EP0443119B1 - Dynamischer Wälzmühlen-Luftstromsichter - Google Patents

Dynamischer Wälzmühlen-Luftstromsichter Download PDF

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Publication number
EP0443119B1
EP0443119B1 EP90122986A EP90122986A EP0443119B1 EP 0443119 B1 EP0443119 B1 EP 0443119B1 EP 90122986 A EP90122986 A EP 90122986A EP 90122986 A EP90122986 A EP 90122986A EP 0443119 B1 EP0443119 B1 EP 0443119B1
Authority
EP
European Patent Office
Prior art keywords
classifier
rotor
roller mill
flow
air classifier
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP90122986A
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German (de)
English (en)
French (fr)
Other versions
EP0443119A3 (en
EP0443119A2 (de
Inventor
Franz Poeschl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Loesche GmbH
Original Assignee
Loesche GmbH
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Filing date
Publication date
Application filed by Loesche GmbH filed Critical Loesche GmbH
Publication of EP0443119A2 publication Critical patent/EP0443119A2/de
Publication of EP0443119A3 publication Critical patent/EP0443119A3/de
Application granted granted Critical
Publication of EP0443119B1 publication Critical patent/EP0443119B1/de
Anticipated expiration legal-status Critical
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
    • B02C23/18—Adding fluid, other than for crushing or disintegrating by fluid energy
    • B02C23/24—Passing gas through crushing or disintegrating zone
    • B02C23/32—Passing gas through crushing or disintegrating zone with return of oversize material to crushing or disintegrating zone

