CN105318193B - A kind of low-pressure nitrogen manifold system and control method - Google Patents

Abstract

The present invention relates to a kind of low-pressure nitrogen manifold system, including at least three space divisions；First main pipe, first main pipe comprises at least the first son pipe, the second son pipe and the 3rd son pipe, the first sub- space division of pipe first and connected, the second sub- space division of pipe second connection, the 3rd sub- space division of pipe the 3rd connection, the first son pipe, the second son pipe and the 3rd sub- pipe are connected by inlet tube with nitrogen compressor respectively；Second main pipe, second main pipe comprises at least the 4th son pipe, the 5th son pipe and the 6th son pipe, 5th son pipe with the second sub- pipe by being connected the first communicating pipe, 6th son pipe with the 3rd sub- pipe by being connected the second communicating pipe, the 4th sub- space division of pipe first connection, the 5th son pipe and the 6th sub- pipe are connected by inlet tube with nitrogen compressor respectively.It can ensure the public of any nitrogen compressor on house steward when any space division is run.

Description

A low-pressure nitrogen main pipe system and control method

technical field

The invention relates to a low-pressure nitrogen main pipe system and a control method.

Background technique

Low-pressure nitrogen (referred to as "low-pressure nitrogen") is produced by a low-temperature rectification oxygen generator (referred to as "air separation"), and then sent to the low-pressure nitrogen main pipe; medium-pressure nitrogen compressor or high-pressure nitrogen compressor (referred to as "nitrogen compressor") ) sucks low-pressure nitrogen from the main pipe, pressurizes it, processes it into medium-pressure nitrogen or high-pressure nitrogen, and delivers it to users. According to the user's demand for nitrogen, a corresponding number of nitrogen compressors with pressure delivery capacity are configured on the low-pressure nitrogen main pipe at the air separation outlet, that is, the start, stop and pressure delivery of the nitrogen compressor are based on the total low-pressure nitrogen of the air separation unit. controlled by production capacity.

Fig. 1 is a structural schematic diagram of a medium and low pressure nitrogen main pipe system in the prior art. As shown in Figure 1, in the prior art, the low-pressure nitrogen main pipes are independent and not connected to each other. No. 6 air separation 10 is equipped with 1 medium-pressure nitrogen compressor 407 (referred to as "No. 7 medium-pressure nitrogen"); No. 7 air separation 20 is equipped with 1 medium-pressure nitrogen compressor 409 (referred to as "No. 9 medium-pressure nitrogen"), 2 sets High-pressure nitrogen compressors 507 and 508 (referred to as "No. 7 high-pressure nitrogen" and "No. 8 high-pressure nitrogen"); No. 8 air separation unit 30 is equipped with 1 medium-pressure nitrogen compressor 410 (referred to as "No. 10 medium-pressure nitrogen") and 1 set High-pressure nitrogen compressor 509 (referred to as "No. 9 high-pressure nitrogen"). With the development of the industry, the demand for nitrogen gas has increased significantly. Therefore, after transformation, the low-pressure nitrogen main pipes 701, 702, and 703 of the three air separation units are connected to a main pipe 70, and node valves 61 and 62 are set between adjacent two air separation units. The air separation and nitrogen compressors can be called each other, that is, each nitrogen compressor can be freely adjusted according to the total low-pressure nitrogen production capacity of the three air separation units, and the overall nitrogen delivery rate can be increased.

However, there are following problems in the above-mentioned low-pressure nitrogen main pipe system in the prior art:

1. The main pipe 70 is a pipeline, which is arranged in the order of No. 6 air separation 10, No. 7 air separation 20, and No. 8 air separation 30. Node valves 61 and 62 are provided between adjacent two space divisions; when some pipe sections, When there is a problem with the equipment and the node valve needs to be closed, the adjacent pipe sections cannot be connected, and the nitrogen compressors of each other cannot be freely called. For example, after closing any node valve, No. 6 air separation 10 and No. 8 air separation 30 cannot be connected when they are running at the same time, and No. 7 medium-pressure nitrogen 407 and No. 10 medium-pressure nitrogen 410 cannot be shared.

