, Dhanbad-826004, India
of Fuel
and
Mineral
The multistage three-phase mathematical model developed by ElAlwagi and El-Rifai’ for gas-solid fluidized bed catalytic reactors has been applied to fluidized bed coal combustors with some modifications. The reaction rate constant for combustion has been derived by taking into account the coal particle population balance, particle reduction rates and particle surface temperature. The combustion reaction has been assumed to follow first order kinetics. The mode1 considers the fluidized bed combustor to be composed of a number of equivalent stages in series. In each stage the oxygen is assumed to pass from bubble to cloud wake phase and then to emulsion phase. The product gas, i.e. CO,, will pass in the reverse direction. It is further assumed that the release of volatile matter from the coal is instantaneous and it burns at the same rate as the char which is left behind after devolatilization. A salient feature of the model is the incorporation of particle size distribution. The simulated results have been compared to the 10 MW fluidized bed combustor plant data of TISCO Jamadoba, India. The combustion efficiency, exit gas composition and carbon load in the bed have been predicted and compared to plant data. The agreement between simulated and plant data is good. Utilizing the model, a number of illustrative predictions have been made; in particular the mode1 has bee used to predict the influence of coal feed particle size distribution on various combustion parameters. Useful inferences have been drawn based on these predictions. REFERENCE 1
El-H&@,
M. M. and El-Refai, M. A. Chem. Eng.
Sci.
1988. 41 (9). 2477
Reactivity of some Colombian coals towards CO*. Influence of swelling J. M. Rincdn, National BogotB,
G. Moreno
University, Department Colombia SA
Fuel 1993
Evaluation of the Recreio Flowsheet C. H. Sampaio,
L. A. C. Klujszo
COPELMI
and G. F. Cavalcante
Post-Graduate Program on Metallurgical and Materials Engineering (PPGEMM), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil The Recreio Flowsheet, belonging to ‘Companhia de Pesquisas e Lavras Minerais’ (COPELMI), Porto Alegre, Brazil, cleans two different kinds of coal, one from Recreio Mine and the other from Butia-Leste Mine, both open-pit mines. This work evaluates the coal preparation plant, which consists of coarses and fines circuit (Baum jig and hydrocyclones). Densimetric and granulometric analyses were done to determine the densimetric and granulometric partition curves and the performance criteria deriving from them. Studies were also made of the possible points of waste, such as size fraction -1 mm of the jig’s middle and refuse, undersize of the dewatering screen of the final fine product and scope of the hydrocyclone’s feeding sump. Ash was analysed in all the densimetric and granulometric fractions obtained. Proposals to increase the recovery of the process through operational improvements are suggested, as well as changes in the Flowsheet.
and S. Cruz of Chemistry,
Santafi:
de
Colombian coals are believed to be of Gondwanaland origin, which are characterized by a high concentration of inert macerals; therefore their behaviour towards processes like combustion and gasification may be different from coals of Europe and North America. Samples of coal from low rank to semianthracite were solvent swollen with butylamine and THF. After extraction of the solvent, the samples of the parent coal and solvent-treated coal were carbonized at 773 K and crushed to pass 147pm. The reactivity towards CO, of the carbonized products was measured using 2-5mg of char in a TGA equipment at 973,1073,1123 and 1173 K. The flushing gas was allowed to flow while heating (20 K min- ‘) and the starting tine for the reactivity measurement was taken after the sample had reached the programmed temperature. The swelling ratio (Q) of the samples treated with butylamine was higher than for those treated with THF. The highest Q value for butylamine was for the low rank coals (7678% C) and the lowest value was for the semianthracite. When THF was used as swelling solvent,
722
In this study, the promoting effect of a natural oil-breaking by-product (PYROLIZAT) was tested. The feed material used in this investigation was low rank coal. The experimental results illustrated an improvement in the low rank coal flotability. It was found that this natural chemical reagent has a remarkable effect in the promoting of coal flotation as higher recovery and higher selectivity was obtained. In addition to the promoting effect, PYROLIZAT was found to have a collecting action better than that of standard diesel oil collector. The specifications of this promoter and its active functional groups is still under consideration.
Volume
72 Number
5
Research and coal combustion industry -
the twain shal1 meet
A. Sanyal
Energy and Environmental OH, USA
Research
Corporation,
Orville,
The coal utilization industry for power generation is currently faced with a greater challenge than ever before to meet the stringent environmental demand. World-wide research has been underway for improved understanding of the transformation of the coal ingredients which pose the environmental problems. Research activities have been faciiitated by the availability of advanced analytical techniques, diagnostic tools and bench/pilot-scale facilities. The paper overviews the state-of-the-art of research on combustion, slagging, fouling and trace elements and cites examples of successful applications of research in industry to minimize emissions and improve combustion efficiency. The author proposes a plan and its techno-economical justification for improved bridge-building between research and industry.
