In the bulk material storage and handling industry, material caking and blockages in silos, hoppers, and chutes are among the primary causes of unplanned downtime. The global silo cleaning service market is projected to reach 8.91 billion yuan by 2031, with a CAGR of 4.6%-. To address this persistent challenge, physical blockage clearing technologies represented by CO₂ cannons are becoming mainstream solutions in cement, power, grain, and chemical industries.
I. Technical Principle: The Phase-Change Power of Liquid CO₂
The CO₂ cannon (also known as the Cardox system) consists of a high-strength reusable steel tube filled with liquid carbon dioxide, equipped with a chemical heater and a rupture disc-21. When energized by a small electrical charge, the chemical heater instantly converts liquid CO₂ to gas, expanding to 600 times its original volume within milliseconds-21. Pressure inside the tube rises rapidly until it causes the rupture disc to burst, releasing a high-pressure CO₂ stream through a special discharge nozzle, creating a powerful heaving force at pressures up to 40,000 psi (3,000 bar)-21.
This process completes in milliseconds, and CO₂ being an inert gas, does not generate secondary reactions with gases in the vessel-21. Unlike traditional explosives, the CO₂ cannon produces no open flame or toxic gases and is classified as non-explosive, requiring no dedicated magazine for storage-.
II. Safety Protocols: Why "Non-Explosive" Does Not Mean "Risk-Free"
Although classified as non-explosive, the tremendous energy released means strict operational protocols must be followed. Incident records show that an improperly secured tube was launched approximately 50 meters and impacted an office building window, fortunately without injury-58.
Key safety points include:
First, proper tube securing. The tube must be tightly secured in the gripcase with the correct insertion depth. Shallow insertion increases backpressure, risking refractory damage and increasing the chance of tube launch-58.
Second, use of port safety devices. In high-temperature applications such as cement plants, hot material at 900°C+ may flow out immediately when the port cap is removed. Industry best practice is to fit a cover with a closable spade over the Cardox port, allowing operators to slide it across from a safe position without needing to replace the cap manually-34.
Third, usage logging and lifecycle management. Each tube should have a unique reference number with usage recorded, and should be completely removed from service after the manufacturer-recommended number of uses (typically 1,000)-77.
III. Efficiency Comparison with Air Cannons
A study on surface coal bunkers demonstrated that for arching blockage, air cannon usage was 3.0 times higher than CO₂ blasting, with 5.83 tons less coal drop per operation-. This indicates that CO₂ cannons achieve more thorough destruction of material arch structures, reducing repeated operations.
IV. Application Coverage
CO₂ cannon systems are widely used in the cement industry (preheater towers, cyclones, rotary kilns, coolers), power generation (boilers, economisers, silos), bulk material handling (grain, flour, soya, salt, sugar, cement, gypsum, coal, fertilizer, ores), and mining and quarrying-35.
