Sealed defrosting device for mixed gas discharge pipe of cryopump

Abstract

The utility model belongs to the technical field of low-temperature pump discharge pipe defrosting equipment, and relates to a low-temperature pump mixed gas discharge pipe sealing defrosting device which comprises a low-temperature pump impeller, a low-temperature pump shaft is connected to the front side of the low-temperature pump impeller, a labyrinth sealer is arranged on the low-temperature pump shaft, a primary sealing gas inlet pipe is connected to the labyrinth sealer, and a secondary sealing gas inlet pipe is connected to the primary sealing gas inlet pipe. The front end of the first-stage sealing gas inlet pipe is connected to the defrosting sealer through a defrosting gas inlet pipe, and the front end of the defrosting sealer is inserted into the discharge pipe and extends out of the rear end to be connected to the labyrinth sealer. A dry and pure air source is introduced, so that a dry micro-positive pressure environment is formed in a low-temperature discharge pipe area, the outside atmosphere is isolated, condensation and freezing of water vapor are eliminated, condensation and freezing of the water vapor are avoided, and the operation safety of equipment is improved.

Description

Technical Field

[0001] This utility model belongs to the technical field of defrosting equipment for cryogenic pump discharge pipes, specifically relating to a sealing defrosting device for a cryogenic pump mixed gas discharge pipe. Background Technology

[0002] The air separation unit uses atmospheric air as its processing feedstock and employs a deep cryogenic process. Inside the fractionation tower, the air is first liquefied, then refined to extract nitrogen, oxygen, and argon. The high-purity gaseous product is reheated, pressurized by a compressor, and then supplied to various users in the steel plant. A cryogenic liquid pump powers the liquid product, used for continuous distillation in the fractionation tower or for external supply to users. The cryogenic liquid pump operates in a low-temperature range of -183 to -190°C. A sealing gas path is designed between the pump impeller and the rotating bearing to isolate the impeller from cryogenic conduction and ensure bearing operation. The sealing gas leaking from the bearing seal mixes with a small amount of gas leaking from the cryogenic product and is released into the atmosphere.

[0003] To address the issues of frosting and freezing at low temperatures, the discharge pipe of a cryogenic liquid pump is typically designed in a spiral shape. Increasing the number of spiral turns increases the length of the discharge pipe, thereby increasing its heat exchange area and preventing frost from melting. Additionally, a special hammer is used for manual defrosting; due to safety requirements, the hammer for cryogenic liquid oxygen pumps is made of copper.

[0004] Natural defrosting works well in hot summer weather, but in low-temperature, high-humidity environments, frost often forms on the gas-mixed exhaust pipe. Over time, this freezes, increasing the pipe's weight and affecting operational safety. Increasing the number of spiral turns in the exhaust pipe to improve heat transfer also adds to the weight of the frost. Furthermore, manual defrosting by tapping introduces external vibration into the exhaust pipe. At the point where the exhaust pipe exits the air separation unit, this vibration causes friction and wear, impacting operational safety.

[0005] Therefore, a defrosting device for sealing the discharge pipe of a cryogenic pump mixed gas is provided. Utility Model Content

[0006] The purpose of this invention is to provide a cryogenic pump mixed gas discharge pipe sealing defrosting device, which has a cryogenic pump mixed gas discharge pipe sealing defrosting function. This solves the problems of existing technologies where natural melting occurs in low-temperature, high-humidity environments, frequently resulting in frost formation on the mixed gas discharge pipe. Over time, this leads to freezing, increasing the weight of the mixed gas discharge pipe and affecting equipment operation safety. Furthermore, manual defrosting methods, such as tapping, cause external force vibration to the mixed gas discharge pipe, resulting in friction and wear, which also affects equipment operation safety.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows: This utility model provides a cryogenic pump mixed gas discharge pipe sealing defrosting device, including a cryogenic pump impeller, a cryogenic pump shaft connected to the front side of the cryogenic pump impeller, a labyrinth seal provided on the cryogenic pump shaft, a primary sealing gas inlet pipe connected to the labyrinth seal, the front end of the primary sealing gas inlet pipe being connected to the defrost seal via a defrost inlet pipe, the front end of the defrost seal being inserted into the discharge pipe and extending from the rear end to connect to the labyrinth seal.

[0008] Preferably, a bearing is provided at the rear end of the cryogenic pump shaft.

