Presentation on theme: "Supervisor: Prof. H.S. Ghaziaskar"— Presentation transcript:
1 Supervisor: Prof. H.S. Ghaziaskar An Evaluation of Evaporative Emissions of Gasoline from Storage Sites and Service StationsBy: J.S. RazavizadehSupervisor: Prof. H.S. GhaziaskarTuesday , am
2 5-Legislation regarding evaporative emissions Displacement emissions1- IntroductionBreathing and withdrawal emissions2- Evaporative emissionsFilling emissionsEmission from vehicle refuelingEmissions prevention and minimization3- Factors affecting evaporationCollection of vaporabsorption4-control of emissionsVapor recoveryPressure swing and purge regenerationCondensationDiffusion technologiesTreatment of vapor5-Legislation regarding evaporative emissions
3 The hydrocarbons emitted during petrol storage and distribution can be broadly classified as volatile organic compounds (VOCs)1-Pure hydrocarbonsVOCs2-Partially oxidized hydrocarbons3-Organics containing chlorine , sulphur and nitrogen1-Industrial and domestic solvents(40%)1-Industrial and domestic solvents(40%)2-exhaust gases from motor vehicles(25%)2-exhaust gases from motor vehicles(25%)3-Evaporation and loses from motor vehicle(10%)VOCs emissions originate from4-Petrol distribution(3%)5-Vehicle refueling(2%)6-Oil refining (3%)7- from other source(17%)
7 Typical petrol vapor composition (only VOC) VOLUMECOMPUNDTracesEthane1.5%Propane8%Isobutane10%n-Butane14%Pentane5000ppmBenzene6%Hexane and others40%TOTAL(voc only, remainder in air)
8 EVAPORATIVE EMISSIONS the average emission from a typical European petrol storage and distribution system, is O.56% volume of the petrol distributeddisplacementrefuelingbreathing and withdrawalfilling0.30.030.050.18
9 Displacement emissions Breathing and withdrawal emissions Displacement emissions occur from fixed roof storage facilities (bulk storage tanks), as well as underground service station tanks due to vapor displacement by incoming petrol.Displacement emissions from fixed roof storage facilities account for 0,14 %from service station storage tanks for 0,16 %Breathing and withdrawal emissionsBreathing emissions are caused by variations in tank contents, temperature and by changes in barometric pressures that cause expansion and contraction of the liquid and vapor in a tank.Withdrawal emissions occur when petrol is pumped out of a storage tank resulting in the intake of air through pressure/vacuum relief valves or ventsBreathing and withdrawal emissions from bulk storage tanks account for 0,02% and from service station storage tanks for 0,01% of total emission losses.
10 Filling emissionsFilling emissions occur when petrol is transferred from storage tanks to road tankers.two types of vapor making up filling emissions, namely preloading vapor (PLV) and evolution vapor (Ve).PLV is residual vapor originating from a tank's previous contents, being displaced by loading of the new product, and is defined as a fraction or percentage of full saturation, Cp,.Cp less than 1 % (Cp < 0,Ol) when the previous contents of a road tanker were a non-volatile product.Cp between 10% and 20% (0,l < Cp < 0,2) when the previous contents of a tanker were discharged completely at one point.Cp between 30% and 50% (0,3 < Cp < 0,5) when the previous contents were discharged at several occasions.Cp between 90% and 100% (0,9 < Cp < 1,O) when the contents of a tanker were discharged at a service station tank that allows for vapor return.
11 Evolution vapour (ve) evaporates from the product itself when it is being loaded. Petrol can be loaded into a road tanker via top splash loading, submerged top loading or bottom loading.In order to estimate Ve a parameter VB is used to represent the amount of splashing in a tanker during filling.VB is equal to the fraction of the original tank atmosphere that is assumed to be completely saturated during loading.VB = 0,4 for top splash loading.VB = 0,15 for submerged top loading.VB = 0,13 for bottom loading.Concentration of petrol vaporunder equilibrium conditionsParameter representingthe amount of splashingfilling emissionliquid to vaporvolume equivalencefactorAverage preloadingvapor concentration
12 Emissions from vehicle refueling These emissions contribute to 0,18 volume % of the total emissions from petrol storage and distribution systems1- product (liquid petrol) properties.FACTORSAFFECTINGEVAPORATION2- Liquid/vapor interface areas.3- turbulence in the relevant liquid and vapor.
