The occurrence of boiler tube burst seriously affects the safety of the boiler and the economy of the unit operation. Very likely to cause injury to operators, the following Shandong Gas Boiler Factory will summarize the causes of the boiler tube burst, I hope you pay more attention to it, to help you all! 

（1）鍋爐運(yùn)行中操作不當(dāng)，爐管受熱或冷卻不均勻，產(chǎn)生較大的應(yīng)力。

(1) The operation of the boiler is improper, and the heating or cooling of the furnace tube is not uniform, resulting in greater stress.

1)冷爐進(jìn)水時(shí)，水溫或上水速度不符合規(guī)定；啟動(dòng)時(shí)，升溫升壓或升負(fù)荷速度過(guò)快；停爐時(shí)冷卻過(guò)快。

1) When the cooling furnace feeds water, the water temperature or feeding speed does not conform to the regulations; when starting, the speed of temperature and pressure rise or load increase is too fast; when stopping the furnace, the cooling rate is too fast.

2)機(jī)組在啟?；蜃児r運(yùn)行時(shí)，工作壓力周期性變化導(dǎo)致機(jī)械應(yīng)力周期性變化；同時(shí)，高溫蒸汽管道和部件由于溫度交變產(chǎn)生熱應(yīng)力，兩者共同作用造成承壓部件發(fā)生疲勞破壞。

2) The cyclical change of working pressure leads to the cyclical change of mechanical stress during start-up, shut-down or off-design operation of units; meanwhile, the thermal stress of high-temperature steam pipes and components due to temperature alternation causes the fatigue damage of pressure components.

（2）運(yùn)行中汽溫超限，使管子過(guò)熱，蠕變速度加快

(2) In operation, the steam temperature exceeds the limit, which makes the pipe overheated and the creep speed accelerated.

1)超溫與過(guò)熱。

1) Overheating and overheating.

過(guò)熱可分為長(zhǎng)期過(guò)熱和短期過(guò)熱兩大類，長(zhǎng)期過(guò)熱爆管是指金屬在應(yīng)力和超溫溫度的長(zhǎng)期作用下導(dǎo)致爆破，其溫度水平要比短期過(guò)熱的水平低很多，通常不超過(guò)鋼的臨界點(diǎn)溫度。

Overheating can be divided into two categories: long-term overheating and short-term overheating. Long-term overheating tube explosion refers to metal explosion under long-term stress and overheating temperature. Its temperature level is much lower than that of short-term overheating, and usually does not exceed the critical temperature of steel.

超溫是指金屬超過(guò)額定溫度運(yùn)行。超溫分為長(zhǎng)期超溫和短期超溫，長(zhǎng)期超溫和短期超溫是一個(gè)相對(duì)概念，沒(méi)有嚴(yán)格時(shí)間限定。超溫是指運(yùn)行而言，過(guò)熱是針對(duì)爆管而言。

Overtemperature refers to the operation of metals above rated temperature. Overtemperature can be divided into long-term overtemperature and short-term overtemperature. Long-term overtemperature and short-term overtemperature are relative concepts without strict time limit. Overheating refers to operation, and overheating refers to explosion.

短期過(guò)熱爆管是指，在短期內(nèi)由于管子溫度升高在應(yīng)力作用下爆破，其溫度水平較高，通常超過(guò)鋼的臨界點(diǎn)溫度，會(huì)導(dǎo)致金屬組織變化發(fā)生相變。

Short-term superheated tube blasting refers to the high temperature level of tube blasting under stress in a short time due to the increase of tube temperature, which usually exceeds the critical point temperature of steel, leading to the transformation of metal structure.

2)熱偏差

2) thermal deviation

影響熱偏差的主要因素是熱應(yīng)力不均和水力不均。

The main factors affecting thermal deviation are uneven thermal stress and hydraulic pressure.

3)傳熱惡化

3) Deterioration of heat transfer

類傳熱惡化也稱作膜太沸騰，是指管外熱負(fù)荷過(guò)大，因管壁形成汽膜導(dǎo)致的沸騰傳熱惡化。

The first type of heat transfer deterioration, also known as membrane boiling, refers to the deterioration of boiling heat transfer caused by the excessive heat load outside the tube and the formation of vapor film on the tube wall.

類傳熱惡化所對(duì)應(yīng)的臨界熱負(fù)荷非常大，大型電站鍋爐一般不會(huì)發(fā)生。

The critical heat load corresponding to the deterioration of the first type of heat transfer is very large, and large utility boilers generally do not occur.

