Regarding oxygen interruption handling in two-stage furnaces

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This post was last edited by Small and on 2017-8-27 at 13:26. Regarding the handling of oxygen interruption in a two-stage furnace, an oxygen interruption in such a furnace leads to a significant reduction in reaction heat, as well as a decrease in conversion rate; this results in: (1) a decline in the amount of high-pressure steam produced by the high-pressure drum. (2) An increase in the CH4 content in the syngas leads to a deterioration in its composition, resulting in poor reaction performance, a decrease in the yield of crude methanol, an increase in off-gases, and a reduction in the amount of steam produced by the syngas drum. Treatment: 1. External steam supply (4.0 MPa) at 45 T/h. a. The system load drops to 55–60%. b. Five burners with full ignition; TI-1247 at 560℃, up to 650℃. c. The temperature at the outlet of section one of the furnace, TI-1274, was increased to 760°C. d. The amount of off-gas released from the synthesis system was increased (off-gas volume ≥ 17,000 Nm3/h). The temperature of the catalyst bed in the synthesis tower was carefully controlled, and the start-up heater C0304 was used to maintain the inlet temperature of the synthesis tower at 220–235°C. E. It is strictly prohibited to reduce steam at 4.0 MPa and 2.6 MPa to a low-pressure steam system at 0.35 MPa ； If the 0.35 MPa low-pressure steam system is insufficient, the distillation system should reduce its load or operate in full cycle to ensure that the pressure in the low-pressure steam system remains ≤ 0.35 MPa. F. Comprehensive inspection. 2. The external steam supply (4.0 MPa) can only provide 30 T/h. In addition to following the steps in ﹙1﹚, it should also be specified that the scheduler requires dimethyl ether to be returned to a pressure of 1.2 MPa, with operation from J0204A to J0204B. 3. Steam cannot meet the 20 T/h supply requirement. a. In addition to being processed according to the methods in ﹙1﹚ and ﹙2﹚, b. it is necessary to notify the dispatching team to have the air separation unit immediately switch off at 4.0 MPa. 4. External steam cannot meet the 10T/h supply requirement. a. In addition to being treated according to the methods in ﹙1﹚, ﹙2﹚, and ﹙3﹚, b. the entire synthesis system must be cycled, with the steam from the synthesis drum being vented through V-20505. Pay attention to the temperature of the medium-pressure steam preheating coil, and replenish low-pressure steam in a timely manner to ensure that the coil does not overheat. c. Change one section of the furnace to steam cooling: TI-1274↘550℃, V-20603 for air protection. e. Comprehensive adjustment: steam supply increased to 20 T/h, production was restored immediately. Steam balance of the second-stage furnace on July 3, 2008 (oxygenation not enabled; air separation unit not in operation): Load, Steam (T/h); Steam production volume of F0201, Steam production volume of F0301: 5815.89, 3.920. Steam balance of the second-stage furnace on July 3, 2008 (air separation compressor and dimethyl ether in operation): Load, Steam (T/h); Steam production volume of F0201, Steam production volume of F0301: 5843, 93.20. The above data were collected after the system reached stability under normal operating conditions; in emergency situations, the requirements regarding external steam supply were relaxed accordingly. July 7, 2008