STANDARD TECHNICAL FEATURES OF BTG SYSTEM FOR SUPERCRITICAL 660/ 800 MW THERMAL UNITS Government of India Ministry of Power Central Electricity Authority New Delhi – 110066 JULY, 2013
STANDARD TECHNICAL FEATURES OF BTG SYSTEM FOR SUPERCRITICAL 660/ 800 MW THERMAL UNITS Government of India Ministry of Power Central Electricity Authority New Delhi JULY, 2013
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units STANDARD TECHNICAL FEATURES OF BTG SYSTEM FOR SUPERCRITICAL 660/800 MW THERMAL UNITS CONTENTS Chapter/ Clause No. Description Page No. Section-1: General 1. Introduction 1 1.1 Supercritical technology 1 1.2 Implications on design/ construction 2 2. Operating Capability of Plant 6 3. General Technical Requirements 7 4. Layout Considerations 9 5. Performance Guarantees 12 5.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 7.3 Dampers 60 Coal Preparation and Firing System 62 8.1 General 62 8.2 Bunker shut off gates, RC feeder inlet & outlet gates 62 8.3 Coal chutes 62 8.4 Raw coal feeders 63 8.5 Coal pulverizers 64 8.6 Pulverised coal pipes 68 8.7 Coal burners 69 8.8 Primary air fans 71 Fuel Oil Firing System 73 9.1 General 73 9.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units Section 3: Steam Turbine Generator & Auxiliaries 12. Steam Turbine 87 12.1 General 87 12.2 Turbine casing 90 12.3 Turbine rotor 91 12.4 Nozzles and blades 91 12.5 Bearings 92 12.6 Turning gear 92 12.7 Gland sealing system (steam turbine and TD-BFP drive) 92 12.8 Steam admission valves (emergency stop, reheat stop, interceptor stop valves and control valves) 93 12.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 14. Feed Water Heating Plant and Flash Tanks 107 14.1 General requirements 107 14.2 Low pressure heaters and drain cooler 108 14.3 Deaerator 109 14.4 High pressure heaters 110 14.5 Flash tanks 111 Boiler Feed Pumps 113 15.1 Number and type 113 15.2 Pump sizing 113 15.3 Design requirements 114 15.4 Operational and maintenance requirements 116 15.5 Mechanical seals 117 15.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 18.3 Thermal insulation 181 18.4 Refractories 184 Steam Turbine HP-LP Bypass System 185 19.1 Purpose 185 19.2 General requirements 185 20. Auxiliary Steam Pressure Reducing & Desuperheating System 187 21. Equipment Cooling Water (ECW) System 189 21.1 General 189 21.2 System requirements 189 21.3 Design requirements 190 21.4 Sizing criteria 193 Condensate Polishing Plant 194 22.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units SECTION -1 GENERAL
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER 1 INTRODUCTION 1.1 Supercritical Technology The current thrust of thermal power development in the country is on supercritical units so as to improve the conversion efficiency and reduce carbon footprint. A number of power generation utilities are going for supercritical technology and a large number of supercritical units of 660/800 MW size are already under construction.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units document. The Central Electricity Authority (Technical Standards for Construction of Electrical Plants and Electric Lines) Regulations, 2010, stipulate the maximum turbine cycle heat rate for supercritical units as 1850 kcal/kWh with turbine driven BFP and 1810 kcal/kWh with motor driven BFP and this would require adoption of minimum steam parameters of 247 kg/cm2, 565/ 5930C at turbine inlet.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units The vertical water wall design uses rifled tubing for improved cooling effect with uniform temperature across the walls and is also operating satisfactorily. Its advantage lies in ease of construction and maintenance. Keeping in view the fact that various manufacturers have standard water wall configurations which are proven, both the options viz. spiral and vertical tube designs have been included. 1.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units inventory management. For large size supercritical units also, the same configuration i.e. 2x50 % TD-BFP and 1x50 % MD-BFP has been adopted. Alternate provision of 3x50% MDBFPs has also been suggested. However, this shall be resulting in increased auxiliary power consumption and reduced net unit output. 1.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 1.2.9 Materials High steam pressure and temperature parameters adopted in supercritical boilers require use of improved materials to withstand the severe operating conditions. Gas side corrosion & erosion and steam side scaling and exfoliation are some of the major issues in material selection for coal-fired boilers.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER - 2 OPERATING CAPABILITY OF PLANT 2.1 The plant shall be designed to operate as a base load station and shall have a design life of minimum twenty five (25) years. However, continuous operation under two shift and cyclic modes during certain periods is also envisaged. The design of the plant equipment and control system would permit participation of the plant in automatic load frequency control.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER - 3 GENERAL TECHNICAL REQUIREMENTS 3.1 All equipment, systems and work covered herein shall comply with all latest statutes, regulations and safety codes, as applicable in the locality where the equipment will be installed. 3.2 The design of Steam Generator shall meet or exceed all the requirements of latest editions of Indian Boiler Regulations (IBR).
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 3.9 All power cycle pumps shall comply with the latest applicable recommendations of Hydraulic Institute Standards (U.S.A.) or approved equivalents. 3.10 Stand-by equipment of all the auxiliaries which have direct impact on operation and safety of the plant shall be designed for auto start up, on failure of running equipment with minimum time delay and without runback on unit load. 3.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER - 4 LAYOUT CONSIDERATIONS 4.1 The broad salient features of the layout arrangements of various equipment in the main plant building housing the turbine- generator and its auxiliaries and steam generator area are given as hereunder: 4.1.1 The arrangement of the turbine- generator in the main plant building shall be of longitudinal type.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 4.1.7 There shall be no regular basement floors in main plant building and mill bunker bay building. Also, the local pits/trenches in main plant building/ mill bunker bay building/ boiler/ ESP area shall be avoided as far as possible. 4.1.8 The dearator shall be located in the BC bay at an appropriate elevation so as to meet the NPSH requirement of boiler feed pumps.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 4.1.15 Layout of facilities and equipment shall allow removal of generator transformers, station transformers and unit auxiliary transformers without disturbing structure, equipment, piping, cabling, bus ducts etc. routed in the area. 4.1.16 Clear approach width of minimum 10m with clear height of 8m shall be provided at the front and rear of ESP. 4.1.17 Trestles to be provided for routing of cables, pipes etc.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER 5 PERFORMANCE GUARANTEES 5.1 General Requirements 5.1.1 The equipment shall meet the ratings and performance requirements stipulated for various equipment. The guaranteed performance parameters shall be without any tolerance values and all margins required for instrument inaccuracies and other uncertainties shall be deemed to have been included in the guaranteed figures. 5.1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units guarantees, even after the above modifications/ replacements within ninety (90) days or a reasonable period allowed by the purchaser, after the tests have been completed, the purchaser will have the right to either of the following: i) For Category-I Guarantees Reject the equipment/ system/ plant and recover the payment already made OR Accept the equipment/ system/ plant after levying Liquidated Damages as stipulated.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 5.2.5 Turbine Cycle Heat rate in kcal/kWh under rated steam conditions, design condenser pressure with zero make up at 80% TMCR load (for reference). 5.2.6 Continuous TG output at 105% TMCR load under rated steam conditions, design condenser pressure with zero make-up. Note: The condenser pressure measurement while conducting the guarantee tests from clause 5.2.4 to 5.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 5.4.2 Start up time (for one unit only) Start-up time (upto full load), and loading capabilities for the complete unit (boiler, turbine and generator together) for cold start, warm start and hot start conditions as agreed shall be demonstrated, ensuring that the various turbine operational parameters like vibration, absolute and differential expansion, eccentricity and steam metal temperature mismatch etc.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 5.4.6 5.4.7 Electrostatic precipitator i) The ESP air in leakage shall not be more than 1% of total gas flow at ESP inlet at the guarantee point condition and shall be demonstrated. ii) The maximum pressure drop through the ESP at the guarantee point flow condition shall not exceed 25 mmwc and shall be demonstrated.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 5.4.12 Furnace exit gas temperature (FEGT) It shall be demonstrated that maximum furnace exit gas temperature (FEGT) shall be minimum 60 deg C below the minimum initial deformation temperature (IDT) of ash. A comprehensive thermal performance test (TPT) shall be conducted for this purpose on one unit. FEGT shall be demonstrated through such TPT by indirect measurement. 5.4.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units v) When one half of the condenser is isolated, condenser shall be capable of taking at least 60% T.G. load under TMCR conditions. vi) The design capacity of each vacuum pump in free dry air under standard conditions at a condenser pressure of 25.4 mm Hg (abs) and sub cooled to 4.170C below the temperature corresponding to absolute suction pressure shall be demonstrated.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units Under all above conditions, while passing the required steam flows as per the relevant heat balances, the condenser should be able to swallow the entire steam without increasing the exhaust hood temperature and condenser pressure beyond the maximum permissible values. The same shall be demonstrated. 5.4.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units e) For air motors it shall not exceed 95 dBA. f) For pressure regulation valves & steam generator water drain control valve it shall not exceed 90 dBA. Corrections for background noise shall be considered in line with the applicable standards. 5.4.23 Condensate polishing plant i) Effluent quality at outlet of each vessel at its rated design flow and design service length between two regenerations.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units a) Test loads b) Test conditions c) d) e) f) g) ii) 100% TMCR and 80% TMCR. Boiler operating at rated steam parameter, excess air, coal fineness and firing design coal. Ambient 27oC dry bulb temperature and 60% relative conditions humidity. The reference air temperature for the efficiency guarantee/ testing shall be taken as 27oC at APH inlet (without consideration of heat credits). No.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) The following correction curves shall be applicable for performance test of the ESP: a) Inlet flue gas flow. b) Inlet flue gas temperature. c) Inlet dust loading. d) Sulphur content of coal. 5.5.3 Auxiliary power consumption The unit auxiliary power consumption shall be calculated using the following relationship: Pa = Pu + TL Pa = Guaranteed Auxiliary Power Consumption.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units If they differ by more than 0.25%, additional test run(s) shall be made at the same point until corrected heat rates of atleast two test runs agree within 0.25% and achieved heat rate shall be calculated as average of test run points satisfying the above criterion. v) The performance guarantee test shall be carried out after successful completion of trial operation.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units SECTION-2 STEAM GENERATOR & AUXILIARIES
