psa nitrogen machine selection details and related investigation directions

Pressure Swing Adsorption (PSA nitrogen machine) is a leading gas separation skill that uses carbon molecular sieve as an adsorbent. It has an irreplaceable position in the field gas supply in today's world, and is widely used in all walks of life. How should customers choose a functional nitrogen machine, is the preferred problem for many customers, about the selection of a nitrogen machine touch more questions, but as long as we carefully analyze, compare, master the key points, you can be satisfied with the results.

First, before determining the specific model standards (that is, hourly nitrogen production, nitrogen purity, outlet pressure, dew point), we should focus on the functions and characteristics of the nitrogen machine for all comparative analysis, together with their existing environmental conditions, to make the right choice.

First, the comparison and analysis of the nitrogen machine from the following aspects:

a) The rationality of the entire system planning;

b) carbon molecular sieve filling skills and compaction methods;

c) The service life of the control valve;

d) Research and development, production experience, user achievements;

Second, the factors that affect the cost of nitrogen machines:

1) One-time contribution of the whole system;

2) Service life of molecular sieve;

3) The life and cost of the parts required in the process of use;

4) Operation protection, maintenance costs and electricity, water, compressed air consumption;

Third, the factors affecting the stability of the nitrogen machine:

Nitrogen making machine is a high-tech commodity that integrates machine, electricity and appearance, and the stability of equipment is especially important in long-term use. It is not difficult to see from the composition of the nitrogen machine that the stability is affected by the following two points:

1, control valve:

In terms of pressure swing adsorption nitrogen making machine, the valve is necessary to have the following functions:

a) Good function of raw materials, certainly no air leakage;

b) Complete the on or off action within 0.02 seconds of receiving the control signal;

c) Can accept frequent opening and closing to ensure long service life;

1.1, the source of the valve fault

Under normal conditions of use, each programmed valve in each cycle (120 seconds) it is necessary to switch once, according to the nitrogen machine 300 working days per year, 24 hours a day continuous movement, adsorption and desorption cycle of 4 minutes, then each valve needs to open and close more than 200,000 times a year. As long as one valve is faulty, it will affect the normal operation of the entire equipment. Therefore, the continuous service life of the valve is the most important part of the stability and reliability of the nitrogen machine.

2, carbon molecular sieve is the center of the transformer nitrogen machine:

2.1. Functional objectives of carbon molecular sieve:

a. Hardness

b. Nitrogen production (Nm3/T-h)

c. Recovery rate (N2/Air) %

d. Packing density

The above target carbon molecular sieve manufacturers have been indicated at the factory, but can only be used as reference data, how to make the maximum performance of carbon molecular sieve, which has a direct relationship with the technical process of each nitrogen manufacturer and the ratio of adsorption tower height to diameter, together to ensure the use of molecular sieve life is very particular:

2.2. Carbon molecular sieve loading skills:

It is necessary to have special filling skills when carbon molecular sieve is loaded into the adsorption tower, otherwise it is very simple powder and cause failure, from the technical process we can find that when the compressed air enters from the bottom of the adsorption tower at high speed, if there is no special gas disperser, the molecular sieve is subjected to strong impact and conflict by the air flow, which simply causes the powder of the molecular sieve. Other molecular sieves filled into the adsorption tower is not sure tight, after a period of use, the gap between the molecular sieves is decreasing, gradually sinking, if there is no molecular sieve actively fill equipment and compaction equipment, the upper part of the adsorption tower will show significant space. When the compressed air enters the lower part of the adsorption tower, the molecular sieve will have a rapid displacement in a short time under the impact force of the air flow, resulting in molecular sieve collision with each other, conflict and impact with the adsorption tower wall, which simply makes the molecular sieve powder failure.

2.3. The effect of oil and water in the air on molecular sieve:

Because the air contains water and oil vapor, after the compressor, if not treated by strict air purification, the oil vapor is simply adsorbed by the carbon molecular sieve, and it is difficult to desorption, and the molecular sieve pore size is stuffed, resulting in the molecular sieve "poisoning" failure. Therefore, setting up strict air purification equipment before compressed air enters the adsorption tower is a part of ensuring the service life of molecular sieve. Although water is not fatal to molecular sieve, it will make molecular sieve adsorption "load" added, that is, affect its ability to adsorb O2 and CO2, so compressed air drying water removal is to improve molecular sieve adsorption ability and stability can not ignore the question.

3. Plan analysis

Regarding the above problems, SAP has made special research and development, for which the complete nitrogen production system has been carefully planned and placed, and the complete nitrogen production equipment includes the following.

3.1 System flow chart



3.1.1 Air compressor

The air compressor is the first of the air supply, and the compressed air is mainly passed into the compressed air purification component after water removal and oil removal

3.1.2 Air purification equipment

The air purification component is composed of high efficiency filter, freeze dryer, fine filter, super fine filter, catalyst oil separator, etc., compressed air enters the pipeline filter to remove > 1μm particles and larger water, to ensure the normal use of the freeze dryer and the post-filter, the freeze dryer makes it forcibly cooled to 5℃, so that the water vapor in the air condenses into water. After separating and filtering through the water filter, it is discharged by the sewage valve, so that the dew point of the compressed air reaches -10℃, and the fine filter filters the particles and oil and water > 0.01μm, and then enters the super-fine filter to filter the oil and water; Filtration accuracy > 0.001μm, through the activated carbon in the oil remover adsorption of the remaining trace oil mist, to obtain clean compressed air through the pipeline into the nitrogen oxygen separation system, to ensure that the molecular use of long life.

3.1.3 Air storage tank components

The role of the air storage tank is to ensure the smooth use of gas in the system, reduce air pulsation, play a buffer role, and then reduce the pressure of the system to shake, so that the compressed air smoothly passes through the compressed air purification system, in order to fully remove oil and water impurities, and reduce the load of the subsequent PSA oxygen and nitrogen separation equipment. At the same time, when the oxygen and nitrogen separation system performs periodic work switching, it also supplies a lot of compressed air required for agile pressure boost in a short time to the oxygen and nitrogen separation system, and then the adsorption pressure in the adsorption tower quickly rises to the working pressure, ensuring the stable operation of the equipment.

3.1.4 Oxygen and nitrogen separation system

Oxygen and nitrogen separation system is the center of the nitrogen machine, composed of two adsorption towers, tightening equipment, program control valve, and other components, our hospital selected high-quality imported valves, no leakage service life of more than 3 million times, for the whole equipment to provide a reliable function to ensure.

3.1.5 Nitrogen buffer tank

Nitrogen buffer tank is mainly composed of buffer tank, dust filter, flow meter, pressure regulator, throttle valve, etc., to supply stable nitrogen source to the user site. Summary: After the above plan analysis, we can have a certain knowledge and understanding of the structure and composition of the nitrogen machine, but for different environmental conditions and different technical application conditions, the equipment will have certain selection in the equipment.