第二類傳熱惡化即管內(nèi)環(huán)狀流動(dòng)的水膜被撕破或者“蒸干”。發(fā)生第二類傳熱惡化的熱負(fù)荷低于類傳熱惡化的熱負(fù)荷值。直流爐因加熱、蒸發(fā)、過(guò)熱三階段無(wú)明顯分界點(diǎn)，工質(zhì)含汽率x 由0逐漸上升到1，發(fā)生第二類傳熱惡化不可避免。

The second type of heat transfer deterioration is that the annular flow of water film in the tube is torn or "steamed dry". The heat load of type II heat transfer deterioration is lower than that of type I heat transfer deterioration. Because there is no obvious boundary point in three stages of heating, evaporation and overheating, the vapor content x of working medium gradually rises from 0 to 1, and the second type of heat transfer deterioration is inevitable.

直流鍋爐蒸發(fā)受熱面的沸騰傳熱惡化現(xiàn)象主要與工質(zhì)的質(zhì)量流速、工作壓力、含汽率和管外熱負(fù)荷有關(guān)。

The deterioration of boiling heat transfer on evaporative heating surface of once-through boiler is mainly related to mass flow rate, working pressure, vapor content and heat load outside the tube.

（3）受熱面磨損

(3) Wear of heating surface

受熱面磨損是由含灰氣流對(duì)受熱面沖刷撞擊造成的。受熱面磨損的速度與氣流速度的三次方成正比，與飛灰濃度成正比，與管子的排列方式、管子的耐磨性能有關(guān)，同時(shí)，飛灰硬度、形狀、直徑大小也是影響受熱面磨損速度的因素。

The wear of the heating surface is caused by the erosion and impact of the ash-containing air flow on the heating surface. The wear rate of heating surface is directly proportional to the cubic power of air velocity and fly ash concentration. It is related to the arrangement of pipes and the wear resistance of pipes. At the same time, the hardness, shape and diameter of fly ash are also factors affecting the wear rate of heating surface.

受熱面磨損是省煤器爆管的主要原因。

Wear of heating surface is the main cause of tube burst of economizer.

（4）受熱面腐蝕。

(4) Corrosion of heating surface.

1)爐管內(nèi)高溫氧化腐蝕。受熱面管子中鐵離子在一定的溫度下氧化，隨著受熱面壁溫度升高，氧化速度不斷加快；當(dāng)溫度高于580℃時(shí)，爐管金屬內(nèi)壁氧化皮層由FeO、Fe2O3、Fe3O4三種氧化物組成，靠近金屬的氧化物FeO構(gòu)成氧化層的主要部分。

1) High temperature oxidation corrosion in furnace tube. The oxidation rate of iron ions in heating surface tubes is accelerated with the increase of heating surface temperature at a certain temperature. When the temperature is higher than 580 C, the oxide layer of inner metal wall of furnace tubes is composed of three oxides: FeO, Fe2O3 and Fe3O4, and the oxide FeO near the metal is the main part of the oxide layer.

2)爐管內(nèi)結(jié)垢、腐蝕。給水品質(zhì)不良，爐水品質(zhì)差，引起爐管管內(nèi)結(jié)垢，結(jié)垢后易產(chǎn)生垢下腐蝕。同時(shí)，結(jié)垢使傳熱熱阻增大，管壁溫度上升，強(qiáng)度減弱，發(fā)生爆管。

2) Scaling and corrosion in furnace tubes. The poor quality of feed water and the poor quality of furnace water cause scaling in the furnace tube, and corrosion under scaling easily occurs after scaling. At the same time, scaling increases heat transfer resistance, increases wall temperature, weakens strength and bursts occur.

3)受熱面的高溫黏結(jié)灰和高溫腐蝕。在高溫?zé)煔猸h(huán)境中，飛灰沉積在受熱面管子表面，煙氣和飛灰中的有害成分（復(fù)合硫酸鹽）會(huì)與管子金屬發(fā)生化學(xué)反應(yīng)，使管壁減薄、強(qiáng)度降低，稱為高溫腐蝕。

3) High temperature bonding ash and high temperature corrosion of heating surface. In high temperature flue gas environment, fly ash deposits on the surface of heating surface pipes. The harmful components (compound sulfate) in flue gas and fly ash will react with the metallic elements of pipes, making the pipe wall thinner and the strength lower, which is called high temperature corrosion.

4)制造、安裝、檢修質(zhì)量不良。如管材或管子鋼號(hào)錯(cuò)誤、管子焊口質(zhì)量不合格、彎頭處管壁嚴(yán)重減薄。

4) The quality of manufacture, installation and overhaul is poor. If the pipe or pipe steel number is wrong, the quality of the pipe weld is not qualified, and the pipe wall at the elbow is seriously thinned.

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