Refreezing Conveyors | Tan Long Vietnam

Q: When does a plant need a re-freezing belt?

Khi dây chuyền có khâu mạ băng. Sau khi sản phẩm đi qua máy mạ băng, lớp nước trên bề mặt phải được làm đông lại trước khi vào bao gói, nếu không lớp áo băng sẽ không đều và sản phẩm dễ dính khối khi trữ kho. Băng chuyền tái đông đảm nhận đúng khâu này.

REF refreezing conveyor is the equipment that re-freezes the ice glaze on the product surface after the glazing stage, running in a chamber at -38°C to -42°C with a dwell time of only 2 to 15 minutes. It is not a replacement for an IQF belt freezer: the IQF cools the whole product mass, while the REF only treats the surface layer, so the two machines stand one after the other on the same processing line.

Tan Long designs and builds REF re-freezing belts in three capacity ranges 600, 900 and 1,200 kg/h (designated TMRF.600 / TMRF.900 / TMRF.1200) at our plant in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), for PTO, HLSO, HOSO, PD and Nobashi shrimp, fish, seafood and battered products. The equipment runs on both NH3 refrigerant and Freon.

What is a re-freezing belt? Operating principle and technical standards

REF refreezing conveyor

Outstanding technical characteristics of Tan Long refreezing conveyor

Super fast refreezing of a wide range of products including value-added and breaded products on the same conveyor.
High freezing capacity, low weight loss rate after freezing
Energy savings come from optimised design, maximising freezing capacity per unit of electricity consumed, together with the ability to self-balance the pressure inside and outside the freezing chamber, which minimises cold air loss.
Continuous operating time, no need to stop production to defrost the belt and evaporator up to 23 hours and when needed can run up to 48 hours without stopping the conveyor belt to defrost the evaporator
Specialized conveyor belt for freezing made of stainless steel with extremely high heat transfer coefficient, manufactured in EU
Easy to clean all parts inside and outside the conveyor belt. Drain the floor thoroughly after cleaning.
Design complies with HACCP/FDA standards for food hygiene and safety, high durability, stable operation, beautiful appearance
Safe and user-friendly control system designed for food processing environment with high stability and precision, ready to connect to all communication networks in SCADA system

Principle of refreezing

The product is continuously moved through the freezing chamber on a mesh conveyor belt specifically for food. Through the air distribution system, high-pressure cold air jets blow directly and continuously onto both the top and bottom of the product. These cold air jets circulate at high speed, continuously breaking the heat layers surrounding the product. This allows the cold air jets to directly contact and penetrate deeply into the product. Therefore, the product freezing process takes place very quickly, helping to preserve cell structure, reduce dehydration, and save operating energy.

Principle of refreezing

Freezer chamber insulation panel

Wall and ceiling panels are insulated with 125mm thick polyurethane, density 40-42kg/m3, sprayed with high pressure sprayer.

Wall panels: The inside is covered with 0.6mm thick SUS 304 stainless steel, the outside is covered with 0.8mm thick SUS 304 stainless steel with anti-scratch tape.
Ceiling panel: The inside is covered with 0.6mm thick SUS 304 stainless steel, the outside is covered with 0.6mm thick SUS 304 stainless steel with anti-scratch tape.
Background panel: The inside is covered with 1.2mm thick SUS 304 stainless steel, the outside is covered with 0.6mm thick SUS 304 stainless steel, cast and welded seamlessly, waterproof. The REF floor is sloped enough to drain water thoroughly during cleaning.
Doors for cleaning and performing repair and maintenance work

The door is insulated with 125mm thick polyurethane, density 40-42kg/m3. Both sides of the door are covered with 0.8mm thick SUS 304 stainless steel covered with anti-scratch tape. The door lock and hinges are made of SUS 304 stainless steel or plastic. The door is equipped with silicone gasket, anti-snow heating resistor and lock with anti-lock mechanism.

Conveyor

Using specialized mesh conveyor belts for seafood processing industry, made of stainless steel with high thermal conductivity, meeting the most demanding food hygiene and safety standards.

Condenser

The evaporator uses stainless steel or copper heat exchange tubes and aluminum fins depending on the refrigeration system. The technical parameters of the evaporator are calculated and selected in the most optimal way to ensure high heat exchange efficiency, continuous operation for a long time, saving energy costs. The evaporator is provided by famous suppliers such as Guntner, Thermofin, Kelvion (EU).

Evaporator fan

Fans are made of aluminum alloy, high performance, low energy consumption, supplied by Ziehl-Abegg or Rosenberg of Germany.

The fan motors are specially designed for IQF, with IP56 standards for complete insulation and moisture resistance. The motor housing is covered with a special protective layer that helps them operate durably in low temperature environments. The motors are supplied by ABB or WEG.

