DE2411024C3 - Method and device for feeding liquid material into a spray basket of a prilling tower - Google Patents

Description

WNUUtunu is reduced in the Norwegian The invention is based on the object

Coitschrift 1 22 298 described. The splash basket throw distance of the drops in the cooling tower effectively be-JSbäß this patent is such that its diameter is reduced in the interior with a border and | i | "j £ _rm strength body is provided, the surface of which at the same time clogging of the holes in the spray basket iiäochwn wall of the spray basket is opposite; this 5 is avoided.

The surface has a shape similar to that of the spray basket.

fP <j runs concentrically with it. If the liquid passage described according to the invention is loosened iliaterially in the annular space between the basket wall and the fact that the supply takes place in the form of an annular lamifflurfläche of the tubular body directed narrow currents, each current in verti i rd arises in large "slip" and consequently io Small, mutually spaced, separated seeds will throw the droplets into a large throwing distance of the rows of holes in the wall of the spray basket.

According to British Patent 1126 199, one sub laminar flows are stratified flows

"Sorühkristallisationseinrichtung described in which to understand the strength of which can vary. Any stream

"■ ^x '- * äi different hole line areas a regulated 15 can be introduced and controlled separately from the others

feji, _ _e liquid material can be fed. and to the different areas of the wall of the

änie partially perforated wall of a cylindrical spray basket with its rows of holes are guided.

^ The container is on its inside and long

? 'iamten to achieve extensively with a number of Umienk- or ejections with a given spray basket, like

Provided baffle plates. He is not between two baffle 20 when applying the usual method

A certain number of openings can be reached in advance. In addition, through such

Lhen The liquid material is fed from above into the separate feed, for example a product.

Container introduced. From the upper one, not perforated, the one made of a mechanical mixture

No liquid is poured out of part of the hopper.

ichleudert, it gets over the horizontal impact means. If necessary, one or more

Weche in the lower part of the container and dyes will be added to the other areas

«The lower row of holes was sprayed out. To identify the hydrau product.

«See pressure is practical at all holes As already mentioned, it is important that each of the

Pale By adjusting the number of holes, hole throughflows with liquid material in the separate areas of the hole and speed, which are attached with a vertical knife projection width of the baffle plates, loading 30 distance, a certain particle size can be guided in rows. You can thus achieve every stream and grains of the same size from all holes within the spray basket at a certain distance from brazen. In doing so, however, the liquid material should let the perforated wall end, whereby the wall should reach the speed of rotation of the loading device if possible in vertically spaced, separate holders, ie the above-mentioned "slip" 35 areas is divided by rows of holes. Does not arise around you If you were to try to achieve such a maximum "slip", it would have proven to be a small "slip" if the number of impactors would prove useful, the annular, laminar sheets, the liquid a tangential velocity currents liquid material close to or up to which give the "slip" insignificant to lead rows of holes in the wall, the hole diameter must therefore be chosen to be relatively small, which increases the risk of clogging a more controllable supply of """'8" J Matehöht. This device is therefore not very good for ^REAS rial in the various B ^he f J ^ f '£ atomization of liquid materials, particularly of openings in the wall of the ^S P ^r' ™ ° ^it; ™. ™ suspensions, suitable. The number of baffles in achieved by a better regulation du ch He ^tting "s inside the Behälfors difficult, moreover, the 45 a favorable ratio between the vorhande lakes NEN surface of the slot-like openings in each area

The use of splash baskets has made special and feeding into this area. Since you have a n.e meaning can choose output per opening when atomizing fertilizer melts, can also get zen and suspensions. In the relevant the throwing distance and thus the diameter of the pipe Manufacturers use spray baskets to lower 50 towers.

each with a capacity of more than 100 t / h. The method according to the invention allows: I aut

The difficulty of selecting an appropriate form several different A '* JJ "^ ^ f" ^ of the holes in the wall increases with the amount of power streams of the ^k fluss.gen material. ^onn f """^ ™ ^ of the basket. In practical operation this means, or pulls coaxially to the axis of rotation of the Spntzkorbes, that the maximum throwing distance for the drops are also supplied. If the ve ™ * £ jSri ^ ome un The grain size distribution of the product, which is symmetrical in relation to the row area, tends to have a larger wall of the cutting basket so that the width is greater. The reason for this may be that, with increasing flows, close to or aird * wall d »Spntrtarbes capacity the course of the liquid flow in the rich, the liquid ^^ Jj ^ J ^ Sahrt, spray basket becomes more complex. The turbulence increases, 6 ° of the spray basket oscillates the holes ™ & ™ £ , local pressure waves arise, etc. whereby a shyness and ^ mU a rhyme

