Experimental study of the hydrodynamic behaviour of slug flow in a horizontal pipe

Abstract

Abstract:Despite the research efforts in the last decades, the dynamic behaviour of gas-liquid two-phase flows remains a challenging topic. This is due to the growing demand within the petroleum, process and nuclear industries. In particular, data on the behaviour of these flows in more industry relevant fluids are limited. This paper presents a summary of the experimental results on the hydrodynamic behaviour of slug flow using airsilicone oil mixture in a horizontal 67 mm internal diameter pipeline. A series of slug flow regime experiments were performed for a range of injected air superficial velocities (0.29 to 1.4 ms -1 ) and the liquid flows with superficial velocities of between 0.05 to 0.47 ms -1 . The translational Taylor bubble velocity and slug frequency were measured using two pairs of Electrical Capacitance Tomography (ECT) probes. The expected linear dependence of the translational Taylor bubble velocity on the mixture superficial velocity was confirmed.Pressure drop was measured using a differential pressure (dp) transducer cell. The void fractions in the liquid slugs and Taylor bubbles and slug and Taylor bubble lengths parameters were obtained from the processed data.The average total lengths of the observed slugs were of the order of 8 to 46 pipe diameters. The dimensionless Taylor bubble length is concluded to increase as the gas superficial velocity increases. The average slug frequency was observed to increase as the liquid superficial velocity increases but on the other hand was concluded to be fairly weakly dependent on the gas superficial velocity. The measured translational Taylor bubble velocities, void fractions in the liquid, and slug frequencies are presented and compared to data predicted by empirical models available in the literature. A comparative analysis of this and the previously published experimental data sets confirms good agreement.Key words: ECT, Taylor bubble, liquid slug, slug unit, frequency, void fraction 2 | P a g e Introduction:The determination of the multiphase flow regimes that may exist within pipelines is a key factor to the development of efficient oil and gas production systems. As oil and gas reserves are being depleted in developed fields, activity is shifting to harsher and less accessible environments. As offshore production moves into deeper waters farther offshore, the cost of constructing and operating fixed platforms with separation facilities becomes increasingly challenging. An alternative solution is to utilize subsea production systems which entail minimum offshore processing. The adoption of this method requires the simultaneous transport of produced fluids to land-based separation facilities, with minimal offshore treatment to reduce the undesirable effects as corrosion, wax and hydrates formation. Thus, an accurate prediction of the multiphase flow characteristics that may be experienced within these pipelines is therefore required to effect the safe and economic design and operation of these transportation systems.Slug flows are the most preva...

Experimental Investigation of Air-Silicone Oil Slug Flow Development around a Horizontal 90 Degree Bend

“…The frequency of slugs has been commonly correlated in term of pipe diameter and liquid superficial velocity, where a neglected change with axial position is suggested. This work ,in accordance with to Fossa et al (2003), [10] and [11], indicates the frequency seems to be better correlated in term of Strouhal number as a function of liquid volume fraction. However, this approach needs to be tested against a wide range of experimental data before a final conclusion can be reached.…”

“…7 shows a satisfactory agreement between the experimental results and the correlation of Fossa et al and eq. (1), similar findings are reported by [10] and [11]. The frequency of slugs has been commonly correlated in term of pipe diameter and liquid superficial velocity, where a neglected change with axial position is suggested.…”

On gas-liquid intermittent flow in a horizontal pipe: Influence of sub-regime on slug frequency

“…Thaker and Banerjee (2015) 2017)). Abdulkadir et al (2016) found that the slug frequency data obtained in a 67 mm ID pipe with a mixture of air and silicone oil, can be well correlated using a gas based Strouhal number StG = ! " " ⁄ # and liquid volume fraction λL $ = " " + " ⁄ #.…”

Identification of horizontal slug flow structures for application in selective cross-correlation metering

“…A further way of analysing slug structural effects, is through the comparison of slug front and tail velocities. As pointed out by Abdulkadir et al [34], relatively close values of slug front and tail velocity can be used as an indication of good flow development. Therefore, by categorising the different slug structures within a developed flow, the variation present for the different structures can be used as an indication of their stability, or degree of representation.…”