Assessment of Air Quality in and Around Raichur Thermal Power Station, Raichur by IRJET Journal

Assessment of Air Quality in and Around Raichur Thermal Power Station, Raichur

Ashwini G1, Santosh Kumar2 , Nagesh Sugandhi3 Megha Yadav4

Abstract- Thermal power plant has led to significant degradation of ambient air quality due to the release of air pollutants from the combustion of fuel.

Raichur Thermal Power Station uses coal as a fuel to produce electricity. The present study was carried out to assess the ambient air quality levels in respect of suspended particulate matter (SPM), SO2 and NOx in certain areas of Raichur Thermal Power Station, Raichur. The study was carried out for a period 45 days. The ambient air quality was monitored at three places in and around RTPS to give the representative data. Themonitoring was donefor 24hours for every 10days. Similarly stack monitoring was carried out for all the 8 units of RTPS with an interval of 10 days. The pollution control equipment used at RTPS was Electrostatic Precipitator. The performance study of this equipment was carried out. It was found to operating well with an efficiency of 99.8% and more. The dispersion of particulate matter follows the annual predominant wind direction of an area. Therefore, to identify any possible cause and effect relationship between pollutant levels and climate changes, meteorological parameters, such as temperature, relative humidity, wind speed and direction were also monitored simultaneously during the sampling period of air pollutants.

Maximal concentration of SPM are found in the sensitive area i.e., Hospital region due to the wind patterns and the concentration gradually diminished with increase in distance due to transportation, deposition and dispersion of particles. Also the concentrations of the sulphur dioxide and oxides of nitrogen were not meeting the standards for any of the stacks.

Key Words: Suspendedparticulatematter(SPM),SO2,NOx, stack,ElectrostaticPrecipitator,meteorologicalparameters, samplingperiod,etc.,

1. INTRODUCTION

UrbanizationinIndiaismorerapidaroundthemajorcities in India. Increase in industrial activities, population both endemicandfloatingandvehicularpopulationetc,haveled toanumberofenvironmentalproblems,oneofthembeing airpollution.Variouscontaminantscontinuouslyenterthe atmospherethroughnaturalandman-madeprocessesand thesecontaminantsinteractwiththeenvironmenttocause disease,toxicity,environmentaldecayandarelabelledas

pollutant.AirPollutantsmeansanysolid,liquidorgaseous substance(includingnoise) presentintheatmospherein such concentration as may be or tend to be injurious to human beings or other living creatures, plants, property, andenvironment.Airpollutionisbasicallythepresenceof air pollutants in the atmosphere. The air has a relative constantcompositionofgasesandisutilizedbymostofthe livingorganismsinrespirationtoliberatechemicalenergy fortheirsurvival.Thiscompositiondeterminesitsquality andisbeingchangedintherecentpastduetoemissionof largeamountofun-naturalmaterialsintheatmosphereby industriesandautomobiles.Thischangedqualitybecamea great threat to survival of life, properties, materials and ecosystemasawhole.

In India, Industrial developments of urban centres have posed severe threat to air pollution due to uncontrolled emissionsofpollutantsintotheenvironment.Inthecourse ofenergyproduction,coal-firedpowerplantsdirectlyemit particulatematter(PM,sometimescalled“soot”)aswellas gasesthatundergochemicalreactionstoformfineparticles intheatmosphere,suchasSO2andNOx.Theseemissionsof PM,SO2 andNOx increasetheambientconcentrationofPM lessthan2.5micronsindiameter(PM2.5)overhundredsto thousandsofkilometersdownwindoftheplants.Exposure to PM2.5 has been consistently linked with increased mortalityfromcardiopulmonarydiseases,lungcancer,and numerous other respiratory illnesses and associated morbidity.

