Small temperature rise centrifugal steam compression device

Abstract

The present invention discloses a small temperature rise centrifugal steam compression device, including a compression element and a driver. The inlet and outlet of the compression element are both connected to the inlet and outlet pipes of the inlet pipe, a vent pipe is provided between the inlet pipe and the outlet pipe, and a vent valve is provided on the vent pipe; the temperature rise of steam after passing through the compression element is less than 10°C; the compression element includes a volute and an impeller arranged in the volute, the driver is connected to the impeller through a main shaft and drives the impeller to rotate; the volute is supported by a support body, and the connection point between the support body and the volute is consistent with the height of the main shaft center. The small temperature rise centrifugal steam compression device provided by the present invention has a compact structure, high efficiency in operation, low maintenance cost, stable equipment operation, and can be widely used in MVR evaporation systems.

Description

Technical Field

[0001] The invention relates to the technical field of steam compressors, and in particular to a small temperature rise centrifugal steam compression device. Background Art

[0002] As the world's requirements for environmental protection and energy conservation continue to increase, MVR (mechanical vapor recompression) system technology is widely used in food, pharmaceutical, chemical and wastewater treatment industries.

[0003] MVR system technology utilizes the secondary steam and its energy generated by the evaporation system itself, and through the mechanical work of the compressor, it upgrades low-quality steam into a high-quality steam heat source to replace fresh steam. This cycle provides heat energy to the evaporation system, thereby realizing an energy-saving technology that efficiently recycles and utilizes energy.

[0004] Among them, the core equipment of MVR technology is steam compressor. In particular, centrifugal steam compressors are increasingly used in MVR systems due to their superior performance such as large flow, high efficiency, oil-free and low maintenance costs. At present, centrifugal compressors used in MVR systems mostly use speed increasers to increase the speed of transmission to improve the rotation of the impeller inside the compressor.

[0005] However, due to the power loss of the speed increaser, the efficiency of the whole machine is reduced and the equipment maintenance links are increased; at the same time, the centrifugal compressor with a speed increaser has a high speed, so the noise generated during the operation of the equipment is also relatively large.

[0006] Secondly, the impeller inside the compressor is connected to the driver (motor) through a rotating shaft, and the rotating shaft passes through the sealing component on the stator component (volute) on the compressor. The sealing component is used to prevent steam leakage; however, traditional centrifugal steam compressors have not fully considered the impact of thermal deformation on the operation of the compressor. When the stator component (volute) is deformed, the rotating shaft and the stator component will be relatively offset, resulting in eccentric contact between the rotating shaft and the sealing component in the shaft hole, which will cause severe wear on one side of the sealing component, which will easily lead to a decrease in the sealing effect and cause steam leakage. Summary of the invention

[0007] The purpose of the present invention is to solve the deficiencies in the prior art and provide a centrifugal steam compression device with a small temperature rise.

[0008] The object of the present invention is achieved through the following technical scheme: a small temperature rise centrifugal steam compression device, comprising a compression element, a driver, the inlet and outlet of the compression element are connected to the inlet and outlet pipes, a vent pipe is arranged between the inlet and outlet pipes, and a vent valve is arranged on the vent pipe; the temperature rise of steam after passing through the compression element is less than 10°C;

[0009] The compression element includes a volute and an impeller arranged in the volute, and the driver is connected to the impeller through a main shaft and drives the impeller to rotate; the volute is supported by a support body, and the connection point between the support body and the volute is consistent with the height of the center of the main shaft.

[0010] As a preferred method, the diameter and speed of the impeller are calculated according to the steam inlet amount and the pressure ratio. The calculation formula of the impeller speed n is as follows:

[0011] ;

[0012] Where n is the impeller speed, is the flow coefficient, is the circumferential speed of the impeller, is the steam intake;

[0013] The calculation formula of the impeller diameter D2 is as follows:

[0014] ;

[0015] Among them, the circumferential speed of the impeller The calculation formula is as follows:

[0016] ;

[0017] In the formula, For the energy head, is the energy head coefficient;

[0018] Energy Head The calculation formula is as follows:

[0019] ;

[0020] In the formula, ε is the pressure ratio, σ is the exponential coefficient, T1 is the inlet steam temperature, is the gas constant.

