A method selection of residual product processing, especially that of vacuum residuum, becomes more and more important recently but creates a serious technical and economic challenge for every refinery.
One of possible approaches to this issue is an hydrocracking and hydrodesulfurization process of vacuum residue - Vacuum Residue Upgrading (VRU). This paper shows some aspects concerning stability of products received from the process when processing vacuum residue derived from Ural crude oil. Taking proper corrective measures in the process itself and respective product preparation we succeeded to improve product stability caused by specific chemical composition of vacuum residue received from Ural crude oil.
The radical constrains referred to environment protection regulations and the resulting limits for harmful substances emissions have brought the violent increase of quality requirements for fuels produced in petroleum refineries, during the last 10 years. It concerns the motor fuels and fuel oils.
The necessity of substantial emissions decrease from power stations has forced the direct impact on fuels structure change. Heavy fuel oils are gradually replaced with light oils and fuel gas. The growth of demand for middle distillates is observed in result of these changes (motor fuel oils and light fuel oils). In parallel the low sulphur fuels are required. The very rigorous requirements for low sulphur residue fuel oils are difficult to fulfil and strongly influence the whole crude oil processing scheme and residue oils disposal The one problem solution may be the residue oil hydrocracking and hydrodesulphurisation. In this process the desulphurised residue oil and motor fuel distillates are obtained. The product properties depend on process conditions and conversion.
In commercial scale two types of residue hydrocracking processes are used.
The seventh Vacuum Residue Upgrading Plant was started up in PKN Orlen SA refinery, in Plock, Poland, in 1999. The Unit is processing vacuum residue from Russian Ural crude oil. 2 VRU process Process of VRU with ebullated-bed reactor was invented in the mid-1960's to overcome problems characteristic experienced by fixed-bed processes when processing heavy or dirty feedstocks.
Ebullated-bed reactors have the unique characteristics of an operation type and a fluidised bed of catalyst. This results in the ability to handle reaction exotherms, solids containing feedstocks and for providing a flexible operation for changing feedstocks and operating objectives.
The typical operating conditions for the VRU Process are shown in Table 1. It is a high pressure, high temperature process. The lowest operating temperatures utilised are approximately those used at the fixed-bed EOR conditions. The operating pressure