CN118224528A - Pressure and flow distribution system and method for multiple-row device in natural gas ethane recovery engineering - Google Patents
Pressure and flow distribution system and method for multiple-row device in natural gas ethane recovery engineering Download PDFInfo
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- CN118224528A CN118224528A CN202211641039.2A CN202211641039A CN118224528A CN 118224528 A CN118224528 A CN 118224528A CN 202211641039 A CN202211641039 A CN 202211641039A CN 118224528 A CN118224528 A CN 118224528A
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 224
- 239000003345 natural gas Substances 0.000 title claims abstract description 108
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 title claims abstract description 97
- 238000011084 recovery Methods 0.000 title claims abstract description 93
- 238000009826 distribution Methods 0.000 title claims abstract description 24
- 238000000034 method Methods 0.000 title claims description 7
- 239000007789 gas Substances 0.000 claims abstract description 60
- 239000002994 raw material Substances 0.000 claims abstract description 9
- 239000007788 liquid Substances 0.000 claims description 52
- 230000001105 regulatory effect Effects 0.000 claims description 38
- 230000001276 controlling effect Effects 0.000 claims description 13
- 239000012071 phase Substances 0.000 claims description 10
- 230000005540 biological transmission Effects 0.000 claims description 6
- 239000007791 liquid phase Substances 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 6
- 238000005057 refrigeration Methods 0.000 claims description 5
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 5
- 239000005977 Ethylene Substances 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 239000003208 petroleum Substances 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- -1 natural gas hydrocarbon Chemical class 0.000 description 2
- 238000004781 supercooling Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003498 natural gas condensate Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D1/00—Pipe-line systems
- F17D1/02—Pipe-line systems for gases or vapours
- F17D1/04—Pipe-line systems for gases or vapours for distribution of gas
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D3/00—Arrangements for supervising or controlling working operations
- F17D3/01—Arrangements for supervising or controlling working operations for controlling, signalling, or supervising the conveyance of a product
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D5/00—Protection or supervision of installations
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
The invention discloses a pressure and flow distribution system of a multi-row device in a natural gas ethane recovery project, which comprises a plurality of single-row natural gas ethane recovery devices, wherein the plurality of single-row natural gas ethane recovery devices are connected in parallel, the plurality of single-row natural gas ethane recovery devices are all connected with a collecting pipe, raw material gas enters into each single-row natural gas ethane recovery device through the collecting pipe to be separated, and flow and pressure control are carried out inside each single-row natural gas ethane recovery device, so that the raw material gas inlet flow of the multi-row natural gas ethane recovery device is consistent, frequent fluctuation of pressure is avoided, and stable operation of the multi-row natural gas ethane recovery device is ensured.
Description
Technical Field
The invention belongs to the technical field of light hydrocarbon recovery, relates to a pressure and flow distribution system of a multi-row device in natural gas ethane recovery engineering, and further relates to a pressure and flow distribution method of the multi-row device in the natural gas ethane recovery engineering.
Background
The ethylene raw materials in China mainly come from naphtha, the naphtha comes from petroleum, the petroleum price is high in recent years, the ethylene production cost is increased, the imported ethane is used as a construction project for producing important ethylene raw materials, the ethane supply is easy to be limited, the competition of ethylene preparation by ethane in China is weakened, and the variable is brought to the ethylene market in China. Along with the increase of the demand for ethane, at present, the natural gas is mostly recovered by light hydrocarbon, the extraction of ethane from the natural gas is used as a new trend of the development of natural gas condensate recovery technology, and the natural gas ethane recovery is used as a project of synergy of the Chinese petroleum system, so that the upstream and downstream integrated efficient development of the natural gas industry is realized.
Most of the existing domestic natural gas hydrocarbon removal devices have small treatment capacity, generally below 200 trillion square/day, and one natural gas hydrocarbon removal treatment plant only recovers propane (C 3) and more components and does not recover ethane (C 2), and for a large-scale natural gas treatment general plant, multiple columns of devices are required to operate simultaneously, such as a 200 trillion square/year treatment scale, four columns of 1500 trillion square/day natural gas ethane recovery devices are required to operate simultaneously, the phenomenon that the pressure flow of the bleed air is unstable and the pressure is related to repeatedly fluctuation is unfavorable for the stable operation of the devices, so that it is important to adjust the flow and the pressure of each column of devices by adopting a reasonable technology.
Disclosure of Invention
The invention aims to provide a pressure and flow distribution system of a plurality of columns of devices in natural gas ethane recovery engineering, which solves the problems of frequent fluctuation of pressure and flow and unstable operation of the existing natural gas ethane recovery device.
