EP1032641A2

EP1032641A2 - Improved method for producing tenside granulates with a higher bulk density

Info

Publication number: EP1032641A2
Application number: EP98961137A
Authority: EP
Inventors: Olaf Blochwitz; Georg Assmann; Andreas Syldath; Ditmar Kischkel; Karl-Heinz Schmid
Original assignee: Cognis Deutschland GmbH and Co KG
Current assignee: Cognis IP Management GmbH
Priority date: 1997-11-14
Filing date: 1998-11-05
Publication date: 2000-09-06
Anticipated expiration: 2018-11-05
Also published as: ES2272014T3; US6362157B1; DE59813704D1; WO1999025805A2; WO1999025805A3; EP1032641B1; DE19750424A1

Abstract

The invention relates to an improved method for producing tenside-containing granulates with a washing and cleaning action and a bulk density of over 500 g/l. The granulates are produced from a tenside formulation which does not contain a non-tenside liquid component and which is in a liquid to paste state at normal pressure at temperatures of between 20 and 80 DEG C, by granulation and simultaneous drying in a fluidized bed over a bottom provided with through openings for the incoming flow of fluidizing gas. The aim of the invention is to make this method more economical. To this end, the through openings are covered by a grid with a mesh size of less than 600 mu m.

Description

Improved process for producing surfactant granules with a high

Bulk density

The invention relates to a process for producing detergent-containing granules with a bulk density above 500 g / l, which are active in washing and cleaning, from a surfactant preparation which has a non-surfactant liquid component, in particular water, and which operates under normal pressure at temperatures between 20 and 80 ° C is in liquid to pasty form, by granulation and simultaneous drying in a fluidized bed above an inflow floor provided with through-openings for the fluidizing gas, in particular fluidizing air, drying being understood to mean the partial or complete removal of the non-surfactant liquid component.

Such a method is known from the applicant's European patent specification 0 603 207 B1. The inflow floor and the size and shape of its passage openings can be different, as is already shown in detail in the cited patent.

In this known method it occurs again and again, especially when the operation is interrupted, that granules fall through the openings of the inflow floor into the particularly hot area below the floor, are damaged there thermally and in terms of color and partly again through the openings of the inflow floor reach the fluidized bed so that the end product contains white granules with brown to black spots, which render the entire product unsuitable for use. If the particles that have fallen down through the inflow floor remain in this hot area, then after each shutdown of the system, complex cleaning of this inflow zone and also of the floor itself, to which these particles adhere, is necessary. The problems occur in particular in the production of granules with particularly high bulk densities above 500 g / 1. These particularly heavy particles sometimes fall against the fluidized air during operation through the passage openings of the inflow floor into the lower hot area, from which they are blown back into the fluidized bed after thermal decomposition and breakup by the fluidized air.

Another serious problem in the production of granules with particularly high bulk densities in accordance with the known method is the caking of the hot granules, which are sticky due to their surfactant content, on the inflow floor and in the area of its passage openings, where they gradually narrow the free cross section until the ventilation for the fluidizing gas can no longer compensate for the pressure loss caused in this way. The system must be switched off at this point at the latest and the inflow floor must be freed from the partially thermally decomposed caking with great effort.

The invention is therefore based on the object of improving the economy of the method of the type mentioned. In particular, the duration of an uninterrupted operation of a corresponding system is to be extended considerably. In addition, the quality of the product obtained should be improved so that there is no longer any risk of black or brown spots ("specks") on the preferably white granules.

This object is achieved in that the passage openings are covered by a grid with mesh sizes smaller than 600 microns. The grid can be arranged inside or above the passage openings. However, the grid preferably lies directly below the passage openings of the inflow floor.

In a practical embodiment, a metal gauze with the appropriate mesh size can be sintered onto the underside of a known inflow floor or attached in some other way. The metal gauze preferably consists of the same material as the inflow floor, in particular of stainless steel.

