Implementation of a top-down noise control strategy for a liquefied natural gas peak-shaving facility

摘要

There have been many previous noise-related studies on liquefied natural gas (LNG) facilities in the United States; however, noise control of these facilities using a top-down approach has not been explored in detail. Most studies have demonstrated noise compliance to applicable standards by focusing on a combination of treatments and specifications, with less consideration on control technology feasibility, ranking, and cost-effectiveness. The Federal Energy Regulatory Commission (FERC) prohibits natural gas facilities from emitting day-night noise levels in excess of 55 dB(A) (equivalent to 24-hr continuous level of 49 dB(A)) at nearby receivers. A case study was conducted to evaluate a top-down approach to reduce noise at a typical LNG peak-shaving facility under normal operating conditions, accounting for technical feasibility, control effectiveness, and cost implications. A modeling approach (International Organization for Standardization standard ISO 9613-2) was used to predict and evaluate the facility's noise reduction potential. The study found that the strategy could achieve feasible and environmentally effective reductions up to 11 dB(A) at 500 m from the facility by first identifying source groups with highest-emitting sources and then targeting major noise source contributors per group. This approach is cost-effective because the FERC noise goals can still be achieved by avoiding unnecessary control costs associated with lower-ranked sources. The study identified the following four source groups as the highest noise emitters: (1) liquefaction and instrument air, (2) boil-off gas (BOG) compression, (3) glycol water system (air coolers), and (4) pretreatment. Of all the treatments evaluated, installation of enhanced silencers for gas turbine (GT) package-as well as construction of an acoustical building for the BOG compressors and drivers-resulted in the greatest noise reduction at nearby receivers. The study notes that incremental treatment costs presented in this paper are approximate estimates that may vary depending on factors such as facility size and region. Implications: This study assessed potential noise reductions associated with implementing a top-down noise control strategy on a typical LNG peak-shaving facility. The study determined the top-down noise control strategy could achieve feasible and environmentally effective reductions up to 11 decibels at receivers within 500 m from the facility's center. As LNG suppliers need to support potential supply disruptions, some regions of the US, including New England and Gulf Coast with projected increase in LNG exports and growing needs from power sector, may find information in this study useful with regard to evaluating and prioritizing noise reduction potential of their LNG peak-shaving facilities.