A multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control

Abstract

The utility model discloses a kind of multistage centrifugal compressor based on supercritical carbon dioxide temperature control, mainly through cooler to carbon dioxide cooling, by high-temperature carbon dioxide is led to the place of reflux regulating valve assembly, carbon dioxide temperature compensation, the temperature of carbon dioxide can be adjusted to above supercritical temperature, avoid gas-liquid characteristic to centrifugal compressor cause damage, guarantee the normal stable operation of centrifugal compressor.The main technical scheme of the utility model is as follows: a kind of multistage centrifugal compressor based on supercritical carbon dioxide temperature control, including multistage compressor main body, the multistage compressor main body includes upper level inlet and lower level outlet;Lower level outlet is connected with the inlet of cooler and the first end of temperature regulating valve respectively;The outlet of cooler and the second end of temperature regulating valve are all connected with the first end of reflux regulating valve assembly, the second end of reflux regulating valve assembly is connected with upper level inlet.The utility model is mainly used for carbon dioxide temperature regulation.

Description

Technical Field

[0001] This utility model relates to the field of centrifugal compressor technology, and in particular to a multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control. Background Technology

[0002] With advancements in centrifugal compressor technology and the expansion of CO2 applications, CO2 can be used in various ways, such as transporting it to oil wells for oil displacement and CO2 sequestration in carbon reduction. Both of these require compressors to pressurize the CO2. For CO2 applications, the characteristics of supercritical CO2 must be considered. Supercritical carbon dioxide refers to CO2 forming a fluid where gas and liquid phases are mixed when the temperature is below 31.26℃ and the pressure is above 72.9 atmospheres. During compressor pressurization, if the pressure and temperature exceed the supercritical characteristics of CO2, the gas-liquid properties of CO2 will cause serious damage to the compressor and deviate from the original compressor design parameters. Therefore, to avoid supercritical phenomena and compressor damage, temperature control is crucial as pressure increases.

[0003] Because of the high compressor outlet temperature, supercritical phenomena will not occur even under high pressure. However, in some special operating conditions, CO2 is self-circulated via reflux to prevent surge. To avoid the impact of high temperature on subsequent equipment, a cooler is usually installed to cool the medium. However, the cooler's temperature control is an indirect method, and changes in ambient temperature have a significant impact on the medium's temperature. In winter, if the cooling water temperature is too low, the medium temperature will be low. Furthermore, since reflux is a pressure reduction process, according to fluid characteristics, the temperature will continue to decrease after reflux, causing CO2 to reach a supercritical state. Utility Model Content

[0004] In view of this, in order to solve at least one of the above-mentioned technical problems, this utility model provides a multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control.

[0005] To achieve the above objectives, this utility model mainly provides the following technical solutions: This utility model provides a multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control, comprising: The main body of a multi-stage compressor includes an inlet for the previous stage and an outlet for the next stage. The cooler and temperature regulating valve are connected to the inlet of the cooler and the first end of the temperature regulating valve, respectively. The reflux regulating valve assembly is connected to the first end of the cooler outlet and the second end of the temperature regulating valve. The second end of the reflux regulating valve assembly is connected to the inlet of the previous stage.

[0006] The multi-stage centrifugal compressor also includes: Temperature sensing element, which is connected to the input end of the reflux regulating valve assembly; The multi-stage centrifugal compressor also includes: The temperature control module is electrically connected to the temperature detection element and the temperature regulating valve.

[0007] The temperature regulating valve is a pneumatic valve, and it is connected to the first instrument air source.

[0008] The multi-stage centrifugal compressor also includes: The first position feedback module and the control system are electrically connected to the temperature regulating valve and the control system, respectively. The control system is at least used to display the position of the temperature regulating valve.

[0009] The reflux regulating valve assembly includes a reflux regulating valve, a first solenoid valve, and a second solenoid valve. The first end of the reflux regulating valve is connected to the outlet of the cooler and the second end of the temperature regulating valve, respectively; the second end of the reflux regulating valve is connected to the inlet of the previous stage inlet. The first and second solenoid valves are connected to the reflux regulating valve.

[0010] The multi-stage centrifugal compressor also includes: The solenoid valve control module is electrically connected to the first solenoid valve and the second solenoid valve.

