RU2660260C1 - Electrohydroimpulsive method for destruction of concrete products using pinch effect - Google Patents

Abstract

FIELD: recycling and disposal of waste.

SUBSTANCE: invention relates to methods of processing of end-of-life or defective reinforced concrete products. Destructible product is immersed in water and subjected to a high-voltage electric discharge between the electrodes. Initially, the mobile working electrode is located on the opposite side from the connection of the second pole of the high voltage generator to the reinforcing cage. In the course of destruction, the first working / positive electrode approaches the second / negative electrode connected to the armature, this causes a pinch effect in the reinforcing elements, which accelerates the process of peeling the reinforcement from the concrete.

EFFECT: simplification and acceleration of the process of preparation of concrete products for destruction is provided.

1 cl, 1 dwg

Description

The invention relates to methods for processing old or defective reinforced concrete products (hereinafter - reinforced concrete) - crushing and separation of reinforcement from concrete. The method is intended for the destruction of products containing internal reinforcing conductive elements.

Known methods of mechanical crushing of concrete products, which consist in the fact that they are subjected to mechanical compression or impact before the concrete is separated from the reinforcement (B.V. Gusev, V.A. Zagursky. Recycling of concrete. - M .: Stroyizdat, 1988). The disadvantage of these methods is the high cost, mechanical complexity and high massiveness of the mechanical equipment used for their implementation. So, the SMZH-541 unit with a capacity of 15 t / h for concrete waste has a mass of 150 tons. There can be many such plants, and substandard plants that are substandard or old concrete products have to be transported from afar. Transport costs in this case are many times higher than the possible benefits of disposal. Methods using jaw mechanical crushers require preliminary grinding of the waste to a size corresponding to the size of the crusher inlet, which makes production more expensive. In addition, crushers are very dusty, clogged with reinforcement, the working surfaces of crushing parts wear out quickly. All known mechanical methods crush the reinforcement, turning it into scrap metal. Metallurgical plants accept reinforced scrap only in a compact form, and therefore plants with mechanical crushing must be supplemented with a press for reinforcement. The acceptance price of such scrap is several times lower than the price of business fittings.

There is a known method of destroying old precast concrete elements, which consists in the fact that deaf holes are drilled in a destructible object filled with water or another liquid, two working electrodes are introduced into each hole in turn, which are usually connected by wire, the hole in the hole is tightly closed, and once to the electrodes a relatively low impulse is applied — up to 10 kV — of voltage with an energy of 50 ... 100 kJ (L. A. Yutkin. Electro-hydraulic effect and its application in industry. L.: “Mechanical Engineering”, 1986, p. 161). The high pressure that develops in a hole during a wire explosion destroys the product. After each pulse, if destruction has not occurred, the electrodes are removed from the hole to re-install the wire.

The disadvantages of the method are the high cost of equipment for its implementation (the price of only a capacitor bank of 50 ... 100 kJ is 0.7 ... 1.5 million rubles), low productivity, the need for drilling holes, complicated by the fact that the drill often gets into the valve, and also the fact that when it is used, the product, although it is destroyed, does not occur in a few parts (low brisance), and the concrete does not completely separate from the reinforcement. If electrodes are introduced into the structural cavities of the product, for example, into the internal channels of reinforced concrete pillars or hollow overlapping panels, then destruction does not occur at all, since the method is effective only at a very small distance from the electrodes to the walls of the cavity, the blind bottom of the cavity and a tightly closed hole through which Electrodes are introduced into the cavity. The structural cavities of reinforced concrete products are usually open at both ends, the edges of the cavity are often broken off and the tight clogging of cavities, which are few in many products, is practically impossible with a reasonable expenditure of time and effort.

