TRANSACTIONS OF
THE ENGINEERING ASSOCIATION OF CEYLON
ECONOMICS OF POWER UTILIZATION
IN CEYLON.
BY
D. J. WIMALASURENDRA,
A.M.I.C.E., A.M.I.E.E., District Engineer, P. W. D.
INTRODUCTORY
The prime source of all energy, no matter in what form it may present itself to
us, is the sun. The most recent investigations made show that the "solar
constant," that is, the amount of heat which reaches us in unit time - making
due allowance for losses in transmission through. the atmosphere - is 1.93
calories per square centimetre per minute. This is equivalent to 5,000 h.p. per
diem, for every acre. Of this vast quantity of energy, an infinitely small
proportion is retained and stored through the agency of the chemical and
physical changes it produces.
AVAILABLE SOURCES OF ENERGY
The energy thus stored may be classified as follows:-
Energy in the potential form, accumulated and stored during long periods of
time, in the form of coal, heat, lignite, petroleum, &c.
Energy in potential form, accumulated and stored for short periods, as wood
and other vegetable products.
Energy in Kinetic form, for which there is practically no natural storage,
such as water, winds, the tides and radiant heat from the sun.
Transactions of the Engineering Association of Ceylon
These are the various sources on which we can draw; and we will now consider the
sources which are of the greatest commercial utility to us in this country.
Ceylon is deplorably destitute of any source of accumulated energy of the form
described under 1.
There is only a very moderate amount of wood suitable for fuel, and that exists
sparsely scattered throughout the country and no organized attempt has hitherto
been made to utilize what is available on a commercial basis. Charcoal, leaving
aside other bye-products of commercial value distilled in the process of
conversion, has a good commercial value as fuel, especially, for use in producer-gas engines.
A vast store of energy in the Kinetic form is one of the most valuable assets in
this country. The extent of its availability and the possibilities of its
utilization for producing cheap power will be considered later.
SOURCES OF POWER IN USE.
The principal sources of power in use in Ceylon are:
(a) Coal imported mostly from India and the United Kingdom.
(b) Liquid fuel imported from Russia, Texas and elsewhere.
PRIME MOVERS.
Cable No. 1 contains a statement of the principal prime movers in use in Colombo
during 1917. This table is compiled from data given in Ferguson's Directory for
1917.
TABLE I.
STEAM ENGINES.
GAS ENGINES.
OIL ENGINES.
No.
Total Horse Power.
No.
Total Horse Power.
No.
Total Horse Power
90
6,450
38
1,450
17
2,765
(200 Steam Locos)
9 6
of 296 of 27
The average size of Steam Engine in use is 70 H.P.
" " " " Gas Engine " " " 40 H.P
" " " " Oil Engine " " " 35 H.P.
.
Taking first the case of steam engines, the engines in use, are mostly of the medium or low pressure non-condensing type, working at pressures varying from 70 to 90 lbs. per sq. in. The average steam consumption of this type and size of
engines range from 30 to 35 lbs. per B.H.P. per hour. An allowance of an average
consumption of 30 lbs. per B.H.P. will be quite a conservative one. The duty of
the boilers in use is about 5 lbs. of steam at 80 lbs. pressure evaporated per 1
lb. of coal consumed; so that the coal consumption per B.H.P. per hour is about.
6 lbs.
Total coal consumption per hour
for 90 x 70 H.P. = 6300 x 6 lbs,
Per year of 313 working days of
10 working hours per day = 6x6300x313x10/2240 tons.
= 52820 tons nearly.
Cost of coal per year
at Rs. 20/- per ton = Rs. 1,056,400.
If this amount of motive power, aggregating 6,300 B.H.P., is supplied to the
various consumers by means of electricity generated at a central station,
employing modern types of steam Turbo generator plant, an enormous saving could
be effected in the coal consumption, besides supplying the power to the
consumers at much reduced rates. A modern Turbo-generator set of requisite
capacity to generate this output will consume only 12 to 13 lbs. of steam per
Kilo Watt hour, which, taking the latter figure, works out to 9¾ lbs. of steam
per electrical H.P. and the coal consumption will be only 2 to 3 lbs. per Kilo
Watt hour, i.e., if we take the latter figure, 2¼ lbs. per H.P. electrical.
