buletinul institutului politehnic din iaşi - Universitatea Tehnică ...

Bul. Inst. Polit. Iaşi, t. LVIII (LXII), f. 4, 2012 15
Ethane power expander was assumed 0.89, while isentropic efficiency of the
Ethane low pressure expander (which drives Ethane pump) 0.83. Isentropic
efficiency of the Ethane pump is assumed to be equal to 0.86; while the
efficiency of the Electric generator and mechanical efficiency of the system are
respectively equal to 0.94 and 0.91. Ethane flow rate is 35.4 kg/s. LNG flow
rate to be regasified is 62.7 kg/s, when the modular unit operates 9 months/year
it regasifies 2 × 10 9 Stm 3 /year.
For the case study analysed for the modular unit proposed the significant
Energetic efficiency parameters above defined have the following
values:COPEthCP= 161% and COPReg= 201%, while the Exergy efficiency as
above defined have the values: εEthCP= 35% and εReg= 64%.
It is worth of mention that ε would be a 42% if the same Regasification
Plant of Fig. 2 regasifies LNG at a pressure below that pseudo-critical, as
proposed in eastern countries. Moreover, ε would be a 48% for a simple
regasification plant based on Open Rack technology working at hypercritical
pressure and a 32% when the same works at a pressure below that of the
pseudo-critical state of LNG. Note that, the exergy “recovered” in both the last
two cases is only that of the natural gas regasified.
The simulation analysis for the whole regasification facility, represented
in Fig. 2, gives the main results reported in Fig. 8, which shows main results
obtained performing the Exergy analysis of each part of the process.
The input exergy is represented in Fig. 8 by the exergy of the stream of
LNG to be regasified. This quantity includes the exergy of cold contained in the
LNG stream to be regasified and the LNG liquid pumping power.
The Dead State parameters used in the Exergy analysis are: P0= 1 atm
and T0 = 15 °C (288.15 K).
The flow rate of LNG to be regasified in the plant is 62.7 kg/s.
kW.
Fig. 8 – Main results of exergetic analysis (La Rocca, 2010).
The exergy of LNG at inlet in the regasification facility (ELNG) is 69,666