2. Each nitrogen compressor is connected with its own air distribution system, and the start and stop interlocks are still controlled by its own air separation system. For example, when the No. 7 air separation unit 10 jumps abnormally, the interlock will be triggered and the No. 9 medium pressure nitrogen 409, No. 7 High-pressure nitrogen 507 and No. 8 high-pressure nitrogen 508 all tripped and stopped.

3. When two or more air separation units are running at the same time, and more than one of them suddenly jumps, the pressure of the near side pipe section of the jumping air separation unit will drop instantaneously, and it is too late to be supplemented by other air separation units, which will cause the near side nitrogen compressor to fail. The suction pressure is low and the car jumps.

No. 4 and No. 6 air separation 10 have been transformed, and the production of low-pressure nitrogen has been greatly increased, and there is only one No. 7 medium-pressure nitrogen 407 near it, which needs to be sent through other nitrogen compressors on the main pipe; when the aforementioned 1, 2, and 3 types In either case, the incremental output cannot be smoothly conveyed.

5. After the air separation low-pressure nitrogen production is increased, the original nitrogen compressor is not enough to deliver the full amount, so a new nitrogen compressor is required; but the capacity of the main pipe is limited, and after the density of the nitrogen compressor increases, when the aforementioned third situation occurs, the consequences will be more serious.

Contents of the invention

In order to solve the above technical problems, the present invention provides a low-pressure nitrogen main pipe system and control method, which can ensure the common use of any nitrogen compressor on the main pipe during any air separation operation, even when the air separation suddenly trips, it can Perform rapid control and stable operation.

The low-pressure nitrogen main pipe system that the present invention relates to comprises:

At least three air separations including the first air separation, the second air separation and the third air separation, which produce low-pressure nitrogen; the first main pipe, the first main pipe at least includes the first sub-pipes connected successively, The second sub-pipe and the third sub-pipe, a first node valve is set between the first sub-pipe and the second sub-pipe, and a first node valve is set between the second sub-pipe and the third sub-pipe There is a second node valve, the first sub-pipe is connected to the first air separation through the first low-pressure nitrogen delivery pipeline, and the second sub-pipe is connected to the second air separation through the second low-pressure nitrogen delivery pipeline, The third sub-pipe is connected to the third air separation through the third low-pressure nitrogen sending pipeline, and the first sub-pipe, the second sub-pipe and the third sub-pipe are respectively connected to the nitrogen compressor through the inlet pipe;

The second main pipe, the second main pipe at least includes a fourth sub-pipe, a fifth sub-pipe and a sixth sub-pipe, a third node valve is arranged between the fourth sub-pipe and the fifth sub-pipe, A fourth node valve is provided between the fifth sub-pipe and the sixth sub-pipe, the fifth sub-pipe is connected to the second sub-pipe through the first communication pipe, and the sixth sub-pipe is connected to the second sub-pipe through the first communication pipe. The second connecting pipe is connected to the third sub-pipe, the fourth sub-pipe is connected to the first air separation pipe through the fourth low-pressure nitrogen delivery pipe, and the fifth sub-pipe and the sixth sub-pipe are respectively passed through the inlet The tube is connected to a nitrogen compressor.

Preferably, it also includes a plurality of purging devices arranged at both ends of each sub-pipe for purging each sub-pipe to detect whether the purity of the low-pressure nitrogen in each sub-pipe is qualified.

Preferably, the purging device includes a purging pipe, a purging valve and an analysis sampling valve arranged on the purging pipe.

Preferably, one end of the first sub-pipe, the third sub-pipe, the fourth sub-pipe and/or the sixth sub-pipe without a node valve is provided with a blind plate.

Preferably, node valves are provided at both ends of the first sub-pipe, the third sub-pipe, the fourth sub-pipe and/or the sixth sub-pipe.

In addition, the present invention also relates to a control method based on the above-mentioned low-pressure nitrogen main pipe system, the control method comprising:

The first node valve, the second node valve, the third node valve and the fourth node valve are closed, and the purge device is started to purge each sub-pipe to detect the purity of low-pressure nitrogen in each sub-pipe;

For any node valve in the first node valve, the second node valve, the third node valve and the fourth node valve, when the purity of low-pressure nitrogen in the sub-pipes on both sides of the node valve is detected to meet the conditions, the node valve is opened ;According to the scheduled total production capacity, operate one or more air separation and nitrogen compressors independently or in combination;

Close the corresponding node valves as required to realize the connection or isolation of each air separation low-pressure nitrogen.

