MECON LIMITED. CONTROL OF SULPHUR DI OXIDE (SO 2 ) FROM TPPs TECHNOLOGY, ISSUES, CHALLENGES & WAY FORWARD SOx NOx 2016 THE FIRST CONFERENCE

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1 CONTROL OF SULPHUR DI OXIDE (SO 2 ) FROM TPPs TECHNOLOGY, ISSUES, CHALLENGES & WAY FORWARD SOx NOx 2016 THE FIRST CONFERENCE D. VERMA & DR. P.K. MAJI (A Govt. of India Enterprise)

2 New Emission Norms Notified by MOEF, GOI on EMISSION PARAMET ERS OLD NORMS NEW NORMS (mg/nm 3 ) UNITS INSTALLED BEFORE UNITS INSTALLED AFTER AND UPTO UNIT SIZE ALL < 500 MW > 500 MW < 500 MW > 500 MW SO 2 Dispersion Through Chimney UNITS TO BE INSTALLED FROM ALL NOx No Standard SPM 150 mg/nm 3 For 210 MW and above Old Vs New Environmental Norms MERCURY No Standard X

3 Major FGD Technologies at a glance TECHNOLOGY REAGENT USED END PRODUCT SO 2 REMOVAL I. PRECOMBUSTION OR DURING COMBUSTION TECHNOLOGIES Direct Furnace Sorbent Injection Fluidised Bed Combustion Scrubbing II. POST COMBUSTION TECHNOLOGIES IIA. WET SCRUBBING 1.Forced Oxidation Wet Limestone FGD (LSFO) Limestone or hydrated lime Gypsum (CaSO 4 ) 50 % - 60% Limestone Gypsum (CaSO 4 ) 90% - 95% Limestone slurry Gypsum (CaSO 4 ) 95% - 98% 2. Wet Lime FGD System (MEL) Slaked Lime (Mg enhanced) CaSO 3 / CaSO 4, MgSO 3 98% - 99% 3. Sea Water Scrubbing Sea Water None 90% - 98% 4. Ammonia Scrubbing Anhydrous Ammonia Ammonium Sulphate 96% - 99% IIB. DRY / SEMI DRY SCRUBBING 1. Spray Dryer Absorber (SDA) Dry Hydrated Lime / Lime Slurry 2. Circulating Dry Scrubber (CDS) CaSO 3 / CaSO 4 85% - 99% Dry Hydrated Lime CaSO 3 / CaSO 4 >98%

4 PRE COMBUSTION FGD TECHNOLOGIES DIRECT FURNACE SORBENT INJECTION (DFSI) INJECTION OF POWDERED LIMESTONE PNEUMATICALLY INTO FURNACE COMMERCIALLY DEMONSTRATED ON BOILERS - FROM 15 TO 700 MW BY PRODUCT FORMED IS CaSO 4 (Gypsum) WHICH COMES OUT WITH ASH FLUIDISED BED COMBUSTION SCRUBBING FGD LIMESTONE ADDED TO THE FLUIDISED BED ALONG WITH THE FUEL FOR INSITU CAPTURE OF SO2 GENERATED COMMERCIALLY DEMONSTRATED ON BOILERS FROM 10 TO 450 MW BY PRODUCT FORMED IS CaSO 4 (Gypsum) WHICH COMES OUT WITH ASH

5 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. Wet Lime (Mg enhanced - MEL) also quite commonly used. Better reagent utilisation in MEL leads to better SO2 removal efficiency. Absorber Vessel Height is reduced, Pumping Heads are lower, Auxiliary power consumption is less as compared to LSFO. However in Wet Lime (MEL) process, reagent cost is considerably high. ADVANTAGES of WET FGD SYSTEMS DISADVANTAGES of WET FGD SYSTEMS Coal Sulphur range from 0.2% to 8% Inlet SO 2 ranges from ppm SO 2 Removal efficiencies up to 99% Mature Technology One tower per boiler ( no spare tower required upto 1100 MW capacity boiler. Gypsum / Ammonium Sulphate saleable / marketable by product High Water Consumption High Auxiliary Power Consumption Requires Waste Water Treatment Alloys or coatings required for corrosion protection Wet Stack required Sulfites formed in Wet lime System are difficult to be disposed off. Conversion into Sulfates also possible.

