Home >> Industry Knowledge >> Nitrogen Generator (Nitrogen equipment) manufacturing technology
Preface
China is a large population and little arable land per capita
Countries, to solve the food problem concerning people's livelihood, it is necessary large
Force the development of fertilizer industry, improve fertilizer (especially nitrogen) production,
In order to meet the needs of agricultural development.
Production of raw materials for fertilizer nitrogen and hydrogen gas. Nitrogen can be empty
Sub-devices, hydrogen from oil or coal-water slurry pressurized gasification was followed by
Take. From oil or coal-water slurry pressurized gasification gas obtained by the raw materials,
Primary components of hydrogen containing carbon monoxide and carbon dioxide, but there is
Harmful impurities. These impurities cause the tower in the synthesis gas catalyst "in
Poison "and failure. Therefore, 'raw materials entering the reactor before the hydrogen is bound to
Must undergo a decontamination process to make carbon monoxide and carbon dioxide and other impurities
The total content of no more than 10X 10 ~.
Raw hydrogen purification, usually copper-ammonia liquid absorption, A
Alkylation method and liquid nitrogen washing method. In which washing liquid nitrogen method, not only removing a
Carbon dioxide and carbon dioxide and other harmful impurities, but also removal of methane
And argon gas can be inert gas content of less than 100 X 10's
Of nitrogen and hydrogen mixture. High purity of product synthesis gas to make hydrogen, nitrogen
At the time of consumption of ammonia close to the theoretical value, and greatly extend the reminder
Agent's life. Especially in the coal or residual oil as raw materials, they often work
Works with empty sub-equipment, the removal of acid gases using low-temperature methanol
Wash. At this point, using liquid nitrogen washing method to removal of carbon monoxide is not only energy-saving
Energy, and the more economical and reasonable, they are often recommended.
Washing liquid nitrogen cold box is the main equipment of liquid nitrogen wash process, in which packets
Including nitrogen wash tower, plate-fin heat exchangers as well as other tank, tanks, meters,
Regulating valves and pipelines and so on, the cold box device at low temperature (1 193 oC),
Medium-pressure (5.2MPa) environment, run under medium is flammable, explosive
The high hydrogen and volatile materials. "Tenth Five-Year" period, the State Economic and Trade
Committee has organized experts to "15" major technical equipment, "large-scale
Fertilizer complete sets of equipment development project "carried out feasibility study. The project
The "washing liquid nitrogen cold box design and development of the topic" by the State Economic and Trade Commission
Approval, agreed to Lu Hengsheng Chemical Co., Ltd. Shandong, China Oil changes
Coal Expansion Project in the liquid nitrogen wash cold box to support projects, a "liquid
Localization of nitrogen wash cold box "research.
A nitrogen wash tower manufacturing
1.1 The manufacture of nitrogen wash tower pre-selection argument
The manufacture of washing liquid nitrogen cold box, from Hangzhou Oxygen Company Limited (in
Hereinafter: Hang oxygen) to take, cold box of the key equipment - nitrogen wash
Tower, although its internal structure and the air separation distillation column similar to the high tower
18m, but the tower design pressure of 5.8MPa (air separation distillation column internal
The design pressure is only 0.7MPa). For such a high pressure, nitrogen
Washing tower austenitic stainless steel materials, whether elected or aluminum? China
Huanqiu Chemical Engineering Corporation and Hangzhou oxygen was repeated demonstration made
Three kinds of programs.
1.1.1 All materials, use of aluminum-magnesium alloy tower
Advantages: ① imported from Linde AG of Germany, and has matured
In the application of air separation distillation column more than 20 years of "aluminum Sieve
Manufacturing Technology "applied to the manufacture of nitrogen wash tower, tower has the use of performance
Guarantees; ② tower shaped pieces of aluminum to produce the required profile, the domestic are
Had produced complete specifications.
Need to solve the problem: Domestic only produced thin-walled (≤
30mm), low (P ≤ 0.7MPa) aluminum sieve plate distillation column, right
Nitrogen wash tower in thick-walled (= 64ram), small-diameter (=
1200mm), high-intensity (5083) the manufacture of aluminum alloy shell, such as the
Simplified volume system, at both ends of head forming, welding and nondestructive testing
And so on, are in need of manufacturing technology research.
1.1.2 All materials used austenitic stainless steel tower (0Grl8Ni9)
Advantages: ① stainless steel, high strength, a thin shell relative
Point; ② shell head, simplified manufacturing technology is mature, there is no technical
Operation issues; ③ tower functioned relatively safe and reliable.
