Analysis of nozzle designs on zoned and staged double P-type gas-fired radiant tube

In this study, the nozzle characteristics of a zoned and staged double P-type gas-fired radiant tube were improved to optimize combustion efficiency. Experimental and numerical analyses were conducted on the optimized radiant tube. The deviation between the experimental and simulated monitoring parameters was less than 3.6%, thereby proving the reliability of the model. The gas and wall temperatures were compared by changing the positions of the main and branch tube nozzles, and structural parameters. The results showed that as the nozzle moved outward, the maximum surface temperature decreased from 1328 K to 1320 K, and the minimum wall temperature increased from 1253 K to 1258 K. When the branch tube nozzle was located at the intersection of the tee and branch tubes, the impact of high-temperature gas on the tube wall was reduced, and the uniformity of the branch radial temperature was improved. When the nozzle was fully premixed, the temperature difference was at its minimum. When the tube nozzle was asymmetric, the wall temperature difference was at its minimum, and combustion thermal efficiency was at its maximum.