The fine-meshed grid prevents particles from falling through, especially when the granulation system stops unscheduled, but in the case of heavy particles with bulk weights around 1000 g / l are prevented even during operation.

The mesh size of said grid is preferably between 200 and 400 μm.

To remove the caking that occurs during operation on the top of the inflow floor and on the grid filling the through openings, it is no longer necessary to switch off the granulation device with a subsequent manual cleaning, or only at much longer intervals if, in a further advantageous embodiment of the invention, the top is switched off cleans the inflow floor during operation by means of a slide, scratch or the like. Such cleaning can be done manually or automatically. The scratch or scraper used can be made of a thermally resistant plastic, e.g. B. polytetrafluoroethylene (PTFE) exist to exclude damage to the inflow floor with certainty.

Similarly, it is advantageous if the inside of easily accessible system parts, in particular pipelines with a larger diameter, which tend to gradually grow due to adhering products or product components, is cleaned by means of mechanical scrapers during operation. As an example of a product component of detergents and cleaning agents that tends to stick, fatty alcohol sulfates (FAS) may be mentioned, which can hydrolyze at elevated temperatures.

It is also advantageous if the inflow floor used has a pressure loss of at most 10 mbar and in particular at most 6 mbar.

When carrying out the granulation process, it cannot be avoided that oversize, ie granules with grain sizes above the desired range, are formed. It is known to grind the oversize grain, to add the obtained good grain, i.e. the granules within the desired grain size range, to the finished product stream and to blow the fine grain, ie the granules with grain sizes below the desired range, into the fluidized bed apparatus as germs.

Problems arise when grinding particularly large oversize particles. These granules are generally not completely dry and contain inside the not yet crystallized form of surfactant preparation. This liquid to pasty and hot portion bakes on the rollers of the mill, so that the rollers have to be cleaned more frequently than usual.

To further improve the economy of the process mentioned at the outset, in which the granules obtained are also classified by sieving according to the desired particle size range, it is therefore proposed that the undersize obtained during sieving be returned to the fluidized bed, which is above the desired particle size but below one oversized grain that is of a predetermined size grinds and likewise returns to the fluidized bed and the oversized grain that is above the specified size is collected, cooled and only then ground and returned to the fluidized bed.

The specified grain size is preferably about 10 mm. The desired grain size range is preferably 0.4 to 1.6 mm.

It is favorable in the process according to the invention if the surfactant preparation form used has a surfactant concentration of 35 to 95% by weight. Particularly suitable compositions of the preparation form are mentioned in EP 0 603 207 B1, to which reference is expressly made to supplement the disclosure.

The aqueous surfactant preparation form used has a relatively high viscosity of 3,000 to 20,000 mPas. This toughness requires two-component atomization.

When spraying the surfactant preparation form into the fluidized bed, a particularly fine distribution of the droplets is desired. The reasons for this lie in the need to produce not only the granules in the desired grain size range, but also a sufficient amount of fine grain that serves as the seed material. In addition, the proportion of oversize particles, ie granules with particle sizes above the desired range, should be kept as small as possible. A fine distribution of the droplets has the further advantage of a relatively large surface area of the droplet or particle compared to the volume, so that it not only dries up quickly, but also completely, and there is no gelatinous sticky area inside, which is present during storage and use of the finished product can lead to problems. For this reason, it is proposed that the surfactant preparation form is sprayed into the fluidized bed by means of at least one nozzle which has at least one additional nozzle channel for compressed air, in particular swirl air, for fine atomization of the surfactant preparation form. The nozzle channel for the compressed air is preferably on the outside and the channel for the surfactant preparation form is on the inside.