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER 6 STEAM GENERATOR 6.1 Type 6.1.1 The Steam Generator shall be of single pass (Tower type) or two pass type using either spiral wall (inclined) or vertical plain/ rifled type waterwall tubing. 6.1.2 The Steam Generator shall be direct pulverized coal fired, top supported, single reheat, radiant, dry bottom, with balance draft furnace and shall be suitable for outdoor installation.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 6.3 Fuels 6.3.1 Coal i) The primary fuel for the Steam Generator(s) shall be coal (coal characteristics of design coal, worst coal, best coal and range of coal for the project to be considered for boiler design). ii) The Steam Generator shall be designed to give the guaranteed efficiency when firing the coal having the characteristics for design coal.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 6.4.2 Minimum load without oil support for flame stabilization The design of Steam Generator shall be such that it does not call for any oil support for flame stabilization beyond 40% BMCR load when firing any coal from the range specified, with any combination of mills/ adjacent mills in service. 6.4.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 6.4.5 Operation with HP and LP turbine bypass system i) With HP-LP bypass system in operation, the unit shall be capable of smooth start-up, fast loading & house load operation. ii) Steam Turbine trip will call for boiler operation in HP/LP bypass mode.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) The ducting and supporting structure to be designed to take care of future Guillotine damper to be installed between the two tap offs before chimney. 6.4.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units Maximum steam side temperature 100C imbalance in the LHS & RHS at boiler outlet (from the average) viii) Minimum load with separator running dry 30-40 % TMCR (As per manufacturer’s proven practice) ix) Header pressure unbalance (steam side) 6% x) Air ingress from furnace bottom Hopper As per manufacturer's predictions vii) 6.4.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) The enclosure integral with boiler (except air heaters) shall be formed by water/steam cooled tubes on all the four sides, roof and bottom. The furnace water walls shall be formed using either spiral (helical) wound tubes or vertical plain/rifled tubes. The roof of single pass/tower type boilers could be formed by gas tight metal sheeting of appropriate material.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) The casing/ pent house and its supporting system shall be capable of taking additional loads due to accumulations of ash upto 300 mm height or actual expected (in between two overhauls of the units), whichever is higher. This additional load is over and above other loads considered for casing design. The ash density for the purpose of ash loading shall be at least 1350 kg/m³.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units v) 6.5.3 The working fluid temperature to be considered for design of boiler tubes, headers, separators and other pressure parts upto first stage of attemperation, shall be as maximum predicted/ expected fluid temperature in these pressure parts plus margins as per IBR.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Definition of Acronyms Used in (i) Above a) NHI & furnace plan area b) 1. Net heat input (NHI) or heat available in furnace is obtained by considering the calorific value of the fuel minus the radiation losses, loss due to unburnt combustible, moisture in air, moisture in fuel, moisture formed by combustion of H2 in the fuel plus the sensible heat of combustion air (primary plus secondary air), all above 270C. 2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units Furnace residence time shall be calculated by dividing the furnace volume between the center line of top coal burner and furnace exit plane by the flue gas volume at mean gas temperature in the above furnace volume. iii) Furnace/ evaporator shall be designed for variable pressure operation over 30% to 100% BMCR load range. iv) Water/ steam walls shall be of membrane wall construction and shall be made of seamless tubes.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units xi) Minimum tube thickness at the bends in no case shall be less than the minimum tube thickness for the straight tubes calculated in the manner described above. For this purpose appropriate thinning allowance shall be considered while calculating the thickness of the bends xii) In case water wall orifice are provided, these should be supplied with indexing holes and index pins. xiii) Other Provisions 6.5.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 6.5.5 ii) Design Temperature Maximum fluid temperature plus margin as per IBR. iii) Design Pressure 1.05 times the maximum operating pressure or as required by IBR/ other international codes, whichever is higher.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units The insulation shall have sufficient dielectric strength to withstand rated phase to earth voltage in slot portion and phase to phase voltage in end windings. The insulation material shall not have any tendency for plastic deformation even under extreme operating condition like the conductor temperature, mechanical forces, vibrations etc.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units c) Maximum allowable tube 400C below oxidation metal limit for the skin temperature tube metal. d) Means of temperature control: 1. Superheaters Spray water attemperation, (utilising water tapped off from downstream side of HP heaters or intermediate banks of economizer or economizer outlet). Tapping of spray water upstream of top HP heater is not allowed. 2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) Minimum transverse tube pitching in the direction of gas flow path: 1. 600 mm for banks/ sections placed in areas where gas temperature exceeds the FEGT (MHVT) value. 2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 2. For balance of the tubes in the bank: Erosion allowance of 0.6 mm (min.) over and above the calculated thickness as per IBR shall be provided. 3. Minimum tube thickness at the bends in no case shall be less than the minimum tube thickness for the straight tubes calculated in the manner described at (1) and (2) above.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units d) Maximum permissible spray attemperation flow (as percentage of main steam flow at superheater/ reheater outlet) 1. Superheater attemperation 8% of main steam flow at superheater outlet. 2. Reheater attemperation 3% of steam flow at reheater outlet (0% under normal operating conditions). Above permissible limits shall be applicable to all boiler loads with any combination of mills in service and shall be guaranteed.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) Access openings alongwith air/ gas tight hinged doors shall be provided for approach to above maintenance spaces without any hindrance from hanger tubes. 1. All access door shall be of 450mm x 450mm size (minimum). 2. Access doors 800 mm above the nominal floor level shall have access platform. 3. Hanger tubes of horizontal banks shall have access opening for crossing over.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units e) Maximum allowable tube metal skin temperature f) Maximum depth of tube banks/ sections in the direction of gas flow g) Thermal shock aspect ii) Minimum tube thickness at the bends in no case shall be less than the minimum tube thickness for the straight tubes calculated above including erosion allowance. For this purpose appropriate thinning allowance shall be considered while calculating the thickness of the bends.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units g) If the Steam Generator has the flue gas down-flow section with horizontal tube banks, the top most row shall be shielded to reduce erosion. h) Headers shall be located external to gas path and shall be completely drainable. If locating headers in gas path becomes unavoidable, than suitable erosion shields/ protectors must be provided.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) Space Provision Space provision shall be kept on gas inlet side for installation of atleast 20% additional economizer surfaces, if required, in future. Structure/ hanger design shall be suitable for loads due to these additional surfaces (filled with water) also. 6.5.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units h) Minimum flue gas exit 50C above acid dew point of flue gas. temperature (for complete range of specified fuels) i) Air leakage (at 100% 10% of the flue gas weight entering airTMCR load for complete heater.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units d) Air heater drive 1. One (1) no. peripheral AC drive or central AC drive as per OEM’s proven practice with gear box and automatic clutching/ declutching facility. 2. One (1) no. auxiliary air motor drive with automatic clutching, declutching facility for rotation during non availability of A.C. drive system. 3.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units c) Air-preheaters ii) 2. Short rotary, multiple nozzle, retractable type for low temperature zones. Power driven swinging arms soot blower, or retractable multi-nozzle soot blowers. Soot blowing system shall be: a) capable of effectively removing deposited ash from steam generator heat transfer surfaces with on- load cleaning devices. The soot blower design shall be of self draining type.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units platforms, stairs & ladders shall be provided in accordance with following requirements: ----------------------------------------------------------------------------------------------------------------------------------- Description Minimum clear width* ----------------------------------------------------------------------------------------------------------------------------------- a) b) c) d) Main access walkways St
