In many areas of industrial production, assembly line drying tunnels are used, especially in large-scale coating plants, food processing plants, textile printing and dyeing plants, etc., which are used in many fields. Industrial drying tunnels are also called drying chambers, drying furnaces, tunnel kiln, etc. The design schemes are various. Generally, the design and construction of a project is completed through certain design verification according to the workpiece size and design experience. Today, Infrared Heating Tube Supplier share a bridge drying tunnel.
The bridge type drying tunnel has many advantages over other types of drying tunnels. The oil smoke at both ends is less spilled, so the environment of the workshop is clean and sanitary, and the noise of the air curtain is also relatively small in the exhaust. The bridge type drying tunnel can make full use of the air in the workshop. The horizontal part of the whole drying tunnel is in the air. The bottom of the drying tunnel can prevent electrical cabinets, tool boxes and other items, and the space utilization rate is higher. The uphill and downhill sections of the bridge tunnel are longer and can be used as preheating and cooling stages for the workpiece, increasing the initial investment of the equipment, which is also a disadvantage of the bridge tunnel.
Carbon Infrared Emitters
The structure of the bridge drying tunnel is generally composed of a furnace body skeleton, an insulation layer, an infrared radiator, and a high temperature resistant conveyor belt. The skeleton is generally made of angle steel or channel steel. The thickness of the insulation cotton is between 80mm and 150mm, and the design temperature of the drying tunnel surface does not exceed 50 degrees. Considering the installation and thermal expansion, the drying tunnel is generally designed to have a length of 2 m, and the joints are bolted between the sections.
The infrared radiator of the drying tunnel can be selected from a carbon fiber heating tube and a tungsten wire Infrared Heating Tube. The design of the ventilation system needs to take into account the exhaust gas or solvent emitted during the drying of the workpiece. The main purpose of the design is to ensure that the concentration of flammable and explosive vapor in the drying tunnel is kept within 50% of the explosion limit, except for the exhaust on both sides of the drying tunnel. Outside the hole, one more row to two rows of venting holes should be added to the drying section where water and solvent are most discharged. Otherwise, harmful gas with a large concentration will easily leak in the workshop, which will cause an explosion accident.
When the carbon fiber heating tube is selected, it is necessary to carry out a simulation experiment in the simulation experiment device. Before this, it is necessary to perform infrared absorption spectrum test on the selected paint, and select the carbon fiber heating tube of the optimal band. Then select the appropriate radiator based on the experimental values. However, the composition of the coating is relatively complicated, and the infrared absorption flavor is generally more than one, corresponding to the medium temperature heating and high temperature heating, so the drying tunnel design needs to select the medium temperature band or the high temperature band according to actual needs.
However, when selecting the drying temperature section, it is better to compare it with the experimental scheme. In the experiment, the directional radiation is used to test, obtain the test data and the process temperature curve of the workpiece, and determine the surface temperature of the carbon fiber heating tube and the distance from the workpiece. Workpiece surface temperature. For the different drying stages of heating, constant temperature and cooling, a suitable carbon fiber heating tube is selected as the infrared radiator.
In the actual use process, a problem was found. Although the design of the drying tunnel was well considered, the carbon fiber heating tube was arranged very evenly, but the temperature inside the drying tunnel still showed high upper temperature and low lower temperature. The maximum temperature difference was As much as 60 ° C. Why is this? The main reason is that although the carbon fiber heating tube is mainly heated by infrared radiation, the surface temperature is high, and the phenomenon of heat convection cannot be avoided inside the drying tunnel, resulting in a phenomenon of high top temperature and low bottom temperature. We can divide the cross section of the drying tunnel into three upper, middle and lower regions. The density of the heating pipes is different in different regions, and the heating pipes are arranged according to a certain ratio, so that the problem of large temperature difference can be solved.
The above is a description of the Carbon Infrared Emitters manufacturer's precautions for carbon fiber heating tubes, hoping to help everyone.