scholarly journals Saturated Densities of Carbon Dioxide+Water Mixture at 304.1 K and Pressures to 10 MPa.

2000 ◽  
Vol 79 (2) ◽  
pp. 144-146 ◽  
Author(s):  
Rikio YAGINUMA ◽  
Yoshikazu SATO ◽  
Daisuke KODAMA ◽  
Hiroyuki TANAKA ◽  
Masahiro KATO
Keyword(s):  
Carbon Dioxide ◽  
Water Mixture

Conversion of Wet Ethanol to Syngas and Hydrogen

2008 ◽  
Author(s):  
Colin H. Smith ◽  
Daniel M. Leahey ◽  
Liane E. Miller ◽  
Janet L. Ellzey ◽  
Michael E. Webber
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Fuel Cells ◽  
Mole Fraction ◽  
Equivalence Ratio ◽  
Fossil Fuels ◽  
Water Mixture ◽  
Stoichiometric Mixture ◽  
Flammability Limits ◽  
Pure Ethanol

Because of converging concerns about global climate change and depletion of conventional petroleum resources, many nations are looking for ways to create transportation fuels that are not derived from fossil fuels. Biofuels and hydrogen (H2) have the potential to meet this goal. Biofuels are attractive because they can be domestically produced and consume carbon dioxide (CO2) during the feedstock growth cycle. Hydrogen is appealing because its use emits no CO2, and because hydrogen fuel cells can be very efficient. Today most hydrogen is derived from syngas, a mixture of hydrogen, carbon monoxide (CO) and carbon dioxide, which is produced through catalytic steam reforming of methane (CH4). Although effective, this process still produces CO2. Another method used to generate hydrogen is water electrolysis, but this process is extremely energy intensive. Thus, finding an energy-efficient approach to producing hydrogen from biofeedstock is appealing. Though there are many biofuels, ethanol (C2H5OH) is a popular choice for replacing fossil fuels. However, many have questioned its value as a renewable fuel since it requires a significant amount of energy to produce, especially from corn. Producing pure ethanol requires substantial energy for distillation and dehydration to yield an appropriate “dry” fuel for traditional combustion engines. Wet ethanol, or ethanol that has not been fully distilled and dehydrated, requires significantly less energy to create than pure ethanol. In this paper, we present a non-catalytic pathway to produce hydrogenrich syngas from wet ethanol. The presence of water in the reactant fuel can increase the hydrogen mole fraction and decrease the carbon monoxide mole fraction of the product syngas, both of which are desired effects. Also, because there are no catalytic surfaces, the problems of coking and poisoning that typically plague biomass-to-hydrogen reforming systems are eliminated. The non-catalytic fuel reforming process presented herein is termed filtration combustion. In this process, a fuel-rich mixture of air and fuel is reacted in an inert porous matrix to produce syngas. Some of the ethanol and air mixtures under study lie outside the conventional rich flammability limits. These mixtures react because high local temperatures are created as the reaction front propagates into a region where the solid matrix has been heated by exhaust gases. These high temperatures effectively broaden the flammability limits, allowing the mixture to react and break down the fuel into syngas. The conversion of pure and wet ethanol is a novel application of this process. Exhaust composition measurements were taken for a range of water fractions and equivalence ratios (Φ) and were compared to equilibrium values. The water fraction is the volumetric fraction of the inlet fuel and water mixture that is water. Equivalence ratio is the ratio of the fuel to oxidizer ratio of the reactant mixture to the fuel to oxidizer ratio of a stoichiometric mixture. A stoichiometric mixture is defined as a mixture with proportions of fuel and oxidizer that would react to produce only water and carbon dioxide. The stoichiometric mixture (Φ = 1) of ethanol and oxygen (O2) is 1 mole of ethanol for every 3 moles of oxygen: C2H5OH+3O2↔2CO2+3H2O Hydrogen mole fraction of the exhaust gas increased with increasing equivalence ratio and remained nearly constant for increasing water-in-fuel concentration. Carbon monoxide mole fraction was also measured because it may be used as a fuel for certain fuel cells while it can poison others [1]. Species and energy conversion efficiencies were calculated, showing that significant energy savings could be made by reforming wet ethanol rather than pure ethanol into syngas. Also, it is shown that the hydrogen to carbon monoxide ratio increases with addition of water to the fuel, making this method attractive for the production of pure hydrogen.