It is another object of the present invention to provide a method for distributing pressure and flow of a plurality of units in a natural gas ethane recovery project.
The technical scheme adopted by the invention is that the pressure and flow distribution system of the multi-row device in the natural gas ethane recovery engineering comprises a plurality of single-row natural gas ethane recovery devices which are connected in parallel, the plurality of single-row natural gas ethane recovery devices are all connected with a collecting pipe, raw material gas enters each single-row natural gas ethane recovery device through the collecting pipe to be separated, and the flow and pressure of each single-row natural gas ethane recovery device are controlled.
The present invention is also characterized in that,
Each single-row natural gas ethane recovery device comprises a cold box, wherein the cold box is communicated with an expander and a low-temperature separator, the low-temperature separator is connected with a demethanizer, the methane tower is connected with the cold box, raw gas enters into each row of branch pipes through a collecting pipe and goes to the low-temperature separator through the cold box, liquid separated by the low-temperature separator enters into the bottom end of the demethanizer, and part of gas in the demethanizer returns to the cold box for supercooling.
The low-temperature separator is respectively connected with the liquid level controller and the J-T valve, a liquid amount regulating valve is arranged on a pipeline of the low-temperature separator connected with the demethanizer, and when the pressure is not more than 4.1MPa, a gas phase separated from the low-temperature separator enters the demethanizer through the J-T valve; the liquid phase in the low-temperature separator is connected with the bottom of the demethanizer through a liquid quantity regulating valve, and the liquid level is automatically regulated through a liquid level controller controlling the liquid quantity regulating valve.
The low-temperature separator is connected with an expansion end inlet of the expander when the pressure is not more than 4.1MPa, the expansion end of the expander is connected with an input port of the demethanizer, part of gas in the low-temperature separator is sent to the expansion end of the expander and is sent to the input port of the demethanizer after being expanded and cooled, and an output end of the demethanizer is connected to an input port of the cold box through an output pipeline of the demethanizer; the cold box output port is connected to the booster end input port of the expander through a pipeline, the booster end output port of the expander is connected to the centrifugal compressors through pipelines, and the output ports of all rows of centrifugal compressors are connected with the external transmission collecting pipe through pipelines.
The output pipeline of the expansion end of the expander is connected with a third pressure transmitter, the output pipeline of the expansion end of the expander is connected to the input port of the demethanizer, the gas is input to the expansion end of the expander through the gas inlet pipeline of the expansion end of the expander, the gas is processed by the expansion end of the expander and then is conveyed into the demethanizer, and the third pressure transmitter detects the pressure of the gas entering the tower.
The output pipeline of the demethanizer is sequentially connected with a second pressure transmitter and a pressure regulating valve; the second pressure transmitter detects the pressure of the tower gas.
The manifold is provided with a first pressure transmitter and a first flow transmitter.
The expansion end of the expander is connected with a guide vane valve, and the guide vane valve controls the opening degree of the guide vane of the expander.
The raw material gas enters each row of branch pipes through a collecting pipe, a second flow transmitter is arranged on each single row of branch pipes, and the second flow transmitter is used for monitoring the inlet flow of each row of natural gas ethane recovery devices; the first pressure transmitter, the first flow transmitter, the second flow transmitter, the guide vane valve, the pressure regulating valve, the second pressure transmitter, the third pressure transmitter, the J-T valve, the liquid level controller and the liquid amount regulating valve are all connected with the expander control module through electric signals.
The invention adopts another technical scheme that the pressure and flow distribution method of the natural gas ethane recovery project multi-row device adopts the pressure and flow distribution system of the natural gas ethane recovery project multi-row device, and comprises the following specific steps: controlling flow and pressure signals of each row of natural gas ethane recovery devices through an expander control module, and setting each row of flow Fi = F/m when flow control is selected, wherein Fi is a flow control set value, F is a flow value displayed by a first flow transmitter, and m is the number of rows of natural gas ethane recovery devices; when the pressure control is selected, the pressure is subjected to split-control, the split-control set value is 4.1MPa, the value of the third pressure transmitter is equal to or more than 4.1MPa as the feedback value PC1, and the expander control module is used for adjusting the output signal and simultaneously adjusting the opening of the J-T valve, so that the natural gas pressure passing through the expander is controlled, and the pressure is not more than 4.1MPa; the third pressure transmitter measures the inlet pressure PC1, the PC1 is less than 4.1MPa, and the pressure is controlled by adjusting the opening of the guide vane valve;
the second pressure transmitter detects the natural gas pressure in the output pipeline of the demethanizer and transmits the natural gas pressure to the expander control module, and the expander control module changes the natural gas pressure in the output pipeline of each row of demethanizer by controlling the rotating speed of the pressurizing end of the expander according to a PID algorithm;
when the second pressure fluctuation device measures that the outlet pressure value PC2 of the demethanizer is more than 3.2MPa, the pressure value PC2 is transmitted to the expander control module, and the expander control module adjusts the output signal and simultaneously adjusts the opening of the guide vane valve.
