Joy Western Precipitation Microdyne Scrubber

THE JOY MICRODYNE has three main sections: a mixer section, an eliminator section, and a booster fan section; all shown in the cutaway view. Air and entrained dust particles enter the mixer section of the scrubber under suction from the booster fan. Water sprays entering the unit supply a heavy boundary layer of water on the impingement element through which the dust-laden air must pass. As the dusty air passes through the impingement element, the dust par­ticles are forced to encase themselves in water, thus increasing their effective mass many times.

Leaving the impinger, the dust-laden water droplets and air enter the eliminator section of the unit. The eliminator section imparts a strong helical motion to the gas, and this cyclonic action dynamically separates the entrained droplets from the air stream. The cyclonic action drives the droplets to the surface of blind louvres, each of which is a separate air-tight elimination chamber.

The unmatched compactness of this "Edu­cated Pipe" is illustrated by comparison with other scrubbers commercially available. A 40,000 CFM unit of the old type will weigh over 50,000 lbs. A JOY MICRODYNE of the same rating weighs less than 3,000 lbs.

Moderate water rates seldom exceeding 1 gallon per 1,000 cubic feet of gas or air handled, allow for easy integration into the existing plant water system.

If corrosion is a problem, the unit can be fabricated from Type 304 or 316 stainless steel, or from other metal alloys.

All parts are easily accessible for maintenance. Result: Unusually low operating costs for un­usually high efficiency dust collection. Particle size efficiency on dust particles 5 microns and larger in size exceeds 99%.

JOY MICRODYNE is available in sizes from 2,500 to 64,000 CFM.

Typical installations in Australia include conveyor belt discharge points in coal, lead, zinc and copper mines; acid fume and other process discharges; crushing and grinding dusts DUCT SIZE 11" 15" 17" 19" 23¼" 28" 34" 40" 48" 54" C.F.M. 2500 4000 6000 8000 12,000 16,000 24,000 32,000 48,000 64,000

JOY MANUFACTURING COMPANY PTY. LTD./78-86 KENT ROAD, MASCOT, N.S.W. 2020/TEL: 67 5161

A Keener 'Nose' for S02 The air we have to live on is becoming more and more polluted by the by-products of industry and transport. Monitoring the level of pollution could be a step towards its control. Sulphur dioxide has long been recognised as a reliable indicator of the state of air pollution in many localities. Information about the S0 2 level in the air, as a function of place and time, could indicate, and even predict, dangerous situations. However, SO2 detectors have hitherto required too much supervision to be suit­able for a large operating system.

When Mr. H.J. Brouwer at Philips Research Labora­tories, in consultation with Mr. H. Zeedijk from the Eindhoven Technical University, started the design of an improved S0 2 monitor, he realized that a built-in, reliable chemical calibration source would greatly reduce problems of long term accu'racy. Furthermore, the measuring cell proper should require a minimum of maintenance.

Unlike most of its fore-runners, the new monitor functions on the principle of continuous coulometric titration. When S02 enters the cell, it reacts with bromine, thereby lowering the Br2 concentration and thus the redox potential.This is sensed by the measuring electrode, which, via an amplifier, controls an electric current into the solution. This current replenishes Br2

by electrolysis of KBr and is a direct measure of momentary S02 contents of the air.

The S02 calibration source consists of a vessel, with a small hole, filled with S02. The hole is covered with a plastic membrane into which SO2 may dissolve. S02 diffuses through the membrane and evaporates at the other side. The product of solubility and diffusion constant, which determines the 'leakage' has a temper­ature coefficient of only one per cent per degree C. A simple thermostat suffices to keep the required accuracy.

Dust, 03 and H2S are filtered from the incoming air-stream, because the latter two would react with

the cell contents in a way similar to S0 2 . An air flow switching system. provides for three states-'zero', 'cali­brate', and 'measure'. In the 'zero' position the air first passes an active coal filter, which removes S0 2 . Trie-loss of bromine then indicated by the current is due to evaporation. In the 'calibrate' position the cleaned air-passes the S02-source and is thus polluted to a known extent. This fixes a second point on the linear scale. In the 'measure' position the air stream, with unknown S02 contents, is led through the cell.

The detection limit, as well as the zero drift per day, obtained with the new monitor, is down to below 0.01 parts per million, a level typical for a nature park - in a non-volcanic region, of course.

We now have a monitor, able to provide stable, unattended operation for periods up to three months, as required in a national system for automatically monitoring the air above the Dutch polders.

For further information on pollution monitoring equipment, contact Philips Industries Limited, 69 Clarence Street, Sydney, 2000.

PHILIPS 38.S93Z

Clean Air / July, 1970 Al

Fully automated

Air Pollutants analysis is now a reality. . .

The CSM 6 Air Monitor

The best air pollution surveillance system now on the market is the Technicon CSM 6

Air Monitor. It's actually a small instrument, as compared to the large amount of work

that it does. It measures 48 inches wide, 32 inches deep, and 75 inches high.

What it does

The CSM 6 gives you totally automated and simultaneous measurement of SO2, NO2, NO and NO2, total oxidants, aldehydes, and the

latest parameter to be added, hydrogen sulfide. The recorder on the CSM 6 prints

out a wri t ten record of the air being monitored. All of the data produced by the

CSM 6 can be made available for computer evaluation and statistical analysis.

Air Monitor II A

The Air Monitor II A can be easily programmed by a change of manifold and colorimeter filters to perform either SO2

or NO2 analysis. Further, built-in range expansion permits a selection of sensitivity ranges for SO2 analysis of 0 - 1 ppm, 0-0.5 ppm, and 0 -0 .2 ppm. Parameters such as total oxides of nitrogen, aldehydes, hydrogen sulfide, among many others, are currently under investigation for adaptation to the system.

Technicon Equipment Proprietary Limited 46 LONGUEVILLE ROAD, LANE COVE, N.S.W. 2066, AUSTRALIA

Telephone: Sydney 4281733

A2 Clean Air / July, 1970

HANSSON DUST AND FUME EXTRACTORS

DUST AND FUME COLLECTION Dust and fume is generated in many forms. Some have a nuisance value while others, especially those generated in iron and steel foundries, machine tools, etc., have proved toxic properties. Dust or fume collection presents three main aspects, either collection to regain material lost during process or to remove the harmful products generated during operation, and saves machine tools from damage to bearings and slides, etc.

It has been established with reasonable certainty that silicious dust particles of size-range 0.2 to 5 microns cause respiratory disease when inhaled by power-tool operators. This collection may be made either by general room ventilation or by hoods adjacent to the work bench, or by collection at source.

An interesting note on the efficiency of the first two methods may be made here by comparison of the rate of fall of special particles of different sizes. A particle of 0.5 micron size has a terminal velocity of .001 c.m.s. per second in still air, while a particle of 10 micron size i nc reases the rate to 0.3 c.m.s. per second, and the rate of a 20 micron particle raises to 1.2 c.m.s. per second.

It will thus be seen that the small harmful particles dispersed in the normal air currents encountered in factories or foundries, may well remain in suspension for very long periods. If these particles are collected at source, such a condition cannot occur, and it is now generally accepted by authorities on dust that collection at source is the best method.

SELF-CONTAINED FUME EXTRACTOR

Contaminated air in factories can be troublesome in many ways. It can cause discomfort and loss of efficiency in personnel: it may even be dangerous if the contaminent is toxic. The solution which many people have found is to adopt a policy of partial air re­circulation and heat conservation, incorporating an active carbon filter. This removes all traces of process gases.

Hanssons Self-Contained Dust and Fume Extractor Units contain a gravity settling compartment, filter chamber with flame-proof fabric sleeves or steel wool packet quality sewn filter envelopes.

Air movement is derived from a backward curved blade centrifugal exhauster located on the clean side of the air circuit. Drive is from direct-coupled totally enclosed 2850 r.p.m. electric motor.

Coarser particles are gravity deposited at inlet into a removable tray or hopper, at the underside of the unit into which the finer dust is also rapped, by working the handle at the right side.

The fume extractor contains 22 filter envelopes to remove dust particles, etc., and prevent these from fouling the carbon bed. The gas or fume flows through these 22 flame-proof filter envelopes to the active carbon filter chamber. With a pressure drop of about 12%, the clean air can be let free in the factory. This equipment, a design of Hansson & Co., tends to promote good relationship between employer and employee.

Air movement from 12" Fan. Drive is direct coupled totally enclosed 2850 r.p.m. 3/4 H.P. Electric Motor 440 Volt. 50 Cycle. Fine filtration is accomplished by drawing the dust laden air at low speed, through 22 quality sewn, steel wool packed flame proof filter envelopes.

The total effective filtering area is 36 Sq. Ft. Being self contained the unit is eminently suited to collecting almost any type process dust.

Capacity: 320 Cubic Ft. M.

Dust and Fume Control, Portable Units, from 200 to 3000 cu. ft. per minute.

SUITABLE FOR ANY MACHINE TOOLING

Engineering - Foundry, Plastics, Pigments and almost any type of Process Oust.

