Meeting demand with industrial power

The Turkish power market has undergone many changes in recent years, all in the name of attracting private investment to meet rapidly growing power demand. Three recently commissioned gas turbine-based projects illustrate the market trends of this expanding economy.

Steve Demoret,

GE Industrial AeroDerivative Gas Turbines,

Evendale, Ohio, USA;

Ruhan Temeltas,

S&S Energy Products,

Istanbul

Since the early 1980s, Turkey`s electricity market has shown growth averaging nine per cent between 1980 and 1996. Estimates also indicate that some $16 billion of investment is required in the country`s energy sector before 2000 and $24 billion thereafter. A majority of money will be used for the construction of new power generating capacity.

This growth and the prospect for additional expansion has brought many changes to Turkey`s power generation market, in particular, deregulation and privatization. Turkey`s principal electricity generator and distributor is the Turkish Electricity Authority (TEK), the state entity that owns and operates 18 478 MW of generation. In preparation for privatization, the government split TEK into two divisions: the Turkish Electricity Generation & Transmission Co. Inc. and the Turkish Electricity Distribution Co. Inc. There also are several private power producers in Turkey.

Rapid growth and privatization have also helped to attract international attention and investment into the country. Turkey will need 2500 MW a year of electricity until 2010, which translates to 30 000 MW of new capacity over the next 11 years. Turkey expects most of this new capacity to be sourced from the international private sector. The current installed capacity in Turkey is under 22 000 MW which includes 6500 MW of coal-fired projects, 2550 MW of gas-fired plants, 680 MW of oil-fired plants and 10 700 MW of small and large hydroelectric projects.

It is also expected that Turkey will increase its use of natural gas, with most of the demand coming from natural gas-fired power stations. Imports of natural gas are expected to quintuple to 55 billion m3 per year by 2010. There is strong competition within Turkey itself to be the new source for this supply. Yet plans exist to develop pipelines from Turkmenistan, Iran, Iraq and Egypt. There are also plans to bring liquefied natural gas in from Qatar, Algeria and Nigeria.

According to Turkish Energy Minister Ziya Aktas, the proposed Baku-Ceyhan and Trans-Caspian pipelines are Turkey`s top priority in building east-west energy corridors. Turkey is proposing a pipeline that would run from Baku, Azerbaijan to Ceyhan on Turkey`s Mediterranean coast.

It is believed that these pipelines would help stabilise the region and serve Turkey`s long-term interests, especially in its rapidly expanding power market. While some developers in Turkey are known to have experienced problems in implementing their projects, at least three three new power plants have begun commercial operation over the past six months – Ataer Elektrik, Entek Bursa, and Zorlu Enerji.

All three projects were developed to bring an efficient and reliable source of power to a variety of industrial customers. Each is based on state-of-the-art GE gas turbine technology, with turnkey services performed by S&S Energy Products.

A common thread

Ataer Elektrik, Entek Bursa, and Zorlu Enerji each use GE`s LM6000 aeroderivative gas turbines; Zorlu Enerji also uses GE`s LM2500+ aeroderivative gas turbine. The generator sets were sold and packaged by S&S Energy Products (SSEP) of Houston, TX. The gas turbines were manufactured by GE Industrial AeroDerivative Gas Turbines, Evendale, OH.

The LM6000 shares many common components with GE`s CF6-80C2 aircraft engine, and is a unique aeroderivative in that its low-pressure turbine can be directly coupled to its load without using a separate power turbine. This concept improves the simple cycle efficiency, and reduces the gas turbine`s cost and unit size.

The LM6000 low pressure rotor consists of a five-stage low-pressure compressor and a five-stage low-pressure turbine connected by means of a mid-shaft, which extends through the centre of the engine. The high pressure rotor consists of a 14-stage high-pressure compressor and a direct-coupled, two-stage high-pressure turbine.

The Brush air-cooled generators are rated at 59 500 kVA at 0.80 power factor, 15 degreesC (59 degreesF) cooling air and 11 000 V, and are designed to accommodate full gas turbine power output over the full ambient air temperature range. Each generator is fully rated to accommodate future ratings increases, and includes a brushless excitation system with permanent magnet generator. The gas turbine is controlled by Woodward Governor`s NetCon 5000 controls.

The LM6000s have a two-piece skid assembly sectioned between the gas turbine and the generator/main load gearbox for convenient transportation. Each SSEP gas turbine-generator package uses an earthquake-qualified structural design, durable electrical systems and all-stainless steel fluid systems and reservoirs. All packages are factory assembled and tested at full load before shipment.

The test uses the contract control panel and auxiliary systems to minimize field start-up and debugging time. This demonstration of power output and heat rate guarantees, significantly reduces performance risks for both the owner and the lender.

The 40 MW LM6000 simple-cycle Ataer Elektrik power plant is owned by Ataer Elektrik Uretim Otoproduksiyon A.S. (Ataer Elektrik), a company formed by members of the Ataturk Organized Industrial Zone. The plant began operation in August 1998. It is expected to be converted within a year to combined cycle cogeneration configuration with the addition of the same type and capacity gas turbine, two waste heat boilers and a steam turbine.

Several of the small- to mid-size companies in the Ataturk Organized Industrial Zone (see Table 2) have high steam and electricity requirements for manufacturing. With the anticipated energy shortages in Turkey, these organizations formed Ataer Elektrik, a company whose purpose is to produce electricity in the industrial region.