Control cabinet

The control cabinet is made of rust-proof stainless steel, has moisture-proof and waterproof functions. Equipment and components come from famous brands from the EU, USA or Japan such as Rockwell, Schneider, Siemens ABB and Mitsubishi.

REF re-freezing belt specifications (TMRF)
PARAMETER	UNIT	TMRF.600	TMRF.900	TMRF.1200
Freezing capacity	kg/h	600	900	1200
Product Type		Shrimp PTO, HLSO, HOSO, PD, Nobashi, fish, seafood, breaded
Product inlet/outlet temperature	⁰C	+10 / -18
Freezer temperature	⁰C	(-38 ÷ -42)
Refreezing time	minute	(2 ÷ 15)
Cooling capacity	kW	30	45	60
Refrigerant		NH3, Freon
Translation method		Fluid pump / LVS (Low Volume System)
Snow removal method		By hot water / gas
Conveyor type		Stainless steel mesh for food
Conveyor width	mm	1800	1800	1800
Panel shell size	mm	3700L3500W2900H	5000L3500W2900H	6200L3500W2900H
Insulated panel		125mm thick PU covered with 304 stainless steel, density 40-42 kg/m
Power supply		AC 380V / 3-phase / 50Hz

Which industries use re-freezing belts?

Below are the industry groups in which Tan Long has installed the most re-freezing belts:

Seafood processing: fish fillets, shrimp, squid and frozen export products.
Food and meat processing: carcass meat, cut meat and ready-prepared foods.
Agricultural produce and vegetables: vegetables and fruit that need rapid cooling after harvest.

Each sector has different requirements for temperature range, contact materials and capacity. Please contact Tan Long's engineering team for advice on the right configuration for your products.

Comparing mesh belt IQF, flat plate IQF and REF re-freezing belts

The three belt freezer lines Tan Long builds solve three different problems on the same processing line. The table below compares them on the actual parameters of each line:

Criteria	Mesh belt IQF (TMF)	Flat plate IQF (TSF)	REF re-freezing (TMRF)
Capacity	500 / 750 / 1.000 kg/h	500 / 750 / 1.000 kg/h	600 / 900 / 1.200 kg/h
Suitable product	PTO, HLSO, HOSO, PD and Nobashi shrimp, battered products	Fish fillets and whole fish, meat, battered products, agricultural produce	Already frozen goods that need surface re-freezing after glazing
Time in the chamber	3 – 55 minutes	5 – 30 minutes	2 – 15 minutes
Cooling capacity	120 / 180 / 240 kW	120 / 180 / 240 kW	30 / 45 / 60 kW
Conveyor type	Food-grade stainless steel mesh	Food-grade stainless steel flat plate	Food-grade stainless steel mesh
Conveyor width	1.800 mm	1.500 mm	1.800 mm
Shell dimensions (smallest version)	7.200 × 3.600 × 2.900 mm	10.700 × 3.300 × 2.900 mm	3.700 × 3.500 × 2.900 mm
Room temperature	-38 to -42 °C	-38 to -42 °C	-38 to -42 °C
Product inlet/outlet temperature	+10 / -18 °C	+10 / -18 °C	+10 / -18 °C
Refrigerant	NH3 or Freon	NH3 or Freon	NH3 or Freon

The most notable point in the table: the re-freezing belt needs only 30 – 60 kW of refrigeration capacity and takes up less than half the floor area of an IQF belt freezer, because it only re-freezes the surface layer after glazing rather than cooling the whole product mass. This is why the two machines complement each other on the same line instead of replacing each other.

Technical standards applied to re-freezing belts

Equipment supplied by Tan Long is manufactured to the following standards and material requirements:

HACCP
FDA
SUS 304 stainless steel
polyurethane insulation
NH3 refrigerant
Freon refrigerant
IP protection rating

Depending on each project's requirements, the engineering team will advise on the material configuration and connection standards that best suit the plant's existing system.

The re-freezing belt consulting and supply process at Tan Long

Tan Long controls both design and manufacture at its plant in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), so the investor deals with a single point of contact from survey to handover:

Survey and requirement definition: engineers work directly at the plant to establish capacity, layout, refrigerant and real operating conditions.
Technical proposal: calculating a suitable configuration and discussing it with the investor's technical team before it is fixed.
Detailed design: drawings are prepared and materials and equipment selected to match the refrigerant and the operating temperature range.
Manufacture and works testing: machining, assembly and a test run before the unit leaves the factory.
Installation and acceptance: connection into the plant's system, load testing and handover with the technical documentation.
Warranty and operating support: operating instructions for the plant's technical team and fault support during the warranty period.

