Instrument air supplementing device in liquid ammonia tank area during overhaul period

Abstract

The utility model relates to an instrument air supplementing device in a liquid ammonia tank area during overhaul, which comprises an instrument air storage tank, an outer net header pipe, a downstream air supply pipeline, a nitrogen cylinder group and a storage platform, the outer net header pipe and the downstream air supply pipeline are connected with the instrument air storage tank, a pressure gauge and a gas distribution tank are sequentially arranged on the downstream air supply pipeline, and the gas distribution tank is connected with a user side; a first stop valve, a check valve and a gas supplementing channel are sequentially arranged on the outer net header pipe in the gas inlet direction, one end of the gas supplementing channel is connected into the outer net header pipe through a second stop valve, and the other end of the gas supplementing channel is connected with the nitrogen cylinder set. A stop valve, a check valve and a gas supplementing channel are additionally arranged on a boundary area header pipe, so that a nitrogen cylinder group can be connected in time when abnormal conditions occur during the period of years of repair, and instrument air can be supplemented in time as an alternative scheme. By means of the mode, instrument air supply of a small-scale device can be met, the situation that a pneumatic control valve of the liquid ammonia storage tank is automatically opened due to pressure loss is avoided, environmental protection and safety are guaranteed, original pipeline distribution and trend do not need to be changed, and high flexibility is achieved.

Description

Technical Field

[0001] This utility model relates to the field of chemical production equipment, and in particular to an instrument air replenishment device for liquid ammonia tank areas during major overhauls. Background Technology

[0002] Liquid ammonia storage tanks are critical storage devices in chemical, refrigeration, and other fields, used to maintain production continuity. Their safe operation relies on the precise control of pneumatic regulating valves by the instrument air system. Under normal operating conditions, instrument air is supplied by an air compressor or air separation unit. However, during annual overhauls, the air separation unit needs to be shut down for maintenance. Companies typically switch to a backup oil-free screw compressor as a temporary air source. Simultaneously, according to design requirements, a certain amount of liquid ammonia still needs to be stored during this period for start-up use. However, overhaul cycles are long, maintenance items are complex, and the temporary air source is prone to sudden pressure loss due to equipment aging, load fluctuations, and other issues, leading to a sharp drop in instrument air pressure.

[0003] In existing technologies, using a backup oil-free screw compressor as a temporary gas source has significant drawbacks: First, during annual maintenance, the temporary gas source is typically located far from the gas source point due to the need to supply the entire plant. Long-distance transport during maintenance may result in insufficient gas supply stability, making it difficult to meet the long-term demands of major overhauls. Second, traditional gas storage tanks have limited capacity and short buffer times, failing to cover the emergency repair cycle in the event of sudden pressure loss. Third, in the event of sudden pressure loss, the pneumatic regulating valve of the liquid ammonia storage tank automatically switches to the open state based on a "fail-safe" design principle to prevent overpressure explosion. However, this action can trigger liquid ammonia leakage, causing air pollution and safety risks. Utility Model Content

[0004] To address the problem that using a standby oil-free screw compressor as a temporary air source during overhauls in existing technologies can easily lead to sudden loss of instrument air pressure and ammonia leakage, this utility model provides an instrument air replenishment device for liquid ammonia tank areas during overhauls. The device includes an instrument air storage tank and an external main pipe and a downstream gas supply pipeline connected to it. A pressure gauge and a gas distribution tank are sequentially installed on the downstream gas supply pipeline. The gas distribution tank is connected to the user end. The device also includes a nitrogen cylinder group and a storage platform for placing the nitrogen cylinder group.

[0005] The external main pipe is provided with a first shut-off valve, a check valve and a gas replenishment channel in sequence along the gas inlet direction. One end of the gas replenishment channel is connected to the external main pipe through a second shut-off valve, and the other end of the gas replenishment channel is connected to the nitrogen cylinder group.

[0006] Furthermore, the nitrogen cylinder group consists of several nitrogen cylinders.

[0007] Furthermore, the gas replenishment channel is a pressure-resistant hose, and a pressure reducing valve is provided at the connection between the nitrogen cylinder group and the gas replenishment channel.

[0008] Furthermore, a safety valve is externally connected to the instrument air storage tank.

[0009] Furthermore, the user terminal is equipped with an oxygen detector.

[0010] Compared with the prior art, this utility model has the following beneficial effects:

[0011] By adding shut-off valves, check valves, and air replenishment channels to the main pipeline in the boundary area, nitrogen cylinder groups can be connected promptly during annual maintenance in case of abnormalities, serving as an alternative to replenish instrument air in a timely manner. This method not only meets the instrument air supply needs of small-scale units and prevents the pneumatic regulating valve of the liquid ammonia storage tank from automatically opening due to pressure loss, ensuring environmental safety, but also eliminates the need to change the pipeline distribution and routing of the external main pipeline. The manual external air replenishment channel provides convenient operation and high flexibility. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0013] In the diagram: 1. Nitrogen cylinder group; 2. Pressure reducing valve; 3. Gas supply channel; 4. Check valve; 5. First shut-off valve; 6. Second shut-off valve; 7. Instrument air storage tank; 8. External main pipe; 9. Downstream gas supply pipeline; 10. Pressure gauge; 11. Gas distribution tank; 12. User end; 13. Storage platform; 14. Safety valve; 15. Oxygen detector. Detailed Implementation

[0014] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0015] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "upper," "lower," "front," "rear," "top," "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or part referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. It should be understood that such data can be interchanged where appropriate for the embodiments of this utility model described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0016] like Figure 1 As shown, a liquid ammonia tank area instrument air replenishment device during overhaul includes an instrument air storage tank 7 and an external network main pipe 8 and a downstream air supply pipe 9 connected thereto. A pressure gauge 10 and a gas distribution tank 11 are sequentially installed on the downstream air supply pipe 9. The gas distribution tank 11 is connected to the user terminal 12. It also includes a nitrogen cylinder group 1 and a storage platform 13 for placing the nitrogen cylinder group 1.

