A liquid ammonia storage tank pressure balance control device

Abstract

The utility model relates to the technical field of liquid ammonia storage in synthetic ammonia production, and in particular to a pressure balance control device for a liquid ammonia storage tank. The technical problem is as follows: after the liquid ammonia is pressurized and transported to the relay tank by a pump, the pressure balance cannot be maintained because the non-condensable gas will not be released. The technical solution is as follows: a pressure balance control device for a liquid ammonia storage tank, the air separation nitrogen main pipe of the air separation unit is connected to the relay liquid ammonia storage tank through a two-stage pressure reducing device; a first instrument automatic control valve group is provided in the first-stage pressure reducing device, and the concentrated pressure signal after the valve group of the first instrument automatic control valve group is P1, and the first instrument automatic control valve group automatically adjusts the pressure after the valve through P1; a second-stage pressure reducing device is connected in series after the first-stage pressure reducing device; a second instrument automatic control valve group is provided in the second-stage pressure reducing device, and the concentrated pressure signal after the valve group of the second instrument automatic control valve group is P2, and the second instrument automatic control valve group automatically adjusts the pressure after the valve through P2.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid ammonia storage in synthetic ammonia production, in particular to a liquid ammonia storage tank pressure balance control device. Background Art

[0002] As an important basic chemical raw material, ammonia is usually stored in liquid ammonia storage tanks in liquid form by pressurization at room temperature for easy storage during the production process.

[0003] In the synthetic ammonia production process, the pressure difference between the production unit and the liquid ammonia storage tank can be used to discharge the liquid ammonia from the synthetic ammonia unit cold delivery and ammonia separation to the finished liquid ammonia storage tank through the pressure reducing device, and then the finished liquid ammonia is sent to the liquid ammonia relay tank through the pressure pump, and then the liquid ammonia is sent to the subsequent production process or sold to the outside through the liquid ammonia relay tank. In the above process, the liquid ammonia relay tank plays a connecting role. It is necessary to control the appropriate liquid ammonia inlet and outlet pressure difference between the liquid ammonia relay tank and the previous and next processes to achieve the smooth transportation of liquid ammonia, that is: when storing liquid ammonia, the pressure of the liquid ammonia storage tank should be reduced; when sending liquid ammonia to the outside, the pressure of the liquid ammonia storage tank should be increased.

[0004] The current problem with pressure balance control in liquid ammonia storage tanks is that, in the process of reducing pressure and discharging the produced liquid ammonia into the liquid ammonia storage tank, most of the non-condensable gases (such as hydrogen, nitrogen, methane, etc.) dissolved therein will be released due to the reduced pressure, causing the pressure of the ammonia storage tank to increase; after the liquid ammonia is pressurized and transported to the relay tank by a pump, the non-condensable gases will not be released, and the pressure balance cannot be maintained, affecting the operating stability and reliability of the ammonia storage section. Utility Model Content

[0005] The utility model provides a liquid ammonia storage tank pressure balance control device, which solves the problem in the prior art that after liquid ammonia is pressurized and transported to a relay tank by a pump, no non-condensable gas is released, and pressure balance cannot be maintained, thus affecting the operating stability and reliability of the ammonia storage section.

[0006] The technical solution of the utility model is as follows:

[0007] A liquid ammonia storage tank pressure balance control device, an air separation nitrogen main pipe is connected to a relay liquid ammonia storage tank through a pressure reducing device.

[0008] As a further technical solution, the air separation nitrogen main pipe of the air separation unit is connected to the relay liquid ammonia storage tank through a secondary pressure reducing device.

[0009] As a further technical solution, the air separation nitrogen main pipe of the air separation unit reduces the nitrogen pressure through a first-stage pressure reducing device.

[0010] As a further technical solution, a first instrument automatic control valve group is provided in the first-stage pressure reducing device, and the concentrated pressure signal after the valve group of the first instrument automatic control valve group is P1, and the first instrument automatic control valve group automatically adjusts the pressure after the valve through P1.

[0011] As a further technical solution, the first instrument automatic control valve group includes an automatic regulating valve and a bypass valve. Root valves are arranged before and after the automatic regulating valve of the first instrument automatic control valve group. A vent valve is arranged between the automatic regulating valve and the root valves before and after the automatic regulating valve. The pipeline of the vent valve is connected to an external ammonia recovery device.

[0012] As a further technical solution, the vent valve is a double valve.

[0013] As a further technical solution, a second-stage pressure reducing device is connected in series after the first-stage pressure reducing device, and the second-stage pressure reducing device is connected to a relay liquid ammonia storage tank.