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units v) All manholes, all access doors, all observation ports, all instruments including flame scanners, flame cameras & ash level indicators, junction boxes for control and instrumentation, all instrument test/ sampling points including that for PADO and all dirty pitot tube & coal sampling points shall be accessible from main access walkway/ platforms.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) APH baskets: Adequate platforms with proper approach near APH(s) for storage of at least 40 nos. baskets for each APH. Weight of stored APH baskets shall be accounted in the structure and platform design.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units f) xv) All areas subject to lube oil or chemical spills will be provided with curbs and drains. Two main stairways shall be provided one on each side of the steam generator. One stairway shall extend continuously from grade to the highest operating level and the other shall extend continuously from grade to the boiler roof. Steel framing for penthouses for each stairway shall be provided.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER 7 DRAFT FANS, DUCT WORK AND DAMPERS 7.1 Forced Draft and Induced Draft Fans The forced draft (FD) and induced draft (ID) fans shall be capable of maintaining balance draft conditions in the furnace upto 60% BMCR load with any one or both FD fans and any one or both ID fans in operation and above 60% BMCR load with both FD fans and both ID fans while firing the specified range of coals. 7.1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 7.1.2 Fan sizing criteria- Additional The fans shall also fulfill following sizing criteria in addition to those mentioned at 7.1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Both FD fans and both ID fans shall operate with highest possible efficiency which shall be nearly equal at the 100% TMCR and test block points depending upon margin on flow and pressure. iii) Fan components alongwith servo/ blade pitch control mechanism shall be designed to withstand and continuously operate with the maximum air or flue gas temperature that these fans will be required to handle.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units c) Fan rotational 1500 rpm (max.) speed d) Air/ flue gas flow blade pitch control control e) Fan critical speed not less than 125% of fan maximum operating speed f) Fan component to withstand torsional design* stresses three (3) times the normal/ full load motor torque at all speeds g) Fan casing Carbon steel, 6.00 material & mm (min.) thickness h) Fan Housing Shut off head of fan design pressure 750 rpm (max.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) Fan Balancing The fans shall be statically and dynamically balanced before shipment and balancing of each fan shall be checked and adjusted at site, if necessary. 7.1.5 Flow measuring devices i) The draft plant shall include flow measuring devices in the air system for total air flow measurements and control with adequate number of tapping points.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units The above velocities shall not be exceeded even in case of operation with one stream of ID, FD, PA fans and air heater operation at 60% of BMCR load. 7.2.2 Loads for duct and structure design The duct design shall take into account following loads all occurring together: i) Wind loads. ii) Dead weight including weight of insulation, lining, wash water and the vertical live load.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units i) Minimum 8 mm thick steel plates for gas ducts from APH outlet to ESP inlet and minimum 6 mm thick steel plates for gas ducts from ESP outlet to the chimney inlet. ii) Minimum 5 mm thick steel plates for air ducts. iii) A corrosion allowance of 1.5 mm shall be considered for stress calculation for the flue gas ducting. iv) Duct stiffening shall be by means of rolled sections.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 7.3 Dampers 7.3.1 Power operated gas tight isolation dampers along with their drives shall be provided at all locations required for carrying out internal repair and maintenance of pulverizers, electrostatic precipitators and induced draft fans when the steam generator is on load.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 7.3.7 The auto regulating dampers shall be capable of being operated between 20% to 80% opening as per the optimal requirements of control systems to achieve stable, steady and smooth automatic control of the plant and processes under all operating conditions. 7.3.8 There shall not be any backlash, play, etc. with linkage mechanism, actuator and final control element. 7.3.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER 8 COAL PREPARATION AND FIRING SYSTEM 8.1 General 8.1.1 Coal preparation and firing system shall commence with the shut-off valve at raw coal bunker outlet and shall include raw coal feeders, coal pulverizers, primary air & seal air fans, pulverized fuel pipes, coal burners, coal valves and associated auxiliaries. 8.1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units i) Chutes between outlet of raw coal bunker shut off valves and inlet to the coal feeders. ii) Chutes between outlet of coal feeder and inlet to the pulverizers. 8.3.2 The internal diameter of coal chutes selected shall not be less than following: Minimum I.D. Coal Chute i) Between bunker outlet gate & feeder inlet ii) Between feeder outlet & pulveriser inlet 914.4 mm 600 mm 8.3.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) Feeder accuracy a) In-situ weighing accuracy : ± 0.5%. b) Repeatability : 0.1%. c) Shall have in-built facility for calibration. v) "No coal" flow detection to be provided to stop the feeder when no coal is detected on the conveyor and when pluggage occur at feeder outlet.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Number of standby mills a) At 100% of TMCR, worst coal firing : One b) At 100% BMCR, worst coal firing : Nil c) At 100% BMCR, : One design coal firing iii) Sizing of coal pulverizers confirming to clause (i) and (ii) above shall be under following conditions all occurring simultaneously: a) Maximum permissible mill 90% or the mill loading achievable loading for deciding mill corresponding to the near worn out c
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 8.5.5 Mill sound level shall not exceed specified values. While selecting lagging, background noise from adjacent mills, drive system and other secondary & stray noises shall be taken into account. 8.5.6 Seal air system i) 2x100% centrifugal seal air fans common for all the mills of one Steam Generator unit shall be provided.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 8.5.11 Materials of construction The material of construction of wear parts shall be selected taking into account highly abrasive nature of coal resulting from coal contamination with silica sand and Alpha-quartz as specified.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 8.5.14 Tapping points shall be provided on each pulverized coal pipe at mill outlet for coal sampling as per ISO 9931. 8.5.15 One (1) no. Rota probe shall be provided for each steam generator for coal sampling as per ISO 9931. 8.5.16 Four (4) nos. Dirty Pitot tubes shall be provided for each steam generator for measurement of coal-air velocity in coal pipes. 8.5.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 8.6.7 Calculated static loading of each support of the PC pipes shall be increased by at least 25% to arrive at the design load, to take care of the shock loading occurring in the pipe work under abnormal conditions of operation. 8.6.8 The guide plates, wherever provided in the coal pipe, shall be removable, and access to them shall be obtained through detachable cover.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) The coal burner design shall ensure a steady log mean density of coal air mixture distribution as it enters the combustion zone without allowing the coal dust to settle down. iii) The burner design shall minimize erosion. The burner shall be designed to ensure smooth variation in the fuel flow without affecting the air fuel ratio.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 8.8 Primary Air Fans 8.8.1 Fan design i) 8.8.2 Type of fan : Two stage, constant speed, variable pitch, axial type. ii) No. of fans per unit : Two iii) Type of fan blade : Streamlined/ aerofoil bladed type designed to withstand high bending and axial load.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) The system resistance curves shall always be sufficiently below the fan stall line. iii) Best efficiency point shall be close to 100% TMCR operating point of fan. 8.8.4 Fan control system i) Fan flow control shall be by blade pitch control. The final control element shall be electrically/ pneumatically operated.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER 9 FUEL OIL FIRING SYSTEM 9.1 General Fuel oil preparation and firing system shall comprise of heavy fuel oil (HFO/LSHS/HPS) firing system and light diesel oil (LDO) firing system. 9.1.1 Heavy fuel oil firing system Heavy fuel oil (HFO) shall be used for initial start-up, low load operation and as secondary fuels for pulverized coal flame stabilization at the startups/ low load operation.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 9.1.4 Fuel oil condensate system Condensate from complete fuel oil plant shall be brought to a common condensate flash tank in fuel oil unloading area. Drain from this condensate tank shall be connected to nearest station drain. 9.1.5 Oily water drain system The oily waste water drains from each steam generator area shall be collected and suitably treated in an oil separator.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) Pump HIS, ASTM, ASME or equivalent design/ construction code v) No. of One working 2(1W*+1S) 2(1W+1S) pumps for each SG for each plus one drain oil common tank standby vi) No. of oil One working heaters for each SG plus one common standby vii) Capacity of To cater to To cater to 4 m3/hr each pump 30% BMCR 7.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iii) Heater inlet fuel oil temperature for design shall be considered as 300C. iv) Heater outlet temperature shall be suitable for the viscosity requirements at the fuel oil burner tips for the grade of oil (HPS/HFO/LSHS) used. v) Maximum metal temperature of heater heat transfer surface shall be 2100C (maximum).
