Currently, there are three primary methods for LNG cryogenic storage tanks: atmospheric pressure storage, pressure storage of daughter tanks, and pressure storage of vacuum tanks. The choice of storage method depends mainly on the storage capacity required.
1. Low-Temperature Atmospheric Pressure Tank
The structure of the atmospheric tank includes bimetal tanks, using prestressed concrete for the outer tank. These tanks can be installed above ground or underground, with most below 20,000m³ being bimetal tanks. The inner and outer tanks are manufactured on-site, contributing to a lengthy production cycle.
The operating pressure of these tanks is 15KPa, and their operating temperature is -162 °C. They feature a flat-bottomed double-walled design composed of two layers, with a heat-insulating structure and a cold-keeping layer. The inner tank stores liquefied natural gas, while the outer shell provides protection and insulation.
To minimize external heat introduction, the inner and outer tanks are independent and separated. The tank uses pearlescent sand as cold insulation material, filled with dry nitrogen to ensure micro-positive pressure in the interlayer. This design effectively isolates the thermal insulation material from atmospheric pressure and temperature changes, preventing moisture from entering the cold insulation layer.
While the initial investment for low-temperature and atmospheric pressure storage tanks is lower than the alternative mother-and-son tank scheme, their operating costs are higher.
For more information on Cryogenic Pressure Vessels, please contact us for professional answers.
Features of Our Low Temperature Atmospheric Pressure Tank
- Adiabatic method: adiabatic powder accumulation
- Effective volume: 5000m³ ～ 50,0000m³
- Working pressure: 10k Pa ～ 50k Pa
- Storage medium: LNG, liquid ethylene, etc.
- Structural characteristics: vertical, flat bottom, suspended ceiling, double-walled, all-inclusive structure with thermal angle protection
- Foundation type: concrete foundation overhead
2. LNG Mother and Child Tank
The inner tank of the mother tank comprises several low temperature-resistant stainless steel pressure vessels. The outer tank is a large carbon steel container housing multiple inner tanks. Both tanks are filled with thermal insulation material, with the interlayer filled with dry nitrogen to prevent moisture ingress.
These inner tanks are manufactured at a factory, pressure-tested, and transported to the site, where the outer tanks are installed. Storage and distribution stations with a storage scale of 1000m³ to 5000m³ can choose between mother-tank or atmospheric tanks based on their specific requirements.
Features of Our LNG Mother and Child Tank
- Effective volume: 600m³ ~ 3000m³
- Working pressure: 0.3MPa ~ 1.0MPa
- Adiabatic method: pearlite sand powder accumulation insulation & slightly positive pressure dry nitrogen
- Medium: liquid oxygen, liquid nitrogen, liquid argon, LNG, liquid ethylene, etc.
3. LNG Vacuum Storage Tank
The LNG Vacuum Tank is a double-layer metal tank. The inner tank is made of low temperature-resistant stainless steel, while the outer tank is made of carbon steel. The interlayer is filled with thermal insulation material and evacuated to create a vacuum. These tanks are fully assembled and pressure-tested at the factory before being transported to the site.
Generally, individual vacuum tanks in China have a maximum volume of 150m³, with total storage capacities below 1000m³ often requiring multiple tanks for centralized storage. These tanks are typically used in small domestic and foreign LNG gasification stations due to their simple process and low energy consumption.
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