WO2014064239A1

WO2014064239A1 - Method for granulating meltable materials

Info

Publication number: WO2014064239A1
Application number: PCT/EP2013/072366
Authority: WO
Inventors: Axel GOTH; Pascal TRIBOLET
Original assignee: Bertrams Chemieanlagen Ag
Priority date: 2012-10-25
Filing date: 2013-10-25
Publication date: 2014-05-01
Also published as: AT513566B1; KR20150081297A; CN104884154A; CN104884154B; AT513566A1

Abstract

The invention relates to a method for granulating meltable materials, spherical prills (2) being produced from the melted material (3). The melted material (3) is introduced into a spray system with a cup-shaped spray head (12) which rotates about a vertical axis while a spray cage (10) rotates about the longitudinal axis, and the drops are discharged in the radial direction through perforations in the casing of the spray cage (10). The drops fall between the casing of the spray cage (10) and the inner wall of a solidifying tower (11) in the direction of the bottom outlet of the solidifying tower (11). The prills (2) are transported through a gaseous coolant which flows through the solidifying tower (11) in the longitudinal direction. In the process, the outer surface of the prills (2) is cooled to a temperature less than or equal to the solidifying temperature. The rotational speed of the spray cage (10) and the flow speed of the gaseous coolant are limited at the top such that the trajectory of at least a plurality of drops or prills (2) runs within an imaginary enveloping cylindrical casing, the diameter of which is slightly smaller than the diameter of the inner casing of the solidifying tower (11). The prills (2) are further cooled in a heat exchanger (18).

Description

Process for granulating fusible materials

The invention relates to a method for granulating fusible materials, wherein spherical prills are produced from the molten material and transported through a gaseous cooling medium flowing in the longitudinal direction and the outer surface of the spherical prills is cooled to a temperature less than or equal to the solidification temperature, whereupon the spherical prills be further cooled in a heat exchanger. Moreover, the invention relates to a solidification tower for granulating fusible materials, wherein spherical prills are produced from the molten substance, and transported longitudinally and cooled by a gaseous medium flowing through, with an upstream collecting tank for Äztkali, a downstream conveyor belt and heat exchanger for the prills, a conveying device, in particular a vibratory conveying element and a bucket elevator for the prills to a prillsilo and a Steuerbzw. Control device with at least one sensor for detecting at least one of the following measured values such as for the temperature, the volume and the flow velocities of the medium or the air and / or the prills. The granules produced by spraying molten masses become small

Called pearls or prills. To granulate a product from the melt, it is generally sprayed at the top of the solidification tower through a distributor formed as a showerhead, basket or rotating perforated plate. In these devices, the droplets of more or less equal size fall into the tower in which they are cooled by equal or countercurrent air and solidify into prills, which are collected at the foot of the tower and then cooled.

EP1243316A2 discloses a pelletizer for petroleum residues which are subjected to a prilling process in the molten state. In this process, a prilling head with outlet openings rotating about a vertical axis, over which the molten material is thrown radially outward, is used. As a result, the liquid particles of the material thrown outward solidify in a substantially spherical form. The prilling head is disposed within an upright container. The spherical particles fall down and get into a located at the bottom of the container water bath. There is a cooling of the solidified pellets before they are removed from the container in a row.

US2714224A1 discloses a device for granulating chemical substances, in particular fertilizers. In this case, a molten substance is introduced into a screening device or vibrating device. Individual drops fall by gravity through the sieve in a container down and solidify during their fall. At the bottom of the container, the particles collect and are withdrawn. To cool the particles during their fall, cooling air is conveyed through the container in countercurrent to the falling particles.

DE 2409695 describes a method and an apparatus for granulating meltable substances or highly concentrated substances, in particular the production of granules of virtually the same particle size as fertilizers or sodium hydroxide and potassium hydroxide. Disadvantages of this method according to DE 2409695: no uniform Prill formation, no constant temperature distribution in the solidification tower, no simple cleaning and poor recovery of the process in the specification not compliant prills.

The object of the invention is thus to achieve a device and a method with uniform Prillbildung, with a constant temperature distribution in the solidification tower, a simple cleaning of the solidification tower and a good recovery of the prills not according to the specification.

The object is achieved by a method of the type mentioned according to the invention by the following steps by the molten substance is introduced into a spray system with a pot-shaped spray head rotating about a vertical axis, while the spray basket rotates about the longitudinal axis and the droplets through openings in the mantle Sprühkorbes be discharged in the radial direction and fall between the shell of the spray basket and the inner wall of the solidification tower in the direction of the bottom outlet of the solidification tower and the rotational speed of the spray basket and the flow rate of the gaseous cooling medium is limited upwards such that the trajectories of at least a plurality of Droplets or prills within a Run imaginary cylindrical shell sheath whose diameter is slightly smaller than the diameter of the inner shell.

The invention also enables production of KOH prills having a uniform shape and structure. This is also supported by a constant and uniform cooling of the falling out of the spray prills in the counterflow or in DC with the fall direction. Also, in this production process, the non-specification prills are recycled by diluting the dissolved prills with fresh water and returning the solutions completely to the production process. The solidification tower is in the first cleaning step with "wash water", with

KOH / K ₂ CO ₃ contaminated is cleaned and rinsed in a second step with fresh water. The wash water may contain a maximum of 40% by weight KOH / K ₂ CO ₃ .

