Water vapor compression apparatus, control method thereof, and water vapor circulation system

Abstract

The present application relates to a kind of water vapor compression equipment and its control method and water vapor circulation system, water vapor compression equipment includes: first compression part, for compressing water vapor;Second compression part, with first compression part by intermediate flow path connection and be configured to compress after the water vapor compressed by first compression part;First cooling water vapor flow path, with intermediate flow path communication, to intermediate flow path transport cooling water vapor for reducing the temperature of water vapor inhaled by second compression part;Temperature detection component, be in intermediate flow path, to detect the temperature of water vapor transported to second compression part;First control valve, be in first cooling water vapor flow path;Controller, with temperature detection component and first control valve signal connection respectively, and be configured to adjust the opening of first control valve according to the temperature detected by temperature detection component, to make the temperature of water vapor inhaled by second compression part higher than saturation temperature.

Description

Technical Field

[0001] This invention relates to the field of compressors, and more specifically, to a steam compression device, its control method, and a steam circulation system. Background Technology

[0002] Steam is widely used in various industrial production processes and is an indispensable power source for modern industry. Currently, steam is mostly produced by various types of boilers, but electric boilers, gas boilers, and coal-fired boilers all have significant drawbacks. Their energy utilization efficiency is low, and coal-fired boilers may also pollute the atmosphere. After the country clearly proposed the energy conservation and emission reduction goals of "carbon peaking" and "carbon neutrality," energy utilization efficiency has become an issue that cannot be ignored. Mechanical steam recompression is a highly efficient and energy-saving technology. It can recompress the low-temperature, low-pressure steam produced by a heat pump to produce steam with the temperature and pressure required by the project. It is widely used in food processing, chemical industry, paper industry, salt fields, pharmaceuticals, and seawater desalination. Heat pumps extract heat from the air source and output steam at a certain temperature and pressure, far exceeding the energy utilization efficiency of boilers.

[0003] A steam compressor is the core component of a mechanical vapor recompression system. It pressurizes and heats low-pressure or low-temperature steam to meet the temperature and pressure requirements of a process or engineering project. Currently, there are three main types of steam compressors: centrifugal steam compressors, screw steam compressors, and Roots steam compressors. Screw and Roots steam compressors are positive displacement compressors with relatively small capacities, making them unsuitable for applications requiring large flow rates of steam. Centrifugal steam compressors have large capacities but low compression ratios. When producing high-temperature, high-pressure steam, multi-stage compression technology is required. In multi-stage compression systems, the exhaust temperature of each stage is very high, resulting in significant exhaust superheat. This increases the power consumption of each compression stage and also raises the temperature of the motor rotor and stator, increasing the difficulty of cooling the compressor motor. Summary of the Invention

[0004] The present invention aims to provide a steam compression device and its control method and steam circulation system to improve the problems of high energy consumption of the compression section of the compressor and high temperature of the motor rotor and stator in the prior art.

[0005] According to one aspect of the present invention, a water vapor compression device is provided, comprising, in some embodiments:

[0006] The first compression section is used to compress water vapor;

[0007] The second compression section is connected to the first compression section via an intermediate flow path and is configured to compress the water vapor compressed by the first compression section.

[0008] The first cooling water vapor flow path is connected to the intermediate flow path to deliver cooling water vapor to the intermediate flow path to reduce the temperature of the water vapor drawn into the second compression section;

[0009] A temperature detection component is provided in the intermediate flow path to detect the temperature of the water vapor supplied to the second compression section;

[0010] The first control valve is located in the first cooling water vapor flow path;

[0011] The controller is signal-connected to the temperature detection component and the first control valve, respectively, and is configured to adjust the opening of the first control valve according to the temperature detected by the temperature detection component, so that the temperature of the water vapor drawn into the second compression section is higher than the saturation temperature.

[0012] In some embodiments, the water vapor compression device further includes a pressure detection component disposed in an intermediate flow path, and the controller is signal-connected to the pressure detection component and configured to calculate the saturation temperature of the water vapor in the intermediate flow path based on the pressure detected by the pressure detection component.

[0013] In some embodiments,

[0014] The controller is also configured to calculate the superheat T of water vapor in the intermediate flow path. 过热度 And in T 过热度 With target overheat T 目标过热度 When the superheat difference ΔT between the two values ​​is greater than a predetermined value, the opening of the first control valve is increased.

