After finishing painting, it is necessary to polymerize the powder at temperatures from 180 0C to 220 0C, depending on the manufacturer of the powder. This process takes place in a polymerization oven. The stove is designed with a flat entrance and a perforated double floor for even distribution of heat and air flow. Furnaces for powder polymerization can be designed as:
– Batch (manual/automatic)
– Tact (manual/automatic)
– Flow (A – Stoves, automatic)
Fossil fuel furnaces
The power of the furnace is designed according to the power of the burner and heat exchanger. Depending on the set parameters of the burner, the power of the combustion chamber ranges from 120 to 200 kW. The set of firebox elements, burners, ventilation unit and thermal insulation is called Termo-blok. The total projected power of the furnace depends on its dimensions, and thus one or several Thermo-Blocks are installed for the purpose of even distribution of power.
The possibility of choosing the energy source of the WEISHAUPT aggregate: natural gas, oil and propane butane. The maximum power of the exchanger (Thermo-block unit) is 220kW. The thickness of the panel insulation is 180 mm PT Vunizola (100 kg/m3). Heating of the working space is made possible by air flow – air mixing through the heater (exchanger). Heat exchange is performed by air suction from the upper zone of the furnace and recirculation flow through the exchanger. Newly heated air is blown into the lower zone of the furnace. Heat removal from the exchanger is achieved by SCHIEDEL thermally insulated chimneys.
Due to the double perforated floor of the furnace, the entire system of the heating unit is under overpressure. This achieves even removal and distribution of heat exchanger / interior of the furnace.
The substructure is made of steel profiles and protected with a fire-resistant coating. Temperature regulation is double. The heat exchanger is made of refractory stainless steel that withstands temperatures up to 1100 0C and is thermally insulated with 180mm PT Vunizol insulation (100kg/m3). Air recirculation is performed by two 1.5 kW motors; 1420 0/min, which are driven by two Ø 450mm working wheels via pulleys and belts. One fan impeller has an air flow capacity of 4000 m3/h. The inlets of the working circuits are made of copper – Cu, ensuring safe and secure operation without the possibility of sparking inside the Thermo-block. Ex-ATEX construction and explosion protection are provided by this technical undertaking.
Temperature regulation is controlled automatically. Independent measurement, monitoring and regulation of the ambient temperature of the furnace, in relation to the temperature of flue gases, does not allow improper, inefficient and disproportionate burning of fossil fuels.
Electric ovens
Constructively, this type of stove is identical to a fossil fuel stove, and the difference is in the heat energy supply unit. It is the electric heaters that emit and radiate heat to the recirculating air, which transfers the heat and increases the ambient temperature of the furnace to a set value. The limiting factor of electric furnaces is the larger dimensions of the furnace, which require high electrical power, i.e. amperage. Thus, these furnaces have found application in low-volume production or dedicated industry where Ex – ATEX explosion protection requirements are more rigorous. The dimensional factor of electric furnaces has limited such furnaces to be efficient up to some dimensions of 4 x 2 x 2 m (L x W x H). Anything beyond that requires compromises in consumption and corresponding infrastructure needs. The construction of the electric thermal unit has a very small heated mass compared to fossil fuel burners, which requires the constant operation of the electric heater and the constant consumption of energy. For this reason, the electric thermal unit is constructed from a larger number of electric heaters in order to reduce consumption.
The thermal block of fossil fuels compensates for this disadvantage by being an aggregate, i.e., a combustion chamber of large mass. Its glow is able to emit and exchange heat for a certain time depending on the set temperature value without burning fossil fuels. This type of regulation allows efficient operation of the burner and low consumption at constant parameters.
IR ovens – Infrared ovens
Infrared furnaces are dedicated furnaces intended to be used as preheating zones in front of regular polymerization furnaces or in the MDF Coating industry, i.e. painting mediapan. Structurally, this type of furnace consists of a series of panel heaters that directly radiate the surfaces of the workpieces. The more these panels are, the more precise the temperature regulation by zones. Accordingly, IR heaters differ:
Electric
Natural gas / Propane butane / Oil
New technological discoveries in the technology of low-temperature polymerizing powders have created conditions for the application of powder colors in the MDF industry. Thus, the need for furnaces that can initially quickly heat surfaces to temperatures of 150 0C required the development of a new technological solution.
New solutions for the application of these furnaces as preheating zones for batch type furnaces opened up new challenges. By introducing a preheating zone, the possibility of mixing pigments of other colors on the surfaces of workpieces of different shades was prevented.