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 9.2.7 Oil burners Description HFO firing system LDO firing system i) Type of burner Steam atomized Air atomized ii) Burner medium iii) Burner material iv) v) vi) cooling Steam or air tip Resistant to corrosion due to fuel oils containing sodium, vanadium, sulphur, chloride etc.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units vi) Separate flame viewing opening/facility for boiler operation and for flame monitoring at each burner from out side of the boiler. Provision shall be made to keep the viewing heads cool below 750C and to keep optical system clean during firing/non firing by pressurized air. 9.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER- 10 ELECTROSTATIC PRECIPITATOR 10.1 Design Data The electrostatic precipitator(s) (ESP) of each unit shall be arranged in minimum four (4) independently operating gas streams (casings) for 660 MW unit and six (6) independently operating gas streams (casings) for 800 MW unit. Each gas stream/ casing shall be provided in twin compartments.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ix) x) xi) xii) xiii) xiv) stringent with one field out of service in each pass. ESP dust collection To be worked out efficiency (%) corresponding to outlet dust burden and inlet dust burden as above. Minimum specific collection area (sca) with one field out of service in each pass (m2/m3/s) Spacing between the 300* collecting plates (centre line to centre line) transverse to the gas flow (mm) Maximum flue gas 1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units g) Minimum dust eight (8) hopper storage capacity (upto the maximum trip level based on design point conditions (while firing worst coal (with maximum ash) (in hrs) h) Minimum hopper Sixty (60) Sixty (60) valley angle to the horizontal (degrees) i) Maximum nos.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 10.5 Maintenance Requirements 10.5.1 The design of the precipitators shall allow adequate space above and between the adjacent fields to carryout necessary inspection and maintenance. A permanent walkway shall be provided at each rapper level both for the discharge and collecting plates. 10.5.2 Minimum 2.0 m wide platforms shall be provided between the two casings of the ESPs to facilitate maintenance work and minimum 1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units maximum utilisation of collection areas at the inlet and outlet. It shall be designed to minimise local velocity regions and to avoid bypassing and reentrainment of dust. To achieve the above, internal baffles etc. shall be provided. The distribution screens shall be of modular design. 10.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 10.10.2 A minimum rapping acceleration of 75 g measured normal to the plane of the plate shall be imparted on all parts of all the collecting plates. 10.10.3 The perforated plates and/or guide vanes furnished for gas distribution system shall also be provided with rapping systems. The rapping mechanism shall produce sufficient force to keep the perforated plates/guide vanes clean. 10.11 Dust Hoppers 10.11.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 10.11.5 Each dust hopper shall be provided with a high level and a low-level dust level monitor operating on proven radio frequency measurement principle. The level monitoring system shall incorporate all the necessary accessories including two nos. level switches per hopper (one for high and other for low level), each with 2 NO + 2 NC contacts, local and remote signaling lamps and high and low level alarms.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 10.12.6 The precipitator shall be guided, anchored or supported by lubricated plates/roller bearings at such locations as may be required to limit precipitator, ductwork or expansion joint forces or movement. Each casing shall be restrained to grow in a radial direction from the anchor point. In case lubricated plates are used these shall be covered under all conditions of precipitator movements by 1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER – 11 VOID
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units SECTION-3 STEAM TURBINE GENERATOR & AUXILIARIES
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER - 12 STEAM TURBINE 12.1 General 12.1.1 Type The steam turbine shall be tandem compound, single reheat, regenerative, condensing, multi-cylinder design with separate HP, separate IP and separate LP casing(s) OR combined HP-IP and separate LP casing(s), directly coupled with generator suitable for indoor installation. HP turbine shall be of double casing design.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units temperature at inlet to : 330C1 ix) Cooling water condenser x) Maximum design condenser pressure : 77 mm Hg (abs)2 xi) Turbine speed : 3000 rpm. xii) Frequency variation range around rated : (-) 5% to (+) 3% frequency of 50 Hz (47.5 Hz to 51.5 Hz). xiii) DM water make up to thermal cycle under : 1% of throttle TMCR condition steam flow. xiv) Final feed water temp.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units manufacturer. In such case VWO shall mean wide open condition of the turbine main control valves and the overload valves. ii) The turbine- generator set shall be capable of continuous TMCR output under rated steam conditions, 89 mm Hg (abs)3 condenser pressure, 1% make-up and 47.5 Hz grid frequency.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units vi) House- load Operation: The TG set shall be capable of operating on House load using HP-LP bypass system during sudden total export load throw off. Unit shall not trip on overspeed in the event of total export load throw-off. vii) No. of Start- ups: Expected number of turbine generator start-ups during design life of minimum 25 years shall be as under.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Steam tight horizontal joints with metal to metal contact or as per proven practice of the manufacturer. iii) All extractions shall preferably be from the lower half of casing and extraction branches shall be welded to casings except for LP casing(s) extractions which can be with either welded type or bolted type connection as per turbine manufacturer’s standard practice.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 12.4.5 12.5 Independent tuning of free standing LP turbine blades shall be provided to avoid resonance frequency in the operating frequency range of 47.5 Hz to 51.5 Hz. Bearings Adequate number of Journal and thrust Bearings shall be provided with following features: 12.6 i) Tin base babbit lining properly secured to the bearing shell. ii) Pressure lubrication.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 12.7.2 Fully automatic gland sealing steam supply system shall be provided. Gland steam condenser, designed to operate under vacuum, shall be provided to condense and return to cycle all gland leak off steam along with 2x100% capacity exhausters (AC motor drive) to remove air and non condensable gases.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units steam extraction line (except for extractions from LP turbine) including steam extraction line to BFP drive turbine. For extractions from LP turbine (except for heaters in condenser neck) and for each CRH line, one hydraulic/ pneumatic power operated/ assisted QCNRV shall be provided. 12.9.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 12.12 iii) Adjustable steady state speed regulation shall be provided between 3% to 8% of rated speed. iv) Dead band at rated speed and at any power output within rated output shall not exceed 0.06% of rated speed. Turbine Protective Devices 12.12.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 12.14 Turbine Lubrication Oil System A self contained lubrication oil system shall be provided for each TG Unit consisting of: 12.15 i) Centrifugal/ gear type, main oil pump (MOP) directly driven by turbine shaft or by an AC motor as per manufacturer’s standard practice with capacity to cater lube oil for bearings & emergency seal oil requirement. In addition to above, minimum 1x100% AC Aux.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 12.16 iv) Electric oil heater to heat oil to temperature not more than 65°C with possibility to cut heater elements in steps, applicable for centrifuge type purifier. v) Duplex type filters/strainers with stainless steel element of size 5 micron or a size suited to the requirement of the turbine.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER - 13 STEAM CONDENSING PLANT 13.1 General Requirements 13.1.1 Design, manufacturing and testing of condensing plant shall be as per Heat Exchange Institute, USA (latest). For performance testing of condenser and pumps, ASME PTC codes shall be used. The thermal, hydraulic and mechanical design shall be proven. 13.1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 13.2 Condenser 13.2.1 Construction i) Condenser shall be horizontal surface type of proven design with integral air cooling section and divided water-box construction. ii) Shell shall be of carbon steel as per ASTM SA285 Gr. C/ IS2062 Gr.B or equivalent and shall be suitable for intended service with welded construction and 16mm minimum wall thickness.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 13.2.2 x) Suitable provisions shall be made for expansion between shell and tubes. Further, suitable provisions (like sliding and fixed base plate of condenser support feet etc.) shall also be made for expansion of condenser shell under various operating conditions. xi) Air release valves and vacuum priming pumps (if applicable) shall be provided in water box of the condenser.