RU2220390C1 - Drying drum - Google Patents

Abstract

FIELD: construction industry, equipment designed to dry viscous, lumped materials, predominantly wet, water-clogged clays. SUBSTANCE: chains suspended freely in internal space of revolving body of drum are used in the capacity of chain screens. Their links have torus shapes with torus diameter and cross-section areas varying from link to link and links positioned within limits of single chain with successive reduction of diameter of torus and its cross-section area from point of attachment of chain to its free end. Invention makes it feasible to raise efficiency of drying process thanks to intensification of process of comminution of formed lumps of material and redistribution of flow of heat transfer agent into lower zone of drying space of drum where major bulk of wet raw material concentrates and to cleaning of working tools and internal surface from stuck material. Proposed structure of chain screens makes it possible to prolong their service life and to increase operational stability of drying drum. EFFECT: raised efficiency of drying process, prolonged service life and increased operational stability of drying drum. 6 cl, 5 dwg

Description

Technical field

The claimed invention relates to a technique for drying plastic, viscous, clumping mainly clay materials and can be used in the building materials industry, in particular in the processes of preparing raw materials for brick production.

State of the art

Known dryer drum for drying viscous and clumping materials (see copyright certificate for the invention No. 1374011, MPK F 26 B 11/04, publ. 02.15.1988, bull. No. 6), containing longitudinal peripheral blades and a chain nozzle, consisting of interconnected radial and transverse chains forming a polyhedron in the center of the drum. The chains are located right next to each other along the length of the drum and form continuous chain webs, many times sifting through which when the drum rotates, the material loosens and dries, while the arrangement of chain curtains helps to intensify the heat and mass transfer process and evenly distribute the coolant throughout the drum volume.

The specified device is effective enough for drying coal concentrates, as well as loose clay of moderate humidity.

However, when the material fed to the drying is wet clay moistened with atmospheric precipitation, the material is moved mainly by gravitational forces during the rotation of the drum, as well as by mixing by means of peripheral blades, sticking of the blades and chain partitions occurs , large clods are formed on them that do not wake up between the chains. In addition, the moist raw material entering the drum from the loading device forms a lumpy blockage in the lower part of the drum. Chains fixed at both ends, due to their limited mobility, do not contribute to breaking up the resulting lumps, which leads to insufficient disclosure of the surface of the material and, as a result, to a decrease in the efficiency of the drying process, uneven drying, and overdrying of small fractions of the raw material. Other means for loosening and grinding the material are not provided for by the construction.

The closest in design features to the claimed solution and selected for the prototype is a tumble dryer (see copyright certificate for the invention No. 983408, IPC F 26 B 11/04, publ. 12/23/1982, bull. No. 47) containing chain curtains in the middle part, a receiving-screw nozzle in the form of chain and sheet blades in the loading part and lifting sheet blades at the discharge end.

The uniformity of drying is ensured by the constant redistribution of the material in the volume of the drum by means of blades and movable chain curtains. The material is moved from the loading end of the drum to the unloading via the blades of the receiving-screw nozzle located at an angle of 50 degrees in the direction of the unloading end.

In a drying drum on.with. No. 983408 partially solved the problems of material sticking to the chain curtains and increased the drying process by supplying the drum with freely suspended chains alternating with diametrically fixed chains. Fluctuations and collisions of freely suspended and diametrically fixed chains contribute to loosening and grinding of the material, in addition, from the collision of the chains they are shaken and partially cleaned.

However, in cases of drying clay materials with a high degree of humidity, the blades of the take-up screw nozzle, partitions, brackets on which chains and chain blades and other fixed elements are fixed, undergo increased adhesion of moist material, while freely suspended chains provide loosening of the material and removal of adhering material raw materials only in the middle of the drum. As a result of sticking, the mixing process of the material worsens, the bulk of the wet raw material is concentrated closer to the inner surface of the drum (on the blades of the loading and unloading part of the drum, the attachment points of the chains, the inner walls), while the coolant is directed uniformly throughout the drying space of the drum. The drying efficiency is reduced, it is necessary to stop the device and to clean the drum elements from adhering material, which is quite laborious and associated with the use of manual labor. In addition, the chains used in the design of curtains have a short life and wear out quickly.

