Liquid ammonia unloading device

Abstract

The utility model discloses a liquid ammonia unloading device which comprises a liquid ammonia tank car, a liquid ammonia spherical tank, an unloading crane pipe, an ammonia gas compressor system and a connecting pipe network which are sequentially communicated, and further comprises a medium-pressure nitrogen pipe network and a nitrogen pipeline, and the medium-pressure nitrogen pipe network is connected into the connecting pipe network of an outlet of the ammonia gas compressor system and the unloading crane pipe through the nitrogen pipeline. And a control valve group and a pressure gauge are arranged on the nitrogen pipeline. According to the utility model, a proper positive pressure difference is ensured to exist between the liquid ammonia tank car and the liquid ammonia spherical tank in a mode of combining the pressure of the liquid ammonia tank car and the nitrogen pressure supplement from the medium-pressure nitrogen, and the liquid ammonia is pressed into the liquid ammonia spherical tank from the liquid ammonia tank car through the pressure difference to be stored. Non-toxic inert gas-nitrogen is used for providing unloading operation conveying pressure, unloading operation is guaranteed to be carried out smoothly, frequent leakage of the ammonia gas compressor is avoided fundamentally, and therefore safety and environment management and control in a major dangerous source area are greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of truck unloading devices, and particularly relates to a liquid ammonia truck unloading device. Background Art

[0002] In the technical field of nitric acid production, the existing method for unloading raw material liquid ammonia from tank trucks is to combine the self-pressure of the liquid ammonia tank truck and the pressurization of the ammonia gas compressor to ensure a positive pressure difference between the liquid ammonia tank truck and the target liquid ammonia spherical tank, and press the liquid ammonia from the liquid ammonia tank truck into the target liquid ammonia spherical tank for storage through the pressure difference between the two storage pressure vessels.

[0003] As the main equipment for providing conveying pressure during the unloading operation - the ammonia gas compressor, due to reasons such as damaged or aged seals, improper operation by personnel, long-term overloading operation, and inadequate maintenance, will cause situations such as combustion and explosion in the first-level major hazard source area, leakage of toxic and harmful ammonia gas, and frequent alarms of toxic gases, endangering the safety of operating personnel and equipment. Content of the Utility Model

[0004] Purpose of the Utility Model: The purpose of the utility model is to provide a safe and stable liquid ammonia truck unloading device.

[0005] Technical Solution: A liquid ammonia truck unloading device of the utility model includes a liquid ammonia tank truck, a liquid ammonia spherical tank, a truck unloading crane pipe, an ammonia gas compressor system, and a connecting pipeline network that are connected in sequence. It also includes a medium-pressure nitrogen gas pipeline network and a nitrogen gas pipeline. The medium-pressure nitrogen gas pipeline network is connected to the connecting pipeline network between the outlet of the ammonia gas compressor system and the truck unloading crane pipe through the nitrogen gas pipeline. A first control valve group and a first pressure gauge are provided on the nitrogen gas pipeline. [[ID=2C]]

[0006] Further, the connecting pipeline network includes a spherical tank liquid ammonia feed pipeline connecting the liquid phase pipeline of the liquid ammonia spherical tank and the truck unloading crane pipe, a gas phase balance pipeline connecting the liquid ammonia spherical tank and the inlet of the ammonia gas compressor system, and a pipeline connecting the outlet of the ammonia gas compressor system and the gas phase pipeline of the truck unloading crane pipe.

[0007] Further, the ammonia gas compressor system includes an ammonia gas compressor, an ammonia gas compressor inlet pipeline, and an ammonia gas compressor outlet pipeline. The ammonia gas compressor inlet pipeline is connected to the gas phase balance pipeline. The ammonia gas compressor outlet pipeline is connected to the gas phase pipeline of the truck unloading crane pipe. An ammonia gas compressor inlet cut-off valve is provided on the ammonia gas compressor inlet pipeline. A second control valve group and a second pressure gauge are provided on the ammonia gas compressor outlet pipeline.

[0008] Further, a quick unloading cut-off valve group is provided on the spherical tank liquid ammonia feed pipeline. A DCS cut-off valve and an SIS cut-off valve are provided at the bottom of the liquid ammonia spherical tank.

[0009] Further, a check valve is provided on the outlet pipeline of the ammonia compressor, and the nitrogen pipeline is connected between the check valve and the gas-phase pipe of the unloading crane pipe.

[0010] Further, the medium-pressure nitrogen pipeline network is connected to the medium-pressure nitrogen spherical tank.

[0011] Further, a number of manual valves are provided on the connecting pipeline network.

[0012] Technical principle: By combining the self-pressure of the liquid ammonia tank truck with the nitrogen gas pressure supplement from the medium-pressure nitrogen gas, an appropriate positive pressure difference is ensured between the liquid ammonia tank truck and the liquid ammonia spherical tank, and the liquid ammonia is "pressed" from the liquid ammonia tank truck into the liquid ammonia spherical tank for storage through the pressure difference.

