Performance analysis of a low pressure discharge thermal energy combined desalination unit

• The LP-DTECD is a new steam recovery system.
• The LP-DTECD cogenerates water and power without any external fossil energy.
• It utilises an eductor to generate vacuum in the single desalinator and save the valuable steam.
• This system is a good option for coupling to a plant where discharge steam emits to the environment.
• The proposed system is a well economic and energy efficient choice.

This study proposes a novel steam recovery cogeneration system, which is based on the low temperature thermal desalination (LTTD) system and named Low Pressure-Discharge Thermal Energy Combined Desalination (LP-DTECD). This technology includes open water and closed power cycles. Utilizing discharged thermal energy from a waste steam in an ammonia plant to cogenerate water and power is one significant of this system. Also, using an eductor instead of a steam jet ejector or a rotary vacuum pump to save valuable steam and make a convenient operation is another merit of the proposed technology. The mixture of NH3–H2O is utilised as working fluid for its closed Rankin cycle. A 28% improvement in the exergy flow was noted as in comparison with the energy waste of the base case. Utilising the LP-DTECD system is economical and demonstrates an improved CO2 emission reduction by 7%.