separators of different generations

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COMPARISON TYPES OF SEPARATOR DESIGN

1st generation HEYD or Sturtevant separators 2nd generation Cyclone separator 3rd generation QDK or High Performance cage rotor separator

1. 1ST GENERATION SEPARATOR The dispersing equipment - distribution plate (1) - and the classifying equipment - the auxiliary fan or centrifugal system (2) - are in a common casing - separation chamber (3) - for this type of separator design, which began with the development by MUMFORD and MODI towards the end of the last century. The separator ventilator - the circulating fan (4) - is situated above the separating chamber (3). The separator chamber (3), tailings cone (5), louver ring (6) and the circulating fan (4) are encased by the separator housing. The ring chamber between the separating chamber and separator casing is called the precipitating chamber (8).

Comparison – Types of Separator Design

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OPERATION: The material to be separated is fed onto the rotating distribution plate and thus dispersed across the cross-section of the separating chamber. The separating air is sucked through the material curtain thrown out by the distribution plate via the circulating fan that works as a radial ventilator fan. Particles of separation material that can be carried in the stream of separation air, reach the classification area in the stream of separation air. The spirally shaped, climbing separating air is accelerated across the auxiliary fans here, which are attached to the auxiliary fan of the centrifugal system, in the rotational direction of the ascending separating air spiral.


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The following forces act, in the direction of rotation, upon the particles of the separation material: a: gravity b: centrifugal acceleration (inertia) c: drag force of the separating air, which results from the cross sectional

area of the stream of particles, whose resistance co-efficient (CW-co-efficient) gives the flow speed and the dynamic viscosity of the separating air.

If the centrifugal component predominates, the material to be separated collides with the wall of the separating chamber, is slowed and, following the gravitational pull, slides back into the dispersion area and eventually reaches the tailings cone. Particles of the material to be separated, for which the drag force component of the separating air predominates, come into the circulating fan in the stream of separating air, are accelerated there and, equally effected by centrifugal acceleration in the separating air, enter the precipitation chamber and reach the walls of the separator casing. This is where the precipitation from the separating air stream takes place - comparable with the precipitation of the tailings in the separating chamber - through the so-called cyclone-type wall effect. The separating air is returned to the separating chamber via the louver ring. This system, although capable, has, as proven in an uncountable number of separator installations, some grave inadequacies which only then show themselves to their full extent, when a high degree of fineness of product is required and when there is pressure, particularly financial - to optimise a grinding plant. These inadequacies can essentially be seen in the material circuits. They are as follows:


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A: MATERIAL CIRCULATION INSIDE THE DISPERSION AREA: The material precipitated as tailings inside the separation chamber in

the stream of separating air, i.e. the grain make-up of the material is suited to a pneumatic transportation under the existing surrounding conditions.

After precipitation inside the separation chamber, this material once

again reaches the stream of separation air - the process repeats itself and a material circuit between the dispersion area and the separation chamber begins.

Because the separating air only has a limited load capacity within the

boundaries of the existing surrounding conditions - the specific gravity of the feed material, the flow speed and dynamic viscosity of the separation air - the further acceptance of the separating material, which is continually being fed into the dispersion chamber in the stream of separation air from the dispersion plate is reduced. As a result, a portion of the separation material passes into the tailings cones without being separated.

B: MATERIAL CIRCUIT BETWEEN THE AUXILIARY FAN CENTRIFUGAL

SYSTEM AND THE CIRCULATING FAN: Within the separating chamber, the area of the auxiliary fan, the rising

rotating air is accelerated through the auxiliary fan system that turns in the same direction.

The highest speed of separation air loaded with separation material is

found in this area. The separation of the size ranges of the separator feed material into

fines and tailings mainly occurs in this area. The mechanisms which work here are essentially the three dimensional results of the alternating effects between gravity, centrifugal acceleration and the drag force of the separation air.