[0013] Beneficial effects: Compared with the prior art, the utility model has the following advantages: (1) The utility model uses a non-toxic inert gas - nitrogen gas to provide the conveying pressure for the unloading operation, ensuring the smooth progress of the unloading operation, fundamentally avoiding the frequent leakage of the ammonia compressor, and thus greatly improving the safety and environmental control in the major hazard source area. (2) The whole of the utility model adopts a multiple control valve group in cooperation with a pressure gauge, which is convenient for the operators to quickly and conveniently master the operation situation and improves the safety of on-site unloading. Brief description of the drawings

[0014] Figure 1 is the overall structural schematic diagram of the utility model. Specific implementation manners

[0015] The technical solution of the utility model will be further described below with reference to the drawings.

[0016] As shown in the figure, a liquid ammonia unloading device provided by the utility model includes a liquid ammonia tank truck 1, a liquid ammonia spherical tank 2, an unloading crane pipe 3, an ammonia compressor system and a connecting pipeline network that are connected in sequence, and also includes a medium-pressure nitrogen pipeline network 4 and a nitrogen pipeline 5. The medium-pressure nitrogen pipeline network 4 is connected into the connecting pipeline network between the outlet of the ammonia compressor system and the unloading crane pipe 3 through the nitrogen pipeline 5. A first control valve group and a first pressure gauge are provided on the nitrogen pipeline 5, and the medium-pressure nitrogen pipeline network 3 is connected to the medium-pressure nitrogen spherical tank. A number of manual valves are provided on the connecting pipeline network. The utility model combines the self-pressure of the liquid ammonia tank truck 1 with the nitrogen gas pressure supplement of 2.5 MPa (≥ the highest working pressure of the liquid ammonia spherical tank) from the medium-pressure nitrogen spherical tank in the factory to ensure an appropriate positive pressure difference between the liquid ammonia tank truck 1 and the liquid ammonia spherical tank 2, and the liquid ammonia is "pressed" from the liquid ammonia tank truck 1 into the liquid ammonia spherical tank 2 for storage through the pressure difference.

[0017] In some embodiments, the connecting pipe network includes a spherical tank liquid ammonia feed pipeline 6 connecting the liquid ammonia spherical tank 2 and the liquid phase pipeline of the unloading crane pipe 3, a gas phase balance pipeline 7 connecting the liquid ammonia spherical tank 2 and the inlet of the ammonia compressor system, and a pipeline connecting the outlet of the ammonia compressor system and the gas phase pipeline of the unloading crane pipe 3. A quick cut-off valve group 12 for unloading is provided on the spherical tank liquid ammonia feed pipeline 6, and a DCS cut-off valve 13 and an SIS cut-off valve 14 are provided at the bottom of the liquid ammonia spherical tank 2.

[0018] In some embodiments, the ammonia compressor system includes an ammonia compressor 8, an ammonia compressor inlet pipeline 9, and an ammonia compressor outlet pipeline 10. The ammonia compressor inlet pipeline 9 is connected to the gas phase balance pipeline 7, and the ammonia compressor outlet pipeline 10 is connected to the gas phase pipeline of the unloading crane pipe 3. An ammonia compressor inlet cut-off valve 11 is provided on the ammonia compressor inlet pipeline 9. A second control valve group and a second pressure gauge are provided on the ammonia compressor outlet pipeline 10. A check valve is provided on the ammonia compressor outlet pipeline 10. The nitrogen pipeline 5 is connected between the check valve and the gas phase pipe of the unloading crane pipe after accessing the check valve.

[0019] Workflow: In the use of the present utility model, medium-pressure nitrogen is used for liquid ammonia unloading. The medium-pressure nitrogen pipeline in the factory is introduced into the nitrogen pipeline -50 in the liquid ammonia tank area, and its pressure is adjusted and controlled not to exceed the maximum working pressure of the liquid ammonia spherical tank 2 through a combination of valves and pressure gauges, thereby forming an effective protection for the liquid ammonia spherical tank 2 and the associated ammonia pipelines; the nitrogen pipeline -50 in the liquid ammonia tank area is introduced between the check valve of the ammonia compressor outlet pipeline -50 and the gas phase pipe of the unloading crane pipe, and the positive pressure difference between the liquid ammonia tank truck 1 and the liquid ammonia spherical tank 2 is stabilized through a combination of valves and pressure gauges, thereby realizing balanced unloading operation. A small part of the supplemented medium-pressure nitrogen enters the liquid ammonia spherical tank 2 along with the liquid ammonia and is discharged into the atmosphere during the regular inspection and replacement of the pressure vessel; most of the supplemented medium-pressure nitrogen is stored in the liquid ammonia tank truck 1. When the liquid ammonia tank truck 1 is loaded, the nitrogen and ammonia in the liquid ammonia tank truck 1 are discharged into the synthetic ammonia storage tank for recovery through the exhaust crane pipe, and the nitrogen is discharged into the flare system through the pressure control valve of the synthetic ammonia storage tank.