It is furthermore advantageous if the apertures are circular, oval, polygonal or slit-shaped, whereby the discharge of the drops to the desired volumes can be easily adapted.

Furthermore, it can also be provided that the walls of the jacket of the rotating spray basket are produced with openings with an area of a minimum of 0.007 mm. This results in prills of the desired shape and size.

But it is also possible that the walls of the shell of the rotating spray basket with

Breakthroughs are made with a maximum area of 3.2mm. This results in prills of the desired shape and size.

In a preferred embodiment in the production of KOH prills from a starting material having a KOH concentration of greater than 85%, in particular with a KOH concentration between 90% and 95%, the area of the openings in the shell of the

Spray basket between 0.007mm 2 and 4.53mm 2, preferably between 0.032mm 2 and 3.2mm. This not only prills desired size can be made, but also the solidification process is improved after leaving the spray head, since the preferred size of the apertures an optimal relationship between the surface chip tion and the other mass forces acting on the droplets, which leads to an optimally spherical shape of the resulting prills.

According to a further procedure, it is provided that the rotational speed is controlled or regulated in such a way that, depending on the supplied mass of the melted substance, the diameter of the spray head and the discharged volume of the droplets in a predeterminable unit of time, an equilibrium between the mass of the molten substance and the mass of droplets is achieved. As a result, an optimization of the production process is achieved and also solved in that the rotating spray has revolutions of a maximum of 1500 revolutions per minute. This also allows a uniform size and shape of the prills.

It also proves to be advantageous if the rotational speed of the spray head with greater than 200 revolutions / minute is limited downwards. From this number of revolutions prills of uniform shape and size are produced.

Further, it is advantageous that the trajectories of the majority of the droplets have a distance of at least 0.1 mm from the shell of the solidification tower. This prevents the prills from having their outer surface cooled at least below the solidification point, from coming into contact with the wall of the solidification tower, and thus from being unable to adhere or stick there. This additionally increases the duration of use of the Storming Storm as the number of washings can be reduced.

In the course of the process, however, it is also expedient if the outer diameter of the spray basket in relation to the inner diameter of the shell of the solidification tower between see 1 to 20 to 1 set to 200, whereby prills can be produced continuously with uniform shape and size.

In a preferred embodiment, in the production of KOH prills from a starting material having a KOH concentration of greater than 85%, in particular with a KOH concentration between 90% and 95%, the outer diameter of the spray basket in

Ratio to the inner diameter of the shell of the solidification tower between 1 to 20 to 1 to 50. It has been found that this measure is optimal for the solidification process of KOH droplets after leaving the spray basket and the properties of KOH, especially density and viscosity optimally takes into account.

In a particularly preferred embodiment, which relates to the preparation of KOH prills from a starting material having a KOH concentration of greater than 85%, in particular having a KOH concentration between 90% and 95%, the following process parameters are used: At temperatures between 200 and 350 ° C and at concentrations between 90% and 95%, KOH has a density between 1750 and 1850 kg / m and a viscosity between 2.5 and 3.5 mPa.s. In addition to these conditions, the area of the holes in the spray basket shell (hole size) is between 0.007mm 2 and 3.2mm 2 and the spray basket speed is between 100 and 1000 revolutions / minute. As a result, sufficiently small KOH prills can be made that will cool quickly and become firm and stable. After a further, advantageous method step, it is provided that the speed of the

Sprühkorbes device via a drive steplessly regulated by means of a control device. As a result of this rapid regulation or control of the spray basket, a rapid readjustment can take place with changing temperatures of the etching crystal, so that the volume of the droplets ejected by the spray basket can be maintained with relatively small tolerances over a longer service life.

Furthermore, it is also possible that the speed of the spray basket is controlled or regulated as a function of the supplied mass of the molten substance and / or the viscosity of this mass. This produces prills of uniform shape and size.

A rapid adjustment of the volume of the droplets dispensed can also be promoted by the fact that with a change in the viscosity of the molten substance, the speed of the spray basket is changed in the same direction.

If the mass of the supplied, molten substance is changed, it is further advantageous if the speed of the spray basket is changed in the same direction. Thus, suitably the size and shape of the prills can be kept stable. According to a further advantageous procedure, an air duct is carried out in cocurrent with the direction of fall of the prills in the solidification tower controlled and uniform cooling of the falling prills. In various applications, however, it may also be expedient to proceed in such a way that an air flow in countercurrent with the direction of fall of the prills in the solidification storm is led. There is a controlled and uniform cooling of the falling prills.

It is advantageous to control and regulate the amount or the temperature of the gaseous medium, preferably formed by air, when it is guided in cocurrent with the direction of movement of the prills in the solidification tower, as a function of the temperature of the medium in the region of the medium outlet, by increasing the temperature the amount of medium supplied increases and / or its temperature is reduced.

This results in a controlled and uniform cooling of the falling prills.

