Tubular Electric Heater, often abbreviated as electric heating tube, is a common heating element that converts electrical energy into thermal energy. It is widely used in industrial equipment, household appliances, and commercial facilities to heat liquids, gases, or solid surfaces. The following is a core knowledge, classification, selection, and application guide for tubular electric heaters: 1. Basic Structure and Working Principle Structure: Composed of a metal tube (outer shell), spiral resistance wire (heating element), insulating filler (usually high-purity magnesium oxide powder MgO), and sealing materials. Metal tube: Protects internal components and conducts heat. Resistance wire: Generates heat when energized (commonly made of nickel-chromium alloy or iron-chromium-aluminum alloy). Magnesium oxide powder: Fills between the resistance wire and the metal tube, serving dual functions of insulation and heat conduction; after compaction, it quickly transfers heat to the tube wall. Terminal: Located at the tube end, used to connect the power supply, usually with moisture-proof sealing treatment. Principle: Current passes through the resistance wire to generate Joule heat, which is conducted through the dense magnesium oxide powder to the metal tube surface, and then transferred to the heated medium. 2. Main Classifications Based on different uses, materials, and installation methods, they can be divided into various types: A. Classification by Heating Medium Dry-burning electric heating tubes: Used for heating air, solids (such as molds, ovens). Features: Low surface load to prevent overheating and burnout. Usually equipped with fins to increase heat dissipation area. Water/liquid type electric heating tubes: Used for heating water, oil, acid-base solutions, etc. Features: High surface load, must be fully immersed in liquid during use, strictly prohibited from dry burning, otherwise easily damaged. Explosion-proof electric heating tubes: Used for heating flammable and explosive gases or liquids (such as petroleum, chemical environments). Features: The junction box adopts an explosion-proof structure, meeting explosion-proof grade standards (such as Exd II BT4). B. Classification by Tube Material (Determines corrosion resistance and temperature resistance) Table Material Applicable Scenarios Maximum Operating Temperature (Surface) Characteristics Stainless Steel 304 Ordinary water, weak acids, air ~600°C Most commonly used, cost-effective, average corrosion resistance. Stainless Steel 316/316L Seawater, strong acids, food-grade liquids ~600°C Strong corrosion resistance, commonly used in chemical and food processing. Titanium Tube Strong acids (such as electroplating solution), seawater ~300°C Excellent resistance to strong acid corrosion, but more expensive and not resistant to dry burning. Quartz Tube High-temperature radiant heating, clean environments ~800°C+ Fast heating, high thermal efficiency, but fragile. Incoloy 84/800 Extremely high temperatures, harsh environments ~900°C+ Resistant to high-temperature oxidation, long lifespan, used in high-end industries. Carbon Steel/PTFE Coating Specific corrosive liquids Limited PTFE coating resists strong acids and alkalis, but has low temperature resistance (<250°C).
