CN117722821A - Quick starting method of air separation device - Google Patents
Quick starting method of air separation device Download PDFInfo
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- CN117722821A CN117722821A CN202311655708.6A CN202311655708A CN117722821A CN 117722821 A CN117722821 A CN 117722821A CN 202311655708 A CN202311655708 A CN 202311655708A CN 117722821 A CN117722821 A CN 117722821A
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- Prior art keywords
- pressure
- nitrogen
- air
- tower
- liquid
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- 238000000926 separation method Methods 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 23
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 113
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 56
- 239000007788 liquid Substances 0.000 claims description 33
- 239000007789 gas Substances 0.000 claims description 19
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 6
- 238000004458 analytical method Methods 0.000 claims description 4
- 238000000746 purification Methods 0.000 claims description 4
- 230000001502 supplementing effect Effects 0.000 claims description 4
- 238000010992 reflux Methods 0.000 claims description 2
- 238000005057 refrigeration Methods 0.000 claims description 2
- 239000002699 waste material Substances 0.000 claims description 2
- 238000006073 displacement reaction Methods 0.000 claims 1
- DOTMOQHOJINYBL-UHFFFAOYSA-N molecular nitrogen;molecular oxygen Chemical compound N#N.O=O DOTMOQHOJINYBL-UHFFFAOYSA-N 0.000 claims 1
- 238000010408 sweeping Methods 0.000 claims 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 11
- 239000001301 oxygen Substances 0.000 abstract description 11
- 229910052760 oxygen Inorganic materials 0.000 abstract description 11
- 238000011010 flushing procedure Methods 0.000 abstract 1
- 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
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- OLBVUFHMDRJKTK-UHFFFAOYSA-N [N].[O] Chemical compound [N].[O] OLBVUFHMDRJKTK-UHFFFAOYSA-N 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000110 cooling liquid Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04763—Start-up or control of the process; Details of the apparatus used
- F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
- F25J3/04812—Different modes, i.e. "runs" of operation
- F25J3/04818—Start-up of the process
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
The invention provides a quick starting method of an air separation device, which adopts a more scientific and efficient quick starting scheme to reduce the time from about 6 hours to 3-4 hours from the time of flushing a steam turbine to the time of qualified oxygen and nitrogen in the cold starting process of the air separation device by controlling the moisture of compressed air entering an air separation system after stopping, thereby greatly reducing the starting time of the air separation device, ensuring the quick starting of a rear working section and having remarkable safety benefit and economic benefit.
Description
Technical Field
The invention relates to the technical field of air separation devices, in particular to a quick starting method of an air separation device.
Background
An air separation device (air separation for short) is an industrial device for producing gases such as oxygen, nitrogen and the like by separating component gases in air by utilizing different boiling points of the components in the air. Fig. 1 shows a typical air separation system structure, which basically operates as follows: raw air is filtered by a self-cleaning air filter to remove dust and mechanical impurities in the air, the air enters an air compressor through a pipeline to be compressed, the compressed air enters an air cooling tower to be washed and cooled, the cooled air enters a molecular sieve purification system (comprising a molecular sieve A, a molecular sieve B, a molecular sieve heater and the like) to be purified, water, carbon dioxide and most of hydrocarbon in the air are adsorbed, the air is divided into two parts, one part enters a lower tower of a rectifying tower after heat exchange by a low-pressure plate heat exchanger, the other part enters a booster to be pressurized, part of the air is sequentially pressurized and then is partially liquefied by cold energy generated by a turbine expansion unit, and then enters the rectifying tower to be rectified after being secondarily pressurized, the part of the air is throttled and enters the rectifying tower to be rectified after heat exchange with liquid nitrogen which is sent out of the high-pressure plate heat exchanger, and the oxygen and nitrogen which are reheated are sent to users, and the polluted nitrogen is used as reclaimed gas of the purification system and the water cooling tower is reduced.
