O2/N2、O2/CO2和O2/CO2/NO气氛下煤粉燃烧NOx排放特性

利用滴管炉研究了O₂/N₂、O₂/CO₂和O₂/CO₂/NO气氛下煤燃烧过程中NO_x的排放特性。实验结果表明,在O₂/N₂和O₂/CO₂气氛下,高温或高O₂浓度均使NO排放量增加。O₂/CO₂气氛下NO排放量比O₂/N₂气氛下NO排放量低大约30%～40%。在O₂/CO₂/NO气氛下,温度不同时,O₂浓度变化对NO排放量的影响规律不同,对循环NO降解的影响规律也不同。高温不利于循环NO降解。随停留时间的延长NO排放量出现两个峰值。     

6FDA型聚酰亚胺中气体溶解行为的分子模拟

用分子模拟方法对6FDA-durene、6FDA-pPDA及其共聚物6FDA-durene/pPDA的链间距及自由体积进行了模拟计算,结果与文献实验值一致;采用巨正则Monte Carlo(GCMC)方法模拟了O₂、N₂、CH₄和CO₂在聚酰亚胺中的溶解,计算结果表明：COMPASS力场能较准确地描述O₂、N₂和CH₄在聚酰亚胺中的吸附溶解,O₂、N₂、CH₄的溶解系数模拟结果与实验数据吻合较好。CO₂的溶解系数计算值与实验值偏差较大(约50％),主要原因可能在于模拟过程中未考虑体积溶胀效应以及COMPASS力场不能精确描述CO₂与—CF₃基团的相互作用。同一聚合物中,计算所得气体溶解系数的大小顺序为CO₂>CH₄>O₂>N₂,与气体凝聚性趋势一致,同种气体在6FDA型聚酰亚胺中的溶解系数与其自由体积分数变化趋势一致。3种聚合物对CO₂/CH₄的溶解选择性高于O₂/N₂,共聚物与均聚物相比,气体溶解选择性没有明显提高。     

O2/CO2气氛煤焦的燃烧及其孔隙结构变化

采用热力工况与实际煤粉炉相近的沉降炉实验装置,制备了不同环境气氛下（O₂/N₂及O₂/CO₂气氛）、不同燃尽率的煤焦试样,并采用低温氮吸附仪和扫描电子显微镜测定了其孔隙结构和表面形貌。结果表明,在相同的操作条件下,相同O₂浓度的O₂/CO₂气氛下煤焦的燃烧速率较慢、燃尽率较低,各试样的孔比表面积和比孔容积均较小。两种气氛下燃尽过程孔结构参数（SBET和VBJH）均呈减小趋势,且在孔径变化较明显的区域内（<5 nm）在CO₂气氛下煤焦的孔径分布较小且与煤种相关。SEM图像显示CO₂气氛下的煤焦表面致密,孔隙较少,其定性结果与N₂吸附法的定量测量结果吻合较好。     

煤在O2/CO2中燃烧的Nox释放规律

利用一维沉降炉,对3种煤在O₂/CO₂和空气两种气氛下燃烧NO_x析出特性进行了比较,分析了炉膛温度、过量空气系数对NO_x生成量的影响,并对O₂/CO₂气氛下NO_x的生成和破坏机理进行了分析.研究发现两种气氛下NO_x都有一个峰值出现,挥发分含量高的煤种峰值靠前, 挥发分含量低的煤种峰值靠后,O₂/CO₂条件下,峰值出现较空气条件下提前且有所下降;空气条件下NO_x的生成量随温度提高较快地增加,而O₂/CO₂气氛中NO_x的生成量随温度变化比较缓慢;在两种气氛下NO_x的峰值均随过量空气系数的增加而增加,高挥发分煤在O₂/CO₂气氛下NO_x峰值低于空气条件下峰值,而低挥发分煤则受影响较小.     

Fe/C杂化炭膜的制备及其气体分离性能

将二茂铁作为有机添加剂引入炭膜前驱体聚酰亚胺,经高温热解制备了Fe/C杂化炭膜。考察了二茂铁的添加量对杂化炭膜气体渗透性能的影响。采用热重、红外、X射线衍射和透射电镜等分析方法对所制备的杂化炭膜进行了表征。结果表明,在前驱体中添加二茂铁能显著提高炭膜的气体渗透性能,随着添加量的增加,膜的气体渗透系数明显增加而分离系数则减小,当二茂铁添加量为15%时,对H₂、O₂、N₂、CO₂、CH₄等纯气体的渗透系数分别为2806、1039、266、31、8 barrer,对O₂/N₂、CO₂/N₂、CO₂/CH₄的分离系数分别为8.6、33.5、129.5。Fe/C杂化炭膜是基于“分子筛分”机理分离气体分子。     

