Low pressure heater drain gravity device and control method thereof

Abstract

The application discloses a low-pressure heater drainage self-flow device and a control method thereof. The low-pressure heater drainage self-flow device comprises a drainage self-flow pipeline, a steam injection pipeline and an adjusting door. The drainage self-flow pipeline comprises a drainage rising pipe section and a drainage falling pipe section. The drainage rising pipe section is used for forming a vapor-liquid two-phase fluid after steam is introduced. The drainage falling pipe section is used for flowing drainage and forms a density difference with the drainage rising pipe section. The density difference is used for providing power for the drainage flow in the drainage self-flow pipeline. The steam injection pipeline is arranged on the drainage rising pipe section and is used for injecting saturated steam into the drainage rising pipe section to reduce the density of the fluid in the drainage rising pipe section. The adjusting door is arranged on the steam injection pipeline and is used for adjusting the steam flow injected into the drainage rising pipe section. According to the low-pressure heater drainage self-flow device, power is provided for the drainage flow in the drainage self-flow pipeline to ensure the drainage self-flow of the low-pressure heater drainage self-flow device under a low-load working condition.

Description

Technical Field

[0001] This invention relates to the field of thermal power generator sets, and more specifically, to a low-pressure heater condensate drainage device and its control method. Background Technology

[0002] To ensure the power generation of new energy sources, traditional thermal power generating units are undertaking the task of grid peak shaving. Under the current electricity market situation, the power generation load of thermal power units has been repeatedly reduced, making the staged gravity flow of condensate formed by the pressure difference of the steam inlet of each low-pressure heater no longer sufficient.

[0003] In existing thermal power unit regenerative systems, low-pressure heater condensate typically flows downstream through condensate pipes to recover heat from the condensate. However, during low-load operation, the pressure difference between the inlet steam of each low-pressure heater decreases, making it difficult to maintain gravity flow of condensate. Often, the low-pressure heaters have to open emergency condensate valves to directly discharge the condensate to the condenser or exhaust system. This prevents the recovery of heat from the low-pressure heater condensate, further deteriorating the unit's economic efficiency under low-load conditions. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a low-pressure heater condensate gravity flow device, which can provide power for the flow of condensate in the condensate gravity flow pipe with minimal modification to the existing regenerative system, so as to solve the problem that the condensate of the low-pressure heater cannot flow in stages under low load conditions and alleviate the degree of deterioration in the economic performance of the unit.

[0005] Another object of the present invention is to provide a control method for a low-pressure heater drainage self-flow device that applies the above-mentioned low-pressure heater drainage self-flow device.

[0006] According to an embodiment of the present invention, a low-pressure heater condensate gravity flow device includes: a condensate gravity flow pipe, the condensate gravity flow pipe including a condensate riser section and a condensate faller section, the condensate riser section being used to form a vapor-liquid two-phase fluid after steam is introduced, the condensate faller section being used to flow condensate and forming a density difference with the condensate riser section, the density difference being used to provide power for the condensate flow in the condensate gravity flow pipe; a steam injection pipe, the steam injection pipe being disposed on the condensate riser section, being used to inject saturated steam into the condensate riser section to reduce the density of the fluid in the condensate riser section; and a regulating valve, the regulating valve being disposed on the steam injection pipe, being used to regulate the steam flow rate injected into the condensate riser section.

[0007] According to an embodiment of the present invention, a low-pressure heater condensate gravity flow device includes a condensate riser section and a condensate faller section in the condensate gravity flow pipe. The condensate riser section is used to form a vapor-liquid two-phase fluid after steam is introduced. The condensate faller section is used to flow condensate and forms a density difference with the condensate riser section. The density difference is used to provide power for the condensate flow in the condensate gravity flow pipe. A steam injection pipe is provided on the condensate riser section to inject saturated steam into the condensate riser section to reduce the density of the fluid in the condensate riser section. A regulating valve is provided on the steam injection pipe to regulate the steam flow rate injected into the condensate riser section so that a vapor-liquid two-phase fluid is formed in the condensate riser section, and a density difference is formed with the condensate faller section to drive the condensate flow, thereby providing power for the condensate flow in the condensate gravity flow pipe to ensure the condensate gravity flow of the low-pressure heater condensate gravity flow device under low load conditions.

[0008] In some embodiments of the present invention, the steam injection pipe is provided with multiple steam inlets along the hydrophobic riser section.

