348
VOL. 14, NO. 17
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Gas-Fired Lime Kilns J . B . NEALEY, American G a s A s s o c i a t i o n , 420 Lexington Ave., New York, N . Y, URNING lime with gas has been successfully employed in the lime district south of Birmingham, Ala., in California, and in Ohio for some time past. This fuel fires the kilns of a large lime company in the heart of metropolitan Chicago. This, together with many other industrial applications of gas, was made possible by the adoption of a low summer or off-peak rate by the local public utility in order to improve its load factor. The volume of gas consumed in the summer (April to October, inclusive) was far below the big peak winter demand, and lower rates for Targe-volume summer uses met with a prompt response from industry. One of the first to take advantage of this new low fuel rate was the Stearns Lime and Stone Co., which owns and operates a quarry 27 acres in extent and 255 feet deep in downtown Chicago. Established in 1850, when this spot was outside the city limits, it grew with the city and has furnished lime for a large part of its buildings. In addition to building lime, it produces a special lime that is used nationally by creameries in the neutralization of butter fat. Another product is employed as a base in buffing and polishing compounds used in the metal-plating department of many factories. More exacting requirements being necessary in the making of these products, a better grade and more uniform quality are obtained with lime made with gas. The gas in the Chicago district is a mixture of natural and coke-oven gas and contains 800 B. t. u. per cu. ft. The amount of gas consumed per ton of lime produced averages 6250 cu. ft., but with a full production schedule as little as 5625 cu. ft. per ton has been sufficient. Burning or calcining in this plant is accomplished in six lime kilns, known as the "gradual combustion" or "patent" type, which operate on the "separate feed" principle. The shaft of each is 5.5 X 7.5 X 45 ft. high. Formerly fired with wood, each has two combustion chambers, one on each side, the eyes of which were closed upon conversion. The kiln walls are of limestone blocks, about 4 ft. thick, and are lined with 9 inches of firebrick. Conversion was accomplished by punching six 9 X 9 inch holes through the kiln walls, three on each side just above the combustion chambers, equipping them with burners, and forcing the fuel mixture through them. These gas burners are of a novel design and were specially developed after a number of tests.
B
C o m b u s t i o n Delayed In order to get a comparatively cool flame, and to prevent localized heating and slagging of refractories, combustion is delayed and controlled by the introduction of waste products of combustion, promoting diffusion throughout the charge. This principle is being successfully employed in the glass industry where controlled luminous flames are made to cover the entire area of horizontal glass-melting furnaces. Unless a sufficient volume of gases is passed through the kiln, they will have a tendency to follow up the walls, leaving the core of the lime rock charge comparatively cool while the outside of the charge is overheated. Not only does this action produce a poor quality of product, but a corroding slagging reaction takes place between the acid kiln lining and the basic lime charge. These adverse conditions were produced with a group of gas burners which were tried and discarded. Inasmuch as the kiln charge and kiln conditions constantly vary within wide
the shutter and cap for the admission of gas and this spudded t o allow for maximum capacity a t the maximum gas pressure of 2 lb. per sq. ft. Primary air admitted t*©*».Gajc eew&R
,. -fa£cts*cvrt.A.-rm» PAW
H E R TVMW.L
4 0 U O FUli. CO^euSTiOM
SECTION THROUGH A T Y P I C A L L I M B K I L N INDICATING GAB B U R N E R APPLICATION, U S I N G RECIRCULATED F L U E PRODUCTS
limits, flexibility in firing is vital. The stone mined in this quarry is a dolomite which is approximately 55 per cent calcium carborate and 45 per cent magnesium carbonate. The theoretical calcining or dissociation temperature is approximately 1652° F. Since the penetration of heat into a piece of limestone varies directly as the ratio of the area of the surface to the weight, material ranging from 4 to 8 inches in diameter is used, to ensure uniform calcination. Great care must be exercised not to overburn the small and underburn the large lumps. Controlled L u m i n o u s F l a m e Segregating the factors which make controlled luminous gas flames ideal in lime burning, we have fast radiant heat