NO142958B - PROCEDURE AND DEVICE FOR MANUFACTURING FIBER MATTS OF GLASS THERMOPLASTIC MATERIAL - Google Patents

Abstract

Method and device for manufacturing fiber mats from thermoplastic material such as glass.

Description

Procedure for thawing frozen fish or other frozen foodstuffs, as well as container for use when carrying out the procedure.

The present invention relates to defrosting

of frozen fish or other frozen foodstuffs (hereinafter the designation

fish is used as also including others

foodstuffs) and concerns more specifically

the problem of thawing on land of fish

which is frozen on board trawlers in the sea.

However, the invention is not limited

for this application.

With herring, which is a fatty 'fish, it has

usable results have been obtained in a relatively simple way by dielectric heating, but with cod, which contains

very little fat, it is found difficult to

achieve satisfactory results on this

manner. In particular, errors occur in the form of

local overheating, especially in thinner

portions of the fish near the edges of the blocks.

According to the present invention is lowered

the block of frozen fish or other foodstuffs into water, at least to the level of the upper surface of the block,

while the block is exposed to an electric field

with radio frequency. The inventors have found that by keeping the block of frozen fish submerged in this way is reduced

substantially the danger of local overheating of the fish even in the event that the block contains white fish frozen in

whole 'state.

The blocks to be thawed are brought along

a speed such as can be of one

order of magnitude of from 5-7.6 cm per minute.

(2-3" per minute) between the electrode plates

for a radio frequency field generator. So that

the blocks must be kept submerged in water

while under the impact

of the electric field, each block must be placed in a waterproof container, e.g. of wood or plastic, as the excess space is filled with water which can conveniently be at room temperature when filling.

From the beginning, the blocks must be prevented 1 from floating up, e.g. in that they are held in place by means of plastic straps or the like or in that the containers are designed so that each container has one or more protruding, projecting tongues that extend over adjacent containers when the containers are arranged end to end on a conveyor belt.

Optionally, the conveyor which carries the blocks can be made to run down into a water container between the electrodes, whereby the necessity of using individual containers for the blocks is avoided.

Although the method according to the invention is particularly applicable when thawing cod and similar white fish, it is equally satisfactory for fatty fish such as e.g. Herring.

In order for the invention to be more easily understood, it will be described in more detail below in connection with an embodiment illustrated in the drawing. The drawing shows: Fig. 1 schematically a dielectric heating system for thawing frozen fish blocks;

fig. 2 and 3 are respectively cross-sections and ground plans of a container according to an embodiment of the invention and show the position of the container in relation to two adjacent containers.

The containers 1 in which the blocks of

frozen fish is placed, placed on a trans-

sports band 2 and is immediately led there-

after under a water shower 3 by means of which the containers are filled with water before they enter a first passage 4 which

rer to the dielectric heating furnaces.

Passage 4 is destined to reduce it

electrical interference produced by the dielectric heater.

After passing through the passage

4 the containers enter the first oven 5

which is supplied with electrical energy by radio-

frequency e.g. a frequency of between 30

and 40 Mc/c using a first gen-

tor 6. The containers then pass through a series of dielectric lifting ovens in each of which the fish is subjected to a further heating burn. The Individual heat-

furnaces are separated by interference

diminished passage 7 which is of a similar type to passage 4, but has a cor-

tere length, as the purpose of these pas-

bags is to prevent an interference between the individual generators 10 and 11. After passing the furnace 9, the containers are passed through an outlet passage 12 which has a similar design to the passage 4 and ma-

is then taken out from conveyor belt 2.

The container shown in fig. 2 and 3

consists of an outer bowl 15 and a lid in the form of an inner bowl 16. The side walls of the outer bowl are made with protruding tun-

ger, 17 which on one side is still arranged in relation to the tongues on the other side so that when the containers pass in order with their end edges lying against each other on the conveyor belt, the tongues on one side of a container will fit between the tongues on the 'adjacent side of the next closest container. As shown in fig. 2 extends the tongues of two containers

you on opposite sides of an inter-

generally remains above the upward-facing edges of the lid 16 in the intermediate container and in this way holds the largest

part of the lid's surface 'pressed down below the level of the top edge of the container. On

this way, the frozen fish will be prevented from floating above the water level.

The cover 16 can be in the form of a braided

works or can toa strips or fingers in an open structure that extends over the fish.

Although the invention is described in

connection with a heating apparatus of the type shown in fig. 1 can too

other forms of dielectric devices come into consideration. For example can it be frozen fish or other frozen foodstuffs

ler is passed under fixed electrodes which are supplied with current from a single radio frequency

generator and it can be arranged mid-

ler for setting the voltage which

is carried across the electrode as required.

According to another option, 'block-

of fish or other foodstuffs while immersed in a liquid, on

me place in the dielectric heating furnace during the heating period, and intensity

ten of the dielectric heating field is automatically varied in a predetermined manner as the thawing of the frozen fish block progresses. The containers can be placed in and removed from the oven in groups

show or they can possibly be placed on a conveyor which is moved step by step to style

lings in which a group of containers are located

settles in an oven to be transferred to the next oven after the next movement of the belt. The degree of heating of the fish in a particular oven can be adjusted by varying the voltage between the heating electro-

those by means of variable capacitors which are connected to the output of the radio-frequency generator and the working electrode.

Claims (4)

1. Procedure for thawing frozen fish or other frozen food means, during which a block of frozen foodstuffs is exposed to the influence of a radio-frequency operated dielectric heating device, characterized in that the block is kept submerged in water at least at car level for the upward-facing surface. 2. Method as stated in claim 1, characterized in that the block placed in a container passes through the dielectric heating apparatus on a conveyor belt on which, before entering the apparatus, it passes under a water source. 3. Container for thawing frozen fish or other frozen foodstuffs which are kept submerged in water by dielectric heating on a conveyor belt, for carrying out the method as stated in claims 1 and 2, consisting of a bowl (15) for receiving the frozen goods , which bowl is made with extensions (17) directed to the side from the upper edges of the bowl, which extensions overlap adjacent containers when the betools are arranged end to end, and which extensions thereby serve to retain the frozen goods below the level of the upper edges of the bowl's sides. 4. Container as specified in claim 3, characterized by a shallow inner bowl (16) which forms a lid, the up- and down-facing edges of the inner bowl being held down by means of the side-directed extensions (17) of adjacent bowls .