Electric heating system for underground pipeline

Published on:

2022-09-22 15:54

Electric heating is widely used as effective pipe insulation and antifreeze. Its working principle is to dissipate a certain amount of heat through the heat transfer medium and make up for the losses of the heated pipe through direct or indirect heat exchange to meet normal operating requirements for temperature rise, heat preservation or antifreeze.

Since the insulation material of the overhead pipeline usually consists of a glass wool shell, the construction of the insulating material will be carried out on site after the completion of the pipeline construction, so the design of the winding and laying of the electric heating cable The overhead pipeline is very mature, and the pipelines requiring electric heating. Are installed in the pipeline of insulating material. It can be installed in accordance with the requirements of the electric heating installation before construction. In this case, because the ground temperature is higher than the air temperature, the underground pipeline can only meet the technological requirements by thermal insulation. However, when the transmission process environment is relatively special, and the underground pipeline also needs electric heating, electric heating is required Special design for laying and construction methods.

Take as an example an oil depot in Yulin, Shaanxi Province. Oil from the third line of the tank farm has low density, low viscosity, high freezing point and high paraffin deposition temperature. In winter, Yulin has a low temperature, and the average monthly minimum temperature is minus 15.8 ° C. In addition to the normal process of entering and exiting the tanks, the warehouse has a large number of periodically operating pipelines. Given that the pipeline is shut down for a long time, the oil product will drop to the paraffin drop point or even below the freezing point in the winter, and condensation will occur, causing difficulties in re-starting, so the process pipeline needs to adopt a heating design. Most of the process pipelines in the warehouse are laid on the ground, but since crude oil is transported from the storage tank to the external pump room, the fire road in the area of the tank is separated in the middle, and the pipeline from the tank to the pump room is partially buried, so it needs to be buried. The electric heating cable of the ground pipeline is used for heating and heat preservation.

Electric heating system generally consists of electric heating cables, connecting boxes, cable fittings, junction boxes, control and control components, etc. D.

When installing underground electric heating cables, it should be borne in mind that the underground insulation layer has a good thermal insulation effect; the outer protective layer of the underground insulation layer should have good waterproof performance; the electrical heating cable junction box should be installed on the ground.

When designing the underground electric heating cable system, we can study the method of laying the ultra-long-distance electric heating cable and reserve space for the electric heating cable to pass through the pipe outside the pipeline to be kept warm. A small steel tube sleeve (electric heating cable cutting pipe) is added on the outside of the working steel pipe, temporarily fixed with galvanized iron wire, and then filled with polyurethane foam between the outer protective pipe and the working steel pipe. The reserved in the insulation layer is aligned to the average drop, and the electric heating cable is laid along the reserved tube through the tube, and the junction box of the head end and tail end is installed at both ends of the inlet and outlet of the ground.

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