A method for crushing reinforced concrete scrap based on the use of the electro-hydraulic effect is known, in which reinforced concrete waste is pre-cut into pieces of reinforced concrete and placed in a crushing chamber filled with water with a bottom in the form of a movable grate and exposed to a shock wave generated by a powerful electric discharge between the end immersed in water vertically mounted stationary working electrode and a grating connected to the poles of the high-voltage pulse generator (in sometimes referred to in the literature as a pulse current generator). Discharge pulses, following with a certain frequency, gradually destroy concrete and release the reinforcement (Pat. RF No. 2152826, class. V02C 19/18, 11/30/98). The method requires large labor costs for the preliminary cutting of waste into small pieces. When crushed by this method, reinforcing bars are not damaged, but since they are repeatedly cut during the preparation of waste for crushing, the possibilities for their reuse are very small.

The known method of crushing reinforced concrete products based on the use of the electro-hydraulic effect is free from this drawback, in which they are immersed in a water-filled crushing chamber with a grating bottom and subjected to electric discharge between a stationary working electrode mounted vertically and a loading grate, and stones are added to the reinforced concrete waste in an amount of 0.2 to 5 volumes of waste (US Pat. RF No. 2193449, class B02C 19/18, 03.03.01). However, the productivity of this method is low, and energy consumption is great. The shock wave acts outside the product, causing compressive stresses in them, to which concrete is very resistant. Destruction occurs slowly and with high energy consumption. In addition, its implementation requires additional costs for stone delivery.

Closest to the proposed technical essence is the installation for the destruction of old or defective concrete products, containing a crushing chamber filled with water with a flat bottom, on which a grating is installed, a set of working electrodes mounted in a row vertically across the entire width of the crushing chamber with the possibility of moving in a direction parallel to the plane in which the destructible product lies motionless, that is, the surface of the water in the crushing chamber, and the high-voltage pulse generator connected by one pole to the armature with the skeleton of the destructible product, and with the other with working electrodes electrically connected together. A high-voltage breakdown between the ends of the electrodes and the reinforcement through the thickness of concrete destroys it, separating it from the reinforcement (L.A. Gelfond, N.T. Zinoviev, V.D. Kazantsev et al. Electropulse installation ESU-2T / 11 for destruction of substandard reinforced concrete. - " Electronic processing of materials ", 1990, No. 6, p. 74-75). The disadvantage of the installation is that it is operable only at very high - about 300-400 kV - voltages, which extremely complicates and increases the cost of the installation, its operation, requires a large area to accommodate high-voltage equipment. The parallel connection of all electrodes does not provide uniform release of the reinforcing cage from concrete, since breakdown develops more often from some electrodes, and less often from some electrodes. For complete cleaning, it is necessary to increase the processing time, which reduces productivity and increases energy consumption. This method requires the destruction of an excessively high (over 10 kJ) discharge energy, in which the service life of the electrode before repair does not exceed 1000 ... 1500 pulses. The indicated source does not show the installed power of the power source of the high-voltage pulse generator, but the photo of the generator shows a TBTM 1600/35 rectifier-rectifier with a rated power of 210 kW. The connection and maintenance of this expensive rectifier transformer is possible far from everywhere. Weak rural networks are simply not able to provide the required capacity. This increases the transportation costs for the concentration of reinforced concrete products in such unique installations.

Especially ineffective are known methods using electric discharge when destroying reinforced concrete pillars. Currently, in all countries, due to the expansion of the scope of cable power supply, many millions of reinforced concrete pillars are being released. The round cross-sectional shape of such pillars ensures their very high resistance to shock. Because of this, the fracture productivity is so low that these known methods are not applicable for economic reasons.

The technical objectives of this proposal is to simplify and accelerate the process of preparing reinforced concrete products for destruction, increase the productivity of the method, reduce its energy consumption, ensure complete separation of concrete from reinforcement, simplify and reduce the cost of equipment that performs destruction.

These technical problems are solved by the fact that changes are made to the known method of destruction of reinforced concrete products, namely, that the product to be destroyed is immersed in water and subjected to an electric discharge between the working electrode and the reinforcing cage, while initially the electrodes are removed as far as possible from each other to enhance the pinch effect in fittings. In the process of destruction of the product, the working electrode is moved.