[0009] Preferably, the labyrinth sealer is also connected to a secondary sealing gas inlet pipe.

[0010] Preferably, the discharge pipe is spirally placed inside the defrost seal, and preferably, the discharge pipe is fixed to the inner wall of the defrost seal by a plastic support.

[0011] The defrosting sealer has a sealing gas outlet at its rear end.

[0012] An air intake valve is installed on the defrosting air intake pipe.

[0013] Compared with the prior art, the advantages and positive effects of this utility model are as follows:

[0014] 1. This utility model introduces a dry and pure air source to create a dry, slightly positive pressure environment in the low-temperature discharge pipe area, which isolates the outside atmosphere, eliminates the condensation and freezing of water vapor, and improves the safety of equipment operation.

[0015] 2. This utility model features a sealing and defrosting function for the low-temperature pump's mixed gas discharge pipe, solving the problems of existing technologies where natural melting often results in frost formation on the mixed gas discharge pipe in low-temperature, high-humidity environments. Over time, this leads to freezing, increasing the weight of the mixed gas discharge pipe and affecting equipment operation safety. Furthermore, manual defrosting methods, such as tapping, cause external vibrations to the mixed gas discharge pipe, resulting in friction and wear, which also impacts equipment operation safety. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of a defrosting device for sealing the discharge pipe of a cryogenic pump mixture;

[0018] Figure 2 It is a partial structural diagram of a sealing and defrosting device for the mixed gas discharge pipe of a cryogenic pump;

[0019] In the above figures, 1 is the primary sealing gas inlet pipe, 2 is the discharge pipe, 3 is the secondary sealing gas inlet pipe, 4 is the bearing, 5 is the cryogenic pump shaft, 6 is the labyrinth seal, 7 is the cryogenic pump impeller, 8 is the defrosting inlet pipe, 9 is the defrosting seal, 10 is the plastic bracket, and 11 is the sealing gas outlet. Specific Embodiment

[0020] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0021] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the present invention is not limited by the specific embodiments disclosed in the following specification.

[0022] Embodiment 1, as Figure 1-2 shown, a sealing and defrosting device for the mixed gas discharge pipe of a cryogenic pump includes a cryogenic pump impeller 7. The cryogenic pump impeller 7 is a part of a cryogenic liquid pump supporting an air separation device, used to transport cryogenic liquid, and the working temperature is in the range of -183 to -190 °C. The front side of the cryogenic pump impeller 7 is connected to a cryogenic pump shaft 5. The cryogenic pump shaft 5 connects the cryogenic pump impeller 7 and transmits power. A labyrinth seal 6 is provided on the cryogenic pump shaft 5. The labyrinth seal 6 provides a complex path to block gas leakage, enhances the sealing effect through multiple labyrinth structures, and prevents the low-temperature cold quantity at the working end of the cryogenic pump impeller 7 from conducting and leaking to the front end of the cryogenic pump shaft 5. The sealing gas of the labyrinth seal 6 requires dry, clean, oil-free air or nitrogen, and the dew point temperature < -60 °C.

[0023] A primary sealing gas inlet pipe 1 is connected to the labyrinth seal 6. The primary sealing gas inlet pipe 1 transports dry and pure sealing gas to form a dry slightly positive pressure environment, isolates the outside atmosphere, and prevents water vapor from condensing into ice. The front end of the primary sealing gas inlet pipe 1 is connected to a defrosting seal 9 through a defrosting inlet pipe 8. The defrosting inlet pipe 8 is used to lead out the sealing gas in the primary sealing gas inlet pipe 1. Using the principle that the thermal conductivity of dry gas is less than that of water and ice, a dry space isolated from the atmospheric environment can be formed inside the defrosting seal 9. Purified dry and heated air or low-pressure nitrogen can be used. The physical characteristic of the gas source is dry, and its dew point temperature needs to be below -65 °C.

[0024] The front end of the defrost seal 9 is inserted into the discharge pipe 2 and extends out from the rear end to connect to the labyrinth seal 6. Under the isolation of the dry gas, the low temperature of the discharge pipe 2 cannot be conducted to the defrost seal 9. Moreover, the dry gas does not contain moisture, so there will be no frost or frosting on the outside of the discharge pipe 2 which is wrapped by the defrost seal 9.

