Use Of Gas Research Articles

Highly accurate gas chromatographic analysis of reference gases for use in vehicle emission measurements

A highly accurate gas chromatographic analytical method has been developed for the determination of the composition of gas mixtures. It was tested using a reference gas as an example consisting of 3.5% of CO, 14% of CO2, 0.2% of propane and residual N2 intended for the use in vehicle emission measurements. The method is based on comparison measurements with samples of a calibration gas, whose composition is iteratively adapted to that of the sample investigated using a gravimetric gas mixing method. For the gas chromatographic measurement, a molecular sieve column and a polymer column are used in parallel and in isothermal operation. All gas components can be determined by a single gas chromatographic measurement, and the relative uncertainty of measurement achievable is ?0.4%.

Microencapsulated fluorinated gases for use as imaging agents

It has been discovered that the incorporation of fluorinated gases, especially a perfluorocarbon such as octafluoropropane, into synthetic polymeric microparticles, significantly enhances echogenicity as compared with microparticles having air incorporated therein. The microencapsulated perfluorocarbon is manufactured with a diameter suitable for the targeted tissue to be imaged, for example, for intravenous or oral administration. In one embodiment, bioadhesive microparticles are formed for enhanced imaging of mucosal surfaces.

Plasma reformer-fuel cell system for decentralized power applications

A plasma-driven process is described for the reforming of hydrocarbon fuels into hydrogen-rich gases for use in fuel cells. High temperature non-catalytic reforming offers many advantages over thermal catalytic reforming. The high gas temperatures obtained via plasmas reduce the volume and weight of the reformer, due to the fast kinetic rates. In addition, it allows fast response to changing fuel requirements, a characteristic needed in mobile applications. A plasma reformer-fuel cell system could provide a means to increase fuel flexibility and cost reduction of systems for both stationary and mobile fuel cell systems, over a wide range of operating modes. In addition to steam reforming and partial oxidation, thermal decomposition could be used to provide hydrogen-rich gas with greatly reduced production of carbon dioxide. Plasma reformer-fuel cell systems could utilize a wide range of hydrocarbon fuels including diesel, gasoline, biomass, natural gas and alcohols.

Status of the hydro-hydrogen pilot project (EQHHPP)

The concept of a hydrogen-based, clean, renewable energy system, conceived by the Joint Research Centre Ispra of the Commission of the European Communities, is currently being investigated by European and Canadian industries, coordinated by the JRC-Ispra of the Commission of the European Communities and the Government of Québec. The 100 MW pilot project is to demonstrate the provision of clean and renewable primary energy in the form of already available hydroelectricity from Québec, converted via electrolysis into hydrogen and shipped to Europe, where it is stored and used in different ways: electricity/heat cogeneration, vehicle and aviation propulsion, steel fabrication and hydrogen enrichment of natural gas for use in industry and households. Phase II, the detailed system definition, indicates the costs of the electrolytic hydrogen produced with hydropower, which would be available at 2 centsECU kWh−1 (cents of European Unit of Account, reference price for cost calculation) shipped to and stored in a European port, as 14.8 centsECU kWh−1 in the form of liquid hydrogen. The present Phase III,0 is a hydrogen demonstration programme on the utilization of hydrogen in the fields of vehicle and aviation propulsion, steel fabrication and advanced techniques of liquid hydrogen storage. This phase also involves detailed studies of safety measures and codes, along with socio-economic studies on the comparison of hydrogen with conventional fuels.

Conversion of Synthesis Gas to Isobutylene over Zirconium Dioxide Based Catalysts

Recent amendments to the Clean Air Act have renewed interest in synthesizing isobutylene from coal derived synthesis gas for use in producing methyl-tertiary-butyl ether. Previous work in isosynthesis was performed at extreme conditions or at very low conversions. This paper reports on both the process conditions and the catalyst that give the highest yield of isobutylene. The catalysts were zirconia based and were synthesized by both a precipitation and a hydrothermal method. The effects of sodium, titanium, manganese, cerium, and thorium additives were investigated. Catalysts prepared by the precipitation method were most active while those prepared hydrothermally were more selective to the i-C 4′s. Results for the most active catalyst for each preparation method are as follows. A CO conversion of 35% (34% CH 4, 20% i-C 4′s, 26% C 5+, wt basis) was achieved at 673 K, 50 atm, 1/1 CO/H 2 ratio, and 150 sec space time over a precipitated 7% (wt) Ce-ZrO 2. A 1.6% Na, 10.3% Ti, ZrO 2 prepared hydrothermally gave a CO conversion of 16.7% (37% CH 4, 30% i-C 4′s, 22% C 5+) under the same conditions.

