Application of oxygen analyzer in PSA nitrogen generator

Date: 2020-03-09 14:53:21

Air is the "life gas" that we breathe every day. Its main components are nitrogen and oxygen. Calculated by volume fraction, nitrogen is about 78% and oxygen is about 21%. The other 1% air composition includes rare gases such as helium, neon, argon, krypton, xenon, krypton, etc., with a volume fraction of about 0.934%, about 0.034% of carbon dioxide, about 0.002% of water vapor, impurities and other substances.


Although these gases are transparent, colorless and odorless and cannot be easily noticed, they have an important impact on the survival and production of us humans. For example: Oxygen is a breathing organism that supports humans and all animals on the planet. People's industrial production: iron and steel making, ammonia synthesis, rocket combustion, etc. require a large amount of oxygen, but they are directly extracted from the air during production. ; The respiration of green plants also requires oxygen.


Although nitrogen contains more than oxygen in the atmosphere, but because it is an inert gas, its nature is not active, and it is often used as a protective gas, such as: fruit, food, bulb filling gas. In order to prevent certain objects from being oxidized by oxygen when exposed to air, filling grain silos with nitrogen can keep the grains from mildew and germination, and keep them for a long time.


With the rapid development of industry, nitrogen has been widely used in chemical, electronics, metallurgy, food, machinery and other fields. The demand for nitrogen in China has increased at a rate of more than 8% each year. The chemical nature of nitrogen is inactive, and it is very inert under ordinary conditions, and it is not easy to chemically react with other substances.


Therefore, nitrogen is widely used as a protective gas and a sealing gas in the metallurgical industry, the electronics industry, and the chemical industry. Generally, the purity of the protective gas is 99.99%, and some require high-purity nitrogen above 99.998%. However, pure nitrogen cannot be directly extracted from the natural world. Therefore, in order to improve the utilization rate of nitrogen in industrial production, the company mainly uses air separation. The air separation method includes a cryogenic method, a pressure swing adsorption method, and a membrane separation method. The following is a brief introduction to the relevant application of the oxygen analyzer in the PSA nitrogen generator.


Principle of PSA nitrogen generator

PSA is a new gas separation technology. Its principle is to use the difference in the "adsorption" performance of molecular sieves to different gas molecules to separate gas mixtures. It uses air as the raw material and carbon molecular sieve as the adsorbent. The method of separating nitrogen and oxygen by the selective adsorption of oxygen and nitrogen by a carbon molecular sieve is commonly referred to as PSA nitrogen production. This technology has been rapidly developed abroad since the late 1960s and early 1970s.


Features of PSA nitrogen generator

1. Low cost: The PSA process is a simple nitrogen production method. Nitrogen is produced within a few minutes after startup, and the energy consumption is low. The cost of nitrogen is much lower than the cryogenic air separation nitrogen production and liquid nitrogen on the market.


2. Reliable performance: imported microcomputer control, fully automatic operation, no operator who needs special training, just press the start switch, it can run automatically to achieve continuous gas supply.


3. High nitrogen purity: The instrument detects trace oxygen and trace water to ensure the required nitrogen purity, and the purity can reach 9999%.


4. Select high-quality imported molecular sieve: it has the characteristics of large adsorption capacity, strong pressure resistance and long service life.


5. High-quality control valves: High-quality imported special pneumatic valves can ensure the reliable operation of nitrogen-making equipment.

Work flow of nitrogen generator.


The work flow of the nitrogen generator is controlled by a programmable controller that controls three first conductive magnetic valves, and then the solenoid valves control the opening and closing of eight pneumatic pipeline valves. Three pre-conducting solenoid valves control the left suction, pressure equalization, and right row states, respectively. The time flow of left suction, equal pressure and right row has been stored in the programmable controller. When the process is in the left suction state, the solenoid valve that controls the left suction is energized, and the pilot air is connected to the left suction intake valve and the left suction gas valve. The right exhaust valve makes these three valves open to complete the left suction process, while the right suction tank desorbs.


When the process is in the pressure equalization state, the solenoid valve that controls the pressure equalization is energized and the other valves are closed; the pilot air is connected to the upper pressure equalizing valve and the lower pressure equalizing valve, so that these two valves are opened to complete the pressure equalization process. From the principle of the PSA nitrogen generator above, we know that the adsorption tank of the PSA nitrogen generator, when the pressure is high, the carbon molecular sieve adsorbs oxygen in the air, and the nitrogen that is not easily adsorbed becomes the product; when the pressure is low, the oxygen Desorbed from the carbon molecular sieve. With the change in pressure, the required nitrogen can be effectively separated from the air.


Among them, when testing the oxygen concentration in nitrogen, because most of them are trace levels, Industrial Mining Networks recommends a Southland oxygen analyzer-OMD-640. The OMD-640 oxygen analyzer combines a rugged and portable design, making the user interface easy to understand. At the same time, the design also makes the instrument more cost-effective and reduces maintenance costs. This is mainly reflected in the analyzer carrying an 8G removable USB A flash drive records data in a .csv (Excel) file format, and users have been using the instrument for approximately 50 years before running out of storage. OMD-640 oxygen analyzer has a full scale low range of 0-1ppm, lower measurement range and higher accuracy. The analyzer can see the screen clearly under direct sunlight without obstruction or other methods.


On the other hand, the oxygen sensor used in OMD-640 is based on the principle of electrochemical fuel cells. All oxygen sensors are manufactured under strict quality inspection procedures. The standard sensor TO2-133 can work smoothly in inert gas, and can also choose the acid resistance TO2-233 sensor. In addition, the sensors are independent and require very little maintenance. There is no need to clean the electrodes or add electrolyte.
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