scholarly journals Spruce Bark—A Source of Polyphenolic Compounds: Optimizing the Operating Conditions of Supercritical Carbon Dioxide Extraction

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4049 ◽  
Author(s):  
Petra Strižincová ◽  
Aleš Ház ◽  
Zuzana Burčová ◽  
Jozef Feranc ◽  
František Kreps ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Total Phenolics ◽  
Extraction Process ◽  
Solvent Mixture ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Bark Extract ◽  
Water Mixture ◽  
Spruce Bark ◽  
Phenolics Content

The present study described the optimization of the extraction process with carbon dioxide in supercritical state for obtaining extractives, especially polyphenols from softwood bark, Norway spruce (Picea abies (L.) Karst.). Using a full 23 factorial design of experiments, the effect of varying the working parameters on the yield of extractives was studied for the following ranges: temperature 40–100 °C, pressure 1050–9000 psi (7.2–62 MPa), and concentration of EtOH/water co-solvent mixture 40–96.6%. In addition, total phenolics content and the antioxidant capacity of the spruce bark extract were determined. The optimum operating conditions for the yield of extractives were identified as 73 °C, 6465 psi (44.5 MPa), and 58% EtOH/water cosolvent concentration for a yield of 8.92%. The optimum conditions for achieving a total phenolics content of 13.89 mg gallic acid equivalent (GAE)/g dry extract were determined as: 45 °C, 1050 psi (7.2 MPa), and 96.6% EtOH/water mixture.

Practical Experience With a Mobile Methanol Synthesis Device

2014 ◽  
Author(s):  
Eric R. Morgan ◽  
Tom Acker
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Methanol Synthesis ◽  
Low Pressure ◽  
Practical Experience ◽  
Gaseous Hydrogen ◽  
Water Mixture ◽  
Pressure Side ◽  
Northern Arizona ◽  
Northern Arizona University

Northern Arizona University has developed a methanol synthesis unit that directly converts carbon dioxide and hydrogen into methanol and water. The methanol synthesis unit consists of: a high pressure side that includes a compressor, a reactor, and a throttling valve; and a low pressure side that includes a knockout drum, and a mixer where fresh gas enters the system. Methanol and water are produced at high pressure in the reactor and then exit the system under low pressure and temperature in the knockout drum. The remaining, unreacted recycle gas that leaves the knockout drum is mixed with fresh synthesis gas before being sent back through the synthesis loop. The unit operates entirely on electricity and includes a high-pressure electrolyzer to obtain gaseous hydrogen and oxygen directly from purified water. Thus, the sole inputs to the trailer are water, carbon dioxide and electricity, while the sole outputs are methanol, oxygen, and water. A distillation unit separates the methanol and water mixture on site so that the synthesized water can be reused in the electrolyzer. Here, we describe and characterize the operation of the methanol synthesis unit and offer some possible design improvements for future iterations of the device, based on experience.

Carbon Dioxide and Water Mixture in Pipeline Flow Systems

2018 ◽  
Author(s):  
Faraj Ben Rajeb ◽  
Mohamed Odan ◽  
Yan Zhang ◽  
Syed Imtiaz ◽  
Amer Aborig ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Flow Regime ◽  
Flow Rate ◽  
Critical Issue ◽  
Water Mixture ◽  
Two Phase ◽  
Mean Pressure ◽  
Point Pressure ◽  
Temperature Levels ◽  
Phase Water

Global warming is considered the most challenging issue facing humanity today, with many research studies now focusing on investigating the main cause of this problem. Studying the behaviour of carbon dioxide in its different phases can provide the key to resolving this critical issue. In the present study, pipe flows are used to investigate the behavior flow of water-CO2 mixtures at different pressures and temperatures. The flow rate and pressure of water and CO2 are changed by using a pump placed before the mixing point. Pressure and temperature levels are recorded by sensors and thermocouples affixed at points along the pipe loop. The flow rate of water and carbon dioxide is changed simultaneously, and the flow regime of two-phase water-CO2 flow is visualized through transparent tubes. After repeating experiments several times, we found that the mean pressure drop along the tube for water-CO2 system flow is about 4 kPa/m. We also predict that the flow regime of the flow is often intermittent.

