Process Control Engineering - BP Kwinana Refinery - Case Study Example

Process Control Engineering Name: University: Date: Process Control Engineering - BP Kwinana Refinery Introduction The objective of the process control systems is monitoring the production environment as well as controlling the manufacturing or process flow electronically according to the different set-points offered by the user. Basically, process control is utilised expansively in food and beverage, electrical generation, chemical processing as well as oil refining industries whereby product creation is rooted in a nonstop processes’ series. These systems characteristically handle analogue meters and sensors signals which commonly are broadcasted to specialised computers that facilitate continuous the adjusting and control of fluid flow, pressure and temperature. Some examples of process control engineering include the programmable logic controller (PLC), which is a acomputerised control system utilised in industries to continuously monitor the condition of input devices and to control the condition of the output devices. Another example of process control engineering is distributed control system (DCS), which is an automated control system which includes control elements that are geographically distributed over the control area or plant. Real-time optimizers are also considered to be process control engineering that handles methods of maximising the company’s economic goal associated with the continuous process operation. As mentioned by Souza, Darci, and Zanin (2010), the majority of real-time optimizers systems are anchored in process system’ non-linear steady state models, integrated with parameter estimation or data reconciliation to bring key parameters, like feed efficiencies and compositions up to date. Advanced regulatory control is another example of process control engineering; it incorporates knowledge of process objectives, constraints, disturbances, and dynamics with the aim of increasing the processing capacity as well as efficiency. Model predictive control is a process control technique applied widely for controlling large-scale installations, which normally are depicted by large-scale models with dynamics that are relatively slow. The objective of this paper is to give in-depth details on the programmable logic controller with the view to BP Kwinana oil refinery. BP Kwinana Oil Refinery Overview The BP Kwinana oil refinery is located in Perth, Western Australia and normally refines approximately 137,000 barrels of crude oil daily. The refinery is Australia’s largest crude oil refinery and offers fuel requirements for the majority of Western Australians and across Australia. BP Kwinana is considered as one of the most contemporary refinery in the Southern Hemisphere after major upgrades and investments. Given that the refining technology is continuously improving, BP Kwinana has implemented numerous process control systems that have led to cleaner fuel production. Process Modelling For Control At BP Kwinana, programmable logic controllers (PLCs) are utilised in different control applications. The process modelling for control in various refineries and manufacturing companies involves relay ladder logic (RLL), which is a well-known PLCs’ programming language. A mentioned by Moon (1994), at any time RLL errors could be included over the cycles of software development; therefore, companies that utilise PLCs should verify RLL. Normally, the RLL verification process relies on manual tests anchored in the experience of the designer. Most oil refineries utilise simulators to test numerous scenarios. When the input variables augment, whereby the variables could be changed randomly, the scenarios tested increases rapidly. Moon (1994) asserts that the verification technique for model checking offers a rational solution to such a predicament. Given that the PLC programs are developed in numerous diverse forms, oil refineries utilise RLL to document the PLC programs. High-level programming languages such as Boolean, Function Chart as well as Grafcet can also be accessed for the development of PLC program development. Such PLC program representations could be converted into equal logical expressions. At BP Kwinana oil refinery, the programmable logic controller is utilised as a dedicated microprocessor which incessantly reads inputs as well as establishes new outputs in real-time. The PLC executes the scanning cycle repeatedly considering that one cycle involves three steps: the first step is reading and recording the sensors’ input values; the second step is the execution of the programmed logic a well as changing the internal bit table (where input values are recorded), and the last step involves writing new actuators’ outputs according to the bit table’s values. BP Kwinana ensures that the PLC remains an effective process controller by ensuring that scanning time must be less than this below the output or input signal’s shortest duration. Normally, the scanning times range between milliseconds and tenths of seconds, but as mentioned by Moon (1994), it depends on the speed of the processor, the length of the program, as well as the number of output and input devices. Most oil refineries understand that computer-aided verification is a crucial undertaking in a multifaceted embedded system. Therefore, the PLC system’s formal modelling for verification is a daunting undertaking. The model, on the one hand, has to be authentic with the system, and on the other hand, it must have an appropriate scale due to the state explosion verification problem. The espousal of PLC has enabled BP Kwinana to reduce machine downtime, and the controller has been designed in modular form, which facilitates the company to remove subassemblies easily for repair or replacement. Sensors and Instrumentation of Process Control Instrumentation at BP Kwinana includes a central processing unit (CPU), which is the main part of the PLC utilised for retrieving, decoding, storing, as well as processing information. In addition, the CPU is utilised to execute the control program that the PLC’s memory stores. Essentially, the CPU is considered to be PLC ‘brain’ and functions similarly to the CPU of a normal PC, apart from the fact that it utilises special coding and instructions to execute its functions. The PLC’s central processing unit has three parts: the power supply, the memory and the processor system. The power supply offers the PLC with the current and voltage needed to operate efficiently. The memory system stores the control data and program from the PLC’s connected equipment. The processor is involved in the coding, decoding, and computation of data. Aside from the CPU, the input/output (I/O) system is a PLC section where every device in the refinery is connected. In this case, the I/O system is what performs the control commands physically using the program that the PLC’s memory is storing. Basically, the I/O system can be divided into two parts: the I/O modules and the Rack. The former are the devices that have connection terminals whereby