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An extension of the cross section occurs above the auxiliary-fan-

centrifugal-system in this type of separator design. The flow speed of the separation air is reduced accordingly and a portion - first and foremost the coarser portion of the feed material - falls out of the stream of separation air and is returned to the upper part of the separator chamber again via the auxiliary-fan system.

A portion of the material returned in this way is broken on the wall of

the separator casing and reaches the separator tailings or the material circuit between the dispersion and separation chambers.

Another portion is lifted by the rising stream of separation air, reaches

the area of reduced flow speed again, partially falls out and arrives back in the upper part of the separator chamber. Thus, a material circuit also begins here.

It should be emphasised at this point that the separating process is not

completed above the separation chamber. Attempts at optimisation of this form of separator design, which had

the goal of increasing the flow speed above the auxiliary fan in order to prevent the fall out of material from the stream of separation air and thus the formation of the material circuits, were unsuccessful because the separator fines became so coarse that the increase in the speed surrounding the auxiliary fan could not be corrected within acceptable limits. In particular, the percentage of so-called "refractors" grew to an extent that could no longer be controlled.


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1st generation separator: internal material circuit C: MATERIAL CIRCUIT WITHIN SEPARATING AIR: The separating air, laden with separator fines, reaches the so-called

precipitating chamber, which concentrically surrounds the separating chamber, via the circulating fan. The separating air, laden with fines departs from the circulating fan that acts as a radial fan and is operated with a circumferential velocity of approx. 40 m/s, and enters the precipitating chamber.

The predominantly tangential discharge of separating air continues

here and the separating air reaches the louver ring area via the alternating currents that are aimed in a downward direction and thus back into the area of the low-pressure suction created by the circulating fan. The separating air is tangentially returned, via the louver ring or guiding blade ring, to the separating chamber.


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The precipitation of fines from the separating air occurs inside these

downwardly directed alternating currents; also via centrifugal acceleration. The fine particles are pressed onto the wall of the separator casing by the centrifugal forces and slide downwards in the form of a boundary layer between the casing wall and the separation air into the fines discharge.

It is obvious that this form of precipitation of fines from the separating

air cannot be particularly effective. Accordingly, tests of the precipitation performance merely result in an

efficiency in the order of between 40 and 70 %, with the understandable trend that the effective precipitation worsens with increasing fineness of the separator fines.

The separating air which is inadequately cleansed arrives in this way

with an accordingly high basic loading of fines via the louver ring back into the separating chamber and thus into the dispersion chamber.


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No further explanation is necessary to realise that the three material circuits described here limit the effective capacity of this system of separation because of the limited loadability of the separating air, particularly as the separating air volume current can hardly be increased. An increase in the stream speeds in the fines separation chamber results in a reduction of the effectivity of precipitation, i.e. the basic fines loading increases further and the separator effectivity decreases accordingly. It should be noted that this form of separator design achieved good results for a construction size of approx. 5 m casing diameter and a fineness of finished product, expressed in mass related specific surface area, of up to approx. 3.500 cm²/g according to Blaine. Corresponding to increasing diameter, a decrease of the capacity e.g. represented in the assessment process according to F.K. Tromp can be established for larger casing diameters. The appearance of this can mainly be attributed to a reduction of the fines precipitation from the separating air in the precipitation chamber via the so-called cyclone-type wall effect. Comparable observations have also been made for cyclones with increasing diameter.


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2. 2ND GENERATION SEPARATORS

2nd generation separator: cyclone separator The interdependence of the separator diameter with the capacity of the separator led to the development of the cyclone separator towards the end of the 1960's. This development came from a patent from the company WEDAG. Mr Heinz Jäger (Bochum) was given as inventor.


