In-Furnace Sulfur Capture by Cofiring Coal With Alkali-Based Sorbents

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Emad Rokni ◽  
Hsun Hsein Chi ◽  
Yiannis A. Levendis
Keyword(s):  
Alkali Metals ◽  
Nox Reduction ◽  
Sulfur Oxide ◽  
Drop Tube ◽  
So2 Emissions ◽  
Sodium Potassium ◽  
Molar Ratios ◽  
High Sulfur Content ◽  
Coal Particles ◽  
Sorbent Injection

This manuscript presents experimental results on the reduction of sulfur oxide emissions from combustion of a high-sulfur content pulverized bituminous coal (Illinois #6 Macoupin) using a dry sorbent injection method. The coal particles were in the size range of 90–125 μm and were blended with calcium-, sodium-, potassium-, and magnesium-containing powdered sorbents at different proportions. The alkali/sulfur molar ratios were chosen to correspond to stoichiometric proportions (Ca/S = 1, Mg/S = 1, Na2/S = 1, and K2/S = 1) and the effectiveness of each alkali or alkali earth based sorbent was evaluated separately. Combustion of coal took place in a drop-tube furnace, electrically heated to 1400 K under fuel-lean conditions. The evolution of combustion effluent gases, such as NOx, SO2, and CO2 was monitored and compared among the different sorbent cases. The use of these sorbents helps to resolve the potential of different alkali metals for effective in-furnace sulfur oxide capture and possible NOx reduction. It also assesses the effectiveness of various chemical compounds of the alkalis, such as oxides, carbonates, peroxides, and acetates. Reductions in SO2 emissions were in the range of 5–72%, with sodium being the most effective metal followed by potassium, calcium, and then magnesium. Acetates were effective as dual SO2 and NOx reduction agents.

In-Furnace Sulfur Capture by Co-Firing Coal With Alkali-Based Sorbents

2016 ◽  
Author(s):  
Emad Rokni ◽  
Hsun Hsien Chi ◽  
Yiannis A. Levendis
Keyword(s):  
Sulfur Dioxide ◽  
Sulfur Content ◽  
Flue Gas ◽  
Alternative Energy ◽  
Alkali Metals ◽  
Operating Conditions ◽  
Flue Gas Desulfurization ◽  
Sulfur Oxide ◽  
Drop Tube ◽  
Coal Particles

Over the last quarter of a century, since the 1990 US Clean Air Act Amendments were enacted the gaseous sulfur emission, in the form of sulfur dioxide, have been reduced [1] by a factor of 4, by switching to lower sulfur content coals, installation of flue gas desulfurization (FGD) sorbents or switching altogether to natural gas as a fuel. Penetration of alternative energy generation also has had a positive impact. However, current emissions of sulfur dioxide are still voluminous, amounting to 3,242,000 short tons annually in the USA [2]. As wet flue gas desulfurization is both real-estate- and capital-intensive, infurnace dry sorbent injection has been considered over the years to be a viable alternative. However there is still uncertainty on the best selection of the sorbents for particular coals and furnace operating conditions. This is particularly the case when it is economically attractive for the power-plant operator to burn locally-sourced high-sulfur coal, such as the case of Illinois bituminous coals. This manuscript presents experimental results on the reduction of sulfur oxide emissions from combustion of a high-sulfur content pulverized bituminous coal (Illinois #6 Macoupin). The coal particles were in the size range of 90–125 μm and were blended with dry calcium-, sodium-, potassium-, and magnesium-containing powdered sorbents at different proportions. The alkali/S molar ratios were chosen to be at stoichiometric proportions (Ca/S = 1, Mg/S = 1, Na2/S = 2, and K2/S = 2) and the effectiveness of each alkali or alkali earth based sorbent was evaluated separately. Combustion of coal took place in a drop-tube furnace, electrically-heated to 1400 K under fuel-lean conditions. The evolution of combustion effluent gases, such as NOx, SO2 and CO2 were monitored and compared among the different sorbent cases. The use of these sorbents helps to resolve the potential of different alkali metals for effective in-furnace sulfur oxide capture and possible NOx reduction. It also assesses the effectiveness of various chemical compounds of the alkalis, such as oxides, carbonates, peroxides and acetates.

