RU2793646C1 - Complex for washing and drying of polystyrene waste - Google Patents

Abstract

FIELD: polystyrene waste washing and drying.

SUBSTANCE: invention relates to a complex for washing and drying expanded polystyrene waste. The effect is achieved by a complex for washing and drying expanded polystyrene waste, which consists of a bale breaker, a belt conveyor, a washing screen, a sorting belt conveyor, a shredder with a magnetic trap, a belt conveyor, a washing unit, a squeezing unit, a roller machine, a belt conveyor, connected in series into a single line. , drying machine, storage silo.

EFFECT: obtaining washed, selected from foreign impurities and dried to a residual moisture content of not more than 10% expanded polystyrene, suitable for further processing.

1 cl, 1 dwg, 2 tbl, 2 ex

Description

The invention relates to a complex line for washing and drying of expanded polystyrene waste for their further processing into a secondary polystyrene granule. The secondary granule can be used for the production of various products and, in particular, insulation based on extruded polystyrene foam.

The problem of processing waste polymers in general, and expanded polystyrene in particular, has become more relevant in recent years due to an increase in their production and consumption and, accordingly, an increase in the environmental burden.

The specificity and complexity of processing polystyrene waste is that:

1. This type of waste has a large volume with a small weight, has a very low specific gravity.

2. Styrofoam waste is very heavily contaminated with food waste and foreign materials.

3. Expanded polystyrene has an increased moisture absorption, which greatly complicates and makes it impossible to further process it without prior drying. Drying expanded polystyrene is a rather complicated process, unlike drying non-porous materials, due to the presence of a large number of capillaries and, accordingly, a large amount of moisture absorbed by this material.

The prior art method for cleaning contaminated polymers, patent RU 2673886, publ. 03.12.2018 Bull. No. 34. The invention relates to a method for purifying recycled polymers after domestic use or after industrial use. This method is based on the dissolution of polymers at high temperature and excess pressure with further extraction of the dissolved polymers. The disadvantage of this method is the technical and technological complexity of the process, the dissolution of contaminants with their entry into the extractable polymer, additional environmental and fire hazards due to the use of volatile solvents at elevated temperatures and pressures.

Known washing equipment for crushed waste polymer materials, patent RU 2323823, publ. 05/10/2008 Bull. No. 13. The invention relates to washing equipment mainly of film materials. The disadvantage is the insufficient efficiency of washing contaminated waste, especially polystyrene foam. This invention does not solve a complex of issues related to the processing of polymer waste: there is no separation of foreign inclusions, there is no effective drying of the washed material.

Known line for washing crushed waste polymers, patent RU 2227093 C1, publ. 20.04.2004 Bull. No. 11. The invention relates to the field of waste processing of polymeric materials, in particular to equipment for washing waste (film, bags, disposable tableware, etc.) in crushed form. The disadvantages of this line: it does not provide high-quality washing of waste and separation of impurities of polymeric materials, it is intended mainly for film materials, and does not solve a complex of issues related to the processing of polymeric waste.

Known line for processing waste polymer materials, patent SU 1109313 A1 The invention relates to the processing of polymeric materials and can be used in the chemical industry, processing used polymer films, bags, bags. The disadvantage of this line is that it is intended for the processing of film materials, not intended for the processing of foamed materials.

The objective of the proposed technical solution is to develop a complex for crushing, removing foreign objects, washing and drying polystyrene waste with a capacity of 300 kg per hour. This problem is solved due to the design features of the units of the complex and the technical possibility of a wide change in technological parameters for effective process control.

The complex for washing and drying expanded polystyrene waste consists of a bale breaker, a belt conveyor, a washing screen, a sorting belt conveyor, a shredder with a magnetic trap, a belt conveyor, a washing unit, a wringer unit, a roller machine, a belt conveyor, a drying machine, a silo, connected in series into a single line. drive, while the bale breaker consists of a body, a horizontally placed feed conveyor and a portal with agitators, each of which contains two vertically located oppositely rotating axes with levers perpendicular to the axis of rotation, the bale breaker is configured to change the speed of material supply to the agitators , the belt conveyor for feeding raw materials to the washing screen is made with the possibility of adjusting its speed according to the degree of load, the washing screen is a cylinder rotating in a closed housing with technological holes made on the surface in the form of segments, which are half a circle with a diameter of 50 mm, and on the inside the cylinder is equipped with blades, a horizontal auger is located under the screen cylinder, picking up the inclusions that have fallen into the screen holes and moving them to the diagonal unloading auger outside the device, the shredder consists of a magnetic trap, a rotor with knives with a sizing grid and a receiving hopper at the outlet, while the magnetic trap is located in the upper part of the shredder and is made in the form of a conveyor with a magnet, the rotor knives grind the material to a size passing through the cells of the sizing grid, a closed-cycle washing unit with a water tank and a water circulation system consists of a loading window, a housing, a perforated glass, at the bottom of which there are two impellers placed one above the other, a remote pipe with an auger, a tank for dirty water, while the washing unit is designed to be used in the hot water washing mode and the cold water washing mode, the wringing unit is a friction wringing device with a fine floating fraction selection tank , the main working element of which is a centrifugal blower, consisting of an electric motor with an impeller installed on its shaft, enclosed in a perforated drum; a sleeve made in the form of a chute with holes, and blocks of adjustable thermal fans, the storage silo is a vertical container with a loading opening in its upper part and a conical bottom with an unloading opening with a slide gate in the lower part.