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The basic thought behind this invention was the storage of the fines, inadequately precipitated in the separator's precipitation chamber, in a separate precipitation aggregate with a significantly higher effectivity. Cyclones offered the following for this purpose. Effective precipitations in the range of 90 to 97 % are achieved in this aggregate for sensible dimensions. As the circulating fans installed in the 1st generation separators are not able to create pressure systems according to the system's pressure losses - separator, precipitation cyclones and connecting pipes - the circulating fan was installed as a separate aggregate outside the separator preferably in the area with the lowest dust loading i.e. behind the precipitation cyclones. This arrangements also allows the use of stream technical, optimised radial fans with a high degree of effectivity. The geometry of the separating chamber of this form of separator design is comparable with that of the 1st generation separators. The same mechanisms work here. Accordingly, comparable material circuits are also developed. These are: a: Material circuit between the dispersion and classification zones b: Material circuit between the centrifugal auxiliary fan system and the

separation air outlet to the precipitation cyclone.


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2nd generation separator: cyclone separator

internal material circuits The material circuit - rest dust to precipitation cyclone and separation chamber - may be neglected and considered non-existent for this observation due to the decidedly low content of solids. Even just the return of the almost completely cleansed separation air to the separation chamber - the rest dust content generally lies in an order of magnitude of less than 15 g/m³ - resulted in separators of this form of design requiring approx. one third of the quantity of separation air of separators of the 1st generation with a comparable throughput.


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As an almost identical separating chamber diameter is present for comparable throughput performances, the stream speed in 2nd generation separators is in the order of 30 - 40 % of the stream speeds for 1st generation separators. The reduction of stream speeds directly affects the granulometry of the separator fines, particularly in the upper end of the range of the grain sizes. There are considerably lower sieve residues for comparable specific surface areas of the fines compared with 1st generation separators, e.g. on the 0.09 mm sieve. Cyclone separators gained entry to the cement and related industries from the end of the 1960’s. From the mid 1970’s onwards, they had largely become the standard separator, particularly for installations with larger throughput. Based on the separation of cement, it can be said that this form of design gives very good results for the separating out of products comparable with PZ35F or up to approx. 3,200 cm²/g according to Blaine. A distinct improvement of separation results for qualities comparable with PZ45F of up to approx. 4,000 cm²/g according to Blaine, from the 1st generation can be proven and was shown in the separation tests according to the method of F.K. Tromp.


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3. 3RD GENERATION SEPARATORS Despite the great improvement in separator performance that was confirmed in that cyclone separators became the standard separator on the market, the separation results for the separation of high and very high quality cement or other very fine products, e.g. filler, remained unsatisfactory. Increased demand on quality, the general trend towards finer and finer products which was observed in the market and competition in both product technical and economic areas led to the development, to industrial maturity, from the early 1980’s, of the principle of spiral wind separation as described as early as 1939 by RUMPF.

OPERATION PRINCIPLES OF 3RD GENERATION SEPARATORS In separators of this form of design, the separation of the separator material, which is given into a tangentially directed stream of separation air that undergoes central suction, occurs through the interaction between the forces of inertia and resistance as well as gravity. The cyclograph picture of the separation air has a spiral form between the tangential entrance and the central suction. To roughly simplify, the forces working on the particles of the separation product that is fed into this stream can be broken down into a centrifugal component, radially inwards directed and the gravitational component. The spatial results of these components decide whether a particle of separation material ends up in the coarses’ discharge or inwards in the fines discharge.


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3rd generation separator: QDK form of design


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COMPOSITION OF 3RD GENERATION SEPARATOR - QDK FORM OF DESIGN The material feed occurs from above onto a distribution plate that, through its supporting structure, concurrently represents the upper covering of the cage rotor. The mainly central feed guarantees an even distribution of the separation material onto the distribution plate and thus an even distribution into the annular gap between the cage rotor and the air return ring. In this area, a moving veil of material in the form of a downwardly pointed orbit is further accelerated and aerated by the separating air entering in the same rotational direction. The guide vein ring which represents the outer boarder of the separating chamber with its tangentially fitted air return veins and the spirally shaped separation air entry canal guarantees an even distribution of the separation air across the entire area of the separating chamber. Agglomerates, or insufficiently dispersed material, which reaches the outer area of the separating chamber via the centrifugal forces are further loosened by the mechanical contact with the tangentially installed air return veins and are once again fed into the separation area via the separation air entering through the air return veins. Finally, yet importantly, the high sharpness of selection of this separator can be attributed to this mechanical loosening of agglomerates. The fines, carried into the inside of the cage rotor in the stream of separation air is sucked in a downward direction with the separation air and, in the basic concept of the QDK separator, fed across an elbow on the quickest route to the precipitation of from the separation air possibly from the design of the installation.


