Combustion of Biomass in Fluidized Beds: Problems and Some Solutions Based on Danish Experiences

2003 ◽  
Author(s):  
Weigang Lin ◽  
Anker D. Jensen ◽  
Jan E. Johnsson ◽  
Kim Dam-Johansen
Keyword(s):  
Gas Phase ◽  
Fluidized Beds ◽  
Early Stage ◽  
Full Scale ◽  
Boiler Load ◽  
High K ◽  
Fundamental Understanding ◽  
Annual Biomass ◽  
Operation Parameters ◽  
Boiler Design

This paper summarizes the major problems in firing and co-firing the annual biomass, such as straw, in both lab-scale and full-scale fluidized bed combustors. Two types of problems were studied: operational problems, such as agglomeration, deposition and corrosion; and emission problems, e.g. emissions of NO and SO2. Measurements of deposition and corrosion rate on the heat transfer surfaces, as well as gas phase alkali metal concentrations, were performed in full scale CFB boilers (an 80 MWth and a 20 MWth plant), which have been co-firing coal with straw and other biomass. Severe corrosion and deposition were observed in the superheater located in the loop-seal of the 80 MWth boiler. The boiler load variation has impact on the operation parameters. When the fraction of biomass with a high K-content (>1 wt. %) was higher than 60% on a thermal basis, the boiler suffered from severe agglomeration problems. Lab-scale experiments were carried out for the fundamental understanding of phenomena found in full-scale boilers and for testing possible solutions to the problems. The results showed a strong tendency of agglomeration in fluidized beds during combustion of straw, which normally have a high content of potassium and chlorine. The results indicate that the operational problems may be minimized by a combination of additives, improved boiler design, split of combustion air and detection of agglomeration at an early stage.

Direct Nucleation of Crystalline SiGe on Substrates by Reactive Thermal CVD with Si2H6 and GeF4

1997 ◽  
Vol 467 ◽  
Author(s):  
Fumio Yoshizawa ◽  
Kunihiro Shiota ◽  
Daisuke Inoue ◽  
Jun-ichi Hanna
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Film Growth ◽  
Early Stage ◽  
Gaseous Mixture ◽  
The Other ◽  
Thermal Cvd ◽  
Initial Deposition

ABSTRACTPolycrystalline SiGe (poly-SiGe) film growth by reactive thermal CVD with a gaseous mixture of Si2H6 and GeF4 was investigated on various substrates such as Al,Cr, Pt, Si, ITO, ZnO and thermally grown SiO2.In Ge-rich film growth, SEM observation in the early stage of the film growth revealed that direct nucleation of crystallites took place on the substrates. The nucleation was governed by two different mechanisms: one was a heterogeneous nucleation on the surface and the other was a homogeneous nucleation in the gas phase. In the former case, the selective nucleation was observed at temperatures lower than 400°C on metal substrates and Si, where the activation of adsorbed GeF4 on the surface played a major role for the nuclei formation, leading to the selective film growth.On the other hand, the direct nucleation did not always take place in Si-rich film growth irrespective of the substrates and depended on the growth rate. In a growth rate of 3.6nm/min, the high crystallinity of poly-Si0.95Ge0.05in a 220nm-thick film was achieved at 450°C due to the no initial deposition of amorphous tissue on SiO2 substrates.

scholarly journals Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

2019 ◽  
Author(s):  
Ariadni Georgatou ◽  
Massimo Chiaradia
Keyword(s):  
Solid Solution ◽  
Early Stage ◽  
Volcanic Field ◽  
Geodynamic Setting ◽  
Calc Alkaline ◽  
Western Turkey ◽  
Epithermal Deposits ◽  
High K ◽  
Wide Range ◽  
Magmatic Sulphides

Abstract. We investigate in both mineralised and barren systems the occurrence and chemistry of magmatic sulphides and their chalcophile metal cargo behaviour during evolution of compositionally different magmas in diverse geodynamic settings. The investigated areas are: (a) the Miocene Konya magmatic province (hosting the Doganbey Cu-Mo and Inlice Au-epithermal deposits) (Post-Subduction) and (b) the Miocene Usak basin (Elmadag, Itecektepe and Beydagi volcanoes, the latter associated with the Kisladag Au porphyry) in Western Turkey (Post-Subduction). For comparison we also investigate (c) the barren Plio-Quaternary Kula volcanic field, west of Usak (Intraplate) and finally we discuss and compare all the above areas with the already studied (d) Quaternary Ecuadorian volcanic arc (host to the Miocene Llurimagua Cu-Mo and Cascabel Cu-Au porphyry deposits) (Subduction). The volcanism of the studied areas displays a wide range of SiO2 spanning from basalts to andesites/dacites and from high K-calc-alkaline to shoshonitic series. Multiphase magmatic sulphides occur in different amounts in all investigated areas and based on textural and compositional differences, they can be classified in different types, which crystallised at different times (early versus late saturation). A decrease in the sulphide Ni/Cu (proxy for mss-monosulphide solid solution/iss-intermediate solid solution) ratio is noted with magmatic evolution. Starting with an early stage, saturating Ni-richer/Cu-poorer sulphides hosted by early crystallising minerals e.g. olivine/pyroxene, leading up to a later stage, producing Cu-richer sulphides hosted by magnetite. The most common sulphide type resulting from an early saturating stage is composed of a Cu-poor/Ni-rich (pyrrhotite/mss) and one/two Cu-rich (cubanite, chalcopyrite/iss) phases making up 84 and 16 area % of the sulphide, respectively. Our results suggest that independently of the magma composition, geodynamic setting and whether or not the system has generated an ore deposit on the surface, sulphide saturation occurred in variable degrees in all studied areas and magmatic systems and is characterised by a similar initial metal content of the magmas. However not all studied areas present all sulphide types and the sulphide composition is dependent on the nature of the host mineral. In particular sulphides, resulting from the late stage, consisting of Cu-rich phases (chalcopyrite ,bornite, digenite/iss) are hosted exclusively by magnetite and are found only in magmatic provinces associated with porphyry Cu (Konya and Ecuador) and porphyry Au (Beydagi) deposits.

