refining india 2023
Nuclear gauges and alternative level technologies in critical refinery applications
David Williams berthold
unexpected shutdowns, equipment dam- age, reduced throughput, and increased maintenance costs. All of these elements have the potential to lead to an increase in operational expenses.⁴ The time frame of a unit shutdown after a foam-over can vary depending on the severity of the foam-over. In extreme cases, it may be shut down for several weeks to physically clean the solidified foam in the overhead line, fractionator tower strainers, and other relevant components. The previ- ously mentioned expenses not only result in an increase in maintenance costs but also contribute to a decrease in the opera- tional availability of the delayed coking unit. In the event of a delayed coker shutdown, the refinery may need to decrease the total throughput to the crude distillation unit. Additionally, other units, such as the fluid- ised catalytic cracker and mild hydrocrack- ers, may also see reductions in their feed rates. This reduction in operational units can greatly reduce the operational margins of a refinery.⁵ Conclusion Nucleonic gauges, suitable for severe con- ditions, excel at monitoring levels in crucial applications. By incorporating these meas- uring devices, companies may improve operational effectiveness and safety cri- teria, eventually safeguarding valuable assets and ensuring the safety of individu- als. Nucleonic gauges emerge as a trusted ally in volatile environments with flammable or explosive materials, considerably lower- ing ignition hazards. Because of their unri- valled dependability, they are a favoured choice for safety shutdown systems. References 1 Edwards J E (2010). Select the Right Liquid Level Sensor – It’s important to con- sider a variety of factors when choosing the type of technology. Retrieved from https:// www.chemicalprocessing.com/processing- equipment/fluid-handling/article/11372865/ select-the-right-liquid-level-sensor 2 Difference between Invasive and Non-Invasive and Intrusive and Non-Invasive (2019, June 26). Instrumentation Tools: https://instrumenta- tiontools.com/difference-invasive-non-invasive- intrusive-non-intrusive/ 3 Kister H Z (2003). What caused tower malfunc- tions in the last 50 years? Trans IChemE , 81 (Part A), 62-72. doi: 10.1205/026387603321216941 4 Hart (2014) Sawarkar et al (2007). Petroleum Residue Upgrading via Delayed Coking: A Review, A N Sawarkar, A B Pandit, S D Samant, J B Joshi, The Canadian Journal of Chemical Engineering , Vol 85, Feb 2007. 5 Williams, Feldmann (2021, Sept). Increase reli- ability and profitability in delayed coking units Global refiners are always seeking new tech- niques to optimise their refinery assets with the purpose of maximising their profitability. Digital Refining . https://www.digitalrefining.com/arti- cle/1002656/increase-reliability-and-profitabil- ity-in-delayed-coking-units
Fundamentally, each level measur- ing technique comes with a unique set of advantages, but it also has built-in limita- tions. The ultimate choice is contingent upon the particular demands of the given application, prevailing environmental fac- tors, the properties of the fluid in question, and financial factors. Case studies One of the most common malfunctions iden- tified in a study by Kister³ was that tower failure was related to faulty level measure- ment or control, which caused excess base level and premature tower flooding. For instance, in one case, it describes a pro- pane deasphalting unit where the level con- troller failed, causing the tower to flood. The remedy was to install a nuclear level gauge and a redundant level control valve. Similarly, another case describes a crude distillation unit where the level transmitter did you know? nucleonic gauges, suitable for severe conditions, excel at monitoring levels in crucial applications failed, causing the tower to flood, exceed- ing the reboiler return. The remedy was to install a nuclear level gauge and a redun- dant level transmitter. This study highlights the importance of proper level measurement and control to prevent tower malfunctions. By learning from past malfunctions and implementing preventive measures, engineers and oper- ators can avoid falling into the same traps and ensure safe and efficient tower opera- tion. The study recommends installing bet- ter level measurement, primarily nuclear levels, and ensuring adequate level indica- tion to prevent excess base level and pre- mature tower flooding. By following these recommendations, operators can minimise the risk of tower malfunctions and ensure safe and efficient operation.³ The inaccuracies in the level measure- ment of the coke drums can exert a sub- stantial influence on both the quality of the product and the output of the delayed coker. The coking process facilitates the conversion of heavy residuum, leading to the generation of lighter and more economi- cally valuable gasoils. The optimisation of feed rate is dependent upon an accurate determination of the level, as it enables the maximisation of yields while simultaneously limiting the potential incidence of a drum foam-over. The foaming over of a drum in the delayed coking unit can have a substan- tial impact on the refinery’s overall profit- ability through numerous means, including
