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In the manufacturing of duct electric heater systems, welding is a very important step. Most of the system is transported through pipelines, so the connections between pipelines and between pipelines and other components, except for bolted connections, are made by welding. First, weld the flange to the pipe, then connect the two pipes through bolted connections. Since the pipeline contains hot oil, the temperature and pressure are relatively high, and the quality of welding directly affects the quality of the entire system. Thus, welding process is an indispensable step in the design of heat transfer oil systems.

　　Welding is a process of local rapid heating and cooling of the duct electric heater. The welding area, constrained by the surrounding workpiece body, cannot expand and contract freely. After cooling, welding stress or even deformation will occur in the weldment.

　　Duct electric heater consists of two parts: the main body and the control system. The heating element uses stainless steel tube as protective casing, high-temperature resistance alloy wire, and crystalline magnesium oxide powder, formed by compression process. The control part adopts advanced digital circuits, integrated circuit triggers, high reverse voltage thyristors, etc., to form an adjustable temperature measurement and constant temperature system, ensuring the normal operation of the electric heater.

　　Product features and technical features of duct electric heater

　　Duct electric heater is mainly used for heating air in ducts. The specifications are divided into three types: low temperature, medium temperature, and high temperature. The common feature in structure is the use of steel plates to support the electric heating tubes to reduce vibration, and the junction box is equipped with an overtemperature control device. In addition to overtemperature protection, an interlocking device is installed between the fan and the heater to ensure that the electric heater starts only after the fan starts. A differential pressure device is added before and after the heater to prevent fan failure. The gas pressure for duct heating generally should not exceed 0.3Kg/cm2. If it needs to exceed the above pressure, please choose a circulating electric heater. The gas heating temperature for low-temperature heaters does not exceed 160°C; medium-temperature does not exceed 260°C; high-temperature does not exceed 500°C. Duct electric heaters are used in industrial ducts, air conditioning ducts, and various industries for air heating to increase the output air temperature. They are generally inserted horizontally into the duct. According to the duct working temperature, they are divided into low, medium, and high temperature; according to the air velocity in the duct, they are divided into low, medium, and high wind speed.

　　Product features:

　　1. The electric heater adopts externally wound corrugated stainless steel strip, increasing the heat dissipation area and greatly improving the heat exchange efficiency.

　　2. The heater design is reasonable, with low wind resistance, uniform heating, and no high or low temperature dead corners.

　　3. Dual protection, good performance. The heater is equipped with a thermostat and fuse to control the duct air temperature in case of overtemperature and no wind, ensuring foolproof operation.

　　Product applications:

　　Heating air for drying/sulfurization, heat treatment, reheating, dehumidification, and other similar applications of various substances.

　　Technical features:

　　1. Can heat air to very high temperatures, up to 450°C, with the shell temperature only about 50°C.

　　2. High efficiency: up to 0.9 or more.

　　3. Fast heating and cooling rates, up to 10°C/s, with fast and stable adjustment. There will be no leading or lagging of the controlled air temperature, causing temperature control drift, making it very suitable for automatic control.

　　4. Good mechanical performance: Because the heating element is made of special alloy material, under the impact of high-pressure air flow, it has better mechanical performance and strength than any other heating element, which is more advantageous for systems and accessory tests that require continuous air heating for a long time.

　　5. When used in accordance with operating procedures, it is durable and has a service life of up to several decades.

　　6. Clean air, small size, beneficial to the people.



Note: The above information and technical parameters are published by Yangzhou Darui Electric Co., Ltd.