HANSSON & CO. 117 BAKERS R O A D , NORTH COBURG, V I C T O R I A

Clean Air / July, 1970 A3

Tilghman Wheelabrator Dust and Fume

Control Equipment engineered for efficiency and

economy

A4 Clean A i r / Ju ly , 1970

Birrus Suction Conveying Systems Eliminate Causes of Air Pollution in Indus t ry

Granular and powdered materials may be conveyed, handled or reclaimed by suction in metal or P.V.C. pipes. The fact that the system is below atmospheric pressure prevents any source of dust. The line diagram shows a typical system; the controls are not shown. Controls may be manual by sight glasses, automatic with level sensing devices or an electronic memory device to fill process hoppers in the order in which they become empty. Valve actuation may be pneumatic, hydraulic or mechanical with servo motor. Such a system may be extended by further inlets on the dust filter and further interceptor hoppers to reclaim valuable or poisonous materials, or to vacuum clean the factory.

• We make systems for conveying foods, plastics, garments, sand, metal swarf, cement, plaster, carbon black, oxides of zinc, lead, etc.

• Similar suction units are used to clean out low pressure dust collector filters.

• Fixed pipe vacuum cleaning systems can overcome pollution and save product.

• We supply road tankers for transport of powders and granules without loss or con­tamination. These are fitted with blowers for unloading.

• Birrus suction systems may be used to separate fines from useable material in foundry sand, blasting shot, etc. • Birrus range of exhauster/blowers are used to fluidize powders in hoppers, air slides or fluidized bed processes, and for passing

gasses through liquids.

For further information or a quotation on a system for your particular needs, contact —

RUSDEN BIRRELL & CO. PTY. LTD.

AIR POLLUTION CONTROL EQUIPMENT THE MIKRO-PULSAIR

a unit for every dust recovery or dust control application . . .

Reverse jet action • No moving parts

There is no dust recovery job too big for the Modular Mikro-Pulsaire because there is no limit to its filtering capacity. Units are designed in precision sections which are combined as required to meet any CFM specification. Knocked-down, they are economical to ship, and all parts are manufactured for simple alignment and speedy assembly at the site. Applicable throughout the processing industries, the Modular Mikro-Pulsaire is designed to vent all types of particle reduction equipment, spray dryers, separators, calciners, mixers, packaging machinery, mechanical conveyors, carloading operations, and many other dust generating sources. The Modular Mikro-Pulsaire is available with 6 or 8 ft . filter tubes and can be equipped with screw conveyor for continuous discharge at one point through a Mikro-Airlock. Available in the smaller round or square standard units.

ALSO AVAILABLE —

MANCUNA VACUUM VALVE —ELECTROSTATIC PRECIPITATORS — GAS SCRUBBERS

Supplied and manufactured under exclusive licence from Pulverizing Machinery, Division of Slick Industrial Company,

Summit, New Jersey, U.S.A., by

INDUSTRIAL ENGINEERING LIMITED CHEMICAL PLANT & ENGINEERING LTD. DIVISION

CONSULTATION

• INSTALLATION

• FABRICATION

• DESIGN

• PILOT TESTING

• COMMISSIONING

THE MODULAR MIKRO-PULSAIRE

Head Office: 97 FRANKLIN ST., MELBOURNE, 3000

Postal Address: G.P.O. Box 1700P, Melbourne, 3000 Telephone: 34-9311 — Telex: IEL AA 30756

New South Wales Office: 288 PARRAMATTA ROAD, AUBURN, N.S.W.

Postal Address: Box 85, P.O., Auburn, N.S.W. Telephone: 648-2144 — Telex: IEL AA 20818

Also represented in WEST AUSTRALIA 9 QUEENSLAND TASMANIA • SOUTH AUSTRALIA

• NEW ZEALAND

Clean Air / July, 1970 A5

"Bring me fire that I may purify the house with sulphur'

Purification—or pollution? "Bring me fire that I may purify the house with sulphur" The quotation comes from Homer's Odyssey, but even today sulphur is still sometimes used for fumigation purposes. Since Homer's day however, many new uses have been found for sulphur and the world requirements amount to some 6 million tons each year.

Much of it is used to make sulphuric acid and unless stringent precautions are taken, the processes involved can add undesirable fumes to an already polluted atmosphere. The application of a simple principle involving static electricity can however help to overcome this problem.

By charging the exhaust gases electrostatically, the pollutant particles can be easily captured in a precipitation unit and returned into the process. This is one of the methods of pollution control used in the ICI sulphuric acid plant at Yarraville in Victoria.

Whilst static electricity can be usefully employed in industry it can also be a potential hazard. Some of its uses and problems are demonstrated in the film "Static Electricity in the Chemical Industry" available from the ICI Film Library in Melbourne.

The Pathfinders

IMPERIAL CHEMICAL INDUSTRIES OF AUSTRALIA & NEW ZEALAND LTD ICI House 1 Nicholson Street Melbourne-Telephone 6620201

ICI,183,A

A6 Clean Air / July, 1970

VOL. 4 / No. 2 / JULY, 1970

EDITOR W. Strauss

ART DIRECTOR Stuart Byfleld

ASSISTANT EDITOR J. R. Alonso

EDITORIAL BOARD W. H. Cock H. Hartmann J. Maher N. Hawthorn

EDITORIAL OFFICE Department of Industrial Science, University of Melbourne, Parkville, V i c , 3052, Australia.

The journal is published quarterly, in March, June, September, and December.

Manuscripts of original papers in the area of Air Pollution, its measurement, effects and control should be sent to the Editor.

Annual Subscription rates ( inc. postage) for non-members and libraries: Australia SA2.50 U.S.A. $US3.50 U.K. £S1.10.0 Elsewhere $A3.50 Single copies 0.75 cents.

Subscriptions and Subscription enquiries should be directed to the Circulation Manager, Mr. W. H. Cock, 151 Northern Road, Heidelberg, V i c , 3081, Australia.

ADVERTISING H. E. Pett & Co., 29 Crossley Street, Melbourne, 3000.

Clean Air is the Journal of the Clean Air Society of Australia and New Zealand.

Page

PRESIDENT'S MESSAGE J.G. Schroder

TECHNICAL PAPERS

The Systems Approach to Air Pollution, Arthur C. Stern (Part 1 )

Olfaction and Air Pollution, Herbert E. Heist, Bruce D. Mulvaney

Introduction of Natural Gas in Victoria, H.F. Hartmann

FEATURES

26

27

34

38

Meetings of the Branches: New Zealand New South Wales Victoria

Forthcoming Conferences: Fourth Australian Ceramic Conference The Way to Air Pollution Control

Book Review: Air Pollution Engineering

26 42 42

37 37

42

Clean Air / July, 1970 25

PRESIDENT'S MESSAGE The Population — Pollution Syndrome

Man, by harnessing natural energy sources, has created a situation where he is on a collision course with his environment, unless he becomes a more skillful navigator than he has been in the past. Our population ex­plosion is coupled with man's insati­able appetite for energy. This results in the conversion of millions of acres each year from parkland to asphalt as well as the moving of mountains, creating lakes and altering the flow of rivers.

This requires the muscle provided by the combustion of fossilized fuels which discharge their pollutants to the atmosphere. While Thomas Mal-thus in 1798 correctly predicted our current population dilemma he did not envisage our enormous conversion of hydrocarbons into energy and car­bon dioxide, which by the year 2000 is estimated as being at 250 times the 1900 rate.

The trend in Australian urban con­ditions is towards more pollution, and if there is no change in philosophy we will find ourselves in a position where

MEETINGS OF THE BRANCHES New Zealand Branch

The first Annual General Meeting was held at Caltex House, Fanshawe St., Auckland, on Wednesday, 25th February 1970, at 7.45 p.m. There was an attendance of some 80 members from Auckland and Wellington, and we were very pleased to welcome Dr. W. Strauss from the Victorian Branch who was later to address members and the fifty visitors present.

Officers elected for the year end­ing December 31, 1970 were as follows:

President: Mr. J. E. Fitzgerald, Borough Engineer, Mt. Wellington Borough Council, Auckland.

Vice-President: Mr. D. M. Walter, Chief Chemist, Caltex Oil N.Z. Ltd., Wellington.

Secretary-Treasurer: Mr. A. W. Skam, Executive Officer, Auckland In­dustrial Development Division, De­partment of Scientific & Industrial Research, Auckland.

Committee Members: Mr. L. E. Buckley, Manager, Furnace and Re-factories Contract Division, Lynn Pot­teries Ltd., Auckland. Mr. E. L. G. Clist, Chief City Inspector, City of Manukau, Auckland. Dr. J. F. de Lisle, Assistant Director (Research), N.Z., Meteorological Service, Wellington.

it becomes extremely expensive to turn the clock back and reverse this trend.

However, that this is not impos­sible can be demonstrated by the fact that in the last 15 years the dust fall out in Sydney has dropped from 25 tons per square mile per month to under 15 tons per square mile per month. To a large extent this trend can be attributed to the reduction in the quantity of coal burnt in the city's power stations — from 42,000 tons/ week in 1956 to 7000 tons/week in June 1969 — as well as the addition of precipitators to boilers.

