Air cannon systems prevent the buildup of materials in transfer chutes, storage vessels, and process equipment
Air cannon systems prevent the buildup of materials in transfer chutes, storage vessels, and process equipment such as preheater towers and clinker coolers.
Sometimes called blasters, air cannons shoot bursts of compressed air into a chute to dislodge built-up materials. The systems are reservoirs of factory-compressed air attached to fast-acting discharge valves and tied to a system that controls the pattern of the bursts. Because of the higher speed of escaping air, blasters effectively keep a wide area free of buildup, and carefully designed systems keep an entire chute clear.
The nozzles from which air is released are embedded within the chute wall, each connected to a separate air cannon or a larger central air reservoir. These nozzles should all be positioned to direct the blast toward the outlet or direction of flow. The nozzles must be carefully designed to dislodge any materials that build up so they do not offer additional edges on which materials can catch and accumulate. This generally means embedding them below the level of the chute wall. Nevertheless, the movement of the bulk material may wear the nozzles, and larger lump sizes can deform or destroy the nozzles.
The number and distribution of air cannons in a chute depends on the types of materials and the design of the chute, but in general, one air cannon can usually keep clear an area between 1.5 and 2 square meters (15 to 20 square feet).
Air cannons with an air volume of 50 liters (1.75 cubic feet) have shown good results in chute applications, but these systems come in multiple sizes, both in terms of air reservoir and discharge diameter.
In addition to the size of the air cannon, designers should vary the firing sequence to meet the conditions of the chute, the materials being conveyed, and the local climate. Once an appropriate sequence is established, it can be programmed into an automated system so the system will not require further attention from personnel.
Air cannons are used with sticky material that cannot be effectively cleared by vibrators. These materials often create less dust, limiting concerns about added air pressure. However, for materials that will produce dust, conveyor systems should account for the added positive air pressure created by air cannons.