Numerical Investigation and Improvement of Coke Oven Gas-Fired W-Shaped Radiant Tubes for NO_x Reduction

Abstract

In this study, to solve the problem of excessive NO x emission of W-shaped radiant tube (WRT) burning coke oven gas (COG), the numerical calculation method was adopted to investigate the effects of N 2 and CO 2 as diluent gases in the air, CH 4 as a diluent gas in the fuel, and blast furnace gas as a diluent gas for COG on NO x emissions of WRT. Besides, a novel WRT (N-WRT) with a flue gas circulation structure was developed to reduce NO x emissions. Moreover, the effects of the nozzle diameter and nozzle location on the gas flow, temperature distribution, and NO x emission were analyzed and discussed in detail. The results shows that CO 2 as a diluent can inhibit the production of NO x more than N 2 . The high NO x emission of the COG-fired WRT is caused by a higher proportion of H 2 and CO in COG. The NO x production of the WRT is about 6 times that of the N-WRT, indicating the effect of circulating flue gas on reducing NO x emission is quite remarkable.

Review and Perspectives of Novel Flue-Gas Internal Recirculation Combustion Technology for Low Nitrogen Emission: Fundamentals, Performance, Method, and Applications for Conventional Fossil Fuels and Sustainable e-Fuels

“…Schematic of the (a) WRT and (b) novel WRT. This image was reproduced with permission from ref . Copyright 2020 American Chemical Society.…”

“…Wang et al 59 designed the FIR circulation channel applied to the coke oven gas-fired w-shaped radiant tube (WRT), as shown in Figure 12. The W-type radiation tube structure with flue-gas circulation is designed by adding a return flue-gas pipe between the fourth straight section and the first straight section of the Wtype radiation tube, which leads some of the smoke to the center of the burning flame.…”

The Structural Design of and Experimental Research on a Coke Oven Gas Burner

“…Coke oven gas is the main by-product of the coke-making industry, with the production of 1 ton of coke yielding 300-360 m 3 of coke oven gas [10][11][12]. In 2015, China's coke production amounted to approximately 378 million tons, and this figure had surged to around 473 million tons by 2022 [13].…”

Numerical simulation on heating performance and emission characteristics of a new multi-stage dispersed burner for gas-fired radiant tubes

“…The numerical simulation results agreed with the experimental data in predicting the RT temperature. Wang et al [18] numerically simulated the heating performance of a W-shaped RT with a flue gas circulation tube. They compared the effects of different gas compositions of coke oven gas on combustion and emission characteristics.…”