An Evaluation of Evaporative Emissions of Gasoline from Storage Sites and Service Stations

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An Evaluation of Evaporative Emissions
ofGasoline from Storage Sites and Service
Stations
By J.S. Razavizadeh Supervisor Prof. H.S.
Ghaziaskar Tuesday 88.02.22 , 11.00 am
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Displacement emissions
1- Introduction
Breathing and withdrawal emissions
2- Evaporative emissions
Filling emissions
Emission from vehicle refueling
Emissions prevention and minimization
3- Factors affecting evaporation
Collection of vapor
absorption
4-control of emissions
Vapor recovery
Pressure swing and purge regeneration
Condensation
Diffusion technologies
Treatment of vapor
5-Legislation regarding evaporative emissions
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• The hydrocarbons emitted during petrol storage
  and distribution
• can be broadly classified as volatile organic
  compounds (VOCs)

1-Pure hydrocarbons
2-Partially oxidized hydrocarbons
VOCs
3-Organics containing chlorine , sulphur and
nitrogen
1-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)
4-Petrol distribution(3)
VOCs emissions originate from
5-Vehicle refueling(2)
6-Oil refining (3)
7- from other source(17)
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Oxygen Molecule (O2) NOx VOC
Sunlight
Ozone Molecule (O3)
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Typical petrol distribution
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Typical petrol vapor composition (only VOC)
VOLUME COMPUND
Traces Ethane
1.5 Propane
8 Isobutane
10 n-Butane
14 Pentane
5000ppm Benzene
6 Hexane and others
40 TOTAL (voc only, remainder in air)
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EVAPORATIVE EMISSIONS

• the average emission from a typical European
  petrol storage and distribution system, is O.56
  volume of the petrol distributed

displacement
refueling
breathing and withdrawal
filling
0.3
0.03
0.18
0.05
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• Displacement 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 emissions
• Breathing 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
  vents
• Breathing and withdrawal emissions from bulk
  storage tanks account for 0,02 and from service
  station storage tanks for 0,01 of total emission
  losses.

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• Filling emissions
• Filling 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 lt 0,Ol) when the previous
  contents of a road tanker were a non-volatile
  product.
• Cp between 10 and 20 (0,l lt Cp lt 0,2) when the
  previous contents of a tanker were discharged
  completely at one point.
• Cp between 30 and 50 (0,3 lt Cp lt 0,5) when the
  previous contents were discharged at several
  occasions.
• Cp between 90 and 100 (0,9 lt Cp lt 1,O) when the
  contents of a tanker were discharged at a service
  station tank that allows for vapor return.

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• 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 vapor under equilibrium
conditions
Parameter representing the amount of splashing
filling emission
liquid to vapor volume equivalence factor
Average preloading vapor concentration
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Emissions from vehicle refueling

• These emissions contribute to 0,18 volume of
  the total emissions from petrol storage and
  distribution systems

1- product (liquid petrol) properties.
FACTORS AFFECTING EVAPORATION
2- Liquid/vapor interface areas.
3- turbulence in the relevant liquid and vapor.
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Control of emission

• Safe operation
• Ease of operation
• Reliable operation
• Low maintenance
• Low operation costs
• Low investment costs
• Highest possible emission reduction.

Emissions prevention and minimization
Collection of vapor
absorption
4-control of emissions
Vapor recovery
Pressure swing and purge regeneration
Condensation
Diffusion technologies
Treatment of vapor
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Emission prevention and minimisatim

• decreasing the volatility of petrol
• vapor balancing
• minimizing the liquid/vapour interface area
• reducing turbulence.

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Typical construction of a modern day tanker
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Tanker at Terminal(No Vapor Recovery)
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Tanker at Service Station(No Vapor Recovery)
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Bottom Loading at Terminal(With Vapor Recovery)
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Fuel Drop at Service Station(With Vapor Recovery)
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API to Drop Hose Connection(At Service Station)
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Vapour recovery
Step 1 collection of VOCs/air mixture Step 2
separation of VOCs from air Step 3 the recovery
of the separated VOCs into liquid state.
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Once the vapor has been collected, various
processes or combinations ofprocesses can be
used to separate and recover the vapor. These
include condensation, absorption, diffusion and
adsorption.