Abstracts
devices of small dimensions and weight, that are the result of a 15 year fundamental scientific investigation. A few devices and equipment may now be produced, and may be applied in mines and in laboratories. This includes four portable pieces of equipment for sampling and investigating samples which allow their hermetization and maximum conservation of their characteristics to be assured, decreasing considerably labour consumption and the duration of various laboratory investigations. It will promote a wider application of modern methods including computer systems for coal utilization and control and optimization of the environment.
the Q values were similar for all the samples except for the semianthracite, which as in the previous case was the lowest. The reactivity of the carbonized swollen coals towards CO, was higher for those coals with the higher Q value. However, the calculated
activation energy remains constant for the chars of the same coal. These results indicate that the enhancement of reactivity is due to the higher porosity of the swollen char which allows a better contact reactive gas and the active sites in the chars.
between
the
The promoting effect in the flotation of low rank coal A. M. Saleh and J. Iskra*
A multistage three-phase mathematical coal combustors G. I/: Reddy and Sriram
model for fluidized bed Mining Department, Faculty of Engineering, Alazhar University, Cairo, Egypt * Mineral Processing Institute, Faculty of Mining and Geology, Silesian Technical University, Gliwice, Poland
Prasad
Indian School of Mines, Department Engineering, Dhanbad-826004, India
of Fuel
and
Mineral
The multistage three-phase mathematical model developed by ElAlwagi and El-Rifai’ for gas-solid fluidized bed catalytic reactors has been applied to fluidized bed coal combustors with some modifications. The reaction rate constant for combustion has been derived by taking into account the coal particle population balance, particle reduction rates and particle surface temperature. The combustion reaction has been assumed to follow first order kinetics. The mode1 considers the fluidized bed combustor to be composed of a number of equivalent stages in series. In each stage the oxygen is assumed to pass from bubble to cloud wake phase and then to emulsion phase. The product gas, i.e. CO,, will pass in the reverse direction. It is further assumed that the release of volatile matter from the coal is instantaneous and it burns at the same rate as the char which is left behind after devolatilization. A salient feature of the model is the incorporation of particle size distribution. The simulated results have been compared to the 10 MW fluidized bed combustor plant data of TISCO Jamadoba, India. The combustion efficiency, exit gas composition and carbon load in the bed have been predicted and compared to plant data. The agreement between simulated and plant data is good. Utilizing the model, a number of illustrative predictions have been made; in particular the mode1 has bee used to predict the influence of coal feed particle size distribution on various combustion parameters. Useful inferences have been drawn based on these predictions. REFERENCE 1
El-H&@,
M. M. and El-Refai, M. A. Chem. Eng.
Sci.
1988. 41 (9). 2477
Reactivity of some Colombian coals towards CO*. Influence of swelling J. M. Rincdn, National BogotB,
G. Moreno
University, Department Colombia SA
Fuel 1993
Evaluation of the Recreio Flowsheet C. H. Sampaio,
L. A. C. Klujszo
COPELMI
and G. F. Cavalcante
Post-Graduate Program on Metallurgical and Materials Engineering (PPGEMM), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil The Recreio Flowsheet, belonging to ‘Companhia de Pesquisas e Lavras Minerais’ (COPELMI), Porto Alegre, Brazil, cleans two different kinds of coal, one from Recreio Mine and the other from Butia-Leste Mine, both open-pit mines. This work evaluates the coal preparation plant, which consists of coarses and fines circuit (Baum jig and hydrocyclones). Densimetric and granulometric analyses were done to determine the densimetric and granulometric partition curves and the performance criteria deriving from them. Studies were also made of the possible points of waste, such as size fraction -1 mm of the jig’s middle and refuse, undersize of the dewatering screen of the final fine product and scope of the hydrocyclone’s feeding sump. Ash was analysed in all the densimetric and granulometric fractions obtained. Proposals to increase the recovery of the process through operational improvements are suggested, as well as changes in the Flowsheet.
and S. Cruz of Chemistry,
Santafi:
de
Colombian coals are believed to be of Gondwanaland origin, which are characterized by a high concentration of inert macerals; therefore their behaviour towards processes like combustion and gasification may be different from coals of Europe and North America. Samples of coal from low rank to semianthracite were solvent swollen with butylamine and THF. After extraction of the solvent, the samples of the parent coal and solvent-treated coal were carbonized at 773 K and crushed to pass 147pm. The reactivity towards CO, of the carbonized products was measured using 2-5mg of char in a TGA equipment at 973,1073,1123 and 1173 K. The flushing gas was allowed to flow while heating (20 K min- ‘) and the starting tine for the reactivity measurement was taken after the sample had reached the programmed temperature. The swelling ratio (Q) of the samples treated with butylamine was higher than for those treated with THF. The highest Q value for butylamine was for the low rank coals (7678% C) and the lowest value was for the semianthracite. When THF was used as swelling solvent,
722
In this study, the promoting effect of a natural oil-breaking by-product (PYROLIZAT) was tested. The feed material used in this investigation was low rank coal. The experimental results illustrated an improvement in the low rank coal flotability. It was found that this natural chemical reagent has a remarkable effect in the promoting of coal flotation as higher recovery and higher selectivity was obtained. In addition to the promoting effect, PYROLIZAT was found to have a collecting action better than that of standard diesel oil collector. The specifications of this promoter and its active functional groups is still under consideration.
Volume
72 Number
5
Research and coal combustion industry -
the twain shal1 meet
A. Sanyal
Energy and Environmental OH, USA
Research
Corporation,
Orville,
The coal utilization industry for power generation is currently faced with a greater challenge than ever before to meet the stringent environmental demand. World-wide research has been underway for improved understanding of the transformation of the coal ingredients which pose the environmental problems. Research activities have been faciiitated by the availability of advanced analytical techniques, diagnostic tools and bench/pilot-scale facilities. The paper overviews the state-of-the-art of research on combustion, slagging, fouling and trace elements and cites examples of successful applications of research in industry to minimize emissions and improve combustion efficiency. The author proposes a plan and its techno-economical justification for improved bridge-building between research and industry.