The lower the liquid throughput through the nozzle, the higher the specific air consumption and the finer the droplet distribution. Too fine a droplet distribution is disadvantageous, however, since the droplets dry almost completely before they reach the granules present in the fluidized bed, so that the resulting excess of germs is quickly blown into the filter of the fluidized bed apparatus. In addition, in the case of droplets which have already partially solidified on impact with the granules already present, undesired relatively light agglomerates, ie a product with a low bulk density, are obtained. By using suitable nozzles and setting a suitable air consumption and liquid throughput, a product with a relatively high bulk density can be produced, at the same time generating a sufficient amount of new germs. It has turned out to be particularly favorable if a nozzle with an air consumption of 0.5 to 1.3 kg of air / kg of liquid and a liquid throughput of 150 to 850 kg / h is used.

In principle, the nozzles can be attached in different ways inside the fluidized bed apparatus. It is known, for example, to attach the nozzles to holders in the interior of the fluidized bed apparatus. On the brackets and on the supply lines for the nozzles that necessarily run inside the fluidized bed apparatus in this case, product components are disadvantageously deposited, so that cleaning is necessary from time to time. Another disadvantage with this arrangement is a possible disturbance of the fluidized bed by the brackets and supply lines. This arrangement of the nozzles with their supply lines has so far been chosen in order to ensure that a uniform spraying of the fluidized bed is achieved from top to bottom.

The inventors have now surprisingly found that the required uniform spraying of the fluidized bed from top to bottom is ensured even if the nozzles are attached directly to the inner wall of the fluidized bed apparatus. In this case, they are slanted downwards directed. It is therefore proposed in a further advantageous embodiment of the invention that the surfactant preparation form is sprayed in by means of nozzles which are arranged on the inside of the side wall of the fluidized bed apparatus, the feed lines for the nozzles running outside the fluidized bed apparatus. In addition to avoiding caking, the arrangement of the feed lines has the additional advantage that leaks in the feed lines can be recognized immediately by the operating personnel and can be remedied easily from the outside. With this arrangement of the nozzles, injection at different heights is also possible.

In the fluidized bed granulation process according to EP 0 603 207 B1, it is only necessary to add germs at the start of the process. However, since granules are continuously produced during production outside the desired grain size range of the good product, it is expedient for economic reasons if in a further advantageous embodiment of the invention 1 to 90% by weight, in particular 2 to 80% by weight, % Germ material, based on the product output, feeds the fluidized bed.

This seed material is preferably produced granules with a grain size that is too small or corresponding granules with a grain size that is too large, which have been ground and sieved.

Reference is made to EP 0 603 207 B1 with regard to the preferred and preferred swirl air velocities. The preferred inlet temperature of the fluidized air is 80 to 230 ° C, the preferred air outlet temperature is 30 to 120 ° C.

In the known method, the product drawn off from the fluidized bed is cooled in a product cooler before it is packaged. In contrast to the previous method, it is advantageous if, instead of ambient air for cooling, an already cooled supply air is used, in particular at a temperature of 5 to 8 ° C, so that in any case, even on very hot summer days, a product temperature of less than 35 ° C with certainty. The lower absolute humidity of this pre-cooled cooling air also has advantages for the wash- and cleaning-active granules, since this removes further (residual) moisture from the product, which results in increased storage stability. A filter is preferably installed in or on the product cooler, the filter dust of which is returned to the fluidized bed as seed material. The cooler works especially self-promoting.

The following filter system for the actual fluidized bed system is also advantageous. In addition to an optional top filter, a separate cyclone for separating particles from an external filter system is provided. The design of the filter depends on the material properties of the product to be granulated and the amount of dust generated.

The way the burner is used can be direct or indirect. When driving directly, the hot exhaust gas from the burner comes into direct contact with the fluidized bed. In indirect driving, which is preferred here, a heat exchanger is interposed, in which the exhaust gases the fluidizing gas, for. B. air, heat.

Exemplary embodiments of the method according to the invention which have been carried out in a device according to FIG. 1 are described in more detail below. A product flow diagram is shown in Figure 2.

