Energy Service: Increasing efficiency of steam turbines

Transcription

1 Energy Service: Increasing efficiency of steam turbines Erich Steiner, Head of Service-Engineering for Industrial Steam Turbines siemens.at/future-of-energy

2 Energy Service: Increasing efficiency of steam turbines Contents Energy Service: Your competent partner in Austria 3 Basic functions of a steam turbine 4 Increasing efficiency of steam turbines 9 with focus on the total plant process Example for optimization of steam turbine & plant process as a result of changes in plant operation Summary 17 age 2

3 Energy Service: Your competent partner in Austria ortfolio of products Wind ower Scope of services Steam Turbine Compressor Field service Spare parts Monitoring Siemens City Vienna Inspections Gas Turbine Generator Overhauls Repairs Revamps Upgrades Modernization Our team in Vienna is always available for your questions Your problems are our business - your worries are our challenge age 3

4 Basic functions of a steam turbine Steam turbine set Electrical Output of the steam turbine set = m D h S h i ( h mech ) age 4

5 Basic functions of a steam turbine Steam flow through the steam turbine View of the interior of a steam turbine Live steam age 5

6 Basic functions of a steam turbine Rotor blades (shown in unrolled plane) Steam flow in blade channel (unrolled) guide blade rotor blade guide blade rotor blade age 6

7 Basic functions of a steam turbine The geometry of the blade channel of a turbine is determined by the mass flow and the steam parameters at the inlet and outlet recise shape and angle of the blade profiles ensure best use of thermal energy to mechanical rotation = m D h S h i ( h mech ) Outflow p out [bar] t out [ C] c 0 Guide blade Rotor blade w 2 u 2 Inflow p in [bar] t in [ C] L out p 0, t 0 w 1 c 2 L in p 2, t 2 ØD in m [kg/s] ØD out c 1 u 1 The plant process defines the geometry in the turbine age 7 Thermal energy in outflow p 2, t 2 < inflow p 0, t 0

8 Basic functions of a steam turbine Short trip to thermodynamics isobaric lines p 1 = m D h S h i ( hmech) The highest efficiency of a turbine is defined with the design load point Enthalpy h [ kj/kg ] h 1 h 2 h 2.0 h S p 2 t 1 isothermal lines t 2 t 2.0 h h i = h hs Enthalpy (spec.) h [kj/kg] Thermodynamic state variable, measure of the energy of a system (thermal capacity) Entropy (spec.) s [kj/kg K] Thermodynamic state variable, measure of the reversibility of a process (efficiency) Steam state turbine inlet p 1 [bar], t 1 [ C], h 1 [kj/kg] Efficiency η i [%] 100% 90% 80% 70% 60% part load design load Efficiency reaction stage over load blade length Steam state turbine outlet p 2 [bar], t 2 [ C], h 2 [kj/kg] u / c 0 50% 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 Entropy s [ kj/kg K ] 25% 50% 75% 100% 125% 150% Steam flow m [%] age 8

9 Increasing efficiency of steam turbines with focus on the total plant process Example: Original design of the plant process Basic functions of the plant equipments Live steam H Extraction steam Turbine L Exhaust steam Generator G BOILER: Combustion of various fuels / evaporation of water Supply of thermal energy for the steam cycle Input: Chemical energy -> Output: Thermal energy TURBINE: Transform flow velocity to expansion and rotation Supply of rotation movement for the generator Input: Thermal energy -> Output: Mechanical energy Boiler Feed water system rocess Dryer Air Condenser Cooling air GENERATOR: Electromagnetic Field; Supply of elect. output Input: Mechanical energy -> Output: Electrical energy ROCESS: Steam extraction from the turbine Consumption of thermal energy for the plant process CONDENSER: Condensation of exhaust steam from turbine Destruction of residual steam energy for return in water cycle Feedwater Condensate FEEDWATERSYSTEM: Recirculation of feed water in boiler age 9

10 Increasing efficiency of steam turbines with focus on the total plant process Example: Original design of the plant process Technical data of original plant design Live steam 73 bar 476 ºC H Extraction steam 12 bar 255 ºC Turbine L Exhaust steam 0,15 bar Generator G Original design load of the steam turbine: Type: Extraction condensing turbine (air condenser) Live steam: 127,0 t/h / 73,0 bar / 476 ºC Extraction steam: 82,7 t/h / 12,0 bar / 255 ºC Exhaust steam: 44,3 t/h / 0,15 bar / 54 ºC Electr. Output: kw Boiler Feedwater Feed water system rocess steam 12 bar 250 ºC rocess Dryer Condensate Air Condenser Cooling air Original design process steam (dryer): Extraction steam: 79,0 t/h / 12,0 bar / 250 ºC Thermal heat: kw History of Changes: Shut down of a process dryer Connection to district heating age 10

11 Increasing efficiency of steam turbines with focus on the total plant process Example: Changes of the process of the plant Step 1: Destrict heating & original turbine Live steam 73 bar 476 ºC H Extraction steam 12 bar 255 ºC Turbine L Exhaust steam 0,15 bar Generator G Basic Requirements for the new process: Electr. output: kw fixed original design Max. possible district heat based on electr. output Red. valve Heating steam Boiler rocess Dryer Air Condenser Heater 4,2 bar 145 ºC Supply 140 ºC Cooling air Return 60 ºC Feedwater Condensate Condensate age 11

