Atmospheric and vacuum towers for the combined GK-3/1 unit. Revamping at Ukrtatnafta Co.

Abstract

The GK-3 combined crude refining plant was developed at Giprogrozneft’. It includes the following blocks: crude atmospheric distillation, atmospheric resid vacuum distillation, vacuum gasoil cat cracker, secondary distillation of naphtha. The atmospheric and vacuum blocks in the GK-3/1 plant were revamped at Ukrtatnafta Co. in 2004 according to the plan for its development. The following were defined as the basic problems: • ensuring a range of stable and effective operation within the limits of 60-100% of the nominal; • improving the quality of separation, increasing takeoff of vacuum gasoil as feedstock for the cat cracker; • decreasing the content of cuts under 360°C in atmospheric resid and under 500°C in vacuum resid. To solve these problems, the internals in the atmospheric and vacuum towers had to be replaced and the necessary check calculations of the existing equipment had to be performed: furnaces, transfer lines, heat-exchange and condensation equipment. The results of the study showed that the housings of atmospheric K-2 and stripping K-3/1-4 towers had to be replaced since their lifetime had expired. In revamping, the new K-2 tower had to be installed on the existing foundation while preserving the upper-level product removal and circulating reflux stream marks if possible. In addition, the process scheme and equipment in the existing plant had to be retained to the maximum. Kedr-89 Co. performed the process calculations for the atmospheric and vacuum blocks, developed designs for the new atmospheric and vacuum towers, and prepared the initial data for the revamping detail design. The detail design was developed by Ukrneftekhimproekt Co. (Kiev). The following work was done: • the optimum heat-exchange circuit was developed with consideration of use of only existing heatexchange equipment; • check calculations of the transfer pipeline in the K-2 atmospheric tower were performed and calculations for the strength of this pipeline and determination of the optimum design with consideration of obstructions in the existing area and existing structural supports were conducted; Chemistry and Technology of Fuels and Oils, Vol. 42, No.5, 2006