[0015] in,

[0016] △T=T 过热度 -T 目标过热度 ;

[0017] Superheat T 过热度 = Temperature detected by the temperature sensing component - Saturation temperature.

[0018] In some embodiments, the increment of the opening of the first control valve is ΔD = A*ΔT1 + B*(ΔT1 - ΔT2);

[0019] Where A and B are both constants;

[0020] The opening degree is the ratio of the valve's flow area to its flow area in the fully open state.

[0021] △T1 is the superheat difference △T of the first control valve in the current adjustment cycle;

[0022] △T2 is the superheat difference △T in the previous adjustment cycle of the first control valve.

[0023] △T represents T 过热度 and T目标过热度 The numerical value of the difference.

[0024] In some embodiments, in the direction of water vapor flow in the intermediate flow path, the first cooling water vapor flow path is located upstream of the pressure sensing component.

[0025] In some embodiments, in the direction of water vapor flow in the intermediate flow path, the first cooling water vapor flow path is located upstream of the temperature sensing element.

[0026] In some embodiments, the steam compression device further includes a supply unit connected to the air inlet of the first compression unit to supply cooling water vapor to be compressed to the first compression unit, the supply unit being in communication with the first cooling water vapor flow path to provide cooling water vapor to the first cooling water vapor flow path.

[0027] In some embodiments, the water vapor compression device further includes:

[0028] The cooling device includes an inlet connected to a cooling water vapor supply unit and an outlet connected to a first cooling water vapor flow path.

[0029] In some embodiments, the water vapor compression device includes:

[0030] The air inlet is used to introduce water vapor to be compressed.

[0031] The air outlet is used to output compressed water vapor;

[0032] The second cooling water vapor flow path is connected to the air outlet to adjust the temperature of the water vapor output from the air outlet;

[0033] The second control valve is installed in the second cooling water vapor flow path to regulate the flow rate of the second cooling water vapor flow path.

[0034] In some embodiments, the outlet of the second cooling water vapor flow path is connected to the water vapor flow path between the compression section and the outlet, which is closest to the outlet on the water vapor flow path between the inlet and the outlet.

[0035] According to another aspect of the present invention, a steam circulation system is also provided, which in some embodiments includes the steam compression device described above.

[0036] According to another aspect of the present invention, a control method for the above-described steam compression device is also provided, which, in some embodiments, includes:

[0037] Obtain the temperature of the water vapor supplied to the second compression section;

[0038] The opening of the first control valve is adjusted according to the temperature of the water vapor so that the temperature of the water vapor drawn into the second compression section is higher than the saturation temperature.

[0039] In some embodiments, the control method further includes:

[0040] Obtain the pressure of water vapor in the intermediate flow path;

[0041] The saturation temperature is calculated based on the pressure of the water vapor in the intermediate flow path.

[0042] In some embodiments, the control method further includes:

[0043] Calculate the superheat T of water vapor in the intermediate flow path. 过热度 Overheating T 过热度 = Temperature detected by the temperature sensing component - Saturation temperature;

[0044] Calculate T 过热度 With target overheat T 目标过热度 The difference in superheat between them is ΔT;

[0045] If the temperature difference ΔT is greater than the predetermined value, the opening of the first control valve will be increased.

[0046] In some embodiments, the increment of the opening of the first control valve is ΔD = A*ΔT1 + B*(ΔT1 - ΔT2).

[0047] Where A and B are both constants;

[0048] The opening degree is the ratio of the valve's flow area to its flow area in the fully open state.

[0049] △T1 is the superheat difference △T of the first control valve in the current adjustment cycle;

[0050] △T2 is the superheat difference △T in the previous adjustment cycle of the first control valve.

[0051] △T represents T 过热度 and T 目标过热度 The numerical value of the difference.

[0052] The technical solution of this application utilizes cooling water vapor supplied through a first cooling water vapor flow path to the intermediate flow path to lower the temperature of the water vapor drawn into the second compression section. This improves upon the problems of high energy consumption and high temperatures of the motor rotor and stator in existing compressors. Furthermore, by controlling the amount of cooling water vapor added to the intermediate flow path, it ensures that the water vapor drawn into the second compression section is entirely dry, saturated gas without liquid, preventing the water vapor from carrying liquid and avoiding wet compression, thus protecting the long-term reliability of the centrifugal compressor.

[0053] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A schematic diagram of the structure of a compression device according to an embodiment of the present invention is shown.

