<<
>>

the analysis of designs pomolnyh assembly units and directions of their is constructive-technological perfection

Ways of levigating of building materials and the equipment applied to this purpose it is rather numerous and it is various. However only rather few of them are intended for reception of levigated powders.

It is necessary to notice, that basically for the decision of the given problem pomolno-classification complexes are applied. At creation of similar complexes besides krupnosti and properties of levigated raw materials on a choice of the assembly unit of a grinding indicators of a ready product [12-18] essentially influence.

The important indicators of process of a grinding and effective work of the corresponding equipment are absence of difficult and bulky knots, insignificant power inputs, compactness, working life etc.

Assembly units applied now for a grinding have both advantage in front of other assembly units, and a number of lacks. All known designs pomolnyh assembly units at destruction of particles of a levigated material use principles, first of all blow, razdavlivanija, to a lesser degree splittings and frettings. Thus in a material particle the loadings exceeding forces of intermolecular cohesion are created. Thereof in a material particle cracks are formed - the particle collapses. It is essential to raise efficiency of destruction of a particle of a material and to lower a consumption of energy probably at the expense of creation in them of breaking loads. Thus the consumption of energy decreases, and productivity increases three times. As it is a question of particle sizes of an order 5 - 50 microns, to create in the foreseeable future industrial assembly units with use of a way of a rupture of particles of a material it is not obviously possible. Therefore in the near future it is a question only about
Perfection of installations working now for the purpose of increase of their reliability and profitability [6, 8, 10].

In process of development of technics, changes of requirements to levigated powders, mills become more effective, their grading - is more various. Designing requirements assume unweighting of a choice of mills in each concrete case of an industrial use. Various variants of ordering are resulted in works [12 - 18].

The most widespread grading of mills - on a way of destruction in them of materials.

One mills are intended for a rough grinding, other mills - for a fine grinding. There is a wide spectrum of the equipment on which it is possible to receive powders of a various subtlety.

For a grinding, both in the industry, and in laboratory practice apply mills of following types - drum-type, srednehodnye, tsentrobezhno-shock, dezintegratornye, vibrating and jet. From various references it is known, that there is no universal car for a grinding, meeting all requirements even in a narrow range of problems [156].

Despite wide application of pebble mills which are the base equipment of the majority of the enterprises for a cement making, they have a number of lacks: big massogabaritnye indicators, complexity of the main knots, presence of stagnant working areas in pomolnyh chambers, low EFFICIENCY [30].

Insignificant high-speed characteristics of movement of grinding loading in pebble mills have led to working out pomolnyh assembly units, in which loading movement most intensively. To this requirement to the full answer vibromelnitsy, which are more reliable (fig.

1.1) [27].

It is known for the workings out vibromelnits experimental plant VNIIkrovli (Moscow) which makes two-chamber mills productivity to 7 t/ch and an enclosed volume 0,7м3 [78].

Drawing 1.1. Schemes of vibrating mills:

- The inertial; - giratsionnaja; 1 case; 2 grinding bodies; 3 debalansnyj the bulwark;

4 springs; 5 ekstsentrikovyj the bulwark; 6 counterbalances

However vibrating mills concede to installations with great dispatch - reflective action on productivity, power inputs and demand preliminary levigating of a material by the sizes to 3 - 5 mm [78], therefore the given mills cannot be independent grinders for a fine grinding of materials.

High energonaprjazhennost (8 - on 10 дм3) owing to numerous interactions of a levigated material and grinding bodies the complex of actions for chilling of the case of a mill [18] compels to spend 10 kw.

Considerable enough interest is shown now to valkovym srednehodnym to mills (on the western grading - vertical mills) (rice 1.2). The largest chetyrehvalkovaja a vertical mill is designed and made by firm "Polysius" in 1990 in Paris for firms "TongYangCement" (South Korea) [24].

