Refurbishment and Repowering: More power for Phu My

Under a $100 million turnkey contract with EVN, Alstom and Marubeni supplied two Alstom GT13E2 gas turbines, each with an output of 144 MW, to Phu My 2.1
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In May 2001, Electricity of Vietnam (EVN) broke ground on a $137.5 million project to convert a simple cycle power plant at the Phu My power complex to combined cycle. By early 2003, the project will be complete, adding 160 MW of power to Vietnam’s grid.

The expansion of the Phu My 2 Phase 1 (Phu My 2.1) power plant is an important part of the development of the Phu My complex in southern Vietnam. The project will be developed by an international consortium consisting of Alstom and Marubeni Corporation – the same consortium that built Phu My 2.1 between 1995 and 1997.

EVN awarded the Alstom-Marubeni consortium a $115.4 million turnkey contract for the project in March 2001.

“The facility will not only be environmentally sound but will also generate tremendous amounts of additional energy without additional fuel costs,” said Fredy Hausermann, senior vice president of Alstom. “Therefore, it is a very good investment for EVN.”

Growing demand

Figure 2. The two existing GT13E2 gas turbines at Phu My 2.1 will each be coupled to a triple pressure HRSG unit with no reheat. The two HRGSs will be supplied by Alstom Australia
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As the state-owned power corporation, EVN generates the majority of Vietnam’s power. To support the country’s growing economy, the government has given the power sector a high priority for several years, and significant progress has been made in capacity addition, rural electrification and transmission grid development.

Current installed capacity in Vietnam is around 5.5 GW, of which hydropower accounts for 52 per cent, coal fired plants 11.6 per cent, oil fired plants 9.7 per cent, gas turbine plants 18.8 per cent and diesel generators eight per cent.

EVN’s forecasts to 2010 indicate that electricity demand growth in Vietnam will average around 11 per cent, with peak demand growing by about 700 MW per year until 2003 and by more than 1000 MW per year thereafter. The utility faces a number of challenges in meeting this demand.

Vietnam’s overdependency on hydropower means that the country has difficulty meeting power demand during the dry season and during drought years. The country therefore requires an unusually large reserve capacity. In 1998, hydropower accounted for approximately 87 per cent of electricity generation, and EVN is planning to increase natural gas consumption in the power industry, using gas from the country’s offshore gas reserves.

Although the government remains keen to continue tapping Vietnam’s vast hydropower potential, the planned development of offshore gas fields in the Nam Con Son basin and other fields makes natural gas fired power plants the obvious choice for the fast-track development of power generating capacity.

The Phu My complex

Development of the Phu My power complex in Ba Ria – Vung Tau province near Ho Chi Minh City was designed to add 4000 MW of power generating capacity to Vietnam’s power grid by 2003. When it was approved in 1995, strong economic growth was placing severe demands on the power sector and the government envisioned that the complex would become the largest electric power industrial zone in the country.

The Phu My complex was one of the first sites in Vietnam to use natural gas for power production. Currently, the available generating capacity at Phu My stands at around 1300 MW. When complete, the output will be 3875 MW.

Five years ago, Marubeni and Alstom – then ABB – broke ground on the 300 MW Phu My 2.1 simple cycle plant having been awarded the turnkey contract by EVN in December 1995. The two companies won the engineering, procurement and construction (EPC) contract over competition from 17 foreign companies that bid for the project, including Siemens AG and GE.

Under the $100 million contract, Alstom and Marubeni supplied two Alstom GT13E2 gas turbines, each with an output of 144 MW at ambient conditions. The project was financed by the World Bank’s IDA fund.

Phu My started up on schedule in 1997 and since commercial operation began, the two units have accumulated almost 90 000 EOH and 290 starts. Performance testing revealed that both units have also reached output levels higher than the guaranteed level, and efficiency is also higher. The plant is operated by EVN.

Both GT13E2 units are dual fuel. As required by EVN, the machines can run on mixed fuel firing and can switch from gas to oil firing on-line. Both units underwent their first C inspection in 1999 within the spare parts budget.

Power conversion

Under its second contract with EVN, the Alstom-Marubeni consortium will convert Phu My 2.1 to combined cycle within 23 months. The project is being funded by the Vietnamese government.

As consortium leader, Alstom will supply two heat recovery steam generators (HRSG), one steam turbine and the generator. The plant’s output will increase by 160 MW to 450 MW.

Alstom is also responsible for the main mechanical equipment and the control system of the power island. Marubeni will provide the balance of plant equipment, civil works and the installation of equipment at site. Alstom Switzerland will engineer the integration of the existing plant with the new equipment.

The add-on plant will use the exhaust energy of the two existing gas turbines to generate steam for the steam turbine. The exhaust heat of the turbines is currently unused, and no additional fuel will be required to produce the additional output. EVN expects to generate an additional 1 million MWh annually worth about $50 million per year through the add-on facility.

New equipment

The GT13E2 turbine is based on the components of its predecessor, the GT13E, and has been installed in power plants around the world, including Deeside in the UK, Kuala Langat in Malaysia and Meishi Power Plant II in China’s Guangdong province.

The GT13E2 consists of a 21-stage subsonic compressor and a five-stage turbine on a welded rotor and bearing section. It has a pressure ratio of 15:1 and an exhaust mass flow of 523 kg/s. With a turbine inlet temperature of 1100rC, the GT13E2 achieves a power output of 165 MW and a net efficiency of 35.7 per cent in simple cycle operation.

High efficiency and low NOx emissions are achieved through the use of a single annular combustor with EV-burner technology. This design gives a uniform temperature distribution and allowed an increase in the turbine inlet temperature from the GT13E – which used a single burner/silo – without increasing the metal temperature of the turbine blading. The combustor is equipped with 72 EV burners arranged in circles around the turbine shaft.

The two existing GT13E2 gas turbines at Phu My 2.1 will each be coupled to a triple pressure HRSG unit with no reheat. The two HRGSs will be supplied by Alstom Australia and will generate steam at 95.7 bar, 514à‚°C for the 160 MWe Alstom steam turbine.

The steam turbine is of triple pressure two casing design with a HP-IP turbine and a double flow LP-turbine. The live steam supplied by the HRSG is admitted to the HP turbine through two main stop valves and two main control valves. IP steam is admitted via an IP-stop valve and two IP steam control valves. At the IP exhaust side LP steam supply is connected via a stop and a control valve. From the LP turbine exhaust the expanded steam flows into the condenser.

Alstom will also supply an ABB Advant Power Distributed Control System (DCS) to integrate the new equipment with the existing plant. The DCS is for control and monitoring of the combined cycle plant. For control of the steam turbine, a proprietary control system – Turbotrol – will be provided and will be integrated into the overall Advant Power DCS.

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