SU914909A1 - Dryer for loose and lumped mateials - Google Patents

Description

The invention relates to a drying ’technique, namely to installations for carrying out the processes of drying loose and komkuyuschih materials in the chemical, pharmaceutical and pharmaceutical, food and other industries.

Known dryers for bulk and lumping materials containing a stationary drum, inside of which is a hollow shaft with scraper elements [1].

The disadvantages of these dryers are relatively small heat transfer surface, sticking of the material on the shaft and scraper elements, uneven filling of the material along the length of the drum.

Also known apparatus for heating and drying fine materials containing a heated drum, placed on its axis auger, made in the form of a flexible shaft with a loop-like elastic fixed on it2

scrapers and devices for loading and unloading material [2].

The disadvantages of this device are the relatively small surface of the heat supply (heating wall of the drum), ^{5 the} uniformity of filling with the drum material and sticking of the material on the shaft.

The closest to the proposed invention is a dryer for syruping and lumping materials, containing a heated cylinder with loading and unloading devices and a flexible auger with variable pitch in the form of a hollow heating coil, provided at the periphery with a SZD scraper drying does not provide

_m sufficient heat supply to the material being dried.

The purpose of the invention is the intensification of heat and mass transfer in the implementation of the periodic drying process.

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The goal is achieved by placing a cylindrical shell in the cylinder inside the heating coil, which is provided on the inner side with spiral fins having a direction 5 opposite to the direction of the screw turns, with cavities inside the shell and between it and the cylinder connected to the ends of the cylinder.

Installation on the auger of a cylinder with spiral fins, having a direction opposite to the direction of the turns of the flexible auger, will allow continuous orderly circulation of material in the dryer, isolating material flows transported in opposite directions from each other, i.e. eliminate cross-mixing, as well as increase the level of material in the dryer, which leads to the intensification of drying and allows you to increase productivity. The implementation of a flexible auger in the form of a heating coil creates improved conditions for the flow of material around it.

FIG. 1 shows a schematic representation of a dryer for bulk and lumpy materials, a general view; in fig. 2 • section A-A in FIG. one; in fig. 3 is a graph comparing drying curves without a cylindrical shell and with it.

The dryer has a stationary cylinder 1 with a jacket, a flexible auger in the form of a heating coil 2 with scrapers 3> a shaft 4 with a cylindrical shell 5 fixed on it, having a spiral fin 6, a loading 7 and a discharging 8 device. The fins 6 has a direction opposite to the direction of the auger turns. The cavities inside the shell 5 and between it and cylinder 1 are communicated at the loading and unloading ends of the cylinder. ₀

The dryer works as follows.

Through the loading device 7, in the heated cylinder 1, 'inside of which the heating coil 2 with scrapers 3 and the shell 5 with fins 6 on the inner surface rotate on the shaft 4, wet bulk material is loaded. Upon contact of the wet material with the inner surface of the cylinder 1, the heating coil 2 and the scrapers 3, heat is supplied ^{to the} material and it is dried to the specified humidity during transportation.

When transporting material to a snake Evik 2 in the space between the heating surface of cylinder 1 and the outer surface of the shell 5, the material flows around the coil 2 because of its small amount and "thorough mixing within the cells formed by the turns of the coil 2 and the surfaces of the cylinder 1 and the shell '5 10 receives a strictly defined amount of heat and at the outlet of the hollow cylinder 5 has a constant moisture content for the whole batch. Accumulating in the discharge end of cylinder 1, the material 15 is picked up by the end coils of the fins 6 and loading Both gulls 5 are drawn inwards. With constant rotation, both gulls 5 material, being poured, is transported by fin 6 to the opposite side to the charging end of cylinder 1.

By the time the material is unloaded from the shell 5 of the dried material, the raw material loaded into cylinder 1 with the initial moisture is transported by the coil 2. The portion of material unloaded from both gulls 5 is picked up by the coil 2 and transported again in the direction of the discharge end of cylinder 1. And so it repeats until until the material is dried to the desired humidity. After this, the valve of the unloading device 8 opens and the material is discharged by means of the coil 2. When material sticks to the inner wall of cylinder 1 and shell 5, scrapers 3 cut it, and when material sticks to scrapers 3, with the next turn of the coil 2 they are wedged into the material according to the plow principle and, due to friction, stuck to scrapers 3 material is cut off. As a result, an insignificant ^<5 distinct vibration of the coil 2, which occurs when the material is cut by scrapers 3, adheres to the inner surface of cylinder 1 and shell 5, coil 2 and scrapers 3, is additionally ⁵⁰ self-cleaning. An experimental test on a laboratory installation made of stainless steel X1810T with an internal cylinder diameter of 220 mm, a length of 350 mm, and a diameter of ³³ rum of a coil tube of 10 mm and an external diameter of 175 mm of the shell was performed under the following initial conditions:

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Drying material HED-anhydride

Heat carrier temperature 85 ° С

Residual pressure 4.9 kPa

Speed

shaft 0.1 rev / s.

The results of an experimental comparison of a dryer without a shell with a reversible rotation of the coil and with a shell are shown in FIG. 3, where the kinetic curve B corresponds to a cylinder without a shell, and curve B to a cylinder with a shell.

As can be seen from the graph of humidity I) (%} material from time V (min) under the same experimental conditions, the kinetic curve C is located under curve B, the angle of inclination of curve B in the first drying period, which characterizes the drying rate, is greater than the angle of inclination of the curve B, as a result, it takes less time to reach a given final moisture content on curve C than on curve B. This is partly due to the fact that during reverse rotation of the coil, the material is constantly pressed to the ends of the cylinder and does not participate in the drying process.

In this case, the possibility was established of carrying out a periodic drying process in the proposed dryer; the possibility of increasing the drying rate, i.e. intensification of the drying process; the possibility of obtaining a uniform moisture content and material structure; possibility of self-cleaning of heat transfer surfaces; the absence of overdried material due to the intensive mixing of the material in the moving cells and the possibility of increasing the fill level of the dryer.

Thus, the use of the proposed dryer allows to intensify the drying process; raise the level of filling with the material of the dryer and increase its productivity; increase the heating surface of the dryer; get a product homogeneous in structure and at a given final humidity; protect the material from drying out; better manage the process and expand the range of thermolabile materials being processed.

Claims (1)

Claim Dryer for bulk and lumping materials, containing a heated cylinder with loading and unloading devices and a flexible auger placed inside the cylinder in the form of a hollow heating coil, equipped with scrapers along the periphery, because with the first goal of intensification of heat and mass transfer during the periodic drying process , in the cylinder inside the heating coil there is a cylindrical shell, provided on the inner side with spiral finning, having a direction opposite to the direction of the screw turns, n The cavities inside the shell and between it and the cylinder are communicated along the ends of the cylinder.