Page
Use Green Island Cement
for
Constructural Work of
Every Description.
HOW GREEN ISLAND CEMENT IS MADE
Green Island Cement is manufactured from hard limestone and clay. It is necessary that these materials should be finely ground in order that they may come into intimate contact, with one another in the burning process...
The finely pulverised materials are mixed in a certain definite proportion, roughly one part of clay to three of limestone, and are fed to the Rotary Kilns.
In these kilns they meet the hot gases and flames generated by pulverised coal blown in at the other end of the kilns, and after various chemical actions have taken place, they combine to form Portland Cement Clinker:
17
The "Clinker is ground down with a small percentage of gypsum to regulate the setting time, and Green Island Portland Cement is thus produced.
Although sounding.so simple, in reality the process is an intricate combination of mechanical, physical and chemical operations, needing great skill and care. Nothing but constant and accurate supervision will yield the results "so well-known with Green Island Cement, namely, strength, uniformity and reliability.
•
USE GREEN ISLAND CEMENT
Issued by the
GREEN ISLAND CEMENT CO., LTD.
i
2ND FLOOR,
EXCHANGE BUILDING
ROCKGLOSS
WHITE ENAMEL
FOR BOTH INTERIOR AND
EXTERIOR USE.
STOCKS CARRIED
W. R. LOXLEY & CO.
Berger Product
YORK BUILDING, CHATER ROAD.
98-TON GIRDER FOR LONDON HOTEL.
RIVETS ALONE WEIGH":
28 TONS.
One of the Main Supporters.
+
HONG KONG DAILY PRESS, SATURDAY, NOVEMBER 14, 1931.
Engineering ~ AND BUILDING
UTILISING
DISTILLED WATER IN INDUSTRY.
THE PROBLEM OF IMPURITIES AND SCALING
EFFECTIVE OPERATION OF MULTIPLE STAGE EVAPORATORS.
The problem of a pure fond water is one which has for long claimed the attention of the boiler chemist. Is has necessitated, a search into overy corner of a wide fold of chemistry owing to the many and varied-constituents of the availablo natural waters which might be put service in xtcam-raising. The preliminary treatment of the wator for boiler purposes has long been practised with marked zuccess, con- siderably reducing the time and Inbour involved in the descaling of the boller when the encrusting cunt- pounds precipitated by steaming have assumed a dangerous thickness, Not only are natural waters liable to impurities producing hardness and other undesirable features of boiler operation, but other im- purities lave of late nesumed con
CHEAPER ROAD MAKING
MIXED-IN-PLACE METHOD.
Pin' thick. There is, however, a growing tendency to regard an compacted, as the minium thickzem. necessary to give a satisfactory surface mate
The Aggregate.
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soa-wator, and if this is allowed
The type of aggregate used in to form scale on the exterior of the road construction has been largely graved and crushed stone of a The mixed-in-plato-method-or this construction incluick both heating coils the efficiency of heat responsible for the progros made maximum size of about 1 to fin and transfer falls off considerably. The in many districts in the improve graded to dust. With the use of quality of the scale varies with thement of secondary roads. Natural pressure of the steam and therefore ly the types of bituminous mater-have high inherent stability and in- the light oils it is necessary to the temperistaro, that at higher tem-ials and the kinds of aggregateterlocking of fragments, while, with peratures being much harder than vary according to locality," and, s that at lower pressures, which area result, some surfaces are
the heavier bituminous materials, therefore more commonly employ: bettor than others. But in spite o
far this in not no important with the dis
these differences in the finished pro-former material the custom is to In one type of evaporator sealingduat, the method has much to com- have 3 to 10 Ber cent. or more of is to a large extent obviated by the mand it
material passing the 200 mesh sieve, nature of the coiling of the heating either by scarifying the old base
Usually the aggregate is obtained" while, in the latter the crushier run tubes, which on heating tend to for by adding new material, or by material should prove highly satis tie needs of the crew. The early open, and contrnet somewhat on both scarifying and adding now factory. evaporators were, therefore, of the wooling, thereby breaking the scale rin! is applied in about one-half
matarials. The bituminous "mat
Altough the maximum size of the same type, but operating on a and thus encouraging, its detach-gallon applications by pressure aggregate given above is that gor larger scale. They involved passing ment from the coils.
In marine distributors until the desired orally used, the indications steam through a system of coils gur-work it is very desirable that the immediately after each application used in this type of work should amount has been spread. Discing that the maximum size of stond rounded by aca-water, this being heating efficiency of the evaporators is generally done, which not only not be larger, particularly for the boiled and evaporated by the Intent should be maintained until the end effectively aids in the mixing but light oil material, and might satis heat of the condensing steam. This of the voyago, when opportunity for oil frem adhering to passing, vehi There is a tendency for the coarser also prevents the freshly applied factorily be considerably smaller. lod to the concentration of the salts thorough cleaning presents itself, eles,
particles of-aggregate-to-be-loos- of the water boiled, necessitating This disintegration of the scale in Windrowing and Spreading.. oned from the surface and thrown frequent descaling. Moreover, the effected by raising the temperature
After the required amount of oil lieved that a smaller maximum size to the edges by traffic. It is bo- steam produced from the sea-water
as high as safety allows and then has been added the materials are had still to be condensed, and this allowing a large quantity of cold shines by repeatedly winilrowing
would reduce the segregation and further mixed with blading masubsequent ravelling. process involved the loss of all its son-water to pass round the coils. and spreading until all the aggre important, particularly with the The quality of the aggregate.ie latent heat.
