There are many customers who often complain about the poor quality and short life of the heating elements they used before, what is the reason for this? What are the internal factors that can affect the service life of an electric heaters?
The factors that affect the service life of the heating tube are different in different environments, so the following heating media can be used to analyze the life of the electric heaters:
I. Air dry-fired heating
The heating tubes used to heat air include mold cartrdige heaters, U-shaped tubular heaters, finned tubular heaters and other shapes of electric heaters.
1、Cartridge heater for molding
a, the use of mold cartridge heater when the mold hole diameter than the heating pipe diameter of the tube is 0.1-0.2mm, because the air heat conduction of the heating pipe is a hindrance, if the mold hole diameter and heater tube diameter gap is too large, the mold can not be timely to absorb the heat from the heating tube , The mold cannot absorb the heat from the heating tube in time. this will cause the surface temperature of the heating tube of the mold to rise, and the internal temperature is too large. To a certain extent, the heating tube will expand, burst, or burn out the resistance wire , Resulting in a shorter life of the mold heating tube;
b. Before designing the mold cartridge heaters, determine the working temperature of cartridge heaters, and use the heater material suitable for their working temperature. And to carry out a certain temperature control to prevent the working temperature is too high and burn out the electric heating tube.
c, if the mold in the work will produce vibration, the resistance wire of molding cartridge heater need to choose a relatively good flexibility of nickel-chrome wire, to prevent the resistance wire of cartridge heaters from breaking due to vibration
2.U-shaped tubular heaters and finned air tubular heaters and other dry-fired tubular heaters.
a, these heating tube in the air dry burning when the power per meter should be controlled at 1KW, in the fan cycle when the maximum of 1.5KW.exceeds this standard, the surface load of the heating tube is too large, so the heating tube surface temperature will increase, resulting in the heating tube internal temperature is too high and burned resistance wire, the seriousness of the tube will make the occurrence of expansion, the phenomenon of burst pipe, thus reducing the service life of the heating tube.
b, according to the working temperature to choose the appropriate heating tube material, such as the oven working temperature is 600 degrees, you can not use the temperature of 300-400 degrees of stainless steel 304 material, we should use the temperature of 700 degrees of stainless steel 310s material. And a certain temperature control should be carried out to prevent the working temperature from being too high and burning the heat pipe. If the right material is not chosen, or the temperature is not controlled properly, then the service life of electric heaters will be shortened.
II. Liquid heating
Here are the liquids including general liquids (pure water, tap water, groundwater, oil) and weak acid and weak base liquids.
The heating pipes for heating liquids are threaded cartrdige heaters, U-type waterproof electric heaters, W-type electric heaters, wire buckle flange heaters, flat flange heaters, etc.
1.Heat ordinary water
a, per meter power control between 1-3KW, power over the limit will accelerate the formation of scale, once the scale condenses on the surface of the electric heating tube to a certain extent, it will hinder the heat transfer of the heating tube, then the heating tube surface load is too large, so the heating tube surface temperature will increase, resulting in the heating tube internal temperature is too high and burned resistance wire, serious will make the electric heating tube internal expansion, the phenomenon of burst pipe, thus reducing the life of the heating tube.
b, to ensure that the heating zone of the heating tube is fully immersed in the liquid, itself heating tube heating zone surface temperature is very high, if separated from the water surface, the heat can not be absorbed in time, resulting in the heating tube surface load is too large, so the heating tube surface temperature will increase, resulting in the heating tube internal temperature is too high and burn the resistance wire, so the heating tube life will be shortened.
c. The water in some parts of the country is very hard and very prone to limescale. At this point, the design of the heating tube should reduce the power per meter of the heating tube, usually within 2KW. Or use the Shenglong developed waterproof scale coating heaters, the scale will automatically fall off after a certain degree, so that the heaters can quickly dissipate heat, to achieve the effect of protecting the heating tube. Conversely, the heater has a short life.
2、Heat acid and alkaline corrosive liquid
The heating of acidic and alkaline liquids affects the life of the heating tube, in addition to the heating zone dry burn phenomenon and power overload like the heating of general liquids, and more importantly the material of the heating tube. Acid and alkali resistant heating tube material is generally used 316L or titanium tube, if no corrosion resistant material is used, the heating tube surface is corroded, the phenomenon of leakage, the heating tube life becomes short.
III. Heating oil
a, heating oil is generally controlled at 1KW per meter of power, if the mobility is strong, good oil without impurities, at most 1.5KW per meter of power is greater than this standard, will accelerate the formation of oil scale, that is, the phenomenon of carbon. Once the oil scale condensation on the surface of the electric heating tube to a certain extent, it will hinder the heat emitted by the heating tube can not be quickly emitted, resulting in the heating tube surface load is too large, so that the heating tube surface temperature will increase, ultimately leading to the heating tube internal temperature is too high and burned resistance wire, the seriousness of the tube will make the tube expand, resulting in burst pipe phenomenon, thus shortening the life of the heating tube.
b、Heating oil should also consider the pressure factor, used in the reactor heat transfer oil inside the heating tube, if the pressure is too high, we should choose seamless tube. If not in use, the heating tube cracks due to high pressure, which can shorten the life of the heating tube.
