Decarbonisation Technology - February 2025 Issue

ORC

ORC evaporator

Turbine

Cooled NCG to ATM

Hot steam + NCG

Generator

K O- D rum with NCG cooler

Su b cooled condensate

Hot steam condensate

Recuperator

ORC preheaters

Stripping column

Cooling tower

Cooling water

Condenser

Pot

CW pump

Condensate return

ORC pump

Figure 3 Layout with ORC WHR integration in the chemical process with overhead condensers

design and supply of ORC systems. In 2009, the company introduced the Radial Outflow Turbine (ROT) for ORC systems (see Figure 4 ). The unique configuration of Exergy’s ROT allows for efficient conversion of thermal energy into mechanical power thanks to several technical features: • Increased volumetric flow during expansion. • Reduced leakage and rotor friction due to straight blades and radial design. • Multiple inlets on the same rotor disk at different pressures. • Up to nine stages on a single rotor disk, allowing for higher efficiency. • Optimised pressure gradient distribution to limit vortex formation and fluid dynamic losses. • Flexibility in choosing the cycle pressure with fewer technological limitations. • Patented mechanical group, easily removable

at low and medium-high temperatures or for small applications gives some advantages over a steam cycle, including: • Higher efficiency and flexibility in operations, even at partial loads. • Automated operations, which avoid dedicated trained personnel to run them. • Low, easy maintenance and a long plant lifecycle. • Enabling operation without water consumption by choosing an air-cooled condenser. These characteristics make ORC technology a flexible, customisable solution suitable for retrofitting existing sites or greenfield installations. In the chemical sector, ORC systems can recover waste heat from distillation processes by harnessing available heat from the overhead vapour of the distillation column and the non- condensable gas (NCG) stream from stripping columns. In these cases, the ORC system serves a dual function, providing significant benefits: it replaces the conventional condensers at the top of the column while simultaneously generating electrical energy (see Figures 2 and 3 ). The process steam, NCG flow, and organic working fluid never come into contact, avoiding the potential issue of process steam and condensate contamination. ORC waste heat recovery system with radial outflow turbine Exergy International is a global provider of clean energy technologies and an expert in the

Figure 4 Exergy’s Radial Outflow Turbine