In our country vertical mills are issued on a mill of heavy mechanical engineering (the Samara area) by productivity to 35 t/ch, thus the quantity valkov varies from 2 to 4 [24].

Working life of basic knots of a mill is a weak link and limits majority life cycle valkovyh srednehodnyh mills [34].

As the grinding in valkovyh srednehodnyh mills is carried out by a principle razdavlivanija and frettings the given assembly units are applied basically at raw materials grinding.

The industrial practice shows expediency of application of roliko-pendular mills in relation to another srednehodnym to mills [24].

Drawing 1.2. The scheme valkovoj srednehodnoj mills (vertical):

1 frame; 2 rotating plate; 3 valok razmolnyj; 4 broneplity; 5 separator;

6 compartment for not crushed out materials; 7 frame

Now widely apply a press-valkovye grinders (PVI) [126].

It is necessary to notice, that the greatest efficiency possess PVI, in common working with trumpet mills [127]. At specific power inputs nearby 3 kVtch/t, 30 - 40 % of a material on an exit from PVI have the sizes less than 100 microns [127].

As a whole it is possible to note advantages a press-valkovyh of grinders: insignificant massogabaritnye indicators, insignificant power inputs, noiselessness of work. In economic plan PVI at a grinding are more favourable,
Than srednehodnye mills. One of lacks PVI is that the given grinders work only complete with separators.

Recently the increasing application is found by mills of shock action.

Developed in IGHTU dezintegratornaja installation [24] (fig. 1.3) includes the case 1, being in it on one horizontal axis rotating baskets 3 and 5 with setpins of the round form 4, levigating elements 6 which are rigidly fixed on an internal part of a rotor.

On periphery of the chamber of a grinding are fixed otbojnye slabs 2. A principle of action of installation the following. Disks 3 and 5 with levigating elements 4 and 6 rotate from electric motors by means of klinoremennyh transfers.

The raw materials go to the central part of the chamber of a grinding dezintegratora. Here material particles are exposed to high-speed impacts from setpins 4. The greatest speed of impact possess beat 6 which carry out additional levigating.

Drawing 1.3. Combined dezintegrator.

1 case; 2 otbojnye slabs; 3, 5 baskets; 4 setpins; 6 beat; 7 tubular bulwark;

8 end cap; 9 reciprocating screw; 10 unloading aperture

Having passed an operative range otbojnyh the slabs 2, the ready product unloads through a branch pipe 10.

In the given design dezintegratora the quantity of impacts of particles of a material with shock bodies of the chamber of a grinding and time of their impact essentially increases.

Thereof the subtlety of a ready product in 1,5 times [24] raises. With great dispatch-reflective mills.

One of the basic lacks of with great dispatch-reflective mills is the raised deterioration shock beat and otbojnyh slabs [134], therefore increase of life cycle of executive elements of the given mills has an actual meaning. Besides, the important point of development of the given type of mills is grinding and grading combination. Also significant actions in respect of increase of an overall performance of with great dispatch-reflective mills are increase of high-speed shock characteristics along with increase in quantity of impacts, the organisation of rational trajectories of movement of particles of a material in the grinding chamber. Productivity (throughput) of the given mills directly is interrelated to diameters of a rotor and the case [134]. The increase in throughput of the first rotor leads to increase in dimensions and installation masses at the central loading of a material.

On fig. 1.4 the mill with possibility of grading of a material in the chamber of a grinding [46] is presented rotornaja.

Drawing 1.4. Rotornaja a mill with the lotic laminate sizing machine:

1 case; 2 bottom; 3 electric motor; 4 flange; 5 cover; 6 nutritious branch pipe;

7 unloading branch pipe; 8 otbojnye plates; 9 reflective rods; 10 disk; 11 blades

The mill works as follows. The disk 10 rotates from the electric motor 3. The Initial material moves on a disk 10, then by means of blades 11 is dispersed towards reflective rods 9 where there is an impact. Besides, by means of a branch pipe 6 in a mill air which directs a material to an unloading branch pipe 7 moves.

