02157 Laser ignition and combustion of pulverized coals

09

Fluidized bed combustion of solid organic 97102148 and low-grade coals: research and modeling

wastes

Borodulya, V. A. <‘I rrl. PIW. /,tr. C‘orlf Fhid. Bed Con~hmt.. 1995. 13. ( 2). Y35-Y42. Studies were carried out to study devolatilization and combustion of single spherical particles of wood. hydrolytic lignin from ethanol production, leather processing wastewater sludge. and low-grade Belarus brown coals in a fluidized hed of sand. A two-phase model of hiowaste fluidized bed combustion i\ proptrsed. The model accounts for combustion of both volatiles and char in the hed and in the freeboard. The characteristics of devolatilization and char combustionderived from the experiments are used as parameter\ of the proposed model.

FTIR analysis of transient carbon 97102149 sions in a circulating fluidized bed boiler Raincs, T. S. 1096. 140 pp. Avail. degree-granting rlh\rr. In,.. u I’)%. 57(4). 2x30.

dioxide

institution.

97102150 Fuel and ash characterization their suitability in fluidized bed combustion8

of Indian

emis-

From Dis.,.

coal for

Palit. A. and Mandal. P. K. pro<,. /,rf. Cortf: F/r&. Arrl Cornhlr\/.. IYYS. 13. (2). 1433-1445. Coal fuel and ;~.>hcharactrri\tics, and the effects of coal properties on fluidiTed-hcd combustion are Investigated. The propertie? discussed include ImoI*Iturc. mincral/ahh content. volatile matter-, rn-aceral structure (petrographical properties). \wellingicaking index. ash properties including ash fusion temperature. The experience with a IO MW FBC unit, and cxprrlmental investigations on suitability of Lalmatia coal (Rajmahal coal lield) in fluidizcd-hcd combustion and pollutants formation, arc also t(,uched up,,n.

Fuel-gas injection to reduce 97102151 the combustion of coal in a fluidized bed

N20 emissions

from

Marhan. G. cf ol. Cornh~r,t. Flanrc. 1906. 107, (112).103-l 13. Thiq experiment utilized a laboratory-scnle, fluidized-hed reactor (29 mm i.d.) In which a stream of simulated combustion gases was passed through a countercurrent flame of tither methane nr propane. The effects of NIO concentration. hcd temperature. and added gases (e.g. NO, SO:. OL. and N? or He carrier gas) on N,O reduction were analysed. An attempt to establish whether N?O decomposition in the flame proceeds via radical or thermal mechanisms was carried nut. Up to 99% N,O decomposition was achieved at a gas-02 equivalence ratio of 0.83 (I? vol.? 02) and a total flow rate of I I:min. for both methane and propane injected into the reactor. Under the conditions used, thermal decomposition accounts for only IO? of the high NZO convers,ons achieved in the flame. with radical mechanisms playing a maior role.

97102152 Hydropyrolysis and hydrodenitrogenationtechnological aspects of studies on coal Kisielo~. W. (‘t nl. /‘r-on. C‘l~cm.. 1906, 75. (9), 32Y-332. (In Polish) This paper discusse\ the technological aspects of the industrial hydropyrolysis. Hydropyrolysis of coals of increased sulfur content yields valuable raw materials and ecologically sound fuels. Direct combustion of the carbonization product allows tn generate power with yield reaching 43% while limiting the sulfur dioxide emissions hy 90% compared to conventional coal combustion. A hydrorefining catalyst for coal liquids WBF developed which removed up to 85? nitrogen.

97102153 In-situ FT-IR diagnostics of fossil fuel combustion

for monitoring

and control

Bonanno. A. S. (11ul. Proc. Annr,. /nr. f’irrshltr$ Cotrl Con/‘.. l9Y.5. 12, 429434 The design and development of a prototype Fourier-transform IR (FT.IR)hased measurement system was carried out for continuous emission monitoring (CEM) and process control in fossil fuel-fired power plants. The prototype systems were transported. assembled, and tested at full-scale and pilot-scale fossil fuel-fired comhustors. The observed trends in NH,, NO. and CO concentrations were found as expected in relation to reagent Injection rate (e.g. urea) and injection-zone temperatures. In general, good agreement was found between FT-IR data and independently measured CO and NO concentration\

97102154 Influence of conversion to low NO, combustion fly ash petrology and mineralogy: A case study

on

Kohl. T. L. CI trl. Proc,. Anrru. IHI. /‘i/trhurgh Coal Conf., lY95, 12. 121-l 2.5. The wall-fired II6 MW unit 2 at the John Sherman Cooper Station, Pulaski County. Kentucky, wa\ converted to low-NO, combustion in the winter of 1903-1994. A detailed studv of the fly ash produced before and after the conversion was carried out:The fly ash carbon can be divided into three types: anisotropic coke, isotropic coke and inertinite. The post-conversion fly a‘;h has nearly twice the amount of carbon as the preconversion ash and shows an increase in anisotropic coke. Mullite and quartz were observed to he petrographically more abundant in the post-conversion fly ash. although only the mullite increase was confirmed hy XRD. The proportion of glass is slightly less in the post-conversion ash and is accompanied by one-third drop in the amount of cenoqphercs.

