Automatic thawing of single frozen fish

THAWING SYSTEM

THE SYSTEM

UNI-FOOD TECHNIC A/S — QUALITY FOOD PROCESSING EQUIPMENT

EMPTYING STATION / IN-FEED CONVEYOR This emptying system consists of an operator platform from where the operator empties the fish onto the out feed con-veyor. The operator receives the fish from the pallet lift, and places the empty boxes on an upper take-away conveyor. The in-feed conveyor for the two de-frosting tanks are equipped with one fixed guide and one automatic pusher arm, for guiding the fish into the two de-frosting tanks. The automatic pusher arm is controlled by the operator that is emptying boxes onto the conveyor.

• Motor: Drum, variable speed.

• Belt type: to be agreed upon.

• Belt width : 1200 mm

• Design: Hygiene design

• Dimension: 7500 x 1556 x 2500 mm

• Belt wash: Can be delivered with automatic control, that enables the belt wash to run when the belt is moving, only , or in intervals of e.g. five minutes.

• Sidebars can be flipped for easy cleaning.

• Material: AISI 304

• Electrical connection: 3x400V + PE, 50Hz

• Pneumatic controlled flipping arms. DESLIMING / DE-SCALING / FRESH FISH Depending on the season, price and product demand, some producers purchase both single frozen fish and fresh fish. This system is produced to meet the alternating needs that these producers face. To avoid unnecessary bacteria accumulation in the further process, we always recommend the producers to descale or at least de-slime fresh fish before entering the VAP section. When fresh fish are to be processed the thawing tanks can be used as cooling/ buffer tanks, ensuring that the fish are kept at a certain temperature before entering the VAP area. THAWING TANKS These two tanks have the purpose of thawing single frozen fish before filleting. The thawing process takes up to eight hours depending on the fish size. The thawing process is controlled by using different parame-ters. Firstly, for the system to learn how to make the best

thawing of the fish and secondly, to use best practice for the future process. First, the tank thaws the fish. When the center temperature reaches –1° Celsius the tank starts the cooling process in order to keep the fish cold until it moves forward for further processing. The tank is therefore used both as a thawing tank and cool-ing tank and can - if necessary - also be used as a bleeding tank. The system can be made in accordance to customer needs, depending on the chosen cooling and heating system. SYSTEM DESCRIPTION Each tank can contain 6000 kg of fish. In this case, the ratio between fish and water is 1:2. In each tank there are six compartments, the four in the middle measuring 2.3 m3 and the two at the end measur-ing 4.4 m3. This means that each of the four compartments in the middle contain 760 kg fish and the two end compart-ments each contain 1480 kg each. FILLING THE TANK WITH WATER The tank is equipped with an adjustable level control [L].

When the tank is to be filled up before processing the valve [V7] will open for the fresh water (or alternatively sea wa-ter). When the water level reaches [L3] the [V7] will close. When the water reaches [L1] the heating/cooling process can begin. During this process the water needs to be taken from the bottom side of the tank. To do this [V1] will be open and [V2] will be closed. The pump [P1] generates the water circulation. Before the water enters the pump it will be filtrated by [F1] (a self- cleaning rotary filter). After the filter the water passes the chamber for steam in-jection, which is used when the water needs to be heated. The steam injection is controlled by [V3]. The steam cham-ber is placed before the pump to ensure that the steam will be injected into the water. The input pressure of steam must be higher that the pipe water pressure. Whenever the water needs to be heated or cooled down depends entirely on the process and the temperature cho-sen. E.g. if the temperature is set to be 12° Celsius, [T2] will measure if the temperature is higher or lower than this. When [T1] equals [T2], [V3] will close.

