基于Redlieh-Kwong对比态方程的天然气压缩因子计算

对Redlieh-Kwong对比态方程进行了推导,并将AGA8报告中30组压缩因子实测值与混合物天然气压缩因子的计算值进行了对比分析,计算误差小于1. 20%。最后得到了压力、温度对天然气压缩因子的影响规律。     

超高压天然气压缩因子计算方法及其在气井压力计算中的应用

天然气压缩因子是天然气重要的物性参数之一,但是传统计算方法对于超高压天然气的计算存在较大误差.本文收集了超高压天然气压缩因子的实验数据,并将其进行拟合,得到了适用于高压天然气的压缩因子计算公式.并将这一公式应用于气井压力的计算当中,取得了较高的计算精度.     

实际气体压缩因子的应用

实际气体与理想气体有偏差,必须考虑压缩因子的影响。采用李和凯斯勒方程计算实际气体的压缩因子,并用PLC(可编程逻辑控制器)实现有关计算,解决了实际气体的密度补偿。     

运用立方型方程预测超高压下气体的压缩因子

通过vdW方程、RK方程、SRK方程和PR方程预测氮气、二氧化碳和甲烷气体在超高压情况下的压缩因子,此外进一步运用PR方程预测空气在压强为1000~2000 MPa的压缩因子,并与文献值进行比较,发现PR方程在超高压下计算气体压缩因子时有较宽的适应范围和较好的精度。     

天然气压缩因子计算及影响因素分析

天然气长输管道首端与末端之间往往会出现输差,输差是影响输气成本的一个最关键的因素。针对出现的输差问题,以天然气组分为基础,以压缩因子作为突破口,通过着重理解天然气压缩因子的解法与改进来得到控制输差。以BWRS方程为重点,通过Excel求得方程系数,然后从中解出气体密度,再代入气体状态方程中求得压缩因子。通过对天然气压缩因子的求解,得到影响压缩因子的主要因素,从而修正到天然气输量,以便减少输差。     

应用VB实现AGA8-92DC气体压缩因子计算方法

天然气压缩因子在天然气工程计算中具有重要的地位,其计算方法有多种,其中就包括由美国燃气协会提出的基于气体组成来计算压缩因子的AGA8-92DC方程。根据GB/T 17747.2-2011标准所给出的AGA8-92DC方法计算过程,用Visual Basic6.0 program编写了计算程序。为了验证程序的正确性,分别将程序计算值与GB/T 17747.2标准提供的计算值和含碳贫气气样实测值进行了对比,且获得了较小的计算误差。由计算值与实测值的对比结果可知,通过Visual Basic6.0 program所编写的AGA8-92DC方法计算程序而得到的计算结果能够满足工程上的要求;对于中高压含碳贫气,AGA8-92DC方法具有较高的计算准确度;当气体温度升高时,AGA8-92DC方法的计算误差将有所减小。     

基于普遍化压缩因子对小型LNG储罐蒸发气的计算研究

针对小型液化天然气（LNG）储罐,基于普遍化压缩因子图,在LNG储罐工作压力范围内,对理想气体状态方程加以修正,建立LNG储罐工作压力与压缩因子的关系,从而计算小型LNG储罐内蒸发气（BOG）质量,并提出改进的计算方法和BOG回收利用方案建议。     

状态方程计算高含硫天然气压缩因子评价研究

压缩因子在天然气开发与输运过程中是很重要的物性参数,其它一些参数的变化与压缩因子密切相关。但是对于高含硫天然气由于H2S的存在,使得临界参数产生较大偏差。目前应用较多的计算压缩因子的方法多是针对常规天然气的,故利用这些方法来计算高含硫天然气的压缩因子会产生较大误差。对于硫化氢摩尔含量小于12%的高含硫天然气体系,用RK、SRK、PR、BWRS状态方程计算在1.05≤Tr≤2,0≤Pr≤13范围内的压缩因子,并与标准压缩因子图进行了对比分析,得出这四个状态方程的适用范围。     

工程设计中气体压缩因子确定方法

实际气体仅在压力较低、温度较高的情况下近似满足理想气体状态方程式。当压力很高、温度很低时工程设计中常引入压缩因子。     

用构形因子关联纯物质的临界压缩因子

用纯物质的构形因子ξ对lnZc作图,可得一直线,对67种纯物质的Z_c实验数据,用最小二乘法电算回归得到推算纯物质Z_c的线性方程,lnz_c=-1.20586-1.10230ξ,用此式对67种纯物质的z_c值进行了计算,并与实验数据进行比较,结果表明,平均相对误差仅1.45％,标准偏差仅1.48％,对67种化合物以外的18种复杂大分子化合物的z_c值预测结果表明,本关联式的平均相对误差为2.17％,标准偏差为1.98％。     

A fundamental equation of state for the calculation of thermodynamic properties of chlorine

A fundamental equation of state is presented for the calculation of thermodynamic properties of chlorine. It is expressed in terms of the Helmholtz energy with the independent variables temperature and density. Based on the available experimental data from the literature, the equation is valid from the triple point temperature 172.17–440 K with a maximum pressure of 20 MPa. The quality of the equation is evaluated by comparisons with experimental measurements. Since the equation was developed in part for use in mixture models relevant for carbon capture and storage applications, special focus was also given to correct extrapolation behavior.     

