Characteristics and maintenance of nitrogen generator

Principle of PSA nitrogen production

Carbon molecular sieve can simultaneously adsorb oxygen and nitrogen in the air, and its adsorption capacity also increases with the increase of pressure, and there is no significant difference in the equilibrium adsorption capacity of oxygen and nitrogen under the same pressure. Therefore, it is difficult to separate oxygen and nitrogen effectively only by the change of pressure. If the adsorption rate is further considered, the adsorption characteristics of oxygen and nitrogen can be effectively distinguished. The diameter of oxygen molecule is smaller than that of nitrogen molecule, so the diffusion speed is hundreds of times faster than that of nitrogen, so the adsorption speed of carbon molecular sieve for oxygen is also very fast, and the adsorption can reach more than 90% in about one minute; At this time, the adsorption capacity of nitrogen is only about 5%, so at this time, oxygen is mostly adsorbed, and the rest is mostly nitrogen. In this way, if the adsorption time is controlled within 1 minute, oxygen and nitrogen can be initially separated, that is, adsorption and desorption are realized by pressure difference, adsorption when the pressure increases and desorption when the pressure decreases. The difference between oxygen and nitrogen is achieved by controlling the adsorption time, which is controlled very short. Oxygen has been fully adsorbed, while nitrogen has not yet been adsorbed, so the adsorption process is stopped. Therefore, pressure swing adsorption nitrogen production should have pressure changes, and the time should be controlled within 1 minute.

Characteristics of PSA nitrogen production

(1) Nitrogen generation is convenient and fast:

Advanced technology and unique air distributor make the air distribution more uniform. Carbon molecular sieve can be used efficiently to provide qualified nitrogen in about 20 minutes.

(2) Easy to use:

The equipment is compact in structure and skid mounted as a whole. It occupies a small area and does not require capital investment. It requires only a power supply to produce nitrogen on site.

(3) More economical than other nitrogen supply methods:

PSA process is a simple nitrogen production method, which uses air as raw material and consumes only the electric energy consumed by the air compressor. It has the advantages of low operation cost, low energy consumption and high efficiency.

(4) Electromechanical integration design to realize automatic operation:

The imported PLC controls the fully automatic operation. The purity of nitrogen flow and pressure can be adjusted and continuously displayed to realize unattended operation.

(5) Wide application range:

Protective gas for metal heat treatment process, gas for chemical industry production and nitrogen charging and purification of various storage tanks and pipelines, gas for rubber and plastic products production, oxygen discharging and fresh-keeping packaging in food industry, purification and covering gas in beverage industry, nitrogen charging and oxygen discharging of nitrogen charging packaging and containers in pharmaceutical industry, protective gas for electronic components and semiconductor production process in electronic industry, etc. The purity, flow and pressure are stable and adjustable to meet the needs of different customers.

The maintenance of nitrogen generating unit system mainly includes the maintenance of air compressor, cold dryer, filter and nitrogen generating host. Routine maintenance of air compressor mainly includes:

1. The air compressor shall be regularly maintained, and the air filter, oil filter and engine oil shall be regularly replaced by the manufacturer according to the instructions.

2. The refrigerant pressure of the cold dryer shall be checked regularly to ensure timely replenishment. The dust of the radiator shall be purged with compressed air every day. The filter element shall be replaced regularly, normally 8000h, depending on the specific situation and pressure difference.

3. Open the drain outlet of the air storage tank once a day to drain the condensed water in the air.

4. Check the automatic drainer every day to avoid blocking and losing the drainage function. If it is blocked, slightly open the manual valve, close the self draining valve, and then remove the automatic drainer for disassembly and cleaning. When cleaning the automatic drainer, use soap foam to clean it.

5. The nitrogen generator mainly checks the working pressure, purity and flow of the adsorption tower and makes records.

6. It is generally recommended to replace the activated carbon in the activated carbon filter once a year.

7. If the silencer emits black smoke, it means that the molecular sieve is powdered. Stop the machine immediately for maintenance.

8. The nitrogen analyzer shall be calibrated regularly, and it is recommended to calibrate once every half a year.

9. Check the sensitivity of pneumatic valve and solenoid valve. The abrasion of pneumatic valve affects the purity of nitrogen, which belongs to vulnerable parts.

10. The safety valve shall be calibrated at the boiler inspection institute every year.