In order for important equipment in an oil refinery to function in a smooth and produc- tive manner, accurate level measurement is an essential component. Making sure that the readings are accurate not only improves the efficiency of the refining process but also keeps the workers, the equipment, and the environment safe. The desalter, the delayed coker, and the fluidised catalytic cracker are three units that greatly rely on this precision for a variety of reasons. The accurate and reliable measurement of lev- els in critical applications is paramount to ensuring not only the efficiency of indus- trial processes but also the safety of both personnel and the environment. The choice of appropriate technology for these meas- urements can directly influence the robust- ness of a system and, in many scenarios, the margin between successful operation and catastrophic failure. Within this con- text, nucleonic gauges have emerged as a frontrunner, boasting a degree of reliability unmatched by many other level measure- ment technologies. Refineries employ a combination of var- ious level measuring methods selected according to the particular needs of the application. Variables like the make-up of the process fluid, the environment, the required level of precision, and the cost of installing and maintaining the instruments frequently have an impact on the decision. The technique of measuring level using differential pressure (DP) is known for its versatility. The versatility of this technol- ogy extends from storage tanks to reactor vessels, supported by its extensive histori- cal background and well-known principles. Nevertheless, it is important to acknowl- edge that this approach has certain con- straints. For example, DP measurements might be susceptible to variations in fluid density or external air pressures. In the event that there are changes in the specific gravity of the fluid, it becomes necessary to perform recalibration in order to maintain the accuracy of measurements.¹ The utilisation of displacer level meas- urement provides a reliable and consistent method of measurement, even in scenar- ios where there are fluctuations in liquid densities. This characteristic makes it a very suitable option for accurately meas- uring interfaces or in circumstances where there are changes in liquid-specific grav- ity. One potential drawback is that, due to its mechanical composition, the system has movable components that may experience wear and tear over time, requiring periodic maintenance. The presence of very viscous liquids or slurries may impede the displac- er’s motion, potentially impacting the accu- racy of the measurement.¹ capacitance level measurement Capacitance level measurement is pre- ferred in situations where prioritising min- imal maintenance is crucial, especially owing to the absence of mechanical com-
ponents. Moreover, it demonstrates proficiency in managing a wide range of cir- cumstances, including specific substances with corrosive properties. Nonetheless, the reliance on a uniform dielectric constant of the medium in order to get precise meas- urements might pose a constraint. In addi- tion, the accumulation of probe residue may occasionally impact measurements, neces- sitating periodic maintenance.¹ Radar level monitoring Radar level monitoring is widely recognised for its non-contact characteristic, render- ing it highly suitable for substances that are volatile or prone to corrosion. The robust- ness of this technology, demonstrated by its capacity to maintain dependability when encountering various obstacles such as vapours, high temperatures, or fluctua- tions in liquid characteristics, reinforces its prominent role in several refinery oper- ations. However, occasionally, using tech- nology may come at a slightly higher cost compared to using alternative strategies. Moreover, intricate settings may require a process of calibration or tuning in order to guarantee precise measurements.¹ benefits of Nucleonic gauges Nucleonic gauges stand out in the domain of level measurement due to their non-intru- sive nature, making them ideal for high- temperature, high-pressure, or corrosive situations. Their non-invasive technique not only protects them from potential wear and corrosion but also assures an amazing level of stability unaffected by changes in the qualities of a substance. This non-contact technique of measuring also makes them resistant to changes in fluid parameters such as density and viscosity. A really non-contact device is charac- terised by its lack of interference and non- intrusiveness to the process. To illustrate the distinctions among non-intrusive, non- invasive, and non-contact, it should be noted that a non-invasive device does not disrupt the flow of a process fluid. While non-intrusive implies that the devices do not make direct contact with the process fluid, it can be either invasive or non-inva- sive.² Occasionally, the phrase ‘non-con- tact’ is employed to indicate that a device does not physically touch the process fluid. However, it should be noted that such instruments, like through air RADAR, none- theless intrude into the vessel. This unique ability assures constant and trustworthy readings even in changing pro- cess circumstances, removing the possible dangers associated with erroneous data. Precision is praised for these gauges, which promote predictable and consistent indus- trial processes. The lack of moving com- ponents, along with a non-contact mode of operation, results in low maintenance needs. Furthermore, their resistance to external disturbances such as foam or ves- sel internals emphasises their toughness.
Contact: david.williams@berthold-us.com
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