The technical result is to obtain at the output of the complex washed, selected from impurities, and dried to a residual moisture content of not more than 10% expanded polystyrene, suitable for further processing.

The essence of the claimed invention is illustrated by graphic material. In FIG. 1 shows a general view of the complex.

The complex for washing and drying expanded polystyrene waste consists of a bale breaker 1, a belt conveyor 2, a washing screen 3, a sorting belt conveyor 4, a shredder with a magnetic trap 5, a belt conveyor 6, a washing unit 7, a wringer unit 8, a roller machine, connected in series into a single line. 9, belt conveyor 10, dryer 11 and silo 12.

Bale breaker 1 is a device that breaks bales and provides a uniform supply of material to the line. The bale breaker consists of a body, a conveyor placed horizontally in it and a portal with agitators. On the bale to be torn, the binding material is cut, and the bale is placed on the conveyor, on which the bale moves towards the portal with agitators. Passing through the portal, the bale falls between the "claws" of the agitators, which tear it apart. The agitator consists of two vertically located axes with "claws", while the axes rotate in opposite directions. "Claws" are levers perpendicular to the axis of rotation. Axes with levers provide tearing of a pile of Styrofoam waste and moving the disintegrated parts of Styrofoam further onto the line. This device (bale breaker) provides for the possibility of changing the speed of material supply to the “claws” of the agitator. The change in the speed of material supply to the "claws" of the agitator occurs due to the delay timer for turning on the drive of the material supply conveyor. By increasing the pause in the operation of the conveyor drive, the amount of material entering the "claws" is reduced. The change in the rotation speed of the "claws" of the bale breaker is also due to the turn-on delay timers of the corresponding drive. Thus, the duration of the pause in the operation of the drives allows you to change the amount of material entering the line, adjusting the productivity of the entire line depending on the quality of the incoming material and the quality of the material at the exit from the complex.

The disintegrated material then enters the belt conveyor 2 to feed the feedstock to the washing screen. This conveyor 2 has the additional ability to adjust its speed up to a stop to regulate the degree of loading of the screen in the event of large pieces of incoming material.

Washing screen 3 is used to wash off surface contaminants (primarily abrasive) from the surface of unground waste (such as PET containers, small household containers, etc.), as well as to remove solid inclusions from the material (such as metal, stones and etc.). Screen 3 is a cylinder of large diameter (~1000 mm), 2000 mm long, rotating in a closed housing. The entire wall of the cylinder is equipped with a large number of technological holes made in the form of identical segments, which are half a circle with a diameter of 50 mm. This allows elongated foreign objects (eg nails, pieces of wire, wood chips, etc.) to fall into the holes, and relatively large pieces of polystyrene foam, having a rounded shape, are washed off and pass further along the screen. On the inside, the cylinder is equipped with blades. During operation, recyclable plastic waste is fed into it through the loading device. They enter the rotating cylinder and move towards the unloading area. In the process of advancing, water is supplied to the material from above, which leads to preliminary washing of the material. Foreign inclusions present on the surface of plastic waste fall into the technological holes in the cylinder body, are picked up by a horizontal auger and moved by it to a diagonal unloading auger located under the screen cylinder, which unloads the inclusions outside the device.

For better pre-cleaning of the material in the screen, it is possible to add a detergent and disinfectant - sodium hypochlorite - to the water. The concentration of sodium hypochlorite in the wash water should be no more than 0.1% to prevent corrosion of metal parts of the equipment.

Belt conveyor 4 is designed for manual sorting, which removes all non-polystyrene waste fractions.

