Home >> Industry Knowledge >> Nitrogen Generator (Nitrogen Equipment) Vibration analysis and treatment of high

The two sets of air separation equipment, respectively 10000m / h switch heat exchanger since the removal process
Air separation equipment, and 14000m / h Air Separation Plant molecular sieve purification process.
10000m / h air separation plant complete drum production, Shen DH. 80 Air
Machines; 14000m / h air separation plant supporting two air compressors: respectively,
Shen drum production DH. 80.20-type air compressor and the Hang oxygen production 5TYD. 160
-Type air compressor.
In 2004, DH. 80.20-type air compressor 3 consecutive times due to shaft vibration
Moving high value of parking, the follow-up system, high load impact.
Large air compressor unit appears the problem of high axial vibration value is part of the general
Elephant, but the value of each unit appear shaft vibration is not the reason for the high-phase
The same. Here in the repair air compressor in the process of experiences and lessons learned
A brief summary for the peer reference.
1 Failure
In 2004, DH. 80.20-type air compressor in the first overhaul of the
Ago, the air permeability of a ~ 4-axis vibration values are high, in Table 1. Demolition review
Found that two to four impeller fouling phenomena to varying degrees, of which three
Impeller fouling more. Units have been in operation at that time to consider a year, there are plot
Polymer is a normal phenomenon, not caused a high degree of attention, only a
Conventional impeller cleaning, replacement of defective bearing and so on.
After the first overhaul to start air compressor, was found at all levels of axial vibration value
Are high. One or two-axis vibration value of 69 ~ 81pm, 3,
Run 1 weeks 4 rear axle vibration value reached 106pm (full range),
Over interlock value (the value chain: 1, 2 96ttm, three, four
Class 88pm). Found during the second overhaul three impeller fouling Yan
Heavy, in just 1 week, the impeller fouling to 30mm. Scale Body
Black red and very hard, body composition scale in FeaO content
84%.
After analysis, the three serious and two impeller fouling the air cooling
It is directly related to devices with water. When a second repair on a ~ 3
Cooler wick, shell and air flow channel carried out a thorough clean-up.
Table 1 DH-type air compressor for the first time a 80-20 front axle repair vibration value m
1 2 3 4
The level of the level of vertical vertical vertical level of the level of vertical
2004-02.01 6,161,615,723,213,736
2OO4.02.10 60 72 66 57 24 23 38 38
2OO4. O2.20 65 73 65 61 28 27 42 43
2OO4.03.01 64 65 58 61 27 25 36 36
2OO4.03.10 66 75 67 59 33 31 44 46
2OO4.03.20 60 73 69 55 35 31 47 49
2OO4.04.01 65 73 63 61 32 29 45 47
2OO4.04.10 66 74 66 62 39 34 52 53
2OO4.04.19 69 75 62 66 74 65 79 94
2OO4.04, 20 68 74 61 65 78 69 87 103
After the second repair to start air compressor, one, two-axis vibration value
≤ 24 m, 3, 4-axis vibration value of the rapid rise within 1 week on rising
As high as 106 ~ m. The third repair was found two gas cooler top
Department of stagnant water, analysis of the reasons is the two gas cooler, the lower part of
Short-circuit board air seal damaged, part of the air from the cooler at the bottom of the short
Road, water was brought into the impeller, an increase in the water part of the process of water
Back to the cooler at the top. And two cooling wick pickling of partial
At the end, cooler wick in the fouling and water together in the impeller
, Which leads to higher value-axis vibration. When the third overhaul, re-2
Grade cooler wick for pickling, as well as short-circuit seal plate cooler
The replacement, transformation.
After the third overhaul open air compressor, at all levels of axial vibration values are ≤
32 belly m, an evident result.
2 Analysis
2.1 The poor performance of air filters
The original use of pulse bag filter air filter precision partial
Low, small dust into the compressor, the air humidity is large,
Especially in the air cooler condensate flow discharge poor or short-circuit
With water, moisture and dust formed on the dirt at the impeller.
2.2 intercooler and the level of serious inter-pipe corrosion
Inter-stage air intercooler and pipes made of carbon steel, the atmosphere contains hydrogen sulfide and carbon dioxide and other acid gases, if they are
The air with one air cooler, in the cooler condensation of water within the existing
Cases, exacerbated the corrosion of carbon steel, corrosion material washed off leaves
Wheel and attach to the impeller, the destruction of the rotor balance, shaft vibration plus
I.
2.3 impeller fouling. Lead to shaft imbalance
Working conditions at all levels of the air cooler is different from condensate produced
Different amount of condensation water was brought into the impeller in the volume and the possibility of a different, ·
Therefore, at all levels, the chance of different impeller fouling. Impeller fouling materials in high -
Speed rotation that can easily fall off, for such high-speed rotation of the unit while.
Statement, balance the amount requested is less than lg, so a small impeller fouling,
Both may lead to shaft imbalance, shaft vibration value is higher.
