Study on the thermal characteristics of crude oil batch pipelining with differential outlet temperature and inconstant flow rate

When several kinds of crude oil need to be transported, the batch pipelining is a better choice than the single-pipeline-single-oil and blending pipelining due to its advantages. In the batch pipelining process, to avoid the frequent operations on the pumps and control valves, the flow rate is generally inconstant in practice. All previous studies simplify the flow rate distribution as a constant one, which largely deviates from the engineering practice. Focused on this point, based on the features of the batch pipelining in practice, the gradient-type flow rate distribution model and corresponding calculation approach are proposed in this paper. The accuracy of this model and corresponding calculation approach are verified by the field data, and it indicates that the accuracy of numerical results can meet the engineering requirement. Further, the thermal characteristics of the batch pipelining are found by numerical simulation and the further analysis is carried out to make these characteristics more convincing. Finally, the shortcoming of the step-type flow rate distribution with simple expression is pointed out. It is found that the adoption of the step-type flow rate distribution in the simulation would introduce a prominent deviation when the change period of flow rate is relatively long. To overcome this shortcoming, the proposed gradient-type flow rate distribution, whose accuracy is higher, is an alternative method.