CN215855123U - Multifunctional marine nitrogen preparation device with safety redundancy - Google Patents
Multifunctional marine nitrogen preparation device with safety redundancy Download PDFInfo
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- CN215855123U CN215855123U CN202023305990.XU CN202023305990U CN215855123U CN 215855123 U CN215855123 U CN 215855123U CN 202023305990 U CN202023305990 U CN 202023305990U CN 215855123 U CN215855123 U CN 215855123U
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 310
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 150
- 238000002360 preparation method Methods 0.000 title claims abstract description 28
- 239000012528 membrane Substances 0.000 claims abstract description 139
- 238000000926 separation method Methods 0.000 claims abstract description 36
- 238000003860 storage Methods 0.000 claims abstract description 26
- 230000001105 regulatory effect Effects 0.000 claims abstract description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000001301 oxygen Substances 0.000 claims abstract description 11
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 11
- 239000007789 gas Substances 0.000 claims description 44
- 238000011084 recovery Methods 0.000 claims description 17
- 239000002912 waste gas Substances 0.000 claims description 11
- 238000012544 monitoring process Methods 0.000 claims description 9
- 238000009826 distribution Methods 0.000 claims description 6
- 230000003993 interaction Effects 0.000 claims description 4
- 238000012806 monitoring device Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 31
- 238000004519 manufacturing process Methods 0.000 abstract description 27
- 230000008569 process Effects 0.000 abstract description 21
- 229910001873 dinitrogen Inorganic materials 0.000 description 11
- 238000010586 diagram Methods 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- 238000009835 boiling Methods 0.000 description 4
- 239000002808 molecular sieve Substances 0.000 description 4
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 238000004422 calculation algorithm Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000005429 filling process Methods 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000007726 management method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
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- 238000004092 self-diagnosis Methods 0.000 description 2
- 238000007792 addition Methods 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
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- 230000009286 beneficial effect Effects 0.000 description 1
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- 230000005494 condensation Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000013524 data verification Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
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- 238000003745 diagnosis Methods 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen(.) Chemical compound [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
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Abstract
The utility model discloses a multifunctional marine nitrogen preparation device with safety redundancy, which comprises an air compressor (A1), a compressed air storage tank (A2), a freeze dryer (A3), a filter (A4), a membrane inlet flow transmitter (C1), a membrane inlet pressure transmitter (C2), a membrane inlet temperature transmitter (C3), a membrane inlet electromagnetic valve (B1), a membrane air separation device (A5), an oxygen analyzer (C4), a dew point temperature meter (C5), a membrane outlet pressure transmitter (C6), a membrane outlet flow transmitter (C7), a regulating valve (B3), a membrane outlet three-way valve (B2) and a nitrogen storage tank (A6) which are connected in sequence; the utility model detects parameters such as O2 content, dew point temperature, membrane inlet and outlet pressure and the like in real time, detects the nitrogen quality in real time at each stage of equipment operation, realizes the optimized matching of process variables and membrane performance, and determines whether to vent or not in real time according to the detected conditions, thereby not only ensuring the nitrogen purity, but also improving the nitrogen production rate.
Description
Technical Field
The utility model relates to a multifunctional marine nitrogen preparation device with safety redundancy.
Background
Nitrogen is used as the gas with the most abundant content in air (the content in air is 78.084 percent, the boiling point is-195.8 ℃, the condensation point is-210 ℃) and is inexhaustible, and is a sub-inert gas due to the characteristic, and is often used as a protective gas. The nitrogen-making device can be used in the fields of LNG storage tank inerting, pipeline purging, atmosphere replacement and the like, and along with the development and application of the existing LNG technology, the nitrogen-making device also gradually becomes a key component of an explosion-proof system of an LNG liquid cargo ship and a chemical ship.
Current several conventional nitrogen gas production systems state of the art, drawbacks and deficiencies
There are three methods commonly used in industry today for nitrogen production- -cryogenic air separation, molecular sieve air separation (PSA), and membrane air separation.
