Air separation device medium pressure nitrogen gas supply system

Abstract

The utility model discloses a kind of medium-pressure nitrogen gas supply system in air separation device, including liquid nitrogen storage tank, water bath type heat exchanger, first medium-pressure nitrogen pump and second medium-pressure nitrogen pump;The liquid nitrogen storage tank is connected with the water bath type heat exchanger through first medium-pressure nitrogen pipeline, the water bath type heat exchanger is connected with medium-pressure nitrogen gas pipe network through gas nitrogen delivery pipeline;The first medium-pressure nitrogen pump is set on the first medium-pressure nitrogen pipeline;Second medium-pressure nitrogen pipeline is connected on the first medium-pressure nitrogen pipeline between the liquid nitrogen storage tank and the first medium-pressure nitrogen pump, and the other end of the second medium-pressure nitrogen pipeline is connected on the first medium-pressure nitrogen pipeline between the first medium-pressure nitrogen pump and water bath type heat exchanger.The advantage is: by adding second medium-pressure nitrogen pump, ensure that medium-pressure nitrogen gas is stably supplied, avoid the pressure fluctuation of medium-pressure nitrogen gas pipe network caused by the frequent start-stop of first medium-pressure nitrogen pump, while reducing equipment failure rate;By interlocking the medium-pressure nitrogen pump with medium-pressure nitrogen gas pipe network, the overpressure risk of medium-pressure nitrogen gas pipe network is avoided.

Description

Technical Field

[0001] This utility model relates to the technical field of flexible adjustment of medium-pressure nitrogen supply capacity in air separation units, and in particular to a medium-pressure nitrogen supply system for air separation units. Background Technology

[0002] In chemical production plants, medium-pressure nitrogen is mainly used for sealing and protection, purging and replacement, and as a carrier gas and reaction gas. During normal production, the nitrogen pressure produced by the air separation unit is constant, but the nitrogen pressure requirements of different production units vary. Therefore, it is necessary to increase the nitrogen pressure according to the actual needs of users. Currently, the main ways to increase nitrogen pressure are compressor boosting or liquid nitrogen pump boosting.

[0003] Currently, the medium-pressure nitrogen system in the air separation unit operates as follows: liquid nitrogen from the liquid nitrogen tank is pressurized by a medium-pressure nitrogen pump, and then vaporized by a water bath vaporizer to supply the plant's medium-pressure nitrogen pipeline network. The medium-pressure nitrogen pump is designed for a pressure of 2.5 MPa and a flow rate of 2560-5120 Nm³. 3 / h; Under normal circumstances, the liquid nitrogen pump is kept pre-cooled, and the interlock automatically starts when the pressure after the pump is low, serving as a backup nitrogen for emergency response; the pipeline pressure can be maintained at 1.3-1.6MPa to meet the usage requirements.

[0004] After the VA (vinyl acetate)-UHMWPE (ultra-high molecular weight polyethylene) system is started up, the daily requirements for medium-pressure nitrogen are: purity ≥99.9%, flow rate 104 Nm³. 3 / h, pressure 1.9-2.3MPa, continuous supply; peak emergency demand: purity ≥99.9%, flow rate 6820Nm³ / h. 3 / h. Since the VA-UHMWPE unit began operation, the pipeline pressure needs to be maintained at 2.0-2.2 MPa, compared to 104 Nm under normal production conditions. 3 The current medium-pressure nitrogen pump model is too large for the continuous usage of / h. During normal production, the nitrogen pump will start and stop continuously. Frequent start and stop will increase the failure rate of the liquid nitrogen pump and make it impossible to guarantee a stable supply of medium-pressure nitrogen. Utility Model Content

[0005] The purpose of this invention is to provide a compressed nitrogen supply system for an air separation unit, thereby solving the aforementioned problems existing in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] A medium-pressure nitrogen supply system for an air separation unit includes a liquid nitrogen storage tank, a water bath heat exchanger, a first medium-pressure nitrogen pump, and a second medium-pressure nitrogen pump. The liquid nitrogen storage tank is connected to the water bath heat exchanger via a first medium-pressure nitrogen pipeline, and the water bath heat exchanger is connected to a medium-pressure nitrogen pipeline network via a gas nitrogen delivery pipeline. The first medium-pressure nitrogen pump is installed on the first medium-pressure nitrogen pipeline. A second medium-pressure nitrogen pipeline is connected to the first medium-pressure nitrogen pipeline between the liquid nitrogen storage tank and the first medium-pressure nitrogen pump, and the other end of the second medium-pressure nitrogen pipeline is connected to the first medium-pressure nitrogen pipeline between the first medium-pressure nitrogen pump and the water bath heat exchanger.

[0008] Preferably, the second medium-pressure nitrogen pump serves as the main gas supply equipment under normal production mode, interlocked with the medium-pressure nitrogen pipeline network, starting at 2.0 MPa and stopping at 2.2 MPa; the first medium-pressure nitrogen pump serves as the backup gas supply equipment under normal production mode, interlocked with the medium-pressure nitrogen pipeline network, starting at 1.95 MPa and stopping at 2.2 MPa; thus meeting normal production needs.

