02365nas a2200169 4500008004100000022001400041245008500055210006900140260007100209300001400280490000700294520172000301100002702021700001602048700001902064856011202083 2006 eng d a0888-588500aModeling of rotary cement kilns: applications to reduction in energy consumption0 aModeling of rotary cement kilns applications to reduction in ene a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR a2315-23300 v453 a

Rotary cement kilns are used for converting calcineous raw meal into cement clinkers. In this paper, we discuss and evaluate possible ways of reducing energy consumption in rotary cement kilns. A comprehensive one-dimensional model was developed to simulate complex processes occurring in rotary cement Kilns. A modeling strategy comprising three submodels. viz. a model for simulating the variation of bed height in the kiln, a model for simulating reactions and heat transfer in the bed region, and a model for simulating coal combustion and heat transfer in the freeboard region, was developed. Melting and formation of coating within the kiln were accounted for. Combustion of coal in the freeboard region was modeled by accounting for devolatilization, finite-rate gas-phase combustion, and char reaction. The simulated results were validated with the available data from three industrial kilns. The model was then used to understand the influence of various design and operating parameters on kiln performance. Several ways of reducing energy consumption in kilns were then computationally investigated. The model was also used to propose and to evaluate a practical solution of using a secondary shell to reduce energy consumption in rotary cement kilns. Simulation results indicate that varying kiln operating variables, viz. solid flow rate or RPM, can result only in small changes in kiln energetics. Use of a secondary shell over the kiln and energy recovery by passing air through the annular gap between the two appears to be a promising way to achieve significant energy savings. The developed model and the presented results will be useful for enhancing the performance of rotary cement kilns.

1 aMujumdar, Kaustubh, S.1 aArora, Amit1 aRanade, V., V. uhttps://library.ncl.res.in/content/modeling-rotary-cement-kilns-applications-reduction-energy-consumption-002740nas a2200217 4500008004100000022001400041245015100055210006900206260007100275300001400346490000800360520189600368100001802264700001602282700001402298700001602312700002202328700002602350700001802376856012802394 2009 eng d a1520-610600aEffects for the incorporation of five-atom thioacetamido nucleic acid (TANA) backbone on hybridization thermodynamics and kinetics of DNA duplexes0 aEffects for the incorporation of fiveatom thioacetamido nucleic  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR a2944-29510 v1133 a

Thermodynamic studies of nucleic acids serve not only to widen our understanding on the nature and strength of forces that stabilize nucleic acids in a myriad of structural states they assume but also to facilitate the development of databases that could be used to predict the stability and selectivity of probe/primer-sets required in a broad range of nucleic acid-based diagnostic and therapeutic protocols. In the current study, we investigated the effect of a novel, backbone-modified ``thioacetamido linkage'' (TANA) on thermodynamics of hybridization, binding kinetics, and conformation of a DNA duplex. The modification comprises of an extended five-atom amide (N3'-CO-CH(2)-S-CH(2)) linker, as opposed to four-atom phosphodiester linker backbone present in DNA. One to three TANA-substitutions have been introduced in the linker backbone of two thymidine residues of one of the strand of the DNA duplex. Using spectroscopic and calorimetric techniques, we observed that TANA destabilizes the DNA helix by lowering the favorable enthalpy parameter of duplex formation. TANA center dot DNA duplexes were found to adopt a conformation toward an A-type duplex as shown by circular dichroism spectroscopy studies. Analysis of differential scanning calorimetry data indicated a nonzero heat capacity change, Delta C(p), accompanying the duplex formation. The average Delta C(p) change per duplex was found to be 832.5 cal mol(-1) K(-1), giving an average base-pair change of 59.5 cal (mol of base pairs)(-1) K(-1). Hybridization kinetic measurements using surface plasmon resonance indicated a decrease in binding affinity parameter (K(A)) that originates from higher dissociation rate constants (k(d)). Furthermore, optical melting studies showed that increasing the number of modifications results in a modest change in the number of counterions taken up during duplex formation.

1 aKaur, Harleen1 aArora, Amit1 aGogoi, K.1 aSolanke, P.1 aGunjal, Anita, D.1 aKumar, Vaijayanti, A.1 aMaiti, Souvik uhttps://library.ncl.res.in/content/effects-incorporation-five-atom-thioacetamido-nucleic-acid-tana-backbone-hybridization-001991nas a2200229 4500008004100000022001400041245009600055210006900151260009000220300001000310490000600320520113200326100001601458700003101474700001901505700002901524700002301553700002101576700002201597700001801619856012401637 2016 eng d a2045-232200aBiosurfactant as a promoter of methane hydrate formation: thermodynamic and kinetic studies0 aBiosurfactant as a promoter of methane hydrate formation thermod aMACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLANDbNATURE PUBLISHING GROUPcFEB a208930 v63 a