Figure 1 shows a device suitable for performing the method according to the invention in a schematic representation. The surfactant preparation form to be dried and granulated is passed from stirred templates 1 of different sizes via metering pumps 2 and a line 3 to the fluidized bed granulation dryer 4. The templates 1 are connected to the lines 3 for the nozzles 8 so that different pumps 2 and nozzles 8 from the templates 1 can be operated. A mixture of the contents of different templates 1 for setting the desired recipe is possible in this way. Another advantage is the possibility of switching from one nozzle 8 to another nozzle 8 in the event of malfunctions without the operation of the granulation dryer 4 having to be interrupted.

The fluidized bed granulator dryer 4 essentially consists of two areas, namely an upper area with the fluidized bed zone 5 above an inflow floor 6 provided with passage openings. The air required to maintain the fluidized bed, which also serves for drying, flows out of the lower, particularly hot area 7 up through the through openings of the inflow base 6. In this example, the inflow base 6 consists of six circular sector-shaped elements, a central circular opening for the downpipe 13 being kept free. Alternatively, the bottom 6 can also be in one piece. The inflow floor is equipped with holes with a diameter of 2 mm, which are spaced 10 mm apart (hole division). In operation, the particle stream moves upwards on the outer wall and from there to the central discharge area, where it is classified by means of the classifying air flowing upward in the downpipe 13. The granules above a certain grain size range fall down through the downpipe 13 to the rotary valve 14; the smaller and lighter particles move in the vicinity of the inflow bottom again outwards to the side wall of the fluidized bed granulator dryer 4.

In order to prevent the relatively heavy granules produced according to the invention from falling through the openings in the inflow floor, a wire mesh with a mesh size of 0.3 mm is sintered under the floor. The pressure loss of the entire floor increases in this way from 2 mbar to 6 mbar. With this configuration of the inflow floor 6, no more product falling through was observed, in contrast to a floor without this wire mesh.

The pasty surfactant preparation form is fed via line 3 to six nozzles 8, where it is divided into particularly fine droplets by means of compressed air of approximately 3 bar, which is fed to the nozzles via line 9 and swirled within the nozzles 8. The nozzles 8 are attached to the inside of the side wall of the fluidized bed granulator dryer 4 and are directed obliquely downwards, the spray direction being adjustable from the outside. The droplets hit the particles of the fluidized bed, are dried at the same time and allow the particles of the fluidized bed to grow into larger granules. The finely divided solids required for the process, the so-called germs, are fed to the fluidized bed via lines 10, 11, 12. The germs come from different sources, as will be explained below.

The granules, the grain size of which is in the desired range or above, are discharged via a down pipe 13 and a rotary valve 14 and fed to a cooler 15. For grain size classification, classifier air is allowed to enter the downpipe 13 from below. For the sake of clarity, this detail is not shown in FIG. 1. The still relatively hot granules are cooled with air heated to 5 to 8 ° C., which is supplied via a line 16, leave the cooler 15 via a further rotary valve 17 and are fed from a conveyor belt 8 to a screening plant 19. The exhaust air from the cooler 15 is cleaned with a bag or pocket filter 20, the filtered fine particles being returned to the fluidized bed as seed material.

The screening plant 19 consists of at least two screening decks 21. Oversize 22 with a size of more than 10 mm is collected, cooled and only ground later, when this oversize has also cooled to the inside, so that this grain is continuously crystallized. Coarse grains with a grain size below 10 mm, but above the desired grain size range, are fed into a roller mill (roller mill) 25 via a screw 23 and a pneumatic steep conveyor section 24 and milled there. The gap width of the roller mill can be set between 0.4 mm and 1.2 mm. The ground material can either be passed to the screening plant 19 (line 26) or back into the fluidized bed immediately above the inflow floor (line 27).

The good grain obtained from the screening plant 19, that is to say the granules within the desired grain size range, are drawn off and packed via the line 28.

