Since 1989, Demaco has been active in the field of vacuum technology as cryogenic (pipe)insulation. This innovative technique provides the best insulation for cryogenic transfer lines and applications. Our technique has already enabled more than 1500 of our clients to effectively set up their cryogenic systems.
But what exactly is vacuum insulation, and what are the main advantages of this technique? We will be covering this in detail in this blog.
What is vacuum insulation?
Vacuum insulation is double-walled cryogenic (pipeline)insulation that uses vacuum or high-vacuum to keep heat out of a transfer line or cryogenic application. A vacuum pump draws out all the air between the double walls, creating a vacuum. The cryogenic gases in the pipe or application are kept at optimum temperature by this cryogenic pipe insulation, thus retaining their liquid form.
What exactly is a vacuum? In a theoretically perfect vacuum, the pressure is precisely 0 Pascal (Pa) while the space is empty of matter, including air
The insulation value matter-free space, such as vacuum glass is exceptionally high. Compared to, for example, PIR/PUR, Foam vacuumglas, Armaflex, Perlite, and Misselon, vacuum insulation insulates as much as 8 to 25 times better. If the vacuum environment is combined with a multi-layer combination of aluminum foil and glass paper, heat ingress is almost completely blocked.
The illustration above shows the parts that make up a vacuum insulated pipe section. The pump valve under the black cap pumps the space between the two layers of pipe into a vacuum. The green spacers ensure sufficient space between the two tubes, and the compensator (bellow) absorbs any shrinkage of the inner tube. Finally, multi-layer insulation is shown, which further increases the insulation value.
What does this mean on a practical note? The following ten benefits are a reason for many of our customers to choose vacuum insulated cryogenic systems to process cryogenic liquids like liquid nitrogen, liquid hydrogen, liquid helium, liquid oxygen or liquified natural gas.
A smaller diameter
Compared to other forms of cryogenic pipe insulation, a vacuum system takes up relatively little space. Cryogenic engineers can therefore keep the diameter of vacuum-insulated transfer lines relatively small, and applications with this form of insulation also require little space . This makes vacuum insulation ideal for use in small(er) spaces.
The figure below shows the ratio of uninsulated pipes, pipes with foam insulation, and vacuum insulated pipes. Of course, a vacuum insulated pipe takes up more space than an uninsulated pipe, but the diameter does not come close to that of the foam insulation.
Quality Preservation of cryogenic substances
Quality retention is central to cryogenic engineering. Cryogenic systems, transfer lines, cryogenic tanks, complementary products and cryogenic applications are all built to minimize the warming of cryogenic fluids to ensure they reach an application in the proper quality. In case they heat up, gas bubbles will form and may cause problems in the application.
The insulation value of vacuum insulation is significantly higher than that of most other cryogenic insulation materials. This means less heat inleak, less gas-forming, and consequently higher quality liquid gas.
Reduced gas loss
As mentioned earlier, heat inleak results in lower quality liquid gas and the loss of gas.
In most cases, when a cryogenic liquid such as liquid nitrogen or liquid hydrogen becomes gaseous due to poor insulation or a leak in the system, the gas is lost. Consequently, it leaves the system, whether or not through a quality improvement product such as an automatic gas vent or a degasser.
Losing gas is expensive; this can be avoided through the use of proper insulation. Compared to other forms of cryogenic insulation, vacuum insulation significantly reduces gas formation and gas loss. This means less waste and lower costs for the end-user.
Less ice formation with cryogenic cooling
Gas leakage leads to icing on piping, often at weak spots or damages at connections or joints. When gas exits a pipeline, it is still very cold. Therefore, when it comes into contact with the ambient, warm and humid conditions, the water vapor in the surrounding air will freeze instantly on the cold surface of the pipe.
Large chunks of ice on pipes can break off and cause injury or damage to surrounding materials. In addition, ice build-up can also cause blockages in transfer lines or systems.
Because of its very high insulation value, vacuum insulation is very successful in preventing ice accumulation. In addition, the use of auxiliary products, such as an exhaust gas heater, can further reduce ice build-up.
Hygiene
Broad applicability
Particularly in specific industries, such as the pharmaceutical industry and the medical industry, cryogenic applications and vacuum insulated pipes are subject to strict regulations. The available space for the cryogenic constructions is often limited, and bacterial contamination is impermissible.
For many end-users in these industries, vacuum insulation is the ultimate solution. Accompanied with the appropriate certification, we see many vacuum insulated systems in, for example, biobanks (for cryopreservation) and in pharmaceutical laboratories.
Within almost every cryogenic industry, applications are insulated using vacuum insulation. This makes the vacuum technology incredibly useful.
Safety cryogenic freezing
On our page about cryogenic technology, we cover some of the risks involved in using cryogenic liquids. For example, the release of liquid gas can cause injuries, be harmful to health, or cause a fire or explosion. In addition, a gas leak can have significant financial consequences due to the loss of valuable resources and the additional risk of the earlier mentioned ice build-up and bacterial contamination.
Compared to other forms of cryogenic insulation, vacuum technology significantly reduces all of the above risks. It, therefore, provides greater safety for employees, surrounding systems, and the budget.
Easy to maintain
Vacuum insulated transfer lines are produced in the form of separate pipe sections. A section is 6 meters on average, and under the supervision of a cryogenic engineer, a complete piping system is formed by connecting various pipe sections. This piping is vacuum pumped section by section and assembled with the appropriate couplings.
This segmental method of installation makes it easy to solve problems in the pipeline system. If one piece of piping presents difficulties, for example, in the form of a leak, then this part of the piping can easily be removed for repair.
Extended service life
Not only the insulation value but also the quality of vacuum insulated transfer lines is exceptionally high. The pipes are made of a double layer of stainless steel. When the space between these layers is vacuum pumped, on average, a piping section lasts about 15 to 20 years. After this period, the piping section is often vacuum pumped again, after which it can be used for much longer.
The service life of the materials is significantly higher than that of most other insulation materials. This makes vacuum technology systems economical and durable.
Complete systems
Lastly, a practical advantage of vacuum insulation. Unlike several other types of cryogenic pipe insulation, vacuum-insulated piping is easy to combine with auxiliary products that further enhance the quality of liquid gas.
In combination with a network of transfer lines, we supply many of our customers with auxiliary (vacuum insulated) products such as phase separators, automatic gas vents, or phase separators. If these products were protected with other insulation methods, the complete systems would take up much more space than necessary.
The relatively small diameter of vacuum-insulated piping and the uncomplicated connection to quality-enhancing products create a high-quality cryogenic system that is modest in size, broad in application, with safety at the core, and providing liquid gases of the highest quality.
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