The beneficial effects of the invention are as follows: the invention discloses a pressure and flow distribution system of a plurality of rows of devices in natural gas ethane recovery engineering, which comprises a plurality of single-row natural gas ethane recovery devices connected in parallel, wherein each row of natural gas ethane recovery devices comprises a demethanizer, an expansion end of an expander, a pressurizing end of the expander, an expander control module, guide vanes and a J-T valve. The expander control module controls linkage protection of the guide vane-JT valve of the expander, selects control, split-range control and ultra-pool control to realize the consistency of feed gas inlet flow of the feed gas of the multi-row natural gas ethane recovery device, avoids frequent fluctuation of pressure and ensures stable operation of the multi-row natural gas ethane recovery device.
Drawings
FIG. 1 is a schematic diagram of the pressure and flow distribution system of the natural gas ethane recovery engineering multi-row device of the invention.
In the figure, 1, a first pressure transmitter, 2, a first flow transmitter, 3, a second flow transmitter, 4, a cold box, 5, a low temperature separator, 6, an expander boost end, 7, an expander expansion end, 8, a vane valve, 9, an electrically operated regulator valve, 10, a second pressure transmitter, 11, a third pressure transmitter, 12, J-T valve, 13, a demethanizer, 14, a liquid level regulator valve, 15, a liquid level controller, 16, an expander control module, 17, a centrifugal compressor.
Detailed Description
The invention will be described in detail below with reference to the drawings and the detailed description.
The invention relates to a pressure and flow distribution system of a multi-row device in natural gas ethane recovery engineering, which is shown in figure 1 and comprises a plurality of single-row natural gas ethane recovery devices, wherein the plurality of single-row natural gas ethane recovery devices are connected in parallel, the plurality of single-row natural gas ethane recovery devices are all connected with a collecting pipe, raw gas enters into each single-row natural gas ethane recovery device through the collecting pipe to be separated, flow and pressure control are carried out in each single-row natural gas ethane recovery device, pressure and flow stability are realized, and repeated fluctuation of device pressure association is avoided.
Each single-row natural gas ethane recovery device comprises a cold box 4, wherein the cold box 4 is communicated with an expander and a low-temperature separator 5, the low-temperature separator 5 is connected with a demethanizer 13, the methane tower 13 is connected with the cold box 4, raw gas enters into each row of branch pipes through a collecting pipe and goes to the low-temperature separator 5 through the cold box 4, liquid separated by the low-temperature separator 5 enters into the bottom end of the demethanizer 13, and a part of gas in the demethanizer 13 is supercooled by the cold box 4 again.
The low-temperature separator 5 is respectively connected with a liquid level controller 15 and a J-T valve 12, a liquid amount regulating valve 14 is arranged on a pipeline of the low-temperature separator 5 connected with the demethanizer 13, and when the pressure is not more than 4.1MPa, a gas phase separated from the low-temperature separator 5 enters the demethanizer 13 through the J-T valve 12; the liquid phase in the low-temperature separator 5 is connected with the bottom of the demethanizer 13 through a liquid quantity regulating valve 14, and the liquid level is automatically regulated by controlling the liquid quantity regulating valve 14 through a liquid level controller 15.
The expander comprises an expander pressurizing end 6, an expander expansion end 7 and an expander control module 16, when the pressure is not more than 4.1MPa, the low-temperature separator 5 is connected with the inlet of the expander expansion end 7, the expander expansion end 7 is connected with the input port of the demethanizer 13, part of gas in the low-temperature separator 5 is sent to the expander expansion end 7, and after expansion and refrigeration, the gas is sent to the inlet of the demethanizer 13, and the output end of the demethanizer 13 is connected to the input port of the cold box 4 through the output pipeline of the demethanizer; the output port of the cold box 4 is connected to the input port of the booster end 6 of the expander through a pipeline, the output port of the booster end 6 of the expander is connected to the centrifugal compressors through pipelines, and the output ports of all rows of centrifugal compressors are connected with an external transmission collecting pipe through pipelines. The booster end 6 of the expander is used for recovering the energy of the ventilation pressure difference, driving the centrifugal compressor connected with the booster end to work, further changing the pressure in the pipeline, and simultaneously carrying out air intake and air exhaust when the system works, so that dynamic balance is formed in each single-row natural gas ethane recovery device.