Natural gas hydrates (NGHs) are solid non-stoichiometric compounds often regarded as a next generation energy source. Successful commercialization of NGH is curtailed by lack of efficient and safe technology for generation, dissociation, storage and transportation. The present work studied the influence of environment compatible biosurfactant on gas hydrate formation. Biosurfactant was produced by Pseudomonas aeruginosa strain A11 and was characterized as rhamnolipids. Purified rhamnolipids reduced the surface tension of water from 72 mN/m to 36 mN/m with Critical Micelle Concentration (CMC) of 70 mg/l. Use of 1000 ppm rhamnolipids solution in C type silica gel bed system increased methane hydrate formation rate by 42.97% and reduced the induction time of hydrate formation by 22.63% as compared to water saturated C type silica gel. Presence of rhamnolipids also shifted methane hydrate formation temperature to higher values relative to the system without biosurfactant. Results from thermodynamic and kinetic studies suggest that rhamnolipids can be applied as environment friendly methane hydrate promoter.

1 aArora, Amit1 aCameotra, Swaranjit, Singh1 aKumar, Rajnish1 aBalomajumder, Chandrajit1 aSingh, Anil, Kumar1 aSanthakumari, B.1 aKumar, Pushpendra1 aLaik, Sukumar uhttps://library.ncl.res.in/content/biosurfactant-promoter-methane-hydrate-formation-thermodynamic-and-kinetic-studies-101684nas a2200265 4500008004100000022001400041245011500055210006900170260009900239300001400338490000700352520069900359653001901058653002001077653002201097653002101119653001601140653002301156100001601179700001901195700002601214700002201240700002901262856012701291 2016 eng d a0261-306900aEffect of different fixed bed media on the performance of sodium dodecyl sulfate for hydrate based CO2 capture0 aEffect of different fixed bed media on the performance of sodium aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcJAN a1186-11910 v903 a

Sodium Dodecyl Sulfate (SDS) is used as a kinetic promoter in gas hydrate formation. In this work, the performance of SDS for carbon dioxide gas hydrate formation in two different fixed bed media: silica sand and zeolite (5A and 13X) has been evaluated. The concentration of SDS was fixed at 0.5 wt%. The experiments were carried out in batch mode with the initial pressure fixed at 3.0 MPa, and the temperature kept constant at 274.65 K. The results showed that hydrate of carbon dioxide with fixed bed of silica sand was significantly promoted by the addition of SDS as compared to the other fixed bed medium used in this study: zeolite 13X. (c) 2015 Elsevier Ltd. All rights reserved.

10aCarbon dioxide10aFixed bed media10aHydrate formation10aKinetic promoter10aSilica sand10aZeolite 5A and 13X1 aArora, Amit1 aKumar, Asheesh1 aBhattacharjee, Gaurav1 aKumar, Pushpendra1 aBalomajumder, Chandrajit uhttps://library.ncl.res.in/content/effect-different-fixed-bed-media-performance-sodium-dodecyl-sulfate-hydrate-based-co2-002325nas a2200289 4500008004100000020004100041245008300082210006900165260012400234520125600358653001901614653002001633653003001653653002701683653001601710100001601726700003101742700001901773700002301792700002201815700002901837700001801866700001301884700001501897700001401912856010901926 2016 eng d a978-81-322-2773-1; 978-81-322-2771-700aRole of Rhamnolipid: A biosurfactant in methane gas hydrate formation kinetics0 aRole of Rhamnolipid A biosurfactant in methane gas hydrate forma a7th Floor, Vijaya Building, 17, Barakhamba Rd, New Delhi, 110 001, IndiabSardar Swaran Singh Natl Inst Bio-EnergycFEB3 a

Naturally occurring methane gas hydrate is a vast source of methane gas which is trapped in crystalline ice-like structure present in permafrost regions and under the sea in outer continental margins. It is purposed that total amount of carbon in the form of methane hydrates is almost twice the carbon content in all the fossil fuel reserves put together, and hence these are supposed to be the future potential energy resource. This paper investigates the laboratory investigations on effect of a biosurfactant rhamnolipid on methane hydrate formation kinetics. Rhamnolipid was produced by Pseudomonas aeruginosa strain A11. The presence of P. aeruginosa has been reported in Gulf of Mexico gas hydrate samples. Biosurfactant reduced the surface tension of water from 72 to 36 mN/m with CMC of 70 mg/L. The biosurfactant dose is studied at two different concentrations in the solution at 100 and 1000 ppm. Kinetic of hydrate formation and growth is compared at 0, 100, and 1000 ppm of rhamnolipid showing that rhamnolipid acts as a hydrate promoter at these concentrations. Thus, small dosages of rhamnolipids produced by P. aeruginosa strain A11 must clearly affect the gas hydrate formation kinetics in natural sites (as in Gulf of Mexico).

