Process optimisation and control with reliable multiphase measurement

Not all refineries are the same and as such, the challenges with blending crude feedstocks vary between facilities.  Fluctuation in crude supply can be beneficial, however, it can also bring significant operational challenges during the desalting process that can have an impact further downstream into other parts of the distillation unit. Tracerco provides a total solution in process analysis and optimisation by creating ingenious ways to measure the difficult-to-measure, offering insights which empower operators to make better informed decisions, be safer and more productive.

Crude Blending

Opportunity crudes are becoming a more attractive option for refiners looking to improve flexibility, operating margins, increase distillate yields or convert high sulphur fuel into diesel and gasoline: but they are not without their difficulties.  Whether it be oil sands, shale or condensate, higher TAN (Total Acid Number) or increased levels of elemental impurities and contaminants such as waxes, solids, iron and vanadium, all these characteristics can lead to processing issues.  The efficient removal of these impurities along with salts and water (BS&W) from crude feedstock is imperative to maintain reliable operations, prevent unplanned shutdowns and outages, and reduce corrosion and fouling.

Foremost of these challenges is to monitor and manage the position and quality of process fluids, including emulsion. Whether the process involves inline or intermediate blending, the use of accurate and reliable level or interface control devices (LIC) in the desalter can reduce and in some cases eliminate process problems.

Reliable Control

Introducing these crude blends creates some variable processing conditions with respect to instrumentation and control, so it is important by design that devices can reliably manage fluctuations.  There are several technologies that can be employed for level and interface control that look at differential pressure, volume percentage of water or electro-magnetic pulses for example. Changes in operating conditions such as temperature, pressure or even the type of feedstock can also affect the accuracy and reliability of these devices.  Being able to monitor and adapt to these variable conditions can optimise separation to improve feedstock flexibility.

Not being able to accurately control the interface is a common occurrence. By providing a high-resolution measurement around the oil/water interface layer, the tendency or lack of control leading to incursions of conductive process fluids to the electrostatic grids and overdosing of chemicals such as demulsifiers is reduced.  This enables refiners to reduce costs associated with unplanned trips or upsets, ensure the correct amount of chemical dosing, all while enhancing safety. There are also associated environmental benefits from having accurate control over process interfaces with respect to brine or effluent discharge and recirculation as part of wash water recharge.  By visualising and monitoring the water level position, it is possible to reduce hydrocarbon carry under or oil in water (OiW), which reduces demand on filtration and chemical treatment, improving operational efficiency and environmental compliance of the wastewater treatment plant.

The Tracerco Profiler^TM

The Tracerco Profiler™ typically comprises of a two or three dip pipe assembly, installed into a vessel through a single nozzle.  A narrow dip pipe holds a chain of low energy gamma sources, while the remaining dip pipe(s) hold an array of gamma detectors. Typically, each source is directed using a collimating rod onto two detectors above and below the plane of the source.  This collimation reduces the number of low energy gamma sources used, stops radiation in all directions except that of the detector.  This creates a continuous measurement range by directing each radiation beam up or down.

Measuring density change in this way allows for the most efficient operating conditions to be maintained, as well as monitoring the effectiveness of chemical additive and mud washing regimes.  With repeatable, accurate and reliable real-time process measurements, the Profiler™ provides the confidence to correctly control operating levels, enhancing separation.

Case Example

In the months subsequent to the installation of a Tracerco Profiler™ on a first stage desalter, a number of key and measurable benefits were realised that enhanced the unit’s performance and reliability.  Due to the industry leading vertical resolution of 30mm, the client’s confidence in the interface level was increased. This led to optimising the interface for maximum wash water contact, reducing emulsion breaker chemical dosing by 50%.  In relation to their crude quality, the refiner noted a 44% reduction in BS&W and an improvement in the Salt Removal Efficiency (SRE) of the unit with a reduction in chlorides by 50%.

To learn more about Tracerco’s advanced range of nucleonic instrumentation, visit https://www.tracerco.com/products/nucleonic-instrumentation/ or download our Augmented Reality app from the respective app store on both Apple and Android devices.