Director of Gas Processing
14:00 - 14:30
Thursday, 19 September 2019
T3.9 Advances in Freeze Component Removal Technology for LNG Plants
The Benz-FreeSM technology is a flexible and efficient cryogenic heavy hydrocarbon removal process that is developed by McDermott’s Lummus Technology for LNG applications to accommodate a wide range of feed gas pressure, composition, richness and freeze component concentrations. Some aromatic and cyclic hydrocarbons such as benzene have relatively high melting points and low solubility in liquid methane. Presence of these components at even low ppm concentrations in the natural gas could result in operational problems due to freezing of these components at cryogenic temperatures. The deep reduction in troublesome heavy hydrocarbon components may be achieved by an upstream turbo-expander based NGL/LPG extraction technologies, a scrub column integrated to liquefaction process, or an upstream temperature swing adsorption technology. These technologies however have limited ranges of applications where they are economical. As examples, turbo-expander based technology for rich feed gases, scrub column for moderate to rich feed gases, temperature swing adsorption for lean feed gases with relatively low amount of freeze components. As the global LNG market is evolving and more challenging natural gas streams are processed, the need for a flexible and cost effective freeze component removal technology capable of accommodating a wide-range of feed compositions is increasing.
Lummus’ Benz-FreeSM technology is capable of handling feed gases with a very wide range of hydrocarbon compositions. As an upstream pretreatment plant with the capability to produce refrigerant make-up for the LNG process, Benz-Free can economically reduce 100 to 3000 ppm of benzene and other freeze components to less than 1 ppm from feed streams. This is achieved by controlled cooling and partial condensation of the feed stream with targeted injection of propane and butane condensed from the feed gas to maintain a safe margin to solubility limits. In this paper, example applications of this new technology for lean feed gas compositions are compared against conventional integrated scrub-column configuration for feed gas flexibility and impact on LNG production. Development of high efficiency cryogenic two-phase separator internals is also discussed with an application example for a new baseload LNG facility.