RU2273513C2 - Device for electro-osmosis dehydration of materials - Google Patents

Abstract

FIELD: electro-osmosis dehydration of moist dispersed materials; dehydration of materials at high content of water, mainly finely ground bone tissue.

SUBSTANCE: proposed device has housing which performs function of anode, transporting mechanism which performs function of cathode and vacuum chamber. Housing is made in form of tube with perforated tube located inside it. Transporting mechanism is made in form of screw feeder located in perforated tube and supported by electric insulating insert; sliding cathode current collector is mounted on its tail-piece.

EFFECT: increased productivity; reduced power requirements; ease in use.

3 dwg

Description

The invention relates to electroosmotic dehydration of wet dispersed materials and can be used for dehydration of materials with a high water content, mainly for finely ground bone tissue.

A known apparatus for electroosmotic dewatering of materials, including a housing with drained side surface and bottom, which are the cathode and anode, made in the form of rods mounted on the lid of the apparatus. Between the anode and cathode are placed plates of a porous material having a relative dielectric constant higher than that of the particles of the solid phase of the dehydrated material (1).

However, this apparatus is ineffective in dehydration of polydisperse materials, for example, crushed bone tissue, since it is of periodic action and has a large specific energy consumption.

A device for cleaning suspensions is known. It consists of electrodes made in the form of mesh tapes passed between tightly adjacent to each other rotating drums with an elastic surface. The mesh tape is made of alternating conductive and dielectric sections with a cell ratio of the dielectric and conductive sections equal to 1: 2 (2).

The disadvantages of the device include its low efficiency in the dehydration of polydisperse materials. In addition, there is a rapid wear of the mesh tape due to frictional forces between homogeneous materials, the layer between which is an abrasive material, for example, dispersed bone tissue.

A device for electroosmotic dewatering of suspensions is known, comprising a housing between two vertical walls of which a filter cloth and an anode are placed, attached along the perimeter with elastic material to a wall made with a hole for current supply, and the opposite wall is perforated and is a cathode. The device is equipped with a vacuum chamber located on the cathode side and a device for regulating the interelectrode distance (3).

The closest analogue to the proposed one is a device containing a housing, which is an anode, a transporting mechanism, which is a cathode and placed inside the housing, and a vacuum chamber (4).

These devices are not suitable for dehydration of materials in a continuous mode, which reduces productivity, increases specific energy consumption and complicates the mechanization of the process. The dehydrated material is not in the same conditions in volume. The use of vacuum increases the requirements for structural strength and reliability of seals, and the design of devices with large flat surfaces does not allow for high performance. In addition, the operation of the devices requires the need for auxiliary operations, including periodic loading of raw materials and unloading of dehydrated material, the mechanization of which requires an appropriate number of electric drives.

The objective of the invention is to increase productivity, reduce specific energy consumption for obtaining dehydrated material and simplify the maintenance of the device.

The problem is solved in that in a device for electroosmotic dewatering of materials, including a housing that is an anode, a transport mechanism that is a cathode and placed inside the housing, and a vacuum chamber, according to the invention, the housing is made in the form of a pipe with a perforated tube coaxially located inside, the transport mechanism made in the form of a screw placed in a perforated pipe resting on an insulating insert, and a cathode sliding current collector is installed on its shank uk.

The use of vacuum increases the requirements for structural strength and reliability of seals, and the design of the device having large flat surfaces does not allow for high performance. The use of flat surfaces leads to their deformation, since the resulting force of atmospheric pressure can reach 10 t / m ² , which necessitates the use of stiffeners.

The length of the pipe and the speed of rotation of the screw and the fill factor of the screw provide the corresponding duration of the material in the dehydration zone and the productivity of the process. When moving the material along the perforated pipe with the help of a screw ensure thorough mixing of the dehydrated material, which intensifies the process and reduces unproductive energy consumption compared with drying in a stationary layer in the prototype.

