Liquid nitrogen tank emptying and gas nitrogen recovery device

Abstract

This utility model discloses a liquid nitrogen tank venting and nitrogen recovery device, belonging to the field of chemical technology and relating to cryogenic gas recovery. The device includes a liquid nitrogen tank, a liquid nitrogen pump, an extended discharge pipe, a liquid nitrogen vaporization device, and a cold box. The extended discharge pipe is made of cryogenically resistant material, with a length ≥3 meters, and is connected to the liquid nitrogen tank's discharge pipe via a valve. The horizontal distance between the extended discharge pipe and the liquid nitrogen tank's foundation is ≥3 meters. The end of the extended discharge pipe is connected to the liquid nitrogen vaporization device. The liquid nitrogen pump is connected to the liquid nitrogen vaporization device via a collection pipe equipped with a valve. The liquid nitrogen vaporization device is connected to the cold box via a collection pipe equipped with a valve. This utility model solves the cost, safety, and environmental problems associated with traditional venting methods, achieving 100% recovery of nitrogen from vented liquid nitrogen tanks, reducing production costs, and eliminating the risk of nitrogen poisoning and asphyxiation, as well as the potential for equipment foundation damage from freezing.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology and relates to cryogenic gas recovery, specifically a liquid nitrogen tank venting and gas nitrogen recovery device. Background Technology

[0002] In production, traditional venting systems for cryogenic storage tanks such as liquid nitrogen tanks present problems such as resource waste, safety hazards, and environmental impact. Specifically: direct discharge of liquid nitrogen or nitrogen gas without recycling increases nitrogen procurement costs and energy consumption; nitrogen gas accumulates in confined spaces after vaporization, which can easily lead to personnel asphyxiation and nitrogen poisoning risks, or the low-temperature discharge can freeze and damage the tank foundation or pipelines, reducing equipment lifespan and even causing leakage accidents; liquid nitrogen vaporization absorbs heat, changing the local ambient temperature and indirectly exacerbating energy waste, such as requiring additional heating for surrounding equipment.

[0003] However, existing technologies lack efficient recovery devices for the vented gas from liquid nitrogen tanks, and cannot simultaneously solve the problems of cost, safety, and environment. Therefore, this problem seriously restricts the economic efficiency and safety of chemical production, and innovative technical solutions are urgently needed.

[0004] To address the aforementioned shortcomings of existing technologies, a liquid nitrogen tank venting and gas nitrogen recovery device was developed. Utility Model Content

[0005] The purpose of this invention is to provide a liquid nitrogen tank venting and gas nitrogen recovery device to achieve the recovery and utilization of vented nitrogen, eliminate safety hazards, reduce costs, and improve equipment operational stability.

[0006] This utility model is achieved through the following technical solution: A liquid nitrogen tank venting and gaseous nitrogen recovery device includes a liquid nitrogen tank, a liquid nitrogen pump, an extended discharge pipe, a liquid nitrogen vaporization device, and a cold box. The extended discharge pipe is made of cryogenic material, has a length of ≥3 meters, and is connected to the discharge pipe of the liquid nitrogen tank via a valve. The horizontal distance between the installation position of the extended discharge pipe and the foundation of the liquid nitrogen tank is ≥3 meters. The end of the extended discharge pipe is connected to the liquid nitrogen vaporization device. The liquid nitrogen pump is connected to the liquid nitrogen vaporization device via a collection pipe equipped with a valve. The liquid nitrogen vaporization device is connected to the cold box via a recovery pipe equipped with a valve.

[0007] Furthermore, the extended discharge pipe is made of stainless steel or aluminum alloy and has resistance to low-temperature embrittlement.

[0008] The liquid nitrogen vaporization device is a heat exchanger structure. The vaporization efficiency is improved by increasing the heat exchange area. It is preferably made of 304 stainless steel and has a heat exchange area of ​​2m². The heat exchanger is installed at the end of the extension pipe. The inlet of the heat exchanger is sealed to the flange of the extension pipe, and the outlet is connected to the recovery pipe to ensure smooth flow of liquid nitrogen and uniform heat exchange.