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Allowing an efficiency of transmission of electricity at 90 per cent., over a
four mile radius, the nett saving of coal works out to 29,711 tons per annum and
this at Rs. 20/- per ton = Rs. 594,220 saving per annum.
At this rate of earning a capital outlay of Rs. 13,205,000/- could, at 4½ per
cent. interest, be profitably invested in an undertaking of this earning
capacity.
Now making ample allowance for. stand-bye plant and supply mains extending to a
four mile radius, the cost of a steam Turbo-generator plant installed does not,
on the very most, go over
£35 per K.W., i.e., Rs. 525/-. The capital cost of an
undertaking to meet these requirements will come to only about
Rs. 525 x 6300 x ¾
= Rs. 2,480,625/-
With a load factor of about 30 to 35 per cent., power could be delivered
electrically within a four mile radius at a wholesale price of 3 to 3½ cts. per
unit with a substantial margin of profit. Whereas if the whole of the 11,000 H.P.
used in Colombo could be served electrically from a central generating station
and the lighting be also secured for this projected undertaking, which will help
to raise the load-factor, both the capital expenditure and plant per K.W.
installed and the running expenses, &c., could be still further reduced. With an
undertaking of this capacity it ought to be quite practicable to supply
electricity for power at 2 to 3 cents per unit and for lighting at 12 to 15
cents per unit, with a good margin of profit.
In Fig. 1, Appendix, is given a curve showing how the capital cost of an
electricity undertaking per K.W. hour capacity and with an average radius of
distribution of about 5 to 6 miles, is reduced with an increase of capacity of
the generating plant.
The outlay on the mains and distributing net-work is included in the cost per K.W. This curve is taken from a past number of the "Electrician".
The average cost of a 70 B.H.P. motor of the five different types largely in use
in Colombo and other parts of this country is given in Table No. 2 below. The
prices given are the average in the British market with a 30 per cent. added to
meet cost of freight, etc., etc., etc.
TABLE II
Electric Motor with Starter.
Steam Engine
Town Gas Engine.
Suction Gas Engine with Producer.
OIL ENGINE.
Ord. Liquid Fuel Engine.
Diesel.
Rs 3,500
Rs 14,000
Rs 10,200
Rs 15,550
Rs 14,800
Rs 19,350
The electric motor priced as above is capable of carrying an overload of 25 per
cent. over the rated output of 70 B.H.P., whereas the best an oil engine could
do, when in good working order, is 15 per cent. and the Suction and Town gas
engines only 10 per cent. So as to place the comparison on "all fours"
with the electric motor, an oil engine that will develop a normal working load of 77
B.H.P. and a suction-gas engine of 80 B.H.P. will have to be considered. This
will increase the capital outlay on the oil engine by about 10 per cent. and the
suction-gas engine by about 12 per cent., thus bringing up the capital cost of
the oil engine to Rs. 16,280/ and the suction-gas engine to Rs. 17,420/-.
Analysis of costs per B.H.P. hour for each of the prime movers are given on
pages Nos. 19-20 appendix, and the costs may be tabulated as follows:
A Perusal of these figures will show the relatively small capital outlay, a
small power consumer using 70 B.H.P. has got to invest in an electric motor as
compared with a liquid-fuel engine or a Suction-gas engine.
The saving to him in capital outlay over a liquid-fuel engine is Rs. 14,000/- and
Rs. 15,420/- over a suction-gas engine. He will thus be in a position to invest
this saving in machinery more remunerative to his particular class of business.
In working out the cost; per B.H.P. given in columns 3 and 5 of the above table,
interest on the capital outlay has been reckoned at 4½ per cent. This will be
warrantable in a Government undertaking where the pockets of the officers
responsible are not in any way effected by the economy or otherwise of the plant
installed; but in the case of a small private consumer, the interest on the
outlay lay must be reckoned on the, profit-earning value of the capital invested
in his particular business, and this will be more in the order of 12 to 15 per
cent. If we take an average rate of interest at 13½ per cent, the actual cost
per B,H.P. hour to the consumer works out to figures given in columns 3 and 5 of
Table III.
It is now obvious from these figures that the electric motor is the cheapest
motive power in the market. It is a fact acknowledged in all parts of the
civilized world that besides the numerous advantages peculiar. to electric
drive, there is no motor yet devised that can compete with it for supplying
cheap power.