6 TYPICAL WET FGD (LSFO) SYSTEM WITH GGH

7 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 C. AT OUTLET OF ABSORBER INSTEAD OF C 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.

8 WET FGD ABSORBER ABSORBER IMPORTANT FEATURES PH MAINTAINED INSIDE THE ABSORBER IS 5-6 MATERIAL OF CONSTRUCTION 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

9 SEA WATER BASED WET FGD SUITABLE AND PREFERRED FOR COASTAL POWER PLANTS MEDIUM TO HIGH SULPHUR CONTENT AND FOR USES HIGH NATURAL ALKALINITY OF SEA WATER ( SEA WATER CONTAINS SODIUM, MAGNESIUM, POTASSIUM, CALCIUM, CARBONATES AND BICARBONATES IONS) HAVING ph IN THE RANGE OF LIQUID EFFLUENT IS AERATED AND CO2 IS REMOVED. ph IS RAISED TO 6 7 TO OXIDIZE HSO 3- and SO 2-3 to HSO 4- and SO4 2- BEFORE RETURNING TO SEA. IN SEA ALSO, CONVERSION OF REMAINING HSO - 4 to SO4 2- CONTINUES AS ph INCREASES TO AROUND 8 IN THE OCEAN MIXING ZONE. ADVANTAGES:- NO CHEMICAL ABSORBENT OR REAGENT (ONLY SEA WATER AND AIR) NO BY PRODUCT AND ITS HANDLING SYSTEM REQUIRED LOWER OPEARTING AND CAPITAL COSTS CONTAMINATION BY RETURN SEA WATER ( HIGHER SULFATE CONCENTRATION, AIR TOXICS, MERCURY, PARTICULATE MATTER ETC.) IS A CAUSE OF CONCERN. SO PROPER OCEAN MIXING ZONE FOR THE RETURN SEA WATER IS REQUIRED.

10 SEA WATER BASED WET FGD SEA WATER SCRUBBING BASED FGD SYSTEM

11 AMMONIA SCRUBBING BASED WET FGD AMMONIA (NH 3) AGENT - EITHER IN ANHYDROUS OR AQUEOUS FORM - IS THE SCRUBBING HIGH SO 2 REMOVAL EFFICIENCIES (96% - 99%) ACHIEVABLE END PRODUCT IS SALABLE AMMONIUM SULFATE ((NH 4 ) 2 SO 4 ) FERTILISER MAKE UP WATER ADDED TO THE ABSORBER TO KEEP AMMONIA DILUTED. AMMONIA AS A REAGENT IS COSTLY. HOWEVER, IT CAN BE RECOVERED BY SELLING THE BY PRODUCT AMMONIUM SULPHATE. AMMONIA HANDLING AND STORAGE AT SITE REQUIRES EXTREME CARE AS AMMONIA IS A HAZARDOUS MATERIAL SYSTEM COMES WITH THE PRESCRUBBER MODULE IN WHICH SATURATED AMMONIUM SULFATE LIQUOR ( ABSORBER BLOWDOWN) IS SPRAYED TO COOL THE FLUE GAS AND ALSO TO EVAPORATE WATER FROM SATURATED AMMONIUM SULFATE SOLUTION TO PRODUCE AMMONIUM SULFATE CRYSTALS. NO CO 2 GREEN HOUSE GAS IS PRODUCED. REDUCES / ELIMINATES SOLID AND LIQUID WASTE ISSUES.

12 AMMONIA SCRUBBING BASED WET FGD Cost of per ton of Ammonia is about 2.25 times the cost of per tonne of Ammonium Sulphate. For every 1 kg of SO 2 removed, 0.5 kg of Ammonia is required and produces 2 kg of Ammonium Sulfate. 4:1 product / feed ratio ( Ammonium Sulfate : Ammonia) generates favourable economic leverage which significantly ofsets the operating cost.

