|LNG Badak Bontang, East Kalimantan Indonesia|
One interesting phenomenon of LNG is when we expose it onto water surface it could result in a small to big explosion. How this phenomenon could happen? It happens with the same reason of hot cooking oil when we spray it with water droplets.
It should be noted that the differences in water temperature and the heat of cooking oil is quite large. The water temperature was 25 C, whereas no cooking oil at temperatures above the boiling point of water at 100 C. When water touches the surface of the hot cooking oil, evaporation occurs quickly. Volume of water changed rapidly to 1000 times greater after the phase change from liquid to vapor. As a result water vapor trapped in the hot cooking oil fluid pushes out quickly and explosion effects are occurring accompanied by splashing of hot cooking oil.
The same thing happens when the temperature is -160 C LNG thrown over a water surface at a temperature of 25 C. There is a difference in temperature of 185 C. This is greater than in water example with hot cooking oil before. LNG volume when it turns to gas will increase to 600 times greater. As a result, the LNG liquid which turns into gas will quickly break through the surface of the water, causing explosions effects.
True Story of Danger When LNG Poured onto Water Surface
I will share a true story I experienced while working in one of the LNG plant in Indonesia when there was LNG liquid spill. It was a very depressing moment because we all know what could happen when LNG vapor gets ignited by an electric spark or other ignition sources. The electrical power source had been disconnected to reduce risk. It happened early in the morning. LNG liquid spill stopped but came out again every four hours later. Suddenly around midnight there was a huge explosion. We all wondered what really happened. There was no sign of fire smoke or any fire at all. But it was dark because the electricity was shutdown. Fortunately, there were no operators at the scene because it was very dark. We must wait until the next morning. The next morning I told my boss that LNG spill will appear again in less than 4 hours from now. Finally it was decided to install an isolation valve so that the spill could be stopped for good.
After investigation, it was concluded that when the LNG leaked from the valve it fell onto the ground and cooled the surroundings. As a result, the LNG initially was evaporated into a gas, remained in a liquid phase and flowed into a closed trenches (sewers). In the trenches the liquid LNG met with water surface causing explosion. The forces resulted from the explosion are capable of tearing up a 50 cm thick concrete, split in half and lifted it up to the surface of the ground. One sand trolley was thrown up to the top and stuck on a pipe rack. It took long overhaul to repair the damages.
Liquefying Natural Gas is basically a risk management business. As a matter of fact man can never reduce the risk to an absolute zero. Companies and state regulations are usually will require that we reduce the risk to a minimum possible or as low as reasonably practical. If you can not, then we must stop the operation and make the necessary repairs or modifications. Therefore readiness to face the worst case scenario should always be prepared and practiced.
Helfia Nil Chalis. Bisnis Internet.