[0021] Preferably, the driver is a variable frequency motor.

[0022] Preferably, a collector is provided at the inlet of the volute, and a water spraying device for cooling the steam is provided on the collector.

[0023] Preferably, when the steam is sprayed with water to reduce the temperature through the water spray device, the calculation formula of the cooling water volume d is as follows:

[0024] d =((h2-h1) / η+ h1- h2') ×D×0.95 / (h2'-hs);

[0025] Wherein, h1 is the enthalpy of inlet steam, h2 is the enthalpy of outlet steam, h2' is the enthalpy of outlet saturated steam, η is the adiabatic efficiency, hs is the enthalpy of cooling water; D is the steam evaporation amount.

[0026] Preferably, when the operating condition of the compression element is close to the surge line, the vent valve is opened and the opening of the vent valve is adjusted, and part of the steam discharged from the outlet pipe flows back to the inlet of the compression element through the vent pipe and the inlet pipe to reduce the surge of the compression element.

[0027] Preferably, the impeller and the driver are connected via a main shaft, and a main shaft hole is provided on the volute for the main shaft to pass through; an air seal is provided on the outside of the main shaft hole, the air seal is annular, the main shaft passes through the air seal, and the air seal is fixedly connected to the volute; the inside of the air seal adopts a carbon ring seal or a labyrinth seal to cooperate with the main shaft;

[0028] The air seal is provided with an air filling port, an air extraction port and a water discharge port, which all pass through the inner surface of the air seal, and the water discharge port is located at the lower side of the air seal;

[0029] When the internal pressure of the compression element is lower than the atmospheric pressure, clean steam is charged into the charging port of the gas seal, and the charging steam pressure is 10-20kPa higher than the outlet steam pressure of the compression element;

[0030] When the internal pressure of the compression element is greater than the atmospheric pressure, the inside of the shaft seal is evacuated through the evacuation port, and the evacuated steam is led to the inlet pipe;

[0031] Preferably, the main shaft is installed on the bearing seat, and an air baffle is provided on the main shaft, the air baffle is located between the air seal and the bearing seat, the air baffle is coaxially arranged with the main shaft, the air baffle is located on one side of the air seal, and a plurality of spiral grooves are provided on the side of the air baffle close to the air seal, the rotation direction of the spiral grooves is consistent with the rotation direction of the main shaft, and the spiral grooves are distributed on the air baffle in a circular array; an air baffle shield is provided on the periphery of the air baffle, and the lower end of the air baffle shield extends to the drain outlet on the air seal.

[0032] Preferably, a drainage device is provided at the lower end of the volute.

[0033] The beneficial effects of the present invention are:

[0034] 1. In the present invention, the temperature rise of steam after passing through the compression element is less than 10°C, which belongs to the small temperature rise range. To achieve this, a relatively low impeller speed can be used. Since the impeller speed is relatively low, it can be achieved without using a gearbox to increase the speed. The drive can be directly connected to the impeller; this eliminates the need for an intermediate gearbox, reduces the complexity of the structure and the manufacturing cost, and also reduces the maintenance cost; and the lower impeller speed also reduces the noise of the compression element during operation.

[0035] 2. In the present invention, the volute is supported by a supporting body, and the supporting body is connected to the equipment foundation so that the position of the supporting body remains fixed; the supporting body is supported at a position on the volute that is consistent with the center height of the main shaft (the horizontal mid-plane of the volute), while the rest of the position on the volute is in a suspended state (not supported). This has the advantage that when the volute is deformed by heat, the deformation of the volute diffuses radially from the axis to the surroundings, while the axis position of the volute remains almost unchanged, that is, even when the volute is thermally deformed, the axis position of the volute always remains concentric with the main shaft, so that the main shaft will not have eccentric contact with the sealing component on the volute, thereby avoiding severe unilateral wear of the sealing component and causing a decrease in sealing performance, thereby effectively preventing steam leakage.

[0036] 3. The small temperature rise centrifugal steam compression device provided by the present invention has a compact structure, high efficiency, low maintenance cost, stable equipment operation, and can be widely used in MVR evaporation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the structure of a small temperature rise centrifugal steam compression device.

