Vapor compression equipment, cooling control system and control method

Abstract

The invention discloses steam compression equipment, a cooling control system and a control method, and relates to the technical field of compressors, the steam compression equipment comprises a cooling control assembly connected with a liquid storage tank and multiple stages of compression parts sequentially connected in series; the cooling control assembly comprises a main water pump and a plurality of cooling pipelines connected in parallel, the number of the cooling pipelines is the same as that of the compression parts in the multi-stage compression parts, the cooling pipelines correspond to the compression parts in the multi-stage compression parts in a one-to-one mode, an inlet of the main water pump is connected with the liquid storage tank, and an outlet of the main water pump is connected with the cooling pipelines; the outlet pressure value of the main water pump is configured as a target pressure value; the outlet of each stage of compression part is connected with a steam pipeline, and each cooling pipeline is connected with the steam pipeline behind the outlet of the corresponding stage of compression part through a nozzle. Water pressure control in the multiple cooling pipelines can be achieved through one main water pump, steam cooling can be achieved, the equipment cost can be reduced, and the failure rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and in particular to a steam compression device, a cooling control system and a control method. Background Art

[0002] Reducing industrial carbon emissions is a key step in achieving carbon neutrality. To improve energy efficiency, industrial high-temperature heat pumps are used to recover waste heat, generating low-temperature, low-pressure steam. This steam is then compressed into high-temperature, high-pressure steam by a multi-stage steam compressor within the heat pump. Due to the high temperature of the high-temperature, high-pressure steam, the compressor consumes significant power and places high demands on components such as the gearbox and seals at each stage. Therefore, interstage cooling is required for multi-stage steam compressors.

[0003] Prior art interstage cooling methods for multi-stage steam compressors include indirect heat exchange cooling and direct water spray cooling. However, indirect heat exchange cooling requires an external cooling source to remove the heat from the superheated steam, adding additional equipment. Direct water spray cooling typically requires a separate water pump for each stage of the steam compressor, resulting in high equipment costs, complex control, and increased equipment failure rates. Summary of the Invention

[0004] The main purpose of the present invention is to provide a steam compression device, a cooling control system and a control method, aiming to solve the problem of imperfect inter-stage cooling methods of existing multi-stage steam compressors.

[0005] To achieve the above-mentioned objectives, in a first aspect, the steam compression device proposed in the present invention includes: a cooling control component connected to a liquid storage tank, and a multi-stage compression section connected in series in sequence; the cooling control component includes a main water pump and multiple cooling pipes in parallel, the number of the cooling pipes is the same as the number of compression sections in the multi-stage compression section and corresponds one to one, the inlet of the main water pump is connected to the liquid storage tank, and the outlet of the main water pump is connected to the multiple cooling pipes, wherein the outlet pressure value of the main water pump is configured as a target pressure value; the outlet of each stage of the compression section is connected to a steam pipe, and each cooling pipe is connected to the steam pipe after the outlet of the compression section of the corresponding stage through a nozzle.

[0006] Preferably, a flow regulating valve is provided on each of the cooling pipelines, and the flow regulating valve is used to adjust the amount of water mist sprayed by the target nozzle into the connected steam pipeline according to the valve control signal, and the target nozzle is the nozzle connected to the cooling pipeline where the flow regulating valve is located; wherein, the valve control signal of each of the flow regulating valves is obtained according to the actual superheat in the steam pipeline connected to the cooling pipeline where the flow regulating valve is located and the preset superheat.

[0007] Preferably, a temperature sensor and a pressure sensor are provided on the steam pipeline. The temperature sensor and the pressure sensor are respectively used to detect the real-time temperature value and the real-time pressure value in the steam pipeline. A water pump pressure detector is provided at the outlet of the main water pump for detecting the outlet pressure of the main water pump.

[0008] Preferably, a gas-liquid separator is provided on the steam pipeline. In the steam transmission direction between two adjacent compression parts, the gas-liquid separator is located downstream of the nozzle, and the temperature sensor and the pressure sensor on the steam pipeline are both located downstream of the gas-liquid separator.

[0009] In a second aspect, the present invention provides a cooling control system for a steam compression device. The system includes a controller and the steam compression device according to any one of the first aspects. The controller is respectively connected to the main water pump of the steam compression device, the flow regulating valves on each cooling pipeline, the temperature sensors and pressure sensors on each steam pipeline, and the water pump pressure detector. The controller is configured to obtain the actual superheat degree of the steam in each steam pipeline according to the real-time temperature value and the real-time pressure value in each steam pipeline, and obtain the valve control signal of the flow regulating valve corresponding to each steam pipeline according to the magnitude relationship between the actual superheat degree and the preset superheat degree, so as to control the valve opening of each flow regulating valve.

[0010] Preferably, the controller is further configured to adjust the frequency of the main water pump according to the valve control signal of any flow regulating valve and the outlet pressure of the main water pump, so as to control the outlet pressure of the main water pump to be the target pressure value.

[0011] In a third aspect, the present invention provides a cooling control method for a steam compression device, which is applied to the cooling control system of the steam compression device according to any one of the second aspects. The method includes: determining the actual superheat degree of the steam in the steam pipeline according to the real-time temperature value and the real-time pressure value in each steam pipeline; obtaining the valve control signal of the flow regulating valve corresponding to the steam pipeline according to the magnitude relationship between the actual superheat degree and the preset superheat degree; controlling the valve opening of the flow regulating valve corresponding to the steam pipeline according to the valve control signal, so as to control the amount of water mist sprayed by the target nozzle into the steam pipeline, and the target nozzle is the nozzle connected to the cooling pipeline where the flow regulating valve corresponding to the steam pipeline is located.