After soliciting and reviewing bids for equipment and construction capabilities, Ataer Elektrik selected SSEP to build the new power plant. But before construction could begin, Ataer Elektrik needed to secure financing. Working over a period of six to seven months, SSEP helped arrange financing (US Exim and medium-term commercial loan) for the gas turbine through the Chase Bank Texas and Chase Manhattan, Turkey.

SSEP provided the turnkey installation of the 40 MW LM6000 which features SSEP`s dual-fuel naphtha fuel system; diesel is used to start-up the gas turbine before switching to naphtha at part load. Table 3 provides an overview of the civil, mechanical and electrical work provided by SSEP for this project.

SSEP also supplied and installed various mechanical equipment including the hydraulic start skid, air-cooled lube oil cooler skid, the inlet air filtration system, final duplex air filter, the wash water storage tank, the naphtha fuel tank (one raw and one treated), and a distillate fuel-oil tank.

Naphtha fuel system

SSEP announced its patent-pending flash temperature control technology in mid-1997. This system eliminates the need for an entire standby diesel fuel supply circuit. This technology is designed for the LM6000, and it offers power producers the flexibility to operate this aeroderivative gas turbine on naphtha fuels. The system underwent a two-phase testing programme at SSEP`s Houston test cell. Over 150 engine operating parameters were measured on each of the two LM6000 gas turbines using a very light 0.65 specific gravity naphtha.

Phase I, which was successfully completed in the first quarter of 1996, demonstrated the capability to predict the naphtha flash point and to transfer between naphtha and diesel fuel at safe power levels. Phase II started the engine on naphtha using a patent-pending liquid cooling system designed by SSEP. This test eliminated the need for diesel fuel, and was completed in October 1996.

Naphtha has a very low flash temperature and forms a gas that is heavier than air when it evaporates. The gas can therefore fall to the ground and pool. Should a naphtha leak become severe, the level of the vapours could rise, come into contact with the gas turbine and cause an explosion.

With this in mind, safety was a strong consideration for SSEP while designing the naphtha fuel system. To prevent any inadvertent leaks from coming into contact with the gas turbine, heavy gas ventilation fans were added to the package base. These fans direct any naphtha vapours outside the gas turbine enclosure to the atmosphere or to a customer-supplied flare stack.

In addition, the gas turbine control uses a flash temperature algorithm which tells the operator when it is safe to transfer to and from naphtha fuel. The algorithm was verified during Phase I and was later incorporated into production control systems.

To ensure that the operator is always aware that operation on naphtha has been initiated, the control system does not allow automatic transfer to naphtha. Instead, the operator must press a button to start on naphtha or transfer to naphtha.

Additional single-lift skid modules are required if starting the LM6000 on naphtha: a refrigeration module which is 7.3m x 3.0m, and a brine tank which is 2.4m x 2.4m. Both modules are fully-assembled and pre-tested with the complete system prior to delivery.

A strategic team

Entek A.S. uses two LM6000 gas turbine-generator sets for its 106 MW combined cycle cogeneration plant in Bursa. Entek was established to handle the responsibilities of developing this power plant. Entek consists of 80 per cent KOC Group, Istanbul, one of the world`s largest industrial corporations, and 20 per cent Sonmez Holding, Bursa, which encompasses 29 associations in various industrial sectors such as textiles, building and communications. The new power plant is adjacent to the Tofas/KOC automotive factory and the Sonmez textile factory.

The power plant began generating energy in simple cycle mode in December 1998; combined cycle service is slated for the second half of 1999. The plant will produce 15 000 to 120 000 kg/h of process steam. All steam and electricity will be used for processing operations.

As the turnkey contractor, SSEP formed a strategic project team consisting of Turkish contractor Istanbul Goema (IG) and Energy Services, Inc. of the United States.

As the project leader, SSEP supplied the following equipment for the Bursa power plant:

•Two LM6000 gas turbine generator sets;

•Two unfired triple pressure DESA heat recovery steam generators (HRSGs);

•One GE extraction/admission steam turbine generator set.

The DESA HRSG has a total steam flow of 38 t/h, working pressure of 46.5 bar and superheated steam temperature of 396.1 degreesC.

Also in Bursa, SSEP provided power generation equipment and turnkey services to Zorlu Enerji Elektrik Uretimi Grubu A.S. as part of a three-company consortium. The power plant equipment included an LM2500+ aeroderivative gas turbine that is used by Zorlu Enerji for a captive 35 MW combined cycle plant in Bursa. Electricity is supplied to Zorlu Enerji`s sister company, Korteks, a textile manufacturer.

The LM2500+ power plant began commercial operation in August 1998, and as of March 1999 had logged 2900 fired hours. It is used in conjunction with an 8.5 MW steam turbine with 15 bar bleed provision.

SSEP devised and implemented a test programme at the Zorlu Enerji Bursa site which consisted of: development of performance procedures for the gas turbine, steam turbine, HRSG and air-cooled condenser; development of a combined cycle plant performance test; and supervision of performance testing.

SSEP also provided Zorlu Enerji with an LM6000 gas turbine-generator set which will join the LM2500+ at the same site. The LM6000 will begin commercial operation in the second half of 1999 at this Bursa location; total plant output will be increased to 90 MW.

Zorlu Enerji has also purchased a second LM6000 from SSEP for another power plant in Luleburgaz. The unit was added to an existing cogeneration facility that already has two industrial gas turbines in service. With the LM6000 operating, total installed capacity for the plant will be 61 MW of electricity and 110 t/h of steam which will be used for textile processing.

Commercial operation of the LM6000 at this site was slated to begin during the second half of 1999. Zorlu Enerji also has an option for a second LM6000 for the Luleburgaz site.

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Figure 2. Entek Bursa project, Turkey

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