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 13.2.3 Design parameters for condenser and associated systems i) Condenser Design Parameters a) Number of pressure stages b) c) d) e) f) g) h) Number of passes Number of shells Design cold water temp Water velocity in the tubes Maximum design condenser pressure Max.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iii) Condenser Air Evacuation System Design Parameters a) Source of vacuum pump heat exchanger Condenser cooling cooling water water b) Source of sealing water Condensate c) Source of make-up water Condensate d) Design pressure (cooling water side) for Vacuum (0.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Shaft - Carbon Steel (EN8) iii) Impeller - Nodular iron/stainless steel iv) Shaft sleeves-Nodular iron/stainless steel 13.3.8 The stand-by pump shall cut in automatically in case running pump fails or when condenser pressure falls back to a preset value. 13.3.9 Vibration levels for the pumps shall be as per “zone A" of ISO 10816. 13.4 Condenser On- Load Tube Cleaning System 13.4.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) Shaft sealing Either mechanical seals or packed type with external water sealing designed to prevent air ingress to condenser even when the pump under shut down and exposed to condenser. v) Impeller/Casing design Closed and nonover-loading type impeller with wear rings on pump bowls. vi) Materials a) Suction bell/pump casing : Cast Iron. b) Impeller/ wear rings/ shaft/ shaft sleeves :12%Cr stainless steel.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units g) Minimum recirculation Minimum recirculation flow requirements of the pump shall be not less than 25% of design flow or on set recirculation (discharge/ suction) whichever is higher. CEPs can be provided with individual recirculation line or a combined recirculation line to cater to maximum of the pumps minimum flow and GSC minimum flow as per standard proven practice of OEM.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 13.7 Drip Pumps (if applicable) 13.7.1 In case drip pumps are envisaged for cycle optimization for forward cascading of LP heater drain, then 1x100% or 2x100% Drip pumps as per proven practice of the OEM shall be provided for each unit at any one location.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER 14 FEED WATER HEATING PLANT AND FLASH TANKS 14.1 General Requirements 14.1.1 The plant shall be designed as per IS 2825 or ASME Boiler and pressure vessel code, section VIII, Division-I (Latest) and Heat Exchange Institute Standards (USA). In addition the requirements of latest edition of ASMETDP-1 code for turbine damage prevention shall also be taken care of.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 14.1.6 Each of the HP heaters, LP heaters and drain cooler shall be capable of handling 110% of the design flows from BFPs, CEPs as the case may be without undue vibrations and deleterious effects. 14.1.7 Heaters shall be provided with start-up and operating vents with orifices and relief valves. Provision shall be made for removing non condensable gases collecting on shell side individually to the condenser.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 14.2.2 Shell shall be of rolled steel as per ASTM A-516 Gr. 70. Water box channel shall be of carbon steel as per ASTM A-516 Gr. 70 and welded to tube sheet. 14.2.3 Design pressure: Tube side - CEP shut off head at 51.5 Hz and full vacuum; Shell side - Not less than maximum extraction steam pressure with minimum design pressure of 3 kg/cm2 (g) and full vacuum. 14.3 Deaerator 14.3.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 1.5 kg/cm2 with steam from auxiliary steam header. During hot and warm startup, if boiler startup drain circulation pumps are in service, deaerator pressure shall be maintained at 3.5 kg/cm2. In case startup drain circulation pumps are not in service and startup drains are routed through condenser, deaerator pressure shall be maintained 1.5 kg/cm2. Steam supply shall be from auxiliary steam header.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units extraction from CRH line, the maximum expected HPT exhaust pressure shall also be taken into account. 14.5 Flash Tanks 14.5.1 The flash tanks shall be provided receive the drains and safety valve connections from various equipments and systems. These, as a minimum, shall include Unit flash tank, turbine drain flash tanks (left & right), HP drain flash tank and LP drain flash tank. 14.5.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 14.5.6 The temperature in the flash tanks shall be maintained by using condensate spray or service water spray (for flash tanks open to atmosphere). The spray shall be automatically controlled. However, for flash tanks open to atmosphere continuous spray through an orifice shall also be acceptable. 14.5.7 Facility shall be provided for remote manual operation of the drain valves from the control room.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER - 15 BOILER FEED PUMPS 15.1 Number and Type 15.1.1 2x50% capacity turbine driven feed pumps shall be provided for each unit for normal working along with 1x50% capacity motor driven feed pump for start up purpose and to serve as standby. Alternatively, 3x50% MDBFPs shall also be acceptable. 15.1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Best efficiency point Combined flow of 2x50% TDBFPs shall be based on TMCR requirement and corresponding head. iii) Emergency point Two turbine driven feed pumps to be capable of generating the discharge pressure corresponding to steam generator highest safety valve set pressure at 100% BMCR flow.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units v) MD-BFP Lue Oil System: Common lubricating oil system shall be provided for main BFP, booster pump, motor and hydraulic coupling with one shaft driven main oil pump, 1x100% capacity AC motor driven auxiliary oil pump, one (two in case of 3x50% MDBFPs) full capacity each of working oil cooler/ lube oil cooler, oil filters/ strainers and piping, valves, fittings, instruments etc. as required.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 4. 5. 6. Balancing drum Pump shaft Shaft sleeves Stainless steel. 13% chromium steel forging. High alloy chromium chromium nickel alloy steel. or b) Booster pumps 1. 2. 3. Casing Cast steel. Impeller 13% chromium steel casting. Shaft, shaft sleeves 13% chromium steel forging.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 15.4.5 The inner pump element comprising shaft, impellers, stage casings shall be capable of being removed and replaced as a unit in not more than 15 hours without disturbing feed piping. 15.5 Mechanical Seals 15.5.1 Seals shall be of fully cartridgised design. The Seal face materials shall not be inferior to rotating silicon Carbide and stationary Carbon seal face combination.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 15.7 Drive Turbine 15.7.1 General 15.7.2 i) The drive turbine shall be dual admission or single admission type with external/ integral control valve, single cylinder, condensing type. ii) Drive turbine of BFP shall get normal motive steam from IP-LP crossover/cross around pipe or from a point as per optimized cycle during operation of turbine from full load to 60% TMCR load or below, if possible.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 15.7.3 15.7.4 15.7.5 Casing i) The casing shall be designed to withstand the maximum pressure and temperature likely to be subjected during normal operation and 25% over rated pressure for short term duration. ii) Casing shall be horizontally split at the centre line for raising and lowering the upper halves and rotor to clear off remainder of machine.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 15.7.6 15.7.7 15.7.8 Bearings i) The bearing shall be designed to avoid oil whip. Bearings shall be spherically seated, horizontally divided type, with provision of adjustment and alignment of rotor, forced feed lubricated type, lined with babbit or suitable antifriction alloy. ii) Bearings to be arranged so that these are outside drive turbine for readily accessibility.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) 15.7.9 Suitably sized hydraulic accumulators shall be provided in governing oil system to maintain system pressure, when there is a change over from one running pump to stand by oil pump. Also provision shall be made for initial air purging of the governor system. Drive turbine exhaust i) The drive turbine exhaust shall be separately piped to the main condenser of the TG unit.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER – 16 GENERATOR AND AUXILIARY SYSTEMS 16.1 Generator The turbo-generator set with all auxiliary systems and accessories shall have following features/ parameters: 16.1.1 Type 3-phase, horizontal mounted, 2-pole cylindrical rotor type, directly driven by steam turbine running at rated speed conforming to the latest version of IEC-60034-1, 60034-3 or other equivalent international standards. 16.1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units insulation under such operating conditions, but shall be lower than those permissible for Thermal Class155(F) insulation as per IEC60034. ii) Power factor iii) Terminal voltage iv) v) vi) vii) 16.1.3 Frequency Speed Short circuit ratio Efficiency 0.85 (lag) As per manufacturer’s practice 50 Hz 3000 rpm ≥ 0.