Blindly Increasing Exhaust Air Volume Is a Major Misunderstanding of Modern Tunnel Kiln Drying Chamber Design
In recent years, a serious design misunderstanding has spread in the field of tunnel kiln drying chamber optimization: the larger the exhaust air volume, the better the drying effect. Influenced by this wrong concept, supporting fans of drying chambers have been continuously upgraded. Traditional small-power axial flow fans have been gradually replaced by high-power centrifugal fans, and the fan power and air volume show an endless upward trend.
In actual industrial production, 3.6m-wide drying chambers are equipped with No.18 centrifugal fans, and 4.8m-wide drying chambers match No.22 centrifugal fans, with motor power ranging from 75kW to 110kW. The power consumption of these high-power fans is more than double that of traditional axial flow fans, causing huge and unnecessary electric energy waste for brick and tile enterprises. Worse still, blind air volume increase cannot solve the core drying problem, and winter green brick collapse still occurs frequently.
Taking the 6.9m tunnel kiln production line of Tai’an Huatai Building Materials in Shandong as a typical case, the original drying chamber is 79.1 meters long, equipped with 4 sets of GD30K2 axial flow dehumidification fans. The single fan air volume is 44,000 m³/h, the total designed exhaust air volume reaches 176,000 m³/h, with stable configuration parameters. However, the production line has suffered from persistent winter brick collapse since its commissioning, and various conventional adjustment measures failed to achieve a radical solution.
In 2016, the production line was technically renovated. The original 4 high-air-volume fans were replaced with 2 optimized fans, with single air volume of 58,000 m³/h, wind pressure of 500Pa, and motor power of only 11kW. After the renovation, the total exhaust air volume was reduced to 66% of the original design, and the total power was only 73.3% of the original. Surprisingly, the production line operated stably throughout the winter without a single brick collapse, and the daily output increased by nearly 100% compared with before.
Another typical negative case is a 7.2m drying chamber in Jiangxi, equipped with 7 sets of 11kW exhaust fans, with a total installed power of 77kW and a total exhaust air volume of 329,000 m³/h. With such a super-large air volume configuration, the production line still cannot avoid winter blank collapse, which fully verifies that drying effect is not positively correlated with exhaust air volume.
It is undeniable that the increasingly strict environmental protection policies require dehumidification flue gas desulfurization. The newly added desulfurization tower increases system resistance, so it is necessary to properly optimize fan power and air volume. However, unlimited air volume superposition is a typical inefficient design, which only increases operating costs without improving drying quality.