[0038] Figure 2 A cross-sectional view of a compression element.

[0039] Figure 3 This is the front view of the volute.

[0040] Figure 4 This is a partial enlarged view of the compression element.

[0041] Figure 5 Schematic diagram of the structure of the air baffle.

[0042] In the figure: 1, inlet pipe, 11, inlet expansion joint, 2, compression element, 21, impeller, 211, cover plate, 212, cover ring, 22, volute, 22, horizontal center plane, 222, manhole, 223, drainage device, 224, reinforcement rib, 225, large flange, 226, flange, 227, support body, 23, collector, 231, water spray device, 24, air seal, 241, charging port, 242, exhaust port, 243, drainage port, 244, air baffle, 244a, connecting hole, 244b, spiral groove, 245, air baffle shield, 25, pressure plate, 26, locking nut, 3, outlet pipe, 31, outlet expansion joint, 4, vent pipe, 41, vent valve, 5, bearing seat, 51, main shaft, 511, shaft sleeve, 52, end cover, 6, coupling, 7, driver. DETAILED DESCRIPTION

[0043] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0044] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0045] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0046] like Figures 1 to 5 As shown, a small temperature rise centrifugal steam compression device includes a compression element 2 and a driver 7. The inlet and outlet of the compression element 2 are both connected to the inlet pipe 1 and the outlet pipe 3. A vent pipe 4 is provided between the inlet pipe 1 and the outlet pipe 3, and a vent valve 41 is provided on the vent pipe 4. The temperature rise of steam after passing through the compression element 2 is less than 10°C. The compression element 2 includes a volute 22 and an impeller 21 arranged in the volute 22. The driver 7 is connected to the impeller 21 through a main shaft 51 and drives the impeller 21 to rotate. The volute 22 is supported by a support body 227, and the connection point between the support body 227 and the volute 22 is consistent with the height of the center of the main shaft 51.

[0047] In the present invention, the temperature rise of steam after passing through the compression element 2 is less than 10°C, which belongs to the small temperature rise range. To achieve this, a relatively low speed of the impeller 21 can be achieved. Since the speed of the impeller 21 is relatively low, there is no need to use a gearbox to increase the speed. The impeller 21 can be directly connected to the driver 7. In this way, the intermediate gearbox is omitted, the complexity of the structure and the manufacturing cost are reduced, and the maintenance cost is also reduced. The lower speed of the impeller 21 also reduces the noise of the compression element 2 during operation. In the present invention, the volute 22 is supported by a support body 227, and the support body 227 is connected to the equipment foundation so that the position of the support body 227 remains fixed; the support body 227 is supported at a position on the volute 22 that is consistent with the center height of the main shaft 51 (the horizontal center plane 221 of the volute 22), while the rest of the position on the volute 22 is in a suspended state (not supported). This has the advantage that when the volute 22 is deformed by heat, the deformation of the volute 22 diffuses radially from the axis to the surroundings, while the axis position of the volute 22 remains almost unchanged. That is to say, even when the volute 22 is thermally deformed, the axis position of the volute 22 always remains concentric with the main shaft 51, so that the main shaft 51 will not have eccentric contact with the sealing component on the volute 22, thereby avoiding severe unilateral wear of the sealing component and causing a decrease in sealing performance, thereby effectively preventing steam leakage.

[0048] In this embodiment, four support bodies 227 are provided in total, two support bodies 227 are distributed on each side of the volute 22 , and the two support bodies 227 on each side are respectively located on both sides of the center of the volute 22 .

[0049] When the device is in operation, steam is introduced from the inlet pipe 1, and the steam is discharged from the outlet pipe 3 after being pressurized by the compression element 2; when the operating condition of the compression element 2 is close to the surge line, the vent valve 41 is opened and the opening of the vent valve 41 is adjusted, and part of the steam discharged from the outlet pipe 3 flows back to the inlet of the compression element 2 through the vent pipe 4 and the inlet pipe 1 to reduce the surge of the compression element 2.