The output pipeline of the expansion end 7 of the expander is connected with a third pressure transmitter 11, the output pipeline of the expansion end 7 of the expander is connected to the input port of the demethanizer 13, the gas is input into the expansion end 7 of the expander through the gas inlet pipeline of the expansion end of the expander, the gas is processed by the expansion end 7 of the expander and then is conveyed into the demethanizer 13, and the third pressure transmitter 11 detects the pressure of the gas entering the tower. The output pipeline of the demethanizer 13 is sequentially connected with a second pressure transmitter 10 and a pressure regulating valve 9; the second pressure transmitter 10 detects the pressure of the tower gas.
The header is provided with a first pressure transmitter 1 and a first flow transmitter 2.
The expansion end 7 of the expander is connected with a guide vane valve 8, the guide vane valve 8 controls the opening of the guide vane of the expander, and further controls the flow in a pipeline, and the opening of the guide vane is 0-100%.
The raw material gas enters each row of branch pipes through a collecting pipe, a second flow transmitter 3 is arranged on each row of branch pipes, and the second flow transmitter 3 is used for monitoring the inlet flow of each row of natural gas ethane recovery devices; the first pressure transmitter 1, the first flow transmitter 2, the second flow transmitter 3, the guide vane valve 8, the pressure regulating valve 9, the second pressure transmitter 10, the third pressure transmitter 11, the J-T valve 12, the liquid level controller 15 and the liquid level regulating valve 14 are all electrically connected with the expander control module 16.
The invention relates to a pressure and flow distribution method for a plurality of devices in a natural gas ethane recovery project, which adopts the pressure and flow distribution system for the plurality of devices in the natural gas ethane recovery project, and comprises the following specific steps: controlling flow and pressure signals of each row of natural gas ethane recovery units by an expander control module 16, and setting each row of flow fi=f/m when flow control is selected, wherein Fi is a flow control set value, F is a flow value displayed by a first flow transmitter, and m is the number of columns of natural gas ethane recovery units; when pressure control is selected, the pressure is subjected to split-phase control, the split-phase control set value is 4.1MPa, the numerical value of the third pressure transmitter 11 is equal to or more than 4.1MPa when the feedback value PC1 is equal to or more than 4.1MPa, and the expander control module 16 is used for adjusting output signals and simultaneously adjusting the opening of the J-T valve 12, so that the natural gas pressure passing through the expander is controlled, and the pressure is not more than 4.1MPa; the third pressure transmitter 11 measures the inlet pressure PC1, PC1 is less than 4.1MPa, and the pressure is controlled by adjusting the opening of the guide vane valve 8;
The second pressure transmitter 10 detects the natural gas pressure in the demethanizer output lines and sends it to the expander control module 16, and the expander control module 16 varies the natural gas pressure in each column of demethanizer output lines by controlling the speed of the expander boost end 6 according to a PID algorithm.
When the second pressure changer 10 measures the outlet pressure value PC2 of the demethanizer to be more than 3.2MPa, the outlet pressure value PC2 is transmitted to the expander control module 16, and the expander control module 16 adjusts the output signal and simultaneously adjusts the opening of the guide vane valve 8.
If the expander fails to stop, the expander control module 16 immediately outputs a valve position given value of the J-T valve 12, and gives a preset opening of 30%, and controls the opening of the J-T valve 12 according to a PID algorithm on the condition of a normal value P0 or F0, so that the value measured by the third pressure transmitter 10 is kept at P0 or the flow of the second flow transmitter 3 is kept at F0.
In each single-row natural gas ethane recovery device, an expander control module 16 forms a PID control loop through a guide vane valve 8 and a J-T valve 12 to regulate an inlet guide vane of the expander, when the opening degree of the guide vane valve 8 for controlling the guide vane reaches 100%, the operation takes an average value of 1 minute as feedback, the J-T valve 12 starts to regulate relay, the treatment scale range is 1050-1500 multiplied by 104m 3/d, a set value is determined according to the numerical value of a first flow transmitter 2 of a manifold, the numerical value of the first flow transmitter 2 is recorded as Fi, and a set value FC=Fi/m, wherein m is the number of device columns.