13 WET FGD SYSTEM ATTRIBUTES COMPARISON Attributes Wet Limestone Forced Oxidized Magnesium Enhanced Wet Lime Sea Water Based FGD Ammonia Based FGD Capital Cost Medium Low High High Industry Experience High High Low Limited Reagent Cost Medium High Low High By Product Management Disposal to revenue producer Disposal Only Disposal only Revenue producer Maximum Removal efficiency Achievable Maintenance Requirement 95 98% 98-99% Upto 98% Upto 99% Medium Medium Low Medium

14 DRY FGD SYSTEM SPRAY DRYER ABSORBER (SDA) SDA ACCOUNTS FOR ABOUT 15% OF ALL FGD INSTALLATIONS LIME SLURRY IS THE SCRUBBING AGENT - ATOMISED INTO FINE DROPLETS BY HIGH SPEED ROTARY ATOMIZERS OR SPRAY NOZZLES INJECTED IN FLUE GAS INSIDE ABSORBER MODULE SO 2 REMOVAL EFFICIENCIES 85% - 99% AND LOW WATER CONSUMPTION, NO WASTE WATER GENERATED DURING REACTION WATER IS EVAPORATED COMPLETELY. PRECISE CONTROL OF PROCESS PARAMETERS ( GAS DISTRIBUTION, SLURRY FLOW RATE, DROPLET SIZE ETC.) ENSURES FREE FLOWING DRY BY PRODUCT ( CaSO 3 / CaSO 4 ) USUALLY COLLECTED WITH FLY ASH IN A FABRIC FILTER. PART OF IT IS RECYCLED FOR BETTER UTILISATION OF UNREACTED LIME THEREBY REDUCING LIME CONSUMPTION.

15 DRY FGD SYSTEM SPRAY DRYER ABSORBER (CONTD.) IN FABRIC FILTER ALSO REACTION TAKES PLACE BETWEEN UNREACTED LIME AND REACTION PRODUCTS. THIS ADDITIONAL CONTACT MAY RESULT IN AS MUCH AS 20% ADDITIONAL SO 2 REMOVAL. SO 3 REMOVAL EFFICIENCY MORE THAN 99 % IS ACHIEVABLE. SUITABLE FOR LOW MEDIUM SULFUR FUELS ( up to 3.5% ) ABSORBER, DOWNSTREAM DUCTS / COMPONENTS, CHIMNEY ARE CARBON STEEL CONSTRUCTION. NO CORROSION RESISTANT LINING IS REQUIRED. WATER REQUIREMENT IS LOW, SLURRY PUMPING REQUIREMENT IS LOW NO WASTE WATER TREATMENT REQUIRED

16 DRY FGD SPRAY DRYER ABSORBER

17 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 ( CaSO 3 / CaSO 4 )

18 DRY FGD SYSTEM CIRCULATING DRY SCRUBBER (CDS) CONTD. SUITABLE FOR HIGH SULFUR FUELS WITH 98%+ SO 2 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

19 DRY FGD SYSTEM CIRCULATING DRY SCRUBBER

20 COMPARISON OF WET LIMESTONE FGD Vs. DRY FGD Parameters Wet Limestone FGD DRY FGD (SDA / CDS) Commercially available range ~1100 MW ~ MW Single Absorber SO 2 Removal Efficiency % % ( Sea Water) % for CDS 85% - 99% for SDA SO 3 Removal Efficiency % ~ % Mercury Removal Efficiency Without additive < 40% With additive < 92% Installn. Cost ( ZLD & Chimney lining included) Higher (Base:100) Without additive < 60% With additive < 97% Lower (SDA :~ 80 & CDS: ~83) O & M Costs Moderate High (When base level is high > 2000 mg/nm3. For base levels < 2000, O&M costs comparable) Sorbent Limestone (CaCO3) Lime (CaO / Ca(OH)2) Sorbent Costs (Rs./Ton) ~ 1500 (Lower) ~ (Higher) Aux. Power Consumption High with GGH Moderate without GGH ( % of plant output) Moderate (0.6% of plant output)