Advantageously, a control and regulation of the amount or temperature of the gaseous medium preferably formed by air in the guide in countercurrent to the direction of movement of the prills in the solidification tower, depending on the temperature of the medium or the air in the region of the medium outlet is regulated by at increasing temperature increases the amount of the supplied medium or the air and / or its temperature is reduced. This results in a controlled and uniform cooling of the falling prills.

However, it is also possible to proceed in an advantageous manner such that the medium or the air for circulating the spherical prills is circulated in a closed system. This results in independence from the ambient air.

However, it is also expedient if the prills are precipitated with size and / or shape and / or weight deviating from the product specification and / or melting with high proportions of nickel or nickel oxide formed during the prill production process. This results in prills with high purity. It is also advantageous if the excreted prills dissolved, processed, possibly cleaned and again be introduced as Ätzkali in the production process. As a result, material that has been lost during the production process, can be used again.

However, an advantageous procedure of the method can also be achieved if the lye-contacting parts of the spray basket, the deflection point and the collecting container are overlaid with nitrogen to contact with oxygen and prills adhering to the surface is not sufficiently cooled are to be avoided.

Advantageously, the nitrogen addition may be continuous or periodic to avoid contact with oxygen.

Advantageously, a procedure in which the solidification is stormy subjected to a cleaning and the wash water is pumped from the wash water tank in the upper part of the same solidification tower and the funnel-shaped outlet and the walls of the solidification tower with wash water and then washed with fresh water. The washing water is treated again and can then be used again in the washing water circuit. Likewise the fresh water. There is a high degree of utilization of the washing water and the fresh water and thus a lower water consumption than in conventional systems.

It is advantageous in the process if wash water up to a concentration of less than or equal to 40% KOH / K ₂ CO _{3 is used} for rinsing and is regenerated again in order to be used again for rinsing. A long service life of the system can be conveniently achieved by the sprayer and the spray head are removed for cleaning from the solidification tower, heated for several hours in a steam bath at a maximum of 200 ° C and then preheated to a maximum of 400 ° C and the spray and the During the washing process, outside the solidification implosion, the second, already heated, spray basket is installed in the place of the soiling, in order to take the solidification tower out of operation for as short a time as possible. It is expedient if the cleaning process takes place after a defined degree of soiling or periodically. This can ensure that the solidification tower is as short as possible out of service. A further method step is advantageous after the inner surface of the funnel-shaped outlet of the solidification storm is heated by an electrical heat tracing. This prevents the caking of hot prills on the inner surface and thus the clogging of the outlet funnel. In the process, it is also advantageous if the inner surface of the outlet hopper to a maximum temperature of 180 ° C, preferably to a maximum temperature of 100 ° C, heated. This prevents the caking of hot prills on the inner surface and thus the clogging of the outlet funnel. The object of the invention is also achieved independently with a device of the type mentioned in that in the solidification storms a feeder line for the molten material in a spray system opens, which has a cup-shaped spray head, which has a substantially cylindrical spray with a vertical longitudinal axis comprises and the spray head is rotatably mounted about a longitudinal axis parallel to the axis of rotation and connected to a rotary drive and the jacket of the spray basket is formed with a plurality of distributed over the surface openings for discharging droplets of the molten substance in the radial direction.

An embodiment in which the openings in the spray basket are circular, oval, polygonal or slot-shaped is advantageous, as a result of which prills with different shapes can be produced.

However, a suitable use of the method can also be achieved if the openings in the jacket of the rotating spray basket are formed with a maximum area of 0.007 mm - 3.2 mm. This results in prills of the desired shape and size.

According to an advantageous development it is provided that the outer diameter of the spray basket in relation to the inner diameter of the shell of the solidification tower between is 1 to 20 to 1 to 200. The advantage here is that, depending on the extruding mass and the amount of prills to be produced a suitable mass of caustic potash is in the spray and thus the highest possible uniformity of the temperature is achieved, whereby the size and shape of the prills in each case at different Requirements can be optimally predetermined.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

1 shows a process diagram of a plant for the production of KOH prills in a highly simplified, schematic representation;

Fig. 2 is a greatly simplified and schematic circuit diagram of the control and regulating device of the system of Fig. 1;

3 shows a spray head of the system shown in Figure 1 in side view with the associated drive system in a highly simplified, schematic representation ..;

Fig. 4 is a spray basket of the spray head shown in Figure 2 on a larger scale partially cut with arranged in a part of the cylindrical shell of the spray basket openings.

5 shows a process diagram of a plant for the production of KOH prills in a highly simplified, schematic representation.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the position information selected in the description, such as top, bottom, side, etc. related to the immediately described, as well as illustrated figure and are to be transferred to a new position analogously to the new situation. Furthermore, individual features or combinations of features may also be distinguished from the differences shown and described. represent exemplary embodiments of their own, inventive or inventive solutions.

All information on value ranges in objective description should be understood to include any and all subsections thereof. For example, the indication 1 to 10 should be understood to include all sub-ranges, starting from the lower limit 1 and the upper limit 10, i. all subregions begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

The embodiments show possible embodiments of the process using the example of obtaining KOH prills, it being noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments are possible with each other and this variation possibility due the doctrine of technical action by objective invention in the skill of those working in this technical field is the expert. So are all conceivable embodiments, which are possible by combinations of individual details of the illustrated and described embodiment variant, includes the scope of protection.

