Application for LNG and Other Low-temperature Pipeline

LNG conveying pipe cold insulation material application status quo

Based on the LNG super-low temperature (-163 ℃) storage characteristics, the selection of LNG pipe cold insulation material has become the industry must face the problem. Cold or cold effect is not only related to the quality of the entire pipeline transmission efficiency, but also the safety of the device also has a crucial impact. Therefore, suitable cold-insulation materials can not only reduce the energy consumption, reduce the cold loss and loss of BOG, but also meet the requirements of environmental protection and provide safeguards for enterprises to produce safely and create better benefits.
At present, most of the LNG transmission pipeline cold insulation projects in our country are not very satisfactory. The main defects and causes are as follows:
 lngcoolinsulation3.jpg
Defect 1: cold insulation structure is unreasonable, cold insulation thickness is not standard
Cause: some of the main insulation materials used in cold engineering is not cold enough, low temperature stability is poor; the traditional material low temperature thermal conductivity calculation fallacy more, resulting in cold insulation thickness calculation error.
Defective 2: poor cooling effect and easy to decay, cold loss, increase maintenance costs and system operation risk
Cause: Higher thermal conductivity of traditional materials, low mechanical strength at low temperatures, fragile, resulting in damage to the cooling layer.

Defective 3: After the cold large diameter, large gallery volume, pipeline layout difficulties
Cause: Higher thermal conductivity of traditional materials.

Defects 4: need to set expansion joints, increase the construction difficulty and the risk of failure of cold insulation structure
Causes: Traditional materials at low temperature expansion rate or shrinkage and steel pipe larger differences, the need to set up special expansion joints.

Defective 5: construction complex, difficult, longer installation time
Cause: The traditional cold preservation project more construction processes, technology and more complicated, more difficult to master.

Aerogel insulation blanket are used for the benefit of LNG pipe cool insulation
The main advantage:
1. Ultra-low thermal conductivity, aerogel is the world's lowest thermal conductivity of the solid, -200 ℃ thermal conductivity ≤ 0.01W / (m • K). 
2. The best low temperature stability, -200 ℃ can still maintain long-term cold insulation performance and good flexibility, no cracking.
3. Excellent dimensional stability, nano-special structure can resist the internal stress caused by pipe expansion, without the need to set expansion joints.
4. Soft and light, easy to install, compressive, tensile, seismic, shock absorbers can withstand brutal construction.
Contrast with the traditional cold insulation material in the table below:
 

 

Aerogel insulation blanket

Foam glass

PIR

Thermal Conductivity，W/(m•K)
（25℃）

0.014～0.016

0.045～0.055

0.022～0.026

density，kg/m3

180

180～240

50～80

cold insulation

thickness

About 1/2 of traditional materials

——

——

energy saving effect

Save 30% on cold loss and BOG

——

——

Water absorption（vol%）

0.36

0.5

1.5

Hydrophobic rate

≥99%

 

 

Construction

Roll coil, flexible, easy construction

Very poor, high loss, shaped parts still need internal polyurethane foam

Ordinary, field foaming, but poor foam uniformity

Low temperature stability

excellent

excellent

Easy to aging, lower strength, poor stability

Dimensional stability

0.45%

poor

poor

Expansion joints

No need to set, reduce the risk of system failure

To be set, to prevent the pipe material due to low temperature displacement of extrusion, broken

To be set, to prevent the pipe material due to low temperature displacement of extrusion, broken

Protect pipes against mechanical impact

Compression, tensile, crack, resist brutal construction

Poor, fragile material brittle

Poor, fragile material brittle

Reuse

Disassembly and maintenance, can be reused

Fragile disassembly, can not be used

Fragile disassembly, can not be used

Other

Reduce the cost of auxiliary materials by 25%, reduce the size of the workshop or pipe gallery, and reduce the difficulty of pipeline arrangement.

 
Aerogel Insulation blanket Insulation Program and Economic Benefits:
Take the LNG pipeline with a pipe diameter of 108mm (straight pipe section) as an example, the thickness of the aerogel and the traditional insulation materials, the cooling effect and the economic benefits are analyzed as follows:
Cool insulation program
lngcoolinsulation2.jpg
Aerogels insulation blanket as a thermal insulation material, the outer layer of aluminum foil to reduce heat radiation, thermal insulation layer with a color steel plate for protection.
Insulation material thickness in the table below:
 

Aerogel Insulation

10mm×4 layers + Aluminum foil

Traditional materials

PIR 80mm + Aluminum foil

Test environment: ambient temperature 35 ℃, humidity 60%.
 
Construction diagram can refer to the following figure:
aerogel construction.jpg
 

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