在燃油鍋爐的運行管理中，我們經常會接觸到一個詞“超低負荷運行”，那么鍋爐多大負荷運行才算是超低負荷運行？超低負荷運行有什么危害呢？

In the operation management of the fuel boiler, we often come into contact with a word "ultra low load operation", then how much load of the boiler operation is the super low load operation? What are the hazards of ultra low load operation?

一般鍋爐正常負荷變化范圍是：燃煤鍋爐為額定負荷的70%～100%，燃油鍋爐為額定負荷的60%～100%。低于這個范圍運行時即視為超低負荷運行。

The scope of the normal load change of the boiler is: 100% to 70% of the rated load, the fuel oil boiler is 60% ~ 100% of the rated load. The lower than the scope of operation that is regarded as a super low load operation.

鍋爐超低負荷運行的危害主要有：

The main hazards of the operation of the ultra low load of the boiler:

（1）燃油鍋爐水循環可靠性下降

(1) the reliability of boiler water cycle decreased

燃油水循環通常采用自然循環方式。超低負荷運行時，因為鍋爐投入燃料量少，整個爐膛溫度下降，水冷壁受熱減弱，鍋爐水循環流速會相應降低，水循環可靠性下降。

Natural circulation mode is usually used in fuel oil water cycle. Low load operation, because the boiler fuel is less, the entire furnace temperature is decreased, the water wall is weakened, the boiler water circulation flow rate will be decreased, and the water cycle reliability decreased.

（2）難以保證蒸汽的品質

(2) it is difficult to ensure the quality of steam

隨著鍋爐負荷的降低，蒸汽的溫度和濕度將會受到影響，尤其是對于有過熱器的鍋爐而言，當鍋爐負荷降低時，出口汽溫也隨著下降，難以維持額定的汽溫，蒸汽品質變差。當過熱蒸汽溫度下降到低于額定值時，汽水系統受熱面工況將進入危險區，這時的負荷被稱為技術上的最低允許負荷。

With the decrease of boiler load, temperature and humidity will be affected by the steam, especially for boiler superheater, when the boiler load decreases, steam temperature decreased, it is difficult to maintain the rated steam temperature, steam quality variation. When the superheated steam temperature drops below the rated value, the heating surface of the steam water system will enter the danger zone, when the load is known as the minimum allowable load.

（3）鍋爐尾部受熱面，如空氣預熱器、省煤器以及熱水鍋爐本體的尾部受熱面等酸腐蝕加劇

(3) the heating surface of the boiler tail, such as the air preheater, the provincial coal heater and the hot water boiler body, such as the heated surface, such as the heated surface

通常鍋爐按正常符合設計鍋爐受熱面和排煙溫度，排煙溫度一般都會高于露點溫度。超低負荷運行時，爐內各部溫度均不同程度下降，最終排煙溫度也會降低。極易使低溫受熱面的金屬壁溫低于硫酸汽的露點溫度，硫酸蒸汽便會在低溫受熱面上結露，從而造成低溫受熱面的腐蝕。

Normal boiler according to the normal design of boiler heating surface and smoke exhaust temperature, exhaust gas temperature is generally higher than the dew point temperature. The temperature of each part of the furnace is decreased at different degrees, and the temperature of exhaust gas will be decreased at the low load operation. Easy to make low temperature heating surface of the metal wall temperature below the dew point temperature of sulfuric acid sulfuric acid vapor, steam will be in the low temperature heating surface condensation, resulting in the low temperature corrosion.

因此，燃油鍋爐在運行管理中，應盡量避免鍋爐超低負荷運行的情況發生。

Therefore, the operation of the fuel boiler in the management, should try to avoid the occurrence of ultra low load operation of the boiler.