On the choice of configuration of electric heating of oil pipelines in ports
Due to the great distance between the port terminal and the tank farm at the rear, the pipeline is the artery connecting the vessel and the shore. According to the characteristics of crude oil, most oil pipelines in northern ports need heat preservation and heating to prevent clogging of pipelines.
In the early stage of the oil pipeline, hot water and steam were mainly used for heating and heat preservation. Depending on the diameter of the pipeline and the length of the transportation path, steel pipes of various thicknesses are selected to be attached to the crude oil pipeline, and the heat is monitored by hot water and steam. The thermal efficiency is low, and the phenomenon of "running, crackling, dripping and leaking" will occur, and there will be a large maintenance workload, energy waste, environmental damage and other disadvantages.
Electric heating is to use the heat generated by the electric heating products to compensate for heat losses by heating pipes and other process devices so that the appropriate temperature of the medium can be maintained within reasonable limits to meet the process requirements. Electric heating can directly convert electrical energy into thermal energy, has simple structure, convenient installation and maintenance, etc. D. It is widely used in petrochemical pipelines for heat preservation and heating.
The electric heating cable is installed between the insulation layer and the outer wall of the pipeline and uses electric heating to compensate for heat loss in the transportation and storage process, so that the transport pipeline can be maintained within a certain temperature range to achieve the goal of heating, heat preservation, and antifreeze. The two commonly used heating cables are constant power heating cables and self-controlled heating cables.
In accordance with the thermal losses of the pipeline, calculated by the electric heating insulation system, the equivalent heat generated by a certain specification and quantity of electric heating products is used for replacement and supplement; through the parameters of the pipeline, the working situation and the actual form of the pipeline laying on site. In combination with the characteristics of the electric heating cable, the configuration of the electric heating cable can be precisely selected.
Electric heating cable is a heating method that uses insulation resistance or resistance heating wire to create a temperature after power supply. It can automatically adjust the output temperature and reasonably maintain the process temperature requirements to keep warm, raise the temperature and protect the heating equipment from freezing. The insulation and antifreeze effect of the container is very good.
Transport of heavy oil through the pipeline over long distances and long-term retention in the pipeline will result in a drop in temperature due to heat dissipation and increased viscosity, which will cause the pipeline to be blocked by freezing or condensation-related accidents. Electric heating is widely used as effective insulation of pipelines and anti-freeze protection.
According to the statistics of the Hydrometeorological Center, the average daily minimum temperature at the location of the CNPC tank farm is 5 ° C, and the average daily maximum temperature is 14 ° C. Since the freezing point of the PX is about 15 °C, the supply pipeline needs heat preservation and heating. The oil depot has been in operation for many years without a stable source of steam, therefore, this project is considering the use of electric heating technology.
Long-distance crude oil pipelines with a high paraffin content with freezing temperatures above 50 °C. According to the requirements of the production plan of the plant, the volume of oil transportation through the pipeline is 150 thousand rubles. Tons per year, maximum-200 thousand. Tons per year.. According to the thermodynamic analysis of the pipeline, the initial supply temperature of the pipeline is 80 ° C (TN), and the temperature of the end entering the tank is 60 ° C (Tu). Since the transportation temperature needs to be adjusted according to the time of year, it sometimes needs to be transported by heat.
In petrochemical engineering, trunk infusion pipelines are the lifeblood of the factories. The temperature in the northern region is too low in winter and the pipeline needs to be insulated to compensate for the heat loss due to the low temperature in winter to ensure the normal operation of the pipeline.
The toughness of the asphalt is greatly affected by the temperature. When the temperature decreases, the toughness of the asphalt increases, and the drop in resistance of the asphalt during pipeline transportation increases; when the temperature falls below the freezing point, the asphalt solidifies, causing the pipeline to clog and the conveyor belt to come to trouble. Therefore, electric heating and heat preservation during the transportation of asphalt are very important.
To solve many problems in the "three high levels" crude oil extraction process, the thermal energy generated by the electric heating is used to heat the crude oil in the oil pipe throughout the process to improve the fluidity of the crude oil. Effectively solve various technical problems encountered in the operation of high-condensation, high-viscosity and high-paraffin crude oil, and achieve the goal of improving the productivity and efficiency of oil wells.