What is the drying process?
Drying means reduction of moisture contained on the surface of plates or in capillary pores of the material by evaporation upon supply of thermal energy, it is a process in which the heat and mass are simultaneously exchanged. The most common method is convection drying.
The drying consists of three processes and two stages:
1. The movement of vapour from the surface of the material to the ambient air.
2. The movement of moisture inside the dried material to its surface.
3. Phase transition of the liquid into vapour.
The first drying stage is characterised by constant drying rate. The moisture is evaporated from the surface of the plates and the created vapour gets into the drying air. The rate of the entire process is conditioned by diffusion rate of water vapour in the volume of drying air.
The second drying stage is characterised by decreasing rate of drying. The moisture evaporates in deeper layers of the dryied plates, movements of water vapour to the surface and diffusion in the layer of the flowing air. The type and thickness of the plates to be dried have considerable influence on the drying rate in the second stage.
What does the efficiency of the process depend on?
Three conditions must be met for the drying process to be most effective:
1. The drying air must have appropriate permissible temperature for particular types of plastics.
2. The material to be dried i.e. the plates must be properly ventilated (flown round by air).
3. The drying air must be maximally dry because the moisture can diffuse to the drying factor only if the vapour pressure in it is lower than the equilibrium (desorption of moisture); to conclude the drier the drying air, the shorter the drying process.
Developing drying technologies we followed the above dependencies to make our system as effective as possible.
Closed air circulation = lower energy consumption
As opposed to our devices, driers most commonly found on the market are adopted furnaces and adjusted to function as driers. These devices dry using ambient air, most frequently in the open cycle. The air heated at the entrance to the temperature setpoint is forced in the chamber and next removed outside. If it works in the closed circuit, the user must open it every hour in order to exchange the air for drier one, otherwise the moisture will not come out of the sheets.
From beginning to end our driers are prepared and adapted for drying plastic sheets and forms. They are distinguished by the system of drying air circulation, which above all operates in the closed circuit, allowing to reduce the electricity consumption of eighteen times. Finally, more economic and ecological system is created.
We adjust technology and dimensions of our devices to the needs of the contracting party:
We dry using dry air. Our system of drying air circulation includes the inbuilt air dehumidifier which considerably advances the process of drying. It has a direct influence on shortening the time of heating plastic sheets and forms.
In each device we install mechanical protection against overheating of the heated elements in the event of a failure of one of the actuators. We guarantee quick replacement of worn-out or broken components.
The drier has a touch-screen controller, which can be used to change the settings of the drier and monitor the current parameters of the operation of the device. The controller manages the drying room controlling temperature and time as well as monitors the operation of heaters, engines of the fans and dehumidifier engine. Failure of one of the devices stops the drying process and the error code appears on the display unit. The power cut causes the suspension of the drying process and when the power is restored the process is continued.
The controller allows to program the remote temperature ± 0.5 ºC, program the remote time as well as day and time of switching the drier on. For fire safety reasons the controller is controlled by two thermocouples placed inside the chamber.
The device allows for configuration of the account, thanks to which the access to functions is possible via the Internet connection. It allows for transfer of data via USB 2.0 or Ethernet and remote programming and monitoring of the drying process. Additionally, it is possible to set text message or e-mail notifications informing of the end of the process, failure or other occurrences.
Experience the advantages of our drier. Our device is designed from scratch to dry plastic sheets and forms. It takes into consideration the users’ individual needs and requirements so that they are fully adapted to the solutions used in their enterprises.
Owing to our solutions the process of thermoforming can be:
– more efficient,
– more effective,
– more economical.
Our drier is a convective dryer equipped with a chamber where dry air is the drying factor that flows around the hanging PMMA, ASA, PC, PSU, PES, PET sheets and forms. Side walls, the back wall, the ceiling and the door are made as a sandwich panel. The sandwich panel is made of two linings of sheet metal and ISOVER mineral wool insulation core having a thickness of 25 mm. The used type of boiler mat guarantees that for 20 years of exploitation the connections between fibres will not degrade under the influence of the temperature and the mat will not change its volume which could result in formation of thermal bridges. The floor is made of 10 mm thick sandwich panel. The thickness of the used core gives considerable thermal resistance which guarantees minimal heat losses during the drier explantation.
The single door can open to the left or right, can be lifted on servomotors to the drier level or in the guillotine system can pull itself vertically upwards – according to the clients’ needs. Regardless of the opening way the door is equipped with strong duty hinges which ensures long-standing, trouble-free operation.
The drier has self-supporting structure and is stands on four height-adjustable antivibratory feet.
The drier includes a cart which can be entirely moved from the chamber to the outside of the drier – it makes loading and unloading of sheets or forms easier without exposing them to mechanical damage.
Due to vertical position of sheets on the cart the air flows perfectly from all sides which obviously shortens the drying time.
The sheets or forms are hung on sticks of the cart with specially designed clamps which are previously put on the upper edge of the sheet. The place of contact of the clamping holder with the material is beyond the area of use. The very manner of fixing holders on the material is quick and easy.
Exemplary electricity consumption for our drying chamber including the following parameters:
– Dimensions of the loading chamber: 2245x2900x2240mm (depth x width x height)
– External dimensions: 2860x4300x4340mm (depth x width x height)
– Weight of the device: 4000kg
– Weight of the cart: 300kg
– The total power of the heaters 36 kW
– The drying chamber insulated with 300mm boiler wool
– Drying cycle: 16 hours
– The temperature setpoint in a given cycle: 120°C
– The total electricity consumption is~160 kW/h
The idea of construction, exceptional energy efficiency, user-friendliness - are the result of many years of experience of our company in plastics processing technology, which we have been engaged in since 1992. From years of experience in the industry we were able to produce all controllers and electronic parts on our own.