10aInduction time10amethane hydrate10aPotential energy resource10aPseudomonas aeruginosa10aRhamnolipid1 aArora, Amit1 aCameotra, Swaranjit, Singh1 aKumar, Rajnish1 aSingh, Anil, Kumar1 aKumar, Pushpendra1 aBalomajumder, Chandrajit1 aLaik, Sukumar1 aKumar, S1 aKhanal, SK1 aYadav, YK uhttps://library.ncl.res.in/content/role-rhamnolipid-biosurfactant-methane-gas-hydrate-formation-kinetics02177nas a2200301 4500008004100000022001400041245012500055210006900180260000900249300001100258490000800269520115900277653004601436653002701482653002401509653002201533653002001555653001601575653001301591653001301604653001501617100001601632700001901648700002601667700002901693700002201722856013101744 2021 eng d a0195-073800aHydrate-based carbon capture process: assessment of various packed bed systems for boosted kinetics of hydrate formation0 aHydratebased carbon capture process assessment of various packed cMAR  a0330050 v1433 a

The case for developing novel technologies for carbon dioxide (CO2) capture is fast gaining traction owing to increasing levels of anthropogenic CO2 being emitted into the atmosphere. Here, we have studied the hydrate-based carbon dioxide capture and separation process from a fundamental viewpoint by exploring the use of various packed bed media to enhance the kinetics of hydrate formation using pure CO2 as the hydrate former. We established the fixed bed reactor (FBR) configuration as a superior option over the commonly used stirred tank reactor (STR) setups typically used for hydrate formation studies by showing enhanced hydrate formation kinetics using the former. For the various packing material studied, we have observed silica gel with 100 nm pore size to return the best kinetic performance, corresponding to a water to hydrate conversion of 28 mol% for 3 h of hydrate growth. The fundamental results obtained in the present study set up a solid foundation for follow-up works with a more applied perspective and should be of interest to researchers working in the carbon dioxide capture and storage and gas hydrate fields alike.

10aair emissions from fossil fuel combustion10aCarbon dioxide capture10acombustion of waste10aFixed bed reactor10afuel combustion10aGas hydrate10ahydrates10akinetics10aSilica gel1 aArora, Amit1 aKumar, Asheesh1 aBhattacharjee, Gaurav1 aBalomajumder, Chandrajit1 aKumar, Pushpendra uhttps://library.ncl.res.in/content/hydrate-based-carbon-capture-process-assessment-various-packed-bed-systems-boosted-kinetics02364nas a2200289 4500008004100000022001400041245012000055210006900175260000800244300000600252490000700258520141400265653001801679653001101697653001601708653001901724653002101743100001601764700003101780700002901811700001901840700002301859700002101882700002201903700001801925856013101943 2021 eng d a0025-323500aRhamonolipids produced by Pseudomonas aeruginosa promotes methane hydrates formation in fixed bed silica gel medium0 aRhamonolipids produced by Pseudomonas aeruginosa promotes methan cMAR a50 v423 a

Natural gas hydrates are seen as an alternative future energy source. They have also been valued for their carbon dioxide capturing capability, gas separation, desalination, natural gas storage and transportation. Developing economical and viable gas hydrate based technology is one of the most promising research areas of present decade. Successful commercialization of gas hydrate based technology is often curtailed due to slow formation rate. The present study evaluates biosurfactant as a kinetic promoter of methane hydrates formation in a fixed bed C type silica gel medium. Biosurfactant was produced by growing Pseudomonas aeruginosa strain A11 in glycerol supplemented mineral salt medium. Biosurfactant characterization with FTIR, NMR and MALDI-TOF spectroscopy reveled it to be a glycolipids type biosurfactant namely rhamnolipids. Saturating C type silica gel with of 100 ppm rhamnolipids solution enhanced the rate of methane hydrates formation by reducing the induction time. Mole of methane consumed and percentage of water to hydrate conversion was observed to be more in 1000 ppm rhamnolipids saturated C type silica gel as compared to quiescent water system and water saturated silica gel system. Overall results suggest that rhamonolipids produced by strain A11 in combination with silica gel can be utilized as environmentally safe kinetic promoter for methane hydrate formation.

10aBiosurfactant10aEnergy10aGlycolipids10aInduction time10aKinetic promoter1 aArora, Amit1 aCameotra, Swaranjit, Singh1 aBalomajumder, Chandrajit1 aKumar, Rajnish1 aSingh, Anil, Kumar1 aSanthakumari, B.1 aKumar, Pushpendra1 aLaik, Sukumar uhttps://library.ncl.res.in/content/rhamonolipids-produced-pseudomonas-aeruginosa-promotes-methane-hydrates-formation-fixed-bed