Inhibitor protection and corrosion monitoring in Benfield installation to purify gas for synthesis

AbstractThe aggressive media in the Benfield processfor preparing gasfor use in synthesis by means of ‘potassium purification’ consist of KHCO3 + K2CO3 solutions having total contents and molar ratios that vary over a very wide range which also contain diethanoloamine. Operating temperatures are typically 70–120°C. Despite the use of inhibitors, intensive corrosion of mild steel walls has been observed in several installations. In laboratory tests performed in simulated Benfield solutions, a relationship has been established between the inhibitor content necessary to suppress active dissolution and pitting corrosion and the total content and molar ratio of the carbonates. These results have been checked and verified in an industrial installation. The corrosion monitoring system applied to critical parts of the equipment allowed the solution composition to be controlled and an inhibitor content appropriate to the composition of the aggressive medium to be maintained. As a result, substantial decreases in c...

Euro-Quebec Hydro-Hydrogen Project (EQHHPP): a challenge to cryogenic technology

The concept of a hydrogen-based, clean, renewable energy system, conceived at the Joint Research Centre (JRC), Ispra of the Commission of the European Communities, is currently being investigated by European and Canadian industries, co-ordinated by the JRC, Ispra of the Commission of the European Communities and the Government of Quebec. The 100 MW | pilot project aims to demonstrate the provision of clean and renewable primary energy in the form of already available hydroelectricity from Quebec, converted via electrolysis into hydrogen and shipped to Europe, where the equivalent of some 14 600 tonnes of liquid hydrogen per year is handled and used in different ways: electricity/ heat cogeneration, vehicle and aviation propulsion, steel fabrication and hydrogen enrichment of natural gas for use in industry and households. This paper describes the different processes in the conceptual chain, i.e. production by electrolysis, liquefaction, overseas transport and storage. Considerations are discussed with respect to safety, standards, norms and regulations. The actual status of and indications for future work in the field are described.

Behaviour of electromagnetically rotated arcs in gas heaters and circuit interrupters

Magnetically rotated arcs are used in many commercial devices. The paper examines the communality of the fundamental processes which govern the behaviour of devices which use electro-magnetically driven arcs. Two representative applications of such arcs are considered. The first device is used to produce a uniformly heated gas for use in the processing industry and is a DC-operated device; the second is designed to interrupt alternating fault currents on electricity-distribution networks.Experimental information and theoretical modelling of the two types of devices are considered, particularly relating to the shape and velocity of the electric arc under the two operating connections.

The applicability of binary collision theories to complex molecules in simple liquids

The relaxation dynamics of vibrationally excited ground-state azulene molecules have been examined by picosecond transient absorption spectroscopy in a variety of different solvents including hexane, chloromethanes, methanol, CClF3, Xe, and Kr. A high pressure optical cell was used to liquify gases for use as solvents and to change their density and temperature independently over the entire liquid density range. Experimental results indicate that the vibrational cooling rate is strongly solvent dependent, with cooling rates of approximately 20 ps in molecular solvents and approximately 150 ps in atomic solvents. Comparison of the rates in Xe and Kr at constant number density demonstrates the strong effect of solvent mass on energy transfer. The effect of solvent temperature on vibrational cooling is minimal, as is the effect of solvent density. The latter result is quite surprising in light of earlier experiments on simpler molecular systems, such as I2 in Xe, and predictions of isolated binary collision theories. An explanation is offered from large scale molecular dynamics simulations of the system. In effect, azulene forms an ‘‘ordered Xe cluster’’ with xenon atoms; the xenon number density normal to the azulene molecular plane is independent of solvent density.

