Measures for electric heating and thermal insulation of fire extinguishing pipelines in road tunnels
With the development of my country's economy, a large number of tunnels have been built and put into operation in cold regions. In cold regions, the ambient temperature in winter is often below the freezing point, which is fraught with freeze-thaw cycles, frost damage, cracks in the walls of tunnels, water seeping and freezing, water freezing in fire pipes. Among them, the freezing of fire water seriously threatens the fire safety of the tunnels. In order to ensure the normal operation of the tunnel fire protection system, it is necessary to optimize the insulation structure design of the fire protection pipeline to ensure that there is no fire water freezing, which is a key point in the design of the tunnel fire protection. Tunnels in cold regions.
There are now many ways of not freezing pipelines, and the electric heating insulation layer is more popular in the northern region.
The electric heating system is an additional electric heating system. The electric heating system of fire extinguishing pipelines is widely used and can be customized to control the temperature, has a certain energy-saving effect, and has a high degree of commercialization. The water in the common fire main stagnates. The heating cable is located between the insulation and the pipe wall. In the process of transferring heat from the wall of the fire water pipe to the external environment, it needs to overcome the thermal resistance of the thermal conductivity of the insulating layer and the thermal resistance to convective heat transfer between the outer wall of the insulating layer and the ambient air.
In the fire protection system of road tunnels in cold regions, it is imperative to take measures of active thermal insulation and anti-freeze protection. This can effectively solve the problem that the fire pipe network is prone to freezing and failure, And effectively ensure the normal use of the fire water supply system in the period of low temperatures in winter is of great importance and safety has a role.
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.