Yes, Nozzles are Critical: Hot Topic Hour November 8, 2007
Hundreds of years of FGD experience were efficiently utilized in a Hot Topic Hour yesterday on nozzles for FGD, NOx, SO3 and Mercury control.
Tony Licata of Babcock Power was the lead speaker. He addressed the nozzle selection by Babcock in the various applications. The utilization of bi-directional nozzles in the lower three layers of the wet limestone spray tower improves efficiency without adding height or additional spray banks. The first use was at Tiefstack in 1992 and then in the U.S. at Vectren Culley station in 1994. Tony said that they are now routinely asked to guarantee 98.5 and even 99 percent SO2 removal. With the bi-directional nozzles they are able to do this economically. Tony maintains that the spray tower provides lower energy consumption than alternatives. One of the utilities participating in the discussion stated that they have had trouble with nozzle pluggage and asked how that could be solved. Tony said that the bi-directional nozzles have orifices so large that you could pass a golf ball through them. Therefore pluggage should not be a problem.
In the Babcock design for NOx control with aqueous ammonia dual fluid nozzles are integrated with the Delta wing mixing element.
Babcock’s Turbosorp circulating fluid bed dry FGD unit uses a mechanical atomizing nozzle at 500 psi to humidify the gas ahead of the fluid bed.
The Lechler presentation was provided by a foursome: Mughis Naqvi, John Coulston, Martin Reinsalu and Robert Van Durme. Both hydraulic and air atomizing nozzles are available. Lechler has designed customized twin-fluid nozzles for high solids applications, such as in Spray Drier Absorber Lances. The nozzle has been proven to work in flyash/lime slurry applications up to 35 percent by weight. For wet FGD a double nozzle design called “Twinsorb” was reported to have increased SO2 removal rates and reduced maintenance costs.
Bill Ellison of Ellison Consultants and Bill Walsh of VGA Nozzle Company said that for SNCR in-furnace, air atomizing nozzle lances mounted on the wall spray into appropriate combustion zones. Control of droplet size and flow rate is made by varying air and liquid pressures. VGA two-fluid (air) atomizing nozzles provide finer atomization with economical air consumption, via moderated air pressure, for a wide range of electric utility applications including reducing NOx, SO2, SO3 and mercury emissions. VGA nozzles, serving as burners, provide means of fulfilling growing applications for combustion of mixtures of fossil and biomass fuels.
Silicon carbide is the material of choice for limestone wet FGD nozzles. The nozzle companies subcontract the manufacture to silicon carbide parts manufacturers. When Coors dropped out of the picture there was a crunch to provide capacity in the U.S. But now the suppliers say that subcontractors have expanded to meet the needs.
One Chinese supplier listed as a nozzle supplier in the FGD Decision Tree is also a silicon carbide parts supplier and claims to be shipping products around the world. McIlvaine posed the question as to how the very large demand in China was met last year. The answer was that it was done with a combination of local and foreign supply.
The individual power point presentations can be immediately viewed through the FGD Decision Tree as follows.
Overview of Nozzles presented by Tony Licata, Babcock Power at November 8, 2007 Hot Topic Hour
A variety of nozzle types are applicable to FGD absorber spray tower service, mist eliminator washing, and dry FGD. Lechler has provided an overview.
Spray nozzles - Slides presented by
Mughis Naqvi at Hot Topic Hour November 8, 2007.
http://www.mcilvainecompany.com/FGD_Decision_Tree/subscriber/Tree/DescriptionTextLinks/LECHLER
hottopic110807.pdf