FIG. 1 shows an optionally independent embodiment of the process for obtaining KOH prills, wherein the same reference numerals or component designations are again used for the same parts as in all figures. To avoid unnecessary repetition in subsequent drawings, reference is made to the detailed description in the preceding figures.

For the sake of order, it should finally be pointed out that, for a better understanding of the method, these or their components have been shown in part to be out of scale and / or enlarged and / or reduced in size.

The task underlying the independent inventive solutions can be taken from the description. FIG. 1 shows a plant 1 with which KOH prills 2 are produced from concentrated caustic potash.

For this purpose, the liquid Ätzkali 3 is supplied via a line 4 and a deflection point 5 and a subsequent line 6 to a collecting container 7. In the region of the deflection point 5, it is additionally possible to provide a heat exchanger 8 with which the caustic potash is heated to a temperature of less than or equal to 400.degree. For this purpose, the heat exchanger via the schematically indicated lines with a hot medium, for example steam, heated. Instead of the supply of the Ätzkalis 3 shown in Fig. 1 from above via the line 6 by utilizing the force of gravity, it is also conceivable, a line from below, e.g. from the height of the foot of the freezing tower, to lead upwards. The promotion of the meltable substance 3 to the upper part of the tower takes over in this case arranged in this line pump, which also ensures a continuous and controllable supply of the starting material for the prilling process. For example, the line coming from below could pass directly into the line 9 shown in FIG. 1, omitting a collecting container 7 or opening into it.

The heated caustic potash 3 is then fed via a line 9 into a spray basket 10 of a spray head 12 arranged within a solidification tower 11.

The function of this spray head which can be set into rotation via a drive device, for example an electric motor, will be explained below with reference to FIG. 2. The drops of the concentrated caustic potash discharged via the spray head are cooled in the interior of the solidification tower 11, in which at least the outer surface is cooled below the solidification temperature of the liquid caustic potash and so-called spherical, in particular spherical, KOH prills 2 are formed. The cooling of the drops to form the KOH prills 2 takes place in the present exemplary embodiment by air in the conveying device 13, for example a blower or a compressor for a gaseous medium, preferably air, in the top-side, upper region of the solidification tower 11 via a line 14 is supplied, flows through them the solidification storms 11 in the vertical direction and in the direction of a bottom outlet. The airflow is used to cool the prills 2.

In an alternative embodiment, which is shown in FIG. 5, the gaseous medium is sucked by means of negative pressure through the solidification storm 11. A fan 55 generates in a vacuum container 54 a preferably controllable negative pressure. Via line 53 gaseous medium from the solidification tower 11 is sucked. Via at least one inlet 52, preferably via a plurality of inlets, the gaseous medium in an upper region passes into the solidification 11. As a result, a cooling flow is likewise produced parallel to the direction of the falling prills 2.

The prills 2 solidified at least in the region of the outer surface are fed to a conveying device, in particular a conveyor belt 17, via a line 16 which adjoins the bottom-side outlet 15 of the solidification storm 11. From this they are transported to a heat exchanger 18 and further cooled in this during transport. For this purpose, the heat exchanger 18 can be flowed through the lines 19, for example, with a gaseous or liquid cooling medium.

In the heat exchanger 18, the prills 2 are cooled to a maximum temperature of 80 ° C., preferably to a maximum temperature of 70 ° C., and fed via a subsequent vibratory conveying element 20 to a conveying device 21, for example a cup conveyor, with which the prills be deposited in a prillsilo 22.

The inner surfaces of the deflection point 5 and / or the collecting container 7 and / or the solidification tower 11 and / or spray basket 10 can be flushed via lines schematically indicated with nitrogen to avoid contact with oxygen. Furthermore, it is advantageous if, in the region of the bottom-side outlet 15, a heating device 23 is arranged, for example, the particular funnel-shaped outlet 15 to a temperature between 50 ° C and 180 ° C, preferably between 50 ° C and 150 ° C, particularly preferred not more than 150 ° C, most preferably at most 100 ° C, heated or held at this temperature. Since the caustic potash 3 and the prills 2 are very hygroscopic, it is advantageous if the entire plant 1, in particular those lines and spaces in which the caustic potash 3 and the prills 2 are produced, cooled, conveyed and deposited with dry gas, especially dry air, or even a noble gas are superimposed.

For cleaning the solidification tower 11, a washing water tank 24 is furthermore arranged. This wash water tank 24 is connected to the bottom outlet 15 of the solidification tower 11 via a connecting line 25 and, on the other hand, wash water is supplied via this connecting line via a feed pump 26 into the cover-side inlet of the solidification tower 11.

For the control and / or regulation of the system 1, a control or regulating device 28 is shown schematically, which can be connected to additional memories 29 and other computers and data measurement displays and receivers. The control or regulating device 28 is, for example via a line 30 with a sensor 32 for measuring the

Air temperature in the region of the bottom outlet 15 and / or via a line 31 with a sensor 34, preferably for measuring the flow rate of the cooling medium inside the solidification tower 11, in particular the flow velocity of the air, via a line 30 with a sensor 32 for measuring the temperature at least the surface temperature of the prills 2, for example via a non-contact infrared scanner or the like. Likewise, additional sensors 35, 37, and 38 may be connected to the controller 28 via conduits 33 and 39.

