How the axial flow forced draft fan works

The axial flow forced draft fan makes use of the change of the installation angle of the moving blade to shift the performance curve of the forced draft fan. A series of working points can be obtained from the performance curve, different installation angles of moving blades and performance curves of air ducts. If the flow rate and pressure head need to be increased, only increase the installation angle of the moving blade; On the contrary, it is only necessary to reduce the installation angle of the moving blade. The moving blade adjustment of axial flow forced draft fan has high adjustment efficiency, and can make the adjusted fan work in the high efficiency area. The axial flow forced draft fan with moving blade adjustment can also avoid falling into the unstable working condition area under low flow conditions.

The adjustment of moving blades of axial flow forced draft fan makes the fan structure complex, the requirements for adjusting devices are high, and the requirements for manufacturing accuracy are also high. Changing the installation angle of the moving blade is implemented by the moving blade adjusting mechanism, which includes a hydraulic adjusting device and a transmission mechanism. The piston in the hydraulic cylinder is axially positioned by the shaft sleeve and the shoulder of the piston shaft. The hydraulic cylinder can move left and right on the piston, but the piston cannot move axially. In order to prevent leakage through the clearance between the piston and the hydraulic cylinder when the hydraulic cylinder moves left and right, the piston is also equipped with two rows of grooved seals. When the impeller rotates, the hydraulic cylinder rotates synchronously with the impeller, and the piston also rotates due to the rotation of the shield and piston shaft.

Therefore, when the fan works stably under a certain working condition, there is no relative movement between the piston and the hydraulic cylinder. The other end of the piston shaft is equipped with a control shaft. When the impeller rotates, the control shaft is stationary, but when the hydraulic cylinder moves left and right, it will drive the control shaft to move together. The control head and other parts are stationary and do not rotate. The blade is installed at the outer end of the blade handle. Each blade is fixed on the blade handle with 6 bolts. The blade handle is supported by the blade handle bearing. The balance block and the blade are installed at a specified angle. The displacement of the two is different. The balance block is used to balance the centrifugal force, making the blade adjustable during operation. The moving blade adjusting mechanism is surrounded by the impeller and the shield, so that it can work safely, prevent dirt from falling into the adjusting mechanism, and make it flexible or not jammed.