Home >> Industry Knowledge >> 35000m3 / h Nitrogen (Nitrogen Generator) Operating Current Situation and Countermeasures
Maanshan Iron and Steel 35000m3 / h air separation plant mentioned by the French company Air Liquide
For the use of molecular sieve purification, pressurized turbo-expander stream external compression
Cheng; the next column with sieve plate towers, other towers are used packed column; Main
With falling-film and the cold bath duplex-type structure together.
The air separation plant at the end of 1998 officially put into operation, 1999
Year in March to undergo a performance assessment. However, in a continuous operation more than a year later,
Its oxygen and argon gas production began to decline. Despite several optimization transfer
The whole, can not meet design requirements. And the operation in recent years, the
Product yield is drop quickly. The author of the problem on a more personal
The superficial understanding, hope experts hesitate to Fu Zheng 1
1 35000m / h Air Separation Plant Status
An air separation plant design products production (gaseous total): Oxygen
35000m3 / h, nitrogen 40000m3 / h, liquid argon lO00m / h, liquid oxygen
600m3 / h and liquid nitrogen 400m3 / h. Rated air volume 174600m3 / h,
Oxygen extraction rate, while the low rate of extraction of argon.
The air separation plant put into operation since 7 years, in the initial operation
A more than a year time, oxygen, nitrogen output could still reach production, while the liquid
Argon, liquid oxygen and liquid nitrogen production can only meet the design value of 80%. From
Since 2000, the output of various products a declining trend, which
Although many inter-organizational systems repair and optimize the process of adjustment, but this
The downward trend in production has not been brought under control. Particularly over the past 3 years
Years, its products production (total gas) can only be maintained at the oxygen
31500m3 / h
, Nitrogen 38000m / h and argon gas 800m3 / h, while the liquid
Oxygen, liquid nitrogen production can only achieve the original design value of 50%.
From the currently running process and equipment status point of view, a serious deviation from established
Of job status of the situation largely reflected the following aspects: ① Material Air
Plane displacement is obviously insufficient, the average annual only 160000m / h
Left; ② air compressor to the next column after the pressure drop between the up 0.036MPa,
Than the design 0.025MPa; ③ from the current operation, from previous
Optimize operations and increase the production of research outcome, argon, argon production is not
Be able to meet the design standards.
2 Analysis
2.1 The reasons for lack of air compressor displacement
From the entire operation of air separation equipment, point of view, the amount of air into the tower
Annual average of only achieve 160000m / h or so, including both air
Press their own reasons, but also ancillary equipment and its maintenance management .
Specific analysis, mainly in the following aspects.
2.1.1 Air Compressor machines before the total resistance is too large, the suction pressure below the set
Denominated
35000m / h air separation plant is Sulzer compressor matching
Shou's RIK 1 100.4 Centrifugal Compressor. Basic design
Parameters: suction pressure 0.1005MPa, suction temperature of 35 ℃, inhalation
Gas mass flow 64.84kg / s, discharge pressure (nominal)
0.602MPa, Displacement 174600m3 / h, maximum displacement
180255m / h. Machine before the maximum allowable value of total resistance 970Pa, from 3
Parts consists of: aircraft before the muffler pipe resistance machines before the inhalation of pipe
And the suction outlet of the inhalation resistance and resistance of air filter.
The original design of the machine before the air filter is a kind of a drawer-type units Unit
Well-formed filters, all of the drawer-type units installed in a large inlaid in Li
Side frame, each drawer-type filter unit has a rough one before and after the two
Fine filter layer, running resistance interval 200 ~ 600Pa. When the filter
Resistance to meet the design allows the upper limit of running resistance, then replace all
Filtration unit, designed to use cycle of 24 months. However, the actual use,
To be replaced one time per week is simply unable to maintain continuous operation. To
This, special filter in the chamber before the addition of a set of blow bag filter
Device, known as pre-filters, and filter the original filter chamber
Removing all elements of its air filter room only as a channel to use.
Pre-filter design and operation of the resistance of 400 ~ 700Pa. When the resistance reached
To the upper limit, then the automatic purge.
However, such a transformation brought about serious consequences, namely, the Airport ago
Resistance increases, compressor suction pressure drop. Machine before the resistance increases
From two aspects: First, the Airport before the inhalation channel growth increases
The flow of air resistance; second bag filter cap resistance comparison
High resistance of the ceiling when the filter is run, the machines before the total resistance on the
Exceeds the design allowable values. Worse still, the filter cleaning system
Unification failure-prone, repair and maintenance problems, coupled with the quality of filter bags
Also difficult to control, the resistance increased rapidly, and cleaning to reduce resistance to
Use is not good, basic is 3 months to replace a second bag. Notwithstanding
Here, the filter running resistance, or all year round at 650 ~ 800Pa
The case of running a serious beyond the design requirements. So that unit
The suction pressure is much lower than the design requirements (due to the entrance of non-smoking unit
For manometry point, the measured value can not be obtained). As the machine before the suction pressure
Force reduction, it is necessary to achieve the same discharge pressure, flow rate will inevitably decline.
2.1.2 Air Compressor 2 gas seal fragile and leak, airway a large number of
Fouling
Air compressor fouling machine airway is machine operational status before the filter is not
The inevitable result of a good. The dissolution of all previous inspections show that in turn Tao Ye
Cooler air inside and middle side of the plot are a lot of dust, which resulted in
Impeller flow area is reduced and the reduced ability to intercooler heat exchanger, which
These will cause the unit to reduce displacement.