(1) The cryogenic air separation nitrogen production principle comprises the following steps: the nitrogen is obtained by compressing and purifying air as a raw material, liquefying the air into liquid air (mainly a mixture of liquid oxygen and liquid nitrogen) by heat exchange, and rectifying the liquid air by utilizing the difference of the boiling points of the liquid oxygen and the liquid nitrogen (the former boiling point is-183 ℃ and the latter boiling point is-196 ℃ under the standard atmospheric pressure) to separate the liquid oxygen and the liquid nitrogen.
The method has the disadvantages of complex cryogenic air separation nitrogen production equipment, large floor area, higher capital construction cost, more equipment one-time investment, higher running cost, slow gas production (12-24 h) and unsuitability for ships.
(2) The principle of molecular sieve air separation nitrogen production: a method for separating nitrogen from oxygen by using air as a raw material and a carbon molecular sieve as an adsorbent and utilizing the selective adsorption of the carbon molecular sieve on the oxygen and the nitrogen by applying a pressure swing adsorption principle is generally called PSA (pressure swing adsorption) nitrogen preparation. Compared with the traditional nitrogen preparation method, the method has the advantages of high automation degree, fast gas production (15-30 minutes), low energy consumption and capability of adjusting the product purity in a larger range according to the needs of users.
The defects that pressure swing adsorption requires frequent switching of devices such as valves and the like, the loss of equipment components is large, the failure rate is high, and the pressure swing adsorption is not suitable for ships.
(3) The principle of membrane air separation nitrogen production: air is used as a raw material, and under a certain pressure condition, gases with different properties, such as oxygen, nitrogen and the like, have different permeation rates in a membrane to separate the oxygen and the nitrogen. The equipment has the advantages of quick start, simple structure, less switching valves, small volume, quicker gas production (less than or equal to 3 minutes) and the like, and is particularly suitable for medium and small-sized nitrogen users with the nitrogen purity of less than or equal to 98 percent.
The device of the type is characterized in that the membrane component for producing nitrogen belongs to a consumable product and needs to be replaced regularly. The nitrogen quality (O2 content) and nitrogen productivity are influenced by a plurality of parameters such as membrane module performance, membrane inlet temperature, membrane inlet/outlet pressure, membrane inlet/outlet flow and the like, and if stable nitrogen quality and nitrogen productivity are obtained, the parameters have large mutual influence, a plurality of coupling factors and more complex control.
SUMMERY OF THE UTILITY MODEL
The technical problem to be solved by the utility model is as follows: provides a device and a method for preparing marine nitrogen with safety redundancy, which integrate multiple functions. Mainly solves the following problems:
in general, for a conventional membrane air separation nitrogen production device, the production flow rate of nitrogen is related to the membrane inlet temperature, the membrane inlet pressure, the membrane back pressure and the like at a certain nitrogen purity. Within the allowable range, the higher the membrane inlet temperature, the higher the membrane inlet pressure, and the higher the nitrogen production flow; likewise, at a given nitrogen production flow rate, the higher the membrane inlet temperature, the higher the membrane inlet pressure, and the higher the nitrogen production purity. The pressure (commonly called as 'back pressure') of a nitrogen storage device (generally a nitrogen buffer tank) of the membrane air separation nitrogen production device also has a certain influence on the nitrogen production efficiency, and when the back pressure is increased, the nitrogen production purity is increased, but the nitrogen production flow is reduced, so that the nitrogen production capacity is influenced. The pressure, flow, temperature, etc. parameters collectively determine the efficiency and stability of the nitrogen generation system.
The device adopts an optimization control method according to the membrane inlet temperature, the membrane inlet pressure, the membrane outlet pressure and the membrane outlet flow rate, and is matched with the membrane rear flow rate adjusting device, so that the nitrogen making process is stable, the stability of the nitrogen purity and the stability of the nitrogen pipe network pressure are ensured, and the nitrogen production capacity is improved.