[0011] The reflux regulating valve is a pneumatic valve, and it is connected to a second instrument air source.

[0012] The multi-stage centrifugal compressor also includes: The second position feedback module and the control system are electrically connected to the reflux regulating valve and the control system, respectively. The control system is at least used to display the position of the reflux regulating valve.

[0013] This invention proposes a multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control. It controls the temperature of the reflux carbon dioxide returning from the outlet of the next stage compressor to the inlet of the previous stage. The carbon dioxide is cooled by a cooler, and the high-temperature carbon dioxide is led to the inlet of the reflux regulating valve assembly by adjusting the opening of the temperature regulating valve. This compensates for the temperature of the carbon dioxide after it has been cooled by the cooler. The temperature of the carbon dioxide can be adjusted to above the supercritical temperature as needed, avoiding damage to the centrifugal compressor caused by gas-liquid properties and ensuring the normal and stable operation of the centrifugal compressor. Attached Figure Description

[0014] Figure 1 A schematic diagram of a multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control is provided for an embodiment of this utility model; Figure 2 A schematic diagram of another multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control provided for an embodiment of this utility model. Detailed Implementation

[0015] To further illustrate the technical means and effects adopted by this utility model to achieve its intended purpose, the following detailed description, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control proposed according to this utility model.

[0016] In one implementation, such as Figure 1 As shown, this utility model provides a multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control, comprising: The multi-stage compressor body includes an upper stage inlet 100 and a lower stage outlet 200; The cooler 300 and the temperature regulating valve 400 are connected to the inlet of the cooler 300 and the first end of the temperature regulating valve 400, respectively. The outlet of the cooler 300 and the second end of the temperature regulating valve 400 are both connected to the first end of the reflux regulating valve assembly 500, and the second end of the reflux regulating valve assembly 500 is connected to the previous stage inlet 100.

[0017] The multi-stage compressor body includes at least two centrifugal compressor stages, each consisting of an upper-stage compressor and a lower-stage compressor. The upper-stage inlet 100 and the lower-stage outlet 200 are the inlet and outlet of the upper-stage compressor, respectively. Specifically, this embodiment is based on a CCUS eight-stage CO2 assembled centrifugal compressor unit. After the sixth stage compressor, the pressure will be above 70 barA. If the temperature is not properly controlled, the CO2 will be in a supercritical state. The upper-stage inlet 100 is the seventh-stage inlet, and the lower-stage outlet 200 is the eighth-stage outlet. It can be understood that the multi-stage centrifugal compressor also includes first to sixth-stage centrifugal compressors. Since the multi-stage compressor body is an existing structure, and the inlet and outlet of the first to sixth-stage centrifugal compressors do not involve supercritical carbon dioxide temperature control, this embodiment will not describe them in detail. The multi-stage compressor body is omitted in the figure, only the upper-stage inlet 100 and the lower-stage outlet 200 are shown. The centrifugal compressors are connected in series to achieve continuous compression of carbon dioxide, and the carbon dioxide temperature and pressure will continuously increase.

[0018] The connections of the components described below, such as the first-stage outlet 200 being connected to the inlet of the cooler 300 and the first end of the temperature regulating valve 400, refer to connections via pipes, meaning they are connected and interconnected, allowing carbon dioxide to be transferred between the connected components. Further details regarding pipe connections will not be elaborated upon later.

[0019] Cooler 300 can be a conventional cooler. Under normal operating conditions, when carbon dioxide is output, it is output through the OUT terminal. The temperature of the carbon dioxide can be adjusted by the settings of cooler 300. For example, if the outlet pressure of the compressor's eighth stage is 126 barA and the temperature is around 113°C, the set temperature of cooler 300 is around 40°C to 50°C. When the medium is one that is inconvenient to vent, the gas flows back from the eighth stage outlet to the seventh stage inlet. This backflow prevents excessive pressure and allows the gas to circulate, preventing surge. Cooler 300 serves to cool the gas through backflow, preventing the high-temperature gas from affecting the seventh stage inlet temperature. This would prevent the seventh stage inlet temperature from becoming too high, thus avoiding a continuous rise in gas temperature at the eighth stage outlet, which could damage the centrifugal compressor. Since backflow is a pressure reduction process, the temperature will continue to decrease after backflow according to fluid characteristics. At this point, the high-temperature carbon dioxide is replenished by opening the temperature regulating valve 400, thereby preventing supercriticality.

