KJG-140 Belt Dryer for Wet Sludge

The dewatered sludge, with an average solid content of 25%, is transported by vehicles, weighed via a truck scale, and then unloaded into a discharge hopper equipped with a bottom sliding frame system. Two high-pressure screw feed pumps are installed at the lower part of the discharge hopper to pump the sludge into the drying machine's spreading device (i.e., the noodle-making machine). The spreading device is positioned above the upper belt of the drying unit. As the filter belt moves forward, the spreading device shifts left and right. The coordinated movement speed between the spreading device and the filter belt ensures that the belt surface is covered with strip-shaped sludge of a certain thickness and spacing, facilitating uniform sludge drying. The drying unit consists of four layers of filter belts arranged vertically, allowing air to pass through. At one end of the upper belt, a layer of dewatered sludge of a specific thickness is laid, and the sludge on the filter belt moves slowly forward within the drying unit. Partially dried sludge falls from the other end of the upper belt onto the lower belt, which moves the sludge in the opposite direction within the drying unit. As the sludge moves through the drying unit, it is slowly dried by airflow, gradually reducing in volume. To maintain a consistent thickness of the sludge layer on all filter belts, the lower belt moves slower than the upper belt, with each filter belt equipped with its own variable-speed motor. Air enters from the lower side of each drying belt, passes through the drying belt, and exits from the top of the drying machine. As the air flows through the sludge layer, it absorbs and carries away moisture, drying the sludge. Most of the low-temperature, humid air extracted by the exhaust fan is reheated via a heat exchanger and reintroduced into the drying machine for further sludge drying. A small portion of the low-temperature, humid air first passes through a heat exchanger, where the exchanged heat is used to preheat gas returning to the system after passing through a condenser, thereby saving energy. The preheated gas is then heated to the required temperature via another heat exchanger before being reintroduced into the drying machine system. The gas that needs to be discharged daily undergoes chemical and biological deodorization before being released outside the facility in compliance with standards. At the end of the lowest drying belt, there is a cooling zone where the sludge naturally cools to approximately 40°C before being sent to the dry sludge conveying system.