21 COMPARISON OF WET LIMESTONE FGD Vs. DRY FGD (Contd.) Parameters Wet Limestone FGD DRY FGD (SDA / CDS) Water Consumption Higher Lower ( about 40% less) Flue Gas Temp. at FGD Outlet MOC for Absorber Condition of existing stack FGD By product disposal Saturation Temperature deg.c without GGH High Alloy Steel or CS with Lining Existing stack to be modified in almost all cases Gypsum is produced which is saleable when limestone purity is 90% and emission from ESP < 50 mg/nm3 Waste Water Waste Water Generated Needs to be treated for Zero Liquid Discharge (ZLD) Above Saturation (~ 90 deg.c) Carbon Steel Fuel % Sulphur preference Upto 8% < 3.5% Existing Stack can be used without modifications Product for disposal (CaSO3 / CaSO4). Space required for disposal. Waste water free system and can also utilise waste water from other sources.

22 ESTIMATED AREA / SPACE REQUIREMENT Description Area ( in acres) Required for F.G.D. System Sp. Area ( in acres / MW) Sp. Area ( in Sq. m. / MW) 2 x 500 MW 3 x 660 MW 5 x 660 MW 6 x 660 MW 4 x 800 MW 5 x 800 MW 3 x 700 MW Coastal Station (Using imported coal) Source : CEA Report on Land Requirement Of Thermal Power Stations Estimated Area - Based on some actual layouts ) Sq.m / MW ( WET FGD) N.A. Environmental clearances given since 2003 required units larger than 500 MW to keep space for future FGD installation. So space for these plants is not a constraint. For the old plants, requiring retrofitting, Space is likely to be a major constraint and these plants are likely to suffer due to non availability of space.

23 LIMESTONE FACT SHEET Limestone - key raw material required for FGD. Assuming that units larger than 500 MW will install FGD and smaller units can install partial FGD, around million tonnes of limestone is required annum, which is small fraction of cement Industry s limestone use. However, this figure is likely to increase progressively with increase in FGD installations. Total reserve of limestone in India is above million tonnes. Limestone mines are distributed almost all over India. Production of limestone in India was about 279 million tonnes during Majority of limestone is of 80%-85% purity which will produce gypsum for cement or fertiliser consumption. High quality limestone mostly available in Rajasthan. The present mining capacity of limestone in the country and transportation capacity to plants shall be able to meet this additional requirement... May be with little augmentation.

24 COST DATA INVESTMENT REQUIRED FOR SOx CONTROL TECHNOLOGY Technology Required Capacity in GW Approx Capital Cost ( in Rs. Crores PARTIAL FGD About 54.2 Rs lakh / MW FGD About 98.2 Rs lakh / MW Capital Costs of FGD are manageable. Exact investments would depend on the combination of upgradation and new installation required, which in turn would depend on present abetment technology, actual emissions, applicable norms and age of the plant. Source: Centre for Science & Environment Stake holder Workshop Dated OPERATING COSTS would depend on the Technology Selected, Reagent Used, Sulphur Content in the Fuel and O&M cost of the Plant.

25 COST DATA (Contd.) LIKELY IMPACT ON TARIFF There would be impact on the tariff. Based on the projected Capital Expenditures Given by the plants in Haryana, the State Electricity Regulatory Commission (HERC) estimated a generation tariff impact of around 22 paise per unit for adopting all the Pollution Control Technologies ( SPM, SOx, NOx, Hg etc.) for meeting New GOI Norms. For the FGD Systems alone, the generation tariff impact would be in the range of 9 paise to 14 paise. It shall largely depend on FGD technology adopted and Sulphur Content of the Fuel. Typical Case Study: Sulphur 0.7% and 2% in Bithnok & Barsingsar Lignite Attributes (Wet FGD) Increase in Power Tariff Bithnok Thermal Power Plant 1 x 250 MW Lignite CFBC Rs to 0.10 Barsingsar Thermal Power Stn. (extn.) 1 x 250 MW Lignite CFBC Rs to 0.14 Fixed Cost :- Variable Cost : - Rs to 0.09 Rs Rs to 0.12 Rs. 0.02