[0050] An inlet expansion joint 11 is provided on the inlet pipe 1, and an outlet expansion joint 31 is provided on the outlet pipe 3. The inlet expansion joint 11 and the outlet expansion joint 31 are both used to offset the axial expansion and contraction displacement of the pipe.

[0051] The impeller 21 is a core component of the compression element 2. In this embodiment, the impeller 21 is a closed, three-dimensional curved blade welded impeller 21, which reduces the manufacturing cost of the impeller 21 while ensuring the efficient aerodynamic performance of the impeller 21.

[0052] Among them, the diameter and speed of the impeller are calculated according to the steam inlet volume and pressure ratio. The calculation formula of the impeller speed n is as follows:

[0053] ;

[0054] Where n is the impeller speed; is the flow coefficient, ranging from 0.05 to 0.10; is the circumferential speed of the impeller, in (m / s); is the steam intake amount.

[0055] The calculation formula of the impeller diameter D2 is as follows:

[0056] .

[0057] Among them, the circumferential speed of the impeller The calculation formula is as follows:

[0058] ;

[0059] In the formula, is the energy head, in (J / kg); is the energy head coefficient, ranging from 0.4 to 0.7;

[0060] Energy Head The calculation formula is as follows:

[0061] ;

[0062] Wherein, ε is the pressure ratio; σ is the exponential coefficient, which is a dimensionless empirical value. In this embodiment, the exponential coefficient σ is 3.32; T1 is the inlet steam temperature; is the gas constant, and its unit is (J / kg·K).

[0063] In this embodiment, the driver 7 is a variable frequency motor. The output shaft of the variable frequency motor is connected to the main shaft 51 through the coupling 6. The variable frequency motor has a large speed adjustment range, which can make the compression element 2 run at different speeds, greatly improving the adjustment range of the equipment and meeting the stable operation within the load range of 30-100%.

[0064] A collector 23 is provided at the inlet of the volute 22, and a water spray device 231 for cooling the steam is provided on the collector 23. The collector 23 is a cylindrical structure, and the diameter of the end of the collector 23 away from the impeller 21 is larger, and the diameter of the other end is smaller. The steam enters the volute 22 through the collector 23. When the steam from the inlet pipe 1 passes through the collector 23, the water spray device 231 is used to spray water and cool the steam, which can effectively control and adjust the steam inlet temperature, prevent steam from overheating, and ensure the safe operation of the equipment and system.

[0065] Specifically, when the steam is sprayed with water to reduce the temperature through the water spray device, the calculation formula for the cooling water volume d is as follows:

[0066] d =((h2-h1) / η+ h1- h2') ×D×0.95 / (h2'-hs);

[0067] Wherein, h1 is the enthalpy of inlet steam, h2 is the enthalpy of outlet steam, h2' is the enthalpy of outlet saturated steam, η is the adiabatic efficiency, hs is the enthalpy of cooling water; D is the steam evaporation amount.

[0068] It is worth mentioning that the enthalpy value h2 of the outlet steam is the enthalpy value of the outlet steam before being cooled by water spraying, and the outlet steam is in a superheated state at this time; the enthalpy value h2' of the outlet saturated steam is the enthalpy value of the outlet steam after reaching a saturated state after water spraying.

[0069] The impeller 21 is connected to the driver 7 via a main shaft 51. The volute 22 is provided with a main shaft 51 hole through which the main shaft 51 can pass. An air seal 24 is provided on the outside of the main shaft 51 hole. The air seal 24 is annular, and the main shaft 51 passes through the air seal 24. The air seal 24 is fixedly connected to the volute 22. The inside of the air seal 24 adopts a carbon ring seal or a labyrinth seal to cooperate with the main shaft 51.

[0070] The gas seal 24 is provided with an air filling port 241, an air extraction port 242 and a water discharge port 243, which all penetrate the inner surface of the gas seal 24, and the water discharge port 243 is located at the lower side of the gas seal 24; when the internal pressure of the compression element 2 is lower than the atmospheric pressure, clean steam is filled into the air filling port 241 of the gas seal 24, and the pressure of the filled steam is 10-20 kPa higher than the outlet steam pressure of the compression element 2; this can prevent the outside atmosphere from entering the compression element 2 through the fitting between the gas seal 24 and the main shaft 51. When the internal pressure of the compression element 2 is greater than the atmospheric pressure, the inner side of the shaft seal is evacuated through the air extraction port 242, and the extracted steam is led to the inlet pipe 1, or the steam is led to the non-condensable gas treatment tank through a vacuum pump. The condensed water leaked to the gas seal 24 can be discharged outward through the water discharge port 243.