[0012] Preferably, the preset superheat has a minimum threshold and a maximum threshold. Obtaining a valve control signal for a flow regulating valve corresponding to the steam pipeline according to the magnitude relationship between the actual superheat and the preset superheat includes: obtaining a valve control signal for increasing the valve opening according to the actual superheat being greater than the maximum threshold; obtaining a valve control signal for decreasing the valve opening according to the actual superheat being less than the minimum threshold; and keeping the valve opening unchanged according to the actual superheat being greater than or equal to the minimum threshold and less than or equal to the maximum threshold.

[0013] Preferably, the method further includes: adjusting the frequency of the main water pump according to the valve control signal of any flow regulating valve and the outlet pressure of the main water pump detected by a water pump pressure detector, so as to control the outlet pressure of the main water pump to be a target pressure value.

[0014] Preferably, adjusting the frequency of the main water pump according to the valve control signal and the outlet pressure of the main water pump detected by the water pump pressure detector includes: adjusting the frequency of the main water pump according to the valve control signal and the outlet pressure of the main water pump detected by the water pump pressure detector includes: increasing the frequency of the main water pump until the outlet pressure of the main water pump is the target pressure value according to the valve control signal of any flow regulating valve being for increasing the valve opening; decreasing the frequency of the main water pump until the outlet pressure of the main water pump is the target pressure value according to the valve control signal of any flow regulating valve being for decreasing the valve opening.

[0015] Preferably, the method further includes: determining the acting pressure of the nozzle according to the particle size required for the water mist ejected from the nozzle to evaporate; determining the target pressure value according to the acting pressure of the nozzle and the maximum steam pressure value after being compressed by a multi-stage compression part.

[0016] Generally speaking, the present invention has at least the following beneficial effects:

[0017] In the technical solution of the present invention, the steam compression device includes a main water pump and multiple parallel cooling pipelines. The outlet pressure value of the main water pump is configured as the target pressure value. The water pressure in multiple cooling pipelines can be controlled by one main water pump, and then the amount of water mist sprayed by the nozzle into the steam pipeline can be controlled to control the superheat of the steam entering the next compression part in the steam pipeline, which can not only achieve steam cooling but also reduce equipment costs and reduce the failure rate. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0019] Figure 1 Schematic diagram showing the structure of a steam compression device according to an embodiment of the present invention;

[0020] Figure 2 Schematic diagram showing the water spraying cooling of a steam pipeline according to an embodiment of the present invention;

[0021] Figure 3 Another schematic diagram showing the structure of a steam compression device according to an embodiment of the present invention;

[0022] Figure 4 Schematic diagram showing the structure of a four-stage steam compression device according to an embodiment of the present invention;

[0023] Figure 5 Schematic diagram showing the structure of a cooling control system of a steam compression device according to an embodiment of the present invention;

[0024] Figure 6 Flowchart showing the steps of a cooling control method of a steam compression device according to an embodiment of the present invention;

[0025] Figure 7 Logic diagram showing a cooling control method of a steam compression device according to an embodiment of the present invention.

[0026] Explanation of the reference numerals in the drawings:

[0027]

[0028] The realization, functional features and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed implementation manners

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0030] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the attached drawings). If the specific posture changes, the directional indications will also change accordingly.

[0031] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0032] In the present invention, unless otherwise clearly specified and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In addition, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0034] The steam compression equipment in the embodiments of the present application, such as a multi-stage steam compressor, is a device used to compress steam and improve the efficiency of the system through compression at multiple levels. It usually consists of two or more compression stages, and each stage has a compression chamber and a working medium (usually steam). In each stage, the steam is compressed, cooled by a condenser, expanded by a pressure reducing valve, and then enters the next stage for further compression. For example, after using an industrial high-temperature heat pump to recover waste heat and generate low-temperature and low-pressure water steam, the low-temperature and low-pressure water steam is compressed into high-temperature and high-pressure water steam by a multi-stage water steam compressor in the heat pump to improve the energy utilization efficiency.

[0035] However, the exhaust temperature of compressed water vapor is very high, resulting in a high degree of superheat. Superheat refers to the difference between the saturated steam temperature and the saturated steam temperature, meaning that the steam temperature is higher than it should be. Superheat is often used to describe the state of steam, reflecting its thermal energy level and thermodynamic properties. High superheat results in high compression power consumption and places high demands on components such as the gearbox and seals of each stage of the compressor. Therefore, interstage cooling is necessary for multi-stage steam compressors.

[0036] Interstage cooling methods for multi-stage steam compressors include indirect heat exchange and direct water spray. However, indirect heat exchange requires an external cooling source to remove the heat from the superheated steam, adding additional equipment and underutilizing the sensible heat of the superheated steam. Direct water spray typically requires a separate water pump for each stage of the steam compressor, resulting in high equipment costs, complex control, and increased equipment failure rates.

[0037] Furthermore, direct water spray cooling involves injecting water mist between the stages of a multi-stage steam compressor. This requires time for the mist to evaporate completely. If the mist fails to completely evaporate, the remaining droplets can cause liquid hammering on the impeller, impacting reliability and shortening service life. Whether the spray completely evaporates depends primarily on the spray particle size and the length of the spray pipe. For highly integrated multi-stage compressors with limited interstage distances, it's likely that the calculated water volume won't be fully evaporated to achieve the target superheat. Increasing the water volume will result in excess water being carried out, further increasing the amount of excess water, which can affect the reliability of the compression equipment.

[0038] To address the above-mentioned issues, embodiments of the present application provide a steam compression device, a cooling control system, and a control method. The cooling control assembly of the steam compression device in this embodiment includes a main water pump and multiple cooling pipelines. The outlet pressure value of the main water pump is configured as a target pressure value. The main water pump can be used to control the water pressure in multiple cooling pipelines, thereby controlling the amount of water mist sprayed into the steam pipeline by the nozzle to control the superheat of the steam entering the next compression section in the steam pipeline. This can not only achieve steam cooling, but also reduce equipment costs and lower the failure rate.

