How to determine whether the air volume adjustment during the combustion process is at the optimal level

How to determine normal operation of a heating furnace: 1. Judge from the instruments: The criterion is that the outlet temperature of the heating furnace is within the specified process range. The temperature difference between various points within the furnace chamber of the cylindrical furnace should not exceed 30°C. Judging from the recorded curve: (1) The curve indicates normal operating conditions ； (2) The curve shows regular fluctuations with a stable center line, which generally indicates that the instrument or the scaling factor is too high and that the response is slow. (3) The center line of the curve is unstable, and the curve changes rapidly in an irregular manner; this usually indicates large fluctuations in fuel pressure or the presence of oil in the gaseous fuel. (4) The curve changes irregularly with a long bending period, but there is also a period of stability, which generally indicates changes in the feed rate or feed temperature. (5) The center line of the curve is unstable, changing rapidly over a short period, yet the changes follow a pattern; this generally indicates that the proportional-integral control is too weak, resulting in excessive effect. (6) A slow upward or downward movement of the line generally indicates a malfunction of the instrument. 2. Judging from the sound of the heating furnace: The operator must assess the operating condition by listening to the sounds emitted by the furnace, focusing on any changes in those sounds. The sound changes of the furnace can generally be categorized as follows: (1) The normal sound of a heating furnace, with a consistent level of noise ； (2) With a loud noise, the engine shuts down; the wind and power are cut off, and steam supply stops suddenly ； (3) The regular back-and-forth thudding sound is caused by improper proportional-integral control of the instrument ； (4) Irregular back-and-forth roaring sounds are caused by improper operator adjustment, changes in feed rate and fuel oil pressure, or gas fuel containing oil. 3. Judgment from the flame in the furnace chamber: The flame should have multiple flames, a short length, be evenly distributed, and of uniform height. The flame of fuel oil should be apricot-colored, while that of gas should be sky-blue. The furnace chamber should be bright, with complete combustion, consistent flame colors, and no smoke coming from the chimney. The flame height is generally around 2 meters. Based on the above criteria, the abnormal phenomena in flame combustion include the following: (1) Incomplete combustion of the flame in the furnace; the flame is weak and limp, its base is dark black, and smoke may even emerge from the chimney. Reason: The ratio of fuel oil to steam is improper; there is too little steam, resulting in poor atomization. (2) The flame in the furnace does not burn completely; it spreads out chaotically, is weak and soft, colored black-red, or smoke emerges from the chimney. Reason: Insufficient steam and air volume. (3) The combustion of some flames does not meet the standards. Reason: Improper adjustment by the operator. (4) The furnace flame is prone to going out. Reason: The fuel oil has excessive viscosity and contains water, or the oil valve is open to a low degree, along with excessive steam volume that also contains water. (5) The fuel exits the combustion channel at the nozzle and burns there. Reasons: Light fuel oil, excessive steam volume, excessive opening of the oil valve, and insufficient air supply. (6) The flame is ejected in an unshaped form. Reason: Clogging in the burner section, and clogging of the burner combustion channel due to carbonization. (7) The duration of the flame cluster is short or long. Reason: Improper proportional-integral control of the instrument. (8) The flame is white and hard, with flickering. Reason: Excessive steam and air volume. (9) Flash fire. Reason: The opening of the oil and steam valves is too large, causing regular and significant fluctuations in fuel oil pressure. 4. Judgment from the heating furnace chimney: (1) It is normal if no smoke is visible coming from the furnace chimney. (2) Emitting intermittent small amounts of black smoke. Reason: Insufficient steam volume, poor atomization, incomplete combustion, or an improper oil-to-vapor ratio in some nozzles, as well as an excessive load on the heating furnace. (3) Emiting thick smoke. Reason: Sudden increase in fuel ； Instrument failure ； Sudden drop in steam pressure ； The furnace tube has burned through. (4) Emit large amounts of gray-black smoke. Reason: Sudden increase in gaseous fuel with oil. (5) White smoke emission. Reason: The superheated steam pipe burst. (6) Yellow smoke emission. Reason: Confused operations ； Improper adjustment ； This caused some nozzles to stop functioning ； Fuel oil vapor carries smoke out of the flue ； Incomplete combustion.

This post was last edited by dongjiang1001 on 2012-2-23 17:17. The pressure fluctuations inside the furnace are minimal.

This post was last edited by dongjiang1001 on 2012-2-23 at 17:17. Thank you for sharing; I’ve learned something from it.

Testing method: Increasing or decreasing the air volume will both result in a decrease in the boiler load; the air volume at this point is the optimal one.

The adjustment of the boiler’s air volume can be observed from the following aspects: for reference only. 1. The color of the flame. In excess, the color becomes a glaring bright white. When insufficient, the flame appears golden yellow. Under normal conditions, the flame is orange-yellow. 2. Is the flame uniform within the furnace, and is the flue gas flow stable? 3. Whether the fire bed is even, and whether there is any flame jumping in different areas. 4. Is the entire furnace chamber under a slight negative pressure? 5. Is the color of the exhaust gas discharged from the chimney light gray? 6. Is the flow rate of the flue gas too high? 7. If possible, measure the levels of oxygen and carbon monoxide in the exhaust gas.

Testing method: Increasing or decreasing the air volume will both result in a decrease in the boiler load; the air volume at this point is the optimal one.

This post was last edited by dongjiang1001 on 2012-2-23 at 17:17. The smoke is gray; buy a smoke analyzer to check its composition. This testing method doesn’t work; it isn’t that precise. Both increasing and decreasing the air volume result in a decrease in the boiler’s load, and the air volume at this point represents the optimal value.

This post was last edited by dongjiang1001 on 2012-2-23 at 17:17. The flame is golden yellow; if ventilation is insufficient, it turns red, and if ventilation is excessive, it turns white.