异辛烷热值标准物质

采用国家固体燃烧热基准,即电能标定的等温式氧弹热量计,为异辛烷热值标准物质定值。通过电能标定热量计的热容量,使热值结果溯源到温度、电流、时间和质量等国际单位上。采用自制的聚乙烯胶囊盛装异辛烷,避免了样品挥发引入的质量测量和不完全燃烧的系统误差。异辛烷热值标准物质在标准状态下的高位发热量为47777 J/g,扩展不确定度为52 J/g（扩展因子k=2）。     

Measurements of the Calorific Value of Methane with the New GERG Reference Calorimeter

A new reference calorimeter has been developed under a European research project and set-up by Physikalisch-Technische Bundesanstalt (PTB) in Germany. The objective of the project is to measure the superior calorific value (SCV) of methane and other pure gases with a measurement uncertainty of less than 0.05 %. This paper presents the measurement results obtained for methane. Nine repeatability measurements were made. The molar SCV obtained when the measurements were averaged is 890.578 kJ·mol^?1. This value agrees very accurately with the value of 890.63 kJ·mol^?1 specified by ISO 6976 [Natural Gas—Calculation of Calorific Values, Density, Relative Density and Wobbe Index from Composition. International Standard ISO 6976, corrected and reprinted 1996-02-01]. Twice the standard deviation determined for the measurements is 0.023 % and is thus clearly lower than in previous experiments. Two independent uncertainty analyses confirm that the envisaged total uncertainty of 0.05 % is achieved (95 % confidence level).     

基于氧弹热量计测量天然气发热量标准装置及方法的研究

根据天然气能量计量的研究现状和应用需求,研究了天然气发热量测量标准装置,采用绝热式氧弹热量计测量高纯甲烷气体发热量,使测量结果通过燃烧热标准物质溯源到国际单位上。设计并研制了平衡取气装置系统,实现了燃烧前样气的采集。高纯甲烷发热量测量结果为39900 J/m3,扩展不确定度为0.6%（k=2）。     

A Two-Sinker Densimeter for Accurate Measurements of the Density of Natural Gases at Standard Conditions

A special reference densimeter has been developed for accurate measurements of densities of natural gases and multicomponent gas mixtures at standard conditions of temperature and pressure (T _s = 273.15 K and p _s = 0.101325 MPa). The densimeter covers the range from 0.7 kg · m^?3 to 1.3 kg · m^?3; the total measurement uncertainty in density is 0.020 % (95 % level of confidence). The measurement principle used is the two-sinker method, which is based on the Archimedes buoyancy principle. The certified calibration laboratory of E.ON Ruhrgas AG, Germany, uses this densimeter to verify the standard densities of certified calibration gases (binary and multicomponent gas mixtures). Moreover, the densimeter is used to determine the compositions of commercially available binary gas mixtures with a small uncertainty of (0.01–0.03) mol%.     

Measurement of the Calorific Value of Methane by Calorimetry Using Metal Burner

With the diversification of natural gas origins and variations in natural gas compositions, the accurate measurement of the calorific value of natural gas has become a very important issue for the gas industry and standardization. Korea Research Institute of Standards and Science is developing a standard gas calorimeter based on the isoperibolic technique. This work describes the details of the experimental apparatus and procedures of the developed gas calorimeter along with the measurement results for the superior calorific value of methane at \(25\,^{\circ }\hbox {C}\). A burner made of stainless steel was used for the first time in this type of calorimeter, and the potential application of a metal burner to a gas calorimeter was investigated. Eight measurements were performed, and the deviation from international standards was 0.16 %. The deviation was mainly caused by the measurement of the burned methane gas. The measurement results show that the metal burner may potentially be employed in a gas calorimeter.     

Chemical thermodynamics of the vapor-oxygen gasification of graphite

A thermodynamic analysis of the vapor-oxygen gasification and combustion of graphite with a variation of the oxidizer excess α has been performed. Chemical reactions proceeding in the process of gasification and combustion, as well as components of flammable gases, which are the combustion products, have been determined. The channels of the distributing of the energy of exothermal and endothermal processes have been revealed. The energy of exothermal reactions compensates the endothermal effect of the reaction and increases the physical heat of the system. Expenditures on the endothermal reaction where flammable gases are produced are not irretrievable and transverse to the calorific power of the flammable gases. The effect of the oxidizer concentration on the adiabatic temperature at partial combustion of graphite has been analyzed. The thermal efficiency has been found as the ratio of the total thermal energy in the combustion of flammable gases and their physical heat to the spent energy, which is determined by the calorific power of graphite. The thermal efficiency is about 100%.     

Thermodynamic Research Improves Energy Measurement in Natural Gas

This paper gives a brief overview of existing energy measurement systems for natural gas and presents a novel correlative concept for determining the energy contained in a gas. In addition, it provides information on the development and application of a new fundamental reference equation of state. This equation greatly improves prediction of caloric properties and therefore allows optimization of the use of critical nozzles for metering natural gas flows of varying qualities. Laboratory tests of the new energy measurement system have shown that the target uncertainty of 0.2% for the calorific value is routinely reached. A feasibility study currently underway examines the possibility of building a reference calorimeter with an uncertainty of 0.05%.     

