What are the hazards of silica to boilers?
Destroy the water cycle. The boiler water cycle there are two kinds of natural water cycle and forced water circulation. Circulation is the natural water by the rising proportion of tube and tube under different water pressure difference generated by water circulation. Forced water circulation pump is a mechanical power depends on the role of forced circulation. Whether it is a a form of water circulation, is through the design, that is to say that there is sufficient flow area. When the wall scale, the tube flow area is reduced, the flow resistance increases and the damage to the normal circulation of water, the fire is the gold higher wall temperature. When the pipeline is scale blocked, water circulation completely stopped, the metal wall temperature is higher, the long run will happen explosion accident.
Shorten the service life of the boiler. The service life of the boiler under normal conditions of use, can run continuously for 20 years. But now most of the use of units of the boiler has not been reached in the life, the reason has many aspects, one of which is the scale effect. The drum drum blister, patching after repair, should use the appropriate pressure, to ensure safety, so that the requirements for high pressure steam unit, will have to replace the new boiler.
High content of silica fouling, reduce the thermal efficiency of the boiler, waste a large amount of fuel. The boiler is connected into the scale, the heat transfer performance of the heat released by the combustion of the fuel becomes poor, the heat can not be quickly transferred to the water, so a lot of heat is caused by smoke away, smoke temperature, increase the heat loss, the heat efficiency of the boiler reduced. Two, caused by overheating of the metal, low intensity, endanger the safety of the heating surface of the boiler. The use of steel in general are carbon steel, in the process of use, allowing the metal wall temperature at 450 DEG C. During normal operation of boiler, metal wall temperature is below 280 DEG. When the heating surface of the boiler without scale. The heated metal will soon be heat to the water, then the temperature is about 30 degrees Celsius. But if the heating surface scale, temperature difference between the two is large. When the working pressure is 1.25Mpa The heating surface of the boiler with 1 mm thick scale (mixed scale), temperature difference between the metal wall and water will reach 200 degrees Celsius. When the scale is 3 mm, the metal wall temperature will rise to 580 degrees Celsius, far exceeding the allowable temperature of steel. The tensile strength of steel will be reduced, the boiler pressure parts will be under the inner pressure of overheating, bulge deformation, leakage, and even explosion. The measured data show that the metal wall temperature is increased with the increase of the thickness of the scale, the scale is thicker and the metal wall temperature is higher, the probability of the accident is.
Increase the amount of inspection, a waste of money. Once the boiler fouling, it must be clear, so as to ensure the safe and economic operation of the boiler. The scale more nodes, more consumption of chemicals, investment funds will be more. Such as: 1t/ H type boiler if the average scale of 3 mm, in addition to a scale is needed 0.5 tons of chemicals. Tonnage increased in accordance with the boiler tonnage of different, the required dose will increase 1/3, funds also increased. The general boiler fouling eliminating slightly convenient, if the tube fouling is difficult to eliminate, not only that, if the tube explosion accident, put on a new pipe, welding is not convenient. The drum bulge when patching requirements, a long time, the construction is more difficult. A large bulge reclamation, would cost 1 to 20 thousand yuan of funds. In both the chemical cleaning or purchase materials to repair, must spend a lot of manpower The physical, and skills.