B safety is very important for LNG cargo ships and chemical ships. The traditional nitrogen making device has potential safety hazard and is difficult to meet the requirements. The device adopts various safety measures to realize the safety redundancy of the nitrogen making device.
And C, the traditional membrane air separation nitrogen making device is not high in informatization degree and difficult to integrate with a master control system. The device adopts HMI and SQL databases, combines with a mainstream communication protocol, and solves the informatization problem of the nitrogen making device.
In order to solve the technical problems, the utility model adopts the technical scheme that:
the multifunctional marine nitrogen preparation device with safety redundancy is characterized by comprising an air compressor (A1), a compressed air storage tank (A2), a freeze dryer (A3), a filter (A4), a membrane inlet flow transmitter (C1), a membrane inlet pressure transmitter (C2), a membrane inlet temperature transmitter (C3), a membrane inlet electromagnetic valve (B1), a membrane air separation device (A5), an oxygen analyzer (C4), a dew point temperature meter (C5), a membrane outlet pressure transmitter (C6), a membrane outlet flow transmitter (C7), a regulating valve (B3), a membrane outlet three-way valve (B2) and a nitrogen storage tank (A6) which are connected in sequence;
a nitrogen storage tank pressure transmitter (C8) and a nitrogen storage tank pressure switch (D3) are arranged on the nitrogen storage tank (A6);
an air compressor state switch (D1) is arranged on the air compressor (A1), and a cold dryer state switch (D2) is arranged on the cold dryer (A3);
a gas emptying pipeline (E2) is arranged on the membrane air separation device (A5); an exhaust gas discharge pipeline (E1) is also arranged on the membrane outlet three-way valve (B2);
the waste gas discharge pipeline (E1) and the gas emptying pipeline (E2) are respectively provided with a waste gas recovery pipeline (F1) and a gas recovery pipeline (F2), and the waste gas recovery pipeline (F1) and the gas recovery pipeline (F2) are respectively connected with a gas inlet of the air compressor (A1).
The gas in the waste gas discharge pipeline (E1) and the gas emptying pipeline (E2) is purified by a filter and is relatively wasted if directly discharged into the atmosphere, and the utility model designs a recovery pipeline: the waste gas recovery line (F1) and the gas recovery line (F2) may be re-introduced into the air compressor (a 1) for the preparation of nitrogen.
The electrical control system consists of a power distribution unit and a control unit PLC;
the power distribution unit in the electrical control system receives 440V power feed, and provides 440V power supply for the air compressor (A1) and the cold dryer (A3), and also provides 220V power supply for the control unit PLC.
The control unit PLC comprises HMI man-machine interaction, a man-machine interface dynamically displays the nitrogen preparation process flow, and the membrane inlet temperature, the membrane inlet pressure, the membrane inlet flow, the membrane outlet pressure, the membrane outlet flow, the dew point temperature, the nitrogen storage tank pressure and the O2 content in the preparation process are connected with the control unit and displayed in real time on the main interface.
The air compressor (A1), the freeze dryer (A3), the membrane inlet solenoid valve (B1), the membrane outlet three-way valve (B2) and the regulating valve (B3) are also connected with the control unit PLC.
The control unit PLC also comprises a remote monitoring interface and a nitrogen tank overpressure monitoring device.
The basic principle of the utility model is as follows:
the function of the device is to produce nitrogen, the quality of the nitrogen is the core control target of the device, and the quality of the nitrogen is determined by several parameters such as nitrogen purity, dew point temperature and the like, wherein the nitrogen purity is the most important technical parameter of the nitrogen quality, and the nitrogen purity is related to the oxygen content in the nitrogen, so the index for measuring the nitrogen purity can be represented by the O2 content. In the actual nitrogen preparation process, the phenomenon that the nitrogen quality does not reach the standard can occur due to the membrane self-efficiency and the existence of various external objective factors.
