Method for producing solid, dry, granular, chemical products

Abstract

Granular products are obtained by injecting the appropriate reactants, at least one of which is liquid, solution, slurry, or paste, in an atomized state upwardly into a circulating fluidized bed of growing granules having its cross-section increasing with height, so that material is deposited on the granules (before, during, or after reaction) and any liquid evaporates, the product granules being removed from the top of the bed to keep it level. The reactants may be introduced separately through concentric nozzles, or may be premixed: gases may be introduced at a velocity greater than that of the fluidizing gas (30-100 m. / sec.) or may be mixed with it; and liquids may be injected by means of compressed air. The fluidizing gas may be heated, and is introduced at such a rate that the granules are projected upwards in the central zone to form a jet, and then fall back down the side, larger granules tending to remain on top. Inlet gas temperatures of 280-600 DEG C. are referred to. The exhaust gases are treated to recover dust (which is returned), heat, unreacted gases and gaseous products. The product may be screened to obtain granules 0.5-8 mm. in diameter, and fines recycled. The reactor may be cylindrical with a conical lower end of angle 55-65 degrees, the top of the bed being 20-70 cm. above the top of the cone. The reactions listed are: (1) Ammonium phosphate from dil. H3PO4 and gaseous NH3 (Example 1). (2) Na phosphate from dil. H3PO4 and NaOH. (3) Triplesuperphosphate from dil. H3PO4 and pebble phosphorite (Example 2). (4) (NH4)2SO4 from NH3 and H2SO4. (5) Ammonium sulphonitrate from NH3 and (NH4)2SO4, NH4NO3, HNO3 and / or H3PO4. (6) Na or K carbonate from CO2 and dil. NaOH or KOH. (7) AlF3 from gaseous or aqueous HF and Al(OH)3 slurry. (8) Complex fertilizers from HNO3, H3PO4, NH4NO3, gaseous NH3, and K salts, e.g. K2SO4 or KCl, N / P2O5 / K2O ratios of 16 / 16 / 16, 8 / 24 / 24, 18 / 16 / 32, 11 / 22 / 22 and 12 / 24 / 12 may be obtained (Example 3).

Description

PATINTANWILT HAM ItUHO 3B · NKU KH WAI.!. 41 · F « HNHUF 8β 74 28 AND S6 41 18 TBLK(IXAMIi-AVSOHaIrTI VBOBDAJTATBIfT ~"~* Societa EdisonFor&ogr; Bonaparte 31Mllano. Italy July 20, 1965 Process for producing solid, dry, granular chemical products The invention relates to a method for producing solid, dry, granular chemical products, such as inorganic salts, in particular Fertilizers, directly from the reactants, which are in a gaseous state, solution or suspension. The known methods for producing dry, granular products, especially fertilizers, usually consist of the following: First, the various reactants in a reactor are converted to the desired extent (for example, by increasing or increasing the amount of reactant). less extensive neutralization reactions between an acid or acid mixture and salts and an alkali or a basic salt or by attack of minerals with inorganic acids of different concentrations in an aqueous solution), thereby obtaining a solution, suspension or sludge which is subsequently used in a plant or a group of plants cn is added for granulation and drying. Therefore, three different work steps are available for de- '" had" of which the first iib«rw? e^and ci"fi¥*n»' t lie (chemical reaction) and «ILe "heLiItMi fol<_;·>!'#'<«! ^ BAD ORIQiMAL ~ 2 - Recording processes (granulation and removal of the liquid phase, generally water). The granulation and removal of the liquid phase from the sludge, solution, or suspension obtained by reaction is carried out in The process is carried out in various ways depending on the liquid content and the product in question. The methods generally used are: Granulation of the sludge obtained from the reaction in granules or mixers; if necessary, the addition of fine particles beforehand, in a closed loop. recycled powder or other additives to reduce the liquid content of the sludge, so that moist granules are obtained which are then dried, for example, in a rotary kiln through which a hot gas stream flows. Spraying the product into a solidification tower in a countercurrent flow to cold air, resulting in crystallization and solidification of the sprayed material. The product is then dried before reaching the surface. "Spray drying" (or spray atomization), whereby the sludge with high moisture content is immersed in a stream of hot gas ε breaking down to form a dry, powdery product- oo is dusted, which is further converted into grain form by bees -* must be subjected to actions and procedures (re-wetting, pre-pressing and subsequent drying, etc.)