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Maintenance method of steam boiler


The following main steam boiler cleaning and maintenance methods, I hope to help you:

(I) necessity of boiler cleaning

Boiler after a long time of operation, the inevitable occurrence of scale, corrosion problems, the main reason for the formation of scale boiler is to give water with a hardness component, after high temperature, high pressure of continuous evaporation and concentration, a series of physical and chemical reactions in the furnace, the final formation of hard, dense scale on the heating surface.Scale is the "most harmful" of boilers, and the main cause of boiler accidents.

1, waste a lot of fuel (chengdu and surrounding boiler cleaning)

Because the thermal conductivity of scale is only a few tens of steel, so when the heating surface scale will hinder the heat transfer, in order to maintain a certain boiler output, it is necessary to increase the temperature of the fire side, so that outward radiation and smoke exhaust caused heat loss.Due to different boiler working pressure, different types and thickness of scale, different amount of fuel is wasted. According to the test and calculation, the thickness of scale and fuel loss are as follows:

When scale thickness (S) ≥1mm, 5 ~ 13% of fuel is wasted.  

≥2mm, waste fuel 13 ~ 18%;  

When ≥3mm, 18 ~ 26% of fuel is wasted.  

2, easy to make steel plate, pipe due to overheating and be burned

Because the boiler after scaling, and to maintain a certain working pressure and evaporation, only to increase the temperature of the fire side, but the thicker the scale, the lower the thermal conductivity, the higher the temperature of the fire side.Generally speaking, the temperature on the fire side of the boiler is around 900℃, while the temperature on the water side is around 190℃.When there is no scale, the temperature of the steel plate is about 230℃. Once the scale is about 1mm, the temperature of the steel plate is about 140℃ higher than that without scale.20# steel when the temperature reaches 315℃, the metal plasticity index began to decline, when 450℃, the metal will creep deformation due to overheating.So boiler scale is easy to burn metal damage.  

3. Increase maintenance cost and reduce service life

Boiler accidents caused by scale are about one third of the total number of boiler accidents, which is still on the rise, not only causing damage to equipment, but also threatening personal safety.  

Therefore, in the case of qualified water supply, boiler operation should strictly control the pot water to meet the national standards;And in the operation to prevent the formation of scale, and scale, need to be treated in time, must be completely prevent and remove the scale and control water quality.To solve the above problems, the most scientific method is to add good comprehensive performance, comprehensive efficacy of the operation of the boiler maintenance and regular cleaning and scaling.  

(ii) solutions

In order to make the boiler system in the optimal state of operation, it is necessary to boiler system water system special chemical treatment: remove scale, corrosion and corrosion prevention treatment:

1, chemical cleaning: cleaning of boiler is the convection pipe, boiler superheater tube, air heat exchanger, water wall tube scale, rust cleaning, to join the system at the time of chemical cleaning agent will floating rust, scale, oil cleaning, back into clean metal surface, according to the different working conditions have stopped cleaning and keep furnace cleaning two;  

A, before cleaning, factory to help us deal with the furnace boiler internal and external detailed inspection, in case of leakage, scale of A boiler wall tube (tube by root check each pipe within the drum for blocking phenomenon), scale down pipe and perforation, furnace tube deformation problem, effective measures should be taken in advance to deal with and recorded in detail.  

B. Before cleaning, the type and total amount of scale shall be determined. The thickness of scale layer at different parts shall be measured when taking scale samples to calculate the total amount of scale and the amount of drug used.  

C. general steps of cleaning:

Water rinsing (leak detection) -- acid rinsing -- alkali rinsing -- water rinsing -- rinsing -- passivation.  

D. acceptance standards for cleaning quality:

Annex: boiler chemical cleaning rules issued by the state bureau of quality and technical supervision require that boiler chemical cleaning should meet the following standards:

(1) when cleaning carbonate scale, the scale removal area should reach more than 80% of the original scale coverage area;  

(2) when cleaning silicate or sulfate scale, the scale removal area should reach 60% of the original scale coverage area;  

(3) the average corrosion velocity of metal measured by the weight loss method of corrosion test plates should be less than 6g/m2•h.  

2. Daily maintenance: the daily maintenance is to conduct water quality treatment of boiler water. Gr-943c boiler scale inhibitor and gr-201 gram scale agent are added into the automatic dosing system to avoid metal rust and prevent calcium and magnesium ion crystallization and precipitation.  

Gr-943 has filled the gap at home and abroad with gr-201g neutral and non-acidification technical cleaning technology, which brings a revolution to chemical cleaning and a new chapter of green and neutral chemical cleaning.This technology can be used in the normal production process without stopping the cleaning, no corrosion damage to the equipment.Waste cleaning liquid does not need to be treated to meet the emission standard, no pollution to the environment.It has become an inevitable trend that neutral non-acidification cleaning replaces pickling.  

1, neutral operation cleaning can be in neutral or weak alkaline (pH value 7~12) conditions, do not change the state stipulated boiler water operating indicators, do not stop cleaning, can reduce the loss caused by the stop cleaning, this is the only sign of neutral cleaning.  

2. Efficient scale removal?Using the principle of chemical coordination field, gr-943 and gr-201 of descaling are applied to conduct coordination field chemical reaction with Ca2+, Mg2+, calcium and magnesium compounds in the water to prevent the formation of scale crystallization and gradually decompose the original scale, forming colloidal suspended substance to be discharged from the boiler.It can clean the insoluble scale that can't be cleaned by pickling, with high cleaning rate.  

3. Safe and corruption-free?Theoretical research and boiler operation practice have proved that the cleaning corrosion rate is less than that of water on metal without any corrosion damage.  

No toxicity, no pollution?Gr-943 and gr-201 grams of grime are green environmental protection products, and the COD, BOD and pH values of the boiler after cleaning are fully in line with national standards.  

5. Easy to use?Drugs can be added to the water supply, no need for another professional, post operators can operate, can be widely used.  

6. Significant water saving. The water consumed in the whole cleaning process is normal production water, unlike acid pickling, which consumes a large amount of fresh water resources consumed by drug dispensing, passivation and repeated flushing.