[0009] The recovery pipe is connected to the liquid nitrogen vaporization device and the cold box at both ends via flanges. A pressure gauge is installed on the recovery pipe, and the pressure is monitored and regulated by the pressure gauge and the valve body. The valve body on the recovery pipe is a cryogenic ball valve (resistant to -200℃) to ensure reliable sealing.

[0010] The two extension discharge pipes, collection pipes, and recovery pipes, as well as the connection between the pipes and the valve body, are flanged and equipped with sealing gaskets to ensure the airtightness of the device.

[0011] This invention connects the discharge extension pipe to the original discharge pipe of the liquid nitrogen tank. The length of the discharge extension pipe is not less than 3 meters, and it is made of low-temperature resistant material to withstand the low-temperature environment during the liquid nitrogen discharge process. At the same time, the horizontal distance between the installation position of the extension pipe and the foundation of the liquid nitrogen tank is ≥3 meters to avoid the impact of cold energy on the tank foundation. The discharge extension pipe is led to an open area next to the tank. The end of the extension discharge pipe is connected to the liquid nitrogen vaporization device. Heat exchange is carried out through the natural temperature difference between the ambient temperature and the liquid nitrogen to quickly convert liquid nitrogen into gaseous nitrogen. The liquid nitrogen vaporization device is a heat exchanger structure. The vaporization efficiency is improved by increasing the heat exchange area. The preferred material is 304 stainless steel with a heat exchange area of ​​2m². The inlet of the heat exchanger is sealed to the flange of the extension pipe, and the outlet is connected to the recovery pipe to ensure smooth flow of liquid nitrogen and uniform heat exchange.

[0012] The operating principle is as follows: When the liquid nitrogen tank is in normal use, the pressure of the liquid nitrogen tank is controlled between 0.2-0.4 MPa. If the pressure of the liquid nitrogen tank rises, the pressure is adjusted, the liquid nitrogen tank vent valve is opened, and the liquid nitrogen enters the liquid nitrogen vaporization device through the valve body on the discharge extension pipe for vaporization. The heat exchange process of the liquid nitrogen vaporization device does not require external energy drive, but only relies on the natural temperature difference to complete the vaporization. After the pressure detection device ensures that the gas pressure meets the system requirements, the gas enters the cold box as sealing gas through the valve body on the recovery pipe, realizing the reuse of nitrogen. Another part is that when the liquid nitrogen pump is running normally, some leaked liquid and gas are generated. The valve body on the collection pipe is opened to enter the vaporization device, and after vaporization, it enters the cold box as sealing gas.

[0013] Compared with existing technologies, this utility model solves the cost, safety and environmental problems of traditional venting, achieves 100% recovery of nitrogen gas vented from liquid nitrogen tanks, reduces production costs, and eliminates the risk of nitrogen poisoning and suffocation as well as the hidden danger of equipment foundation freezing damage. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model; In the diagram: 1-Liquid nitrogen tank, 2-Extended discharge pipe, 3-Liquid nitrogen vaporization device, 4-Cold box, 5-Pressure gauge. Detailed Implementation

[0015] The technical solutions of the present utility model 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 utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0016] like Figure 1 The device shown is a liquid nitrogen tank venting and gas nitrogen recovery device, comprising a liquid nitrogen tank 1, a liquid nitrogen pump, an extended discharge pipe 2, a liquid nitrogen vaporization device 3, and a cold box 4; the extended discharge pipe 1 is connected to the discharge pipe of the liquid nitrogen tank 1 via a valve body; the end of the extended discharge pipe 2 is connected to the liquid nitrogen vaporization device 3; the liquid nitrogen pump is connected to the liquid nitrogen vaporization device 3 via a collection pipe equipped with a valve body; the liquid nitrogen vaporization device 3 is connected to the cold box 4 via a collection pipe equipped with a valve body.

