PTQ Q1 2023 Issue

Desalting chemistry and monitoring methods to help expand crude basket Widening the crude basket increases the challenges of maintaining asset reliability and plant performance, including formation of rag layers

Mahesh Subramaniyam, Debjit Chandra, Vivek Srinivasan, Ajay Gupta and Hiten Makwana Dorf Ketal Chemicals

G eopolitical tensions and economic pressures have increased the need for refiners to expand their crude basket. India is an excellent point of reference for this global trend, as crude oil production in India is only about one-fifth of the refinery capacity of 5 MMBPD. Data from India 1 comparing the top 10 oil exporters to India by country over the last three years demonstrate the speed and magnitude of change in crude supplies (see Figure 1 ). Russia and Brazil are new to the top 10 list, and imports from the US increased in 2021-2022. Although not in the top 10 of India, Canadian exports to Asia are now at record levels. This example of the dynamic nature of sources of crude in India is not unique. At the microeconomic level of a single refinery that can receive crude oils by ship, every refinery faces an increased pace of change in crude selection. The future of assigning carbon efficiency to each crude will fur - ther increase the complexity of crude selection, increasing the importance of crude flexibility. Widening the crude basket increases the challenges of maintaining asset reliability and plant performance. This article discusses Dorf Ketal's experience in supporting refiners with the management of change, including innova - tive monitoring methods and desalting chemistry to assist with the impact of solids and amine contamination that are a leading root cause of unsolved problems associated with the management of change in crude supply.

Refining challenges with changing crude supply Introducing new crudes in the blend requires a holis - tic approach towards measuring and mitigating the risk of change. The biggest challenge with new crudes is often seen in the tank farm and desalter, which eventu - ally becomes the bottleneck to the use of new crudes. Challenges include tank farm management, asphaltene precipitation, solids-induced rag layer, oil under-carry, amine carryover, increased water in desalted crude, brine circuit fouling, increased preheat fouling, increased slop formation, and downstream impact on waste water treat - ment plant (WWTP) and refinery process units. The challenges can be further classified by the source of the oil. Light sweet crudes from the US are highly paraffinic and often contain particulate iron, soluble iron, and tramp amines. Canadian oils often contain high solids, organic calcium, and are viscous and low API. Pre-salt crudes from Brazil introduce high salt and chloride loading and can reduce brine pH, increasing the risk of corrosion in the brine circuit. Generic solutions for improving salt removal and deal- ing with compatibility issues are well documented and not repeated here. However, these generic solutions have proven to be insufficient for:  Handling the challenges of solids contamination that often result in the formation of a rag layer at the oil-water

interface in the desalter.  Amine contamination.

30.34

22.87

22.76

20.36

12.3

11.32

10.93

8.97

8.59 7.94

6.03

4.89 4.84

3.6 3.42

3.31 2.64

2.47 2.23

2.14

Figure 1 Top ten oil exporters to India from 2019 to 2022

PTQ Q1 2023