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Source: electric heating manufacturers of: the number of shares Ampang electrical reading: 6052

Introduction to electric heat tracing

Introduction to electric heat tracing

Most of the heat tracing of process pipelines and tank containers in China adopts traditional steam or hot water heating. Electric heat tracing is to use the energy of electric heat to supplement the heat lost by the heat tracing body in the process, so as to maintain the most reasonable process temperature of the flowing medium. It is a high-tech product. Electric heat tracing is uniform heat radiation along the length of the pipeline or large area of the tank volume. It is different from electric heat tracing where the heat load is highly concentrated at a point or a small area; the temperature gradient of the electric heat tracing is small, and the thermal stabilization time is longer. Long, suitable for long-term use, the heat (electric power) required is much lower than electric heating. Electric heat tracing has the advantages of high thermal efficiency, energy saving, simple design, convenient construction and installation, no pollution, long service life, and can realize remote control and automatic control. It is a technology development direction that replaces steam and hot water heating, and is a national key promotion Energy saving project.

电伴热介绍

Electric heat tracing is an effective pipeline insulation and antifreeze solution, which has been widely used. The electric heat tracing has a small temperature gradient and a long thermal stabilization time, which is suitable for long-term use. Its required heat (electric power) is much lower than that of electric heating. Electric heat tracing has the advantages of high thermal efficiency, energy saving, simple design, convenient construction and installation, no pollution, long service life, and can realize remote control and automatic control. It is a technology development direction that replaces steam and hot water heating, and is a national key promotion Energy saving project. Its working principle is that it radiates a certain amount of heat through the heat tracing medium, and supplements the loss of the heat tracing pipe through direct or indirect heat exchange, so as to meet the normal working requirements of heating, insulation or antifreeze. Electric heat tracing is to use the energy of electric heat to supplement the heat lost by the heat tracing body in the process, so as to maintain the most reasonable process temperature of the flowing medium. It is a high-tech product. Electric heat tracing is uniform heat release along the length of the pipeline or large area of the tank volume. It is different from electric heating where the heat load is highly concentrated at a point or a small area.

Electric heat tracing principle

After the electric heating cable is connected to the power supply (note that the core at the tail end must not be connected), a current flows from one core through the conductive PTC material to the other core to form a loop. Electrical energy heats up the conductive material, and its resistance increases immediately. When the temperature of the core belt rises to a certain value, the resistance is so large that it almost blocks the current, and the temperature no longer increases. At the same time, the heating cable is heated to a lower temperature Heat transfer. The power of the electric heating cable is mainly controlled by the heat transfer process, and the output power is automatically adjusted according to the temperature of the heated system, but the traditional constant power heater does not have this function.

Electric heat tracing advantage

Compared with steam (hot water), electric heat tracing has many advantages as follows:

(1) The electric heat tracing device is simple, the heat is even, and the temperature is accurate. It can be controlled remotely and remotely to realize automatic management.
(2) The heat has explosion-proof, all-weather working performance, high reliability and long service life.
(3) There is no leakage of electric heat tracing, which is good for environmental protection.
(4) Saving steel: It does not require one or two trips of heat tracing pipes required by steam tracing.
(5) Save insulation materials.
(6) Save water resources, unlike boilers that need a lot of water every day.
(7) Electric heat tracing can also solve the difficult problems of steam and hot water tracing.
(8) The electrical heat tracing design has a small workload, convenient and simple construction, and small maintenance workload.
(9) High efficiency can greatly reduce energy consumption.

The one-time investment is still the annual operating cost. Electric heating cables can save more than steam heating. Some projects may have a one-time investment that is slightly higher than steam and hot water heating. However, based on annual operating costs, usually Electricity tracing operation saves the cost of 1-2 years and can recover the investment.

电伴热系统

Classification of electric heat tracing

电伴热带分类

Commonly used electric heat tracing can be divided into the following types for different pipes (tanks):

Self-limiting electric heating cable

As the temperature rises, the resistance of the heating cable decreases with the increase in temperature. Due to the large current at startup, the length of the heating cable is generally not more than 100 meters. The heating cable can be cut at will.

Parallel electric heating cable

Two (or three) parallel insulated copper stranded wires of this heating cable are used as power buses. PTC characteristic heating wires are wound on the skeleton. The length of every other heating node is alternately connected to the bus bar to form a continuous parallel resistance. About 10-800 meters.

Tandem electric heating cable

This heating cable uses three parallel insulated copper stranded wires of the same cross-sectional area and a certain length as the power bus and heating core wire. One end is reliably shorted, and the other end is connected to a 380V (or designed voltage) power supply to form one. Star load, according to the Joule-Lenz law: Q = 0.24IRT electric energy is converted into thermal energy. The star load continuously emits heat, forming a continuous, uniformly heating electric heating cable. According to the actual situation, the three phases (single phase) of the electric heating cable can be separated (separate) or integrated into one. The length of the heating cable used should not be too short, generally 500-2500 meters.

High temperature electric heating cable

This heating cable is made of glass fiber or other high temperature resistant materials, with a temperature resistance of 300 ° C and a length of 1-50 meters.

Silicone rubber heating belt

This heating belt can be used for industrial equipment or laboratory tube boxes, tanks and tanks in humid, non-explosive gas places, heating, heat tracing and insulation of oil barrels (tanks). The length of the heating belt is 1-15 meters.

MI heating cable

This heating cable is composed of a metal core (heating body), a mineral magnesium oxide (insulating layer) tightly surrounded by the core, and a metal pipe (usually copper, steel or stainless steel) which has been drawn many times. Continuous working temperature can reach 250-590 ℃, short-term working temperature can reach 1083 ℃, making the length 18-680 meters.

电伴热应用

Features of electric heat tracing products

1. Heat-tracing structure: conductive thermoplastic on the inner layer, double-layer flame-retardant polyolefin on the outer layer and a shielding layer
2. Temperature range: the maximum exposure temperature is 85 ℃, the maximum working temperature is 65 ± 5 ℃, and the minimum use temperature is -60 ℃
3. Construction temperature: Lowest: -5 ℃
4. Thermal stability: After cycling back and forth from 10 ℃ to 99 ℃ for 300 times, the heating value of the heating cable is maintained above 90%.
5. Bending radius: 25.4mm at 20 ° C and 35.0mm at -30 ° C
6. Insulation resistance: When the length of the heating cable is 100m and the ambient temperature is 20 ° C, shake with a 2,500VDC shaker for 1 minute. The minimum value of the insulation resistance (between the lead and the shield) is 20MΩ.
7. Starting current (10 ℃) 0.4A per meter
8. Please refer to some notes for installation and use
9. Maximum use length: not more than 100 meters