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What is LNG?

What is LNG?

Natural gas, the cleanest-burning hydrocarbon, is a major source of energy. But many energy-hungry places are located far from gas fields, making pipelines too impractical or costly to build. But if you cool natural gas to make a liquid, you shrink its volume and make it easier and safer to store and shipping.

 

A typical LNG process. The gas is first extracted and transported to a processing plant where it is purified by removing any condensates such as water, oil, mud, as well as other gases such as CO2 and H2S. An LNG process train will also typically be designed to remove trace amounts of mercury from the gas stream to prevent mercury amalgamizing with aluminium in the cryogenic heat exchangers. The gas is then cooled down in stages until it is liquefied. LNG is finally stored in storage tanks and can be loaded and shipped.

 

What is LNG and how can we use it?

LNG is a clear, colourless, and non-toxic liquid which forms when natural gas is cooled to -162ºC (-260ºF). The cooling process shrinks the volume of the gas 600 times, making it easier and safer to store and ship. In its liquid state, LNG will not ignite.

When LNG reaches its destination, it is turned back into a gas at regasification plants. It is then piped to homes, businesses, and industries where it is burnt for heat or to generate electricity. LNG is now also emerging as a cost-competitive and cleaner fuel, especially for shipping heavy-duty road transport.

Fuelling a growing market with LNG

LNG is rapidly playing a bigger role in the energy mix, and the market for it is expected to grow at around 5% annually. Global demand could increase from about 240 million tonnes per annum (mtpa) to around 430 mtpa in 2025. For comparison, just 80,000 tonnes of LNG were shipped in 1964, the first year of the LNG trade.

 

Qatar’s expansion was an act of sheer audacity. Qatar tripled its LNG production capacity to over 80 million metric tons a year — about 11 billion cubic feet a day — leaping past Malaysia and Indonesia as the world’s largest LNG maker. Last year Qatari plants exported almost one-third of the LNG traded across the globe. In the mid-2000s, with construction under way, Qatari officials thought they’d be selling much of their LNG to the United States. The Lower 48 shale-gas boom blew apart that plan. But last year, as Japan idled nuclear power production after the Fukushima disaster, Qatari exports to Japan soared 56 percent over their 2010 level, according to the BP Statistical Review of World Energy. That dulled Qatar’s pain of losing the U.S. market.

 

 

Duplex Stainless Steel

 

Why chose Duplex and Super Duplex?

First off, both Duplex and Super Duplex have far greater corrosion resistance than the stainless grades 304 and 316.

An important feature of Duplex stainless steel is that it’s pitting and crevice corrosion resistance is greatly superior to that of 304 or 316 grade Stainless Steel.  This combined with high mechanical strength and ductility makes it an excellent material for so many applications especially as many fittings are being submerged in salt water.

It would be false economy to use 316 Grade Stainless Steel for marine environments as it is by no means the most robust alloy for high chloride environments.

 

Duplex stainless steel was developed as a product which could improve upon some of the technical weaknesses of the standard austenitic and ferritic stainless steel grades that are available in the market. Both have low strength, ferritic steels have poor low temperature toughness, and austenitic steels have a very low resistance to stress corrosion cracking. Duplex has a microstructure which is split roughly 50/50 between austenite and ferrite and balancing of these phases provides the following benefits

Higher strength which is about twice of 304 stainless steel.

This leads to reduced plate thicknesses being used in fabrications reducing the weight which is of particular significance in items such as pressure vessels, storage tanks, and structural applications such as bridges.

Good weldability in thick plates.

Good low temperature toughness.

Resistance to stress corrosion cracking of importance in many applications including hot water tanks, process plant, brewing tanks, and desalination plant.

Another key feature of Duplex stainless is its enhanced corrosion resistance. There is no single measure of corrosion resistance but the Pitting Resistance Equivalent Number (PREN) is widely used as a means of comparing the relative corrosion resistance of different steel grades.

To work out the PREN we use a mathematical formula for the chemical composition of steel. PREN = %Cr + (3.3 x %Mo) + (16 x %N)

 

Here are the approximate PRE pitting corrosion values for 304 and 316 Stainless Steel plus Duplex and Super Duplex grades:

304                  = 17-20
316                  = 25-30
Duplex             = 30-38
Super Duplex   = >40

Source: http://steelfinder.outokumpu.com/

Duplex stainless steel is still being developed and improved by steel manufacturers.

 

Chart

How quickly we forget. If we look back on the graph over a 10 year period, we will see that the high oil price was a relatively short spell.

What if today’s oil price is the normal level? Will we learn to adjust spending and investments accordingly?

When it comes to water consumption, here in the UK, we use approx. 150 litres of water a day per person and if we compare with USA where they get through some 570 litres a day per person.

The worlds demand for fresh water is rising by 640bn litres a year.

Desalination is more expensive than treating rainwater or waste water, at about £1.95 per m³, but pumping a cubic metre of fresh water distances of more than 200km requires more energy than desalinating the same amount of seawater. Many plants produce the bulk of their water at night when there is less demand for electricity, and utilise power that would otherwise go to waste.

Even here in the UK we have a seawater desalination plant. This plant is not routinely used and is there if we suffer severe drought, after a couple of dry winters.

However there is no wastewater recycling in London, food for thought with the knowledge of the rising demand.

As the world’s population continues to rise, the pressure on water resources are only going to increase. Let us hope that there will be technological advances to meet the demand.