A disturbing trend is the increase of sulphur dioxide in Sydney's indust­rial and commercial suburbs as shown in recently released statistics by the N.S.W. Department of Health. Since 1965 the measured annual average has more than doubled. This increase is coincident with the consumption of indigenous crude oil in Australia. While Australian crude oil, being a light crude, is very suitable for petrol­eum production, there are insufficient heavy ends to produce furnace oils. This shortage is being replaced from Middle East crudes which contain over 3% sulphur whereas Australian and Indonesian crude oils contain much less than 1% sulphur.

Countries such as Japan and the

Mr. R. T. Douglas, Chief Chemical In­spector, Department of Health, Well­ington. Mr. H. E. Evans, District Elec­trical Engineer, N.Z. Electricity De­partment, Auckland. Mr. D. J. Higgins, Works Superintendent, Fertiliser Divi­sion, Kempthorne Prosser & Co. Ltd., Christchurch. Dr. J. Rogers, Director, N.Z. Fertiliser Manufacturers' Re­search Association (Inc.), Auckland. Mr. N. G. Thorn, Chemical Inspector, Department of Health, Auckland.

There was some discussion on the types and frequency of the program­me for the year and it was suggested that one of these could be held in some other centre, say Wellington, perhaps in collaboration with one or more other technical group such as the Royal Society of N.Z., Technology Section, and the Institute of Fuel (N.Z. Group). Dr. Strauss commented on the frequency and types of pro­grammes arranged in Victoria, and after some discussion, the Chairman said that all of the helpful comments made would be considered by the Committee when planning the year's activities.

At the conclusion of the formal business, Dr. W. Strauss of the Indust­rial Science Department, University of Melbourne, gave an address on "Air Pollution and the Environment." He emphasised that pollution, and in par­ticular, air pollution, is the most

U.S.A. are legislating to reduce the sulphur content of furnace oils and one wonders whether by not legislat­ing similarly against high sulphur oils Australia will become a dumping ground for sour residuals. It is pos­sible to remove the sulphur from crude oil (and residual fractions) but this increases costs. We should ask ourselves whether we are prepared to put up with the increase in the sul­phur dioxide content of our urban at­mosphere or whether we are prepared to pay the cost of removal of this. The longer we defer action the more costly will become the cure.

The main danger to Australian cities is complacency. We are inclin­ed to regard levels of pollution that have occurred overseas as not being possible here. But if something is not done to reverse the present trends, we will find ourselves in a similar situ­ation to cities in Europe and America. It becomes extremely expensive to turn the clock back.

The Clean Air Society of Australia and New Zealand believes that the time for action is now. We believe now is the time for the oil industry, the electricity industry, the motor indust­ry and our political leaders to follow the leads set by countries who have experienced the plague of pollution.

J. G. SCHRODER

serious problem facing civilized man. It is a result of the increasing demand for the amenities of our urban envir­onment and the good things in life.

The reduction of air pollution to acceptable levels requires that every source has to be controlled. Thus motor car exhausts, industrial waste gases and domestic air pollution will have to be minimised. This will re­quire decisions of social as well as en­vironmental consequences. We may have to reduce our demand, and in­crease costs to achieve a worthwhile environment.

The control of pollution from a major source — the generation of electricity from oil — was discussed in detail. The problems involve site selection, the development of suitable processes for preventing pollution, particularly sulphur dioxide, and the possibility of alternative advanced power systems such as the high tem­perature fuel cell.

At the conclusion of his address, Dr Strauss answered several questions from members after which a vote of thanks to the speaker was carried with acclamation.

Supper, generously provided by the management of Caltex Oil N.Z. Ltd., concluded a most interesting and in­formative programme.

(Continued on page 42)

26 Clean Air / July, 1970

Arthur C. Stern THE SYSTEMS APPROACH TO ASR POLLUTION CONTROL (PART 1)

Professor Stern is Professor of Air Hygiene, Department of Environmental Sources and Engineering, School of Public Health, University of North Carolina, Chapel Hill, N.C., 27514, U.SA

This paper was presented at the Sydney Clean Air Conference, May, 1969.

Introduction: The systems approach means the application of the prin­ciples of systems analysis, systems engineering or operations research to the problem at hand. Although there are shades of difference implicit in these three disciplines, they so over­lap and the techniques employed are so similar that, from our point of view, they are but different names for the same thing, thing.

The classical systems approach to a problem (1) is to first structure the real situation into a model; then give the model a graphic or mathematical form; effect a graphical or mathe­matical solution that optimizes the value or values used as measures of success; test the validity of the sol­ution; and, finally, apply the solution to the problem.

The starting point for the systems approach is the formulation of the problem to be studied and solved. If the problem is incorrectly or incom­pletely stated, the solution obtained will be the right solution for the wrong problem, and its application may cause more harm than good.

Modelling Block diagrams and linear program­ming are the common tools of the systems analyst. However he does not give them sole reliance. The better the systems analyst, the more likely he is to by-pass these proced­ures when other descriptive, statis­tical, logical or intuitive approaches are more likely to best explore and explain a system.

In the block diagram (2) (Figure 1) each element of the system occurs within its own black box - a block definable by how it operates on its in­put to create its output. The system input variables are represented by the lines connecting the blocks. Setting up mathematical expressions for which the optimum value is to be found when there are constraints on the values that may be assigned the variables is known as linear program­ming. Finding the optimum value re­quires special mathematical methods

specifically devised for this purposed). In problems of this type, there is fre­quently insufficient information of a precise nature, so that the problem solver must resort to probability the­ory to supply missing ingredients. The search procedure for mathematically finding the highest value of a three-dimensional response surface without having a complete mathematical ex­pression for the surface, has been lik­ened to the task of a blind-folded man rinding his way to the highest peak in a range of mountains.

People first exposed to these tech­niques, and even some of those steep­ed in its technology, tend to be so impressed with what the computer can do that they lose sight of what can be done at less overall time and cost without a computer. In fact, many of the simpler problems can be solved for an optimal solution by paper and pencil.

However as soon as it is desired to do what is known as manipulate or exercise a model to see the effect of a variety of input changes, and changes in the model itself, only a large computer can cope with the size and complexity of the computational load.

One form of exercising a model is what is called gaming, (4) which is characterized by there being opposing forces, each attempting to maximize their position — when, in the con­text of the air pollution situation, polluters and receptors are in conflict. It is but a step from this to the form­ulation of elements of models to bridge the gaps where the real world does not provide useable elements. This practice is known as simulation (4-5).

The Air Pollution System The basic model of the air pollution system has increasingly been structur­ed in more and more complex graphic form (Figure 2), but has only recently been subjected to the introduction of appropriate mathematical algorithms and attempts at their solution. The system must be in the broadest con­text compatable with the scale under

Clean Air / July, 1970 27

study. By the scale of the system is meant the universe for which an opt­imal solution is sought. That universe may be a process, a plant, a corpor­ation or an industry; a region, a city, a state, a country, a continent or the world. The larger the universe, the more complex the system and the less likely the development of a workable model.

The Global System

The most comprehensive air pollution system that can be analyzed is the global system which looks at all global sources and sinks, and, in the course of so doing, develops a global bal­ance for each pollutant to determine whether sources and sinks are or are not in balance. If they are not in balance we need to know whether sources exceed sinks and, whether, as a result, the background level of the pollutant in the world's atmosphere is increasing, and at what rate. Nei-berger(6) has postulated what could occur if this is so (Figure 3). If they are in balance, or if sinks exceed sour­ces, we need to know the effective half-life of the pollutants. A tentative global balance sheet for the principal pollutants (Table 1)(7) shows many gap areas where firm knowledge of the fate of pollutants is lacking. The com­plete system should provide not only this analysis but also show what in­dividual nations must do to correct this inbalance and prevent global eco­logical and climatological disaster. The United Nations in late 1968 pass­ed a resolution calling for an inter­national conference in 1972 on this and related subjects.

Moroz(8) has pointed out that for the pollution transport and diffusion sub-model the decision as to horiz­ontal scale inherently establishes the vertical scale of the model, and that the smaller the horizontal scale, the smaller the vertical scale that can be treated in the analysis. In the global scale we are therefore dealing with the entire atmosphere associated peculiarly with the earth.

Since systems are analyzed to aid and improve decision making the time scale on which decisions can effec­tively be implemented should deter­mine that inherent in the analysis. The global system, is implemented by the actions of nations. Since the time scale of international action is meas­ured in decades, analysis should look at the system in this scale of time. The best example of the global system of air pollution is the world wide dis­semination of radio-active debris from the testing of nuclear weapons in the atmosphere. As is well known, the procedure adopted internationally for the control of this hazard has been the underground testing of weapons.

Continental and National Systems You in Australia are in the uniquqe position that, as a nation, you decide the fate of a continent and can study air pollution as a system on a con­tinental basis. It is not too important for the three countries of North America to analyze their problem on a continental scale because the prin­cipal air flow is west to east, largely confining the pollution produced in each country to other regions of the same country. The international in­terchanges of pollution in North America have local rather than con­tinental implications. Transport of pollution across the Canada-United States border has for some years been under study and, to a limited extent, has been subjected to regulation by the International Joint Commission (U.S. — Canada).

In Europe the principal air flow cannot fail to transport pollution from country to country and create a prob­lem of continental scale. In February

1969 the Economic Commission for Europe held a meeting in Geneva to assess this problem for their contin­ent.

