Gas burners or quartz infrared heaters have a certain history of development in the drying of paper machines and coating machines. Infrared radiation is invisible light, and heat is transmitted through electromagnetic wave radiation heating without direct contact to the heated object. The infrared peak wavelength of gas burner is about 3-4 microns, which has a good drying efficiency on the surface of the paper board. The quartz infrared heater has a smaller peak wavelength, about 1-2 microns, and has a strong penetration effect, which has a good drying effect on the inside of the paper board. The radiation energy utilization rate of quartz infrared heating is as high as 80%, while the infrared thermal energy utilization rate of gas burners is only 50%. At the same time, it is accompanied by the emissions of greenhouse gases such as carbon dioxide.

1. The application of infrared drying on tissue paper machines can improve the lateral moisture unevenness of the paper web, reduce the fluctuation by half, and increase the output by 5-10%. Infrared radiation energy(E) is proportional to the fourth power of absolute temperature（E=XT⁴）. Therefore, the higher the temperature of the heating element, the stronger the infrared radiation energy. Generally, the temperature of plate heaters is only 550℃, the infrared temperature of gas burners is about 1100℃, and the infrared temperature of the tungsten alloy heating wire of quartz infrared heaters can reach about 2200℃. The maximum infrared radiation energy density of quartz infrared heaters can reach 360kW/m2. As long as there is no fire risk, the heater can be allowed to be 6cm away from the paper surface without risk of fire. If a head breakage occurs, the infrared heater needs to be shut down immediately within 1 second and cooled down. Air cooling or water cooling can be used. No flammable materials are allowed near the IR heaters, and operators must check frequently.

The absorption efficiency of IR energy depends on the quantity of paper and its surface reflection. Low weight paper requires a reflector. Firstly, the IR energy reflected from the paper is returned to the paper through the reflector, and secondly, the IR that penetrates the paper is also returned to the paper through the reflector.

Research has shown that using an infrared heater before paper pressing increases the temperature of the wet paper sheet and reduces the viscosity of the water, thereby allowing for more dehydration in the pressing section; Or increase the speed to increase production, with an average increase of 10℃ in the wet paper temperature, the dryness of the wet paper can be increased by 1%.

Through experiments, the installation of IR can increase production by an average of 7%, and the average power consumption is much less than that of steam drying. After using quartz IR heaters, in addition to increasing production, it can also reduce paper roll damage, improve the horizontal moisture uniformity of the paper web, and improve the calendering efficiency.

2. Quartz infrared heater for coating machine

The quartz infrared heater installed behind the scraper allows the coating agent to dry quickly, avoiding migration caused by the absorption of water and adhesive in the coating agent by the original paper, and improving printing quality.

During the coating process, as soon as the coating agent comes into contact with the original paper, the adhesive begins to migrate. The moisture in the coating agent moistens the fibers of the original paper, and the adhesive begins to flow into the original paper. Under the pressure of the scraper, the coating agent is forced into the base paper, causing it to firmly bond with the base paper, and the migration of the adhesive begins to become a capillary process. The longer the residence time of the coated paper before infrared drying, the more liquid and adhesive migrate from the coating agent to the original paper. The unevenness of the original paper surface affects the micro thickness of the coating layer, causing changes in the flow of the adhesive, resulting in local uneven concentration on the coating surface. When the drying process reaches the gel point, the flow of the adhesive/water slows down, and the relationship between the adhesive/solid is fixed, which may lead to the speckle phenomenon and affect the printing quality. The longer the time before curing of the coating agent, the more uneven the micro-morphology of the paper surface. Immediately fixing the coating agent through infrared drying after the scraper is removed will improve the coating quality and prevent spots. The rapid heating of the quartz infrared heater can help complete the above tasks.

The short-wave infrared radiation heater has a high amount of radiation. The wavelength when the IR emits the highest energy is proportional to the fourth power of the absolute temperature. The peak wavelength of short-wave infrared radiation is 1.0-1.4 microns, which can penetrate into the inside of the paper, from one side of the paper Heat evenly on the other side. Infrared rays that pass through the paper can also be reflected back to the paper using a reflector. For thin paper, such as paper with a basis weight of 65g/m2, energy utilization can be increased by 40% with a reflector rather than without a reflector. For cardboard of 300g/m2 and above, since the cardboard can absorb all IR radiation energy, there is no need to use a reflector.

Infrared Heating

Quartz Infrared Lamp

Short Wave Infrared Lamp