[0056] In the diagram: 1. First compression section; 2. Second compression section; 3. Pressure detection component; 4. Temperature detection component; 5. Intermediate flow path; 6. First cooling water vapor flow path; 7. First control valve; 8. Pump; 9. Cooling device; 10. Supply section; 11. Third compression section; 12. Second cooling water vapor flow path; 13. Second control valve. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] like Figure 1 As shown, the water vapor compression device of this embodiment includes a first compression section 1, a second compression section 2, and a first cooling water vapor flow path 6. The second compression section 2 is connected to the first compression section 1 via an intermediate flow path 5 and is configured to compress the water vapor compressed by the first compression section 1. The first cooling water vapor flow path 6 communicates with the intermediate flow path 5 to reduce the temperature of the water vapor drawn into the second compression section 2. The intermediate flow path 5 includes an exhaust port of the first compression section 1 and an intake port of the second compression section 2.

[0059] In this embodiment, an appropriate amount of cooling water vapor is added to the intermediate flow path 6 after the exhaust port of the first compression section 1 to reduce the temperature of the water vapor, thereby lowering the temperature of the water vapor entering the second compression section 2, reducing the power consumption of the second compression section 2, and thus reducing the overall power consumption of the water vapor compression device. The decrease in exhaust temperature also reduces the difficulty of cooling the motor of the water vapor compression device. Furthermore, the cooling water vapor added to the intermediate flow path 6 can increase the compressed gas output of the water vapor after mixing and vaporization with the compressed water vapor.

[0060] In some embodiments, the steam compression device includes a centrifugal compression device. Each stage of the centrifugal compression device includes a centrifugal impeller.

[0061] In some embodiments, the water vapor further includes a temperature detection component 4, a first control valve 7, and a controller. The temperature detection component 4 is disposed in the intermediate flow path 5; the first control valve 7 is disposed in the first cooling water vapor flow path 6; the controller is signal-connected to the temperature detection component 4 and the first control valve 7 respectively, and is configured to adjust the opening of the first control valve 7 according to the temperature detected by the temperature detection component 4, so that the temperature of the water vapor drawn into the second compression section 2 is higher than the saturation temperature.

[0062] If the water vapor drawn in by the steam contains liquid, it will cause wet compression and damage the steam impeller. By controlling the amount of cooling water vapor added in the intermediate flow path 5, it is ensured that the water vapor drawn in by the second compression section 2 is dry saturated gas without liquid, preventing the water vapor drawn in by the second compression section 2 from carrying liquid, avoiding wet compression, and protecting the long-term reliability of the centrifugal steam operation.

[0063] In the flow direction of water vapor in the intermediate flow path 5, the first cooling water vapor flow path 6 is located upstream of the temperature detection component 4. The temperature detection component 4 detects the temperature of the water vapor mixture of cooling water vapor and compressed water vapor.

[0064] In some embodiments, the water vapor compression device further includes a pressure detection component 3 disposed in the intermediate flow path 5, and the controller is signal-connected to the pressure detection component 3 and configured to calculate the saturation temperature of the water vapor in the intermediate flow path 5 based on the pressure detected by the pressure detection component 3.

[0065] In the flow direction of water vapor in the intermediate flow path 5, the first cooling water vapor flow path 6 is located upstream of the pressure detection component 3. The pressure detection component 3 detects the pressure of the water vapor mixed with the cooling water vapor.

[0066] In some embodiments, the steam compression device further includes an inlet, an outlet, a third compression section 11, and a second control valve 13. The inlet is used to introduce steam to be compressed; the outlet is used to output compressed steam; the third compression section 11 is the compression section closest to the outlet in the flow direction of steam from the inlet to the outlet; the second cooling steam flow path 12 is connected to the flow path between the third compression section 11 and the outlet; the second control valve 13 is provided in the second cooling steam flow path 12 to regulate the flow rate of the second cooling steam flow path 12.

[0067] In this embodiment, a second cooling water vapor flow path 12 is also provided between the exhaust port of the last stage compression section of water vapor and the outlet of water vapor. The flow rate of the second cooling water vapor flow path 12 can be adjusted by adjusting the opening of the second control valve 13, thereby adjusting the superheat of the water vapor discharged from the outlet of the water vapor compression device and expanding the application range of water vapor.

[0068] In other embodiments, the compression device includes two or more compression stages, and the second cooling water vapor flow path 12 is connected to the outlet of the last compression stage to output cooling water vapor of a higher degree to regulate the output of water vapor from the outlet of the water vapor compression device.