Definitions

  • the invention relates to a dynamic roller mill air flow classifier according to the preamble of claim 1.
  • Airflow classifiers of this type which are provided integrated directly above a roller mill, are generally known.
  • An approximately comparable air flow classifier is known from "Cement-Lime Gypsum", No. 10/1987, p. 524, Figure 3.
  • the flow principle implemented there envisages a gas regrind flow rising in the exterior. In the upper area of the classifier, this is fed radially and tangentially inwards to a centrifugal basket classifier via fixed guide vanes.
  • the gas fine material flow is diverted upwards in the centrifugal basket, while semolina and coarse grain are returned downwards to the roller or roller mill via a conical collector.
  • this is a reduction in the upward energy of the ground material coming from the upper part of the mill, mainly the fine material, with less dynamic energy.
  • the gas regrind flow or the material mass flow that is offered to the classifier in a roller mill essentially depends on the gas speed in the guide vane ring around the grinding table and the direction of the gas flow and the gas speed in the upper part of the mill is.
  • the gas regrind flow from the mill room to the classifier is often faced with a part of the coarse material separated from the classifier, which flows downwards from the classifier housing, in counterflow, whereby this counterflow can sometimes reach up to 50%.
  • a portion of the finished product portion present in the gas stream at the outlet of the upper mill part with coarse material flowing back is returned to the grinding bowl.
  • the actual separator chamber with its annular gap cross section must be designed in such a way that the upward gas velocity also allows the particles pushed against the separator wall to move downwards.
  • This can result in a strong sensitivity of the classifier to fluctuations in the gas quantity and thus also an influence on the roller mill run.
  • this disadvantageous effect can be referred to as a "bypass fraction", with fine particles which have once been pushed outwards against the classifier wall in a strand of material Have more opportunity to be brought into the actual classifier zone, i.e. near the sight strips.
  • bypass fraction probably influences the throughput and the specific work requirements more than the ability of the classifier to produce a steep grain line in the finished product.
  • the bypass portion should be eliminated as far as possible.
  • a criterion as to how far this can be achieved can be seen in the proportion of finished or fine product that is present in the fluidized bed above the guide vane ring around the grinding table. The aim is therefore to reduce the proportion of fine material in the grinding bed as much as possible, since this inevitably leads to an increase in performance and energy savings when considering the combination of the roller mill classifier.
  • the aim is therefore to distribute the regrind fed to the classifier as homogeneously as possible and at a uniform speed over the entire rotor height of the classifier.
  • the regrind obtained in a reduction process is fed to a classifier in an ascending gas flow.
  • the classifier has an upper, central fine material outlet and a coarse material discharge sloping radially outwards as well as radially and axially adjustable blind devices, by means of which different flow velocities and separations are to be made possible.
  • the invention is based on the object, especially design a Roller mill air classifier in relation to the total energy requirement of the system efficiently, the gas flow rates can be reduced in relevant areas.
  • An essential feature of an air flow classifier according to the invention with a centrally provided riser pipe for the ascending gas regrind flow can be seen in the fact that the coarse and fine material are discharged from the sighting space separately from the ascending gas regrind flow in external return lines or discharge channels .
  • the viewing area between the largely vertical viewing strips and the inner housing wall of the classifier is designed with cone-shaped, ring-like blind segments, which are provided in several stages at the level of the classifying zone.
  • These blind segments are moved, for example directly on the inner wall of the classifier housing or attached to the inner wall using spacers.
  • the general alignment of these blind rings downwards and inwards means that the gas regrind flow, which falls downwards on an upper blind level between the blind and the inner wall of the classifier housing, is fed inwards again on the lower blind level and thus again fed to the screening process is, so that just fine particles can be classified excellent.
  • the fine material particles are guided through the sight strips into the sight basket and down through the bottom opening of the classifier, which surrounds the riser in a ring, wherein a largely horizontal gas discharge channel can be provided in the lower area of the classifier.
  • the gas discharge duct expediently has fines collecting channels, as a result of which downstream filters are relieved.
  • the coarse material thrown outwards in the classifying chamber by the centrifugal forces is collected approximately in the form of a funnel and led downwards, this being done via external return lines, which are provided approximately in the form of an arc in the lower region of the classifier and suitably return the coarse grain to the actual mill via cellular wheel locks.
  • roller mill air flow classifier according to the invention is therefore characterized by a clear separation of the gas and material flows, a multiple supply to the classification process being realized as a downflow classifier with an energy-saving design.
  • the carrier gas regrind flowing upwards in the central riser pipe is mushroom-like channeled in the upper area of the classifier housing by a downwardly directed distributor cone and the riser pipe, which widens upwards to the diameter of the rotor, with a somewhat tapering flow channel. It is particularly advantageous if, in the deflection area of this channeling, there are approximately radially directed vanes, for example on the distribution cone, which promote a radial and tangential outflow.
