Release of Chlorine and Its Retention in Ash During Co-Combustion of Biomass and Coal in a Pulverized Fuel Combustor

Wei, Xiaolin; Lopez, Christian; Puttkamer, Thore von; Schnell, Uwe; Unterberger, S.; Hein, K. R. G.

doi:10.1615/interjenercleanenv.v5.i1.10

Cited by 2 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, at low temperatures, the effect of the water vapor was still important. The present reaction order of 0.12 at high temperatures agreed with the 0.15 value reported by Sengeløv et al 37 Based on the preceding experimental data, the sulfation rate as a function of temperature (523−1023 K) and reactant concentrations was determined as follows: 31 Boonsongsup et al, 33 Wei et al, 43 and Adams et al, 44 (R13)…”

Section: Energy and Fuelssupporting

confidence: 88%

See 1 more Smart Citation

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K

Wang

et al. 2014

Energy Fuels

View full text Add to dashboard Cite

Sulfation of condensed alkali chloride significantly affects deposition and corrosion in heat transfer surfaces during biomass combustion. This study investigates the heterogeneous sulfation of condensed potassium chloride (KCl) in a fixed-bed reactor at 523−1023 K with levels of 0.1−2% sulfur oxide (SO 2 ), 2.5−10% oxygen (O 2 ), and 5−15% water vapor. The sulfation rate is determined by measuring the sulfur content in solid residues. No other potassium species are found, and potassium sulfate (K 2 SO 4 ) is the only sulfation product. The KCl sulfation within the temperature range of 523−1023 K was divided into three stages: (1) slow sulfation rate increase below 723 K, (2) slight decline at 723−773 K, and (3) rapid increase over 823 K. The sulfation mechanism transformation occurs between 723 and 823 K. This change in the reaction mechanism is further proven by investigating the effects of SO 2 and O 2 reactants and water vapor at 723 and 923 K. The KCl−K 2 SO 4 mixture forms a eutectic to change the reaction mode at high temperatures, thereby explaining the phenomenon, which is further confirmed by the results of scanning electron microscopy. The sulfation reaction rate of condensed KCl is described by the following expressions: dX/dt = 5.3 × 10 −3 exp(−2120/T)(1 − X) 2/3 (C O 2 ) 0.27 (C SO 2 ) 0.27 (C H 2 O ) 0.42 at 523−723 K and dX/dt = 1.20 × 10 4 exp(−14180/T)(1 − X) 2/3 (C O 2 ) 0.92 (C SO 2 ) 0.39 (C H 2 O ) 0.12 at 823−1023 K.

show abstract

Section: Energy and Fuelssupporting

confidence: 88%

“…A KCl sulfation mechanism in the presence of SO 2 , H 2 O, and O 2 , which is similar to that proposed by Henriksson and Warnqvist, Boonsongsup et al, Wei et al, and Adams et al, is presented as follows: …”

Section: Resultssupporting

confidence: 60%

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K

Wang

et al. 2014

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…Compared with coal, straw has a high amount of potassium and chlorine, as straw typically has a content of potassium (0.5−1.3%), chlorine (0.2−0.7%), and silicon (0.3−1.0%) on dry straw base as well as minor amounts of Ca, Mg, Al, Na, Fe, S, and P, etc . During straw combustion or pyrolysis, significant amounts of alkali metals and chlorine are released into the gas phase, such as KCl, KOH, and HCl. − Equilibrium calculations indicated that the chlorine distribution in the gas species greatly vary with an increasing cofired straw fraction . When the gas is cooled later in the boiler, potassium condenses mainly as sulfate and chloride, and ash deposits form on the heat transfer surfaces. ,− The lower melting point for some potassium species (e.g., KCl melts at 1044 K) puts a high risk of formation of hard deposits on furnace walls and convection tubes.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…A few results have been reported about the effect of Ca and Mg on the behavior of chlorine and alkali metals. , It was found that, during brown coal combustion, due to the lower content of aluminum, Al more likely combines with Ca and Mg, so only a low content of potassium aluminosilicate is formed. Thus a high amount of gaseous alkali chloride forms, which may be captured by the fly ash or deposits as KCl (s) and NaCl (s) during the gas cooling . On the other hand, the influence of limestone addition on the retention of chlorine has been reported and most studies have focused on the impact of limestone on the dechlorination and desulfurization efficiency. − Experimental results showed that the concentration of chlorine in fly ash tended to increase, and the HCl concentration was found to decrease with increasing limestone dosage .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of Chlorine−Alkali−Mineral Interactions during Co-Combustion of Coal and Straw

et al. 2002

View full text Add to dashboard Cite

During co-combustion of coal and straw, ash deposition and pollutants (HCl, aerosols, etc.) formation is significantly influenced by the behavior of chlorine and alkali metals. On the bases of measurement data, the effect of inherent minerals in blended fuels on the release and retention of chlorine and alkali metals is investigated through the equilibrium analysis tool FACT-Win. Si, Al, Ca, Mg, and S may greatly affect the behavior of Cl, K, and Na, where the other minor elements, such as Fe, Ti, and Mn have not much influence. According to measurement data, very low amounts of chlorine and sulfur are retained in bottom, air preheater, and cyclone ash in a pulverized fuel combustor. But in filter ash, the chlorine and sulfur contents are relatively high and the ratio (K + Na)/(Cl + 2S) is close to 1. According to equilibrium calculations, in hard coal co-combustion with less than 50% straw, most of the potassium is combined with aluminosilicates to form KAlSi2O6(s,s2), etc., which can prevent ash depositing on the furnace surface. Besides the formation of NaAlSi3O8(s2), some sodium is released as NaCl(g) and NaOH(g). In brown coal co-combustion, most of the potassium is released as KCl(g), KOH(g), and K2SO4(g) because aluminum can be combined in the Ca and Mg compounds, such as Ca3Al2O6(s), CaAl2O4(s), and MgAl2O4(s). Increasing the straw fraction reduces KAlSi2O6(s2) and increases K2Si4O9(liq). Most of the sodium is released as NaOH(g), NaCl(g) and Na2SO4(g). Na2SO4(liq) is formed between 1200 and 1400 K for conditions with less than 50% straw. In pure straw combustion, KCl(g) and K2Si4O9(liq) are the main species. During the gas cooling, KCl(g) and KOH(g) may react with SO2(g) and H2O(g) to form K2SO4(g) and then a lot of aerosols are formed. Finally, the possible reactions involving chlorine and alkali metals are analyzed.

show abstract

Release of Chlorine and Its Retention in Ash During Co-Combustion of Biomass and Coal in a Pulverized Fuel Combustor

Cited by 2 publications

References 0 publications

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K

Assessment of Chlorine−Alkali−Mineral Interactions during Co-Combustion of Coal and Straw

Contact Info

Product

Resources

About

Release of Chlorine and Its Retention in Ash During Co-Combustion of Biomass and Coal in a Pulverized Fuel Combustor

Cited by 2 publications

References 0 publications

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO2/O2/H2O at 523–1023 K

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO2/O2/H2O at 523–1023 K

Assessment of Chlorine−Alkali−Mineral Interactions during Co-Combustion of Coal and Straw

Contact Info

Product

Resources

About

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K