In this connection the following extract from the Interim Report of the Coal
Conservation sub-committee of the Reconstruction Committee published in the
"Electrician" of 28th December, 1917, is both interesting and conclusive.
One question that has been settled conclusively during the last 15 years is
that the most economical means of applying power to industry is the electric
motor.
Thus the problem is not so much how to apply the power to the tool or process as
the case may be; but how best to generate the "electric power"
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It should be stated here that the consumption of coal in steam locomotives is
also about 6 lbs. per 1 H.P.
CENTRALIZATION OF POWER PRODUCTION.
"The production and distribution of power in bulk from large and suitably placed
central power stations would at a conservative figure save us 50 per cent of our
coal bill for power purposes and effect a still greater saving in cost of power
generated." - Electrician.
The advantages of centralization of power production may be very briefly
summarised as follows:
Economy in working, due to
(a) Large units; (b) Units run more nearly on full load and therefore at a
higher efficiency (c) Reduced cost both in capital outlay on prime movers and
installing them; (d) Saving in attendance cost; (e) Reduced outlay on fuel, as
cheaper qualities of fuel can be used at a high efficiency; (f) Stand-bye plant
carried at a lower percentage capital cost.
In case of a now mill more capital can be spent on remunerative machinery.
Elimination from customers consideration of all matters not directly
connected with his business, e.g., engineering details, fuel costs, etc.
Facility with which any portion of a mill can be run, independent of the
rest.
The expert advice of the Power Company's engineers are at the customer's
disposal when engineering problems arise.
WATER POWER.
The two principal methods of producing electricity in bulk are either by use of
steam power or water power. What this country deplorably lacks in accumulated
energy in the form of coal or oil deposits, it possesses in abundance in "White
coal". The exploitation and development, of the extensive sources, of water
power available and utilization of them by rational generation and distribution,
to meet the large demand for cheap power in this, country, both for traction and
industrial purposes has so far not been attempted to any degree.
To the very limited extent investigations have so far been made by the
writer, the following appear to be the principal sources of water power in this
country and their approximate capacities are as noted below.
The river Mahaweli is the greatest asset we possess in this respect. At its
minimum flow, without any provision for water storage it is capable of
developing over 70,000 E.H.P. at a point which, on a direct line, is only 12
miles from Peradeniya and 24 miles from the Ambewella Railway station and 20
miles from Nanu Oya.
At a point about one mile below (a) another about 30,000 H.P. could be
obtained.
At spot about 8 miles distant from Kandy about 12,000 E.H.P. can be derived.
At Ulapana again another 15,000 E.H.P. could be obtained. So that at these
four spots alone this river is capable of furnishing us with over 127,000 E.H.P.
The Kotmalic Oya, one of the tributaries of the Mahaweli. could be harnessed
to give over 6,000 E.H.P. at Talawakelle alone.
Aberdeen Falls, situated on a source of the Kelani River, is capable of
contributing 10,000 E.H.P. at one spot.
The Laxapana Falls and Kitulgala rapids can be harnessed to derive over
50,000 E.H.P. and this source is only 42 miles distant from Colombo on a direct
line.
Besides the above there are several other sources distributed throughout the
Central Province, which could be harnessed to contribute from 3,000 to 1,000 H.P.
each. Everyone of the sources B, C, D, E, F, could be developed to contribute
power on a commercial basis to a main distribution network fed by either of the
main sources A or G.
Power derived from one or more of these sources could be utilized for operating,
some sections of our railway system electrically, especially the hill section,
and that most economically. For the purpose of this paper, we will select for
consideration the section from Polgahawella to Bandarawella including the branch
line from Kandy to Matale.
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In absence of data of the existing steam loco. service, it is difficult to
determine the exact amount of power that would be required to operate this
section. On reference to the railway pocket time-table, roughly, 52 locomotives
are found to be in service each day in hauling the trains over this section.
Allowing another 8 locomotives for switching, etc. a total of 60 locos. can be
said to be in service per day over this section. The average loco. working over
this section cannot be over 2,000 H.P. when developing its maximum power. If we
suppose that ? of this total number of 60 locos., viz., 20, will be in operation
simultaneously over this section this will probably cover all contingent
services. This will necessitate an aggregate power output of 20 x 2,000 = 40,000
H.P. But all the 20 locos. in operation simultaneously will not be developing
their maximum output at one and the same time. One train may be running on a
level section while the other is ascending a steep gradient. Therefore about 60
per cent. of this 40,000 H.P. will be a conservative figure to allow.