[0014] As a further technical solution, the secondary pressure reducing device is provided with a second instrument automatic control valve group, the relay liquid ammonia storage tank concentrated pressure signal is P2, and the second instrument automatic control valve group automatically adjusts the pressure after the valve through P2;

[0015] The second instrument automatic control valve group includes an automatic regulating valve, root valves before and after the automatic regulating valve, and a bypass valve.

[0016] As a further technical solution, the second-stage pressure reducing device is provided with a matching root valve, a shortcut valve and a vent valve.

[0017] As a further technical solution, the relay liquid ammonia storage tank body has a vent valve group, the relay liquid ammonia storage tank body is provided with a pressure reducing device, and the pressure reducing device is provided with a third instrument automatic control valve group;

[0018] The third instrument automatic control valve group includes an automatic regulating valve, root valves before and after the automatic regulating valve, and a bypass valve. The third instrument automatic control valve group automatically adjusts the valve opening or opening degree through P2;

[0019] The pressure reducing device of the relay liquid ammonia storage tank is provided with a matching root valve, a shortcut valve and a vent valve.

[0020] The beneficial effects of the utility model are:

[0021] 1. Use medium-pressure nitrogen from air separation as the pressure supplement gas source for the ammonia storage tank to compensate the pressure of the relay liquid ammonia storage tank and maintain pressure balance;

[0022] Because nitrogen is an inert gas and the medium-pressure nitrogen provided by the air separation unit has been fully dehumidified and deoiled, it will not affect the safety of the ammonia storage tank and the quality of the liquid ammonia product.

[0023] 2. Set up a secondary nitrogen pressure-replenishing device and ensure operational stability through automatic control valves to achieve controllable pressure difference between the liquid ammonia relay tank and other storage tanks or subsequent process materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0025] Figure 1 This is a schematic diagram of the pipeline structure in the utility model;

[0026] In the figure: 1. The first instrument automatic control valve group; 2. The second instrument automatic control valve group; 3. The third instrument automatic control valve group. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] like Figure 1 As shown, a liquid ammonia storage tank pressure balance control device, the air separation medium-pressure nitrogen main pipe is connected to the relay liquid ammonia storage tank through a pressure reducing device.

[0029] The air separation medium-pressure nitrogen main pipe of the air separation unit is connected to the relay liquid ammonia storage tank through a secondary pressure reducing device.

[0030] The air separation nitrogen main pipe of the air separation unit reduces the nitrogen pressure through the first stage pressure reducing device.

[0031] A second stage pressure reducing device is connected in series after the first stage pressure reducing device, and the second stage pressure reducing device is connected to a relay liquid ammonia storage tank.

[0032] Medium-pressure nitrogen from the air separation unit is used to compensate the pressure of the relay liquid ammonia storage tank. At room temperature, the pressure of the liquid ammonia storage tank is generally maintained at 1.6-2.0MPa, and the pressure of the air separation nitrogen pipeline is generally around 6.5MPa. In order to ensure that the liquid ammonia in the relay tank maintains a certain pressure difference with the subsequent process when it is delivered, medium-pressure nitrogen is used for pressure compensation of the ammonia relay tank through secondary pressure reduction, and dynamic pressure compensation is achieved for the relay liquid ammonia storage tank to maintain pressure balance.

[0033] The first-stage pressure reducing device is provided with a first instrument automatic control valve group 1. The concentrated pressure signal after the valve group of the first instrument automatic control valve group 1 is P1. The first instrument automatic control valve group 1 automatically adjusts the pressure after the valve through P1. Generally, the pressure before the valve group is about 6.5MPa, and the control range of the pressure P1 after the valve group is about 2.4MPa, which can be adjusted according to specific circumstances.

[0034] The first instrument automatic control valve group 1 includes an automatic regulating valve and a bypass valve. Root valves are arranged before and after the automatic regulating valve of the first instrument automatic control valve group 1. A vent valve is arranged between the automatic regulating valve and the root valves before and after the automatic regulating valve. The pipeline of the vent valve is connected to an external ammonia recovery device. During maintenance, the residual pressure is relieved and the tail gas is recovered through the vent valve to ensure the safety of maintenance and eliminate environmental impact. The root valve can facilitate the maintenance of the automatic regulating valve.

[0035] The vent valve is a double valve to comply with the safety setting specifications of the ammonia storage tank.

[0036] The second stage pressure reducing device is provided with a second instrument automatic control valve group 2, the relay liquid ammonia storage tank concentrated pressure signal is P2, and the second instrument automatic control valve group 2 automatically adjusts the pressure after the valve through P2;

[0037] The second instrument automatic control valve group 2 includes an automatic regulating valve, root valves before and after the automatic regulating valve, and a bypass valve;

[0038] Generally, the pressure before the valve group is about 2.4MPa, and the pressure P2 after the valve group is controlled in the range of 1.8-2.1MPa. It is appropriate to control the pressure difference to 0.2-0.4MPa, and it can be adjusted according to specific circumstances.

