Simulation of an Industrial Tangentially Fired Boiler Firing Metallurgical Gases

Abstract

In industrial environments, boiler units are widely used to supply heat and electrical power. At an integrated steel mill, industrial boilers combust a variable mixture of metallurgical gases combined with additional fuels to generate high-pressure superheated steam. Most tangentially fired boilers have experienced water wall tube failures in the combustion zone, which are thought to be caused by some deficiency in the combustion process. The challenge faced in this present process is that there are very limited means to observe the boiler operation. In this study, a three-dimensional computational fluid dynamics (CFD) modeling and simulation of an industrial tangentially fired boiler firing metallurgical gases was conducted. Eddy dissipation combustion model was applied on this multiple fuel combustion process. Simulation results obtained from the developed CFD model were validated by industrial experiments. A quick comparison of the flame shape from the simulation to the actual flame in the boiler showed a good agreement. The flow field and temperature distribution inside the tangentially fired boiler were analyzed under the operation conditions, and a wall water tube overheating problem was observed and directly related to the flow characteristics.

An Integrated Model to Study the Effects of Operational Parameters on the Performance and Pollutant Emissions in a Utility Boiler

“…For example, CFD and metallurgical studies was combined to find the reason of tube rupture of platen radiant superheater in a utility boiler [11]. In another study [12], a tangentially fired boiler firing metallurgical gases was evaluated by means of CFD. Results showed that the non-uniform flow pattern which is a characteristic of tangentially fired boilers was the major reason for non-uniform wall temperature distribution and formation of hot spots.…”

“…For combustion, the eddy dissipation model was employed. This model is appropriate for fast burning and non-premixed situations and has been utilized in some articles for modeling combustion inside furnaces [11,12,36]. Radiation heat transfer was considered using P-1 model.…”

“…In comparison to discrete ordinates (DO) radiation model, the P-1 was resulted nearly identical wall fluxes in modeling an oil fired boiler [7]. In addition, P-1 radiation model was used successfully in many research articles dealing with CFD simulation of industrial boilers [3,5,7,12,14,33]. Thermal and prompt NOx were also included in the CFD simulation via an equilibrium model in the FLUENT software.…”

Over-attemperation and Short-term Overheating in Pendant-type Superheaters

“…A heat transfer study found that the temperature distributions over boiler tube walls become highly non-linear due to overfiring in the furnace, which could also increase the tube hoop stresses and contribute to failures [19]. A more recent computational fluid dynamics study confirms this possibility by indicating that the flame shape over the water wall tubes of an industrial boiler leads to overheating of these tubes [20]. Another numerical study on the downcomer tubes of a 600 MW thermal plant boiler evaluated the heat flux and wall temperature distribution over the tubes to identify overheating conditions [21].…”

Simulation and Experimental Analysis of Tangential Over Fire Air System of an Industrial Boiler

“…The flow field and temperature distribution inside the tangentially fired boiler were analyzed under the operation conditions [10]. A computational fluid dynamics (CFD) modeling study was performed for the combustion of the brown coal in a large-scale tangentially-fired furnace (550 MW) under different operating conditions and performance has been studied [11].…”