Equal area constructions are basic graphical or iterative procedures that allow calculations of equilibrium conditions for a pure component, or equilibrium compositions for binary nonreactive mixtures or reactive mixtures that satisfy the condition of components minus reactions equal to two. Reactive mixtures can be multicomponent mixtures as long as they satisfy the previous condition. This paper first demonstrates that previously reported equal area algorithms for solving equilibrium conditions are numerically equivalent to a Newton-Raphson procedure. Then, given that result, the equal area algorithm for equilibrium calculations is modified to involve fewer function evaluations; moreover, this new algorithm is able to converge from various initial conditions, even for systems that other numerical procedures cannot accommodate.
In this paper, we have derived the transformational relationship between the porosity under triaxial, biaxial stress and uniaxial stress respectively. Moreover, porosity tests under biaxial and triaxial stress for 11 groups of parallel unconsolidated core samples are conducted. Based on the transformational relationship, we have converted the tested porosity under triaxial stress into the porosity under biaxial stress and then compared it with the tested porosity under biaxial stress. The results indicate that the theoretical porosity model is reliable and deformation of unconsolidated cores is approximate elastic deformation of the rock body. Therefore, the porosity under uniaxial stress can be converted from the porosity under biaxial stress, which can simplify the experimental procedure and equipment, and provide a new way of determining subsurface porosity of unconsolidated cores. Besides, the Poisson’s ratio of unconsolidated cores is much larger than that of the normal clastic rock, and the actual conversion factor should be used for the conversion.
The solubility of methane has been measured in 3 M solutions of alkanolamines at 75 ºC. The solutions also contained various loadings of H 2 SorCO 2 . Partial pressures of methane varied up to 6830 kPa. The effect of the acid gases on the solubility of methane is highly non-linear.
The coal bed methane (CBM) gathering pipeline system of Northern Fanzhuang is in Shanxi province of The People’s Republic of China, near the city of Jincheng. Its features include: low pressure, small throughputs, congestion of the landscape, and undulating terrain. As a result, the management and analysis of the system is very difficult because of the complex structure and the sensitivity to the pressure and to the flow. In response to these problems, a management system was developed using the Pipeline Simulation Network (PNS) pipeline simulation software, integrated with the geographic information system (GIS) and supervisory control and data acquisition (SCADA) system of the CBM gathering system. The management system can automatically generate the required simulation model for the selected systems, pipelines and stations from the GIS geometric information and database. It can perform online simulation with real time data from the SCADA for a quick, direct and precise evaluation of the pipeline system. All the simulation results are stored in the SQL database for history review, and are also sent to the GIS system. According to the simulation results, the status and the flow of the gathering pipeline system are visualized in GIS three-dimensional mode for a quick overall acknowledgement. In addition, more detailed information about the past and current data for each individual component in the gathering system can be searched, sorted and shown in GIS whenever required. The theory and methods for building the management system are discussed in this paper, including the architecture, the simulation model, the self-training of the model, the interaction between the PNS simulation and GIS system, and the three-dimensional search and visualization of the flow status in GIS. Finally, an example was presented to demonstrate the application using better management and regulation of the CBM gathering pipeline system.
Helium is produced from natural gas by treatment of vent gas from Nitrogen Rejection Units or LNG plants. There are 16 liquid helium plants in the world, 7 of which are outside of the United States. There are at least six industrial (specialty) gas companies in the world that have direct access to sources of helium: Air Liquide, Air Products, Linde, Matheson, Messer and Praxair. Conventional helium plants use cryogenic distillation to produce crude helium followed by PSA to purify it for liquefaction. There was a period of helium shortage in 2011–2014 which caused more efficient use of helium and helium recycling. The world is now experiencing a period of too much supply of helium, and new helium plants will come online in Qatar and Russia in 2018 and beyond. The global helium demand in 2016 is estimated at 5.9 Bcf, and the supply is around 6.0 Bcf. Helium plays an important role in modern industry and medicine. There are many applications for helium, but the single largest application is in MRI (Magnetic Resonance Imaging), which accounts for around 30% of all helium usage.