1.1 OBJECTIVES OF THE PRESENT STUDY

1. Todeterminetheconcentrationofmajorpollutants viz., SO2, NO2 and SPM in the ambient air in and aroundRTPS.

2. TomonitorthestackatdifferentunitsofRTPS.

3. To study the performance of Electrostatic precipitator.

4. Tocomparethequalityofthecollectedairsample withrespecttotheNAAQstandards.

1,2,3 Assistant Professor, Dept. of Civil Engineering, NIT Raichur, Karntaka, India. 4 Assistant Professor, Dept. of Civil Engineering, BITS Adoni, Andhra Pradesh, India

***

2. INDUSTRY AND ITS DESCRIPTION

2.1

Introduction:

Raichur Thermal Power Station (RTPS) is a coal-fired electric power station located at 16°21′18″N 77°20′31″E 16.355°N77.34194°EintheRaichurdistrictofthestateof Karnataka, India. It is operated by the Karnataka Power CorporationLimited(KPCL)anditaccountsforabout40% of the total electricity generated in Karnataka. RTPS has eightunitsof210MWeachforunits1-7and250MWfor8th unit and it is generating around 35-40 million units of energy/day TheprocessflowdiagramofRTPSisgivenin figure3.1.

2.4 Ash Handling System:

RTPSgeneratesabout1.5milliontonnesofflyashannually which causes environmental problems. 20% of the ash producediswetbottomashwhichisletintotheashbund. Ashremovalisdonebyhydro-pneumatic/jetpumps. The bottom ash resulting from the combustion of coal in the steam generator is collected in the water impounded bottom ash hopper. The ash so collected is fed once in a shiftof8hourstoclinkergrinderwhereitisground.Flyash is extracted sequentially from the hoppers located in the fluegaspathbycreatingvacuumintheextractioncircuit using high-pressure water pumped by vertical ash water pumps through ejectors or alternatively using vacuum pumps. The fly ash thus extracted is disposed of in wet form bymixingwithwaterinwettingunits andpumping theresultantslurrybyashslurrypumpstotheashdisposal area.

An efficient electrostatic precipitator (collection in efficiencyofabout99.89%)alongwithaproperlydesigned boilerwouldkeepthestackemissionofparticulatewithin acceptablelimits.

Asthesulphurcontentincoalislow(<0.4%),SO2generated duringcombustionwouldbenominal. Moreover,a stack heightof220mwouldlimitgroundlevelconcentrationof SO2 withinacceptablelimitsbyproperdispersion.Witha properlydesignedfurnaceandburnersystem,generationof COandNOx wouldbeminimized.

2.2 Coal Handling System:

The total quantity of coal required is around 8.0 million tonnes per annum. The coal is received at RTPS by conventional box ‘N” wagons. The present coal yard is capable of storing the coal for a period of 25 days comfortablyaspertheguide-linesoftheCentralElectricity Authority.

2.3 Raw Water & Water Treatment System:

Waterrequiredforthestationisaround160-180m3/day. Raw water supply to the plant as well for the colony is presentlydrawnfrom Krishna River throughthe existing intakepumphousewouldbeadequate.Toensureadequacy, and MOEF/KSPCB stipulations, treatment of waste water and recycling at the plant has been implemented. The stationdeploysre-circulatingcoolingwatersystemtomeet the cooling water requirement by adopting natural draft cooling towers. Make-up water supplied from raw water system is provided for condenser cooling. Eight natural draft cooling towers designed for a flow rate of 32,000m3/hr per unit with a design cold water outlet temperatureof36 Careprovided.

Thestationhasbeenaccreditedwith ISO 14001 - 2004 for environmental protection management. To minimize emissionofSuspendedParticulateMatter(SPM)alongwith boilerfluegasesElectrostaticPrecipitatorsofadequatesize withanefficiencyofmorethan99.93%isprovidedatexit endoftheboilertobringdownSPMemissionlevelunder 100mg/Nm3Alltheunitcontainssingle-flueRCCstack.The stackheightdetailsareasbelow.