Thermochemistry of Elementary Actinide Sulfide Molecules: A Gas-Phase Study of Curium Sulfide

2010 ◽  
Vol 1264 ◽  
Author(s):  
Cláudia C. L. Pereira ◽  
Joaquim Marçalo ◽  
John K. Gibson
Keyword(s):  
Gas Phase ◽  
Bond Dissociation Energies ◽  
Gas Phase Reactions ◽  
General Applicability ◽  
Molecular Systems ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Phase Study ◽  
Fundamental Understanding ◽  
Actinide Ions

AbstractExperiments to explore the reactivity and thermochemistry of elementary transuranium sulfide molecules have been initiated to expand the basis for a fundamental understanding of actinide bonding, and to enable the development of advanced theoretical methodologies which will be of general applicability to more complex molecular systems. Bimolecular gas-phase reactions between transuranium actinide ions and neutral reagents are employed to obtain thermochemical information. The initial actinide sulfide studies have focused on obtaining the 298 K bond dissociation energy for the CmS+ ion, D[Cm+-S] = 475±37 kJ mol-1; from this result and an estimate of IE[CmS] ≈ IE[CmO] + 0.5 eV, we obtain D[Cm-S] = 563±64 kJ mol-1. The bond dissociation energies, D[Cm+-S] and D[Cm-S] are approximately 200 kJ mol-1 and 150 kJ mol-1 lower than for the corresponding oxides, CmO+ and CmO. The nature of the bonding in the CmS+ ion appears to be generally similar to that in other oxophilic metal sulfides. Comparisons with previous bond dissociation energies reported for ThS and US may suggest a difference in the An-S bonds for these early actinide sulfides as compared with CmS.

Evaluation of Wearing Pipe for Subsea Mining With Large Particles in Slurry Transportation

2015 ◽  
Author(s):  
Satoru Takano ◽  
Masao Ono ◽  
Sotaro Masanobu
Keyword(s):  
Full Scale ◽  
Small Scale ◽  
Pipe Material ◽  
Test Results ◽  
Material Loss ◽  
Large Particles ◽  
Fundamental Understanding ◽  
Maximum Particle ◽  
Scale Test ◽  
Set Up

For a fundamental understanding of pipe wear under hydraulic transportation of deep-sea mining, a small scale test is conducted because there are many restrictions in conducting a full scale test. The small scale test apparatus are set up using the pipes of about 80mm in diameter and the rocks of which maximum particle diameters are about 20mm are used. In the test, the pipe materials and the pipe inclination are changed to evaluate the differential of the amount of pipe material loss. Furthermore, the amount of the pipe material loss in full scale is estimated based on the small scale test results.

Biofiltration of dichlorobenzenes

2001 ◽  
Vol 44 (9) ◽  
pp. 287-293 ◽  
Author(s):  
F. Roberge ◽  
M.J. Gravel ◽  
L. Deschênes ◽  
C. Guy ◽  
R. Samson
Keyword(s):  
Gas Phase ◽  
Contaminated Soil ◽  
Cooling System ◽  
Ambient Air ◽  
Animal Manure ◽  
Full Scale ◽  
Peat Moss ◽  
Aerobic Treatment ◽  
Load Variations ◽  
System A

The use of air biofiltration for the degradation of dichlorobenzenes (1,2-DCB and 1,4-DCB) was studied at a refinery site. At this plant, 93 m3/h of contaminated groundwater, used in a cooling system and containing a maximum of 2 ppm of dichlorobenzenes, had to be treated. Stripping of the DCBs followed by biofiltration was selected as the most suitable technology to avoid volatilization in ambient air as expected with a wastewater aerobic treatment system. A stripper of 15 m height and 1.27 m diameter was designed as a first step treatment to volatilize DCBs with 3400 m3/h of air. Two full-scale biofilters of 70 m3 each were built and filled with 45 m3 of filtering media for the adsorption and biodegradation of the DCBs in the gas-phase. Filtering media was composed mainly of peat moss, with animal manure, wood chips and DCBs contaminated soil. Air to be treated was also contaminated with naphthalene. Laboratory tests showed an effective microbial activity in the contaminated soil and in the filtering media for DCBs degradation. Degradation of naphthalene induced slower degradation of DCBs. Full-scale operation was studied during four months. Water flow and DCBs content in the water entering the stripper were lower than expected with only 57 m3/h and a maximum concentration of only 240 ppb. Effective desorption was obtained in the stripper in the full-scale operation (more than 99% removal). Full-scale biofilters maintained a DCB concentration of less than 1 ppmv in the air outlet, but removal efficiency varied between 0 and 79% because of the low DCB inlet concentrations, load variations and sporadic naphthalene presence.

