RU2501501C1 - Double-screw extruder - Google Patents

Abstract

FIELD: food industry.SUBSTANCE: invention is related to equipment for production of extruded products of meat-and-vegetal raw materials. The extruder contains a charging nipple, a body, two screws with drives and a matrix. Arranged in the body are channels for supply of cold and hot heat medium therein. Each screw has two compression zones with a decompression-and-extraction zone positioned between them. The first compression zone includes three sections: those of loading, compaction and dosaging. The decompression-and-extraction zone includes decompression and extraction sections. Mounted over the body section positioned downstream the decompression section is a feeder for supply of meat components having a vertical delivery screw. The second compression zone includes two sections: those of homogenisation and delivery. Within the charging section, the screws shaft and coils have a constant diameter. Within the compaction section, the screw shafts diameter conically expands while the screw coils are thickened. Within the dosaging section, the screw shafts diameter also conically expands but at a smaller angle while the screw coils are still thicker. Within the decompression section on the screw shaft there are six serially installed cams that are displaced relative each other on the rotation axis so that the cams synchronously contact each other during rotation. Downstream the cams there are warming washers installed; within the extraction section the screw shafts have a smaller diameter; within the homogenisation section the screw shafts diameters dramatically conically expand; within the delivery section the screw coils are thickened.EFFECT: allowing to expand the extruder technological capabilities.5 dwg

Description

The invention relates to equipment for the production of extruded products from meat and vegetable raw materials in the food-concentrate industry.

The closest in technical essence and the achieved effect is a twin screw extruder [US Pat. No. 2284914, IPC ⁷ B29C 47/40, A23P 1/12. Twin screw extruder / A.N. Ostrikov, A.S. Popov, I.Yu. Sokolov (RF). - No. 2005112086/12, Declaration 04/25/2005, Publ. 10/10/2006, B.I. No. 28], comprising a housing with screws with screw threads placed in it with the same pitch with the possibility of rotation in opposite directions. In the areas of loading, compression and dosing, the screw threads of the screws have opposite directions, and in the homogenization zone the screw threads of the screws have the same direction. In the crests of the cutting of one of the screws in the direction opposite to the direction of its screw cutting, grooves are made for the passage of the crests of the screw cutting of the other screw. In the homogenization zone there are sections of intensive shear and distribution of the product, and the section of intensive shear consists of successively repeating screw elements with screw thread and grooves, and the product distribution section has screw elements with screw thread and plasticizing cams, and in the metering zone it has a screw screw threaded element and cylindrical conical mandrel.

The twin-screw extruder contains a forming unit, which consists of an intermediate disk, matrix, channel former, filling filler. The filling machine consists of a hollow disk with a tube for supplying the filling and the forming tube, a fairing of the pre-matrix zone. The latter is a truncated cone with holes for supplying the melt of the product to the channel former.

A disadvantage of the known extruder design is the complexity of the additional input of thermolabile components into the melt and the implementation of their necessary physical and chemical transformations during extrusion cooking, as well as a narrow range of products.

An object of the invention is to expand the technological capabilities of the extruder for processing raw materials in order to expand the range of products and obtain more balanced food products by introducing meat components into their composition.

The task is achieved by the fact that in a twin-screw extruder, a new one is that each screw contains two compression zones, between which there is a decompression-extraction zone, the first compression zone includes three sections: loading, compression and dosing, the decompression-extraction zone consists of a decompression section and the extraction section, the second compression zone includes two sections: homogenization and injection, the decompression section of the decompression-extraction zone of each screw is six last of the cams installed independently, shifted relative to each other along the axis of rotation, so that the cams of the screws synchronously contact each other during their rotation, and in the extraction section the screw shaft is made of a smaller diameter, in the upper part of the extruder housing located after the decompression section of the decompression-extraction zone of the screws, a feeder with a vertical discharge screw is installed.

Figure 1 presents a front view of a twin-screw extruder, figure 2 is a three-dimensional image of the working chamber of a twin-screw extruder, figure 3 is a three-dimensional image of six sequentially installed and offset relative to each other along the axis of rotation of the cams in the decompression section of the decompression-extraction zone; figure 4 is a planar image of six cams on two shafts in the decompression section of the decompression-extraction zone; figure 5 - image of the screw with combined graphs of temperature and pressure along the length of the screw and indicating all sections of the three zones.

