Influence of organic chlorine on emissions from sludge incineration by a pilot fluidised bed furnace

2000 ◽  
Vol 42 (9) ◽  
pp. 243-250 ◽  
Author(s):  
G. Mininni ◽  
V. Lotito ◽  
L. Spinosa ◽  
E. Guerriero
Keyword(s):  
Sewage Sludge ◽  
Operating Conditions ◽  
Critical Conditions ◽  
Fluidised Bed ◽  
Sludge Incineration ◽  
Before And After ◽  
Afterburning Chamber ◽  
Organic Chlorine ◽  
Set Up ◽  
Circulating Fluidised Bed

To demonstrate that sewage sludge incineration could be a safe operation if well conducted and that hazardous compounds could also be disposed of without problems in sludge incinerators plants, a research program has been set up by the Italian Water Research Institute on a demonstrative scale plant where a completely circulating fluidised bed furnace and a rotary kiln furnace can operate alternatively. In this paper results of tests performed by a fluidised bed furnace on sewage sludge spiked with highly chlorinated compounds under different operating conditions are presented. A deep investigation on micropollutants formation has been made at different sampling points: before and after bag house filter, and at the chimney. The experimental data show that concentrations of PCDDs+PCDFs (TE) and of PAHs do not strictly depend on the operation of the afterburning chamber and that a complete compliance with the European and Italian standards on the emissions were always achieved even in the most critical conditions investigated.

Sludge incineration tests on circulating fluidised bed furnace

2001 ◽  
Vol 44 (2-3) ◽  
pp. 409-416
Author(s):  
V. Lotito ◽  
G. Mininni ◽  
A. C. Di Pinto ◽  
L. Spinosa
Keyword(s):  
Gas Phase ◽  
Aromatic Hydrocarbons ◽  
Polynuclear Aromatic Hydrocarbons ◽  
Fluidised Bed ◽  
Organic Micropollutants ◽  
Copper Addition ◽  
Sludge Incineration ◽  
Organic Chlorine ◽  
Acidic Compounds ◽  
Circulating Fluidised Bed

Results of sludge incineration tests on a demonstrative fluidised bed furnace are reported and discussed. They show that particulate, heavy metals and acidic compounds in the emissions can be easily controlled both when sludge is spiked with chlorinated hydrocarbons up to a chlorine concentration in the feed of 5%, and when the afterburner is switched off. As for organic micropollutants, polynuclear aromatic hydrocarbons (PAH) were much lower than the Italian limits of 10 μg/m3 (no limits are at present considered in the European Directives). Dioxins (PCDDs) and furans (PCDFs) in some tests exceeded the limit of 0.1 ng/m3 (TE) but the concentrations in the fly ashes were much lower, thus evidencing a possible presence of contaminants in gas phase. PAHs and PCDD/PCDFs were not depending on the afterburning operation, the presence of organic chlorine in the feed sludge and the copper addition to sewage sludge.

Behavior of Organic and Inorganic Micropollutants in Chlorine Spiked Sludge Incineration by a Circulating Fluidized Bed Furnace

2003 ◽  
Author(s):  
Giuseppe Mininni ◽  
Dario Marani ◽  
Camilla Maria Braguglia ◽  
Ettore Guerriero ◽  
Andrea Sbrilli
Keyword(s):  
Fluidized Bed ◽  
Flue Gas ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Operating Conditions ◽  
Metal Enrichment ◽  
Chlorinated Organic Compounds ◽  
Sludge Incineration ◽  
Before And After ◽  
Afterburning Chamber

The effects of combustion and feeding conditions on Polycyclic Aromatic Hydrocarbons (PAH) and PCDD/F formation and appearance in the emissions at the stack during sludge incineration are discussed in this paper. Partitioning in the solid streams of Cd, Cr, Cu, Mn, Ni, Pb and Zn is also analyzed. Tests were performed on a demonstrative plant equipped with a fluidized bed furnace (FBF) using sewage sludge either as is or spiked with chlorinated organic compounds (tetrachloroethylene or a mixture of tetrachloroethylene, chlorobenzene and toluene) to study the chlorine effect on the presence of micropollutants in the different streams. Exhaust gases were sampled both before and after the treatment system (bag house and wet scrubber). In the untreated flue gas the highest values of PCDD/F and PAH were detected when the afterburning chamber was not in use or operating at low temperatures. Operation of the afterburning chamber at temperature higher than 850–900 °C was sufficient to keep organic micropollutants concentrations in the untreated flue gas at reasonably low levels. No significant correlation of the operating conditions with emissions at the stack was found. High copper concentration in the feed enhanced PCDD/F formation, with exception of tests carried out with high afterburning temperature. The homologue profile of PCDD/F and PAH depended on test conditions. Preferential accumulation of heavy metals in the filter ash with respect to cyclone ash was quantified in terms of an enrichment factor. Out of the seven metals considered, only Cd and Pb undergo significant enrichment in the filter ash. The enrichment increased with increasing chlorine content of the feed. In contrast, Cu, Cr, Mn, Ni, and Zn behaved as refractory (non-volatile) elements even at high chlorine dosage. In accordance with the widely accepted hypothesis that metal enrichment is due to metal vaporization in the combustion chamber and subsequent condensation onto the filter ash particles, a thermodynamic model of the combustion process was able to satisfactorily predict the different metal behavior and the effect of chlorine dosage on metal enrichment.

