Industries the world over require huge quantities of water for their production processes. In most cases they use freshwater sources such as rivers and reservoirs. In Saudi Arabia there are no natural perennial sources of freshwater, and the cost of producing desalinated water for cooling purposes would be prohibitive.
In both Jubail and Yanbu the lack of freshwater has been overcome by way of a masterful concept: using seawater for cooling purposes in a uncomplicated, once-through, non-contact system.
In Yanbu, about 60 percent of the seawater that passes through the pump station at the central utility complex is used to supply process cooling water for the industries.
The Yanbu facility is the largest pressurized cooling system in the world. Seawater enters the system at the main pumping station. Following filtration and chlorination, water flows to the industries through 27 kilometres of underground piping. Each industry siphons off the amount of water it needs. They return used seawater via gravity mains to an outfall channel that discharges into the Red Sea five kilometres southeast of the intake channel.
Strict control is exercised over the quality and temperature of the return water to minimize adverse environmental effects on coastal marine water quality and the sensitive coral reef ecosystem at the nearby barrier reef that protects part of the Yanbu port complex.
The seawater cooling system in Jubail consists of two adjacent pumping stations near the seashore and a distribution canal connected to industrial customers through an array of underground lateral pipes. Seawater pumped into the distribution canal flows by gravity to the industries and the return water flows by gravity back to the sea.
Seawater is drawn from the Arabian Gulf through dredged intake channels. It passes through coarse trash screens and fine trash screens at the pump stations and is chlorinated before it is pumped into the distribution canal. Each of the two pumping stations has fourteen pumps with a total installed capacity of 346 cubic meters per second, or 29.9 million cubic meters per day.
Chlorination plants attached to the two pump stations generate sodium hypochlorite which is used for disinfecting the seawater pumped into the canal by continuous dosing and shock dosing to control marine fouling. The pumping stations and distribution system are provided with cathodic protection to minimize corrosion.
The seawater canal system, which is twelve kilometres long, is divided by vertical concrete walls into three compartments. One compartment is used for supply and one for return flow. The third canal is normally used as an additional supply compartment but can be used for return flow if required.
The seawater intake and discharge canals are separated by the causeway to the Industrial port. It serves as a barrier between the two to eliminate the possibility of recirculation.
The seawater cooling facility will be extended to the new industrial city of Jubail 2 through a pump station at the west end of the canal system and a network of pressurized pipes.