978 THE COLLIERY GUARDIAN. November 8, 1918. CURRENT SCIENCE Steaming Retorts in Gas Manufacture. Mr. F. Shewring (Gc/s World) considers that the best way to economise coal in gas making is to add blue water gas by means of steaming the charges in horizontal retorts. The accepted method, taking the idea from a water gas plant, is to admit the steam so that it passes through the incandescent bed of fuel, allowing a liberal travel for the steam,' or rather blue gas. Some engineers favour the steaming of the free space in the retorts, but in either case it is better to supply the steam as dry as possible, and super- heating the steam should be carried out wherever con- venient. The pipes can be run through the flues of the steam boiler or the waste gas flues of the retort setting. Assuming the steam supply enters the back end of the retort, there are a variety of ways of distributing the steam. The writer has tried a single jet fixed near the level of the bottom of the retort to enable the steam to pass through a thick body of incandescent fuel. In some respects a more efficient method is to run the pipe, with holes drilled therein, around the back end of the retort and about 18 in. on either side. The back end is invariably the hottest place of the retort. Others have had pipes fitted along the sides, laid on the bottom. Consideration must be given as to the damage likely to occur to the pipes fixed in the above-mentioned respective positions during drawing operations. There is a drawback in having the connection at the back of the setting, although in the first two referred to positions damage to the Dipe is not frequent if ordinary care is exercised. F r drilling a hole in the side of the mouthpiece for connecting steam supply, and fixing a drilled pipe the full length of the retort, distribution of steam is attained, and renewal of piping can be carried out with the setting in action. Where steam-raising plant is not available, a water tank (small galvanised or sheet iron tank will do) should be placed on the top of the setting. Connected to this, with a suitable tap in between, should be a double length of wrought iron piping placed in the top waste gas flue of the retort setting, which is generally at the retort house floor level. A connec- tion is made to the steam piping which enters the retort. The advantage of fixing the water supply tank on the top of the bed is to pre-heat the water before gravitating to the pipes in the waste gas flue, and so assisting in the ultimate generation of steam. In some cases provision could be made for raising water to or near boiling point by fixing a water tank in the main flue of the setting. The Pressure Gauge in Pitot Tube Measurement. Mr. E. Anderson (Chemical and Metallurgical Engineering) finds that, in making use of the Ellison or similar differential pressure gauges for the measurement of.small differences of pressure, as with the Pitot tube in the determination of the velocity of gases in stacks and flues, a simple modification of the ordinary connections has been found of very great advantage. The differences of pressure that must be dealt with in gas velocity measurement are ordinarily very small. Thus the velocity pressure corresponding to 12 ft. per sec. at 200 degs Cent, and at sea level is only about 0*02 in., or two of the smallest divisions on the ordi- nary gauge. It is, consequently, very important that the zero reading of the instrument be always known with accuracy. To overcome difficulties usually encountered, the author has devised connections and fittings consisting of two pipe tees and nipples connected with a rubber tube, with a tube clamp to close this connection. The Pitot tube is connected to the upper nipples by means of rubber tubing in the ordinary way as shown. When the zero point is to be read, the tube clamp is opened, equalising the pressure on both sides of the gauge. Of course, this can be done without re- moving the Pitot tube from the stack or flue where the gas velocity is being measured. When the liquid meniscus has come to rest, the zero reading is noted, the tube clamp closed, and the gauge is ready for the regular velocity reading. If the velocity of the gas in the flue or stack is high, it is necessary to close one of the connecting rubber tubes by doubling it up between the fingers while making the zero reading in order to ensure correct results. With these connections the zero point can be deter- mined