RU2277473C1 - Method of recycling worn tires to broken rubber crumbs - Google Patents

Abstract

FIELD: regeneration of plastics.

SUBSTANCE: method of recycling worn tires to broken rubber crumbs is based upon feeding pieces of worn tires to hammer crusher provided with feed speed controller, processing of pieces in hammer crusher for destroy of rubber-cord system along borders of rubber and textile and metal cord to components, removal of separated textile cord out of hammer crusher by air, removal of mixture of rubber crumbs from cuts of metal cord and control of power supplied to drive of hammer crusher. Temperature of mixture of broken rubber crumbs containing cut of metal cord is measured. When temperature of mixture achieves 120°C, the mixture is cooled down. For the purpose water is applied to area of working area of hammer crusher. Discharge of water provides dew point of air at output of hammer crusher to be higher than temperature of wall of sucking-out air duct. When temperature of mixture achieves 100°C, the supply of water is stopped. According to the method, the other version is provided. According to the version, supply of pieces of worn tires is reduced depending on level of power of hammer crusher.

EFFECT: higher intensity of crushing of worn tires; elimination of condensate formation onto walls of equipment; elimination of corrosion.

Description

The invention relates to techniques for the regeneration of plastics and can be used in the processing of worn tires into crushed rubber crumb.

A known method of processing worn tires into crushed rubber crumb, comprising feeding pieces of worn tires to a rotary-knife crusher, grinding them in a rotary-knife crusher, the design of which simultaneously provides for grinding material “pulling” of textile and metal cord and supplying a mixture of crushed rubber crumb with scraps of textile and metal cord to separators, where crushed rubber crumb is separated. Pieces of worn tires go to the rotary knife crusher from the hopper-homogenizer, in which they can be stored up to several days before that (see the patent of the Russian Federation No. 2194616, B 29 V 17/00 // B 29 K 21:00, 12/20/2002 ) The use of a rotary knife crusher provides the disclosure of up to 70% of textile and metal cord, as a result of which the increased content of textile and especially metal cord remains in crushed rubber crumb, which significantly impairs the quality of crushed rubber crumb. The fractional yield of crushed rubber crumb is completely determined by the design features of the rotary knife crusher and cannot be changed without changing its rolls, which limits the ability to control the fractional output of crushed rubber crumb directly during the process.

The closest to both variants of the claimed invention, in terms of essential features, is a method of processing worn tires into crushed rubber crumb, comprising feeding pieces of worn tires into a hammer crusher with a feed rate control, processing them in a hammer crusher with destruction of the rubber cord system along the borders of rubber and textile and metal cords for the components, removing the separated textile cord from the hammer mill with air, withdrawing the mixture of crushed rubber crumb with scraps of metal thallic cord to the separator, separation of crushed rubber crumb from the scraps of metal cord and control of the power supplied to the electric drive of the hammer crusher (see patent of the Russian Federation No. 2140357, 29 29 17/00, 17/02, 02 02 13/04, 27.10 .1999). Using a hammer crusher allows you to change the fractional composition of crushed rubber crumbs directly during the process by changing the feed rate of pieces of worn tires and power supplied to the hammer crusher. With the right choice of operating mode, the use of a hammer crusher allows intensive grinding of pieces of worn tires in the mode of brittle destruction of rubber, which makes it possible to almost completely separate textile and rubber cords from the rubber itself, which significantly improves the quality of crushed rubber crumb.

With intensive grinding of pieces of worn tires in the mode of brittle destruction of rubber, the consumed power substantially depends on the strength characteristics of the crushed pieces of tire. Depending on the design of the tire, the conditions of its operation and the duration of operation, the strength characteristics of the worn tire vary so widely that to average the technological properties of individual portions of pieces of worn tires fed to the hammer mill, it is necessary to organize special sections with control of the physicomechanical characteristics of all incoming tires, or reduce the productivity of the hammer crusher to prevent overheating, and possibly ignition of crushed rubber crumb and cutting textile cord during the fragmentation.

The problem to which the claimed invention is directed, is to create a method for processing used tires into crushed rubber crumb, providing intensive grinding of pieces of used tires regardless of the physico-mechanical, including strength, characteristics of the processed used tires by controlling the crushing process and eliminating technological overheating mass in a hammer mill. Another objective of the invention is to provide a method for processing worn tires into crushed rubber crumb, the use of which will not lead to the formation of condensate on the walls of technological equipment and thereby exclude accelerated wear of equipment due to corrosion. An additional object of the invention is to provide a method for processing worn tires into crushed rubber crumb, providing optimal conditions for processing tires (mode of brittle destruction of rubber).

