The influence of fuel characteristics in the formation of NO during combustion of methyl ester in oil-burner industrial boilers is presented in this paper. Under strictly controlled conditions of combustion, NO formation shows great susceptibility to biodiesel density, ignition delay, oxygen concentration, and adiabatic flame temperature. Results show that the adiabatic flame temperature affects NO formation more than the other variables, and the level of this pollutant exponentially increases with this ideal temperature for combustion. It is also shown that (a) NO formation during combustion of methyl esters linearly change with fuel density, (b) the increase of the combustion pressure reduces the effect of the density on NO formation, (c) the influence of the fuel cetane number on NO formation is intrinsic because it remains constant even when the quality of combustion is enhanced, and (d) in fuel-lean flames, oxygen of the biodiesel chemical structure increases the NO level.
8CO 2 is a common constituent of natural gas. Standards for its maximum concentration differ from about 9 2% for pipeline to 50 ppm for liquefaction. All natural gas constituents absorb CO 2 to some degree when 10 in the liquid phase, requiring multi-step natural gas treatment processes. The existence of a minimum-11 boiling temperature azeotrope between ethane and carbon dioxide particularly complicates CO 2 separation. 12Extractive distillation with higher molecular weight hydrocarbons as the solvent represents the most 13 competitive means for the separating CO 2 from ethane. The conventional separation method involves two 14 distillation columns in series and rather high amount of energy. 15This investigation proposes an efficient method for CO 2 -ethane separation that produces all products at high 16 purity with less capital and operating costs in comparison with the conventional system. The new operating 17 flowsheet includes three columns: a CO 2 recovery column, a solvent recovery column, and a concentrator 18 column. The proposed system requires 10 % less total annual cost (TAC) and 16% less energy compared 19 to the conventional system at the same purification. Additionally, unlike the conventional system, the 20 proposed design separates CO 2 in the form of a liquid product, which avoids the high amount of energy 21 required for the liquefaction. Thus, this technology provides a useful alternative towards the less expensive 22 CO 2 -ethane separation process. 23
The cryogenic carbon capture (CCC) process provides energy-and cost-efficient carbon capture and can be configured to provide an energy storage system using an open loop natural gas (NG) refrigeration system. This system stores energy during non-peak times by liquefying and storing natural gas to be used as a refrigerant. This investigation compares four different natural gas liquefaction processes simulated by Aspen HYSYS as incorporated as part of the CCC-ES process. In these processes, LNG vaporizes in the CCC process and the cold vapors return through the LNG heat exchangers exchanging sensible heat with the incoming flows. Aside from this difference, this investigation uses process designs similar to traditional LNG processes. The simulations meaningfully compare these alternative liquefaction options, eliminating differences in assumptions and process details inherent in comparing processes simulated by different authors or different codes. The comparisons include costs and energy performance with individually optimized processes, each operating at three operating conditions: energy storage, energy recovery, and balanced operation. Given similar quality turbomachinery, efficient heat exchangers in particular reduce energy input requirements and maximize energy savings and capital costs, including heat exchangers used to cool compressed gases.
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