In the dangerous chemical field such as LNG, use not up to standard nitrogen gas can have serious potential safety hazard.
It is known from process practice that the O2 content is mainly influenced by the following external factors, in addition to the membrane itself:
temperature factor A
The higher the membrane inlet temperature, the higher the efficiency of the membrane air separation plant, and the lower the membrane outlet O2 content. Changes in membrane inlet temperature, which can affect the O2 content;
factor of B pressure
The higher the membrane inlet pressure, the higher the efficiency of the membrane air separation unit. Changes in membrane inlet pressure, which can affect the O2 content;
factor of C flow
The greater the gas flow through the membrane air separation unit, the less O2 in the gas will be separated and the higher the content of membrane outlet O2. Changes in membrane inlet and outlet flow rates can affect the O2 content. In the nitrogen filling process, along with the pressure rise in the nitrogen buffer tank, the pressure difference (PT 1-PT 2) between the inlet and the outlet of the membrane air separation device is reduced, the air flow passing through the membrane air separation device is reduced, and the O2 content at the membrane outlet is also reduced (the nitrogen quality is improved).
From the above analysis, to adjust the O2 content, parameters such as temperature, pressure, flow rate, etc. are variables that can be used for adjustment. Considering the characteristic that the marine equipment is not too complex, the device selects the flow regulation mode with the most cost performance through the balance of cost and income.
Compared with the conventional nitrogen preparation system, the nitrogen preparation system has the following beneficial effects:
the device has the advantages of excellent performance, rich functions, simple operation, convenient maintenance and strong maneuverability, and completely accords with the national standard of the marine inert gas system. The use, operation and maintenance of the nitrogen making device accord with the principle of ergonomics, the nitrogen making process is stable, the pressure stability of a pipe network is ensured, the noise is low, and the nitrogen making device has the following characteristics:
1. basic Properties
| Parameter(s) | Unit of | Range |
| Purity of nitrogen gas | % | 95.0-99.9 (optional) |
| Oil content | PPM | <0.001 |
| Dust content | PPM | <0.01 |
| Pressure of nitrogen | Bar | 2-10 |
| Dew point temperature | ℃ | <-40 |
| Pressure of compressed air | Bar | 10-12 |
2. Based on O2Nitrogen quality self-adaptive control for real-time content detection (automatic emptying of unqualified nitrogen)
The system finds a set of unique self-adaptive control algorithm according to process practice and deep understanding of a control algorithm of a gas preparation device, and the basic principle is that the nitrogen quality is detected in real time at each stage of equipment operation by detecting parameters such as O2 content, dew point temperature, membrane inlet and outlet pressure and the like in real time, so that the optimization matching of process variables and membrane performance is realized, whether the air is emptied is determined in real time according to the detected condition, the nitrogen purity is ensured, the nitrogen production rate is improved, the membrane loss is reduced, and the service life of the whole machine is prolonged.
The quality of the nitrogen is ensured to meet the requirements, and the use safety of the nitrogen is ensured.
3. Safety redundancy
Aiming at the high-level requirements of the marine equipment on reliability and safety, the system adopts a unique safety redundancy design.
Is mainly embodied in
In the nitrogen preparation process, each process loop adopts a safety valve, a check valve and other components which are obtained by precise calculation according to process requirements, and is matched with a flow sensor, a temperature sensor, a pressure sensor and other components. The sampling position/static and dynamic characteristics of the sensing instruments of parameters such as flow, temperature, pressure and the like are subjected to precise calculation and long-term process practice.
The nitrogen buffer tank B is used as a pressure container, the selection of the nitrogen buffer tank meets the relevant national specifications, and the system adopts a unique overpressure monitoring and turn-off loop, so that the nitrogen buffer tank can also be quickly cut off the relevant loop after overpressure even if the master control PLC fails.
