PLANT TORINO NORD
Iren Energia is the company in the Iren Group whose core businesses are the production and distribution of electricity, the production and distribution of thermal energy for district heating and the provision of technological services. The Torino Nord cogeneration plant with its capacity of 400 MW of electric power and 220 MW of thermal power provides district heating for another 15 million cubic metres and is fed exclusively with natural gas. Iren Energia, which has always been sensitive to environmental protection issues, produces electricity and heat from renewable energy sources (hydroelectric power plants) or similar sources (cogeneration plants). Iren Energia constantly pursues its objectives, which are quality, reliability, sustainable development, energy efficiency and a close relationship with the areas in which it operates. The buildings served are reached via the 120 km district heating pipe network which is interconnected with the previous Torino Sud and Torino Centro plants. The Torino Nord plant also comprises a 340 MW supplementary and back-up plant and an innovative hot water accumulation system with a capacity of 5,000 cubic metres.
The Iren Energia cogeneration plants combined with the city district heating system produce heating for 550,000 people living in Turin, making it the city with the largest district heating system in Italy and one of the largest in Europe, with significant environmental benefits compared to traditional heating systems. Iren Energia s integrated cogeneration and district heating system also comprises supplementary and back-up plants (BIT, Mirafiori Nord, Moncalieri, Polytechnic and Torino Nord) for the Moncalieri and Torino Nord cogeneration plants. The Torino Nord project (cogeneration plant and district heating networks) has enabled new standards to be reached in the field of energy and environmental efficiency in the area. Part of the merit for this is due to the fact that the Torino Nord plant has been fitted with advanced selective catalyst reduction systems capable of drastically reducing the amount of nitrogen oxide emitted and to the presence of a large hot water accumulation system, which minimizes the need to use the supplementary and back-up system. Another important feature is that both the cogeneration plant and the supplementary and back-up plant are fed exclusively with natural gas. The cogenerator has an efficiency of over 85% in cogeneration mode and 56% in electricity only mode. The Torino Nord plant reduces atmospheric emissions considerably by eliminating the need for hundreds of apartment building boilers, and ensures a reduction in emissions of 134 tons of nitrogen oxide, 400 tons of sulphur oxides and 17 tons of powder per year. In terms of energy, the yearly saving is 95,000 TOE (Tonnes of Oil Equivalent), in addition to the 180,000 TOE saved due to the effect of the Moncalieri cogeneration plant. Following the commissioning of the Torino Nord plant, the old Le Vallette cogeneration plant, situated in the district of the same name, has been decommissioned and is to be dismantled. An underground heat exchange substation has been built on its site. The area left free will be remediated and returned to the community in the form of public gardens.
Torino Nord Cogeneration Plant The Torino Nord cogeneration plant produces electricity and heat for district heating. The most important parts of the plant are: The thermoelectric, dual shaft, combined-cycle unit (gas turbine and steam turbine), with a gross electrical power in cogeneration mode of about 400 MW, fed exclusively with natural gas; The 3 supplementary and back-up steam generators, with a total thermal power of 340 MW, fed exclusively with natural gas; The heat accumulation system made up of 6 tanks with a total capacity of 5,000 cubic metres. The gas turbine The turbine with its electrical power of 270 MW is a single-shaft machine with a 15-stage air compression section (18-bar compression ratio) combined with a 4-stage turbine section. The normal power gradient is 13 MW/min. The blades of the turbine, subjected to stress, are air-cooled internally and protected externally by a cushion of cooling air blown in through holes machined into the blades. The blades for conveying the air flowing into the compressor have an adjustable angle. The turbine is equipped with a hydraulically activated system for recovering the casing/rotor blade play, which ensures an improvement in performance. The steam generator The heat recovery steam generator has a horizontal design, three pressure levels with a resuperheater. Its main components are: High pressure (HP), medium pressure (MP) and low pressure (LP) heat The thermoelectric combined-cycle unit includes a selective catalytic reduction (SCR) system Catalyst Gas Turbine Air Gas COMP GT Injection of NH 4 Storage tank NH 4 OH Smoke fan skid Atomizer Regulation valve
exchanger banks, final heat recuperator; HP, MP and LP cylindrical bodies complete with hydrometric columns and accessories; Chimney with a height of 60 metres from the ground; Degassing tower; Selective nitrogen oxide (NO X ) catalyst TORINO NORD reduction system that drastically reduces the concentrations of oxides in the smoke at the chimney. The combustion chamber has 24 dry low NO X emission burners set in a ring and the combustion area lies around the inlet section of the first turbine stage. The steam turbine The turbine, with its electrical capacity of 119 MW is made up of two bodies (medium-high and low pressure) and is suitable for producing electricity and thermal energy for district heating through the extraction of steam. The steam for producing thermal energy is extracted from a tap on the middle body and one on the crossover connecting the two turbine bodies. The steam released by the low pressure turbine flows into the steam pipe of the condensation system. MIRAFIORI NORD POLYTECHNIC BIT MONCALIERI Cogeneration plants Supplementary and back-up plants District heated area The condensation system The condensation system is made up of a unit heater equipped with dualspeed, low noise fans. The steam is conveyed from the LP steam turbine outlet to the unit heater through a pipe, it is then distributed through four dividing lines and the condensate is conveyed to a special conden-
sation collecting tank. A system of extraction pumps transfers the condensate to the degassing tower and the desuperheaters. The condensation flow regulating unit is made up of two pneumatic regulation valves, each at 100%, complete with manual shutoff and bypass valves. The supplementary and back-up plant The three generators are of the type with pressurized natural circulation water tubes, with natural gas burners and a static smoke heat recuperator. Each steam generator is equipped with two burners for combustion with an extremely low production of nitrogen oxides. The steam produced by the generators is transferred to a single heat exchanger for the production of water superheated to 120 C for the district heating network. The generators perform the dual function of: Supplementing the supply to cover peak loads of the district heating network; Replacing the combined cycle when it is out of order. The main characteristics and technical data of each steam generator are: Net power at Maximum Continuous Load (MCL) returned to water by district heating system 116.4 MW; Net power at MCL returned to water by the district heating system through smoke heat recovery 5.4 MW; Cold start-up to full load time of no more than 3 h. The six tanks have the following characteristics: Design pressure 18 bars; design temperature 210 C; Inside tube diameter 7,000 mm; Tube height 18,500 mm. The essential function of the heat accumulation system is to store the heat produced by the cogenerator at night time, when there is a lower demand for heat and to transfer it at peak demand times to the district heating network, thus reducing the need to use the supplementary boilers to a minimum. On the basis of the service needs, the heat accumulation tanks may be filled and emptied several times a day. The heat accumulation system The heat accumulation system comprises six pressurized tanks with a total net capacity of 5,000 cubic metres.
Functional diagram G 3~ Steam generator with three pressure levels pressure (bars) capacity (Kg/s) temperature ( C) AP 125 70,3 550 MP 30 81,5 550 BP 4,5 12,65 237 Gas turbine Capacity Fuel 270 MW natural gas DEGASSING TOWER AP MP BP G 3~ Steam turbine Capacity 119 MW M Air-cooled condenser Heat exchangers for district heating thermal power 220 MW inlet temperature 70 C outlet temperature 120 C district heating
w w w. i r e n e n e r g i a. i t Iren Energia S.p.A. Corso Svizzera, 95 10143 Torino - Italy Tel. +39 011 5549 111 Fax +39 011 53 83 13