After the air separation device is stopped by the device or caused by external reasons, the oxygen and nitrogen device for the rear working section needs to be reused in the shortest time, so that the loss caused by oxygen and nitrogen interruption is reduced. The air separation device needs to be started for 2 hours to carry out dew point replacement analysis on dry low-moisture air for a system, the dew point is less than or equal to minus 65 ℃, cold box air is led after the air separation device is qualified, the air is led in the order that the lead low-pressure air needs about 0.5 hour, then the medium-pressure air is led to start an expander for about 0.5 hour, after the main cold liquid level is qualified, a liquid oxygen pump is started to send oxygen, and meanwhile, high-pressure air is led in for about 2 hours, and the purity of the oxygen and the nitrogen is started to be adjusted until the air is qualified.
In order to overcome the defects of the existing space division starting driving technology, the invention aims to provide a method for quickly starting space division, which solves the problems of low cold driving speed and high consumption of a cryogenic air separation device, accelerates the starting speed and saves the cost and provides qualified oxygen and nitrogen for a rear working section.
Disclosure of Invention
The invention aims to solve the technical problem that the starting time of the air separation device after the shutdown is long, and the follow-up production is affected.
In order to solve the technical problems, the invention adopts the following technical scheme: a quick start method for air separation unit. In order to achieve the above purpose, the present invention is realized by the following technical scheme:
1. the air supplementing of the air inlet of the supercharger is changed from compressed air into pure nitrogen with low dew point during the stopping period of the air separation device.
2. The heating gas of the expander and the replacement gas source are pure nitrogen with low dew point, so that the water in the compressed air is reduced to enter the system, the system can be heated and replaced during the stopping period, and the time required for the system to replace the dew point is reduced.
3. The low-temperature liquid oxygen pump and the liquid nitrogen pump are heated by low-pressure normal-temperature nitrogen, and the liquid nitrogen is precooled to reach the starting condition before being led to the rectifying tower.
4. And after the air compressor is started, a precooling and purifying system is sequentially used for purging and replacing the supercharger, and the outlet dew point analysis of the supercharger is qualified for conducting air and pressurizing the lower tower of the rectifying tower.
5. The low-pressure air guide is carried out while the booster is loaded, the expander is started, the three-section outlet high-pressure air throttle valve is opened by 10%, and the low-pressure air guide, the medium-pressure air guide and the high-pressure air guide are carried out on the lower tower of the rectifying tower. The upper tower pressure and the lower tower pressure of the rectifying tower are controlled through a liquid air conditioner throttle valve, a dirty liquid nitrogen I throttle valve, a dirty liquid nitrogen II throttle valve, a low-plate dirty nitrogen delivery valve and a high-plate dirty nitrogen delivery valve. When the pressure of the upper tower rises, the high-plate sewage nitrogen flow control valve is preferentially opened, the high-plate temperature is reduced, the flow of the expander is increased, the high-pressure air throttle valve is opened, the refrigerating capacity is increased, the liquid accumulation of the cold tower of the rectifying tower is quickened, the plate temperature is prevented from being reduced to be negative, and the starting time is shortened.
7. And (3) the main cooling liquid level rises to 2/3, an oxygen-nitrogen pump is started, the load of the oxygen-nitrogen pump is increased until the oxygen-nitrogen emptying reaches 70% of rated load, and simultaneously, the expansion amount and the final-stage air amount of the supercharger are increased to perform effusion purification. .
The invention provides a quick starting method of an air separation device, wherein a low dew point pure nitrogen gas is used as a replacement gas source through gas supplementing of a parking unit and system heating. The operation mode of the starting process is changed, low-pressure, medium-pressure and high-pressure air guiding in the air guiding process is simultaneously combined, the load of the high-pressure plate type heat exchanger is improved as early as possible particularly in the starting process, the risk of over-pressure of the upper tower of the rectifying tower is reduced, the risk of pipeline damage caused by low temperature of a low-plate polluted nitrogen outlet is reduced, and the cold energy can be recovered as much as possible, so that a foundation is laid for pure adjustment.
The method changes the pure regulation mode from medium-low load regulation to medium-high load regulation, and the emptying amount of high-pressure oxygen and medium-pressure nitrogen is not less than 70% of rated load, which is beneficial to the formation of good rectification working condition of the rectifying tower.
The air separation device has shorter starting time, the original starting time is compressed to 3-4 hours after 6 hours, the starting time of the air separation device is greatly reduced, the quick starting of a rear working section is ensured, and the safety benefit and the economic benefit are greatly improved.