O2/CO2气氛下煤燃烧SO2/NO析出特性

在水平管式炉上研究了O₂浓度、CO₂浓度、温度及石灰石添加等各参数对O₂/CO₂气氛下徐州烟煤和龙岩无烟煤燃烧过程中SO₂/NO排放特性的影响。结果发现,O₂/CO₂气氛下,烟煤和无烟煤燃烧SO₂/NO的析出规律与空气气氛下不同,同等O₂浓度下析出量比空气气氛下小。O₂/CO₂气氛下,随着O₂浓度的提高,烟煤和无烟煤SO₂/NO排放量均增大;随着CO₂浓度的升高, SO₂/NO排放量均减小。O₂/CO₂气氛下,石灰石添加对SO₂排放的抑制作用低于空气气氛下;石灰石添加对NO的排放有一定减排作用。对煤灰的元素分析显示O₂/CO₂燃烧对SO₂的抑制主要是由于煤灰的自固硫能力增强,而对NO的减排作用则是促进燃料N向其他含N气体的转换。     

O2/CO2气氛下煤燃烧SO2/NO析出特性

在水平管式炉上研究了O₂浓度、CO₂浓度、温度及石灰石添加等各参数对O₂/CO₂气氛下徐州烟煤和龙岩无烟煤燃烧过程中SO₂/NO排放特性的影响。结果发现,O₂/CO₂气氛下,烟煤和无烟煤燃烧SO₂/NO的析出规律与空气气氛下不同,同等O₂浓度下析出量比空气气氛下小。O₂/CO₂气氛下,随着O₂浓度的提高,烟煤和无烟煤SO₂/NO排放量均增大;随着CO₂浓度的升高, SO₂/NO排放量均减小。O₂/CO₂气氛下,石灰石添加对SO₂排放的抑制作用低于空气气氛下;石灰石添加对NO的排放有一定减排作用。对煤灰的元素分析显示O₂/CO₂燃烧对SO₂的抑制主要是由于煤灰的自固硫能力增强,而对NO的减排作用则是促进燃料N向其他含N气体的转换。     

α-纤维素膜气体分离性能

制备了α-纤维素膜并对其气体分离性能进行了研究.测定了水溶胀下，CO₂、H₂、CH₄、N₂、O₂等气体在α-纤维素膜内的气体渗透速率.通过比较研究醋酸纤维素膜、苯甲酰化纤维素膜和聚砜膜在干态和湿态下的气体渗透性能，揭示了水对α-纤维素膜气体渗透性能的作用规律.     

气体与煤表面吸附作用的量子化学研究

选用褐煤、次烟煤、高挥发分烟煤、低挥发分烟煤和无烟煤5种煤表面结构模型,采用量子化学半经验方法INDO,从分子水平描述了CO、O₂、H₂O(g)、CO₂、CH₄和H₂等6种气体在煤表面的吸附作用,计算了气体在煤表面的吸附能、吸附距离、吸附作用键级和净电荷变化等微观参数,用Morse函数拟合了气体与煤表面的结合能曲线,得到了气体吸附作用强弱次序为：CO和O₂最强,H₂O和CO₂次之,CH₄和H₂最弱。     

超临界CO2萃取丁香油的数值模拟

为了预测超临界CO₂萃取挥发油动态过程,根据挥发油在超临界CO₂与物料之间的质量传递平衡,采用集总参数法建立超临界CO₂萃取丁香油过程的数学模型。结合不同温度、压力、粒径和CO₂流速条件下的实验结果,对方程进行了合理的简化,并利用实验数据拟合出模型中CO₂密度、粒径和流速的系数。验证结果表明模型的计算值和实验值的平均相对误差在6. 88%～57. 78%之间,建立的数值模型能较好地描述实际的超临界CO₂萃取丁香油行为。     

一氧化碳在苯酚+乙醇中的溶解度测量和关联

The solubility of carbon monoxide in phenol＋ethanol mixed solvents at elevated pressures is reported in this article. The experimental results revealed the influence of pressure on the solubility of CO in phenol＋ethanol mixtures. These mixtures are a poorer solvent for carbon monoxide. The solubility of CO is a linear function of pressure, and the extended Henry＇s constants were presented at different concentrations of phenol. The cubic Soave-Redlich-Kwong equation of state was used to correlate the experimental gas liquid equilibrium data and to predict the solubility of CO. At the same time, the binary interaction parameters, kO, for CO-phenol, CO-ethanol and phenol-ethanol systems were estimated by fitting experimental GLE data at 303.15 K and at 2.0-9.0 MPa. Hence, a model was suggested for the solubility of CO in phenol＋ethanol mixed solvents. The agreement between experimental and calculated solubilities with the proposed model was rather satisfactory.     

