In order to encourage the more economical use of oil in industry many interesting and to a certain degree efficient devices have been introduced. But for the most part these apparatus are devoted to the filtering of what may be described as dirty free oil. They scarcely venture beyond the removal of whatever impurities may be associated with the product in the suspensory form. They do not attempt to reclaim waste oil. Such timid treatment is readily explicable. Oil is a somewhat sensitive product. Its inherent qualities may be easily impaired. For example, oil prepared essentially for lubricating purposes must be possessed of specific qualities, of which viscosity is one and the most important. Then the requirements of lubricating oil fluctuate so widely. An oil designed for use with a high-speed engine, such as the petrol motor, is not adapted to the lubrication of a slow-moving steam engine. Yet the depreciation of one single quality in any one grade is adequate to render the oil unsuited to the purpose for which it has been specially prepared.
The consumption of lubricating oil by the authorities during the war ran into imposing figures, and the liability to waste was proportionate to the consumption. Aeroplane engines and lorry motors, together with their auxiliary gearing, were in a constant condition of overhaul. Every time an engine or gearbox had to be dismantled many gallons of oil had to be drawn off. Consequently the handling of this enormous quantity of material to frustrate waste demanded special consideration, inasmuch as the oil could not be put back into the machinery after the latter had been reassembled. The authorities solved the problem by the perfection of an organization for the collection of this oil, which was returned to the oil-refinery to be re-conditioned, that is to be cleaned thoroughly and to have its original properties restored. By the observance of this practice of turning old oil into new the country was saved huge sums.
But there is a vast difference between official and civil conditions. So far as the former is concerned it was a comparatively simple matter to introduce an efficient organization to cope with the problem, while the waste oil was recovered in bulk, the hospitals for treating the engines of the aeroplanes and motor vehicles being centralized. It is the degree to which facilities for satisfying the civil demand are scattered which renders collection and handling of the waste along inexpensive lines so perplexing. It might be satisfactorily overcome if each garage and private owner undertook to maintain a waste-bin and to commit all oil-soddened rags thereto for periodical collection by a centralized authority, either municipal or private. The waste would be obtainable at a low figure, possibly free, inasmuch as the majority of garage owners would only be too glad to be rid of it. Possibly it would be found profitable to strike a bargain along the lines of free waste in return for the de-oiled rags, particularly if they were dusters or cloths. In this event the waste oil exploiter would only be called upon to incur the expense of collection and the treatment of the spoil. The return of the cloths would not entail further expense, because they could be returned in exchange for another consignment of waste. The vehicle would have to make the journey in any event, and it might just as well make the outward trip laden as empty. It is quite possible, moreover, that the garage would be readily disposed to pay a slight charge for the cleaning of this material, particularly of cloths, so long as the sum was attractively below the price ruling for new supplies of the article. To the waste exploiter the value of the oil recovered should be adequate to defray all expenses of collection and treatment, and then leave a handsome profit capable of accretion from the disposal of the cleaned rags, which the garage did not require, for paper-making. It is merely a question of enterprise and organization, and in a large centre could be rendered a highly attractive and profitable venture.
This fact is borne out by the experience of private firms. Of course, it is essential that the volume of spoil handled should be of sufficient bulk to keep the plant installed for the reclamation of the oil going to its full capacity, or to one approaching the maximum. This is possible in the case of a large private company, such as a railway, electric-generating station, or even industrial plant.
One of the largest motor omnibus companies in the world was induced to consider the possibilities of this issue, and finally was induced to make the experiment. The “Iwel” plant in question was designed to turn out 6 tons of clean dry rags per week. This may seem to be an enormous quantity to accumulate during a period of seven days, but it must be pointed out that the company in question maintains 2,000 to 3,000 public vehicles upon the roads, as well as several garages and repair shops.
