|
Abstract
|
In recent years, the use of liquefied biogas in the power plant for peak shaving and transportation indus-
tries from an environmental and economic perspective has been considered. Simultaneous design of
biogas purification and liquefaction processes reduces the number of equipment required and energy
consumption. In this paper, a novel purification and liquefaction integrated structure includes a biogas
upgrading process by cryogenic separation and amine scrubbing methods and a biomethane liquefaction
cycle based on the mixed fluid cascade. In this integrated structure, 2.393 kg/s biogas and 2730 kW power
are consumed and 0.5387 kg/s bioLNG, 0.1280 kg/s bioCH4, and 0.2102 kg/s liquid bioCO2 are produced
along with 1.625 kg/s hot water. The required cooling of cryogenic biogas upgrading and required heat for
the biogas upgrading by amine scrubbing method are provided through mixed refrigerant cascade cycles
and waste heat in the integrated structure, respectively. The total thermal energy and exergy efficiencies
are 73.11 % and 72.58 %, respectively. The specific power consumption and coefficient of performance of
the mixed fluid cascade cycle are calculated to be 0.4761 kW h/kg bioLNG and 3.675, respectively. The
economic analysis illustrates that the prime cost of product and return period are 0.2399 US$/kg LNG
and 2.122 years, respectively.
|