All of the developed nations of the world have some agency charged with looking at pollution as a system on a national basis. In the United States a contract has recently been negotiat­ed between the federal government and Thompson-Ramo-Wooldridge Inc. (TRW) to apply systems analysis to the national problem in its broadest context(9).

The time scale of national imple­mentation and hence of systems re­levant to it is in years. The vertical scale for the United States and Aust­ralia certainly includes the stratos­phere. The vertical scale for some of the smaller nations of the world may well be restricted by the horizontal dimensions of the country.

State-wide Systems I hope while I am in Australia to

28 Clean Air / July, 1970

learn the extent that you are apply­ing these analytical tools on a State­wide scale. In the United States, most of our States are assembling the kinds of data that would form input for systems analyses, but have yet to make such application in a structured analytical model. One state that has done so is Connecticut, a relatively small state on the Atlantic Coast in the north-eastern portion of our country. The Connecticut Research, Commission, with federal financial assistance granted funds to the Travellers Research Centre for the development of a simulation model of air pollution over Connecticut. The model for the physical aspects of the problem was completed in 1967(10). Some results are shown in Figure 4. The report of the project concludes: "The social and economic consequen­ces of air pollution and of measures to control air pollution are also part of the total air pollution problem. Ex­tension of these studies into these realms is a logical and necessary step along the way to a complete and fully operational air pollution information system." In 1968 additional funds were awarded for verification, refine­ment and reprogramming this model for greater computer efficiency. A pre­liminary report of this work is sched­uled for presentation at the Air Poll-

Clean Air / July, 1970 29

ution Control Association meeting in New York next month.

Regional Systems

It is on the regional basis that air pollution systems analysis is presently most active, although here too, most attention is being paid to the phy­sical, rather than the economic and social aspects of the model.

The time scales of State and re­gional implementation are somewhat interchangeable, but normally we would expect State implementation to be on a scale of days; and regional response time to be measured in hours. Smaller systems with the ability to use short time scales have the oppor­tunity to also analyze their systems in longer time scales than their in­herent minimum, to determine not only the present but also the future consequences of present actions. The lower the jurisdictional position in the heirarchy, the more time scales may be required of its systems analysis.

The shortest time scale, that of hours, is that associated with the air pollution epidose or emergency situ­ation of a city or region; and with the utilization of alerts or forecasts of impending high air pollution potential. The kinds of decisions that must be made under these circum­stances have immediate impact on the social and economic behaviour of a population, by possibly suddenly re­stricting their transportation, employ­ment and domestic activities. We are looking to systems analysis to help show us how to prevent an air poll­ution disaster with the least social and economic disruption.

The horizontal scale of the city or regional system is sufficiently small that the vertical scale is effectively restricted to the lowest mile of air above the earth.

Strategic and Tactical Systems

One may characterize the actions that must be taken on the longer time scales as "strategic"; short time scale decisions as "tactical"; and give similar names to the systems analyses associated with them. Tactical deci­sions made to avert an episode mainly affect the short term economic and social behaviour of the city involved, but have very little lasting impact on other jurisdictions largely because the city reverts to the status quo ante after the emergency situation has passed. The same is not true of strat­egic decisions made to shape a long-term trend of pollution levels and effects in a community. In this case, local decisions may have long-term economic and social impact not only on the community itself but also on the rest of the world with which it has economic and social interaction.

As previously noted, in the United States, the federal government has

30 Clean A i r / July, 1970

contracted with TRW to undertake a strategic systems analysis for the nation. However, this company has also been charged with the develop­ment of a tactical model for use at the local level and is expending most of its effort on this, rather than on the strategic model. In its prelimin­ary analysis of the task(9) (Figure 5), TRW has noted that the distinctions between strategic and tactical analy­sis, and between regional and national analyses, are not sharp. They point out that there are national tactics as well as strategies, just, as previously noted, there are regional strategies as well as tactics; and that there are inter-regional tactics as well as multi-regional strategies. They have broken the regional analysis into two ele­ments (Figure 6) — a regional scena­rio, which is a compendium of region­al characteristics describing all relev­ant information elements of the sys­tem required by the decision elements of the regional and State air pollution control agencies; and a regional model which constitutes those por­tions of the regional scenario which can be expressed mathematically and therefore programmed for computer application.

Some of our largest cities, most notably Chicago (11) have idependently started the development of models applicable to their tactical and strat­egic problems. Such studies are be­coming quite popular as research pro­jects in university departments con­cerned with air pollution, city and regional planning, and economics. In fact, we at the University of North Carolina have interests along these lines.

Transport and Diffusion Sub-System(12)

Complex models are made up of sub­

systems which can themselves be modeled and studied. In air poll­ution systems, the most important sub-model is the transport and diffu­sion model. The simplest diffusion model is that of sources under stag­nant weather conditions, i.e. no lat­eral wind movement and a meteoro­logical ceiling that effectively pre­vents vertical transfer of pollution. This is the familiar box model (Fig­ure 7) in which pollution continues to pour at a fixed rate into a fixed volume of air with the resultant con­tinual and computable increase in average pollution concentration in the box. In this model the lateral dimen­sions of the box are those of the community.

The first extension of this model is to consider its behaviour when the ceiling persists but there is lateral wind movement. This is the ventilated box model (Figure 8) which allows estimation of concentration of poll­ution in the air leaving the box through its down wind side when air from the adjacent area enters its up wind side. This entering air cannot be considered free of pollution since there is a background concentration of all important pollutants in non-urban air, which must be added to any computed urban concentration.

Grid Models The next extension of the model is to relieve it of its vertical ceiling con­straint by treating area sources as if they were line sources; and, by further extension as single sources, located in the centre of the area, the plume from each diffusing according to the accepted theories of line source or single stack plume diffusion. Treating the area as a point source offers great computational advant­ages since a point source looks the

same to winds of all directions. Since area sources consist mainly of large areas of buildings of approximately the same height, and of automobiles operating at street level they may be classified into a very few categories of mean effective emission release height.

For computational purposes, it is convenient to impose a square grid pattern on the community, so that the community becomes a set of rel­atively small squares each transmit­ting pollution to its neighboring squares and those beyond (13). In real models there are high emission rate single sources such as fossil fuel fired power plants, and industrial sources, that must be introduced into the model as they actually exist; and super-highways that have to be in­troduced as line sources.

To add the final touch of reality to this model, and to avoid the un­realistic situation of the upwind por­tions of each square being unpolluted by the pollution arising from within the square, the pollution is assumed to diffuse laterally from a virtual source upwind of the effective single source(14) (Figure 9). The distance of this virtual source to the centre of the square needs to be added to the distance from the centre of the square to any downward location at which pollution concentration is to be com­puted. This is not a fixed distance, since it depends upon the turbulent characteristics of the atmosphere at the time of computation. Since the downwind concentration of pollution in the diffusing stream also depends upon turbulence, it becomes necessary to build into the computational pro­cess the relationships between atmos­pheric stability, downwind distance and the lateral and vertical diffusional parameters.

The pollution in any square at a specific time is the computed sum of the pollution being transmitted to it at that time from each upwind square, including those not in the direct line of wind direction. However, for simul­taneous arrival of pollution at a receptor square from a number of emitting squares, the time of emission release would be different for each emitting square depending upon trans­port time between them, which is a function of wind velocity and distance between the squares. The longer the transport time, the more unrealistic the assumption of uniform wind direc­tion, velocity, and turbulence and of conservation of the mass of the poll­utant during transit. Almost imme­diately after its emission, the mass of the pollutant may start decreasing because of reaction with gases, aero­sols and the terrain. When this occurs, a decay rate needs to be intro­duced into the computation.

A model can be set to provide time integration and averaging of the poll-

Clean Air / July, 1970 31

ution received by any one square over succeeding time periods. It can also use as wind direction, velocity and turbulence, average values for the time period of the computation, be it a year, a month, a day or an hour. We can thus introduce into the com­putation, our climatological knowl­edge of the expected frequency dis­tribution of these variables over various time periods.

Advanced Meteorological Models To properly test the validity of a model, by challenging it with real retrospective data, would require that it be capable of handling observed variations in meteorological and source factors as part of its input. This requires that the model have built into it what is, in effect, a com­putational clock to keep track of the time of arrival of air parcels at the locations at which changes in wind direction, velocity and turbulence occur. This takes us into the sophis­tication of trajectory analysis.

Moroz(8) states that "meso-scale meteorological and air pollution models are sufficiently advanced in­dependently to permit the develop­ment of an overall combined model in the not-too-distant future. Such a model could apply the predicted wind and temperature structure (which will vary in space and time) from the meteorological section of the model to forecast the dispersion and trans­port of pollutants on the basis of vary­ing meteorological parameters. This type of forecase would be of particular value in the more heavily industrializ­ed areas near large bodies of water which give rise to organized local circulation patterns."

The Los Angeles model proposed by Ulbrich(15) (Figure 10) recognizes that there are air-flow reversals asso­ciated with the land-sea breeze regime; channelling through valleys in the mountains on the landward side of Los Angeles; and an inter­change between an upper and a lower airflow. His model is designed to be run on a hybrid analogdigital com­puter.

