Abstract

This paper explores the potential of utilizing large diameter steel pipelines, that are no longer in use, to simultaneously transport small batches of different products.These pipelines were originally created in the United States to transport gas from the south to the north.As Canada emerged as a gas supplier to the northern states, these pipelines were no longer needed for their original purpose.Many of these pipelines were completely abandoned because an alternate usage was not identified for transporting large quantities of a single product.With these pipelines obsolete, building new smaller diameter pipelines was the only solution considered to accommodate the present need.

To accomplish the necessity of economically transporting small batches of product, multiple pipes are inserted into these large diameter steel pipelines.Polyethylene (PE) was selected as the piping material for this application because of the flexibility and tensile strength required during the insertion process.A method was developed to insert 10-mile sections of the PE pipes into the steel pipeline.Once these PE pipes are installed, a method of controlling and monitoring the flow is required. The control system allows the outputs to be maximized without causing failures such as bursting or leaking.Furthermore, to assure economical feasibility, performance benchmarks were proposed by industrial partners.

The model produced from this study analyzes steady state operation as well as transient effects such as opening/closing a valve or starting/stopping the pipeline.New formulas are derived to calculate frictional pressure drop for fluid flow in pipes containing internal pipes.National Instruments LabView, a graphical programming language, was used to transform the mathematical model into a real-time operational tool that can be directly connected to the pipeline system.

Introduction

In the past, many 16" diameter and larger steel pipelines were built in the United States that could transport large quantities of a single product.These pipelines were primarily used to transport gas from the south to the north.As Canada emerged as a gas supplier to the northern states, these pipelines were no longer needed for their original purpose.Many of these pipelines were completely abandoned because an alternate usage was not identified for transporting large quantities of a single product.With these pipelines obsolete, building new smaller diameter pipelines was the only solution considered to accommodate the present need.Construction of a new pipeline is a very expensive endeavor, largely due to the amount of labor involved.Minimizing this expense was one of the motivations for the exploration of a new technology that would utilize the old steel pipelines to produce a more economical solution.

Numerous benefits would result if the capacity of these large pipelines could be partitioned to allow for the transportation of multiple products.By transferring products in smaller batches, the supplier would reduce delivery time, minimize storage requirements, and increase the number of products provided to the user.This partitioning concept will be accomplished by inserting multiple smaller diameter pipes into the large diameter steel pipeline.

Due to the rigidity of steel pipe, a different piping material had to be used that was very flexible, but strong enough to overcome the tensile stresses that would be applied during the insertion process.Polyethylene (PE) pipe was selected because of its many favorable qualities and since it has been successfully used in the oil and gas industry for decades.PE became a popular replacement to steel because it possessed many superior qualities such as:greater flexibility, increased resistance to abrasion and chemicals, improved service life, and lower installation cost.Due to its toughness and flexibility, PE is used in various trenchless technology applications.Incorporating different existing technologies, a method to install this system was developed.

With the PE pipes installed inside the steel pipeline, a method of controlling and monitoring the flow is required.

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