Flyashproductionisoftheorderof15lakhtonsperannum with 7 units in operation. A sizeable portion of fly ash is alreadybeingconsumedbylocalcementindustries,namely ACCPlant,RajashreeCementandVasavadattaCementand localSSIunitsformanufactureofflyashbricks.

Fig -1:FlowdiagramofRTPS. Table -1: Stackheightsofalltheunits

Stack Height(m) Unit1&2 135 Unit3-8 220

3. MATERIALS AND METHODS

3.1 General

Theschemeofexperimentalmethodologywasformulatedto investigatethepotentialconcentrationofcriteriapollutants i.e.,SPM,SOx,NOxforaperiodof45daysfrom20/10/2011 to5/12/2011inandaroundRTPS,Raichur.

3.2 Ambient Air Quality Monitoring

Theambientairqualitymonitoringwascarriedoutatthree placesMainplantstationbuilding(Industrialarea),RTPS Hospital (Sensitive area), River water intake point (Restricted area) considering different criteria’s for selectingthesamplingstations.Thesamplingwasdonefor threetrials.

For the analysis of SPM and RSPM Aero Vironment’s “RespirableDustSamplerModelRDS9000”instrumentwas andsamplingwascarriedoutfor24hrs.

Fortheanalysisofsulphurdioxideambientairisinjected intoimpingeroftheinstrument“RespirableDustSampler Model RDS9000” having absorbent which is taken for chemicalanalysisaftersampling After30minsofreaction, absorbance is measured at 548nm. SOx concentration is determined using standard graph of absorbance against concentration

Analysis of oxides of nitrogen is same as SO2. Here the solution is kept for 15min for reaction to complete and absorbance is measured at 540nm. NOx concentration is determined using standard graph of absorbance against concentration.

3.3 Stack Monitoring

ThesamplingfortheanalysisofSPMiscarriedoutusingthe stack monitoring kit of Aero Vironment. The sample is drawnatthecalculatedflowratefor20mins.Theinitialand final weight of thimble is taken and the weight of dust collectedisfound.

The SOx and NOx in the stack are measured using the “QuintoxFlueGasAnalyser”.Theprobewhich sensesthe fluegasesinthestackisconnectedtotheinstrument.

Thesamplingwasdoneforallthe8unitsofRTPSanditwas carried out for three trials during the study period 20/10/2011to5/12/2011.

Table -2: TestingProcedure

Sl. No. Pollut ants Unit of Measureme nt Sampling Frequency Methods and Instrument Adopted AmbientAirQualityMonitoring 1. SPM mg/Nm3 24 hourly every10days Gravimetric (HighVolume) 2. RSPM mg/Nm3 24 hourly every10days Gravimetric (High-Volume withCyclone) 3. SO2 mg/Nm3 24 hourly every10days Colorimetric 4. NO2 mg/Nm3 24 hourly every10days Colorimetric StackMonitoring 1. SPM mg/Nm3 20min Stack MonitoringKit 2. SOx mg/Nm3 - Quintox Flue GasAnalyser 3. NOx mg/Nm3 - Quintox Flue GasAnalyser

Date Temperatur e DegC Humidity % Relativ e Humid ity Wind Speed M/S Wind Direction Rai nfa ll M m Min max Dry Wet Diff 20/10/211 37 22 18 15 3 53 1.3 EW21/10/11 37 24 28 16 12 55 1.0 NS22/10/11 38 22 19 16 3 61 1.2 EW24/10/11 37 24 18 15 3 63 1.3 NS26/10/11 37 27 25 17 7 64 2.0 ES 5.6 28/10/11 39 29 27 15 12 77 0.4 NS29/10/11 38 27 29 21 8 71 2.8 EW31/10/11 35 23 29 15 29 58 1.0 NS2/11/11 34 22 26 15 11 71 2.3 EW3/11/11 35 23 27 15 12 62 1.5 ES4/11/11 35 20 27 15 12 63 1.7 EW6/11/11 37 18 26 14 12 79 2.2 EW7/11/11 36 23 26 14 12 65 0.9 EN9/11/11 28 18 23 10 13 69 2.5 NS10/11/11 35 13 26 18 8 72 1.4 EW11/11/11 35 17 26 13 13 55 1.3 NS15/11/11 35 23 27 10 17 73 1.0 SN16/11/11 35 16 23 10 13 78 1.5 SN19/11/11 33 11 25 16 9 59 1.4 EW -

Table -3: Meteorologicaldataduringthestudyperiod

4.

