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The transport of unprocessed gas streams in production and gathering pipelines is becoming more attractive for new developments, particularly those in less friendly environments such as deep offshore locations. Transporting gas, oil, and water together from wells in satellite fields to existing processing facilities reduces the investments required for expanding production. However, engineers often face several problems when designing these systems. These problems include reduced flow capacity, corrosion, emulsion, asphaltene or wax deposition, and hydrate formation. Engineers need a tool to understand how the fluids travel together, to quantify the flow reduction in the pipe, and to determine where, how much, and what type of liquid that would form in a pipe. The present work provides a fundamental understanding of the thermodynamics and hydrodynamic mechanisms of this type of flow. We present a model that couples complex hydrodynamic and thermodynamic models for describing the behavior of fluids traveling in near-horizontal pipes. The model presented herein focuses on gas transmission exhibiting low-liquid loading conditions. The model incorporates a hydrodynamic formulation for three-phase flow in pipes, a thermodynamic model capable of performing two-phase and three-phase flash calculations in an accurate, fast, and reliable manner, and a theoretical approach for determining flow pattern transitions in three-phase (gas-oil-water) flow and closure models that effectively handle different three-phase flow patterns and their transitions. The unified two-fluid model developed herein is demonstrated to be capable of handling three-phase systems exhibiting low-liquid loading. Model predictions were compared against field data with good agreement. The hydrodynamic model allows (1) the determination of flow reduction due to the condensation of liquid(s) in the pipe, (2) the assessment of the potential for forming substances that might affect the integrity of the pipe, and (3) the evaluation of the possible measures for improving the deliverability of the pipeline. [DOI: 10.1115/1.3000135]

Pressure and temperature variations of natural gas flows in a pipeline may cause partial gas condensation. Fluid phase behavior and prevailing conditions often make liquid appearance inevitable, which subjects the pipe flow to a higher pressure loss. This study focuses on the hydrodynamic behavior of the common scenarios that may occur in natural gas pipelines. For this purpose, a two-fluid model is used. The expected flow patterns as well as their transitions are modeled with emphasis on the low-liquid loading character of such systems. In addition, the work re-examines previous implementations of two-flow model for gas-condensate flow. [DOI: 10.1115/1.1616584]

This work explores the possibility of utilizing the interaction between a pressure pulse propagating in a pipe with the blockages therein, as a means of blockage detection and characterization. Whereas an earlier work focused on a single blockage, the present work attempts to extend the strategy to multiple blockages. A one-dimensional isothermal non-compositional single-phase Eulerian model was used to describe the propagation of a pressure pulse through a pipe with multiple blockages. Pressure variations at the inlet caused by reflections of the propagating transient are monitored and analyzed. This analysis is used to make deductions about the internal configuration of the pipe. The results demonstrate that the technique is feasible and that accurate characterization of multiple blockages is possible. [DOI: 10.1115/1.1525002]

The modeling of pressure transient across constrictions is achieved by using a one-dimensional, isothermal, noncompositional, single-phase representation of the Eulerian model. A TVD scheme was used to solve the ensuing nonhomogeneous hyperbolic set of first-order quasi-linear partial differential equations. Three types of constrictions were modeled and in each case the behavior of the transient was analyzed. This analysis was used to interpret the pressure response at the inlet resulting from the reflection of the transient at the constrictions. The comparisons between the predicted and inputted data are very good, suggesting that the technique has much promise. [SO195-0738(00)00301-0]

Spondias mombin foliage was processed into fresh (as control), air-dried and sun-dried samples and were analyzed for proximate, fibre, minerals, vitamins and antinutrients. Also, Identified rumen microorganisms were exposed to non-reconstituted ethanol extract of the foliage. The results showed that crude protein, crude fibre and gross energy were greatly improved by drying from 4.9% to 15.1%, 2.1% to 18.4% and 0.9 kcal/g to 2.9kcal/g in that order. Fibre constituents improved from 11.5% to 67.9%, 7.2% to 53.6% and 2.9% to 9.3% for neutral detergent fibre, acid detergent fibre and acid detergent lignin. Similarly, all the mineral components were improved from 0.083% to 0.21%, 0.193% to 0.533% and 0.073% to 0.23% for Calcium, Phosphorus and Sodium respectively by drying. Drying decreased the Ascorbic acid, Riboflavin and Niacin contents from 27.8mg/100g to 9.1mg/100g, 0.083mg/100g to 0.033mg/100g and 0.323mg/100g to 0.143mg/100g in that arrangement. Above all, it was observed that drying tremendously improved the nutritional value of S. mombin foliage by reducing tannin from 2.2% to 1.64%, oxalic acid (2.1% to 1.38%), phytic acid (1.15 to 0.45%), saponin (1.18% to 0.72%) and trypsin inhibitor from 39.74% to 16.57%. However, drying did not influence the toxic potential of the foliage as indicated by susceptibility of all the rumen microorganisms except the mould species. The nutritional quality potentials observed in the present study suggested that S. mombin foliage may be efficiently utilized by ruminants for optimal performance. [ABSTRACT FROM AUTHOR]

The article presents a study conducted on examining the effects of using a simple numerical model for accurate blockage characterization in natural gas pipelines. Topics discussed through the model include analysis of reflected pressure waves, the partial differential equations for isothermal natural gas flow, and the quasi-compositional effect of real gases. It concludes that the model proved suitable to be used in blockage characterization and in analyzing transient flow in natural gas.