Cold utilization system, energy system provided with cold utilization system, and method for utilizing cold utilization system

摘要

The present invention provides a cold utilization system in which the efficiency of utilizing the cold exergy of liquefied gas can be improved while gas delivery pressure in the outlet side of a secondary expansion turbine, which is the supercritical-pressure power generation (LSG) of a cryogenic fluid, is freely controlled. The LSG is provided with a pressure-increasing pump for increasing the pressure of a low-temperature liquefied gas to a prescribed pressure equal to or greater than the critical pressure thereof while the liquefied gas remains in liquid form, a Rankine-cycle primary power generation device, and a direct-expansion secondary power generation device. To effectively utilize the cold exergy of the liquefied gas, it is more efficient to utilize the cold exergy as pressure exergy than as temperature exergy. The LSG, which is for converting cold exergy more dominantly to pressure exergy, can determine optimal operating conditions that will yield the highest conversion efficiency, according to the composition of the liquefied gas, the temperature of the heating source, and the gas delivery pressure. In a case of maximum power generation with a low gas delivery pressure, as one example, the power generation intensity is approximately 486 (kJ/kg) (135 (kWh/ton)) in values corrected for actual machinery, and an equivalent of approximately 54% of the cold energy can be recovered as electric power.