• Condensation by compression or cooling
• Condensation is most efficient for VOC recovery
  at relatively high VOC
• concentration (above 5000 ppm)

Air
Step2 and 3 Separation and Recovery
via condensation
Step1 collection
VOC/air mixture
Condensed VOCs
Flow diagram for condensation as vapor recovery
process.
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Advantage and disadvantage of condensation
Disadvantage Advantage
Energy requirements of Mechanical refrigeration are high Moderate efficiencies, 50-90
Nitrogen source needed for cryogenic condensation Simple, flexible, safe process
May result in the generation of a wastewater stream Can handle wide range of products
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• 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.

air
Step2 Separation from Air via absorption (with
kerosene)
Step1 collection
Absorbent (kerosene)/ VOC mixture
VOC /air mixture
Recycling of Absorbent (kerosene)
Separation from Absorbent via distillation
Step3 Recovery via Absorption (with petrol)
Absorbent (petrol)/VOC mixture
VOC
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• Absorption can be used for high vapor flows and
  VOC concentration ranging between 500 ppm to 5000
  ppm.

Advantage and disadvantage of absorption
Disadvantage Advantage
Liquid absorbent may be transferred to the exit gas Good for high humidity streams (relative humidity lt 50)
High efficiencies, 95_98
Wide range of vapor flow rates and VOC concentration
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• Diffusion technologies such as membrane is
  relatively new
• Two types of membrane namely diffusion membrane
  and solubility membrane.

air
Step2 Separation via diffusion
VOC /air mixture
Step1 collection
Step3 Recovery via condensation
Step3 Recovery via absorption
VOC /absorbent mixture
Condensed VOCs
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Advantage and disadvantage of diffusion technology
Disadvantage Advantage
Constant vapor flow rate are Necessary, but buffer tanks are a major safety concern Recovery of between 95 and 99
High power consumption Safe process and operational flexibility
Post 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
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• 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.

air
Step2 Separation via adsorption
Step1 collection
VOC /air mixture
Step3 Recovery via condensation
Step3 Recovery via absorption
Condensed VOCs
VOC /absorbent mixture
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Advantages and disadvantages of adsorption
disadvantages advantages
Hydrogen 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 process
Light hydrocarbon fraction such as methane are very poorly adsorbed Flexible and inexpensive to operate
Carbon performance decreases with high humidity vapor streams (ralative humidity lt50)
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1. References
2. MEMBRANES FOR VAPOR/GAS SEPARATION Richard W.
   Baker Membrane Technology and Research, Inc. 1360
   Willow Road, Suite 103, Menlo Park, CA 94025
3. NEW TECHNOLOGY FOR EMISSION REDUCTION AT PETROL
   STATIONS OHLROGGE K., WIND J. GKSS-Forschungszentr
   um Geesthacht GmbH, Institut für Chemie,
   Max-Planck-Strasse, D-21502 Geesthacht, Germany
4. Safety design of a petrol pump attendant robot
   Francesco Becchi, Rezia M. Molfino and Roberto P.
   Razzoli University of Genova, Genova, Italy
5. The Problem of Volatile Organic Compound (VOC)
   Emissionsfrom Petrol in Lithuania and
   Methodological Aspects of Emission Reduction
   Viktoras Doroševas, Vitalijus Volkovas, Ramunas
   Gulbinas Technological Systems Diagostics
   Institute, Kaunas University of Technology
6. Membrane Based Vapor Recovery at Petrol Stations
   Klaus Ohlrogge and Jan Wind
7. A 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 Kevin.anderson_at_umist.ac.uk Tel. [phone]
   3715 Dr Richard Starkey, Tyndall North, UMIST

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Questions?