The essence of the claimed invention

The claimed invention solves the problem of increasing the efficiency of the drying process of mainly clay raw materials of high humidity due to the intensification of the processes of grinding material and redistribution of the coolant. At the same time, the task of increasing the stability of the device, the reliability and durability of the operation of chain curtains is being solved.

The problem is solved due to the fact that in the drying drum containing a rotating housing with loading and unloading devices located on its opposite end sections, the inner cavity of which is connected to the heat carrier source and forms a drying space in which chains are mounted, fixed at one end on the inner surface of the housing and others freely placed in the drying space, according to the claimed invention, the chain links are made toroidal with variables from s ene link to the diameter of the torus, and its cross-sectional area and are arranged within the same circuit with consequent reduction of the diameter of the torus, and its cross-sectional area of the chain attachment points in the direction of its free end.

The implementation of the chain links of variable size (diameter and cross-sectional area) and their location within the chain with a successive decrease in the size of the link in the direction of the free end of the chain allows to increase the mobility, the flaccidity of the end parts of the chains, which intensifies the process of grinding the resulting lumps and loosening of the material. Grinding and loosening of the material, in turn, ensures uniformity of drying, increases its efficiency. In addition, the increased mobility / chelosity of the chains contributes to their cleaning and cleaning the inner surface of the drum from adhering material, which leads to the stability of the device.

At each moment of time of rotation of the drum in the upper part of the drying space are freely hanging chains, and in the lower part of the chain lie on the inner surface of the housing. The placement of the largest massive links at the points of attachment to the inner surface of the drum body contributes to the fact that in the upper part of the drying space at each moment of time a large number of the largest links are concentrated, forming massive curtains that impede the advancement of hot gas flows in the upper part and deflect the coolant flow towards the bottom of the drying space of the drum, where the bulk of the raw material is concentrated. Thus, the design of the circuits made it possible to redistribute the flow of coolant, direct it downward, where the heat of hot gases is most fully transferred to the mass of material, which also contributes to an increase in the efficiency of the drying process.

Redistribution of the coolant flow is known from the prior art. However, it is carried out, for example, through the use of perforated distribution boxes (see the drying plant according to ed. St. No. 1268915 of 11/07/86), the directional coolant supply pipe (see the drying and grinding plant according to the invention patent No. 2018367). In the claimed invention, the chains perform not only the functions of grinding and loosening the material, but also the functions of the distributor of the coolant flow, which is new and unknown from the prior art.

On the other hand, the implementation of chain links of increased massiveness close to the case contributes to the fact that during periods when the chain is in its lower position, it is covered with clay on the inner surface of the case, due to the increased degree of heating of the massive links, the amount of heat that can be transferred increases links to the material in direct contact with clay. Improving heat and mass transfer conditions also helps to increase the efficiency of the drying process.

The implementation of chain links in the form of a torus is aimed at increasing the wear resistance and durability of the operation of the chain, because ordinary oval chain links are subject to rapid wear (grinding) in the area of contact with neighboring links, i.e. in the so-called “spot” of contact. The shape of the torus provides the possibility of rotation of the chain links relative to each other, therefore, the contact does not have constant contact zones, and abrasion occurs uniformly along the ring.

The design of the chains, namely the placement of the thickest massive ring at the point of attachment of the chain to the case and the redistribution of the total mass of links along the length of the chain with the shift of the most massive heavy to the place of attachment, and the lightest to the end part, provides increased wear resistance of the chain curtains, the durability of their operation , which means the stability of the device as a whole.