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units i) Voltage variation (±)5% of rated value at rated power and rated power factor (as per IEC-60034-3). ii) Frequency variation (-)5 to (+)3% of 50Hz at rated power and rated power factor (as per IEC-60034-3). iii) Combined voltage and frequency variation 5% (absolute sum). iv) Power factor variation 0.85 (lag) to 0.95 (lead). v) Operation under unbalanced load As specified in IEC 60034 -1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 16.1.6 Design and constructional features All components of the generator to be designed to avoid resonance at any of the frequency in the operating range. i) Stator Body Enclosure To withstand without any residual deformation, any internal hydrogen explosion. ii) Stator Core Material High permeability, low loss, cold rolled silicon sheet steel segmental punchings.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) Winding overhang Overhang portion of winding to be braced and supported to withstand three phase short circuit at its terminal as per IEC-60034. c) Bushing housing To be housed in stator frame in a non-magnetic steel terminal box or as per proven manufacturer’s practice. d) Bushing Porcelain/ epoxy based material with nonhygroscopic property with suitable cooling arrangement.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units c) Jacking arrangement (if required) The hydrostatic jacking arrangement in line with turbine bearings. d) Bearing insulation At least one of the bearings to be suitably insulated with arrangements to access the insulation of the generator bearing while the machine is in operation. Insulating material to be non-hygroscopic epoxy glass laminate.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units xi) Generator Drying Arrangement Suitable equipments, accessories and controls shall be provided to enable drying out operation of the generator as per manufacturer’s standard and proven practice.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units xiii) Shaft grounding and voltage monitoring Shaft riding brushes for shaft grounding and voltage monitoring system complete with all software and hardware to be provided as per manufacturer’s proven practice.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) Dryer type Reactivation/ Refrigeration/ Manufacturer’s practice. v) 3-way valve used along with the drier for interconnecting the H2 and air line (as applicable) preferably have mechanical interlocking, such that closing of the H2 side port is positively ensured before opening of the air side port.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) Coolers (if applicable) a) 2x100% duty seal oil coolers. b) Cooler tube/ plate redundancy: Seal oil coolers to be designed to have 15% excess cooling surface area over and above designed tube surface area required for the rated load conditions, while maintaining the design pressure drop on cooling water side. v) Filters Suitable filters of 2x100% duty to be provided. 16.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units e) De-mineraliser One (1) mixed bed demineraliser (MBD) of adequate capacity to maintain the required quality of water. MBD to remain continuously in service in order to retain high purity of stator cooling water with its associated electrical resistivity. ii) On-line monitoring Required for ensuring a corrosion free system for water quality operation to be provided along with stator water system. 16.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units c) Margin Each excitation system channel shall be designed to continuously carry at least 110% of the rated machine excitation current at the rated output of the machine and higher currents for short time duty. Short time duty as mentioned above shall be on MCR base as per clause 1.14 of part III in VDE 530. d) Excitation system response time <0.5 sec (as per IEEE 421 A).
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 4. Range of transformer 0 to 15%. drop compensation 5. Maximum change in <0.5% (when AVR is transferred from auto generator voltage to manual under all conditions of excitation). 6. Manual control range 70% of no load to 110% full load excitation. d) Technical features The AVR shall be provided with minimum following features: 1. Channel reference Solid state microprocessor control. control 2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units SECTION-4 CONTROL AND INSTRUMENTATION SYSTEM
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER- 17 CONTROL AND INSTRUMENTATION 17.1 General 17.1.1 General requirements i) A totally integrated Instrumentation and Control System shall be provided ensuring operability, maintainability and reliability.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 17.1.2 Unit control & monitoring philosophy i) The control & monitoring of the plant is envisaged from two locations: a) From Unit Control Room (UCR) There shall be one common UCR for controlling the boilers, turbine-generators and unit auxiliaries.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) Control & Monitoring of Off Site Plants The control, monitoring and operation of the off-site plants i.e. coal handling plant, ash handling plant, fuel oil plant, D.M. plant etc. (not forming part of BTG system) shall be carried out from the local control panel/operator work station.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) On- Line Maintenance It shall be possible to remove/replace online various modules (like I/O module) from its slot for maintenance purpose without switching off power supply to the corresponding rack.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units Control & protection signal exchange between SG- C&I, TG-C&I and BOP - C&I shall be hardwired only. Protection signals like MFT shall necessarily be hardwired even for exchange within the same sub-system. No single failure either of equipment or power source shall render any part/system/sub-system of DDCMIS in-operative to any degree.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) All analog signals for control purpose shall be acquired, validated, processed and their respective data base updated at a maximum interval of 250 milli-seconds except for some fast-acting control loops for which the above-referred time shall be as per process requirement. For signals required for information only, the above functions shall be performed at an interval of within 1 second.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 7. Facility to delete any binary input from scan or to return to scan on operator demand.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) Stream concept shall be maintained. The different equipment shall be clubbed in such a manner that failure of a controller set affects only one stream of the process path, e.g. in air and flue gas path, IDfan A, FD-fan A, and rotary air pre heater– A can be clubbed on one set of controllers. c) Inter-related controls shall be provided in one group, i.e.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units vice versa without resulting in any change in control status. In case of switchover from main controller to the 100% hot backup controller, the back-up controller shall work as the main controller. Facility shall also be provided for manual switchover from main to 100% hot back-up controller and vice versa from the programmer's console. 17.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units vi) The sequence of startup mode shall be of the following types: a) Automatic mode In this mode of operation, the sequence shall progress without involving any action from the operator. The sequence start/stop command shall be issued from the TFT/KBDs. b) Semi-automatic mode In this mode of operation, once the sequence is initiated, the step progressing shall be displayed on the TFT.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units synchronisation of unit etc. All the features and requirements as indicated above shall also be applicable for electrical system. 17.2.5 Analog controls/closed loop controls system (CLCS) functions The CLCS shall continuously act on valves, dampers or other mechanical devices such as hydraulic couplings etc., which alter the plant operation conditions.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units inputs/outputs like analog (4-20 mA DC, thermocouple, RTD), binary, pulse, etc. The inputs which are required for only information and monitoring purposes shall be distributed suitably in various groups of the measurement system. i) The control system shall be broadly divided into SG- C&I, TG- C&I and BOP- C&I. a) The SG- C&I part of DDCMIS system shall perform the following function as minimum but not limited to: 1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 2. Binary control functions pertaining to main plant auxiliaries like FD/ ID/ PA fans, APH, BFP etc., generator auxiliary systems and electrical breakers etc. The generator auxiliary system can alternatively be implemented in TG C&I as per standard and proven practice of the OEM.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 2. Prevent start-up of individual fuel firing equipment unless permissive interlocks have first been satisfied. 3. Monitor and control proper equipment sequencing during its start-up and shutdown. 4. Provide equipment status feed back and annunciator indication to the unit operator. 5.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units elevations shall be modulated on fuel oil pressure signal whereas the auxiliary air dampers at all other elevations shall be modulated to maintain the wind box to furnace differential pressure. c) In order to limit the NOx content in flue gas, SADC shall also include the control of over-fire dampers (if provided).
