Air cannon

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Air cannon is a de-clogging equipment composed of two main elements : a pressure vessel (storing air pressure), and a triggering mechanism (high speed release of compressed air). They are permanently installed on silos, bins and hoppers walls for all powdery form of materials, thus preventing caking and allowing maximum storage capacity.

Air cannons do not require any specific air supply. Available plant air is sufficient with a minimum of 4 bars air pressure (60 psi), although 5 to 6 bars are preferred for better results (75 to 90 psi). The average air consumption is moderate, and depends on the number of firing per hour, size of the pressure vessel, and number of air cannons installed. For instance, a 50-liter air cannon consumes 0.60 Nm³/hour at 6 bars air pressure (90 psi), with 2 firing per hour.

The compressed air contained in a pressure vessel is instantly released, and the achieved blast, called the impact force, evacuates material sticking to the walls (rat holing), as well as breaking potential bridging due to the shock wave produced. The blasts are usually organized by using an automatic sequencer.

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[edit] Operating principle

[edit] Phase 1: Air eating mode

Air supply from the air compressor passes through a 3/2 way solenoid valve feed, the Quick Release Valve (QRV), and reach the triggering mecanism with its piston disc in closed position. The air reservoir is then pressurized in less than 15 seconds, depending on the air pressure and air volume used.

[edit] Phase 2: Waiting mode

An air pressure equilibrium between air circuit, triggering mechanism, and pressure vessel is created. This is the waiting mode.

[edit] Phase 3: Blasting mode

When activated, solenoid valve purges the air circuit, thus creating an air vacuum. Then, the piston inside triggering mechanism is abruptly pushed back by negative pressure, thus creating a sudden blast from the air contained in the pressure vessel. This phase is measured in milliseconds. Then the cycle repeats again at Phase 1.

[edit] Design criteria and construction

An efficient air cannon should be designed to ensure:

  • Complete safety for the operators, thus avoiding harsh rodding or other manual cleaning methods;
  • A sturdy design, able to cope with the most severe operating conditions;
  • Easy maintenance, due to an easily accessible triggering device;
  • A metal-to-metal construction design, making the air blaster extremely reliable even in harsh environment (such as exposed to heat and/or dust);
  • A cost effective solution to all customers that prevents hopper, bin, and silo discharge interruption, as well as process disruption.

Usually two different versions exist:

  1. High temperature version: mainly for heat exchanger and cooler applications to remove clogging and to avoid costly plant stoppages and downtime;
  2. Low temperature version: to eliminate build up and dead stock of powdery and granular materials, thus preventing caking and enabling the optimization of storage capacity.

Air cannons, such as the Vortex Blastair, solve problems occurring in cement factories, among other industries, with blockages occurring in preheater towers (kiln inlet, cyclones, riser ducts, etc.) and in grate coolers, thus providing substantial savings.

[edit] References

[edit] External links

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