60/100x40,000 H.P. =24,000 H.P., which is the nett horse power that would have
been required to work the normal passenger and. goods traffic - prior to the
recent retrenchment - over this section.
The over-all efficiency from the outgoing cables at the generating station to
the pantagraphs on the electric locos. will be about 75 per cent. and the "Pantagraph to Drawbar" efficiency of an electric loco. of about 2,500 H.P. is about 89 per cent., so that the resultant efficiency of the system between the generating station and the tractive force exerted by the loco. will come to 89 x 75 per
cent.
= 66.75 per cent.
= 66 per cent. say.
The capacity of the plant will therefore have to be increased in this
proportion:
Now source A is capable of developing about 70,000 E.H.P. so that the power
available from this source alone is about double our requirements.
GENERATING COSTS.
Source A could undoubtedly be harnessed to generate this 70,000 E.H.P. at a cost
of about 1½ to 1¾ cents per Kilo Watt hour. If this energy is to be delivered at
Peradeniya and Ambewella, or Nanu Oya., which appears to be the most suitable
feeding points for our purpose, and which are situated at an average distance of
about 18 miles from the source A, the additional investments costs associated
with the step up and step down transformers, transmission lines. etc., together
with the operating costs will add, at the most, another one cent per K.W. hour
delivered, thus bringing up the cost of electricity delivered to the tie-in line
feeding the overhead system at Nanu-Oya and Peradeniya to 2½ to 2¾ cents per
Kilo-Watt hour.
These figures are based on costs available, of power output, from hydro-electric
undertakings of similar capacity, in operation in different parts of the world.
But in almost all these undertakings, the provision of a fair water storage and
consequent capital outlay thereon has influenced the rate per unit generated.
The entire absence of the necessity of any water storage to get this vast amount
of power in this case will be an important factor in reducing the amount of the
capital investment on the installation and therefore the final cost of the
electricity manufactured. With power obtainable at this rate or even a slightly
higher one, the fact that electric traction per ton-mile compares most
favourably or is cheaper than steam loco.-haulage, results of what has been
accomplished in other parts of the world, most successfully, go to establish
beyond doubt.
STEAM VERSUS ELECTRIC HAULAGE.
In absence of actual data of costs of operation, by existing steam locos,
comparative costs of operation by the two systems cannot be derived.
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However, estimates made by Mr. Hobart., an eminent authority on
electric railways, and reproduced in his Forest Lectures of
1916, for the electrification of a hypothetical 96 mile single-track mountain-grade division of a main railway, illustrates the merits of the project under
consideration. This example has been selected as it affords the closest parallel
the writer has been able to find, to the project under consideration. The main
points may be briefly recorded as follows:-
2,400 VOLT RAILWAY ELECTRIFICATION.
Trains ascend to an altitude of 3,800 ft. in 48 miles and return to the original
level in the remaining 48 miles, average gradient 1.5 per cent. Trains up to
1,600 tons were to be hauled by electric locos. at an average speed of 12 miles
per hour.
48 locos. each averaging 27,200 loco. miles per annum, estimated to be required.
Price paid for electricity delivered at the sub-station .336d x 6 = 2.016 cents
per K.W. hour.
Total amount of outlay for (a) Electricity per loco. mile with and without
regenerative control work out as follows:
TABLE IV.
Annual Outlay for Electricity
Without Regenerative Control
With Regenerative Control
Per Locomotive
£ 4,160
£ 3,100
" Loco. mile
36.8 d
27.4 d
The relative operating costs for the steam loco. and the two cases of electric.
locos. without and with regenerative control are shown in Table V. Electricity
at .336 d per K.W. hour. Lignite (fuel for steam loco.) with a calorific value
of 11,000 B.T.V. per pound at 11 shillings per ton.
It was shown in the paper that for 1,600 tons behind the Drawbar there would be
required three 200 ton steam locos. or two 143 ton electric locos. Consequently
the operating expenses per train-mile work out as follows, vide Table VI.
On a perusal of above figures it will be apparent that the cost of hauling a
given train load by steam locos. is 50 per cent. higher than for same done by
electric locos.
CAPITAL CHARGES AND COMPARATIVE EFFECTS.
