Shell-and-Tube Heat Exchangers for Exhaust Gas Heat Recovery
Maximize energy efficiency by recovering heat from exhaust gases
LAI's shell-and-tube heat exchanger is essential for maximizing the energy efficiency of cogeneration plants. Exhaust gases from internal combustion engines leave the combustion chamber at temperatures typically ranging from 400 to 550 °C—a considerable amount of thermal energy that, if not recovered, is lost to the atmosphere through the exhaust stack.
Our heat exchanger captures these hot gases and transfers their energy to a secondary fluid—hot water, saturated steam or diathermic oil—which can then be used in industrial processes, district heating networks, greenhouses or absorption cooling systems. In the most efficient installations, heat recovery from the exhaust gases brings the cogeneration unit’s overall energy efficiency—calculated as the sum of electrical and thermal efficiency—to between 80% and 90%.
We manufacture shell-and-tube heat exchangers with carbon steel or stainless-steel shells and AISI 316 stainless-steel tube bundles, ensuring resistance to corrosion from acidic condensates that may form in exhaust gases containing sulfur. Our technical department sizes the heat-transfer surface based on gas mass flow rate, inlet temperature and the required temperature differential in the secondary fluid, with the aim of maximizing energy recovery while keeping the exhaust outlet temperature above the acid dew point to prevent condensation in the stack.
Each heat exchanger is fitted with a bypass system with a motorized three-way valve, which allows the outlet fluid temperature to be adjusted to meet downstream process requirements, or the heat exchanger to be bypassed while the engine is serviced without interrupting plant operation. The unit is manufactured and tested entirely in our workshop in Cerreto Guidi (FI), where its hydraulic tightness and thermal performance are checked before shipment.
On request, the heat exchanger can be fitted with a low-temperature economizer to recover residual sensible heat from cool exhaust gases, or an acid vapor condensation system to recover latent heat. All LAI heat exchangers come with complete technical documentation and CE certification in accordance with the Pressure Equipment Directive (PED) 2014/68/EU.
The system can be integrated with the LAI automation panel for continuous temperature monitoring and automatic bypass control.