The twin-screw extruder (FIGS. 1 and 2) consists of a loading nozzle 1, a housing 3, two screws 2, a feeder 8 and a matrix 9. In the housing 3, channels 4 are made, into which cold or hot coolant is supplied through the nozzles 14 (depending on the required temperature condition). The screws 2 are driven into rotation by an electric motor 13 using chain sprockets 11, a chain 12 and a variator 10, which provides smooth adjustment of the rotational speed of the screws 2. Above the section of the casing 3 of the extruder located after the decompression section of the decompression-extraction zone, a feeder 8 with a vertical discharge screw is installed 7.

Each of the screws 2 consists of three zones (figure 5):

- the first compression zone, which includes three sections: loading, compression and dosing;

- decompression-extraction zone, which includes two sections: decompression and extraction;

- the second compression zone, which includes two sections: homogenization and injection.

At the loading site, the shaft and turns of the screws 2 have a constant diameter (Fig.2 and 5).

In the compression section, the diameter of the shafts of the screws 2 is conically expanded and the turns of the screws 2 are thickened to provide the necessary compaction and preliminary compression of the feedstock (FIGS. 2 and 5).

At the dosing section, the diameter of the shafts of the screws 2 also conically expands, but at a smaller angle (FIGS. 2 and 5), and the turns of the screws 2 are made with an even greater thickness. In this section, the raw material melts and it passes into a plastic state.

On the decompression section on the shaft of the screws 2 there are six sequentially mounted cams 5 offset from each other along the axis of rotation (FIGS. 3 and 4), so that the cams 5 of the screws 2 synchronously contact each other during their rotation. After the cams 5 on the screws 2, heating washers 6 are installed, which contribute to the additional heating of the homogeneous melt.

At the extraction section, the shafts of the screws 2 are made of a smaller diameter (Fig.2 and 5).

On the site of homogenization, the diameters of the shafts of the screws 2 sharply conically expand (figure 2 and 5). At this site, additional melting of the product with added meat additives takes place.

At the injection site, the turns of the screws 2 are thickened to force the melt through the holes of the matrix 9 (FIGS. 2 and 5).

The design of the screws 2 significantly affects the rational mode of operation of the extruder. The main problem is the possibility of the flow of the melt through the feeder 8 for supplying meat components. Therefore, when designing the screws 2, it was necessary to exclude the appearance of excess pressure in front of the feeder 8 for feeding the meat components. As a result, three-zone augers 2 were developed, each of which contains two compression zones, between which a decompression-extraction zone is located.

To ensure the input of meat components through the feeder 8, two conditions must be met. Firstly, it is required to provide atmospheric pressure in front of feeder 8. In addition, the product in this zone must be completely melted.

The requirement of atmospheric pressure is explained by the need to avoid leakage of the melt through the feeder 8 for the supply of meat components. The need to fulfill the second requirement is explained by the following reasons. If the product is not completely melted in the dosing section, then a reliable seal between the feeder and the loading section will not be ensured. The second reason requiring complete melting of the product is related to the diffusion coefficient, which is largely dependent on temperature. While the product temperature is below the melting point, the diffusion process proceeds at a low speed. Therefore, to increase the diffusion rate, the product must be in a molten state. In addition, turbulization processes more easily occur in the melt.

Pressure stabilization at atmospheric level can be ensured by the fact that the melt does not completely fill the decompression-extraction zone. If the channel is not completely filled, then the pressure does not increase. In order to achieve incomplete filling, the depth of the decompression-extraction zone is usually greater than the depth of the dosing section, and the transporting capacity of the homogenization section should be greater than the transporting capacity of the extraction zone [Rauwendaal K. Extrusion of polymers / Trans. from English Ed. AND I. Malkin - St. Petersburg: Profession, 2006. - 768 p.]. That is, it is necessary that the melt is removed from the decompression-extraction zone at a faster rate than it enters it. If the transporting ability of the homogenization section is insufficient, the melt will return to the extraction zone, which will lead to leaks through the feeder 8 for supplying meat components.

Twin screw extruder operates as follows.

The electric motor 13 is turned on, which, with the help of chain sprockets 11, a chain 12 and a variator 10, drives two screws 2 (1).