All lines which are connected to the control or regulation device 28, regardless of whether these are lines to the sensors, 32, 34 to 38 or lines to the drives of the spray head 12 of the conveyor of the conveyor belt 17 of the vibratory conveyor 20 or conveying device 21 can also be formed by bus lines or a bus system, as is known from the prior art for such control devices 28 for the control expert working in this field. The same applies to a drive motor 40 for the spray head 12th

FIG. 2 again shows the circuit diagram of the control and regulating device 28 with the associated sensor 28 for detecting the air temperature for cooling the spherical prills, the sensor Sor 32 for detecting the volume and the flow rate of the air, the sensor 32 for determining the temperature of the prills 2 in the funnel-shaped outlet 9 of the solidification tower shown. The temperatures are determined by means of thermography, ie the temperature measurement of the prills 2 is detected contactless preferably areally and displayed on the basis of the temperature determination with heat-sensitive sensors 34 to 38. The data are then eg in a microprocessor 28, the central control and regulating device 28th in which all components of a processor are combined on a microchip, collected, and evaluated by the processor unit and can alternatively be provided in the memory 29 for evaluation.

In Fig. 3, the spray head 12 and the associated drive motor 40 is shown on a larger scale.

The drive motor 40 is connected via a coupling and a drive shaft 41 to the spray basket 10, so that it can be rotated about the longitudinal axis 42, which is preferably also identical to the longitudinal axis of the drive shaft 41 in rotation.

The spray basket 10 is schematically indicated here in dotted lines. In the region of the drive or of the drive motor 40 for the spray basket 10, supply lines or feed devices 43, 44 are provided. Thus, the melted Ätzkali 3 is supplied through the line or feeding device 43 so that it can enter via an outlet 45 into the interior of the spray basket 10. Nitrogen can be supplied to the interior of the spray basket 10 via the outlet 46 via the feed line or feed device 44).

The spray basket 10 shown in Fig. 4 on a larger scale is rotatably connected to the drive shaft 41 and thus rotates about the longitudinal axis 42. The cylindrical shell of the spray basket 10 is provided with a distributed over this coat plurality of openings 47, of which only a few examples Fig. 4 are shown provided. The passage cross section of these apertures 47 is dimensioned such that depending on the speed of the spray basket 10 and the mass of the supplied, molten Ätzkali 3 drops can pass with a predeterminable volume through the openings 47 of a cylindrical shell 48 of the spray basket 10. In FIG. 4, apertures 47 of the jacket 48 of the spray basket 10 with different shapes are exemplified, such as elliptical openings 49, round openings 50 and angular openings 51.

The rotation of the spray basket 10, the small droplets are thrown into the interior of the solidification tower, where they solidify by cooling and prills 2, in this case KOH prills. The inventive method for producing these prills 2 from the liquefied Ätzkali 3 will now be explained in more detail below with reference to the system 1 shown in FIGS. 1 to 4.

The KOH prills process is divided into four steps - Preparation of KOH prills - Treatment of KOH prills - Cleaning of the solidification tower - Re-provision of non-compliant prills to obtain KOH prills.

To produce the KOH prills 2, liquid caustic potash 3 is concentrated (less than or equal to 95% by weight) via the lines 4 and 6 to a deflection point 5 having a temperature of less than or equal to 400 ° C. into the collecting container 7 and from there via the line 9 into the rotating spray basket 10 with the spray head 12 which storm in the solidification 11 is arranged. The caustic potash flows through the dead weight through the deflection point 5 into the collecting container 7. However, it is also possible not to supply the melt to the spray basket 10 by gravity, but to pump it into the spray basket by means of a pump.

The openings 47 in the jacket or the side walls of the spray basket 5 have a diameter or cross-section of at most 1 mm and is discharged through the forces exerted on the Ätzkali by the rotation of the spray basket 10 centrifugal drops through the apertures 47 into the solidification tower 11. By varying the shape of the apertures 47, prills with circular, oval, polygonal, slot-shaped and other shapes can be created. The openings 47 in the walls of the jacket 48 of the rotating spray basket can be made with an area of 0.007 mm 2 - 3.2 mm 2. The rotational speed of the spray basket 10 is controlled in dependence of the supplied mass of Ätzkali 3, the diameter of the spray head 12 and the volume of the resulting droplets in a predetermined unit of time. The rotational speed of the spray head 12 is between 200 to 1500 revolutions / minute and the speed of the

Sprühkorbes 10 can be steplessly controlled by a drive device by means of a control device but the speed of the spray 10 can also be determined in addition to or instead of the mass of the supplied Ätzkali 3 and / or the viscosity of Ätzkali 3.

It is advantageous here if the rotational speed of the spray head 12 or of the spray basket 10 is designed as a function of the abovementioned physical values of the medium or the rotational speed and the like such that the trajectory of the individual drops is at a distance from the inner wall of the jacket of the solidification tower 11 and at least have a distance of 0.1 mm from the inner wall of the solidification tower.

