RU2495578C2 - Method and device for separation of frozen fish brick into carcasses without defrosting - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: invention relates to food industry. The method for separation of frozen fish bricks into carcasses without defrosting involves performance of wire explosions in proximity to the frozen fish brick being transported by the conveyor method. A hydraulic pressure occurs sufficient for destruction of ice bridges within the brick. Envisaged for the method implementation is a device containing a bath for water with a support mesh of the conveyor for bricks and supplying devices of exploding wire electrodes connected to a pulse HV generator. The negative electrode is represented by a metal tape rigidly fixed along the conveyor.

EFFECT: invention enables separation of frozen fish bricks into individual fish carcasses without defrosting.

2 cl, 1 tbl, 2 dwg

Description

The alleged invention relates to the food industry, and more specifically to technological processes, methods and devices using the physical effect of electro-hydraulic shock and can be used to separate the briquette of frozen fish into carcasses at sub-zero temperatures without thawing them. As you know, before selling the fish is partially thawed to destroy the frozen briquette [6, 7], and then placed in small bags by weight and re-frozen, which negatively affects the quality of the product.

Known, and already applied in technology, are methods of converting electro-hydraulic shock energy into mechanical energy [8], for example, for crushing and grinding materials, stamping metal and plastics, for cleaning castings, in agricultural machinery, etc. (from Prince Yutkina L. A. Electro-hydraulic effect and its application in industry, - L .: Mechanical engineering, 1986). The electro-hydraulic effect (EGE) uses the energy stored in a capacitor bank. As a result of electric discharge or burnout of the safety wire that occurs in a liquid medium, a channel is formed that represents a vapor-gas cavity, the expansion of which is accompanied by pressure waves and a high-speed flow, forming an electro-hydraulic shock that destroys the ice bridges in a frozen fish block. Installations of this type due to the significant energy accumulated in the batteries of pulse capacitors provide a pressure in the wave front of the order of 10 ² -10 ³ MPa, which exceeds the structural strength of the destructible ice.

The most important feature of the electropulse technology is the high selectivity of the destruction of brittle materials and the safety against the destruction of viscous materials (with the correct selection of the steepness of the pressure rise).

Electro-hydraulic installations based on the use of a pulsed spark discharge in a liquid have some characteristic features. This is instability and poor reproducibility of the process, low energy conversion efficiency (10-15%) and a significant effect on it of the liquid parameters, electrode sizes, their relative positions, etc., which leads to unproductive energy consumption stored in the storage tank to create conditions for occurrence of electrical breakdown of the working period.

The initiation of a discharge by an exploding conductor makes it possible to localize the breakdown point up to providing, in some cases, the specified geometry of the discharge channel, and to reduce the operating voltage by several times. In addition, it is known that the introduction of the elements of group I of the periodic table (for example, copper) into the discharge channel by means of an electric explosion of wires (EEC) helps to increase the effective adiabatic index γ _e , which determines the efficiency of the process of converting the energy stored in storage devices into expansion work channel [9].

The closest in technical essence and the achieved positive effect to the claimed is a device for defrosting fish briquettes by electro-hydraulic shock in a liquid [1], for which there is copyright certificate No. 1701235 of September 1, 1991. It represents a bath-gutter with water and a support grid, a series of point electrodes connected to a pulsed voltage source. When voltage is applied to the positive point electrode, a spark jumps between it and the mass electrode, which causes an electro-hydraulic effect in the liquid. Subsequently, thawing of individual carcasses of fish in water is intensified with the help of mechanical vibrators placed in a fluid stream with a temperature of + 15 ° С. The disadvantage of this device is the fast electroerosive wear of the electrodes, which changes the operating conditions and, to restore these properties, it is necessary to periodically replace them. In addition, processing is carried out in the entire liquid volume, which leads to increased power consumption. The disadvantage of the prototype method is the complexity of controllability by the magnitude of the spark, its frequency and power, the limitation of its scope only for defrosting fish (but not separation), since there was a sufficient amount of ice on the carcasses.

We proposed to use a method of converting the energy of electro-hydraulic shock into mechanical energy by blasting wires of controlled diameter in a liquid near a moving fish briquette. Moreover, due to the uneven structure of the wire, explosive heating and its melting are not uniform, and therefore the front of the propagating wave acquires a needle shape [4]. The development of the method consists in the fact that such a form of a shock wave crushes ice into fine crumbs more qualitatively and does not leave it on fish carcasses.

The aim of the proposed invention is the creation of conditions for the separation of a briquette of frozen fish into carcasses at sub-zero temperatures without thawing them and automatically coating them with water glaze before packaging. Similar devices for implementing the required method for the separation of frozen products were not found.