[0009] In some embodiments of the present invention, multiple steam inlets are uniformly arranged along the hydrophobic riser pipe section.

[0010] Some embodiments of the present invention further include: an ultrasonic flow meter, wherein the ultrasonic flow meter is disposed outside the hydrophobic flow pipe and is used to detect the hydrophobic flow rate inside the hydrophobic flow pipe.

[0011] In some embodiments of the present invention, the hydrophobic gravity flow pipe further includes a hydrophobic connecting pipe section connecting the hydrophobic downflow pipe section and the hydrophobic upflow pipe section, and the ultrasonic flow meter is located outside the hydrophobic connecting pipe section.

[0012] Some embodiments of the present invention further include: an upstream low-pressure heater, which is connected to the steam injection pipeline and is used to supply saturated steam to the steam injection pipeline.

[0013] Some embodiments of the present invention further include: a downstream low-pressure heater, which is connected to the gravity-flow drainage pipe and is used to supply drainage to the downstream low-pressure heater; the upstream low-pressure heater and the downstream low-pressure heater are two low-pressure heaters arranged sequentially along the gravity-flow drainage direction.

[0014] According to an embodiment of the present invention, a control method for a low-pressure heater condensate gravity flow device is provided, wherein the low-pressure heater condensate gravity flow device is as described above, and the control method includes: when the condensate flow rate in the condensate gravity flow pipe is determined to be zero, controlling the regulating valve to open.

[0015] According to the control method of the low-pressure heater condensate gravity flow device of the present invention, when the condensate flow rate in the condensate gravity flow pipe is determined to be zero, the regulating valve is opened, and the fluid state in the condensate riser section is changed by steam injection to restore the driving force required for condensate gravity flow. This can reduce the heat loss caused by direct discharge of condensate under low load conditions and help maintain the economic operation of the regenerative system.

[0016] In some embodiments of the present invention, the low-pressure heater drainage gravity flow device further includes an ultrasonic flow meter, which is used to detect the drainage flow rate in the drainage gravity flow pipe, and the ultrasonic flow meter is communicatively connected to the regulating valve.

[0017] In some embodiments of the present invention, the control method includes: after determining that the drainage flow rate in the drainage gravity flow pipe has been restored, controlling the regulating valve to close.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the structure of a low-pressure heater hydrophobic self-flowing device according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the principle of liquid column pressure difference formed by fluids of different densities within a connected structure according to an embodiment of the present invention.

[0020] Figure label: 100. Low-pressure heater drainage gravity flow device; 1. Gravity drainage pipe; 11. Drainage riser pipe section; 12. Drainage downcomer pipe section; 13. Drainage connecting pipe section; 2. Steam injection pipeline; 21. Steam inlet; 3. Adjustment door; 4. Ultrasonic flow meter; 5. Upstream low-pressure heater; 6. Downstream low-pressure heater. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] In the description of this invention, "first feature" and "second feature" may include one or more of the features, "multiple" means two or more, "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them, and "above," "over," and "on top" the second feature may include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0024] The following description, with reference to the accompanying drawings, describes a low-pressure heater drainage self-flow device 100 according to an embodiment of the present invention.

[0025] like Figure 1 and Figure 2 As shown, the low-pressure heater condensate gravity flow device 100 includes: a condensate gravity flow pipe 1, which includes a condensate riser section 11 and a condensate fall section 12. The condensate riser section 11 is used to form a vapor-liquid two-phase fluid after steam is introduced, and the condensate fall section 12 is used to flow condensate and form a density difference with the condensate riser section 11. The density difference is used to provide power for the condensate flow in the condensate gravity flow pipe 1; a steam injection pipe 2, which is located on the condensate riser section 11, and is used to inject saturated steam into the condensate riser section 11 to reduce the density of the fluid in the condensate riser section 11; and a regulating valve 3, which is located on the steam injection pipe 2, and is used to regulate the steam flow rate injected into the condensate riser section 11.

[0026] Specifically, in this embodiment, the gravity-flow condensate drain pipe 1 constitutes a tiered gravity-flow path for condensate between the low-pressure heaters, and the condensate downcomer section 12 is located at... Figure 1 On the left, the drainage riser section 11 is located Figure 1On the right side, the two are connected at the bottom by a condensate drain pipe section 13 to form a continuous condensate flow path. The steam injection pipe 2 is led out from the upstream steam intake on the left and connected to the condensate riser pipe section 11. A regulating valve 3 is arranged on the steam injection pipe 2 to introduce an appropriate amount of steam into the condensate riser pipe section 11 when needed. In this way, the low-pressure heater condensate gravity flow device 100 does not require a separate condensate cooler or water pump; instead, the driving force is directly restored within the existing condensate gravity flow loop.

