Water－Aromatic Liquid－Liquid－Vapour Equilibrium Calculation Using a Cubic Equation of State

Ｗａｔｅｒ－ＡｒｏｍａｔｉｃＬｉｑｕｉｄ－Ｌｉｑｕｉｄ－ＶａｐｏｕｒＥｑｕｉｌｉｂｒｉｕｍＣａｌｃｕｌａｔｉｏｎＵｓｉｎｇａＣｕｂｉｃＥｑｕａｔｉｏｎｏｆＳｔａｔｅＧｕａｎｇｈｕａＧａｏ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ...     

LKP方程在天然气相平衡计算中的应用

由于液化天然气(LNG)所具有的低温特性,其在储运中必然会发生相态的变化.目前,对于天然气相平衡的计算大多应用状态方程法,采用P-R方程和SRK方程进行计算.本文采用了LKP方程进行了气液相平衡的计算,通过与实验值的对比表明:应用LKP状态方程用于天然气及混合制冷剂的相平衡计算具有较好的精度,能够满足进一步天然气热物性...     

Exergetic analysis of carbon dioxide vapour compression refrigeration cycle using the new fundamental equation of state

The purpose of this paper is to present exergy charts for carbon dioxide (CO₂) based on the new fundamental equation of state and the results of a thermodynamic analysis of conventional and trans-critical vapour compression refrigeration cycles using the data thereof. The calculation scheme is anchored on the Mathematica platform. There exist upper and lower bounds for the high cycle pressure for a given set of evaporating and pre-throttling temperatures. The maximum possible exergetic efficiency for each case was determined. Empirical correlations for exergetic efficiency and COP, valid in the range of temperatures studied here, are obtained. The exergy losses have been quantified.     

Calculation of NARM‘s Equilibrium with Peng—Robinson Equation of State

The liquid molar volumes of nonazeotropic refrigerant mixtures (NARM), calculated with Peng Robinson (PR) equation, were compared with vapor -liquid equilibrium experimental data in this paper. Provided with co-reaction coefficient k _ij , the discrepancies of liquid molar volume data for R22+R114 and R22+R142b using PR equation are 7.7% and 8.1%, respectively. When HBT (Hankinson-Brobst-Thomson) equation was joined with PR equation, the deviations are reduced to less than 1.5% for both R22+R114 and R22+R142b.     

Can China afford to commit itself an emissions cap? An economic and political analysis

As the world’s second largest carbon emitter, China has long been criticised as a ‘free-rider’ enjoying benefits from other countries’ efforts to abate greenhouse gas emissions but not taking due responsibilities of its own. China has been singled out as one of the major targets at the subsequent negotiations after the Kyoto curtain had fallen. By analysing the historical contributions of inter-fuel switching, energy conservation, economic growth and population expansion to China’s CO₂ emissions during the period 1980–1997, this article first demonstrates that the above criticism cannot hold its ground. Next, we analyse what the economic effects would be if China’s carbon emissions in 2010 were cut by 20 and 30%, respectively, relative to the baseline. We found that China’s GNP losses under the two less restrictive carbon limits are in the same range as the often reported estimates for industrialised countries under very restrictive carbon limits. Then the article envisions some efforts and commitments that could be expected from China until its per capita income catches up with the level of middle-developed countries. By emphasising the win–win strategies, these efforts and commitments could be unlikely to severely jeopardise China’s economic development and, at the same time, would give the country more leverage at the post-Kyoto climate change negotiations. Finally, the article is concluded with the argument that combating global climate change is in China’s interest. It will be beneficial to a more sustainable development of the Chinese economy as well as to the global climate.     