  • the actual sight strips of the centrifugal basket or the rotor are suspended around the height of the outflow channel via aerodynamically shaped driver bolts.
  • a few such driving bolts are sufficient here, while the viewing strips arranged underneath via an annular disc are designed in accordance with the classification requirements, taking into account the material to be processed and the rotational and gas speeds.
  • Air flow classifier with a speed of approx. 12 m / s for cement raw material.
  • the cylindrical outlet cross-section in the area of the driving bolts that is to say between the rotor cover disk and the upper ring disk for the viewing strips, can be designed in such a way that a relatively low flow velocity is possible there.
  • speeds of 6 m / s to 3 m / s can be set in the area of the actual viewing area.
  • the flow in the horizontal exhaust duct can also be kept very low, for example in the range of 5 m / s. As a result, the wear on the material and the pressure loss can be significantly reduced.
  • the blind devices provided in the viewing area can be closed rings, but preferably ring segments, the steps of the blind devices lying one below the other being provided radially offset from one another.
  • ring segments for feeding the regrind inwards are again attached below the free arch areas of the higher blind level.
  • an external material supply can be provided in the upper part of the classifier, the cover plate of the rotor then expediently functioning as a spreading plate.
  • the air flow classifier 10 shown in axial section in FIG. 1 is arranged above the mill housing 31, for example a roller mill 30.
  • a central riser pipe 1 which starts from the mill housing 31 via a tapering section 33, the carrier gas regrind flow 40 is transported vertically upwards into the classifier head.
  • a classifier rotor 5 with a smaller diameter and largely vertical sight strips 51 is present in the classifier housing 14 in the classifier housing 14, on the one hand.
  • This classifier rotor 5 is driven via the rotor axis 15 mounted in the upper part 7 of the classifier.
  • the closed rotor cover plate 2 is arranged below it, which in the case of an external, upper material inlet 16 acts as a spreading plate 17.
  • a cellular wheel sluice 8 can be provided upstream of the material inlet 16. Suspended on the underside of the rotor cover disk 2 is a downwardly directed distributor cone 19. In terms of flow, this distributor cone interacts with the riser pipe extension 21, which begins approximately halfway up the centrifugal basket.
  • driver bolts 6 which can also have a circular cross section, are connected in a rotationally fixed manner to the rotor cover disk 2.
  • annular disc 3 is attached to which the vertically downwardly extending classifying strips 51 are attached.
  • the classifier rotor 5 has a larger diameter than the riser pipe 1, the classifier rotor 5 being open in the bottom area, so that an annular opening 24 is present for the fine material emerging downwards.
  • approximately radially oriented vanes 18 are suitably attached to the underside of the rotor cover disk 2 in order to improve the material distribution and to transfer the channeled ascending flow 20 into a rotating movement.
  • a relatively low speed can be set in the outlet area 23 or in the deflection area of the ascending gas material flow, which e.g. can be in the range of 5.5 m / s.
  • the radially and tangentially deflected carrier gas regrind flows into a falling flow in the classifying chamber 12, which is formed between the inner wall of the classifier housing 14 and the classifying bars 51.
  • several steps of blind segments 4 are installed on the wall side in the viewing space 12 with an inclination inward and downward.
  • These blind segments 4, which are fastened in the form of a ring or a ring segment to the inner wall of the classifier housing 14, are fastened directly to the inner wall in a preceding stage and, in a subsequent stage, offset to the inner wall via spacers 13.
  • the regrind entering the classifying chamber 12 can be fed several times to the actual classifying process.
  • Coarse-grained semolina can be guided, for example, on the inner wall through the radial gap to the next stage of the blind segments and are there, however, again fed to the sighting process in the area of the sight strips 51.
  • the blind segments 4 therefore bring about an even distribution of the gas flow over the entire rotor height, so that a more efficient sighting is achieved by homogenization and multiple feed lines.
  • the inclination of the conical blind segments 4 is required a precise coordination with the other sighting components, such as gas flow, rotation speed, etc., in order to prevent deposits on these blind segments.
  • the coarse sizes 42 flow downward from the viewing space 12 into the conical collecting funnel, the coarse material being fed to the actual mill housing 31 and the grinding bowl via arcuate return lines 32 with cellular wheel locks 9 interposed therebetween.
  • a part of the coarse size can also be derived directly from the collecting funnel 11.
  • the fine material 41 passing through the viewing strips 51 passes downwards via a chute 26 adjoining the bottom opening 24 of the viewing basket 3.
  • this exhaust air duct 44 has fines collecting channels 45 in the lower region. Part of the fine material 41 can already collect in these fine material collecting troughs 45 due to the relatively low exhaust gas flow of approximately 5 m / s. As a result, downstream filters are relieved and the entire gas flow is considerably reduced in terms of energy.
  • the concept of the air flow classifier 10 according to the invention therefore improves the specific energy requirement per quantity of material carried through, particularly in the case of an integrated design with a roller mill provided underneath, the material flow being reduced due to the low flow velocities.