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POSSIBILITIES FOR INFLUENCING THE GRAIN MAKE-UP OF THE SEPARATOR FINES: These are mainly: a: changes in the centrifugal component b: changes in the inwardly-directed resistance components which work

on the resistance coefficients of the particles and the dynamic viscosity of the separation air on the particles of separation material via the cross section of separation particles of the stream speed of the separation air.

This influence is with few exceptions usually performed below the cage rotor, which works as a radial fan, in 3 generation separators. For a generally constant stream of separation air, the stream speed of the separation air in the separation gap between the air return ring and the cage rotor and finally the previously mentioned interaction between the centrifugal and resistance components are influenced by the circumferential speed of the rotor. Under the evaluation of the mechanisms and connections relevant to the separation, it is clear that the form of the separation chamber’s geometry of the air return vein ring, the rotor and the separation air feed is of immense importance for the functioning ability and the separation properties of this form of separator design. The conversion of this knowledge as well as the knowledge about the limits and possibilities of this form of separator design constitute the manufacture’s expertise.


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INTERNAL MATERIAL CIRCUITS IN 3RD GENERATION SEPARATORS If, for the separation of fines in cyclones, the unimportant rest dust after the cyclones is disregarded, as in the observations of the 2nd generation or cyclone separators, the material circuits which interfere with the separation process because of the limited carrying capacity of the separation air, can not come into being, neither in the distribution zone, the actual separation chamber nor in the separation gap or in the fine discharges in 3rd generation separators. This means that for a sensible geometric design of the separator and for the use of these installations within the limits of the allowable specific loading, the portion of fine material fed into the separator in the feed material is almost completely carried away in the fines. This important advantage of this separation system has a direct influence on the feasibility of the grinding installation before the separator and also a direct influence on the properties of the fines.


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USE OF 3RD GENERATION SEPARATORS - DESIGN FORM QDK Let us first take a look at the grave inadequacies of the 1st and 2nd generation separators. The internal material circuits limit the complete capture of separator material particles in the area of grain separation nearing the grain separation of the fines due to the limited carrying capacity of the separation air. A portion of the grain size range thus gets into the separator coarses and thus back into the mill. That is, this material, which is actually of the fineness of the finished product, is ground again on its way through the mill. Accordingly, the separator feed material is notably finer for a comparable fineness of separator fines for separators of the 1st and 2nd generation. The observation of the particle size distribution of the separator fines shows a reduced portion of very fine grains in the fines of 3rd generation separators compared with 1st and 2nd generation separators, for comparable specific surface areas.

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COMPARISON OF 3RD AND 1ST GENERATION SEPARATORS 1. Feed material 2. Coarse material/rejects 3. Fines/finish product • 3rd generation separators 1370 cm²/g acc. to Blaine 740 cm²/g acc. to Blaine 3800 cm²/g acc. to Blaine • 1st generation separators 1616 cm²/g acc. to Blaine 1218 cm²/g acc. to Blaine 3637cm²/g acc. to Blaine


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A WORKING EXAMPLE OF A CEMENT MILL IS USED FOR THE CLARIFICATION OF THESE STATEMENTS: In the given case, two HEYD separators of the 1st generation were replaced in a cement mill. The process technical changes in the grinding of PZ45F can be seen in the separator evaluation according to F.K. Tromp and the changes in the particle size distribution from the grain group block diagrams. The increase in the throughput during the production of cement of the quality PZ45F - specific surface area approx. 3,800 cm²/g according to Blaine- was 18 %. It should be noted that no changes were made to the grinding charge filling of the mill. The results may thus be directly compared.