Statistical Models Once we introduce the frequency dis­tribution of measured values of wea­ther, and further add, the frequency distribution of source strength and character, we are getting further and further away from the elementary physical model with which we started, and are approaching, instead, an essentially statistical model that makes no attempt to trace pollutants from source to receptor as discrete trajectories. The basic premise of our most sophisticated statistical model, the Chicago Air Pollution System Model(11) for sulfur dioxide, being developed by Argonne National Lab-

32 Clean Air / July, 1970

oratory, is that a linear regression equation (Figure 11) in the form:

can be found which will allow pre­diction of X, the average concent­ration of SO2 at the receptor during time period n. C is the SO2 back­ground concentration for averaging time n; T is temperature; C1 and C2 are temperature dependent co-effi­cients or functions; P1 and P2 are heating or fuel pattern co-efficients or functions; Q is the average emmis-sion from a point source over time period n; K is the coupling co-effi­cient between the sources and the receptor for a specific meteorological regime; subscripts 1 and 2 represent different area source categories; and subscript i identifies point sources. For example, subscript 1 could be for dom­estic sources; subscript 2 for large apartments and commercial build­ings; and subscript i for a utility power plant. C, P and K are to be derived by statistical regression, dis­criminate, or factorial analysis of data obtained during a carefully defined meteorological regime, i.e. a specific stability condition, wind direction and wind velocity range.

The Argonne group has had the co-operation of Chicago's electric utility company, the Commonwealth Edison Company (CECO), which is the principal SO. emitter in Chicago. To­gether, they have developed a model to determine the extent that air poll­ution incidents, i.e. adverse combin­ations of SO2 concentration and duration, can be averted by reducing CECO emissions. The model (Figure 12) also seeks the least cost combin­ation of fuel switching, load shifting and power purchase to accomplish these reductions. The coupling co-effi­cients between CECO power plants and the Chicago Department of Air Pollution Control air quality monitor­ing stations, which are the receptors are computed using a physical rather than a statistical model.

Clean Air / July, 1970

(This paper to be continued in the next edition.)

33

Herbert E Heist OLFACTION AND AIR Bruce D. Mulvaney POLLUTION

The authors are members of the Life Sciences Group at the Honeywell Corporate Research Centre, 500 Washington Avenue South, Hopkins, Minnesota, U.S.A., 55343.

Odor sensing cells are delicate, specialized nerve cells which have received little attention from sensory scientists. The ever increasing problems of air pollution focus new interest on our dependence upon this vital sense organ.

Introduction: For over 100 years scientists have been attempting to get an insight into man's least understood sense — the sense of smell. Until the last decade or two, the emphasis on the importance of these particular scientific endeavours has been severely lacking. Through the process of evol­ution the components for the physio­logical function of odour perception seemingly have been pushed away from the direct line of fire. This move to a back seat, so to speak, has been considered by many to be an indic­ation of secondary importance for this sense when compared to our greater dependency upon vision, hearing and touch. Now, however, in this frenzied era of air pollution perils, we tend to give credit to Mother Nature for hav­ing sufficient foresight to locate the fragile tissues of this keen sense in a somewhat protected area. Most of us have never been too aware of the over­all benefits of our olfactory acuities but a few words from those who have suffered temporary or total loss of this sense can give us considerable en­lightenment.

Our perception of odours is per­formed by very delicate and sensitive specialized nerve cells. This article will discuss briefly (1) the structure of these cells and the nature of their im­mediate environment, (2) the research approaches being taken to determine the basic functional mechanisms of olfaction process with possible medi­cal and economic implications.

Olfactory Tissue: The olfactory tissue is located to­ward the roof and back of the nasal passage in mammals, including man. In this position it is not in the direct path of the air that is drawn in through the nose to the lungs. The odour molecules in the air are taken more or less indirectly to the olfactory cells via eddy currents. Because of this, we sniff when we wish to detect an odour more acutely. Sniffing serves to increase both the amount and the rate of odour molecules entering the sensory area. Although this cellular location is not particularly beneficial

as an odour detector, it does serve somewhat to protect against possible injury from air pollutants. All of the remaining surface area in the nasal passages is covered with respiratory epithelium consisting of ciliated col­umnar cells. The exposed surface of these cells is covered with hundreds of hair-like structures called cilia. These cilia continuously move or beat in an orderly manner and they, to­gether with the mucus that bathes them, serve to filter out most of the particulate pollutants that are inhal­ed. It is these cilia and others like them on cells in the bronchial tubes that are temporarily inactivated by tobacco smoke(1).

To understand a physiological function such as olfaction, it is essential to learn about its most basic unit, the bipolar sensing cell. Our initial approach to this study was to use the light microscope to completely map the location of ol­factory cells on the complex sensory structures(2). New Zealand white rab­bits were used for all of the studies discussed in this article. Gross anat­omical differences exist in olfactory tissues among various species, but the odour sensing cells themselves are re­markably similar throughout the an­imal kingdom(3). Thus information gained from investigating the cells in rabbits is considered applicable in un­derstanding those in man. Using the mapping study to accurately guide our selection of olfactory tissue sections, the next step was to use the electron microscope to determine the cell's ul-trastructure. Figure 1 is a drawing of the 3 types of cells that are found in olfactory epithelium. The bipolar sen­sing cell is a specialized nerve cell; consequently, it is assumed to do the sensing and is so named. The susten-tacular cell is also called the support­ing cell in the assumption that it physically assists the bipolar in main­taining position. Its actual function and relation to the bipolar cell in mammals is still not fully understood.

Figure 2 is a more detailed drawing of the bipolar cell. (These drawings are based on our electron photomicro-

34 Clean Air / July, 1970

graphs as seen in Figure 3.) Because of this sensing cell's unusual morph­ology, some of its dimensions should be noted. The overall length of the cell is variable between 60 micron and 100 micron. The diameter of the cell body is between 5 micron and 10 mic­ron and that of the terminal swelling is 2 micron. The cilia, approximately 30 to 50 per cell, and the axon have the same diameter, 0.5 micron.

The distal location of the protrud­ing cilia suggests that they would make first contact with the odour molecules. Consequently, some in­vestigators believe that the odour de­tection sites are located on the mem­brane surrounding the cilia. This important function of the cilia has yet to be demonstrated. In some species, but certainly not all, the cilia are motile (4) and thus probably function in much the same way as the respir­atory cell cilia, i.e., to move the mucus.

The area of the cell to which most of our research attention has been directed is the terminal swelling. The cell membrane around the terminal swelling is what we consider as the functional area of contact between the sensing cell and the odour mole­cules. Figure 4 is an electron photo­micrograph of the terminal swelling and some of its cilia. The terminal swelling extends beyond the tissue sur­face level into the mucus which over­lays the cells. Here it can be in direct contact with the odour molecules that enter the mucus.

The sustentacular cell is much larger in volume than the bipolar cell and is covered by hundreds of finger-like projections called microvilli on its exposed surface. These microvilli offer extensive surface area suggestive of an absorptive function. In some animals, however, particularly amphi­bians, mucus is secreted by these cells (5). In many mammalian species the mucus is produced by the Bow­man's glands peculiar to the under­lying lamina propria of olfactory epithelium (6).

Research Approaches:

In reviewing the literature on olfac­tory research in which the sensing cells are physically involved, it is ap­parent that recording electrical or nerve impulses is probably the oldest and most persistently used approach. Such recordings have been made from rather indefinite areas of olfactory tissue, from a number of bipolar cell axons, and from cell layers in the ol­factory bulb of the brain. The in­formation obtained from these electro­physiological measurements has been extremely valuable, but no single ap­proach can explain all the functional aspects of such a complex system. Although electrical recordings from groups of cells continue to be made by

olfactory researchers, the interpret­ations are still arbitrary. More mean­ingful recordings might be those ob­tained from single sensing cells, but the small size of the cell makes this type of measurement very difficult.

The electron microscope has aided us in opening new avenues of re­search. For example, we are now trac­ing odour molecules that have been tagged with carbon-14 in attempting to pinpoint the exact location of odour detection on the sensing cell. Prelim­inary findings with light and electron microscope radio-autography indicate that some of the molecules actually enter into the cells of the sensory epithelium. This had been proposed at one time (7), but has never had sup­portive evidence. We are not suggest­ing that entrance to the cell is a pre­requisite to odour sensing but merely that it does occur as one step in the overall process of olfaction.

Biochemical research in our lab-

oratory has also been related to the outer membrane of the terminal swell­ing. In one approach the mucus over­laying the cells and in contact with the outer membranes is being ana­lyzed. A water-soluble component (probably a protein) isolated from the mucosa shows a change in macro-molecular conformation after being stimulated by a particular odour (8). The conformational change is monit­ored by ultraviolet difference spectro­scopy. Further work in this area has shown that ascorbic acid is a neces­sary cofactor in this reaction affect­ing the degree of conformational change (9). The results from these studies cause us to conjecture that this type of reaction may be an initial transduction step in the olfaction sen­sing process.