The shredder with a magnetic trap 5 is designed for crushing various solid thin-walled waste. The shredder consists of a magnetic catcher, a rotor with knives with a sizing grid and a receiving hopper at the outlet. The incoming raw material passes through a magnetic trap, which removes metal objects that were not selected manually. The magnetic catcher is located in the upper part of the shredder and is made in the form of a conveyor with a magnet. Metal objects are magnetized to the conveyor belt, taken to the side and scraped off into the receiving container using a scraper. Further, the whole mixture is crushed into the desired fraction with the help of knives mounted on the rotors. The material to be ground is in the grinding chamber until its size is small enough (no more than 40 mm) for it to pass through the cells of the sizing grid. After reaching the appropriate size, the crushed material enters the receiving hopper under the sizing grid and then with the help of a belt conveyor 6 into the washing unit 7.

The washing unit 7 is made in a closed cycle with a water tank and a water circulation system. This washer is used for high-efficiency washing of various Styrofoam wastes in continuous mode. The optimal size of the crushed particles of the washed material is in the range of 10…40 mm.

The washing unit consists of a loading window, a housing, a perforated glass, at the bottom of which two impellers located one above the other, a remote pipe with an auger, and a tank for dirty water are installed.

The first impeller, rotating, creates a directed turbulent flow of a suspension of the washed material in water, feeds this flow through a remote pipe to the auger for unloading from the sink. Dirt and fine sand pass through the mesh cup due to centrifugal force and then fall into the wash water settling tank. The second (lower) impeller additionally removes heavy impurities that have settled during the washing process into the wash water settling tank. Thus, a sufficient washing of foamed polystyrene waste from contamination is achieved in a continuous mode with a capacity of 300 kg per hour.

The principle of operation of the washing unit: through the conveyor, the raw material enters the loading window, from the latter into the glass, at the bottom of which the impeller, rotating at high speed, creates pressure. Under pressure, the washed mixture enters the pipe, which returns the suspension of particles with water to the glass. Clean material is taken by the auger, dirty water is discharged through the pipe into the tank. In the tank, the water settles and is pumped back into the glass. The circulation of water is constant. Ultimately, pure raw materials enter the next stage of its processing, and the water remains in the unit. Dirty water is drained into a separate container, settled, and the sedimented dirt is disposed of.

Depending on the degree and nature of contamination, the washing unit can be used in the following modes:

- Hot water wash. This mode can be used both with and without detergents. This mode is used when washing heavily contaminated materials, which are ineffective in washing with cold water. Such contaminants include oil products, animal fats, etc.

- Washing mode with cold water. This mode can be used both with and without detergents. The main task solved when washing in the washing mode with cold water is the task of washing easily washed and / or water-soluble contaminants, such as sand, dust, some adhesive compositions and other similar contaminants.

Next, the raw material enters the squeezing unit 8. The squeezing unit is a frictional squeezing device with a small floating fraction selection tank. The main working element of the unit is a centrifugal supercharger. Structurally, a centrifugal supercharger consists of an electric motor with an impeller mounted on its shaft, which is enclosed in a perforated drum. During the operation of the squeezing unit, the impeller rotating at high speed creates a zone of discharged pressure at the inlet to the perforated drum and draws the processed material into the perforated drum. In the process of moving the material along the drum, it is affected by a significant friction force that occurs between the impeller blades and the inner surface of the drum, which simultaneously removes contaminants from the material and the water that wets them, which in turn leads to cleaning and drying of the washed material. After entering the last centrifugal blower of the unit, the washed material is ejected by the impeller of the centrifugal blower outside, for mechanical extraction.

Next, the raw material enters the roller machine 9 (mechanical extraction), including a cyclone, a conveyor belt with two rotating rolls. The roller machine is designed to remove moisture absorbed by the material by squeezing it out. By means of pneumatic supply from friction pressing, the raw material enters the cyclone, where excess pressure is extinguished. The material then enters the conveyor belt and is squeezed out, passing between two rotating shafts. The roller machine is equipped with a feeder and an unloader.

Further, the pressed and clean raw material rises along the 10 belt conveyor and enters the 11 dryer. The 11 dryer is used to remove residual moisture from the processed material. The main working elements of the dryer are a mesh separation unit and blocks of adjustable thermal fans. The mesh separator consists of a screw enclosed in a perforated sleeve. The perforated sleeve is made in the form of a trough with holes, covering the lower half of the auger, providing a diffuse air flow to the drying zone for uniform contact of the heated air with the material being dried. During operation, the auger, rotating, pushes the material through the perforated sleeve. Blocks of thermal fans are forced into the cavity with a sleeve hot air with a temperature of up to 60 ° C. Thus, the material is dried. Also, the design of the sleeve allows the label (paper and shrink) to be separated during the drying process due to a constant and strong air flow, which takes it through the discharge channel to the collection tanks (if equipped with a label separator). The material is pushed through the sleeve by means of an auger and discharged from the dryer.

