pipe heat tracing
heat tracing system type
heat tracing system can be divided into two categories, electric and fluid. The fluid heat tracing system uses heating medium at high temperatures to transfer heat to the pipe. Fluid is usually contained in a tube or small tube connected to the tracked tube. If the steam is a heat-tracing fluid, condensed water will either return to the boiler or pour. If an organic heat transfer fluid is used, it is returned to heat exchanger for reheating and recirculation. Typically, heating of the heat-tracing fluid can be provided by combustion of waste heat of the process flow, fossil fuel, steam or electricity.
Electric heating tracing system converts electrical energy into heat and transfers it to the pipe and its fluids. Most commercial electric heating systems currently used are resistive and are in the form of cables placed on the pipes. When current flows through the resistive element, the heat generated is proportional to the square of the current and the resistance of the element to the current flow. Other dedicated electrical heat tracing systems use impedance , induction and skin conduction effects to generate and transfer heat.
Effective steam tracing
Steam tracing is to apply steam heat to pipes and containers to maintain the required process temperature, antifreeze, viscosity control or obtain temperature control points in the fluid to allow it to chemically interact in the process.
Steam heating is usually done by running a steam line in direct contact with the pipe or container to be heated.
Steam heat tracing requirements
Steam heat tracing working principle is very simple. When the product in the pipe is higher than the air around it, heat will be transferred from the product to the air around it through the pipe wall.
This heat loss will cause the product's temperature to drop. Pipe insulation will significantly reduce the heat loss rate, but unfortunately, no insulation is 100% effective.
Steam is a very effective heat carrier with a fixed relationship between its pressure and temperature. It can transport heat for a long distance and release heat at a constant temperature.
To compensate for the lost heat in the product pipeline, small-diameter steam pipes or tracer are connected to the product line. The heat generated by the steam enters the product line and replaces the lost heat. The heat transferred, as well as the product temperature, can be easily controlled through a simple self-acting control system. The same type of control can also be used in winterized applications, allowing steam to enter the hotline only when the ambient temperature is below a predetermined level.
In order to find the leaking part, the insulation layer of the pipe hundreds of meters must be removed. The cost is huge and it is also related to scaffolding. So keep this in mind and make sure the steam tracing is installed correctly.
Steam heat tracing type
Jacket - For super critical applications, the product temperature must always be maintained at a higher temperature. The use of a steam jacket also allows for quick preheating of the pipe.
Key - Here, steam tracing is used to maintain the temperature of the product, which will cure or deteriorate if its temperature is below a predetermined level.
non-critical - Tracking is used to maintain product viscosity at optimal pumping levels.
Winter - Make sure the pipeline will not be damaged due to freezing in severe weather conditions.
Instrument -Small diameter steam heat tracing pipe, usually 10 mm, is used to protect flowmeter , control valve , sampling station, pulse pipeline, etc.
Determine tracer requirements
To select the size and quantity of steam heating tracing pipelines required for a specific application, the heat loss rate of the product pipeline under the worst design conditions must be determined.
This heat loss rate depends on the difference between product temperature and ambient temperature. Other factors such as the thermal conductivity of the insulation, ambient wind speed and emissivity of the insulated surface will affect this loss rate.
Size and length
The most common steam heat tracing diameters are 3/8 inch (9.52 mm) and 1/2 inch (12.7 mm) outer diameter copper tube or stainless steel tube . The 5/8-inch (15.88 mm) and 3/4-inch (19.05 mm) outer diameter tubes were used; however, this would require a greater cost. The 3/8-inch pipe is more likely to be clogged with sediment and/or debris, so it is less frequently used. Copper is the first choice for its heat transfer properties, while stainless steels show better tolerance in corrosive environments.
Advantages of steam heating tracing compared to other methods
Although the advantages of each method can be argued, the following table shows the relative advantages and disadvantages of each system.
As energy costs continue to rise, one of the key areas that factories need to focus on is the reliability and energy efficiency of trace systems. The high available heat content of steam provides many benefits compared to using hot fluids for heat tracing and is much more efficient than electrical heat tracing.
Since steam is mainly composed of water, it has little impact on the environment when it leaks into the atmosphere. It is estimated that cleaning up a liter of glycol leak can cost as much as $5,000.00. This cost includes cleaning, reporting and documentation required in case of leaks on an industrial site. Steam is inherently safe, making it a practical choice for most industrial applications where ignition sources must be minimized.
For these reasons, in most industrial and process applications, the use of steam heat tracing remains the first choice for temperature maintenance.
