Qugas

For the constant measuring of the PCS

The gas distribution system is characterized by high variability of the PCS caused by many combinations that can result from the mixing of different supply sources. The chemical composition of natural gas varies widely depending on the source, with a variation of PCS of up to 8% in a range from 37,650 to 40,750 KJ/Smtc

The method currently adopted for determining PCS (in the various A.O.P.), leads to inevitable errors in the calculation of energy supplied due to a number of variable factors:

  • the application of an arithmetic average per month
  • exclusion of variations in rate of extraction
  • the gas analyzed at the sampling points does not effectively represent that supplied at the point of delivery due to the distance between the two points and/or the configuration of the transport and distribution network
Gascromatografo

Gascromatografo

As it is, the declared uncertainty for the determination of the PCS figure (used for invoicing) is at best 2%. The technical solution already applied for a number of years for correctly determining the energy, consists in the realization of a single measuring system for the simultaneous on-line processing of Stmc volumes and PCS on the same plant. The qugas package solution consists essentially in installing a gaschromatography device in the area of the existing measuring system for the constant measuring of the PCS, eliminating the uncertainty associated with the method of sampling at the A.O.P.

The measuring system and the reserved area of the Internet portal provide the following data for each day of the month:

  • volume supplied per day in Stm3
  • relative PCS average per day in kJ/Stm3
  • energy supplied per day in MJ

This solution has already been approved in the “network code” issued by Snam Rete Gas, in which the requirements and performance of the gaschromatography device to be used are defined, along with the installation method and management procedures. It is also useful to assess the possibility of obtaining additional indirect advantages from the availability on-line of the PCS figure for areas of the site, like for example obtaining a daily energy balance, or adjusting a process to improve efficiency.

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