Theresultsofanalysisoftheairpollutantsatanintervalof 10 days duration has been tabulated in the following differenttablesforaperiodof45days(from20/10/2011to 5/12/2011).

4.1

Table -4: Stackemissionsforunit1-7

ThetableshowsthatUnit-6hasamaximumSPMvalueof 162.2mg/Nm3 during second trial which is exceeding the limit,150mg/Nm3.Thereasonforhigherconcentrationof SPMinthestackmaybeduetoincompletecombustionof coalorlesserresidencetime(<34seconds)offluegasesin theESPwhichcausedthegasestomoveoutofESPbefore treating them. The table also clearly shows that all other unitsarewithinthelimitrange.

TheconcentrationofSOxandNOxarecrossingthelimitsfor alltheunits.Thereasonforthesehighconcentrationsmay beduetousageofunwashedcoal,highsulphurcontentof coalandcombustionprocesspresentlyimplementedsuch ashighexcessair.

4.2 Results of Ambient Air Quality Monitoring:

Table -6: AmbientAirQualityMonitoring

*theunitwasshutdownduringthatdayoftrial.

Table -5: StackEmissionvaluesminimumandmaximum forthestudyperiod

Hospital

AAQM-2 Stationbuilding

AAQM-3 Intake

Table -7: AmbientAirQualityMonitoringvaluesminand maxforthestudyperiod

Thetableshowsthatduring1sttrialTSPMvaluesforAAQM1i.e.,Hospitalregion(Sensitivearea)isexceedingthelimit due to dispersion patterns and all other pollutants are withintherangeforallregions.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 10 Issue: 03 | Mar 2023 www.irjet.net p-ISSN: 2395-0072 © 2023, IRJET | Impact Factor value: 8.226 | ISO 9001:2008 Certified Journal | Page491 21/11/11 36 12 25 16 9 65 1.5 NS22/11/11 34 16 25 12 13 70 0.6 NW23/11/11 33 12 25 18 7 67 1.0 NS24/11/11 33 18 24 12 13 70 2.0 NE25/11/11 35 22 25 14 11 59 0.6 NE27/11/11 32 19 24 14 10 72 3.0 NE 1.5 28/11/11 31 21 26 14 12 71 2.8 NS -

Results and Discussion Results of Stack Monitoring:

Parameter mg/Nm3 SPM SOx NOx Min Max Min Max Min Max Unit-1 89.2 91.04 1397 2095 50 464 Unit-2 56.88 82.58 294 355 247 300 Unit-3 54 90.48 48 1398 11 550 Unit-4 41.3 112 242 1221 209 217 Unit-5 43.7 112 520 1296 310 440 Unit-6 108 162.2 699 775 201 239 Unit-7 79 145 570 886 301 320

AAQM-1 AAQM-2 AAQM-3 Param eter Mg/N m3 TSP M RSP M SO 2 N O2 TSP M RSP M SO 2 N O2 TSP M RSP M SO 2 N O2 1st set 130 25. 4 28 32 112 36. 24 24 20 39 19 26 28 2nd set 93 58. 2 26 22 10. 98 4.0 6 19 17 41. 3 20 24 20 3rd set 96. 5 63. 8 20 17 11. 87 4.5 5 20 15 47 23 20 17 Avg 106 .5 49. 1 25 24 44. 95 14. 95 21 17 42. 4 21 23 22 Limits 100 75 30 35 500 150 12 0 12 0 200 100 80 80