Thus, in the given installation the grinding is combined with material grading on a ready product and krupku which comes back on domol [47].

For razmola plastic materials at the Ivanovo state himiko-technological university various designs of vortical mills in which the material is levigated in turbulent air currents [88] have been created.

Advantages of rotorno-vortical mills: compactness, insignificant deterioration of executive powers, possibility of thermal processing of raw materials during a grinding.

Lack of work RVM at considerable productivity are high power inputs and complexity of the instrumentation.

Necessity to reduce namol as a result of wear process of working bodies explains working out and research of the jet mills realising self-levigating of particles of a material in counter streams of air or vapour (fig. 1.5) [4, 146]. Speed of particles reaches values over 200 km/s, after impact of a particle by air stream go to a rotor-qualifier operative range. Large particles go on domol, the particle size of a ready product varies from 3 to 40 microns [4, 5].

1 pomolnaja the chamber; 2 loading chamber; 3 nozzle of a pressure air; 4 razgonnaja a tube;

5 storage bin of an initial material; 6 pipeline for tap of a levigated material

Now jet mills classify the such

In the image [146]:

- Mills with a motionless slab;

- Mills with a tangential supply of gas;

- rotivotochnye jet mills.

Besides, there is a following grading:

- With a consecutive grinding and grading;

- With the combined pomolno-classification system.

Productivity of jet mill С1-0.20-У-01 is equal 1 t/ch, thus levigated material has the sizes to 0,25 mm, and on an exit from a mill - 1-5 microns. Pressure of gas makes 0,7 - 0,8 MPa.

At enough high for such class of grinders of productivity in the given design there is an essential lack - necessity of preliminary levigating (to 250 microns) an initial material submitted to a grinder, that in turn leads to input in a production process of additional operation of thin levigating and, as consequence, to increase in power inputs. In some modern designs of jet mills use a combination jet and dezintegratornogo impact principles on a levigated material in the grinding chamber.

So, experts of Kommunarsky mountain-metallurgical institute develop a jet mill with opposite directed streams, intended for superthin levigating of the loose materials, characterised by the raised efficiency [4, 5, 146].

Now the development was received also by foreign designs of jet mills. Firm Alpine (Germany) makes mill AFG which has productivity from 2 to 10 t/ch and specific expenses of energy, on 30 - 35 % smaller in comparison with similar mills. The given installations have found application in the industry of building materials, a paint and varnish industry by manufacture of pigments, medicine and so forth [4, 5].

Despite it, the increase in quantity of nozzles in the chamber of a grinding of a jet mill leads to increase of power inputs that affects production cost price.

Jet mills JOM (Japan) to 1 t/ch provide with productivity reception of a ready product with the set grain size distribution, are easy-to-work, work with various energy carriers. [4, 146]. A lack of the given mills is the raised deterioration of an inside face of the chamber of a grinding.

Thus, it is possible to conclude, that simplicity of a design, absence of rotating knots predetermine advantages of jet mills in relation to a number of the grinders providing reception of a ready product from 5 to 40 micron. For the purpose of life cycle increase certain lots (razgonnye tubes, the grinding chamber) are carried out from wearproof materials. These actions raise life cycle of jet mills [4, 5].

Restrained application of jet mills speaks, first, a problem of acquisition of necessary speeds of movement in razgonnyh knots large particles of a material, and secondly, necessity of dispersal till speeds of destruction of a crushed fines. Thus there is a certain complexity of allocation of a ready product from an air stream. Therefore the given mills are applied basically to a grinding of materials by the initial sizes to 5 mm to the sizes of a ready product from 5 to 40 microns [4, 5].

Hence, as a result of the given analysis of technics and technology of levigating of materials it is possible to tell, that everyone pomolnaja installation corresponds to performance of specific targets at reception of disperse products, having both advantages, and lacks [2, 134].

