Benefits of Installing Restrictive Orifice Plates On the Suction of Reciprocating Pumps:1D Pulsation and CFD Studies

Case Stud

Benefits of Installing Restrictive Orifice Plates on the Suction of Reciprocating Pumps: 1D Pulsation and CFD Studies

Case StudiesIt is well understood that static pressure at the inlet of reciprocating pumps, quantified typically by Net Positive Suction Head Available (NPSHA), must be sufficient to avoid cavitation in the pump suction manifold and chamber. In an effort to conserve NPSHA, pump designers generally rely on rules of thumb that resist the addition of pressure drop elements such as restrictive orifice plates, choke tubes and line-size reductions to the inlet piping of all pumps, including reciprocating pumps. Another design consideration of reciprocating pumps is the generation of pressure pulsations due to pump piston and valve motion. Uncontrolled pulsations can result in cavitation and vibration-related fatigue failures. In many cases, pressure drop elements are required to control pressure pulsations. Can there be a balance between the pulsation control benefits of pressure drop elements and the need to meet NPSHA? This paper is of interest to designers and engineers working with reciprocating pump installations. It aims at challenging industry resistance to using pressure drop elements in the suction piping of reciprocating pumps by, first, outlining the virtues achieved in terms of pulsation and vibration control, and second, presenting results from numerical simulations (one-dimensional pulsation and detailed CFD modelling). Recent field data from a quintuplex pump installation were used to validate the 1-D pulsation model. The results show that well-designed orifice plates, and other pressure drop elements, are beneficial for reducing pulsations and cavitation risks; and can be used in the suction piping of reciprocating pumps

Study of solid deposition phenomena and fluid properties of Alaska North Slope crude oil, gas-to-liquid products and their blends for transportation through the trans-Alaska pipeline system

Thesis (M.S.) University of Alaska Fairbanks, 2005Earlier studies on the options for utilization of Alaska North Slope (ANS) gas had indicated that it is economical to convert the gas to Gas-to-Liquid (GTL) products, blend it with the ANS crude oil and transport the resulting liquid through the existing Trans-Alaska Pipeline System (TAPS) to monetize the stranded gas. The objective of this study was to evaluate the effect of blending ANS crude oil with a GTL sample acquired from BP Alaska Inc. (BPGTL). Solid deposition phenomena and fluid properties of ANS crude oil, BPGTL and their blends were studied. The blends of BPGTL and ANS crude oil would require less pumping pressure. It is concluded from this study that the possibility of vapor and wax formation is precluded during transportation of the blends, and that asphaltene deposition is a potential major problem in blending ANS crude oil with BPGTL.Introduction -- Literature review -- GTL technology -- Rheological classification of fluids -- Gel strength -- Phase behavior -- Solid deposition -- Experimental techniques -- Experimental apparatus -- Experimental procedures -- Results and discussion -- Density -- Rheological parameters -- Gel strength -- Bubble point pressure -- Static asphaltene in ANS crude oil -- Stability of asphaltene in ANS crude oil -- Onset of asphaltene flocculation in ANS crude oil -- Influence of pressure on precipitated asphaltene in a flowing fluid -- Wax appearance temperature -- Vapor pressure -- Conclusions and recommendations -- References -- Appendices