[0027] Specifically, the formula for calculating the density of water in both vapor and liquid phases is: (1) In the formula: ρm: Density of the mixture of water and gas phases ρg: Density of single-phase saturated steam ρL: Density of single-phase saturated water x: The mass ratio of single-phase steam to water in the two-phase mixture, i.e., dryness. Taking a power plant with a heat balance diagram showing a steam extraction pressure of 0.268 MPa in section six as an example, the saturated steam density is found to be 1.485 kg / m³, and the saturated water density is 934.78 kg / m³, according to tables or calculations. Assuming a certain dryness fraction, the density of the water-vapor-liquid mixture can be calculated using Formula 1, as shown in Table 1 below. Table 1

[0028] As shown in Table 1, the density of the steam-water two-phase mixture is much lower than that of the single-phase water after adding a small amount of steam to the single-phase water. Assuming saturated water at a pressure of 0.268 MPa is injected into a connecting pipe within a closed space, this is further illustrated by the following scenario: Figure 2 As shown.

[0029] According to the physical principles and formulas for calculating liquid pressure, the pressure at points A and A' inside the connecting pipe, which are at the same height h above the liquid surface, is the same and both are values ​​shown in the following formula: (2) In the formula: P: liquid pressure; ρ: liquid density h: height above the liquid surface g: acceleration due to gravity Saturated steam at the assumed pressure is injected into side A'. Table 1 shows that the density of the steam-water two-phase mixture will be less than the density of single-phase water, i.e.: (3) In this state, the pressures on side A and side A', as determined by Formula 2, are no longer equal, that is: (4) If the pressures on sides A and A' remain equal, the only change is the liquid level height on side A' in Formula 2, i.e., hA'. When the following formula holds true, the liquid on side A' will flow out of the connecting pipe, i.e.: (5) If single-phase water is continuously injected into side A and steam is injected into side A', a continuous liquid flow will be formed, provided that Formula 5 is satisfied.

[0030] Therefore, from Table 1 and Figure 2 It can be seen that within a connected structure, if the fluid density decreases on one side, the liquid column relationship at the same height will change, thus creating a pressure difference that drives the continuous flow of the liquid. Corresponding to... Figure 1 In the low-pressure heater condensate gravity flow device 100, after saturated steam is introduced into the condensate riser section 11 by the steam injection pipe 2, the condensate in the condensate riser section 11 changes from a single-phase liquid to a two-phase vapor-liquid fluid, and the average density of the fluid in the condensate riser section 11 decreases accordingly. The condensate fallr section 12 still mainly flows with single-phase condensate, so the fluid density in the condensate fallr section 12 is higher than the fluid density in the condensate riser section 11. As a result, a stable density difference is formed between the condensate fallr section 12 and the condensate riser section 11, and this density difference continues to be converted into the power to drive the condensate to flow along the condensate gravity flow pipe 1.

[0031] Since the density of the two-phase gas-liquid fluid is less than the density of the single-phase condensate in the condensate downcomer section 12, the liquid pressure difference formed by the density difference can continuously provide power for the condensate flow in the condensate gravity flow pipe 1, thereby solving the problem that the low-pressure heater cannot complete the condensate gravity flow under low load conditions because the extraction steam pressure difference cannot meet the requirements.

[0032] In practical applications, this embodiment is primarily used in thermal power plants under low-load conditions. Under low load, the existing system suffers from reduced extraction steam pressure differences between low-pressure heaters, making it difficult for the gravity-flow of condensate, which was originally maintained by pressure differences, to continue. The low-pressure heaters are forced to open emergency drain valves to directly discharge the condensate to the condenser or exhaust system, resulting in unrecoverable heat from the condensate. The low-pressure heater gravity-flow device 100 addresses this by adding a steam injection pipe 2 and a regulating valve 3 to the original gravity-flow pipe 1, directly utilizing the saturated steam from the regenerating heater to restore the driving force of the condensate riser section 11. This preserves the original condensate path while avoiding the need for additional large heat exchangers or power equipment, resulting in minimal modification and lower costs.