Co-Firing of Steam Coal With High Sulfur Content Lignite in a Bubbling Fluidized Bed Combustor

2005 ◽  
Author(s):  
Nevin Selc¸uk ◽  
Yusuf Gogebakan ◽  
Hakan Altindag
Keyword(s):  
Fluidized Bed ◽  
Molar Ratio ◽  
So2 Emissions ◽  
Molar Ratios ◽  
High Sulfur Content ◽  
Bubbling Fluidized Bed ◽  
On Line ◽  
Emission Behavior ◽  
Nitrogen Contents ◽  
Fluidized Bed Combustor

Combustion and emission behavior of 100 % steam coal (SET 1) and a mixture of 80 % by weight steam coal and 20 % by weight local lignite, characterized by high sulfur and ash contents, (SET 2) were investigated in the 0.3 MWt Middle East Technical University (METU) Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) Test Rig. Experiments were performed with limestone addition at various Ca/S molar ratios with fines recycle. In both sets of experiments, parameters other than Ca/S molar ratio were held as nearly constant as possible. On-line measurements of O2, CO2, CO, SO2, NOx emissions were carried out. Comparisons between the emissions show that lower NOx and SO2 emissions are obtained from combustion of steam coal/lignite mixture compared to those from steam coal only despite higher sulfur and almost equal nitrogen contents of the mixture. Calculated combustion efficiencies were found to be around 98 and 96 % for SET 1 and SET 2, respectively. As for the sulfur retention efficiencies, up to three times higher efficiencies were achieved when steam coal is co-fired with high sulfur lignite.

A Convenient Method of Distillation of the Alkali Metals

1927 ◽  
Vol 23 (8) ◽  
pp. 953-955 ◽  
Author(s):  
R. J. Clark
Keyword(s):  
Convenient Method ◽  
Alkali Metals ◽  
Mercury Vapour ◽  
Sodium Potassium

The alkali metals, sodium, potassium and rubidium can be distilled easily in a good vacuum and obtained reasonably free from occluded gas in the following way. As potassium is now used for the absorption of mercury vapour and many experiments are being done on the others, an account of a convenient way of preparing pure specimens may be of some service to experimenters.

The de Haas–van Alphen effect in alkali metals

1964 ◽  
Vol 281 (1384) ◽  
pp. 62-91 ◽  
Keyword(s):  
Fermi Surface ◽  
Field Dependence ◽  
Alkali Metals ◽  
Spherical Shape ◽  
Orientation Dependence ◽  
Sodium Potassium ◽  
Fermi Surfaces ◽  
Fixed Orientation ◽  
Absolute Amplitude ◽  
Structure Calculations

A new method for studying the de Haas–van Alphen effect in steady magnetic fields has been developed in which the field is modulated at frequency ω and a signal at frequency 2 ω is generated in a pick-up coil round the specimen because of the non-linear field dependence of magnetization. The rectified 2 ω signal is proportional to d 2 M /dH 2 and so shows de Haas–van Alphen oscillations either when H is varied for fixed orientation or when the orientation is varied in fixed H if the Fermi surface is anisotropic. Because the phase of oscillation is very high (of order 10 4 π ) even very slight anisotropy will produce a few oscillations when the orientation is varied and the method is therefore particularly sensitive for studying very nearly spherical Fermi surfaces. From the oscillations with H , values of the frequency F were found for sodium, potassium, rubidium and caesium which were close to those predicted for a free-electron sphere containing 1 electron per atom, though some small systematic deviations of order ½ % were observed which may be significant. From detailed study of the oscillations produced by rotation of single crystals in fixed H it was found possible to describe the orientation dependence of F (proportional to the area of cross-section of the Fermi surface) for potassium and rubidium consistently by a series of cubic harmonics and hence to deduce the small departures of the Fermi surfaces from spherical shape. The deviations from a sphere were found to be of the order of 1 part in 10 3 for potassium and a little less than 1 part in 10 2 for rubidium; these deviations are compared with those predicted by band structure calculations. Preliminary results for sodium suggest that it is appreciably less anisotropic than potassium. Some results are also reported on the temperature and field dependence and the absolute amplitude of the de Haas-van Alphen effect, and it is also shown how the effect can be used to measure very small variations of field with position.

A preliminary study of the influence of alkali-metal promoters on the selectivity and activity of vanadium catalysts in the oxidation of naphthalene

1981 ◽  
Vol 34 (6) ◽  
pp. 1325 ◽  
Author(s):  
NR Foster ◽  
MS Wainwright ◽  
DWB Westerman
Keyword(s):  
Alkali Metal ◽  
Partial Oxidation ◽  
Alkali Metals ◽  
Catalyst Activity ◽  
Fixed Bed ◽  
Oxidation Products ◽  
Metal Sulfate ◽  
Sodium Potassium ◽  
Fixed Bed Reactors ◽  
Preliminary Study

The oxidation of naphthalene over vanadia catalysts promoted by alkali- metal sulfates was studied in the temperature range 400-440°C. The effects of SO3 levels and alkali-metal sulfate promoter type on catalyst activity and selectivity were investigated in laboratory fixed-bed reactors employing integral conversions. ��� The relative promoting abilities of the alkali metals sodium, potassium, rubidium and caesium were investigated with laboratory catalyst preparations. Alkali metals of higher atomic number favoured selectivity to partial oxidation products with an associated loss in overall activity.

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