· Furthermore, additional procedures were proposed, which awei äev - 3 - BATH ORIGINAL The aforementioned work steps can be combined into one. For example, it is possible to granulate and dry simultaneously. (fluidized bed granulator, special rotary drums, etc.), or the reaction can be carried out simultaneously with the granulation (granulator- Ammonizer TVA). All these known methods for producing granular products very often exhibit disadvantages. Depending on the method used, difficulties in operation or handling, low flexibility regarding the shape and size of the resulting granules, the exclusive usability of raw materials with low moisture content, the need for considerable recycling of fine products, which makes the plant more cumbersome and increases process costs, auxiliary equipment, considerable operating times, and generally several operating stages and steps can be considered disadvantages. The object of the invention is to create a highly simple, effective, extremely fast, and economical process for producing chemical products, in particular solid, dry fertilizers of uniform particle size, directly from the reactants in a single operating stage. This object is also achieved according to the invention by the fact that the reactants, at least one of which is liquid, are processed by a a fluidized bed consisting of growing grains, whose cross-section increases with increasing height, is continuously and directly fed into a stream that flows upwards just like the vortex gas flow, and that the dry O (O OO The final product consists of grains of the desired medium size and regular shape, achieved by moving the fluidized bed at a constant height. The overflow is removed. The heat required for drying the product and, if necessary, for carrying out the endothermic reactions, is supplied to the eddy gas stream. supplied, which transfers the heat to the fluidized bed through a very high heat exchange» so that the evaporation of the reactants injected liquid phase and, in endothermic processes, the shift of the reaction equilibrium in the desired direction This is ensured. In strongly exothermic reactions, it may be unnecessary to supply additional heat for the evaporation of the water, as the heat supplied by the The heat supplied by the reaction may be sufficient, so that the carrier gas does not require any further heating. According to the inventive method, the finely atomized and intensively mixed reactants injected into the swirling gas stream begin to During simultaneous evaporation of the liquid phase at a very short distance from the injection nozzle, they react with each other and are directed towards the The particles are transported to the surfaces of the upper grains of the fluidized bed, where they adhere in a thin layer as a deposit. These particles are circulated. The guided grains are processed – as will be shown below – in successive stages thanks to the ^ Vortex gas stream covered by thin layers of reactants and / or the end product. The grain size increases continuously, since at* Each complete layer also includes the reaction and evaporation of the liquid phase, generally water, introduced with the reactants. or through the The reaction that was formed is coming to an end. The device for carrying out the method according to the invention is very simple: It essentially consists of • a vertical, preferably cylindrical, tower with a substantially conical base with an opening angle of preferably 55 to 65°. The gases for stirring up the grain bed are supplied from the ground. In the lower part of the conical Bodens is used in an injector that injects the atomized reactants in the same flow direction as the swirling gas. At the upper end of the bed, preferably at the end of the conical part, there is an overflow for removing the raw material supplied to the bed. corresponding dry granular product provided, while the utilized gate (utilised swirl gas, water vapor, not The reacted volatile reaction partners and volatile byproducts are drawn off from the top of the reactor. After these gases have been removed... If necessary, the dust carried along with it is removed by precipitation in a cyclone (which is usually returned to the plant, (in order to form new condensate ion nuclei for the subsequent growing grains), sensible heat and / or the recovered the substances of interest contained therein (unreacted gaseous reagents, volatile reaction products). For example, in the production of ammonium salts, it is possible to use the sensible heat of the exhaust gases as well as the heat contained therein. Ammonia is removed by washing with the solution of the acid used as a reagent. 