Organic Rankine Cycle has proven to be ideally suited to exhaust heat recovery from both engines and gas turbines in low-medium size range. 

Recovering exhaust heat from gas turbines and internal combustion engines is an easy way to optimise efficiency and performance whilst at the same time reducing the environmental impact of power generation plants widely employed for processing and refining in Oil & Gas sector and in the electricity production field. 

When it comes to available technologies to recover waste heat from these sources the market offers two commercial solutions: steam technologies and Organic Rankine Cycle systems. WHR plants employing steam offer advantages in both efficiency and security for plant operation but they lack flexibility and require more maintenance when compared to ORC. 

Organic Rankine Cycle (ORC) has proven to be ideally suited to exhaust heat recovery from both engines and gas turbines in low-medium size range. This application counts nowadays the 65% of the total ORC power plants installed or under construction worldwide (2017 figures).

EXERGY ORC waste heat recovery systems employing the revolutionary Radial Outflow Turbine offer high efficiency for modern low temperature engines in addition to all the advantages of ORC vs steam:

exergy heat industrial power graph
SIMPLE PLANT DESIGN
SIMPLE PLANT DESIGN
  • Competitive capital cost leading to fast payback
COMPACT AND AUTOMATED SOLUTION
COMPACT AND AUTOMATED SOLUTION
  • No need of operators thus lower running cost
FLEXIBILIY OF PLACEMENT AWAY FROM THE HEAT SOURCE IF REQUIRED
FLEXIBILIY OF PLACEMENT AWAY FROM THE HEAT SOURCE IF REQUIRED
  • More freedom of placement according to space
  • Available and production process requirements
FAST START UP AND SHUT DOWN
FAST START UP AND SHUT DOWN
  • High operating hours
  • Easy maintenance
NO WATER TREATMENT PLANT OR MAKE UP WATER REQUIRED
NO WATER TREATMENT PLANT OR MAKE UP WATER REQUIRED
  • No need for water consumption and higher
  • Higher Sustainability
HIGH EFFICENCY (UP TO 30%) AT A VARIETY OF OPERATING TEMPERATURES AND LOADS
HIGH EFFICENCY (UP TO 30%) AT A VARIETY OF OPERATING TEMPERATURES AND LOADS
  • Possibility to exploit the maximum energy available from the process

EXAMPLE of performance and payback time from 7 gas engines:

7 GAS ENGINES MOD. ROLLS ROYCE B35:40 V20AG2 | OPERATIONAL LOAD 100% | FUEL: NATURAL GAS

50,400 kg/h 380 C° 140 C° 25.3 MWT 5.5 MWe 6 years 3 years less than 2 years
Exhaust gas mass flow rate (each engine) Exhaust gas temperature WHR outlet exhaust temperature Recovered Thermal Power Generated Power Payback time (50USD/MWh) Payback time (100USD/MWh) Payback time (200USD/MWh)

EXERGY’s ORC single units power size range between 1 MW to 20 MWe.

Portfolio
Portfolio
6 MWe
Plants
Plants
10
OIL SAVED toe/y
OIL SAVED toe/y
1650
CO2 SAVED t/y
CO2 SAVED t/y
5000
Applications:
GAS ENGINE
GAS ENGINE
DIESEL ENGINE
DIESEL ENGINE
BIOGAS ENGINE
BIOGAS ENGINE
GAS TURBINES FOR POWER
GAS TURBINES FOR POWER
GAS TURBINES FOR MECHANICAL DRIVE
GAS TURBINES FOR MECHANICAL DRIVE

WASTE HEAT RECOVERY CYCLE FROM GAS TURBINES OR ENGINE

The heat recovery system extracts the thermal power from the exhaust of the engines or turbines to feed the ORC module via an intermediate loop of heat recovery. The intermediate fluid, which is usually oil, transfers heat to the organic fluid in the ORC evaporator, where the organic fluid vaporizes. The vaporized fluid then flows to the turbine. Here the vapour expands causing the turbine to spin and creating electricity in the generator. The vaporized organic fluid then continues through the cycle to the condenser where it transforms into liquid, ready to be processed by the pump before beginning the cycle again.

The conventional ORC solution as described above employs an intermediate heat transfer loop that offers some advantages over steam technology but leads to a more complex plant design and requires
the use of flammable fluids at the interface with the hot flue gas which instead is not necessary with steam technology. 

EXERGY’s R&D activities on WHR systems are today focusing to give an answer to this gap with an innovative ORC configuration (patent pending) combining the benefits of steam technology and ORC technology. 

exergy heat industrial power orc cycle