The problem of paraffin wax deposition from waxy feedstocks is of longstanding in oil processing industry and continues to attract research scientists and engineers. It is of particular importance in transportation of crude oil through pipelines with major difficulties arising during restarting after shut down and in subsequent processing in equipment such as heat exchangers. Informations and data which help to provide a better understanding of these problems, are, therefore of interest to designers and operators of process plants. The temperature gradient in hydrocarbon pipelines is probably the singlemost important factor in understanding these processes. The present paper attempts to analyse the effects of temperature gradient in paraffin wax deposition process and offers techniques/mathematical models to determine the temperature gradients in crude oil pipelines.
The thermal environment and temperature gradient of a hydrcarbon-carrying pipeline are of paramount importance in designing and operating the pipeline as these parameters largely control the crucial wax deposition process in crude pipelines. Worldwide the petroleum industry is particularly concerned with the wax deposition problem. According to an estimate in 1969, paraffin control in USA alone cost around $4.5 to $5 million per annum [Ref:6]. These were only direct costs that resulted from the periodic removal of accumulated crude paraffin by various mechanical, thermal and chemical means excluding production losses, increased horsepower requirements, wear or damage to equipment and manpower attention. This is primarily the reason for continuous attention by various researchers to this topic for more than seventy years and even now the basic approach to the problem is divergent and not fully understood. Nevertheless the thermal environment around a pipeline has a profound effect on the temperature distribution which in turn controls the carrying fluid properties [like density, viscosity and diffusivity to a great extent.
