Electrical motors used as starter/helper/generator on an LNG plant refrigeration train Read more about Electrical motors used as starter/helper/generator on an LNG plant refrigeration train Body Bonny Island, Nigeria The Case One of the world’s largest LNG complexes The project for Nigeria LNG Ltd based in Bonny Island, Nigeria utilizes the gas reserves of the eastern part of the Niger delta by converting them to liquefied natural gas for export to industrial customers in Europe and Turkey. The plant has seen substantial growth since start up 8 years ago and now has six liquefaction trains in operation. The capacity of each train is 4 million metric tons of LNG per year. In 2002, GE Electrification‘s business was chosen to supply the first two sets of a complete electrical system for the liquefaction of trains 4 and 5. Subsequently in 2004, Electrification was selected again for the electrical set for train 6. Regarding the liquefaction in the LNG supply chain The most economical transportation of natural gas for destinations upwards of 5,000 miles is through liquefaction. The patented liquefaction process reduces the volume by 600 times. Natural gas liquefaction occurs when the gas is cooled to -160°C (-260°F). Several processes are patented. It consists mainly of methane (C1), ethane (C2), propane (C3), butane (C4) and nitrogen (N2). The liquefaction system used at Bonny Island is a conventional process using a Propane Refrigeration (PR) pre-cooling step followed by a Mixed Refrigerant (MR) condensation cycle. Our solution 3 complete electrical systems each comprised of : • Harmonics filters 33 kV • Network transformer 33 kV / 3 kV • Frequency converter SD7000 15.5 MW • Machine transformer 3 kV / 10 kV • 10 kV switchboards • 2 high-speed motors 3,600 rpm – 10 kV - Power 13 MW each • Cooling systems • Energy Management System The challenge The customer’s requirements were very specific, with only two similar installation set-ups in the world. Electrification was able to meet the challenges of optimizing available energy for the customer by using their technical competencies and capabilities. Original concept to reduce the number of equipment For each train, a converter drives two 2-pole turbo synchronous machines of 13 MW each. One machine is dedicated to the 60 MW compressor of the propane cycle, and the other one to the 80 MW compressor of the MR cycle. The two 2-pole turbo synchronous machines are used as : • Starter: to start the gas turbine by accelerating the shaft until the combustion enables the turbine to work alone • Helper: to provide additional power to the gas turbine if required • Generator: to regenerate the excess of power (automatic energy management) Dynamic stability studies Responding to customer demand, Electrification performed time domain studies of the entire system dynamic behavior, including network, gas turbine and compressor shaft-lines. The studies analyzed different occurring events to confirm the stability of the whole process under any possible situations. LCI converters bring high availability and increased reliability Based on thyristor technology for synchronous motors, the SD7000 LCI drive allows speed control up to 100 MW. Electrification’s proven technology and high reliability, for processes requiring high availability, ensures continuous operation 365 days per year. In addition, the four- quadrant operation enables the regeneration of energy to the network with no additional costs. The fully digital controller integrates all the components of an automation controller into a coherent unit: a mechanical structure for industrial environments, powerful CPUs, high-performance operating system, communication networks and industrial inputs/outputs. Combining the thyristors advantages and the last generation of controllers, the SD7000 converter meets the compressor requirements in terms of : • High overall efficiency (> 98.5%) • High availability and reliability • High network disturbance robustness • High starting torque and throughout the speed range • No upper limit of power • Four-quadrant operation • Reduced installation time and cost Power regeneration for increased efficiency During operation thanks to regeneration of excess power, whenever the need is for any loop to reach more or less power, a system balances the need from the power grid to a gas turbine, from a loop to the other one or from a gas turbine to the power grid. So in static mode, as well as in transitory mode, the gas turbine always performs at its optimal operating point. Energy Management System for smooth operation The Electrical Protection and Control Functionality (EPCF) system monitors energy flow and controls the energy requirements of each compressor (PR and MR). It also communicates the energy balance and status of each part of the electrical system through to the gas turbine control system and the plant’s DCS. Harmonic filters also improve power factor Based on extensive experience, Electrification has studied and designed the suitable harmonic filters for the power grid to ensure reduced harmonics disturbance while improving the power factor of the whole grid. 10 kV switchboards: security in all situations Up to nine 10 kV circuit breakers are installed to ensure proper operation and protection of the LNG trains during start up, continuous running and back up. Increase of availability through the interconnection of each train’s supply The power supply for trains 4, 5 and 6 are interconnected. In the event of breakdown, each converter train can function in back up mode for the neighboring train. From the 33 kV network to the 13 MW synchronous motor shaft end, Electrification carried out all the studies, supplied and integrated the different electric components and commissioned the complete electrical system.
Electrical solution with induction motors for LNG - Yemen LNG Project Read more about Electrical solution with induction motors for LNG - Yemen LNG Project Body The Case Yemen began producing oil and gas in 1986 and exporting liquefied natural gas in November 2009. In 2011, production of natural gas reached 340 billion cubic feet and 164.48 thousand barrels per day of petroleum. With a capital expenditure of $4.5 billion, the Yemen LNG project is the largest industrial project in the country. French company Total holds a 39.6 % stake in the project, with the other participants being Hunt at 17.22%, Yemen Gas Company at 16.73%, SK Corporation at 9.55%, Korea Gas Corporation at 6%, Hyundai Corporation at 5.88% and GASSP at 5%. The liquefaction plant operated by Total at the port of Balhaf on the Gulf of Aden is comprised of two liquefaction trains and has a total capacity of 6.7 million metric tons per year. GE’s Electrification business was awarded a contract to supply two sets of complete electrical systems to drive four compressors for the liquefaction trains. Our solution GE provided two complete electrical systems, with each including : • Network transformer 33 kV / 4x1850 V • Frequency converter MV7612 and accessories housed in ATEX containers • Two 2-pole induction motors: 3,600 rpm – 11 MW each • Cooling systems • Automation system for operator monitor and control interface The challenge From the 33 kV network to the 11 MW induction motors shaft end, GE carried out all the studies, supply and integration of the different types of electrical equipment , and was able to reduce the number of items of equipment . For each train, a converter drives two 11 MW induction motors that are directly coupled to the compressor. The 2-pole turbo induction machines are used as a : • Starter, which accelerates the shaft until combustion starts the gas turbine • Helper, to provide additional power to the gas turbine when required (future operation) Induction motors to replace synchronous motors Since the early 1980s frequency converter technology has evolved so that it now applies to electrical motors and acts as direct drives of pumps and compressors. The latest progress in IGBT technology and advanced motor control allows induction motors to provide higher power in medium- voltage, whereas traditionally, synchronous motors are used for driving compressors. The squirrel cage induction motor rotor is a far simpler construction and is inherently more robust than synchronous motors. The rotor conductors are not insulated, and the rotor does not require any rotor excitation circuit. Benefits of VSI technology Voltage Source Inverter (VSI) technology improves the quality and efficiency of the production and offers lower network interferences (low harmonics and high power factor). MV7000 medium-voltage drive technology also offers the benefits of : • Energy enhancement: The PWM active front end enables regeneration of the energy to the network • High efficiency: Up to 99 percent performance • Reliability: With press-pack IGBT technology, fuseless protection and low component count , the MV7000 has a longer life expectancy even under load cycling • Power density: Up to 1.1 MVA/m3 for the complete drive • Redundancy: Secured continuous conduction of the PPI in failure mode • Safety: Case rupture-free and arc ignition-free due to pressed contacts and no wire bonding Additional advantages of this solution, which is based on an induction motor with IGBT inverter, are its reliability and robustness in induction motors, lower maintenance requirements, and compact size.