[0025] The specific design of the aforementioned key components will be discussed in detail below:

[0026] A bearing 4 is installed at the rear end of the cryogenic pump shaft 5. A secondary sealing gas inlet pipe 3 is also connected to the labyrinth seal 6. The sealing gas employs a two-way design: one is the primary sealing gas, with the primary sealing gas inlet pipe 1 connected to the front side of the labyrinth seal 6 near the impeller; the other is the secondary sealing gas, with the secondary sealing gas inlet pipe 3 connected to the rear side of the labyrinth seal 6 near the bearing 4. A discharge pipe 2 is connected between the primary sealing gas inlet pipe 1 and the secondary sealing gas inlet pipe 3 at the midpoint of the labyrinth seal 6.

[0027] The discharge pipe 2 is spirally placed inside the defrost seal 9. The discharge pipe 2 is fixed to the inner wall of the defrost seal 9 by a plastic bracket 10. The height of the plastic bracket 10 is slightly less than the radius of the inner wall of the defrost seal 9 by 2-3 cm. The plastic bracket 10 provides stable support for fixing the discharge pipe 2 inside the defrost seal 9. The plastic bracket 10 is low-temperature resistant and non-thermal conductive. The defrost seal 9 can be made using a thin aluminum sheet to create a circular sleeve, with sealing heads made on both the front and rear sides of the sleeve.

[0028] The defrost seal 9 is provided with a sealing gas outlet 11 at its rear end. The sealing gas outlet 11 discharges the gas inside the defrost seal 9, maintaining the gas pressure balance inside the defrost seal 9 and avoiding overpressure. A dry and pure gas source is introduced into the defrost seal 9 to form a dry micro-positive pressure environment, isolating it from the outside atmosphere and preventing the outside of the discharge pipe 2 from coming into contact with water vapor and causing condensation and freezing.

[0029] An air inlet valve is provided on the defrost air inlet pipe 8. The opening of the defrost air inlet pipe 8 is adjusted by regulating the air inlet valve to adjust the flow rate of the outgoing gas.

[0030] All standard parts used in this utility model can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art. In addition, the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0031] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution of the present utility model shall still fall within the protection scope of the present utility model.

Claims

1. A cryogenic pump mixed gas discharge pipe sealing and defrosting device, comprising a cryogenic pump impeller, characterized in that: The front side of the cryopump impeller is connected to a cryopump shaft, a labyrinth seal is arranged on the cryopump shaft, a first-level sealing gas inlet pipe is connected to the labyrinth seal, a front end of the first-level sealing gas inlet pipe is connected to the defrost sealer through a defrost air inlet pipe, a front end of the defrost sealer is inserted into a discharge pipe and extends from the rear end to be connected to the labyrinth sealer.

2. A cryogenic pump mixed gas discharge pipe sealing and defrosting device according to claim 1, characterized in that: A bearing is arranged at the rear end of the cryogenic pump shaft.

3. A cryogenic pump mixed gas discharge pipe sealing and defrosting device according to claim 2, characterized in that: The labyrinth sealer is also connected with a secondary sealing gas inlet pipe.

4. A cryogenic pump mixed gas discharge pipe sealing and defrosting device according to claim 3, characterized in that: The primary sealing gas inlet pipe is connected to the area on the front side of the labyrinth sealer close to the cryogenic pump impeller, and the secondary sealing gas inlet pipe is connected to the area on the rear side of the labyrinth sealer close to the bearing.

5. A cryogenic pump mixed gas discharge pipe sealing and defrosting device according to claim 4, characterized in that: The middle part of the labyrinth sealer is connected with a discharge pipe between the connection positions of the primary sealing gas inlet pipe and the secondary sealing gas inlet pipe.

6. A cryogenic pump mixed gas discharge pipe sealing and defrosting device according to claim 1, characterized in that: The discharge pipe is placed in a spiral shape in the defrost sealer, and the discharge pipe is fixed to the inner wall of the defrost sealer through a plastic bracket.

7. A cryogenic pump mixed gas discharge pipe sealing and defrosting device according to claim 1, characterized in that: A sealing gas outlet is arranged at the rear end of the defrost sealer.

8. A cryogenic pump mixed gas discharge pipe sealing and defrosting device according to claim 1, characterized in that: An air intake valve is arranged on the defrosting air intake pipe.

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