Efficient technology needs effective
safety

The core process of liquefaction consumes a lot of energy. Powerful, explosion-protected motor actuators guarantee efficiency when compressing the natural gas and dissipating the heat via ventilators. In this respect, R. STAHL provides the CUBEx motor control units in a seawater-resistant Ex d enclosure, which is available in a range of control versions.

Explosion protected IS1+ remote I/O stations with intrinsically safe signal circuits are suitable for the compressor units in the LNG train, whose surroundings are classified as zone 1. 8- and 16-channel Ex i modules enable the stations to be positioned in a compact layout. This is particularly advantageous when considering the limited space available on Floating LNG (FLNG) plants. The IS1+ system is available with a seawater-resistant enclosure that offers protection against vibration and electromagnetic influences. It is therefore an ideal choice for maritime applications, as it complies with twelve different ship approvals, including DNV-GL, ABS and ClassNK, prove.

The compressors can also be equipped with explosion-protected control and distribution panels which are a combination of Ex d and Ex e type of protection. They can be equipped with indicator lamps, rotatory switches, push buttons and emergency stop buttons produced by R. STAHL.

Numerous pumps are used for a range of purposes in both LNG train and in upstream natural gas purification stages for a range of purposes. It includes the transport of absorption and washing solutions, as well as coolant for the heat exchangers. Explosion-protected controls can be custom designed, in a way that their dimensions are perfectly adapted for their performance and with a suitable control version for each application, they support in cost-effective liquefaction process. Depending on the requirements, they are equipped with transformers, main fuses and control fuses, as well as a range of control and monitoring equipment. R. STAHL Series 8220 standard motor control units are installed in Ex d enclosures and have an Ex e connection chamber enclosure. On the other hand, the motor control units in CUBEx Series 8264/5 are located entirely within the Ex d enclosure. Thanks to their robust construction design and tolerance to a wide temperature range, they are suitable for many partial processes in natural gas liquefaction.

Explosion protection must also be ensured for the filling arms. These flexible conduits are used to transport natural gas or LNG between the extraction site and the FLNG plant or between the LNG tanker and storage tanks at the unloading terminal. "Ship-to-shore" (STS) connections follow the movements of the ship. Among other requirements, the area within which the filling arm is operated must also comply with hazardous area regulations. The cabinet may be a built with a combination of two enclosures with the Ex e (increased safety degree of protection) and two enclosures with the Ex d (flameproof enclosure degree of protection). When operating multiple filling arms, a combination of a flameproof panel (Ex d) and a terminal box with the increased safety type of protection (Ex e), alongside multiple local Ex-protected operating terminals, is suitable.
Explosion-protected portable control devices can also be implemented. Wireless control systems are particularly convenient, for which the receiver is installed in a flameproof CUBEx enclosure on the hydraulic unit. In addition, a position monitoring system with a human-machine interface (HMI) can be installed. To do so, an explosion-protected enclosure with an integrated remote I/O system, which transmits its position data to the HMI, is installed on each arm.

Efficiency and explosion protection must come together in perfect harmony at every stage of LNG production process. Suitable process monitoring is therefore of high importance. Combining auxiliary contacts, miniature circuit breakers, residual current circuit breakers, load disconnect switches and safety switches with an Ex-protected remote I/O system enables access to the fault outputs from the pumps and power distribution boards via a distributed control system. For this purpose, R. STAHL provides IS1+ remote I/O solutions, which fulfils all requirements, including the strict demands for maritime applications as well as FLNG plants. The IS1+ system is certified for use in Zones 1 and 2. It provides data and diagnostics that can be used to improve the availability and efficiency of the plant without the risk of maintenance and servicing costs spiralling out of control. Depending on the requirements, the corresponding cabinets are equipped with displays or operating elements.

Reliable explosion protection is crucial for more than just automation and low-voltage technology. The standard and emergency lighting in hazardous areas must also comply with the necessary regulations in order to prevent explosions in the event that natural gas or heat carriers leak and escape the system, for instance at the pre-cooling stage. Ex-certified lighting technology from R. STAHL such as linear luminaires, tubular light fittings, floodlights and portable lamps make a perfect addition to a comprehensive system that guarantees maximum safety during the natural gas liquefaction process.

In this respect, digital lighting management using DALI is particularly important. Linear luminaires and emergency luminaires with an integrated DALI interface makes it easier to light up hazardous areas in purification and liquefaction plants in a way that is perfectly adapted to the task and the ambient brightness. This reduces energy consumption and extends the service life of the lighting. DALI communication is bidirectional, which enables error messages and brightness values to be automatically monitored, making predictive maintenance possible.