Another biochemical approach in­volves literally taking the cells apart. By using density gradients and differ­ential centrifugation, we are able to

Clean Air / July, 1970 35

isolate and analyze almost any kind of subcellular component regardless of size; this includes membranes such as those of the terminal swell­ings. One of our biochemists is study­ing certain enzymes associated with these membranes. He has found that one particular enzyme of the olfactory cell membrane reacts differently from the same enzyme of a brain nerve cell (10). He has also demonstrated for the first time that chlorinated hydro­carbon pesticides in living systems in­hibit the energy-releasing ATPase en­zymes at the cellular level(11). These findings could be vital in understand­ing the true functional mechanism of the odour sensing cell. Investigations such as these in olfaction research are relatively new, but more scientists are and will be using these approaches in directing their studies on odour perception. The ultimate and com­plete understanding of the sense of smell will be the cumulative result of many types of research including psy-chophysiology (odour panels) and the organic chemistry of odour molecules, neither of which are included in this article.

Air Pollutants and the Olfactory Process: The immediate problem concerning us at this time is the relation be­tween air pollution and odour percep­tion. Fortunately our odour sensing cells do not appear in serious danger of being injured by the major air pollutants; however, this is not a cer­tainty at present. Much has been writ­ten and stated about effects of pollut­ants to our overall health. Certain compounds cause eye irritations, some cause various degrees of coughing, others antagonize emphysematous conditions, etc. Little is actually known, though, about the pollutant effects at the cellular level such as the chemical reaction of polluting compounds with the cells of the bron­chial tubes and lungs. Even less is known about the effects on olfactory cells, since little specific research has been conducted on them.

Through part of our research pro­gram, we have gained some insight into the problem and a degree of en­couragement as relates to air pollut­ants. While making detailed observ­ations on odour sensing cells in adult animal tissues, we noticed unusual locations of a certain organelle, the centriole. In addition to their function in cell division, centrioles, in cells con­taining cilia, reduplicate and form basal bodies from which the cilia de­velop. In the fully mature cell the centrioles would be expected to be found only in that location. However, we observed significant numbers of bipolar cells with centrioles in other locations(12). This suggested to us that perhaps we were observing developing

cells. Further, it suggested that, un­like most nerve cells, these cells might have regenerative capability. Using previously established techniques (13), we preferentially destroyed olfactory epithelium by treatment with a 1% zinc sulphate solution. A regeneration process began almost immediately and a nearly complete new olfactory tissue layer was formed in one month. Although destruction of these cells was not produced by air pollutants, presumedly this tissue would regen­erate just as well after possible in­jury by such pollutants. The amount of injury, if any, to olfactory cells would depend upon the concentration of the pollutant and the exposure time. Until such studies are made, we have no way of measuring the detrim­ental effects.

A complicating factor in this odour-air pollution matter is the in­dividual human variance to odours. Likewise, a single odour can vary ac­cording to its concentrations. Many chemicals have an unpleasant odour when concentrated, but become more pleasant in dilution. The character­istic strong skunk smell is an ex­ample. When very diluted it smells somewhat like musk which is a basic ingredient for many perfumes and soaps.

Much has been written about the factors that influence humans' odour likes and dislikes including the effects of sex, age and temperament(14). Preg­nancy is also known to change the sense of smell and certain substances (caffeine) reportedly enhance odour sensitivity whereas others (acetylcho­line) suppress it. There are a number of abnormal conditions of olfaction which may be due to genetics, disease, injury or even emotional upsets. The effects from these conditions vary in that some individuals perceive an odour completely differently from "normal" persons; some detect an odour when there is no odour stim­ulus; some lose perception of only cert­ain odours; some continually perceive unpleasant odours; some have a tem­porary or permanent complete loss of odour perception; etc. That air pollut­ants may cause any of these anom­alies is unknown. It would not be sur­prising, though, to find that such a sensitive and delicate system as ol­faction is affected by certain pollut­ants.

From an economic or psychological standpoint, the nuisance value of odourous pollutants is currently of more importance than the threat to the well-being of our olfactory cells. A strong unpleasant odour in this day of air pollution concern can cause in­tense reaction by the public to the source of the odour. Regardless of actual cellular injury by the pollut­ant, a general ill-feeling such as nausea can be induced by the asso­

ciated odour. Although odours may serve as warning signals in some in­stances, odour abatement is neces­sarily involved with air pollution problems.

It is readily recognizable that the field of odour control is highly com­plicated. Public demand is making the control, or at least the masking, of odours absolutely essential. This should become an easier task when we hope, some day, completely to un­derstand the mechanism of olfaction.

Summary: Rabit olfactory tissue, particularly the bipolar sensing cell, has been an­alyzed fairly extensively. Cell ultra-structure was determined by electron microscopy. The terminal swelling and cilia are of considerable interest be­cause of their exposed position and presumed initial contact with odour molecules. Exact odour detection sites have not been determined, but pre­liminary radioautographic findings in­dicate entrance of some of the mole­cules into the cells.

Biochemical investigations have is­olated a water-soluble component from, the olfactory mucosa which undergoes a conformational change when stim­ulated by certain odourants in the presence of an ascorbic acid cofactor. Other studies have determined the activity of certain ATPase enzymes associated with the outer membrane of the terminal swelling. The activity in one instance is different from that of the same enzyme isolated from a similar section of brain nerve cells.

Following destruction of the olfac­tory tissue by a 1% zinc sulphate solu­tion, almost complete regeneration of the epithelium occurred within one month. This is encouraging in the light of possible cell injury by air poll­utants. We doubt very much that in­jury by pollution would ever be as severe as that caused experimentally by zinc sulphate. Public reaction to the odour-air pollution problems will un­doubtedly be more concerned with the nuisance and psychological aspects than with actual effects on the odour sensing cells at this time.

Acknowledgements: This article is partially a result of several years of research because of Honeywell's interest in the field of air pollution. The research was conducted at the Honeywell Corporate Research Centre by scientists in the Life Scien­ces Group of the Chemistry Depart­ment. Dr. Herbert E. Heist is a Staff Scientist and Mr. Bruce D. Mulvaney is an associate Research Scientist in this group. The initial studies were conducted to get a better understand­ing of the functional mechanism of the sense of olfaction. Information re­sulting from these investigations were

36 Clean Air / July, 1970

FORTHCOMING CONFERENCES

Fourth Australian Ceramic Confer­ence, held in conjunction with the Fifth Australian Clay Minerals Con­ferences.

This conference, which will in­clude a "Natural Gas Symposium," will be held at Monash University, Clayton, August 18-20, 1970.

Enquires should be directed to Mr. R. R. Hughan, CSIRO Division of Aplied Mineralogy, Box 4331, Mel­bourne, Victoria, 3001.

A one-day Symposium "The Way to Air Pollution Control" will be held on 16th September 1970. This sym­posium is being organized by the New South Wales Branch of the Clean Air Society and is sponsored by the Air Pollution Control Branch of the N.S.W. Department of Health.

The lectures will deal with com­bustion and pollution control techno­logy. Members of the Clean Air Society will be admitted free. Visitors will be charged $5.

Enquiries regarding the Sympo­sium should be directed to the Organ­ising Secretary, Mr. S. Stanley, P.O. Box 163, Lidcombe, N.S.W., 2141.

Announcing . . .

An important new international journal concerned principally with the biological and ecological effects of all types of environmental pollution and pollution control.

ENVIRONMENTAL POLLUTION

AN INTERNATION JOURNAL

Edited by KENNETH MELLANBY, Monks Wood Experimental Station, Abbots Ripton, Huntingdonshire, England

Associate Editors:

Dr. M. Buck (Germany) Prof. B. Commoner (USA) Prof. R. W. Edwards (Wales) Prof. W. A. Feder (USA) Mr. G. T. Goodman (Wales) Dr. Michio Hashimoto (Japan) Prof. H. B. N. Haynes (Canada)

Dr. P. Lindop (England) Dr. B. Lundholm (Sweden) Prof. N. Polunin (Switzerland)

Dr. M. Ruzicka (Czechoslovakia) Dr. P. J. W. Saunders (England) Dr. J. E. Smith (England) Dr. W. Strauss (Australia)

Dr. Michail Telitchenko (USSR)

PUBLISHED QUARTERLY — FIRST ISSUE JULY 1970

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Clean Air / July, 1970 37

H F Hartmann INTRODUCTION OF NATURAL GAS IN VICTORIA

Mr. Hartmann is the Chief Chemist of the Gas & Fuel Corporation of Victoria. This paper was delivered to the New South Wales Branch of the Clean Air Society of Australia and New Zealand, 17 February, 1970.

Melbourne is now being supplied with natural gas from the Gippsland shelf through a 105 mile pipeline of 30 ins. diameter. Over a million appliances in the Metropolitan area are being converted to the use of natural gas. Early difficulties encountered in the conversion have been overcome and this will be completed by the end of the year. Absence of impurities and ease of combustion of natural gas, coupled with its extended use, is expected to reduce air pollution.

I. Introduction: Gaseous fuels when compared with liquid and solid fuels have the advantage that they are more convenient to distribute and use and are cleaner in combustion. Town's gas is, however, a secondary fuel, whose manufacturing costs include not only the cost of the coal or oil from which it is produced, but also the capital and operating costs of the plant. Natural gas, while frequently slightly higher in cost than coal or oil, is nevertheless competitive in many situations and its advantages outweigh slightly higher prices where they apply. For this reason, in the United States one third of all energy requirements are supplied by natural gas. In contrast, manufactured gas was never able to capture more than a fraction of the fuel market because its cost had to be much higher.