Transformation and Release to the Gas Phase of Cl, K, and S during Combustion of Annual Biomass

2004 ◽  
Vol 18 (5) ◽  
pp. 1385-1399 ◽  
Author(s):  
Jacob N. Knudsen ◽  
Peter A. Jensen ◽  
Kim Dam-Johansen
Keyword(s):  
Gas Phase ◽  
Annual Biomass

scholarly journals Identification of a prismatic P3N3 molecule formed from electron irradiated phosphine-nitrogen ices

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cheng Zhu ◽  
André K. Eckhardt ◽  
Sankhabrata Chandra ◽  
Andrew M. Turner ◽  
Peter R. Schreiner ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Chemical Bonding ◽  
Time Of Flight ◽  
Synthetic Chemistry ◽  
Energetic Electrons ◽  
Flight Mass Spectrometry ◽  
Cage Molecules ◽  
Fundamental Understanding ◽  
Photochemical Processing

AbstractPolyhedral nitrogen containing molecules such as prismatic P3N3 - a hitherto elusive isovalent species of prismane (C6H6) - have attracted particular attention from the theoretical, physical, and synthetic chemistry communities. Here we report on the preparation of prismatic P3N3 [1,2,3-triaza-4,5,6-triphosphatetracyclo[2.2.0.02,6.03,5]hexane] by exposing phosphine (PH3) and nitrogen (N2) ice mixtures to energetic electrons. Prismatic P3N3 was detected in the gas phase and discriminated from its isomers utilizing isomer selective, tunable soft photoionization reflectron time-of-flight mass spectrometry during sublimation of the ices along with an isomer-selective photochemical processing converting prismatic P3N3 to 1,2,4-triaza-3,5,6-triphosphabicyclo[2.2.0]hexa-2,5-diene (P3N3). In prismatic P3N3, the P–P, P–N, and N–N bonds are lengthened compared to those in, e.g., diphosphine (P2H4), di-anthracene stabilized phosphorus mononitride (PN), and hydrazine (N2H4), by typically 0.03–0.10 Å.  These findings advance our fundamental understanding of the chemical bonding of poly-nitrogen and poly-phosphorus systems and reveal a versatile pathway to produce exotic, ring-strained cage molecules.

Application of ScaleGuard® at reverse osmosis and nanofiltration installations

2003 ◽  
Vol 3 (5-6) ◽  
pp. 133-138 ◽  
Author(s):  
S.G.J. Heijman ◽  
H. Folmer ◽  
F. Donker ◽  
B.M. Rietman ◽  
J.C. Schippers
Keyword(s):  
Mass Transfer ◽  
Surface Water ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Reverse Osmosis ◽  
Early Stage ◽  
Inorganic Compounds ◽  
Full Scale ◽  
Reverse Osmosis Plant ◽  
On Line

ScaleGuard® is a continuous on-line monitor that detects scaling at an early stage when fed with the concentrate of a pilot- or full-scale plant. Scaling is observed in the ScaleGuard before it occurs in the full-scale installation. The ScaleGuard is used to optimize the recovery of two full-scale plants: one reverse osmosis plant treating pretreated surface water and one nanofiltration plant treating anaerobic groundwater. Based on the results of the ScaleGuard the conversion of both the reverse osmosis plant and the nanofiltration plant has been increased from 80% to 82%. The interpretation of the results of the ScaleGuard which was connected with the reverse osmosis plant was not unambiguous. This was due to the mass transfer coefficient decline in the ScaleGuard which could not be attributed to scaling. Results in the nanofiltration plant did not give room for any doubt. In addition, safe supersaturation ratios were derived from experience in pilot- and full-scale plants using anti-scalants for seven sparingly soluble inorganic compounds.

Modeling Air Jet Penetration Into Gas-Particle Suspension Cross Flow

2003 ◽  
Author(s):  
Ville Tossavainen ◽  
Reijo Karvinen ◽  
Matti Ylitalo
Keyword(s):  
Numerical Modeling ◽  
Cross Flow ◽  
Full Scale ◽  
Design Tool ◽  
Particle Suspension ◽  
Jet Mixing ◽  
Pilot Unit ◽  
Air Jet ◽  
Jet Penetration ◽  
Boiler Design

In the paper, numerical modeling of air jet mixing in gas–particle suspension is discussed. The theory on which the modeling is based on is presented and to get a reliable opinion of its capability as a boiler design tool, the results are compared with those obtained experimentally in a cold pilot boiler. Based on the research on the pilot unit, the modeling seems to give reliable results. The modeling has also been applied to a full-scale boiler.

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