penetration into the rock itself from flame luminosity or incandescence; even heat penetration throughout the charge because of flame length due to delayed combustion; and prevention of overburning through the comparative coolness of the flame brought about by the introduction of waste products of combustion. In this case a large portion of carbon dioxide gas, which is liberated by the dissociation of the lime, is included. Analyzing the calcining cycle, we can roughly divide the kiln into three zones from top to bottom: (1) preheating and moisture evaporation; (2) supplying heat for dissociation; and (3) cooling. The dissociation of limestone into lime and carbon dioxide gas (CaCO. + heat = CaO -fC0 2 ) is an endothermic reaction. As this reaction is reversible, the carbon dioxide gases must be removed as rapidly as they are generated by means of sufficient draft to prevent recarbonization. The gas burners first tried consisted of 3-inch pipe 30 inches long, open at one end and capped on the other with an adjustable shutter to control the primary air. A short 0.75-inch pipe was passed through
amounted to about 20 per cent and the secondary air entered from the combustion chamber ash-pit. These burners, six in number, were located in the combustion chamber, firing into the bottom of each eye. The gas burners now in use a n these kilns are simply mixing tubes, or 9 X 9 inch holes punched through the kiln walls, as described. These openings are covered by steel burner boxes on the outside of the kiln wall. Gas and air, plus t h e waste products of combustion, etc., enter these boxes through separate openings and are mixed in the 4-ft. burner tunnel through the kiln wall. The gas pressure i s varied between 1 and 2 lb. to suit production conditions. The products of combustion, together with carbon dioxide gas, are removed from two 8-inch holes in the kiln walls in the preheating zone by ducts to the inlet end of a motor-driven fan, and then forced into the burner boxes to mix with the incoming gas. Provision was made for introduction of primary air for combustion into the blower. The fan has a capacity of 1000 c u . ft. of mixture per minute to the 6 burners at 5-inch static pressure; however, this mixture contains only 1 0 per cent of the air needed for combustion and the balance is drawn up through the charge by way of the draw gate. No combustion takes place until the mixture from the burners reaches and intermingles with the secondary air in the charge; in fact, the flames are actually blown away from the kiln walls at this point, which is the area most prone to slagging. A bluish transparent flame, long and bushy, is produced and the ratio of combustion products to gas is usually 6 to 1, although they have been used u p to 10 to 1 when lower dissociation heats were required. Drawing nearly all the combustion air through the burnt line in the cooling zone causes it t o be preheated, thus again increasing the kiln efficiency. In order to augment the heat supply in
SEPTEMBER 10, 1936 t h e center, additional burners were run t o this point b y means of a n arch, primarily installed across t h e kiln shaft a t the burner level a n d opposite t h e burners t o reduce slippage of t h e charge. A tunnel 4.5 inches square was built in below the t o p course of tile from one e n d t o the center of this arch and connected to t w o openings on the opposite ends of t h e arch. A 4-inch pipe was inserted a n d a supply of gas forced through t h e tunnels and openings where it burns in t h e center of the charge. T h e movement of t h e charge was originally aided b y poking it through the eyes of t h e combustion chambers, b u t as these were bricked when t h e kilns were converted to gas, poke holes were punched in t h e walls a t points just above t h e arch. Draft conditions were improved and control over t h e volume of secondary air for combustion was obtained b y placing a sheet metal cover over the kiln t o p . This consists of two sheet-steel covers t h a t can be raised t o a n y position t o control the draft. The most effective draft was found a t 0.02 to 0.03 inch. Applying here t h e efficiency control method used in boiler practice, t h a t of flue gas analysis, t h e most efficient kiln operation w a s determined with a flue gas analyzing 3 0 per cent carbon dioxide and 3 per cent oxygen. T h e new type of firing doubled t h e capacity of each kiln, lowered t h e fuel consumption b y 30 per cent, reduced slagging of t h e refractories, a n d produced a better and more uniform product.
14th Midwest Regional Meeting HE Fourteenth Midwest Regional T SOCIETY will be held in O m a h a next spring.
