A digital future for the LNG value creation chain

The global demand for LNG is skyrocketing. We need a way of bridging a supply gap of around 390 million tonnes a year by 2040. In response to this, a great many new natural gas liquefaction plants will be popping up over the coming years. Across the world, we will also witness the expansion of the value creation chains that follow this stage, from loading equipment and tankers to unloading terminals and regasification facilities. As things stand, around 80% of LNG tankers are equipped with R. STAHL's products. One of these products is R. STAHL's remote I/O systems.

Even though the number of LNG accidents has remained low in the past, incidents such as the Freeport blast in Texas, USA, and the Hammerfest fire in Norway highlight how crucial it is to have fully functioning safety equipment in LNG plants; it is also vital to do whatever is needed to minimise the risk of human error. When they are constructed, equipped and operated properly, the risks associated with LNG plants are as manageable as they are with any processing plant.

LNG, which consists predominantly of methane, is categorised as explosion group IIA and temperature class T1. Though it is less explosive than hydrogen (IIC), it is nonetheless important to take into account the explosion limits (LEL 4.4 vol%, UEL 17.0 vol%) and other characteristic values with an influence on safety. LNG plants must be powered using explosion-protected products, which are readily available. Suitable devices are also available for the purpose of process instrumentation and local operation. Ex-certified equipment can also be employed for lighting, monitoring and security purposes. R. STAHL has suitable, LNG-safe products for all such applications. Embracing automation and digital modernisation will be key for those who are seeking to make their installations future-ready – if you want to produce and transport LNG efficiently to keep your prices competitive, you will need maximum-efficiency plant automation.

Having operating and monitoring systems that are adapted for hazardous areas helps users to avoid errors. Modern HMI systems achieve this much more effectively than the pushbuttons and indicator lamps that were customary in the past. They clearly present the possible actions available to the user, thereby reducing the risk of human error. A number of new solutions have recently also been developed for security applications in hazardous areas. Cameras and CCTV equipment are increasingly being used in LNG production and liquefaction plants to prevent unauthorised activity.

Over the past few years, the digital modernisation sector has made significant progress. Remote I/O technology is now used for digital data transmission and has opened up a whole host of diagnostic possibilities. Additionally, it enables the latest automation concepts, such as NOA (NAMUR Open Architecture), to be realised. And with the development of Ethernet-APL, which will extend the reach of Ethernet in industrial environments to hazardous areas, LNG plants will be able to further capitalise on this technology.

Modern remote I/O systems additionally support structures of the kind developed by OPAF (Open Process Automation Forum) so that plants can be furnished with small-scale, localised intelligence. A few remote I/O systems are now able to work with modular plants that are configured using the MTP (Module Type Package) approach. These innovative concepts can even be implemented in equipment that is already in use, further boosting a plant's efficiency.

R. STAHL's Zone 1 remote I/O systems are designed to be used the world over. They possess the necessary certification for explosive gas and dust atmospheres – ATEX and IECEx, as well as FM for the USA and Canada, EAC for Russia, INMETRO for Brazil, PESO for India, KTL for Korea, etc. They also have approval from many bodies (DNV, LR, BV, ABS, CCS, KRS, ClassNK, PRS, RINA, RS, etc.) for the construction of both LNG tankers and ships powered by LNG using a fuel gas supply system (FGSS).

Remote I/O technology uses far fewer cabinets and much less cable than conventional installations. A typical installation, which previously needed 10 cabinets, now only needs two or three cabinets. Bus cables can cover large distances cost-effectively; the field devices are connected in the field via intelligent distributors. Depending on the installation, remote I/O technology can reduce capital expenditure by 25 to 47%. Faster production start-up coupled with higher availability thanks to integrated diagnostics and alerts can also reduce operating costs. It is hard to put a precise figure on this – when it comes to LNG plants, being able to avoid even a single shutdown is invaluable. Enhanced diagnostic capabilities also improve the process and product quality.

Having fewer cabinets and less wiring translates to significant weight savings. In a real project with around 1000 signals, the remote I/O installation allowed for a weight saving of over 80% – from 23-28 tonnes to just 3.8 tonnes – while still being able to implement redundancy and reserve concepts.

The weight savings and compact construction are also proving useful in fuel gas supply systems (FGSS) that power LNG tankers, and increasingly, other ships such as cruise ships. Ships often only have a few technical specialists on board. In conjunction with modern operating systems, remote I/O technology simplifies operation and trouble-shooting. It even allows remote access by external specialists.

Modern remote I/O solutions in Zone 1 support numerous protocols – starting with PROFIBUS DP, and more recently, PROFINET, EtherNet/IP, Modbus TCP, etc. Various OT/IT applications are feasible via the open diagnostics interface, and not just using HART, the grandfather of asset management protocols. Modern concepts using FDT/DTM or OPC UA, and in the future, FDI, can also be implemented. This way, particularly useful web server technologies can provide long-term trouble-shooting support.

The NOA concept mentioned earlier, which allows for a second channel for monitoring and optimisation domains, makes it easy to access additional diagnostic data without detrimentally affecting the main process. The UniversalAutomation.org concept is also relatively new. It works with the open ecoRT runtime (based on IEC 61499), opening up the otherwise closed control system world for I/O systems and package units that are able to communicate with the control system via open runtimes. If you delve into IEC 61499, you will quickly realise that the interoperability that renders the coupling and adaptation work unnecessary affords many benefits. R. STAHL is a founding member of UniversalAutomation.org and assists with promoting the technology.

OPA Forum members such as ExxonMobil have driven the development of other innovative automation structures. These automation structures enable small, intelligent I/O systems to communicate – these systems can be implemented using R. STAHL's remote I/O hardware in conjunction with control tools based on IEC 61499 and IEC 61131 (e.g. CoDeSys).

For many applications along the LNG value creation chain, modular plant concepts are used, in which pre-automated package units are incorporated into the overall plant structure. This works best using standardised MTP interfaces. And this, too, can be implemented using remote I/O technology, in conjunction with MTP libraries and, for example, an IEC 61131-based runtime. The result is exceptionally flexible digital modernisation platforms for the LNG value creation chain.

The networks sector now has technologies that unite explosion protection and innovation. For a long time now, Ethernet has been considered "THE " technology for universal networking across all process automation levels. There are a few solutions that will allow this technology to be used in hazardous areas, Ethernet-APL being the most innovative and the most interesting among them. It is supported by the four major fieldbus organisations PROFIBUS & PROFINET International, FieldComm Group, ODVA and the OPC Foundation, along with a great many control system, field device and explosion protection technology manufacturers.

While it would take too long to list all the details here,  the basic technical information for this technology includes an Ethernet transfer rate of 10 Mbit/s using a two-wire cable spanning distances of 1000 metres. This makes it suitable even for very large plants. It comes with integrated explosion protection and constitutes an intrinsically safe power supply to field devices in Zone 1. Ethernet-APL supports all Ethernet protocols, including PROFINET, EtherNet/IP, OPC UA and HART-IP.

This technology boasts integrated explosion protection. This explosion protection means that the field devices installed in Zone 1 have an intrinsically safe power supply, eliminating the need for a separate energy network. This reduces your costs. Furthermore, the Ethernet-APL field switches open up additional possibilities for the operator. They have a multitude of diagnostic functions, which make it incredibly easy to analyse the plant – both the physical layers and the networks – from a central location.