Need to solve the problem: ① there is a big manufacturer of stainless steel tower parts of
Problems (such as: sieve plate of the red system, school equality); ② Manufacturing tray support
Stays ring shaped profile has yet to be developed; ③ nitrogen wash tower of stainless steel and aluminum
System of plate-fin heat exchangers need to use a reliable connection to stainless steel and aluminum alloy
Conversion connector transition, such large-caliber adapter not the current domestic
There are manufacturers able to produce, to be imported; ④ Because austenitic stainless steel and aluminum
Magnesium Alloy difference between linear expansion coefficient of a larger (about a difference of 31%),
Using different materials, the issue of compensation prominent cold, cold-box pipeline
Design of the question of compensation, such as cold not handled properly, will build equipment or piping
Into the local stress concentration, easily lead to fatigue damage of equipment or pipeline
Or leakage.
1.1.3 use of austenitic stainless steel shell, which pieces of aluminum
Materials
Advantages: ① Column used to introduce special Linde AG from Germany
Technology, manufacturing, size precision, good quality; ② strength of the shell using
Gao, manufacturing technology, mature austenitic stainless steel tower operation
Safe and reliable.
Need to solve the problem: ① manufacturing (with the shell welded) tray support
Stays ring shaped profile to be developed; ② temperature of nitrogen wash tower
266 ℃, stainless steel shell with aluminum parts in the different coefficient of thermal expansion
Aluminum plate will affect the level of degree, endangering the use of nitrogen wash tower
Can; ③ stainless steel shell with aluminum plate-fin heat exchanger connected the same
You need to use and reliable stainless steel and aluminum adapter transition, dealing with non -
When the same device or pipe can cause fatigue damage or leakage.
Taking these, Hang oxygen that the use of nitrogen wash tower aluminum structure, fluid
Nitrogen wash cold box in the overall design of the system leakage, cold compensation
And inner parts of the processing problems, can get a better solution. For
Small-diameter thick-walled, high-strength aluminum alloy shell manufacture, may be in the original
Aluminum shell manufacture of air separation distillation column based on the experience, and then through the thick-walled
Shell manufacturing technology research, it was entirely sure of this technology difficult to overcome
Off. Therefore, the first China-made nitrogen wash tower of selected aluminum structure.
December 2001 29 13, in Beijing's "15" big
-Type fertilizer complete sets of equipment development project feasibility study report on the feasibility studies
, The Hang oxygen on some experts in "nitrogen wash tower structure using aluminum
The main problems is to create a thick plate used and the corresponding forging,
There is currently a lack of accurate mechanical performance parameters, to bring difficulties to the design
Difficult "to the participating experts: Hang ethylene oxide according to ASME standard design
Cold box, a number of large aluminum flange aluminum forgings produced by the Southwest.
Although China's current shortfall of aluminum vessel design standards, but the early HangYang
The 20th century, early 80s, with the German co-production of air separation Linde AG
Equipment, had been the introduction of aluminum vessel design standards (Germany
AD specifications), and now the U.S. ASME specifications, Japanese JIS standard
Quasi-able reference, I believe as long as the aluminum processing plant, nitrogen washing device is located
Dollars, manufacturing units complement each other, combined with nitrogen washing device prototype, to take
The corresponding mechanical data, will be able to meet the design requirements, while
The preparation of our own design specifications of the aluminum alloy welded containers. 2002
Years, the National Standardization Technical Committee of the pressure vessel organization of a single
Bits of specialists have compiled JB / T 4734-2002 "welded aluminum tolerance
Device ", and was implemented in March 2003.
1.2 Nitrogen Wash Tower Manufacturing Technology
Hangzhou Oxygen nitrogen wash tower for a small diameter, thick-walled, high-strength aluminum alloy
Gold shell manufacturing, mainly carried out four aspects of manufacturing technology research.
1.2.1 large thickness, high strength aluminum alloy welding technology research
As the aluminum thickness, welding current will be increased, weld
Metal grains will become thick and mechanical properties of weld, there may be
Reduce. As the thickness increases, the lack of penetration weld, interlayer
Is not fusion, as well as a mixture of defects such as pores or cracks easily produced
Health. To ensure that nitrogen wash tower thick-walled aluminum welding quality, Hang oxygen to
A number of welding and welding test evaluation. In the welding test, the product system
Making and testing, take the following measures:
(1) The acquisition, use matching welding machine, welding lifting frame and welds
Then roller frame and so on welding equipment.
(2) welding using reasonable, and the smaller current and appropriate
Welding speed to control the welding hot energy.
(3) using thin-layer multi-pass welding, rational design of welding groove, welding
Then the order to avoid incomplete penetration welds between layers without defects such as fusion.
(4) to strengthen clean-up work to minimize the resulting weld
Defects such as inclusions and porosity generation.