[0020] During the liquid ammonia unloading operation, first connect the gas and liquid phase pipelines between the liquid ammonia tank truck 1 and the unloading crane pipe 3, and open the quick cut-off valve group for unloading on the liquid ammonia feed pipeline 6 from the liquid phase pipeline of the unloading crane pipe 3 to the liquid ammonia spherical tank 2, the DCS cut-off valve, the SYS cut-off valve, and all relevant hand valves to make the liquid ammonia pipeline unobstructed before and after. Then, open the outlet valve of the liquid ammonia tank truck 1 and the ball valve of the liquid phase pipeline of the liquid ammonia unloading crane pipe 3, and adjust the DN50 stop valve according to the local pressure gauge on the DN50 pipeline at the liquid phase outlet of the unloading crane pipe 3 to control the value of the local pressure gauge to be 0.3 - 0.5 MPa higher than the actual pressure of the liquid ammonia spherical tank 2, and use the positive pressure difference between the liquid ammonia tank truck 1 itself and the liquid ammonia spherical tank 2 to transport the liquid ammonia in the liquid ammonia tank truck 1 into the liquid ammonia spherical tank 2.

[0021] When the positive pressure difference between the liquid ammonia tank truck 1 and the liquid ammonia spherical tank 2 is lower than 0.3 MPa, open the valve of the nitrogen pipeline -50 in the liquid ammonia tank area to keep the nitrogen pipeline in the tank area unobstructed. Adjust the medium-pressure nitrogen DN50 valve from the pipe network to control the local pressure gauge within the range of the maximum working pressure of 1.65 MPa of the liquid ammonia spherical tank 2. By adjusting the nitrogen DN25 pressure supplement valve in front of the gas-phase loading arm and referring to the local pressure gauge behind the valve, control the pressure-supplement nitrogen to be 0.3 - 0.5 MPa higher than the actual pressure of the spherical tank until the liquid ammonia tank truck continues to unload the material.

Claims

1. A liquid ammonia unloading device, comprising a liquid ammonia tank truck (1), a liquid ammonia spherical tank (2), a loading and unloading crane pipe (3), an ammonia compressor system and a connecting pipe network that are connected in sequence, characterized in that, It also includes a medium-pressure nitrogen pipeline network (4) and a nitrogen pipeline (5). The medium-pressure nitrogen pipeline network (4) is connected to the pipeline network connecting the outlet of the ammonia compressor system and the loading / unloading crane pipe (3) through the nitrogen pipeline (5). A first control valve group and a first pressure gauge are provided on the nitrogen pipeline (5).

2. The liquid ammonia unloading device according to claim 1, characterized in that, The connecting pipeline network includes a spherical tank liquid ammonia feeding pipeline (6) that connects the liquid ammonia spherical tank (2) and the liquid phase pipeline of the loading / unloading crane pipe (3), a gas phase balance pipeline (7) that connects the liquid ammonia spherical tank (2) to the inlet of the ammonia compressor system, and a pipeline that connects the outlet of the ammonia compressor system to the gas phase pipeline of the loading / unloading crane pipe (3).

3. The liquid ammonia unloading device according to claim 2, characterized in that, The ammonia compressor system includes an ammonia compressor (8), an ammonia compressor inlet pipeline (9), and an ammonia compressor outlet pipeline (10). The ammonia compressor inlet pipeline (9) is connected to the gas phase balance pipeline (7), the ammonia compressor outlet pipeline (10) is connected to the gas phase pipeline of the loading / unloading crane pipe (3), an ammonia compressor inlet cut-off valve (11) is provided on the ammonia compressor inlet pipeline (9), and a second control valve group and a second pressure gauge are provided on the ammonia compressor outlet pipeline (10).

4. The liquid ammonia unloading device according to claim 2, wherein, A loading / unloading quick cut-off valve group (12) is provided on the spherical tank liquid ammonia feeding pipeline (6), and a DCS cut-off valve (13) and an SIS cut-off valve (14) are provided at the bottom of the liquid ammonia spherical tank (2).

5. The liquid ammonia unloading device according to claim 3, wherein, A check valve is provided on the ammonia compressor outlet pipeline (10), and the nitrogen pipeline (5) is connected between the check valve and the gas phase pipe of the loading / unloading crane pipe.

6. The liquid ammonia unloading device according to claim 1, wherein The medium-pressure nitrogen pipeline network (4) is connected to a medium-pressure nitrogen spherical tank.

7. The liquid ammonia unloading device according to claim 1, characterized in that, Several manual valves are provided on the connecting pipeline network.

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