The stated technical problems are solved by the fact that in the method of processing worn tires into crushed rubber crumb, which includes feeding pieces of worn tires into a hammer mill with control of the feed rate, processing them in a hammer mill with the destruction of the rubber cord system along the boundaries of rubber and textile and metal cord into components, removal of the separated textile cord from the hammer mill with air, withdrawal of a mixture of crushed rubber crumbs with scraps of metal cord to a separator, separation of crushed rubber new crumbs from scraps of metal cord and control the power supplied to the drive of the hammer crusher, according to the invention, measure the temperature of the mixture of crushed rubber crumbs with scraps of metal cord, at a temperature of this mixture above 120 ° C it is cooled, for which water is fed into the working area of the hammer crusher , and when the specified mixture is cooled to a temperature below 100 ° C, the water supply is stopped.

In this case, the flow rate of air that removes the textile cord is measured, the absolute humidity at the outlet of the hammer mill is calculated at a dew point equal to the temperature of the wall of the suction duct, and the maximum amount of water carried away by the air and the water are supplied at a rate that ensures the outlet dew point from a hammer mill above the temperature of the wall of the suction duct.

In addition, simultaneously with the supply of water, the supply of pieces of worn tires to the hammer mill is reduced.

In this case, water consumption is reduced in proportion to the change in the feed rate of pieces of worn tires.

According to the second embodiment, the technical tasks are solved by the fact that in the method of processing used tires into crushed rubber crumb, which includes feeding pieces of used tires into a hammer mill with a feed rate control, processing them in a hammer mill with the destruction of the rubber cord system along the borders of rubber and textile and metal cords for components, removal of separated textile cord from a hammer mill with air, withdrawal of a mixture of crushed rubber crumb with scraps of metal cord on arator, separating crushed rubber crumbs from scraps of metal cord and controlling the power supplied to the drive of the hammer mill according to the invention, when the power consumed by the drive of the hammer mill is increased to a level of 1.15-1.2 from the nominal, water is supplied to the working area of the hammer mill, simultaneously with the water supply, reduce the supply of pieces of worn tires to the hammer mill, reducing its power consumption, while reducing the power consumption to nominal, reduce the amount of water supplied by 1.5-2 times, and p and 0.75-0.9 achieving power consumption of the nominal flow of water is stopped and transferred to the hammer mill at a nominal operating mode.

In this case, the flow rate of air that removes the textile cord is measured, the absolute humidity at the outlet of the hammer mill is calculated at a dew point equal to the temperature of the wall of the suction duct, and the maximum amount of water carried away by the air and the water are supplied at a rate that ensures the outlet dew point from a hammer mill above the temperature of the wall of the suction duct.

The basis of the invention is the control of the external characteristics of the technological process of grinding pieces of worn tires in brittle fracture mode during the operation of the hammer crusher in a steady (nominal) mode, the change of which will primarily reflect the change in the physical and mechanical properties of the pieces of worn tires received for processing and the output of which for critical parameters may lead to disruption of the process.

In the first embodiment, the temperature of the mixture of crushed rubber crumb with scraps of metal cord, which reflects the specific energy costs for crushing pieces of worn tires, is used as such a characteristic. An increase in the specific energy consumption leads to an increase in the temperature of this mixture and when the temperature of the mixture reaches 120 ° C to prevent a critical situation, for example, the possibility of smoldering heat sources, water is fed into the working area and the mixture of crushed rubber crumb with scraps of metal cord temperature is cooled below 100 ° C, excluding this possibility, after which the water supply is stopped.

Coordination of the water flow rate with the air flow rate, which removes scraps of textile cord, protects the inner walls of the technological equipment from accelerated corrosion, since even with maximum water supply the air temperature will be higher than the dew point of the wall of the suction duct.

Reducing the supply of pieces of worn tires in a hammer mill simultaneously with the supply of water accelerates the exit from a critical situation.

Reducing the water flow in proportion to the change in the feed rate of pieces of worn tires ensures that the air temperature in the suction duct remains above the dew point.

