Home >> Industry Knowledge >> 20000m3 / h Nitrogen (Nitrogen equipment) features and commissioning Summary
Preface
Willow Steel 20000m3 / h air separation plant is Liu Gang, "Tenth Five-Year Plan"
The key technological transformation project is Liuzhou Iron and Steel to build an annual output of 4.5 million t steel heald
Combined production capacity of the main auxiliary projects. The sets of air separation plants using regular
Temperature molecular sieve adsorption, pressurized turbo-expander, structured packing tower and the whole
Distillation hydrogen-free argon technology, in June 2003 to begin preparations,
In April 2004 to start construction in December 2004 formally put into operation,
In May 2005 to undergo a performance assessment. Device indicators of good
Stable operation, unit design and equipment are to reach the domestic advanced level.
The project uses the imported equipment and domestic equipment combined square
Case, taking the strengths of Ge Jia. Germany's MAN-TURBO compressor selection
The company's RIK80 compressor, the models mature, reliable, its maximum
The advantage of the design with the scroll into one of the built-in the middle of the cooling
Devices, easy installation, saving area; oxygen compressor selection, Shenyang permeability
Ping Machinery Co., Ltd. of 2MCIA54 +3 MCL406 compressed
Machine, the model has a perfect safety protection system has been in the domestic multi -
Units to put into use, running in good condition; nitrogen compressor used by the U.S.
Ingersoll-Rand Company C450Mx5-type compressor; Automatic Control Department
HONEYWELL the company's integration with TPS systems; air separation of the main set
Preparation of oxygen from Hangzhou Hangzhou Co., Ltd. manufacture.
A process and device configuration features
Liuzhou Iron and Steel 20000m ~ / h air separation plant processes shown in Figure 1.
1.1 The design and manufacture their own box-type filters
Because this set of air separation equipment, geographic location close to the Liuzhou Iron and Steel Coal
Field, the atmosphere, soot and other impurities are more poor air quality. Because
This, there is no choice of a traditional self-cleaning air filter bag, but the election
Used by the Liuzhou Iron and Steel gas company's own design and manufacture of box-type filter (knot
Structure shown in Figure 2). The air filter from the frame of external access, via
Off the box on the filters after filtration into the filter interior, re-entry
Pass filter connected with the air compressor within the import pipeline. Filters
By two layers of cloth and two layers of stainless steel wire mesh frame composition. Inner layer of filter cloth is fixed
Set between two layers of stainless steel wire mesh frame, into the outer layer of cloth to rely on air compressor
Naturally attached to suction the mouth of the outer stainless steel wire mesh frame. Filter cloth from the wool
Felt and synthetic woven.
The filter advantages: simple structure, low manufacturing costs, and air
Gas flow through the resistance is small, easy maintenance; replacement of filter cloth can be only one person
Complete air compressor can be transported in the case of non-stop to replace filter cloth; cloth
Can be reused; weekly regular replacement of filter cloth in order to ensure efficiency
Rate, increasing the reliability of air compressor operation. Applicable to their environment space
Gas entrained dust more air separation unit. From the air compressor is running close to 9
Months of situation, the vibration value has been very stable, indicating the air over
To maintain a good filtration efficiency than filters.
Figure 2 Schematic diagram of frame-type filter
1.2 high-performance structured packing tower
In Liuzhou Iron and Steel 20000m ~ / h air separation plant, in addition to the next tower using sieve
Board tower, the last tower, the crude argon column and refined argon column are using new and efficient regulation
The entire packed tower. The actual operating situation from the device, its operating flexibility than the
Well, working load may be between 90% ~ 110% adjustable, restored condition
Complex rapidly, resistance, oxygen, argon extraction rate higher, respectively,
97% and 75% respectively. As a result of structured packing on the tower, reducing to
Consumption also play a significant role, as long as the compressor discharge pressure maintained at
0.48MPa would enable the normal production air separation plant, oxygen unit consumption of only
0.413kW · h/ln3.
1.3 All non-hydrogen-argon distillation technology
All-hydrogen-free argon distillation techniques, namely the use of structured packing fine
The advantages of distillation tower is entirely relying on distillation means to achieve the extraction of argon, take
Elimination of the hydrogen station and the crude argon purification systems. Not only air separation plant safety
Performance, while also saving equipment investment and daily operating costs.