To complete the fluidized bed granulator dryer 4, a filter system 29 with a bag or pocket filter based on needle felt for the exhaust air and a burner 30 for heating the fluidized air supplied via the line 31 are provided. Here, a so-called direct mode of operation of the burner is used. The system is also equipped with an emergency chimney 33 behind the burner 30. In this way, the hot air from the burner (residual heat) can be released directly to the environment in an emergency without additionally heating or fluidizing the organic components in the fluidized bed. In the event of a fire, the source of the fire is quickly extinguished by water injection from a specially installed facility. Since no more supply air is sent through the fluidized bed, a fire cannot be started again and the supply of oxygen is cut off at the same time.

After a gas scrub, the exhaust air from the filter system 29 can be used again as supply air for the burner 30 or the corresponding heat exchanger. In this way, air recirculation can be achieved without emissions. The fine particles obtained in the filter system 29 are also added to the fluidized bed again as seed material via a cellular wheel sluice 32 and the line 12.

The use of clearing locks is an advantage when granulating and drying sticky products. Clearance locks are understood to mean locks for powder or granules with a possibility of forced clearing. It is favorable to use such clearing locks in the area between the fluidized bed and the rotary valve 14, in front of the rotary valve 32 of the main filter 29 and between the cooler 15 and the downstream rotary valve 17. In the case of sticky products, this prevents the rotary valve from sticking.

In FIG. 2, an exemplary embodiment of the method according to the invention is shown again in summary with the aid of a product flow diagram. The reference symbols used here have the same meaning as in FIG. 1. The solid lines indicate continuous, the dashed lines a discontinuous execution of the corresponding process steps.

The product produced in the fluidized bed granulator dryer 4 is cooled down in the fluidized bed cooler 15 before it is placed on a tumbler screen 19. The gut grain arrives at the filling 34; the oversize is fed via a feed 35 and a dosage 36 to a roller mill 25. Alternatively, the oversize can also be collected in a further template 37 and filled into big bags 38 and stored. The big bags can later be emptied in doses (reference number 39) and fed to the roller mill 25. The particularly large oversize is also stored in big bags 40 and later fed to said roller mill 25 or another roller mill 41, the ground product in turn being filled into big bags 42 for later use.

Depending on the grain size, the ground product obtained from the roller mill 25 is fed either to the fluidized bed granulation dryer 4 as seed material (line 43) or to the fluidized bed cooler 15 (line 44).

The fluidized bed granulation dryer 4 is also supplied with germ material from other sources, namely fine grain from the exhaust gas filter 29, from a silo 45 and from the big bags 42. The table below shows parameters of two process examples according to the invention. Sodium salts were used as sulfates. "Fatty alcohol sulfate" here means sulfates made from a fatty alcohol mixture in the following proportions:

Ci2 fatty alcohol 13% by weight

C <i4_fatty alcohol 6.5% by weight

Ci6_fatty alcohol 26% by weight

Ci8 fatty alcohol 53% by weight

The rest of 100% by weight is distributed among other fatty alcohols.

Parameter fatty alcohol sulfate lauryl alcohol sulfate

Paste temperature 70 ° C 40 ° C

Paste viscosity 10,000 mPas 3,000 mPas

Mesh size of the mesh 300 μm 300 μm

Pressure loss of the inflow floor 6 mbar 6 mbar

Screen cut <1.6 mm <1.25 mm

Surfactant concentration of

Granules 90% 47%

Air consumption 0.7 kg air / kg liquid 0.7 kg air / kg liquid

Nozzle throughput paste 650 kg / h 650 kg / h

Inlet temperature of the

Swirl air 230 ° C 210 ° C

Air outlet temperature 90 ° C 60 ° C

Bulk density 600 g / l 700 g / l

Reference list

template

Dosing pump

management

Fluid bed granulation dryer

Fluidized bed zone

Inflow floor lower area

Nozzle, 10, 11, 12 line 3 downpipe 4 cellular wheel sluice 5 cooler 6 line 7 cellular wheel sluice 8 conveyor belt 9 sieve system 0 bag or pocket filter 1 sieve deck 2 oversize grain 3 screw 4 pneumatic steep conveyor section 5 roller mill 6, 27, 28 line 9 filter system 0 burner 1 Line 2 rotary valve 3 emergency chimney 4 filling 5 template 6 dosage 7 template 8 big bags 9 emptying Big bags

