What is an industrial oven
Industrial ovens are heated chambers, commonly used in high-temperature processing of raw material that may come in a liquid or solid state of aggregation, for different industries like ceramics, chemical, steel, glass, brick, tyre, metallurgy, sintering etc., and for a variety of industrial applications, for numerous components, parts or final products. They are suitable for large or small volume applications, in batches or continuously, with a conveyor line and several temperature ranges, sizes and configurations.
We use them in broad spectrum of heat treatment processes like tempering, normalization, annealing, sintering, nitriding, carbonitriding, baking, drying, curing or heating prior to smithing, pulling, improving the structure of products and altering their physical properties.
These devices can be classified based on several different criteria like their technological purpose (melting, heating, heat processing, sintering, drying), chamber design (cave, line, rotary, tunnel, chamber), heat source (gas, mazut, coal, electricity, no external heat source), the way how they utilise heat from gas emissions (recuperative, regenerative, without heat exchangers) etc.
Common types of industrial ovens
Different products off course demand different types of heat treatment. So, let us talk about most common types of industrial ovens, used for many different purposes.
While curing ovens are designed to cause a chemical reaction in a substance, once it reaches a specific temperature, and drying ovens remove moisture (typically used for pre-treating and painting), baking ovens combine functions of the first two.
Reflow Ovens are used primarily for reflow soldering of surface mount electronic components to printed circuit boards (PCB). Generally they have several heating zones followed by one or more cooling ones.
Batch ovens (also called cabinet, Walk-in or Truck-in ovens) facilitate curing, drying or baking in small batches, using wheeled racks, carts or trucks. They are often used in places like large-volume supermarkets bakeries.
Conveyor or Continuous Ovens typically play parts of automated conveyor processing lines, and usually allow higher processing volumes. They provide consistent and systematic thermal processing options for mass-produced parts and are specially designed for heat treatment of the items that run on conveyors.
Chamber ovens are designed for heating products loaded on carts. The larger carts are powered and usually placed on tracks. The oven’s negative pressure zone has a built-in burner for heating. Both, the manner of loading products onto the carts, and size of ventilation systems, impact the speed of heating and the evenness of products.
Continuous ovens represent the ideal combination of infrared heaters and ventilation systems with burners for a quality paint finishing and baking. They are usually intended for colour curing after powder coating. The dyed pieces travel through the device, designed as a heating tunnel. The transport is facilitated by the chain transporter. The heating is done through a combination of infrared heaters, interchangeably placed throughout the oven, capable of heating the side of the channel in the interim between two pieces. As a result, the outside surfaces are heated quickly as well. Ventilation systems of continuous ovens are equipped with channel burners. This method of curing or paint finishing is suitable for products with a large exterior surface, which later travel along the other part of the oven, where the paint finishing process ends with the help of convection.
Ovens for heating products below 600 °C
Industrial ovens for heating products bellow 600°C are meant for heating products to the prescribed temperature. The evenness of products and their temperature can be achieved through mixing the oven atmosphere with the air flow vents. These sorts of devices are usually insulated using mineral wool that prevents heat loss and equipped with a double ceiling and walls, ensuring proper air circulation. The supply and return air ducts have temperature sensors built-in for each zone.
High temperature ovens
The unique feature of high temperature industrial ovens is their insulation, as each cycle needs to be heated and cooled-down again, constituting significant energy loss. Therefore, ovens for heating products at temperatures above 1000˚C are equipped with a frame and appropriate insulation, that is carefully selected, based on the atmosphere, temperature and the type of oven. It can be done using different types of refractory ceramic wool, grog brick of different shapes and qualities, or refractory concrete.
To achieve evenness, chamber ovens have built-in burners that mix the atmosphere with strong impulses. Due to the high speed and the types of these impulses, the smoke fumes that are released into the atmosphere from the mouth of the burner, act as an atmosphere mixers. With extremely high-temperature ovens, where the work temperature can exceed 1200°C, radiation is the main transmission tool. Special radiant burners enable the heating of large radiant surfaces, like for example ceilings and walls.
Ovens can be heated either directly, or indirectly, when also the product heating occurs indirectly in the required oven atmosphere (reduction, oxidation). The unique characteristic of high-temperature ovens is the use of recuperative and regenerative burners that allow for greater energy efficiency.