[0039] The second-stage pressure reducing device is provided with a matching root valve, a shortcut valve and a vent valve to meet the requirements of automatic regulating valve maintenance and venting tail gas recovery.

[0040] The relay liquid ammonia storage tank body has a vent valve group to ensure pressure balance when feeding the ammonia relay tank. The relay liquid ammonia storage tank body is provided with a pressure reducing device, and the pressure reducing device is provided with a third instrument automatic control valve group 3;

[0041] The third instrument automatic control valve group 3 includes an automatic regulating valve, a root valve before and after the automatic regulating valve, and a bypass valve. The third instrument automatic control valve group 3 automatically adjusts the valve opening or opening degree through P2;

[0042] Generally, during feeding, the pressure P2 of the liquid ammonia storage tank is controlled in the range of about 1.2-1.6MPa, and the pressure difference with the external supply is controlled in the range of about 0.2-0.4MPa, which can be adjusted according to specific circumstances.

[0043] The pressure reducing device of the relay liquid ammonia storage tank is provided with a matching root valve, a shortcut valve and a vent valve to meet the maintenance requirements of the automatic regulating valve.

[0044] Specifically, the liquid ammonia relay tank plays a connecting role in the liquid ammonia production process. When storing and delivering liquid ammonia, it is necessary to control the normal inflow and outflow of liquid ammonia through pressure balance. The utility model further explains the specific implementation as follows in view of the existing problems. Figure 1 :

[0045] 1. During feeding, the pressure of the storage tank can be reduced to a certain range through the relay liquid ammonia storage tank body pressure reducing device, and the pressure difference with the external supply is generally controlled to be in the range of 0.2-0.4MPa; in particular, the venting air is connected to the ammonia recovery device to ensure that there is no impact on the environment.

[0046] 2. When liquid ammonia is delivered from the relay liquid ammonia storage tank, medium-pressure nitrogen is used as the pressure balance gas source. A secondary pressure-replenishing device is used to ensure that there is a certain pressure difference between the relay tank and the downstream users of the subsequent receiving process. The pressure difference can be adjusted according to various actual working conditions.

[0047] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid ammonia storage tank pressure balance control device, characterized in that: The medium-pressure nitrogen from the air separation is connected to the relay liquid ammonia storage tank through a pressure reducing device; The air separation medium-pressure nitrogen main pipe of the air separation unit is connected to the relay liquid ammonia storage tank through a secondary pressure reducing device; The air separation nitrogen main pipe of the air separation unit reduces the nitrogen pressure through a first-stage pressure reducing device; The first-stage pressure reducing device is provided with a first instrument automatic control valve group (1), the concentrated pressure signal after the valve group of the first instrument automatic control valve group (1) is P1, and the first instrument automatic control valve group (1) automatically adjusts the pressure after the valve through P1; The first instrument automatic control valve group (1) comprises an automatic regulating valve and a bypass valve, root valves are arranged before and after the automatic regulating valve of the first instrument automatic control valve group (1), a vent valve is arranged between the automatic regulating valve and the root valves before and after the automatic regulating valve, and a pipeline of the vent valve is connected to an external ammonia recovery device; A second stage pressure reducing device is connected in series after the first stage pressure reducing device, and the second stage pressure reducing device is connected to a relay liquid ammonia storage tank; The second-stage pressure reducing device is provided with a second instrument automatic control valve group (2), the relay liquid ammonia storage tank concentrated pressure signal is P2, and the second instrument automatic control valve group (2) automatically adjusts the pressure after the valve through P2; The second instrument automatic control valve group (2) comprises an automatic regulating valve, root valves before and after the automatic regulating valve, and a bypass valve; The second-stage pressure reducing device is provided with a matching root valve, a short-circuit valve and a vent valve; The relay liquid ammonia storage tank body has a venting valve group, and the relay liquid ammonia storage tank body is provided with a pressure reducing device, and the pressure reducing device is provided with a third instrument automatic control valve group (3); The third instrument automatic control valve group (3) comprises an automatic regulating valve, root valves before and after the automatic regulating valve, and a bypass valve. The third instrument automatic control valve group (3) automatically regulates the valve opening or opening degree through P2; The pressure reducing device of the relay liquid ammonia storage tank is provided with a matching root valve, a shortcut valve and a vent valve.

2. A liquid ammonia storage tank pressure balance control device according to claim 1, characterized in that: The vent valve is a double valve.

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