Viscosity Measurements and Predictions for Natural Gas

A vibrating-wire viscometer of very high precision was used to measure the viscosity of methane and of two natural gases. The experimental data were, in general, taken at temperatures of 260, 280, 300, and 320 K and at pressures up to 20 MPa, and additionally in the case of methane at temperatures of 340 and 360 K and at pressures up to 29 MPa. The estimated uncertainty is ±0.3 and ±0.5% for methane and the natural gases, respectively. The new experimental data for methane were used together with zero-density or low-density viscosity values from this study and from the literature to develop a viscosity equation for natural gas composed of two contributions. The mixing rule of Wilke [J. Chem. Phys. 18: 517 1950] was applied for the zero-density viscosity part which is based on zero-density correlations for twelve components (methane, nitrogen, carbon dioxide, ethane, propane, n- and isobutane, n- and isopentane, n-hexane, n-heptane, and n-octane) and agrees with the values derived from experiment within ±0.3%. The density dependence of the residual viscosity part was correlated with methane data only, neglecting any temperature dependence, whereas the composition dependence is characterized by a pseudo-critical viscosity value. For methane the agreement between the correlated and experimental data is within ±0.5 %. The values predicted with the correlation and the experimental data agree within ±1 % for both the high calorific, H, natural gas and the low calorific, L, natural gas.Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Kalibrierdruckerzeugung durch statische Gasexpansion

The method of generating well known calibration pressures by means of static expansion of gases is described and the required mathematical equations are derived in general form for real gases. Temperature effects caused by the expansion process are estimated and compared with experimental data obtained at an expansion apparatus. Thereafter, the experimental measurement of the expansion ratio and the generation of calibration pressures over a wide pressure range are discussed for a specific apparatus. Controlling the temperature by immersing the apparatus in a circulated water bath, the uncertainty contribution due to temperature effects was substantially reduced as compared to conventional apparatuses. The uncertainty budget reveals that this apparatus allows the generation of a pressure of, e.g., 0.1 mbar for various gases with a small relative uncertainty (2σ) of 1 . 10^‐3.     

A gas phase analysis technique applied to in-situ studies of gas–solid interactions

An ultrahigh vacuum technique using mass spectrometry for in-situ investigations of gas–solid interactions is described in this paper. Examples of chemical reactions (oxidation, hydration) between solids and gas mixtures, dissociation of gases on solid surfaces, outgassing of solid materials and permeation of gases through membranes are discussed where the experimental arrangement is explained in detail. This Gas Phase Analysis (GPA) technique can be used at temperatures from room temperature to 1200 °C and at pressures up to 1 atm. Aspects related to sample preparation, isotopic gas mixture selection, data acquisition, calibration and interpretation of the experimental data are also addressed.     

Superb storage and energy saving separation of hydrocarbon gases in boron nitride nanosheets via a mechanochemical process

Light hydrocarbon olefin and paraffin gas mixtures are produced during natural gas or petrochemical processing. The petrochemical industry separates hydrocarbon gas mixtures by using an energy-intensive cryogenic distillation process, which accounts for 15% of global energy consumption [1]. The development of a new energy-saving separation process is needed to reduce the energy consumption. In this research, we develop a green and low energy mechanochemical separation process in which boron nitride (BN) powders were ball milled at room temperature in the atmosphere of an alkyne or olefin and paraffin mixture gas. BN selectively adsorbs a much greater quantity of alkyne and olefin gas over paraffin gases, and thus the paraffin gas is purified after the ball milling process. The adsorbed olefin gas can be recovered from the BN via a low-temperature heating process. The mechanochemical process produces extremely high uptake capacities of alkyne and olefin gases in the BN (708 cm³/g for acetylene (C₂H₂) and 1048 cm³/g for ethylene (C₂H₄)) respectively. To the best of our knowledge, assisted by ball milling, BN nanosheets have achieved the highest uptake capacities for alkyne/olefin gases, which are superior to all other materials reported so far. Chemical analysis reveals that large amounts of olefin gases were quasi-chemically adsorbed on the in-situ formed BN nanosheets via C–N bond formation, whereas small amount of paraffin gases was physically adsorbed on BN nanoparticles. This scalable mechanochemical process has great potential as an industrial separation method and can realize substantial energy savings.     

气载氚监测仪校准用氚化甲烷体积活度测量方法及其不确定度分析

针对气载氚监测仪校准用气体参考源氚化甲烷,提出其体积活度测量方法,用催化氧化燃烧炉将其转化为氚化水,用二级串联鼓泡器收集氚化水,并用液体闪烁计数器测定活度,从而确定气体参考源氚化甲烷体积活度,并进行了不确定度分析测定实验室已有氚化甲烷的体积活度为17.4 MBq/m3,不确定度为6.4％(k=2),符合GBT 3015...     