[0039] Figure 1 FIG2 is a schematic diagram showing the structure of a steam compression device according to an embodiment of the present invention. Figure 1, in the embodiments of the present invention, the vapor compression device 10 includes: a cooling control component 102 connected to a liquid storage tank 101, and a multi-stage compression section connected in series in sequence; the cooling control component 102 includes a main water pump 103 and multiple parallel cooling pipelines 104, the number of cooling pipelines is the same as and corresponds one-to-one with the number of compression sections in the multi-stage compression section, the inlet of the main water pump 103 is connected to the liquid storage tank 101, the outlet of the main water pump 103 is connected to multiple cooling pipelines 104, wherein, the outlet pressure value of the main water pump 103 is configured as a target pressure value; the outlet of each stage of the compression section is connected with a steam pipeline 105, and each cooling pipeline 104 is respectively connected to the steam pipeline 105 after the outlet of the corresponding stage of the compression section through a nozzle 106.

[0040] The liquid storage tank 101 stores a working medium for cooling, which is used to provide a refrigerant. For the convenience of description, in this embodiment, the working medium is taken as water as an example, that is, the liquid storage tank 101 stores cooling water, and the vapor compression device compresses water vapor.

[0041] Reference Figure 1 , the multi-stage compression section includes a first-stage compression section A, a second-stage compression section B, a third-stage compression section C... an N-stage compression section, N is a positive integer, the first-stage compression section A, the second-stage compression section B, the third-stage compression section C... the N-stage compression section are connected in series in sequence to achieve step-by-step compression. The inlet of the first-stage compression section A sucks in low-temperature and low-pressure steam with industrial waste heat, the first-stage compression section A performs a first-stage compression on the low-temperature and low-pressure steam, and the steam flowing out after the first-stage compression flows into the second-stage compression section B again. The second-stage compression section B performs a further compression on the steam after the first-stage compression, and the steam flowing out after the second-stage compression. After the low-temperature and low-pressure steam passes through multi-stage compression, finally, high-temperature and high-pressure steam is output to the user end through the outlet of the N-stage compression section, and the temperature and pressure of the output high-temperature and high-pressure steam are determined by the user's requirements.

[0042] The inlet of the main water pump 103 is connected to the liquid storage tank 101, the outlet of the main water pump 103 is connected to multiple cooling pipelines 104, the multiple cooling pipelines 104 are connected in parallel, the number of cooling pipelines 104 is the same as and corresponds one-to-one with the number of compression sections in the multi-stage compression section. If the multi-stage compression section includes an N-stage compression section, then the cooling pipelines 104 include N cooling pipelines, which can achieve the cooling of the steam after each stage of compression.

[0043] The outlet of each stage of the compression section is connected with a steam pipeline for transporting the compressed steam. Each cooling pipeline 104 is respectively connected to the steam pipeline 105 after the outlet of the corresponding stage of the compression section through a nozzle 106. Furthermore, a refrigerant transmission direction of the liquid storage tank, the main water pump 103, the cooling pipelines 104, the nozzles 106 and the steam pipelines 105 can be formed, and the effect of reducing the temperature in each steam pipeline 105 by using the refrigerant in the liquid storage tank can be achieved.

[0044] Considering that the exhaust temperature after water vapor compression is very high and the superheat degree is very large. For example, 0.047 MPa saturated water vapor is compressed to 0.93 MPa in one stage, that is, the pressure ratio is 1.96. At this time, the exhaust temperature is 155 °C. Assuming the isentropic efficiency is 0.82, the exhaust superheat degree is 57 K. If it is directly sent to the second-stage compression part and compressed directly to 1.82 MPa, the exhaust temperature is 245 °C and the exhaust superheat degree is 127 K. The excessive superheat degree will lead to large compression power consumption. Working at high temperatures requires higher material requirements for components such as the gearbox and seals of the compressor. Therefore, in this embodiment, multiple cooling pipelines 104 are respectively connected to the steam pipeline 105 through nozzles 106 to spray water mist into the steam pipeline 105 through the nozzles 106 to achieve the cooling of the water vapor in the steam pipeline 105.

[0045] Figure 2 Fig. shows a schematic diagram of spraying water to cool the steam pipeline according to an embodiment of the present invention. As Figure 2 shown, the flow direction of the water vapor in the steam pipeline 105 is as shown by the dotted arrow (from left to right), and the cooling water mist sprayed by the nozzle 106 is as shown by the solid arrow (from top to bottom), so as to achieve the cooling of the water vapor in the steam pipeline 105.

[0046] Reference Figure 1 , multiple cooling pipelines 104 are respectively connected to a steam pipeline 105 through nozzles 106, and multiple cooling branches can be formed. The number of cooling branches is the same as the number of compression parts in the multi-stage compression part. Each cooling branch includes a cooling pipeline 104, a nozzle 106, and a steam pipeline 105, so as to achieve the independent control of each steam pipeline 105.

[0047] In addition, the outlet pressure value of the main water pump 103 is configured as the target pressure value, which can achieve the constant pressure control of the outlet of the main water pump 103. Each cooling branch does not affect each other, and the flow rate adjustment decoupling between each cooling branch is realized. In the embodiment of the present application, only one main water pump 103 is used to achieve the water supply control of multiple cooling branches, meet the inter-stage temperature cooling requirements of the multi-stage compression equipment, and reduce the equipment cost.

[0048] In an embodiment of the present application, a flow regulating valve 107 is provided on each cooling pipeline 104. The flow regulating valve 107 is used to adjust the amount of water mist sprayed into the connected steam pipeline 105 by the target nozzle according to the valve control signal. The target nozzle is the nozzle 106 connected to the cooling pipeline 104 where the flow regulating valve 107 is located.

[0049] For example, if the flow regulating valve 107 is the flow regulating valve on the cooling pipeline connected to the outlet of the first-stage compression part A, the target nozzle is the nozzle connected to the cooling pipeline connected to the outlet of the first-stage compression part A.