4. Fault self-diagnosis
The device has abundant fault self-diagnosis functions.
And A, aiming at conventional components (such as valves, air compressors and cold dryers) and the like, adopting logic analysis to prejudge faults.
And B, performing fault diagnosis on the operation condition of the membrane module by adopting a brand new method.
And C, monitoring faults between the CPU and the I/O module by the PLC, monitoring abnormal events such as disconnection, short circuit, power loss and the like between each module and a sensor of each station of the equipment, and monitoring the faults by the PLC and the HMI by adopting a heartbeat program.
And D, when a fault occurs, the system automatically outputs alarm information through the HMI, the acousto-optic device and other equipment, and the fault can be quickly positioned and eliminated through the alarm information.
5. Production process data recording (process value filing) and report output function
The production process data record has very important function on the control and retrospective analysis of the nitrogen quality. The device realizes accurate record of production process data by using the SQL database. The recording system has stable operation, no data loss, no data disorder and other conditions, and has the following specific functions,
(1) data recording the data recording of the present apparatus comprises three parts,
recording the A process: recording process data (membrane inlet temperature, membrane inlet pressure, membrane inlet flow, membrane outlet pressure, membrane outlet flow, nitrogen purity, dew point temperature, buffer tank pressure) of the process flow
B, alarm recording: alarm logging for abnormal events (such as valve failure, etc.).
C, recording operation: recording of operations on equipment and its components (e.g. equipment on/off, air compressor on/off, valve on/off), modification of key parameters, etc
(2) Data query and display browsing
By time, paging inquiry is carried out according to various retrieval modes such as ID numbers and the like, Trend browsing display is carried out according to time periods, and operations such as left shift, right shift, zooming, panoramic view and the like of data curves can be carried out.
(3) Data export
The device can output reports in different modes such as XML, PDF, CSV and the like according to the selected time range.
(4) Data verification
And according to the preset values of the process parameters, the data are checked for validity through a statistical method, and according to the development trend of the data, the situation that the data are found to be unqualified is early warned.
The historical data can be stored for up to 36 months
The production data recording function of the device thoroughly overcomes the defect of low informatization degree of the traditional nitrogen preparation system, and the nitrogen preparation system is incorporated into the automatic ship monitoring system.
6. Remote data interaction
The data related to the preparation system can be provided to a third party (such as a main control room) through a mainstream communication mode such as Prifinet, ModbusTCP, OPC UA and the like, and the control output of the third party is received.
7. Authority management
The management of rights is a very important content in information systems, and particularly in the field of LNG application, any operation should be performed by a right. The device groups the user authority, different groups have different operation authorities, and completely eradicates unauthorized behaviors of key process parameters and equipment operation from the use level of the equipment.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
FIG. 1 is a specific structure of a mechanical system of a nitrogen informatization preparation device for a ship.
Fig. 2 is a specific structure diagram of an electrical control system of the nitrogen informatization preparation device for the ship.
Fig. 3 is a flow chart of the operation of the apparatus.
Fig. 4 is a gas flow diagram of the present apparatus in operation.
FIG. 5 is a diagram of the gas flow apparatus when nitrogen quality is not acceptable.
FIG. 6 is a block diagram of gas flow for a nitrogen gas of unacceptable quality.
FIG. 7 is a diagram of the apparatus for gas flow when nitrogen gas is of acceptable quality.
FIG. 8 is a block diagram of gas flow for nitrogen quality.
In the drawings:
a1 air compressor, A2 compressed air storage tank, A3 refrigeration dryer, A4 filter, A5 membrane air separation plant, A6 nitrogen storage tank,
B1 membrane inlet electromagnetic valve, B2 membrane outlet three-way valve, B3 regulating valve
C1 membrane inlet flow transmitter, C2 membrane inlet pressure transmitter, C3 membrane inlet temperature transmitter, C4 oxygen analyzer, C5 dew point temperature meter, C6 membrane outlet pressure transmitter, C7 membrane outlet flow transmitter, C8 nitrogen storage tank pressure transmitter
D1 air compressor state switch, D2 cold dryer state switch, D3 nitrogen storage tank pressure switch.