In the second embodiment of the invention, the power consumed by the hammer mill drive is used as such a characteristic, an increase in which when stationary supplying pieces of worn tires means an increase in the specific energy consumption for crushing them, and an increase in the power consumed by the drive to a level of 1.15-1.2 of the nominal value that the specific energy costs are approaching a critical level and it is necessary to reduce the heating of the mixture of crushed rubber crumb with scraps of metal cord, which is achieved by supplying water to the working area of the hammer mill and simultaneously with the water supply reduce the supply of pieces of worn tires to the hammer mill, reducing power consumption (approximately proportional to the feed rate of pieces of worn tires). The water supply is coordinated with the level of power consumption, in particular, when the power consumption is reduced to the nominal value, the amount of water consumed is reduced by 1.5-2 times so as not to cause overcooling of the working area of the hammer mill. Reducing power consumption to a level of 0.75-0.9 from the nominal value means getting out of a critical situation and the water supply is stopped, and the hammer mill is transferred to the nominal operating mode.

As in the first version, matching the water flow rate with the air flow rate, which removes textile cord trim, protects the inner walls of the process equipment from accelerated corrosion, since even with maximum water supply the air temperature will be above the dew point of the wall of the suction duct.

The application of the claimed method provides intensive processing of worn tires into crushed rubber crumb with a size of 10-20 mm in the optimal mode of destruction of the rubber cord system along the boundaries of the components and along the rubber for both textile and metal cord, due to the stable operation of the hammer crusher in brittle mode destruction of rubber with a duration of mechanical impact on rubber not exceeding its relaxation time, regardless of the physicomechanical characteristics of a particular batch of worn tires, which makes it possible to reduce the cost of their processing.

Figure 1 and 2 shows a General scheme of lines for processing worn tires into crushed rubber crumb, implementing two versions of the proposed method.

The line for recycling used tires to produce crushed rubber at the outlet contains a storage bin 1 of pieces of used tires connected by a batch conveyor 2 with a hammer mill 3, in which the pieces of the tire are crushed to separate metal and textile cords from the rubber and crush the rubber component of the tire into separate pieces with a size of not more than 20 mm. An inlet duct 4 is connected to the hammer mill. The hammer mill has two exits. A textile selection system is connected to the first exit, including a suction duct 5, a cyclone 6, a textile waste bin 7, a device 8 for measuring air flow, and a suction fan 9. A conveyor 10 is connected to the second outlet, to which the crushed rubber mixture flows from scraps of metal cord. The conveyor 10 is equipped with a magnetic separator 11 and a magnetic drum 12. At the outlet of the conveyor, a cooling heat exchanger 13 and a crushed rubber storage hopper 14 are installed. To the magnetic separator 11 is connected to the storage hopper 15 scraps of metal cord. The batch conveyor 2 is equipped with an adjustable drive 16. The hammer mill 3 is equipped with an adjustable drive 17 and nozzle 18 for supplying water to the working area of the hammer mill.

Depending on the technological scheme being implemented, the line is equipped with additional equipment.

To implement the first variant of the method for processing used tires into crushed rubber crumb, the hammer mill is equipped with a sensor 19 for measuring the temperature of the mixture of crushed rubber and metal cord scraps and a control unit 20, to which a device 8 for measuring air flow is connected, an adjustable drive 16 for a batch conveyor, an adjustable drive 17 hammer crusher, nozzle 18 and sensor 19.

To implement the second variant of the method of processing used tires into crushed rubber crumb, the hammer mill is equipped with a control unit 21, to which a device 8 for measuring air flow, an adjustable drive 16 of a portion conveyor, an adjustable drive 17 of the hammer mill and nozzle 18 are connected.

Disposal of worn tires is as follows.

Tires are crushed to pieces of rubber, the dimensions of which do not exceed 30 × 50 mm. Pieces of rubber are fed into the storage hopper 1 and from there, using a batch conveyor 2, they enter the hammer mill 3, in which the pieces of the tire are crushed into individual fragments of 10 × 20 mm in size with the destruction of the rubber cord system along the boundaries of rubber and textile and metal cord into components. At the same time, the metal and textile cords are separated from the rubber. By means of a fan 9, the hammer mill 3 is blown with air. Air draws off the exfoliated textile cord and transports it through the duct 5 to cyclone 6, where the textile cord is separated from the air and collected in the storage hopper 7. The mixture of crushed rubber and metal cord scraps is passed through a magnetic separator 11, where the metal cord scraps are separated from the crushed rubber and transferred to the storage hopper 15. The crushed rubber, cleaned from scraps of metal cord, is cooled in the heat exchanger 13 and transferred to the storage hopper 14. The crushed rubber can be ready for duktom, but can also be used for subsequent processing. The fractional composition of crushed rubber is determined by the operating mode of the hammer mill and can be adjusted by changing the power and speed of the drive 17.

