456 THE COLLIERY GUARDIAN September 8, 1916. CURRENT SCIENCE Power with By-product Recovery. , Mr. T. Roland Wollaston {The Engineer) says it is generally accepted that coal prices will never again fall to the level of ten years ago, when it was possible for a few enlightened and enterprising firms to obtain all the power they required for nothing, the coal by-products obtained exceeding in value the total running, labour, and capital charges on the plant employed. Coal of quite good producer quality could be purchased at 6s. per ton delivered at works, and from every ton could be obtained about 901b. of sulphate of ammonia, worth 9s. 6d. The difference—3s. 6d.—was found to cover easily running and capital charges. With coal at higher prices, the average rebate of 6s. per ton would still pro- bably remain upon a resumption of normal industrial conditions. The universal ideal for future power generation seems to be the installation of economical generating plants in cheap-fuel localities and electrical distribution, and the typical modern station is one containing large steam turbine units, few in number, taking steam from water- tube boilers, and surface condensing. In the following analysis these facts are tacitly accepted, to avoid the introduction of more controversial argument than is absolutely necessary, and a hypothetical example, repre- sentative of a modern electrical generating station of average size, is considered, in connection with which the following assumptions will probably be accepted as reasonable :— (a) The station has a maximum output capacity of 15,000 unite, or 20,000 horse-power, with a load factor of 25 per cent. (5) Coal-fired boilers, working at 70 per cent, average efficiency, consume 21b. of coal per horse-power hour, including banking and standby. (c) Gas-fired boilers will work at 83 per cent, efficiency, calculated on cold gas value. This result is consistently obtained on boilers of ordinary type con- verted for gas-firing. Better results may be expected as special types develop. (d) Recovery gas producers will, on common slack, work at 68 per cent, cold gas efficiency—yielding sulphate of ammonia equal to 4. per cent, by weight of the coal gasified, and generating their own blast steam. The last condition remains to be demonstrated on the large scale, but is clearly practicable. (a) The gas plant, to secure the above efficiency, must be worked continuously at or near full load. The obvious conclusion from (e) is that gas-firing should only be adopted for the average load factor, i.e., 5,000 hoinse-power. The only radical modification from orthodox procedure inside the station would be the adaptation of one-quarter of the boilers for gas-firing or the installation of special gas-fired boilers to this extent. This modification, if it affected capital outlay and labour charges at all, would tend to reduce them, so, for simplicity, capital charges and labour on all but extra plant are ignored. The extra plant, to wit, the recovery gas plant and mains, involve charges which can only be approximated, but which may be reasonably taken as : Extra capital outlay, £22,500; extra labour on plant, £2,100 per annum; extra stores, £700 per annum. Now, taking for the moment 5,000 horse-power as a dead steady load throughout the year, the annual normal coal consumption would be :— 5 ' >L2 X 24 X 365 = 3910. tons 2.240 The combined efficiency of the gas-fired boilers and gas plant will be :— 0-83 x 0-68 = 56-44 per cent. as against 70 per cent, for direct-fired boilers. Therefore the total annual coal consumption under gas-firing will be :— 39,107 x 70 0 .ot'AAx —-———-------- say, 48,500 tons. 56-44 J Taking coal as worth 15 s. per ton, and sul- phate as £15 per ton, at works the proposed practice would yield a net saving per annum of £13,520 on running costs, representing at least 50 per cent, return on added capital outlay, with coal at 15s. and sulphate at £15 per ton. Economies in Gas Production. In the course of his presidential address to the Irish Association of Gas Managers, at the Dublin meeting, Mr. J. E. Enright referred to the method he had adopted at the Tralee gas works for reducing the cost of gas manufacture by cutting down the consumption of coal through using a Tully carburetted hydrogen plant. After inspecting similar plant, he drew up a report on its advantages, which include ability to be started in a few hours, thus making it unnecessary to keep retorts under heat, idle, as a stand-by in case of emergency. By means of this plant any emergency can be met, consequently the coal gas retorts can be worked to their maximum efficiency. It is simple and inexpensive to work, requiring no skilled labour whatever. The repairs and maintenance expenses are very low, and do not amount to one-fourth of that of a coal gas plant. The ground occupied is considerably less than that required for a coal gas plant. The storage or gas holder accommodation is less than that required for coal gas, owing to the ease with which the plant can be started and worked; moreover, the holders can be kept practi- cally full, thereby assuring maximum pressure at all times. That the cost of producing carburetted hydrogen AND TECHNOLOGY. gas is considerably less than that of coal gas, may be observed from the following Coal Gas.—Per 1,000. d. Coal, less residuals ... 20-72 Wages, carbonising ... 2-62 Purification ........... 0-25 comparison :— Carburetted Hydrogen Gas— Per 1,000. d. Oil ................ 3-45 Coke ................. 4-60 Wages ............... 1-50 Purification ......... 0-50 Steam ............... 