BGY4/BGY2 Constant Temperature Explosion-Proof Tubular Electric Heater
BGY4/BGY2 Constant Temperature Explosion-Proof Tubular Electric Heater
Electric heating is the process of converting electrical energy into thermal energy. Since the discovery that current passing through a conductor can produce thermal effects, many inventors around the world have been engaged in the research and manufacturing of various electric heating appliances. The development and widespread application of electric heating, like other industries, follows a pattern: from advanced
Electric Heater
Electric Heater
countries gradually spreading to the world; from cities gradually developing to rural areas; from collective use to household and then to individual use; products from low-end to high-end. In the 19th century, electric heating appliances in their infancy were mostly crude. The earliest electric heating appliances were for daily life. The prototype of the electric iron first appeared and was used in the United States in 1893, followed by the use of electric stoves in 1909, where electric heaters were placed in stoves, meaning heating shifted from firewood to electricity, i.e., from electrical energy to thermal energy. However, the rapid development of the electric heating appliance industry truly began after the invention of nickel-chromium alloy as a heating element. In 1910, the United States first successfully developed an electric iron using nickel-chromium alloy heating wire, which fundamentally improved the structure of the iron and quickly popularized its use. By 1925, products with electric heating elements installed in Japanese pots became the prototype of modern rice cookers. During this period, industrial electric heating products such as laboratory electric furnaces, glue melting furnaces, and heaters also emerged. The years 1910 to 1925 were a major development period in the history of electric heating appliances. In both household and industrial sectors, various types of electric heating appliances appeared and were rapidly popularized, especially in households. Therefore, the invention of nickel-chromium alloy laid the foundation for the development of the electric heating appliance industry.
After the 1920s, there were fewer new application developments than in the previous period, but during this stage, all kinds of electric heating appliances were redesigned and continuously improved, becoming a period of improvement in the history of electric heating appliances. In household electric heating appliances, various devices were designed to be more aesthetically pleasing, durable, and robust, and most had automatic temperature and time control.
Measurement Units
1. Power: W, kW 1kW=3.412BTU/hr British Thermal Units per hour=1.36 (horsepower)=864Kcal/hr
2. Weight: kg: 1kg=2.204621b (pound)
3. Flow velocity: m/min
4. Flow rate: m3/min, kg/h
5. Specific heat: Kcal/(kg℃): 1Kcal/(kg℃)=1BTU/hr.°F=4186.8J/(kg℃)
6. Power density: W/cm2: 1W/cm2=6.4516 W/in2
7. Pressure: MPa
8. Thermal conductivity: W/(m℃): 1 W/(m℃)=0.01J/(cm s℃)=0.578Btu/(ft.h.F)
9. Temperature: ℃: 1F=9/5℃+32 1R=9/5℃+491.67 1K=1℃+273.15
Power Calculation
The calculation of heating power includes the following three aspects:
Power during operation
Power during startup
Heat loss in the system
All calculations should consider the worst-case scenario:
Lowest ambient temperature
Shortest operating cycle
Highest operating temperature
Maximum weight of heating medium (maximum flow rate for flowing medium)
Steps for calculating heater power:
Based on the process, draw the heating process flow diagram (not involving material form or specifications).
Calculate the heat required for the process.
Calculate the heat and time required for system startup.
Redraw the heating process flow diagram, consider appropriate safety factors, and determine the total power of the heater.
Determine the sheath material and power density of the heating element.
Determine the form, size, and quantity of the heater.
Determine the power supply and control system of the heater.
Working Principle
The fluid explosion-proof electric heater is a device that consumes electrical energy and converts it into thermal energy to heat the material to be heated. During operation, the low-temperature fluid medium enters the input port under pressure through the pipeline, flows along the specific heat exchange channel inside the electric heating container, following the path designed based on fluid thermodynamics, and carries away the high-temperature thermal energy generated by the electric heating element during operation, thereby raising the temperature of the heated medium. The outlet of the electric heater obtains the high-temperature medium required by the process. The internal control system of the electric heater automatically adjusts the output power of the electric heater based on the temperature sensor signal at the outlet, ensuring uniform temperature of the medium at the outlet. When the heating element overheats, the independent overheat protection device immediately cuts off the heating power supply, preventing the heated material from overheating, which could cause coking, deterioration, carbonization, or even damage to the heating element, effectively extending the service life of the electric heater.