Thus, to achieve the goal in the proposed device, it is possible to use the technology of directed microexplosions from pulsating data and burnt wires. An electrohydraulic shock is produced directly at the design points under the fish briquette.

Due to the different strength characteristics of the muscle tissue of fish and ice, as well as the selective concentration of wave power on the surface of the fish, the block is divided into separate carcasses and crushed ice, without damaging the quality of the fish itself. This is one of the main advantages of this method of separation of frozen foods over others. It is known that with prolonged defrosting of fish in a liquid medium, some of the proteins and other substances are lost, its volume increases by 8-10% (a porous fiber structure of the muscles appears), as a result of which its quality is markedly reduced (table 1). Another advantage of using the proposed technology is the speed of achieving the desired result: all technological separation processes occur in less than a second. In addition, such a device allows you to use it to separate other food products, for example, frozen berries, vegetables, mushrooms, some block meat products, etc. To exclude the ingress of metal micro-suspensions, the wires can be structurally placed in an elastic tube, also filled with liquid, and their installation in the working position is automated. The experiments showed that if a copper wire with a diameter of 0.30 mm is used as a fusible element, then the energy dissipation during the destruction of one element is about 200 J. This amount of energy is released in thousandths of a second, so the power that turned into a shock wave is large enough for the possibility of destruction of fragile bodies (ice) and is easily adjustable.

The proposed experimental industrial device is depicted in the diagram (Fig. 1), which consists of a bath 1 with a mechanism for maintaining the water level from the water supply 2, a belt-mesh conveyor 3, feeding devices of working electrodes-wires 4, grounded electrodes-reflectors 6, a temperature regulator water discharge 7. For the formation of high-voltage direct current pulses of a given power and repetition rate and realization of an explosion of conductors in a liquid, an energy storage device based on KBG-50 capacitors is used. (Figure 2)

Technical characteristics of the installation:

- supply voltage, constant, U = 10000 V;

- the energy storage capacity C = 0.1 μF per 40,000 V;

- charging resistance R ₃ = 2 mOhm;

- air gap type K;

- supplied electrode N with a copper wire with a diameter of 0.3 mm;

- the number of discharges per second is 2-3 (adjustable depending on the strength of the fish block).

The device operates as follows (Figure 2):

Briquettes of fish are fed directly to conveyor 3. After that, through the openings of the mesh conveyor, the block is affected by an electro-hydraulic shock wave from the burnt conductor and after 2-3 strokes it divides the briquette into fish carcasses 5, which remain on the conveyor, and small-cracked ice floats and is discarded by the next wave to the edges of the bathtub, where it is utilized and partially melts due to the energy coming from the water supply to the bathtub. The proximity of the working body (electrodes, wires) and the processed object can significantly increase the efficiency of the device and eliminate the disadvantages of known devices.

High-voltage direct current is supplied from the rectifier through the charging resistance R to the capacitive energy storage device C, which is charged to a certain energy level. When charging is reached, all the accumulated energy through the ball gap K is supplied to the load - copper wire N. The process of discharge and thermal explosion of the wire in the liquid occurs. The experimental setup has a working bath made in the form of a metal box with a protective grid of 130 dm ³ in the center of which the feeding devices of working electrodes-wires are mounted in insulators. The negative electrode is a fixed metal strip along the conveyor, grounded to the conveyor body and the bathtub.

The product, placed in the working chamber, is thus subjected to dosed electro-hydraulic processing. Externally, the process is observed as a slight (2-3 cm) water swelling on the surface of the bath. The speed of movement of the shock front in water from an exploding wire can reach 4300 m / s (3, 4), but at a distance of 0.05-0.1 m it already drops to 260-300 m / s, and, given the significant mass of water, approaches the surface to zero. Therefore, to determine the optimal distance between the center of the explosion and the briquette moved on the mesh tape, calculation by a known method is required [4]. The separation process is performed when the briquettes move in water, i.e. conveyor method, and the fish can go directly to the packaging without additional freezing. A feature of the separation of frozen carcasses by this technology is the possibility of their subsequent orientation on the vibrating conveyor and packaging without actually thawing. Due to the negative temperature of the carcass, the fish is covered with icing. The quality of pre-sale processing of fish is obviously higher.

