Granulation steam

The economics of the four basic compound fertilizer production processes (bulk blending, compaction granulation, steam/water granulation, and chemical granulation) are compared in terms of (1) required fixed captal investment, (2) conversion cost (not including raw materials), and (3) production cost (conversion cost plus raw material cost). The premises and assumptions used in this evaluation and a discussion of the main economic characteristics of the processes follow. 

Oat lAlso see OATS.I Cleened oats are dried, dehulled, cut into granules, steamed, and tolled Into flakes. Then, the flakes are ground Into flour. A white powder with a bland taste. 

Reduction of A-nitrosomethylaniline. Into a 1 litre round-bottomed flask, fitted with a reflux condenser, place 39 g. of A-nitroso-methylaniline and 75 g. of granulated tin. Add 150 ml. of concentrated hydrochloric acid in portions of 25 ml. (compare Section IV.34) do not add the second portion until the vigorous action produced by the previous portion has subsided, etc. Heat the reaction mixture on a water bath for 45 minutes, and allow to cool. Add cautiously a solution of 135 g. of sodium hydroxide in 175 ml. of water, and steam distil (see Fig. II, 40, 1) collect about 500 ml. of distillate. Saturate the solution with salt, separate the organic layer, extract the aqueous layer with 50 ml. of ether and combine the extract with the organic layer. Dry with anhydrous potassium carbonate, remove the ether on a water bath (compare Fig. II, 13, 4), and distil the residual liquid using an air bath (Fig. II, 5, 3). Collect the pure methylaniline at 193-194° as a colourless liquid. The yield is 23 g. 

Essentially all the ammonium sulfate fertilizer used in the United States is by-product material. By-product from the acid scmbbing of coke oven gas is one source. A larger source is as by-product ammonium sulfate solution from the production of caprolactam (qv) and acrylonitrile, (qv) which are synthetic fiber intermediates. A third but lesser source is from the ammoniation of spent sulfuric acid from other processes. In the recovery of by-product crystals from each of these sources, the crystallization usually is carried out in steam-heated sa turator—crystallizers. Characteristically, crystallizer product is of a particle size about 90% finer than 16 mesh (ca 1 mm dia), which is too small for satisfactory dry blending with granular fertilizer materials. Crystals of this size are suitable, however, as a feed material to mixed fertilizer granulation plants, and this is the main fertilizer outlet for by-product ammonium sulfate. 

A flow sheet of a typical steam granulation plant is shown in Figure 16. Initial steps are cmshing, screening, proportioning, and blending of the dry... 

Fig. 16. Steam granulation process for production of granular mixed fertilizers from dry, pulverized feed materials (7). A granulator producing 12 t/h would...

Steam granulation is practiced in Europe, AustraUa, and elsewhere, chiefly in small plants in which superphosphate, either ordinary or triple, is a primary ingredient. However, for many of the larger operations, superphosphates have been replaced by ammonium phosphates as the principal P2 s source, and granulation procedures involving chemical reactions are employed in Europe as well as in the United States. 

Wet pastes that cannot be granulated or extruded may be predried and preformed on a steam-neated finned drum. Preforming on a finned drum may be desirable also in that some prediying is accomplished. 

The adsorbers are usually built of steel, and may be lagged or left unlagged the horizontal type is shown in Figure 28. The vapor-laden air is fed by the blower into one adsorber which contains a bed of 6- to 8-mesh activated carbon granules 12 to 30 inches thick. The air velocity through the bed is 40 to 90 feet per minute. The carbon particles retain the vapor only the denuded air reaches the exit, and then the exhaust line. The adsorption is allowed to continue until the carbon is saturated, when the vapor-laden air is diverted to the second adsorber, while the first adsorber receives low-pressure steam fed in below the carbon bed. The vapor is reformed and carried out by the steam. The two are condensed and if the solvent is not miscible with water, it may be decanted continuously while the water is run off similarly. After a period which may be approximately 30 or 60 minutes, all the vapor has been removed, the adsorbing power of the charcoal has been restored, and the adsorber is ready to function again, while adsorber No. 2 is steamed in turn. 

Activated carbon or activated charcoal Carbon in the form of charcoal granules, which has an affinity to adsorb many gases and vapors and, in so doing, removes odors. It is manufactured by exposing coal, coconut shells, or peat to steam at 800 to 900 C. 

Prepare a mixtime of 40 ml. of concentrated nitric acid and 40 ml. of concentrated sulphiu-ic acid as detailed in the previous Section. Introduce 50 g. of findy-powdered naphthalene in small quantities at a time and with vigorous shaking maintain the temperatime at 45-50° and cool in ice water if necessary. When all the naphthalene has been added, warm the mixtime on a water bath at 55-60° for 30-40 minutes or until the smell of naphthalene has disappeared. Pour the mixture into 500 ml. of cold water the nitronaphthalene will sink to the bottom. Decant the liquid. Boil the solid cake with 200 ml. of water for 20 minutes and pour the water away. Transfer the oil to a large flask and subject it to steam distillation (Fig. II, 40, 1) any imattacked naphthalene will thus be removed. Pour the warm contents of the flask into a beaker containing a large volume of water which is vigorously stirred. Filter ofiF the granulated a-nitro-naphthalene at the pump, press it well, and recrystallise it from dilute alcohol. The yield of a-nitronaphthalene, m.p. 61°, is 60 g. 

The heat input into the fluidized bed granulation process is controlled with a steam control valve. The settings for the sensors and controls used in the Glatt unit are listed (Table V). 

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