It is most preferable to fasten the chain to the casing by means of a bracket that is freely passed through the largest chain link and attached at both ends to the inner surface of the casing of the bracket, the dimensions of which exceed the dimensions of the said link. Such a design of the attachment node provides free movement of the chain link in the bracket, both rotational and longitudinal. The mobility of the chain link contributes to the uniformity of wear of the contacting elements - the bracket and chain link, in addition, when moving the chain link along the bracket, the latter is cleaned of adhering material. In the specific case of the implementation of the drying drum device, the brackets can be made in the form of one and a half, in which the diameter of the torus and its cross-sectional area exceed the above values of the chain link associated with it. An increase in the size of the bracket compared to the first chain link associated with it helps to increase the reliability of fastening, as the chain is quite massive, in addition, the bracket performs the above functions of the chain links, namely, it helps to block and deviate the coolant flow, heat transfer with the mass of raw materials.

In another specific case of the implementation of the device, it is possible to execute a U-shaped bracket with an elongated cross member. In this case, it is preferable that the bracket in the cross section be round, which reduces the friction forces and helps to increase the durability of operation.

The condition for promoting the flow of material along the drum body in the direction of the discharge end is the location of the staples with a turn of the plane in which the bracket lies at an angle in the direction of movement of the material flow. The elongated shape of the staples promotes mixing of the raw materials, while solving the problem of cleaning it from adhering raw materials. Thus, the bracket in the claimed solution not only performs the functions of the fastener, but also the functions of mixing peripheral blades directing the flow of material.

The most appropriate is the dispersion of the chains on the inner surface of the case in a checkerboard pattern, which allows you to evenly distribute the chain curtains in the volume of the drying space, overlapping it as much as possible.

An additional condition that allows directing the coolant flow to the lower part of the drum cavity, where the largest part of the mass of raw materials is concentrated, is to place the coolant source from the discharge end of the drum body with the horizontal orientation of the coolant supply pipe into the drum cavity, while the drum is inclined towards the discharge end where the heat source is installed. It was experimentally established that a similar placement of the heat carrier source with respect to the drum and the drum inclination of 3-5 degrees maximally orient the flow of hot gases in the direction of the lower region of the drying space.

List of drawings

Figure 1 is a General view of a drying drum, a schematic representation.

Figure 2 is a section aa from figure 1, schematically shows the location of the chain curtains in the cross section of the drying space.

Figure 3 - scan of the inner surface of the drum, shows the location of the brackets for attaching chains.

Figure 4 shows an example of the execution of the links and their location within the same chain.

Figure 5 - fragment I of figure 1, shows the change in the position of the chain link relative to the bracket during rotation of the drum:

Ia) - the relative position of the bracket and chain linking with it at a certain position of the drum,

Ib) - the same, when the drum is rotated by a certain angle in the direction of rotation shown by the arrow;

Ic) - the same, with a further rotation of the drum by another angle in the same direction of rotation of the drum.

Information confirming the possibility of carrying out the invention

The dryer drum (see Fig. 1) contains a rotating casing 1, on its inner surface free-hanging chains are fixed 2. At one end end of the casing 1, a loading device 3 is installed in the form of a receiving hopper with a screw feeder, and an unloading hopper 4 is located on the other end side and a heat carrier source or a furnace 5. The drum housing 1 is installed with an inclination towards the discharge end. The furnace 5 is installed horizontally, while the nozzle 6 for supplying the coolant to the housing 1 of the drying drum is also directed horizontally, the angle of inclination between the axes of the drum and the furnace is 4 degrees. Chains 2 are fixed on the inner surface of the drum by U-shaped, round in cross section staples 7 (see figure 2, figure 4) so that in the cross section they are located at an angle of 120 degrees relative to each other, and the surface area of the drum is scattered in a checkerboard pattern (see figure 3).

The links of the chains 2 are made in the form of round (in cross section) rings in the shape of a torus (see Fig. 4) with a diameter D of the torus and a diameter d of the cross section of the torus. The diameter D of the torus and the diameter d of the cross section, therefore, and the cross-sectional area decrease from link to link in the direction of the free, loose end of the chain. The links of the chains 2 can be made in the form of toroidal rings with a cross-section in the shape of an oval, which can further increase the wear resistance of the chains. Chains 2 are fixed on the inner surface of the drum casing 1 for the largest, largest and most massive link.

