RU2649145C2 - Grinding tacking for disk mill - Google Patents

Abstract

FIELD: desintegrators and crushing devices.

SUBSTANCE: invention relates to a grinding head for a disc mill and can find application in the grinding of various fibrous materials. Grinding headset contains rotor and stator disks, the working surface of which is divided by intermediate grooves into sectors. Grooves are closed at the entrance to the grinding cavity and open at the outlet from it. Grooves are formed by the active side wall of the knife, opposite to it the passive side wall of the knife and the lower plane of the base. Interfaces of the base with the active wall are given the shape of concave fillets with a radius equal to 0.25 of the height of the knife, while the active side walls of the interlocking grooves, which are closed on the entrance side, are tilted with respect to the passive ones by an angle α, the value of which is 2ϕ<α<2.5ϕ, where ϕ – the angle of friction of the pulp mass on the knife surface.

EFFECT: grinding headset allows you to intensify the grinding process, improve the quality of grinding, as well as to reduce specific energy costs and increase productivity.

1 cl, 2 dwg

Description

The invention relates to a grinding set for a disk mill and can be used in the pulp and paper industry at the stage of fine grinding.

Known grinding headset disk mill, including rotor and stator disks, the working surfaces of which are equipped with knives, alternating with through mezhnevyh grooves [1].

A disadvantage of the known headset is that the inter-knife grooves are through. Due to this, in the intercutaneous cavity:

- overpressure of the suspension slightly exceeds atmospheric;

- mass acceleration reaches 1500-2000 g due to the large peripheral speed of the rotor disk;

- in one cycle, most of the suspension passes through the grooves without falling into the inter-knife gap, and the fibers contained in it do not undergo grinding in the form of mechanical and hydrodynamic effects from the cutting edges of the knives.

Known grinding headset of a disk mill, including rotor and stator disks, the working surface of which is divided into sectors equipped with knives parallel to one of the radial side generators of a single sector, as well as inter-knife and intersector grooves, closed alternately from the input and output sides and limited by the side walls of adjacent knives [2].

The disadvantages of the known headset are the following features of the intercutaneous grooves:

- symmetry of the cross-sectional profile;

- the verticality of the side walls;

- parallelism of the side walls.

One of the side walls of the intercutaneous grooves is active, because it performs three main working functions:

- perceives pressure loads arising from the continuous contact of the flows of the fibrous suspension in the form of normal components of the peripheral forces developing during the rotation of the rotor disk;

- transports the fibrous mass along the groove, from the entrance to the grinding cavity of the headset, to the exit from it under the action of centrifugal force, which develops when the rotor disk rotates, forcing the mass to move along the grooves through the grinding cavity of the headset;

- serves as a supporting surface for advancing the adjacent highly consistent layer of fibrous suspension, from the bottom up, towards the interdisk gap under the action of the normal and tangential components of the component of the circumferential force.

Opposite side walls of the inter-knife grooves, which do not fulfill the main working functions, are passive.

Taking these features into account, it can be assumed that the symmetry of the cross-sectional profile of the inter-knife grooves does not contribute to the advancement of the pulp adjacent to the active walls from the bottom upward towards the inter-disk gap.

It should also be noted that the pressure in the grooves closed on the outlet side is higher than the pressure in the grooves closed on the inlet side.

In this regard, we can assume that in the known solutions [1, 2] for the successful advancement of the pulp from the bottom up, towards the interdisk gap, the geometry of the active walls of the intercutaneous grooves closed from the side:

- exit and open from the entrance side is quite acceptable, because the pressure in the groove is higher than at the outlet;

- entrance and open from the exit side does not seem to be an ideal solution, because the pressure in the groove is less than the outlet.

The closest in technical essence solution is a grinding mill headset of a disk mill, including rotor and stator disks, the working surface of which is divided by intermediate grooves closed at the entrance to the grinding cavity and open at the exit from it, into sectors parallel to one of their radial forming straight knife, alternating with inter-knife grooves, closed alternately on the input and output sides, limited by the active side wall of the knife, opposite to it - passive and lower plane the base bone, the interface of which with the active wall is given the shape of concave fillets with a radius of curvature equal to 0.25 ... 0.4 of the height of the knife [3].

The advantage of the well-known headset [3] is the presence of concave fillets, which to some extent promotes the movement of the fibrous suspension from the bottom up, towards the interdisk gap.

The disadvantages of the solution [3] are similar to the disadvantages of the known solutions [1], which are the features of the inter-knife grooves closed on the entrance side:

- the verticality of the side walls;

- parallelism of the side walls.

- reduction, compared with the known solution [1], the cross-sectional area of the inter-knife grooves due to the introduction of fillets.

The indicated features of the sets [2, 3] make it difficult to circulate the suspension from grooves closed on the inlet side to adjacent grooves closed on the outlet side. This means that a smaller part of the suspension passes through the inter-knife gap of the grinding annular cavity in one cycle. During this time, the rest, most of the suspension, the most distant from the gap along the height of the grooves, passes through them, without falling into the grinding zone at all and without being subjected to significant force action, i.e. practically does not grind. Accordingly, it is practically not exposed to force.