Drawings
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
fig. 1 is a schematic structural view of an air separation apparatus.
Detailed Description
As shown in fig. 1. The quick starting method of the air separation device specifically comprises the following implementation steps:
1. during the stop period, the air supplementing of the booster is changed from compressed air to low dew point pure nitrogen.
2. The heating gas of the expander and the replacement gas source are pure nitrogen during the stopping period, so that the water in the compressed air is reduced to enter the system, the system can be heated and replaced to be qualified during the stopping period, and the time required for the system to replace the dew point to be qualified is reduced.
3. The low-temperature liquid oxygen pump is used for heating a liquid nitrogen pump during stopping, low-pressure normal-temperature nitrogen is used for heating, and the liquid nitrogen pump is pre-cooled to be qualified before gas is led to the rectifying tower to reach a starting condition.
4. And after the air compressor is started, sequentially feeding a pre-cooling and purifying system, and carrying out air guide and pressurization on the lower tower after the middle pumping and final-stage outlet dew point analysis of the supercharger is qualified. And simultaneously loading the booster and starting the expander, and opening a final-stage high-pressure air throttle valve of the booster by 10 percent to charge the lower tower together.
5. Along with the gradual rise of the pressure of the lower tower of the rectifying tower, the pressure of the lower tower is maintained to be 0.4-0.43MPa; when the pressure of the lower tower is higher than 0.4 MPa; gradually opening the liquid-air throttle valve, the dirty liquid nitrogen I throttle valve and the dirty liquid nitrogen II throttle valve to 100% to guide air to the upper tower of the rectifying tower, wherein the pressure of the upper tower is controlled to be lower than 50KPa.
6. The pressure of the upper tower rises, a low-pressure plate type heat exchanger polluted nitrogen pressure control valve is gradually opened, the temperature of polluted nitrogen at the outlet of the low plate is controlled, and the temperature above 0 ℃ is maintained. The waste nitrogen flow control valve of the high-pressure plate type heat exchanger is gradually opened, the final-stage gas flows of the expander and the supercharger are increased, the flow of the expander is increased and the high-pressure air throttle valve is opened by the high-pressure plate type temperature reduction, the refrigeration of the positive-flow gas and the expander is increased, the liquid accumulation of the cold tower of the rectifying tower is accelerated, the low-pressure plate type temperature reduction is prevented from being negative, and the starting time is shortened.
7. When the pressure of the upper tower is increased, more dirty nitrogen exchanges heat through the high-pressure plate heat exchanger, the load of the high-pressure plate heat exchanger is increased, the pressure of the lower tower is controlled to be not more than 0.44MPa, and a large amount of low-pressure air entering amount is kept to enter the lower tower of the rectifying tower.
8. The pressure air flow is reduced to be normal under the temperature in the tower, the main cold liquid level rises to 2/3, a liquid oxygen pump and a liquid nitrogen pump are started, and the temperature difference of the hot end of the high-pressure plate type heat exchanger is increased by increasing the air quantity of the expander and the final air quantity of the supercharger to balance the temperature difference of high-pressure plate and low-pressure plate exchange.
9. After the liquid oxygen pump and the liquid nitrogen pump are started, the liquid oxygen and the liquid nitrogen are discharged through high-pressure heat exchange, the temperature of the cold end of the high-pressure heat exchanger is gradually reduced to below minus 170 ℃, the working condition is gradually stable, liquid accumulation begins in the rectifying tower, the main cold liquid level is in an ascending trend, a main cold liquid nitrogen reflux valve is opened, the pumping amount of the air compressor is increased, and the pressure of the lower tower is maintained to be 0.45MPa; the oxygen and nitrogen emptying amount reaches more than 70% of the rated flow, the dirty liquid nitrogen I throttle valve and the dirty liquid nitrogen II throttle valve are gradually closed, and the upper tower resistance and the lower tower resistance of the rectifying tower are regulated.
The invention has the following beneficial effects: after the method is implemented, the starting time of the air separation device is reduced, the production cost can be saved, and qualified oxygen and nitrogen can be provided for the later working section as soon as possible.