[0017] The extended discharge pipe 2 is made of low-temperature resistant stainless steel / aluminum alloy (anti-embrittlement), with a length of ≥3 meters. It is connected to the discharge pipe of liquid nitrogen tank 1 through a valve body, and the horizontal distance between the installation position of the extended discharge pipe and the foundation of the liquid nitrogen tank is ≥3 meters (to avoid cold corrosion of the foundation). Its function is to lead liquid nitrogen to an open area, disperse the influence of low temperature, and provide space for vaporization.

[0018] The liquid nitrogen vaporization device 3 uses a heat exchanger made of 304 stainless steel with a heat exchange area of ​​2m². It utilizes the natural temperature difference between the ambient temperature and the liquid nitrogen for heat exchange, eliminating the need for external energy and rapidly vaporizing the liquid nitrogen.

[0019] The connecting pipes are connected via a combination of flanges and sealing gaskets, and are connected to the sealing gas system of the cold box 4; the valve body used is a low-temperature ball valve (resistant to -200℃) to ensure reliable sealing.

[0020] Configure pressure gauge 5 to detect the device pressure, ensure that the gas pressure matches the requirements of cold box 5, and prevent leakage.

[0021] When the liquid nitrogen tank 1 is in normal use, the pressure of the liquid nitrogen tank is controlled between 0.2-0.4 MPa. If the pressure of the liquid nitrogen tank rises, the pressure is adjusted by opening the liquid nitrogen tank vent valve and allowing the liquid nitrogen to enter the liquid nitrogen vaporization device 3 through the extended discharge pipe 2. After vaporization and pressure reduction, the liquid nitrogen enters the cold box 4 as a sealing gas. Another part of the liquid nitrogen is generated when the liquid nitrogen pump is running normally. Some of the leaked liquid and gas enters the liquid nitrogen vaporization device 3 and then enters the cold box 4 as a sealing gas.

[0022] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for venting and recovering gaseous nitrogen from a liquid nitrogen tank, characterized in that, The system includes a liquid nitrogen tank, a liquid nitrogen pump, an extended discharge pipe, a liquid nitrogen vaporization device, and a cold box. The extended discharge pipe is made of cryogenic material, with a length ≥3 meters, and is connected to the discharge pipe of the liquid nitrogen tank via a valve. The horizontal distance between the installation position of the extended discharge pipe and the foundation of the liquid nitrogen tank is ≥3 meters. The end of the extended discharge pipe is connected to the liquid nitrogen vaporization device. The liquid nitrogen pump is connected to the liquid nitrogen vaporization device via a collection pipe equipped with a valve. The liquid nitrogen vaporization device is connected to the cold box via a recovery pipe equipped with a valve.

2. The liquid nitrogen tank venting and gas nitrogen recovery device according to claim 1, characterized in that, The extended discharge pipe is made of stainless steel or aluminum alloy.

3. A liquid nitrogen tank venting and gas nitrogen recovery device according to claim 1, characterized in that, The liquid nitrogen vaporization device is a heat exchanger structure.

4. A liquid nitrogen tank venting and gas nitrogen recovery device according to claim 3, characterized in that, The liquid nitrogen vaporization device is made of 304 stainless steel and has a heat exchanger with a heat exchange area of ​​2m².

5. A liquid nitrogen tank venting and gaseous nitrogen recovery device according to claim 4, characterized in that, The heat exchanger inlet is sealed to the extension tube flange, and the outlet is connected to the recovery pipe.

6. A liquid nitrogen tank venting and gas nitrogen recovery device according to claim 1, characterized in that, The recovery pipe is connected to the liquid nitrogen vaporization device and the cold box at both ends via flanges.

7. A liquid nitrogen tank venting and gas nitrogen recovery device according to claim 1, characterized in that, A pressure gauge is installed on the recovery pipe.

8. A liquid nitrogen tank venting and gaseous nitrogen recovery device according to claim 7, characterized in that, The valve body is a cryogenic ball valve.

9. A liquid nitrogen tank venting and gas nitrogen recovery device according to claim 1, characterized in that, The two extension discharge pipes, collection pipes, and recovery pipes, as well as the connection between the pipes and the valve body, are flanged and equipped with sealing gaskets.

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