The single or combined operation of one or more air separation and nitrogen compressors includes:

When only a single air separation unit needs to be operated, run the nitrogen compressor connected to the same sub-pipe as the air separation unit;

When multiple air separation units are operated in combination, the nitrogen compressor connected to the same sub-pipe as the running air separation unit should be run first, and then the nitrogen compressor connected to other sub-pipes should be selected to run.

Preferably, it also includes:

When one of the air separation units is tripped, or the air separation unit is unloaded, the nitrogen compressor that is connected to the air separation unit will be unloaded without tripping, and the other nitrogen compressors will not be unloaded or tripped, and according to User command to stop one or more nitrogen compressors.

Preferably, it also includes:

For any nitrogen compressor, when its own failure trips and interlocks, it will jump directly and start other nitrogen compressors with the same amount according to user instructions.

Preferably, it also includes:

For any nitrogen compressor, when the suction pressure is low, it will send an alarm and then unload, but it will not trip, and continue to operate normally after the main pipe recovers the pressure; when the suction pressure of the nitrogen compressor is too low, it will jump directly.

Using the low-pressure nitrogen main pipe system and control method of the present invention can ensure the common use of any nitrogen compressor on the main pipe during any air separation operation, and can perform rapid control and stable operation even when the air separation suddenly trips.

Description of drawings

Fig. 1 is the structural representation of prior art medium and low pressure nitrogen main pipe system;

Fig. 2 is the structural representation of the low-pressure nitrogen main pipe system involved in the present invention;

FIG. 3 is a schematic structural view of the purging device S in FIG. 2 .

detailed description

A specific embodiment of the present invention will be described below in conjunction with accompanying drawing 2 . Fig. 2 is the structure diagram of the low-pressure nitrogen main pipe system involved in the present invention, as shown in the figure, the first main pipe 70 is divided into the first sub-pipe 701, the second sub-pipe 702, and the third sub-pipe 703, in the first Both ends of the main pipe 70 are provided with blind plates 711 and 712 . A first node valve 61 is disposed between the first sub-pipe 701 and the second sub-pipe 702 , and a second node valve 62 is disposed between the second sub-pipe 702 and the third sub-pipe 703 . When the first main pipe 70 needs to be expanded, in order to connect more air separation and sub-pipes, the blind plates 711 and/or 712 can be replaced with node valves. The first air separation 10 is connected with the first sub-pipe 701 through the first low-pressure nitrogen sending pipeline 101; the second air separation 20 is connected with the second sub-pipe 702 through the second low-pressure nitrogen sending pipeline 201; the third air separation 30 is connected through the third The low-pressure nitrogen delivery pipeline 301 is connected with the third sub-pipe 703 .

The first nitrogen compressor 407 is connected to the first sub-pipe 711 through the first inlet pipe 4071, and the first nitrogen compressor 407 is a medium-pressure nitrogen compressor. The second nitrogen compressor 409 is connected to the second sub-pipe 702 through the second inlet pipe 4091, the third nitrogen compressor 507 is connected to the second sub-pipe 702 through the third inlet pipe 5071, and the fourth nitrogen compressor 508 is connected to the second sub-pipe 702 through the third inlet pipe 5071. The four inlet pipes 5081 are connected to the second sub-pipe 702, wherein the second nitrogen compressor 409 is a medium pressure nitrogen compressor, the third nitrogen compressor 507 and the fourth nitrogen compressor 508 are high pressure nitrogen compressors. The fifth nitrogen compressor 410 is connected to the third sub-pipe 703 through the fifth inlet pipe 4101 , and the sixth nitrogen compressor 509 is connected to the third sub-pipe 703 through the sixth inlet pipe 5091 . The fifth nitrogen compressor 410 is a medium pressure nitrogen compressor, and the sixth nitrogen compressor 509 is a high pressure nitrogen compressor.

