Modeling of Pulverized Coal Combustion in Cement Rotary Kiln
In this paper, based on analysis of the chemical and physical processes of clinker formation, a heat flux function was introduced to take account of the thermal effect of clinker formation. Combining the models of gas-solid flow, heat and mass transfer, and pulverized coal combustion, a set of mathematical models for a full-scale cement rotary kiln were established. In terms of commercial CFD code (FLUENT), the distributions of gas velocity, gas temperature, and gas components in a cement rotary kiln were obtained by numerical simulation of a 3000 t/d rotary kiln with a four-channel burner. The predicted results indicated that the improved model accounts for the thermal enthalpy of the clinker formation process and can give more insight (such as fluid flow, temperature, etc,) from within the cement rotary kiln, which is a benefit to better understanding of combustion behavior and an improvement of burner and rotary kiln technology.
Modeling of rotary kiln for sponge iron processing using cfd package (ANSYS 13.0)
CFD analysis of heat transfer in freeboard of rotary kiln was done with licence version of ANSYS 13.0, authorized by NIT Rourkela. ANSYS 13.0 is an engineering simulation software (Computer-Aided Engineering. Kiln of a typical Sponge Iron producing plant having capacity 500 Tons Per Day was modelled and simulated with CFD package (ANSYS 13.0). This kiln is of length 80m. and inner diameter 4.34m. Kiln was assigned with 9 air tubes to get a maximum turbulence for better temperature profile.A horizontal cross-section of kiln was modelled in a 2D geometry.These air tubes are separated from Inlet end to outlet end at distances of 8.1, 8.1,5.7, 6.7, 6.7, 6.7, 6.7 & 4.6 respectively. Air flow rate in these tubes 10000 cubic meter/hour. Air flow of 15000 cubic meter/hour mint for central blower spliced into two streams. A larger stream for Axial flow and smaller for radial flow. Axial flow is responsible pushing flame in forward direction. Radial flow pushes the flame in along Y-axis to rise the flame coverage diameter.Flame profile of kiln was modeled two values of with Axial to Radial volume ratios. Simulated proportions were 9:1 and 8:2.The simulated result of two proportions were compared at various time.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.