If the ejected drops are to solidify during their final effect on the holes in the wall. If through a cooling tower, then it should be. The Trennl.ne fish the different hole the maximum throw distance of the drops as low as re.henbere.chen the wall kann.mehr or wemg ^ possible be held, clearly marking the cost of the tower ° _5, according ™ ^c * ^ ™ _n £ ^ _t ° ™ _t to use the cold air optimally and ^{to avoid liquid material up to the Loc} J ^r ^ ^^^ of _the deposits of solidified material on the cup wall or whether they ^ ™ _h _ inner walls of the spray basket . Cup with a certain distance from the hole

row areas end. Each area can at least contain a row of holes. You can use the more or less clear dividing lines between the areas holes can be omitted if necessary.

An apparatus for performing the invention Procedure consists of a perforated wall and around a vertical axis rotatable conical spray basket, with through a number of through cylindrical, to the axis of rotation of the spray basket concentrically arranged tubes separate annular spaces, the tubes with their lower ends end near the wall of the spray basket in practically horizontal planes.

Another embodiment of a device for carrying out the method according to the invention consists of a cylindrical one with a perforated wall and rotatable around a vertical axis or the spray basket widening slightly conically towards the top, followed by a number of Bottom conically widening tubes arranged concentrically to the axis of rotation of the spray basket from one another separate annular spaces, the pipes with their lower ends in the vicinity of the wall of the spray basket end in practically horizontal planes.

The invention is explained in more detail below with reference to exemplary embodiments in the drawing.

It shows

Fig. 1 is a vertical section through a conventional perforated spray basket,

FIG. 2 shows the spray basket according to FIG. 1, but with the feed device according to the invention,

3 shows a vertical section through a spray basket with a small conicity and the one corresponding thereto feed device according to the invention,

4 shows a feed device for a relatively large, cylindrical spray basket.

Fig. I shows a conventional, perforated conical spray basket 1, the bottom part of which is attached to the axis of rotation 2. The liquid material is from introduced through the opening 3 at the top.

FIG. 2 shows the same spray basket as in FIG. 1, however in connection with the feed device according to the invention. The influx of the material is here split open with the aid of a number of concentrically arranged tubes 4. In this example they are enough Pipes close to the perforated basket wall. The number of rows of holes in each area can be as well as changing the hole diameter. The liquid material passes through the annular passages 9 introduced. The pipes do not need to reach all the way to the wall of the spray basket A certain amount of "leakage" into adjacent areas is permitted.

Fig. 3 shows how the feed device can be designed according to the invention, if a spray basket has a relatively low taper. The concentrically arranged tubes 4 are then conical design; the wall thickness of the tubes increases in the direction of the basket wall, so that a robust Construction arises with a larger surface area near the basket wall so that the edge of the pipe is not worn away too quickly by erosion. If necessary, you can remove the edge of the Cover the pipe with an abrasion-resistant material.

4 shows an example of a corresponding feed device in a relatively large, cylindrical spray basket.

The number of horizontally aligned hole areas, to which the entire current supplied by the supply device is divided, can depending can be varied according to the required effect. Max Theoretically, control is achieved if a feed area is provided for each hole. When using the feed device according to the invention a side effect is achieved. Because the feed stream is close to the walls of the spray basket ends, very high shear forces are generated in the introduced liquid material. Through this the viscosity of the dispersions, which are often pseudoplastic, decreases. Also arises a large difference between the velocities of the liquid material and the basket wall. Because of the With a high degree of "slip", the material enters the holes almost tangentially. In I ο Ige of that one can be great Provide holes from which only thin rays emerge. The risk of the holes becoming blocked is thereby reduced; for this reason and in connection with the reduced viscosity and With the controlled feed, the diameter of the tower can be reduced.

As already mentioned, the tubes are 4 normally »5 stationary, but they can also be designed to be rotatable. Jc smaller the speed difference between the separate annular spaces 9 and the spray basket 1 is. the lower the achievable "slip" and the smaller the required hole diameter. With pure melts or concentrated Solutions in which the viscosity and the risk of clogging are not very significant can use a low one Speed difference be desirable, because then a steady flow pattern to the Holes. In the case of large injection baskets with large annular spaces and a pseudoplastic, viscous one Suspension, it is recommended to keep the viscosity low by allowing the annular spaces to circulate. If a high degree of "slip" is to be achieved, the annular spaces can be used if necessary let it rotate in a direction opposite to the direction of rotation of the spray basket.