Combustion

(burners, combustion

systems)

97102155 pyrolysis

Interaction of the organic matrix with pyrite during of a high-sulfur bituminous coal Grvglewicz. G. et 01. F&, 1996, 75, (l3), 1499-1504. Th;-interaction between pyritic sulfur and the organic part of coal during pyrolysis was examined using high-sulfur bituminous coal containing 4.17 wt.q of pyritic sulfur and the pyrite concentrate separated from this coal. The results demonstrate that the decomposition of pyrite is markedl) affected by the presence of the organic coal suh$tance.

97102156 Kinetic analysis on combustion of lignite

of DSC and thermogravimetric

data

Kok, M. V. and Okandan, E. .I. Tlrern~. .4n(rl., IYY(,. 46, (6). lhS7-1660. A comparative study of several methods used to analyse differential scanning calorimetry (DSC) and TG!DTG data obtained on the oxidation of Beypazari lignite are used in this work. A general computer program was developed and the methods are compared with regard to their accuracy and the ease of interpretation of the kinetics of thermal decomposition The ratio method was regarded as the preferred method. hecauce it permits the simultaneous estimation of reaction order. activation energ\ and Arrheniu\ constant from a single experiment. 97/02157 Laser ignition and combustion of pulverized coals Chen. J. C. Proc. Ar~rr~c. In,. Piftshru~h Cool c‘mj’,. IY95. 12, 04Y-0.54. High-speed video was used to makr direct observation of pulsed-laser ignition and combustion of pulverized coals. Thr ignition and comhuation hehaviours of amorphous carbon spheres and an anthracite were a\ expected for heterogeneous ignition and rcactlon. Surprisingly. the reaction of a high-volatile bituminous coal and a \uhhltumlnous coal was accompanied hy two broad emissions ot light. a\ detected with a photomultiplier tube. For these coals. high-speed videos revealed that two successive clouds of burning volatile\ surrounded the particles. and each cloud was associated with one of the emissions. A pos\ihle explanation for thi\ finding is proposed in this paper. 97102158

centrations

Laser-based non-intrusive measurements and temperatures in technical combustion

of condevices

Ehert. V. CI nl. Teclr. MESS., l9Yh. 63. (7’8). 2hR-277. (In German) This paper reviews laqer-induced fluorescence, Rayleighand MIEscattering. fragmentation fluorescence. NIR emission and absorption spectroscopy in premixed gas flames. automohilc cnglnc\. prcssurizcd fluidizcd-hed coal combustion. and waste Incinerators.

97102159 A mathematical MW FBC power plant

model for coal combustion

in a lo-

Reddy. G. V. and Sinha, A. Enc,r~~. April lY97, 22, (4). 381-3X7. Presents a mathematical model which has been developed for the exit-gas composition 111 a IO-MW fluidized bed Cl)ill-conlhustion power plant operated at Jamadoha. Model predictions are compared with plant data and reasonable agreement is ohtained.

97102160 A mathematical fluidized bed combustion.

model for pressurized

circulating

Heinhockel. I. and Fett, F. N. Proc. Inf. (‘otrf. b?rr,r/. Be(/ C‘omhrrtr.. lYY5. 13, (2). 1283-1301. Discusses that pressurized fluidized bed combustion i\ one of the mo\t promising techniques for high efficiency and low emission power generation from hard and brown coal. Mathematical modelling and simulation may facilitate understanding, development and operation of this new process. Work carried out upon mathematical model\ for the simulation of tluidized bed coal combustion comprises the simulation of steadv state and transient hehaviour of atmospheric bubbling and circulating fliidized bed comhustars based on hard and brown coal as well as the steam generator and the control system. The work has been extended to combined cycle processes hy modelling the steady state behaviour of a prea\uriLed circulating fluidized bed comhustor (PCFBC) for hard coal.

97102161 Mathematical modeling of fluidized-bed tion. 1. Combustion of carbon in bubbling beds

combus-

Sriramulu. S. ef al. F~rel. 1996. 75, (12). 1351-1362. The development of a three-phase model for carbon combustion in fluidized beds to take into account the effect\ of gas haclunixing and solids circulation was undertaken. Inclusion of thess phenomena i\ expected ultimately to he important in extending the fluidized hed combustion model to predict NZO emissions. Transient mass and energy halance equations are presented in this paper for the fast bubble regime. These equations can hc easily modified for the slow huhhle operating regime. It is possible ttr compare the predictive capability of the model with puhli\hed data on combustion rates and these comparisons show that improvement in the predictive capabilities of the model depend\ on ability to predict the product CO/CO2 ratio.

97102162 The measurement using infrared photoacoustics

of unburned

carbon

in fly ash

Wailer. D. J. and Brown. R. C. Pro,. .4)1)1!(. Irrr. Piff.shurgh <~~a/ C‘mf.. 1995, 12. 417-422. Valuable information on coal combustion efficiency in coa-fired boilers can he obtained from unburned carbon in fly ash yields. The carbon content of fly ash is also an important parameter in the sale of fly a%h for Portland

Fuel and Energy Abstracts

May 1997

173