Roller mill

Big bags

management

Claims

claims

1. A process for producing detergent-containing granules with a bulk density above 500 g / l, which are active in washing and cleaning, from a surfactant preparation which has a non-surfactant liquid component, in particular water, and which under normal pressure at temperatures between 20 and 80 ° C. is in liquid to pasty form, by granulation and simultaneous drying in a fluidized bed above an inflow floor provided with through-openings for the fluidizing gas, in particular fluidizing air, drying being understood to mean the partial or complete removal of the non-surfactant liquid component, characterized in that the Passage openings are covered by a grid with mesh sizes smaller than 600 μm.

2. The method according to the preceding claim, characterized in that the mesh size of the grid is between 200 and 400 microns.

3. The method according to any one of the preceding claims, characterized in that the top of the inflow floor is cleaned during operation by means of a slide, scratches or the like.

4. The method according to any one of the preceding claims, characterized in that the inflow floor used has a pressure loss of at most 10 mbar and in particular at most 6 mbar.

5. A process for producing detergent-containing granules with a bulk density above 500 g / l, which are active in washing and cleaning, from a surfactant preparation which has a non-surfactant liquid component, in particular water, and which is under normal pressure at temperatures between 20 and 80 ° C. is in liquid to pasty form, by granulation and simultaneous drying in a fluidized bed, with the partial or complete removal of the non-surfactant while drying Liquid component is understood, and wherein the granules obtained are classified by sieving according to the desired particle size range, characterized in that the undersize obtained during sieving is returned to the fluidized bed, which grinds oversize above the desired particle size but below a predetermined size and also in returns the fluidized bed and collects the oversized grain above the specified size, cools and only then grinds and returns it to the fluidized bed.

6. The method according to the preceding claim, characterized in that the predetermined grain size is about 10 mm.

7. The method according to any one of claims 1 to 6, characterized in that the surfactant preparation form used has a surfactant concentration of 35 to 95 wt .-%.

8. Process for producing detergent-containing granules with a bulk density above 500 g / l, which are active in washing and cleaning, from a surfactant preparation which has a non-surfactant liquid component, in particular water, and which under normal pressure at temperatures between 20 and 80 ° C. is in liquid to pasty form, by granulation and simultaneous drying in a fluidized bed above an inflow floor provided with through-openings for the fluidizing gas, in particular fluidized air, drying being understood to mean the partial or complete removal of the non-surfactant liquid component, characterized in that spraying the surfactant preparation into the fluidized bed by means of at least one nozzle which has at least one additional nozzle channel for compressed air, in particular swirl air, for fine atomization of the surfactant preparation.

9. The method according to the preceding claim, characterized in that one uses a nozzle with an air consumption of 0.5 to 1.3 kg of air / kg of liquid at a liquid throughput of 150 to 850 kg / h.

10. The method according to claim 8 or 9, characterized in that the surfactant preparation is sprayed by means of nozzles which are arranged on the inside of the side wall of the fluidized bed apparatus, the feed lines for the nozzles running outside the fluidized bed apparatus.

11. The method according to any one of claims 1 to 10, characterized in that 1 to 90 wt .-%, in particular 2 to 80 wt .-% germ material, based on the product output, is fed to the fluidized bed during the current process.

12. The method according to any one of claims 1 to 11, characterized in that the product withdrawn from the fluidized bed is cooled with air heated to 5 to 8 ° C.