1.4 New High Efficiency condensing evaporator
The main condenser evaporator pool bath with double-layer structure of liquid oxygen, which
Solve the large-scale air separation plant which produces the main cold too large Q
Question. As a result of a dual-pool structure of liquid oxygen, liquid oxygen level in the oxygen capacity
Volume and plate-fin heat exchanger to increase the case may remain unchanged, thus
Reach the goal of increasing heat transfer area while maintaining or even reducing the temperature difference between the main condenser head
The.
1.5 improve the emergency systems of liquid vaporization
Equipped with liquid oxygen, liquid nitrogen and liquid argon emergency vaporization system. Empty
When equipment breaks down and stopping points with emergency liquid pump liquid storage tank
Pressurized to 2.0MPa, and then through the heat recovery steam vaporizer temperature gas
After the send body can be restored to the pipeline network 10min aspirated and get gas
Achieve oxygen 20000m3 / h, nitrogen 20000m3 / h and argon
200m3 / h
Can ensure the normal supply 40h.
DCS control system for 1.6 sound
DCS control system set up three sets GUS, through its staff
Monitoring of air separation equipment, the operation of various systems and to carry out remote-controlled adjustment
Section. At the same time, through the Ethernet network directly connected with the factory management will be
Unit operation reached the management and production scheduling computer.
DCS system implementation level of air pre-cooling system, automatic adjustment,
Pump interlock stop and molecular sieve purification system, the order of control valve
System.
Air compressor, oxygen compressor site next to the dashboard with no machines, only with a
The necessary on-site instruments, probes and sensors, in DCS control room
Can be achieved on the system compressor start, automatic upload, automatic unloading
And parking and other operations, can be observed compressor important operating parameters.
DCS system is also responsible for the realization of the accident chain parking, anti-surge control
System, automatic pump start-up and the fuel tank heater temperature control.
2 Project construction experience
Liuzhou Iron and Steel 20000m3 / h air separation plant construction from the beginning to face a
A short duration, engineering and construction units of large multi-issues. However,
After Liuzhou Iron and Steel and the construction units to work together, concerted effort with
20000In3 / h air separation plant to start production from the construction in just out of oxygen
231d, including equipment installation, commissioning only the 119d. In such a
Within a short period of time successfully complete the project, mainly due to the following
Measures.
2.1 The construction headquarters was established to guide the coordination of work of various departments
Construction of an air separation plant is very specialized, strictly in accordance with the standard
Accurate, standardized construction. Meanwhile, the project involves multiple types of cross -
Operation. Therefore, the establishment of a strong coordinating body for the command is necessary
To. Liuzhou Iron and Steel plant to focus the professional engineering and technical personnel, managers
Members of the establishment of 20000m3 / h Air Separation Plant Project Construction Headquarters, from through the
Reasonable person in command, consists of technology, machinery, instruments, electrical and civil engineering
And other professional groups. Various professional groups in accordance with relevant guidance and supervision of professional division of labor
Unit construction and installation. Construction headquarters and led by a week
Project held two regular meetings on a regular basis. Command with the professional primarily responsible for
People, equipment manufacturers and the construction of the site on behalf of people responsible for a
Clear from the construction schedule, coordinate and solve problems in a timely manner to ensure that
Construction well under way.
2.2 The strict implementation of the scientific development of the construction schedule
Construction headquarters and well-developed work plan (Figure 3
Shown), to the cold box and the internal piping and the main air compressor installation and commissioning.
Lines, the preparation of a scientific and rational construction of network planning and coordinating the entire work
Process of construction, installation, the equipment installation, commissioning and construction work of Ling
Interludes to live an orderly manner to maximize savings in construction time, and let
Set of 13 assessment node (see Figure 3), and urge all relevant units Yan
Grid construction according to the progress of the organization.