The method has proved very muc-gate is overed and the mix is use of light oila. Until recently uniform in appearance. Areas that the material was considered entis. are lean ars given an additional factory when the fines had a co- Aghin, frequent blowing down of application of oil and then remix-menting value of not less than 100 the concentrated sea-water becomesed, areas which are too rich are by Page impact test, moisture. remixed with additional aggre equivalent of not more than 20 par necessary. The saline strength of gate.
cant, and lineal shrinkage of not sea-water is usually expressed as a To aid in handling traffic, the
more than 3 per cent. More Ta Brline density of 1-32nd, this figure two windrows along each edge and these requirements did not indicate aggregate is generally placed in contly it has become evident that mixing completed on: onch, after definitely the suitability of the age
thus allowing the passage of truf failures of these ronds which were at mixed in the centre of the road considerable number of
rapid fie throughout the complete opera- first believed to be due tion. Speed and plenty of power character of the oil,particularly are essentials in efficient mixing,
es to the quantity of paraffin con- When the mixing operations are tained. have after more careful complete, the mix is spread" to study been definitely determined to " uniform oross section for compne the due to the character by rolling or by traffic or by both, tion. which may be secured either Fagaregate. Mr. J. T. Pauls, who has had much construction shows that there
Experience with the light oil mix experience in this class, of work, a tendency for the slow rise of considers it advisable to roll the the oil to the surface even under surfaco when heavy bitaminous dry conditions, necessitating the material, such П.В. л cut-back remixing of the surfacing as fre- naphalt or asphalt emulsion, is quently as every two or three years, used. The thickness of the finished and where moisture conditions are surface ranges from 1 to 3in comnot so favourable the rate of this preted, with a majority of work movement greatly increased.
Thermal Lossen. From the thermal standpoint the operation lacked any" attempt at efficiency, but that matter was not of the importance which it has as- sumed at the present time. Tho.
cessful.
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siderable importance, including the thermal aspect of the process will representing the proportion of salis
be recognised in the fact that they weight in the water. This value which they are combined and gregato för light oil mixing.
dissolved air which must be ze moved in order to minimise internal corrosion, especially at the higher temperatures common to modern practice. The de-nerator has thus become an essential constituent of the boiler house equipment.
While these conditions are com mon to land practice, a totally, dif- ferent set of conditions obtain in marine practier. Here the only
available water is that from the sea, with its 3 per cent, of dissolved
the solids, mostly of Corrosive type. Yet time was when oven this impute product had perforce, to be baed, accompanied by the practice (of 'blewing down at very short in- tervals to prevent undesirable ac cumulation of the dissolved solids.. Sooner or later, however, it ho- can the law in marine practice that, in order to maintain the clean- liness of the boiler and thus make the greatest use of its steaming capacity, the boiler was to be ori- ginally charged with distilled water, and all make-up. water subsequent ly used was to be of the same type. High Evaporative Capacities of Bofers.
distilled water carries no more en- ergy than the impure water from which it is produced.
With an
The efficient and econ-.. omical lubrication of the METROPOLITAN-VIC- KERS Steam Turbines in. the Electricity Works of the GREENOCK COR PORATION is ensured by:
Lubricating Oils
A grade for tach type of service
is usually not allowed to go beyond 3-32nds after evaporation. The water is then blown out and a fresh supply introduced.
To avoid this intermittent opera tion it is common marine practice to enter for the continuous addition of sea-water and the ejection of auch proportion of the heated water as keeps the saline figure within the allowable limits. This system is known as continuous bringing.
Where loss impure waters are used in the evaporators, the feed is sally controlled by some type of Boat, which maintains a constant. level within the evaporator, Fur- ther, as the shell of these evapora- tors is commonly of castixon, some type of safety valve must be added to obviate the possibility of exces sive pressure. From this point of view the evaporator is the equiva- lent of a boiler, and, as such, re- quires the usual safety provisions of the latter.
Multiple Effect Evaporators," These may provide as many as six stages for the production of distill
Most frequently, how- ever, two stages are used and op cases sextuple fect evaporators dre casionally "thren, though in spoeial in use. While there is increasing efficiency with an increase in the number of stages there is to be set installation.
operation involving no heat loss ised water. should be possible to produce an indefinite amount of distilled water with a relatively small weight of steam. But the nature of the
In the case of land boilers the thermal losses will be equally readi-ngainst this the added cost of "the whole position has changed withinly recognised when the process is
enrried out in a single stage.