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 2. Canceling the operation of any soot blower in the system when required. 3. Indication of the soot blower-selected to operate. 4. Capability to monitor all the essentials of the soot blowing system. 5. Capability to prevent continued soot blower operation if the system is not functioning properly. 6. The ability to operate two soot blowers located in opposite walls simultaneously. 7.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) The Turbine Protection System shall be implemented in 2 out of 3 voting logic. Three independent trip channels each having its own dedicated processing modules, controllers, input/output modules etc. shall be provided to achieve 2 out of 3 voting logic. The outputs of the three channels will be used to implement 2 out of 3 voting logic in two relay units, the output of which will be fed to the two turbine trip relays.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) The turbine governing system shall meet the following functional requirements: 1. The controls covered in this system shall basically consist of speed controller, load controller, overspeed protection controller, valve-lift controller, inlet steam pressure controller and output frequency droop characteristic controller.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units normal operation and keeping all protective functions operative during the test. The ATT facility shall include but not be limited to the following: a) Opening and closing of emergency stop and control valves, reheat stop and interceptor valves. b) Over-speed trip. c) Low vacuum trip. d) Electrical remote trip. ATT mentioned at item b), c) & d) above shall be possible to be carried out on 100% load.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units d) Carry out a fatigue analysis for all affected components of the turbine and also to compute the percentage service life consumption of the turbine. e) Display the stress margins etc. on OWS for operator guidance and storage of necessary data such as percentage service life consumption etc. f) Store long term data & carry out residual life analysis.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 17.2.7 Man-machine interface and plant information system (MMIPIS) requirements i) General a) MMIPIS shall be used primarily to act as operator interface for control operation of the plant and to perform plant supervisory, monitoring and information functions. b) MMIPIS shall employ high-performance, non-proprietary architecture to ensure fast access and response time and compatibility with other system.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units d) The display selection process shall be optimised so that the desired display can be selected with the barest minimum number of key strokes / steps by the operator. iii) Plant Supervisory, Monitoring and Information Functions of MMIPIS The MMIPIS shall be designed as an on-line system and following minimum functions shall be performed by MMIPIS: a) Calculations 1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units Other types of displays as applicable for convenience of operation shall be provided. However, the minimum quantity of major types of displays shall be as follows: 1. Control displays (group/sub-group/sequence/loop) 500 2. P&ID/ mimic display 200 3. Bar chart 100 4. X-Y/ X-T Plot 100 5. Operator guidance message 100 6. Plant starting/ shutdown guidance message 100 7. Other misc. displays 8.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units e) Historical storage and retrieval system (HSRS) The HSRS shall collect, store and process system data from MMIPIS data base. The data shall be saved online on hard disk and automatically transferred to erasable & removable type disk/ drive once in every 24 hours periodically for long term storage. The capacity of removable disk/ drive shall be sufficient to store at least one month data.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) MMIPIS Program Development/ Modification and System Maintenance Facilities Standalone online system shall be provided for programme development/modification to achieve various functions including development, modification and testing of software of MMIPIS, generation and modification of graphics, logs, HSRS functions in an interactive manner, MMIPIS database modification/creations, downloading the software with associ
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units c) Data transmitting speed shall be sufficient to meet the responses of the system in terms of displays, control etc. under worst possible data loading condition and minimum 20% spare capacity shall be available for future expansion. d) UTP cables or coaxial cables or fibre optic cables shall be employed for system bus.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) The SOE reports shall also include a list of major equipment trip in chronological order and include the points which initiated SOE collection. 17.2.11 Annunciation system function Annunciation system shall be LVS based with top portion of all the LVS reserved for annunciation with 3/4 bands for different priority. It shall be implemented as an inbuilt function of the DDCMIS.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Flame monitoring system shall be fail safe and easily maintainable which shall include flame detectors of proven design for the type of fuel, environmental condition and other conditions, of established reliability at all loads of the steam generator.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Each coal feeder shall be provided with a minimum of two independent speed sensors, pulser units and associated amplifiers, etc. Output from the speed sensors shall be used to provide at least four number isolated 4-20 mA DC analog signals corresponding to coal flow rate in tons per hour and any other signals that may be required for the control of the coal feeder.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 17.3.5 17.3.6 Acoustic pyrometers (if applicable as per OEM practice) i) Acoustic pyrometers are to be provided to determine the average flue gas temperatures and complete flue gas temperature profile at furnace exit plane (for FEGT measurements) and at economiser outlet. ii) For each temperature measurement plan/section, a PC based system complete with all required software, comprising of minimum eight nos.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 17.3.7 Flame viewing system i) The boiler shall be provided with a flame viewing system. The flame cameras shall be suitable for direct online continuous viewing in the central control room of the coal and oil flame. The numbers of flame cameras to be provided shall be appropriate as per boiler design subject to minimum of two (2) numbers for each boiler.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Sensor head shall be protected from hot gas, particulate matter, and corrosive elements in the flue gas by suitable protective tube and enclosure which will however not block the sound waves. The probes shall have a minimum life of 20,000 hours of operation. All the parts coming into contact with hot gas shall be designed to withstand the high temperature.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units h) Emergency stop and control valve position. i) Main steam and hot reheat steam inlet temperature and pressure. j) Bearing metal and drain oil temperature. k) Turbine casing metal temperature. l) In case of vibration, shaft mounted reference detectors and required supervisory instrument circuitry shall also be provided. m) Any other measurement necessary for safe and reliable operation of the turbine.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units c) Differential expansion. d) Overall expansion. e) Speed (triple pickups). f) Turbine casing and bearing metal temperature for all bearings. g) Stop valve metal temperature. h) Bearing pedestal vibration (both in horizontal and vertical direction). i) Absolute as well as relative shaft vibration measurement in both X & Y direction. j) Any other measurement necessary for the safe and reliable operation of the turbine.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units v) Facilitate obtaining lowest emission while maintaining combustion efficiency. vi) Evaluate system and component performance degradation to detect worn plant equipment. vii) Expert system diagnostics using neural and Bayesian belief networks and historical data for quick identification of problem pinpointing down to the component.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iv) For PLC system of CPU, two (2) nos. latest version of PC based OWS each with 19" color TFT’s and key boards shall be provided for control & monitoring and programming function. One number heavy duty A3 size color printer shall be provided alongwith OWS.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units SECTION-5 MISCELLANEOUS SYSTEMS, PIPING, VALVES, INSULATION ETC.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER- 18 POWER CYCLE PIPING, VALVES AND THERMAL INSULATION 18.1 Power Cycle Piping 18.1.1 General 18.1.2 i) All the piping systems and equipments supplied shall be designed to operate without replacement and with normal maintenance for a plant service life of 25 years and shall withstand the operating parameter fluctuations and cycling which can be normally expected during this period.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Pressure drop in reheat steam circuit (cold reheat, hot reheat line & reheater) should not exceed 10 % of HP turbine exhaust pressure. iii) Pipes shall be sized for the worst operating conditions (i.e. maximum flow, temperature and pressure values).
