Call for advanced operation methods?

Introduction to methods for improving the efficiency of heating furnaces. To enhance the thermal efficiency of heating furnaces, it is necessary to consider various aspects such as the medium flowing through the furnace tubes, the flame combustion process, and waste heat recovery, while also taking other factors into account. Therefore, the following methods have been developed to optimize the operation of heating furnaces: 1. Operation of feed materials into the heating furnace: It is essential to strictly control the flow rates of the four feed streams entering the furnace. Pay attention to the distribution of these flows to avoid any imbalances, ensuring stability and preventing large fluctuations in flow rates. Regularly check whether the opening degrees of the control valves for these four streams remain stable; if not, it may be necessary to adjust the flow meters or control valves. It is also possible to determine whether there are imbalances by observing changes in the temperature of the flowing medium, thereby allowing for appropriate adjustments to the feed amounts for each stream. . Make sure that the temperatures of the four feed streams do not fluctuate significantly; influenced by the preheating in the coke tower, maintain the bottom temperature of the distillation tower within the range of 325–335°C. II. Operation of steam injection at three points in the furnace tube: Control the steam injection volume at an appropriate level of 3.5 MPa; the injection rate at the first point should be around 150–160 Kg/h, at the second point around 280–300 Kg/h, and at the third point around 130 Kg/h. If the processing capacity decreases, increase the steam injection rates at the first and second points accordingly. A large amount of steam injection increases the flow rate of the medium inside the furnace tubes, which helps to prevent coking in these tubes ； However, a large amount of steam injection leads to high gas consumption, which reduces the thermal efficiency of the heater; therefore, it is necessary to adjust the steam injection volume appropriately. Based on whether the pressures at the radiation points of the four circuits are equal, the steam injection rates at the first and second points are adjusted slightly to maintain equal pressures across all four circuits, thereby ensuring that the flow velocities of the media in the furnace tubes are similar. Monitor the pressures at the inlet and outlet of the furnace tube (main pipe, steam injection pipe), and pay attention to any changes in pressure ； By comprehensively analyzing the influencing factors, the coking condition of the furnace tubes is assessed, so that timely measures can be taken to ensure long-term normal operation and high thermal efficiency of the furnace. III. Flame adjustment procedures: By properly adjusting the burners, air valves, and flue dampers, it is ensured that each burner burns efficiently, resulting in multiple burners with short flames and uniform flame heights, thereby striving to reduce fuel consumption. Adjust the flue dampers properly to ensure an appropriate draft in the furnace and to control the negative pressure within it. The furnace negative pressure is controlled at -30 to -40 Pa. A higher negative pressure results in greater suction force, but it also accelerates flue gas flow and leads to greater heat loss; therefore, the negative pressure needs to be adjusted appropriately. The oxygen content in the furnace chamber should be maintained at 3–4%. A higher oxygen level leads to more intense combustion; however, if the oxygen level is too high, more heat is absorbed by the air, resulting in greater heat losses. Additionally, it accelerates the oxidation of the furnace tubes, so the oxygen level also needs to be controlled appropriately. Control the gas pressure; keep the pressure in the gas tank at around 0.37 MPa, with the pressure in each branch being above 0.03 MPa. Ensure the suction force of the gas. Flame adjustment method: General adjustment approach – Adjust the air supply to each burner properly. Therefore, for the first 6 burners in each circuit, the first stage of the gas control valve should be fully open, the second stage valve should be opened to 2.5 turns, and the primary air damper should be set at around 80% ； For the gas manual valves of the last 6 nozzles, the first stage should be fully open, the second stage valve should be opened to 2.5 turns, and the primary air damper should be set at around 90%. Because the gas and air pipeline layout follows a reverse flow, it is possible to properly adjust the amounts of gas and air. Then, the flame is fine-tuned according to the characteristics of each burner. Method for fine-tuning each burner: If the flame is yellowish-red, diffuse, and large, and the furnace chamber appears dark. The gas volume should be reduced, the air