Corso di formazione ed aggiornamento professionale per Energy Managers-Trenitalia Giugno 2011

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1 Corso di formazione ed aggiornamento professionale per Energy Managers-Trenitalia BOLOGNA Giugno 2011 E N O I Z A R E N E COG co n a r F i D o in N. g n D I N I E TE U A ENE

2 COGENERAZIONE PRE-CONDIZIONI CHE RENDONO FATTIBILE UN IMPIANTO DI COGENERAZIONE 1) Domanda di calore a bassa temperatura (vapore a bassa pressione, acqua calda, cicli ad assorbimento) 2) Domanda di elettricità 3) Contemporaneità tra domanda e offerta 4) Dimensione importante della domanda energetica 5) Giusto rapporto tra domanda elettrica e termica 6) Elevato numero di ore all anno di richiesta energetica

3 COGENERAZIONE COGENERAZIONE CONTROINDICAZIONI PER LA COGENERAZIONE 1) Investimento elevato (seppur con tempi di ritorno normalmente variabili tra 3 e 5 anni) 2) Rigidità gestionale degli impianti

4 COGENERAZIONE A) PRODUZIONE SEPARATA DI ELETTRICITA E CALORE (Cifre in unità energetiche) DOMANDA TERMICA 50 IN: (η =80%) = 50/0.8 = DOMANDA ELETTRICA 30 IN: (η =35%) = 30/0.35= Perdite = 68 η = 80/148 = 54% 148

5 COGENERAZIONE B) PRODUZIONE CONGIUNTA DI ELETTRICITA E CALORE (Cifre in unità energetiche) DOMANDA TERMICA DOMANDA ELETTRICA IMPIANTO DI COGENERAZIONE IN: Perdite = η = 80/100 = 80%

6 COGENERAZIONE COGENERAZIONE CON TURBINA A GAS η e =20-40% EL. INDEX W/Q = 0,2-0,8 SIZE > 0,5 MW FUEL: methane COST: Eur/kW MAINTEN.: 0,8 ceur /kwh

7 COGENERAZIONE

8 COGENERAZIONE CON TURBINA A GAS Advantages Diisadvantages - High grade heat available - Lower mechanical efficiency than reciproc. engines - High reliability which permits long-term - Limited number of unit sizes within the Output range unattended operation - Constant high speed enabling close - If gas fired, requires high-pressure supply or in-house frequency boosters - Control of electrical output - High noise levels - High power to weight ratio - May need long overhaul periods. - No cooling water required - Need to be clean of dry - Relatively low investment cost per kwe - Output falls as ambient temperature rises due to electrical output thermal constraints within the turbine - Wide fuel range capability (diesel, LPG, - Poor efficiency at low loading (but they can operate naphtha, associated gas, landfill sewage) continuously at low loads) - Multi fuel capability - Low emissions

9 COGENERAZIONE CON MOTORI A COMBUSTIONE INTERNA COGENERATION η e =25-50% EL. INDEX W/Q = 0,2-0,5 (total recovery) 0,5-1,5 (only exhaust gas recovery) SIZE > 0,2 MW FUEL: methane, oil, landfill sewage COST: 800 Eur/kW MAINTENANCE: 1,5 ceur/kwh

10 COGENERATION COGENERAZIONE CON MOTORI A COMBUSTIONE INTERNA Advantages Diisadvantages - High power efficiency, achievable over a wide load - Must be cooled, even if the heat range recovered is not reusable - Relatively low investment cost per kwe electrical output - Low power to weight ratio - Wide range of unit sizes from 3 kwe - High levels of low frequency noise - Part-load operation flexibility from 30% to 100% with - Forces requiring substantial foundations high efficiency - Can be used in island mode (all ships do this) good load - High maintenance costs following capability - Fast start-up time of 15 second to full load (gas turbine needs hours) - Real multi-fuel capability, can also use HFO as fuel - Can be overhaul on site with normal operators; - Low investment cost in small sizes - Can operate with low-pressure gas (down to 1 bar)

11 APPLICATION FIELD OF DIFFERENT COGENERATION TECHNOLOGIES COGENERATION Electricity/Heat ratio ,5 0,2 0,1 TOTAL HEAT RECOVERY MOTORS ONLY EXHAUST GAS RECOVERY MOTORS COMBINED CYCLES CONDENSING STEAM TURBINES GAS TURBINES BACK PRESSURE STEAM TURBINES 0,05 0,02 0,01 0,1 0, Electric Power - MW e

12 COGENERATION TYPICAL MANAGEMENT CONDITIONS FOR TURBOGAS 1) The heat recovered from exhausted gas is sensible heat. To absorb completely the offer of heat, contemporary low and high temperature needs are requested C b) 430 a) Curve a) (both low and high temperatures needs) satisfies completely the offered heat Curve b) (only high temperature needs) exploits only a part of the offered heat Q

13 COGENERATION 2) Ambient temperature and site altitude affect the electric production output: - every 10 C exceeding the ambient temperature, the output decreases by 8% (ambient reference: 16 C) - every 1000 m in altitude, the output decreases by 10% Effects of Ambient Tempature - Typical Heavy-duty GT

14 GAS TURBINE INLET AIR COOLING ENERGY SAVING IN REFINERIES Cooler air is denser and consequently provides more mass flow. Cooling air by injection of water droplets could be an inexpensive, low maintenance and hassle-free alternative to chillers or media type evaporative coolers. A high-pressure pump system pressurizes water, typically deionized water for gas turbine applications. Normal operating pressures are from 50 to 200 bar. The high-pressure water flows through a network of stainless steel tubes to special stainless steel nozzles.

15 ENERGY SAVING IN REFINERIES GAS TURBINE INLET AIR COOLING The fog nozzles atomize water into micro-fine fog droplets that evaporate quickly even in high humidity conditions. Time for retrofitting is short (1-3 days). A fog system installed for a 100MW turbine (8 C degrees of cooling) costs about $160,000. The turbine will produce about 10 MW more power. Furthermore, the overall efficiency of the turbine can increase by about 3%.

16 ENERGY SAVING IN REFINERIES GAS TURBINE INLET AIR COOLING Droplet Size and Flow Rate vs. Operating Pressure

17 ENERGY SAVING IN REFINERIES GAS TURBINE INLET AIR COOLING

18 ENERGY SAVING IN REFINERIES GAS TURBINE INLET AIR COOLING The Plant

19 ENERGY SAVING IN REFINERIES GAS TURBINE INLET AIR COOLING Problems adopting inlet air cooling 1) If ambient moisture is high, there are problems in keeping the fog production plant set at standard parameters. 2) There are problems of corrosion and rust along the air ducts of the compressor. 3) Possibility of wear and tear for the compressor blades if hit by the droplets.

20 POWER PLANTS - MEASURES TO IMPROVE EFFICIENCY ENERGY SAVING IN GAS TURBINE PLANTS IF THERE IS EXHAUST HEAT ANYWHERE IN THE PLANT, IT IS POSSIBLE TO RECOVER IT AND HEAT THE METHANE FEED OF THE COMBUSTION CHAMBER METHANE

21 POWER PLANTS - MEASURES TO IMPROVE EFFICIENCY ENERGY SAVING IN GAS TURBINE PLANTS IT IS POSSIBLE TO RECOVER THE EXHAUST HEAT OF AIR FROM THE VENTILATION PLANT OF THE HUT CONTAINING THE EQUIPMENTS, TO HEAT THE COMBURENT AIR COMBURENT AIR METHANE