高纯氮中微量氧分析的不确定度和氧气体标准物质在有效期内变化不确定度计算方法的讨论

介绍了氮中微量氧标准气体在研究过程中稀释气体高纯氮中氧分析不确定度的评价依据,给出了评价过程和结果.讨论了氧气体标准物质在有效期内变化不确定度的计算方法,对氧气体标准物质定值不确定度进行了评价.     

氧化亚氮(N_2O)标准气体复现性及性能评价的研究

论述了温室气体监测用N2O标准气体气相色谱分析方法和条件,并对该标准气体配制的均匀性、稳定性及随压力变化的实验结果进行了分析与考察,对该气体标准物质的性能进行了评价。     

氧化亚氮(N2O)标准气体复现性及性能评价的研究(续)

论述了温室气体监测用N2O标准气体气相色谱分析方法和条件,并对该标准气体配制的均匀性、稳定性及随压力变化的实验结果进行了分析与考察,对该气体标准物质的性能进行了评价.     

气相色谱法测量天然气热值的不确定度评定

根据天然气能量计量的研究现状和应用需求,提出了一种天然气发热量测量方法。该方法采用气相色谱仪测量天然气高位发热量,使用不同热值的标准气体对气相色谱仪进行标定,验证了标准物质的一致性及仪器的测量能力。对天然气发热量的测量结果进行不确定度评定,结果表明:在线气相色谱仪的扩展相对不确定度在0.15%～0.30%范围内。     

A broadband power meter calibration system in the frequency rangefrom 10 MHz to 40 GHz using a coaxial calorimeter

A broadband power meter calibration system based on a newly constructed coaxial calorimeter has been developed in the frequency region 10 MHz-40 GHz. The RF power is measured as the difference of DC power supplied to the calorimeter built-in heater in the RF load, when RF is turned off and on, holding an isothermal control between the RF load and a temperature reference. To minimize the error due to the adiabatic coaxial waveguide, we devised a new method utilizing its output port as a test port. The evaluations showed a calibration uncertainty of (0.28-2.2)% expressed by one standard deviation at the 1 mW level in the full band     

Extracting inert gases from water samples for analysis on a magnetic resonance mass spectrometer

A system for extracting and purifying inert gases from water samples has been developed that ensures the isolation of more than 90% of He and Ne dissolved in water. The system is linked to a magnetic resonance mass spectrometer (MRMS) that is used for determining the peaks of helium and neon isotopes and performing calibration measurements of reference gas mixtures. On this basis, the absolute amounts of ³He, ⁴He, and ²⁰Ne as well as the isotope ratios of ³He/⁴He and ⁴He/²⁰Ne in the sample are calculated with a good precision. The errors of determination depends on the amounts of isolated gases and the uncertainty of electrode potential adjustment in the ion source (for the MRMS operating in a double-beam mode); in the case of measurements on the static stage (for neon ions), an additional error component is related to the jumplike switching of the accelerating voltage.     

Co-firing of paper sludge with high-calorific industrial wastes in a pilot-scale nozzle-grate incinerator

Experiments on the co-firing of high-calorific industrial wastes with paper sludge were performed in a pilot-scale industrial waste incinerator with a nozzle-type grate system. The incineration capacity was approximately 160kg/h. The temporal variations in the temperatures and exhaust gas emissions were monitored and used as parameters for determining the desirable incineration conditions. The high CO emissions that were mainly due to the rapid vaporization of combustibles from high-calorific industrial wastes could be alleviated through the co-firing of sludge with the high-calorific industrial wastes. Because of the high nitrogen content in the sludge, the increase in the co-firing rate caused higher NO emissions in the flue gas. If the total calorific value of the feed was lower than 750,000kcal/h, for 25-30% of sludge co-firing, the temperature of gases exiting the secondary combustion chamber might be lower than that required by regulations.     

A New Instrument for the Measurement of the Thermal Conductivity of Fluids

The transient hot-wire technique is at present the best technique for obtaining standard reference data for the thermal conductivity of fluids. It is an absolute technique, with a working equation and a complete set of corrections reflecting departures from the ideal model, where the principal variables are measured with a high degree of accuracy. It is possible to evaluate the uncertainty of the experimental thermal conductivity data obtained using the best metrological recommendations. The liquids proposed by IUPAC (toluene, benzene, and water) as primary standards were measured with this technique with an uncertainty of 1% or better (95% confidence level). Pure gases and gaseous mixtures were also extensively studied. It is the purpose of this paper to report on a new instrument, developed in Lisbon, for the measurement of the thermal conductivity of gases and liquids, covering temperature and pressure ranges that contain the near-critical region. The performance of the instrument for pressures up to 15 MPa was tested with gaseous argon, and measurements on dry air (Synthetic gas mixture, with molar composition certified by Linde AG, Wiesbaden, Germany, Ar – 0.00920; O₂ – 0.20966; N₂ – 0.78114), from room temperature to 473 K and pressures up to 10 MPa are also reported. The estimated uncertainty is 1%.M. L. V. Ramires: DeceasedPaper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.