An Evaluation of Evaporative Emissions of
Gasoline from Storage Sites and Service Stations
By: J.S. Razavizadeh
Supervisor: Prof. H.S. Ghaziaskar
Tuesday 88.02.22 , 11.00 am
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
•The hydrocarbons emitted during petrol storage and distribution
can be broadly classified as volatile organic compounds (VOCs)
1-Pure hydrocarbons
VOCs
2-Partially oxidized hydrocarbons
3-Organics containing chlorine , sulphur and nitrogen
1-Industrial and domestic solvents(40%)
2-exhaust gases from motor vehicles(25%)
3-Evaporation and loses from motor vehicle(10%)
VOCs emissions originate from
4-Petrol distribution(3%)
5-Vehicle refueling(2%)
6-Oil refining (3%)
7- from other source(17%)
Oxygen Molecule (O2) + NOx + VOC +
Sunlight
Ozone Molecule (O3)
Typical petrol distribution
Products storage
At refinery
Rail car
Pipe line
Marine vessel
Bulk storage at
Marketing depot
Road tanker
Storage tank at
service station
Motor vehicle
Typical petrol vapor composition (only VOC)
COMPUND
VOLUME
Ethane
Traces
Propane
1.5%
Isobutane
8%
n-Butane
10%
Pentane
14%
Benzene
5000ppm
Hexane and others
TOTAL
(voc only, remainder in air)
6%
40%
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
0.3
0.03
filling
0.05
0.18
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.
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 < 0,Ol) when the previous contents of a road tanker were a nonvolatile 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.
•
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.
1.
2.
3.
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
filling emission
liquid to vapor
volume equivalence
factor
Average preloading
vapor concentration
Parameter representing
the amount of splashing
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.
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
Emission prevention and minimisatim
•
•
•
•
decreasing the volatility of petrol
vapor balancing
minimizing the liquid/vapour interface area
reducing turbulence.
Typical construction of a modern day tanker
Tanker at Terminal
(No Vapor Recovery)
Tanker at Service Station
(No Vapor Recovery)
Bottom Loading at Terminal
(With Vapor Recovery)
Fuel Drop at Service Station
(With Vapor Recovery)
API to Drop Hose Connection
(At Service Station)
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.
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 cooling
Condensation is most efficient for VOC recovery at relatively high VOC
concentration (above 5000 ppm)
Air
VOC/air
mixture
Step1
collection
Step2 and 3
Separation and
Recovery via
condensation
Flow diagram for condensation as vapor recovery process.
Condensed
VOCs
Advantage and disadvantage of condensation
Advantage
Disadvantage
Moderate efficiencies, 50-90%
Energy requirements of Mechanical
refrigeration are high
Simple, flexible, safe process
Can handle wide range of products
Nitrogen source needed for cryogenic
condensation
May result in the generation of a
wastewater stream
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
VOC /air
mixture
Step1
collection
Step2
Separation from
Air via absorption
(with kerosene)
Recycling of
Absorbent (kerosene)
Absorbent
(petrol)/VOC
mixture
Step3
Recovery via
Absorption
(with petrol)
Absorbent
(kerosene)/
VOC mixture
Separation from
Absorbent via
distillation
VOC
• Absorption can be used for high vapor flows and VOC concentration ranging
between 500 ppm to 5000 ppm.
Advantage and disadvantage of absorption
Advantage
Good for high humidity streams
(relative humidity < 50%)
High efficiencies, 95_98%
Wide range of vapor flow rates and
VOC concentration
Disadvantage
Liquid absorbent may be transferred
to the exit gas
Diffusion technologies: such as membrane is relatively new
Two types of membrane namely diffusion membrane and solubility
membrane.
air
VOC /air
mixture
Step1
collection
Step2
Separation via
diffusion
Step3
Recovery via
absorption
Step3
Recovery via
condensation
VOC /absorbent
mixture
Condensed
VOCs
Advantage and disadvantage of diffusion technology
Advantage
Disadvantage
Recovery of between 95 and 99%
Constant vapor flow rate are Necessary,
but buffer tanks are a major safety
concern
Safe process and operational flexibility
High power consumption
Very wide range of products handling,
for example ,hydrogen, Sulphide ,
acetone , MTBA, ethyl acetate
Post treatment system needed in The
case of very high emission standards.
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
VOC /air
mixture
Step1
collection
Step2
Separation via
adsorption
Step3
Recovery via
absorption
Step3
Recovery via
condensation
VOC /absorbent
mixture
Condensed
VOCs
Advantages and disadvantages of adsorption
advantages
Wide range of vapor and vapor
concentration can be handled .
disadvantages
Hydrogen sulphide from crude oil
vapor poison the carbon.
Efficient, relatively simple process organic compounds like ketones,
aldehydes and organic acids can
causes localised hot spots or bedfires
in carbon beds.
Flexible and inexpensive to
operate
Light hydrocarbon fraction such as
methane are very poorly adsorbed
Carbon performance decreases with
high humidity vapor streams (ralative
humidity <50%)
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-Forschungszentrum Geesthacht GmbH, Institut für Chemie, Max-Planck-Strasse, D21502 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, Ramūnas 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@umist.ac.uk Tel. 0161 200 3715 Dr Richard
Starkey, Tyndall North, UMIST
Questions?