The negative pressure of gas heating boiler furnace is too large, which indicates that the suction force of induced draft fan is too large. At this time, the air flow in the gas heating boiler is obviously upward, the flame center is moved up, and the smoke temperature at the furnace outlet is increased, which leads to the increase of steam temperature or superheater slagging. The air flow is upturned and the flame stroke is shortened, resulting in incomplete combustion.
If the negative pressure of the furnace is too large, the air leakage of the furnace and flue will be increased, the smoke volume will be increased, and the smoke speed of the heating surface will be accelerated. As a result, the wear of the heating surface and the power consumption of the fan are aggravated. The efficiency of gas heating boiler is reduced, especially when the gas heating boiler is running at low load or unstable combustion, it is likely that the negative pressure of the furnace is too much to extinguish the fire of the gas heating boiler. If the negative pressure of the furnace is too small or the positive pressure is too small, the high temperature smoke and flame in the furnace will not only affect the hygiene of the workshop and endanger the personal safety, but may also cause the furnace coke, injector, steel frame, furnace wall and so on to deform and burn down due to overheating. Therefore, the furnace must maintain a certain negative pressure operation
When the furnace negative pressure rises sharply, the furnace implosion accident may also occur. Implosion can cause water wall damage or personal accident. The causes of implosion are as follows: one is the abnormal operation of the induced draft fan, the high static pressure head or the poor operation of the baffle; the other is that when the fuel supply is cut off due to fire extinguishing, the negative pressure of the furnace increases sharply. Therefore, while cutting off the fuel, the small induced draft fan baffle should be properly turned off to avoid the sharp increase of negative pressure. In addition, the large unit should be equipped with pressure alarm and safety protection device in the furnace. The harm of excessive negative pressure is summarized: air leakage increases, furnace temperature is reduced, combustion instability, furnace wear, fan power consumption and gas heating boiler efficiency are reduced.