In the complete gas storage installation, sensors might look like just a drop in the ocean. But despite their small nature, they play a big part for safe operations in cryogenic storage and transportation of gases.
Cryogenics refer to temperatures of -150° C (-238° F) and under and is used to store some gases in liquid form. When in liquid form, the volume is compressed drastically. For instance, liquid natural gas (LNG) is 600 times more compact in liquid form compared to its gaseous state, while liquid hydrogen is 851 times more compact in liquid form, which makes it possible to store or transport much larger quantities. But cryogenic storage and transportation can be a dangerous affair, and temperature control is vital to ensure safe operations.
Use sensors to minimize risks
When dealing with liquified gas under cryogenic temperatures, sensors are an absolute must. Although sensors are a small part of the full gas storage installation, they are vital to ensure safe operations. Without them, the risk of slow reaction to undesirable temperature rise, and serious accidents as result, increases.
Inside the gas storage tank, sensors are used to monitor the temperature, while sensors placed in the tank’s insulation is used to detect leakage.
The interior temperature sensors are important to monitor stratification of the gases. Even in its liquid form, there will be a boil-off of lighter fractions, making the substance divide into layers with a risk of rollover. Rollover happens if the liquid surface density surpasses the density of the layers beneath, causing inversion of the tank substances. The sudden mixing of layers gives risk of volume expansion due to emission of heat and could potentially cause an explosion, linking temperature sensors directly to safety.
FOUR COLD FACTS ABOUT CRYOGENICS
Cryogenic is used to define temperatures from -150° C (-238° F) and under. The word comes from the Greek “kyros” meaning cold, and the English word “generate”.
Sensors are vital for safety
Sensors monitor the extreme temperatures and are vital for safety. Sensors placed in the storage tanks control temperatures and stratification, while sensors in the insulation can detect leakages. If temperatures rise, the liquid will expand and might potentially explode due to high pressurization.
Transport more gas by not transporting gas
To transport larger quantities, some gases are cooled to cryogenic temperatures, which transforms it to a much smaller amount of liquid. For instance, liquid natural gas (LNG) is 600 times more compact in liquid form compared to its gaseous state, while liquid hydrogen is 851 times more compact in liquid form.
Part of the global green transformation
Easing transportation and storage of gases is in fact also part of a larger mission:
Transforming energy sources from reliable renewables. Liquefying excess energy from wave, solar or wind sources at cryogenic temperatures makes it possible to store off-peak energy that would otherwise be lost. When needed, the liquid is expanded back into its gas state, resulting in a rapid volume increase, which can generate energy.
Sensors designed for the harsh cryogenic environment
To uphold performance and endure the harsh cryogenic environment, the sensors are all specially designed.
For example, multi-spot temperature sensor performance is secured by filling the sensor tube with a dry inactive gas. This is to prevent condensation of water inside the sensor, which would otherwise be a failure risk once the sensor exterior is put into contact with the low temperatures.
For maximum accuracy, our in-house laboratory can test and calibrate 4-wire sensors at -195° C (-383° F) to +100° C (+212° F).
All sensors and production processes meet relevant market standards.
Senmatic produces four types of sensors that can be used in cryogenics. One multi-spot sensor and three types of single spot sensors:
- type MNS for skin and cool down temperature measurement inside the storage tank and leakage measurement in insulation and concrete surroundings as well as pipeline
- type NL Cryogenic for stratification temperature measurement in the tank
- type NS for stratification temperature measurement in tanks systems
- type PMK for leakage measurement where long cables are required
Other equipment for cryogenic use includes:
- Connection box type-MCB holds up to 5 temperature sensors and 5 transmitters
Sensors for LNG storage and distribution
LNG is an effective solution in the goal of CO2 reduction, because it is a much cleaner burning fuel than heavy fuels such as diesel. Natural gas emits up to 50 percent less CO2 than coal and can reduce the nitrogen oxide up to 90 percent compared to heavy fuels, meanwhile the sulphur oxide emission is nearly zero.