The second main pipe 80 is divided into a fourth sub-pipe 801 , a fifth sub-pipe 802 and a sixth sub-pipe 803 , and blind pipes 812 and blind plates 811 are respectively provided at both ends of the second main pipe 80 . A third node valve 63 is disposed between the fourth sub-pipe 801 and the fifth sub-pipe 802 , and a fourth node valve 64 is disposed between the fifth sub-pipe 802 and the sixth sub-pipe 803 . When the capacity of the second main pipe 80 needs to be expanded, in order to connect more air separation and sub-pipes, the blind plates 811 and/or 812 can be replaced with node valves. The fifth sub-pipe 802 is connected to the seventh nitrogen compressor 408 through the seventh inlet pipe 4081, and the seventh nitrogen compressor 408 is a medium-pressure nitrogen compressor. The sixth sub-pipe is connected to the eighth nitrogen compressor 411 through the eighth inlet pipe 4111 through 803, and the eighth nitrogen compressor 411 is a medium-pressure nitrogen compressor.

In addition, the connection relationship between the first main pipe 70 and the second main pipe 80 is as follows.

The fifth sub-pipe 802 is connected to the second sub-pipe 702 through the first communication pipe 804, the sixth sub-pipe 803 is connected to the third sub-pipe 703 through the second communication pipe 805; the fourth sub-pipe 801 is sent through the fourth low-pressure nitrogen delivery pipe 103 is connected with the first air separation unit 10.

In this embodiment, a purging device is also installed for purging each sub-pipe and detecting the purity of nitrogen in each sub-pipe. FIG. 3 is a schematic structural diagram of a purging device S, which includes a purging pipe 721 , a purging valve 722 and an analysis sampling valve 723 installed on the purging pipe 721 . In this embodiment, on the first main pipe 70, near the blind plate 712, both ends of the second node valve 62, both ends of the first node valve 61, and the vicinity of the blind plate 711 are respectively provided with a purge pipe S, On the second main pipe 80 , near the blind plate 812 , both ends of the third node valve 63 , both ends of the fourth node valve 64 and near the blind plate 811 are respectively provided with a purge pipe S.

This embodiment also provides a control method based on the above-mentioned low-pressure nitrogen main pipe system.

First, close the node valves one by one, and open the purge valve of the purge device on the corresponding sub-pipe to purge the sub-pipes, and then check the purity of low-pressure nitrogen through the sampling and analysis valve. The node valve is opened after the nitrogen purity has passed the inspection. For example, at first the first node valve 61 is closed, and the purging device S arranged on the first sub-pipe 701 and the second sub-pipe 702 is respectively opened to purge and detect the purity of the low-pressure nitrogen. The first node valve 61 is opened after the nitrogen purity in the pipe is tested as qualified.

After all the sub-pipes pass the inspection, open all the node valves, and the first main pipe 70 and the second main pipe 80 are connected through the sub-pipes and connecting pipes, realizing that all nitrogen compressors are common, and can be used for any combination and call.

For the low-pressure nitrogen main pipe system of the present invention, the total production capacity of low-pressure nitrogen ΣQ _D can be set according to the user demand ΣQ _X , so that the two can reach a balance.

Specifically, user demand ΣQ _X = total pressure delivery volume of medium-pressure nitrogen ΣQ _Z + total pressure delivery volume of high-pressure nitrogen ΣQ _G .

The total pressure delivery volume of medium-pressure nitrogen ΣQ _Z = the pressure delivery volume Q 407 of the first nitrogen compressor ₄₀₇ + the pressure delivery volume Q 409 of the second nitrogen compressor ₄₀₉ + the pressure delivery volume Q _{410 of the fifth nitrogen compressor 410} + the seventh nitrogen The pressure delivery volume Q 408 of the press ₄₀₈ + the pressure delivery volume Q _{411 of the eighth nitrogen compressor 411} .

The total pressure delivery volume of high-pressure nitrogen ΣQ _G = the pressure delivery volume Q 507 of the third nitrogen compressor ₅₀₇ + the pressure delivery volume Q 508 of the fourth nitrogen compressor ₅₀₈ + the pressure delivery volume Q _{509 of the sixth nitrogen compressor 509} .

