The evaporator foundation of the Barka power and desalination project is depicted above.
Click here to enlarge imageThe Barka project will be developed in two separate phases. The first phase, now under development, will result in a net power output of 427.36 mW and 6.6 million Imperial gallons of water per day (migd). Two gas turbine generators of a gross power output of 117.36 mW plus one steam turbine generator of 222 mW-rated output will generate power in the first phase.
The steam downstream of the steam turbine generators is passed to the desalination yard where three multi-stage flash desalination plants will each provide a capacity of 6.6 migd. The V94.2 model gas turbines provided by Siemens of Germany are designed for duel fuel-firing, using natural gas and oil. The system is equipped with downstream heat recovery steam generators that have a provision for supplementary firing to cater for operational flexibility.
The back pressure steam turbine provides for total steam bypass and is fed with steam having the following parameters: flow of 121 kg/sec, 77 bar pressure and 541 °C. Each evaporator can reach a performance ratio of 7.7 in fouled conditions. Auxiliary equipment and seawater intake are designed for future project extension.
The intake structures will be of a velocity cap type set at five metres below the Lowest Astronomical Tide (LAT) 1,200 metres into the sea. A series of 2.2-m-diameter intake pipes, buried in the sea bed with a minimum cover of 2.5 m, will be installed between the intakes and on-shore seawater pump house - a monolithic concrete structure incorporating a stilling basin, six bar screens, six motorised band screens, a pump bay and 16 pump chambers.
Each main seawater supply pump has its own pump chamber, except for firefighting and auxiliary pumps fed via a common forebay. Each chamber can be isolated by stop gates for maintenance to allow the dewatering of each individual sump. Pumps bays are sized with a nominal approach velocity of not more than 0.25 m/s in accordance to Hydraulic Institute standards. The Hydraulic Institute is located in Parsippany, New Jersey, USA.
The stilling bay will be divided into two separate bays for Phase 1 (427 mW power and 20 migd desalination plants) and Phase 2, in which the plants will be expanded.
The outfall facilities include 2.5-metres-diameter sub-sea discharge pipelines, each 700-metres-long and similar in design to the intake system, and a discharge sump. An electrolytic chlorination plant using seawater as raw make-up feedstock will also be constructed to inhibit biological growth and fouling of the entire seawater systems.
Design review