The dryer drum operates as follows.

Hot gases are supplied to the rotating drum housing 1 from the furnace 5 through the nozzle 6. The movement of the mentioned gases (coolant) is directed along arrow 8 towards the movement of the material being dried — clay, which is supplied to the rotating drum body 1 by means of a screw feeder of the loading device 3. The main coolant flow is oriented towards the lower part of the drum cavity (region 9).

Clay gradually moves to the discharge hopper 4, being subjected to thermal effects of flue gases, heated surfaces of the housing 1 and chains 2, mechanical grinding - abrasion - due to the interaction of pieces of clay with each other and the impact of clay on the clay 2. The bulk of the wet clay forms large clods, focusing in the lower part of the cavity of the drying space. Chains 2, possessing increased mobility and lumpiness, due to the location of the lightest links with the smallest diameters D and d from the side of the free end of the chain break the clods that are formed, loosen the clay. From the collision of chains 2 is their cleaning and cleaning the inner surface of the housing 1 of the drum from adhering material. Massive links 10 located near the attachment points and subsequent large links with the largest diameters D and d deflect the coolant (arrow 11) that comes up against them towards the lower wall of the inner cavity of the drum, where the bulk of the wet material is concentrated. At the same time, intense heat is exchanged between the clay and the heated chains 2, which are in their lower position, lying on the surface of the housing 1.

Moving, during rotation of the drum, along the bracket 7 (see figure 5), the link 10 of the chain 2 cleans the surface of the bracket 7 from clay adhering to it. Exhaust flue gases are discharged in the direction of arrow 12 through the hollow shaft on which the screw feeder 3 is mounted. The crushed and dried clay is removed through the discharge hopper 4.

The drum allows drying of clay with an initial moisture content of 24% to a final moisture content of 8%. The design of the chain curtains and the elements of their fastening of the inventive drying drum made it possible to abandon the use of various kinds of mixing blades that uniformly redistribute the material during drying, but are subject to increased adhesion of the wet material. At the same time, drying efficiency is ensured due to the increased mobility of the chains, aimed at grinding and loosening of the resulting lumps of material, as well as due to the most efficient and rational redistribution of the coolant flow.

The use of chains of such a design as working bodies of the drum made it possible to increase the operating life of chain curtains, increase the stability of the device, and practically get rid of the device stops for cleaning the internal cavity and working bodies of the drying drum.

Claims (7)

1. A drying drum containing a rotating housing with loading and unloading devices located on its opposite end sections, the internal cavity of which is connected to a heat carrier source and forms a drying space in which chains are mounted, fixed at one end on the inner surface of the housing, and the other freely placed in a drying space, characterized in that the chain links are made of a toroidal shape with variables from link to link with a torus diameter and its cross-sectional area and are located within the same chain with a sequential decrease in the diameter of the torus and its cross-sectional area from the point of attachment of the chain in the direction of its free end. 2. The drum according to claim 1, characterized in that the chain is attached to the casing by means of a bracket that is freely passed through the largest chain link and fastened by the ends to the inner surface of the casing, the dimensions of which exceed the dimensions of the said link. 3. The drum according to claim 2, characterized in that the bracket is made in the form of one and a half. 4. The drum according to claim 2, characterized in that the bracket is made of a U-shaped with an elongated cross member. 5. The drum according to claim 2, 3, or 4, characterized in that the brackets are mounted with a turn of its plane at an angle in the direction of movement of the material flow. 6. A drum according to any one of claims 1 to 5, characterized in that the chains are staggered on the inner surface of the housing. 7. A drum according to any one of claims 1 to 6, characterized in that the drum casing is installed with an inclination in the direction of the discharge end, on the side of which there is a heat source, made with a horizontal orientation of the coolant supply pipe into the drum cavity.

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