Meeting of t h e AMERICAN C H E M I C A L
T h e Omaha Section is sure t h a t there will be no heat wave at t h a t time, b u t it is making certain b y scheduling its meetings in air-conditioned rooms a t t h e Paxton Hotel. Since t h e next three national meetings of t h e SOCIETY will b e held in t h e East, Omaha extends a special invitation t o all chemists who will be unable to attend any of the national meetings before 1938 to participate in t h e O m a h a meeting of 1937—Thursday, April 29, t o Saturday, M a y 1. Six divisional groups are contemplated: physical, inorganic a n d analytical; organic; chemical education; agricultural; biological; a n d industrial chemistry. Several symposia are planned. Titles of papers are invited even a t this early date, and will be forwarded t o t h e appropriate chairman if sent t o the general convention secretary, Nicholas Dietz, Jr., School of Medicine, Creighton University, Omaha, Nebr.
Regional Farm Chemurgic Conferences
T
HREE Regional Chemurgic Conferences, covering a wide field of agricultural-industrial crops in the S o u t h and Northwest, have been announced as a p a r t of t h e Farm Chemurgic Council's fall program. T h e first of this series of sectional meetings will be held at Lafayette, La., October 15, 16, a n d 17. I t will be known as t h e Southern Chemurgic Conference. T h e second meeting will b e held during the following week, October 20 and 21, a t Pensacola, Fla., as t h e Gulf Coast Chemurgic Conference. A third conference will be held a t Spokane, Wash., November 12 and 13, under t h e direction of t h e State Planning Councils of four northwestern states.
NEWS EDITION
349
Meeting Calendar American Chemical Society 93RD M E E T I N G . Chapel Hill, N . C , April 12 t o 15, 1937. 94TH MEETING.
MIDWEST
REGIONAL
MEETING.
Omaha, Nebr., April 29 to M a y l , 1937. D E T R O I T SECTION.
H . O. C H U T E
Rochester, N . Y., S e p -
tember 13 to 17, 1937. 9 5 T H M E E T I N G . Dallas, Texas, April 18 t o 2 1 , 1938. 14TH
petroleum. H e also did much work for t h e nickel industry, a n d took o u t m a n y p a t e n t s on electrolytic m e t h o d s a n d on various nickel a n d cobalt compounds. His work also embraced methods of producing alkalies. Although known t o few except t h e older chemists, his life w a s active a n d well spent and of importance t o t h e industry.
September 14, 1936.
" T h e Latest Theories on Polymerization," by F . C. Whitmore. Group meetings with reports from the A. C. S. meeting a t Pittsburgh, September 7 t o 1 1 . Reports from Councilors.
Other Scientific Societies
Wilhelm Gluud
W
ILHELM G L U U D , m a n a g e r of t h e G e -
sellschaft fur Kohlenteehnie, Dortmund, Germany, died August 9 after a short illness. Dr. Gluud h a d been manager of t h e institute since its founding in 1918, a n d h a d done outstanding work on coal.
Carl H a m b u e c h e n
C of t h e Benwood-Linze Co., dealers in radio a n d electrical equipment, died a t ARL H A M B U E C H E N , secretary-treasurer
AMERICAN ASSOCIATION OF T E X T I L E C H E M ISTS AND COLORISTS. Providence, R. I.,
December 4 a n d 5, 1936. AMERICAN INSTITUTE O F CHEMICAL E N G I -
NEERS. Baltimore, Md., November 11 to 13, 1936. AMERICAN O I L C H E M I S T S SOCIETY.
Con-
gress Hotel, Chicago, Ill., October 8 a n d 9, 1936. AMERICAN
PETROLEUM
INSTITUTE,
Chicago, Ill., November 9 t o 12, 1936.