Partitioning of Cr, Cu, Pb and Zn in sewage sludge incineration by rotary kiln and fluidized bed furnaces

2000 ◽  
Vol 41 (8) ◽  
pp. 61-68 ◽  
Author(s):  
G. Mininni ◽  
C. M. Braguglia ◽  
D. Marani
Keyword(s):  
Fly Ash ◽  
Sewage Sludge ◽  
Rotary Kiln ◽  
Bottom Ash ◽  
Point Of View ◽  
Fluidised Bed ◽  
Chlorinated Organic Compounds ◽  
Sludge Incineration ◽  
Significant Enrichment ◽  
The One

The behaviour of four metals (Cr, Cu, Pb, Zn) during sewage sludge incineration was studied in eight pilot plant tests performed with a rotary kiln (RK) and a fluidised bed (FB) furnace. To simulate sludge co-incineration with hazardous wastes, in three FB tests feed sludge was mixed with chlorinated organic compounds. Chromium and copper showed similar concentrations both in bottom or cyclone ash and in fly ash, even at high chlorine input and high combustion temperature. In contrast, zinc and lead concentrations in fly ash produced in RK tests are one or two orders of magnitude higher than those in bottom ash. However, not even these two metals showed significant enrichment in FB tests carried out at high chlorine input. The predictive capability of a thermodynamic model was checked by comparing predicted metal volatilisation in the combustion chamber with experimental metal enrichment in the fly ash. Large discrepancies were observed in FB tests carried out at high chlorine content, where Pb, Zn, and Cu are predicted to volatilise in great extent, andin RK tests where zinc volatilisation is not predicted. Likely explanations of these discrepancies are the very short solid residence times in the FB furnace (non equilibrium conditions) and the incomplete mixing conditions in the RK furnace (pyrolysis pockets). From the environmental impact point of view, the pilot tests suggest that sludge incineration with fluidised bed furnace is safer than the one using rotary kiln furnace.

Dynamic behaviour of sewage sludge incineration in a large-scale bubbling fluidised bed in relation to feeding-rate variations

Fuel ◽  
2008 ◽  
Vol 87 (8-9) ◽  
pp. 1552-1563 ◽  
Author(s):  
Yao Bin Yang ◽  
Lynne Sliwinski ◽  
Vida Sharifi ◽  
Jim Swithenbank
Keyword(s):  
Sewage Sludge ◽  
Large Scale ◽  
Feeding Rate ◽  
Dynamic Behaviour ◽  
Fluidised Bed ◽  
Sludge Incineration

A design model of sewage sludge incineration plants with energy recovery

1997 ◽  
Vol 36 (11) ◽  
pp. 211-218 ◽  
Author(s):  
G. Mininni ◽  
R. Di Bartolo Zuccarello ◽  
V. Lotito ◽  
L. Spinosa ◽  
A. C. Di Pinto
Keyword(s):  
Sewage Sludge ◽  
Energy Recovery ◽  
Electric Energy ◽  
Design Model ◽  
Gas Treatment ◽  
Treatment Line ◽  
Sludge Incineration ◽  
Afterburning Chamber ◽  
Sludge Cake ◽  
Sludge Drying

A design model of sewage sludge incineration plants has been developed to examine the possibilities for energy recovery. It was evident that, without sludge drying, there was a high fuel (methane) consumptions (149-192 Nm3/t sludge cake at 25% concentrations), but considerable amount of electric energy is obtainable (391-515 kWh/t sludge cake). Sizes of boiler and whole exhaust gases treatment line are in this case quite large. On the contrary, fuel consumption can be lowered down to 20 Nm3/t sludge cake at 44% concentration by introducing sludge drying. In this case fuel is needed only in the afterburning chamber, as the combustion in the fluidized bed furnace is autothermal. Boiler and exhaust gas treatment line are considerably reduced in size when power production is not performed, thus allowing a simpler and smaller plant to be designed.

Behaviour of Cd, Cr, Mn, Ni, Pb, and Zn in sewage sludge incineration by fluidised bed furnace

2003 ◽  
Vol 23 (2) ◽  
pp. 117-124 ◽  
Author(s):  
D Marani ◽  
C.M Braguglia ◽  
G Mininni ◽  
F Maccioni
Keyword(s):  
Sewage Sludge ◽  
Fluidised Bed ◽  
Sludge Incineration
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