Practical Experience With a Mobile Methanol Synthesis Device

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Eric R. Morgan ◽  
Thomas L. Acker
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Synthesis Gas ◽  
Methanol Synthesis ◽  
Low Pressure ◽  
Practical Experience ◽  
Gaseous Hydrogen ◽  
Distillation Unit ◽  
Water Mixture ◽  
Pressure Side

A methanol synthesis unit (MSU) that directly converts carbon dioxide and hydrogen into methanol and water was developed and tested. The MSU consists of: a high-pressure side that includes a compressor, a reactor, and a throttling valve; and a low-pressure side that includes a knockout drum, and a mixer where fresh gas enters the system. Methanol and water are produced at high pressure in the reactor and then exit the system under low pressure and temperature in the knockout drum. The remaining, unreacted recycle gas that leaves the knockout drum is mixed with fresh synthesis gas before being sent back through the synthesis loop. The unit operates entirely on electricity and includes a high-pressure electrolyzer to obtain gaseous hydrogen and oxygen directly from purified water. Thus, the sole inputs to the trailer are water, carbon dioxide, and electricity, while the sole outputs are methanol, oxygen, and water. A distillation unit separates the methanol and water mixture on site so that the synthesized water can be reused in the electrolyzer. Here, we describe and characterize the operation of the MSU and offer some possible design improvements for future iterations of the device, based on experience.

scholarly journals Clathrate hydrates in interstellar environment

2019 ◽  
Vol 116 (5) ◽  
pp. 1526-1531 ◽  
Author(s):  
Jyotirmoy Ghosh ◽  
Rabin Rajan J. Methikkalam ◽  
Radha Gobinda Bhuin ◽  
Gopi Ragupathy ◽  
Nilesh Choudhary ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Thermal Treatment ◽  
Interstellar Medium ◽  
Molecular Mobility ◽  
Chemical Processes ◽  
Clathrate Hydrates ◽  
Water Mixture ◽  
Prebiotic Molecules

Clathrate hydrates (CHs) are ubiquitous in earth under high-pressure conditions, but their existence in the interstellar medium (ISM) remains unknown. Here, we report experimental observations of the formation of methane and carbon dioxide hydrates in an environment analogous to ISM. Thermal treatment of solid methane and carbon dioxide–water mixture in ultrahigh vacuum of the order of 10−10 mbar for extended periods led to the formation of CHs at 30 and 10 K, respectively. High molecular mobility and H bonding play important roles in the entrapment of gases in the in situ formed 512 CH cages. This finding implies that CHs can exist in extreme low-pressure environments present in the ISM. These hydrates in ISM, subjected to various chemical processes, may act as sources for relevant prebiotic molecules.

scholarly journals Thermodynamic and Kinetic Description of the Main Effects Related to the Memory Effect during Carbon Dioxide Hydrates Formation in a Confined Environment

2021 ◽  
Vol 13 (24) ◽  
pp. 13797
Author(s):  
Federico Rossi ◽  
Yan Li ◽  
Alberto Maria Gambelli
Keyword(s):  
Carbon Dioxide ◽  
Memory Effect ◽  
Water Mixture ◽  
Kinetic Description ◽  
Local Conditions ◽  
Demineralized Water ◽  
Confined Environment ◽  
Main Effects ◽  
Over Time ◽  
Process Completion

This article consists of an experimental description about how the memory effect intervenes on hydrates formation. In particular, carbon dioxide hydrates were formed in a lab–scale apparatus and in presence of demineralized water and a pure quartz porous medium. The same gas-water mixture was used. Half of experiments was carried out in order to ensure that the system retained memory of previous processes, while in the other half, such effect was completely avoided. Experiments were characterized thermodynamically and kinetically. The local conditions, required for hydrates formation, were compared with those of equilibrium. Moreover, the time needed for the process completion and the rate constant trend over time, were defined. The study of these parameters, together with the observation that hydrates formation was quantitatively similar in both types of experiments, allowed to conclude that the memory effect mainly acted as kinetic promoter for carbon dioxide hydrates formation.

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