New environmental norms: Modalities for adoption of FGD Technologies for NSPCL Projects

1. New environmental norms: Modalities for adoption of FGD Technologies for NSPCL Projects PukhrajSoni & AbhishekAgrawal NSPCL (A Joint Venture of NTPC-SAIL)

2. New Emission Norms Notified by MOEF, GOI on07.12.2015 Old Vs New EnvironmentalNorms

3. New Emission Norms for NSPCL Plants

5. IMPLEMENTATION PLAN OF FGD FOR NSPCL PROJECTS • NTPC vide letter Ref: 01/CP/SP/CEA dated 14.06.2017 informed CEA regarding implementation plan for FGD installation in Coal based thermal units of NTPC. • NTPC has included existing NSPCL Power Projects in the list submitted to CEA i.e. 2 X 60 MW Units of Durgapur, 2 X 60 MW Units of Rourkela , 2 X 250 MW Units of Bhilai. • Installation of FGD for Bhilai PP-II is not included in the aforesaid list. • Implementation Plan for above Units as per NTPC commitment to CEA is 31.12.2023 • For Rourkela Expansion 1 X 250 MW Unit FGD shall be installed in consultation with NTPC. • For Durgapur Expansion 2 X 20 MW Units FGD systems is included in the already awarded EPC Package.

6. Technologies adopted for NSPCL Projects • Technologies adopted for Expansion projects:- • Durgapur PP- III ( 2 x 20 MW ): Dry FGD Circulating Dry Scrubber (CDS) • Rourkela PP-II Expansion ( 1 X 250 MW ): Wet FGD ( Forced Oxidation Wet Limestone FGD LSFO) • Technologies for Existing Units : • Bhilai PP-III Units ( 2 X 250 MW ) : Wet FGD ( Forced Oxidation Wet Limestone FGD LSFO) • NSPCL PP-II Units: Dry FGD - Circulating Dry Scrubber (CDS) or Dry FGD - Spray Dryer Absorber (SDA ) may be used depending upon detailed study.

7. DRY FGD SYSTEM – CIRCULATING DRY SCRUBBER(CDS) • LIME HYDRATED AT SITE i.e. (Ca(OH)2) IS THE SCRUBBING AGENT - INTRODUCED AS A DRY FREE FLOWING POWDER • THE PROCESS INVOLVES EVAPORATIVE COOLING AND RECIRCULATION OF UNREACTED REAGENT – IMPROVES LIME UTILIZATION • 90% OF THE SOLIDS (CONTAINING UNREACTED LIME) DISCHARGED FROM ESP or FF ARE RECYCLED TO THE CDS BY GRAVITY USING AIR SLIDES – FRESH HYDRATED LIME ALSO IS FED IN THE ABSORBER BY ROTARY FEEDERS. • EXTREMELY LONG SOLIDS RETENTION TIME ALLOWS HIGH ABSORPTION OF GASEOUS POLLUTANTS AND IMPROVES LIME UTILISATION • BY PRECISE CONTROL OF PROCESS PARAMETERS (GAS DISTRIBUTION, REAGENT FLOW RATE, ETC.) ENSURES FREE FLOWING DRY BY PRODUCT ( CaSO3 / CaSO4)

8. DRY FGD SYSTEM – CIRCULATING DRY SCRUBBER (CDS) – CONTD. • SUITABLE FOR HIGH SULFUR FUELS WITH 98%+ SO2 REMOVAL • ABSORBER, DOWNSTREAM DUCTS / COMPONENTS, CHIMNEY ARE CARBON STEEL CONSTRUCTION. NO CORROSION RESISTANT LINING IS REQUIRED. • WATER REQUIREMENT IS LOW. • NO WASTE WATER TREATMENT REQUIRED • ELEVATED ESP / BAGHOUSE

9. DRY FGD – Scheme for Dry Scrubber

10. CDS CHEMICAL EQUATION The equipment and the processes are similar to those in limestone scrubbing Lime Scrubbing offers better utilization of the reagent. The operation is more flexible. The major disadvantage is the high cost of lime compared to limestone. The reactions occurring during lime scrubbing are : Hydrated Lime: Ca(OH)2(s)+ SO2(g) → CaSO3(s) + H2O(l) • CaSO3(s)+ ½O2(g) → CaSO4(s)

11. POSSIBLE UTILISATION OF DRY FGD BYPRODUCT • Utilisation in agriculture- Fertiliser • Utilization as Backfilling (combination with fly ash)in road construction • Utilization for Underground mining Filling • Landfill for Low Lying Areas

12. WET FGD SYSTEMS - CHARACTERISTICS Wet FGD accounts for about 80% of all FGD installation. Among Wet FGD Systems, Limestone Forced Oxidation (LSFO) most commonly used technology.

