Increasing demand for LNG has led to some regasification terminals in Europe importing and managing much larger volumes than usual. However, when plants are operated above their nominal capacity, this increases safety risks in what is already a hazardous environment. Organizations must therefore find ways of increasing the operational efficiency of their assets, to optimize capacity whilst still ensuring that safety is never compromised.
In an article in LNG Industry magazine, ‘Increasing terminal capacity’, Rosa Medina, sales manager for energy with Emerson’s Automation Solutions business, explains how the application of a broad range of advanced digital automation technologies is helping to meet this challenge. This includes plant-wide digital ecosystems – such as Emerson’s Plantweb™ – that incorporate advanced systems and software, intelligent control technologies, and intelligent field devices. Rosa says:
…Automation systems and software with modelling and analytics tools create high integrity data to enable informed decisions and optimise performance. New sensing and measurement technologies eliminate blind spots previously out of reach or not contemplated, increasing visualisation of the health and performance of equipment and processes, while intelligent control devices are responsive and provide more precise control to maximise process performance.
Rosa examines some of these digital automation solutions in detail, and begins by explaining the need for effective inventory and supply chain management. She says:
…An inability to efficiently track cargoes, adjust schedules, and maximise jetty utilisation against inventory demand fluctuations can impact the profitability of a regasification facility by as much as 5%. However, many facilities are still operating without an integrated terminal management system to plan and manage loading and unloading operations and provide visibility and management of the terminal’s inventory and commercial activity.
Rosa describes how the latest terminal information management systems (TIMS) help to optimize terminal operations and supply chain management performance by keeping track of stored volumes, measuring mass/energy balance, and calculating total send-out flow rate. TIMS can integrate with inventory management software, which collects level, temperature, density and pressure measurements to provide a complete overview of individual storage tanks and enable organizations to optimize their usage.
Rosa next describes the importance of optimizing the performance of boil-off gas (BOG) compressors and how this can be achieved by integrating advanced process control (APC) software within a distributed control system. She explains:
…APC software solutions help to increase capacity by co-ordinating setpoints for the multiple process variables that are key to BOG compressor performance, safely and efficiently driving them to the desired values. This can dramatically reduce process variability, allowing optimal control performance across multiple compressor trains while operating closer to process constraints and limits, resulting in fewer compressor trips and less flaring. Using the software’s embedded optimiser feature, throughput can be automatically increased and units operated at peak profitability, while emissions can be reduced.
The article explains how APC software also enables organizations to achieve significant benefits by implementing multi-variable model predictive control (MPC) strategies. MPC uses dynamic process models and/or historical data to predict how a plant will behave in the future. These predictions are then used to determine an optimum sequence of control actions.
Rosa then looks at how the latest tank gauging systems – incorporating advanced non-contacting radar level gauges and powerful inventory management software – help to maximize storage capacity and increase safety by enabling precise and reliable measurements of the liquid level inside LNG tanks. The article states:
…Measuring the level of LNG in storage tanks is challenging, with large tanks of over 40 m making accuracy difficult to achieve. Because tanks are not opened during operation, this means instruments are not accessible for maintenance, thus requiring the technology to be extremely reliable, and redundant level measurements to be provided. The latest advanced non-contacting radar level gauges deliver outstanding measurement accuracy and reliability at distances of over 55 m. A specific antenna enables them to function in the extreme environment of LNG tanks, while a design that includes no moving parts helps achieve a mean time between failures measured in decades.
Heat exchange fouling is a problem at LNG regasification terminals, as it can result in poor energy efficiency, unit under-utilization, reduced throughput, or even a shutdown for cleaning. It is therefore important to implement a predictive maintenance strategy supported by a range of digital solutions that enable the collection and analysis of asset health data. Rosa explains:
…Automated condition monitoring enables heat exchangers to be monitored remotely 24/7, so that any issues can be identified earlier and maintenance tasks scheduled and performed well before an operator alarm is triggered. This not only increases the efficiency of the heat exchangers but also reduces costs, as performing scheduled maintenance is usually significantly less costly than unscheduled maintenance.
The article describes how the latest asset performance software can aggregate data from a range of advanced sensing technologies to create a holistic picture of asset health. The software translates equipment health data into a user-friendly format, and instantly and securely delivers it to relevant personnel, wherever they are located. This enables better and faster decision-making that will improve operational performance and maintenance efficiency. In addition, by using embedded communications protocols, the data can be shared with machine learning and analytics software. Rosa says:
…This enables users to identify abnormal situations and inefficiencies, and track the health of the equipment to make predictions about future outcomes. This can then lead to the creation of new strategies for improved asset management, reliability, and operational efficiency.
Safety is of paramount importance at LNG regasification terminals, and to help reduce risk it is vital to implement valve and actuator technology that provides tight shut-off and low leakage rates. The article explains the importance of protecting against BOG compressor surge, to prevent catastrophic damage that would severely impact availability and capacity. Rosa states:
…Anti-surge control valve assemblies are designed specifically for these demanding low-temperature applications, and include control valves, actuators, and digital valve controllers. The technology detects when a surge state is approaching and acts to move the operating point away from surge. This decreases plenum pressure and increases the flow through the compressor, resulting in stable operating conditions.
For more, visit Emerson’s portfolio of advanced solutions for LNG regasification plants.