First, the nitrogen machine is compared and analyzed from the following aspects: a) the rationality of the whole system design: b) carbon molecular sieve filling technology and compaction method; Control valve service life; d) Research and development, manufacturing experience, user performance.

2, the factors affecting the cost of nitrogen machine: 1) the whole system one-time investment; 2) Service life of molecular sieve; 3) Life and cost of parts required during use; 4) Operation and maintenance, maintenance costs and electricity, water, compressed air consumption; Third, the factors affecting the stability of the nitrogen machine: the nitrogen machine is a high-tech product involving machinery, electricity and instrumentation, and the stability of the equipment is particularly 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:

Control valve: for the pressure swing adsorption nitrogen machine, the valve must have the following properties: a) good material performance, absolutely no air leakage; b) Complete the on or off action within 0.02 seconds of receiving the control signal; c) can withstand frequent opening and closing to ensure long enough service life;

Under normal use, each programmed valve must be switched on and off once in each cycle (about 120 seconds), according to the nitrogen machine 300 working days a year, 24 hours a day, the adsorption and desorption cycle is 4 minutes, then each valve needs to open and close more than 200,000 times a year. The failure of just one valve 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.

Carbon molecular sieve is the core of the nitrogen converter

2.1, carbon molecular sieve performance indicators: a. hardness b. nitrogen production (Nm3/T-h c. Recovery rate (N2/Air); d. Packing density

The above indicators carbon molecular sieve manufacturers have been indicated at the factory, but can only be used as reference data, how to make the carbon molecular sieve play the maximum efficiency, which has a direct relationship with the process flow of each nitrogen manufacturer and the adsorption tower height to diameter ratio, while ensuring the service life of the molecular sieve is very particular.

2.2, carbon molecular sieve loading technology: carbon molecular sieve into the adsorption tower must have a special filling technology, otherwise it is easy to powder and lead to failure, from the process process we can find that when compressed air enters from the bottom of the adsorption tower at high speed, if there is no special gas distributor, the molecular sieve is subject to strong impact and friction of the air flow, which is easy to cause the powder of the molecular sieve. In addition, it is impossible to fill the molecular sieve into the adsorption tower is absolutely tight, after a period of use, the gap between the molecular sieve is decreasing, slowly sinking, if there is no molecular sieve automatic filling device and compression device, there will be obvious space in the upper part of the adsorption tower. 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, friction and impact with the adsorption tower wall, which is easy to make the molecular sieve powder failure.

2.3, the effect of oil and water in the air on molecular sieve: because the air contains a certain amount of water and oil vapor, after the compressor, if not strictly air purification treatment, oil vapor is easy to be adsorbed by carbon molecular sieve, and difficult to desorption, filling the molecular sieve pore size, resulting in molecular sieve "poisoning" failure. Therefore, setting up a strict air purification device before the compressed air enters the adsorption tower is an essential part of ensuring the service life of the molecular sieve. Although water is not fatal to molecular sieve, it will increase the adsorption "load" of molecular sieve, that is, affect its ability to adsorb O2 and CO2, so compressed air drying water removal is a problem that can not be ignored to improve the adsorption capacity and stability of molecular sieve.

3, solution analysis In view of the above problems, SAP has done special research and development, for this purpose, the complete nitrogen system has been carefully designed and arranged, and the complete nitrogen production device contains the following parts.

3.1 System Flow Chart

3.1.1 Air compressor, air compressor is the main part of providing air source, the compressed air first passes into the compressed air purification component after water removal, oil removal into the air purification component

3.1.2 Air purification device 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 most of the water, to ensure the normal use of the freeze dryer and the post-filter, the freeze dryer to force cooling to about 5℃, The water vapor in the air condenses into water, which is separated and filtered through the water separation filter, and discharged by the sewage valve, so that the dew point of the compressed air reaches -10℃, the fine filter filters > 0.01μm particles and oil and water, and then enters the super-fine filter to filter oil and water; Filtration accuracy > 0.001μm, after the active carbon in the oil remover adsorption residual trace oil mist, get clean compressed air through the pipeline into the nitrogen oxygen separation system, to ensure the longevity of molecular use.

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, so as to reduce the system pressure fluctuations, so that the compressed air smoothly through the compressed air purification system, in order to fully remove oil and water impurities, reduce the load of the subsequent PSA oxygen and nitrogen separation device. At the same time, when the oxygen and nitrogen separation system performs periodic work switching, it also provides a large amount of compressed air required for rapid pressure increase in a short time for the oxygen and nitrogen separation system, so that 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 core part of the nitrogen machine, composed of two adsorption tower, compression device, program control valve, and other components, our hospital adopts high-quality imported valves, no leakage service life of more than 3 million times, to provide a reliable performance guarantee for the whole device.

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 provide a stable nitrogen source on site. Summary: Through the above analysis of the scheme, we can have a certain understanding and understanding of the structure and composition of the nitrogen machine, but for different environmental conditions and different process conditions, the equipment will have a certain selectivity in the configuration.