as often as desired, and accurate results thereby ensured. It is also possible to use regular metal or glass connections fitted with a valve, instead of the rubber tube together with Hoffman clamp. Charging Tar in Gas Producer. A new method of enriching producer gas in use at the Gasteam Plant, Ford City, Ontario (Power) consists in returning tar recovered in the gas cleaning system to the producer for gasification. At this plant are installed two Smith gas producers, each built in six independently controlled sections, and with a total capacity of 100 tons in 24 hours each. The pro- ducer has an incline grate with a heavy clinker bar at the toe of the slope, all of the grate bars being operated by compressed air. Each section is charged mechanically through an air lock at the top of the fuel bed, which latter is normally at a dark cherry- red heat and maintained at a depth of 5 ft. at the top and 7 ft. at the bottom of the slope. Exhaust steam is blown under the grate bars, thermostatically controlled so as to regulate the temperature of the blast at 120 degs. Fahr. ; too cool and dry a blast means hard clinker, while too hot a blast gives CO2 in the gas. The steam is blown into the producer in puffs, two per minute, so that the action some- what simulates that of the Mond. Each producer has its own gas-cleaning system, in which the hot, dirty gas is first scrubbed in a primary cooling tower which reduces its temperature from 1,100 to 120 degs. Fahr. An exhauster, displacing AND TECHNOLOGY. 45 cu. ft. per rotation, delivers the cool gas under 3 lb. pressure to a series of seven tar extractors. These consist of 14 lb. of spun glass-wool made into a diaphragm through which the gas passes at high velocity, leaving behind its tarry matters, which agglomerate into drops and fall into a drain leading to a storage tank. The stored tar is delivered to five sprays above each fuel bed through a 2 in. line, unjacketed, being blown out of the tank by 880 lb. steam. This method is superior to pumping, since the steam blows out the entire system when it is empty, obviating any danger of plugging with solidified tar. About 950 gals, of tar are produced and consumed daily. Little trouble is had if the tai* is sprayed evenly over a compact fuel bed running steadily at a temperature between 1,000 and 1,200 degs. Fahr. Too high a temperature pro- duces fine lamp black which clogs the cleaning system, while if the fuel bed is too cool, the liquid saturates the interstices. The use of the tar reduces the hydrogen and increases the methane content of the gas; it also betters the thermal efficiency of the •odu cei- from 8 to 9 per cent Analyses of typical ises are as follow : — No tar on bed Tar on bed 12 per cent, ash in coal. 4’7 CO., .. 28 per cent, ash in coal. 4’7 12 per cent, ash m coal. 3’8 CO?... On 23’9 ... 0’5 23’3 (•’5 22’1 0’5 H., 15*3 CH4 2-3 B.Th.U. per cu. ft. 161’0 12’7 5’1 179’0 6’2 10’5 208’0 BOOK NOTICES. By-Product Coking. By G. Stanley Cooper. 174 pp. 84 in. x 54 iR- 65 figs. (London : Benn Bros Limited. 8, Bouverie-street, E.C. 4.) 1917. Price 7s. 6d. net. This is a posthumous publication, the author having died in 1916, leaving the concluding chapter unwritten. This gap has been filled by Mr. C. P. Finn, manager of the Hemsworth By-Product Coke Ovens of the South Kirkby, Featherstone and Hemsworth Collieries Limited. The volume covers the whole range of by-product coking. Events have moved rapidly, however, since Chapter I. was written, and the statistics relating to the number of by-product ovens as compared with beehive ovens, both in this country and in the United States, would look very different now from those given. The view is expressed that there was formerly some amount of truth in the notion prevalent in Durham and Yorkshire that certain classes of coal could not be so satisfactorily coked in by-product ovens as by the non-recovery process. But such prejudices, if they still linger, have no longer any foundation provided that suitable adaptations are made in the process adopted. Mr. Cooper has followed a logical course in unfolding his subject, and some preliminary space is naturally given to the quality and preparation of coking coals. The view is held that coking is due to certain resinous constituents of coal which on being heated act. as a binding agent and form the particles of carbon into the coherent mass which is termed coke. It may' be doubted, however, whether in writing