Liquid nitrogen refrigerating system

Abstract

The liquid nitrogen refrigerating system comprises a compressor used for pressurizing nitrogen; the first heat exchanger is used for cooling nitrogen and connected with a gas output port of the compressor through a pipeline; the second heat exchanger is used for cooling the nitrogen to a liquid state and is connected with the first heat exchanger through a first pipeline; the throttling valve is connected with the second heat exchanger through a second pipeline, an outlet of the throttling valve is connected with a separator, the bottom of the separator is connected with a liquid nitrogen output pipe, the top of the separator is connected with an inlet of a compressor through a nitrogen output pipe, and the nitrogen output pipe sequentially passes through the second heat exchanger and the first heat exchanger. And cooling capacity is provided for the second heat exchanger and the first heat exchanger. The liquid nitrogen circulating refrigeration system has the advantages that liquid nitrogen circulating refrigeration is adopted, the nitrogen consumption is low, and the refrigeration efficiency is high.

Description

Technical Field

[0001] The utility model relates to the recycling of chemical gases, in particular to a liquid nitrogen refrigeration system suitable for a low-temperature adsorption pump. Background Art

[0002] A device that relies on the spontaneous condensation of gas molecules under low temperature conditions or adsorption by the surface of other substances to remove gas molecules and obtain a high vacuum is called a cryogenic adsorption pump. The vacuum degree obtained by using a cryogenic adsorption pump depends on many factors such as the cryogenic temperature used, the surface area of ​​the adsorbed material, the type of adsorbed gas, etc. Its ultimate vacuum degree is generally between 10-1 and 10-8Pa. In the physical adsorption process, adsorption is exothermic, so a low-temperature cooling source needs to be provided. The adsorption amount decreases with increasing temperature, which is an inevitable result of thermodynamics. However, when the gas adsorbate molecules (such as N2, A r , CO, etc.) is close to the pore size of the adsorbent, there is only a trace amount of adsorption at 0°C, while the adsorption amount can reach 130mL / g (18.6%) at -196°C. Cryogenic adsorption pumps are mainly used for vacuuming systems in very harsh environments, such as vacuuming systems under conditions of high dust, high gas output, and easy leakage. Liquid nitrogen can be used as a cold source for cryogenic adsorption pumps, but liquid nitrogen evaporates quickly. Liquid nitrogen evaporates quickly on the quick-frozen material and immediately detaches from the surface of the frozen material, resulting in insufficient heat exchange, insufficient utilization of cold capacity, and waste of resources.

[0003] At present, there is a lack of a technology suitable for low-temperature adsorption pumps that can refrigerate liquid nitrogen in a circulating manner. Utility Model Content

[0004] The utility model aims to provide a liquid nitrogen refrigeration system.

[0005] The liquid nitrogen refrigeration system of the utility model comprises:

[0006] Compressors for pressurizing nitrogen;

[0007] A first heat exchanger for cooling nitrogen, connected to the gas outlet of the compressor through a pipeline;

[0008] A second heat exchanger for cooling the nitrogen to a liquid state, connected to the first heat exchanger through a first pipeline;

[0009] A throttle valve for throttling and reducing the pressure of nitrogen is connected to the second heat exchanger through a second pipeline, an outlet of the throttle valve is connected to a separator, a bottom of the separator is connected to a liquid nitrogen output pipe, a top of the separator is connected to a gas inlet of a compressor through a nitrogen output pipe, and the nitrogen output pipe passes through the second heat exchanger and the first heat exchanger in sequence, so that the nitrogen in the nitrogen output pipe provides cooling capacity for the second heat exchanger and the first heat exchanger.

[0010] The utility model provides a liquid nitrogen refrigeration system, wherein a branch pipeline is connected to the first pipeline, the branch pipeline is connected to the air inlet of the expander, the air outlet of the expander is connected to the nitrogen output pipe through a pipeline, and the connection point is located between the second heat exchanger and the separator.

[0011] The liquid nitrogen refrigeration system of the utility model has a nitrogen output pipe connected to a low-temperature nitrogen input pipe, and a gas inlet of a compressor connected to a nitrogen supplement pipeline.