The first three months’ experience served to bring home the economic advantages accruing from the scientific exploitation of this form of waste. During this brief period the company reclaimed 67 tons of rags for further use, the value of which at the time was set down at £1,007 7s. 1d.—over $5,000—while from this waste 4,080 gallons of oil, valued at £59 10s.—$297.50—were recovered. Here was a distinct gross saving of £1,066 17s. 1d.—$5,334—which figure was increased to £1,489 15s. 7d.—$7,449—on the credit side by the delivery of new rags to depots valued at £419 12s. 6d.—$2,098—and the sale of small rags unsuited to further work for £3 6s.—$16.50. On the debit side the heaviest expenses were incurred in connection with the purchase of new rags, valued at £405 12s. 9d.—$2,028, cartage of the waste £152 17s. 10d.—$764.44, wages and salaries £157 15s. 1d.—$788.74, and coal £105 0s. 11d.—$525.22. The total outgoings amounted to £1,038 16s. 7d.—$5,194.14, which left a balance of £450 19s.—$2,254.72—actual saving recorded by the treatment of the waste. So far as the reclaimed oil was concerned, while this was unsuited to further utilization in its original province, it was found to form an excellent fuel for the operation of the Diesel engines, and consequently reduced the fuel bill on this account by a corresponding amount.
Another illuminating instance of the value of such waste is afforded by the working account for one year, furnished by one of the foremost British chemical manufacturers. The plant acquired in this instance comprised two turbine centrifugal separators, one washing machine, and one drying cabinet, the cost of which complete was £210—$1,050. In the course of the twelve months 350,000 wiping and other cloths were treated, and the losses incurred therewith were so slender as to demand renewals to the extent of only 15,000 new cloths, which, at 2s. 1¹⁄₄d.—52.5 cents—per dozen came out at £131 10s. 2¹⁄₂d.—about $657.55. The heaviest item in the operating account was wages—£132 12s. ($663). Other expenditure, including repairs, fuel, and interest on the first cost of plant, brought the total to £324 2s. 2¹⁄₂d.—$1,620.55. From the treatment of the 350,000 cloths 125 casks, or 5,000 gallons, of oil were recovered, which, at 10d.—20 cents—per gallon, represented £208 6s. 8d.—$1,041.64. The saving in cotton waste due to the soiled cloths being rendered available for further duty, set down at 392 lb. at £4 4s.—$21—per week, came out at £218 8s.—$1,092. Thus the total value of the waste recovered was £426 14s. 8d.—$2,133.64, leaving a saving, after deducting expenditure, of £102 12s. 5¹⁄₂d.—$533.11. The results of the year’s working, therefore, enabled the firm to recoup approximately 50 per cent. of its original outlay, while the value of the oil recovered was only a little below the cost of the plant. The saving in cotton-waste—material which otherwise would have had to be provided—actually exceeded the capital outlay upon the plant.
The Lancashire and Yorkshire Railway Company, in consonance with the general practice, formerly utilized cotton-waste in its works for cleaning purposes. In these operations the material becomes saturated with ordinary lubricating, cylinder, and other oils, as well as grease from rubbing down the locomotives and parts. Some years ago it decided to abandon cotton-waste in lieu of sponge cloths, at the same time installing a plant for the recovery of the oil and grease from the soiled materials. During the year these sponge cloths are passed over and over again through the cleansing process, the operations being equivalent to the treatment of 6,500,000 cloths, and in this manner approximately 45,000 to 56,000 gallons of oil are reclaimed.
It does not matter to what phase of industry one turns, a certain amount of oil is possible of reclamation from the waste employed in connection with the conduct of the work. The volume recoverable naturally varies widely according to the nature of the trade pursued, and in some instances the individual yield may appear to be insignificant. But, during the course of the year, even in a small shop, the figure is certain to become impressive and well worth the efforts expended, as well as the money invested in the requisite plant, while, if the one instance be multiplied by the number of other similar establishments distributed throughout the country, the aggregate must necessarily be formidable. The table opposite furnishes a few actual results in the selection of industries specified.
It will be observed that the yield varies widely according to the industry concerned, but in every instance it will be observed that the figure is such as to render the process profitable, not only on account of the oil thus procured, but from the release of the waste or other absorbent for a further spell of useful service. If the waste, or other material, has been employed only for wiping parts, or mopping up free oil, passage through the oil separator will suffice, but if it has been utilized for general work and has become badly soiled, it requires washing. The sludge resulting from this process is subsequently passed through the oil-recovery plant instead of being thrown away, the reclamation thus being complete, while the rags or other textiles are passed through cabinets or other suitable facilities to be dried quickly.