| OCR Text |
Show in previous heating cycle. The modulation, (or pulsation), of the burner heating and cracking gas cycle has to be controlled by set of timer controlled solenoid valves and bypass piping system. The cycle timing will be in the range of 6-10 seconds and total mass flows, during each cycle, are required to be such that a steady flow is obtained from the system at all times (with minimum fluctuations). The advantages of this modulative concept is due to the fact that it minimizes direct m~x~ng of oxy/fuel burner combustion products with the cracking gas, and thus minimizing reforming. The proposed design is expected to provide almost steady gas flow to the furnace, since the cycle time durations are very small (-6 to 10 seconds) and the amount of cracking gas is only 25% of the total fuel to the furnace. 2. Field tests: Field tests using the CTI "cracker" are planned on a typical end port furnace during early 1991. Figure 4 shows a typical reversal sequence gas firing for the standard furnace as well as one equipped with a cracker. This is a simplified version. Interlocks, limit switches, delays are not shown. It further assumes the cracker oxy/gas burner operates continuously. These combustion products enter the furnace through burners at about 8X of normal gas flow rate. Hence, heat is supplied to the furnace during the reversal (desirable), and no unburned products of combustion are present, and hence stable cracker temperature is maintained. The necessary R&D work for final development of this system is underway, and it is expected that a field installation will be made sometime at the end of this year for full scale evaluation trials of NOx reduction. Note: A United States Patent, "Oxygen Enriched Combustion" has been assigned to Combustion Tec, Inc. on the above CRACKER method of combustion. Foreign patents are pending. M. J. Khinkis is the inventor. U.S. Patent No. 4,761,132. -6- |