2.3 The strict quality control, creating high-quality project
Installed before the start of Liuzhou Iron and Steel in collaboration with design unit, equipment manufacturing
Units of the plant process, machinery, apparatus, electronic control, as well as engineering design into the
Line a careful examination to detect and correct design errors, to avoid
Engineering quality problems and resulting incidents. During the construction process, work
Cheng construction headquarters with the design unit at the scene of constant repair
Change, improve the design and construction programs, the problems in the bud stage
Segment. For the installation of various systems, all equipment, installation, construction means
Hui Department has requested the various professional groups are assigned responsibility for the whole journey to follow the construction of
Personnel in equipment installation, carefully check the equipment, installation quality, timely
Elimination of equipment, pipeline installation defects, so that the quality of monitoring the implementation of the
Bit.
2.4 Human Resources to prepare well to achieve construction and production of a smooth transition
After the completion of the smooth production equipment, production operator skills
Operation quality and familiarity with the new equipment is a key factor. To
Here, the air separation plant operators to conduct targeted training for
The future, the normal operation of air separation equipment, ready to do a good job of human resources.
Organizations involved in the installation of the operator in advance to check process control
Road installation is correct, on cold box distillation system leak detection. Link
Off for each flange, each one carefully leak repeated weld to ensure that
The construction quality, but also to enable the operator to fully familiar with the process piping, in order to
Later skilled operation, to ensure a smooth transition to lay a firm foundation.
3 air separation plant operation experience and understanding
3.1 start the cooling phase of accelerated cooling the steam back to liquid nitrogen filling
December 2004 713 officially launched the first air separation plant, 23:
Start expander 30 into the cooling phase. But in the boot process
, 2 expander failure and forced to be revised. As the only open one
Taiwan expander, the cooling rate is slowing down, the temperature dropped slowly. To
As soon as possible to produce oxygen, reduce unnecessary power consumption, engineering command '
Department decided to take back to filling of liquid nitrogen vapor ways to accelerate the air separation unit cold
It. This is based on two considerations: ① charge of steam into the liquid nitrogen
Tower, part of the distillation system to add cooling capacity; ② charge into the liquid nitrogen vapor
Not directly filled into the liquid nitrogen, without causing too much temperature change due to pipeline
Large thermal stress caused by too large.
From 12 Yue 8 Et 17:30 onwards, within the low temperature of liquid nitrogen tank car
Evaporative gas filling return to the tower back to supplement the cooling capacity, cooling rate increases significantly
Fast, so 20000m3 / h air separation plant as scheduled in 12 out of 10 Et Yue
Oxygen.
3.2 Additional spare expander. Variable operating conditions
In order to avoid the existing air separation plant oxygen compressor caused Bump
Equipment with the existing low-pressure air separation plant oxygen connected valve. However, due to
20000m3 / h air separation plant oxygen compressor compressed capacity constraints,
20000m3 / h air separation plant oxygen around the product 1500m3 / h of I
The amount of shorting. In order to avoid oxygen shorting and to increase fluid production, raise
Additional one spare expander, an air separation plant to run variable condition of the square
Case. Because the domestic large-scale air separation plant in this area can learn the practice of
Have relatively less experience, therefore, in the implementation process, Liu Gang mainly rely on
Own experience, trial and error and adjusted gradually to achieve the conditions
20000m3 / h air separation plant oxygen compressor suction pressure fluctuations due to dancing with a more stable and satisfactory.

20000m3 / h air separation plant to operate
Cars, from June 2005 10 Et, the closure of 20000m3 / h Air Separation spare expander operating parameters before and after comparison

Table
Table 1 20000m3 / h air separation plant to operate stand-expander operating parameters before and after comparison
Additional project Expander to open before the post-expander
Oxygen production / (m3 / h) 21315 l9975
Liquid oxygen production / (m3 / h) 380 75O
Liquid nitrogen output / (m3 / h) 75 157.5
Technology Argon volume / (m3 / h) 765 735
Nitrogen throttle opening V3 /% 55.5 55
Expansion of the amount of air entering the tower / (ms / h) ll50o lO50o
Expander Speed / (r / rain) l970o l750o/l73o0
Note: The liquid product yield has been converted into a standard state of gas production, the same below.
3.3 improve the switching operation of the crude argon pump
Switch them to run the whole pump crude argon distillation process special hydrogen-free argon
Some one operation, but also require a higher skill level one pairs of the shooting
To make the slightest mistake, it will result in argon system conditions change, even
Affect the main tower working conditions. Through bold practice, some by the Liuzhou Iron and Steel Summary
Testing and experience.
