How the Cycle Works

The ORC plant produces electricity (and where relevant/needed low-temperature heat) through a closed-loop thermodynamic cycle that follows principles similar to traditional steam (Rankine cycle) facilities, though with a low vapor-point refrigerant used as the working fluid instead of water. The by-product, low-temperature heat not consumed in the electricity-generation process is discharged to the atmosphere through air or water-based condensers.

 

In the ORC process (designed as a closed cycle), the organic working medium is pre-heated in a recuperator/heat exchanger (Area 1), then vaporized in the evaporator (Area 2) heat exchanger through contact with heat from the original heat source (an interposing hot oil loop that delivers thermal energy from the gas turbine exhaust to the ORC). The high-temperature, high-pressure vapor generated from this process is expanded in a two-stage typical axial turbine(Area 3) that drives a generator(Area 4).

After leaving the turbine, the organic working medium (still in the vapor phase) passes through the recuperator (Area 5)that serves two functions, both of which improve total system efficiency: 1) it pre-heats the incoming organic liquid prior to vaporization, and 2) this “heat dump” lowers the parasitic duty of the cooling circuit.(Area 6)

After exiting the cooling/condensing circuit, the working medium is pumped back to the appropriate pressure(Area 7) and is then preheated by internal heat exchange in the recuperator(Area 5).

A customizable logic control and remote monitoring system makes the ORC plant fully automatic in both normal and shutdown operating conditions. As a result, onsite operation/supervision is minimized and all facets of the operation can be outsourced including break-fix, routine, and major maintenance.