909851 / U6A win. As is known from the technology of fluidized beds with upwardly increasing cross-section (conical beds), for holding No frames or porous sheets are required for the bed. A suitable flow velocity of the vortex gas is sufficient to... To keep the bed suspended while simultaneously ensuring proper circulation of the bed components. The thin The solid particles covered by the layer of injected atomized material are rapidly carried by the gas stream through the jet-like formation. Transported upwards in the middle of the bed zone, they fall back onto the top of the bed and regularly sink downwards in the ring space around the circumference, where The velocity of the carrier gas is lower. They sink into the narrow cross-section of the cone where the spray nozzle is located, and Then, more layers are thrown in, with the thin layers settling in increasing amounts growing until the desired amount is reached. The grain size has been reached. The grains of the final product are the result of successive periods, each of which consists of the reaction. The process involves the input of components, granulation, and drying. Simultaneously, the particles are sieved. which causes the larger particles to tend to remain on the surface and around the perimeter of the bed, from where they are easily carried away by the overflow. can be withdrawn. The feed systems for introducing the reactants into the reactor vary depending on the type of chemical. Reaction. In neutralization, and whenever reactants react in simple mixing, the reactants must, for example, be introduced in such a way that their - 7 - BATH ORIGINAL Mixing takes place in the reactor. For this purpose, the reactants are fed into the reactor through an injector consisting of at least two concentric nozzles into which they are introduced separately. Alternatively, if one of the reactants is gaseous, it can be introduced into the reactor mixed with the fluidized bed gas stream. If, however, the reaction does not occur under normal conditions by simply mixing the reactants, but only under conditions within the reactor, they can be introduced into the reactor already mixed. The injector introduces the various reactants at the base of the fluidized bed, below the lower cross-section, into the gas stream, which is also introduced at the base. The tip of the injector is shaped in such a way that intensive mixing of the reactants and the reaction takes place at the nozzle outlet. The reaction proceeds in an aerosol phase and completes on the surface of the solid particle bed above it. If a raw material is gaseous, for example ammonia or carbon dioxide, it is preferably fed to the inner nozzle of the injector at a high velocity, greater than that of the swirl gas flow. This ensures atomization and intensive mixing with the other, generally liquid, component (solution, suspension, sludge, or paste) fed through the outer nozzle. 909851 / U64 If no raw material is gaseous, the atomization of the reactants is preferably promoted by the action of compressed air, which is preferably is forced through the outer nozzle. The product drawn off the bed through the overflow can be sieved, and the fine dust below a predetermined size is removed. These dust particles are usually returned to the reactor to grow, with them acting as growth nuclei for the subsequent grains. It is possible to run the operation continuously, and by appropriately adjusting the flow rate and temperature of the With the feed and the vortex gas flow, the particle sizes of the product approach the mesh size of the sieve, so that the recycled Fractions are reduced to a minimum. The addition of new growth nuclei to compensate for the removed grain material is usually, unnecessary, since the new nuclei formed by the abrasion of the particles among themselves or on the reactor walls are completely sufficient. The special feature of the method according to the invention is that the very large specific surface area of ​​the bed allows for a There is a very high exchange between the solid and gaseous phases. This alters the kinetics of the physicochemical processes to a very high degree. Maximum favored. The method according to the invention can be applied to all industrial processes. 909851 / U64 Processes are used where gaseous, solid or liquid reagents, at least one of which is converted into liquid form in the process, are used. The material is in a state, i.e., in the form of a solution, suspension, sludge or paste, and a solid, dry, granular product is to be produced. For example, the process can be applied to the production of Ammonium phosphate from dilute phosphoric acid and gaseous ammonia, Sodium phosphate from dilute phosphoric acid and sodium hydroxide, Potassium metaphosphate from potassium chloride and dilute phosphoric acid, Triple superphosphate from dilute phosphoric acid and phosphorite, Amaonium ulfphate from ammonia and even highly diluted sulfuric acid, Aeonium sulfonate from ammonium sulfate, dilute nitric acid and assonia, or from dilute nitric acid, dilute Sulfuric acid and ammonia or from ammonium nitrate; dilute sulfuric acid and ammonia, wherein the mixture is such The temperature