these lines the author kept sufficiently in mind the question of ash composition. In treating of the development of by-product coke ovens, a concise summary is given of the •requirements of a good oven and the best way of attain- ing them. A chapter on the practical working of a by-product plant is followed by a description of various tvnes of coke ovens in which the systems of Coppee, Otto, Collin, Huessener, Simon-Carves, Koppers, Simplex, Semet-Solvay, etc., are amply described and illustrated. Amongst regeneratives types, mention is made of the B.M. regenerative coke oven by Messrs. Bagley, Mills and Company. London. It appears that impartial treat- ment is meted out to these more or less rival systems, each, of which has its particular points of advantage’ Auxiliary . machinery, such as oven-charging devices, pushers, discharging plant, blowers and other appliances are duly described. The chapters on tar and ammonia recovery are thoroughly done, within available limits, and the same may.be said for the author’s treatment of benzol recovery, utilisation of surplus coke oven gas, and tar distillation. A brief account of chemical tests concludes that part of the book written by Mr. Stanlev Cooper. The supplementary chapter written by Mr. Finn deals with the future development of the coking industry, in which reference is made to the tendency of Continental prac- tice and the future prospects of the continuous vertical retort, in which great possibilities are foreseen. On the bv-product side, also, the future is full of promise. This chapter is a fitting finale to a most excellent text-book, deserving to take a high place amongst modern works upon this very live subject. Power Plant. By T. Roland Wollaston. 117 pp. 84 in x 54 m. 17 figs. (Manchester: 34. Cross-street, Sherratt and Hughes.) 1918. Price 5s. net. This is a manual upon the installation, upkeep and economical operation of power plant for owners, managers and engineers. The author claims an intimate knowledge of the class of men who are chiefly concerned with this question, and as a practical engineer he disclaims any attempt at cohesion or literary style. .There is no attempt to give an exhaustive description of the various types of power plant , now available, but an effort is made to assist in selecting suitable types, upon the assumption that. each is good in its right place. The author dis- criminates between those industries in which power is the. most expensive raw material involved, and those in which manual labour preponderates, and where the load factor is low, in which case simplicity and first cost of plant are of more importance than high fuel economy. He proceeds to test this theory in various cases. Examining next the available sources of power, mention is made of public electricity supply, hydraulic turbines, steam engines and steam plant, gas' power and oil engines. A short summary of the efficiency of each is given, and the author then proceeds to the work of balancing their relative merit, which is conveniently done in tabular form, although the figures stated are’ to be regarded as examples of method rather than of fact. These tables are highly interesting, and will repay careful examination. The marked superiority of the suction gas plant on the high load factor is here indicated, but on low load factors the conveniences and indirect savings of both the town’s gas engine and the electrical drive may be held to outweigh the small direct saving. The author says that probably the very slight difference shown by these tables will come as a surprise to many who have hitherto regarded fuel cost as the outstanding item of comparison. The next subject treated is power trans- mission, which is considered in the following order, viz., pneumatic, hydraulic, electric, and direct by means of gear wheels, ropes, belts or chains. In connection with these, certain principles are laid down, and hints are given as the result of the author’s experience. In the section on economical operation it is claimed that there should be a close analogy between the methods of running a commercial office and a power house, and specimens of a log book are given, together with hints as to coal tests, CO., recorders, and other aids to economy. Sections on feed water treatment and analysis, oils and lubrication, and a chapter on the analysis of coal and flue gas close the main portion of the volume, to which are added an appendix dealing with water measurement by weirs, and another on condensation water measurement. Upon the whole, a vast amount amount of detailed information is included in this slim-looking but thoroughly well-printed volume. Mill and Cyanide Handbook. By A. W. Allen. 