Why choose the Tan Long REF re-freezing belt

The four points below are all verifiable, not self-assessment:

Criteria	Details
Manufactured in Vietnam	The chamber housing, frame and system are manufactured at the Tan Long factory in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An). Machine dimensions can therefore be adapted to the plant layout instead of having to take a ready-made imported configuration.
Genuine branded components	Güntner, Thermofin or Kelvion evaporators · Ziehl-Abegg or Rosenberg fans (Germany) · ABB or WEG motors · Rockwell, Schneider, Siemens, ABB, Mitsubishi electrical equipment · stainless steel belts imported from the EU.
Proven in service	29 projects since 2005. The plant at Kyokuyo Vina Foods alone received 08 high-speed IQF freezers (05 units at 500 kg/h and 03 units at 600 kg/h, 4,300 kg/h in total).
One party accountable	Design, manufacturing, installation, commissioning and maintenance by the same contractor — if the equipment fails to reach its design temperature, there is no need to arbitrate responsibility between several parties.

In-house manufacturing also pays off later: when an assembly needs replacing after years of operation, Tan Long can rebuild it to the exact original installation dimensions, so the plant does not have to modify the location or wait for imports.

Scope of work Tan Long takes on

Survey of the floor space, output per shift and main product types.
Calculation of the cooling load, selection of the machine configuration and the refrigerant (NH3 or Freon).
Manufacturing at the factory, with inspection before despatch.
Installation on site, electrical and piping connections.
Commissioning until the design temperature and output are achieved.
Handover of as-built drawings, commissioning records and operating instructions.
Regular maintenance under the contract.

Standard configurations of this line: TMRF.600 / TMRF.900 / TMRF.1200 — 600, 900 and 1,200 kg/h. Beyond these three levels, Tan Long also designs to the output of each individual plant — send us your output per shift and product types to receive a load calculation sheet and a quotation.

Which belt freezer to choose for your plant

Loose products, small in size, needing even cold air flow all around the product — shrimp, small seafood, battered items: choose mesh belt IQF freezer. The mesh surface lets cold air reach the underside of the product as well.
Portioned products that must keep a clean flat surface with no mesh marks — fish fillets, meat portions: choose the flat plate IQF freezer. In return, at the same capacity the machine is about 40 – 50% longer.
Already frozen goods that have passed through glazing and need the ice glaze re-frozen: choose the REF re-freezing belt, usually installed immediately after glazing machines on the same line.

When the choice of line is not yet clear, the right approach is to calculate the output per shift and the main product types first, and only then settle on the equipment. Tan Long provides design consulting and cooling load calculation before quoting.

Frequently asked questions about the REF re-freezing belt

How does a re-freezing belt differ from an IQF belt freezer?

The difference is the job they do. An IQF belt freezer cools the whole product mass from +10°C to -18°C, needing 3 to 55 minutes and 120 to 240 kW of refrigeration capacity. A re-freezing belt only re-freezes the surface ice glaze after glazing, needing 2 to 15 minutes and 30 to 60 kW. The REF is therefore smaller, uses less electricity and is installed in series after the IQF rather than replacing it.

When does a plant need a re-freezing belt?

When the line includes a glazing stage. After the product passes through the glazing machines, the water layer on the surface has to be frozen again before packing; otherwise the ice glaze will be uneven and the product will tend to stick together in storage. The re-freezing belt handles exactly this stage.

How much floor space does a REF re-freezing belt need?

Panel shell dimensions by capacity: TMRF.600 is 3,700 × 3,500 × 2,900 mm, TMRF.900 is 5,000 × 3,500 × 2,900 mm and TMRF.1200 is 6,200 × 3,500 × 2,900 mm. Compared with an IQF belt freezer in the same capacity group, the REF takes up less than half the length — an advantage when an extra machine has to be fitted into an existing line.

What is the refrigeration capacity of the re-freezing belt?

30 kW for the 600 kg/h version, 45 kW for the 900 kg/h version and 60 kW for the 1,200 kg/h version. These figures are far lower than an IQF belt freezer of the same output because the machine only treats the surface layer. This load still has to be added to the total compressor capacity when calculating the plant load.

What type of belt does the re-freezing belt use?

A stainless steel mesh dedicated to food use, 1,800 mm wide, with high thermal conductivity. The chamber housing uses 125 mm PU panel at a density of 40–42 kg/m³ clad with SUS 304 stainless steel. Defrosting is by water or hot gas, with liquid feed by liquid pump or LVS.

Does Tan Long build the re-freezing belt in house or import it?

Tan Long designs and builds the chamber housing, frame and system at our plant in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), so dimensions can be adapted to the available floor space. Assemblies requiring high precision are imported: Güntner / Thermofin / Kelvion evaporators, Ziehl-Abegg or Rosenberg fans (Germany), ABB or WEG motors, and Rockwell, Schneider, Siemens, ABB, Mitsubishi electrical equipment.

Request consulting and a belt freezer quotation

Tan Long designs and manufactures freezing belt systems at its factory in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), so capacity and dimensions can be adapted to the actual layout of each plant. Call 0933 357 058 (Mr. Thinh) or send a quotation request with your output per shift and your main product type.