is such that the ammonium nitrate does not decompose. Complex fertilizers of various compositions consisting of nitric acid, phosphoric acid and ammonia, and potassium salts, 909851 / 146A - 10 - Sodium or potassium carbonates from carbon dioxide and dilute sodium or potassium hydroxide solution. The intermediate formation of Bicarbonate formation can also be prevented in the case of an excess of CO2 by operating the bed at a temperature at which Bicarbonate is not stable, Aluminum fluoride from gaseous or water-soluble hydrofluoric acid and aluminum hydroxide, and the like. Depending on the general conditions of implementation of the process according to the invention (i.e., chemical nature, particle size and Dryness of the mixed product, the type of reactants, their liquid content, the quantities of the masses involved, Environmental conditions, etc., can affect the operating conditions (temperature, injection speed of gases and reactants, etc.) in can vary widely: The inlet velocity of the vortex gas depends on the diameter of the system and varies between 30 and 1 / #to. Si· The velocity of the reactants is preferably not kept below the velocity of the circulating gas. The mean exit velocity of the oasis (vortex gas, water vapor and possibly gaseous reaction products) should be •o leg, dafi Not too much solid product should be applied. Therefore, it depends on the type and size of the grains and varies between 1 and 4 m / sec. 909851 / U6 4 - 11 - a The inlet pressure of the !Dräger gas depends on the type of product and the diameter of the system and can reach a value between 500 and 600 OO and more. The initial temperature of the gas depends on the product and must in any case be higher than the dew point of the grass to avoid condensation in the system. The upper edge of the bed is preferably kept slightly above (20 to 70 cm) the cone end of the system so that an upper run can be used. The reactants can be gaseous, liquid or solid, provided that they are injectable and at least one of them is liquid or has a liquid content (solution, suspension, sludge or paste). The final moisture content of the resulting product depends on the type of product itself and, of course, on the desired degree of dryness. The average moisture content is between 0.3 and 0.4 g / cm³, but values ​​below 0.1 g / cm³ can also be achieved upon request. The particle size of the final product can be varied within a wide range, for example, from 0.3 to 8 mm, and preferably from 1 to 4 mm for fertilizers. The inventive process for producing granular dried solids by direct synthesis of the reagents in one step has considerable advantages compared to known processes, of which the following are particularly noteworthy: 909 8 5 1 / UtU - 12 - be led: Elimination or significant reduction of the reaction stage (which occurs in known granulation and drying processes) preceding) and the associated apparatus (reactors, stirrers, etc., which are generally made of stainless steel), The reactor-granulator-dryer can consist of iron insofar as the reactants come into contact with the walls, only after they are in a reacted and dry state on the surface of the particles, in the case of corrosive gases Due to the developing chemical reactions, it is necessary to prevent any condensation of moisture from the exhaust gases by ensuring that all cold areas of the system are insulated. In exothermic reactions, the heat of reaction is fully utilized, as it 'evolves' within the reactor granulator. It is possible to use reagents with any amount of liquid and to carry out reactions using liquid raw materials and to carry out very short reaction times, which usually only occur with concentrated reagents and with long reaction times, since the reactants in the atomized bubble and on the surface of the particles are heated at the expense of the sensible heat of the gases and by the The very high energy and mass exchange in the vortex phase is immediately concentrated. Therefore, the flexibility of the process is very high. considerably. 90 98 51 / 1464 - 13 - Similarly, the very high heat exchange • The drying of the granules is greatly accelerated, so that it happens very quickly. • The thermal efficiency is higher than with conventional drying methods, since even at typically deeper temperatures Products requiring drying temperatures can be salted with very hot gases. This is possible because the reactants and The pest product undergoes very rapid evaporation of the water, causing the grass temperature to drop so low that it is unsuitable for the The end product is not harmful. The system is very simple and requires little space, which considerably simplifies its insulation. Furthermore, it lacks moving parts (except for a blower and the feed pump for the injector), so that they are also very inexpensive and easy to maintain and to regulate and dJi offers the possibility of fully automating them with significant labor savings. The properties of the obtained bodies are excellent in terms of appearance and homogeneity of dimensions, and show from For the same reason, further processing results in a very low tendency to form rods, since only the surface zone is affected by drying. The grain has a greater density without capillaries, which remain in wet-molded grains after drying and are located on the This is due to trapped water migrating from the interior of the grain to the outer surface, resulting in a correspondingly unfavorable... Effect on chemical resistance 909851 / 1404 .