Cool cloud technology in doing boiler wear-proof system product analysis, had a boiler tube rupture in a detailed survey and summary, summed up the cause of keeping the boiler, this article will summarize out various reasons, and the water quality and make a detailed analysis of burst pipes caused water shortage problem.
Caused by boiler tube of 7 major reasons
1, inner salt accumulation tube wall corrosion: substandard quality pot of water, saturated steam with water, salt resulting product superheater tube wall leading to overheating and the squib; high oxygen content feed water; or a low water flow, often causes economizer pitting inner wall pipe explosion; high temperature corrosion caused superheater, one of the causes of the water wall tube squib.
2, water or Stokes, improper shutdown procedure, uneven heating or cooling pipe, large thermal stress is generated.
3, during operation, steam pressure, steam temperature gauge (off-design operating conditions), hot deviation is too large, the tube expansion creep speed, so that the pipe burst.
4, a large load variation, mutation causing the pressure pot, so water circulation is not normal (slow, arrest), or the tube overheating occurs alternating stress fatigue cracking.
5, improper adjustment operation, such as flame skew, partial slagging burning grate plenum, seam thickness and transmission improper adjustment, the drum does not match or adjust the wind uncoordinated, will lead to local overheating of the tube.
6, bad manufacturing, installation, maintenance quality. The poor quality pipes or steel pipes wrong; substandard quality weld pipe; severe thinning the wall thickness at the elbow; a foreign body inside the tube causes the tube cross-sectional area decreases or stuffed; overhaul have been creeping inflation gauge pipe undetected, has been worn thin tube did not find.
7, economizer ash wear is the leading cause of burst pipes. Burner outlet airflow deflection, a "flash", "adherent" phenomenon, the water wall tube wear, is one of the causes of water wall tube squib.
Water plays a very important role in keeping the accident boiler, this article will be poor water quality and water shortages also listed out
The three major causes of poor water quality pipe explosion
1, the high water hardness causing damage to the inner tube furnace tube fouling
Due to the high water hardness, the inner surface of the boiler quickly at the metal layer of hard scale, scale the thicker end until the tube closed, This phenomenon occurs in the high-temperature region, because fouling inside the tube, the tube wall not water cooled tubes creep (low carbon steel typically exceed 450 ℃ began to creep), it will be deformed until the bulge squib.
2, the furnace tube so that oxygen corrosion strength is greatly lowered until squib
Since the low pressure boiler apparatus generally not oxygen, dissolved oxygen in feed water is often high, the boiler water is heated, the dissolved oxygen in the water will be released, and further the metal corrosion in the boiler. The main factors affecting the oxygen corrosion are:
① furnace oxygen content in water;
② boiler water temperature;
③ boiler water flow rate;
④ size of the load.
The higher oxygen content of boiler water corrosion soon; the higher the water temperature of the furnace on the fast etching; faster the flow rate of corrosion on the boiler water fast; boiler load greater corrosion soon;
3, a dissolved salt corrosion damage to the tube and reduce its strength until squib
Boiler water salinity of different size, in particular the presence of calcium and magnesium chloride content in the feedwater, such a high saline water into the boiler, become very good electrolyte in the boiler, the convection tube in the vicinity of the water, in particular higher flue gas temperature at the convection bank, electrochemical corrosion at a fast speed, so that the tube quickly rotten.
Precaution
① strengthen the sense of responsibility of the operator, be prepared to handle the work of boiler feed water;
② strict inspection, testing indicators boiler feed water, to meet the requirements;
③ strictly control the salt content of saturated steam;
④ improve the separation efficiency and service quality water separator to ensure the tightness of water supply installations, boiler operation to prevent the water level is too high, overload, over-temperature operation.
Burst pipes caused by lack of water
The starting point is the steam boiler is allowed to dry, with the boiler water level gauge, water level alarm, automatic water supply device and the like in order to protect the normal water level in the boiler during operation. The main causes of water shortage are:
① fireman staff negligence, water level monitoring is not enough, not timely adjust the operating level or lower;
② water level is false water level, steam flow meter or water flow meter indicates an incorrect result in the operator make wrong judgments;
③ boiler feed water valve failure automatically adjust water pressure decreases, the pressure reduced soft drinks;
④ heating surface after the occurrence of a serious leakage of burning a large amount of water, such as a water wall tube or pipe tobacco storage damaged or the like, will cause the water tube rupture;
⑤ improper sewage pipe leakage or short, will cause water tube rupture;
⑥ soda boiler water level table with tube blockage is one cause of burst water pipe.
Due to the rapid increase in boiler water, most of the local tube or not cooling water, causing the temperature of the tube, the mechanical strength decreases rapidly, since the stress generated in the pressure tube exceeds the yield limit of the material, resulting in deformation of the tube, bulge squib.
Precaution
Process boiler operation must maintain normal water level. When the water level is below the safety level identification line, called the lack of water accidents, water accidents and incidents divided severe water shortages, water scarcity general accident two kinds. According to the new standards: the visible edge of the table below the minimum level is the severe water shortage, should immediately shutdown (does not have to be called water). It called a general shortage of water between the line and the lowest security level to identify visible edge.
To avoid water accidents, should:
① constant attention level monitoring, periodic flushing water gauge, indicating the level correction table;
② strict regulation of water flow meter, making it compatible with evaporation;
③ correct implementation of sewage regulations;
④ strengthen routine maintenance, periodic maintenance boilers to improve the ability of the operator to determine the operating level and the actual ability to deal with accidents, eliminate hidden hazards, strengthen the sense of responsibility of the operator, strict adherence to rules.