E1: exhaust gas discharge pipe, E2: and (5) exhausting the pipeline by using gas.
F1: an exhaust gas recovery pipeline; f2: a gas recovery pipeline.
Detailed Description
Example 1
The embodiment provides a multifunctional marine nitrogen preparation device with safety redundancy, which comprises an air compressor (A1), a compressed air storage tank (A2), a freeze dryer (A3), a filter (A4), a membrane inlet flow transmitter (C1), a membrane inlet pressure transmitter (C2), a membrane inlet temperature transmitter (C3), a membrane inlet electromagnetic valve (B1), a membrane air separation device (A5), an oxygen analyzer (C4), a dew point temperature meter (C5), a membrane outlet pressure transmitter (C6), a membrane outlet flow transmitter (C7), a regulating valve (B3), a membrane outlet three-way valve (B2) and a nitrogen storage tank (A6) which are connected in sequence;
a nitrogen storage tank pressure transmitter (C8) and a nitrogen storage tank pressure switch (D3) are arranged on the nitrogen storage tank (A6);
an air compressor state switch (D1) is arranged on the air compressor (A1), and a cold dryer state switch (D2) is arranged on the cold dryer (A3);
a gas emptying pipeline (E2) is arranged on the membrane air separation device (A5); an exhaust gas discharge pipeline (E1) is also arranged on the membrane outlet three-way valve (B2);
the waste gas discharge pipeline (E1) and the gas emptying pipeline (E2) are respectively provided with a waste gas recovery pipeline (F1) and a gas recovery pipeline (F2), and the waste gas recovery pipeline (F1) and the gas recovery pipeline (F2) are respectively connected with a gas inlet of the air compressor (A1).
Wherein the regulating valve (B3) is an electric regulating valve.
The electrical control system consists of a power distribution unit and a control unit PLC;
the power distribution unit in the electrical control system receives 440V power feed, and provides 440V power supply for the air compressor (A1) and the cold dryer (A3), and also provides 220V power supply for the control unit PLC.
The control unit PLC comprises HMI man-machine interaction, a man-machine interface dynamically displays the nitrogen preparation process flow, and the membrane inlet temperature, the membrane inlet pressure, the membrane inlet flow, the membrane outlet pressure, the membrane outlet flow, the dew point temperature, the nitrogen storage tank pressure and the O2 content in the preparation process are connected with the control unit and displayed in real time on the main interface.
The air compressor (A1), the freeze dryer (A3), the membrane inlet solenoid valve (B1), the membrane outlet three-way valve (B2) and the regulating valve (B3) are also connected with the control unit PLC.
The control unit PLC also comprises a remote monitoring interface and a nitrogen tank overpressure monitoring device.
The basic principle of the embodiment is as follows:
the function of the device is to produce nitrogen, the quality of the nitrogen is the core control target of the device, and the quality of the nitrogen is determined by several parameters such as nitrogen purity, dew point temperature and the like, wherein the nitrogen purity is the most important technical parameter of the nitrogen quality, and the nitrogen purity is related to the oxygen content in the nitrogen, so the index for measuring the nitrogen purity can be represented by the O2 content. In the actual nitrogen preparation process, the phenomenon that the nitrogen quality does not reach the standard can occur due to the membrane self-efficiency and the existence of various external objective factors.
In the dangerous chemical field such as LNG, use not up to standard nitrogen gas can have serious potential safety hazard.