[0033] Furthermore, compared to existing methods that rely solely on the pressure difference at the inlet steam of the low-pressure heater to create a staged gravity flow of condensate, the low-pressure heater condensate gravity flow device 100 of this invention can maintain flow even under low-load conditions through the density difference between the two-phase gas-liquid fluid in the condensate riser section 11 and the single-phase condensate in the condensate faller section 12. In this way, the low-pressure heater condensate can continue to be transported to downstream regenerative equipment and participate in heat recovery, without frequent discharge into the condenser. This provides power for the condensate flow in the gravity flow pipe with minimal modifications to the existing regenerative system, solving the problem of the low-pressure heater condensate not being able to flow gradually under low-load conditions and mitigating the degree of economic deterioration of the unit.

[0034] This embodiment directly utilizes the saturated steam available in the system itself, without the need for additional power sources such as water pumps; moreover, only a few components such as steam injection pipe 2 and regulating valve 3 are needed to supplement the original system, which can achieve a relatively obvious hydrostatic recovery effect under low load conditions. Therefore, the overall technical transformation is relatively simple to implement and the transformation cost is low.

[0035] According to an embodiment of the present invention, the low-pressure heater condensate gravity flow device 100 includes a condensate riser section 11 and a condensate faller section 12 via a condensate gravity flow pipe 1. The condensate riser section 11 is used to form a vapor-liquid two-phase fluid after steam is introduced. The condensate faller section 12 is used to flow condensate and forms a density difference with the condensate riser section 11. The density difference is used to provide power for the condensate flow in the condensate gravity flow pipe 1. A steam injection pipe 2 is provided on the condensate riser section 11 to inject saturated steam into the condensate riser section 11 to reduce the density of the fluid in the condensate riser section 11. A regulating valve 3 is provided on the steam injection pipe 2 to regulate the steam flow rate injected into the condensate riser section 11 so that a vapor-liquid two-phase fluid is formed in the condensate riser section 11 and a density difference is formed with the condensate faller section 12 to drive the condensate flow, thereby providing power for the condensate flow in the condensate gravity flow pipe 1 to ensure the condensate gravity flow of the low-pressure heater condensate gravity flow device 100 under low load conditions.

[0036] In some embodiments of the present invention, such as Figure 1 As shown, the steam injection pipe 2 is provided with multiple steam inlets 21 along the drainage riser section 11.

[0037] Specifically, multiple steam inlets 21 are located at the junction of the steam injection pipe 2 and the condensate riser section 11. These multiple steam inlets 21 are used to disperse the steam in the steam injection pipe 2 into the condensate riser section 11. In this way, the saturated steam will not only concentrate in a single part of the condensate riser section 11, but will be able to enter the fluid inside the pipe at multiple locations within the condensate riser section 11, making it easier to form a stable vapor-liquid two-phase fluid within the condensate riser section 11.

[0038] In some embodiments of the present invention, such as Figure 1 As shown, multiple steam inlets 21 are evenly arranged along the drainage riser section 11.

[0039] Specifically, multiple steam inlets 21 are spaced apart along the length of the condensate riser section 11, making the steam injection positions of each steam inlet 21 relatively dispersed on the condensate riser section 11. As a result, steam can gradually enter the fluid inside the pipe at different heights along the condensate riser section 11, making it easier to form a more uniform vapor-liquid two-phase distribution state inside the condensate riser section 11, which is beneficial for continuously reducing the average density of the fluid inside the condensate riser section 11.

[0040] In some embodiments of the present invention, such as Figure 1 As shown, the low-pressure heater drainage gravity flow device 100 also includes an ultrasonic flow meter 4, which is located outside the drainage gravity flow pipe 1 and is used to detect the drainage flow rate inside the drainage gravity flow pipe 1.

[0041] Specifically, in this embodiment, the ultrasonic flow meter 4 is preferably a clamp-on or externally mounted structure, arranged on the outer wall of the gravity-flow drainage pipe 1, so that the flow information inside the gravity-flow drainage pipe 1 can be obtained without cutting the pipe. In this way, it is convenient to carry out technical transformation on existing power plant systems and can also reduce damage to the original gravity-flow drainage loop.

[0042] In some embodiments of the present invention, such as Figure 1 As shown, the drainage gravity flow pipe 1 also includes a drainage connecting pipe section 13 that connects the drainage downflow pipe section 12 and the drainage upflow pipe section 11, and the ultrasonic flow meter 4 is located outside the drainage connecting pipe section 13.