1-16 23-59 11-21 These figures do not include management, rent, rates, etc., which would be similar in both cases. Taking round figures, at 2s. per 1,000 to manufacture coal gas, it actually costs £3,200 to manufacture 32,000,000 cu. ft. Providing 50 per cent, of the gas was produced in the proposed new plant, the manufacturing cost would be reduced from £3,200 to £2,400 per annum, a direct saving on one year’s working alone of £800. Following upon this report, the District Council ordered from Messrs. Bale and Hardy, London, a car- buretted hydrogen plant capable of producing 100,000 cu. ft. of gas per day, under a guarantee that the cost of production should not exceed Is. per 1,000, allowing 20s. per ton for coke (the present selling price) and 6d. per gallon for oil. The plant was started to work during the month of May last, and gave the following working results for June and July :—The total make of gas for the month of June 1916 was 1,866,400 cu. ft., made up as follows: Coal gas, 915,300 cu. ft.; carburetted hydrogen gas, 971,100 cu. ft. — total, 1,886,400 cu. ft. The coal carbonised was 84 tons 16 cwt., yielding an average make of gas per ton of coal carbonised of 10,800 cu. ft. (House coal had been used for some months past.) The average price of coal per ton was 54s. The materials used in the manufacture of carburetted hydrogen gas were :— £ s. d. Coke, 25 tons 16 cwt., at 20s. per ton ... 25 16 0 Tar, 644 gals., at 2d. per gal......... 5 7 4 Labour ................................ 7 10 0 Total cost ........ 38 13 4 Analysing the above figures, the cost per 1,000 cu. ft. of carburetted hydrogen gas manufactured works out as follows :— d. Coke, 59-51 lb............................ 6-38 Tar, 0-66 gal............................. 1-32 Labour ................................... 1’85 Total cost into holder ....... 9-55 The coke used includes fuel for steam raising, all stand-by charges for coke consumed overnight, during week-ends, and on idle days owing io the gas holders being full. During the month of July the total make of gas was 2,016,700 cu. ft., made up of coal gas 899,500 cu. ft., carburetted hydrogen gas 1,117,200 cu. ft. The coal carbonised was 82 tons 14 cwt., and the average price was 55s. per ton. An analysis of these figures shows even a more satisfactory result than that obtained for the previous month. The average quality of the gas is 500 British thermal units, and the CO2 content 3’21 per cent. The working of the plant is extremely simple and easy, and is at present done by a youth 18 years of age, who has sole charge of it, and whose duty it is to make sufficient carburetted hydrogen gas to mix with the coal gas so as to keep the holders always full. Such a plant is of great comfort to the manager, and saves him an endless amount of trouble and anxiety, for on several occasions the works were completely out of coal, and had to rely on the carburetted hydrogen plant exclu- sively. The plant is so flexible that one cannot fall short. For instance, tar is being used instead of oil for enrichment. For fuel, instead of coke, anthracite coal, house coal, cannel, or any kind of non-caking coal can be used. The idea in the future working of this plant is to use a good coking cannel—such, as Bent, Clydesdale, Quarter, or Allan ton—whieh, in addition to yielding a very rich gas, makes a good hard and intensely hot coke, that should answer very well in the generator. MINING INDUSTRY AND MILITARY SERVICE. At the Little Lever (near Bolton) tribunal last week, Mr. J. H. Hall, military representative, denied the right of a colliery firm to appeal for the manager of their coal depot who was an un at tested man, observing that they had had a chance of appealing for him and had neglected to do so. The representative of the colliery firm said the man was a cripple, in a reserved occupation, over age, and was paralysed from knee to foot, and that was why he had not attested, and they did not appeal for him.—Mr. Hall : Why does he not go before the doctors and get rejected, instead of your coming here?—The case was adjourned. At Milnrow (Lancs), last week, Mr. A. A. Taylor, a colliery agent, aged 31, stated that he had been in business for four years, employed four carters, and carted coal for the Milnrow Gas Company, and also for several local mills. His appeal was supported by the manager of the Gas Company, who said he could not be replaced, and the tribunal granted temporary exemption until the end of the year. At Lytham last w7eek, the local manager of a big coal firm, appealing for a carter, said that 3,000 employees of the firm had joined the Colours, and he thought their appeal deserved consideration. Capt. G. W. Lowcock (military representa- tive) said that if this man were taken he did not suppose it would mean that the business would be closed, and the firm’s representative said that was so, but it would mean transferring business to others whose men were secured. He had already lost one man. A month w7as allowed, and the carter was instructed to go before the medical board, with a view to ascertaining his degree of fitness for the Army. There is great necessity for some uniformity of decision on the part of military tribunals—a fact well illustrated by the decisions of the Cramlington and Seaton Delaval tribunals in colliery cases recently. The Cramlington tribunal, asked to exempt a colliery clerk in the employ of the Cramlington Coal Company, granted conditional exemption, when it was pointed out that the man was engaged in a particular class of work, to undertake which it would be difficult to find a substitute. The Seaton Delaval tribunal, confronted with a similar appeal in respect of a bill clerk in the employ of the local coal company, would grant no relief, although it was pointed out that the already reduced staff was unable to get through the large amount of extra work demanded by the various Government departments, work that could not be done by inexperienced hands. The Sandbach (Cheshire) tribunal has granted conditional exemption to two local coal dealers. At a sitting of the Swinton and Pendlebury tribunal last Wednesday, a