The expander control module 16 carries out the branch-and-range control on the inlet pressure of the expansion end of the expander, the inlet pressure of the expander, the inlet guide vane of the expansion end and the J-T valve 12 form a PID control loop, the inlet guide vane of the expander is regulated, when the opening degree of the guide vane reaches 100%, the J-T valve 12 starts to regulate relay, and the normal set value is 3.8MPa.g.
The expander control module 16 protects the expander expansion end outlet pressure from overpressure, and when the expander outlet pressure exceeds 3.2mpa.g, the expander inlet guide vane and the J-T valve preferably adjust PT-04a0406 values, and the PT-04a0406 set value is 3.2mpa.g, and reset is manually confirmed.
Control of the independent operation of the J-T valve 12 by the expander control module 16: when the expander is overhauled, the J-T valve 12 independently controls the inlet flow, the inlet pressure and the outlet pressure, the opening of the J-T valve is automatically adjusted according to the flow of the gas collecting zone or the inlet pressure of the expander or the outlet pressure of the expander, the set value of the flow and the pressure is 3.8MPa, and the protection of the outlet pressure is 3.2MPa.
The expander control module 16 shuts down the expander for an expander failure emergency stop or for a low temperature separator high-high level interlock: the J-T valve 12 automatically takes over and PID adjusts based on the expander inlet pressure or device flow.
The expander control module 16 monitors the expander booster train: the booster unit is provided with a PLC (programmable logic controller) to independently finish normal loading starting, stopping, anti-surge, protection stopping, emergency stopping and the like of the unit, and performs data exchange with the DCS through a redundant Ethernet. Hard-wired remote monitoring of the unit: allowing start, stop, run status, fault alarms, etc. See IO table and DCS monitoring table in detail. The emergency stop state contact signal output (including fault, other emergency stop logic trigger, relative normal stop output) and the guide vane opening 4-20mA output.
Example 1
The pressure and flow distribution system of the multi-row device in the natural gas ethane recovery engineering in the embodiment 1 comprises four single-row natural gas ethane recovery devices, wherein the four single-row natural gas ethane recovery devices are connected in parallel and comprise four rows of natural gas ethane recovery devices, each row of natural gas ethane recovery devices comprises a demethanizer, an expansion end of an expander, a pressurizing end of the expander, an expander control module, guide vanes and J-T valves, so that the stable operation of the multi-row natural gas ethane recovery devices is realized, and frequent fluctuation of the pressure of the device is avoided.
Example 2
In this embodiment 2, the pressure and flow distribution system of the multiple-row device in the natural gas ethane recovery engineering comprises four single-row natural gas ethane recovery devices, the multiple single-row natural gas ethane recovery devices are connected in parallel, raw gas enters into the branch pipes of each row of devices through a collecting pipe, goes to the cryogenic separator 5 through the cold box 4, liquid separated by the cryogenic separator 5 enters into the bottom end of the demethanizer 13, part of the gas returns to the cold box to be supercooled, the other part of the gas goes to the expansion end inlet 7 of the expander, and enters into the demethanizer 13 after expansion refrigeration, the collecting pipe is provided with the first pressure fluctuation device 1 and the first flow transmitter 2, and the single-row branch pipes are provided with the second flow transmitter 3, which are all connected with the electric signal of the expander control module. The outlet pipeline of the expansion end 7 of the expansion machine is also connected with a third pressure transmitter 11, the third pressure transmitter 11 is connected with an expansion machine control module 16, the output port of the expansion end 7 of the expansion machine is connected to the input port of a demethanizer 13 through an output pipeline of the expansion end, the output port of the demethanizer 13 is connected to the input port of a cold box 16 through an output pipeline of the demethanizer, the output pipeline of the demethanizer 13 is also connected with a second pressure transmitter 10 and a pressure regulating valve 9, the output port of the cold box 4 is connected to the input port of the supercharging end 6 of the expansion machine through a pipeline, the output port of the supercharging end 6 of the expansion machine is connected to a centrifugal compressor through a pipeline, the expansion end 7 of the expansion machine is also connected with a guide vane valve 8, the guide vane valve 8 is connected with an electric signal of the expansion machine control module, the output ports of each row of the expansion end are connected to respective pretreatment devices, and the output ports of the centrifugal compressors of each row are connected with an external transmission manifold through pipelines.