The invention solves the problem of intensification, improving quality and reducing specific energy costs of the grinding process.

The technical result consists in the intensification of the grinding process and improving the quality due to the fact that during the passage of the fibrous suspension through the grinding cavity of the headset, the effect of circulation from the grooves closed on the inlet side to the adjacent grooves closed on the outlet side of the disk increases significantly.

To achieve the specified technical result in a grinding set of a disk mill, including rotor and stator disks, the working surface of which is divided by intermediate grooves closed at the entrance to the grinding cavity and open at the exit from it, into sectors parallel to one of their radial generatrix with straight knives and interknives grooves, alternately closed from the entrance and exit sides, limited by the active side wall of the knife, opposite to it - passive and lower plane of the base, places According to the invention, the active side walls of the intercutaneous grooves closed at the entrance side are inclined with respect to the passive ones by an angle a, the value of which is equal to

,

,

where ϕ is the angle of friction of the pulp against the knife surface.

Due to the inclination of the active side walls of the inter-knife grooves closed on the entrance side by an angle α relative to the passive ones, the cross-sectional area of the grooves and the passage through it of the specific volume of the suspension will increase significantly.

транспортирующая способность активных боковых стенок канавок, закрытых со стороны входа, превалирует над способностью к продвижению по ним прилегающего высококонсистентного слоя волокнистой суспензии, снизу вверх, по направлению к междисковому зазору.At

the transporting ability of the active side walls of the grooves closed on the inlet side prevails over the ability to advance an adjacent highly consistent layer of fibrous suspension along them, from the bottom up, towards the interdisk gap.

Therefore:

- a smaller part of the suspension, especially flowing near the inter-knife gap, is guaranteed to pass it under the influence of flow turbulence and pressure drops;

- the rest, most of the suspension, especially the most distant in height of the groove from the gap, passes through it, almost without falling into the grinding zone.

A smaller part of the suspension in the grinding zone is subjected to intense force first, from the side of the cutting edges of the knives, and then from the side of their adjacent working surfaces, into which it penetrates the gap. Most of the suspension, which did not fall into the grinding zone, is not subjected to force, i.e. does not grind.

соотношение транспортирующей способности активных боковых стенок канавок, закрытых со стороны входа, и продвигающей способности по ним прилегающего высококонсистентного слоя волокнистой суспензии, снизу вверх, по направлению к междисковому зазору, наиболее оптимально. Поэтому, при данном неравенстве, за время прохождения размалывающей межножевой полости по канавке, закрытой со стороны входа, практически весь объем суспензии проходит через междисковый зазор, где и подвергается интенсивному силовому воздействию.At

the ratio of the transporting ability of the active side walls of the grooves closed on the inlet side and the promoting ability of the adjacent highly consistent layer of fibrous suspension along them from the bottom up to the interdisk gap is most optimal. Therefore, with this inequality, during the passage of the grinding inter-knife cavity along the groove closed on the inlet side, almost the entire volume of the suspension passes through the inter-disk gap, where it is subjected to intense force.

способность активных боковых стенок канавок, закрытых со стороны входа, к продвижению прилегающего к этим стенкам высококонсистентного слоя волокнистой суспензии снизу вверх, превалирует над их транспортирующей функцией. Это приводит к чрезмерной разработке волокон и, как следствие этого, к снижению эффекта их фибрилляции и к усилению эффекта рубки и резания.At

the ability of the active side walls of the grooves closed from the entrance side to advance the highly consistent layer of fibrous suspension adjacent to these walls from the bottom up prevails over their transport function. This leads to excessive development of the fibers and, as a consequence, to a decrease in the effect of their fibrillation and to an increase in the effect of chopping and cutting.

In FIG. 1 shows a frontal projection of the working surface of a disk mill headset. The grinding surfaces of the knives are shaded.

In FIG. 2 shows a cross-section AA of a single knife and adjacent inter-knife grooves. Shown by arrows:

single, linear (Fig. 1) - the direction of movement of the fibrous suspension in the knife grooves (Fig. 1, 2);

double, circumferential (Fig. 1) and linear (Fig. 2) - the direction of rotation of the rotor.

The grinding set of the disk mill includes rotor and stator disks with working surfaces divided into sectors 1, equipped with knives 2, parallel to one of the radial side generators 3 of unit sector 1, as well as inter-knife 4, 5 and intersector 6 grooves.

Inter-knife grooves 4 are closed on the input side 7 and open on the output side 8.

The inter-knife grooves 5 are open on the input side 7 and closed on the output side 8.

Intermediate intersector grooves 6 are closed at the entrance 7 to the grinding cavity and open at the exit 8 from it.

Inter-knife grooves 4 alternate with inter-knife grooves 5 and intersector 6 grooves (see Fig. 1).

Each of the grooves 4, 5 and 6 is bounded by active 9, passive 10 by the side walls of adjacent knives 2 and the lower plane of the base 11 (see section AA, Fig. 2).