12 Increasing efficiency of steam turbines with focus on the total plant process Example: Changes of the process of the plant Step 2: Optimization of turbine & process Live steam 73 bar 476 ºC H Extraction steam 4,5 bar 160 ºC Turbine L Exhaust steam 1,2 bar Generator G Requirements for revamping of the steam turbine: Increasing of total efficiency of the plant process based on the original live steam parameter Heating steam 2 Red. valve Heating steam 1 Boiler rocess Dryer Air Condenser Cooling air Heater 1 4,2 bar 145 ºC Heater 2 1,2 bar 105 ºC Supply 140 ºC 100 ºC Return 60 ºC Feedwater Condensate Condensate age 12

13 Increasing efficiency of steam turbines with focus on the total plant process Example: Revamping of the turbine Basic fundamentals: ü Analysis of the current operating process of the plant ü Evaluation of the future goals and requirements ü Optimization of the turbine based on the plant process Modifications of steam turbine (for our example): ü Optimizing of the steam channel for H-turbine part Inlet: original live steam / Outlet: new extraction 4,5 bar ü Optimizing of the steam channel for L-turbine part Inlet: new extraction 4,5 bar / Outlet: new exhaust 1,2 bar lant compatibility and implementation: ü Focus on the inner life of the steam turbine (blade channel) ü Use of the original plant peripherals (original-turbine casing) ü Save time and money in combination with the major revision age 13

14 Increasing efficiency of steam turbines with focus on the total plant process Evaluation of the turbine Original design of plant process and steam turbine Old process dryer Without process District heating Optimization Turbine & rocess Live steam flow 127,0 t/h 50,1 t/h 127,0 t/h 127,0 t/h H-Turbine Inlet steam parameter Outlet steam parameter 73 bar / 476 ºC 12 bar / 255 ºC 73 bar / 476 ºC 12 bar / 272 ºC 73 bar / 476 ºC 12 bar / 255 ºC 73 bar / 476 ºC 4,5 bar / 160 ºC Electrical output 13,46 MW 4,78 MW 13,46 MW 19,26 MW rocess Extraction steam flow Required parameter Dryer: 79,0 t/h FW pre-heat.: 3,7 t/h 12 bar / 250 ºC 0,0 t/h FW pre-heat.: 5,8 t/h not necessary Heater: 79,0 t/h FW pre-heat.: 3,7 t/h 4,5 bar / 150 ºC Heater: 63,8 t/h FW pre-heat.: 1,1 t/h 4,5 bar / 150 ºC Thermal heat (useable) 50,72 MW 0,00 MW 46,70 MW 74,88 MW Exhaust steam flow 44,3 t/h 44,3 t/h 44,3 t/h 62,1 t/h L-Turbine Outlet steam parameter 0,15 bar / 54 ºC 0,15 bar / 54 ºC 0,15 bar / 54 ºC 1,2 bar / 105 ºC Electrical output 5,85 MW 5,97 MW 5,85 MW 2,90 MW Total Electrical output age 14 19,31 MW 10,75 MW 19,31 MW 22,16 MW Increase of electrical output: +2,85 MW / +14,8%

15 Increasing efficiency of steam turbines with focus on the total plant process Evaluation of the process Heat of evaporation (boiler) Electrical output turbine Original design District heating Optimization Turbine & rocess 100,31 MW 100,31 MW 19,31 MW 22,16 MW Original design 19,2% 34,2% 46,6% Thermal heat utilization 46,70 MW 74,88 MW District heater 1 (extraction steam) District heater 2 (exhaust steam) Thermal heat losses Air condenser (indirect heat loss) 46,70 MW not possible 34,30 MW 27,25 MW 37,71 MW 37,17 MW 3,26 MW 0,00 MW Turbine Revamp 3,3% 22,1% 74,6% Various process losses 7,05 MW 3,26 MW Usable portion of evaporation heat 65,8% 96,7% Increase of economic efficiency: + 30,9% age 15 Electrical output turbine Thermal heat utilization process Thermal heat losses

16 Increasing efficiency of steam turbines with focus on the total plant process Example: Highlights of the steam turbine revamp Increase of electrical output: + 2,85 MW per hour hours of operation per year Either: MW h more electrical output per year for the same live steam consumption or: t (steam) less live steam consumption per year for the same electrical output Increase of the thermal heat utilization: + 28,18 MW per hour hours of operation per year MW h more thermal heat per year for the same live steam consumption Increase of total economic efficiency: + 30,9% better use of the available evaporation heat A considerable contribution to our environment age 16

17 Summary Remember: ü ü ü The design of a steam turbine is defined by the process requirements of the steam parameters at the inlet and outlet (thermal capacity of the steam). Fixed geometry of the blade channel with precise shape and angle of the blade profiles ensure best use of the thermal energy to mechan. rotation. The highest efficiency of the steam turbine is in the design load point and is thus predetermined from the (original) process specifications. Conclusion: ü Any changes in plant process can have influence to the efficiency of the steam turbine and consequently on the overall process. ü Improvement and optimization of the overall plant process also means to risk a critical "side view" on the steam turbine. age 17

18 Thank you very much for your kind attention age 18

19 Contact page Erich Steiner Head of Service-Engineering for Industrial Steam Turbines Siemens Energy Service / Austria / E-S SO Siemensstrasse Vienna Austria hone: +43 (0) Fax: +43 (0) Mobile: erich.a.steiner@siemens.com siemens.at/future-of-energy age 19