Drops of Ätzkali are ejected by the rotation of the spray basket 10 through the openings 47 from the spray 10. The discharged drops 2 are cooled with a gas stream, in particular ambient air or with noble gases in the solidification tower, crystallize while they fall in the solidification tower down. They are through the funnel-shaped end of the spray tower, which is provided with a heater 23, at a temperature between 50 ° C - 180 ° C, preferably between 110 ° C - 180 ° C, discharged.

The cooling air or the gas can be conducted in cocurrent with the falling prills 2. But it can also be a cooling and crystallization of the prills 2 with gas or air, which runs in countercurrent, take place. The prills 2 fall from the solidification storm 11 via the line 16 on a conveyor belt 17 and are transported to the heat exchanger 18.

The heated after cooling the prills 2 air is removed via a ring collector which is connected to an exhaust fan on the scrubbing tower from the solidification tower 11. Due to the air supply and removal, a constant temperature, which as such may also vary. can be generated in the stagnation storm. As a result, unwanted water absorption from the resulting prills can be avoided. The used air is washed and returned to the atmosphere. The wash water is discharged into the wash water tank 24 via an overflow.

Is used as a cooling medium for the spherical prills 2 ordinary ambient air, it is fed into the solidification tower, then, after the air has left the solidification tower, washed and filtered and discharged back into the environment.

The cooling and crystallization of the prills with the aid of air or another gaseous medium can also be carried out in a closed system in which the air or gaseous medium is cleaned and circulated. For the production of spherical prills 2, it is also premature to adjust the ratio of the outer diameter of the spray basket to the inner diameter of the jacket. Preferably good results can be obtained if the ratio 1 to 20 to 1 to 200 is set. Also crucial to the preparation of the spherical prills is the mass and viscosity of the caustic potash 3 relative to the speed of the spray basket, i. If the mass or the viscosity is increased, it is advantageous to increase the speed of the spray basket 10. If the mass or viscosity drops, it is advantageous to reduce the speed of the spray basket.

In the production of KOH prills from a starting material with a KOH concentration of greater than 85%, in particular with a KOH concentration between 90% and 95%, preferably the area of the openings in the shell of the spray between

0.007mm2 and 4.53mm 2, preferably between 0.032mm 2 and 3.2mm 2. This not only Prills desired size can be made, but also the solidification process after leaving the spray head is improved, since the preferred size of the apertures an optimal ratio between the surface tension and the other acting on the droplets mass forces is achieved, which leads to an optimally spherical shape of the resulting prills. Also preferred in the production of KOH prills from a starting material having a KOH concentration of greater than 85%, in particular with a KOH concentration between 90% and 95%, the outer diameter of the spray basket in relation to the inner diameter of the shell of the solidification tower between 1 to 20 to 1 to 50 selected. It has been shown that this measure is optimal for the solidification process of KOH droplets after leaving the Sprühkorbes and optimally takes into account the properties of KOH, in particular density and viscosity.

In a particularly preferred embodiment, which relates to the preparation of KOH prills from a starting material having a KOH concentration of greater than 85%, in particular having a KOH concentration between 90% and 95%, the following process parameters are used: At temperatures between 200 and 350 ° C and at concentrations between 90% and 95% KOH has a density between 1750 and 1850 kg / m3 and a viscosity between 2.5 and 3.5 mPa.s. In addition to these conditions, the area of the

Breakthroughs in the shell of the spray basket (hole size) between 0.007mm 2 and 3.2mm 2 and the spray basket speed is between 100 and 1000 revolutions / minute.

As a result, sufficiently small KOH prills can be made that will cool quickly and become firm and stable.

In the heat exchanger 18, the prills are cooled in a rotating cylinder to a temperature of less than or equal to 80 ° C., preferably less than or equal to 50 ° C. The air supply to the heat exchanger 18 via the lines 19. From the heat exchanger 18, the prills are conveyed via a vibrating conveyor 20 and a conveyor 21 in the prill silo 22. The caustic potash also introduces interfering nickel residues into the solidification tower, but especially into the spray basket 10, which block the openings 47 of the spray basket 10. So that the spraying process only has to be interrupted for a short time, two spray baskets 10 are used - that is, the spray basket, which has been soiled with nickel, is manually replaced with a clean spray basket, cleaned and can then be used again cleanly. To clean the sprayer it is brought out with the spray head from the solidification storm, disassembled from the spray head, heated for several hours in a steam bath at 200 ° C, then preheated to a maximum of 400 ° C and the spray basket 10 is mounted again at the next cleaning process to the spray head in which the second spray basket has just been dismantled and introduced into the solidification tower 11. So only the sprayer must be exchanged, while the spray head is only briefly disconnected from the production process. The cleaning process is carried out according to a defined degree of contamination. The cleaning process can also be carried out periodically. In order to free the plant 1 of residues, washing water is pumped out of the washing water tank 24 by means of the pump 26 in the upper part of the solidification tower 11, especially for cleaning the solidification tower 11. The funnel-shaped outlet with the heating device 23 and the walls of the solidification tower are washed with washing water and then with cold water. The wash water is used to a concentration of less than or equal to 40% KOH / K ₂ CO ₃ and then subjected to a neutralization reaction.