Intensive crushing of tire pieces in a hammer mill occurs with the release of heat and is accompanied by heating of a mixture of rubber crumb and scraps of metal cord located in the working area. The heat dissipation rate is determined by the specific power consumption for crushing pieces of rubber tires, depending on the particular batch of worn tires. In the nominal operating mode, the temperature of the mixture of rubber crumb and scraps of metal cord is in the range of 100-110 ° C. With an increase in the batch of worn-out tires with increased bond strength of rubber with cord, the specific power consumption for crushing pieces of rubber tire increases, which leads to an increase in the power consumed by the drive 17 and the temperature of the mixture of crumb rubber and metal cord scraps.

Depending on the version of the implemented method of processing used tires into crushed rubber crumb, one of the external control characteristics is used to control the progress of the technological process: either the temperature of the mixture of crushed rubber crumb and scraps of metal cord, or the power consumed by the drive 17 of the hammer crusher. The measured control characteristic is compared in the control unit 20 or 21 with the limit characteristics embedded in the unit and when the control characteristic exceeds the set limits, the control unit 20 or 21 gives a signal to supply water to the working area of the hammer mill and transfers the line to a new nominal operating mode.

When operating the line in accordance with the first variant of the method, the temperature of the mixture of crushed rubber crumb with scraps of metal cord is measured. When the temperature of the mixture exceeds 120 ° C, water is fed into the working area of the hammer mill until the temperature of the mixture of crushed rubber crumbs with scraps of metal cord drops to 100 ° C or lower, after which the water supply is stopped. The maximum water flow rate is determined from the condition of the absence of condensate (dew loss) on the wall of the suction pipe, which is the coldest part of the line. To bring the line to the nominal operating mode, simultaneously with the supply of water, the supply of pieces of worn tires to the hammer mill is reduced. Moreover, the water flow rate is also reduced in proportion to the change in the feed rate of pieces of worn tires. When the temperature of the mixture of crumb rubber and scraps of metal cord is lower than 100 ° C, the water supply is stopped, as the temperature decrease confirms the line is entering a new nominal operating mode.

When operating the line in accordance with the second variant of the method, the power consumed by the electric drive of the hammer mill is measured. An increase in the specific power consumption for crushing pieces of rubber at a steady feed rate into a hammer mill leads to an increase in power consumption.

When the power consumed by the electric drive of the hammer crusher is 1.15-1.2 times higher than the nominal value, which means an increase in the specific energy consumption for crushing pieces of worn tires and, accordingly, an increase in the temperature of the mixture of crushed rubber crumb and metal cord scraps, water is fed into the working area of the hammer crusher. Simultaneously with the water supply, the supply of pieces of worn tires to the hammer mill is reduced, which leads to a decrease in power consumption. When reducing the power consumption to nominal, the amount of water supplied is reduced by 1.5-2 times, and when reducing the power consumption to 0.75-0.9 from the nominal, the water supply is stopped. The maximum water flow rate is determined from the condition of the absence of condensate (dew loss) on the wall of the suction pipe, which is the coldest part of the line.

Examples of specific implementation of the method.

Example 1. A line that implements the first version of the proposed method.

The line with a hammer crusher with a capacity of 800 kg / h in nominal mode has a mixture temperature of crushed rubber crumb with scraps of metal cord, varying in the range of 95-110 ° C. When crushing a new batch of worn tires, the temperature of the mixture began to rise and exceeded 120 ° C (maximum temperature was 125 ° C). The hammer mill was blown with air at a rate of 6,000 cubic meters per hour with an absolute humidity of 8.7 g / cubic meters. The temperature of the duct wall is 20 ° C. To reduce the temperature, water began to be supplied to the working area at a rate of 0.367 kg / min. The absolute humidity at the outlet was 12.4 g / m3. The dew point for a given absolute humidity is 14 ° C, which eliminates the condensation of water vapor on the pipe wall. At the same time as the water supply, the productivity of the hammer mill was reduced to 720 kg / h. Water consumption was reduced to 0.33 kg / min. After lowering the temperature of the mixture of crushed rubber crumb with scraps of metal cord to 98 ° C, the water supply was stopped and the hammer crusher continued to operate with a capacity of 720 kg / h. In the new nominal mode, the temperature of the mixture of crushed rubber crumb with scraps of metal cord was kept in the range of 105-110 ° C.

Example 2. A line that implements the second version of the proposed method.

