Natural Gas Specification Challenges in the LNG Industry
Publication Date: 2009-May-05
The IP.com Prior Art Database
Paper # 2006
NATURAL GAS SPECIFICATION CHALLENGES IN THE LNG INDUSTRY
Senior Technology Manager - LNG and Gas Processing *
Felix F. de la Vega
Senior Consultant - LNG and Gas Processing Charles Durr
KBR Houston, Texas, USA
LNG is primarily methane, but in most cases also contains ethane, propane and heavier components. Until recently potential buyers of LNG had some flexibility in the ranges of natural gas properties they were able to accept. In many cases the LNG buyer exported electric power and not natural gas, and therefore did not have to meet the needs of natural gas consumers. But now new markets are opening up where pipelines to consumers already exist, and the consumers have specifications which lie outside the range of the LNG produced at many locations. The challenge is to understand the requirements of the potential new markets and plan ways to meet the requirements of both the LNG exporters and importers.
This paper reviews the natural gas specifications of current consumers and those expected in the near future, such as North America and others. These specifications are compared to those of LNG being produced, and the options and problems for conditioning the natural gas on either end of the LNG trade are explored in detail.
Paper # 2006
Natural gas contains methane, heavier hydrocarbons and inert components which affect burner performance. For this reason pipeline companies and LNG buyers specify allowable ranges of components and heating values. These requirements vary widely depending on the market location. But despite this, LNG product specifications have not been a major plant design issue. Historically, plant designs were based on long term contracts to few buyers, and there was little need for flexibility in the plant designs, either on the liquefaction or receiving ends of the trade.
However, the situation is changing as LNG trade becomes more global. The owners of liquefaction plants are targeting more than one market, and new markets have requirements that are not always compatible with existing trades. Furthermore the growing spot market for LNG provides opportunities for buyers and sellers who have the ability to be flexible on product specifications. As a result there is now considerable movement towards technical solutions for conditioning LNG on liquefaction and receiving ends.
WORLDWIDE NATURAL GAS SPECIFICATIONS
Natural gas specifications have several purposes, including corrosion prevention, avoiding liquid drop out in pipelines, and burner performance . The specifications for corrosion prevention limit concentrations of CO2, H2S, mercaptans or total sulfur. LNG facilities treat gas down to 50 ppmv CO2 to avoid freezing in the cryogenic processing unit, and therefore meet receiving end pipelin...