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Front cover story June 2015 - Increasing energy effeciency with motors and variable speed drives

Published:  30 June, 2015

With increased demands in the oil and gas industry to eliminate losses and optimise operations, while meeting safety and environmental regulations, engineers are reviewing their entire drive chain, from the mechanical components, including electric motors, gearboxes and drives, to the control and automation components, as well as electric panels.

Energy plays a key role in the offshore oil industry, in the production, transfer and distribution of oil and gas, yet a huge amount of this energy is wasted as organisations use solutions that are poorly designed, inappropriate for their applications or old out of date technology. In this article Marek Lukaszczyk, European Marketing Manager at WEG, outlines that by reducing this wastage companies can increase operating efficiencies, reliability and total cost of ownership of equipment, and also cut their costs and improve their profitability.

Today, motors are responsible for generating over 40% of total global energy consumption. Carefully considering the choice of motor will therefore enable significant energy savings to be made. Selecting motors that have been designed with energy efficiency as a priority, such as WEG’s ATEX/IECEx certified W22X that has an IE3 energy efficiency rating, will increase productivity further and be more cost-effective.

However, there are various other steps to take to achieve the most energy efficient set up throughout the drive chain. The most significant of these, especially in pump application, is the control of the motors. By optimising the motor using a variable speed drive (VSD) or invertor enables energy savings of between typically 40% and 60% to be realised.

VSD describes equipment used in industry to control the speed of motor-driven machinery. Typically applications do not run at full load 100% of the time, and this is specifically true for variable torque applications like pumps and fans. Therefore, varying the speed of the drive by installing a VSD can help users save energy and money by controlling the speed of the process and adjusting it to the specific load at any time, compared with other techniques for flow control.

WEG works with OEM pump suppliers and major oil and gas companies worldwide to help them realise energy cost savings. Its reliable and efficient solutions are used in some of the most prestigious offshore oil projects. For example, WEG is a major supplier of control and automation systems and equipment to Brazilian oil company Petrobras. WEG’s technologies are used extensively on its P-57 super FPSO (floating production, storage and offloading) platform. P-57 is anchored at Parque das Baleias, Brazil, at a depth of 1260 metres and is capable of processing up to 180,000 barrels of oil and two million m3 of gas per day.

The WEG package supplied for P-57 included Medium and Low Voltage Panels, Motor Control Centres and Medium and Low Voltage Dry-Type Transformers, among other surveillance and safety subsystems. These products were supplied to Single Buoy Moorings (SBM), the company responsible for the engineering, supply and building of P-57. They were sent to the shipyard in Singapore where the ship was adapted, and where the majority of products supplied were integrated into the platform.

In addition, WEG provided a total of 164 motors for use on P-57. These were supplied to several OEMs that worked directly with WEG. For example, motors for gas compressors were sold to MAN Turbo, Switzerland; motors for water pumps were supplied to SULZER, Brazil; and motors for general applications were sold to KSB Brazil. All products were certified by ABS and, when required, products were also certified for applications in classified areas according to Brazilian and international standards.

The P-57 FPSO-type platform integrates the second phase of the development of the Jubarte field. It will operate integrated to 22 wells, 15 for oil extraction and 7 for water injection. The platform will be the first with such technology to operate off the coast of the state of Espírito Santo.

WEG is meeting the demands for high efficiency operation across oil and gas applications with its extensive range of motors and control gear. In addition to its comprehensive ATEX LV motor range, WEG is also a primary front line supplier to Petrobras of explosion-proof medium and high voltage motors for oil and gas applications.

Designed in conjunction with the oil industry, the "H" (HV) and "M" (MV) line motors deliver outstanding performance, reliability and safety in the most arduous operating environments worldwide. They combine many years of experience with a wide operating range, up to 20MW, and all hazardous area classifications in accordance with the latest ATEX directives. Utilised on many applications including water injection, multi-stage gas compression and oil pipeline duties, the M-Line is WEG's cornerstone product for the oil and gas market. Designed for larger applications in the output range up to 20MW, the M-Line range utilises a box frame construction that is ideally suited to Ex.p. and pre-start purged Ex.n. applications for zone 1 and zone 2 areas having low leakage rates. The internal dispersement pipes within the frame ensure an efficient and quick purge cycle thus keeping the cost of providing purging air/ inert gas to a minimum and, more importantly, providing quick start up times for operators.

For smaller applications, WEG's "H"-Line range offers robustness of construction and is available in safe area, Ex n and Ex e designs. The "H" Line motors cater for medium voltage applications in the range up to 3.15MW and voltages up to 6,600V (50 or 60Hz). Manufactured in IEC frame sizes from 315 to 630, they are compact and extremely reliable machines with sturdy cast-iron frames and high levels of resistance to corrosion.

Complementing the "H" Line motors, WEG's MVW-01 drive is setting new benchmarks for medium voltage (MV) drive efficiency; achieving 99% with an innovative design that employs Multilevel Topology to minimise component levels, and high voltage (6.5kV) IBGT's to reduce motor harmonic currents to extremely low levels.

Unlike many MV drives on the market, which have three or five layer control, the WEG MVW-01 range has just two layers. The benefit of this is a reduction in the number of components in the drive, and improvements in efficiency and reliability. With energy costs at record levels, the efficiency performance of the MVW-01 drives is all important. It has been calculated that for every one per cent of efficiency lost on 1MW drives, the user will pay an extra £5,000 per year on running costs – and that figure is just for the drive alone.

Ultimately, there is no one-size fits all solution and liaising with experts to determine the most appropriate solution will enable users to gain the most benefits. WEG has a comprehensive range of explosion-proof medium and high voltage motors for oil and gas applications. Its products, services, and solutions are used extensively in applications from the incoming power distribution network to the produce flowing from the process, enabling those in the oil and gas industry to increase operational efficiencies and improve bottom-line results. WEG's optimised motors and drives provide energy efficient operation in the most arduous applications and environment, regardless of the location: from the coldest regions and the deepest oceans of the world, to the hottest deserts in the Middle East.


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