AAQM-1

Parameter mg/Nm3 AAQM-1 AAQM-2 AAQM-3 Min Max Min Max Min Max TSPM 93 130 10.98 112 39 47 RSPM 25.4 63.8 4.06 36.24 19 23 SO2 20 28 19 24 20 26 NO2 17 32 15 20 17 28

4.3 Results of Performance Study of Electrostatic Precipitator:

The performance study of the Electrostatic Precipitator clearlyshowsthatthealltheESP’sofalltheunitsaremore than99.37%efficient.

Table -9: DetailsofCollectingElectrode(CE)

Table -10:

5. Conclusions and Recommendations

5.1 Conclusion

Basedontheanalysiscarriedoutduringthestudyperiod thefollowingconclusionscanbedrawn:

1. The concentrations of Suspended Particulate Matter(SPM)areallwithintheprescribedNAAQ limitsexceptattheHospitalregion.

2. The concentrations of Sulphur Dioxide (SO2), Oxides of Nitrogen (NOx), Respirable Particulate Matter (RSPM) at all the locations is within the prescribed limits when ambient air quality monitoringwasdone.

Table -8: Detailsofelectrostaticprecipitatorsofunit1to8 Sl. N o Design param eters Unit1&2 Unit3 Unit4 Unit5&6 Unit-7 Unit8 1. Type ofESP 2FAA6X321119 0-2 FAA6X452X90 125-2 FAA6X452X84 125-2 FAA6X452X961 25-2 FAA6X452X961 25-2 FAA6X45 H2X12 01352 2 Specifi c Collect ing Area (SCA) 147.3 2 m2/ m3/s ec 227.5 3 m2/ m3/s ec 209.3 7 m2/ m3/s ec 226.80 m2/m3 /sec 226.80 m2/m3 /sec 316.4 4 m2/ m3/s ec 3. Gas flow rate 347.2 m3/S ec 356 m3/S ec 353.8 8 m3/S ec 380.93 m3/Se c 380.93 m3/Se c 449.5 m3/S ec 4. FG Tempe rature 140 degC 138 degC 134 degC 150 degC 150 degC 127 degC 5. Dust concen tration 30.2 gm/N m3 67.5 gm/N m3 55.42 gm/N m3 83.36 gm/N m3 83.36 gm/N m3 83.28 gm/N m3 6. No.of Gas paths per Boiler FOUR TWO TWO TWO TWO TWO 7. No.of fieldin series SIX SIX SIX SIX SIX SEVE N 8. Guante ed Collect ion Efficie ncy (GCE) 99.37 % 99.78 % 99.83 % 99.82 % 99.82 % 99.87 % 9. Pressu re drop across the ESP 18 mmW C 18 mmW C 18 mmW C 20 mmWC 20 mmWC 20 mmW C 10 Velocit yof gasat Electro de zone on total area 0.87 m/se c 0.791 m/se c 0.85 m/se c 0.79 m/sec 0.79 m/sec 0.57 m/se c 11 . Treati ng time 22.1 Sec 34.13 Sec 34.13 Sec 34.18 Sec 34.18 Sec 55.37 Sec

1 No.rowsof CEperfield. 38 61 61 65 65 81 2 No.ofCE perfield. 304(8 plates/ row) 366(6 plates /row) 366(6 plates /row) 390(6 plates /row) 390(6 plates /row) 486(6 plates /row) 3 TotalNo. collecting electrode 7296 4392 4392 4680 4680 6804 4 Nominal heightofCE 9mtrs 12.5 mtrs 12.5 mtrs 12.5 mtrs 12.5 mtrs 13.5 mtrs 5 Nominal widthofCE 400mm 750 mm 750 mm 750 mm 750 mm 750 mm