Example 3
The pressure and flow distribution system of the multi-row device in the natural gas ethane recovery project of the embodiment 3 comprises a plurality of single-row natural gas ethane recovery devices, the plurality of single-row natural gas ethane recovery devices are connected in parallel, the plurality of single-row natural gas ethane recovery devices are all connected with a collecting pipe, raw gas enters into each single-row natural gas ethane recovery device through the collecting pipe to be separated into pipes, flow and pressure control are carried out inside each single-row natural gas ethane recovery device, each single-row natural gas ethane recovery device comprises a cold box 4, the cold box 4 is communicated with an expansion machine and a low-temperature separator 5, the low-temperature separator 5 is connected with a demethanizer 13, the methane tower 13 is connected with the cold box 4, the raw gas enters into each row of separated pipes through the collecting pipe, goes to the low-temperature separator 5 through the cold box 4, liquid separated by the low-temperature separator 5 enters into the bottom end of the demethanizer 13, and part of gas in the demethanizer 13 returns to the cold box 4 for supercooling. The low-temperature separator 5 is respectively connected with a liquid level controller 15 and a J-T valve 12, a liquid amount regulating valve 14 is arranged on a pipeline of the low-temperature separator 5 connected with the demethanizer 13, and when the pressure is not more than 4.1MPa, a gas phase separated from the low-temperature separator 5 enters the demethanizer 13 through the J-T valve 12; the liquid phase in the low-temperature separator 5 is connected with the bottom of the demethanizer 13 through a liquid quantity regulating valve 14, and the liquid level is automatically regulated by controlling the liquid quantity regulating valve 14 through a liquid level controller 15.
The expander comprises an expander pressurizing end 6, an expander expansion end 7 and an expander control module 16, when the pressure is not more than 4.1MPa, the low-temperature separator 5 is connected with the inlet of the expander expansion end 7, the expander expansion end 7 is connected with the input port of the demethanizer 13, part of gas in the low-temperature separator 5 is sent to the expander expansion end 7, and after expansion and refrigeration, the gas is sent to the inlet of the demethanizer 13, and the output end of the demethanizer 13 is connected to the input port of the cold box 4 through the output pipeline of the demethanizer; the output port of the cold box 4 is connected to the input port of the booster end 6 of the expander through a pipeline, the output port of the booster end 6 of the expander is connected to the centrifugal compressors through pipelines, and the output ports of all rows of centrifugal compressors are connected with an external transmission collecting pipe through pipelines. The low-temperature separator 5 is respectively connected with a liquid level controller 15 and a J-T valve 12, a liquid amount regulating valve 14 is arranged on a pipeline of the low-temperature separator 5 connected with the demethanizer 13, and when the pressure is not more than 4.1MPa, a gas phase separated from the low-temperature separator 5 enters the demethanizer 13 through the J-T valve 12; the liquid phase in the low-temperature separator 5 is connected with the bottom of the demethanizer 13 through a liquid quantity regulating valve 14, and the liquid level is automatically regulated by controlling the liquid quantity regulating valve 14 through a liquid level controller 15.
Example 4
In this embodiment 4, the pressure and flow distribution system of the multiple-row device in the natural gas ethane recovery project, as shown in fig. 1, includes multiple single-row natural gas ethane recovery devices, the multiple single-row natural gas ethane recovery devices are connected in parallel, the multiple single-row natural gas ethane recovery devices are all connected with a collecting pipe, raw gas enters into each single-row natural gas ethane recovery device branch pipe through the collecting pipe, flow and pressure control is performed inside each single-row natural gas ethane recovery device, each single-row natural gas ethane recovery device includes a cold box 4, the cold box 4 is communicated with an expander and a low-temperature separator 5, the low-temperature separator 5 is connected with a demethanizer 13, the methane tower 13 is connected with the cold box 4, raw gas enters into each row branch pipe through the collecting pipe, goes to the low-temperature separator 5 through the cold box 4, liquid separated by the low-temperature separator 5 enters into the bottom end of the demethanizer 13, and a part of gas in the demethanizer 13 is re-cooled by the cold box 4.
The low-temperature separator 5 is respectively connected with a liquid level controller 15 and a J-T valve 12, a liquid amount regulating valve 14 is arranged on a pipeline of the low-temperature separator 5 connected with the demethanizer 13, and when the pressure is not more than 4.1MPa, a gas phase separated from the low-temperature separator 5 enters the demethanizer 13 through the J-T valve 12; the liquid phase in the low-temperature separator 5 is connected with the bottom of the demethanizer 13 through a liquid quantity regulating valve 14, and the liquid level is automatically regulated by controlling the liquid quantity regulating valve 14 through a liquid level controller 15.