Line with a hammer mill with a capacity of 800 kg / h. In the nominal mode, the power consumed by the electric drive of the hammer crusher was 110 kW and ranged from 100-120 kW. (Control measurements showed that the temperature of the mixture of crushed rubber crumb with scraps of metal cord varied within 105-112 ° C). The hammer mill was blown with air at a rate of 6,000 cubic meters per hour with an absolute humidity of 8.7 g / cubic meters. The duct wall temperature is 22 ° C. When crushing a new batch of worn tires, the power consumed by the electric hammer mill increased to 130 kW. To reduce the temperature, water was started at a flow rate of 0.4 kg / min. The absolute humidity at the outlet was 14 g / m3. The dew point for a given absolute humidity is 17 ° C, which eliminates the condensation of water vapor on the wall of the pipeline. Simultaneously with the water supply, the productivity of the hammer mill was smoothly reduced to 680 kg / h. With a decrease in power consumed by the electric drive of the hammer crusher to 110 kW, the water consumption was reduced to 0.26 kg / min. The reduced productivity of the hammer mill led to a reduction in power consumption of up to 100 kW. The water supply was stopped, and the hammer mill was transferred to a new nominal operating mode with a capacity of 720 kg / h at a power consumed by the electric drive of the hammer mill, 105 kW.

The proposed method of processing used tires into crushed rubber crumb can be used on any installations with hammer crushers. If the installation has a detailed measurement and control scheme for the technological process, including temperature measurement in the working area of the hammer mill, it is advisable to implement the first version of the proposed method, since it allows the crushing process to be carried out in the optimal mode. In plants with a simplified control scheme, it is advisable to implement the second version of the proposed method, while the rated capacity of the fan can be used as the measured characteristic of air flow. As a drive in a hammer mill can be used not only an electric drive, as shown in the examples of specific performance, but any other drive, for example, an internal combustion engine of any type.

Claims (6)

1. A method of processing worn tires into crushed rubber crumb, comprising feeding pieces of worn tires into a hammer mill with a feed rate control, processing them in a hammer mill with the destruction of the rubber cord system along the boundaries of rubber and textile and metal cord into components, removing the separated textile cord from the hammer crushers with air, withdrawing a mixture of crushed rubber crumbs with scraps of metal cord to a separator, separating crushed rubber crumbs from scraps of metal cord and controlling the power supplied to the drive of the hammer mill, characterized in that the temperature of the mixture of crushed rubber crumb with scraps of metal cord is measured, at a temperature of the mixture above 120 ° C, it is cooled, for which water is supplied to the working area of the hammer mill with a flow rate ensuring the dew point air at the outlet of the hammer mill above the temperature of the wall of the suction duct, and when this mixture is cooled to a temperature below 100 ° C, the water supply is stopped. 2. The method according to claim 1, characterized in that when water is supplied to the working area of the hammer mill, the air flow rate is removed, removing scraps of textile cord, the absolute air humidity at the outlet of the hammer mill is calculated at a dew point equal to the temperature of the wall of the suction duct, and the maximum amount of water carried away by air. 3. The method according to any one of claims 1 and 2, characterized in that, simultaneously with the supply of water, reduce the supply of pieces of worn tires in a hammer mill. 4. The method according to claim 3, characterized in that the flow rate is reduced in proportion to the change in the feed rate of pieces of worn tires. 5. A method of processing worn tires into crushed rubber crumb, including feeding pieces of worn tires into a hammer mill with control of feed rate, processing them in a hammer mill with destruction of the rubber cord system along the boundaries of rubber and textile and metal cord into components, removing separated textile cord from the hammer crushers with air, withdrawing a mixture of crushed rubber crumbs with scraps of metal cord to a separator, separating crushed rubber crumbs from scraps of metal cord and controlling the power supplied to the drive of the hammer mill, characterized in that when the power consumed by the drive of the hammer mill is increased to a level of 1.15-1.2 from the nominal, water is supplied to the working zone of the hammer mill with a flow rate providing the dew point of air at the outlet of the hammer mill crushers above the temperature of the wall of the suction duct, at the same time as the water supply, reduce the supply of pieces of worn tires to the hammer mill, reducing its power consumption, while reducing the power consumption to par They increase the amount of water supplied by 1.5-2 times, and when the power consumption reaches 0.75-0.9 of the nominal, the water supply is stopped and the hammer mill is switched to the nominal operating mode. 6. The method according to claim 5, characterized in that when water is supplied to the working area of the hammer mill, the air flow is measured, removing the scraps of textile cord, the absolute humidity at the outlet of the hammer mill is calculated at a dew point equal to the temperature of the wall of the suction duct, and the maximum amount of water carried away by air.

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