[0071] Among them, a small flange 226 is provided on the outside of the main shaft 51 hole, and the gas seal 24 is fixedly connected to the small flange 226 by bolts. A connecting hole 244a is provided at the center of the hub of the impeller 21. The end of the main shaft 51 away from the driver 7 is the connecting end, which passes through the connecting hole 244a on the impeller 21. The connecting end of the main shaft 51 is fastened to the impeller 21 through the pressure plate 25 and the locking nut 26. The two end surfaces of the hub of the impeller 21 are respectively provided with a cover plate 211 and a cover ring 212. The cover plate 211 and the cover plate 212 are fixedly connected to the hub of the impeller 21 by screws. A convex ring structure corresponding to the cover ring 212 is provided on the connecting end of the main shaft 51. The cover ring 212 presses the convex ring structure to improve the reliability of the connection between the impeller 21 and the main shaft 51.

[0072] The main shaft 51 is installed on the bearing seat 5, and an air baffle plate 244 is sleeved on the main shaft 51. The air baffle plate 244 is located between the air seal 24 and the bearing seat 5. The air baffle plate 244 is coaxially arranged with the main shaft 51, and the air baffle plate 244 is located on one side of the air seal 24. A plurality of spiral grooves 244b are provided on the side of the air baffle plate 24 close to the air seal 24. The rotation direction of the spiral grooves 244b is consistent with the rotation direction of the main shaft 51, and the spiral grooves 244b are distributed on the air baffle plate 244 in a circular array; an air baffle plate shield 245 is provided on the periphery of the air baffle plate 244, and the lower end of the air baffle shield 245 extends to the drain port 243 on the air seal 24.

[0073] The air baffle 244 is annular and is composed of two semi-annular structures, each of which is provided with a corresponding connection hole 244a, and the two semi-annular structures are connected by connecting screws so that the two semi-annular structures are combined to form a complete air baffle 244. The air baffle 244 is tightly connected to the main shaft 51 and rotates with the rotation of the main shaft 51.

[0074] The air baffle shield 245 is cylindrical and connected to the outer circumference of the air seal 24. The air baffle 244 is used to prevent the steam leaking from the matching position of the air seal 24 and the main shaft 51 from axially entering the bearing seat 5 and affecting the safe operation of the bearing. The main shaft 51 will drive the air baffle 244 to rotate during the rotation process. The spiral groove 244b set on the air baffle 244 can guide and discharge the leaked steam or condensed water. The leaked condensed water can be thrown to the inner surface of the air baffle shield 245 through the action of the spiral groove 244b. The condensed water will accumulate at the bottom of the air baffle shield 245 and be discharged outward through the drain port 243.

[0075] The main shaft 51 is mounted on the bearing seat 5, and the flexible rotation of the main shaft 51 is ensured by the bearing seat 5. An end cover 52 is provided at the end of the bearing seat 5, and the main shaft 51 passes through the end cover 52. A labyrinth seal mechanism is provided at the mating point between the end cover 52 and the main shaft 51, and the end cover 52 is sealed with the main shaft 51 through the labyrinth seal mechanism, which can prevent the leaked steam from entering the bearing seat 5.

[0076] A drainage device 223 is provided at the lower end of the volute 22. The accumulated water in the volute 22 will accumulate at the lower end of the volute 22, and the accumulated water can be discharged through the drainage device 223.

[0077] A manhole 222 is also provided on the outer side of the volute 22. The manhole 222 can be opened to allow maintenance personnel to enter the volute 22 and perform maintenance on the interior.

[0078] The volute 22 is provided with reinforcing ribs 224 for enhancing the strength of the volute 22. A large flange 225 is provided on the side of the volute 22 close to the inlet, and the inner diameter of the large flange 225 is larger than the outer diameter of the impeller 21. The impeller 21 can be installed inside the volute 22 through the large flange 225, which is convenient for equipment maintenance and loading and unloading.