1 TypeofE Spiral with hook s Spiral with hooks Spiral with hooks Spiral with hooks Spiral with hooks Spiral with hooks 2 SizeofE 2.7m m 2.7mm 2.7mm 2.7mm 2.7mm 2.7mm 3 No.ofE perfield 1184 3240 3240 3456 3456 4320 4 TotalNo. of E 2841 6 38800 36288 41472 41472 60480 5 Espacing plate/ wire 150m m/12 5mm 150mm /250m m 150mm /250m m 150mm /250m m 150mm /250m m 150m m/300 mm 6 CE rapping hammer weight 6.3 Kg 4.9Kg 4.9Kg 4.9Kg 4.9Kg 4.9Kg 7 EE rapping hammer weight 4.9 Kg 3.0Kg 3.0Kg 3.0Kg 3.0Kg 3.0Kg E-Electrode

DetailsofEmittingElectrode(EE)

3. It can also be concluded that the SPM concentrationsforall7unitsarewithinthe NAAQ standards.

4. TheSOxconcentrationandNOxconcentrationsare allexceedingthelimitsforalltheunits.

5. It can be concluded that the Electrostatic Precipitator (ESP) of all the units is performing wellwithanefficiencyofmorethan99.78%.

5.2 Recommendations to Reduce the Air Pollution

1. Equally stringent emission norms for industries needtobeenforcedformitigationofairpollution.

2. It is advocated to develop a green belt in the pollutedregionofthecitiesasoneofthecontrol measures.

3. The SOx emissions can be controlled by coal washing/beneficiation and by providing sulphur removalplantatthepre-combustionstage.

4. During the combustion stage by adding the limestonetheproductionofSOx canbelimited.

5. AndalsobyprovidingFlueGasDesulphurization (FGD)plantattheemissionends,theemissionof SOx intotheaircanbereduced.

6. NOx emissions can be controlled by combustion modification: low-NOx burners with or without overfireairorre-burning,water/steaminjection, and selective catalytic or non-catalytic reduction (SCR/SNCR).

6. REFERENCES

[1] A.ChandraandIson.V.Vanchipurackal,Performance upgradation of ESPs using difficult coal, Proc. Of 8th InternationalConferenceonElectrostaticPrecipitation, vol.2,pp.B3-1,May,14-17,2001.

[2] A. Chandra, Some Investigation on ESP Unit: Determination Improvemnet of Collection Efficiency, Proc. Of 7th International Conference on Electrostatic Precipitation,pp.499-507,September,20-25,1998.

[3] Air Pollution Sampling and Analysis (Laboratory Manual) Dr. Sharad Gokhale Department of Civil Engineering Indian Institute of Technology Guwahati Date:May2009.

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[5] EPA Methods 6010, 6020, 7000, 7041, 7060, 7131, 7421, 7470, 7740, and 7841, Test Methods for Evaluating Solid Waste: Physical/Chemical Methods. SW-846,ThirdEdition,November1986,withupdatesI, II, IIA and IIB. Office of Solid Waste and Emergency Response, U. S. Environmental Protection Agency, Washington,D.C.20460.

[6] H. J. White, Industrial Electrostatic Precipitation, International Society for Electrostatic Precipitation, 1988.

[7] NTPCLimited,2006. Environmental Assessment Report, India: Sipat Super Thermal Power Project (StageI andII) and Kahalgaon Super Thermal Power Project (Stage II) Prepared for the Asian Development Bank (ADB) Available at adb.org/Documents/Environment/Ind/39916-INDSEIA.pdf.

[8] Tavoulareas, E. Stratos, and Jean-Pierre Charpentier. 1995. Clean Coal Technologies for Developing Countries. World Bank Technical Paper 286, Energy Series. Washington,D.C.

[9] Techincal EIA Guidance Manual for Themal Power Plants,IL&FSEnvironment,GovernmentofIndia.

[10] World Bank Group, July 1998 “Thermal Power: Guidelines for New Plants”, Pollution Prevention and AbatementHandbook.