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FEATURE each directed by the plant's control room. The discharge sequence moves upward in a spiral, with cannons firing 10 seconds apart. The entire 80-90 second cycle typically repeats approximately every 20 minutes, but operators have varied the time from 5-45 minutes, depending on specific operating conditions. Since the installation of the new air cannon network, no unscheduled shutdowns have been caused by material buildup in that section of the cyclone. With the problem solved, engineers have turned their attention to some additional buildups higher in the deep tube, an area not covered by the air cannon network. During its next shutdown, the plant will install an additional set of four 70L Hurricane Air Cannons, locating them above the cyclone deep tube. COST REDUCTION The audit also revealed an opportunity to reduce the operating cost of the facility's 22 existing Tornado Air Cannons at the inlet chamber and riser duct of the Kiln #2 preheater tower by upgrading each one with a Martin Piston Return Reservoir, a canister that closes the valve after approximately 50 percent of the volume has been discharged. The reservoir is a pneumatic device that collects the exhaust air from the valve and redirects that pressure to close the piston when the valve and tank pressure equalize. When equipped with a piston return reservoir, the air cannon produces an initial blast force of the same strength, but the duration of the discharge is reduced. Instead, the air retained inside the cannon's tank minimizes the overall air consumption without reducing initial output force. Since the main air tank is never completely evacuated, the volume of air required to refill after each discharge is reduced. With the air cannon's peak force unaffected, the same amount of work can be accomplished with half the amount of compressed air. Twenty-two existing Tornado Air Cannons were upgraded with a Martin Piston Return Reservoir to reduce operating costs. Installed in a series and precisely sequenced for maximum effect, the air cannon network can be timed to suit specific process conditions or materials. Before the installation of the return reservoirs, the air consumption of the 22 Tornado Air Cannons at Büyükçekmece was estimated at 2 cu. m/minute, or an annual total air consumption of approximately 525,600 cu. m. If the cost of service air is estimated at two cents per cubic meter, the total air cost would be $10,512 per year. After installation of the reservoirs, the annual air consumption has been reduced to 262,800 cu. m, while retaining the same air cannon performance. If the minimum lifetime of an air cannon is estimated at 10 years (not an unreasonable prospect), the cost savings over that period would be $52,560. Information courtesy of Martin Engineering, www.martin-eng.com www.cementamericas.com • Fall 2013 • CEMENT AMERICAS The air cannon's fast-acting valve and pressure vessel (tank) release a blast of compressed air directed through a shaped nozzle. 7