[0069] Temperature and pressure detection components are also installed in the flow path between the third compression section 11 and the outlet of the steam compressor. The temperature and pressure detection components are located downstream of the second cooling steam flow path 12 in the steam flow path.

[0070] In some embodiments, at least one fourth compression section is provided between the second compression section 2 and the third compression section 11 along the steam flow path between the inlet and outlet of the steam compressor. In other embodiments, the intake ports of some or all of the compression sections are connected to the cooling steam flow path to reduce the intake temperature of the compression section and increase the intake volume, which is beneficial to reducing the operating temperature of the steam compressor and ensuring the stable operation of the steam compressor.

[0071] Pumps 8 are respectively installed in the first cooling water vapor flow path 6 and the second cooling water vapor flow path 12.

[0072] The steam compression device further includes a supply unit 10 connected to the air inlet of the first compression unit 1 to supply the cooling water steam to be compressed to the first compression unit 1. The supply unit 10 is connected to the first cooling water steam flow path 6 to provide the cooling water steam to the first cooling water steam flow path 6.

[0073] The steam compression equipment also includes a cooling device 9, which has an inlet connected to the cooling steam supply unit 10 and an outlet connected to the first cooling steam flow path 6. Steam enters the cooling device 9 from the steam supply unit 10, is cooled by the cooling device 9 to form liquid water, is pressurized by the pump 8 to provide power, and then its flow rate is controlled by the control valve before entering the exhaust pipe of the compression unit to mix with the compressed steam to form saturated steam.

[0074] In this embodiment, a certain amount of cooling water vapor is added to the exhaust pipe of each compression section. The added cooling water vapor mixes with the superheated water vapor after compression to form a dry saturated gas without liquid before entering the next compression section. This reduces the power consumption required by the next compression section and increases the intake volume of the next compression section.

[0075] The controller is also configured to calculate the superheat T of the water vapor in the intermediate flow path 5. 过热度 And in T 过热度 With target overheat T 目标过热度 When the superheat difference ΔT between the two values ​​is greater than a predetermined value, the opening of the first control valve 7 is increased, where the units of superheat and temperature are both degrees Celsius.

[0076] Where, △T=T 过热度 -T 目标过热度 ;

[0077] Superheat T 过热度 = Temperature detected by temperature detection component 4 - saturation temperature.

[0078] The increment of the opening of the first control valve 7 is ΔD = A*ΔT1 + B*(ΔT1 - ΔT2);

[0079] in,

[0080] Both A and B are constants;

[0081] The opening degree is the ratio of the flow area of ​​the valve to the flow area in the fully open state.

[0082] △T1 is the superheat difference △T of the first control valve 7 in the current adjustment cycle;

[0083] △T2 is the superheat difference △T of the first control valve 7 in the previous adjustment cycle.

[0084] △T represents T 过热度 and T 目标过热度 The numerical value of the difference.

[0085] According to another aspect of the present invention, a steam circulation system is also provided, which includes the steam compression device described above.

[0086] According to another aspect of the present invention, a control method for the above-described water vapor compression device is also provided, the control method comprising:

[0087] Obtain the temperature of the water vapor supplied to the second compression unit 2;

[0088] The opening degree of the first control valve 7 is adjusted according to the temperature of the water vapor so that the temperature of the water vapor drawn into the second compression section 2 is higher than the saturation temperature.

[0089] In some embodiments, the control method further includes:

[0090] Obtain the pressure of water vapor in intermediate flow path 5;

[0091] The saturation temperature is calculated based on the pressure of the water vapor in the intermediate flow path 5.

[0092] In some embodiments, the control method further includes:

[0093] Calculate the superheat T of the water vapor in intermediate flow path 5. 过热度 Overheating T 过热度 = Temperature detected by temperature detection component 4 - saturation temperature;

[0094] Calculate T 过热度 With target overheat T 目标过热度 The difference in superheat between them is ΔT;

[0095] If the temperature difference ΔT is greater than the predetermined value, the opening of the first control valve 7 will be increased.

[0096] In some embodiments, the increment of the opening of the first control valve 7 is ΔD = A*ΔT1 + B*(ΔT1 - ΔT2).

[0097] Where A and B are both constants;

[0098] The opening degree is the ratio of the valve's flow area to its flow area in the fully open state.

[0099] △T1 is the superheat difference △T of the first control valve 7 in the current adjustment cycle;

[0100] △T2 is the superheat difference △T of the first control valve 7 in the previous adjustment cycle.

