The kinetics and mechanism of alkali removal from flue gases by solid sorbents

Uberoi, M.; Punjak, W.A.; Shadman, Farhang

doi:10.1016/0360-1285(90)90029-3

Cited by 114 publications

(97 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Various technologies for reducing ash deposition as well as corrosion have been studied. These include: (1) [10,20,41,[60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76]; (2) co-firing bio-fuels with low fouling-tendency fuels [8,55,[77][78][79][80][81]; (3) pretreatment of the feedstock to reduce the alkali metals [82,83], and (4) modification of the boiler (e.g., modification of the re-heater and super-heater in order to allow for larger spacing, more soot-blowing and a decrease in the live steam temperature to less than 500 °C, etc.) [60].…”

Section: Technologies For Reducing Ash Deposition and Corrosionmentioning

confidence: 99%

“…Al-Si-type additives are mostly the first choice in the literatures [61,62,[67][68][69]72] due to their strong ability for converting vapor/liquid-phase KCl and KSiO 3 to potassium aluminum silicates (e.g., KAlSiO 4 , KAlSi 2 O 6 , KAlSi 3 O 8 , etc.) with high melting-points (>1100 °C) by the reactions indicated in Equation (3).…”

Section: Addition Of Combustion Additivesmentioning

confidence: 99%

See 1 more Smart Citation

Ash Deposition in Biomass Combustion or Co-Firing for Power/Heat Generation

et al. 2012

View full text Add to dashboard Cite

This paper presents a concise overview of ash deposition in combustion or co-firing of biomass (woody biomass, agricultural residues, peat, etc.) with other fuels for power/heat generation. In this article, the following five research aspects on biomass combustion ash deposition are reviewed and discussed: influence of biomass fuel characteristics, deposit-related challenges, ash deposition monitoring and analysis of ash deposits, mechanisms and chemistry of fly ash deposition, and key technologies for reducing ash deposition and corrosion in biomass-involved combustion.

show abstract

Section: Technologies For Reducing Ash Deposition and Corrosionmentioning

confidence: 99%

Section: Addition Of Combustion Additivesmentioning

confidence: 99%

Ash Deposition in Biomass Combustion or Co-Firing for Power/Heat Generation

et al. 2012

View full text Add to dashboard Cite

show abstract

“…The glassy surface was determined to be sodium silicate, Na 2 SiO 5 , complexed with increasing amounts of SiO 2 at greater distance from the surface. Feldspar was present in the region below the glassy layer in the partially reacted pellet.Independent results of TGA experiments to determine the gettering qualities of emathlite reported by Punjak et al 21 and Uberoi et al 22 are shown in Figure 2. Unlike the results 19 of Figure 1, the sample appears to be approaching an adsorptive capacity of about 150 mg Na g -1 sorbent after only 40 h of exposure.…”

mentioning

confidence: 99%

“…1 . 4 Effects of Gas ConcentrationPunjak et al 21 and Uberoi et al 22 reported results of short duration TGA tests in a range of 2 to 4 h, with NaCl gas concentrations of 65, 80, and 125 ppmv, a temperature of 800°C and atmospheric pressure. As shown in Figure 4, higher rates of getter flake weight gain were evident in the higher-concentration NaCl environment, exhibiting a nearly linear dependence on gas concentration in these short-duration tests.…”

mentioning

confidence: 99%

“…The larger dimensions of the pelleted sample and lower vapor concentrations of NaCl would limit mass transport to the interior of the pellet. Formation of a glassy deposit on the surface may also affect mass transport and limit complete saturation of the pellet.X-ray diffraction analysis of the saturated samples 21,22 indicated that Na had reacted with the emathlite matrix to form albite, Na 2 O·Al 2 O 3 ·6SiO 2 . Albite has the same atom ratios as feldspar, NaAlSi 3 O 8 , reported by Bachovchin et al 19 The presence of Cl was not detected in the saturated material, and Punjak et al proposed the following reaction to describe the sorption process:…”