[0050] The valve control signal in the embodiment of the present application can be issued by a controller, which is obtained by the controller based on the comparison between the actual superheat degree in the steam pipeline 105 connected to the cooling pipeline 104 and the preset superheat degree. For example, the actual superheat degree in the steam pipeline 105 between the first-stage compression part A and the second-stage compression part B is ΔT, and the preset superheat degree of the water vapor entering the second-stage compression part B is ΔTset±ε, where ε represents the allowable control accuracy. Then, by comparing the magnitude relationship between ΔT and ΔTset±ε, the controller can obtain the valve control signal to control the flow regulating valve on the cooling pipeline 104 connected to the steam pipeline 105 between the first-stage compression part A and the second-stage compression part B, so as to increase or decrease the superheat degree of the water vapor entering the second-stage compression part B, and make the superheat degree of the water vapor entering the second-stage compression part B within the preset superheat degree range.

[0051] A flow regulating valve 107 is provided on each cooling pipeline 104. The flow regulating valve 107 is used to adjust the amount of water mist sprayed by the target nozzle into the connected steam pipeline 105 according to the valve control signal. Taking the cooling of the steam in the steam pipeline 105 between the first-stage compression part A and the second-stage compression part B as an example, for example, when the actual superheat degree in the steam pipeline 105 between the first-stage compression part A and the second-stage compression part B is greater than the preset superheat degree, it indicates that the temperature in the steam pipeline 105 between the first-stage compression part A and the second-stage compression part B is too high. Then, the valve control signal of the flow regulating valve on the cooling pipeline connected to the outlet of the first-stage compression part A is to increase the valve opening, so as to increase the amount of water mist sprayed by the nozzle 106 into the steam pipeline 105 between the first-stage compression part A and the second-stage compression part B, and realize temperature reduction by increasing the sprayed cooling water mist. Similarly, when the actual superheat degree is less than the preset superheat degree, it indicates that the temperature in the steam pipeline 105 between the first-stage compression part A and the second-stage compression part B is lower than the preset temperature. Then, the valve control signal of the flow regulating valve on the cooling pipeline connected to the outlet of the first-stage compression part A is to decrease the valve opening, so as to reduce the amount of water mist sprayed by the nozzle 106 into the steam pipeline 105 between the first-stage compression part A and the second-stage compression part B, and slow down the temperature reduction speed by reducing the sprayed cooling water mist.

[0052] In this embodiment, the flow regulating valve 107 is used to control the water volume on each cooling pipeline 104. Since the outlet pressure of the total water pump 103 is stabilized at the target pressure value, each flow regulating valve 107 can be independently controlled without mutual influence, thereby increasing the stability of the steam compression device.

[0053] Figure 3 Another structural schematic diagram of a steam compression device according to an embodiment of the present invention is shown. Refer to Figure 3 , a temperature sensor T and a pressure sensor P1 are provided on the steam pipeline 105. The temperature sensor T and the pressure sensor P1 are respectively used to detect the real-time temperature value and the real-time pressure value in the steam pipeline 105.

[0054] Detect the real-time temperature value and real-time pressure value in the steam pipeline 105. The actual superheat degree in the steam pipeline 105 can be calculated by combining with the saturation temperature Tvap under the same pressure, and then the valve control signal of the flow regulating valve corresponding to the steam pipeline can be obtained according to the actual superheat degree and the preset superheat degree.

[0055] A water pump pressure detector P2 is arranged at the outlet of the main water pump 103, which is used to detect the outlet pressure of the main water pump 103, so as to monitor and adjust the outlet pressure of the main water pump 103 to make the outlet pressure of the main water pump 103 be the target pressure value.

[0056] Due to the high integration degree between the multi-stage compression parts and the short inter-stage distance between adjacent two-stage compression parts, in order to prevent the water mist from not being completely vaporized, a vapor-liquid separator 108 is added before entering the inlet of the next-stage compression. Refer to Figure 3 , in the embodiment of the present application, a vapor-liquid separator is arranged on the steam pipeline 105. The vapor-liquid separator 108 is used to separate the liquid droplets in the steam pipeline 105, so that the steam entering the next-stage compression part is liquid-free, and the problem of liquid hammer on the compressor impeller caused by liquid-carrying steam in the related technology can be solved.

[0057] The vapor-liquid separator 108 can also solve the reliability problem of variable working condition operation. For example, the average particle size of the mist droplets sprayed by the nozzle 106 under the rated working condition is between 20 and 50 microns, which can ensure that the mist droplets are completely evaporated within a short inter-stage distance. When the compressor load changes, during the adjustment process of the water injection amount, the acting pressure of the nozzle 106 fluctuates, and the spray particle size also changes accordingly. If the acting pressure decreases and the particle size becomes larger for a while, it is difficult to ensure that the spray is completely evaporated. Therefore, a vapor-liquid separator needs to be added after each stage of the nozzle 106 to buffer the system fluctuations under variable working conditions, so that the steam entering the next-stage compression is still liquid-free, and the reliability of the compressor is improved.

[0058] Among them, in the steam transmission direction between adjacent two-stage compression parts, such as the direction from the first-stage compression part A to the second-stage compression part B, the vapor-liquid separator is located downstream of the nozzle 106. In this way, when the water mist sprayed by the nozzle 106 is not completely evaporated, the unevaporated liquid droplets can be separated.

[0059] The temperature sensor T and the pressure sensor P1 on the steam pipeline 105 are both located downstream of the vapor-liquid separator 108. In this way, the temperature and pressure of the liquid-free steam can be detected, the detection accuracy can be improved, and the cooling control accuracy can be improved.

[0060] Figure 4 Show a structural schematic diagram of a four-stage steam compression device according to an embodiment of the present invention. Refer to Figure 4, in one example, the four-stage steam compression device adopts a single-drive double-parallel-axis four-stage steam compressor. The motor M and the driving shaft drive the gearbox to rotate, and the gearbox drives the two driven shafts to rotate, thereby driving each stage of the compressor to work.

