ADVANCES IN HIGH PRESSURE COGENERATION

Transcription

1 ADVANCES IN HIGH PRESSURE COGENERATION BATTERY IN SESHASAYEE PAPER PLANT T. G. Sundara Raman & R. Thirumurugan Seshasayee Paper and Boards Limited 9 th ENERGY EFFICIENCY SUMMIT 2 EnCon in Thermal Systems COANY PROFILE Established in the year 96 Started with a production of 2, tonnes of paper/year SPB produces now ~,2, tonnes of paper/ year 2 High Pressure Cogeneration Plants with state of the art technology Present Gross turnover is about Rs 5 million An ISO-9 / ISO-4 / OHSAS organisation Two projects are under DVR Stage for CDM/VCS CII Chennai 4 Sep. 2 CHOICE OF HIGH PRESSURE STEAM High pressure Steam (5 bar) Low Specific Steam Consumption - SSC (in other words, more power generation per unit ton of steam) Flexibility to produce more steam or more power High cycle efficiency SSC (Te/Mwh) Impact of Steam Pressure on SSC Steam Pressure (bar) MERITS OF HIGH PRESSURE COGENERATION Low cost of total energy generation & conversion Reduced dependence on grid power Flexibility in operation depending on steam & power needs during all time of the year Quality steam at desired levels requirement for process

2 H.P. COGENERATION Pulp & Paper Industries Sugar Plants Boiler # SPECIFICATIONS OF THE 2 HP COGEN UNITS CPP AFBC Boiler Chemical Recovery Cogen Parameter Boiler # Type 7 Rated Steam Evaporation 6 kg/cm² SOP Chemical Recovery Boiler 83(Phase) I4(Phase2) 65 kg/cm² Petrochemical Industries 5 C 35 C SOT Feed inlet temperature 465 C 35 C Fertilizer Units Imported coal Fuel Black 7% solids concn. Chemical Industries 2 MW- DEC STG.5/4. kg/cm² E/E2 6 MW- EBP.5/4.5 kg/cm².9 ata Condensing MW Capacity 6 MW(Phase) / 6 MW(Phase2) POST MDP [PHASE I] FLOW CHART Weak Black Liquor from Pulp Mill Falling Film Evapo rato r GRID IORT Strong Black Liquor 7% Concen tration New CRB 65 kg/cm tpd CPP AFBC# 6 kg/cm 2 95 tph 7 tph EBP 6MW STG DEC 2MW STG 6.5 tph 64 tph 8 MW 22 tph 42 tph. ata 7.5 MW.5 MW kg/cm 2 Steam Header 4 kg/cm 2 Steam Header CW Station Consu mption To Process Station Consu mption To Process Total Power : 26 MW 2

3 7 AFBC High Pressure BOILER Atmospheric Bubbling Fluidised Bed Combustion Boiler with economizer & flue gas air heater High pressure (6 bar) steam unit 7 Steam Generation 5ºC Steam Temperature Enviro Coal as Fuel High Bed Temperature :95-97 C 35ºC Feed water Temperature Highest Efficiency (~ 84% on GCV) 3 Field ESP ( SPM <2 mg/nm3) Lower N 2 O (GHG) for a FBC unit Type Design Actual Gain Efficient Turbo Generators BHEL STEAM TURBINES 2 MW Double Extraction Condensing 97.6 % 97.9 %.7 MW 6 MW Extraction Back Pressure 97.7 % 98. %.6 MW CPP- COGEN LADDER CHART 92 MW FUEL (COAL). 76 BOILER POWER STG in 5 MW C 8½ LP 2 73 MW STG ~G LP C EXH 3

4 CPP II [Recovery] COGEN LADDER CHART ENERGY DISTRIBUTION ACROSS 6 MW STG 8MWt Black Liquor Solids 65½ Boiler MSH 8 MW LP LP 4 Turbine Extraction-Exhaust Steam Range ZONE 2 MW STG 6 MW STG E [ ] -3-6 E2 [LP] Condensing 25-5 X 5 POWER ENHANCEMENT SCHEME -First of its kind With reduction in E steam extraction flows ( as related to design flow ), the temperature at turbine nozzle increases relating to lower Electrical Power conversion and higher de-superheating Hence Splitting E ( M.P. steam extraction ) flows between the 2 steam turbines to be minimized to the extent practicable. 6 4

5 E Nozzle Steam vs Saturation. Temperatures E [ Steam]- Energy in Steam to DSH Low Load,MW High Load,MW E2 Nozzle Steam vs Saturation. Temperature E2 [LPSteam LPSteam]-Energy in Steam to DSH Low Load MWt High Load MWt

6 POWER ENHANCEMENT SCHEME CONCEPT Splitting E ( M.P. steam extraction) flows between the 2 steam turbines to be minimized. Objective is to ensure entire E flow through one of the 2 STGs Accordingly split E2 (L.P. steam extraction) flow between the 2 steam turbines POWER ENHANCEMENT SCHEME [PES] E ( M.P. steam extraction) flow had been reduced in 6 MW steam turbine from 2 to 6 as of now ; this flow had been added in E of 2 MW steam turbine. Accordingly E2 (L.P. steam extraction) flow is being adjusted between the 2 steam turbines. In case of E2, there is hardly any impact ; hence the above philosophy of splitting is not taken up. 2 Thus the overall and LP steam flow rates are left undisturbed. 22 COGENERATION BATTERY COMBINED STEAM & POWER GENERATION RECORD POWER ENHANCEMENT OPERATIONAL COARISON 2 Apr H.P.Steam Te 98 Power Gen. MU 645 Spec. Steam Consn. Te/MW Apr Spec. Steam Consn. Te/MW 6.83 Power equiv. units E-equiv. TPD May May July July Aug Aug*[ [-28]

7 GHG Reduction through PES 2 Apr May July Aug Power equiv. units CO2 [equiv.] Te POWER ENHANCEMENT & GHG REDUCTION { -line : April 2 } April May July August Power' units CO2 eq. T E TPD Advanced Steam Pipe Insulation [5ºC reduction] Energy MWt RECOMMENDATIONS & CONCLUSIONS Maximize combined cycle efficiency in electrical power with either of the turbines acting as slave using Power enhancement scheme [PES]. Main steam temperature drop from Boiler to turbine to be minimal ( through quality and adequate insulation) say 5 to 6 C. The resultant saving in heat in HP steam shall be gainfully converted to Power at no extra fuel input. With PES in place, GHG reduction would be of the order of 5 Te CO2 equiv. 28 7