Calculation of NARM's Equilibrium with Peng-Robinson Equation of State

IntroductionThere are mainly tWo well-known methods for thecalculation of fluid Phase equilibriUm, the method ofusing equation of state (EOS) or achvity coeffident.The later needs a plenty Of vapor-liquid equilibriumexperimental data in Order tO regress the calculatingmodel's parameters (such as non-random tWo liquidequation, (NRTL) etc). All means to describethermodynndc prOPelties are theoretically fonddedwith the equation Of state. If the EOS is suitable for theentire thermodyntalc …     

高压环境下液氧/氢的气-液平衡及其物理属性研究

在考虑氢气溶解的条件下,运用SRK状态方程计算了液氧/氢在超临界环境下达到气-液平衡时氢氧组分在各相中的摩尔分数以及液氧的蒸发热随液氧表面温度的变化情况;根据气-液平衡时各组分在各相中的摩尔分数,以甲烷为参比态气体,运用扩展对比状态理论(ECST)计算了气相及液相氢氧混合物的pVT属性、黏性及导热系数。结果表明,在高压环境下,有一部分氢气溶解于液氧中,且随着温度和压强的增加其溶解度增大;若考虑氢气溶解,则氢氧混合物的临界温度低于氧的临界温度且随环境压强的增加而减小,这时液氧的蒸发热小于其蒸发潜热,也小于不考虑氢气溶解所得蒸发热。当氢氧混合物达到气液平衡状态时,液相混合物的黏性及导热系数随温度升高逐渐减小,气相混合物的黏性及导热系数随温度升高逐渐增加,最终气相及液相混合物的传输属性在其临界点附近几乎相同。     

天然气液化工艺的相平衡计算

天然气液化流程广泛采用的是丙烷预冷混合制冷剂液化流程.为了进一步优化流程,减少能源的消耗,需要对整个流程进行模拟,而模拟过程中热力学参数的计算便是整个流程计算的基础.使用两种状态方程（SRK和PR方程）对热力学参数进行相平衡计算,为后续计算焓、熵等参数提供相应的解决办法,并判断选择的状态方程是否符合要求.     

高温高压湿空气气液相平衡PVT参数估算

以湿空气透平和压缩空气蓄能系统中的工质为研究对象,采用一种新的立方型状态方程对亚临界、近临界状态纯质水,以及目前实验温度和压力范围内的湿空气相平衡参数进行了计算。与现有实验数据比较,纯质水的饱和压力计算平均误差为0．09％,最大误差为0.44％;饱和气相比容计算平均误差为1．81％,最大误差为5．15％;饱和液相比容计算平均误差为2．30％,最大误差为5.47％。湿空气中水蒸气的摩尔分数计算平均误差为0．10％,最大误差为1．99％。这个新的立方型状态方程是目前计算水的相平衡参数和饱和湿空气性质较好的数学模型。     

Hydrogen production from biomass coupled with carbon dioxide capture: The implications of thermodynamic equilibrium

In this work we report on the consequences of thermodynamic equilibrium for hydrogen (_H2)$({\mathrm{H}}_2)$ generation via steam gasification of biomass, coupled with in situ carbon dioxide (_CO2)$({\mathrm{CO}}_2)$ capture. Calcium oxide (CaO) is identified as a suitable sorbent for CO₂ capture, capable of absorbing CO₂ to very low concentrations, at temperatures and pressures conducive to the gasification of biomass. The proposed process exploits the reversible nature of the CO₂ capture reaction and leads to the production of a concentrated stream of CO₂, upon regeneration of the sorbent. We develop a thermodynamic equilibrium model to investigate fundamental reaction parameters influencing the output of H₂-rich gas. These are: (i) reaction temperature, (ii) reaction pressure, (iii) steam-to-biomass ratio, and (iv) sorbent-to-biomass ratio. Based on the model, we predict a maximum H₂ concentration of 83%-mol, with a steam-to-biomass ratio of 1.5 and a Ca-to-C ratio of 0.9. Contrary to previous experimental studies, this maximum H₂ output is reported at atmospheric pressure. Model predictions are compared with an experimental investigation of the pyrolysis of pure cellulose and the reactivity of CaO through multiple CO₂ capture and release cycles using a thermogravimetric analyser, coupled with a mass spectrometer (TGA–MS). On this basis, we demonstrate the applicability of thermodynamic equilibrium theory for the identification of optimal operating conditions for maximising H₂ output and CO₂ capture.     