[0061] The four-stage steam compression device includes first-stage compression, second-stage compression, third-stage compression, and fourth-stage compression, which sequentially compress the recovered low-temperature and low-pressure steam, and output high-temperature and high-pressure steam after four-stage compression.

[0062] The liquid storage tank is a water tank. Water is treated through filtration and deoxygenation, etc., filtering impurities in the water, removing dissolved oxygen in the water, preventing equipment corrosion in a high-temperature environment, and storing the treated water in the water tank. The inlet of the water pump is connected to the water tank, and the outlet of the water pump is respectively connected to the flow regulating valves on 4 cooling pipelines 104. The cooling pipelines 104 are connected to the outlet paths of each stage of compression through nozzles 106 for spraying water mist into the steam after each stage of compression respectively. Among them, the nozzle 106 can be set on the steam pipeline 105, or can be set on the steam flow paths such as the compressor inter-stage outlet / impeller outlet, etc. The purpose is to cool down the steam compressed by the compressor.

[0063] In this embodiment, the flow regulating valve 107 before each stage of nozzle 106 can adjust the flow rate of this water circuit. Since the outlet pressure of the total water pump 103 is controlled by constant pressure, the flow rate adjustment between each water circuit does not affect each other.

[0064] Among them, a gas-liquid separator 108 is arranged between every two stages of compression in this application, which can remove liquid droplets in the steam and solve the problem of liquid hammer in the compressor impeller.

[0065] Overall, the low-pressure and low-temperature water steam is compressed in the first stage. The pressure of the water steam is increased, but the exhaust superheat degree is also very large. Therefore, low-temperature water mist is directly sprayed into the steam at the outlet of the first stage of compression. The water mist absorbs the heat of the superheated steam and evaporates, mixing with the superheated steam to form saturated or nearly saturated steam, greatly reducing the superheat degree. In order to prevent the water mist from not completely evaporating during the steam-water mixing process, the liquid water is first sent to the gas-liquid separator for separation and then sent to the second stage of compression. Similarly, in order to reduce the superheat degree of the steam after the second, third, and fourth stages of compression, low-temperature water mist is directly sprayed into the exhaust gas at the outlets of the second to fourth stages. Before the inlets of the third and fourth stages, they will first pass through the gas-liquid separator. Whether to add a gas-liquid separator after spraying at the outlet of the fourth stage is determined by the user's requirements, that is, if the user allows the steam to carry liquid, there is no need to add a gas-liquid separator; if the user does not allow the steam to carry liquid, a gas-liquid separator needs to be added.

[0066] The above steam compression equipment can control multiple cooling pipelines 104 through a main water pump 103, achieving decoupling between the multiple cooling pipelines 104. Each cooling pipeline 104 is not affected by each other, reducing equipment costs and improving equipment control efficiency. The removal of liquid droplets in the steam is achieved through a gas-liquid separator, solving the problem of liquid hammer in the compressor impeller.

[0067] Figure 5 FIG. shows a schematic structural diagram of a cooling control system of a steam compression equipment according to an embodiment of the present invention. Refer to Figure 5 , this embodiment provides a cooling control system 200 of a steam compression equipment, the system includes a controller 20 and the steam compression equipment 10 of the above embodiment, such as Figure 3 the steam compression equipment in. The controller 20 is respectively connected to the main water pump 103 of the steam compression equipment, the flow regulating valve on each cooling pipeline 104, the temperature sensor T and the pressure sensor P1 on each steam pipeline 105, and the water pump pressure detector P2; the controller 20 is configured to obtain the actual superheat degree of the steam in each steam pipeline 105 according to the real-time temperature value and the real-time pressure value in each steam pipeline 105, and obtain the valve control signal of the flow regulating valve corresponding to each steam pipeline according to the magnitude relationship between the actual superheat degree and the preset superheat degree, so as to control the valve opening of each flow regulating valve.

[0068] Wherein, the controller 20 is connected to the main water pump 103 and the water pump pressure detector of the steam compression equipment, and can control the frequency of the main water pump 103 according to the real-time pressure value of the main water pump 103 detected by the water pump pressure detector, so as to control the outlet pressure value of the main water pump 103 to be configured as the target pressure value.

[0069] The controller 20 is connected to the temperature sensor T and the pressure sensor P1 on each steam pipeline 105, and can obtain the real-time temperature value and the real-time pressure value of the steam in each steam pipeline 105, and then obtain the actual superheat degree of the steam in each steam pipeline 105. Furthermore, the controller obtains the valve control signal of the flow regulating valve 108 corresponding to each steam pipeline by calculating the magnitude of the actual superheat degree and the preset superheat degree.

[0070] The controller 20 is connected to the flow regulating valve 108 on each cooling pipeline 104, and can output a valve control signal to the flow regulating valve 108, thereby controlling the valve opening of the flow regulating valve 108. Furthermore, the amount of water mist sprayed by the nozzle 106 on the same cooling pipeline as the flow regulating valve into the connected steam pipeline 105 is adjusted. For example, when the actual superheat degree is greater than the preset superheat degree, it indicates that the temperature in the steam pipeline 105 is too high, then the valve control signal is to increase the valve opening to increase the amount of water mist sprayed by the nozzle 106 into the connected steam pipeline 105, and cooling is achieved by increasing the sprayed cooling water mist. Similarly, when the actual superheat degree is less than the preset superheat degree, it indicates that the temperature in the steam pipeline 105 is lower than the preset temperature, then the valve control signal is to decrease the valve opening to reduce the amount of water mist sprayed by the nozzle 106 into the connected steam pipeline 105, and the cooling rate is slowed down by reducing the sprayed cooling water mist.

[0071] In this embodiment, the controller 20 of the cooling control system is further configured to adjust the frequency of the main water pump 103 according to the valve control signal of any flow regulating valve and the outlet pressure of the main water pump 103, so as to control the outlet pressure of the main water pump 103 to be the target pressure value.