mentioning

confidence: 99%

See 1 more Smart Citation

Control of alkali species in gasification systems: Final report

Turn¹,

Kinoshita²,

Ishimura³

et al. 2000

View full text Add to dashboard Cite

Gas-phase alkali metal compounds contribute to fouling, slagging, corrosion, and agglomeration problems in energy conversion facilities. One mitigation strategy applicable at high temperature is to pass the gas stream through a fixed bed of sorbent or getter material, which preferentially adsorbs alkali via physical adsorption or chemisorption. This report presents results of an experimental investigation of high-temperature (600° to 700°C) alkali removal from a hot filtered gasifier product gas stream using a packed bed of sorbent material. Two getter materials, activated bauxite and emathlite, were tested at two levels of space time (0.7 and 1.5 s) by using two interchangeable reactors of different internal diameters (51 and 76 mm). The effect of getter particle size was also investigated.The experimental apparatus consisted of a bench-scale fluidized bed gasifier, a hot ceramic filter unit, and a packed bed alkali getter reactor. Banagrass, a candidate crop for tropical and subtropical dedicated feedstock supply systems, was used as fuel. Banagrass's high K and Cl content facilitates experimental measurement of these trace elements at levels well above analytical detection limits. Potassium, Na, and Cl concentrations in the gas stream exiting the filter were 28, 11, and 1,300 ppmw, respectively, with total alkali to Cl ratios of ~0.03, indicating that Cl is present in forms other than alkali chlorides. Potassium and Na removal efficiencies by the getter beds were >99% and >92%, respectively, for all tests, with no apparent differences attributable to the variables tested: getter material, space time, or getter particle size. The highest concentrations of K and Na in the getter materials were measured in the sorbent recovered from the top 5 cm (inlet) of the packed bed. Average alkali concentrations of 4.6 mg K g -1 sorbent and 1.1 mg Na g -1 sorbent were measured in the 51-mm diameter reactor tests. Alkali concentrations in the top 5 cm of the 76-mm diameter reactor were lower because of the greater sorbent material volume.Element balances around the getter reactor for K, Na, and Cl were generally poor because of the small analyte masses, compared to the total getter mass in the reactor. Element balances around the gasifier/ceramic filter/getter reactor system were generally acceptable. Carbon balances ranged from 93% to 103% of complete closure, with carbon conversion efficiencies on the order of 93%. Balances for K, which were present as ~1% of fuel mass, varied from 75% to 91% of closure. Balances for Cl (~0.6% of fuel mass) showed a wider range, from 63% to 93% of full closure. Sodium was present as ~0.1% of fuel mass, and elemental balances were in the range of 63% to 150%.i . Distribution of the Na mass present in the input fuel among 62 the outputs; gasifier bed, filter char, getter material, and gas phase. Table 1. vi LIST OF TABLESComposition of alkali getter materials reported in the literature. 6 Table 2. Thermodynamic equilibrium prediction of phase distribut...

show abstract

Co‐Firing Biomass with Coal in Fluidized Bed Combustion Systems

Selçuk

Gogebakan

2010

Handbook of Combustion

View full text Add to dashboard Cite

This chapter overviews direct co‐firing applications of agricultural and forestry residues with coal in fluidized bed combustion (FBC) systems, which is the most promising technology due to its fuel flexibility and high efficiency. Similarities and differences in characteristics of biomass and coal are summarized. Issues on operational problems and their possible solutions in FBC systems firing biomass only are identified. Among the available solutions to these problems, co‐firing biomass with coal is the most effective and simple option. Experiences obtained from several biomass/coal blends in FBC systems, ranging from laboratory rigs to large‐scale utility boilers, are presented to emphasize the impact of co‐firing on combustion efficiency, emissions and ash‐related operational problems.

show abstract

The kinetics and mechanism of alkali removal from flue gases by solid sorbents

Cited by 114 publications

References 10 publications

Ash Deposition in Biomass Combustion or Co-Firing for Power/Heat Generation

Ash Deposition in Biomass Combustion or Co-Firing for Power/Heat Generation

Control of alkali species in gasification systems: Final report

Co‐Firing Biomass with Coal in Fluidized Bed Combustion Systems

Contact Info

Product

Resources

About