Discharge and Dispersion for CO2 Releases from a Long Pipe: Experimental Data and Data Review

The second phase of the CO2PIPETRANS Joint Industry Project (JIP) aims to fill knowledge gaps associated with the safe and reliable pipeline transport of CO₂. The JIP has three main focus areas and technical work packages designed to address these. The work packages collect experimental data and experience on dense phase CO₂ release model validation data, pipeline fracture arrest, and corrosion. The CO₂ release model validation work package builds on two programmes of experiments previously undertaken for BP (2006/7) and Shell (2010/11) at the DNV GL (formerly GL Noble Denton) Spadeadam test site in the UK. These involved the horizontal release of pressurised liquid and supercritical (dense) phase CO₂ through ¼”, ½” and 1” (6 – 25mm) orifice diameters. This data can be downloaded from www.dnvgl.com/ccus.

The CO2PIPETRANS JIP has undertaken further CO₂ experimental work at the Spadeadam site. This work has been split into two programmes, one involving the release of liquid phase CO₂ through orifices ranging in diameter from 1” to 6” (25 – 150mm), and the other, the subject of this paper, involved the sudden release of 1450psi (100barg) CO₂from one end of a 660ft (200m) long, 2” (50mm) diameter horizontal pipe. The large release experiments are the subject of an abstract submitted by Jock Brown of DNV GL.

The pipe depressurisation experiments (sometimes referred to as ‘shock tube’ experiments) were performed by filling the pipe to the required test pressure and temperature whereupon a bursting disc at one end was deliberately ruptured. Pressure, temperature and mass instrumentation along the pipe recorded the instantaneous and subsequent depressurisation with additional data being recorded within the release plume. Video footage was also recorded of the release plume as well as through the pipe at the mid-length location. The experimental programme included 8 releases of 1450psi (100barg) CO₂through orifice diameters ranging from full-bore releases (50mm) to 10mm. The pipe was insulated for some of the releases.

This paper describes the CO2PIPETRANS JIP CO₂pipe depressurisation programme and the data recorded. It details the test rig design, instrumentation and operation as well as describes each release undertaken. The paper also provides an overview of the subsequent high-level data review and the conclusions of this review.

The data review was carried by DNV GL Software with the purpose of providing an initial assessment of the robustness of the data recorded. The review used the long pipeline model PIPEBREAK in the Phast consequence modelling package as a reference source.

The measured pressure and temperature data clearly demonstrate an initial pressure wave that travels with the speed of sound from the open to the closed end, and the very rapid depressurisation from the initial pressure to the saturated vapour pressure. During the subsequent two-phase flow the data review confirmed that the measured pressure was very close to saturated vapour pressure at the measured temperature (i.e. equilibrium between phases), adding further confidence to the quality of the data.