2.4 short-circuit air cooler air seal plate damaged
Air cooler air short-circuit boards with the original thickness 0.2mm, width
25.4mm of copper. The copper, once damaged, would result in gas to go
Short circuit, the impact effect of heat transfer. If the lower part of the sealing air cooler
Board is damaged, will lead to short-circuit flow of condensate into the impeller to accelerate the
Impeller fouling, leading to shaft imbalance.
Three treatment measures
3.1 The transformation of air filters
Import filters from the air pulse bag filter to self-cleaning
Filters, whose characteristics: filtration accuracy of ≤ 2 m, filtration efficiency "
99.99%, the normal running resistance 150 ~ 650Pa, and the resistance of ≥
1100Pa automatic alarm; filtration resistance of large rooms can be online is more
Exchange cartridge, without restrictions on the main system operation and easy maintenance.
3.2 intercooler and inter-stage treatment of severe pipe corrosion
Intercooler using carbon steel, the internal rust layer through a long
Period of wear and tear, corrosion, almost all off, because every review
Repair time is limited by the overall progress of repair constraints, a short time can not be
All re-corrosion Moreover, anti-corrosion layer is not fully dry, prone to
Shedding phenomenon. An approach is cooler for pickling:
The use of detergents and water mixture dubbed in 5% ~ 10% of the solution, plus
Into 3 ‰ corrosion inhibitor and an appropriate amount of inhibitor (about 3%. 5%.), Oxygen
Agent (about 3 ‰ ~ 5 ‰), cleaning strictly control the concentration of hydrochloric acid
And temperature. In addition to pickling cooler wick, but also the use of high temperature and high
A thorough steam pressure steam blowing fin, brass and copper attached to the bio-adhesive
Mud. Slightly alkaline aqueous solution with the device in and the residue in the pickling bath
And back off; then wash equipment, bring out the pickling process of shedding
Down impurities.
3.3 Short-circuit air cooler air seal plate repair and modification
Overhaul the process found that: two air cooler at the bottom, on the
Division and the side were 400mm × 20ram, 200mm × 20mm and the
300mm X 15mm short of the three gas seal plate is damaged, leading to
Without a cooler air directly from the short-circuit seal plate Agency into the next '
Stage impeller; and the air cooler at the bottom of the seal plate is damaged leading to cold
Condensate water was flow into the next one impeller, and dust, rust off things
Together formed a dense fouling layer, accumulate in the impeller, causing
Excessive vibration of the shaft unit.
Deal with the problems were handled as follows: ① the air short -
Lu = 0.2mm from the seal plate = 0.5mm of copper into the non -
Rusty steel plate, enhanced seal strength; ② replacing all the seal plate; ③ Yan
The cooler the installation of wick the quality to ensure the seal plate mounted on the core
Sub-sealed tank, to avoid the seal plate tilt, deformation.
3.4 two additional air cooler condensate discharge port
Air cooler with two 15mm lower part of the balance of holes,
Balance hole location are living below the gas out of coolers. Given the strategic location
Relations, from the balance of holes through the entrainment of air over the possibility of condensate
Great. To avoid this problem, the emergence of an increase in the outlet side DN50mm
The discharge tube, as shown in Figure 1.
In addition, the deformation of repair cooler wick fins, and clear the air
Channel, increasing the heat transfer area, reducing pressure loss.
Of the original drainage
Figure 1 Figure 2 air cooler substructure
4 treatment effect
DH. 80.20-type air compressor data comparison before and after the third maintenance
Table 2.
Table 2 DH-80 · 20-type air compressor data comparison before and after the third maintenance
Ye Kai-degree temperature conductivity gas inhalation volume 1 2 3 4
Time
/ ℃ /% / (m / h) the level of vertical levels of the level of vertical vertical vertical levels
2OO4-05-28 25 l00 48715 l5 22 l7 24 69 83 89 l03
Maintenance ago
2OO4-05-30 24 l00 50202 l5 2l l7 24 lO6 lO6 90 lO6
2OO4 1 O6-23 30 l00 53740 8 l2 9 l3 10 7 30 3l
After overhaul 2OO4.07-02 30 l00 54300 8 l2 9 14 10 7 32 23
2005 1 O6-28 33 l00 5350o l6 l8 l9 20 l3 26 26 32
As can be seen from Table 2: In the guide vanes fully open, the temperature of the same
Under the overhaul of the gas after the compressor increase of at least 4000nl / h,
Shaft vibration has been maintained at 32 m below. At present air compressor has stabilized
More than a year to run a good effect for the production of the system's high load, steady
Set to run and laid a solid foundation.
5 lessons
(1) the maintenance time is so short, only taking into account the issues
Maintenance, the lack of the necessary system maintenance, the result left corner, repair
Large amount of rework. In the air compressor unit of the maintenance process, the need for a comprehensive
Detailed investigation from the air compressor impeller if any, between the entrance to a ring
Section, to avoid the trade-off.
(2) the causes of high value-axis vibration analysis is not comprehensive enough, the need
Strengthen the impeller fouling a rational and comprehensive understanding.