2 gas-sealed easy to damage, is the unit itself, lack of gas-seal design
Trap. 2 gas seal is damaged, the inter-stage leakage occurs, so that the next
Grade inhaled gas to reduce and eventually will reduce the exhaust unit. First
Times less than six months to run after the disintegration of maintenance took place on two gas seal is damaged
Leakage problem, the situation is particularly serious in recent years, have been so happened Yan
Inter-stage heavy surge. Has been re-designed gas seal at that level is expected to Solution
Resolving the issues.
2.1.3 After the resistance of large air compressor machines, exhaust pressure is high, displacement
Reduction
Air compressor to the next tower, after a lot of resistance between the bottom of the system shipped
OK so far have evolved. The initial run, the pressure within the range
Drop of about 0.023MPa, but has now risen to 0.036MPa. The
Result of the increased resistance is: to keep the pressure remains unchanged under the tower
, The unit is necessary to increase exhaust pressure, flow rate will also decrease. Real
The occasion of the exhaust pressure is increased, the next tower pressure decreased.
The increased resistance mainly from two parts: ① molecular sieve length
Period is still in use, it is inevitable there are some plug the zeolite powder produced and stars
Airflow channels between grains, so that when the air pressure drop through the molecular sieve by
Large; ② long-running air cooling tower, the filler that may arise between a
These algae mud and debris generated by packing broken and so will gas flow
Blocked the passage of air pressure drop will increase.
In addition, the air compressor to reduce the other causes of displacement are cool
Water temperature and quality, air temperature. But for this set of air separation plants
, Its impact is not critical.
2.2 The reasons for the low production of argon gas
An air separation plant to run so far, argon gas production has failed to reach the middle class.
Maanshan Iron and Steel has repeatedly organizational systems optimized operation and increased production of argon gas
Research operations, failed to achieve the desired results. Analysis of unit-based
Meter and the actual production conditions that result in production can not fulfill the anti-Ar
The main reason lies in the following areas.
(1) lack of raw materials directly to the amount of air argon reduced yields. Press
The original design, the volume of air into the tower 174600m3 / h case, argon
Gas production of 1000m / h. Into operation when debugging, basic up to production,
However, some reluctantly. After the reduction in the amount of air as the process, argon gas
Lower yields. Now, the air volume of 160000m. / H, argon fraction
Oxygen content was 90.5%, the crude argon volume of 820m3 / h, operating conditions
Far from ideal.
(2) The design of the low extraction rate of argon, argon system surplus capacity
Small. By design, parameter calculation, the original design of the argon extraction rate is only
About 61%, compared with foreign advanced level was low. In addition, according to Chang
Regulations, in the design and manufacture of spare time have left a certain capacity to meet the
Increase run-time requirements and make up for equipment life cycle due to aging
Er Shi performance degradation defects. However, according to the actual research operation experience,
Design capacity of the reserved surplus clearly inadequate.
2.3 Other reasons
(1) The distillation system leaks. Mainly falling-film cycle of the main cold
Gas-liquid oxygen pump seal leakage. The possible reasons for such a situation caused by the main
Is the poor performance of pump seal, seal gas pressure due to end in a sealing system
Low power and so on.
(2) The original design did not then the increase in liquid oxygen cycle adsorption system
Switching operation so that an air separation plant cold damage increases, but also increases fluid loss
Consumption. Liquid oxygen cycle adsorption system for drawing air separation plant explosion in Indonesia
The lessons of the accident, while in the latter part of the increase in the building of a security measure.
In ensuring security at the same time, has also brought these issues.
(3) The cooling water system problems are the factors that reduce yields
One. The actual operation process, the cooling water quality is poor, the summer water
Temperatures are high, since the clear filter failure can not be removed from the resulting flow
Road congestion Ershi smaller amount of water and so on, is also a video port to the factor.
3 the proposed improvement measures
(1) The transformation of machine pre-piping and filters, to allow the plane before the
Total resistance effectively reduced to 970kPa below, and to filter off
Filter results to meet the quality requirements of gas inhalation.
Can be used easy to use, reliable operation and effectiveness of a clear cleaning
Cartridge-type paper air filter to ensure the filtering effect. On the machine before the Department of
Unification of resistance to analysis and research to meet the plane before the inhalation of the total resistance
Cases, the re-arrangement of machines before the facility could be the export of the original filter chamber
The former facilities, demolition of all the exports of the new filter into the air compressor directly
Mouth muffler pipe connections to allow the plane before the total resistance down to 970kPa
Below. Only in this way can the conditions of inhaled air compressor to meet the design
Requirements. In addition, the inhalation of clean air, the machine leaves alternately Road and heat transfer
Fin fouling also greatly reduced. These measures will effectively eliminate
Inhalation of insufficient pressure on the compressor displacement effects.
(2) The elimination of air compressor to the next column after the pressure drop between the result of too much
Su. ① Bachu molecular sieve and alumina, re-sifting, or replaced with new
, The elimination of the resistance caused by molecular sieve adsorber increases; ② Cooling Tower
Internal inspection, replace or clean fill, and wire mesh mist eliminator to remove within a
Pieces of debris, air-cooling tower to eliminate the accumulation of mud or debris caused by algae
Increase the resistance; ③ ensure molecular sieve adsorber adsorption effects, Caine
Holding an annual heating system 1 in order to eliminate possible to take people dioxide
Carbon caused by increased resistance. Reduce the machine to the next tower, after the increase in resistance
Force, increasing unit displacement.
To strengthen water quality monitoring, so as to meet the original design requirements; for the Department of
Unification overhaul, eliminating liquid oxygen pump, air compressor gas seal leakage, etc., and start
The end to maintain its integrity.
Process operation to strive for excellence, courage to break the original design, excellent
Of each process parameter, so that machine is running at its best.