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COMPARISON OF 3RD & 1ST GENERATION SEPARATORS: Tromp curves Product type: PZ 45 F Fineness: 3rd generation separator: 3.800 cm2/g acc to Blaine 1st generation separator: 3.637 cm2/g acc to Blaine


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Influence on the Properties of the Separator fines: On the basis of separation with a high rate of effectivity - the proportion of fines contained in the separator feed material is almost completely carried out in the separator fines - an ″over grinding“ of the finished product returned to the grinding aggregate via the separator coarses does not occur. Based on these connections, the separator fines are in the range of very fine grains i.e. in the range from 0 to approx. 6 my with a reduced portion of very fine grains. The following observations could be made, to date, for the observation of the effects of the properties of cement: These observations are based on grinding installations where no, or only very slight, changes were made to the composition of the grinding charge filling after the installation of QDK-separators. These observations are further based on comparable specific surface areas. Because in the appropriate industrial installations, the results of which were considered in this observation, products that can be sold are produced and appropriate measures are taken immediately for diversions from the product specific standards, there are no longer term statistical values available. Thus, recognisable trends from during the commissioning period have been merely related.


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- Portland cements with a specific surface area of up to 3,500 cm²/g

according to Blaine: For cement mills with a length to diameter relationship of less than 2.8,

the water demands to achieve the given spread was slightly higher in the concrete aptitude test. A minimal decrease in the early strength was accordingly established.

This trend could not be established with any degree of certainty for

grinding installation with a length to diameter relationship of greater than 2.8.

- Portland cements with a specific surface area of approx. 3,500 to

approx. 4,500 cm²/g according to Blaine: No significant changes whatsoever in the water demands and the

strengthening process could be established for these qualities of cement.

- Portland cements with a specific surface area of greater than 4,500

cm²/g according to Blaine (high Blaine cements): A significant reduction in the water requirements and thus, for

comparable specific surface areas, the increase in compression, also in the early strength, in the first 24 hours, can be particularly established for these cement qualities.

At the same time, a delayed early set is noticed for these cement

types. The working time is thus extended. It can be generally said that, the working properties of cements of this

quality that are produced with the use of a 3rd generation separator, are considerably better.


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These results are founded in the changed particle size distribution for

these cement qualities compared with separators of the 1st and 2nd generation. The reduction of the very fine grains, particularly in the range from 0 to approx. 6 my, has a positive effect on the properties because this portion bonds with a significant portion of the mix water due to its large surface area.

This portion of the grains participates disproportionally little in the

strengthening process, as a significant proportion is already hydrated in the finished product. The water required for this comes partially from the moisture in the mill ventilation air and partially from the moisture content of the sulphate ingredient.

Finally, the take up of moisture is further helped by the increased

circulation that is a forced result of the use of separators with low efficiencies.

A further aspect can be seen in that the particle size distribution

approaches the idealised “densest possible sphere packing“ via the reduction of the portion of very fine particles. That is, there is an increased number of particle contact points, whereby the mix water appears to represent reduced interstice volumes.

It should also be noted that the statement which led to this circular problem, that a minimal reduction in the early strength can be adjusted due to the increased water requirements for cement types of quality PZ35F and for the use of mills with a length to diameter relationship of less than 2.8, is certainly justified, is however based on the running with a separation air throughput in the range of the maximum separation air throughput meant for the particular type of separator. An adjustment of the grain structure of the separator fines to the requirements can be achieved without any problems through a reduction of the separation air throughput. It is also possible to influence the grain structure via a fitting adjustment of the ball charge composition.