It is known from process practice that the O2 content is mainly influenced by the following external factors, in addition to the membrane itself:
temperature factor A
The higher the membrane inlet temperature, the higher the efficiency of the membrane air separation plant, and the lower the membrane outlet O2 content. Changes in membrane inlet temperature, which can affect the O2 content;
factor of B pressure
The higher the membrane inlet pressure, the higher the efficiency of the membrane air separation unit. Changes in membrane inlet pressure, which can affect the O2 content;
factor of C flow
The greater the gas flow through the membrane air separation unit, the less O2 in the gas will be separated and the higher the content of membrane outlet O2. Changes in membrane inlet and outlet flow rates can affect the O2 content. In the nitrogen filling process, along with the pressure rise in the nitrogen buffer tank, the pressure difference (PT 1-PT 2) between the inlet and the outlet of the membrane air separation device is reduced, the air flow passing through the membrane air separation device is reduced, and the O2 content at the membrane outlet is also reduced (the nitrogen quality is improved).
From the above analysis, to adjust the O2 content, parameters such as temperature, pressure, flow rate, etc. are variables that can be used for adjustment. Considering the characteristic that the marine equipment is not too complex, the device selects the flow regulation mode with the most cost performance through the balance of cost and income.
The utility model realizes the basic principle of automatic adjustment of O2 content
The PLC system monitors the content of O2 after the membrane air separation device in real time, and the opening of the electric regulating valve is changed according to the content of O2, so that the gas flow passing through the membrane air separation is changed, and the purpose of regulating the content of O2 is achieved.
When the content of O2 increases (the quality of nitrogen decreases), the opening of the electric control valve is decreased to decrease the flow rate, so that the efficiency of the membrane air separation plant increases and the content of O2 decreases accordingly.
When the content of O2 decreases (the quality of nitrogen gas increases), the opening degree of the electric control valve increases to increase the flow rate, the efficiency of the membrane air separation plant decreases, and the content of O2 increases accordingly.
By the adjusting method, the content of O2 in the prepared nitrogen is stabilized at a set level, and the quality of the nitrogen entering the N2 buffer tank is ensured to be stable and reliable.
In addition, if the O2 content requirement cannot be met by means of adjusting an electric control valve and the like, the relevant electromagnetic valve is immediately closed, and nitrogen is exhausted.
In the specific adjusting process, in order to meet the practical requirement, the system adjusts the content of O2 and also considers the yield.
This example is illustrated in FIGS. 3-4, which are a flow chart and a gas flow chart during operation. After the system is powered on, the electrically operated valves B1 and B2 are both in a closed state, and the membrane air separation unit does not work.
After the system is started, the control method is as follows
(1) The method comprises the steps of preparing compressed air, enabling the compressed air generated by an air compressor to enter and be stored in an air buffer tank (the set pressure is 10-12 Bar), and judging whether the pressure of the air buffer tank meets the production requirements or not by a system according to the state of the air compressor.
(2) The system automatically opens the B1 solenoid valve after the pressure in the nitrogen buffer tank is less than the preset value and the pressure in the air buffer tank reaches the design requirement, the B2 solenoid valve is closed, the B3 electric control valve has 50% opening, and the membrane air separation device enters a working state to start the nitrogen making process. Upon entering the operating state, the nitrogen gas separated from the membrane air separation unit is in a non-qualified state and is evacuated through a B2 solenoid valve (see FIGS. 5-6).
(3) After 1-2 minutes, the quality of the nitrogen monitored by each detection instrument reaches a stable state, the B2 electromagnetic valve is opened, and the qualified nitrogen is not exhausted any more but enters a nitrogen buffer tank (see figures 7-8).
In the process of filling nitrogen gas into the nitrogen gas buffer tank, the system detects the quality of the nitrogen gas in real time, and automatically adjusts the opening of the electric regulating valve according to the regulating principle inside the system to ensure that the O is in contact with the nitrogen gas2The content is maintained at a certain level.
(4) If the pressure in the nitrogen buffer tank is greater than the preset value, the system closes the B1 electromagnetic valve and the B2 electromagnetic valve in sequence, and the membrane air separation device stops working.