The expander comprises an expander pressurizing end 6, an expander expansion end 7 and an expander control module 16, when the pressure is not more than 4.1MPa, the low-temperature separator 5 is connected with the inlet of the expander expansion end 7, the expander expansion end 7 is connected with the input port of the demethanizer 13, part of gas in the low-temperature separator 5 is sent to the expander expansion end 7, and after expansion and refrigeration, the gas is sent to the inlet of the demethanizer 13, and the output end of the demethanizer 13 is connected to the input port of the cold box 4 through the output pipeline of the demethanizer; the output port of the cold box 4 is connected to the input port of the booster end 6 of the expander through a pipeline, the output port of the booster end 6 of the expander is connected to the centrifugal compressors through pipelines, and the output ports of all rows of centrifugal compressors are connected with an external transmission collecting pipe through pipelines. The output pipeline of the expansion end 7 of the expander is connected with a third pressure transmitter 11, the output pipeline of the expansion end 7 of the expander is connected to the input port of the demethanizer 13, the gas is input into the expansion end 7 of the expander through the gas inlet pipeline of the expansion end of the expander, the gas is processed by the expansion end 7 of the expander and then is conveyed into the demethanizer 13, and the third pressure transmitter 11 detects the pressure of the gas entering the tower. The output pipeline of the demethanizer 13 is sequentially connected with a second pressure transmitter 10 and a pressure regulating valve 9; the second pressure transmitter 10 detects the pressure of the tower gas. The header is provided with a first pressure transmitter 1 and a first flow transmitter 2. The expansion end 7 of the expander is connected with a guide vane valve 8, the guide vane valve 8 controls the opening of the guide vane of the expander, and further controls the flow in a pipeline, and the opening of the guide vane is 0-100%.
The raw material gas enters each row of branch pipes through a collecting pipe, a second flow transmitter 3 is arranged on each row of branch pipes, and the second flow transmitter 3 is used for monitoring the inlet flow of each row of natural gas ethane recovery devices; the first pressure transmitter 1, the first flow transmitter 2, the second flow transmitter 3, the guide vane valve 8, the pressure regulating valve 9, the second pressure transmitter 10, the third pressure transmitter 11, the J-T valve 12, the liquid level controller 15 and the liquid level regulating valve 14 are all electrically connected with the expander control module 16.
Claims (10)
1. The pressure and flow distribution system of the multi-row device of the natural gas ethane recovery engineering is characterized by comprising a plurality of single-row natural gas ethane recovery devices, wherein the plurality of single-row natural gas ethane recovery devices are connected in parallel, the plurality of single-row natural gas ethane recovery devices are all connected with a collecting pipe, raw material gas enters into each single-row natural gas ethane recovery device through the collecting pipe to be branched, and flow and pressure control is carried out inside each single-row natural gas ethane recovery device.
2. The system for distributing pressure and flow of multiple columns of devices in natural gas ethane recovery engineering according to claim 1, wherein each single column of natural gas ethane recovery device comprises a cold box (4), the cold box (4) is communicated with an expander and a low-temperature separator (5), the low-temperature separator (5) is connected with a demethanizer (13), the methane tower (13) is connected with the cold box (4), raw gas enters each column of branch pipes through a collecting pipe and goes to the low-temperature separator (5) through the cold box (4), liquid separated by the low-temperature separator (5) enters the bottom end of the demethanizer (13), and a part of gas in the demethanizer (13) is supercooled back to the cold box (4).
3. The natural gas ethane recovery engineering multi-row device pressure and flow distribution system according to claim 2, wherein the low-temperature separator (5) is respectively connected with a liquid level controller (15) and a J-T valve (12), a liquid amount regulating valve (14) is arranged on a pipeline of the low-temperature separator (5) connected with the demethanizer (13), and when the pressure is not more than 4.1MPa, a gas phase separated from the low-temperature separator (5) enters the demethanizer (13) through the J-T valve (12); the liquid phase in the low-temperature separator (5) is connected with the bottom of the demethanizer (13) through a liquid quantity regulating valve (14), and the liquid level is automatically regulated by controlling the liquid quantity regulating valve (14) through a liquid level controller (15).
