The Sohar Power and Desalination Plant utilizes Gas Turbine technology for power generation and Multi-Stage Flash Desalination technology for Seawater Desalination. Natural gas is the primary fuel.
The essence of a combined cycle unit like Sohar Power plant is an attempt to extract the maximum possible output from a scarce resource, natural gas.
The technology consists of utilizing the high grade heat from the exhaust of the Gas Turbine to generate high pressure steam, which in turn powers the steam turbine. Through that heat recovery, approximately 50% additional power can be generated from the steam turbine without using any additional fuel.
The Heat Recovery Steam Generators (HRSG) generate steam at two pressure levels and are equipped with supplementary firing burners. Supplementary firing in the HRSG utilizes the excess oxygen available in the gas turbine exhaust, thereby adding heat capacity. Reduction of excess oxygen in the exhaust from the HRSG has the effect of improving the efficiency of the HRSG unit.
In addition to increase in efficiency of the HRSG unit, additional heating added by supplementary firing enables the HRSG to generate high pressure/high temperature steam and low pressure steam. Generation of steam at two pressure levels at Sohar Power plant helps reduce the temperature of the exhaust from the HRSG thereby further enhancing the efficiency of the unit:
- The high pressure steam allows the steam turbine to operate at high efficiency levels; and
- The low pressure steam is utilized for the generation of distillate water from seawater.
The Sohar Power plant is therefore a Cogeneration – Combined Cycle plant.
The low pressure steam generated by the HRSG, utilizing the exhaust gases of the Gas Turbines acts as the motive force for the generation of water. Further, the steam turbine is an extraction condensing type unit, meaning that residual steam is extracted from the steam turbine to be used in the desalination units, which further enhances the efficiency of the system multi-fold. Condensing this extracted steam (and the steam generated in the low pressure section of the HRSG) in the MSF Units utilizes heat to the fullest extent to evaporate seawater in the MSF Units.
This is a combination of efficiency and environmental friendliness that reinforces one another.
The gas turbines are equipped with low NOx combustors to ensure that Omani and international environmental norms are strictly adhered to.
During the process of distillate production, potable water production and steam production in the HRSG, chemicals are utilized for various purposes. Some of these chemicals are also drained out periodically. Such effluents are all collected and treated so that all discharges from the plant are harmless to the environment.
The potable water supplied by Sohar Power strictly meets the Omani Water Standards specified in the PWPA.