[0012] The utility model has the advantages of: adopting liquid nitrogen circulation refrigeration, low nitrogen consumption, high refrigeration efficiency, closed circulation of liquid nitrogen, and full recycling of liquid nitrogen after gasification, which can save the cost of purchasing liquid nitrogen and reduce processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the liquid nitrogen refrigeration system of the utility model. DETAILED DESCRIPTION

[0014] like Figure 1 As shown, the liquid nitrogen refrigeration system of the utility model comprises:

[0015] Compressor C1 for pressurizing nitrogen;

[0016] A first heat exchanger E1 for cooling nitrogen is connected to the gas outlet of the compressor through a pipeline;

[0017] A second heat exchanger E2 for cooling nitrogen to a liquid state, connected to the first heat exchanger via a first pipeline 10;

[0018] The throttle valve V1 used for throttling and reducing the pressure of nitrogen is connected to the second heat exchanger through the second pipeline 20. The outlet of the throttle valve is connected to the separator F1. The bottom of the separator is connected to the liquid nitrogen output pipe 30. The top of the separator is connected to the gas inlet of the compressor C1 through the nitrogen output pipe 40. The nitrogen output pipe 40 passes through the second heat exchanger and the first heat exchanger in sequence, so that the nitrogen in the nitrogen output pipe provides cooling capacity for the second heat exchanger and the first heat exchanger.

[0019] In the liquid nitrogen refrigeration system of the present invention, a branch pipeline 11 is connected to the first pipeline 10, the branch pipeline is connected to the air inlet of the expander T1, the air outlet of the expander is connected to the nitrogen output pipe 40 through a pipeline, and the connection point is located between the second heat exchanger and the separator.

[0020] In the liquid nitrogen refrigeration system of the utility model, the nitrogen output pipe is connected to the low-temperature nitrogen input pipe 50, and the gas inlet of the compressor is connected to the nitrogen supplement pipeline 60.

[0021] The liquid nitrogen refrigeration system of the utility model comprises the following equipment: a compressor, a heat exchanger, an expander, a separator and related valves and pipelines.

[0022] The working process of the liquid nitrogen refrigeration system of the utility model is as follows:

[0023] The nitrogen is pressurized by the compressor C1, enters the first heat exchanger E1 for cooling, and is then divided into two streams. One stream enters the second heat exchanger E2 for cooling, is throttled and depressurized by the throttle valve V1, and then enters the separator F1 for separation. The liquid nitrogen separated at the bottom of the separation is sent out of the boundary area, and the nitrogen at the top is successively reheated by the second heat exchanger E2 and the first heat exchanger E1 and then returns to the compressor inlet. The other stream enters the expander T1 for expansion and then merges into the gas phase pipeline of the separator F1. The low-temperature nitrogen returned from the boundary area enters the separator gas phase pipeline, and a nitrogen supplementary pipeline 60 is set at the gas inlet of the compressor C1.

[0024] The heat exchanger can be a plate-fin heat exchanger, a plate heat exchanger, a coiled-wound heat exchanger, a shell-and-tube heat exchanger or a combination thereof.

[0025] The compressor may be a screw compressor, a piston compressor, a centrifugal compressor or a diaphragm compressor.

[0026] The expander can be a turbine expander, a screw expander or a piston expander.

[0027] The liquid nitrogen refrigeration system of the utility model is particularly suitable for a low-temperature adsorption pump.

[0028] The utility model has the advantages of adopting liquid nitrogen circulation refrigeration, low nitrogen consumption and high refrigeration efficiency.

[0029] Liquid nitrogen is closed-loop and all liquid nitrogen is recycled after being gasified, which can save the cost of purchasing liquid nitrogen and reduce processing costs.

[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A liquid nitrogen refrigeration system, characterized in that: include: Compressors for pressurizing nitrogen; A first heat exchanger for cooling nitrogen, connected to the gas outlet of the compressor through a pipeline; A second heat exchanger for cooling the nitrogen to a liquid state, connected to the first heat exchanger through a first pipeline; A throttle valve for throttling and reducing the pressure of nitrogen is connected to the second heat exchanger through a second pipeline, an outlet of the throttle valve is connected to a separator, a bottom of the separator is connected to a liquid nitrogen output pipe, a top of the separator is connected to a gas inlet of a compressor through a nitrogen output pipe, and the nitrogen output pipe passes through the second heat exchanger and the first heat exchanger in sequence, so that the nitrogen in the nitrogen output pipe provides cooling capacity for the second heat exchanger and the first heat exchanger.

2. The liquid nitrogen refrigeration system according to claim 1, characterized in that: The first pipeline is connected to a branch pipeline, the branch pipeline is connected to the air inlet of the expander, the air outlet of the expander is connected to the nitrogen output pipe through a pipeline, and the connection point is located between the second heat exchanger and the separator.

3. The liquid nitrogen refrigeration system according to claim 1, characterized in that: The nitrogen output pipe is connected to the low-temperature nitrogen input pipe, and the gas inlet of the compressor is connected to the nitrogen replenishment pipeline.

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