Papers

In today’s charging world of technology there have been may changes in controls that now allow to truly compare a plug and seat regulator to a control valve for high-pressure natural gas installations such as: power plants, city gate stations, large industrial customers, compressor stations, and storage fields. The features, benefits, capabilities, and differences of both devices will be outlined, to enable the reader to make an educated selection. In addition, acceptable design practices will be reviewed concerning sizing, gas velocities, noise levels, equipment layout, and performance. The ball valve is the most commonly used type of modulating valve for natural gas pipeline control applications, for that reason, we will limit this discussion to comparison between the plug and seat regulator and versions of a 1/4 turn ball valve.

Pipelines have transported water, oil and gas for hundreds of years, serving residential communities, industrial sites and commercial centers reliably and silently. Leak detection systems (LDS) are needed because pipeline spills occur more frequently as infrastructure ages and more hazardous products are transported. Leak detection systems cannot prevent leaks, but they can certainly help minimize the consequence of leak. Regrettably, too many leak detection systems fail to detect leaks, and other leak detection systems are ignored by the operators because they are unreliable. Thus, leaks that should have been small spills become disasters that cost pipeline owners millions of dollars.

Natural gas sampling is performed for many reasons. Primarily sampling is performed to determine total gas composition, gas quality, and gas value. The three techniques normally used to obtain gas samples are continuous composite sampling, continuous online sampling, or spot sampling. This paper will discuss the various spot sampling techniques, proper sampling implementation, and equipment utilized to obtain spot samples.

While inaccuracies in measurement can be costly and common, they are also avoidable in many cases.
Technicians willing to study the experiences and best practices of industry leaders can make a world of difference by applying what they’ve learned and sharing this knowledge with others.
Composite sampling is a straightforward method. When managed correctly, samplers are able to take small bites of a flowing gas or liquid in such a way that the complete sample accurately represents what was in the pipeline for a given sample period.
Composite sampling continues to be a widely used method for economically and accurately collecting a representative sample for a prolonged sample period, so it is important for technicians in the field to develop an understanding of the best practices.

Advances in exploration, drilling and production technologies make it feasible to extract natural gas from sources that in the past have been regarded as unconventional and so, such sources are becoming a larger percentage of the gas supply. The feasibility of producing gas from a source is the primary factor in determining whether that source should be categorized as conventional or unconventional. What has been unconventional in the past may be considered conventional in the future.

Determination of fluid properties and phase conditions of hydrocarbon mixtures is critical for accurate hydrocarbon measurement, representative sampling, and overall pipeline operation. Fluid properties such as compressibility and density are critical for flow measurement, and determination of the hydrocarbon due point is important to verify that heavier hydrocarbons will not condense out of a gas mixture in changing process conditions.

Hydrocarbon Dew Point (HDP) remains one of the key quality parameters of natural gas streams. Its determination is needed for operational and safety considerations, as well as to satisfy tariffs and regulations in US and overseas pipeline operations. The recent development of shale gas in US has added to the need for accurate and consistent measurement of HDP across a range of different mixtures of natural gas.

In the one hundred and thirty years, or so that we have known natural gas as a fuel source in the United States, the demand for natural gas has grown at an astounding rate. There is virtually no area of North America that doesn’t have natural gas provided as an energy source. The methods of producing, transporting, measuring, and delivering this valuable resource have advanced, and improved in direct relation to the demand for a clean burning and efficient fuel. While today’s economic climate determines the rate of growth the gas industry enjoys, in a broad sense, natural gas is certainly considered essential and a fuel of the future.

Orifice plate meters are one of the most widely used technologies in industry for gas flow metering. This is due to their relative simplicity, the extensive publicly available data sets that led to several orifice plate meter standards [1, 2, 3, 4] and the fact that they are a relatively inexpensive method of gas metering. However, it is common in industry for gas meters to be installed in applications where the flows are actually wet gas flows, i.e. flows where there is some liquid entrainment in a predominantly gas flow. This is usually done out of economic necessity or due to the fact that the system designers were not aware at the systems conceptual design stage that the gas flow would have entrained liquid. Therefore, with the orifice plate meter being such a popular gas flow meter it is by default the most common wet gas flow meter.

The affect of wet gas flow on an orifice plate meter configured for gas flow service is complicated. There are on going research programs aimed at improving the understanding of the reaction of the orifice plate meter to wet gas flow. Whereas much of this research is published in recent conference papers it is very technical and is not always immediately relevant to the technician in the field how this information can be practically applied. This paper attempts to review the current scientific knowledge from a practical user’s stand point.