- Application
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- HEAT RECOVERY FROM POWER STATION
Cold Energy Recovery
During the production phase, natural gas (NG) is compressed and chilled to a liquid state (liquefied natural gas, LNG) to reduce volume and thereby streamline transportation. To be liquefied, natural gas must be cooled to approximately -160°C at 1 atm. After transport, LNG is pumped and regasified, exploiting the heat input provided by a thermal source prior to injection in the national grid.
Common technologies used for LNG regasification mainly comprise open-rack vaporizers (using seawater as a thermal source) and submerged combustion vaporizers (with NG as a thermal source). Alternatives include intermediate fluid vaporizers and ambient air vaporizers.
COLD ENERGY UTILIZATION ACCOUNTS FOR LESS THAN 1% OF ITS POTENTIAL
None of the regasification technologies exploit the cold energy available in LNG, which is approximately 740 kJ/kg of LNG (-160°C to 0°C at 80 bara).Â
ORC cold energy plants are an efficient way to recover energy from the regasification of liquefied natural gas and decarbonize the Oil & Gas sector.
The Exergy Cold Energy Plant (CEP) is an efficient system based on ORC technology which regasifies liquefied natural gas and converts the heat absorbed from sea water into electricity by recovering the valuable exergy content of LNG. The CEP system designed by Exergy achieves high efficiency thanks to use of the Exergy Radial Outflow Turbine (ROT), combined with the multilevel condensation cycle.Â
The advantages of a multilevel condensation cycle coupled with the Exergy ROT are:
1
SUITABILITY FOR THE USE OF PROPANE AS WORKING FLUID
Low cost and high availability
Low global warming potential
Already in use in the Intermediate Fluid Vaporizer
2
HIGHER PERFORMANCE COMPARED TO SINGLE-LEVEL CONDENSATION AT THE SAME REGASIFICATION CAPACITY
Maximized revenue from electricity production
3
THE BEARING AND SHAFT OF THE TURBINE ARE LOCATED IN THE NON-CRYOGENIC PROCESS AREA
No need for exotic materials
The mechanical group is never exposed to cryogenic temperatures
The CEP is a low-maintenance and cost-effective solution that can be efficiently applied in the LNG industry to:
1
SIMPLE PLANT DESIGN
Competitive capital cost leading to fast payback
2
COMPACT AND AUTOMATED SOLUTION
No need for operators, which reduces operating costs
3
FLEXIBILITY OF PLACEMENT AWAY FROM THE HEAT SOURCE IF REQUIRED
More freedom of placement based on available space and production process requirements
4
FAST START UP AND SHUTDOWN
High availability in operation
Easy maintenance
3
FLEXIBILITY OF PLACEMENT AWAY FROM THE HEAT SOURCE IF REQUIRED
More freedom of placement based on available space and production process requirements
4
FAST START UP AND SHUTDOWN
High availability in operation
Easy maintenance
5
NO WATER TREATMENT PLANT OR MAKEUP WATER REQUIRED
No need for water consumption
Higher sustainability
6
HIGH EFFICIENCY (UP TO 40%) AT A VARIETY OF OPERATING TEMPERATURES AND LOADS
Possibility to exploit the maximum energy available from the process
1
SIMPLE PLANT DESIGN
Competitive capital cost leading to fast payback
2
COMPACT AND AUTOMATED SOLUTION
No need for operators, which reduces operating costs
3
FLEXIBILITY OF PLACEMENT AWAY FROM THE HEAT SOURCE IF REQUIRED
More freedom of placement based on available space and production process requirements
4
FAST START UP AND SHUTDOWN
High availability in operation
Easy maintenance
3
FLEXIBILITY OF PLACEMENT AWAY FROM THE HEAT SOURCE IF REQUIRED
More freedom of placement based on available space and production process requirements
4
FAST START UP AND SHUTDOWN
High availability in operation
Easy maintenance
5
NO WATER TREATMENT PLANT OR MAKEUP WATER REQUIRED
No need for water consumption
Higher sustainability
6
HIGH EFFICIENCY (UP TO 40%) AT A VARIETY OF OPERATING TEMPERATURES AND LOADS
Possibility to exploit the maximum energy available from the process
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How an ORC cold energy plant works
The evaporator exchanges heat between sea water and the ORC working fluid. Working fluid vapor expands in the turbine, producing power in the generator.Â
A multilevel condenser regasifies the LNG by releasing the waste heat from the CEP cycle.
The pump provides the pressure needed for the cycle