[0020] Specifically, the next-level outlet 200, i.e., the eighth-level outlet, branches out into two paths. In one path, carbon dioxide passes through cooler 300 and is cooled according to the set temperature. In the other path, carbon dioxide is drawn out based on the opening of temperature regulating valve 400. The two paths converge before the return regulating valve assembly 500, whereby the low-temperature carbon dioxide is compensated by the high-temperature carbon dioxide. That is, this embodiment adopts a thermal bypass form, regulating the heat flow by controlling temperature regulating valve 400, and mixing it with the cold flow to prevent the carbon dioxide temperature from becoming too low. Temperature regulating valve 400 can be an adjustable valve, allowing adjustment of the carbon dioxide flow rate in the branch as needed, thereby controlling the temperature of the carbon dioxide entering the return regulating valve assembly 500. The opening of temperature regulating valve 400 can be set to a fixed opening as needed. For example, under stable operating conditions, the opening of temperature regulating valve 400 can be roughly predicted to meet the compensation requirements. Alternatively, in some embodiments, the opening of temperature regulating valve 400 can be adjusted based on temperature feedback, which will be described later with more specific embodiments.

[0021] The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control proposed in this embodiment controls the temperature of the reflux carbon dioxide from the outlet of the next stage back to the inlet of the previous stage. The carbon dioxide is cooled by a cooler, and the high-temperature carbon dioxide is led to the inlet of the reflux regulating valve assembly by opening and closing the temperature regulating valve, thereby compensating for the temperature of the carbon dioxide cooled by the cooler. The temperature of the carbon dioxide can be adjusted to above the supercritical temperature as needed, avoiding damage to the centrifugal compressor caused by gas-liquid properties and ensuring the normal and stable operation of the centrifugal compressor.

[0022] In one embodiment, the multistage centrifugal compressor further includes a temperature sensing element 600, which is connected to the input end of the reflux regulating valve assembly 500.

[0023] The temperature sensor 600 is located between the confluence of the two branches and the input of the reflux regulating valve assembly 500. It provides feedback on the temperature of the carbon dioxide fluid after mixing. By calculating the bypass heat return flow rate, the orifice size of the temperature regulating valve 400 is adjusted to meet the temperature setting after mixing. In other words, the opening of the temperature regulating valve 400 is adjusted based on the temperature signal from the temperature sensor 600, ultimately achieving temperature control and preventing CO2 supercriticality. The temperature can be selectively controlled within the range of 40°C to 60°C.

[0024] The following combination Figure 1 A description of a control process: When continuous reflux is required during compressor start-up or anti-surge operation, the reflux regulating valve assembly 500 opens. At this point, the pressure is higher, and the temperature is the same as after the cooler 300. Since reflux is a pressure-reducing process, the temperature will continue to decrease after reflux, according to fluid characteristics. At this time, the bypass thermal bypass temperature regulating valve 400 opens. Based on temperature feedback before the reflux regulating valve assembly 500, the opening of the temperature regulating valve 400 is controlled, maintaining a suitable temperature before the reflux regulating valve assembly 500. Even with reflux cooling, the carbon dioxide will not reach a supercritical state. This control method not only ensures the normal start-up and operation of the multi-stage compressor, keeping the carbon dioxide in a stable gaseous state, but also guarantees the safe and stable operation of the compressor system, improving the customer's work and production efficiency.

[0025] In one implementation, such as Figure 2 As shown, the multi-stage centrifugal compressor also includes a temperature control module 820, which is electrically connected to both the temperature sensor 600 and the temperature regulating valve 400. The temperature control module 820 controls the opening degree of the temperature regulating valve 400 based on the temperature information fed back by the temperature sensor 600.

[0026] More specifically, the temperature regulating valve 400 is a pneumatic valve, which is connected to a first instrument air source 700. The first instrument air source 700 is connected to the temperature control module 820, which in turn drives the temperature regulating valve 400 to different degrees to control the opening degree.

[0027] In one embodiment, the multi-stage centrifugal compressor further includes a first position feedback module 810 and a control system 850. The first position feedback module 810 is electrically connected to both the temperature regulating valve 400 and the control system 850. The control system 850 is used at least to display the position of the temperature regulating valve 400 to indicate the current valve status. The dashed lines in the figure represent connections to the control system; these connections can be wired or wireless (local area network), and will not be detailed further below.