Scleral Buckling After Failed Air Injection Pneumatic Retinopexy-Reply

In Reply. —In his letter Dr Carim notes that in the April 1989 issue of theArchives, we had erroneously stated that the use of large volumes of air in pneumatic retinopexy might result in a higher incidence of retinal breaks as compared with smaller volumes of expansile gases. In that correspondence, we suggested that smaller volumes of intraocular gas result in less vitreous displacement immediately after injection. Because of other issues related to intraocular gas volume, we wish to clarify this issue further in regard to the selection of appropriate intraocular gases for use in pneumatic retinopexy. In his Air Injection Pneumatic presentation at the Pneumatic Retinopexy Symposium in San Diego, Calif, in August 1988, Dr Carim stated that he managed patients with cryotherapy and injection of filtered room air. Initially, room air injections were undertaken with a total volume of 1 mL, requiring paracentesis in all cases.

The 100 MW euro-Quebec hydro-hydrogen pilot project

The concept of a hydrogen-based, clean, renewable energy system, conceived by the Joint Research Centre-Ispra of the Commission of the European Communities, is currently investigated by European industries and the JRC-Ispra. The scope of the investigation is to establish the main characteristics of system and components and to give a first indication of costs. The 100 pilot project is to demonstrate the provision of clean and renewable primary energy in the form of Canadian hydropower converted via electrolysis into hydrogen and shipped to Europe, where it is stored and used in different ways: electricity/heat cogeneration, vehicle and aviation propulsion and hydrogen enrichment of natural gas for use in industry and households. Three transport/storage modes are investigated: methylcyclohexane as energy carrier shipped in normal oil product carriers, ammonia shipped in special tankers and liquid hydrogen shipped in special LH 2 ships and aeroplanes. First evaluations indicate costs of the electrolytic hydrogen, produced with hydropower at 2 Can, cents kWh −1, stored in a European port of 69 Dpfg Nm −3 for the methylcyclohexane mode, 57 Dpfg Nm −3 for the ammonia mode, 30 Dpfg Nm −3 for the LH 2 mode by ship transportation and 77/68 Dpfg Nm −3 by air transportation. These averaged equivalent costs of 20 Dpfg kWh −1 (th) of clean, renewable and stored energy suggest competitivity within the not too distant future.

Evaluation of Parts-per-billion Organic Cylinder Gases for Use as Audits During Hazardous Waste Trial Burn Tests

A repository of 14 gaseous organic compounds at parts-per-billion levels (7-430 ppb) in compressed gas cylinders has been established by the Environmental Protection Agency. This repository was established to provide audit materials for use in conducting performance audits to assess the accuracy and precision of principal organic hazardous constituent (POHC) measurements, especially those performed during hazardous waste trial burn tests. Five- and nine-component mixtures In a balance gas of nitrogen were prepared in aluminum cylinders for use in the performance audit program. The five-component mixtures contain carbon tetrachloride, chloroform, perchloroethylene, vinyl chloride, and benzene. The ninecomponent mixtures contain trichloroethylene, 1,2-dichloroethane, 1,2-dibromoethane, acetonitrile, trichlorofjuoromethane, dichlorodifluoromethane, bromomethane, methyl ethyl ketone and 1,1,1-trichloroethane. Studies of all 14 gaseous organic compounds were performed to determine the stability of the compound...

99mTc particle perfusion/99mTc aerosol ventilation imaging using a subtraction technique in suspected pulmonary embolism

It is generally acknowledged that ventilation-perfusion mismatch is diagnostic of pulmonary embolism. Lung ventilation imaging with radioactive gases is a good method for the detection of pulmonary embolism, but it is not in widespread use because of the limited availability of 81mKr gas and the poor physical properties of 133Xe. Aerosols have been proposed, instead of gases for use in lung ventilation imaging. As perfusion and ventilation distributions may change very rapidly, the two imaging procedures should be done in rapid succession. The cheapest way to perform the combined perfusion-ventilation (Q/V) imaging is to use 99mTc-labelled macroaggregates and aerosols. In our method the perfusion imaging was done first, immediately followed by the ventilation imaging with 99mTc-labelled aerosols. A computer program was used to subtract the contribution of the perfusion from the combined Q/V image so that the pure ventilation image alone was obtained. The method was tested in 41 patients with suspected pulmonary embolism.