(5) to strengthen the control of the temperature between layers, so that weld pool in a relatively co -
Completed within reasonable temperature crystallization process, and to gain a better
Mechanical properties.
(6), layered weld quality inspection: the welding seam to 1 / 2 or
1 / 3 of thickness on the x-ray examination. Any defects immediately
Rework, in order to avoid large thick seam welding seam was found missing after the completion of
Trapped in the deepest of the cosmos created by the Department of the amount of rework, the resulting welding
Deformation affecting the product quality.
(7) on the different structures, using different welding methods
Such as: double-sided MIG automatic welding; melting polar melting plate plus half of
Automatic welding grounding, melting polar automatic welding cover; twin pairs
Hand side vertical position welding Tungsten inert gas arc bottoming, melting polar semi-automatic or fully automatic
Welding coverage. The same time, the above-mentioned welding methods and welding test
Pieces, all the mechanical performance testing to ensure that the weld strength.
1.2.2 Small-diameter, thick-walled and high-strength aluminum alloy head forming techniques
Operation research
Due to the high-strength aluminum alloy extension rate of only ordinary carbon steel
1 / 2, austenitic stainless steel 1 / 3,, at room temperature deformation of more than
10% of the cracks will appear. Thus, small diameter, thick head of adult
Shape can not be carried out at room temperature, must be heated to increase plasticity before
Carried out. But the heating temperature is too high, head forming the amount of wall thinning on the
Very easy-tolerance; heating temperature is too low, forming Shiyou prone to cracking
Pattern, so head forming temperature range is very small, forming more difficult.
In order to overcome small-diameter, thick-walled head forming difficulties, Hang oxygen on
The existing heating equipment technological transformation, while the acquisition of Yuan-hong
External thermometer device, in the head blanks heating temperature, insulation and suppression of
Process, the accurate measurement of workpiece temperature, according to the temperature control of workpiece
Deformation degree, fractional Road will be closed to the first heating, compaction.
1.2.3 Small-diameter, thick-walled and high-strength aluminum alloy cylinder manufacturing technology
Operation research
Nitrogen wash sieve plate tower installation level degree (ie, sieve-plate and column
Body axis vertical degrees), is directly related to nitrogen washing effect of the nitrogen wash tower.
The sieve plate of the installation, based on shell barrel as a benchmark, so the circular cylinder
Degrees and the straight line have a higher degree of technical requirements. However, this small diameter, thick '
Wall cylinder roundness, straightness, and weld the wrong side of their counterparts in the amount of control is more difficult
System. In order to ensure the quality of cylinder manufacturing, Hang oxygen to the corresponding work
Art measures.
(1) the original CNC underwater plasma cutting machine for technical
Transformation, to solve problems cutting thick aluminum plate.
(2) The cylinder section blanks cut the material by the plasma, after the plane side
Machine, the blanks surrounding plasma cutting heat-affected zone after the plane off; with the
Control blanks when the length, width and diagonal length, in order to ensure that the roll after the
Tube section diameters precise, each tube section of two-port parallel tube sections then
After a long tailor-welded tube straightness error is less than 1 / 1000, and the total length of error
Difference is less than 10ram.
(3) to control the roundness of the barrel, reducing the longitudinal seam in the vicinity of the edges and corners
(Straight edge), to prevent rolling generated when the amount of wall thinning in ultra-poor, Hang oxygen through the
Rolling tests, using 120ot hydraulic press molding pre-bent tube section blanks
The direction of rolling around the ends, and precise control with a model pre-bent shape,
Then in the prior approval of the technical transformation, NC operation control system
60mm 4-roll Bending Machine roll round.
(4) melting of polar head automatic welding machines and wire feeder
Be modified to reduce the welding wire feed plate, the plate and the welding head of the
Put down your fixed position, so that head and be able to wire into the small-diameter tube plate
The body welding.
(5) To reduce the cylinder volume cooling for hardening and residual stress, Hang
Of oxygen in the cylinder section rolling, longitudinal seam welding, add an annealing process,
Rolling the school and then it won, so as to effectively prevent a small diameter,
Section of thick-walled aluminum cylinder rolling at room temperature micro-cracks.
(6) The design and manufacture of specialized welding counterparts to control the wrong side of Correction
System, welded tube sections take a long ride when the wrong side of the amount of girth.
(7) cylinder girth melting polar gap-free automatic TIG welding
Then, thus ensuring that the full length of the tube straightness, but also improved the girth weld
Then the work efficiency.
1.2.4 Nitrogen scrubber assembly technology research
Tata nitrogen within the washing parts, such as the blister of the blister tray, sieve tray larvae L
Of the orifice plate, are a direct impact on effectiveness of key components of nitrogen wash.
