Emission fluxes of heavy metals from the fluidized bed combustion of fossil fuels

Using high temperature fly ash for his pozzolan properties to cement composite production is known a few years ago. New ways combustion of fossil fuels also creates a new type of fly ash, named fluidized bed combustion fly ash. However, this fly ash has same pozzolan properties as has high temperature fly ash, this type is not using for production of cement composites. Fluidized bed combustion fly ash has highly variable chemical composition but usually it has a higher amount of free CaO together with sulphates. This higher amounts of free CaO after mixing of fluidized bed combustion fly ash with water to some extent becomes an activator for the beginning of the pozzolanic reaction, during which is consumed the extinguished CaO. If there is also present high temperature fly ash in cement composite, it could be accelerated his pozzolanic reaction in the same manner using a fluidized bed combustion fly ash. In this experiment was tested a synergy effect in the use of fluidized bed combustion fly ash with high temperature fly ash as an additive. The experiment was carried out on cement pastes that have been studied in particular the progress of hydration processes, pointing to a possible acceleration of pozzolanic reactions of both types of fly ash.

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Experimental Studies on Combustion of Cattle Manure in a Fluidized Bed Combustor

Journal of Energy Resources Technology ◽

10.1115/1.3231324 ◽

1987 ◽

Vol 109 (2) ◽

pp. 49-57 ◽

Cited By ~ 14

Author(s):

K. Annamalai ◽

M. Y. Ibrahim ◽

J. M. Sweeten

Keyword(s):

Fluidized Bed ◽

Fossil Fuels ◽

Experimental Studies ◽

Heat Content ◽

Fluidized Bed Combustion ◽

Volatile Solids ◽

Combustion Technology ◽

Solids Content ◽

Combustion Tests ◽

Fluidized Bed Combustor

Manure from cattle feedlots is a renewable energy source which has the potential of supplementing the existing fossil fuels. But the heat content of manure is rather low. Since, the fluidized bed combustion technology has been used for the energy conversion of marginal fuels, such a technology is being explored for the combustion of feedlot manure. A fluidized bed combustor of 0.15 m (6 in.) diameter was used for the combustion tests on manure. Experiments were conducted with −20 to +20 percent excess air and at bed temperatures ranging from 600°C (1112°F) to 800°C (1472°F). Experimental data revealed that the gasification efficiencies ranged from 90 to 98 percent, while the combustion efficiencies varied from 45 to 85 percent. Higher combustion efficiencies were obtained with decreased volatile solids content of manure. The low combustion efficiencies are attributed to the limited residence time available for the volatiles to burn within the reactor.

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Fluidized Bed Combustion: Technology for Efficient Utilization of Biomass Residues

Asian Journal of Engineering and Applied Technology ◽

10.51983/ajeat-2018.7.2.951 ◽

2018 ◽

Vol 7 (2) ◽

pp. 73-79

Author(s):

Vishal Sharma ◽

Rajeev Kamal Sharma

Keyword(s):

Fluidized Bed ◽

Fossil Fuels ◽

Renewable Energy Sources ◽

Biomass Combustion ◽

Fluidized Bed Combustion ◽

Technical Approach ◽

Fast Pace ◽

Combustion Technology ◽

Alternate Source ◽

Fluidized Bed Combustor

Fossil fuels are the most common and reliable energy source, which presently fulfill 80% energy requirements all across the world. In the last few decades, over-consumption, fast pace modernization and population growth are some prominent factors which are exploiting the fossil fuels. The degradation of natural resources has gone up at an alarming rate which provoked to look for an alternate source of energy. From all available alternative renewable energy sources, biomass is the only carbon-based sustainable option. But, its diversity makes it a complex and difficult fuel. Among all technologies used for energy generation from the biomass, fluidized bed combustion is emerging as a suitable best option to handle fuel diversity. This article deals with biomass fluidization and its combustion in a fluidized bed. The difficulties encountered during biomass combustion and different solutions for the same have been highlighted. Problems like deposition, corrosion, agglomeration and trace metal emission have been discussed and their remedies to avoid the discontinuity in the operation of biomass-fired fluidized bed combustor. This technical approach will help to reduce environmental problems, improve the economic structure of the nation, and remove obstacles for sustainable energy development.

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The Study of Partitioning of Heavy Metals During Fluidized Bed Combustion of Sewage Sludge and Coal

Journal of Energy Resources Technology ◽

10.1115/1.2126988 ◽

2005 ◽

Vol 128 (2) ◽

pp. 104-110 ◽

Cited By ~ 10

Author(s):

I. Gulyurtlu ◽

M. Helena Lopes ◽

P. Abelha ◽

I. Cabrita ◽

J. F. Santos Oliveira

Keyword(s):

