The Working Principle and Construction of Pipeline Electric Heat Insulation

Pipeline heat tracing insulation is a new type of heating system. It can also be called the heating cable low-temperature heat tracing system. It is realized by converting electric energy into heat energy. What is its principle? How to construct it? These are the problems we need to solve, so Xiao Bian has collected some knowledge about this from the Internet, hoping to give readers some help and guidance, as described below.

1. How it works

The purpose of pipe insulation and frost protection is to compensate for the heat loss caused by the temperature difference between the inside and outside of the pipe shell. In order to achieve the purpose of preventing freezing and heat insulation of the pipeline, it is only necessary to provide the heat lost to the pipeline, and to maintain the heat balance of the fluid in the pipeline, it can maintain its temperature basically unchanged. Heating cable insulation and anti-freeze system is to provide heat lost to the pipeline to maintain its temperature is basically unchanged.

The pipeline electric heat tracing system consists of three parts: the heating cable power supply system, the pipeline anti-freezing cable electric heating system and the pipeline electric heat tracing intelligent control alarm system. Each heat tracing cable unit includes a temperature controller, a temperature sensor, an air switch, an AC over-limit alarm isolation transmission, a heat tracing cable disconnection monitor, a working status display, a fault buzzing alarm, and a transformer, etc., for observation and control. Adjust the electric heating work situation. In working conditions, the temperature sensor is placed on the heated pipe and the temperature can be measured at any time. The temperature controller compares the temperature measured by the temperature sensor with the temperature set in advance, and isolates the transmission through the air switch in the heating cable control box and the AC current over-limit alarm, and cuts off and turns on the power in time to achieve the heating antifreeze. purpose.

2. Construction

Construction mainly includes preparatory work and installation.

(1) Preparation before construction

Before installation, you must first check the design drawings and confirm that the heating cables and accessories are fully equipped and consistent with the design. After the pipeline system is installed and the acceptance is completed, the accessories such as pipelines and valves have been installed, and the pressure test and acceptance are completed according to the relevant installation specifications. The rust-proof layer and the anticorrosive coating on the outside of the pipeline are completely dried and thoroughly dried. Check the outer surface of the pipe to confirm that there are no burrs or sharp corners, so as to avoid damage to the cable during installation. A cable bushing is reserved for the wall through the pipeline. The location and number of the bushings are determined based on the number of cables passing through the location. Check whether the installation position of the control box meets the design requirements. Coordinate with other professions to ensure that there is no conflict with other professions in the installation process.

(2) Installation

Start the installation from the power connection point, the cable end should be thrown at the connection power supply (no power first), and the cable between the pipeline and the power supply should be connected with a metal hose. The two heating cables are placed along the pipeline in a straight line, and the horizontal pipeline is placed at an angle of 120 degrees on both sides of the pipeline. The vertical pipeline is placed on the symmetrical sides of the pipeline and fixed with an aluminum foil tape every 3 to 50 cm. If the heating cable cannot be placed under the pipe, place the cable on both sides or upper end of the pipe but increase the winding factor appropriately. Measure the resistance value of each electric heating cable before placing the heating cable. Measure the resistance value again after placing the cable. After ensuring that there is no mistake, use aluminum foil tape to wrap the heat-generating cable and pipe tightly to ensure that the cable and the pipe surface are in close contact.

When the heating cable is placed, no dead knot or dead bending phenomenon can occur. When the hole is pierced and the pipe is worn, the sheath of the electric heating cable cannot be damaged. Heating cables must not be placed on sharp edges of pipes. Do not step on heating cables and protect them. The minimum bending radius for laying the heating cable is 5 times the wire diameter, and no cross contact and overlap phenomenon can occur. The minimum spacing between the two wires is 6 cm. Partially wound heating cable should not be too much, so as not to overheat the pipe and burn the heating cable. If more windings are necessary, insulation thickness should be appropriately reduced.

Temperature sensors and monitoring probes shall be placed at the lowest point of the pipe top temperature, close to the outer wall of the pipe to be measured, fixed with aluminum foil tape and away from the heating cable, and away from the heating element by more than 1m. Shield copper wire. In order to ensure that the temperature of the pipeline heating trace is accurate, the temperature sensor probe must be calibrated and then installed on the site with a special instrument. The probe should be installed in a more concealed location to avoid damage. The temperature sensor and the monitoring sensor should be placed in the insulation layer, and the connection line should be connected with the metal hose when penetrating the pipeline to be inspected.