The total production capacity of low-pressure nitrogen ΣQ _D =the low-pressure nitrogen delivery amount Q ₁₀₁ of the first air separation unit 10 + the low-pressure nitrogen delivery amount Q ₂₀₁ of the second air separation unit 20 + the low-pressure nitrogen delivery amount Q ₃₀₁ of the third air separation unit 10 .

Thus, ΣQ _X =ΣQ _D is realized.

The following describes the combined use of multiple air separation and nitrogen compressors.

When only one air separation unit needs to be operated, run the nitrogen compressor connected to the same sub-pipe; for example, if the first air separation 10 is running, the first nitrogen compressor located on the same sub-pipe 701 as the first air separation 10 is preferentially run machine 407, so when the first air separation machine 10 is tripped or unloaded, the first nitrogen compressor 407 is tripped.

When multiple air separation units are running at the same time, the nitrogen compressor connected to the same sub-pipe as the air separation unit will be run first, and then other nitrogen compressors will be selected to run.

When one of the air separation units is tripped, or the air separation unit is unloaded, the air distribution jacket nitrogen compressor will be unloaded but not tripped, and the other nitrogen compressors will not be unloaded or tripped. It is manually controlled to decide which one to stop One or several nitrogen compressors;

Any nitrogen compressor, when its own failure trips and interlocks, it will jump directly, and other nitrogen compressors of the same volume will be manually opened; if its suction pressure is low, it will first give an alarm and then unload, but it will not jump , after the main pipe pressure is restored by manual regulation, it will continue to operate normally; if its suction pressure is too low, it will jump off the car directly.

The following describes how to close the node valve according to the need to realize the communication or isolation of each air separation low-pressure nitrogen.

Specifically, when the first node valve 61 is closed, the first sub-pipe 701 is isolated from the second sub-pipe 702 , and the first air separator 10 is only connected to the first nitrogen compressor 407 through the first low-pressure nitrogen delivery pipeline 101 .

When the third node valve 63 is closed, the fourth sub-pipe 801 is isolated from the fifth sub-pipe 802 , and the first air separator 10 is not connected to any nitrogen compressor through the fourth low-pressure nitrogen delivery pipeline 103 .

When the second node valve 62 is closed, the second sub-pipe 702 is isolated from the third sub-pipe 703, but through the first communication pipe 804, the second communication pipe 805 and the second main pipe 80, the second sub-pipe 702 is connected to the third sub-pipe 703. Tube 703 is still connected.

Similarly, when the fourth node valve 64 is closed, the fifth sub-pipe 802 is isolated from the sixth sub-pipe 803, but through the first communication pipe 804, the second communication pipe 805 and the first main pipe 70, the fifth sub-pipe 802 is connected to the sixth sub-pipe 802. The six sub-pipes 803 are still connected.

When both the first node valve 61 and the third node valve 63 are closed, the first air separator 10 is isolated from the header system.

When both the second node valve 62 and the fourth node valve 64 are closed, the third air separator 30 is isolated from the header system.

When all node valves are closed, each air separation unit can only be used in conjunction with the nitrogen compressor connected to the same sub-pipe, and cannot call each other.

Using the low-pressure nitrogen main pipe system and control method of the present invention can ensure the common use of any nitrogen compressor on the main pipe during any air separation operation, can meet the nitrogen demand of customers, realize the mutual call of air separation, and can also realize the The relative isolation of points and nitrogen compressors. In addition, even when the air separation unit suddenly jumps, it can perform rapid control and stable operation, achieving good control.

The scope of protection of the present invention is not limited to the content of the above-mentioned embodiments, and various modifications can be made without departing from the claims.