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3RD GENERATION SEPARATORS – USE IN RAW MEAL GRINDING

3rd Generation separators were able to gain acceptance in the grinding of cement. This is not the case in the area of the grinding of raw meal in combination with ball mills. Only a very few 3rd generation separators are in use in this area world wide. This reason for this is multifaceted. One reason for this is that from the early 1970’s, rolled bowl mills became accepted for new installations for large and larger throughputs compared with ball mills. These mills are, in their basic design, generally fitted with integrated cage rotor separators that work according to the functioning principle of the 3rd generation separators. The proof as to the suitability for the use of this form of separator design in raw meal separator is brought forward by this alone. A further explanation can perhaps be seen in the following perspective: Raw meal grinding installations deliver a finished product with mainly constant fineness of grinding resulting from the chemism, the mineralogical composition and the burning process in use. Large scale changes in the fineness of grinding, as in cement mills, are generally not normal. The reputation that the use of a 3rd generations separator is only truly justified for the separation of very fine products remains even today. Raw cement mills with sieve residues on the 90 my sieve in the range of 10 to 20 % represents a comparatively coarse product. In addition, because of the minimal number of the raw mill grinding installation fitted with these separation systems, the potential optimisational possibilities with respect to the increase in throughput and economical considerations are not so well known as for cement mills.


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The condition that hardly any definite knowledge about the process technical influences on the burning process associated with these separators generated raw meals is also based in the fact that only a few raw meal grinding installations are fitted with these separators. It must be taken into account here, that the burning process reacts particularly sensitively to influences that come into the oven system through changes in the chemism and the mineralogy. For this reason, it is difficult, and only possible through long term statistical observation, to definitively assign this type of influence to the grain structure of the raw meal. Knowledge collected to date points to a positive effect on the burning process, exerted by the reduced portion of extremely fine grains also present in raw meal. The explanation for this is probably to be seen as lying in the corresponding reduced dust circuit in the system’s heat-exchanger-oven-deduster and in the associated decrease in the tendency to form a coating in the heat-exchanger.


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USE IN RAW MEAL GRINDING – POSSIBILITIES FOR INCREASING THROUGHPUT Raw meal mills executed as crushing plant circuit mills are often fitted with grinding balls with a length to diameter relationship of less than 2. This relationship can be based on the dimensions of the mill tube from “flange to flange“ or alternatively on the length of the individual, separately functioning grinding chambers. Mills of this type e.g. as “double rotaries“ from POLYSIUS, FCB and others or alternatively inside raw meal mills comparable with the HISCHMANN / O&K raw meal grinding systems with serially connected pre-crushing are used. The basic idea behind the philosophy used here, is to remove the grinding material which is receptive to fineness of finished product with in the grinding areas as quickly as possible from the grinding system so as to avoid an unnecessary over grinding and burdening of the grinding areas. Accordingly, relatively large material circuits begin in this type of grinding installation. They are often of the order of 4 to 5 times as large (Basis: tailings + fresh material / fresh material). It stands to reason that a significant increase in throughput can be achieved through the exchange of separators with low degrees of efficiency for high performance separators of the 3rd generation. A further aspect can often be seen in the presence of grave drying problems in addition to separation problems, for raw meal grinding installations of this type, which are usually set up as dry grinding installations. Insufficient drying disables the flow properties of the grinding material within the grinding chamber and, in addition, the procession of size reduction. Further, the dispersability of the separator feed material is limited inside the separator. Both occurrences lead to a decrease of the throughput.


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For these aspects, 3rd generation separators open up perspective which were hardly thought of with previous forms of design. Prognosis as to realistic increases in throughput and improvement of the working relationships are however not possible until after a thorough analysis of the original problem and the individual surrounding conditions. Increases in throughput for previous design forms for comparable fineness of grinding in the order of approx. 20 %, and greater, considering the obviously improved availability, have been achieved.