The average cost per ton of steam locos. is £ 24
" " " " electric " £ 80
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Crediting both locos. with a fifteen year economical life, the annual outlay in
pounds sterling per loco. mile has been found to be as follows. (Hobart on
Electric Railways. Forrest Lecture, 1916.)
TABLE VII
Annual Outlay in Pound Sterling
Per 225 Ton Electric Loco.
Per 330 Ton Steam Loco.
Fuel and Power
£ 2,080
£ 2,020
Wages of Loco. crews
£ 1,020
£ 730
Repairs of Locos.
£ 810
£ 1,250
Interest Taxes & Amortization
£ 2,400
£ 960
Total
£ 6,310
£ 4,950
Total per Loco. Mile
43. 3 d
47. 5d
From, the above study, which is based on equal train loads hauled, the saving in
favour of the electric loco. is an inconsiderable amount. However, in practice
advantage is taken of the inherent ability of hauling heavier trains with
electric locos. and at higher speeds. In both these respects electric operation
increases the capacity of a railroad and incidentally decreases the outlay for
wages of engine crew and train crews.
In this comparison of ultimate costs coal fuel has been priced at 11 shillings
per ton, which is equivalent to Rs. 8/25 per ton in Ceylon currency. But the
average cost of steam coal in Ceylon is Rs. 20/- per ton, and outlay on fuel
being a predominant factor in the total cost of operation by steam locos., the
saving in favour of the electric loco. with the high price paid for coal in this
country will be much more pronounced.
Sources F and G are, on a direct line, about 42 miles distant from Colombo and
about 22 miles from Ambewella - Separated as they are, only by a distance of about
three miles, they could be linked together electrically; and so combined, will contribute about
45,000 E.H.P.
A much higher head of pressure to operate at, than in source A, is
obtainable for both of these sources. Therefore, though the combined capacity is
less than that of source A, the capital investment per unit of power developed
will be perhaps a trifle less. With a load factor of about 60 per cent. it will
be practicable to deliver electricity from this source to consumers in Colombo,
under conditions specified on page 4, at about 2½ to 2¾ cents per unit for power
and 12 to 13 cents per unit for lighting.
Now it is evident that either of the sources A or G and F combined, could be
harnessed to develop sufficient power to operate the section of the Railway
under consideration.
Fig. 1A gives the approximate positions of the different sources of water power
referred to, and the location of the railway track, the electrification of which
has been discussed in this paper. The possible overhead supply system and the
feeding points are also shown diagrammatically.
REGENERATIVE CONTROL.
The profile of the track from Polgahawella to Bandarawella is almost "irregular
one" rising to an a1titude of 5,929 feet in 94 miles and then falling 2,164 feet
in 21 miles. It has thus an average ascending gradient of 1.2 per cent, and a
descending one of 2 per cent. By the adoption of regenerative control, the
momentum energy of the descending trains is utilised to drive the electric
motors as dynamos and return most of it in the form of electricity to the
distribution system. Considerable saving is introduced by the interchange of
current thus produced, between ascending and descending trains. The reduction in
wear of wheels, brake rigging. etc., combined with this saving, effect a
considerable ultimate saving in maintenance charges, capital costs in generating
plant, etc.
LOAD FACTOR.
A close study of the curves given in Fig. 2. Appendix, shows the influence "Load
Factor" has in regulating the cost of electricity
manufactured.
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This is especially so in
hydro-electric undertakings. *"A high load factor will permit of effecting a
greater reduction in the cost of manufactured electricity (as compared with the
cost of the same quantity of electricity but of low load factor)
in the case of a hydro electric station than in the case of a coal-burning
generating station". The various expedients that could be adopted to secure a
high load factor may be briefly stated as follows:-
An electrically propelled train load of either dense service, or one extended
over a large mileage of track. The first could be secured in a town like Colombo
by the installation of an electrically- operated urban train service; the latter
by the electrification of the up-country section of the railway. By either
expedient, a high load factor is obtained, by averaging the widely varying
individual consumption of many electric locos.
Tramway Service Load. One is already in operation in Colombo, others will no
doubt come into existence in towns like Kandy, when cheap power is made
available. On economic grounds, the Colombo Tramways will be forced to obtain
their power in bulk from the projected main source.
Securing the power load referred to in Table No. 1.