[0017] The external main pipe 8 is provided with a first shut-off valve 5, a check valve 4 and a gas supply channel 3 in sequence along the gas inlet direction. One end of the gas supply channel 3 is connected to the external main pipe 8 through a second shut-off valve 6, and the other end of the gas supply channel 3 is connected to the nitrogen cylinder group 1.

[0018] The method of using this device is as follows:

[0019] During the annual maintenance period, a nitrogen cylinder storage platform 13 is set up in advance, and nitrogen cylinder group 1 is prepared. In the event of an anomaly, if the central control system detects a drop in instrument air pressure, personnel are promptly instructed to close the first shut-off valve 5 (boundary main valve) and connect the supplementary air channel 3 at the air inlet. Nitrogen cylinder group 1 is then connected to the instrument air pipeline to maintain instrument air pressure. Simultaneously, a check valve 4 installed on the external network main pipe 8 prevents instrument air diversion in the event of a pressure drop due to an anomaly, thus assisting in maintaining instrument air pressure.

[0020] By adding shut-off valves, check valves, and air replenishment channels to the main pipeline in the boundary area, nitrogen cylinder groups can be connected promptly during annual maintenance in case of abnormalities, serving as an alternative to replenish instrument air in a timely manner. This method not only meets the instrument air supply needs of small-scale units and avoids the automatic opening of the pneumatic regulating valve of the liquid ammonia storage tank due to pressure loss, ensuring environmental safety, but also eliminates the need to change the pipeline distribution and routing of the external main pipeline. The operation is convenient and highly flexible due to the manual connection of the external air replenishment channel.

[0021] Nitrogen cylinder group 1 is a containerized nitrogen cylinder group, consisting of several nitrogen cylinders. In this embodiment, the specification used is 40L×16 cylinders.

[0022] The nitrogen cylinder group is high-pressure nitrogen with a pressure of 15MPa. Therefore, the gas supply channel 3 is a pressure-resistant hose, and a pressure reducing valve 2 is provided at the connection between the nitrogen cylinder group 1 and the gas supply channel 3 to avoid overpressure. In this embodiment, the pressure-resistant hose is a plastic hose, and the pressure after passing through the pressure reducing valve 2 is set to the instrument air pressure of 0.7MPa.

[0023] For ease of safety monitoring, a safety valve 14 is connected to the instrument air storage tank 7. When the pressure in the instrument air storage tank 7 exceeds 0.8 MPa, the safety valve 14 will open to prevent system overpressure and ensure pipeline safety.

[0024] To avoid the risk of asphyxiation caused by high concentrations of nitrogen and reduced oxygen content when nitrogen cylinders are used as instrument air replenishment at user terminal 12, an oxygen detector 15 is installed at user terminal 12 to monitor the oxygen content in the area and trigger an audible and visual alarm when the oxygen content is below 19.5%.

[0025] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of implementation of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and all such improvements and modifications should be covered within the protection scope of this utility model.

Claims

1. A liquid ammonia tank area instrument air replenishment device during major overhaul, comprising an instrument air storage tank (7) and an external main pipe (8) and a downstream air supply pipe (9) connected thereto, wherein a pressure gauge (10) and a gas distribution tank (11) are sequentially installed on the downstream air supply pipe (9), and the gas distribution tank (11) is connected to a user terminal (12), characterized in that, It also includes a nitrogen cylinder assembly (1) and a storage platform (13) for placing the nitrogen cylinder assembly (1); The external network main pipe (8) is provided with a first shut-off valve (5), a check valve (4) and a gas replenishment channel (3) in sequence along the gas inlet direction. One end of the gas replenishment channel (3) is connected to the external network main pipe (8) through a second shut-off valve (6), and the other end of the gas replenishment channel (3) is connected to the nitrogen cylinder group (1).

2. The instrument air replenishment device for liquid ammonia tank area during overhaul as described in claim 1, characterized in that, The nitrogen cylinder group (1) consists of several nitrogen cylinders.

3. The instrument air replenishment device for liquid ammonia tank area during overhaul according to claim 1, characterized in that, The gas supply channel (3) is a pressure-resistant hose, and a pressure reducing valve (2) is provided at the connection between the nitrogen cylinder group (1) and the gas supply channel (3).

4. The instrument air replenishment device for liquid ammonia tank area during overhaul according to claim 1, characterized in that, A safety valve (14) is connected to the instrument air storage tank (7).

5. The instrument air replenishment device for liquid ammonia tank area during overhaul according to claim 1, characterized in that, The user terminal (12) is equipped with an oxygen detector (15).

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