Potential of Ni supported on clinoptilolite catalysts for carbon dioxide reforming of methane

Carbon dioxide reforming of methane to synthesis gas has been investigated with Ni-supported clinoptilolite catalysts. The catalysts were prepared by using the incipient wetness impregnation method. The catalytic activity of Ni supported on clinoptilolite with varying Ni loadings was determined and the results showed that at 700 °C, 8 wt% Ni/clinoptilolite gave the highest activity. It exhibited not only the highest activity and selectivity but also remarkable stability. Moreover, both the activity and stability of this catalyst were observed to vary with the Zr content, exhibiting a maximum at a composition of 2% Zr. The amount of carbonaceous deposits on the spent catalysts was further investigated by temperature-programmed oxidation (TPO) and thermogravimetric analyzer (TGA) studies.     

世界二氧化碳埋存技术现状与展望

埋存CO2是避免气候变暖的主要方法之一,经过十几年的探索,CO2埋存技术取得了很大进步,欧美等世界典型埋存盆地和公司都取得了不错的CO2埋存成果。当前可行的埋存方式有三种:地下埋存、海洋埋存、森林和陆地生态埋存。地下埋存主要选择枯竭的油气藏、深部的盐水储集层、不能开采的煤层及深海埋存等方式。中国在CO2埋存方面具有广阔的前景。CO2埋存前景十分乐观,这一技术的推广和应用必将对全球CO2减排起到举足轻重的作用。     

Carbon dioxide reforming of methane over nickel catalysts supported on TiO2(001) nanosheets

As we all know, the critical problem of nickel catalysts for carbon dioxide reforming of methane is the deactivation of catalysts due to the carbon deposition and sintering of the active components under high temperature. It was reported that anatase TiO₂ nanosheets with high-energy (001) facets had strong interaction with nickel, which was probably beneficial to resist sintering of nickel nanoparticles and to eliminate deposited carbon via oxygen migration. In this study, Ni nanoparticles were supported on TiO2 nanosheets with exposed high-energy (001) facets. The Ni/TiO₂(001) catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, physisorption of N₂, X-ray photoelectron spectroscopy and H₂ temperature-programmed reduction, and the spent catalysts were characterized by Roman and thermogravimetry analysis. The catalytic performance of Ni/TiO₂(001) catalysts were measured for carbon dioxide reforming of methane reaction. It was found that the prepared Ni/TiO₂(001) catalysts showed reasonably higher catalytic activity and stability compared with the nickel catalyst supported on commercial titanium oxide (P25). The high dispersion of nickel nanoparticles of Ni/TiO₂(001) catalysts was helpful to the resistance towards carbon deposition and the strong metal-support interaction was helpful to the resistance towards nickel sintering on account of the unusual surface properties of TiO₂(001).     

氨水溶液节流过程中焦汤效应的试验研究

氨水是一种复杂的二元溶液,其状态方程至今尚无满意的关系式,因此对氨水等焓节流效应的研究有很大的现实意义。采用文献[1]提出的氨水立方体型方程的形式对氨水的汤姆-焦耳逊系数进行了理论的计算,并对氨水溶液节流效应进行了试验的研究。结果表明：采用的氨水立方体型方程计算的汤姆-焦耳逊系数与实验结果比较吻合;氨水在初始压力相同的情况下,节流后的压力越低得到的节流后温度越低,初始温度越高得到的节流后温度越高;氨水在初始温度相同的情况下,初始压力越高得到的节流后温度越低。     

Coke resistance of Ni-based catalysts enhanced by cold plasma treatment for CH4–CO2 reforming: Review

Carbon dioxide reforming of methane can reduce emissions of greenhouse gases, and has been extensively studied. The conventional Ni-based catalysts easily coke, sinter, and deactivate in the CRM reaction. The studies suggested that the cold plasma treatment can improve the structure of Ni-based catalysts, and so enhance coke resistance of the catalysts. The review summarized the effect of cold plasma treatment on the coke resistance of Ni-based catalysts for the CRM reaction. The main goal of the paper was to illuminate: the structure change of catalysts treated by cold plasma, such as crystal planes of Ni particles, the particles size of Ni, the Ni dispersion, the metal-support interaction, and CO₂ absorption capacity; the correlation between plasma treatment conditions (treatment way and parameters) and coke resistance of the catalyst treated by cold plasma; and the mechanism of plasma treatment to improve the coke resistance of the catalysts.