The pressure loss and flow rate in a coiled gas pipe was measured. The coil was treated with adsorbed layers for gas drag reduction purposes. The friction factor and the Reynolds number were calculated from the measured parameters, and finally the friction factor versus the Reynolds number were plotted. This was compared with the corresponding measured values conducting for a blank coil.

In this laboratory test, three inhibitors were tested, their names were confidentielle, so they were called A, B and C. The chemicals which gave the highest reduction of the friction factor was the inhibitor C. The inhibitor B also reduced the friction, but less than C. The inhibitor A, only reduced the friction factor in the beginning of the turbulent regime, but for higher Reynolds numbers, the friction factor increase above the friction factor observed for the blank coil.

The aim of this work was to use a small-scale lab setup to reduce the friction in a coiled pipe, by using gas drag reducing agents. The purpose of a drag reducing agent is to increase the throughput of the flowing fluid in a pipe. This is achieved by fixing an adsorbed layer at the surface of the metal inside the pipeline. A lot of work has been published in minimising hydrodynamic drag in pipelines for the flow of crude oil. However, for the friction reduction in gas pipelines, the published literature is scarce. It is believed that the reduction in friction factor is induced on a microscopic length scale level. The molecules in the gas drag reducing agent bind strongly to the metal surface and mitigate gas turbulence along the interface. The gas drag reducing agents used in this study are also filming chemicals that can directly reduce apparent pipe surface roughness and thus increase gas throughput.

The equipment used was originally constructed for measuring the pressure loss for porous core samples, but modified for the present work. Based on the experimental measurements, the friction factors and the Reynolds numbers were calculated. The friction factors obtained by using inhibitors were compared to the corresponding values for blank coils.

This report is organised as follows: In Chapter 2 the theory for the experiment is presented. In Chapter 3 the laboratory setup and the gas drag reducing agents are described. In Chapter 4 the setup alteration and preparation for this study are connected. Chapter 5 describes the procedure for preparing the adsorbed layer. In Chapter 6 the measured results are presented and discussed and Chapter 7 gives the conclusions.

The experimentally determined friction factor in a coiled pipe was noticeably reduced when an adsorbed layer of a drag reducing agent was applied to the inner surface of the pipe. The inhibitors A, B and C were the three chemicals used in this project.

The inhibitor C gave the best result in these experiments. It was also stated that the decrease of the friction factor is most effective in the beginning of the turbulent regime. The chemical A gave the worst result. In the beginning of the turbulent regime A, caused a reduction of the friction factor compared to the blank coil, but as the Reynolds number increased, the friction factor become higher, than the observed value before the treatment with the adsorbed layer. The inhibitor B reduced the friction factor in the entire turbulent regime but less than C.

It was discovered that the preparation procedure for each chemical affected the experimental results. The flushing process was variable for the chemicals. The inhibitor A was very volatile and needed one hour to flush out all the excess liquid, while for the inhibitors B and C, only required five minutes.

For further investigation on gas drag reducing agents, the following advises are recommend:

The inhibitors should be investigated prior to the experiments. In order to understand their properties. It could also be interesting to do some more experiments using other potential gas drag reducing agents. For example inexpensive solutions that are easy to acquire like oils and soaps before measurements are conducted with more expensive gas drag reducing agents.

The roughness inside the test pipe is also an unknown parameter which has not been measured. The roughness should be investigated before and after the treatment with the inhibitors. Photographs from the inside of the coil could be of interest. This would enable the investigator to see the effect and behaviour of the adsorbed layer.

Improvements of the setup design, may be to insert straight pipe segments, before and after the pipe, to ensure fully developed flow in the pipe, and calibration of the rotameter in the entire interval of rates, and not only in the interval where it overlapped with the smaller rate flow meters.

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