In this case practically the whole of the heat, both latent and sensible
the last two decades. Originally concerned with steaming capacitins. af about 30,000lb, per hour, these strani raisers have now assumed in the steer, is lost in the process gigantic proportions, with capn-.
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The advantage of the multiple effect may be atated by the increased amount of water available from constant supply of steam. These re suits are set at about 0.6 of lb. of of condensation, and there are obsingle effect, 1.7 for double effect, fresh water per pound of steam. for cities up to nearly 1,000,000lb. per this heat might be conserved" with multiple principle is employed in vious channels along, which some of and about for triple effect. The hour. At such enormous steaming rates it is obvious that the smallest an increase in the efficiency and the the evaporation of many liquids used in chemical and other manu content of dissolved solids willeston amount of distilled water-produced factures, in which case the increas be very deleterious, and hence the per pound of steam.
efficiency in expressed addition of evaporators for the pro-
The principle involved in this the quantity of water evaporat duction of distilled water to concconomy is that of the use of a plant, it is possible to develop some ed. In a sextuplo effect distilling stitute the make-up. Without this number of distillation units in4lb. of distilled water from a provision the modern rate of steam-series: the steam developed in the pound of coal without counting the ing would be quite impossible, as first unit passing as the heating drip from the first vessel. the slightest traces of impurities medium to the second, thereby be would rapidly concentrate and coming condensed and it the sume begin their pernicious work of caus-time developing further steamaporators is extending. One ad- ing scaling, with its accompanying
vantage at once gained by the sup- loss of heat transfer, priming, and which, as the product of the second ply of distilled water is, generally in some cases decomposition at the stage, passes to the third stage, in, speaking, the elimination of soften high temperature involved, with the which it in turn becomes the heaters; and further, there is the added production of corrosive gassing agent. It will be seen that some up is reduced from 3 to 6 per cent. advantage that the required make- pressing their effects throughout the whale of the steam circuit, economy is possible by this means, down to a to
per cent. by reason While, moreover, the loss of steam and to this reference will be made from the main steam unit is not Inter
considerable, much greater lossen: Bingle Effect Evaporatoza, are experienced from the auxili
In these days, when every item of possible economy in steam-raising is attended to, the use of these
of less frequent blowing out, while the efficiency of the evaporator has been increased to the extent that, over 20 per cent of the beat up-
!
uries, especially in marine plants. For many years, however, plied to it is returned in the form piece by train from Middlesbrough duction of steam for power is often stuga held the field. In them steam
In land stations, however, the pro- evaporators operating on a single of fresh food water. and was transported from Maryle-supplemented by that required for passes through a copper tube coil-which steam may be drawn from.
There are, a number of systems by bens to Marble Arch between 8 and process work. Of this process steam od in a horizontal plane. The coile the circuit, for use in the evapora 7 mm. on Sunday, October 18.
only a proportion finds its way back are surrounded by the impure and tor. It may even be taken from the to the boiler. A considerable dif often costless water. These coils at turbine at pressure of, say, 29th, ference necessitates distilled make one and open out into a steam cheat, absolute developing steam at 9.81b. It was used at the first floor level. An illustration of this is the while from the other the condensed in the evaporator, which can then distillation plant at Billingham,water drains away. Thu steam gen be led back to the lower-bled range of the Hotel to act as one of the with a usual daily production of ersted from the impure water is led of the turbine. The difference be- Agirder 68ft. long, loft, sins. main supports of the building over 3,000 tons of distilled water, the off through a suitable valve to thetween these two pressures gives deep and ft. sins, wide, weighing the Winter Garden and carrying from 7,000 to 8,000 taon.
total capacity for emergencies being condenser.
temperature range of 48 deg. F., a tone was recently constructed by floors above,-
Where such ovaporators are re- and at the relatively low tempera- It will be appreciated that sothequired for marine purposes, some ture involves only a soft scale re- Mesora, Dorman Long & Co., Ltd, The enormity of this piece of steel of the early types were of a simple care must, be taken to ensure the sulte. Further, the feed water pass- Middlesbrough, for the Cumberland can be gauged by the fact that the order and not marked by a high formation of a soft and therefore ing back to the boiler is allowed to Palace Hotel, Marble Arch, Lon rivets, used in its construction alone work distilled water was always recaps there must be the considerable thereby adding farther to the degree of efficiency. In marine, epaily detachable scale. In any take up heat from the hot drains, don. This girder travelled in one weigh 2 tons.
quired a fresh water for the domes concentration of the salts of the efficiency of the plant.
*
A.
to the
THE EXPRESS LIFT CO., LTD.
WITH WHICH 1 INCORPORATED THE BUSINESS OF
SMITH, MAJOR & STEVENS, LTD.
EXPRESS SMS
LIFTI
MODERN LIFTS
FOR MODERN BUILDINGS
SPEEDY RELIABLE SERVICE
FOR DETAILS APPLY TO.
THE G.E.C., QUEEN'S BUILDING, Chatre Road.
The
EVERYTHING
of the
S&C ELECTRICAL
is