[0101] △T represents T 过热度 and T 目标过热度 The numerical value of the difference.

[0102] In this embodiment, the control method involves setting a temperature detection component 4 and a pressure detection component 3 in the intermediate flow path between two adjacent compression stages to measure the exhaust temperature (T_exhaust) and exhaust pressure (P_exhaust) of each compression stage. The exhaust saturation temperature (T_saturation) is calculated by measuring the exhaust pressure, and then the water vapor exhaust superheat can be calculated. Based on the deviation between the exhaust superheat and the target value, the opening of the first control valve 7 on each cooling pipe is controlled by a certain logic, thereby controlling the water spray volume of each stage to ensure that the water vapor sucked into the next stage of compression is saturated steam, avoiding wet compression of the compressor and wasted power consumption.

[0103] Specifically, the control method in this embodiment includes:

[0104] The control method for pump #8, which is used to supply water to the intermediate flow path between the first compression section 1 and the second compression section 2, is as follows: before the steam compression equipment is started, pump #8 is turned on 60 seconds in advance so as to adjust the superheat of the steam entering the second compression section 2 in time; after the steam compression equipment is stopped, pump #8 is turned off after a delay of 60 seconds so as to continue to supply steam for cooling to the second compression section 2 during the inertial operation phase of the steam compression equipment.

[0105] Control valve control method:

[0106] 1. Upon first power-on, the first control valve 7 performs a reset action, which involves first opening it to 100%, then closing the first control valve 7, and finally reducing the opening of the first control valve 7 to 0.

[0107] 2. After the steam compression equipment is first detected to start, the first control valve 7 opens to 0, and after a delay of 10 seconds, it enters the "exhaust superheat adjustment state". The operation cycle (adjustment cycle) of the control valve opening is adjusted once every T (control valve adjustment cycle) seconds.

[0108] First control valve 7 adjustment target: T 过热度 <T 过热度目标值 +0.5℃.

[0109] The difference in exhaust superheat in the first compression section 1 is ΔT = T 过热度 -T 目标过热度 .

[0110] When the exhaust superheat difference ΔT of the first compression section 1 is less than the predetermined value, the opening of the first control valve 7 does not change, and the predetermined value is 0 to 0.5℃.

[0111] When the exhaust superheat difference ΔT of the first compression section 1 is greater than the predetermined value mentioned above:

[0112] The increment of the opening of the first control valve 7 is ΔD = A*ΔT1 + B*(ΔT1 - ΔT2).

[0113] Where A and B are both constants;

[0114] The opening degree is the ratio of the valve's flow area to its flow area in the fully open state.

[0115] △T1——The superheat difference △T of the first control valve 7 during the current operating cycle (adjustment cycle);

[0116] △T2—The superheat difference △T in the previous operating cycle (regulation cycle) of the first control valve 7.

[0117] △T represents T 过热度 and T 目标过热度 The numerical value of the difference.

[0118] 3. After the water vapor compression equipment is detected to have stopped, the first control valve 7 opens to 0 degrees after a delay of 30 seconds.

[0119] The control methods for pump #2, which supplies steam to the intermediate flow path between the second and third compression sections, pump #3, which supplies steam to the intermediate flow path between the third and fourth compression sections, and pump #4, which supplies steam to the intermediate flow path between the fourth compression section and the outlet of the compression equipment, are the same as those for pump #1. The control methods for the control valves that control the flow rate of steam output by pumps #2, #3, and #4 to the corresponding target positions are similar to those for the first control valve 7; only the superheat target value needs to be adjusted to the corresponding target.

[0120] The above are merely exemplary 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 within the protection scope of the present invention.

