INTRODUCTION

Union Gas with 485,000 customers is Canada's second largest distributor of natural gas. Union's franchise area in southwestern Ontario encompasses 10,965 square miles in which we operate a production, transmission, distribution and storage operation. With 93 BCF of developed storage capability and a main line system consisting of a 26" line looped with 34" and 42" connecting the Great Lakes Transmission system with the TransCanada Pipeline system (Figure 1), Union is uniquely positioned to provide a storage and transportation service to eastern Canada and the northeastern United States. We presently provide storage and transportation service for 4 other utilities as well as transportation service for TransCanada PipeLines. Union's storage system consists of 10 storage pools connected with 10" 'to 24" storage lines to our central compressor facility at Dawn (Figure 2). The usable capacity of the storage pools ranges from 2.5 to 22 BCF with design deliver abilities ranging from 12 MMCFD to 1000 MMCFD. In addition to our main line, we have several other major and minor transmission lines radiating from our Dawn Compressor Station. With this combination of storage pools, compression facilities and transmission lines. Union has a complex operating problem with a great deal of flexibility in how the markets are served. It also connects Union's Storage and Tecumseh Gas Storage with markets in Toronto and further east. During the winter months flow is in an easterly direction from storage and the Great Lakes system to Union's system, TransCanada and the Toronto market. As the load increases the discharge pressure from Dawn is increased to the maximum then units at Lobo and Bright compressor stations brought on line as required. The Trafalgar compressor station is run as required to deliver gas to TransCanada. In the summer months, the flow is westerly from TransCanada to Union's storage. We receive gas in the 500 to 600 psi range at Trafalgar where it is compressed towards Dawn. Compression at Dawn is used to inject this gas into storage as required. Since the storage is providing a peaking service, there are wide fluctuations in flow in both the summer and winter seasons. A recent agreement involving Union, TransCanada PipeLines Ltd. and Transco would require significantly increased transportation and storage capacity over the next few years. To accommodate this business we have been working on a long range plan to expand all storage pools currently under Union's control to their ultimate capacity of 120 BCF. This development, estimated to cost $165 million, involves not only additional storage fields, but a major expansion of our Dawn Compressor Station from the current 77,000 HP to 170,000 HP. Design of the station piping requires evaluating the effects of pressure losses in the pipe on compressor horsepower requirements to meet design peaks. In addition the effect of pipe size on annual fuel consumption over a wide range of operating conditions must be considered. For example, a design optimized on the peak requirements is probably over-sized when annual operating costs are considered.

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