(1) crude argon pump switching, the most likely problem is that the pump
Started, due to pump and pipe have not yet been completely cooled, the crude argon
Vaporization of the liquid pump imported pipe, causing steam blocking, so that two pumps at the same time crude argon
Pumping the liquid, pump back pressure gradually decreased, argon system, bad working conditions
Of. Therefore, the standby pump crude argon should be done before a thorough pre-cooling, while pre -
The cold side plate cars, and pipelines will pump a net evaporation gas emissions.
(2) before the start of imports of crude argon pump valve to open half of the outlet valve
Fully closed, slightly open pump valve of imports and exports, inter blowing blowing except valve. Started,
Inverter motor speed should be used to upgrade slowly to avoid the pump speed
Enhance the rapid generate cavitation.
(3) The crude argon pump inlet pressure fluctuations, indicating that import of pipeline pump hair
Health and steam blocking phenomenon, immediately before the wind In addition to opening its valve will pump gas emissions.
(4) When, after the crude argon pump pressure rise, pump operation currents to reach
Load current (about 22A), it can open the pump outlet valve, and gradually closed
In addition to the export blowing closing valves, pumps imported fully open valve; and then cut off another pump
The inlet and outlet valve. End switch.
3.4 adopt various means to shorten the time of transfer of argon
(1) out of oxygen before they can start the crude argon pump, the system put into operation as soon as possible
Argon system.
(2) or less can not be excluded as far as possible emission crude argon Ⅱ Tata kettle liquid, such as the tower
Reactor liquid surface is too high, only discharge part of the liquid, so that liquid level to maintain
In the crude argon column Ⅱ population of the following can be crude argon gas. Make full use of these rich
Liquid argon to accelerate the accumulation of argon.
(3) in maintaining the stability of the argon fraction as much as possible off unskilled laborer
Arts argon venting valve can also be put into operation as soon as possible refined argon column will be refined argon column of waste
Tata Liquid Ⅱ kettle back to the crude argon to avoid the straight row of argon to reduce the loss of argon
Loss.
By taking the above measures, transfer of argon reduced from 26h to
16h or so.
Four key performance indicators
In May 2005, 20000m ~ / h air separation plant to undergo a performance test
Nuclear, various performance indicators have reached or exceeded the design values shown in Table 2.
Table 2 Liuzhou Iron and Steel 20000m. / H air separation plant products are mainly performance indicators
Yield / (m3 / h) purity
Products
Assessing the value of the contract value is the value of assessing the value of the contract
Processing air volume l08O00 lO70o0
Oxygen 200o0 2l39O ≥ 99.6% 02 99.725% 02
LOX 50o 433 ≥ 99.6% 02 99.725% 02
Nitrogen 200o0 23550 ≤ 5 x 10 1 02 0.166 x 10 1 02
Pressure of nitrogen l0o0 l000 ≤ 5 x 10 1 02 0.166 x 10 1 02
Liquid Nitrogen 200 102 ≤ 5 x 10 1 02 0.166 x 10 1 02
≤ 2 x 10 02, 0.75 x 10 a 02.
Liquid Argon 740,755
≤ 3 x 10 1 N2 0.212 x 10 1 N2
Oxygen unit consumption /
0.42 0.3974
(kW · h / m)
Five areas for improvement
(1) oxygen compressor from the trial since nitrogen is found to have high-pressure cylinder vibration value
High, up to 46.7 m (50 / ~ m chain parking). Apart
Repeated high-pressure cylinder on the shaft after the pair has now dropped to 35.5btm,
But still high.
(2) 20000m ~ / h air separation plant instrumentation gas mains pipe diameter too small
(60mm), when the 15000m3 / h Air Separation Plant by parking
20000m3 / h air separation plant supplies two separate gas meter air separation plant
When the instrument air pressure to fall more, down to 0.42MPa.
(3) molecular sieve purification system manually pressurized pipe diameter too small
(60mm), caused by molecular sieve purification system startup time of filling pressure
Too long (40min), thus affecting the air separation plant start-up time of a
Important reasons.