128 pp. 64 in. x 4 in., with diagrams and charts. (London : Charles Griffin and Company.) 1918. Price 6s. net. This is a handbook comprising tables, formulae, flow sheets and report forms, compiled and arranged for the use of metallurgists, mill men. and cyanide operators. Publication was held up for a time on account of the war. but has now been deemed urgent owing to the great increase of late in the milling of both precious and base metal ores. The book contains an enormous amount of detailed information conveyed in tabular form. The treat- ment charts, solution, clean-up and titration charts and report forms will doubtless be appreciated in the handy size in which they are here presented. The glossary is a valuable addition, and the index is a necessary and useful adjunct to a handbook of this description. IRON AND STEEL PRICES. The Ministry of Munitions has announced that the Director of Iron and Steel Contracts was modifying as from October 1, the schedule of iron and steel prices appended to the Order of November 30, 1917. An Order to this effect will be gazetted shortly. The alterations are as follow : — Maximum Pric s and Provisions above referred to. Per ton. £ s. d 1. Steel—slabs, plates, strips and p eces cut from plates suitable for re-rolling ....... 10 7 6 Steel Plates, Sheets and Black Plate, all Open Annealed Produce! in Sheet Mills. 10 tons and upwards of one size and thickness. 2. Above 44 in. thick.......................... 16 10 0 3. yk in. and under to 16 gauge inclusive ..... 16 15 0 4. Under 16 gauge to 20 gauge ..... 17 5 0 5. Under 20 gauge to 24 gauge ..... 17 10 0 6. Under 24 gauge to 26 gauge ..... 18 10 0 Per ton extra. Under 10 tons down to and including 2 tons of one size and one thickness ............... 0 10 0 Under 2 tons dowm to and including 1 ton of one sze and one thickness ................... 0 15 0 Under 1 ton down to and including 5 cwt. of one size and one thickness .................. 0 20 0 Under 5 cwt. of one size ....................... 0 30 0 The maximum prices for defective steel plates, sheets and black plate above men- tioned will be <£1 per ton less than the above. Extra for sizes, etc., as follows :— Per ton. 7. Over 4 ft. wide up to and including 5 ft... 0 10 0 8. Over 5 ft. wide up to and including 6 ft... 0 20 0 9. Reshearing to exact sizes .................... 0 10 0 10. Close annealing ............................. 0 15 0 IL Cold rolling ................................. 0 20 0 12. Hydraulically flattening .................... 0 20 0 13 Mangling...................................... 0 10 0 14. Pickling .................................... 1 0 0 15. Special Welsh Finish or equal, 16 gauge and thinner .................................. 1 10 0 16. Under 250 square inches area................. 1 10 0 Painting one coat both sides ordinary paint — 17. 20 gauge and thicker ........................ 2 0 0 18. 21/24 gauge inclusive ....................... 2 10 0 19. 25 gauge and thinner ........................ 3 10 0 20. Circled, carved, tapered and thin plates to sketch ...............to be subject to arrangement. 21. Bundling.................................. no extra. Extras for Lengths. Exceeding. be Not gdjj exceeding, tn § 01 r£ 13 to 16 gauge inclusive. 0 ® 04 > O B § bn 2 rj bn 2 22. 9 ft .. . 10 ft. ... nil .. .. nil .. . 5s. . .. 10s. 23. JO ft. .. 12 ft. ... nil .. . 5s. .. . 10s. . .. 20s. 24. 12 ft. .. . 14 ft. ... nil .. . 10s. ... 15s. .. 35s. 25. 14 ft. .. . 16 ft. ... 2s.6d... ;. 20s. .. . 25s. . .. 45s. 26. 16 it. .. . 18 ft. ... 5s. .. . 30s. ... 35s. .. .. 60s. 27. 18 ft. .. . 20ft. ... 7s.6d... .. 40s. .. . 45s. . .. 80s. 28. Corrugated sheets no extra. These prices and extras are applicable to all orders for home trade and export. The above mentioned maximum prices and extras do not apply to separate and independent orders involving the sale of less than two tons. All the foregoing prices are net f.o.t. producers’ works. In connection with an article on waterproof plunger grease, which we published recently, we have received samples of two special greases—Universoline and Glando line — from the manufacturers, Sterns Limited. Royal London House, Finsbury-square. London, E.C.