Prediction of the potential of light fractions and the concentration of sulfur in them

With the drop in processing volume and worsening of the component composition of oils and the increase in the quality requirements for petroleum products, it has become necessary to increase extraction of light fractions as a function of their potential concentration in oil by optimizing its refining. Mixtures of oils with different hydrocarbon composition, physicochemical properties, and potential total content of light fractions (up to 360~ are processed at YUKOS Co. plants. Important fluctuations in the quality of the oil delivered to the plants significantly affect refining processes, which does not allow operatively correcting production operations. As a result, withdrawal of lights from the potential decreases and the quality of the products obtained worsens. Studies of the physicochemical characteristics and refining process in the ARN-2 apparatus according to GOST 11011 were conducted in 1996 1997 for quality control and to increase the efficiency of utilization of the oils delivered to the Northeastern Scientific-Research Institute of the Petroleum Industry Corporation. Samples of petroleum mixtures were parallelly investigated in the plant laboratories. The precise characteristics of a fast method of determining the concentration of sulfur in them according to GOST 1437 were simultaneously checked. The samples were collected from four commercial registration points through which the oils entered the Kuibyshev, Syzran', and Novokuibyshev Refineries (the oils entered the last refinery by two streams: primarily western Siberian in one and Samara and Orenburg in the other). Withdrawal was conducted at each registration point according to GOST 2511. The commercial registration point is designed for automatic measurement and registration of several physical indexes of the oil: pressure, temperature, density, viscosity, etc., and for collection of a combined sample according to GOST 2511, executed according to a fixed algorithm in commercial operations between supplier and consumer. The method of investigation of the oils was based on the program in [ 1 ] approved in 1985 and recommended for all petroleum research laboratories. The instruments and methods provided by the program and the active GOSTs on methods of investigation of petroleum and petroleum products [2] and supplements to them were used in the study. A data base (Microsoft Access 97) on the quality of the petroleum mixtures and the fractions separated from them was created as a result of studying more than 150 samples. The quality of the petroleum mixtures delivered to the company's refineries in 1997 varied within wide limits, especially at the Novokuibyshev Refinery (see Fig. 1): The concentration of total light fractions varied from 44.2 to 66% and the concentration of sulfur varied from 0.69 to 2.76%. More stable raw material was delivered to the Kuibyshev and Syzran' Refineries: the concentration of light fractions was 47.7 58.4%; the concentration of sulfur was 0.91 -2%, and the Kuibyshev Refinery, best equipped for refining high-sulfur raw material, was supplied with lower-sulfur stock. The results of determining the concentration of light fractions in the petroleum by distillation on an ARN-2 apparatus are obtained on the second day (that is, when the petroleum had already been refined). For this reason, they can only be used for commercial registratiou, but not for optimizing the petroleum refining scheme. The data on the concentration of