By organizing feeder services from the termination of the existing tramways
and from the principal railway stations to outlying villages and industrial
centres, both for passenger and goods traffic, in the form of "Rail-less
traction". In this system "Rail less cars" are operated by electricity fed from
an overhead system in the same manner as is done in tramways. It has the
advantage of being able to thread through traffic besides being so much less
costly in installation owing to the absence of the track which is the most expensive item in a tramway system.
Examples of Rail-less Traction are to be seen in Leeds, Stockport, Bradford, &c.,
and in the Continent. A tramway double track costs £12,000 per mile of track
while the overhead equipment £ 3,700 only.
*Hobart on Electric Railways. Note. Load factor of a machine plant or system is the ratio of the average load
to the maximum load during a certain period of time.
The extended use of electric vehicles fitted with storage batteries.
Charging the batteries provides a means of boosting up the load at the central
station at times of "Low peak".
Supplying electricity to estates for motive power and for drying tea
electrically, &c., &c.
Securing as big a lighting load as possible in all the principal towns
through which the electrically propelled railway passes.
CONCLUSION.
The most favourable location of the track, with respect to the sources of power,
and the favourable physical features of its profile for regenerative control
makes it exceptionally well adapted for economical operation electrically.
The electrification of this section will besides result in the
establishment of a net-work of distribution mains - "Main trunk Electric Roads"
-
passing through towns and industrial centres of importance, thus bringing to
their very gates a supply of cheap power to enable such subsidiary services as
those enumerated under heads B - G above to be installed.
The coal output of the world is a limited quantity. The Royal Commission
appointed recently to report on coal supply stated "that the time is not far
distant when the rate of increase of output will be shown to be followed by a
period of stationary output and then a gradual decline". As a result of the
findings of this, Committee Boards of Fuel Research have been appointed in all
parts of the civilized world.
It is impossible to add anything to the force of the appeal by the Ministry of
Munitions for effecting economies in the consumption of coal or to the
resolution passed by the Imperial War conference of 1917 pointing out the
necessity for developing and controlling the natural resources available in all parts of
the British Empire and the economical utilization of such resources.
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The anticipated gigantic business renewal after the war by all nations will no
doubt place prohibitive prices on all forms of fuel and countries like ours,
depending on imported fuel, will no doubt have to pay much more enhanced prices
for perhaps the limited supplies that will be made available to us.
The provision of cheap power, however, is as great a need in Ceylon, as in other
parts of the civilized world. "It ranks only second in importance to cheap food,
with which modern conditions have indissolubly associated. it." The industrial
development of this country has been seriously hampered by the want of cheap
power. Our staple products of commerce, e.g., copra, plumbago, rubber, etc.,
would not have needed the tender patronage of German millers for their
conversion and disposal, after reserving to themselves such stores of them, and
their by-products, as were needed for the production of munitions, had cheap
power been made available in Ceylon.
The development and utilization therefore of the thousands of horse power now
running to waste daily in this country is a national requirement of immense
importance and should be dealt with now, when in the industrial lull caused by
the great war, every country is taking stock of its economic position.
The writer has to acknowledge his indebtedness to the Hon. the Director of
Public Works for permitting him to use in this paper certain results of
hydro-electric investigations made by the writer at the instance of the Public Works
Department.
I may add that a further use that can be made of the current generated at Teldeniya which will also help, largely to improve the load factor at the
station, is in the manufacture of calcium carbide and calcium cynamide and other
artificial manures. Calcium carbide, in its pure form, is used for producing
acetylene for lighting, but in a less pure and cheaper form affords a good artificial manure.
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49
Discussion.
Lime and coke when heated together to a
high temperature of 2,000o to 3,000o C, produce calcium carbide, combining in
accordance with the formula:-
Ca 0 + 3C=Ca C2 + CO
This reaction is carried out in an electric furnace. Calcium carbide is
converted to calcium cynamide by fusing the. former in a stream of nitrogen or
by admitting nitrogen to the electric furnace, in which, lime and coke are being
fused.
Mountain or carboniferous lime-stone beds are said to be in existence in close
vicinity to Teldeniya.
Mr. Ingles, who occupied the chair in the temporary absence of the President,
said :- Gentlemen, we have just listened to a most interesting, instructive and
suggestive Paper. I am quite sure that some members may like to offer some
remarks.
Reproduced from the TRANSACTIONS OF THE ENGINEERING ASSOCIATION OF CEYLON (1918)