In the laboratory of the department "Technological equipment and industry processes" MGUPB made an experimental sample of the proposed device, which has a diameter of 45 mm perforated tube body, auger diameter 40 mm, auger length 700 mm, the volume of the loading hopper 20 liters. The vacuum inside the pipe was maintained at 0.6 * 10 ⁵ Pa. During the experiment, a suspension of cryo-crushed compact bone tissue of cattle was dehydrated. The initial moisture content of the bone tissue is 60%, the particle size of the cryo-crushed bone tissue is less than 100 microns. Dehydration mode: dry product productivity 30 kg / h, voltage between electrodes 50V.

Dehydration indicators: humidity of the finished product 7% -8%, specific energy consumption for electric osmosis 14 kW / h / t, vacuum 6 kW / h / t, press screw 7 kW / h / t. Bacterial contamination and fat content within the industry standard.

The experimental sample was also tested on other suspensions, including on compact bone tissue of pigs. In total, more than 100 experiments were conducted. Tests showed ease of maintenance and high reliability of the device: the product did not stick to the electrodes, the holes of the perforated pipe were not blocked, uniform humidity was achieved throughout the entire volume of the finished product, all technological operations of the electroosmotic dehydration process were mechanized and carried out continuously.

Figure 1 shows a device for electroosmotic dewatering of materials; figure 2 presents a section aa of the connection of the intermediate support and the screw through the insulating insert; figure 3 presents the cathode sliding current collector.

The device consists of a housing 1 in the form of a pipe, a perforated pipe 2, located coaxially to the housing 1, a loading hopper 3 and an unloading pipe 4. The housing 1 is equipped with a pipe 5 for evacuation and removal of water. The pipe 5 is connected to a vacuum system (not shown). A screw 6 is mounted inside the housing; an electrically insulating sliding bearing 10 and a cathode sliding current collector 8 are installed on its shank 7, consisting of a support 9, contact electrodes 11 and 12, a spring 13, a current collector case 14, a high-voltage electric wire 15 with a hermetic cover 16.

The housing 1 is mounted on an intermediate support 17, inside which there is a spline connection of the shaft 18 of the intermediate support and the end of the screw shaft 6 through an electrically insulating insert 19 (Fig. 2). The shaft 18 of the intermediate support 17 is connected via a coupling 20 to the gear motor 21.

The gear motor 21, the intermediate support 17 and the housing are mounted on a common frame 22.

The device operates as follows. An aqueous solution of the dispersed material is loaded into the hopper 3. The gear motor 21 is turned on and the torque is transmitted to the shaft 18 of the intermediate support 17 and the screw 6 through the insulating insert 19 using the coupling 20 and the electric current is supplied for electroosmosis by connecting the grounded housing 1 to the anode, and the shaft of the screw 6 using the current collector 7 to the cathode. The screw 6, rotating, moves the dehydrated material along the perforated pipe from the outlet of the hopper 3 to the discharge pipe 4. In the process of moving the material is dehydrated under the action of three forces: gravitational, fractional pressure due to the vacuum created in the pipe and electroosmotic forces. In addition, when electric current is passed, heat is released in the material, which helps to weaken the bond of moisture with the material and, as a result, intensifies the dehydration process. Vacuum in the pipe of the housing 1 is provided by turning on a vacuum pump (not shown) connected to the pipe 5.

The dehydrated material is discharged through a pipe 4, which can be used as a pin for extruding the product into an elastic shell and subsequent hermetic packaging, for example, using a clipper (not shown).

Thus, the proposed device in comparison with the prototype has a greater efficiency of dehydration and lower specific energy consumption. In addition, mechanization is simplified, since a number of auxiliary operations are excluded and the process is carried out in a continuous mode.

Information sources

1. USSR author's certificate No. 982711, MKI B 01 D 13/02 11, A 01 C 3/00.

2. USSR author's certificate No. 869105, MKI B 01 D 35/06.

3. USSR author's certificate No. 1064971, MKI B 01 D 13/02.

4. SU 175484 A1, cl. B 01 D 61/56, 10/09/1965, p.2 (prototype).

Claims (1)

A device for electroosmotic dehydration of materials, including a housing that is an anode, a transport mechanism that is a cathode and placed inside the housing, and a vacuum chamber, characterized in that the housing is made in the form of a pipe with a perforated pipe coaxially located inside, the transport mechanism is made in the form of a screw placed in a perforated pipe resting on an insulating insert, and a cathode sliding current collector is installed on its shank.

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