representative of Lord Ellesmere appealed for five men in connection with the Walkden yard. Conditional exemption was allowed to three men—a principal timekeeper, an engineer on a steam tug conveying coal barges to the wharves, and a sawyer at the boat repairing yard. The same tribunal granted two months’ exemption to a coal merchant, aged 35 years. At Rochdale last Friday conditional exemption was granted to Mr. H. Talks, aged 31 years, who is in business on his own account as a coal merchant. At Whitehaven tribunal, the first cases dealt with were those of miners with regard to whom the question was whether they had gone into the iron ore mines since the making of the national register. The Ullcoats Mining Com- pany, appealing for four of these men, urged that some came from similar employment, and also that the Government was pressing for ore, and if they were deprived of men it must lessen the output.—The military representative said they might replace them by older men.—In reply to the tribunal it was stated that these men had left their previous employ- ment and come to them to get more money. They were filling and trailing. Anybody could fill and trail. The tribunal gave three men exemption till October 27, and refused the fourth. The Beckermet Mining Company had a number of cases. Some of the men had previously been farm labourers, and had gone into the mines since August 1915, the date of the national registration. — The chairman said the company should apply to the Government for older men and replace these young men.—The representatives of the company agreed that they ought to replace these young men if they could get men who were not too old.—The tribunal refused to exempt five of the men, and exempted the others till October 27. The Ullbank Mining Company appealed for four men— one, 18, a sinker; another, 18, a banker; one 17 years and 11 months, miners’ labourer; and a fourth, 37, weighman.— The tribunal exempted three, who had been previously employed as miners, until October 27, and the weighman was exempted so long as he remained in his present employ- ment. A meeting of miners at Aberdare has made protest against the delay in issuing exemption certificates, a number of them having been seriously inconvenienced by a call to produce certificates to which they are entitled, but which they have not yet received. A special meeting of the executive com- mittee of the Federation in different districts may be called to decide upon what action shall be taken in order to expedite the issue of the certificates. When before the colliery tribunal for the Western district, the representative of Aberpergwm Colliery stated that he had lost 200 men since war began. He made a claim on behalf of a stoker who had only one eye, and was described as practically “unfit”; but the military representative opposed, stating that the man could be replaced by a labourer who was medically unfit.—The tribunal decided to grant the exemption. The chairman of the Carmarthenshire tribunal, with other gentlemen, formed a deputation to the War Office on Saturday with reference to a resolution that had been passed that young men employed in local collieries, as well as in munition factories, should be “ combed out ” and unbadged; and that married men—especially those over 35—should be sent into the factories in their place. The deputation was sympathetic- ally received at the War Office; and afterwards had an interview at the Ministry’ of Munitions. An enquiry is to be made into the circumstances of Carmarthenshire in this respect. Dealing with men on strike at a local colliery, the military representative submitted that as the men were on strike they were not miners. Inasmuch, however, as the strike wras likely to be settled soon, the tribunal decided that it had no right to interfere with disputes. Exemption was granted. One point which apparently was not brought out, is that for two months after miners leave their work they are not liable to military service, and that during such an interval probably the men would obtain work at other pits. Opposition was made to the exemption of a checkweigher, the military representative stating that whilst mining work was w7ork of national importance, checkweighing was not, and that a lame man could do it. Mr. Morgan, who repre- sented the workmen, stated that the Government had “ starred ” checkweighers, and therefore they could not be interfered with. A collier would have to be brought to the surface if the checkweigher went away. The tribunal decided that it had no power to deal with the case. — In another instance, where a checkweigher had signed on since the pass- ing of the Military Service Act, exemption was refused. Rouen Freightage Bureau. — The distribution to other centres of coal transhipped at Bordeaux has for some time past been regulated by the Military Commission on Naviga- tion, which has established at the port a freightage bureau, with a register of craft available for coal transport. Persons desiring to ship coal to river ports below Dizy (near Epernay), Saint-Mammes (at the mouth of the Loing). and Montereau (at the mouth of the Yonne), must apply to the bureau; and once a day the list of applications is called over, in the order , of urgency, to the ship masters present. Those who accept cargoes enter into contracts with the shippers on terms fixed ‘by the Commission. Since the introduction of this system in May last, nearly 700,000 tons of coal per month have been carried up the Lower Seine, as compared with an average of about 300,000 tons per month before the war. Attempts have been made to evade the regulations by chartering boats for up-river ports, and then applying for leave to discharge at Paris; but, except in cases of special circumstances, per- mission to do this is refused, and the cargoes have to be taken to their original destination.