UNI-FOOD TECHNIC A/S — QUALITY FOOD PROCESSING EQUIPMENT

The two butterfly valves [V4] and [V5] will direct the water through the cooling system or around it. If the tank is to be used for thawing, the cooling system will not be activated, no matter what temperature has been cho-sen. As soon as the fish drops into the tank the water tem-perature will quickly decrease. If chemicals are to be used, and the concentration can be defined by a pH-value the system can be equipped with a pH-gauge, a mixer for water and chemicals, a pump [P2], and a valve [V6] that will control the injection. When to add the chemical is to be decided by the user. E.g. the user picks pH 10.5 as low, and pH 12.0 as desired. The system will then start pumping chemicals into the tank when the level is below 10,5 and stop when it has reached 12.0 When the tank is full, the water has the right temperature and the pH-value is correct a light tower will indicate that the tank is ready to receive fish. FILLING UP THE TANK WITH FROZEN FISH The operator empties fish boxes into the six compartments. There is a visual indicator showing which compartment is being filled. When one compartment is full, the operator needs to press a button to move the pusher arm to the next compartment. Being able to change from one compartment to another two sensors are used. The first sensor registers that the pusher arm is in the correct position for the next compartment to be filled, the second sensor registers the position from where the pusher arm needs to stop in order to have enough space for the last fish to enter the compartment. THAWING AND COOLING PROCESS The [P1] will control the water flow in the tank and ensure that the water is perfectly mixed in order not to have tem-perature variations in the water. The water will enter the tank through a pipe system at the bottom side of the tank. This serves as a Jacuzzi system ensuring that the water is spread evenly all over the tank. The pump circulates up to 100 m3/h, ensuring that the wa-ter temperature will be more or less even throughout the thawing process. [T1] measures if there is a need for steam, and [T2] ensures that the water entering the tank is not too hot. These measurements are used to set the control valve.

When the water level is under level [L4], [V7] will open and close again when the water level has reached [L5] again. PROGRAM FOR THAWING Due to the constant water temperature, the thawing time for 1 fish equals that of 6 tons. The only difference is the energy needed for heating the water. The system has a variety of different programs, which are all based on the same programmable platform, that enables the user to make the perfect thawing process at all times. Program one: This program is based on the following mathematic setup and variables. Time cycle (1,…,N) Temperature [T2] [define], Time [define] It is possible to define N time cycles, defining max/min tem-perature, for how long the process will last, before changing to the next time cycle. The final cycle depends on when the tank is empty, and is therefor defined as “maintain [MT]”. Example:

Time cycle 1|Temperature [T2] [12 C], Time [2 H] Time cycle 1|Temperature [T2] [8 C], Time [2 H] Time cycle 1|Temperature [T2] [6 C], Time [2 H] Time cycle 1|Temperature [T2] [4 C], Time [MT]

Program two: It is possible to program the thawing process by using one fish and two sensors. One sensor is placed to measure the center temperature and one to measure the temperature in the belly, as this is the part of the fish that will thaw first. The process is controlled as follows. One frozen fish will be equipped with the two mentioned sensors. Temperature cycle (1,…, N) Temperature [T2] [define], until T5inside is [define] The last will be. Temperature cycle MT (maintain) |Temperature [T2]

[define], when T5inside is ≥ [same as the last cycle]

THAWING SYSTEM Example:

Temperature cycle 1|Temperature [T2] [12C], until T5inside is [-8C]

Temperature cycle 2|Temperature [T2] [8C],

until T5inside is [-3C]

Temperature cycle 3|Temperature [T2] [6C], until T5inside is [-1C]

Temperature cycle MT |Temperature [T2] [4C],

until T5inside is ≥ [-1C] PROGRAM FOR COOLING Likewise, due to the constant water temperature, the cooling time for 1 fish equals that of 6 tons. Again, the only differ-ence is the energy needed for cooling the water. The cooling system is designed to generate the necessary amount of cold water. Program three: This program is based on the following mathematic setup, and variables.

Time cycle MT | temperature [T3] [define, Time [define]

Example:

Time cycle MT | temperature [T3] [4C], time [MT] EMPTYING THE TANK FOR FISH The first operator at the filleting line, normally the de-heading operator, will be provided with an operator control box. From here he can empty the tank, one compartment at a time. If the compartments contain too many fish, each compart-ment can be emptied in two or three steps. CLEANING PROCESS When the tank needs to be emptied the procedure will be as follows. Firstly, the tank is emptied for water. Secondly, the filter needs to be cleaned. When this is done the tank is filled with water until level [L2] by opening for [V7]. Detergent is filled into the tank manually. When this is done pump [P1] is started. It will circulate for 15-20 min. in order to be able to clean the entire system. After this the tank is emptied again. The system is programmed to meet the specific customers needs. The setup for further processing depends on the product, capacity per hour etc. Two examples of a filleting line is pictured below.

Tel.: +45 9677 4100 Info: uft@uni-food.dk Sales: sales@uni-food.dk

UNI-FOOD TECHNIC A/S Jellingvej 30 DK-9230 Svenstrup

Web: www.unifood.tech