Turano Increases 800 MW’s Italian Family
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by Daniela Gentile| Ansaldo Energia, Project Management Director
by Alberto Bigi| Sorgenia Power, CEO


             
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Il contesto economico e finanziario mondiale impone una presenza sempre più globale ai grandi player del settore power, con la ricerca di nuovi mercati al di fuori dei propri confini. Una sfida alla quale Ansaldo Energia non si è certo sottratta, pur continuando a presidiare e sviluppare il mercato domestico.

In quest’ottica è stato particolarmente significativo il 2010, con un contributo al turnover della compagnia di assoluto rilievo, generato proprio da progetti implementati sul territorio italiano: Aprilia (800 MW), San Severo (400 MW) e Turano (800 MW). L’ultimo di questi si è concluso lo scorso ottobre e rappresenta una positiva nuova esperienza per Ansaldo Energia. L’impianto a ciclo combinato di Turano Lodigiano-Bertonico è situato in Lombardia, a ridosso della città di Lodi e appartiene al gruppo Sorgenia.

Il contratto di EPC (Engineering, Procurement, Construction) per l’impianto di Turano è stato assegnato ad Ansaldo Energia nell’aprile 2008. A distanza di 15 mesi dall’avvio del progetto, la stessa Sorgenia ha poi sottoscritto con Ansaldo Energia un contratto similare per la centrale di Aprilia, in provincia di Latina. In entrambi i casi è stato anche previsto un accordo per la manutenzione delle turbine e dei generatori elettrici (Long Term Service Agreement).

Il ciclo combinato di Turano è costituito da due turbine a gas e da una turbina a vapore, per un output nominale di 800 MW. Elementi di particolare rilievo sono stati l’attenzione per le questioni ambientali e per gli aspetti di architettura e la flessibilità operativa.

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INTRODUCTION
In the frame of the actual severe international crisis, in consequence of which competition is pushing companies of the power sector to look for new foreign markets, the activities of Ansaldo Energia (AEN) in the domestic market during the year 2010 significantly still contributed to the company’s turnover, thanks to the EPC projects of Aprilia (800 MW), San Severo (400 MW) and Turano (800 MW). The last one of these, come to conclusion in October, represents a new experience for AEN as far as domestic private customers are concerned.
The Turano Lodigiano-Bertonico Combined Cycle Power Plant is located in northern Italy near the town of Lodi and is owned by Sorgenia, an important private operator in the Italian market in the field of electric power and natural gas, strongly focused on environmental issues.

The plant site is a recently reclaimed industrial area that was previously occupied by an oil refinery demolished in the early 1980s, in the frame of a plan for re-qualifying the surrounding area by developing industrial and artisan sites nearby.
The EPC contract of Turano power plant was awarded to AEN in April 2008 and followed the realization by Sorgenia of similar plants near Termoli and Modugno in central/southern Italy, whose construction had been assigned to other companies.
Fifteen months after the Project start, based also on the positive experience gained during the execution, Sorgenia awarded AEN a contract for a similar plant located in Aprilia site (Province of Latina). In addition to the EPC contract, a Long Term Service Agreement (LTSA) was signed with AEN, relevant to the maintenance of the two gas turbines and their electrical generators.


PLANT CONFIGURATION
This combined cycle is based on a multishaft configuration (2+1), with two gas turbines and one steam turbine generators manufactured in Genoa workshop, delivering a nominal output of 800 MW. The scope of work included the design, supply, construction, start-up and testing of the whole plant, including all the civil works. Apart from the rotating machines, the extent of the supply covered the two Heat Recovery Steam Generators (HRSG), the Air Cooled Condenser (ACC), the gas reduction station, the thermal cycle, the auxiliary systems, including one auxiliary boiler and a Zero Liquid Discharge plant (ZLD), the Distributed Control System (DCS), the HV, MV and LV electrical equipment, including the Gas Insulated Switchgear (GIS) for connection to the substation of the Italian National Grid operator.
The distinctive features of the Project are the focus on environmental and architectural issues and an excellent operating flexibility, that today are critical factors of success, facing an even more competitive market and the community awareness of environmental problems.


SPECIFIC ISSUES
Emissions and efficiency
AEN technology delivers excellent plant performance with low atmospheric emission impact, thanks to the AE94.3A4 gas turbines equipped with VeLoNOx™ burners, whose performances had been already successfully tested on other power plants. The base load efficiency measured during testing was higher than 57%, with CO and NOx emissions much lower than 30 mg/Nm3; the results of plant efficiency tests at partial loads were equally satisfactory.
The average monthly efficiency during the commercial operation, based on daily start&stop in 2+1 configuration during the day and 1+1 configuration at Minimum Technical Load during nighttime and the week-ends, measured in the first quarter 2011, was nearly 56%. During the same period the Minimum Environmental Load has been reduced up to 113 MW, i.e. about 40% of the GT power output.
The Turano Lodigiano-Bertonico Combined Cycle Power Plant
Water management
The management of water resources was also a key issue: the plant has been designed including a Zero Liquid Discharge (ZLD) water treatment system that reduces the consumption of process water from the well, as well as the choice of an air cooled condenser for the thermal cycle. A particular attention has been devoted to the recovery of drains from HRSG and process water as well as for oily and rain water, reducing the average water consumption from the well to about 5 m3/h.

Architectural design
Although the power plant is situated in an industrial area far from population settlements, the design meets specific architectural requirements to ensure environmental and landscape integration in order to reduce visual and acoustic impact. The big hexagonal concrete stack 100m high and the brick red colour used for the cladding of the long machine hall, the boiler houses and the other plant modules, represent the main visual features of the plant, together with the green of the embankments around the plant acting as sound-proof barriers and both recalling the natural colours of the surrounding area.

Flexibility and availability
As far as power generation is concerned, the plant meets the voltage and frequency regulation requirements of the National Grid Operator while from the operational point of view a design requirement is to allow maximum operating flexibility in accordance with legal atmospheric pollutant emission criteria. During the first quarter 2011, average availability has been about 99%. As far as start-up are concerned (on daily basis for each GT alternatively), the following times have been measured:

►Cold start-up: about 180 min;
►Hot-warm start-up: about 90 min;
►Hot start-up: about 60 min.


TIMING
The project was given the Notice to Proceed (NTP) in April 2008 and civil works began in October, following some soil improvement activities. A constant focus on the real needs of the customer and the climate of proactive collaboration established, together with technical expertise and careful planning and monitoring of work, have made possible to achieve the contractual project targets and, specifically, Provisional Acceptance Certificate (PAC) in just 30 months from the NTP.
Site works involved up to about 850 people in peak periods, with an important participation of local companies, taking into account the expectations of industrial organizations and trade-unions. With the final hand-over of the plant in October 2010, the Long Term Service Agreement came into effect, for a contractual duration of 7+7 years; in addition to maintenance and repair works, the agreement entails operating parameters logging and remote monitoring from the diagnostic control room at AEN’s production facility in Genoa.