volume increased, or the flue dampers adjusted appropriately; however, regulation of the gas and air valves should be the primary method. Reason: Excessive gas volume and insufficient air volume. If the flame is white, too short, and unstable. The gas flow rate should be increased, the air flow rate reduced, and the flue dampers should be adjusted slightly; regulation is primarily done through the gas or air valves. Reason: Low gas volume and high air volume. If the flame is skewed. Adjust the nozzle’s verticality or clean the nozzle. Reason: Gas and air are biased to one side, the burner is not installed properly, or some burners are blocked. If the flame is long and soft, red in color, or if it emits sparks, shrinks, the furnace interior is not visible, black smoke is produced, and the temperature inside the furnace rises. Strengthen the liquid removal and condensate discharge from the gas tank, and adjust the furnace temperature properly. Reason: Gas contains oil or water. At the same time, attention must be paid to the test analysis data to keep the excess air coefficient at or below 1.2, thereby ensuring the thermal efficiency of the heating furnace. The furnace temperature should be controlled at no more than 800°C, to ensure complete combustion in each burner, a bright furnace interior, and uniform temperature throughout. Pay close attention to whether the temperatures of the two furnaces, as well as the oxygen level and negative pressure, are similar; otherwise, it indicates that the furnace is not burning properly, and adjustments should be made by taking all relevant factors into account. It is also possible to determine whether the flame in the furnace is burning evenly by checking the eight temperature points on the furnace top. Check whether the flame is licking the furnace tubes, which may cause local overheating, bending, oxidation, and peeling of the tubes. This leads to coking of the furnace tubes, affecting the furnace’s thermal efficiency. The flame of the eternal light should be kept at a low intensity, so the gas pressure regulating the eternal light is maintained at around 0.1 MPa. During inspections, carefully check the flame combustion; if it goes out, light it up promptly. If the flame of the everlasting lamp is too long, it should be adjusted to be smaller; a weak flame is sufficient. All sight windows for monitoring the fire on site must be tightly closed, especially those on the fire pit, which should be checked regularly to ensure they are properly closed. Heat tracing is installed for the gas pipelines and gas liquid separation tanks to maintain the gas temperature above 120°C. Enhance gas drainage, and remove coking in the burners promptly once it is detected. IV. Operation of the water heat medium in the waste heat recovery section: The temperature of TI6834 is controlled based on the exhaust gas temperature; it is required that this temperature not exceed 140°C. If the temperature is too high, the setting value of TI6834 should be reduced. If the control valve TV6834 is already fully closed, then slightly open the manual valve at the water outlet of the air heat exchanger, or increase the opening degree of the outlet valves for P401/P402. Regularly vent the deoxygenated water to prevent gas presence within the tube bundle from affecting heat transfer efficiency. Adjust the circulation rate of deoxygenated water to ensure that the air outlet temperature of the air heat exchanger is above 150°C. Regularly check the operating conditions of the circulation water pumps, blowers, and exhaust fans to increase the temperature of the hot air and reduce the temperature of the flue gas emissions. V. Other aspects: Since the medium flowing through the furnace tubes is residue oil, during inspections it is necessary to check that the heating systems for various instruments are functioning properly, and to ensure that the connection points of these instruments are not blocked by the solidification of residue oil ； Check whether the insulation of the residue oil pipeline, the furnace body, and the waste heat recovery section is in good condition; if not, repair it promptly. Periodically test-operate the flue dampers to check whether the main flue dampers are leaking smoke, which could affect thermal efficiency. Through the comprehensive optimization achieved through the above measures, the heating furnace has operated well. Over the past six months of operation, no coking of the furnace tubes has occurred, and the thermal efficiency of the heating furnace has been gradually improving.

Six strict requirements for operators: 1. Strictly implement the shift handover system. II. Conduct thorough routine inspections. III. Strictly control process parameters. IV. Strictly implement the standard operating procedures for the position. V. Strictly abide by labor discipline. VI. Strictly implement safety regulations.