Claims (10)

1. a kind of low-pressure nitrogen manifold system, including：

At least three space divisions including first space division, the second space division and the 3rd space division, it produces low-pressure nitrogen；First main pipe, institute State the first main pipe and comprise at least the first son pipe connected in succession, the second son pipe and the 3rd son pipe, in the described first son pipe and institute State and be provided with first node valve between the second sub- pipe, section point is provided between the described second son pipe and the 3rd sub- pipe Valve, the first son pipe are sent out pipeline by the first low pressure nitrogen and are connected with first space division, and the second son pipe passes through second Low pressure nitrogen is sent out pipeline and is connected with second space division, and the 3rd son pipe sends out pipeline and the described 3rd by the 3rd low pressure nitrogen Space division is connected, and the first son pipe, the second son pipe and the 3rd sub- pipe are connected by inlet tube with nitrogen compressor respectively；

Characterized in that, the low-pressure nitrogen manifold system also includes：

Second main pipe, second main pipe comprise at least the 4th son manage, the 5th son pipe and the 6th son pipe, it is described 4th son pipe with The 3rd node valve is provided between the 5th sub- pipe, fourth node is provided between the 5th son pipe and the 6th sub- pipe Valve, it is described 5th son pipe by be connected with the described second sub- pipe the first communicating pipe, it is described 6th son manage pass through the second communicating pipe and The 3rd sub- pipe connection, the 4th son pipe are sent out pipeline by the 4th low pressure nitrogen and are connected with first space division, and described the Five son pipes and the 6th sub- pipe are connected by inlet tube with nitrogen compressor respectively.

2. low-pressure nitrogen manifold system as claimed in claim 1, it is characterised in that also include being arranged at the more of each sub- pipe both ends Whether individual blow device is qualified to detect the low pressure nitrogen purity in each sub- pipe for being purged to each sub- pipe.

3. low-pressure nitrogen manifold system as claimed in claim 2, it is characterised in that the blow device includes scavenging conduit, if Put blow down valve and analytical sampling valve on scavenging conduit.

4. low-pressure nitrogen manifold system as claimed in claim 1, it is characterised in that the first son pipe, the 3rd son pipe, the 4th One end for being not provided with node valve of son pipe and/or the 6th sub- pipe is provided with blind plate.

5. low-pressure nitrogen manifold system as claimed in claim 1, it is characterised in that the first son pipe, the 3rd son pipe, the 4th Sub- pipe and/or the 6th sub- pipe are provided at both ends with node valve.

6. a kind of control method of the low-pressure nitrogen manifold system based on as any one of claim 2~5, its feature exist In the control method includes：

The first node valve, section point valve, the 3rd node valve and fourth node valve are closed, start blow device to each Sub- pipe is purged to detect the low pressure nitrogen purity in each sub- pipe；

For any node valve in the first node valve, section point valve, the 3rd node valve and fourth node valve, work as inspection Survey and the node valve is opened when low pressure nitrogen purity is eligible in the sub- pipe of the node valve both sides；It is single according to predetermined aggregated capacity Solely operation separate unit space division and more space divisions of nitrogen compressor or combined running and nitrogen compressor；

Corresponding node valve is closed as needed, realizes connection or the cut-off of each space division low pressure nitrogen.

7. the control method of low-pressure nitrogen manifold system as claimed in claim 6, it is characterised in that the isolated operation separate unit More space divisions of space division and nitrogen compressor or combined running and nitrogen compressor include：

When only needing to run separate unit space division, then operation is connected to the nitrogen compressor on same sub- pipe with the space division；

It is preferential to run the nitrogen compressor being connected to the space division run on same sub- pipe when more space divisions of combined running, it is secondary and Selection operation is connected to the nitrogen compressor on other sub- pipes.

8. the control method of low-pressure nitrogen manifold system as claimed in claim 6, it is characterised in that also include：

When wherein space division jumps car, or the unloading of this space division, then a pair nitrogen compressor supporting with this space division is unloaded but not Car is jumped, car is not also jumped without unloading to other nitrogen compressors, and one or more nitrogen compressor is stopped according to user instruction.

9. the control method of low-pressure nitrogen manifold system as claimed in claim 6, it is characterised in that also include：

For any nitrogen compressor, when itself failure jumps car interlocking action, then it directly jumps car, and starts it according to user instruction Its equivalent nitrogen compressor.

10. the control method of low-pressure nitrogen manifold system as claimed in claim 6, it is characterised in that also include：

For any nitrogen compressor, when its suction pressure is low, then unloaded after sending alarm, but do not jump car, after main pipe recovers pressure Continue to run well；During the minimum of the suction pressure when the nitrogen compressor suction pressure sends alarm less than nitrogen compressor, then directly Connect jump car.