Application Scope
Typical applications of fluid explosion-proof electric heaters mainly include:
1. Heating chemical materials in the chemical industry, drying certain powders under specific pressure, chemical processes, and spray drying.
2. Heating hydrocarbons, including crude oil, heavy oil, fuel oil, thermal oil, lubricating oil, paraffin, etc.
3. Heating process water, superheated steam, molten salt, nitrogen (air), water gas, and other fluids that require heating.
4. Due to the advanced explosion-proof structure, the equipment can be widely used in chemical, petroleum, natural gas, offshore platforms, ships, mining areas, and other places requiring explosion-proof measures.
Functional Features
Explosion-proof Electric Heater
Explosion-proof Electric Heater
1. Small size, high power: The heater mainly uses clustered tubular electric heating elements.
2. Fast thermal response, high temperature control accuracy, and high overall thermal efficiency.
3. High heating temperature: The maximum working temperature of the heater can reach 850°C.
4. Uniform outlet temperature of the medium, high temperature control accuracy.
5. Wide application range, strong adaptability: The heater can be used in explosion-proof or ordinary environments, with explosion-proof levels up to dⅡB and C, and pressure resistance up to 20MPa.
6. Long life, high reliability: The heater is made of special electric heating materials, with low surface power load design and multiple protections, greatly enhancing the safety and service life of the electric heater.
7. Fully automatic control: According to requirements, through the heater circuit design, automatic control of outlet temperature, flow, pressure, and other parameters can be easily achieved, and it can be networked with computers.
8. Significant energy-saving effect: Almost 100% of the electrical energy is transferred to the heating medium.
Converting electrical energy into thermal energy to heat objects is a form of electrical energy utilization. Compared with general fuel heating, electric heating can achieve higher temperatures (e.g., arc heating can reach temperatures above 3000°C), and it is easy to achieve automatic temperature control and remote control (e.g., car electric heating cups). It can maintain a certain temperature distribution of the heated object as needed. Electric heating can generate heat directly inside the heated object, thus having high thermal efficiency and fast heating speed. According to the heating process requirements, it can achieve uniform overall heating or local heating (including surface heating), and it is easy to achieve vacuum heating and controlled atmosphere heating. During the electric heating process, there is less waste gas, residue, and smoke, keeping the heated object clean and not polluting the environment. Therefore, electric heating is widely used in production, scientific research, and experiments. Especially in the manufacturing of single crystals and transistors, mechanical parts and surface hardening, ferroalloy smelting, and artificial graphite manufacturing, electric heating methods are adopted.
According to different methods of electrical energy conversion, electric heating is usually divided into resistance heating, induction heating, arc heating, electron beam heating, infrared heating, and dielectric heating.
Heating Methods Edit
Resistance Heating
Using the Joule effect of current to convert electrical energy into thermal energy to heat objects. It is usually divided into direct resistance heating and indirect resistance heating. In the former, the power supply voltage is directly applied to the object to be heated. When current flows, the object itself (e.g., electric ironing machine) generates heat. Objects that can be directly resistance heated must be conductors but have high resistivity. Since heat is generated inside the object itself, it is internal heating with high thermal efficiency. Indirect resistance heating requires special alloy materials or non-metallic materials to make heating elements, which generate heat and transfer it to the object to be heated through radiation, convection, and conduction. Since the object and the heating element are separate, the type of object is generally unrestricted, and operation is simple.
The materials used for heating elements in indirect resistance heating generally require high resistivity, low temperature coefficient of resistance, small deformation at high temperatures, and not easy to embrittle. Commonly used are metal materials such as iron-chromium-aluminum alloy and nickel-chromium alloy, and non-metallic materials such as silicon carbide and molybdenum disilicide. The maximum working temperature of metal heating elements can reach 1000-1500°C depending on the material; non-metallic heating elements can reach 1500-1700°C. The latter is easy to install and can be replaced while hot, but it requires a voltage regulation device during operation and has a shorter life than alloy heating elements. It is generally used in high-temperature furnaces, places where the temperature exceeds the maximum working temperature allowed for metal heating elements, and some special occasions.