Claims (7)
1. The quick starting method of the air separation device is characterized by comprising the following steps of: s1, supplementing low-dew-point pure nitrogen by a booster before the air separation device is started, wherein the low-dew-point pure nitrogen is adopted as a heating gas source of an expander and a gas source of a displacement gas; s2, heating the low-temperature liquid oxygen pump and the liquid nitrogen pump by adopting low-pressure normal-temperature nitrogen during stopping, and pre-cooling the rectifying tower before introducing gas to the rectifying tower, wherein the start condition is reached; s3, after the air compressor is started, sequentially using a pre-cooling system and a purifying system, conducting air guide sweeping on the lower tower after the dew point analysis of the middle-stage outlet and the final-stage outlet of the supercharger is qualified, starting the supercharger and the expander, opening a final-stage high-pressure air throttle valve of the supercharger, and pressurizing the lower tower; s4, in the pressurizing process of the lower tower, a liquid air throttle valve and a dirty liquid nitrogen throttle valve in the lower tower are opened to pressurize the upper tower, and a low-plate dirty nitrogen delivery valve and a high-plate dirty nitrogen delivery valve are opened to control the pressure of the lower tower and the upper tower; s5, starting the liquid oxygen pump and the liquid nitrogen pump in advance, lifting the load, and improving the introduction quantity of medium-pressure and high-pressure air for purification.
2. A method of fast start-up of a space division apparatus as set forth in claim 1, wherein: in the step S3, the last-stage high-pressure air throttle valve opening of the supercharger is 10%.
3. A method of fast start-up of a space division apparatus as set forth in claim 1, wherein: in the step S4, the pressure of the lower tower is maintained at 0.4-0.43MPa in the process of increasing the pressure of the lower tower, and the air guide to the upper tower is started when the pressure of the lower tower is higher than 0.4 MPa.
4. A method of fast start-up of a space division apparatus according to claim 3, wherein: in the step S4, the liquid air throttle valve and the dirty liquid nitrogen throttle valve are gradually opened to 100%, and the pressure of the upper tower is controlled to be lower than 50KPa.
5. A method of fast start-up of a space division apparatus according to claim 4, wherein: in the step S4, when the pressure of the upper tower rises, the dirty nitrogen pressure control valve of the low-pressure plate heat exchanger is controlled to be gradually opened, and the temperature of the dirty nitrogen at the outlet of the low-pressure plate heat exchanger is controlled to be more than 0 ℃.
6. A method of rapid start-up of a space division apparatus as set forth in claim 5 wherein: in the step S4, the opening degree of the high-pressure plate type heat exchanger waste nitrogen flow control valve is gradually increased, and the final-stage gas amounts of the expander and the supercharger are increased, so that the temperature of the high-pressure plate type heat exchange gas is reduced, the flow rate of the expander is increased, the high-pressure air throttle valve is opened, the normal-flow gas and the expander are increased for refrigeration, and the cooling tower effusion of the rectifying tower is accelerated.
7. A method of fast start-up of a space division apparatus as set forth in claim 1, wherein: in the step S5, after a liquid oxygen pump and a liquid nitrogen pump are started, liquid oxygen and liquid nitrogen are discharged through high-pressure heat exchange, the temperature of the cold end of a high-pressure heat exchanger is gradually reduced to below-170 ℃, after the liquid level rises, a main cold liquid nitrogen reflux valve is opened, the air intake of an air compressor is increased, the pressure of a lower tower is maintained to be 0.45MPa, and after the nitrogen oxygen discharge reaches more than 70% of rated flow, a dirty liquid nitrogen throttle valve is gradually closed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311655708.6A CN117722821A (en) | 2023-12-05 | 2023-12-05 | Quick starting method of air separation device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311655708.6A CN117722821A (en) | 2023-12-05 | 2023-12-05 | Quick starting method of air separation device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117722821A true CN117722821A (en) | 2024-03-19 |
Family
ID=90206335
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311655708.6A Pending CN117722821A (en) | 2023-12-05 | 2023-12-05 | Quick starting method of air separation device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117722821A (en) |
-
2023
- 2023-12-05 CN CN202311655708.6A patent/CN117722821A/en active Pending
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