[0079] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A small temperature rise centrifugal steam compression device, characterized in that: It includes a compression element and a driver. The inlet and outlet of the compression element are connected to the inlet pipe and the outlet pipe. A vent pipe is provided between the inlet pipe and the outlet pipe. A vent valve is provided on the vent pipe. The temperature rise of steam after passing through the compression element is less than 10°C. The compression element includes a volute and an impeller disposed in the volute, the driver is connected to the impeller through a main shaft and drives the impeller to rotate; the volute is supported by a support body, and the connection point between the support body and the volute is consistent with the height of the center of the main shaft; The diameter and speed of the impeller are calculated based on the steam inlet volume and pressure ratio. The calculation formula for the impeller speed n is as follows: ； Where n is the impeller speed, is the flow coefficient, is the circumferential speed of the impeller, is the steam intake; The calculation formula of the impeller diameter D2 is as follows: ； Among them, the circumferential speed of the impeller The calculation formula is as follows: ； In the formula, For the energy head, is the energy head coefficient; Energy Head The calculation formula is as follows: ； In the formula, ε is the pressure ratio, σ is the exponential coefficient, T1 is the inlet steam temperature, is the gas constant.

2. The small temperature rise centrifugal steam compression device according to claim 1, characterized in that: The driver is a variable frequency motor.

3. The small temperature rise centrifugal steam compression device according to claim 1, characterized in that: A collector is provided at the inlet of the volute, and a water spraying device for cooling the steam is provided on the collector.

4. The small temperature rise centrifugal steam compression device according to claim 3, characterized in that: When the steam is cooled by spraying water through a water spray device, the calculation formula for the cooling water volume d is as follows: d =((h2-h1) / η+ h1- h2') ×D×0.95 / (h2'-hs); Among them, h1 is the enthalpy of inlet steam, h2 is the enthalpy of outlet steam, h2' is the enthalpy of outlet saturated steam, η is the adiabatic efficiency, hs is the enthalpy of cooling water; D is the steam evaporation amount.

5. The small temperature rise centrifugal steam compression device according to claim 1, characterized in that: When the operating condition of the compression element is close to the surge line, open the vent valve and adjust the opening of the vent valve. Part of the steam discharged from the outlet pipe flows back to the inlet of the compression element through the vent pipe and the inlet pipe to reduce the surge of the compression element.

6. The small temperature rise centrifugal steam compression device according to claim 1, characterized in that: The impeller and the driver are connected through the main shaft, and the volute is provided with a main shaft hole for the main shaft to pass through; an air seal is provided on the outside of the main shaft hole, and the air seal is annular, and the main shaft passes through the air seal, and the air seal is fixedly connected to the volute; The air seal is provided with an inflation port, an air extraction port and a drainage port, which all penetrate the inner surface of the air seal, and the drainage port is located at the lower side of the air seal; When the internal pressure of the compression element is lower than the atmospheric pressure, clean steam is charged into the charging port of the gas seal, and the charging steam pressure is 10-20kPa higher than the outlet steam pressure of the compression element; When the internal pressure of the compression element is greater than the atmospheric pressure, the inside of the gas seal is evacuated through the evacuation port, and the evacuated steam is led to the inlet pipe.

7. The small temperature rise centrifugal steam compression device according to claim 1, characterized in that: The main shaft is installed on the bearing seat, and an air baffle is sleeved on the main shaft. The air baffle is located between the air seal and the bearing seat. The air baffle is coaxially arranged with the main shaft, and the air baffle is located on one side of the air seal. A plurality of spiral grooves are provided on the side of the air baffle close to the air seal, and the rotation direction of the spiral grooves is consistent with the rotation direction of the main shaft. The spiral grooves are distributed on the air baffle in a circular array; an air baffle shield is provided on the periphery of the air baffle, and the lower end of the air baffle shield extends to the drain outlet on the air seal.

8. The small temperature rise centrifugal steam compression device according to claim 1, characterized in that: A drainage device is provided at the lower end of the volute.

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