As global decarbonisation gains momentum, many steel manufacturers are transitioning to the direct reduction iron (DRI) process to achieve greener and more sustainable production, reducing CO2 emissions by as much as 90% compared to the blast furnace method. However, while the environmental benefits of green steel production are clear, the switch to DRI and electric arc furnace (EAF) processes involves significant capital expenditure costs. Manufacturers exploring greenfield project developments or modernisation of their existing sites must, therefore, be able to make a case for achieving a fast return on investment (ROI) and ensure the economic viability of transitioning to a more sustainable method of production. To expedite their ROI, manufacturers need to reduce project risk, get production online quickly, and optimise their processes to ensure that their plant operates as safely and efficiently as possible.
The implementation of automation technology is essential to the safe and efficient operation of a DRI process, with advanced digital solutions helping to reduce operating costs, improve worker safety, increase sustainability and productivity, and provide faster ROI. Distributed control systems, energy management information systems and asset management systems, based on intelligent measurement and control technologies, provide the critical information that helps to simplify maintenance, troubleshooting and operation.
A greenfield project presents an opportunity for the plant to be ‘born digital’ and immediately benefit from the implementation of digital technologies such as intelligent sensors and control technologies, advanced operations software and systems, cloud data management and analytics. Implementing these technologies from the outset will help to future-proof the facility and support long-term operational excellence but can also impact project schedules. It is therefore vital that project stakeholders place automation front and centre as early as possible during the front-end engineering and design phase.
Accurate and reliable measurements
The implementation of advanced technologies to provide extremely accurate and reliable measurements is fundamental to optimising the performance of a digitally-enabled, smarter and more sustainable steel plant. An EAF, for example, requires instrumentation that can deliver accuracy and reliability in various measurement applications. These include measuring the level of the liquid steel in the furnace, temperature measurement across the EAF, and detecting cooling water leaks.
Furnace level is an extremely challenging measurement because it requires a device that can operate reliably in extremely high temperatures and cope with rapid changes in level and the presence of dust and gases in the vapour space. A solution is provided by the latest non-contacting radar level transmitters, such as the Rosemount™ 5408 from Emerson. When installed inside a cooling box with nitrogen purging, these transmitters mitigate the effects of both the process and ambient temperatures on the device.
Conditions such as vibration, moisture and heat make it challenging to measure EAF temperature. This harsh environment frequently results in wired connection failures that can lead to large measurement errors, safety risks and costly unscheduled shutdowns. To meet this challenge, manufacturers can install the latest wireless temperature transmitters, which eliminate cable and conduit damage, leading to better temperature control, reduced maintenance costs and shorter batch times.
Cooling water leaks can significantly decrease furnace performance and efficiency, and have the potential to damage key equipment, so it is vital to detect leaks in a timely manner. Fast and reliable leak detection requires the implementation of extremely accurate flow meters. Rosemount E-Series magnetic flow meters from Emerson deliver industry-leading performance, providing cooling water measurement accuracy to 0.15% at target flow rates. This enables faster and more reliable leak detection, and improved furnace performance.
The standardisation of measurement devices – or the use of multivariable instruments, with the same model for different types of measurements, such as differential pressure, flow or level – provides a range of benefits. It helps to reduce costs, engineering and service efforts during all project design phases, and reduces installation complexity, process interventions, potential leakage points and safety issues. Non-intrusive measurement devices can be deployed to mitigate these types of problems, and the use of industrial wireless networks and sensors can dramatically lower installation time and costs compared to wired alternatives.
Optimising process control and safety
To make their plants as safe and efficient as possible from start-up, green steel manufacturers must ensure that processes are operating at their optimal point, which requires excellent process control. The benefits of process optimisation can include increased equipment availability and throughput, and significant reductions in energy costs and product quality variation. DRI is a hybrid chemical process and therefore more like a chemical plant than a traditional blast furnace. An integrated control and safety system (ICSS) is the most suitable platform for such applications.
A modern, advanced ICSS provides the high performance required for the complexity of the DRI process, while its versatility, flexibility and speed enable optimal plant operation. An ICSS simplifies hardware requirements and logic programming, and significantly reduces the complexity of future engineering modifications and testing.
Control valves also play a critical role in optimising the efficiency of the DRI process, by making it possible to selectively lead the coke oven gas, fuel gas, steam, combustion air and flue gases according to the stage of the operating cycle, as well as operating the closed-circuit water system. However, a range of severe service and variable process conditions – including cavitation, abrasion, high environmental noise, high temperature and high pressure drops – make DRI a challenging application for valves. Selecting valves that operate reliably despite these conditions is therefore a key consideration. Automation suppliers can provide control valves with trims that mitigate cavitation and prevent critical asset failure; avoid trim and valve body erosion; reduce environmental noise and control pressure and temperature reduction.
DRI and EAF processes generate various toxic and combustible gases that contain carbon monoxide and hydrogen, which creates obvious safety and environmental risks. It is therefore vital for organisations to ensure that reliable gas detection systems and ventilation systems are in place. Automation technology suppliers provide wired and wireless point gas detection, open path gas detection and ultrasonic gas leak detection solutions to support green steel producers. These gas detection safety solutions are designed to continuously monitor and detect gas leaks before they lead to harmful conditions, helping to keep personnel and sites safer.