[0009] When the demand for medium-pressure nitrogen is high, the first medium-pressure nitrogen pump serves as the main gas supply equipment to meet emergency response needs.

[0010] Preferably, a first medium-pressure nitrogen pump inlet valve and a first medium-pressure nitrogen pump outlet valve are respectively provided on the first medium-pressure nitrogen pipeline upstream and downstream of the first medium-pressure nitrogen pump; the two ends of the second medium-pressure nitrogen pipeline are respectively connected to the first medium-pressure nitrogen pipeline between the first medium-pressure nitrogen pump inlet valve and the first medium-pressure nitrogen pump, the first medium-pressure nitrogen pump outlet valve and the water bath heat exchanger.

[0011] Preferably, a second medium-pressure nitrogen pump inlet valve and a second medium-pressure nitrogen pump outlet valve are respectively installed on the upstream and downstream second medium-pressure nitrogen pipelines of the second medium-pressure nitrogen pump.

[0012] Preferably, a medium-pressure nitrogen shut-off valve is installed on the nitrogen delivery pipeline.

[0013] The beneficial effects of this utility model are: by adding a second medium-pressure nitrogen pump, a stable supply of medium-pressure nitrogen is ensured, avoiding pressure fluctuations in the medium-pressure nitrogen pipeline caused by frequent start-stop of the first medium-pressure nitrogen pump, and reducing equipment failure rate; by interlocking the medium-pressure nitrogen pump with the medium-pressure nitrogen pipeline, the risk of overpressure in the medium-pressure nitrogen pipeline is avoided. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the medium-pressure nitrogen system in an embodiment of this utility model.

[0015] In the diagram: V101 - Liquid nitrogen storage tank; E1 - Water bath heat exchanger; V1 - Inlet valve of the first medium-pressure nitrogen pump; V2 - Outlet valve of the first medium-pressure nitrogen pump; V3 - Medium-pressure nitrogen shut-off valve; V4 - Inlet valve of the second medium-pressure nitrogen pump; V5 - Outlet valve of the second medium-pressure nitrogen pump; P1 - First medium-pressure nitrogen pump; P2 - Second medium-pressure nitrogen pump. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the scope of the present utility model.

[0017] like Figure 1 As shown, this embodiment provides a medium-pressure nitrogen supply system for an air separation unit, including a liquid nitrogen storage tank V101, a water bath heat exchanger E1, a first medium-pressure nitrogen pump P1, and a second medium-pressure nitrogen pump P2. The liquid nitrogen storage tank V101 is connected to the water bath heat exchanger E1 via a first medium-pressure nitrogen pipeline, and the water bath heat exchanger E1 is connected to a medium-pressure nitrogen pipeline network via a gas nitrogen delivery pipeline. A medium-pressure nitrogen shut-off valve V3 is installed on the gas nitrogen delivery pipeline. The first medium-pressure nitrogen pump P1 is installed on the first medium-pressure nitrogen pipeline. A second medium-pressure nitrogen pipeline is connected to the first medium-pressure nitrogen pipeline between the liquid nitrogen storage tank V101 and the first medium-pressure nitrogen pump P1, and the other end of the second medium-pressure nitrogen pipeline is connected to the first medium-pressure nitrogen pipeline between the first medium-pressure nitrogen pump P1 and the water bath heat exchanger E1.

[0018] In this embodiment, a first medium-pressure nitrogen pump inlet valve V1 and a first medium-pressure nitrogen pump outlet valve V2 are respectively installed on the first medium-pressure nitrogen pipeline upstream and downstream of the first medium-pressure nitrogen pump P1; the two ends of the second medium-pressure nitrogen pipeline are respectively connected to the first medium-pressure nitrogen pipeline between the first medium-pressure nitrogen pump inlet valve V1 and the first medium-pressure nitrogen pump P1, the first medium-pressure nitrogen pump outlet valve V2 and the water bath heat exchanger E1. A second medium-pressure nitrogen pump inlet valve V4 and a second medium-pressure nitrogen pump outlet valve V5 are respectively installed on the second medium-pressure nitrogen pipeline upstream and downstream of the second medium-pressure nitrogen pump P2.