4. A natural gas ethane recovery engineering multi-line device pressure and flow distribution system according to claim 3, wherein the expander comprises an expander pressurizing end (6), an expander expanding end (7) and an expander control module (16), when the pressure is not more than 4.1MPa, the cryogenic separator (5) is connected with an inlet of the expander expanding end (7), the expander expanding end (7) is connected with an inlet of a demethanizer (13), a part of gas in the cryogenic separator (5) is sent to the expander expanding end (7) and is sent to the inlet of the demethanizer (13) after expansion refrigeration, and an output end of the demethanizer (13) is connected with an inlet of a cold box (4) through a demethanizer output pipeline; the output port of the cold box (4) is connected to the input port of the booster end (6) of the expander through a pipeline, the output port of the booster end (6) of the expander is connected to the centrifugal compressors through pipelines, and the output ports of all rows of centrifugal compressors are connected with an external transmission collecting pipe through pipelines.
5. The system for distributing pressure and flow of the natural gas ethane recovery engineering multi-row device according to claim 4, wherein an output pipeline of an expansion end (7) of the expander is connected with a third pressure transmitter (11), the output pipeline of the expansion end (7) of the expander is connected to an input port of a demethanizer (13), the gas is input to the expansion end (7) of the expander through an air inlet pipeline of the expansion end, the gas is processed by the expansion end (7) of the expander and then is conveyed into the demethanizer (13), and the third pressure transmitter (11) detects the pressure of the gas entering the tower.
6. The natural gas ethane recovery engineering multi-row device pressure and flow distribution system according to claim 5, wherein the output pipeline of the demethanizer (13) is sequentially connected with a second pressure transmitter (10) and a pressure regulating valve (9); a second pressure transmitter (10) detects the pressure of the tower gas.
7. The natural gas ethane recovery engineering multi-row device pressure and flow distribution system according to claim 6, wherein a first pressure transmitter (1) and a first flow transmitter (2) are arranged on the collecting pipe.
8. The natural gas ethane recovery engineering multi-row device pressure and flow distribution system according to claim 7, wherein a guide vane valve (8) is connected to the expansion end (7) of the expander, and the guide vane valve (8) controls the opening degree of guide vanes of the expander.
9. The system for distributing pressure and flow of the multiple columns of devices in the natural gas ethane recovery engineering according to claim 8, wherein the raw gas enters each column of branch pipes through a collecting pipe, a second flow transmitter (3) is arranged on each column of branch pipes, and the second flow transmitter (3) is used for monitoring the inlet flow of each column of natural gas ethane recovery devices; the first pressure transmitter (1), the first flow transmitter (2), the second flow transmitter (3), the guide vane valve (8), the pressure regulating valve (9), the second pressure transmitter (10), the third pressure transmitter (11), the J-T valve (12), the liquid level controller (15) and the liquid level regulating valve (14) are all connected with an electric signal of the expander control module (16).
10. The method for distributing the pressure and the flow of the natural gas ethane recovery engineering multi-row device comprises the following specific steps of: controlling flow and pressure signals of each row of natural gas ethane recovery devices through an expander control module (16), and setting each row of flow Fi = F/m when flow control is selected, wherein Fi is a flow control set value, F is a flow value displayed by a first flow transmitter, and m is the number of columns of natural gas ethane recovery devices; when pressure control is selected, the pressure is subjected to split-phase control, a split-phase control set value is 4.1MPa, the numerical value of a third pressure transmitter (11) is more than or equal to 4.1MPa when a feedback value PC1 is equal to or greater than 4.1MPa, an expander control module (16) is used for adjusting an output signal and simultaneously adjusting the opening of a J-T valve (12), so that the pressure of natural gas passing through the expander in the row is controlled, and the pressure is not more than 4.1MPa; the third pressure transmitter (11) measures the inlet pressure PC1, the PC1 is less than 4.1MPa, and the pressure is controlled by adjusting the opening of the guide vane valve (8);
The second pressure transmitter (10) detects the natural gas pressure in the output pipeline of the demethanizer and transmits the natural gas pressure to the expander control module (16), and the expander control module (16) changes the natural gas pressure in the output pipeline of each row of demethanizer by controlling the rotating speed of the pressurizing end (6) of the expander according to a PID algorithm;
When the second pressure fluctuation device (10) measures that the output pressure value PC2 of the demethanizer is more than 3.2MPa, the output pressure value PC2 is transmitted to the expander control module (16), and the expander control module (16) adjusts the output signal and simultaneously adjusts the opening of the guide vane valve (8).
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| CN202211641039.2A CN118224528A (en) | 2022-12-20 | 2022-12-20 | Pressure and flow distribution system and method for multiple-row device in natural gas ethane recovery engineering |
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