The design of the dryer, the ability to control air flows, provides non-rectilinear movement of the material through the dryer, its presence in the "fluidized bed". This ensures that the material is in the dryer in the mode of its continuous operation for at least 4 minutes, which is necessary to obtain the required residual moisture content of the material after leaving the dryer. The residence time of the material can be adjusted by changing the rotation of the dryer screw to select the optimal effective mode for drying the material. After the dryer, the material, by means of pneumatic feed, enters the storage silo 12 and further, if necessary, into the compactor.

The storage silo 12 is a vertical container with a loading opening in its upper part and a conical bottom and an unloading opening with a gate valve in the lower part.

The compactor consists of a high pressure auger. It creates a more convenient form of material for its further transportation if necessary. The washed and dried material can be further processed on site without the use of a compactor.

Below are the results of the tests of the claimed complex.

Example #1. The operation of the washing complex at maximum productivity in the case of a relatively small contamination of the feedstock with wastes of other polymers.

Table No. 1 presents data on the loaded and received materials. The processing time was 12 minutes, the productivity of the feedstock was 370 kg/h, the productivity of the finished product was 240 kg/h.

Example #2. The operation of the washing complex at a reduced capacity in the case of an increase in the proportion of wastes of other polymers in the feedstock.

Table No. 2 presents data on the loaded and received materials. The processing time was 15 minutes, the productivity of the feedstock was 288 kg/h, the productivity of the finished product was 180 kg/h

The advantage of the proposed complex is that it allows you to process expanded polystyrene waste in a continuous mode with a capacity of 300 kg per hour, regardless of the density of the incoming material, its geometric dimensions, degree of contamination, quantity and quality of foreign inclusions.

As a result of the operation of the complex for washing and drying expanded polystyrene waste, a clean, washed, and dry (no more than 10% residual moisture) raw material is obtained, applicable for further processing. If it is necessary to transport the obtained raw materials, its preliminary compaction is possible.

Claims (1)

A complex for washing and drying expanded polystyrene waste, consisting of material crushing devices connected in series into a single line, raw material supply devices, washing and drying devices, characterized in that it contains devices in the following sequence: a bale breaker, a belt conveyor, a washing screen, a sorting belt conveyor, a shredder with a magnetic trap, a belt conveyor, a washing unit, a wringer unit, a roller machine, a belt conveyor, a dryer, a storage silo, while the bale breaker consists of a body, a horizontally placed feed conveyor and a portal with agitators, each of which contains two vertically located oppositely rotating axes with levers perpendicular to the axis of rotation, the bale breaker is configured to change the speed of material supply to the agitators, the belt conveyor for supplying raw materials to the washing screen is configured to adjust its speed according to the degree of loading, the washing screen is a rotating in a closed case, a cylinder with technological holes made on the surface in the form of segments representing a half circle with a diameter of 50 mm, and on the inside the cylinder is equipped with blades, under the screen cylinder there is a horizontal auger that picks up the inclusions that have fallen into the holes of the screen and moves them to the diagonal unloading auger outside device, the shredder consists of a magnetic trap, a rotor with knives with a sizing grid and a receiving hopper at the outlet, while the magnetic trap is located in the upper part of the shredder and is made in the form of a conveyor with a magnet, the rotor knives grind the material to sizes passing through the cells of the sizing grid, a closed-cycle washing unit with a water tank and a water circulation system consists of a loading window, a housing, a perforated cup, on the bottom of which there are two impellers placed one above the other, a remote pipe with a screw, a tank for dirty water, while the washing unit is made with the possibility of using in hot water washing mode and cold water washing mode, the wringing unit is a friction wringing device with a fine floating fraction selection tank, the main working element of which is a centrifugal blower, consisting of an electric motor with an impeller mounted on its shaft, enclosed in a perforated drum, a roller machine includes a cyclone and a conveyor belt with two rotating rolls, the dryer includes a mesh separation unit, consisting of an auger enclosed in a perforated sleeve made in the form of a chute with holes, and blocks of adjustable thermal fans, a storage silo is a vertical container with a loading hole in its upper parts and a conical bottom with a discharge opening with a slide gate at the bottom.

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