Blowpipe Design and Optimization Tests
Goyen Controls Co. Pty Ltd., Sydney, Australia, conducted blowpipe design optimization laboratory tests. A 27-outlet blowpipe was fabricated per Buell’s specification with additional pressure tap locations. Four-inch blowpipes and valves were selected to meet the pulse cleaning airflow requirements for 27 bags per blowpipe.
The goals of the blowpipe optimization tests were to determine the staggered pipe orifice sizes along the pipe that would provide equal pulse air volume to each bag (within ±10%); determine the optimum blowpipe air straightening nozzle diameter, length, and height above the tube sheet; and determine the air consumption required per blowpipe.
A clean filter bag is usually not very indicative of the cleaning performance with dust-laden filter bags when testing a blowpipe system. Rather than using clean filter bags, Goyan accurately simulated a dust-laden filter bag using a jet pump duct. A significant advantage of the jet pump duct is that it is possible to simulate a range of dust loadings by altering the position of the blast gate (altering the resistance to the pulse), thereby mimicking the varying dust loads on the filter bags. The jet pump duct is 3 meters long with a diameter of 150 mm. A blast gate is located 1 meter from the entry of the duct. A flow meter arrangement using an orifice plate is located at the exit of the duct. Pressure taps are located halfway between the duct entry and the blast gate. Test runs along the blowpipe outlets were conducted at 45 and 60 psi pulse pressure. A good distribution of cleaning flow along the blowpipe was achieved with cleaning flows within ±10% of the average, as designed.
Pulse Jet Conversion Installation
The outboard two ESP chambers were converted during the spring of 2007, one at a time, starting in early March. The first chamber was removed from service with a short outage for blanking plates to be installed in the chamber’s inlet and outlet rectangular ducts. The first chamber was converted during a six-week period, with the unit at reduced load, and started up in April 2007. Conversion of the second outboard chamber followed during another six-week period. Start-up of the second converted chamber occurred in June 2007. During the summer and early fall, the unit operated with the two converted pulse jet chambers and the two chambers with the AHPC design. The remaining two ESP chambers were converted to pulse jet operation during a scheduled late fall outage. The completed conversion was fully operational in December 2007.
All performance guarantees were met, including stack opacity and pressure drop. The stack opacity was close to zero, prompting Big Stone Plant to forego the outlet emission tests. In 2008, Big Stone Plant Unit 1 set a new annual generation record. Operating restrictions caused by opacity problems or ID fan pressure drop limits are just a memory.
——Thomas W. Lugar (twl@fkinc.com) is vice president of the Buell Division of Fisher Klosterman, A CECO Environmental Company. Jeff Endrizzi is plant manager, Stu Schreurs is principal engineer, and DJ Haggerty is plant engineer at Otter Tail Power Company’s Big Stone Plant.
Email
Comments
Print
Reuse
