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Show flame noise became an environmental problem as well. A test of a prototype 439 kW (1.5 million Btu/hr) pyrocore burner was conducted at the refinery to verify the burner's uniform heat flux. In a side-by-side comparison with a conventional flame burner, data for the temperature profile along the lengthof the firing tube were generated, as shown in Figure 5. Tmax _4'" Tmin Pyrocore burner ,"" ;5 ,I f I ,I /" Conventional p' burner Distance along tube, It Fig. 5 - Immersion tube burner comparison The ability of the .152 m (6-inch) diameter by 3.66 m (12-foot) long burner to evenly distribute the heat over the fired area of the tube was clearly shown, allowing the asphalt to be held at a higher temperature and to be shipped over greater distances, leading to the retrofit of burners in four storage tanks. These significant benefits were enhanced by the absence of flame noise for the Pyrocore burner, which solved a noise problem to surrounding neighborhoods. Because of the success of the Strathcona installation, an additional 732 kW (2.5 million) Btu/hr burner was installed in an asphalt line heater in the Imperial Oil Dartmouth Refinery in Nova Scotia. In this application, the more uniform heat transfer allowed a greater fluid temperature rise across the heater to be achieved. The results were faster asphalt loading rates and greater shipping distances. Subsequent annual inspections have shown no evidence of fluid coking on tube surfaces as was experienced with prior conventional burners. Additional burners for these sites are currently in the planning stages. 270 GLYCOL REBOILERS FOR NATURAL GAS DEHYDRATION - Another application where uniform heat transfer to a degradable fluid is important is in glycol reboilers. The common technique for removal of saturated water from natural gas as it comes from the well is to pass the gas through a glycol solution in a vertical packed column where the entrained water is absorbed. The water is then removed from the glycol by evaporation in a boiler such that the glycol can be recycled in the process. Typical glycol reboilers contain one or more horizontally fired tubes immersed in glycol contained in an outer boiler shell. Glycol is an expensive fluid and subject to degradation at temperatures above 177 C (350 0 F). The Pacific Gas and Electric Company in San Francisco, California installed a 1 million Btu/hr input Pyrocore burner in one reboiler at its Sherman Island Dehydration Station. Although the existing reboiler was not of optimal design for utilizing the radiant transfer characteristics of the burner, a nominal system efficiency benefit of two percentage points was gained due to the enhanced radiant transfer in the flame zone. Although local heat transfer rates are now above the ~tandard specified rases of 31.5 kW/m (10,000 Btu/hrft ) for those systems, no degradation of the glycol has been detected. HEAT TRANSFER FLUID HEATERS - A similar tube firing application where uniform heat transfer is of importance is with heat transfer fluid heaters and boilers. Heat transfer fluids and oils are used in a variety of industrial applications (commonly in petrochemical processes) where high temperatures are required. They are used in both the liquid and vapor phases. Fluid cost is very high, and cracking can occur at temperatures above 344 C (650 0 F). Recognizing the potential of the Pyrocore burner, The DeMenno/Kerdoon Refinery in Compton, California utilized the burner in a new vaporizer unit brought on line to increase their capacity of refined oil products. The refinery elected to design a new vaporizing boiler unit around the burner, taking advantage of the compact nature of the burner's heat transfer to achieve a compact boiler. The unit was completed at a cost far below the package system costs of other boiler options and was brought |