The technical effect in the proposed invention is achieved due to the fact that the use of exploding wires requires reducing the distance between the center of the explosion and the briquette that is moved on the mesh tape. The needle-shaped form of the shock wave that is characteristic of this method leads to the appearance of finely chipped ice and the absence of frozen pieces of ice on the carcasses of the fish, as well as to a reduction in energy consumption and an increase in the overhaul periods of this device. Thus, the impulsive supply of energy to the wire allows using a low-power energy source to isolate significant instantaneous power in the object. The frequency and strength of the strokes is synchronized with the speed of the fish blocks and the mass of briquettes.

The whole process of carcass separation is uniform and in speed exceeds all known methods (table).

Comparative characteristics of various defrosting methods Indicator Defrosting in the air Defrosting in the aquatic environment Steam-air mixture Microwave method Infrared method Using EHU with further defrosting in water (bubbling). Defrosting time of 1 block weighing 12 kg Up to 24 hours Up to 4 hours Until 10 o'clock 20-40 minutes Plus 1-2 hours Max. 8-9 hours 5-8 minutes Juice loss Up to 15% Up to 5% Up to 4% Up to 4% Up to 4% 0.5 ... 1.5% Uniformity t of the raw material at the exit on the surface much higher on the surface above on the surface above almost uniform surface overheating completely homogeneous Sanitary condition of raw materials Deteriorating: microflora development Deteriorating: microflora development Deteriorating: microflora development Stable Stable Improves: partial sterilization of raw materials The sanitary condition of the room Deteriorating significantly: strong odor Slightly worse: odor Slightly worse: odor Without changes Deteriorating significantly: strong odor Without changes Convenience of operation (the possibility of mechanization and automation) manual control manual control partial automation partial automation partial automation full automation possible Operating costs High Medium High Medium High Low Cost Low Average Average High High Average Average payback period There is no data Up to 12 months Up to 10 months There is no data Up to 12 months Up to 2-3 months

The proposed technical solution allows the transition to the continuous packaging of frozen fish without thawing or to filleting it after a few minutes of thawing as part of a continuous production line. As can be seen from the table, such an effect is not achievable using known methods.

The low cost and energy consumption of the installation and the existing methodology for industrial safety makes it affordable for small enterprises.

A feature of the method is the high efficiency of disinfecting water and fish from all types of microorganisms, including viruses and spores (reduction of living microorganisms by 10 ⁴ -10 ⁵ times) [7].

Thus, a method and apparatus for converting the energy of electro-hydraulic shock into the mechanical energy of separating an ice briquette into carcasses has been proposed, which has novelty and significant differences from the prototype, providing it with new useful properties (controllability of mechanical energy in frequency, speed, power and shape of shock waves, the possibility of using the method to provide better separation of the frozen fish block into carcasses).

Literature:

1. Antufiev V.T., Gromtsev S.A. Copyright certificate 1701235 of September 1, 1991. The method of defrosting fish briquettes and a device for its implementation.

2. Burtsev V.A., Kalinin N.V., Luchinsky A.V. Electrical explosion of conductors and its use in electrophysical installations. M .: Energoatomizdat. 1990.288 s.

3. Ivanenkov G.V., Pikuz S.A., Shelkovenko T.A. et al. Literature review on modeling the processes of electric explosion of thin metal wires. Part 2 Preprint 10.M .: LPI. 2004.30 s.

4. Tsarenko P.I., Rizun A.R., Zhirnov M.V. and others. Hydrodynamic and thermophysical characteristics of powerful underwater spark discharges. Kiev: Naukova Dumka, 1984.

5. GDR patent No. 44490 class. 53C of January 3, 1966. A device for melting (frozen products).

6. Stefanovsky V.M. Thawing fish. M .: Agropromizdat, 1987 .-- 190 p.

7. Yutkin L.A. Electro-hydraulic effect and its application in industry. L .: Mechanical engineering, 1986.- 250.

8. Semkin B.V., Usov A.F., Kurets V.M. Fundamentals of electropulse fracture of materials. - Apatity: KSC RAS, 1995, 276.

Claims (2)

1. A method for separating briquettes of frozen fish into carcasses without thawing by immersing them in water and applying electro-hydraulic shocks from high-voltage electric discharges with the formation of hydraulic pressures around the discharge zone sufficient to destroy ice bridges, characterized in that the method of converting electro-hydraulic impact energy into mechanical energy by exploding wires in water near a conveyed briquette of fish. 2. A device for separating briquettes of frozen fish into carcasses without thawing, containing a water bath with a support grid of the conveyor for briquettes and electrodes connected to a high-voltage pulse generator, characterized in that it is equipped with feeding devices for exploding wire electrodes and as a negative electrode - a metal tape fixed along the conveyor, while the frequency and strength of the explosions of the wire electrodes are synchronized with the mass and speed of movement of the fish briquettes.

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