[0072] For example, in the case where the valve control signal is to increase the valve opening, the frequency of the main water pump 103 is increased until the outlet pressure of the main water pump 103 is the target pressure value. Among them, the target pressure value can represent the pressure range within the control accuracy. For example, the target pressure value is Pset±ρ, where Pset is the preset pressure value and ρ represents the allowable pressure control accuracy. Similarly, in the case where the valve control signal is to decrease the valve opening, the frequency of the main water pump 103 is decreased until the outlet pressure of the main water pump 103 is the target pressure value.

[0073] Controlling the outlet pressure of the main water pump 103 to be the target pressure value can achieve independent control of multiple cooling pipelines 104 without mutual influence, and increase the stability of the steam compression equipment.

[0074] Figure 6 The step flowchart of a cooling control method for a steam compression equipment according to an embodiment of the present invention is shown. The cooling control method for the steam compression equipment is applied to the cooling control system of the steam compression equipment in the above embodiment, and the execution subject of this method is the controller.

[0075] Refer to Figure 6 , the cooling control method for the steam compression equipment includes the following steps:

[0076] S1. Determine the actual superheat degree of the steam in the steam pipeline according to the real-time temperature value and real-time pressure value in each steam pipeline 105.

[0077] In one example, the actual superheat degree ΔT of the steam in the steam pipe can be obtained by the difference between the actual temperature T and the saturation temperature Tvap at the same pressure, that is, ΔT = T - Tvap. It can be understood that the saturation temperature Tvap corresponding to different pressures and different temperatures is different, and specifically, it can be obtained by looking up a table.

[0078] S2. Obtain the valve control signal of the flow regulating valve corresponding to the steam pipe according to the magnitude relationship between the actual superheat degree and the preset superheat degree.

[0079] In one example, the preset superheat degree in each steam pipe is ΔTset ± ε, where ε represents the allowable superheat degree control accuracy. By comparing the actual superheat degree with the preset superheat degree, that is, according to the magnitude of ΔT and (ΔTset ± ε), the valve control signal is obtained.

[0080] In this embodiment, the preset superheat degree of the (near) saturated steam entering the lower-stage compression can be in the range of 0 - 15K. The saturated steam can be 0K, and the nearly superheated steam can be 10 - 15K. The preset superheat degree accuracy ε can be set to 2K. At this time, the preset superheat degree ΔTset range is 2 - 15K, which can make the actual inlet superheat degree ΔT ≥ 0K.

[0081] Among them, if ΔTset - ε ≤ ΔT ≤ ΔTset + ε, it means that the superheat degree of the steam pipe is already within the allowable superheat degree range and no adjustment is required.

[0082] If ΔT > ΔTset + ε, or ΔT < ΔTset - ε, it means that the superheat degree of the steam pipe exceeds the allowable superheat degree range, and then a valve control signal is generated to increase or decrease the valve opening.

[0083] S3. Control the valve opening of the flow regulating valve corresponding to the steam pipe according to the valve control signal to control the amount of water mist sprayed by the target nozzle into the steam pipe.

[0084] Among them, the target nozzle is the nozzle connected to the cooling pipeline where the flow regulating valve corresponding to the steam pipe is located. That is, the target nozzle is the nozzle on the same cooling branch as the steam pipe and the flow regulating valve.

[0085] Continuing the above example, if ΔT > ΔTset + ε, it means that the superheat degree is too high at this time, and it is necessary to increase the amount of water mist sprayed by the nozzles at this stage into the steam pipe to reduce the superheat degree. Then the valve control signal at this time is to increase the valve opening, and the flow regulating valve is opened wider at this time.

[0086] If ΔT < ΔTset - ε, it means that the superheat degree is too low at this time, and it is necessary to reduce the amount of water mist sprayed by the nozzles at this stage into the steam pipe to increase the superheat degree. Then the valve control signal at this time is to decrease the valve opening, and the flow regulating valve is reduced at this time.

[0087] In this way, by detecting the real-time temperature value and real-time pressure value of each steam pipeline in real time, and according to the above steps S1 to S3, the control of the flow regulating valve of each cooling branch can be realized, and further the amount of water mist sprayed by each nozzle onto the steam pipeline can be controlled, so that the independent control of each branch can be achieved, and the cooling control efficiency can be improved.

[0088] In this embodiment, the preset superheat has a preset minimum threshold and a maximum threshold range. For example, the preset minimum threshold is ΔTset - ε, and the preset maximum threshold is ΔTset + ε. The valve control signal is obtained according to the magnitude relationship between the actual superheat and the preset superheat, including: obtaining a valve control signal for increasing the valve opening according to the actual superheat being greater than the maximum threshold; obtaining a valve control signal for reducing the valve opening according to the actual superheat being less than the minimum threshold. According to the actual superheat being greater than or equal to the minimum threshold and less than or equal to the maximum threshold, the valve opening remains unchanged.

[0089] That is, if ΔT > ΔTset + ε, it indicates that the superheat is too high at this time, and it is necessary to increase the amount of water mist sprayed by the nozzles of this stage into the steam pipeline to reduce the superheat. Then the valve control signal at this time is to increase the valve opening, and the flow regulating valve is opened wider at this time.

[0090] If ΔT < ΔTset - ε, it indicates that the superheat is too low at this time, and it is necessary to reduce the amount of water mist sprayed by the nozzles of this stage into the steam pipeline to increase the superheat. Then the valve control signal at this time is to reduce the valve opening, and the flow regulating valve is reduced at this time.

[0091] Among them, if ΔTset - ε ≤ ΔT ≤ ΔTset + ε, it indicates that the superheat of the steam pipeline is already within the allowable superheat range at this time and no adjustment is required.

[0092] The cooling control method of the steam compression device in this embodiment further includes: adjusting the frequency of the total water pump 103 according to the valve control signal of any flow regulating valve and the outlet pressure of the total water pump 103 detected by the water pump pressure detector, so as to control the outlet pressure of the total water pump 103 to be the target pressure value.