Any statement on fuel costs can only be made in general terms for a number of reasons. First, the price of fuels depends on distribution costs, on the quantity sold and on the origin of the fuel. While a price for natural gas at the Melbourne city gate has been published (3 cents per therm, diminishing with quality) no definite prices are known for coal or oil. Coal prices at the pitmouth are roughly known, but no comparable prices for oil can be quoted. Comparison with manufactured gas can also not be made either because Gas Companies do not publish their manufacturing costs. These will vary widely depend­ing on geographic location, raw mat­erials used and plant employed.

Natural gas is thus a new com­petitive primary fuel intent on cap­turing a share of the market. As this market is continuously expanding, the old established fuels are not likely to lose sales volume but their percent­age of the market will shrink some­what in the future. In fact, coal has steadily lost ground to oil in the years since the war.

Conversion to natural gas of a large city such as Melbourne is a major operation and a brief outline of what has been done is given in this paper.

I I . Exploration Natural gas was known in antiquity and it is claimed that the Chinese have made use of it at one stage piping it into houses by means of bamboo pipes. In the United States the first attempts at utilization were made about one hundred years ago. However, lack of technology prevented the development of the natural gas industry and manufactured gas was used everywhere in preference. In the States natural gas started to forge ahead in the twenties of this century but did not come to its present emin­ence till after the second world war. In Europe, the natural gas industry developed in the 1950's and is there­fore only slightly older than our own.

The first natural gas in Australia was discovered at Roma in Queensland before the turn of the century, and attempts at utilization were made a few years later. Here the technology was inadequate and no lasting in­dustry was established. Serious ex­ploration in the area was resumed after the second world war and con­tinued throughout the 1950's. Gas in quantity was struck in 1954, and after an extensive seismic survey a com­mercial field was established by 1959. This field now supplies the city of Brisbane. Simultaneously, discoveries were made in a number of other places such as Mereenie in the North­ern Territory, Gidgealpa and Yarda-rino in Western Australia, and the largest field was then found on the Gippsland shelf of Victoria. It should be stressed that these discoveries could not have been made without the modern geophysical methods of ex­ploration, and the Gippsland dis­covery was made possible only by the development in the last fifteen years of the large marine drilling rigs.

One of these, the Glomar III rig, was used by Esso-B.H.P. in all explor­ation work in Bass Strait. This is a ship anchored in position by five 16,000 lb. anchors and three 23,000 lb. anchors each with 1,500 feet of two-inch chains. The drilling assembly is monitored by means of a special underwater television camera. A flex-

38 Clean Air / July, 1970

ible pipe leads up to the rig and pro­vision is made for a slip joint and other equipment to compensate for the unit's motion. Drilling in these waters with their frequent high seas is in­evitably a very rough operation.

So far gas has been proved com­mercially in four wells: Barracouta, Marlin, Halibut and Kingfish. The total estimated reserves were recently given as 5.6 trillion ft3, of which 5.3 trillion are in Barracouta and Marlin while the rest is dissolved gas in the other two wells. No estimates have yet been given for Flounder, Tuna or Snapper, but these wells all contain some gas. It is considered that there is enough gas in these to supply Vic­torian and N.S.W. markets on a long term basis.

I I I . Gas Supply Once a field is commercially proved a permanent platform is erected and a number of wells are connected to it by directional drilling. The usual prac­tice is to lay an underwater pipeline from the platform to the shore and from there to the gas treatment plant. In Victoria the latter is located at Dutson near Sale. The gas is found at a pressure of about 1500 p.s.i.g. in the reservoir. It is decompressed to some extent on the platform, and due to the resultant cooling effect, some water and hydrocarbon condensate separate. Methanol is added to the gas prior to being piped ashore in order to prevent hydrate formation. At this stage the gas is still at a pressure above 1000 p.s.i.g.

In the gas treatment plant, heavier hydrocarbons, water and hydrogen sulphide are separated. This is done by expansion and cooling, absorption on Linde sieves, and finally in a re­frigeration plant. The gas is then ready for pipeline transport to the city.

The natural gas, as found, can vary widely in composition but is charact­erized by a high proportion of meth­ane. Some gases have no, or very small amounts of higher hydrocarbons, and these are called "dry" gases. In Gip-psland, as in the majority of fields around the world, decreasing quanti­ties of the hydrocarbons ethane, pro­pane, butane, etc. are present, up to nonane (or higher). The propane and butane are separated and marketed as liquified petroleum gas while the mixture of higher hydrocarbons is a natural gasoline.

Hydrogen sulphide, which is present in small quantities, has to be removed to less than 0.25 grains/100 ft3 (4.2 ppm) to comply with the new Vic­torian Gas Act. Other sulphur com­pounds are limited by contract be­tween buyers and seller to less than 2.0 grains/100 ft3 (35 ppm) provided that any mercaptans do not exceed 0.2 grains/100 ft3 (3.5 ppm). The gas

supplied at present contains no de­tectable hydrogen sulphide or mer­captans but does contain a small amount of carbon oxysulphide.

Specifications on water content are very stringent, limiting it to no more than 7 lbs/million ft3 (150 ppm). This is required to eliminate the possibility of hydrate formation. Natural gas hydrates are mixed crystals of water in the form of ice with methane, ethane, propane, butane and carbon dioxide. They have the appearance of snow and are formed at temper­atures above the freezing point of water and at pressures in excess of 200-300 p.s.i.g. Decompression of the gas from a higher pressure with re­sultant cooling will lead to hydrate formation. Hydrates only form in the presence of liquid water.

The above specification limit is de­signed to eliminate the possibility of liquid water at less than 1000 p.s.i.g. and temperatures greater than 32° F. Where water can not be fully removed, a freezing point depressant such as methanol is added to avoid blockage of valves or pipes which might other­wise result.

The Gippsland gas supplied at present has a water content of less than 0.01 lbs/million ft3 (0.21 ppm).

Below is a typical analysis of the gas as supplied at present. Methane = 89.5% Ethane = 5.4% Propane = 1.8% i-Butane = 0.4% n-Butane = 0.15% i-Pentane = 0.07% n-Pentane = 0.01% Higher hydrocarbons = 0.02% Carbon dioxide = 0.65% Nitrogen = 2.00% Gross Calorific value = .070 B.T.U./ft3

After the commissioning of the re­frigeration plant, hydrocarbons higher than propane will almost disappear, ethane will be reduced, and the pro­portion of methane will increase cor­respondingly. The gross calorific value will then be reduced to about 1020 B.T.U./ft3.

Many natural gases from other fields contain large amounts of carbon dioxide and/or nitrogen. The gas from the New Zealand Kapuni field for ex­ample contains 40% carbon dioxide. As removal is expensive, the low con­centration of these impurities in the Gippsland gas is indeed fortunate.

IV. Gas Transmission The three main functions in the nat­ural gas industry are production, transmission and distribution. These are sometimes performed by three separate organizations but at other times two or even all three may be combined. In Victoria, Esso-B.H.P. is the producer, and the Government

has set up the Victorian Pipelines Commission to transmit gas through­out the state. This newly constituted authority engaged the Gas and Fuel Corporation to design the Dutson-Melbourne pipeline and supervise its construction. A gas measuring and testing station was constructed at Dutson and a "city gate" station was built at Dandenong on the outskirts of Melbourne.

The pipeline diameter was fixed at 30 inches with a maximum operating" pressure at 1000 p.s.i.g. X-60 steel was used in the construction. About 85 miles of pipe, with 0.406" wall thick­ness, was made in Australia and the remaining 25 miles were obtained from two Japanese manufacturers. Of this, 5 miles was 0.5" wall strength for use near townships. The pipes were lined on the inside with epoxy resin, mainly as protection against corrosion in storage, but also for the added benefit of smoother interior walls to give greater transmission capacity at high loads. The exterior of the pipes was coated with coal tar enamel, reinforced with fibre glass matting and asbestos cloth.

The contract for laying the pipe­line was awarded to Snam-Progetti, who are the construction subsidiary of ENI, the Italian State hydrocarbon authority. Welding inspection and construction supervision was carried out by the Gas and Fuel Corporation. 100% radiography was used for weld­ing inspection and about 60 samples were actually cut out of the line after welding for micrographlc inspection and hardness testing.

The laying of the pipeline was completed in 11 months and towards the end of construction completed sections were hydrostatically tested and then dried with air from portable compressors to a dew point of less than -30° F.

In early March 1969 the pipeline was ready for transmission of natural gas to Melbourne.

V. Conversion of Appliances The characteristics of natural gas very from those of manufactured town's gas to such an extent that every ap­pliance was to be converted so that it can burn natural gas. While in some appliances modifications are quite simple, in others they are fairly extensive.

The differences between the two types of gases are briefly as follows: 1. Gross calorific value of natural gas

is about twice that of town's gas, but its density relative to air is the same. The heat input to an appliance is characterized by the so-called Wobbe Index which equals:

Clean Air / July, 1970 39

was found that they would not oper­ate satisfactorily on natural gas when both oven and griller were operating at the same time and extensive work had to be done to produce suitable modifications.

