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Show The physical and mathematical modelling predicted that the kiln could be converted to natural gas firing and maintain the product quality without an increase in the net heat consumption. The dual fuel burner, shown in figure 8, was designed, constructed and installed. Following the installation of the new burner, the kiln produced top quality product within 5 hours of feed on, and was at full production within 12 hours. After four weeks of highly satisfactory operation the guarantee trials were undertaken. The results are shown in table 4. It can be seen that the temperature distribution throughout the kiln system is similar to that prior to conversion. The kiln heat balance is summarised in table 5. The net heat input of 7579 kcal/s is comparable to that in Table 2. The range of experimental error from these kiln tests was + 3%. Thus the net heat consumption, following conversion to natural gas firing, is therefore similar to the heat consumption for liquid fuel firing, within the limits of experimental error. CONCLUSIONS When physical modelling is used in conjunction with mathematical modelling as a process design tool, it is possible to eliminate guess work from burner design and, therefore, to match the flame characteristic produced by the burner to those required by the process. The commissioning period is also reduced compared with the conventional approach, since the optimum position for the burner is known prior to installation, and time consuming trial and error optimisation is eliminated. Therefore, the plant achieves full production within days rather than weeks and months. The practical benefits of this approach are better product quality and reduced costs for the client. Immediate cost benefits arise from a greatly reduced commissioning period. However, the real savings are continuos and on-going because the fuel consumption of the plant is minimised through efficient combustion and optimum heat transfer. -24- |