[0093] In an example, the target pressure value is Pset ± ρ, where Pset is the preset pressure value, and ρ represents the allowable pressure control accuracy. The outlet pressure of the total water pump 103 is represented by Pw. If Pset - ρ ≤ Pw ≤ Pset + ρ, it means that the outlet pressure of the total water pump 103 is stabilized at the target pressure value.

[0094] Among them, adjusting the frequency of the main water pump 103 according to the valve control signal and the outlet pressure of the main water pump 103 detected by the water pump pressure detector includes: when the valve control signal of any flow regulating valve is to increase the valve opening, increasing the frequency of the main water pump 103 until the outlet pressure of the main water pump 103 reaches the target pressure value; when the valve control signal of any flow regulating valve is to decrease the valve opening, decreasing the frequency of the main water pump 103 until the outlet pressure of the main water pump 103 reaches the target pressure value.

[0095] When the valve control signal is a signal to increase the valve opening, at this time, open the flow regulating valve wider and increase the frequency of the main water pump 103, so as to increase the amount of water mist sprayed into the steam pipeline to accelerate the cooling, so as to reach the preset superheat degree, and continuously detect the outlet pressure of the main water pump 103 until the water pump outlet pressure Pset - ρ ≤ Pw ≤ Pset + ρ.

[0096] When the valve control signal is a signal to decrease the valve opening, at this time, close the flow regulating valve smaller and decrease the frequency of the main water pump 103, so as to reduce the amount of water mist sprayed into the steam pipeline to slow down the cooling rate, so as to reach the preset superheat degree, and continuously detect the outlet pressure of the main water pump 103 until the water pump outlet pressure Pset - ρ ≤ Pw ≤ Pset + ρ.

[0097] Through the above method, the constant pressure and variable frequency adjustment of the main water pump 103 can be realized, so that the outlet pressure of the main water pump 103 is maintained at the target pressure value.

[0098] Figure 7 The logic diagram showing a cooling control method of a steam compression device according to an embodiment of the present invention is referred to Figure 7 , and the control method is as described below:

[0099] ① Set the preset superheat degree ΔTset ± ε for entering the next stage, where ε represents the allowable superheat degree control accuracy; set the outlet pressure Pset ± ρ of the main water pump 103, where ρ represents the allowable pressure control accuracy;

[0100] ② According to the actual temperature value and actual pressure value before entering the next-stage vapor compression, calculate the actual superheat degree ΔT at this time. For example, calculate the saturation temperature Tvap at this pressure by the pressure sensor P before the inlet of the second-stage compression (after the first-stage compression), and compare it with the temperature sensor T, and calculate the superheat degree ΔT = T - Tvap at this time;

[0101] ③ Compare the actual superheat degree ΔT with the preset superheat degree (ΔTset ± ε);

[0102] ④ If ΔTset - ε ≤ ΔT ≤ ΔTset + ε, it means that the superheat degree is already within the allowable superheat degree range at this time and no adjustment is required;

[0103] ⑤ If ΔT > ΔTset + ε, it indicates that the superheat degree is too high at this time, and it is necessary to increase the spray amount of this stage to reduce the superheat degree. At this time, open the flow regulating valve and increase the frequency of the water pump until the outlet pressure of the water pump satisfies Pset - ρ ≤ Pw ≤ Pset + ρ; if ΔT < ΔTset + ε, it indicates that the superheat degree is too low at this time, and it is necessary to reduce the spray amount of this stage to achieve the reduction of the superheat degree. At this time, close the flow regulating valve and reduce the frequency of the water pump until the outlet pressure of the water pump satisfies Pset - ρ ≤ Pw ≤ Pset + ρ;

[0104] ⑥ Repeat steps ③ - ⑤ to complete the regulation of the water spray amount and achieve the preset superheat degree.

[0105] The cooling control method of the steam compression device in this embodiment further includes: determining the acting pressure of the nozzle according to the particle size required for the water mist ejected from the nozzle to evaporate; determining the target pressure value according to the acting pressure of the nozzle and the maximum steam pressure value after being compressed by the multi - stage compression part.

[0106] Since the acting pressure of the nozzle (i.e., the pressure difference at both ends of the nozzle) and the flow rate through the nozzle are in one - to - one correspondence and show a positive correlation, there are different spray particle sizes and distributions under different acting pressures of the nozzle, and the particle size decreases with the increase of pressure until it is almost unchanged. The smaller the particle size, the faster the liquid droplet evaporates. For the high - pressure stage, for the same nozzle, the back pressure is high. At this time, the water pump needs to provide a higher pressure to overcome the high back pressure to ensure the same acting pressure so that the spray particle size at the nozzle outlet is the same. Since the single - pump spray system has only one total water pump 103, the pressure of the total water pump 103 in this embodiment needs to be set according to the acting pressure required for spraying after compression in the highest stage (the Nth stage).

[0107] When ignoring other resistances in the system pipeline, if the pressure value Pw of the total water pump 103 ≥ △P + max[Pv], where Pw is the pressure provided by the total water pump 103, that is, the outlet pressure of the total water pump 103, △P is the acting pressure of the nozzle when the particle size d0 required for evaporation is reached, Pv is the steam pressure after each stage of compression, and max[Pv] represents taking the maximum value.

[0108] For example, for the nozzle between the first - stage compression part and the second - stage compression part, when the water mist ejected reaches the particle size d0 required for evaporation, if we want the water mist with particle size d0 to evaporate, we can obtain △P through actual experience values or by looking up tables. Through the pressure sensors after each stage of compression, we can obtain the steam pressure Pv after each stage of compression, and then obtain the maximum value max[Pv], that is, the maximum steam pressure value after being compressed by the multi - stage compression part. Furthermore, according to Pw ≥ △P + max[Pv], we can obtain the pressure value Pw of the total water pump 103. That is to say, when setting the target pressure value in this embodiment, the preset outlet pressure of the water pump Pset ≥ △P + max[Pv]. Combining with the allowable pressure control accuracy ρ, the target pressure value Pset ± ρ can be calculated.