Hang full application of oxygen introduced from German Linde air separation distillation system
Making technology production, but in thick-walled, small diameter cylinder body assembly,
Pressure test and so on, or the emergence of new manufacturing challenges.
(1) Because nitrogen wash tower cylinder wall thickness, diameter and small, and some parts of
Welders could not melt in the cylinder body to implement a very auto-welding, for example:
Cylinder ends connected with the medial head girth, put a welding cylinder body
Machine, there is no welder welding position. To this end, Hang oxygen for different node
Structure, and different locations, using different welding methods, such as the bottom of the head
Connection with the cylinder girth, using double-sided manual tungsten inert gas arc-li
Welding grounding, and then at the outer cover with the melting polar automatic welding; while the top
Department of Head and simplified connectivity girth, because welders can not enter the tower,
Therefore, the inside ring seam plate with melting, with melting in the outer ring slit
Most semi-automatic welding grounding again after melting polar automatic welding cover
Cover. Some take over with the thick-walled cylinder, head of the connection, using double
Double-sided manual tungsten inert gas arc welding grounding legislation, melting polar semi-automatic welding
Way to cover the weld.
(2) thick-walled weld inspection, generally use a single x-ray instrument
Detect single-wall projection, but the nitrogen wash tower at the top of the head and cylinder
Connecting ring seam detection, x-ray machines or people can not enter the cylinder
, The Hang oxygen use high-power x-ray device, in the outer cylinder, mining
With double-wall single-projection method to detect weld quality.
(3) nitrogen wash tower air pressure test the pressure of 6.67MPa, is empty
Sub-atmospheric pressure distillation column under the test pressure (0.85MPa) of 8 times. To
Pressure test to ensure safety, Hangzhou oxygen on the original air compressor, air
Drying devices and pressure piping systems, carried out technological transformation, to ensure that
Nitrogen wash tower air pressure test carried out smoothly.
2 washing liquid nitrogen cold box assembly
Liquid nitrogen wash cold inside the nitrogen wash tower, plate-fin heat exchanger, vapor-liquid
Separators, gas mixers, valves, connecting piping and instrument power control
Lines are assembled in the factory in order to form the container, the entire
Body transported to the user site, the vertical lifting installation, complete turnkey work
Cheng. In order to avoid the cold inside the containers shipped to the user on-site dispersion, transport,
Lost due to injury resulting bump installation due to factory installed units and
Interface between users is wrong with the emergence of new quality problems.
Cold box assembly, the main control of the following three assembly quality.
(1) to strictly control the shape of the shell outside the cold box size, only to make
Rectangular and at the end of the cold box perpendicular to the plane after the cold box in order to ensure the overall effect
The installation of hanging vertical degree. So Hang oxygen on the cold box, under the shell of the profiles
Materials, welding assembly, when the size of ride control and composite welding welding deformation
Prevention, etc., are provided for internal control standards and rigorous processes Daodao
Checks to ensure that the overall size of precision cold box housing.
(2) nitrogen wash tower in the installation of cold-box positioning, using optical instrument
Control, to ensure that nitrogen wash tower and cold Xiangdi perpendicular to the plane in order to ensure
The use of washing liquid nitrogen cold box performance.
(3) strict control of the cold box of containers and pipelines connecting weld
The welding quality, thick-walled double-sided welding seam as far as possible, some due to
Structural reasons for the double-sided welding can not be achieved, then the use of the public from the Linde
Secretary for the introduction of the embedded stainless steel single-plate welding, butt weld all the
The x-ray inspection. Weld assembly is completed, the cold box
Channel air pressure, air tightness pressure test, each connecting welds were examined by the leakage
Leak checks to ensure that equipment is safe, reliable operation.
2004, l0 months, liquid nitrogen wash cold box in the user-site installation,
After commissioning, a driving success, the use of performance to meet user requirements.
3 Conclusion
Washing liquid nitrogen cold box of the successful development of the end of our liquid nitrogen wash cold
Case a long-term dependence on imported history. Aluminum in the chemical field sieve column was
To the application, and the design of pressure under the first time by air separation distillation tower
0.7MPa nitrogen wash tower up to 5.8MPa. Aluminum nitrogen wash tower is located
Meter, manufacturing also contributed to supporting the standard of China JB / T 4734-2002
"Welded aluminum container" formulation.
As international oil prices soaring, many domestic enterprises ammonia
Industry, in order to reduce production costs, there is the "oil and gas" to "water
Coal slurry gasification "to get the intention of hydrogen, especially in the 20th century, 70
To 80 years of imports of synthetic ammonia and equipment, are subject to alteration, extension,
Domestic washing liquid nitrogen cold box has a broad market prospect.