氢气和一氧化碳在混二甲苯中的溶解度

在１立升的高压机械搅拌釜中,采用气体间歇吸收技术,在８０－１６０℃,０．５－５ＭＰａ的范围内,测定了氢气和一化碳在混二甲苯中的溶解度。氢气和一氧化碳的溶解度随着温度和压力的增加而增大,且在相同的温度和压力下,一氧化碳的淀粉 度大于氢气的溶解度。与它们在间二甲苯中的溶解度相比,在混二甲苯中的溶解度是较小的。此外,使用正规溶液理论的Ｐｒａｕｓｎｉｔｚ－Ｓｈａｉｒ方法对它们的溶解度进行了估算。可以看出,一氧化碳在二甲苯中的溶解度的估算值与实验结果较相符,氢气由地临界温度较低,没有合适的估算式,故用实验回归的公式结合Ｐｒａｕｓｎｉｔｚ－Ｓｈａｉｒ方法中的其它公式进行估算,估算值与实验值大体相符。     

Influence of silica and black rice husk ash fillers on the diffusivity and solubility of gases in silicone rubbers

The preparation of elastomeric compositions based on poly(methylvinyl siloxane) using silica and rice husk ash as fillers is reported. Permeation of oxygen, nitrogen, carbon dioxide and methane across the compositions was measured in the temperature interval 30-60° C under upstream pressures lying in the range 15-76 cm Hg. Permeation and diffusion coefficients were independent on the upstream pressure but both parameters were thermal activated processes described by the Arrhenius equation. It was found that the activation energy associated with the diffusion process is larger in the filled than in the unfilled rubbers. The results also showed that the fillers enhance gas solubility in polysiloxane compounds in such a way that in most situations the sorption process is exothermic. The analysis of the solubility and diffusivity of gases in the rubbers suggests very good adherence matrix-fillers that hinder micro-Brownian motions thus impeding the normal development of non-permanent holes through which the diffusive particles can easily jump. Neither the proportion nor the nature of the fillers alters the permselectivity characteristics of polysiloxane based compounds.     

Fundamentals of Glass-to-Metal Bonding: IV, Wettability of Gold and Platinum by Molten Sodium DisiIicate

Further studies were made on the effect of the nature of the atmosphere on the wetting of gold and platinum by sodium disilicate at 1000°C. The gases were oxygen, nitrogen, carbon dioxide, helium, argon, water vapor, carbon monoxide, hydrogen, and several mixtures of some of these gases. Data reported were obtained in the pressure range 10 ^-5 mm. of Hg to approximately 1 mm. of Hg. A special experimental apparatus was constructed for this purpose. In this pressure range the results showed that the wetting of gold was unaffected by these atmospheres. The platinum-sodium disilicate contact angle, on the other hand, depended on the nature and pressure of the gas. This angle was affected most by atmospheres of water vapor, carbon monoxide, hydrogen, and oxygen. Water vapor was found to be easily displaced from the metal by oxygen. The results were interpreted on the basis of selective adsorption of the gases at the various metal interfaces and of absorption of oxygen and hydrogen by platinum.     

A study on the predictive capability of the SAFT-VR equation of state for solubility of solids in supercritical CO2

In this study, a version of the SAFT-VR equation of state based on the Yukawa potential is used for modeling the solubility of diverse organic compounds, mostly drugs, in supercritical carbon dioxide. Prior to any calculations, the SAFT parameters of pure CO₂ were obtained by correlating the vapor–liquid equilibrium data within the range of 220–300 K. The validity of these parameters was examined by applying them in prediction of the compressibility factor and density in wide temperature and pressure ranges. Due to dependence of the rest of the calculations on the sublimation pressure and lack of its experimental values for most of the solids, it was estimated through two main approaches: application of a group contribution method prior to correlating the solubility data, and calculating it in relation with temperature while correlating the solubility data. For each compound, the first isothermal set of the available experimental data was used for correlation and the rest were predicted. Adopting the same procedure for three empirical models and comparing the resulting deviation percents validated the superiority and high capability of this equation of state in correlating and particularly predicting the solubility in supercritical region. The predicted densities were also in very good agreement with the available experimental values.     

