Loviisa 3 unique possibility for large scale CHP generation and CO 2 reductions Nici Bergroth, Fortum Oyj FORS-seminar 26.11.2009, Otaniemi
Loviisa 3 CHP Basis for the Loviisa 3 CHP alternative Replacement of heat generated with fossil fuels in the Helsinki metropolitan area (i.e. Helsinki, Espoo and Vantaa) thermal energy consumption (district heat) 11-12 TWh per year Maximum district heat power approx. 1 000 MW Large reduction of carbon dioxide emissions approx. 4 million tons per year (6 % of the entire CO 2 emissions in Finland) Higher plant efficiency reduction of heat discharge to the sea around Hästholmen island
Loviisa 3 CHP Cumulative probability distribution of heat consumption in Helsinki metropolitan area for 12 TWh annual consumption 3500 3000 2500 p(> 1000 MW) = 0,62 Power (MW) 2000 1500 12 TWh 1000 500 Availability > 0,91 0 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 p
Loviisa 3 CHP Dependency of heat generation power and outdoor temperature 2500 20 2000 15 Power MW 1500 1000 10 5 Outdoor Temperature Power Outdoor Temperature 500 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month -5
Loviisa 3 CHP safety requirements Design of a NPP for combined heat and power generation General design requirement The cogeneration plant shall be designed to prevent transport of any radioactive material from the nuclear plant to district heating units under any condition of normal operation, anticipated operational occurrences, design basis accidents and selected severe accidents. Additional safety requirements the heat generation design solutions have to be such that they will not increase the safety risks of the NPP the heat transport system should not pose unacceptable safety hazards to the population and environment
Loviisa 3 CHP technical implementation Heat generation Maximum district heat power approx. 1 000 MW net electrical power loss approx. 1/6 of the district heat power generated full condensing mode possible Implementation entirely separate closed district heating circuit steam extraction from turbine (NB. cooling water not involved) District heat water temperature hot leg 120 C cold leg 60 C
Loviisa 3 CHP technical implementation Steam extraction from turbine Optimisation to minimise power losses at generator terminals after an intermediate pressure turbine from low pressure turbine one or several extraction points redesign vs. design of new turbine District heating circuit connection Two physical barriers for confinement of radioactivity direct connection to the turbine plant processes possible in PWR BWR requires an intermediate circuit Pressure level design - leakages always towards turbine processes
Loviisa 3 CHP technical implementation Heat generation connection in PWR
Loviisa 3 CHP technical implementation Heat generation connection in BWR
Loviisa 3 CHP technical implementation District heat pipeline Length over 75 km (Loviisa eastern Helsinki) 2 x Ø 1200 mm pipes, PN25 bar, Q = 4-5 m 3 /s 4-7 pumping stations total pumping power needed tens of MWs compensates for heat losses Instrumentation and control district heat water temperature or flow rate Heat accumulator needed, heat distribution to the local district heat network via heat exchangers
Loviisa 3 CHP district heat pipeline Implementation of district heat pipeline Preliminary alternative rock tunnel (A = 30 m 2 ) stable conditions positive maintenance aspects Alternatively surface installation is being investigated
Loviisa 3 CHP district heat pipeline District heat tunnel profile Bedrock soundings done on tunnel route At max. tunnel located 95 meters under sea level
Loviisa 3 CHP district heat transfer system District heat transfer system Analysis of consequences of district heat pipeline transients pipeline leakages pump failures Transfer system including rock tunnel modelled with APROS (Advanced process simulation tool) preliminary flow chart pressure balancing valves and pumps Connection of the heat transfer system model eventually with the model of the whole plant for advanced accident analysis
Loviisa 3 CHP conclusions CHP generation has been presented in the Loviisa 3 DiP application as an alternative Possibility to reduce CO 2 emissions significantly and decrease local environmental impacts Can be implemented in both PWR and BWR Positive statement in STUK s preliminary safety assessment District heat tunnel will require a separate EIA Requires co-operation among the heat producers in Helsinki metropolitan area Must be economically feasible for all parties Political question (both on local and national level)