LNG TURBOMACHINERY

TutorialThe International Liquefied Natural Gas (LNG) trade is expanding rapidly. Projects are being proposed worldwide to meet the industry forecasted growth rate of 12% by the end of the decade. LNG train designs in the coming years appear to fall within three classes, having nominal capacities of approximately 3.5, 5.0 and 8.0 MTPA (Million Tons Per Annum). These designs may co-exist in the coming years, as individual projects choose designs, which closely match their gas supplies, sales, and other logistical and economic constraints. The most critical components of a LNG liquefaction facility are the refrigeration compressors and their drivers which represent a significant expense and strongly influence overall plant performance and production efficiency. The refrigeration compressors themselves are challenging to design due to high Mach numbers, large volume flows, low inlet temperatures and complex sidestream flows. Drivers for these plants include gas turbines that range in size from 30 MW units to large Frame 9E gas turbines. Aeroderivative engines have also been recently introduced. This paper covers the design, application and implementation considerations pertaining to LNG plant drivers and compressors. The paper does not focus on any particular LNG process but addresses turbomachinery design and application aspects that are common to all processes. Topics cover key technical design issues and complexities involved in the turbomachinery selection, aeromechanical design, testing and implementation. The paper attempts to highlight the practical design compromises that have to be made to obtain a robust solution from a mechanical and aerodynamic standpoint

Silver Nanoparticle-Decorated Shape-Memory Polystyrene Sheets as Highly Sensitive Surface-Enhanced Raman Scattering Substrates with a Thermally Inducible Hot Spot Effect

In this study, an active surface-enhanced Raman scattering (SERS) substrate with a thermally inducible hot spot effect for sensitive measurement of Raman-active molecules was successfully fabricated from silver nanoparticle (AgNP)-decorated shape-memory polystyrene (SMP) sheets. To prepare the SERS substrate, SMP sheets were first pretreated with <i>n</i>-octylamine for effective decoration with AgNPs. By varying the formulation and condition of the reduction reaction, AgNP-decorated SMP (Ag@SMP) substrates were successfully prepared with optimized particle gaps to produce inducible hot spot effects on thermal shrink. High-quality SERS spectra were easily obtained with enhancement factors higher than 10⁸ by probing with aromatic thiols. Several Ag@SMP substrates produced under different reaction conditions were explored for the creation of inducible hot spot effects. The results indicated that AgNP spacing is crucial for strong hot spot effects. The suitability of Ag@SMP substrates for quantification was also evaluated according to the detection of adenine. Results confirmed that prepared Ag@SMP substrates were highly suitable for quantitative analysis because they yielded an estimated limit of detection as low as 120 pg/cm², a linear range of up to 7 ng/cm², and a regression coefficient (<i>R</i>²) of 0.9959. Ag@SMP substrates were highly reproducible; the average relative standard deviation for all measurements was less than 10%