In the proposed device for electro-hydraulic destruction of reinforced concrete products using a pinch effect containing a working electrode connected to a high-voltage pole of a pulse generator, the second, grounded terminal of which is electrically connected to the product armature, the above-mentioned disadvantages are eliminated by the fact that the pinch effect accelerates the process of separation of reinforcing bars elements from the concrete base.

Due to the immersion of the product in water and the pinch effect, the process of preparing the product for destruction is accelerated due to the intensification of the crushing process. Even a small layer of water, due to its inertia and almost complete incompressibility, performs well the function of damping a shock wave generated by an electric discharge in water, and the pinch effect ensures quick and effective detachment of reinforcing elements from the concrete base.

The destruction is carried out by many pulses of relatively small (2 ... 5 kJ) energy, which reduces the mass and cost of the capacitor bank used in all electric-discharge methods as an energy storage device.

Thanks to the translational movement of the working electrode, a gradual complete separation of the reinforcement from concrete is ensured during the destruction of extended products.

The essence of the proposal is illustrated in figure 1, which shows a diagram of a device implementing the proposed method in accordance with the independent claim.

The description below applies to both the proposed method and the device for its implementation.

The reinforced concrete product 3 to be destroyed, having reinforcing conductive elements, for example, a reinforced concrete pillar or floor slab, is immersed on cables or chains in a crushing chamber filled with water and laid on lodgements 4. The positive working electrode 2 is made in the form of a metal rod surrounded by insulation. Its end is placed on one side of the product 3 and connected to the positive high-voltage pole of the generator of high-voltage pulses 1. The second, negative, pole of the generator 6 is grounded. At the place farthest from the positive electrode, concrete is removed until the rods of the reinforcing cage (reinforcement) are exposed 5. The negative output of the generator 6 is connected to the reinforcing cage 5.

When high voltage pulses are applied to the working electrode 2 from the generator 1, between its end immersed in water and the reinforcing cage 5 of the product 3, a spark discharge occurs that generates a shock wave that destroys the concrete of the product 3. At the same time, passing through the conductive elements of the armature, the current causes in the conductive elements pinch effect, accelerating the process of peeling reinforcement from concrete. Concrete is not an obstacle to the passage of the spark and the development of the discharge, provided that the voltage of the generator 1 is sufficiently large. For reinforced concrete poles and floor panels, a voltage of about 50 kV is sufficient. At a discharge pulse repetition rate of 2 Hz and an average power of a high-voltage pulse generator from 2 to 8 kW.

The destruction rate is about 5 cubic meters per hour at the indicated generator power and depends on the brand of concrete and the condition of the product.

Concrete fragments separated from the reinforcing cage fall into the sorting and filtration system, where the fragments are sorted by fraction size and washed.

As the reinforcing frame 5 is freed from concrete, the working electrode 2 is advanced along the product 3. After the reinforcing frame 5 is completely released, the freed frame is lifted from the water on the cables.

An installation implementing the proposed method can be placed on a mobile platform based on a truck.

The installation is combined with the equipment necessary for the separation of reinforced concrete products into fragments of the required size for loading into the crushing chamber.

This avoids the cost of transportation and preparation of products and process products directly at storage sites.

The proposed method has a performance sufficient for most cases. The power consumption is so small that the power supply of the installation is quite possible even from weak rural electricity networks and autonomous generators.

Claims (1)

A method for destroying reinforced concrete products using the pinch effect, which consists in immersing the product to be destroyed in water and exposing it to a high voltage electric discharge between the electrodes, characterized in that the movable working electrode is initially located on the opposite side from the connection of the second pole of the high voltage generator to the reinforcing frame, and in the course of destruction, the first working / positive electrode is brought closer to the second / negative connected to the armature, this causes a pinch-effect EKT in reinforcing elements, accelerating the process of peeling off the concrete reinforcement.

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