26 TIME LINE Estimated FGD PLANT Construction Time and Down Time of the Power Plant Technology Construction Time Down time FGD ~18 24 Months days Flue Gas Desulphurisation installation may take around 2 to 3 years and involve plant shutdown of 1-3 months. Dismantling / Relocation of existing plant facilities may be required in certain cases, affecting plant operation. Pre Execution Activities ( Technology Finalisation, cost estimate, financial tie ups / approvals etc.) could take up to 9 months and design, procurement and installation can take another two years. Indigenous supplier capacity to execute this scale of projects is limited and costs may rise due to supply shortage. However, global supply likely to rise quickly to meet demand and it will have soothing effect on the prices also. Source: Centre for Science & Environment Stake holder Workshop Dated

27 ISSUES & CHALLENGES Technology suppliers are mostly situated abroad Indigenous manufacturing capacity to be developed / ramped up fast. Large consumptive water requirement (about 0.25 m3/hr/mw of Water) for Wet FGD. Polluted blow down requiring Zero Liquid Discharge (ZLD) system FGD retrofit. Difficult in many of the older stations due to space constraint. The impact on power supply position due to closure of most of coal based capacity due to non-fulfilment of environmental norms. Time Limit Constraint: - Limited time period specified for implementation of FGD for new & old plants. Little progress made in last one year. - Two years not likely to be sufficient for implementation in view of time required for D & E,approvals, arrangement of funds, tendering, E&C etc. - 20,000 MW / annum in about 2,56,000 MW capacity (1,75,200 existing + 80,800 MW under construction) would take more than 10 years - Newer plants will get delayed due to the new norms. - Expected capacity may not come to the grid, as modifications / retrofits would require large shut downs affecting power supply. Disposal of Gypsum in environmentally friendly manner.

28 ISSUES & CHALLENGES (Contd.) Approx MW of total installed capacity of less than 500 MW units will be affected due to no availability of space for the retrofit. Holding back commissioning of the power plant units on account of non compliance of environmental standards may not be advisable as it could lead to contractual issues with equipment supplier of the power plants, establishment of guarantees of the power plant, etc. Increased Aux. Power Consumption with FGD operation (by %). Lime stone supply and gypsum off take chain needs to be augmented. Financing & Regulatory Problems: - Financing for investment required, impact of investment on cost of generation and Tariff approval remains one of the main concerns. - Weak financial health of discoms has already adversely affected power generators. - No regulatory guidance on technology options, cost benchmarks and approvals. While Capex is project specific, broad guidelines to be in place. - Process and documentation requirements for approval of Capex and Tariff is cumbersome

29 CONCLUSION & WAY FORWARD Promulgation of new environment norms by MoEF is a good move and these norms are comparable with the best in the world. Availability of FGD technology and its suitability for Indian Coals should not be a problem / impediment. However, in order to make implementation of the norms more practicable and better feasible, it is suggested that: Older units which have already lived half their life or more may be exempted from retrofits due to various technical constraints. Plants with firm retirement or replacement plans may be allowed to operate in interim Procurement & Installation of FGD could take up to 24 months. MoEF may therefore be requested to revisit implementation schedule and revise it. A more pragmatic time limit could be decided. Extension to be given on case to case basis based on firm commitments from the operators. Units of size less than 500 MW installed between 1990 and 2016 ( 54.2 GW) need to meet SOx norm of 600 mg/nm 3. These units may choose economical options such as partial FGD or sorbent injection.

30 CONCLUSION & WAY FORWARD Units of size 500 MW and more, installed between 1990 and 2016 (98.3 GW) have to install WET / DRY FGD depending on S - content in fuel, Reagent and water availability. CEA may prepare guideline / document detailing technological options, coal scenario, life cycle cost, O&M cost etc. including capital cost benchmarking. Electricity Regulators may devise simple documentation and approval procedure for CAPEX & Tariff. CAPEX and OPEX would have to be allowed by the regulators in tariff. Pollution Control Boards should develop monitoring mechanism for tracking the progress made by individual plants. Plant operators in consultation with CEA need to prepare a scheduled shut down plan so as to avoid / minimise supply disruptions. For financing of FGD Plants, Government should come up with support in the form of subsidized loans, credit enhancement, etc. Government should work on and formulate incentive plan for replacing old units with Supercritical Units. Incentives should also be considered by the Government for the plants that meet norms by the deadline.

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