Landscapes

  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)
  • Combined Means For Separation Of Solids (AREA)
  • Rolls And Other Rotary Bodies (AREA)
  • Disintegrating Or Milling (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)
  • Motor Or Generator Cooling System (AREA)
  • Compressor (AREA)
  • Finger-Pressure Massage (AREA)
EP90122986A 1990-02-19 1990-11-30 Dynamischer Wälzmühlen-Luftstromsichter Expired - Lifetime EP0443119B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4005031A DE4005031C1 (en) 1990-02-19 1990-02-19 Dynamic wind sifter for roller mill - has central, restricted riser for air material mixt. flow with downwards deflection in top region of sifter rotor
DE4005031 1990-02-19

Publications (3)

Publication Number Publication Date
EP0443119A2 EP0443119A2 (de) 1991-08-28
EP0443119A3 EP0443119A3 (en) 1992-02-26
EP0443119B1 true EP0443119B1 (de) 1994-06-15

Family

ID=6400403

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90122986A Expired - Lifetime EP0443119B1 (de) 1990-02-19 1990-11-30 Dynamischer Wälzmühlen-Luftstromsichter

Country Status (13)

Country Link
US (1) US5115989A (lv)
EP (1) EP0443119B1 (lv)
JP (1) JPH07106341B2 (lv)
AT (1) ATE107193T1 (lv)
CA (1) CA2036510C (lv)
DE (2) DE4005031C1 (lv)
DK (1) DK0443119T3 (lv)
ES (1) ES2056350T3 (lv)
LT (1) LT3222B (lv)
LV (1) LV10402B (lv)
RU (1) RU2014891C1 (lv)
UA (1) UA11094A (lv)
ZA (1) ZA911125B (lv)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5547133A (en) * 1993-12-23 1996-08-20 Rogers; Lynn Manufacture process for ground oat cereal
US6260708B1 (en) * 1996-10-18 2001-07-17 Hosokawa Alpine Aktiengesellschaft Method for air classification of toner
DE102008038776B4 (de) 2008-08-12 2016-07-07 Loesche Gmbh Verfahren zur Sichtung eines Mahlgut-Fluid-Gemisches und Mühlensichter
CA3079989C (en) 2017-12-04 2023-03-28 Goldcorp Inc. Low energy process for metal extraction

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1806980A (en) * 1931-05-26 Ptjlvebizeb
US1623040A (en) * 1927-04-05 Method and apparatus for grading solid materials
CH1557A (de) * 1889-09-27 1890-02-14 Mumford Thomas William Basset Verbesserter Apparat, um die Luft von Staub oder anderen mechanischen Beimengungen zu reinigen
US857988A (en) * 1906-07-28 1907-06-25 James W Fuller Jr Air-separator for pulverizing and grinding mills.
GB372600A (en) * 1930-06-23 1932-05-12 Clarke Chapman Ltd Improvements in pneumatic apparatus for the separation and grading of solid pulverulent material
US2909330A (en) * 1954-09-30 1959-10-20 Hardinge Harlowe Pulverizing mill and process of pulverizing material
US3090487A (en) * 1962-04-05 1963-05-21 Sturtevant Mill Co Method and apparatus for sizing solid particles
US3306443A (en) * 1964-02-19 1967-02-28 Sturtevant Mill Co Vacuum aspirator mechanism with conical barrier element
DE3202054A1 (de) * 1982-01-23 1983-08-04 Steag Ag, 4300 Essen Kohlenmahlanlage mit griessruecklauf und abtrennung von pyrit und bergen

Also Published As

Publication number Publication date
RU2014891C1 (ru) 1994-06-30
ES2056350T3 (es) 1994-10-01
EP0443119A3 (en) 1992-02-26
CA2036510C (en) 1997-05-06
ATE107193T1 (de) 1994-07-15
LTIP433A (en) 1994-10-25
DE59006151D1 (de) 1994-07-21
JPH06206050A (ja) 1994-07-26
LT3222B (en) 1995-04-25
LV10402A (lv) 1995-02-20
CA2036510A1 (en) 1991-08-20
DK0443119T3 (da) 1994-10-24
ZA911125B (en) 1991-11-27
JPH07106341B2 (ja) 1995-11-15
LV10402B (en) 1995-04-20
DE4005031C1 (en) 1991-08-08
US5115989A (en) 1992-05-26
UA11094A (uk) 1996-12-25
EP0443119A2 (de) 1991-08-28

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