Ras Az Zawr is a purpose-built industrial city on the Arabian Gulf coast in a region that is one of the richest natural and mineral resources areas in the world. One of the key activities within the Ras Az Zawr zone is processing of phosphates for use in fertilisers. This entails phosphate concentrate being processed in a fertiliser production facility consisting of phosphoric acid, sulphuric acid, ammonia, DAP granulation as well as co-generation and desalination plants.
Outotec currently accounts for over a third of the entire global sulphuric acid capacity, with more than 600 plants installed worldwide, and was successful in winning the contract for the sulphuric acid part of this project, the largest production facility of its type to be constructed in one phase in the world. The total investment in the facility, which includes three sulphuric acid plants, is approximately 240 million US$. When complete, the three plants will have a total production capacity of 13,500 tons of sulphuric acid per day.
Due to the remoteness of Ras Az Zawr, and the possibility of issues with multiple suppliers should problems occur, Outotec insisted on a single supplier for each element of the sulphuric acid project. “We didn‘t have a previous track record with Outotec in Germany, but we had already done business with the company – successfully – in Brazil and Australia, although there was no specific reference to this type of plant”, comments Andreas Schulte Mesum, WEG Director European High Voltage Solutions. “However, our single contract for project management, allied with the single-supplier argument, was definitely the key to our winning the bid.”
The project demanded products tailored to the challenging conditions prevailing in the Arabian Gulf. The outdoor environment, the remote location of the conveying area and the extreme performance requirements called for motors and drives offering the maximum possible efficiency, reliability and service life. All in all, WEG delivered 21 MV motors, including six slip ring-type MAW710 (5200 kW, 4-p, 13.8 kV, 60 Hz), six MGW450 asynchronous motors (1400 kW, 2-p, 4.16 kV, 60 Hz) and nine HGF400 asynchronous motors (620 kW, 6-p, 4.16 kV, 60 Hz). In addition to the motors and starters, a total of 24 WEG transformers are used to supply and condition electricity for all kinds of equipment across the whole sulphuric acid plant and six liquid rheostat starters.
The MGW and HGF type motors are used in the boiler feed water and circulation pumps of the sulphuric acid plant. The higher power (5200 kW) MAW units are slip ring motors that drive the plant’s main blowers. WEG decided to use slip ring motors controlled by liquid rheostat starters for this application as the blower inertia was high and the starting current was an issue. The advantage of starting the main blowers in this way is that the customer can easily control the starting current while at the same time handling the very high torques involved.
The M-Line is the core product for the oil and gas industries. Designed for larger-scale applications in the power range up to 30 MW, these motors are extremely reliable even under the most adverse operating conditions – both onshore and offshore. All models have classifications for potentially explosive atmospheres in compliance with Atex directives and are used in many applications worldwide. The welded steel structure of the motor frames is optimally suited for Ex p applications as well as for Ex n with pre-start rinsing for zones 1 and 2 in conjunction with low leakage rates. The internal flushing lines in the motor frame ensure a rapid and efficient flushing cycle, so that the costs for purge air and shielding gas are kept to a minimum. They additionally enable fast start-up times.
The H-Line motors can be supplied in Ex n and Ex e protection versions for smaller-scale applications. They cover medium voltage configurations in the range up to 4 MW as well as voltages up to 11,000 V (50 or 60 Hz). Available in IEC sizes 315 to 630, these motors are compact and extremely reliable machines with robust cast frames and high corrosion resistance.
The transformers used in Ras Az Zawr supply a variety of electrical components throughout the sulphuric acid plant with the required voltage, including medium voltage motors from WEG. They are also designed to withstand the harshest operating conditions in hydroelectric power plants, desalination plants, oil and gas installations, mines, offshore facilities, etc. all over the world.
Package of key products
WEG supported the project management stage at Ras Az Zawr, managing three different suppliers and coordinating with Outotec to ensure that several technical modifications requested by the main contractor were actioned promptly and with the necessary level of customer support. Now that the project has reached the start-up phase, WEG engineers are once again heavily involved, their coordination expertise and technical support being much in demand. This major global flagship project in Ras Az Zawr has demonstrated the benefits for plant operators, especially in large-scale projects, of having individual components supplied as a system from a single source.
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