Proceeding from the aforesaid, creation and research of installations for a grinding with high high-speed characteristics of impact on a material, particles providing mechanical dispersal and their self-levigating in counter and crossed streams [17, 134] is necessary. Such pomolnymi

Installations are centrifugal counterflow mills, at which specific expenses of energy make (15-20 kw ch/t) at enough small dimensions (rice 1.6).

Drawing 1.6. A centrifugal counterflow mill:

1 case; 2 tangential channel; 3 slab; 4 bulwark; 5 disk; 6 razgonnye shovels;

7 loading branch pipes; 8 vygruzochnyj a branch pipe

Throughout last years NPTS "Ivenergomash" (of Ivanovo) makes the centrifugal counterflow mills combining a grinding and grading of a material. Given pomolnye installations provide counter movement of streams of particles of a material to similarly work of jet grinders, but as the energy carrier the pressure air acts not, and mechanical dispersal of particles is carried out. The given installations are most effective at a grinding soft and an average strength of materials [65, 134].

The centrifugal counterflow mill differs simplicity and compactness of a design, smaller specific expenses of energy (in 1,5 - 2 times), possibility of regulation of a subtlety of a product of a grinding. The given mills have insignificant deterioration of working bodies (less than 0,05 %), however the area of their application is limited to a limit of moisture content of raw materials (to 4 - 5 %).

All aforesaid gives the base to investigate centrifugal counterflow mills for levigating of limestone and other abrasive materials for the purpose of reception of a ready product with the set grain-growing structure.

The deterrent of successful use of centrifugal counterflow mills in the course of levigating is the wide range of a grain size distribution of a ready product [65, 134].

Thus, working out and research of new designs of centrifugal counterflow mills for the purpose of an intensification of a grinding and narrowing of a grain size distribution of a ready product are represented actual [134].

The important directions of increase of efficiency of a grinding in centrifugal counterflow mills are the organisation of rational trajectories of movement of material streams before their self-levigating in the grinding chamber [65, 134].

1.2

<< | >>
A source: CHUNGUROVA TATYANA LEONIDOVNA. PERFECTION of the DESIGN And GRINDING PROCESS In the CENTRIFUGAL COUNTERFLOW MILL. The DISSERTATION on competition of a scientific degree of a Cand.Tech.Sci. Belgorod - 2017. 2017

More on topic the analysis of designs pomolnyh assembly units and directions of their is constructive-technological perfection:

  1. 4.2 Granulometrichesky research of structure of assembly units
  2. the analysis of techniques of definition of the basic is constructive-technological parametres in high-speed shower mixers with a vertical arrangement lopastnogo the bulwark
  3. 4.3 Definition of a surface tension of various fractions of assembly units of a ground marl
  4. 2.2. The analysis of changes and some directions of perfection of the Russian criminal antiterrorist legislation
  5. § 2. Other directions of activity of National assembly of Byelorussia
  6. research of is constructive-technological decisions of geodetic domes
  7. 5.1.2 Choice of variants of the is constructive-technological decision of geodetic domes
  8. Lu Bo. Russian expressional syntactic designs as communicative units, 2015
  9. offers for choice variants constructive the technological decision.
  10. research of is constructive-technological decisions of spherical structural modules
  11. the Appendix № 2 Analysis of data of expert interrogation by definition of directions of perfection of legal regulation of institute of is conditional-preschedule clearing
  12. IS CONSTRUCTIVE-TECHNOLOGICAL DECISIONS OF PRECAST SPHERICAL SHELLS
  13. research of is constructive-technological decisions of integral envelopments from prestressed panels
  14. RESEARCH OF IS CONSTRUCTIVE-TECHNOLOGICAL DECISIONS OF GEODETIC DOMES-COVERS.
  15. THE CHOICE OF IS CONSTRUCTIVE-TECHNOLOGICAL DECISIONS OF PRECAST GEODETIC DOMES
  16. research of is constructive-technological decisions of spherical shells from prestressed panels.