[0109] Among them, the droplet size d of the mist ejected from the nozzle of each stage of the compression section in this embodiment satisfies: max[d] ≤ d0. In this way, the water mist ejected from the nozzle can be made not to exceed the required particle size for evaporation. Then, when the system operates stably, the spraying of all stages will be evaporated in time without causing excessive waste of water spraying.

[0110] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the concept of the present invention by using the content of the specification and drawings of the present invention, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A vapor compression device, characterized in that, Comprising: A cooling control component connected to a liquid storage tank, and a multi-stage compression section connected in series in sequence; The cooling control component includes a main water pump and multiple parallel cooling pipelines. The number of the cooling pipelines is the same as and corresponds one-to-one with the number of compression sections in the multi-stage compression section. The inlet of the main water pump is connected to the liquid storage tank, and the outlet of the main water pump is connected to the multiple cooling pipelines. Wherein, the outlet pressure value of the main water pump is configured as a target pressure value; The outlet of each stage of the compression section is connected with a steam pipeline, and each cooling pipeline is respectively connected with the steam pipeline after the outlet of the corresponding stage of the compression section through a nozzle.

2. The steam compression device according to claim 1, characterized in that, A flow regulating valve is arranged on each of the cooling pipelines. The flow regulating valve is used to adjust the amount of water mist sprayed into the connected steam pipeline by the target nozzle according to a valve control signal. The target nozzle is the nozzle connected to the cooling pipeline where the flow regulating valve is located; Wherein, the valve control signal of each flow regulating valve is obtained according to the magnitude relationship between the actual superheat degree in the steam pipeline connected to the cooling pipeline where the flow regulating valve is located and a preset superheat degree.

3. The steam compression device according to claim 1, wherein A temperature sensor and a pressure sensor are arranged on the steam pipeline. The temperature sensor and the pressure sensor are respectively used to detect the real-time temperature value and the real-time pressure value in the steam pipeline; A water pump pressure detector is arranged at the outlet of the main water pump for detecting the outlet pressure of the main water pump.

4. The steam compression device according to claim 1, characterized in that, A gas-liquid separator is arranged on the steam pipeline. In the steam transmission direction between two adjacent stages of the compression section, the gas-liquid separator is located downstream of the nozzle, and the temperature sensor and the pressure sensor on the steam pipeline are both located downstream of the gas-liquid separator.

5. A cooling control system for a vapor compression device, characterized in that, The system includes a controller and the steam compression device according to any one of claims 1-4; The controller is respectively connected to the main water pump of the steam compression device, the flow regulating valve on each cooling pipeline, the temperature sensor and the pressure sensor on each steam pipeline, and the water pump pressure detector; The controller is configured to obtain the actual superheat degree of the steam in each steam pipeline according to the real-time temperature value and the real-time pressure value in each steam pipeline, and obtain the valve control signal of the flow regulating valve corresponding to each steam pipeline according to the magnitude relationship between the actual superheat degree and the preset superheat degree, so as to control the valve opening of each flow regulating valve.

6. The cooling control system of the steam compression device according to claim 5, characterized in that, The controller is further configured to adjust the frequency of the main water pump according to the valve control signal of any flow regulating valve and the outlet pressure of the main water pump, so as to control the outlet pressure of the main water pump as the target pressure value.

7. A cooling control method for a vapor compression device, characterized in that, A cooling control system applied to the steam compression device according to claim 5 or 6, the method comprising: Determining the actual superheat degree of the steam in the steam pipeline according to the real-time temperature value and the real-time pressure value in each steam pipeline; Obtaining the valve control signal of the flow regulating valve corresponding to the steam pipeline according to the magnitude relationship between the actual superheat degree and the preset superheat degree; Control the valve opening of the flow regulating valve corresponding to the steam pipeline according to the valve control signal, so as to control the amount of water mist sprayed into the steam pipeline by the target nozzle, where the target nozzle is the nozzle connected to the cooling pipeline where the flow regulating valve corresponding to the steam pipeline is located.

8. The cooling control method of the steam compression device according to claim 7, characterized in that, The preset superheat degree has a minimum threshold and a maximum threshold. Obtaining the valve control signal of the flow regulating valve corresponding to the steam pipeline according to the magnitude relationship between the actual superheat degree and the preset superheat degree includes: When the actual superheat degree is greater than the maximum threshold, obtain a valve control signal to increase the valve opening. When the actual superheat degree is less than the minimum threshold, obtain a valve control signal to decrease the valve opening. When the actual superheat degree is greater than or equal to the minimum threshold and less than or equal to the maximum threshold, keep the valve opening unchanged.

9. The cooling control method of the vapor compression device according to claim 7 or 8, characterized in that, The method further includes: Adjust the frequency of the total water pump according to the valve control signal of any flow regulating valve and the outlet pressure of the total water pump detected by the water pump pressure detector, so as to control the outlet pressure of the total water pump to be the target pressure value.

10. The cooling control method of the steam compression device according to claim 9, characterized in that, Adjusting the frequency of the total water pump according to the valve control signal and the outlet pressure of the total water pump detected by the water pump pressure detector includes: When the valve control signal of any flow regulating valve is to increase the valve opening, increase the frequency of the total water pump until the outlet pressure of the total water pump is the target pressure value. When the valve control signal of any flow regulating valve is to decrease the valve opening, decrease the frequency of the total water pump until the outlet pressure of the total water pump is the target pressure value.

11. The cooling control method of the vapor compression device according to claim 9, characterized in that, The method further includes: Determine the acting pressure of the nozzle according to the particle size required for the water mist sprayed by the nozzle to evaporate. Determine the target pressure value according to the acting pressure of the nozzle and the maximum steam pressure value after being compressed by the multi-stage compression part.

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