the wiring of field devices happens while the latter is an enclosure having slots which are connected to the CPU. Collectively, the I/O modules and rack create an interface between the PLC and the field devices and. In a proper setup, the I/O modules are wired securely to the corresponding field devices as well as installed securely in the rack’s slot. In consequence, a physical connection between the PLC and field devices is connected (Reddy, 2016). The field devices connected to the PLC is categorised into outputs and inputs. Outputs can be described as devices which wait for the PLC’s signal/data in order to carry out their control functions. Some examples of outputs utilised at BP Kwinana include a valve, lights, and motors. On the other hand, the inputs are considered to be devices supplying the signal/data into the PLC. Some examples of inputs at BP Kwinana include measurement devices, switches, as well as push buttons. The basic types of output and input devices are analogue devices and discrete devices. Analogue devices are outputs as well as inputs having an infinite number of states. Such devices are not just on and off, but could nearly be totally on or barely on, but not moderately off. In such devices, complex signals are sent and received to/from the PLC. The discrete devices, on the other hand, are outputs and inputs which have just two states: on and o􀀼. For that reason, only simple signals are sent or received to/from a PLC. Sensors are utilised as an input device which offers usable output following a particular physical input. For instance, BP Kwinana utilises thermocouple to facilitate the conversion of difference in temperature to an electrical output. Therefore, sensors can be considered as transducers since they convert a signal from one form to a physical form. Normally, sensors offer digital/discrete outputs and could be connected easily to the PLCs’ input ports. At BP Kwinana there are different forms of sensors; for instance, the pressure sensors are utilised to offer responses associated with the pressure. The company also uses the liquid level sensor, specifically for monitoring the liquid depth in the tank. Position/displacement sensors are utilised to offer a distance measurement between the target’s current location and a reference point. In this regard, the displacement sensor offers the measurement of the distance between the target present position as well as the previously recorded position. BP Kwinana normally utilises sensors so as to enable the PLC to have a sense of what is materialising inside the machine. In this case, when the actuator is pressed the switch senses and transmits an electrical signal to the programmable logic controller input. Sensors according to Hackworth and Hackworth (2004) could be classified as discrete and proportional, the former offers a single logical output while the latter offers an analogue output. Details of Unit Operations The PLC has enabled BP Kwinana and other oil and gas companies to optimise their operations and monitor various operations such as fluid flow. The PLC system has been beneficial since it is economical as evidenced by its smaller number of functional components. The PLC according to Cantrell (2014) is designed as well as engineered for durability, reliability and performance. At BP Kwinana, sequential fluid power systems used to experience unscheduled and costly shutdowns at different stages during their life cycle. In this case, PLC has enabled the fluid power systems to operate for a long duration with no manual supervision; thus, leading to improvements in flow control as well as refinery techniques. Besides that, PLC facilitates condition monitoring through utilisation of measurable parameters like fluid quality, flow rate and pressure with the aim of offering a valuable indication of how other systems are operating and providing a warning in case of a possible mechanical failure. The use of PLC to monitor the fluid power systems offers BP Kwinana the opportunity to easily monitor the fluid processes as well as detect an impending mechanical failure through actuators. Every time mechanical faults happen in the refinery machines, they normally manifest themselves at the actuator. The PLC can be utilised together with the logic proximity detectors states in identifying possible adverse symptoms of the actuator. Incorporating a simple light-emitting diode (LED) diagnostic display with the PLC has helped BP Kwinana to identify all detected adverse symptoms visually. As pointed out by Alem and Vankdoth (2016), PLC helps companies to ensure water sustainability through detection of the water level. PLC enable the BP Kwinana to safety safely produce quality products, through timely and effective control of liquid level. The Laws of Conservation of Mass and Energy According to the Law of Conservation of Mass, the matter during a chemical reaction can neither be created nor destroyed. While passing through processing operations, the material quantities can be considered as material balances. These balances are mass conservation statements. Equally, energy quantities could be considered as energy balances, which are energy conservation statements. At BP Kwinana, energy and material balances are extremely crucial since material balances allow the company to control refinery processing, especially in the control of the products’ yields. On the other hand, the energy balances are utilised in examining different process stages, over the entire production process. According to the law of conservation of mass and energy, the elements extracted by the society are returned ultimately to the land, water and air after their utilisation. Conclusion In conclusion, this paper has provided in-depth details regarding programmable logic controller with the view to BP Kwinana oil refinery. As mentioned in the piece, PLC has enabled BP Kwinana to monitor and control the refinery processes. PLC is valuable to many manufacturing companies because it improves the machine function or production lines and can also replicate and change the process or operation while gathering and conveying crucial information. References Alem, G., & Vankdoth, K. (2016). Fluid Level Control Using Programmable Logic Controller. International Research Journal of Engineering and Technology, 3(7), 2190-2196. Cantrell, W. (2014.). How industrial-grade, PC-based automation can drive oil and gas integrated operations. White Paper, Siemens, Illinois, United States. Hackworth, J. R., & Hackworth, F. D. (2004). Programmable Logic Controllers: Programming Methods and Applications. Upper Saddle River, New: Pearson/Prentice Hal. Moon, I. (1994). Modeling Programmable Logic Controllers for Logic Verification. IEEE control systems, 14(2), 53 - 59. Reddy, B. (2016, July 4). What is a Programmable Logic Controller. Retrieved from Instrumentation Tools: http://instrumentationtools.com/what-is-a-plc/ Souza, G. D., Darci, O., & Zanin, A. C. (2010). Real time optimization (RTO) with model predictive control (MPC). Computers and Chemical Engineering, 34, 1999–2006. Read More