[0019] Liquid nitrogen in liquid nitrogen storage tank V101 enters first medium-pressure nitrogen pump P1 through first medium-pressure nitrogen pump inlet valve V1. After being pressurized by first medium-pressure nitrogen pump, liquid nitrogen enters water bath heat exchanger E1 through first medium-pressure nitrogen pump outlet valve V2. In water bath heat exchanger E1, liquid nitrogen exchanges heat with 1.27MPa steam. After heat exchange, liquid nitrogen vaporizes from liquid to gas and is sent to medium-pressure nitrogen pipeline through medium-pressure nitrogen shut-off valve V3. The inlet end of the second medium-pressure nitrogen pipeline is connected to the first medium-pressure nitrogen pipeline between the inlet valve V1 of the first medium-pressure nitrogen pump and the first medium-pressure nitrogen pump P1. The outlet end of the second medium-pressure nitrogen pipeline is connected to the first medium-pressure nitrogen pipeline between the outlet valve V2 of the first medium-pressure nitrogen pump and the water bath heat exchanger E1. The inlet valve V4 of the second medium-pressure nitrogen pump, the second medium-pressure nitrogen pump P2, and the outlet valve V5 of the second medium-pressure nitrogen pump are installed on the second medium-pressure nitrogen pipeline. The first medium-pressure nitrogen pump P1 and the second medium-pressure nitrogen pump P2 share a water bath heat exchanger E1.

[0020] In this embodiment, the outlet pressure of the second medium-pressure nitrogen pump P2 is 2.2 MPa, and the flow rate is approximately 320 Nm³. 3 The pump, with functions of remote start / stop, interlocked start / stop, and remote load adjustment, serves as the main gas supply equipment under normal production mode. It is interlocked with the medium-pressure nitrogen pipeline network, starting at 2.0 MPa and stopping at 2.2 MPa. The first medium-pressure nitrogen pump, P1, serves as the backup gas supply equipment under normal production mode, interlocked with the medium-pressure nitrogen pipeline network, starting at 1.95 MPa and stopping at 2.2 MPa, thus meeting normal production needs.

[0021] During emergency response, the demand for medium-pressure nitrogen is large, and the first medium-pressure nitrogen pump P1 serves as the main gas supply equipment to meet the needs of emergency response.

[0022] By adopting the above-disclosed technical solution of this utility model, the following beneficial effects are obtained:

[0023] This utility model provides a medium-pressure nitrogen supply system for an air separation unit. By adding a second medium-pressure nitrogen pump, a stable supply of medium-pressure nitrogen is ensured, avoiding pressure fluctuations in the medium-pressure nitrogen pipeline caused by frequent start-stop of the first medium-pressure nitrogen pump, and reducing equipment failure rate. By interlocking the medium-pressure nitrogen pump with the medium-pressure nitrogen pipeline, the risk of overpressure in the medium-pressure nitrogen pipeline is avoided.

[0024] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A medium-pressure nitrogen supply system for an air separation unit, characterized in that: The system includes a liquid nitrogen storage tank, a water bath heat exchanger, a first medium-pressure nitrogen pump, and a second medium-pressure nitrogen pump. The liquid nitrogen storage tank is connected to the water bath heat exchanger via a first medium-pressure nitrogen pipeline, and the water bath heat exchanger is connected to a medium-pressure nitrogen pipeline network via a gaseous nitrogen delivery pipeline. The first medium-pressure nitrogen pump is installed on the first medium-pressure nitrogen pipeline. A second medium-pressure nitrogen pipeline is connected to the first medium-pressure nitrogen pipeline between the liquid nitrogen storage tank and the first medium-pressure nitrogen pump, and the other end of the second medium-pressure nitrogen pipeline is connected to the first medium-pressure nitrogen pipeline between the first medium-pressure nitrogen pump and the water bath heat exchanger.

2. The medium-pressure nitrogen supply system for the air separation unit according to claim 1, characterized in that: The second medium-pressure nitrogen pump serves as the main gas supply equipment under normal production mode, and is interlocked with the medium-pressure nitrogen pipeline network pressure, starting at 2.0MPa and stopping at 2.2MPa; the first medium-pressure nitrogen pump serves as the backup gas supply equipment under normal production mode, and is interlocked with the medium-pressure nitrogen pipeline network pressure, starting at 1.95MPa and stopping at 2.2MPa; thus meeting normal production needs. When the demand for medium-pressure nitrogen is high, the first medium-pressure nitrogen pump serves as the main gas supply equipment to meet emergency response needs.

3. The medium-pressure nitrogen supply system for the air separation unit according to claim 2, characterized in that: The first medium-pressure nitrogen pump upstream and downstream of the first medium-pressure nitrogen pump are respectively provided with a first medium-pressure nitrogen pump inlet valve and a first medium-pressure nitrogen pump outlet valve; the two ends of the second medium-pressure nitrogen pipeline are respectively connected to the first medium-pressure nitrogen pump inlet valve and the first medium-pressure nitrogen pump, as well as the first medium-pressure nitrogen pump outlet valve and the water bath heat exchanger.

4. The medium-pressure nitrogen supply system for the air separation unit according to claim 3, characterized in that: The second medium-pressure nitrogen pump is equipped with an inlet valve and an outlet valve on the upstream and downstream pipelines of the second medium-pressure nitrogen pump, respectively.

5. The medium-pressure nitrogen supply system for the air separation unit according to claim 1, characterized in that: A medium-pressure nitrogen shut-off valve is installed on the nitrogen gas delivery pipeline.

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