TOKYO GAS TOP > Technical development > For the stable production of city gas > Hot Air Draft Super Heater with Air Fin LNG Vaporizer for Satellite Stations

Hot Air Draft Super Heater with Air Fin LNG Vaporizer for Satellite Stations

Objective


Tokyo Gas has developed and introduced a low-cost, energy-efficient hot air super heater with air fin vaporizer (HAV) for LNG satellite stations. Conventional systems have consisted of a complex combination of an air fin vaporizer, hot water vaporizer (for use during winter), hot water boiler and other auxiliary facilities.
The new system, by contrast, combines an air fin vaporizer with a hot air source in one unit, making it both simpler and usable throughout the year.

 

Practical Use

 
The vaporizer consists of an evaporator, super heater, and hot air draft generator. After maximum use has been made of atmospheric heat to vaporize ultra-low temperature (-162°C) LNG in the evaporator, auxiliary hot air is fed into the super heater to produce ambient temperature city gas.
 
The first HAV, installed at Tokyo Gas’s Kofu Satellite Station, started producing city gas in April 2001 after a long period of testing. About 60 units of this vaporizer are in operation after the installation at Chubu Gas’s Hamamatsu Satellite Terminal, where it entered use in November 2002.
 
Flow diagram of HAV

 


HAV at Chubu Gas’s Hamamatsu Satellite Station
 
 

Features

1. Low cost

Compared with systems that combine an air fin vaporizer with a hot water vaporizer, the HAV is a simpler system that makes maximum use of atmospheric heat, enabling construction costs to be cut by 20% and operating costs by 70%.
 

2. Usable in cold regions

  • Vaporizer: A fan at the top of the evaporator draws in plenty of air, suppressing the performance deterioration caused by accumulation of frost. The air fin tubes have also been redesigned to increase their heat exchange areas.
  • Super heater: Tubes with a large number of fins are used, ensuring that the gas absorbs as much of the heat from the hot air draft as possible.
  • Hot air draft generator: When air temperature falls, the temperature of the hot air draft is raised to keep the gas produced at ordinary temperature.
 
The system is capable of operating continuously to match demand for city gas without the need for any auxiliary equipment such as hot water boilers, allowing it to be used in cold regions.
 

3. Fog prevention

Fog formed by the condensation of water in air, which is a problem with conventional air fin vaporizers, is eliminated by a fan on the top of the vaporizer, which scatters it into the atmosphere.
 

4. High reliability

The HAV’s tubes are made of aluminum alloy, a material that is already widely used owing to its excellent durability at low temperatures. The fan and hot air draft generator are based on generic products, ensuring both proven durability and speedy access to maintenance services.

 

Outlook

 
The hot air draft-type LNG vaporizer developed by Tokyo Gas offers a number of outstanding benefits, including being cost and space-saving, eliminating white smoke and being adapted to cold-weather areas, all of which make it a perfect choice as an LNG vaporizer at satellite terminals, and it is expected to find widespread adoption.
 

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