Qatar LNG Terminal Flare Gas Reduction Project – JBOG

摘要

Qatar produces 77 million tonnes of LNG per annum, and is the largest provider of this clean energy in the world. The world's largest man made harbor in Ras Laffan City, located 80km north of Doha, has six LNG loading berths. During loading of the liquefied natural gas in the special LNG ships, a portion of the minus 160oC liquid boils off as it comes in contact with the warmer ship tank. This boiled off gas is currently being flared at the berth because there is no outlet for this low pressure gas. The average flow rate of the boil-off gas is 100 mmscfd, which has the potential to produce around 750MW of power. In line with Qatar's National Vision to produce and supply clean energy to the world, Qatar Petroleum and the Ministry of Environment decided to recover the flared gas at the LNG berths to the maximum extent practical. This intent gave birth to the Jetty Boil-off Gas Recovery Project in 2007. A Pre-FEED design had been done by RasGas, and the project was handed over to Qatargas in June 2007. The JBOG Project when fully implemented will save the emission of 1. 6 million tonnes of carbon dioxide into the atmosphere. One trillion cubic feet of gas will be saved for the State of Qatar over a period of 30 years. The design of this project encountered many challenges. 1. The gas is discharged from the ships at a pressure of less than 1 Bar Gauge Pressure (BarG). 2. The volume of the gas to be recovered is several times higher than at any other similar facility in the world. 3. Gas is discharged at -100oC, making all facilities cryogenic. 4. No provision had been made for space allocation at the harbor for Boil-off Gas Recovery facilities 5. Check valves and buckling pin valves' design and operating experience was not available for the large flow rates, low pressures and cryogenic temperatures. 6. No space was available at the berths to locate the compressors, as designed in the Pre FEED 7. Limited space available inside the port for JBOG main facilities. 8. Most of the facilities were going to be in brownfield areas, in close vicinity of live hydrocarbon-n carrying lines. 9. Lack of accurate and up to date as -built drawings for brownfield facilities. The Qatargas JBOG Project Management Team (PMT) brought in experts from the shareholders and addressed each of these challenges through innovation, extrapolation and a strong determination to succeed. The Front End Engineering Design (FEED) was awarded to Fluor Daniel in Houston, USA in late 2007. The FEED teams from Qatargas and Fluor produced a basic design package by Q3 2008. In the days of $150 per barrel oil prices, the cost estimate ballooned. Qatar Petroleum took a wise decision, and delayed the final investment decision by a year to let the markets cool down. During 2009, Qatargas JBOG PMT continued to work with Fluor on a Pre-EPC phase. In order to overcome the lack of as-built drawings, The PMT commissioned a "Laser Scan Survey" of all the brownfield areas through which the JBOG facilities were going to be installed. This scan produced digital images of high resolution, which were later incorporated into the 3D computer design model. This innovative approach saved millions of dollars, eliminated possible clashes and reduced the amount of time which otherwise would have been spent on manual surveys, drawings' review and rectification of clashes during construction. The critical path of the project ran through the procurement and delivery of the large Boil-off Gas Compressors. Qatargas and Fluor worked on fine tuning the design of the compressors during 2009, allowing the project the option to purchase the compressors within a month of the start of the detailed design phase. During 2009, the JBOG PMT managed to bring the Capital Expenditure (CapEx) of the project down significantly. This was a result of both scope changes and improved market conditions. The project owners, QP, ExxonMobil, Total, Shell and ConocoPhillips approved the investment decision for the JBOG Proj