Optimising asset performance and reliability
Ensuring that essential plant assets are operating at optimum levels as often as possible requires the swift and efficient rectification of any issues that arise, before they lead to costly repairs or replacements, or create safety risks. Traditionally, checks on the health and performance of critical equipment and devices in a green steel plant have been made during manual inspection rounds. The longer the gap between these inspections, the more likely that a defect would go undetected and result in an unexpected failure, significantly impacting production, product quality and plant efficiency.
However, many plants are now switching to fully automated asset monitoring, to digitally transform their maintenance planning and reduce their costs through the early diagnosis and analysis of developing issues. Edge analytics devices, such as the AMS Asset Monitor from Emerson, digitalise essential asset data and analytics for better operational performance and improved decision-making. These devices combine easy deployment, embedded logic-based analytics and intuitive health scoring to simplify the monitoring and maintenance of essential assets. Their analytics and visualisation can help plant personnel to effectively plan maintenance during scheduled shutdowns and turnarounds, and to minimise or eliminate unplanned downtime, thereby reducing costs.
Better planning, communication and collaboration
The specifics of each green steel project may be unique, but they all face common concerns about keeping within budget and completing on time. Such large, complex projects can require the involvement of multiple owners, engineering contractors and suppliers from different parts of the world, which can create challenges when it comes to planning, communication and collaboration.
To meet these challenges, cloud-based engineering environments can help to engage resources and expertise regardless of location. For example, Emerson has developed Remote Virtual Office (RVO) – a cost-efficient, rapidly-deployed and secure distributed engineering solution that allows worldwide project team members to communicate, collaborate and contribute remotely in a virtual engineering and testing environment. Stakeholders can access files, discussions, updates, tools and applications, and contribute their specific knowledge to the ongoing project. This provides many benefits, including being able to remotely review prototypes to ensure compliance with specifications, and to engage operations personnel early in remote (virtual) factory acceptance tests of the automation equipment.
Reducing engineering time
The actionable data provided by digital ecosystems helps green steel manufacturers to minimise costs, increase energy efficiency and accelerate time to market. However, the task of wiring and connecting all this technology can be significant and directly impacts project timelines.
The design, documentation and installation of input/output (I/O) and marshalling can be especially labour-intensive and time-consuming, and often falls on the critical path of green steel projects. Because I/O hardware and software – bound by traditional marshalling – are so tightly integrated during design, development, testing and commissioning, simple I/O changes can cause major project delays. However, an innovative technology known as electronic marshalling with characterisation modules (CHARMs), removes the complexity of marshalling field wires. CHARMs enable field wiring of any signal type to be terminated in any location. This gives design teams the flexibility to add I/O on demand anywhere in the plant, wherever and whenever it is needed.
Smart commissioning accelerates project timelines
Green steel projects can be delayed by traditional automation system commissioning practices, which involve sequential tasks and manual processes. These include wiring verification, binding, device configuration, loop testing and creating documentation. To make device commissioning faster and easier, and help accelerate project timelines, automation vendors now provide smart commissioning, which reduces trips to the field, eliminates tasks and enables late project changes to be accommodated.
Modern distributed control systems and device management software incorporate functionality that enables improved device binding configuration, testing and documentation, resulting in a device being commissioned in minutes rather than days, thereby shaving weeks off project schedules. Smart commissioning eliminates potential errors by automatically finding and identifying all smart devices, before binding them to the configuration. To further accelerate implementation, the device configuration is pushed to all devices based on pre-configured templates. Testing is easily and safely done from the control room by using digital communication, with no personnel required in the field for confirmation. The use of smart commissioning tools can help manufacturers reduce project engineering hours by up to 40%, reduce instrumentation and control project schedules by as much as 25%, and lower total installed costs by up to 40%.
Digital twins drive operational excellence and process improvements
Green steel manufacturing is one of many industries in which digital twin technology is proving to be a game-changer. A digital twin is a software-based virtual replica of the complete physical assets of a plant, including its control system, process equipment, instrumentation, operator displays and alarms. With this replica, the operation of these assets is modelled and simulated through their lifecycles.
A digital twin provides a highly accurate representation of the behaviour and dynamics of the process, making it an invaluable tool to analyse various ‘what if’ design scenarios. It can also validate optimised control and safety schemes, including advanced control models and start/stop procedures.
Running an exact digital replica in parallel with a live green steel plant also creates a valuable means of training control room operators and technicians, familiarising them with the control system and processes before start-up. Digital twins expose personnel to what they will experience in their actual control rooms, but in an offline and risk-free environment, thereby equipping them to successfully control any process upsets or abnormal situations that arise.
When the plant is operational, a digital twin can provide data and insight into equipment and system health, helping plant management to test and improve processes offline, optimise preventative maintenance practices and avoid costly unscheduled downtime. In addition, the accuracy of the digital twin can be constantly enhanced with data taken directly from the process as it becomes available.