1 Introduction

The Natural Gas (NG) demand profile has been changing in the last decades. Nowadays the Power Plant (PP) fuelled by NG is becoming the most dynamic vector of the NG demand in the world. The gas load curve is today more a function of the electrical dispatching rules than a consequence of the residential consumption behavior. Thus, understanding the expected PP operations means having a better knowledge about pipeline design. In case of networks without NG storage facilities, the design requirements and operational parameters are strongly linked with a right understanding of the transient analysis tools and an efficient line pack management. This paper analyses the operational requirements, the border conditions specified, transient vs. steady state cost benefit analysis and peak hourly vs. average daily flow rate design. The purpose of the paper is to verify the basic requirements and methodology to be used in the NG PP pipeline design, especially in networks without storage. A complete menu of simulations will be carried out for different pipe conditions, NG specification and load curves. The authors have more than 20 years' experience in NG Industry mainly in the Southern Cone Region. Argentina with more than 50 years of NG industry history shows three interesting facts worth analyzing:

  1. 47% of its primary energy matrix is filled up with NG (50% of the power generation).

  2. Its large pipe network (more than 7,500 miles of trunk line spread all over the country) does not have any NG storage

  3. Argentina has a deregulated Power and Gas Industry.

2. Summary of conclusions

(Systems without NG storage)

  • When green field projects are being analyzed the "Steady state design - Transient analysis verification methodology" is the recommended alternative. This statement is made taking into account the general misinformation, uncertainties and ignorance about the demand behavior at beginning of the project.

  • To minimize the design risk the load curve should be agreed between the Transportation Company and the shipper (PP). In certain cases a MHQ (Maximum Hourly Quantity) should be established. (In the minimum risk position: MHQ=MDQ/24).

  • The MDQ (maximum daily quantity) to be contracted by a PP consumer should be the peak gas demand required, otherwise a certain amount of risk due to " gas shortage" must be assumed.

  • When a transportation system has to be design, contract transportation capacity or market NG, should be taking into consideration that "equal transported mass volume does not imply equal transported energy amount".

PSIG 0105 Natural Gas Power Generation 4

3. Power Gas Demand
3.1. Natural Gas & Power infrastructure

The NG is intensely used in Argentina filling the 47% of the Argentine Primary Energy, Matrix. The 2000 production reached 1,6 TCF/y (45 BCM/y), while gas commercialized through transmission & distribution networks in 2000 was 1,3 TCF (37 BCM/y). The gas is consumed among the following sectors Residential & Commercial 27%, Industrial 37%, Power Generation 30% and others 6% (CNG transportation).

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