Appliance Population Issues in Gas Interchangeability Testing

摘要

Due to declining local production, combined with (inter)national deregulation, the supply of natural gas is becoming progressively more diverse. Thus, LNG from all over the world is being introduced into the US market, while pipeline gas from Russia and LNG from the Middle East are becoming increasingly important for Western Europe. The change in geographical origin of natural gas is often accompanied by a change in gas composition; for example, compared to “lean” pipeline gases, most LNGs are rich in higher hydrocarbons, yielding increased higher heating values (HHV) and Wobbe Indices. Another cause of variations in natural gas composition is the fluctuation in the degree of gas processing being done, caused by fluctuations in gas and feedstock prices. With the increasing variation in gas compositions entering the market, the question has inevitably arisen as to the acceptability of the wider range of compositions for the end user: the question of “interchangeability”. In contrast to the goals of interchangeability studies in the 1940s, i.e., the “equivalence” of widely disparate natural and manufactured gases for the end user, the current discussion revolves around the acceptable changes in performance of the population of end-use equipment that has “seen” a relatively narrow range of natural gases. Not only has the range of gases changed, but the demands placed on end-use equipment by customers and regulatory agencies in terms of performance, safety and pollutant emission, has also changed. In addition, the climate regarding product liability is different as well.