The initial product through the loading pipe 1 enters the loading zone of the screw channel of the screws 2 and is carried away by it due to the difference in the friction forces between the product and the walls of the housing 3 and the screw channel of the screws 2. Then, in the sealing section (Fig. 5), the raw materials are gradually compacted and the melt partially him.

At the same time, cold or hot heat carrier (depending on the required temperature regime) is supplied through the nozzles 14 to the channels 4 made in the housing 3.

At the dosing site, the product finally passes from the solid phase to the viscoplastic. Here, melting occurs as a result of the conversion of the mechanical energy of the extruder bodies to thermal energy due to internal friction in the product itself and additional heating of the housing 3 due to the supply of heat to the channels 4 by the hot heat carrier supplied through the nozzles 14. Under the influence of pressure and temperature, the proteins entering the composition of the product is subjected to denaturation, which is an intramolecular phenomenon characterized by a physical rearrangement of internal bonds.

Six rotating cams 5 (FIGS. 3 and 4), mounted and displaced relative to each other along the axis of rotation, on the one hand, provide a significant thermomechanical effect on the melt, and on the other hand, reduce the discharge pressure. The processed product is subjected to mechanical action of the rotating cams 5, as a result of which the formation of a "dead zone" is excluded. The stepped protrusions of the figured cams 5 synchronously contact with each other during their rotation, affect the microstructure of the melt. In this case, there is a violation of the ordering of the internal structure of the molecule, quantitatively determined by a change in the physicochemical properties of proteins (solubility, ability to hydrate, viscosity of solutions, resistance to enzymes, biological activity, etc. [Ostrikov, A.N. Extrusion in food technology [Text ] / A.N. Ostrikov, O.V. Abramov, A.S. Rudometkin. - S.-Pb .: GIORD, 2004. - 288 p.].

Then the melt passes through a narrow annular channel formed between the outer diameter of the heating washers 6 and the inner diameter of the housing 3, where it is subjected to intense mechanical stress, which also contributes to the additional heating of the homogeneous melt.

Then, the drive (in Fig. Not shown) of the vertical injection screw 7 located in the feeder 8 is turned on. And various heat-sensitive components (for example, dried meat) are introduced into the extraction zone into the obtained homogeneous melt.

After passing the injection section, the finished product is squeezed out through the holes located in the matrix 9. Moreover, it has a porous structure with the addition of various components.

Throughout the entire movement of the product, the temperature regime is regulated by means of heat carriers with a given temperature, supplied through pipes 14 to channels 4.

Thus, the use of the invention will allow:

- expand the technological capabilities of the extruder for the production of extruded products of various multicomponent composition;

- to provide the necessary depth of physico-chemical transformations of the components of the processed product by regulating the heat supply and mechanical stress of the installed cams 5 and heating washers 6.

Claims (1)

A twin-screw extruder for the production of meat and vegetable raw materials containing a loading nozzle, a housing, two augers with a drive and a die, characterized in that the housing has channels for supplying cold or hot heat carrier to them, and each of the augers has two compression zones, between which the decompression-extraction zone is located, while the first compression zone includes three sections: loading, compression and dosing, the decompression-extraction zone includes decompression and extraction sections, and In the housing section located after the decompression section, a feeder is installed for feeding meat components with a vertical injection screw, and the second compression zone includes two sections: homogenization and injection, while the shaft and the turns of the screws have a constant diameter in the loading section, and the shaft diameter in the compression section screws conically expands and the turns of the screws are thickened to provide the necessary compaction and pre-compression of the feedstock, in the metering section, the diameter of the shafts of the screws is also conically p expands, but at a smaller angle, and the turns of the screws are made with even greater thickness to ensure the melt of the raw material and its subsequent transition to a plastic state, in the decompression section on the shaft of the screws there are six sequentially mounted cams displaced relative to each other along the axis of rotation so that the cams synchronized contact with each other during rotation, and after the cams on the screws, heating washers are installed, which contribute to the additional heating of the homogeneous melt; ying smaller diameter portion on the screw shaft diameters homogenization sharply conically expanded for additional product melting amended meat additives, and the discharge portion are made thicker coils screw for forcing the obtained melt through die holes.

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