And (5) if the pressure in the nitrogen buffer tank is smaller than the preset value, re-executing the step (2) and entering another filling cycle.
(5) During the nitrogen production process, the system monitors the process parameters and equipment assembly units in real time and gives a response.
Aiming at the demand characteristics of marine equipment, the device of the embodiment provides a perfect monitoring function by combining a nitrogen making process.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art should understand that they can make various changes, modifications, additions and substitutions within the spirit and scope of the present invention.
Claims (2)
1. The multifunctional marine nitrogen preparation device with safety redundancy is characterized by comprising an air compressor (A1), a compressed air storage tank (A2), a freeze dryer (A3), a filter (A4), a membrane inlet flow transmitter (C1), a membrane inlet pressure transmitter (C2), a membrane inlet temperature transmitter (C3), a membrane inlet electromagnetic valve (B1), a membrane air separation device (A5), an oxygen analyzer (C4), a dew point temperature meter (C5), a membrane outlet pressure transmitter (C6), a membrane outlet flow transmitter (C7), a regulating valve (B3), a membrane outlet three-way valve (B2) and a nitrogen storage tank (A6) which are connected in sequence;
a nitrogen storage tank pressure transmitter (C8) and a nitrogen storage tank pressure switch (D3) are arranged on the nitrogen storage tank (A6);
an air compressor state switch (D1) is arranged on the air compressor (A1), and a cold dryer state switch (D2) is arranged on the cold dryer (A3);
a gas emptying pipeline (E2) is arranged on the membrane air separation device (A5); an exhaust gas discharge pipeline (E1) is also arranged on the membrane outlet three-way valve (B2);
the waste gas discharge pipeline (E1) and the gas emptying pipeline (E2) are respectively provided with a waste gas recovery pipeline (F1) and a gas recovery pipeline (F2), and the waste gas recovery pipeline (F1) and the gas recovery pipeline (F2) are respectively connected with a gas inlet of the air compressor (A1).
2. The multifunctional safety-redundant marine nitrogen preparation device according to claim 1, further comprising an electrical control system consisting of a power distribution unit and a control unit PLC;
a power distribution unit in the electrical control system receives 440V power feed, and provides 440V power supply for an air compressor (A1) and a cold dryer (A3) and 220V power supply for a control unit;
the control unit PLC comprises HMI human-computer interaction, a human-computer interface dynamically displays the nitrogen preparation process flow, and the membrane inlet temperature, the membrane inlet pressure, the membrane inlet flow, the membrane outlet pressure, the membrane outlet flow, the dew point temperature, the nitrogen storage tank pressure and the O2 content in the preparation process are connected with the control unit and displayed in real time on a main interface;
the air compressor (A1), the cold dryer (A3), the membrane inlet solenoid valve (B1), the membrane outlet three-way valve (B2) and the regulating valve (B3) are also connected with the control unit PLC,
the control unit PLC also comprises a remote monitoring interface and a nitrogen tank overpressure monitoring device.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023305990.XU CN215855123U (en) | 2020-12-30 | 2020-12-30 | Multifunctional marine nitrogen preparation device with safety redundancy |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023305990.XU CN215855123U (en) | 2020-12-30 | 2020-12-30 | Multifunctional marine nitrogen preparation device with safety redundancy |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112624065A (en) * | 2020-12-30 | 2021-04-09 | 海德威科技集团(青岛)有限公司 | Multifunctional marine nitrogen preparation device with safety redundancy and control method thereof |
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2020
- 2020-12-30 CN CN202023305990.XU patent/CN215855123U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112624065A (en) * | 2020-12-30 | 2021-04-09 | 海德威科技集团(青岛)有限公司 | Multifunctional marine nitrogen preparation device with safety redundancy and control method thereof |
| CN112624065B (en) * | 2020-12-30 | 2023-10-27 | 海德威科技集团(青岛)有限公司 | Multifunctional marine nitrogen preparation device with safety redundancy and control method thereof |
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