PI – Dr. Luc Véchot
Co-PI – Dr. M. Sam Mannan
Co-PI – Dr. Tomasz Olewski
Natural gas (NG) has become one fast-growing source of energy, and Qatar is one of the largest producers and exporters of NG, and the largest exporter of Liquefied Natural Gas (LNG) in the world. Qatar exported 77 million metric tones of LNG in 2011, of which 47% to Asia Pacific and 42% to Europe. The total LNG export from Qatar is about three times larger than this of the next largest exporters, Malaysia and Indonesia, and 4 times larger than Australia’s one.
The worldwide LNG industry has had a relatively good safety record so far. However, this industry seems to continuously increase and thus brings new challenges and needs that require special attention. Therefore, it is crucial and strategic to conduct fundamental and applied research in areas related to LNG production, handling and transportation to increase their safety. Texas A&M University at Qatar in cooperation with the largest Qatar’s oil company, Qatar Petroleum (QP) aims to establish world class research and development at Qatar related to LNG process safety.
From 2004-2009, the Mary Kay O’Connor Process Safety Center (MKOPSC), Texas A&M University College Station, under the supervision of Dr. Sam Mannan, conducted, research on LNG safety with the support of BP Global Gas SPU. This research focused on vapor cloud control and mitigation for vapor dispersion and fire radiant heat reduction. It also included multiple field experiments and validation of computational fluid dynamics (CFD) simulations for vapor dispersion. The experimental work for this project was carried out at the Texas A&M University’s Brayton Fire Training Field (BFTF) between 2005 and 2009.
The work performed at TAMU-Qatar covers following areas:
• Preparation of the medium and large scale experiments at Ras Laffan Emergency and Safety College (RLESC) and design of the TP-5 LNG testing facility.
Since 2009, the BP LNG Project at TAMU-Qatar has received an outstanding technical and financial support from QP through the design and construction of TP-5 LNG testing facility and the associated adjacent facilities that will be used in this research program. With the knowledge provided by TAMU-Qatar, QP kindly invested in transforming a “simple” LNG training facility for fire fighters into a “state of the art” research facility. This facility includes three LNG burning pits of which one will be used to perform our experiments. This pit received 100 thermocouples and 13 heat flux plates embedded in the concrete at two different levels, which enables this pit to monitor temperature and heat flux profile in a concrete and which can be used to determine temperature-dependent thermal properties of concrete. Additional instrumentation used in this test facility includes capacitance-based liquid cryogen level sensor, bubbler systems with differential pressure transmitters for cryogenic liquid level measurement (redundancy in level measurement by different method), various thermocouples to monitor pool spreading and level, and to measure temperature of the liquid, the cloud and the fire; methane gas detectors for LNG gas concentration tracking, ultrasonic anemometers for air movement and turbulences measurement, ultrasonic flow meter for cryogenic liquid flow, hydrocarbon cameras and ordinary video recorders for hydrocarbon vapor mapping, radiometers for measurement of thermal radiation from fires; and two weather stations at 2 and 10 meters elevation.
The scale of prepared experiments will allow the measurement of the pool vaporization and dispersion process on concrete or water as well as the heat transfer from the concrete to the LNG.
• The studies of the effectiveness of mitigation measures for controlling LNG vaporization and dispersion.
This part of the project aims to study the use of water curtains, vapour fences and high expansion foam as mitigation methods to limit the vapour generation and dispersion of the NG vapour generated after an accidental release of LNG.
• Comprehensive modeling of LNG vapor cloud generation.
Numerous studies have been performed on the modeling of the vapor cloud dispersion after a release of LNG, and although there are still many aspects yet to be discovered and improved, many models have been developed and, more importantly, successfully validated against available experimental data. However, the phenomena associated with the vapor cloud formation and the associated source term models have received much less attention despite their critical importance in the prediction of the consequences of a spill. Indeed, the result of a LNG vapor cloud dispersion simulation is highly sensitive to and dependent on the accuracy of the vapor generation rate calculated from a source term model. The results from the source term modeling will in turn have a significant effect on the predicted exclusion zones for LNG facilities. Unfortunately, the modeling of the spill of LNG is very complex and may include various phenomena such as jet flow, flashing, droplet formation and vaporization, pool formation, spreading, boiling and evaporation, depending on the specific conditions of the release. The aim of this project is to focus on LNG liquid pool formation, spreading, boiling and evaporation.
Significant efforts are still to be done in the development and validation of a comprehensive source term model able to describe the physics behind the spreading and vaporization of a LNG pool. One of the reasons behind the surprisingly insufficient amount of knowledge on source term models is the lack of a complete set of good quality experimental data that can be used for their development and validation. This is currently the priority area of our project.
• CFD modeling of LNG vapor cloud dispersion.
A part of this project consists of describing dispersion of a generated LNG vapour in air with consequent mixing and warming in complex geometries using CFD models. All past and future experiments are planned so they result in the creation of sets of experiment data that can be used to validate CFD simulations. The dispersion modelling work is being performed using Commercial Computational Fluid Dynamics (CFD) codes, FLUENT and FLACS with associated 3D visualisation using an Immersive Visualization Facility (IVF) at TAMU-QATAR.
For more info contact: Dr Tomasz Olewski at email address email@example.com
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