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LDH-GAS Small integrated high purity 99.99% liquid nitrogen generator
PSA Nitrogen Generator full name: Pressure Swing Adsorption (PSA).PSA is a new gas separation technology, which has been developed rapidly in foreign countries since the late 1960s and early 1970s. Its principle is to separate the gas mixture by the difference of the "adsorption" performance of different gas molecules by molecular sieve. It takes air as raw material.The nitrogen and oxygen in the air are separated by the selective adsorption of nitrogen and oxygen with a high efficiency and high selection of solid adsorbent.
At present, carbon molecular sieves and zeolite molecular sieves are used more in the field of nitrogen and oxygen production.The separation of oxygen and nitrogen by molecular sieve is mainly based on the different diffusion rates of the two gases on the surface of molecular sieve. Carbon molecular sieve is a carbon-based adsorbent with some characteristics of activated carbon and molecular sieve.Carbon molecular sieves are composed of very small micropores with pore sizes ranging from 0.3nm to 1nm.The smaller diameter of the gas (oxygen) diffuses faster and more into the solid phase of the molecular sieve, so that nitrogen enrichment can be obtained in the gas phase.After a period of time, molecular sieve on oxygen adsorption balance, according to the carbon molecular sieve under different pressure on the adsorption of different gas adsorption characteristics, reduce the pressure to remove the carbon molecular sieve on oxygen adsorption, this process is called regeneration.PSA usually uses two towers in parallel, alternately pressurized adsorption and decompression regeneration to obtain a continuous flow of nitrogen.
When producing your own nitrogen, it is important to know and understand the purity level you want to achieve. Some applications require low purity levels (between 90 and 99%), such as tire inflation and fire prevention, while others, such as applications in the food and beverage industry or plastic molding, require high levels (from 97 to 99.999%). In these cases PSA technology is the ideal and easiest way to go. In essence a nitrogen generator works by separating nitrogen molecules from the oxygen molecules within the compressed air. Pressure Swing Adsorption does this by trapping oxygen from the compressed air stream using adsorption. Adsorption takes place when molecules bind themselves to an adsorbent, in this case the oxygen molecules attach to a carbon molecular sieve (CMS). This happens in two separate pressure vessels, each filled with a CMS, that switch between the separation process and the regeneration process. For the time being, let us call them tower A and tower B. For starters, clean and dry compressed air enters tower A and since oxygen molecules are smaller than nitrogen molecules, they will enter the pores of the carbon sieve. Nitrogen molecules on the other hand cannot fit into the pores so they will bypass the carbon molecular sieve. As a result, you end up with nitrogen of desired purity. This phase is called the adsorption or separation phase. It does not stop there however. Most of the nitrogen produced in tower A exits the system (ready for direct use or storage), while a small portion of the generated nitrogen is flown into tower B in the opposite direction (from top to bottom).
This flow is required to push out the oxygen that was captured in the previous adsorption phase of tower B. By releasing the pressure in tower B, the carbon molecular sieves lose their ability to hold the oxygen molecules. They will detach from the sieves and get carried away through the exhaust by the small nitrogen flow coming from tower A. By doing that the system makes room for new oxygen molecules to attach to the sieves in a next adsorption phase. We call this process of 'cleaning' an oxygen saturated tower regeneration.
What is Pressure Swing Adsorption Gas Generation
PSA stands for pressure swing adsorption. It is a technology that can be used to generate nitrogen or oxygen for professional purposes.
First, tank A is in the adsorption stage, and tank B is regenerated. In the second stage, pressure is equalized between the two vessels in preparation for the switch. After the switch is complete, tank A regenerates, and tank B generates nitrogen.
Nitrogen purity and air intake requirements
To purposefully generate your own nitrogen, it is important to know the purity levels required for each application. However, there are some general requirements for air intake. Compressed air must be cleaned and dried before entering the nitrogen making machine, which is conducive to affecting nitrogen quality and preventing CMS from being damaged by moisture. In addition, inlet temperature and pressure should be controlled between 10 and 25 ° C while maintaining pressure between 4 and 13 bar. For proper air handling, there should be a dryer between the compressor and the generator. If the intake air is produced by an oil-lubricated compressor, an oil-carbon filter should also be installed to remove any impurities before the compressed air reaches the nitrogen generator. Most generators are fitted with pressure, temperature and pressure dew point sensors that act as fail-safes to prevent contaminated air from entering the PSA system and damaging its components.