[0028] In one embodiment, the reflux regulating valve assembly 500 includes a reflux regulating valve 510, a first solenoid valve 520, and a second solenoid valve 530. The first end of the reflux regulating valve 510 is connected to the outlet of the cooler 300 and the second end of the temperature regulating valve 400, respectively, and the second end of the reflux regulating valve 510 is connected to the inlet of the previous stage inlet 100. The first solenoid valve 520 and the second solenoid valve 530 are connected to the reflux regulating valve 510.

[0029] The multi-stage centrifugal compressor also includes: a solenoid valve control module 840, which is electrically connected to the first solenoid valve 520 and the second solenoid valve 530. The reflux regulating valve 510 is a pneumatic valve, and it is connected to a second instrument air source 900.

[0030] The second instrument air source 900 is connected to the return flow regulating valve 510, thereby driving the return flow regulating valve 510 to different degrees to control its opening. The solenoid valve control module 840 is used to receive commands. For example, when the quick-opening function is triggered or the interlocking stop is activated, the solenoid valve control module 840 responds to the command to de-energize the first solenoid valve 520 and the second solenoid valve 530. The air source at the pneumatic diaphragm of the return flow regulating valve 510 is released through the discharge ports of the first solenoid valve 520 and the second solenoid valve 530, causing the return flow regulating valve 510 to fully open.

[0031] In one embodiment, the multistage centrifugal compressor further includes a second position feedback module 830 and a control system 850, wherein the second position feedback module 830 is electrically connected to the reflux regulating valve 510 and the control system 850, respectively. The control system 850 is used at least to display the position of the reflux regulating valve 510 to indicate the current valve status.

[0032] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control, characterized in that, include: A multi-stage compressor body, the multi-stage compressor body including an upper stage inlet (100) and a lower stage outlet (200). A cooler (300) and a temperature regulating valve (400), wherein the next-stage outlet (200) is connected to the inlet of the cooler (300) and the first end of the temperature regulating valve (400), respectively; The outlet of the cooler (300) and the second end of the temperature regulating valve (400) are both connected to the first end of the reflux regulating valve assembly (500), and the second end of the reflux regulating valve assembly (500) is connected to the upper-level inlet (100).

2. The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control according to claim 1, characterized in that, Also includes: A temperature sensor (600) is connected to the input end of the reflux regulating valve assembly (500).

3. The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control according to claim 2, characterized in that, Also includes: Temperature control module (820) is electrically connected to temperature detection element (600) and temperature regulating valve (400) respectively.

4. The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control according to claim 1, characterized in that, The temperature regulating valve (400) is a pneumatic valve, and the temperature regulating valve (400) is connected to a first instrument air source (700).

5. The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control according to claim 1, characterized in that, Also includes: The first position feedback module (810) and the control system (850) are electrically connected to the temperature regulating valve (400) and the control system (850), respectively. The control system (850) is at least used to display the position of the temperature regulating valve (400).

6. The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control according to claim 1, characterized in that, The reflux regulating valve assembly (500) includes a reflux regulating valve (510), a first solenoid valve (520), and a second solenoid valve (530). The first end of the reflux regulating valve (510) is connected to the outlet of the cooler (300) and the second end of the temperature regulating valve (400), respectively, and the second end of the reflux regulating valve (510) is connected to the upstream inlet (100); The first solenoid valve (520) and the second solenoid valve (530) are connected to the reflux regulating valve (510).

7. The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control according to claim 6, characterized in that, Also includes: A solenoid valve control module (840) is electrically connected to the first solenoid valve (520) and the second solenoid valve (530).

8. The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control according to claim 1, characterized in that, The reflux regulating valve (510) is a pneumatic valve, and the reflux regulating valve (510) is connected to a second instrument air source (900).

9. The multi-stage centrifugal compressor based on supercritical carbon dioxide temperature control according to claim 1, characterized in that, Also includes: The second position feedback module (830) and the control system (850) are electrically connected to the return flow regulating valve (510) and the control system (850), respectively. The control system (850) is at least used to display the position of the reflux regulating valve (510).

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