PTQ Q2 2025 Issue

100

55.0

Heavy neutral lab analysis VI results Min VI specication

After Topsoe UCO

45.0

After Topsoe UCO

35.0

150 0 Heavy neutral base oil production days of stream 90 50 250 200 100

25.0

300

100

150

200

250

300

350

Heavy neutral production days of stream

Bright stock usually has a viscosity range of 32-36 cSt, heavy neutral between 10 and 12 cSt, light neutral around 5-6 cSt, and spindle oil is the lightest one having a viscos- ity between 3 and 4 cSt. Adding components with other favourable properties like high VI, high content of saturates, and low content of contaminants further boosts the quality of the base oils. From Figure 3, it can also be seen that the viscosity at 100°C of the UCO from the hydrocracker typically ranges from 3.5 to 5.5 cSt. This makes this type of material very suitable as a blending component for the light neutral base oil produced by the refinery. Origin of UCO co-processing need In the base oil complex furfural extraction unit, the VI of base oil is adjusted through a solvent extraction process that removes poly aromatics with low VIs as extracts. Since there is no reaction mechanism involved and the VI is adjusted solely by the physical solvent extraction process, the VI value of the base oil product relies heavily on the paraffin and aromatic content of the feedstock derived from crude oil. The diverse composition of crude oil in the base oil complex poses a challenge in meeting VI requirements, especially in heavy neutral mode. The solvent extraction process attains a higher VI value for base oil when processing more paraffinic crude oils. However, these paraffinic crude oils are less economical, making it difficult to achieve the desired VI for heavy neutral base oil when using crude oils with lower paraffinic content. To address this issue and increase the flexibility of crude oil variability, the addition of high VI UCO from the hydrocracker is incorporated into the furfural extraction unit feedstock. Consequently, UCO is continuously co-processed in heavy neutral mode primarily to enhance VI, but also to improve the yield of heavy neutral base oil. Given that the viscosity interval of UCO is similar to light neutral base oil, UCO can also be processed in light neutral mode to enhance yields. However, due to the high viscosity of the UCO compared to spindle oil and low viscosity compared to bright stock, UCO cannot be processed in these modes. Since UCO is primarily processed to enhance the VI, its VI is an essential parameter, as it indicates paraffinic content. Consequently, a higher VI of UCO will lead to an increased VI value in heavy Figure 4 VI of heavy neutral before and after introduction of UCO from hydrocracker loaded with Topsoe catalyst

neutral base oil. This improvement enables greater yield enhancement and allows for the processing of crude oil with lower paraffinic content. Figure 4 illustrates the VI values of heavy neutral prod- uct tanks, comparing data collected before and after the implementation of the new UCO processing. The results show that the proportion of production tanks with off-spec VI values decreased from 70% to 18% after the new UCO processing was applied. Additionally, an increase in yield of approximately 6% was observed post-implementation, as depicted in Figure 5 , while maintaining adherence to pro- duction specifications. In light neutral mode, there are no issues related to VI; therefore, UCO is processed in the furfural extraction unit feed primarily to enhance product yield. Additionally, since the viscosity interval of UCO is very close to the light neutral viscosity interval, there is no upper limit for UCO processing in light neutral mode. Consequently, the UCO processing rate is maximised in light neutral mode due to UCO storage and production amounts, as well as the light distillate storage management of the refinery. Figure 6 shows the light raffinate (normal feed for light neu - tral production) yields data before and after implementing the new UCO processing. The data indicates that the high par- affinic content of the new UCO has led to an increase in light raffinate yield by approximately 10% (4%-points). The high VI value of the new UCO allows for an improved VI of heavy neutral base oil, thereby providing a margin to process more cost-effective crude oils with low paraffinic content. Prior to the introduction of the new UCO, the refinery required crude oil types with a minimum paraffin content of 40-45% to produce on-spec base oil. However, based on two separate test runs, it has been demonstrated that on-spec base oil can be produced in all modes (heavy neutral, light neutral, bright stock, and spindle oil) using different crude oil compositions with a paraffin content as low as 35-40% range. Therefore, the reduction of 7% in the minimum requirement for crude oil paraffin content offers significant economic benefits in terms of crude oil costs and provides considerable flexibility in crude oil selection. Figure 7 illustrates that test runs with 7% lower paraffin content in crude oil have resulted in high heavy raffinate yields compared to the yields before the addition of the UCO. Figure 5 Heavy raffinate yield (%) before and after introduc - tion of UCO from hydrocracker loaded with Topsoe catalyst

PTQ Q2 2025