-14- Due to the regular particle size distribution and the almost complete absence of large agglomerates, the grinding and screening plants could be combined in Portfall can occur or at least be reduced to a minimum, as a summary sieving is sufficient to remove the items below the desired level. to reuse the fraction resulting from the desired grain size and, if necessary, to reduce the traction resulting from the fraction exceeding the desired grain size. grind. Furthermore, handling and measuring the separated pipe materials is usually much easier than handling these materials. after the reaction (sludge, suspensions, supersaturated solution). The following examples serve the purpose of illustrating the invention idea. from Granular aemonium phosphate is produced from dilute phosphoric acid prepared by a Hass process with 30% P₂O₆ e and gaseous Ammonia produced (example of a reaction between a liquid and a gas). 350 kg of a granular product made from previous The processing originates from γ ... *° &ogr; This creates an airflow with an inlet temperature of 360°C and a flow velocity of 3000 ft / h. The ^ The cone angle is 60°, and the average porosity of the α-bed is 0.5. Banns are drawn through the receiving nozzle of a [unclear - possibly "mounted on the"]. Injector attached to the underside of the apparatus, 660 l / h of diluted phosphoric acid with 30% P2O5UHa is injected through - 15 - At a production operating speed, the apparatus has an output of 500 kg / h of a very homogeneous, dense product with a nitrogen content of 12%, a mineral content of 52%, and a moisture content of 0.3 l. The particle sizes range between 2 and 4 mm. The undersized particles are recycled back into the reactor. The gases leave the reactor at a temperature of 1050°C. The expelled dust particles are separated from the gases using a centrifugal separator and sent back into the reactor. When working under the same conditions and changing the molar ratio ΔE, ΔE, ΔR, ΔO, fertilizers with different concentrations, for example between 11 / 53 and 16 / 4-8, are obtained. When the series of molar ratios approaches the value ΔE, ΔE, ΔR, ΔO, the hourly production rate increases under the same operating conditions due to the increased reaction heat. In this case, scrubbing the exhaust gases with phosphoric acid is provided to recover the ammonia from the gases, which is contained in them in amounts of a few μ, relative to the amount of ammonia used. - '-'¥V 90985 1 / U64 ~-r; ·# - 16 - EXAMPLE 2 Production of Tripelau-per-phoephat Granular iripel superphosphate is produced from dilute phosphoric acid with 30 i» P2OC and granular phosphorite (example of a reaction). between a liquid and a solid). 214 kg / h of granular phosphorite are continuously mixed at low temperatures with 405 l / h of H5PO4 containing 30 l / h of P2Oc. The analysis of the phosphorite was as follows: follows: P2O5 = 33.7 * Grain size distribution: mm > 96.0 * CO2 3.0 * - 0.2 mm &bgr; 89.0 F2 3.8 * - 0.16 mm = 73.0 * SlO2 3.3 - 0.11 mm s 58.0 * R2O3 2.5 * - 0.08 mm = 42.0 CaO = 48.8 * - 0.05 H2O 1.5 * MgO / 0.6 Loss at 4000C = $3.5 The resulting suspension is then immediately conveyed into the granulation reactor via a compressed air nozzle to atomize the previously to favor mixed raw materials. The bed, consisting of approximately 350 kg of granular product, is heated by a hot air stream of 2800°C and a flow velocity of 3000 m / s. Nm^ / h stirred up. The angle of the conical part of the reactor was 60° and the average porosity was approximately 0.5. 