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 18.1.3 Material selection The material used for power cycle piping shall be equal to or better than the following unless specified otherwise: Design metal temperature 18.1.4 18.1.5 i) Upto & including 4000C ii) Upto & including 5500C iii) Upto & including 6050C iv) Above 6050C Material Carbon steel to ASME SA-106 Gr. B/C or SA 210 Gr. C or equivalent.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 18.1.6 ii) All piping shall be sloped towards the system low point such that slope is maintained in both hot and cold condition. iii) The pipe routing shall be such that a clear head room of not less than 2.2 m above the walkways/ working area is available. Stress/ dynamic analysis i) ii) 18.1.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units ii) Fittings a) Material for 200 NB & above X20 Cr. Mo V 121 to DIN 17175 OR ASTM A234 Gr.WP91 OR ASTM A234 Gr.WP22 ASTM A 234 Gr. WPB for ASTM 106 Gr. B piping ASTM A 234 Gr. WPC for ASTM 106 Gr. C piping OR ASTM A234 Gr.WP11 b) Material for ASTM A234 Gr.WP91 65 NB to OR ASTM A234 Gr.WP22 <200 NB OR ASTM A335 P36/ WB 36 for ASTM A335 P36/ WB 36 piping ASTM A234 Gr.WP11 c) Material for ASTM A182 Gr.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) Non-IBR piping systems: 1. At shop All piping including fabricated piping shall be hydro tested at 1.5 times the design pressure. However, non-destructive testing in lieu of hydro test is also acceptable subject to regulation 343 (3) of IBR. 2. After erection All piping systems shall be hydro tested at 1.5 times the design pressure.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 18.1.8 18.1.9 9. Material P-22 is applicable for piping with temperature > 5100C and upto 5500C and P11 is applicable for all other alloy steel piping below 5100C. 10. Materials for fittings, specialties and valves shall be corresponding to piping material or equivalent.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iii) All gate and globe valves shall be with outside screw and yoke with rising stem. Gate valves below 100 NB shall be solid wedge/flexible wedge type. Valves of class 150/ 300 and size 100 NB and above shall be of flexible wedge type. However, for sizes 100 mm NB and above for temperatures above 3000C, parallel slide valves are also acceptable.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units cold condition or as per the recommendation of TG supplier to ensure that there is no transfer of undesired pipe weight/ load on the turbine valves/nozzles. ii) All pipes hangers and supports shall be designed to carry the weight of the piping, fitting, thermal insulation, self weight of the hanger assembly and medium transported or test medium whichever is heavier.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 18.1.13 Steam blowing of piping systems i) The following piping systems shall be cleaned through steam blowing operation: a) Main steam, HRH, CRH, HP bypass & LP bypass piping. b) Auxiliary steam piping including TG gland sealing lines. c) Steam lines feeding turbines of boiler feed pumps. ii) Steam blowing shall be carried out for removal of particles (rust, scales, weld splatter etc.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units v) 18.3 For cavitation service, only valve with anti cavitation trim shall be provided. Applications like CEP minimum recirculation valve shall have anti-cavitation trim with tight shut-off. The deaerator level control valve shall have characterized trim cages to have a cavitation protection at minimum flow as well as good rangeability. Thermal Insulation 18.3.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units a) Mild steel wires for general engineering purposes. b) IS 3144 Methods of test for mineral wool insulation materials. c) IS 3677 Unbonded rock and slag wool for thermal insulation. d) IS 5696 Loose mineral wool. e) IS 8183 Lightly bonded mineral wool for thermal insulation. f) IS 9428 Pre-formed calcium silicate insulation. g) IS 9742 Sprayed mineral wool thermal insulation. h) IS 9842 Preformed fibrous pipe insulation.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units vi) The thermal insulation for the turbine casing shall consist of sprayed insulation produced by projecting specially prepared mineral wool along with a fine liquid spray. This shall be covered with prefabricated 'blanket' type insulation. Voids around the blankets should be avoided. However, unavoidable voids shall be filled with loose mineral wool. 18.3.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iii) iv) c) For steam generator outer casing : 1.219 mm (18 SWG) ribbed Aluminum d) For ESP : 0.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER - 19 STEAM TURBINE HP-LP BYPASS SYSTEM 19.1 Purpose The HP and LP turbine bypass system is envisaged to be used for the following functions: i) To enable boiler and turbine to be operated independent of each other during start-up and shutdown. ii) To enable in quick reloading of the unit following a turbine trip.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 19.2.5 HP bypass shall be designed to accept continuous spray water at temperature corresponding to all HP heaters out of service and deaerator pegged at pressure 3.5 ata or as per OEM practice. 19.2.6 For LP bypass system the de-superheating may be done outside the valve body with spray water tapped from condensate pump discharge. 19.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER- 20 AUXILIARY STEAM PRESSURE REDUCING & DESUPERHEATING SYSTEM 20.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 20.3 Low capacity PRDS shall be sized for auxiliary steam requirement of about 20 TPH including for requirement of fuel oil heating and air conditioning plant (if required) and shall supply steam for normal continuous requirements of its own unit. 20.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER- 21 EQUIPMENT COOLING WATER (ECW) SYSTEM 21.1 General Closed circuit type ECW system shall be provided with demineralised (DM) water in the primary circuit and water tapped off from CW system upstream of condenser in the secondary circuit. ECW system shall be provided unit-wise and shall cater to cooling water requirements of TG and its auxiliaries as well as Steam Generator auxiliaries.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 21.2.5 The common secondary circulating water system shall operate in parallel to the condenser and shall receive water through a tapping on the CW inlet line to the main condenser. Pressure of this water shall be further boosted by a set of 3x50% or 2x100% capacity secondary cooling water (SCW) pumps and fed through the plate heat exchangers back to the CW discharge line of the main condenser.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units vi) The materials of construction of primary and secondary cooling water pumps shall be as given below or equivalent: Description a) Casing b) Impeller c) Shaft d) Shaft sleeve e) Impeller wearing rings Primary DM Secondary cooling water pumps cooling For fresh water For sea water water pumps ASTM-A2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 21.3.3 Butterfly valves i) The butterfly valves shall be designed as per AWWA C-504 or BS 5155 and tested as per AWWA C-504 standard. ii) The design pressure of valves shall be equal to pump shut off pressure at 51.5Hz with maximum suction pressure.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 21.3.6 Alkali preparation/ dosing system One no. alkali preparation/ dosing tank of minimum 500 litre capacity shall be provided for gravity feed of alkali solution to overhead DM tank and suction piping of ECW system. The tank shall be of MSRL/ stainless steel construction with SS 316 basket, SS 316 agitator with gear reducer unit and other accessories. Alternatively, dosing system may comprise of one no.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER- 22 CONDENSATE POLISHING PLANT . 22.1 General The Condensate polishing Plant shall consist of one set of Condensate polishing Units (CPU) for each TG unit and a common external regeneration system. The CPU for each 660 MW unit shall consist of 3x50% capacity service vessels (4x33.3% for 800 MW unit size). 22.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units iii) During start up conditions, quality of the influent shall be considered as below: a) TDS, ppb b) Silica, ppb c) Crud, ppb (mostly black oxide of Iron) : : : 2000 150 1000 During start-up condition, the sodium and chloride content at the outlet of CPU shall not exceed 5 ppb and 10 ppb respectively. For design purposes, average crud loading shall be considered as 500 ppb.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units c) Service vessels shall be designed and constructed in accordance with the ASME code Section- VIII or equivalent international standard or IS 2825. Suitable mill tolerance shall be considered for determining the thickness of the shell and dished ends. A minimum thinning allowance of 2 mm shall be considered for the dished ends. d) The service vessels shall be fabricated from carbon steel plates to SA 285C or SA-516 Gr.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) Either 2x50% capacity control valves or 1x100% control valve shall be provided to achieve proper control under all operating conditions. The control valve(s) shall be able to bypass requisite percentage of rated flow as per any number of the operating service vessels being out of service.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units d) ii) 2x100% capacity DM water pumps shall be provided for water supply for chemical preparation/dosing and transfer of resin from service vessel to regenerating vessels and vice versa. The pumps shall be horizontal centrifugal type and conform to IS: 1520/IS: 5120 or equivalent without any negative tolerance. All wetted parts of the pump shall be of CF-8M.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units b) The requirement of tanks and unloading pumps shall be as below: 1. 2. 3. 4. v) Acid storage tanks 2 nos., total storage capacity to hold 30- 33% HCl for 30 days (minimum) requirement of the plant or 30 m3 whichever is higher. Alkali storage tanks 2 nos., total storage capacity to hold 48% NaOH for 30 days (minimum) requirement of the plant or 30 m3 whichever is higher.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 22.5.3 It shall be possible to operate the regeneration plant in auto/semi-auto/ manual mode. In 'Auto' mode, once the sequence has been initiated, it shall proceed from step to step automatically. In 'Semi-auto' mode each step shall be performed only after initiation by the operator. In ‘Manual’ mode, complete operation shall be by the operator by operation from the control panel.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER- 23 CHEMICAL DOSING SYSTEM 23.1 General 23.1.1 Water chemistry of boiler feed water during normal operation of the plant shall be maintained using combined water treatment (CWT) comprising of oxygen dosing and ammonia dosing in the condensate and feed water as per the guidelines of EPRI, USA/ VGB, Germany/ CEGB, UK/ relevant Japanese standard.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 23.2.2 The dosing system shall be provided with set of oxygen cylinders alongwith required cylinder isolation/ check valves, cylinder manifolds, isolation valves in the common manifold, piping from manifold, dosing (automatic type) valves, check (non-return type) valves, associated control system and instruments etc. 23.2.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units CHAPTER- 24 EOT CRANE 24.1 Two (2) nos. of electrically operated travelling crane with associated auxiliaries alongwith electrical equipment, control & instrumentation as required shall be provided in the turbine hall for erection and maintenance of turbine-generators and their auxiliaries except generator stator.
Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units 24.7 Three phase squirrel cage Induction motors to be operated from VFD system shall be suitable for speed range and torque without exceeding temperature rise limits. Motors shall conform to latest revision of IS 325, IS 3177. 24.
