In the process of drying materials with a dryer, it is carried out according to different temperature differences between the inner and outer layers and different temperatures. If the temperature control is not within the specified range, some accidents will occur. In order to avoid this phenomenon occurrence, as an operator, he must lead by example, take every process seriously, and not be careless in the slightest. How to control the temperature difference and temperature between the inner and outer layers of the drum?
In order to grasp the effect of the material layer penetration wind speed of the dryer on the material heating rate and temperature distribution uniformity, under the condition that other conditions remain unchanged, the average penetration wind speed of the material layer is carried out on the material heating rate and the temperature distribution uniformity of the material layer. In order to find the suitable range of penetrating wind speed, the single-factor experimental research on the influence of During the test, the power of the far-infrared electric heating tube of the dryer is 9kW, and the thickness of the material layer is 150mm. In the material layer, the temperature rise of the material is measured at three positions near, middle and far from the far-infrared electric heating tube.
It can be seen from the test that when the penetrating wind speed of the material layer is small, the temperature of the material close to the electric heating tube rises faster; after starting to heat, the temperature difference between the inner and outer layers gradually increases, and after heating for 20 minutes, the temperature rise tends to be slow, and the temperature difference between the inner and outer layers Decrease gradually over time. This is because at the beginning of heating, according to the negative quadratic law, the radiation energy attenuates with the square of the radiation distance, resulting in a faster temperature rise in the inner layer of the material and a larger temperature difference between the inner and outer layers; after heating for 20 minutes, the temperature of the inner layer of the material It gradually tends to the highest temperature that can be heated under this condition. At this time, the hot air mainly exchanges heat with the middle and outer materials, causing the temperature of the middle and outer materials to continue to rise, so that the temperature difference between the inner and outer layers gradually decreases.
With the increase of the average penetrating wind speed of the material layer, the temperature increase of the inner layer of the dryer becomes slow, and the temperature difference between the inner and outer layers becomes smaller. This is mainly because when the penetrating wind speed increases, the heat exchange effect is strengthened, and the air flow transfers the inner layer heat to the outer layer material in time, so the temperature rise of the inner layer becomes slower, and the temperature difference between the inner layer and the inner layer becomes smaller. Obviously, when the penetrating wind speed is high, the material is heated evenly, but the temperature rise is too slow, which is not conducive to the drying process, and for a certain thickness of the material layer, the exhaust gas takes away more heat, the heat energy utilization rate is low, and the energy waste is large. If the penetrating wind speed is small, the inner layer material will heat up quickly and easily overheat. Therefore, considering comprehensively, the average penetrating wind speed range of the material layer is preferably 0.25-0.45m/s.