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INSTALLATIONS AND PROCESS TECHNICAL ASPECTS OF THE SEPARATION CONCEPT QDK The sales chances for a new type of separator were tested in the form of a market assessment as the development of the QDK concept advanced. The results of this assessment determined the over all concept of this separator system. The following points resulted, based on the world wide situation in the cement industry: In many parts of the world, the installed production capacity is greater than the demand for cement. A change in this situation can not be see in the near future. New cement plants are rarely being built at the moment. The few current projects usually have a provisional time of up to 5 years to placing of order. Similarly, new grinding installations are also only being erected in small numbers at present. On the other hand, existing mills are being increasingly optimised under the pressure to improve competitiveness and to fit in with increasing demand on quality. The exchange of out dated separators for 3rd generation separators is an important measure towards this goal. Thus, a separator concept which is to be developed should be fitting to the situation in the market. This results in the demand for the highest possible degree of flexibility in planning in both new and existing installations, in addition to the demand for a performance fitting to the investment costs. A further demand is to view the separating installation as merely part, although an important one, of the grinding installation, i.e. the demanded flexibility must take the complete installation as a complex system into consideration.


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Taking these points into consideration, the following demands were placed on the development of a marketable separation concept which is supposed to create an attractive alternative to the competitor’s separation systems: 1. Convincing functioning of the separator 2. Reliable and uncomplicated machine technical assembly 3. Flexibility in planning; in particular in existing installations

4. Possibilities for assimilation in the technical process in an installation through the connection of multiple functions

To 1: The parameters “sharpness of selection“ and “fines spacing“ and the

possibility of influencing the fineness and where necessary the particle size distribution of the separator fines are decisive for the assessment of a separator.

For the development of a new separation concept, the state of

technical development could not be used as a goal, rather had to be taken as the starting point. For this reason, the geometric form of the separation area and of the dispersion area were given particular attention.

The nature of development is so that it advances as long as the driving

impulse still exists. The superiority of a system shows itself in no other way so exactly as in its ability to fit in with the changing surrounding conditions.

Today, the machine factory CHRISTIAN PFEIFFER BECKUM is able

to solve all separator technical tasks for the cement and related industries on a high level with the separator of the design form QDK. At the same time, the previous statement is confirmed, as long as the tasks can change, the development is not complete.


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To 2: We were able to fall back upon over 50 years experience in separator

design for the development of the constructive design and the selection of important components, as well as wear protection. Particularly attention drawing was thus the constructive form of the drive and bearing unit of the cage rotor , the dispersion unit and the sealing between rotor and fines discharge.

Further, in order to insure a high degree of work place safety, the use

of a bearing guidance system which is not limited to measuring temperature rather also records the condition on the bearing and the oscillation relationship, was included.

Obviously, a system of this type is fitted with automatic lubrication

supply. Further points of importance include an easy accessibility and the

exchangeability of worn parts. The constructive form of a separation system can of course only be

limited to the most sensible form of the individual components according to machine technical points. As the functioning is based on stream technical principles, the demands on the stream technology must also be sufficient. A constant feed flow into the separator, of both separation product and separation air, is the basic prerequisite for achieving the “high performance“ characteristic separation parameter.

To 3: The first step towards the development of a separation system is the

development of an optimal separator geometry, the introduction of the separation air, the establishment of load limits and the limits for usage.

Next, construction sizes are assigned according to the different

performance ranges. It should be noted here that:


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Because surface areas develop in the second power but in the third

power, a change in the measurements of the construction sizes is not possible, or only possible with considerable concessions in the performance ability.

Thus a suitable geometry, fitting to the individual construction sizes, must be established. The establishment of the concept occurred parallel to this development.

The QDK-separator concept was developed with consideration of the

situation at the time, that considerably more existing installations were renovated than new ones built.

The basic advantage of the 3rd generation separator is that the spatial

requirements are considerably smaller than for 1st and 2nd generation separators with comparable throughput.


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SEPARATOR CONSTRUCTION SIZES FOR COMPARABLE THROUGHPUTS

Despite this, the planning of a 3rd generation separator can be

plagued by problems under the given spatial surrounding conditions. These problems however, usually lie in the arrangement of the fines precipitation from the separation air. For this reason, cyclones are installed in the standard version of the QDK. Accordingly, the arrangement of the cyclones took place flexibly.


