【Q&A Question 164】2018.06.13

Yes: ① Where conditions permit, installing waste heat recovery or air preheating equipment to reduce the flue gas exit temperature and thereby minimize heat loss from the flue gases is one of the most effective methods. ②Raising the temperature of the combustion air is beneficial for combustion, as it can improve thermal efficiency. ③Ensure complete combustion of the fuel, which can be achieved by improving the burner and optimizing the operation. ④Try to minimize the excess air coefficient, which requires us to have good control over the “three valves” (throttle, valve, and damper). “Operation and adjustment of the “one plate” (flue baffle). Do not allow too much air to enter the furnace. Practice has shown that for every 0.1 decrease in excess air, the thermal efficiency can increase by about 1.3%. ⑤Strengthen management to prevent cracks and collapses in the furnace walls, and carry out regular leak repairs by sealing or blocking any areas where air leakage occurs, such as the burners, viewing ports, and elbow boxes. Try to minimize air leakage from these areas. ⑥The design ensures a rational structure and appropriate material selection, aiming to minimize the furnace wall temperature and reduce heat loss.

(1) Maintain complete combustion. (2) While ensuring complete combustion, reduce the excess air coefficient and adjust the three doors and one plate appropriately. (3) Operate the flue gas preheating and recovery facility properly. (4) Strengthen equipment management; ensure the furnace body is airtight to prevent cracks or collapses in the refractory layer of the furnace walls. Reduce air leakage from areas such as the lower elbow boxes, manholes, and observation windows, thereby minimizing heat loss. Insulation should be enhanced in the exposed areas to prevent excessive heat loss.

Methods to improve the thermal efficiency of a furnace include: 1. Raising the temperature of the combustion air; preheating the air using the waste heat from flue gases can save fuel gas and increase the furnace’s thermal efficiency； 2. Increase the temperature of the fuel gas by using the backpressure steam from the steam heat exchanger in the device to preheat it, with effects similar to those of preheating air ； 3. Apply a layer of thermal radiation coating to the insulation wall in the radiant section of the furnace ； 4. Eliminate air leakage from the furnace to prevent cold air from entering ； 5. Adjust the air valves, gas valves, and flue dampers to ensure as even a combustion as possible in the furnace, so that the furnace tubes are heated evenly ； 6. Install soot blowers in the furnace’s convection chamber to clean the tubes there ； 7. Replace the furnace tube in the convection chamber with finned tubes, etc.

①Lowering the flue gas temperature can be achieved by adding flue gas heat extraction equipment； ②Control the oxygen content in the heating furnace (2–5%) and the negative pressure (-35–50 kPa) ； ③Adjust the dampers and flame to ensure complete combustion ； ④The furnace wall is lined with insulating material to prevent heat loss.

The main measures to improve the thermal efficiency of heating furnaces are as follows: (1) Reducing heat losses ① Strengthen management and establish reasonable operating procedures. ② Control the “three doors and one panel” to lower the furnace’s excess air coefficient. ③ Use automatic control systems and computer-based operations. ④ Employ zirconia sensors to control the oxygen level in the radiation chamber. ⑤ Minimize heat loss through the furnace walls. (2) Increasing heat absorption in the convection chamber ① Use nail-head tubes or finned tubes in the convection chamber. ② Install soot blowers. ③ Increase the number of convection tubes or lengthen them appropriately. ④ Use baffle bricks on the inner wall of the convection chamber. ⑤ Add a convection chamber to pure radiation furnaces. (3) Installing waste heat recovery systems ① Use rotary air preheaters. ② Use cold feed for the convection chamber. ③ Install fixed air preheaters made of steel pipes, cast iron pipes, or glass pipes. ④ Use heat pipe air preheaters. ⑤ Use circulating heat carriers to preheat air. ⑥ Use waste heat boilers. (4) Other methods ① Install warm air generators to preheat the combustion air. ② Use forced air supply or high-energy, high-intensity burners. ③ Burn more plant exhaust gases to eliminate the need for flares.