13. WET FGD SYSTEM CHEMISTRY Limestone slurry is sprayed on the incoming flue gas. The sulfur dioxide gets absorbed The limestone and the sulfur dioxide react as follows : • Limestone: CaCO3(s) + SO2(g) → CaSO3(s) + CO2(g) • CaSO3(s)+ ½O2(g) + 2H2O(l) → CaSO4·2(H2O)(s) • (Gypsum)

14. TYPICAL WET FGD (LSFO) SYSTEM

15. GAS TO GAS HEATER (GGH) – SOME IMPORTANT CONSIDERATIONS • GGH ENTAILS ADDITIONAL AUXILIARY POWER CONSUMPTION • GGH REQUIRES CONSIDERABLE SPACE FOR INSTALLATION • PRONE TO LEAKAGE FROM UNTREATED GAS SIDE TO TREATED GAS SIDE • GGH ENTAILS HIGH O&M COST DUE TO CHOKING PROBLEM REQUIRING FREQUENT BASKET CLEANING • WET FGD SYSTEMS WITHOUT GGH ARE BEING PREFERRED NOW A DAYS. HOWEVER, WITHOUT GGH CLEAN GAS TEMPERATURE WOULD BE ABOUT 50 – 600C. AT OUTLET OF ABSORBER INSTEAD OF 90 – 950C WITH GGH. • LOW TEMPERATURE CLEAN GAS MAKES SYSTEMS DOWNSTREAM OF ABSORBER PRONE TO ACID CORROSION. • TO AVOID / MINIMISE CORROSION, SUITABLY DESIGNED WET STACK / CHIMNEY WITH LINERS WOULD BE REQUIRED. SUITABLE ACID RESISTANT MATERIAL / LINER FOR THE CLEAN GAS DUCT FROM ABSORBER TO GGH AND TO CHIMNEY ALSO WOULD BE REQUIRED. COMMON CHIMNEY LINERS BEING CONSIDERED ARE BOROSILICATE GLASS, FLAKE GLASS REINFORCED VINYL ESTER, FRP ETC.

16. Conventional Chimney Flue Liner for Retrofit Cases

17. Chimney Flue Liner

18. Conventional Chimney Flue Liner for New Projects

19. Chimney Liner for FGD Systems at NSPCL • For Rourkela PP-II Expansion, due to the operational problems associated with the GGH, we have envisaged the FGD system at Rourkela without GGH. • But due to reduced temperature and increased moisture content of the Flue gases, the Chimney is to be considered as a Wet Stack and appropriate liner has to be provided to avoid the corrosion of the Flue Can. • Various Liners are available in the market and choice has to be made based on technical requirement and cost effectiveness. • Rourkela PP-II Expansion- Titanium cladded Flue Can • Bhilai PP-III- Flue Can cladded with Borosilicate blocks/ C-276/ Ti • For existing PP-II Plants decision on liner shall be taken after detailed study

20. ISSUES & CHALLENGES • NSPCL plants are very old and captive in nature. • FGD retrofit …. Difficult in many of the older stations due to space constraint due to already executed and ongoing R&M. • Technology suppliers are mostly situated abroad and costly.Indigenous manufacturing capacity needs to be developed / ramped up fast due to huge demand of FGD systems. • Large water requirement (about 0.25 m3/hr/MW of Water) for Wet FGD . Increased Aux. Power Consumption with FGD operation (by 1.0 - 1.5%).

21. ISSUES & CHALLENGES(Contd.) • Lime stone supply and gypsum off take chain needs to beaugmented. • Disposal of Gypsum in environmentally friendlymanner. • Time LimitConstraint:Limited time period specified for implementation of FGD for new & old plants. Little progress made in last two year. • Financing & RegulatoryProblems:Financing for investment required, impactof investment on cost of generation and Tariff approval remains one of the main concerns.

22. CONCLUSION AND ACTION PLAN • High Capital and operation cost for the proposed system may impact the cost effectiveness of the generated Power. • Rock bottom tariff for Solar Power will pose a big challenge for thermal power. • NSPCL has mostly smaller capacity captive units and non compliance of the new Environment norms may risk the entire Business of NSPCL. • Timely implementation of FGD system to meet the Environmental Norms for • “Safe , Reliable, Efficient and Environment friendly operation of existing and upcoming NSPCL Power Plants”

23. MECONLIMITED A House of EngineeringExcellence

24. WET FGD ABSORBER ABSORBER IMPORTANT FEATURES MATERIAL OF CONSTRUCTION PH MAINTAINED INSIDE THE ABSORBER IS 5-6 • 317 LMN STEEL or Equiv. / CARBON STEEL WITH RUBBER / FRP LINING • CARBON STEEL WITH HIGH CORROSION RESISTANT AND ACID RESISTANT CERAMIC LINING • RCC CONSTRUCTION WITH HIGH CORROSION RESISTANT AND ACID RESISTANT CERAMIC LINING