Properties and Environmental Considerations Related to AFBC Solid Residues

1986 ◽  
Vol 86 ◽  
Author(s):  
E. E. Berry ◽  
E. J. Anthony
Keyword(s):  
Trace Elements ◽  
Fluidized Bed ◽  
Temperature Rise ◽  
Atmospheric Pressure ◽  
Alkaline Ph ◽  
Fluidized Bed Combustion ◽  
Dissolved Solids ◽  
Factors Influencing ◽  
Coal Ashes ◽  
Environmental Considerations

ABSTRACTAtmospheric-pressure fluidized bed combustion (AFBC) produces solid residues that are different from the familiar pulverized coal ashes. When limestone beds are used to adsorb SOx, high-Ca residues, comprised largely of CaO and SO4, are produced. Leachates from high-Ca AFBC residues are strongly alkaline (pH >11) and contain high levels of dissolved solids (TDS >3000 mg/L). If water is added during handling, hydration of CaO may cause a temperature rise and hydration of CaSO4 may result in premature hardening of the residues. Trace elements and organic components may leach from disposal sites. This paper presents an overview of the nature of AFBC residues and the factors influencing their disposal.

Partitioning of Trace Elements During Fluidized Bed Combustion of High Ash Content Lignite

2005 ◽  
Author(s):  
Nevin Selc¸uk ◽  
Yusuf Gogebakan ◽  
Zuhal Gogebakan
Keyword(s):  
Trace Elements ◽  
Fly Ash ◽  
Fluidized Bed ◽  
Inductively Coupled Plasma ◽  
Bottom Ash ◽  
Ash Content ◽  
Fluidized Bed Combustion ◽  
Test Rig ◽  
Minor Elements ◽  
Element Partitioning

The behavior of 20 trace elements (As, B, Ba, Cd, Co, Cr, Cu, Hg, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Sn, Tl, V, Zn) and 8 major and minor elements (Al, Ca, Fe, K, Mg, Na, Si, Ti) during the combustion of high ash content lignite with and without limestone addition have been investigated in the 0.3 MWt Middle East Technical University (METU) Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) Test Rig. Experiments were performed without fines recycle. Inert bed material utilized in the experiments was bed ash obtained previously from the combustion of the same lignite without limestone addition in the same test rig. Concentrations of trace elements in coal, limestone, bottom ash, cyclone ash and filter ash were determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Measurements show that the distribution of major and minor elements follows the ash split between the bottom ash and fly ash and that the major proportion of most of the trace elements (As, Ba, Cr, Hg, Li, Mo, Ni, Sn, V, Zn) are recovered in fly ash. Comparisons between the trace element partitioning of the runs with and without limestone addition reveal that addition of limestone shifts the partitioning of Ba, Cr, Hg, Mo, Ni, Sn, V, Zn from bottom ash to fly ash.

Simultaneous CO2 and SO2 Capture at Fluidized Bed Combustion Temperatures

2005 ◽  
Author(s):  
P. Sun ◽  
J. R. Grace ◽  
C. J. Lim ◽  
E. J. Anthony
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Fluidized Bed ◽  
Co2 Capture ◽  
Atmospheric Pressure ◽  
Pressure Range ◽  
Operating Conditions ◽  
The Other ◽  
Fluidized Bed Combustion ◽  
So2 Capture

Simultaneous carbonation and sulphation have been investigated to simulate non-calcining conditions at FBC temperatures (750–850°C) using an atmospheric-pressure thermogravimetric reactor (TGR) with up to 80% CO2 in the gas stream to extend the pressure range of applicability of the results. This investigation was undertaken to provide insight on simultaneous carbonation and sulphation and to provide knowledge relevant to FBC, including PFBC, operations. Two calcium-based sorbents (one limestone and one dolomite) were tested with particles of diameter 212–250 μm and 500–600 to determine the effects of operating conditions such as temperature, CO2 and SO2 concentrations, particle size and reaction time on the sorbent performance. SO2 was found to impede CO2 capture; on the other hand, CO2 enhanced the capture of SO2. The calcination rate was also observed to decrease as a result of the presence of the sulphate layer.

scholarly journals Emissions of SO3 from a Coal-Fired Fluidized Bed under Normal and Staged Combustion

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Wasi Z. Khan ◽  
Bernard M. Gibbs ◽  
Assem Ayaganova
Keyword(s):  
Fluidized Bed ◽  
Atmospheric Pressure ◽  
Fluidized Bed Combustion ◽  
Staged Combustion ◽  
Bed Height ◽  
Excess Air ◽  
Bed Temperature ◽  
Wide Range ◽  
Level 1 ◽  
Secondary Air

This paper reports the measurements of SO3 emissions with and without limestone under unstaged and staged fluidized-bed combustion, carried out on a  m2 and 2 m high stainless-steel combustor at atmospheric pressure. The secondary air was injected 100 cm above the distributor. SO3 emissions were monitored for staging levels of 85 : 15, 70 : 30, and 60 : 40, equivalent to a primary air/coal ratio (PACR) of ~0.86, 0.75, and 0.67. Experiments were carried out at 0%–60% excess air level, 1-2 m/s fluidizing velocity, 800–850°C bed temperature, and 20–30 cm bed height. During unstaged combustion runs, SO3 emissions were monitored for a wide range of Ca/S ratios from 0.5 to 13. However, for the staged combustion runs, the Ca/S ratio was fixed at 3. SO3 was retained to a lesser extent than SO2, suggesting that SO2 reacts preferentially with CaO and that SO3 is involved in the sulphation process to a lesser degree. The SO3 emissions were found to be affected by excess air, whereas the fluidizing velocity and bed temperature had little effect. SO3 was depressed on the addition of limestone during both the staged and unstaged operations, and the extent of the reduction was higher under staged combustion.

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