L－K－P状态方程用于多元体系的计算

介绍了Ｌ－ｋ－Ｐ状态方程的对比密度根初值公式，等焓节流过程泡、露点温度的快速迭代公式。当对烃类多元体系进行热力参数、汽－液相平衡等计算时，推荐用两类不同状态方程同时进行计算，以相互校核计算结果。     

一个修正的多参数状态方程

从统计热力学的观点出发，结合经验的状态方程，对方程参数作出适当的修正，得到一个改进的适用范围广的多参数状态方程。结果表明，修正的状态方程精度较高。     

用BENDER状态方程计算N_2—Ar—O_2体系的热力学参数

Ｂｅｎｄｅｒ状态方程可用于Ｎ_２—Ａｒ—Ｏ_２三元体系，进行热力学性质计算精度较高．本文根据Ｂｅｎｄｅｒ方程推导出焓、熵、比热等热力学参数的计算公式，对Ｎ_２、Ａｒ、Ｏ_２及其混合物进行计算，并与实验数据进行比较，结果令人满意．     

正戊烯的Helmholtz状态方程研究

正戊烯是重要的精细化工产品中间体和原材料,同时也是燃料添加剂,具有广泛的工业应用。正戊烯的生产和应用过程中常常涉及萃取、精馏、汽提等化工过程,而这些化工流程的设计、模拟、优化等都依赖于准确可靠的热物性数据。通过文献调研发现,目前还没有正戊烯的专用状态方程发表,因此利用文献中公开发表的实验数据开发了正戊烯的专用状态方程。该方程以Helmholtz自由能为显式、以密度和温度为自变量,适用范围为：温度从三相点到500 K,压力最高达到100 MPa,密度不超过15 mol×dm⁻³。方程计算液相区密度的不确定度为0.2%,计算临界区及气相密度的不确定度为0.5%;计算饱和蒸气压的不确定度为0.3%,计算饱和液相密度的不确定度为0.2%,计算与能量相关的物性（例如C_sat、比热容、音速、焓等）的不确定度为1%以内。所开发的正戊烯专用状态方程不仅能够准确地复现实验数据,而且具有良好的外推性。     

Heat capacity of polymer melts from the polymer chain-of-rotators equation of state

Recently, the chain-of-rotators equation of state derived from the rotational partition function was extended to polymers. Values of the three equation of state (EOS) parameters were obtained from fitting with experimental pressure–volume–temperature data and the parameters were correlated with the structure of the polymer repeat unit. In this article, the residual molar heat capacity derived from an EOS is added to the ideal gas heat capacity from Benson's group contribution method to obtain the polymer molar heat capacity at constant pressure, C_p. Predictions from the polymer chain-of-rotators (PCOR) using correlated parameters are compared with those obtained from PCOR, Sanchez–Lacombe, Flory–Orwoll–Vrij, and the perturbed-hard-sphere chain equations of state using parameters fitted from experimental data. Deviations of calculated C_p from the formula of van Krevelen for liquid polymers are likewise presented. With the correlations developed for its parameters, the PCOR offers the advantage of predicting the C_p for polymer melts from just the knowledge of the polymer's structure. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:841–848, 1998     

A new four-parameter cubic equation of state for fluids

A simple cubic equation of state of the van der Waals type has been developed and successfully applied to both nonpolar and polar fluids. It contains four parameters and only one parameter is temperature-dependent. The parameters have been determined by using reliable data of vapour pressure and saturated liquid volume, and correlated in terms of critical properties and acentric factor. The P-V-T relationships, vapour pressures, volumes, and enthalpies of vapourization were calculated for a variety of substances. Comparison of the calculated results with experimental data and with results obtained from other equations shows that the proposed equation is a superior one in overall performance.     

Fluid-phase equilibria in binary systems containing an ionic liquid. Application of the Percus-Yevick-van der Waals equation of state

Following some simplifications to reduce the computational effort, the Percus-Yevick-van der Waals equation of state is used to calculate the isothermal total pressure of a binary liquid system containing one volatile nonelectrolyte liquid and one nonvolatile ionic liquid. Pure-component parameters a and b are found from pure-component enthalpy-of-vaporization and liquid-density data. The single binary parameter a₁₂ is obtained from Henry's constant for the nonelectrolyte in the ionic liquid. For 10 binary systems, calculated total pressures are in good agreement with experiment although in a few systems observed total pressures are slightly higher than those calculated in the region where the ionic liquid is dilute. Brief attention is given to a few binary systems with a miscibility gap.