①Where conditions permit, installing waste heat recovery or air preheating equipment to reduce the flue gas exit temperature and thereby minimize heat loss from the flue gases is one of the most effective methods. ②Raising the temperature of the combustion air is beneficial for combustion, as it can improve thermal efficiency. ③Ensure complete combustion of the fuel, which can be achieved by improving the burner and optimizing the operation. ④Try to minimize the excess air coefficient, which requires us to have good control over the “three valves” (throttle, valve, and damper). “Operation and adjustment of the “one plate” (flue baffle). Do not allow too much air to enter the furnace. Practice has shown that for every 0.1 decrease in excess air, the thermal efficiency can increase by about 1.3%. ⑤Strengthen management to prevent cracks and collapses in the furnace walls, and carry out regular leak repairs by sealing or blocking any areas where air leakage occurs, such as the burners, viewing ports, and elbow boxes. Try to minimize air leakage from these areas. ⑥The design ensures a rational structure and appropriate material selection, aiming to minimize the furnace wall temperature and reduce heat loss.

1) Maintain stable operation to ensure complete combustion; (2) Adjust the flue dampers and air valves properly to minimize the excess air coefficient; (3) Strengthen equipment management, keep the equipment in good condition, and regularly check and seal the burners to prevent large amounts of cold air from entering the furnace.

①Where conditions permit, installing waste heat recovery or air preheating equipment to reduce the flue gas exit temperature and thereby minimize heat loss from the flue gases is one of the most effective methods. ②Raising the temperature of the combustion air is beneficial for combustion, as it can improve thermal efficiency. ③Ensure complete combustion of the fuel, which can be achieved by improving the burner and optimizing the operation. ④Try to minimize the excess air coefficient, which requires us to have good control over the “three valves” (throttle, valve, and damper). “Operation and adjustment of the “one plate” (flue baffle). Do not allow too much air to enter the furnace. Practice has shown that for every 0.1 decrease in excess air, the thermal efficiency can increase by about 1.3%. ⑤Strengthen management to prevent cracks and collapses in the furnace walls, and carry out regular leak repairs by sealing or blocking any areas where air leakage occurs, such as the burners, viewing ports, and elbow boxes. Try to minimize air leakage from these areas. ⑥The design ensures a rational structure and appropriate material selection, aiming to minimize the furnace wall temperature and reduce heat loss.

Methods to improve the thermal efficiency of furnaces include: ① Where possible, installing waste heat recovery or air preheating equipment to lower the temperature of the flue gas exiting the furnace, thereby reducing heat losses from the flue gas; this is one of the most effective methods. ②Raising the temperature of the combustion air is beneficial for combustion, as it can improve thermal efficiency. ③Ensure complete combustion of the fuel, which can be achieved by improving the burner and optimizing the operation. ④Try to minimize the excess air coefficient, which requires us to have good control over the “three valves” (throttle, valve, and damper). “Operation and adjustment of the “one plate” (flue baffle). Do not allow too much air to enter the furnace. Practice has shown that for every 0.1 decrease in excess air, the thermal efficiency can increase by about 1.3%. ⑤Strengthen management to prevent cracks and collapses in the furnace walls, and carry out regular leak repairs by sealing or blocking any areas where air leakage occurs, such as the burners, viewing ports, and elbow boxes. Try to minimize air leakage from these areas. ⑥The design ensures a rational structure and appropriate material selection, aiming to minimize the furnace wall temperature and reduce heat loss.

This post was last edited by Blue Flame on 2018-6-13 at 14:16. Answers: (1) Maintain steady operation to ensure complete combustion; (2) Adjust the flue dampers and air valves properly to minimize the excess air coefficient; (3) Improve equipment management, keep the equipment in good condition, and regularly check and seal the burners to prevent large amounts of cold air from entering the furnace.