Home >> Industry Knowledge >> Yanzhou Coal Mine Nitrogen Generator (Nitrogen Equipment) production summary

Cathay Yanzhou Mining Group in order to achieve an annual output of 230,000 t Chemical Co., Ltd.
Methanol, 210,000 t of acetic acid production scale, to provide for a new type gasifier
Plenty of high-pressure oxygen, the company in 2003 from French Air Liquide has introduced a
Set of 60000m3 / h Air Separation Plant. Begin by the end of 2003 construction work,
2005 October 14 sunrise 72h properties of oxygen through the examination, the former
After spending two years time. The air separation plant is currently the chemical industry
Has been running a set of the largest air separation unit, the following on the air separation plant
Processes, characteristics, and debugging of the relevant issues and improvement measures to do ordinary
Shao, for peer reference.
1 600003 / h air separation plant process
60000m3 / h flow shown in Figure 1.
Two main technical parameters and examination results
60000m3 / h Air Separation Equipment main technical parameters and examination results
Table 1. Air separation plant load adjustment range of 75% ~ 105%.
Table 1 Yankuang 60000m3 / h Air Separation Plant Main
Technical parameters and examination results
Assessing the value of the value of the project design
Oxygen
Yield / (m3 / h) 60000 60000
Purity ≥ 9916% ≥ 9917%
Nitrogen
Yield / (m3 / h) 53500 53500
Purity of ≤ 50 × 10 - 6O2 ≤ 10 × 10 - 6O2
LOX
Yield / (m3 / h) 4800 4800
Purity ≥ 9916% ≥ 9917%
Nitrogen
Yield / (m3 / h) 1500 1600
Purity of ≤ 50 × 10 - 6O2 ≤ 10 × 10 - 6O2
LAr
Yield / (m3 / h) 2300 2308
Grade ≤ 1 × 10 - 6O2 ≤ 011 × 10 - 6O2
3 Features
311 structural features
(1) cold box for all vessels, shell and pipe are used Ostwald
Body of stainless steel;
(2) advanced welded structure to reduce the number of cold box flange
Less;
(3) The aluminum heat exchanger and stainless steel connection head, using
A special bi-metal joints;
(4) All of the distillation column are packed tower.
312 Technical Characteristics
(1) pressurized turbo-expander inlet gas pressure increased, the unit system
Cold increases, expansion of machine efficiency.
(2) using a single pump compression process, through the high-pressure liquid oxygen pump
Pressure, heat exchanger, re-heat output of high-pressure oxygen, oxygen pressure is no longer used
Machine, not only saves space, while simplifying the operation, improve the transport
Line security.
(3) The system uses a full distillation argon argon technology, process liquid argon
Phase feed.
(4) The molecular sieve adsorber using vertical double bed radial flow statement
Structure, and adsorption performance is good, start simple, sequential control system is stable.
(5) set the nitrogen and water pre-cooling systems (air-cooling towers, water towers of nitrogen) on the
Air for cleaning cooling, and set the heat to the chilled water of ammonia down
Temperature. In addition, the chilled water system is closed circulatory system, not only to save
Of water resources, while reducing investment in equipment.
(6) liquid expander to replace high-pressure fluid throttle, its
Expansion of power through the generator to recover.
(7) The compressor system consists of a compressor station turbine drag 2
Group, speed control system uses MANTURBO the TURBOLOG system.
(8) expansion of air into the next tower, distillation stable condition.
4 debugging and improvement measures
411 appears in the pre-commissioning design and installation problems
The rationality of the design is to ensure that the prerequisite of a successful unit testing
Parts, the design of this unit Zengyin the conduct of the reasons for delay in commissioning.
(1) Steam Turbine into the pipeline design, as Design Institute
Not accurate enough, did not seek to conduct a detailed and reasonable calculations, making the country
Foreign experts believe can not meet the test conditions, delayed steam turbine
The red switch. Through the re-design and calculation to resolve this problem.
(2) air compressor venting pipeline design, the design negligence,
Did not consider air compressor anti-surge valves are unique, valves straight pipe before the former
Short, resulting in the compressor anti-surge tests carried out because of the impact of air
The instability of the universal joint fracture venting valve will delay the trial into the
Degrees. Pre-venting valve by extending the length of straight pipe, so that uniform flow
To the impact of butterfly valve plate, eliminating the phenomenon of turbulence, the problem is resolved.
