Small- and Mid-Scale LNG – Industrial LNG Liquefaction Technologies

Volume is measured in cubic meters. Weight – of course – in kilograms. Investment and profit are being measured in a variety of currencies all over the world. But how do you measure the simplicity and flexibility of industrial liquefaction plants?

Keep it simple

Simplicity and flexibility power your investment. And they both power your LNG production in a very simple way – today more than ever.

The 19th century was the birthmark for the Brayton cycle, developed by George Brayton, a pioneer in the development of turbine engines. There are many forms of Brayton cycles: ranging from single open cycles used in gas turbines and jet engines to the closed thermodynamic cycles. More importantly, the reversed Brayton cycle is used to provide cooling.

Among other refrigerant cycles, the reversed Brayton cycle appeared between 1850 and 1880. Based on its principles, First and Second-Generation Brayton cycles had been established, and ultimately the Third as well as the Fourth-Generation cycles for small- and mid-scale in industrial process plants had been developed.

Can liquefaction of gases based on this simple technology, in the range of up to 1 million tons per year, become easier? More flexible? And what’s most important to you: Can it become more cost-effective compared to mixed-refrigerant-based liquefaction processes?

The fundamentals

The reversed Nitrogen Brayton cycle, or Nitrogen Expansion cycle, strictly follows the tradition of simplicity and robustness. The prime liquefaction medium – Nitrogen – is always kept in the gaseous phase. Also, nitrogen is found in abundance; simple and cheap to produce from the surrounding air by separation. Consequently, no extra hold-up system is required to store several hydrocarbons, i.e. pentane, butane, propane, ethylene to obtain the proper mix (Mixed Refrigerants).

Speaking in liquefaction terms, and in a nutshell: nitrogen is being compressed and subsequently expanded – which provides the necessary low temperature to liquefy gases, i.e. converting natural gas to LNG. All liquefaction plants based on the principles of the reversed Brayton cycle comply with the following:

  • fast start-up / shut-down procedures
  • flexible turn-down rates in minutes without affecting process stability
  • superb specific power consumption, i.e. Third and Fourth-Generation

The reversed First and Second-Generation Brayton cycles are fully established within industrial liquefaction processes. Worldwide, several small-scale LNG plants are based on both generations. From 2011 onwards, the fully developed Third and Fourth-Generation Brayton cycles will be introduced into the market.

In comparison, the graph also visualizes industrial small-, mid-scale and base-load MR cycles.

The extension of the fridge

As the wheel is another extension of the foot, clothing is another extension of the skin. Very simple things – yet necessities in daily life. When industrial liquefaction technology is brushed against liquefaction technology, today’s and upcoming industrial liquefaction plants, based on the principles of the reversed Brayton cycle, are the extension of the fridge – only bigger. Simple in design yet highly efficient. Flexible in terms of storing products. Based on an ubiquitous and all-time safe cooling medium (Nitrogen). Easy to start. Easy to turn off. Easy to regulate. Compact and – of course – fast in delivery.

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