Claims

1. A steam compression device, characterized in that, include: The first compression section (1) is used to compress water vapor; The second compression section (2) is connected to the first compression section (1) via an intermediate flow path (5) and is configured to compress the water vapor compressed by the first compression section (1); The first cooling water vapor flow path (6) is connected to the intermediate flow path (5) to deliver cooling water vapor to the intermediate flow path (5) to reduce the temperature of the water vapor drawn in by the second compression section (2); A temperature detection component (4) is provided in the intermediate flow path (5) to detect the temperature of the water vapor supplied to the second compression section (2); The first control valve (7) is located in the first cooling water vapor flow path (6); The controller is signal-connected to the temperature detection component (4) and the first control valve (7) respectively, and is configured to adjust the opening of the first control valve (7) according to the temperature detected by the temperature detection component (4) so ​​that the temperature of the water vapor drawn into the second compression section (2) is higher than the saturation temperature. The water vapor compression device further includes a pressure detection component (3) disposed in the intermediate flow path (5). The controller is signal-connected to the pressure detection component (3) and configured to calculate the saturation temperature of the water vapor in the intermediate flow path (5) based on the pressure detected by the pressure detection component (3). The controller is also configured to calculate the superheat T of the water vapor in the intermediate flow path (5). 过热度 And in the T 过热度 With target overheat T 目标过热度 When the superheat difference ΔT between the two values ​​is greater than a predetermined value, the opening degree of the first control valve (7) is increased. Where, △T = T 过热度 -T 目标过热度 ; The superheat T 过热度 = The temperature detected by the temperature detection component (4) - the saturation temperature.

2. The steam compression device according to claim 1, characterized in that, The increment of the opening of the first control valve (7) is △D = A*△T1 + B*(△T1-△T2); Where A and B are both constants; The opening degree is the ratio of the valve's flow area to its flow area in the fully open state. △T1 is the superheat difference △T of the first control valve (7) during the current adjustment cycle; △T2 is the superheat difference △T of the first control valve (7) in the previous adjustment cycle; △T represents T 过热度 and T 目标过热度 The numerical value of the difference.

3. The steam compression device according to claim 1, characterized in that, In the direction of water vapor flow in the intermediate flow path (5), the first cooling water vapor flow path (6) is located upstream of the pressure detection component (3).

4. The steam compression device according to claim 1, characterized in that, In the direction of water vapor flow in the intermediate flow path (5), the first cooling water vapor flow path (6) is located upstream of the temperature detection component (4).

5. The steam compression device according to claim 1, characterized in that, It also includes a supply unit (10) connected to the air inlet of the first compression unit (1) to supply the cooling water vapor to be compressed to the first compression unit (1), the supply unit (10) being connected to the first cooling water vapor flow path (6) to provide the cooling water vapor to the first cooling water vapor flow path (6).

6. The steam compression device according to claim 5, characterized in that, Also includes: The cooling device (9) includes an inlet connected to the cooling water vapor supply unit (10) and an outlet connected to the first cooling water vapor flow path (6).

7. The steam compression device according to claim 1, characterized in that, include: The air inlet is used to introduce water vapor to be compressed. The air outlet is used to output compressed water vapor; The second cooling water vapor flow path (12) is connected to the air outlet to adjust the temperature of the water vapor output from the air outlet; A second control valve (13) is provided in the second cooling water vapor flow path (12) to regulate the flow rate of the second cooling water vapor flow path (12).

8. The steam compression device according to claim 7, characterized in that, The outlet of the second cooling water vapor flow path (12) is connected to the water vapor flow path between the compression section closest to the outlet and the outlet on the water vapor flow path between the inlet and the outlet.

9. A water vapor circulation system, characterized in that, The steam compression device includes any one of claims 1 to 8.

10. A control method for a steam compression device according to any one of claims 1 to 8, characterized in that, include: Obtain the temperature of the water vapor supplied to the second compression section (2); Adjusting the opening of the first control valve (7) according to the temperature of the water vapor so that the temperature of the water vapor drawn into the second compression section (2) is higher than the saturation temperature.

11. The control method according to claim 10, characterized in that, Also includes: Obtain the pressure of the water vapor in the intermediate flow path (5); The saturation temperature is calculated based on the pressure of the water vapor in the intermediate flow path (5).

12. The control method according to claim 11, characterized in that, Also includes: Calculate the superheat T of the water vapor in the intermediate flow path (5). 过热度 The superheat T 过热度 = The temperature detected by the temperature detection component (4) - the saturation temperature; Calculate the T 过热度 With target overheat T 目标过热度 The difference in superheat between them is ΔT; If the heat difference ΔT is greater than a predetermined value, the opening of the first control valve (7) is increased.

13. The control method according to claim 12, characterized in that, The increment ΔD of increasing the opening of the first control valve (7) is ΔD = A*ΔT1 + B*(ΔT1 - ΔT2). Where A and B are both constants; The opening degree is the ratio of the valve's flow area to its flow area in the fully open state. △T1 is the superheat difference △T of the first control valve (7) during the current adjustment cycle; △T2 is the superheat difference △T of the first control valve (7) in the previous adjustment cycle. △T represents T 过热度 and T 目标过热度 The numerical value of the difference.

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