K Model: The future of blending (RI 2023)

In a refinery operation, the profitability margin is increased when heavy crude fractions are blended with light crude without affecting processability.

Rajeev Kumar, Ravi Kumar Voolapalli, Pranab Kumar Rakshit and Aniruddha Kulkarni
Bharat Petroleum Corporation Ltd

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Article Summary

However, heavy oils with high asphaltene content can cause issues with the desalter operation, such as the formation of strong water emulsions with asphaltene, fouling in heat exchangers, and coking during processing. These issues can lead to excess fuel firing and loss of the advantages of purchasing heavy crudes. Thus, accurate prediction of crude compatibility can be a robust tool for refinery operators to use before starting any process.

Current benchmark processes to determine the compatibility of crude oils are done experimentally and take at least a few weeks to complete. Existing lab tests are limited to checking the compatibility of only two crude oil blends at a time. To check three or more crude oils, they need to test the compatibility of the first two and then mix the two with the third and subsequent ones, which is an exhaustive and time-consuming process.

K Model is a quick and accurate method for crude oil blend compatibility and optimisation. It was developed by coefficients obtained from regression analysis between the ratios of physical parameters in known crude oils and composite compatibility measures determined from multiple compatibility test results on the known crude oils. Several compatibility tests are used in the process, including colloidal instability index (CII), colloidal stability index (CSI), Stankiewicz plot (SP), qualitative-quantitative analysis (QQA), stability cross plot (SCP), Heithaus parameter (or parameter P), Heptane Dilution (HD), toluene equivalence (TE), spot test, and oil compatibility model (OCM).

K Model requires only a few physical parameters of the crude oil as input for optimisation, such as sulphur, carbon residue, api, and kinematic viscosity.

A web-based version of K Model has been developed, which runs over the internet and predicts results rapidly. This enables the user to arrive at an optimum blend based on economics, availability, and processing feasibility in real-time. It promotes the simultaneous evaluation of multiple crude mix options in quick time and helps the user to make more informed decisions. The K Model software package offers different modules that provide a variety of options to meet refinery blending needs. It consists of three modules:
• Module 1 is for crude oil blend compatibility and has two sub-modules. Module 1A predicts crude blend compatibility for known blend compositions. Module 1B predicts the optimal and compatible crude oil blend that can be achieved using a set of crude oils. K Model provides the option for blend optimisation of up to 10 crude oils, considering different blending constraints such as blend compatibility, viscosity, pour, acidity, nitrogen, sulphur, overall distillate yield, and crude oil availability.
• Module 2 is for identifying the bitumen potential of blends. Like Module 1, Module 2 also has two sub-modules. Module 2A checks whether bitumen potential is present for a given crude oil blend composition. Module 2B estimates  the optimum blend composition of crude oils with bitumen potential.
• Module 3 is for fuel oil blending, which gives the user a tool to optimise the cutter stock and minimise the cost of production for a fuel oil of certain desired specifications. Overall, the software integrates a leading web-based blending solution with a user-friendly GUI.

Refiners can use this product in several ways, such as feeding a healthy diet to the refinery to maintain equipment health, ensure smooth operation, save energy, and keep taking good care of the environment by reducing carbon footprint. K Model has the capability to significantly contribute to the world at large if refineries adhere to minimising asphaltene precipitation. With ‘K Model: Blending for future’, a new dimension is added to the entire oil sourcing process.

This short article originally appeared in the 2023Refining India Newspaper, which you can VIEW HERE

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