Springfield, Ill., of heart disease July 3 1 . Mr. Hambuechen was born in Germany in 1876 a n d came t o this country in 1881. He graduated from t h e University of Wisconsin with the degrees of B.S. in 1899 and E . E . in 1901. H e became a member of t h e St. Louis Section of t h e AMERICAN CHEMICAL SOCIETY a b o u t 20 y e a r s ago,
when he was in t h e research department AMERICAN PHYSICAL SOCIETY, OPTICAL of t h e Aluminum Ore Co. in E a s t St. SOCIETY O F AMERICA, ACOUSTICAL S O Louis, and h a s been a member ever since CIETY O F AMERICA, SOCIETY O F R H E - with t h e exception of six years spent in OLOGY, AMERICAN ASSOCIATION O F New York. H e was chairman of t h e PHYSICS T E A C H E R S . Joint meeting of local committee when t h e American Electhe five founder societies of the Ameritrochemical Society m e t in St. Louis in can Institute of Phvsics, New York, 1930. N. Y., October 29 t o 31, 1936. AMERICAN P U B L I C H E A L T H ASSOCIATION.
New Orleans, La., October 20 t o 2 3 , 1936. ELECTROCHEMICAL,
SOCIETY,
Niagara
Ernest J. Manfredo
E
RNEST J. M A N F R E D O , for 20 years chem-
ist in the New York C i t y Department of Purchases, was killed a n d his wife was seriously injured on August 24, when his TION, Cleveland, Ohio, October 19 to 2 3 , automobile turned over several times on 1936. the highway near Kimball, Nebr. A tire N A T I O N A L SAFETY CONGRESS AND E X - blowout was blamed. Dr. Manfredo held POSITION, ATLANTIC C I T Y , N . J., Octothe M.A. and P h . D . degrees from Columbia ber 5 to 9, 1936. University, a n d was a member of Phi Beta Falls, N . Y., October 8 to 10, 1936.
N A T I O N A L M E T A L C O N G R E S S AND E X P O S I -
T E C H N I C A L ASSOCIATION O F T H E P U L P AND P A P E R INDUSTRY, F e b r u a r y , 1937.
Necrology H a n s A. Frasch ANS A. FRASCH, a retired chemist of Syracuse, N . Y., 80 years old, died a t H the Hotel Commodore, Washington, D . C , on August 6. H e was t h e brother of t h e renowned Perkin medalist Herman Frasch whose picture adorns the Chemists' Club a n d whose widow contributed t h e funds b y which t h e Frasch Conservatory was built. Although n o t so renowned as his illustrious brother, Hans A. Frasch was a busy chemist through a long life a n d made m a n y inventions in various lines. As early as 1893 his name occurs in t h e Journal of the Society of Chemical Industry as a patentee of sulfonic acids made from petroleum oils. In succeeding years he patented many products made from petroleum sludges, most of which were assigned t o the Grasselii Chemical Co. He belongs distinctly to a past generation, a s the last patent reference to him in Chemical Abstracts is in 1920 for a p a t e n t applied for many years before. During this long active career there are dozens of references to his work on petroleum products as sulfo acids and dyes from
K a p p a a n d of t h e AMERICAN C H E M I C A L
SOCIETY, which he h a d joined in 1920.
Edward Weston DWARD W E S T O N , noted inventor, scientist, a n d electrical engineer, died at his home in Montclair, N . J., August 20. Through t h e Weston Electrical I n strument Co., of Newark, Dr. Weston had made many outstanding contributions t o science. He was a member of a number of scientific organizations, including t h e
E
AMERICAN C H E M I C A L SOCIETY, which he
had joined in 1908.
Prize W i n n e r s i n C h e m i s t r y — Correction has been called t o a n error t h e list of Grasselii Medalists a p OURin attention
pearing on p a g e 330 of t h e N E W S E D I T I O N
for August 20, 1936. The d a t a relative t o the medalists for 1925 a n d 1926 should read a s follows: 1925 E. R. Berry, General Electric C o . . T h e Manufacture a n d U s e of Clear Fused Quartz. 1926 Charles R. D o w n s , W e i s s a n d D o w n s , Inc., C a t a l y t i c Oxidation of Organic C o m pounds in t h e Vapor Phase.