The effect that can be achieved with the invention is explained below with reference to four examples in which the liquid material consists of an NP-containing fertilizer melt with suspended solids. The effect can of course also be achieved with a different composition of the liquid material.
50

Example I.

The inside diameter at the upper row of holes in a spray basket shown in FIG. 1 is affected 150 mm, at the lower row of holes 80 mm. The gap stood between the upper and lower rows of holes was 200 mm. There were 64 rows of holes with a total of 2240 holes. The hole diameter in de top row was 3.8 mm. The hole diameter gradually decreased downwards and the holes in de The row closest to the bottom had a diameter of 2.4 mm.

31 t / h of a suspension of an approximately anhydrous melt from Amme were put into the spray basket nium nitrate and ammonium phosphates in connection

with about 14 percent by weight of undissolved solids, preferably calcium phosphate. Incapable 10 percent by weight suspension consisted of oversized grains of solidified imported widei

Product with a particle size less than

1.5 mm. The suspension was introduced at a temperature of about 16O ⁰ C. The spray basket rotated at 630 rpm. The sprayed droplets could fall freely in a 35 m high cooling tower.

Most of the solidified grains fell about 5.8 m from the center of the tower. The greatest throw was about 7 m from the center of the tower. The sieve analysis of the product showed the following:

Weight percent

+4 mm 1.0

-4 to +3 mm 2.5

- 3 to +2 mm 33.5

-2 to +1.5 mm 42.4

- 1.5 to +1.0 mm 14.8

-! .0 to +0.5 mm 5.5

-0.5mm 0.3

Example 2

The investigation corresponded to that described in Example 1, but a feed device was used according to FIG. 2, but with a larger number of tubes used. Through six concentric tubes the total amount, approximately 31 t / h, was introduced very close to the basket wall in six areas. Around To achieve the same average grain size as in Example 1, the speed of the spray basket can be reduced to 520 rpm.

Most of the grain fell at a distance of 5.0 m from the center of the tower. The maximum throw was only about 6 m from the center of the tower.

Example 3

A spray basket according to Fig. 1 had the same external dimensions as the cup in Example 1, but it differed in the arrangement of the holes and only 30 rows of holes were provided. The hole diameter gradually increased from

4.6 mm at the top to 3.6 mm in the lower row of holes. There were 70 holes in the top row, in the bottom row had 64 holes. A total of 1,600 holes were planned.

In the cups were 22 t / h of a suspension with the same ingredients as in Example 1 and 2 entered. However, about 23 percent by weight of the suspension now consisted of reused oversized grains with a grain size below 1.5 mm. The suspension was atomized at about 145 ° C. The cup rotated at 900 rpm. the

ίο Spray droplets could be in a 35 m high cooling tower fall free.

Most of the solidified grains fell to the ground about 7.5 m from the center of the tower. The maximal Throwing distance was about 9 m, calculated from the center of the tower.

Example 4

An experiment like that described in Example 3, _ao , was carried out with a feed device according to FIG. 2, the liquid material to be fed being introduced through 36 concentric tubes which ended in the cup near the perforated cup wall in six different horizontal rows of holes. In order to achieve the same average grain size as in Example 3, the speed of rotation could now be reduced to 750 rpm. Most of the solidified grains now fell 5.2 m from the center of the tower. The biggest throwing, ₀ wide was reduced to about 6.5 m.

The grain size distribution of the solidified grains, which was achieved according to Examples 3 and 4, was:

Weight percent

+4 mm 0.5

-4 to +3 mm 4.5

-3 to -2.5 mm 7.5

-2.5 to +2.0 mm 25.5

-2.0 to +1.5 mm 36.0

- 1.5 to +1.0 mm 16.0

-1.0 to +0.5 mm 9.5

-0.5mm 0.5

For this purpose 2 sheets of drawings

«09620/326

Claims (3)