The heat exchanger 18 is also cleaned with washing water, the washing water collected and pumped into the washing water tank 24.

Reference list

Appendix 40 Drive motor

Prills 41 drive shaft

Caustic potash 42 longitudinal axis

Line 43 feeder

Deflection point 44 feed device

Line 45 outlet

Collection tank 46 outlet

Heat exchanger 47 Breakthrough

Cable 48 sheath

Spray Basket 49 Elliptical Breakthroughs

Stiffening storms 50 round breakthroughs

Spray head 51 Square openings

Blower 52 inlet s

Line 53 line

Outlet 54 vacuum tank

55 fan

management

conveyor belt

heat exchangers

management

Vibration conveyor element

conveyor

Prillsilo

heater

Wash water tank

Connection line

feed pump

management

microprocessor

Storage

management

sensor

management

sensor

management

Claims

Patent claims

1. A method for granulating fusible materials, wherein spherical prills (2) are produced from the molten substance (3) and transported through a gaseous cooling medium flowing in the longitudinal direction of a stagnation tower (11) and the outer surface of the spherical prills (2) a temperature less than or equal to the solidification temperature is cooled, whereupon the spherical prills (2) are further cooled in a heat exchanger (18), characterized in that the molten substance is introduced into a spraying system with a cup-shaped spray head (12) rotating about a vertical axis, while a spray basket (10) rotates about the longitudinal axis and the droplets are discharged through openings (47) in the shell (48) of the spray basket (10) in the radial direction and between the jacket (48) of the spray basket (10) and the inner wall of the solidification tower (11) fall in the direction of the bottom outlet of the solidification tower (11) and the Rotati onsgeschwindigkeit of the spray basket (10) and the flow velocity of the gaseous cooling medium is limited to the top so that the trajectories at least one

Plural majority of the droplets or Prills (2) within an imaginary cylindrical shell sheath whose diameter is slightly smaller than the diameter of the inner shell of the solidification tower (11).

2. The method according to claim 1, characterized in that the fusible material

(3) is formed by KOH.

3. The method according to claims 1 or 2 characterized in that the openings (47) are formed with shapes such as circular, oval, polygonal or slit-shaped.

4. The method according to any one of claims 1 to 3, characterized in that the walls of the jacket (48) of the rotating spray basket (10) with openings (47) with a

Surface can be made of a minimum of 0.007mm.

5. The method according to any one of the preceding claims, characterized in that the walls of the jacket (48) of the rotating spray basket (10) with openings (47) are made with a maximum area of 3.2mm.

6. The method according to any one of the preceding claims, characterized in that the rotational speed is controlled or regulated so that, depending on the supplied mass of the molten substance (3), the diameter of the Sprühkop- fes (12) and the discharged volume of Droplets in a predeterminable unit of time a balance between the mass of the molten substance (3) and the mass of the droplets is achieved.

7. The method according to any one of the preceding claims, characterized in that the rotational speed of the spray head (12) with a maximum of 1500 revolutions / minute, preferably with a maximum of 1000 revolutions / minute, is limited at the top.

8. The method according to any one of the preceding claims, characterized in that the rotational speed of the spray head (12) is limited at greater than 200 revolutions / minute downwards.

9. The method according to any one of the preceding claims, characterized in that the trajectories of the majority of the droplets have a distance of at least 0.1 mm from the shell of the solidification tower.

10. The method according to any one of the preceding claims, characterized in that the outer diameter of the spray basket (10) in relation to the inner diameter of the shell of the solidification tower (11) between 1 to 20 to 1 to 200, preferably between 1 to 20 to 1 to 50, is determined.

11. The method according to any one of the preceding claims, characterized in that the rotational speed of the spray basket (10) via the drive device means by means of a control device is continuously controlled.

12. The method according to any one of the preceding claims, characterized in that the rotational speed of the spray basket (10) in dependence of the supplied mass of the molten substance (3) and / or the viscosity of this mass is controlled or regulated.

13. The method according to any one of the preceding claims, characterized in that when changing the viscosity of the molten substance (3), the speed of the spray basket (10) is changed in the same direction.

14. The method according to any one of the preceding claims, characterized in that in a change in the supplied mass of the molten substance (3), the speed of the spray basket (10) is changed in the same direction.

15. The method according to any one of the preceding claims, characterized in that the gaseous medium in the solidification tower (11) flows in cocurrent with the direction of fall of the spherical prills / droplets (2).

16. The method according to any one of claims 1 to 14, characterized in that the gaseous medium storms in the solidification (11) in countercurrent to the direction of fall of the spherical

Prills / droplets (2) is passed.

17. The method according to any one of the preceding claims, characterized in that the amount and / or temperature of the gaseous medium preferably formed by air in the guide in cocurrent with the direction of movement of the prills (2) in the solidification tower, in dependence on the temperature of the medium is regulated in the region of the medium outlet by increasing the amount of the supplied medium and / or its temperature is reduced with increasing temperature.

18. The method according to any one of the preceding claims, characterized in that the amount and / or the temperature of the medium or the air in the guide in countercurrent to the direction of movement of the prills storms in the solidification, depending on the temperature of the medium or the air in Range of the medium is controlled by increasing the amount of the supplied medium or the air and / or the temperature is lowered with increasing temperature.

