Utilising Integrated Natural Gas Liquids (NGL) and Nitrogen Rejection unit (NRU) technology in Qatar on the Barzan Gas Project

Abstract

Abstract Integrated Natural Gas Liquids/Nitrogen Rejection Unit (NGL/NRU) technology will be utilised for the first time in Qatar on the Barzan Gas Project, which is a joint venture project between Qatar Petroleum (QP) and ExxonMobil Barzan Limited. The North Field Reservoir, which supplies the Barzan Gas Project, contains a high content of inerts, e.g., nitrogen and helium. One challenge was to identify a technology to achieve the required specifications of the sales gas by rejecting the inerts from the feed gas. RasGas initiated a study to evaluate process licensors' capability to supply an integrated process design for recovering NGL and rejecting nitrogen for the Barzan Gas Project. The requirements are to recover the NGL product stream, containing 95% of the incoming ethane content and essentially 100 per cent of the propane and heavier (C3+) hydrocarbons. One primary component of the technology is to reject nitrogen from the gas stream to achieve an acceptable BTU content and Wobbe Index to meet QP sales gas specifications. To achieve the above requirements, Chart Energy and Chemicals Inc, as a technology licensor, demonstrated the ability to provide an integrated NGL/NRU licensed process with the following merits:Utilises a proven Brazed Aluminum Heat Exchanger (BAHX) supplier.Takes advantage of the available feed pressure to minimise overall energy consumption without requiring excessiveAluminum / surface area.Utilises high efficiency compression to meet final sales gas delivery requirements.Minimises footprint and plant congestion by installing equipment within sealed cold boxes.Provides a simple exchanger arrangement for easy conversion to various modes of operation. Introduction Natural gas is considered a valuable source of clean energy, as it emits lower quantities of greenhouse gases than other fossil fuels, and is also used as a feedstock to chemical plants. 'In addition, when comparing natural gas with other hydrocarbon energy sources, it is the most hydrogen-rich and has higher energy conversion efficiencies '(1). Natural gas consists primarily of methane as the main element, but it also contains considerable amounts of light and heavier hydrocarbons as well as contaminating compounds of carbon dioxide, nitogen, mercury, helium and hydrogen sulfide (CO2, N2, Hg, He, H2S, etc). Before transporting the gas over long distances to end users, it is necessary to remove all impurities to achieve the required product specifications.