Document G6myMb126M2Oar2pze6waxV

444 The Industrial Chemist, December, 1939 Th A Rotary Kiln Lime Plant Installation at Abadan Sea Shells as a Raw Material THE burning of lime in rotary kilns is a well-established practice, but a recent installation by Edgar Allen & Co. Rotary Kiln A rotating table feeder under the bin extracts the raw Ltd., for the Anglo-Iranian Oil Co. Ltd., at their refinery shells and feeds them at the required rate into the rotary at Abadan is of particular interest on account of the kiln through an inclined pipe. The kiln is a steel tube unusual raw material--sea shells--which the plant is lined with firebricks, and is slightly inclined. It rotates designed to utilize. Abadan is situated on the river slowly on two sets of rollers and bedplates, being driven Shatt-al-Arab, which is the confluent of the Tigris and the by a variable speed motor. The raw shells fed in gravitate Euphrates, about 40 miles north east of the Persian Gulf. slowly to the discharge end as a result of the inclination The plant was installed for the purpose of providing and rotation of the kiln, and the hot combustion gases milk of lime for the oil refinery and also lime for building from the firing equipment, which is fitted at the lower end, purposes. travel in the opposite direction, gradually heating the shells Raw Material to the calcining temperature. The inside of the kiln is fitted with a lining of refractory The sea shells arc deposited in large quantities on the material and an insulating lining between the steel shell shore of the Persian Gulf. They are brought to the works and refractory lining. For European conditions an in barges. The size of the shells varies between about insulation is recommended principally for the purpose of 2 in. and \ in., and even smaller. On a sieving test it was reducing the heat lost by radiation and thus for fuel found that approximately 40 per cent, passed through a economy, but for climates such as at Abadan, where the sieve with | in. square holes. shade temperature in the summer reaches 125 F., it is also The chemical analysis proves that the shells are fairly essential for the. preservation of the plant. pure calcium carbonate. The composition is :-- The waste gases from the kiln pass through a brick dust Per cent. chamber and through a cyclone dust collector, and are Loss on ignition 43-03 exhausted into the atmosphere by an induced draught fan. Silica .. 1-10 The fan is driven by a variable speed motor for the purpose Alumina Ferric oxide .. Lime .. } 0-74 53-00 of adjusting the speed in accordance with the volume of gas to be handled. Magnesia Difference 1-56 0-57 Oil Firing Equipment Total .. .. 100-000 Being located at an oil refinery, the kiln is, of course, fired with oil fuel. This fuel lends itself exceptionally well The shells burnt in a' rotary kiln arc hydrated and the hydrate freed from nibs and impurities by passing it through an air separator. The arrangement of the lime burning plant, the hydrator and the air separator is illustrated in Fig. 1. The raw shells arc filled into a receiving hopper and are lifted by means of an elevator into an overhead storage bin placed over the kiln feeder. The bin is filled every morning in 2 to 3 hours and has sufficient capacity to supply the kiln with raw material for 24 hours. for burning lime because the firing is under close control, no impurity is introduced into the lime, and the calcining temperature can be maintained between very narrow limits. The oil is atomised in the burner by compressed air, which may be considered extravagant, but ensures very thorough atomisation besides being reliable, particularly when attended to by unskilled labour. The oil used has a viscosity of 140 secs. Redwood No. 1 at 100 F. and a specific gravity of 0 913, so that heating is not necessary. The firing equipment comprises the burner, an oil Fig. I--Elevation showing the arrangement of lime-burning plant, hydrator and air separator pump with filters on the suction and delivery sides and an air compressor, control valves and gauges. Ixrfacrmc t Sen r" s- Hydi Th is th< mean for tl the q light; about mach shells hydrr with hydra are re passe: addec in it j washc water The conta be inc if the fore, nibs a The which veyor Milk The about practi kiln p slurry plant, furthe The cent. 1 concre pipes ample water the sir In o is add'