909851 / 146A The particles in the fluidized bed have a temperature between 90 and 1000°C. The gases leave the reactor at almost the same temperature. Temperature and carry away the reaction products, such as HF and CO2. The gases pass through a dust cyclone, whereupon the substance they contain is removed. HP is separated before exiting into the atmosphere. At operating speed (after about 2 hours since commissioning), the reactor has a continuous output of 450 kg / h. The final product, whose chemical analysis immediately after sample removal yielded the following values: gjj ' » 49.7 # The grain size distribution- P2O1. Cancellable - 48.8 * distribution of the output- p of the impact lies between P2O5 soluble in H2O = 46.3 ^ 2 ^ 4 ^ P2O5 free = 2.8 Ji Humidity 2.5% When using other types of phosphorite, such as Gtafsa, Casablanca, Florida, ulordania—phosphorite, etc., the same results are obtained. Result regarding reaction yields. BEISPIED 5 Production of a complex fertilizer with F / PgOg / K^O (Example of a reaction between buckets of water, a liquid or mixture of liquids and a solid) 315 l / h K»POÄ with 30 % i\%0P become *oawvfcerl>rociie;* te** 332 kg / h dry«» K2SO4 and 300 kg / h 82 ?U3^#» "M JfH ^ im It mixed. The porridge is ssmilcteet with 5%£ ^A* ÄS* ««f -3ineB. 909851 / U6A " .^ _ BATH ORIGINAL The pH value was brought to 3 and then sprayed through the outer nozzle of the injector attached to the underside of the fluidized bed. The fluidized bed consists of approximately 350 kg of grain particles, which are carried by 3000 l / h of air at 35°C. The cone angle is 60°, and the mean The porosity (intergrain volume) of the bed is approximately 0.5. At the same time, 21.5 kg / h of gaseous HH is blown in through the inner nozzle to promote the atomization of the slurry and to neutralize it to a pH of 5»2. The bed has a temperature of approximately 9°C. The gases leave the reactor at 10°C and are conveyed to the dry separation unit to recover the dusts removed from the bed. The gases are then subjected to wet scrubbing using the same process phosphoric acid to recover the ammonia, which is present in the gas at a concentration of up to a few percent of the input ammonia, and the sensible heat of the gases. At the production speed chain in the operation, 750 kg / h of fertilizer with the properties 16 / 16 / 16, a moisture content below 0.5 µg, and a particle size distribution between 2 and 4 mm is obtained. Q Bas received product can still be stored warm unci Without the use of any anti-caking agents, it remains in the desired state. <*> In a Varlax / ie d.se Verfalmaas, the gcäamio £eir%e component or a part thereof (in this Böif?piel £&agr;&Pgr; &igr; salz) with the »urüokführtea Onterkoxa directly into the ü·-" - 19 BAD OBIOINAL The actuator is fed in and not fed into the other components. By using the same raw materials in different proportions (KCl can also be used as a potassium source), it is possible to obtain other results. to obtain compositions such as 8 / 24 / 24 / » 8 / 16 / 32 / , 11 / 22 / 22, 12 / 24 / 12, etc., where the operating conditions are almost the same. 909851 / 1464

Claims

/ D^ / ING. H. NE< 'GEGENDANK' PATENT ATTORNEY IJ 4 Z 4 Z bHAMBDRU SS · NKUER W ALL 41 · FJtRNRVF 86 7« 28 AND 86 41 IB 80 Sicieta Edieon Foro Bonaparte 31 Milan, Italy, July 20, 1965 Pat claims 1. Method for producing a solid, dry, granular chemical product directly from the starting materials in a single step A working stage characterized in that the starting materials, at least one of which is liquid, are continuously fed into a growing A fluidized bed consisting of granules, the cross-section of which increases with increasing height, in the same direction as the rising vortex gas stream. are injected so that the finely atomized starting materials react densely at the injector outlet. begin and then deposit in a thin layer on the surface of the circulating fluid particles under the influence of the swirling gas strome, wherein the reaction and the evaporation of the liquid phase are completed upon completion of each layer, and that the dry end product is in the form of Grains of the desired medium size and regular shape are removed by an overflow that keeps the fluidized bed at a constant height. becomes.

2. Method according to claim 1, characterized in that the fluidized bed is in a single vertical, preferably cylindrical, Tower containing vortex particles with a conical base and an opening angle of ☐☐☐☐ before-909851 / U6 / * in stages 55 to 65° is generated and that the vortex gas flow and the reactants are fed into the reaction tower at the bottom.

3. Method according to claims 1 and 2, characterized in that the reaction participants are introduced by at least one injector at the lowest ! Ceil of the conical base of the plant is injected into the bed of the growing part at a speed that is at least equal to the The speed of the vortex gas flow is 4. Method according to claim 3, characterized in that the injection of the raw materials is carried out by a compressed gas, such as air, or by a The gaseous reaction partner itself is promoted.

5. Method according to claim 1, characterized in that the dry, granular end product of the desired average particle size is separated by a The overflow is drawn off above the upper end of the fluidized bed, preferably at the end of the conical base. 309851 / UbA