Preheater rotary kiln

Fig. 5. Schematic of the Kennedy van Saun (KVS) patented low pressure drop (LPD) preheater/rotary kiln lime calcining system available in sites...

Pregnancy, exposure to organic solvents during, 23 119 Preheater rotary kiln, 25 53 Preheat trains, 23 221-223 Preinstalled piping system, in fine chemical production, 2 2 428-429 Prekallikrein, 4 86-87 Prekallikrein activator (PKA), 22 145, 146 Pre-liming, in beet juice purification, 23 459... 

The red water was obtd as a result of treatment of crude TNT widi the soln of Na sulfite, known as sellite (See Ref 6, pp 1—2). The resulting red water consisted of aqueous soln of organic nitrogen salts (such as Na dinitrotoluene sulfonate, Na nitrodiazotoluene sulfonate and unattacked alpha TNT) and inorganic salts (such as Na sulfate and Na nitrate). This liquid was concentrated in vacuum evaporators and the resulting "syrup was introduced thru a feed-inlet into upper part of preheated rotary kiln similar to that shown in Fig 13. The syrup,... 

In the early 1980s the preheater rotary kiln size reached a typical capacity of about 3000 (m)tpd. Further increasing of fhe oufpufs were limifed by a span life of fhe brick refractory lining of a rofary kiln shell wifh a diameter more of 6 m. The precalciner/preheater kilns were developed to reach production up to 10,000 (m)tpd and more, by splitting the total fuel input between the main burner and the auxiliary burners of an additional vertical vessel, called precalciner, located in between the rotary kiln section and the suspension preheater. 

Suspension Preheater Rotary Kilns with Riser Duct Firing In order to improve the heat transfer efficiency of a suspension preheafer, some of fhe total heat can be shifted to the riser duct (connection between the kiln and the preheater). This increases the decarbonation degree along with marginally increasing the total production rate, obviously within other process limitations. 

Figure 16.16. A KVS preheater rotary kiln (by courtesy of Svedala Industries Inc.)...

Figure 16.17. Cross-section of a preheater rotary kiln...

SL/RN Process. In the SL/RN process (Fig. 4), sized iron ore, coal, and dolomite are fed to the rotary kiln wherein the coal is gasified and the iron ore is reduced. The endothermic heat of reduction and the sensible energy that is required to heat the reactants is provided by combustion of volatiles and carbon monoxide leaving the bed with air introduced into the free space above the bed. The temperature profile in the kiln is controlled by radial air ports in the preheat zone and axial air ports in the reduction zone. Part of the coal is injected through the centerline of the kiln at the discharge end. The hot reduced iron and char is discharged into an indirect rotary dmm cooler. The cooled product is screened and magnetically separated to remove char and ash. 

The iron carbide process is alow temperature, gas-based, fluidized-bed process. Sized iron oxide fines (0.1—1.0 mm) are preheated in cyclones or a rotary kiln to 500°C and reduced to iron carbide in a single-stage, fluidized-bed reactor system at about 590°C in a process gas consisting primarily of methane, hydrogen, and some carbon monoxide. Reduction time is up to 18 hours owing to the low reduction temperature and slow rate of carburization. The product has the consistency of sand, is very britde, and contains approximately 6% carbon, mostly in the form of Ee C. 

In a rotary kiln, a countercurrent movement of the charge and the gases results in utilization of the heat carried by the hot gases to preheat the charge. 

Lime Long Rotary Kiln Short Rotary Kiln with Stone Preheater... 

In the rotary kiln process, coke is fed to a rotating cylindrical furnace sloped slightly toward the discharge end. Coke flows down the kiln countercurrent to the hot gas flow. Moisture is liberated from the coke in the feed zone, then the coke passes through the combustion zone where VCM is liberated. As coke leaves the kiln, it is discharged to a cooler where it is quenched with water and then cooled with ambient air. Recent designs have incorporated energy efficient features such as air preheat and steam... 

Currently shaft kilns with the most modern technology and rotary kilns with preheaters are mainly used, depending upon the required product properties. 

Heat recovery in rotary kilns with grate preheaters or cyclone preheaters... 

In rotary kilns the raw powder is preheated by the hot flue gases. The use of special preheaters (grate preheaters, cyclone preheaters) can make heat recovery even more efficient. 

The largest rotary kilns with grate preheaters (Lepol furnaces) have a capacity of up to 3()()() t clinker per day and those with cyclone preheaters up to 5000 t per day. In the latest developments the calcining is partly carried out in a preliminary step, in so-called precalciners, which are between the preheater and the rotary tube, to reduce the thermal loading of the rotary tube. The required clinker throughput can then be achieved with smaller rotary tubes or existing plants can increase their capacities. The largest plants with cyclone preheaters produce up to 8000 t/day. 

During the winter of 1991, bulk mustard was drained from preheated (20°C) 1 ton containers into heavy-walled, polyethylene-lined cardboard boxes and allowed to freeze under cool conditions (<0°C). The boxes containing frozen mustard were then placed in sealed metal cargo containers and immediately transported to the incinerator site. The boxes were then off-loaded and processed via the rotary kiln solids feed system. All bulk mustard (3 tonnes) was destroyed in this manner as part of the incinerator test bum program (see below). 

Rotary kilns can also be fitted with a kiln-feed preheater see Figure 6.8, which enables a shorter kiln to be used, approximately one-half the length of a conventional rotary. The exhaust heat is used to preheat the burden entering the kiln thus increasing heat recovery and improving the thermal efficiency of the furnace. 

Figure 6.8 Rotary kiln fitted with a preheater. (Reproduced by permission of J.A.H. Oates and Wiley-VCH.)...

Less preheater plugging in or ring formation in rotary kiln section... 

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