The junction points of the active walls 9 with warp 11 are given the shape of concave fillets 12 with a radius of curvature (in Fig. 2 indicated by the letter r) equal to 0.25 of the height of the knife (in Fig. 2 indicated by the letter h).

(см. разрез А-А фиг. 2), где ϕ - угол трения волокнистой массы о ножевую поверхность.In contrast to the known headsets in the proposed solution, the active side walls 9 of the inter-knife grooves 4 and 6, closed on the input side 7 and open on the output side 8, are inclined with respect to the passive ones - 10 by an angle

(see section AA of Fig. 2), where ϕ is the angle of friction of the pulp against the knife surface.

Grinding headset disk mill works as follows. The fibrous suspension continuously flows under pressure through the inlet circumferential edge 7 into the inter-knife 5 and intersector 6 grooves (open on its side and closed on the output side 8) and moves along them under the action of centrifugal forces and pressure drop at the input 7 and output 8 to the periphery ( figure 1 shows a single arrow). In the process of movement, the flows of the fibrous suspension are supported at the exit 8 and, under the action of the normal component of the circumferential force developed by the disk, are pressed against the active side walls 9, forming a highly consistent fibrous layer at the point of pressing.

Under the action of a lifting force equal to the pressure difference between the grooves 5, 6 (closed at the exit 8) and the grooves 4 (open at the exit 8), as well as the tangential component of the circumferential force exceeding the friction force of the fibers on the surface of the active side walls 9, this layer moves from bottom to top (in section AA, Fig. 2 is shown by a single arrow) to the inter-knife gap (in section AA, Fig. 2 is conventionally not shown).

In the process of overcoming the inter-knife gap, the pulp is subjected to force from the side of the cutting edges and the mating surfaces of the knives 2 of the rotor and stator sets. Therefore, during the passage of the grinding inter-knife cavity through the grooves 5 and 6, open from the inlet side, almost the entire volume of the suspension is guaranteed to pass through the inter-disk gap, where it is subjected to intense force. The fibrous mass that has passed the inter-knife gap moves into grooves 4 open at the exit 8, where the pressure is much lower than in the grooves 5 and 6 closed at the exit 8.

.In contrast to the known solutions in the proposed headset, in the grooves 4 and 6 (closed from the inlet side 7 and open at the outlet 8), the suspension movement mode is most optimal due to the inclination of their active side walls 9 with respect to the passive 10

.

Moreover, the ratio of the transporting ability of the active side walls of the 9 grooves 4 (closed on the entrance side) and the ability to advance along them the adjacent highly consistent layer of fibrous suspension, from the bottom up, towards the interdisk gap (in the section AA f _& g. 2 is shown by a single arrow) also most optimally.

Therefore, during the passage of the grinding inter-knife cavity along the groove 4 (closed from the inlet side 7), almost the entire volume of the suspension also passes through the inter-disk gap, where it is subjected to intense force. This leads to an intensification of the force effect on the fibrous material in one cycle, which creates the prerequisites for reducing the grinding time and specific energy consumption. The processed fibrous material is sent to the next stage of the process.

Compared with the known solutions, the use of the proposed grinding headset disc mill will allow:

- to intensify the grinding process by increasing the effect of advancing the fibrous suspension from grooves 5 and 6 (closed from the inlet side 7) into the inter-knife gap;

- to improve the grinding quality due to the most optimal ratio of the transporting ability of the working side walls of the 9 grooves 5 and 6 (closed from the inlet side 7) and the promoting ability of the adjacent highly consistent layer of fiber suspension along them, from the bottom up, towards the interdisk gap, with the prevailing fibrillation effect ;

- reduce the specific energy consumption of the grinding process by ensuring passage through the interdisk gap, during one treatment cycle in the grinding inter-knife cavity, almost the entire volume of the suspension, where it is subjected to intense force;

- to increase productivity by reducing the grinding time of one cycle of passage of the fibrous suspension of the grinding interknife cavity.

Information sources

1. SU, No. 878847, IPC D21D 1/30, application. 05/03/1979, bull. No. 41, publ. 11/07/1981

2. SU, No. 2227825, IPC D21D 1/30, B02C 7/12, application. 07/15/2003, bull. No. 12, publ. 04/27/2004

3. RU, No. 2380468, IPC D21D 1/30, B02C 7/12, application. 10/13/2008, bull. No. 3, publ. January 27, 2010

Claims (3)

Grinding headset of a disk mill, including rotor and stator disks, the working surface of which is divided by intermediate grooves closed at the entrance to the grinding cavity and open at the exit from it, into sectors parallel to one of their radial forming straight knives and inter-knife grooves, alternately closed from the side entrance and exit, limited by the active side wall of the knife, opposite to it - the passive and lower plane of the base, the places of interfacing with the active wall are given ma concave fillets with a radius equal to 0.25 the height of the knife, characterized in that the active conjugate with fillets sidewalls mezhnozhevyh grooves closed on the inlet side, inclined relative to the passive an angle α, whose magnitude is equal to 2ϕ <α <2.5ϕ, where ϕ is the angle of friction of the pulp against the knife surface.

Images