19. The method according to any one of the preceding claims, characterized in that the medium or the air for cooling the spherical prills (2) is circulated in a closed system.

20. The method according to any one of the preceding claims, characterized in that the exhaust air is cleaned and discharged back into the atmosphere.

21. The method according to any one of the preceding claims, characterized in that continuously fresh ambient air is supplied as cooling air into the system.

22. Method according to one of the preceding claims, characterized in that the spherical prills (2) have a size and / or shape and / or weight deviating from the product specification and / or melting with high proportions of nickel or nickel oxide which occur during the prilling process. Production process have been formed, are excreted.

23. The method according to any one of the preceding claims, that the excreted prills (2) dissolved, prepared, optionally purified and reintroduced as Ätzkali (3) in the production process.

24. The method according to any one of the preceding claims, characterized in that the coming into contact with lye parts of the spray basket (10), the deflection point (5) and the collecting container (7) are overlaid with nitrogen.

25. The method according to any one of the preceding claims, characterized in that the nitrogen is added continuously or periodically.

26. The method according to any one of the preceding claims, characterized in that the solidification storm (11) is subjected to a cleaning and the wash water from the wash water tank (24) in the upper part of the solidification storm (11) is pumped and the funnel-shaped outlet (45 , 46) and the walls of the solidification tower (11) are washed with washing water and subsequently with fresh water.

27. The method according to any one of the preceding claims, characterized in that the washing water is used up to a maximum concentration of 40% KOH / K2C03.

28. The method according to any one of the preceding claims, characterized in that the spray basket (10) and the spray head (12) removed for cleaning from the solidification tower (11), heated for several hours in a steam bath at a maximum of 200 ° C and then to a maximum of 400 ° C are preheated and the spray (10) and the spray head (12) are again introduced into the solidification tower (11).

29. The method according to any one of the preceding claims, characterized in that the cleaning process takes place after a specified degree of contamination or periodically.

30. The method according to any one of the preceding claims, characterized in that the inner surface of the outlet funnel of the solidification tower (11) is heated by a particular electrical tracing.

31. The method according to any one of the preceding claims, characterized in that the inner surface of the outlet funnel to a maximum temperature of 180 ° C, preferably to a maximum temperature of 100 ° C, heated.

32. The method according to any one of claims 2 to 31, characterized in that KOH prills from a starting material (3) having a KOH concentration of greater than 85%, in particular with a KOH concentration between 90% and 95%, and that the area of the apertures in the mantle of the spray basket is between 0.007mm and

4.53mm 2, preferably between 0.032mm 2 and 3.2mm 2.

33. The method according to any one of claims 2 to 32, characterized in that KOH prills from a starting material (3) with a KOH concentration greater than 85%, in particular with a KOH concentration between 90% and 95%, are prepared, and in that the outer diameter of the spray basket is between 1: 20 and 1: 50 relative to the inner diameter of the shell of the freezing tower.

34. The method according to any one of claims 2 to 33, characterized in that

KOH prills are prepared from a starting material (3) with a KOH concentration greater than 85%, in particular with a KOH concentration between 90% and 95%, wherein the temperature of the fusible substance (3) in the spray basket between 200 ° C and 350 ° C and the area of the openings in the shell of the spray basket between 0.007mm and

3.2mm and the spray basket speed is between 100 and 1000 revolutions / minute.

A solidification tower (11) for granulating fusible materials (3), wherein spherical prills (2) are produced from the molten substance (3), transported in the longitudinal direction of a solidification tower (11), and cooled by a gaseous medium flowing therethrough Container for Äztkali (3), a downstream conveyor belt (17) and heat exchanger (18) for the prills (2), a conveyor device, in particular a vibration conveyor element (20) and a bucket elevator (21) for the

Prills to a Prillsilo and a control device with at least one sensor for detecting at least one of the following measured values, such as for the temperature (32), the volume (34) and the flow velocities (35) of the medium or the air and or prills, characterized in that a feed line for the molten substance opens into a spray system comprising a cup-shaped spray head (12) which encloses a substantially cylindrical spray basket (10) with a vertical longitudinal axis and the spray head (12 ) is rotatably mounted about an axis of rotation parallel to the longitudinal axis and connected to a rotary drive and a jacket (48) of the spray basket (10) with a plurality of openings (47) distributed over its surface for discharging droplets of the molten substance (3 ) is formed in the radial direction.

36. A solidification tower according to claim 35, characterized in that the solidification tower is a KOH prilling solidification tower for producing KOH prills by granulating KOH formed fusible materials (3).

37. solidification tower according to claim 35 or 36, characterized in that the openings (47) in the spray basket (10) are circular, oval, polygonal or slit-shaped.

38. solidification tower according to one of claims 35 to 37, characterized in that the openings (47) in the jacket (48) of the rotating spray basket (10) having an area of 0.007mm 2 "- 3.2mm 2" are formed.

39. solidification tower according to one of claims 35 to 38, characterized in that the outer diameter of the spray basket (10) in relation to the inner diameter of the jacket (48) of the solidification tower (11) between 1 to 20 to 1 to 200, preferably between 1 to 20 to 1 to 50, is.