The barrier properties of polyethylene terephthalate to mixtures of oxygen, carbon dioxide and nitrogen

The diffusion and solubility of oxygen, nitrogen and carbon dioxide have been studied in amorphous and biaxially oriented films of polyethylene terephthalate (PET). To measure the sorption and desorption of each gas simultaneously in cases where mixtures of gases were studied, a mass spectrometer was used as a detector. It was found that the solubility and diffusion of nitrogen in PET were markedly affected by the presence of the other gases, oxygen and carbon dioxide with differences in detail between results for the amorphous and biaxially oriented films. It is of particular interest that the presence of oxygen reduces the solubility and increases the diffusivity of nitrogen.     

Assessing smoke toxicity of burning combustibles by four expressions for fractional effective dose

Toxicity of smoke generated in a fire is difficult to measure accurately. That is because gas sensors for measuring rapidly varying concentrations of toxic gases are not yet developed. Simple expressions are searched for quick measurement in assessing smoke toxicity practically. Four equations on calculating fractional effective dose (FED) related to toxic effluents were reported in the literature, each based on different assumptions. FED value was proposed to be calculated based on peak carbon monoxide concentration and peak carbon dioxide concentration, and transient carbon monoxide, carbon dioxide, and oxygen concentrations. The four values were compared in this article using literature data on toxic gases from different materials measured by (i) cone calorimeter; (ii) full-scale burning tests; and (iii) tunnel full-scale tests. Measured carbon monoxide, carbon dioxide, and oxygen concentrations by standard equipment of oxygen consumption calorimeters were used to calculate the four FED values. It is found that the values of FED based on peak carbon monoxide and carbon dioxide concentrations (denoted as FED₂) are similar to the average values of FED calculated from the updated equation in the literature using the oxygen consumption calorimeters. Putting the values of FED₂ in fire safety design guides is then recommended.     

Measurement and modeling of solubility of H2S in aqueous diisopropanolamine solution

Modeling of solubility of acid gases in aqueous alkanolamine solutions is essential for design of an absorber for natural gas sweetening. In this work an apparatus similar to the device of Hayduk and Chen (1970), which was improved by Pahlavanzadeh and Motahhari (1997), for the measurement of gas solubility data by the synthetic method was used. The solubility of hydrogen sulfide in aqueous diisopropanolamine (DIPA) solution in mass concentration range of 30–40% for 101,325 Pa pressure and for temperature ranging from 313–343 K was reported. The obtained experimental solubility data of H₂S in aqueous solutions of DIPA was used to predict the different interaction parameters of modified UNIQUAC-NRF model for calculating the activity coefficients. For nonideality of species in liquid phase, the UNIQUAC-NRF equation with ion-pair approach was applied. For long range interaction, the Pitzer-Debye-Huckel term was used.     

Single and mixed gas diffusion through polyethylene films

In this paper, the results of using a mass spectrometer technique to measure mixed-gas diffusion through polymer films are presented. Mixtures of oxygen, carbon dioxide and nitrogen are diffused through films of polyethylene with different degrees and type of chain branching. It is shown that in the case of pure gases Henry's law applies; the gas concentration is proportional to the partial pressure of gas. It is also demonstrated that there is a reasonable correlation between gas solubilities and the Lennard-Jones force constants, although detailed departures from this behaviour are observed for the different materials.The results show that, in general, the presence of one gas can affect the diffusion and solubility of another, although the solubility and diffusion of carbon dioxide were found to be independent of other gases. In particular, an apparent competition is observed between nitrogen and oxygen in terms of solubility. Moreover, the nature of the interaction between gases depends on the degree of branching and the state of annealing of the polyethylene. Contrary to expectation, it is shown that annealing, whilst increasing the crystallinity, increases the permeability of all gases for the only two samples studied in this regard.     

Ternary solubility of mono- and di-tert-butyl ethers of glycerol in supercritical carbon dioxide

Using a continuous flow apparatus, the ternary solubility of mono- and di-tert-butyl ethers of glycerol (MTBG and DTBG, respectively) in supercritical carbon dioxide was measured at the temperatures of 313.15, 333.15, and 348.15 K; a pressure range of 80-200 bar; and an expanded gas flow rate of 180 ± 10 mL min⁻¹ at average laboratory temperature of 300.15 K and pressure of 0.89 bar. The ternary solubility of the ethers at the constant temperatures of 333.15 and 348.15 K increased with increasing pressure up to the crossover point (i.e., 152 bar for MTBG and 170 bar for DTBG). MTBG exhibited a higher solubility than DTBG in scCO₂. The experimental data for the ternary solubility of MTBG and DTBG were correlated using the Bartle equation.