13 Control of emission Safe operation Ease of operation Reliable operationLow maintenanceLow operation costsLow investment costsHighest possible emission reduction.Emissions prevention and minimizationCollection of vaporabsorption4-control of emissionsVapor recoveryPressure swing and purge regenerationCondensationDiffusion technologiesTreatment of vapor
27 Condensation: by compression or cooling Once the vapor has been collected, various processes or combinations of processes can be used to separate and recover the vapor. These include condensation, absorption, diffusion and adsorption.Condensation: by compression or coolingCondensation is most efficient for VOC recovery at relatively high VOCconcentration (above 5000 ppm)AirStep2 and 3Separation andRecovery viacondensationStep1collectionVOC/airmixtureCondensedVOCsFlow diagram for condensation as vapor recovery process.
28 Disadvantage Advantage Advantage and disadvantage of condensationDisadvantageAdvantageEnergy requirements of Mechanical refrigeration are highModerate efficiencies, 50-90%Nitrogen source needed for cryogenic condensationSimple, flexible, safe processMay result in the generation of a wastewater streamCan handle wide range of products
29 Absorption : absorbed in to liquid due to molecular force. depends of vapor pressure and the temperature of the absorbent.Low boiling point hydrocarbon liquid( like crude oil or kerosene) are often used for VOC separation from air via absorption.airStep2Separation fromAir via absorption(with kerosene)Step1collectionAbsorbent(kerosene)/VOC mixtureVOC /airmixtureRecycling ofAbsorbent (kerosene)Separation fromAbsorbent viadistillationStep3Recovery viaAbsorption(with petrol)Absorbent(petrol)/VOCmixtureVOC
30 Wide range of vapor flow rates and VOC concentration Absorption can be used for high vapor flows and VOC concentration ranging between 500 ppm to 5000 ppm.Advantage and disadvantage of absorptionDisadvantageAdvantageLiquid absorbent may be transferred to the exit gasGood for high humidity streams(relative humidity < 50%)High efficiencies, 95_98%Wide range of vapor flow rates and VOC concentration
31 Diffusion technologies: such as membrane is relatively new Two types of membrane namely diffusion membrane and solubility membrane.airStep2Separation viadiffusionVOC /airmixtureStep1collectionStep3Recovery viaabsorptionStep3Recovery viacondensationVOC /absorbentmixtureCondensedVOCs
32 Disadvantage Advantage Advantage and disadvantage of diffusion technologyDisadvantageAdvantageConstant vapor flow rate are Necessary, but buffer tanks are a major safety concernRecovery of between 95 and 99%High power consumptionSafe process and operational flexibilityPost treatment system needed in The case of very high emission standards.Very wide range of products handling, for example ,hydrogen, Sulphide , acetone , MTBA, ethyl acetate
33 Adsorption: most effective methods and most economical. the adsorption medium most generally used is activated carbon and hydrophobic zeolites.two regeneration technologies are currently in use, namely: thermal regeneration and pressure swing and purge regeneration.airStep2Separation viaadsorptionStep1collectionVOC /airmixtureStep3Recovery viaabsorptionStep3Recovery viacondensationCondensedVOCsVOC /absorbentmixture
34 disadvantages advantages Advantages and disadvantages of adsorptiondisadvantagesadvantagesHydrogen sulphide from crude oil vapor poison the carbon.Wide range of vapor and vapor concentration can be handled .organic compounds like ketones, aldehydes and organic acids can causes localised hot spots or bedfires in carbon beds.Efficient, relatively simple processLight hydrocarbon fraction such as methane are very poorly adsorbedFlexible and inexpensive to operateCarbon performance decreases with high humidity vapor streams (ralative humidity <50%)
36 References:MEMBRANES FOR VAPOR/GAS SEPARATION Richard W. Baker Membrane Technology and Research, Inc Willow Road, Suite 103, Menlo Park, CA 94025NEW TECHNOLOGY FOR EMISSION REDUCTION AT PETROL STATIONS OHLROGGE K., WIND J. GKSS-Forschungszentrum Geesthacht GmbH, Institut für Chemie, Max-Planck-Strasse, D Geesthacht, GermanySafety design of a petrol pump attendant robot Francesco Becchi, Rezia M. Molfino and Roberto P. Razzoli University of Genova, Genova, ItalyThe Problem of Volatile Organic Compound (VOC) Emissionsfrom Petrol in Lithuania and Methodological Aspects of Emission Reduction Viktoras Doroševas, Vitalijus Volkovas, Ramūnas Gulbinas Technological Systems Diagostics Institute, Kaunas University of TechnologyMembrane Based Vapor Recovery at Petrol Stations Klaus Ohlrogge and Jan WindA policy instrument for the reduction of greenhouse gas emissions An Interim Report to the Tyndall Centre for Climate Change Research 7th |January 2004 Dr Kevin Anderson, Tyndall North, UMIST Tel Dr Richard Starkey, Tyndall North, UMIST