Study on the thermal characteristics of crude oil pipeline during its consecutive process from shutdown to restart

Abstract

Based on the established physical and mathematical models for the thermal system coupled by crude oil, pipeline and soil, the thermal characteristics of crude oil pipeline during its consecutive process from shutdown to restart are investigated. Some conclusions obtained include that: the performance of temperature profile along the pipeline during shutdown needs more attention in contrast to the conventional sole concern on the inlet temperature. The thermal performance along the pipeline after restart has some significant features which contribute to the three regions division along the pipeline. The first region (Region I) is occupied by the hot oil and the temperature field of which is first established. The second region (Region II) is also occupied by the hot oil but is regarded as the transition region from the old temperature field formed during shutdown to the new steady temperature field after restart. The third region (Region III) is occupied by the cold oil which stays in the pipeline since shutdown. And the transient thermal performances for different regions after restart are given. Furthermore, two stages division on the transient thermal evolution is given based on different thermal performances and mechanisms. And the detailed information on the thermal characteristics in different stages is also presented.