Benefit Analysis of Using Heat Tracing
Most of the process pipelines and tank containers in China use traditional steam or hot water heat tracing. Electric heat tracing uses electrical energy to supplement the heat lost by the heated body during the process, thereby maintaining the most reasonable process temperature of the flowing medium. It is a high-tech product. Electric heat tracing provides uniform heat release along the length of the pipeline or over the large area of the tank volume, unlike electric heating that concentrates heat load at a single point or small area. Electric heat tracing has a small temperature gradient, long thermal stability time, and is suitable for long-term use. The 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 the ability to achieve remote control and automatic control. It is the technological development direction to replace steam and hot water heat tracing and is a key energy-saving project promoted by the state.
Principle of Heat Tracing
When the electric heating tape is connected to the power supply (note that the core wires at the end must not be connected), current flows from one core wire through the conductive PTC material to the other core wire, forming a circuit. The electrical energy heats the conductive material, and its resistance increases accordingly. When the temperature of the core tape rises to a certain value, the resistance becomes so large that it almost blocks the current, and the temperature no longer rises. At the same time, the electric heating tape transfers heat to the lower-temperature heated system. The power of the electric heating tape is mainly controlled by the heat transfer process, and the output power is automatically adjusted according to the temperature of the heated system, while traditional constant-power heaters do not have this function.
Advantages of Electric Heat Tracing
Compared with steam (hot water) heat tracing, electric heat tracing has many advantages as follows:
(1) The electric heat tracing device is simple, with uniform heating and accurate temperature control. It can be remotely controlled and automated.
(2) Electric heat tracing has explosion-proof and all-weather performance, high reliability, and long service life.
(3) Electric heat tracing has no leakage, which is beneficial to environmental protection.
(4) Saves steel: It does not require the two-way heat tracing pipelines needed for steam heat tracing.
(5) Saves insulation materials.
(6) Saves water resources, unlike boilers that require large amounts of water daily.
(7) Electric heat tracing can also solve problems that are difficult to solve with steam and hot water heat tracing.
(8) Electric heat tracing requires less design work, is convenient and simple to install, and has low maintenance workload.
(9) High efficiency, can significantly reduce energy consumption.
Whether it is one-time investment or annual operating cost, electric heat tracing tape is more economical than steam heat tracing tape. For some projects, the one-time investment of electric heat tracing tape may be slightly higher than that of steam or hot water heat tracing, but in terms of annual operating cost, the savings from electric heat tracing usually recover the investment within 1-2 years.
Benefit Analysis of Using Heat Tracing
Self-regulating electric heat tracing adjusts its heat output according to the temperature of the sensitive pipe wall (medium), which is an energy-saving measure. The most widely used self-regulating electric heat tracing tape consumes 15W per meter. For a pipeline with a total length of 1000m, the hourly power consumption is 1000×15/1000=15KW.h. When the pipeline temperature reaches the upper limit of the maintenance temperature, the heat output of the electric heat tracing will gradually decrease, and the output power will also decrease accordingly. Thus, the power consumption of electric heat tracing is generally 60% of the rated power. Assuming the plant electricity price is 0.60 yuan/KW.h and the operation period is 100 days (2400 hours), the annual normal electricity cost is: (15×2400)×0.60×60%=12960 yuan. When self-regulating electric heat tracing tape is used with a temperature controller, it can not only accurately maintain the medium temperature of the pipeline or heated body but also greatly reduce operating costs.Constant-power electric heat tracing tape has a constant heat output per unit length. The longer the tape used, the greater the total output power. The most widely used constant-power electric heat tracing tape consumes 20W per meter. For a pipeline with a total length of 1000m, the hourly power consumption is 1000×20/1000=20KW.h. When the pipeline temperature reaches the upper limit of the maintenance temperature, the output power stabilizes, and the power consumption of the electric heat tracing remains constant. Assuming the plant electricity price is 0.60 yuan/KW.h and the operation period is 100 days (2400 hours), the annual normal electricity cost is: (20×2400)×0.60=28800 yuan. When constant-power electric heat tracing tape is used with a temperature controller, it can also accurately maintain the medium temperature of the pipeline or heated body.
Service Life of Electric Heating Tape
With proper maintenance, the service life of the electric heat tracing system is 8 years or longer.
Application Scope of Electric Heat Tracing Products
Electric heat tracing products can be widely used for heat tracing, insulation, anti-freezing, and anti-condensation of pipelines, pump bodies, valves, tanks, and tank containers in industries such as petroleum, chemical, electric power, medicine, machinery, food, and shipping. They are the most advanced and effective method for maintaining process temperature in liquid pipelines and storage tanks. Electric heat tracing is not only suitable for all places where steam heat tracing is used but can also solve problems that are difficult to solve with steam heat tracing, such as heat tracing of long-distance pipelines, heat tracing in narrow spaces, heat tracing of irregularly shaped equipment (such as pumps), heat tracing of pipelines and equipment without steam heat source or in remote areas, and heat tracing of plastic and non-metallic pipelines.
Classification of Common Electric Heat Tracing
Common electric heat tracing can be divided into the following types according to different pipelines (tanks):
1. Self-limiting (self-regulating) electric heating tape: This tape has a resistance that increases with temperature, causing power to decrease. Due to the large starting current, the length used generally does not exceed 100 meters. The tape can be cut arbitrarily, and no matter how long it is, it will generate heat when connected to the rated voltage.
2. Parallel electric heating tape: This tape uses two (or three) parallel insulated copper stranded wires as power busbars. The PTC characteristic heating wire is wound around a skeleton, and at each heating section length, it is alternately connected to the busbars, forming a continuous parallel resistance. The length of this tape is about 10-800 meters.
3. Series electric heating tape: This tape uses three parallel insulated copper stranded wires of the same cross-sectional area and a certain length as the power busbars and heating core wires. One end is reliably short-circuited, and the other end is connected to a 380V (or designed voltage) power supply, forming a star load. According to Joule-Lenz law: Q=0.24IRT, electrical energy is converted into thermal energy, and the star load continuously releases heat, forming a continuous, uniformly heating electric heat tracing tape. According to actual needs, the three phases (single phase) of the electric heat tracing tape can be separated (split type) or integrated into one. This tape cannot be too short; generally, the length used is about 500-2500 meters.
4. High-temperature electric heating tape: This tape is made of glass fiber or other high-temperature resistant materials, with a temperature resistance within 300°C and a length of 1-50 meters (since it cannot be cut arbitrarily, professional manufacturers need to be consulted for design).
5. Silicone rubber electric heating tape: This tape can be used for heating, heat tracing, and insulation of industrial equipment or laboratory pipe boxes, tanks, and oil drums (tanks) in humid, non-explosive gas environments. The length of the tape is 1-15 meters (since it cannot be cut arbitrarily, professional manufacturers need to be consulted for design).
6. MI cable: This tape is composed of a metal core (heating element), tightly surrounded by mineral magnesium oxide (insulation layer) and a metal tube (usually copper, steel, or stainless steel) that has been drawn multiple times. The continuous working temperature can reach 250-590°C, and the short-term working temperature can reach 1083°C. The length is 18-680 meters (since it cannot be cut arbitrarily, professional manufacturers need to be consulted for design).