Patent claims: 1. Method of supplying flux-flowing material into a spray basket with a perforated wall and rotatable around a vertical axis of a prilling tower, thereby marked-η e t that the feed in the form nngform.ger laminar currents occurs, wöbe, each stream in with vertically spaced apart vertical Separated 'rows of holes in the wall of the spray basket is directed. 2. Apparatus for performing the method according to claim 1, consisting of a with a conical spray basket provided with a perforated wall and rotatable around a vertical axis, characterized by a number of cylinders to the axis of rotation (2) of the spray basket, concentric arranged pipes (4) separate clean rooms (9), the pipes with their lower ends near the wall (1) of the spray basket end in practically horizontal planes. 3. Apparatus for performing the method according to claim I, consisting of a cylindrical or slightly conically widening spray basket provided with a perforated wall and rotatable about a vertical axis, characterized by a number of downwardly widening conically to the axis of rotation ( 2) of the spray basket concentrically arranged pipes (4 ') from one another separate annular spaces (9), the pipes ending in practically horizontal planes only at their lower ends near the wall (1) of the spray basket
valley levels end. The invention relates to a method for feeding liquid material into a perforated one A spray basket of a prilling tower provided with a wall and rotatable about a vertical axis. A number of industrial products are supplied in the form of approximately spherical grains. The methods of making such grains vary. A well known and proven practice is the so-called »Priil process« (spray crystallization). In this process, a Melt or a concentrated, warm or hot solution, which can also contain suspended particles, split into rays that are further broken up into drops. These drops are cooled by that they fall through a gas or a liquid, so that solidified grains are produced. Splitting the liquid into jets can be done in a number of ways. For example, the melt, the concentrated solution or suspension can be directed downwards through a horizontal, fixed, perforated plate ("nozzle plate"). The liquid level above the perforations of such a plate is generally moderately high and is around 100 cm. As a rough guide for the hole diameter, the following generally applies: Hole diameter equal to half the required grain diameter. The openings are therefore chosen to be quite small and the risk of clogging is correspondingly great. This method is therefore used in particular for pure melts, for example for melts and concentrated solutions of ammonium nitrate and urea. . _cinem ^c _other n spray crystallization process Here the liquid or the suspension in an «e- ^d * ™ ^ _r filled, which punched around a vertical axis BteMtegu ^ ^ ^^ will be shaped, however se conical or shell-shaped, se cone. _χτ ^ _{n D} large droplets over the ^ Js scored. _{If rows of} holes in the spray basket are required to produce grains of the same size, the ¹ ^ ^ rows must have a smaller _{diameter in the} upper rows. The ^^^ ^ _{g of the} openings depends on one Y ^ ¹ ™ * ™ ™ ₀ ^g _and is based on a certain number of haktoren ao u "" b To ^ on P ™ * «h ^ S ^ ateria.s, melt, Hurdie. £ un? ^nru " ^e ". . * _ς ·, _kh ; _d , »solution or suspension) in.den ^S P ™ ^bsnd f different procedures J" ^ J "™ ^ '^ liquid through ^ of the spray basket ™ ^str * ^en · ^W ^ J ^g J spielswe.se by a ^ ohlwdIe trains carried so has d * ₅ material sufficient time ™™ ^ J "" ^^^ it virtually upon arrival at the Loche ™ ^d "Spntzkorbes hw.nd mitider G". te.t the basket ™ dum. running. If the spray basket has a large diameter and the material is close to the center of the spray 3 «> basket is introduced, it also has time, i.e. high To assume tangential velocity before; it d e perforated Wall reached. This is especially true for the Case of a viscous suspension. Jei less that Difference between the tangential speed ^ ^ ^^ _{There is material on} the basket openings and that of the basket wall, the more spray liquid the holes can emit. As the difference between these speeds decreases, the hole diameter must be reduced by one unchangeable, given radiation intensity and drop size of the sprayed liquid. Especially when suspensions are atomized it is best to use large holes in the Wall of the spray basket to work so the hole punch do not sit down. Large openings (compared to the required grain size) can be permitted if only one row with openings is provided is. By getting the total intake of casual Material is limited, the feed amount is ur each 5 «aperture lowered so that thin rays and hence small grains arise. But even if a basket with several rows of holes can be used with large holes, by deliberately making a big difference between the speeds of the basket wall and Fluid material (a large "Schlupt") heroite-wrong and take advantage of him. For this purpose, the material is introduced into the hole punch approximately tangentially to the basket wall. As a result, the holes are not completely covered filled with liquid material. In this way let yourself be thin beams and small grain sizes can be achieved even with hole diameters of, for example, 5 mm, so that the ratio of grain diameter / hole diameter, which is obtained when atomizing with the »nozzle plate« «5 is around 2: 1 for a spray basket <I: can be 2. A device with which you can increase the "slump" so that the throwing distance of the drops in the