OCR Text |
Show S4/46 (Btu basis) . I t should be not ed that the lower concentration of solids in t he wastewater resulted i n significantly higher natural gas consumption. Raising the concent ra t ion from 44.2% to 49.2% resulted in about 26% lower gas consumption. The flue gas analysis, taken at the i nc i nerator exit, showed that the excess oxygen concentration was maintained at 3.8% during the operation. Carbon monoxi de was usually below 100 ppm. Therefore , the combustion was comp l eted within the incinerator chamber. Based on previous tests, to avoid incomplete combustion, the incinerator base temperature (see Figure 7) was maintained at a higher level than was observed i n the past. The temperature of the flue gases exiting the Horison tube was monitored continuously. Water spraying into the exit of the Morison tube was used for final control of the flue gas temperature entering the convective pass. For the first four days of operation the temperature was kept slightly above the 1000°F ± SO°F (thermocouple) target temperature. The water spraying was used only at night and not used during the day. Dur i ng the day the temperature was allowed to rise to about 1100°F while the ~10rison tube exit was closely monitored (visually) for quality of the ash entering the convective tubes of the boiler. For the remaining 17 days the water spraying was used continuously to maintain the temperature within the target levels. MAJOR CONCLUSIONS 1. The cycl onic incineration demonstration system has proved reliable, highly efficient, low emission incineration of wastewater having a heating value of about 3000 Btu/lb. 2. Performance tests and the final SOO-hour continuous system operation demonstrated stable high-efficiency inc ineration of 40 gal/h of wastewater containing up to SO% solid concentration. The heat contribution ratio of wastewater to auxiliary fuel averaged SS/4S. 3. Major operating parameters during the final operation included 2.1S X 106 Btu/h total firing rate, 20S0°F combustion temperature, air preheat of 32SoF, and specific heat release of 0.12 X 106 Btu/h-ft3 with 20% excess air. Carbon monoxide concentration in the flue gases was usually below 100 ppm. 4. Al though the flue gas temperature entering the boiler convective pass, for s eve r al opera t i onal reasons, exceeded the r ecommended target of 1000°F ± SO°F , the original slagging problem in the heat recovery boiler was 20 |