Typical installation: air compressor, dryer, filter, air receiver, nitrogen generator, nitrogen receiver. Nitrogen can be consumed directly from the generator or through additional buffer tanks (not shown).
Another important aspect of PSA nitrogen production is the air factor. It is one of the most important parameters in a nitrogen generator system because it defines the compressed air required to obtain a certain nitrogen flow rate. Thus, the air factor indicates the efficiency of the generator, meaning that a lower air factor indicates a higher efficiency, and of course, a lower overall operating cost.
At this point, the pressure of the two towers will reach equilibrium and they will change from adsorption to regeneration and vice versa. Tower A's CMS will be saturated, while Tower B, due to decompression, will be able to restart the adsorption process. This process is also known as a "pressure wobble," which means it allows certain gases to be trapped at higher pressures and released at lower ones. The twin-tower PSA system allows continuous nitrogen production at desired purity levels
With air as raw material, with carbon molecular sieve as adsorbent, the use of pressure change adsorption principle, the use of carbon molecular sieve on oxygen and nitrogen selective adsorption and separation of nitrogen and oxygen method, commonly known as PSA nitrogen.This method is a new technology of nitrogen production which developed rapidly in 1970s.Compared with the traditional method of nitrogen, it has simple process, high degree of automation, produce gas quickly (15 ~ 30 minutes), low energy consumption, product purity can be adjusted according to user needs in a wide range, convenient operation and maintenance, low operating cost, good adaptability device etc., in 1000 nm3 / h the following competitive in nitrogen making equipment,PSA is more and more popular among medium and small nitrogen users, and has become the choice method for medium and small nitrogen users.
1. Why choose PSA nitrogen generator ?
High nitrogen purity
PSA nitrogen generator plants allow production of high-purity nitrogen from air, which membrane systems are unable to provide - up to 99.9995% nitrogen.The nitrogen generators use CMS (carbon molecular sieve) technology to produce a continuous supply of ultra high purity nitrogen and are available with internal compressors or without.
Low operating costs
By substitution of out-of-date air separation plants nitrogen production savings largely exceed 50%.
The net cost of nitrogen produced by nitrogen generators is significantly less than the cost of bottled or liquefied nitrogen.
Nitrogen Generators Create Less Impact on the Environment
Generating nitrogen gas is a sustainable, environmentally friendly and energy efficient approach to providing pure, clean, dry nitrogen gas. Compared to the energy needed for a cryogenic air separation plant and the energy needed to transport the liquid nitrogen from the plant to the facility, generated nitrogen consumes less energy and creates far fewer greenhouse gases.
LDH-GAS Small integrated high purity 99.99% liquid nitrogen generator
Process flow and equipment introduction of PSA nitrogen making machine
1. Brief introduction to the technological processNitrogen Generator
Air through the air filter to remove dust and mechanical impurities into the air compressor, compressed to the required pressure, after strict oil removal, water removal, dust removal and purification treatment, the output of clean compressed air, the purpose is to ensure the service life of the molecular sieve adsorption tower.There are two adsorption towers with carbon molecular sieve. One tower is operated while the other tower is decompressed and desorbed.Clean air into the working adsorption tower, through the molecular sieve oxygen, carbon dioxide and water are absorbed by it, flow to the outlet end of the gas is nitrogen and trace argon and oxygen.Another tower (desorption tower) allows adsorbed oxygen, carbon dioxide and water to escape from the pores of the molecular sieve and discharge into the atmosphere.In this way, the two towers take turns to complete nitrogen and oxygen separation and continuously output nitrogen, as shown in Fig. 2.The purity of nitrogen produced by pressure change adsorption is 95%-99.9%. If higher purity nitrogen is needed, nitrogen purification equipment should be added.Psa nitrogen making machine output 95% 99.9% of the nitrogen into the nitrogen purification equipment, at the same time through the flowmeter to add just the right amount of hydrogen gas, hydrogen and nitrogen in the purification equipment of deoxidization tower of trace oxygen in catalytic reaction, and then by water to remove oxygen condenser cooling, in addition to water, water separator, and then through the depth of the dryer drying (two adsorption drying tower used interchangeably:One is adsorbed and dried for water removal, the other is heated for desorption and drainage) to obtain high purity nitrogen. At this time, the purity of nitrogen can reach 99.9995%. At present, the maximum production capacity of nitrogen production by pressure swapping adsorption in China is 3000M3N /h.