(3) Booster test phase, was found in the right booster machine qi Guo
Process, the pressure rise slowly, analysts believe that a machine imported from the booster
Check valve is not installed correctly cause. Conducted a review of its demolition, as expected from the
Mistakes in the construction units should be a vertical valve spool
Central axis is installed into the horizontal direction. Their adjustment, qi speed
Normal.
412 transformation of the steam turbine seal pipeline
Steam Turbine Seal is used to seal the inlet side to prevent leakage of steam
Leak, outlet side of the atmosphere to ensure the vacuum seal. As the space dividing
113MPa pipe network at the end of the entire company, together with pipe insulation
Good, the quality of steam that is hot enough, leading to turbine seal
Steam temperature is lower than the value of the low chain 150 ℃, particularly in the molecular sieve
Heating period, the pressure on the pipe network has great influence not guarantee steamship
The stable operation of machines. Through the single test, the rectification and sealing steam pipe
Road, at 318MPa steam pipe network extraction Yi Gu, through the decompression diminished
Set the temperature control valve, and connected to the steam into the turbine seal
Tracheal line, steam heated to 113MPa. After transformation, effects
Obviously, during the normal operation of the temperature of steam turbine sealing can be achieved
270 ℃, and can meet the requirements of plant operation.
E08 regeneration heater 413 to improve the steam pipe inlet shut-off valve
Program
As 113MPa steam steam and E08 for the same pipeline,
Whenever the regeneration of molecular sieve into the heating stage, E08 heating steam pipe
Intake TV1288 program set up an automatic shut-off valve open 100%, E08
Larger than steam, so at this time of 113MPa steam pipe
Pressure a significant influence. Pressure dips, not only by the shadow of its vacuum
Ring, and because of 318MPa and 113MPa steam seal between the air
Valve response to slow, can not play the role of decompression, sealing steam
Sudden rise of local power, or even super-range, so that the steam pipe valve seal
PV7023 Auto-off small, sealed steam temperature dips. Reason
TV1288 valve procedure is set to automatically open 100%. Debugging
Staff modified the program, when the TV1288 valve automatically opens 90%
After the let off gradually to 50%, followed by further opening its 1% for every 1min,
Until the opening as large as 100%. After sealing steam pipe pressure stability,
Range of temperature fluctuations is extremely small, completely solved the 113MPa steam pipes
Net question.
414 transformation of pressurized heated gas outlet pipe turbo-expander
Air Liquide not designed as an expander heated gas export pipelines,
In the expander inlet pipe line is only a blind flange leads to cold box,
Therefore, when the expander heat required to remove blind flange. As the pipeline pressure
Strength in the 218MPa, the need for pressure relief after stopping only after heating. At
Single test found that the pressure relief poured through a small guide was very slow; and
And the blind flange demolition frequently, not only affects the speed heated expander
Degrees, but the pipeline itself hazardous. These show that this design
Extremely unreasonable, and even design errors. In this regard, the bit in the blind flange
Install the same set of stainless steel valves pressure rating to replace the blind flange,
Not only the speed with pressure relief, and simple operation, no need to dismantle
Unload blind flange.
415 transformation of Instrument Air Supply System
Instrument Air compressor station due to problems, gas oil content meter
Large to provide qualified gas meter. For security and does not affect the open
Cars, dividing the air meter air source has been transformed, in the 215MPa
Nitrogen gas mains terminal leads to a tube, the middle of a Self-less
Pressure vacuum valves connected to gas mains meter air demarcation zone valve
Later, as dividing the whole space instrument air source; in air separation plant to stop
Vehicles or emergency circumstances, as a backup instrument air source to ensure that the air
Sub-meter gas supply equipment. Prior to this, through the temporary control of the entire
Empty dividing instrument gas pipeline blowing steam addition, the pipeline
In addition to the oil blown clean and dry with nitrogen. The completion of the entire air separation
Border in the instrument tracheal network transformation and replacement.
416 transformation of ammonia ammonia pipe heat exchanger
Linkage test of air precooling system appears ammonia heat exchanger does not work
Phenomenon, because the amount of ammonia absorption refrigeration ammonia under construction section, the pressure does not
Enough, piping resistance, and will import valve LV1072 flow of liquid ammonia is not enough.
Pipeline ends after the addition of a bypass valve, the problem is resolved.
Currently ammonia heat exchanger temperature difference before and after the water temperature is about 5 ℃, the basic Man -
Foot requirement.
