Research On The Preheating And Commissioning Process Of The South China Sea Submarine Pipeline

The preheating and commissioning of the submarine pipeline is essentially a process of establishing the temperature field of the seawater around the medium and the pipeline.Mastering the temperature change in the process is important to ensure the safety of the pipeline,save the warm-up time,and reduce the preheating and production costs.In this study,a submarine pipeline in the South China Sea is taken as the research object.Based on the existing research,the mathematical model of the pipeline preheating and conmissioning is established.The influencing factors of the pipeline in the preheating and comissioning process are studied.The thermodynamics of preheating,reverse preheating and altermating forward and reverse preheating processes;the transient process of sea mud temperature field around the pipeline is discussed,and finally combined with sensitivity factor analysis and site conditions,feasible The program has carried out comparative research and has guiding significance for on-site production.(1)During the preheating process of the pipeline,the steady temperature of the outlet of the pipeline is affected by the flow rate of the preheated medium,the temperature and the physical parameters of the sea mud.The influence of the temperature of the preheating medium on the stable temperature of the outlet is the most obvious.Temperature,lower flow preheating production plan;(2)The research on the alternating forward and reverse preheating process shows that the total preheating time is constant,the smaller the period of alternating positive and negative,the better the preheating effect of the pipeline;(3)Studying the transient proeess of the temperature field around the sea mud,it is known that for different seabed temperatures,the temperature of the sea tube and the surrounding sea mud temperature i5 finally different.The temperature differenee between the seabed temperature and the bottom temperature of the study area is greater,the temperature The longer the field is stable;(4)Combining the production conditions of the sea pipe,the analysis and research on several feasible preheating production plans shows that the preheating time is the shortest and the lowest the energy consumption when the preheating temperature is 76? and the flow rate is 0.6 n/s.When the preheating medium is used for Preheating in the forward and reverse directions,when the amount of preheating medium is 2.8 times of the tube capacity,the time and energy consumption are the lowest.The economic comparison of each scheme shows that the water temperature is 80°C and the flow rate is 0.54 m/s.It is economical to use alternating forward and reverse preheating.