VFB #4 - LNG RECEIVING TERMINAL 液化天然气接收站

LNG RECEIVING TERMINAL 液化天然气接收站

Week of November 28 to December 4, 2005

 在谈接受站之前先了解一些有关LNG的资料

1.什么是液化天然气？

 Liquefied Natural Gas or LNG is natural gas in a liquid form, when natural gas is cooled to minus 161 degree Celsius, it becomes a clean, colorless, odorless liquid. LNG is either corrosive or toxic.

2.LNG如何聍藏？

When LNG is received at most terminals, it is transformed to insulated storage tanks, that are built to specifically hold LNG. These tanks can be formed above or below ground and keep the liquid at a low temperature to minimize the amount of evaporation. If LNG vapors are not released, the pressure and temperature within the tanks will continue to rise. LNG is characterized as a Cryogen, a liquefied gas kept in its liquid state at very low temperature. The temperature within the tank will remain constant if the pressure is kept constant by allowing the Boil off gas to escape from the tank. This is known as “Auto-refrigeration”. The Boil-off-gas is collected and used as a fuel source in the facility or on the tanker transporting it. When natural gas is needed, the LNG is warmed to a point where it converts back to its gaseous state. This is accomplished using a Regasification process involving heat exchangers.

3.LNG是否会燃烧或爆炸？

 When cold LNG comes in contact with warmer air it becomes a visible vapor cloud, as it continues to get warmer, the vapor cloud becomes lighter than air and rises. When LNG vapor mixes with air it is only flammable if it is within 5% to 15% natural gas in air. If it is less than 5% natural gas in the air there is not enough natural gas in the air to burn. If it is more than 15% natural gas in air, there is too much gas in the air and not enough oxygen for it to burn.

As a liquid, LNG is not explosive. LNG vapor will only explode if in an enclosed space. LNG vapor is only explosive if within the flammable range of 5% to 15% when mixed with air.

 近年来一些美国公司在申请建造液化天然气接收站时都遇上不少的阻延 , 原因是当局还没有一套如何应付恐怖份子攻击船舶之后所引起災难的对策，直到 2005 年6 月14 日 U.S. Coast Guard 公布一份 Navigation and Inspection Circular (NVIC) No.05-05, providing “Guidance on Assessing the Suitability of a Waterway for LNG Marine Traffic.” This NVIC is intended to provide guidance on the marine traffic safety and security information that must be submitted by those planning to build and operate a shore side LNG terminal.

As a document, the guidance pulls together key findings from independent studies on LNG safety and security and defines them into a single defined scope and methodology. This analysis is called a Waterway Suitability Assessment (WSA). Its recommended content is split into six parts:

1. port characterization
2. characterization of LNG facility and tanker routes
3. risk assessment
4. risk management strategies
5. resources needed for safety, security and response
6. conclusion and recommendations

这份政府公布澄清各方面对 LNG 的顾虑，而打开申请之大门。

Waterway Suitability Assessment (WSA)		USCG responsibilities

到今年 3 月为止美国共有 4 个接收站在运作中：

Terminal design in U.S.

除此以外还有四个正在建造中：

Designs for new U.S.terminals

到目前为止全世界共有 46 LNG Receiving terminals 其中一半是在日本。 See table below:

我国的第一个 LNG 接收站正在广东省深圳附近的大鹏湾由中海油集团负责建造中， 该站将於 2006 年 6 月完工。包括大鹏湾我国政府单位 NDRC 共批准十个接收站， 其中五个在计划中：

Da Pang Wan, China terminal design		Da Pang Wan, unloading equipmeny

卅十多年来 LNG 并没有发生任何特大的意外，但我们也不可以排除它潜在的危险性，所以多数的接收站都造在偏僻的海港如大鹏湾， 这个地方编者到过是一个三面环山人烟稀少的深水港。我国得天独厚有三千多哩的海岸线可选， 但日本就没有这样幸运，他们的接收站都造在人口稠密的港口，如果有一天发生意外后果真的不堪设想。

我国虽然是产煤大国，但天然气是一种非常干净的能源如能够多于采用，这对环保污染和进口原油的压力将可大大减轻。

Tanker berthing		More port design		More port design

附注 : 为保持文章的本意有些字句是用原文 ( 英文 ) 表达。请谅。