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The following are a few examples of forms:

In addition, it is possible to precipitate fines in the filter installations,

with and without separation air return:


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To 4: The represented possibility of fine precipitation in filter installations,

both with and without the return of the separation air, is one of the simplest forms of connection of multiple functions. In addition to this, it is possible to cool the separation air. In the case of partial separation air return, the quantity of which is controlled by measuring the temperature in the separator fines stream, it is also possible, within limits, the possibility of maintaining a defined temperature of finished product.

In addition, the following connections are possible: - DRYING WITHIN THE SEPARATOR: Instead of the separation air, hot gasses are fed into the

separator. A partial or complete exchange of the separation air is also possible here. The range of the separation air exchange occurs dependant on the separation air temperature or the temperature of the finished product.

This type of switch has uses particularly in grinding raw meal.

Both oven exhaust gases and hot gases from a hot gas producer or a mixture of gasses (oven exhausts + hot gasses from a blast furnace) can be used here.

The use for the simultaneous drying and grinding of granulated

blast furnace slag or granulated blast furnace slag cement is equally thinkable. In particularly when the granulated blast furnace slag component is pre-crushed in a high pressure roller press and directly fed into the separator.


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- USE OF THE MILL VENTILATION AIR AS PART OF THE SEPARATION

AIR: In this case, the mill ventilation air is fed in directly as part of the

separator circulation air. The mill ventilation air throughput required for mill operation is guaranteed via a low pressure measuring device which works on a control damper between the mill ventilation air pipe and the inlet into the separator.

The portion of the separator circulation air which corresponds to the portion of the mill ventilation air is led away via a filter. The advantage of this switch come from the avoidance of the loss of pressure of a pre-precipitation installed in the extrusion of the mill dedusting - a static separator- and in the case of raw meal grinding, a cyclone precipitator after the double rotor grinding system with a very large mill ventilation air throughput.


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HIGH PERFORMANCE SEPARATOR

ADVANTAGES OF OUR QDK

PRODUCTION ASPECTS:

• Possible production increase up to 20 % by exchanging at 1st generation separator against a QDK separator.

• Optimised and better separating efficiency.

MAINTENANCE ASPECTS:

• V-belt transmission.

• A cartridge containing all bearings guarantees a long lifetime and protection against dust.

• Easy accessibility to all separator parts.

• Complete protection against wear.

• Central lubrication system and bearing supervision.


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QDK SEPARATOR’S LOAD RATIO

CEMENT: Separator feed rate/separation air 1.8 kg/m³ Separator product/separation air

3,000 cm.2/g acc. to Blaine 0.75 – 0.8 kg/m³ 4,000 cm.2/g acc. to Blaine 0.55 – 0.6 kg/m³ 5,000 cm.2/g acc. to Blaine < 0.5 kg/m³

RAW MEAL 3,000 cm.2/g acc. to Blaine 2.2 kg/m³ Raw meal 12 – 14 % 90 Mm 0.55 kg/m³


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SEPARATOR DIMENSIONING 1. Basic Data:

• Feed material • Particle size distribution of coarse material • Density of fine material

2. Specific Load

• Specific coarse material feed

Max. 1.8 – 2.0 kg feed material m³ separation air

• Specific fine material feed

Max. 0.8 kg feed material m³ separation air

• Specific cage surface load

Approx. 10 kg feed material m³ separation air

3. Separator Type


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SEPARATOR EVALUATION – PARTICLE SIZE DISTRIBUTION


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SEPARATOR EVALUATIONS


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STANDARD WEAR PROTECTION


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SAMPLING POINTS WITHIN MILL SYSTEM

SAMPLING QUANTITIES AND ANALYSIS


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AIR MEASUREMENT POINTS

Points Pressure drop Measurement Mill Ventilation A1 Ambient ∆p mill T, pa A2 Mill exit ∆p static sep T, p A3 Static sep. exit ∆p filter T, p A4 Filter exit ∆p fan T, p, V A5 Fan exit T, p Separator Ventilation B1 Ambient/Inlet ∆p separator T, pa B2 Separator exit ∆p cyclones T, p B3 Cyclone exit ∆p fan T, p, V B4 Fan exit T, p

separators of different generations

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