Collect now! Common problems and treatment of nitrogen generators whose purity is not up to standard (Part 2)
As we all know, the purity of the nitrogen generator is crucial to production. Impurity of nitrogen not only affects the appearance of welding, but also leads to product oxidation and process defects, and even causes major safety hazards in the chemical and fire extinguishing industries.
The previous article “Common Problems and Treatments of Non-standard Purity of Nitrogen Generators” shared the relationship between nitrogen impurity in nitrogen generators and mechanical failures of the equipment itself and supporting systems, as well as the resulting impacts and solutions. In this article, we We will further share dry goods from external factors: the influence of equipment operating environment temperature, compressed air dew point (moisture content), and compressed air residual oil on the purity of the nitrogen generator and equipment performance.
1.
Nitrogen-generating equipment is designed with the stable working environment of the equipment in mind, usually in the range of 0-45°C, which means that the equipment can perform normally within this temperature range. On the contrary, if it is operated outside the designed ambient temperature, it will bring problems such as performance degradation and high failure rate.
When the ambient temperature exceeds 45°C, the exhaust temperature of the air compressor will be too high, which will increase the load on the freeze dryer. At the same time, it may cause the freeze dryer to trip at high temperature. The dew point of the compressed air cannot be guaranteed, which will seriously affect the nitrogen generator. effect. Under the premise of the same purity, the flow rate of nitrogen production will drop by more than 20%; if the flow rate of nitrogen production remains unchanged, the purity of nitrogen gas will not meet the design requirements. Through laboratory high and low temperature testing, we found that when the ambient temperature is lower than -20°C, some electrical accessories cannot be started, or the action is abnormal, which will directly cause the nitrogen generator to fail to start and work.
solution
To improve the environment of the computer room, the ventilation system should be improved in summer, and the heating conditions should be increased in winter to ensure that the ambient temperature of the computer room is within a reasonable range.
2.
The moisture content (pressure dew point) in the compressed air has a direct impact on the nitrogen generator/carbon molecular sieve, so the nitrogen generator has strict requirements on the quality of the compressed air at the front end.
The actual case of the impact of the water removal and water separation effect of the cold dryer on the nitrogen generator:
Case 1: A user did not install an automatic drainer on the air storage tank of the air compressor, and did not drain water regularly, resulting in a large moisture content in the air intake of the cold dryer, and the third-stage filter at the air inlet and outlet of the cold dryer did not install a drainer And regular manual drainage, resulting in super high water content in the system, causing the activated carbon filter installed at the rear end to absorb water and form blocks to block the compressed air pipeline, and the intake pressure is reduced (insufficient intake), resulting in the purity of the nitrogen generator not meeting the standard. The problem was solved by adding the drainage system after the transformation.
Case 2: The water separator of a user’s cold dryer is not good, resulting in the cooling water not being separated in time. After a large amount of liquid water enters the nitrogen generator, 2 solenoid valves are broken within a week, and the inside of the angle seat valve piston is completely damaged. It is liquid water, which causes the piston seal to corrode, causing the valve to operate abnormally, and the nitrogen generator cannot work normally. After replacing the freeze dryer, the problem was solved.
1) There are micropores on the surface of the carbon molecular sieve, which are used to adsorb oxygen molecules (as shown in the figure). When the water content in the compressed air is too heavy, the micropores of the molecular sieve will shrink and the dust on the surface of the molecular sieve will fall off, which will block the micropores of the sieve and cause the unit weight Carbon molecular sieves cannot produce the nitrogen flow and nitrogen purity required by the rating.
It is recommended that users install an adsorption dryer at the inlet of the nitrogen generator to reduce the water content of the compressed air and ensure that the carbon molecular sieve is not polluted by heavy oil and heavy water. Generally, the service life of the molecular sieve can be extended by 3-5 years (according to the purity level).
3.
Effect of oil content in compressed air on nitrogen generator/molecular sieve:
1) For any type/form of molecular sieve, the unnecessary components are screened out through the micropores on the surface of the molecular sieve to obtain the substances we need. But all molecular sieves are afraid of oil pollution, and residual oil pollution is completely irreversible pollution to molecular sieves, so the inlet of the nitrogen generator has strict oil content requirements.
2) As shown in the figure above, oil stains will cover the micropores on the surface of the molecular sieve, causing oxygen molecules to be unable to enter the micropores and be adsorbed, resulting in a decrease in nitrogen production, or under the premise of ensuring the original flow rate, the nitrogen purity will be unqualified within 5 years .
Improvement methods for the above problems: Pay attention to the ventilation of the machine room, reduce the ambient temperature, and reduce the amount of residual oil in the compressed air; strengthen protection through cold dryers, suction dryers, filters, and activated carbon degreasers; regularly replace/maintain the front-end equipment of the nitrogen generator, Ensuring the quality of compressed air can greatly protect and extend the service life of nitrogen generators and the performance of carbon molecular sieves.
4.
To sum up: external factors such as the ambient temperature of the machine room, the water content and oil content of the compressed air will affect the performance of the nitrogen making equipment, especially the cold dryer, suction dryer and filter at the front of the nitrogen making machine will directly affect the nitrogen making equipment. The use effect of the nitrogen generator, so the choice of high-quality and efficient dryer equipment is particularly critical for the nitrogen generator.
Many nitrogen generator manufacturers do not produce front-end compressed air purification equipment. When the nitrogen generator system fails, it is easy for nitrogen generator manufacturers and dryer manufacturers to shirk each other and not take responsibility for each other.
As an excellent supplier of compressed air system products, EPS has a complete product chain, which can provide customers with a complete set of equipment such as cold dryers, suction dryers, filters, nitrogen generators independently developed and manufactured, high-quality Compressed air purification products are equipped with high-quality nitrogen generators, so that customers can buy and use with confidence!