417 implementation of the Automatic Variable Load Control
When the air separation plant is running at 70% load or more, while all
The products have been sent, the purity requirements, you can start from the
Dynamic variable load program. An air separation plant oxygen production by the operator set
Fixed and can automatically adjust settings to allow gaseous oxygen range: 32000
~ 57800m3 / h. In the air separation plant to start smoothly, the various materials
Balance and the automatic state operating for some time, from the initial pressure of
Replaced by automatic flow control vane air compressor, set the high-pressure oxygen
Automatic Variable load calculation that require each product flow, start automatically
Variable load "LOAD CHANGE" program. After a few variable load
Operation of the control observation, after changing the high-pressure oxygen flow, the flow of
Control point can a smooth transition to the corresponding state requirement traffic, and
Maintain the purity and other parameters remain unchanged. In some important changes in traffic
On the specially designed "RAMP" Control of the slope control,
The purpose is to make installation a smooth transition to demand load and interference-free cutting
Change. Run from the current situation, the follow-up production system in the
Failure, variable load is particularly important. In the high-pressure oxygen demand is not high
, Through the automatic variable load to reduce energy consumption and productive as possible solution
Body products, reduce the amount of venting to achieve air separation equipment, highly efficient and stable
Run.
5 Debugging Experience
Shorten the start-up time is the operation of an air separation plant to run a head
Standard. According to different periods of the air separation equipment, the corresponding parameters
Adjustments, especially in the transfer of pure phase, must be based on reflux ratio, the material
Balance, cold-component balance can be balanced and comprehensive and integrated consideration.
(1) to the cold box aspirated, whether to start or in the hot state
Cold start cold box, open the cold box to send the speed of valve must be
Slow. When there is liquid in the cold box should pay particular attention, otherwise it will result in Air
Machine pressure fluctuations, flow phenomena such as rapid change, resulting in Air
Machine into the surge zone automatic unloading. Turned into the first tower of the valve with
A small bypass valve to the cold box step, the pressure to normal, slowly open the aspirated
Large valves and adjust the air compressor operating conditions in order to maintain pressure.
(2) gas to the cold box guide, due to the slow pace of air into the tower
Gas-less, in order to avoid the loss of cold and hot side temperature is too low and interlock
Cold box Bump arise, there may be a negative Heti first pressurized aircraft to positive
Chang, and outlet pressure regulator into automatic control, and then start the swelling
Inflation machine, so that more hot air into the heat exchanger to heat, avoid
The amount of the loss of cold and hot side temperature is too low and the chain jumping off the tram. This experience
In the testing phase of accumulation and summary. In the time you start the process,
As the operator of the errors lead to the tower gas is too slow, resulting in
Inadequate reheating, hot-side temperature of a sharp decline, not only the amount of damage caused by the cold
Loss, but also extended the drive time. Therefore, in subsequent operations, we must
Demand when the first cold start driving an expander to increase the access to heat exchanger
The air volume and air speed guide to speed up the product the amount of venting required
To minimize, so as to achieve stable operation and reasonable operating purposes.
(3) put into operation in the crude argon tower must have certain conditions. If thick
Argon pre-cooling tower is not good, the main tower of unstable or cold conditions is not sufficient
Cases, put into operation in the crude argon column, the result is a crude argon column is not resistance
Go, it will affect the main tower of working conditions. Crude argon column operating conditions to control the key
Is the main tower's stability, control distillate purity argon. In short, the main
Tower stability is the prerequisite condition. Another point to note is the open
Kai steam condenser Air Liquide go to the tower return valve FV1712 to be slow,
And to manually control the opening and avoid automatic control inputs. The initial stage of the
Valve should the pressure controller to control the opening, such as crude argon tower
Nitrogen content tended to be normal, the crude argon condenser after the establishment of a normal temperature, then
Air Liquide gradually opening its vapor return valve FV1712, so that flow of argon fraction
To normal. In the debugging system, Argon System will initially had been due to
FV1712 improper valve control lead to large fluctuations in liquid air evaporation,
Caused by the main tower of oxygen-rich liquid air can not enter the tower and the tower under the flooded tower operations
Failure.
(4) The high degree of automation, air separation plant, the correct use of
DCS system automatically load changing procedure, the open-loop cascade control that controls the
Working conditions conducive to stability. However, we must ensure that working conditions meet the conditions, and to
Seeking the adjustment valve must automatically be put into the state to run stable
Cascade control, or improper handling easily to fluctuations in operating conditions, resulting in an empty
Separation plant outages.