A few of the unflued heaters also showed great sensitivity to adjust­ment, necessitating particularly care­ful control.

At present the number of com­plaints have been reduced to half as adjusters have gained experience, and the causes of earlier troubles were analysed. Conversion is now proceed­ing at the planned rate of two sec­tions per week. At present it is anti­cipated that the whole operation will be completed by the end of 1970. Repeated surveys have shown that the vast majority of customers are now satisfied with both natural gas and the conversion of their appliances.

A point of concern from the begin­ning has been the odour of the gas because natural gas as supplied at the City boundary is odourless, and an odourant has to be added for safety. The contractor had warned the cor­poration that one of their chief causes of complaints in other conver­sions was due to the odour of natural gas being different to town's gas. This had frequently given rise to com­plaints about excessive leaks. The contractor, therefore, asked that the odourant added should give an odour as close as possible to that of the town's gas previously used and that

it be kept to a minimum consistent with safety.

There are only three types of odourant in use at present, and all are sulphur compounds: mercaptans, aliphatic sulphides and cyclic sul­phides. There is no experience with aliphatic sulphides in Australia but tetrahydro-thiophene, a cyclic sul­phide had been used for years to odourize brown coal gas from the Corporation's Lurgi plant. As some tertiary butyl-mercaptan had also been present in town's gas in recent years, a mixture of two-thirds of tet­rahydro-thiophene and one-third ter­tiary butyl-mercaptan is used to odourize the natural gas. Following published information and the sup­plier's recommendations, % lb of this blend was added per million fts (i.e. about 2 ppm). Records of gas escape complaints soon showed that this was too high and thus both absolute quantity and the concentration of the mercaptan were reduced to a lower, but still safe, level. Odourant concent­rations are monitored both by nose and by gas chromatographic analysis. After conversion is completed odour levels will gradually be raised again as consumers get used to the odour.

When conversion is completed next December, Melbourne will have avail­able a new source of energy which is endeavouring to obtain an increased share of the market.

New natural gas tariffs will give domestic consumers reductions be­

tween 10 and 20% depending on vol­ume used and industrial gas custom­ers reductions 10 to 50%. With higher quantities even greater reductions may be obtained. As a result of this and a vigorous sales campaign con­sumption is already rising sharply in spite of the conversion difficulties mentioned.

Natural gas will certainly also have an impact on air pollution. In its combustion all the usual pollutants are present in negligible amounts with the exception of oxides of nitro­gen and these are produced to a lesser extent than with other fuels.

As Australian fuels are generally low in sulphur, natural gas will prob­ably not displace other fuels to the extent it has done in the United States, but the freedom fram poll­ution combined with the fact that no tall stack will be needed will recom­mend it in many industrial situations in our urban areas.

The present contract with the supplier runs for twenty years and adequate reserves are available for this period. Concern has been express­ed that conversion has been under­taken without assurance of a longer lasting reserve. However, there is gas further away at Mereenie and over­seas experience has shown that further discoveries can be confidently expected. The natural gas industry in Australia, like its counterparts over­seas, is likely to be a vigorous growth industry.

ATMOSPHERIC ENVIRONMENT AN INTERNATIONAL JOURNAL

EXECUTIVE EDITORS D. J. MOORE W. KLUG J. P. LODGE, Jr. U.S.A.

Central Electricity Research Laboratories, England. Technische Hochschule, Darmstadt, Germany. National Center for Atmospheric Research, Boulder, Col.,

The journal is published Bi-monthly. Publishing Offices: Headington Hill Hall, Oxford

Subscription Rates per annum (inc. postage) — (a) £20 ($US 50.00) for libraries, Research Establishments and other multiple reader Institutions. (b) £3.10s.0d. ($10.00) for individual subscribers who write direct to the publisher certifying that

the journal is for their personal use. Back issues are available; write for Back Issues Price List.

PERGAMON PRESS LTD. HEADINGTON HILL HALL, OXFORD, ENGLAND

44-01 21st STREET, LONG ISLAND CITY, N.Y. 11101, U.S.A.

Clean Air / July, 1970 41

New South Wa les Branch

The first meeting of the New South Wales Branch for 1970 was held on February 17. The presentation of the Annual Report (printed elsewhere in this issue) was followed by the elec­tion of office bearers for 1970. These are as follows: President: Mr. K. Sullivan. Secretary/ Treasurer: Mr. J. Pottinger. Council­lors: Dr. K. Basden, Mr. A. Denholm, Mr. I. Doig, Mr. N. Lamb, Mr. P. Mur­phy, Mr. S. Stanley, Mr. H. Voss, Mr. R. Williams.

Following on the Annual Meeting an address was given by Mr. H. Hart-mann, President of the Victorian Branch of the Society on "The Advent of Natural Gas in Australia and its Implications for Air Pollution Con­trol."

On the night of February 18, the New South Wales Branch of the So­ciety held its second public meeting. This time in the Newcastle Area at Mayfleld, the heart of sources of in­dustrial pollution in the area. The meeting was opened by Mr. K. Sulli­van, New South Wales Branch Pre­sident and was chaired by the Deputy Lord Mayor of Newcastle. The guest speaker was Mr. R. P. Murphy, Prin­cipal Engineer of the Air Pollution Control Branch of the New South Wales Health Department. Mr. Mur­phy spoke to an audience of over 60 members of the public, on the effects of air pollution and measures used both in Australia and overseas to control the problem. The talk was followed by a film on air pollution after which the meeting was thrown open for general discussion.

Victorian Branch

March Meeting. The first meeting of the year was addressed by Dr. Nigel Gray, Director of the Anti Cancer Council of Victoria on the subject of "Air Pollution and Human Health."

Dr. Gray pointed out that apart

from the fact that air pollution in London and similar cities in the United Kingdom causes chronic bron­chitis, the direct health effects of air pollution are not serious, although they may be unpleasant: for example, Los Angeles smog causes eye irrita­tion, but not serious disease.

Nonetheless, there is the clear pos­sibility that increases in air pollution could be responsible for diseases not yet defined. In the cases of yellow fever, smallpox and polio the identity and extent of the problem was well

known before an answer was avail­able.

In the case of pollution, at this stage we know far more about its con­trol, than the medical effects of air pollution. In view of the spectrum of possibilities of these effects, controls are essential. This will require some of the most important public health decisions of this century.

About 40 members and their friends attended the meeting, the contents of which were afterwards reported by both press and radio.

BOOK REVIEW AIR POLLUTION ENGINEERING MANUAL

Compiled and Edited by John A. Danielson, Public Health Service Publication No. 999-AP-40 U.S. De­partment of Health, Education and Welfare. Obtainable by wri t ing to the Superintendent of Documents, U.S. Government Printing Office, Wash­ington D.C. 2002. Price $U.S. 5.75 (Normal Sea Freight approx. $16.50).

This manual is unique, because it deals with the control of air pollution at individual sources, emphasizing the practical engineering problems of design and operation.

The sources of air pollution are in the metallurgical, chemical and pet­roleum industries and in mechanical, combustion and incineration processes carried out by all industries. It is re­cognized that while the literature con­tains excellent data on some of these, no handbook or manual has previous­ly been compiled. Thus the new vol­ume fulfils a distinct need.

The air pollution problems pre­sented in the manual originate in the Los Angeles area, which has commer­cial industrial sources of a distinct nature, some processes such as burn­ing of coal in combustion equipment are not mentioned. Furthermore, the

degree of control strived for in the techniques surveyed in this manual cor­responds to that demanded by the air pollution control statutes of the Los Angeles County Air Pollution Control District. It must be remembered that many other areas (even within the U.S.A.) require less stringent controls and permit less effective control devices.

The manual consists of 11 chapters, each by different authors and 4 appen­dices. The first chapters treat the history of Air Pollution in Los Angeles County, the types of air contamin­ants, and the design of air pollution control devices. The remaining chap­ters discuss the control of air poll­ution from specific sources. A reader interested in controlling air pollution from a specific source can gain the information needed by referring only to the chapter dealing with that source. If he then desires more gen­eral information about an air poll­ution control device, he can refer to the chapters on control devices.

Many actual field test results are included in this manual. They invol­ved hundreds of painstaking man-years of engineering innovation In the air pollution control field and were carried out by the technical personnel of the Los Angeles County Air Poll­ution Control District, whilst working closely with Industry. This is recom­mended as excellent material which can be used as a guiding reference for air pollution control from specific sources in this country. J.F. MAHER

INDUSTRIAL ENGINEERING LTD. Chemical Plant and Engineering Division

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SALARY in the vicinity of $6,500 per annum. To assist the Manager of the Dust Control Division in the development of Sales and applications for Dust Control Equipment. A Degree or Diploma in Mechanical Engineering and experience in Dust Collection applications desirable. Contributory Superannuation is available and includes a life cover.

The Dust Control Equipment manufactured under licence has the highest world-wide reputation and includes Mikro-Pulsaire bag type collec­tors, Airetron Venturi Scrubbers and Cyclones, and Skirtevant Electrostatic precipitators. Complete supporting technical and application information is available from the Licensors.

Applications should be sent to- THE MANAGING DIRECTOR Chemical Plant and Engineering Division, 97 Franklin Street, Melbourne, 3000

42 Clean Air / July, 1970