Heavy Metals ◽

Sewage Sludge ◽

Fluidized Bed ◽

Bituminous Coal ◽

Fluidized Bed Combustion ◽

Sulphur Compounds ◽

Legal Limits ◽

Higher Temperature ◽

Combustion Tests ◽

Fluidized Bed Combustor

The behavior of Cd, Cr, Cu, Co, Mn, Ni, Pb, Zn, and Hg during the combustion tests of a dry granular sewage sludge on a fluidized bed combustor pilot (FBC) of about 0.3 MW was evaluated. The emissions of these heavy metals from mono-combustion were compared with those of co-combustion of the sludge with a bituminous coal. The effect of the addition of limestone was also studied in order to retain sulphur compounds and to verify its influence on the retention of heavy metals (HM). Heavy metals were collected and analyzed from different locations of the installation, which included the stack, the two cyclones, and the material removed from the bed. The results showed that the volatility of metals was rather low, resulting in emissions below the legal limits of the new directive on incineration, with the exception of Hg during the mono-combustion tests. The partitioning of metals, except for Hg, appeared to follow that of ashes, amounting to levels above 90% in the bed streams in the mono-combustion case. For co-combustion, there was a lower fixation of HM in the bed ashes, mostly originating essentially from the sewage sludge, ranging between 40% and 80%. It is believed that in this latter case, a slightly higher temperature could have enhanced the volatilization, especially of Cd and Pb. However these metals were then retained in fly ashes captured in the cyclones. In the case of Hg, the volatilisation was complete. The bed ashes were free of Hg and part of Hg was retained in the cyclones and the rest was emitted either with fine ash particles or in gaseous forms. In mono-combustion the Hg emissions from the stack (particles and gas) accounted for about 50%, although there was a significant amount unaccounted for. This appeared to have significantly decreased in the case of co-combustion, as only about 15% has been emitted, due to the retention effect of cyclone ashes which presented high quantities of unburned matter, calcium and sulphur.

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The effect of halides on emissions from circulating fluidized bed combustion of fossil fuels

Fuel ◽

10.1016/s0016-2361(96)00135-4 ◽

1996 ◽

Vol 75 (14) ◽

pp. 1655-1663 ◽

Cited By ~ 23

Author(s):

S. Julien ◽

C.M.H. Brereton ◽

C.J. Lim ◽

J.R. Grace ◽

E.J. Anthony

Keyword(s):

Fluidized Bed ◽

Fossil Fuels ◽

Circulating Fluidized Bed ◽

Fluidized Bed Combustion ◽

Circulating Fluidized Bed Combustion

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Volatilization of the Heavy Metals during Circulating Fluidized Bed Combustion of Forest Residue

Environmental Science & Technology ◽

10.1021/es9802596 ◽

1999 ◽

Vol 33 (3) ◽

pp. 496-502 ◽

Cited By ~ 75

Author(s):

Terttaliisa Lind ◽

Tuomas Valmari ◽

Esko I. Kauppinen ◽

George Sfiris ◽

Kristina Nilsson ◽

...

Keyword(s):

Heavy Metals ◽

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Fluidized Bed Combustion ◽

Forest Residue ◽

Circulating Fluidized Bed Combustion

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The distribution of heavy metals during fluidized bed combustion of sludge (FBSC)

Journal of Hazardous Materials ◽

10.1016/j.jhazmat.2007.05.056 ◽

2008 ◽

Vol 151 (1) ◽

pp. 96-102 ◽

Cited By ~ 80

Author(s):

M. Van de Velden ◽

R. Dewil ◽

J. Baeyens ◽

L. Josson ◽

P. Lanssens

Keyword(s):

Heavy Metals ◽

Fluidized Bed ◽

Fluidized Bed Combustion

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Combustion Characteristics of Heavy Liquid Fuels in a Bubbling Fluidized Bed

Journal of Energy Resources Technology ◽

10.1115/1.1446475 ◽

2002 ◽

Vol 124 (1) ◽

pp. 40-46 ◽

Cited By ~ 4

Author(s):

E. J. Anthony ◽

D. Y. Lu ◽

J. Q. Zhang

Keyword(s):

Heavy Metals ◽

Fluidized Bed ◽

Flue Gas ◽

Liquid Fuel ◽

Pilot Scale ◽

Liquid Fuels ◽

Feeding System ◽

Fluidized Bed Combustion ◽

Fuel Flexibility ◽

Bubbling Fluidized Bed

Liquid fuels such as bitumen, tars, and pitches are byproducts of heavy oil upgrading processes, and are usually contaminated with high sulphur and sometimes heavy metals contents as well. Fluidized bed combustion (FBC) appears to be a promising technology for the combustion of such fuels due to its inherent fuel flexibility and low emissions characteristics. The combustion of three liquid fuels, i.e., no. 6 oil, bitumen and pitch was investigated in a pilot-scale bubbling FBC unit. An efficient liquid fuel feeding system was developed and a bubbling FBC was successfully used to combust all three liquid fuels. The proportion of fuel escaping in the form of unburnt hydrocarbons in the flue gas was less than 0.4 percent and combustion efficiencies higher than 98.5 percent were achieved. However, combustion of liquid fuels tended to occur in the freeboard and, therefore, good mixing of the fuels in the bed was critical in achieving satisfactory combustion performance.

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