Performance Predictions for Electron-Beam Controlled On/Off Switches

An electron beam (e-beam) controlled switch makes use of the low-energy secondary electrons in a diffuse e-beam sustained discharge as the conducting medium which carries the switched current. The conductivity of the gas in the switch is negligible before the e-beam is turned on because the circuit parameters are chosen so that the open circuit voltage which appears across the switch electrodes is well below the static breakdown voltage of the gas in the switch gap. The e-beam switch can interrupt direct current because the density of the electrons in the switch decays by recombination and attachment when the e-beam is turned off and the switch conductivity decreases. In typical circuits, this decay in conductivity causes the switch voltage to rise and the switch current to fall, i.e., the switch turns off. This paper presents the results of a series of theoretical calculations which were performed in order to: 1) identify the electron transport and other gas properties which optimize the performance of e-beam switches, 2) evaluate the performance of several real gases for use in e-beam switches, and 3) determine the laws which predict the scaling properties of e-beam switches. Results are presented for N2, Ar, a N2:Ar = 1:9 mixture, and CH4. These results show that CH4 provides the best e-beam switch performance. Comparison of experimental results and theoretical predictions for CH4 supports both the theory and the predicted good e-beam switch performance for CH4.

Coal gasification development and commercialization of the texaco coal gasification process

The development of the Texaco coal gasification process utilizing an entrained bed downflow slagging gasifier is discussed. the advantages of the process including its simplicity and lack of formation of environmentally unacceptable and undesirable by-products are emphasized. Treatment of the crude gasification product gas to produce a clean gas for use as fuel or as feed stock for chemical manufacture is also covered. Status of the commercialization of the process is included.

Selection of dye vapors for use as active media and selection of buffer gases

A report is given of the results of measurements of the quantum efficiency η of the fluorescence emitted from 21 dyes in the vapor phase. A method is suggested for selecting buffer gases for use with dyes: this method is based on observations of the fluorescence and bleaching of vapors by an intense light flux. The results are given of a study of the influence of SF6 and butene-2 on the fluoresence of paraterphenyl and l,4-di[2-(5-phenyloxazolyl)] benzene (POPOP) vapors. It is shown that the absolute values of η of vapors can be deduced from the measured constants of the exponential fall of the fluorescence intensity as a result of action of a constant light flux.

A Method for Heating and Humidification of Gases for Use of the Bird Ventilator in Neonate Anesthesia

A Method for Heating and Humidification of Gases for Use of the Bird Ventilator in Neonate Anesthesia

A Mobile Multistage 3000-cfm Pumping System

A trailer-mounted two-stage booster mechanical pumping system has been constructed for use in evacuation of large vacuum vessels in remote locations. The pumping system is composed of three nominal 1500-cm air-cooled Roots blowers and four nominal 150-cfm mechanical pumps. It includes a high conductance cryogenic baffle, a self-contained helium leak detection station with a high speed oil diffusion pump, a liquid cryogenic system for supply of cryogenic fluids to the two cryogenic traps, and dry gas for use in backfilling of vessels as required. A programmed start-up and run-down control is provided for simplified, safe operation of the pumping system. A simplified method of presenting pumping system performance and a design analysis procedure for matching of mechanical pumps to the boosters are described.

A simple cold gas flow apparatus

A simple, inexpensive, and essentially foolproof apparatus is described for obtaining a constant temperature, constant flow of cold nitrogen gas for use in low-temperature diffraction studies.

Absorption cross-sections of atmospheric gases for use in aeronomy

The current status of absorption cross-section measurements for aeronomic use is reviewed. Recommended values for the gases O2, N2, O, and O3 are given at wavelengths where there is strong atmospheric absorption in the 3500–10 Å region. A table of absorption and ionization cross-sections at important solar emission lines is given. The problem of insufficient resolution at some wavelengths is discussed, and information on photolysis products is given where available.