[0043] Specifically, the drainage connecting pipe section 13 is located between the drainage downcomer section 12 and the drainage riser section 11, connecting the two sections to allow drainage to flow continuously within the drainage gravity flow pipe 1. The ultrasonic flow meter 4, positioned outside the drainage connecting pipe section 13, can detect the drainage flow rate within the drainage gravity flow pipe 1. Since the drainage connecting pipe section 13 is located at the lower connection point of the drainage gravity flow loop, placing the ultrasonic flow meter 4 there makes it easier to reflect the overall drainage flow status within the drainage gravity flow pipe 1.

[0044] In some embodiments of the present invention, such as Figure 1 As shown, the low-pressure heater drainage gravity flow device 100 also includes an upstream low-pressure heater 5, which is connected to the steam injection pipe 2 and is used to supply saturated steam to the steam injection pipe 2.

[0045] Specifically, saturated steam in the upstream low-pressure heater 5 is transported to the condensate riser section 11 via steam injection pipe 2. With this configuration, steam injection pipe 2 can directly utilize existing steam resources within the system to supply steam to the condensate riser section 11, eliminating the need for an additional independent steam source. The regulating valve 3, installed on steam injection pipe 2, allows for adjustment of the steam flow rate into the condensate riser section 11 according to operational needs, enabling adjustment of the fluid state within the condensate riser section 11 under low-load conditions. Furthermore, since the driving force recovery process is primarily achieved by introducing saturated steam into the condensate riser section 11 and altering the fluid density within the pipe, no additional power equipment such as water pumps is required to complete the gravity-flow recovery of the condensate.

[0046] In some embodiments of the present invention, such as Figure 1 As shown, the low-pressure heater drainage gravity flow device 100 also includes a downstream low-pressure heater 6, which is connected to the drainage gravity flow pipe 1 and is used to receive the drainage transported by the drainage gravity flow pipe 1. The upstream low-pressure heater 5 and the downstream low-pressure heater 6 are two low-pressure heaters arranged sequentially along the drainage gravity flow direction.

[0047] Specifically, the gravity-flow condensate drain pipe 1 is located between two adjacent low-pressure heaters. The condensate downcomer section 12, the condensate connecting pipe section 13, and the condensate riser section 11 together form the pathway for condensate flow between the two low-pressure heaters. In addition to supplying saturated steam to the steam injection pipe 2, the upstream low-pressure heater 5 can also continue to transport its condensate to the downstream low-pressure heater 6 via the gravity-flow condensate drain pipe 1. With this configuration, the low-pressure heater condensate gravity-flow device 100 can be arranged in the cascading gravity-flow path between adjacent low-pressure heaters, supplementing the driving force for condensate flow under low-load conditions while maintaining the original condensate transfer relationship.

[0048] The following describes a control method for a low-pressure heater drainage self-flow device 100 according to an embodiment of the present invention.

[0049] According to an embodiment of the present invention, the control method of the low-pressure heater condensate gravity flow device 100 is the low-pressure heater condensate gravity flow device 100 described above. The control method includes: when the condensate flow rate in the condensate gravity flow pipe 1 is determined to be zero, controlling the regulating valve 3 to open.

[0050] Specifically, this control method is mainly used during the low-load operation phase of the unit. At this time, the gravity flow of condensate between adjacent low-pressure heaters, which was originally maintained by pressure difference, may weaken or even stop. The control method first determines the condensate flow rate in the gravity flow pipe 1; when the determination result shows that the condensate flow rate in the gravity flow pipe 1 drops to zero, the control regulating valve 3 is opened, allowing the steam injection pipe 2 to inject saturated steam into the condensate riser pipe section 11.

[0051] After the regulating valve 3 is opened, saturated steam enters the condensate riser section 11 and mixes with the condensate therein to form a vapor-liquid two-phase fluid. Since the average density of the vapor-liquid two-phase fluid in the condensate riser section 11 is lower than the density of the condensate in the condensate downcomer section 12, a density difference is formed between the condensate riser section 11 and the condensate downcomer section 12. This density difference continues to power the flow of condensate within the gravity-flow condensate pipe 1, enabling the condensate to continue being transported along the gravity-flow path.

[0052] Therefore, when the condensate flow stops, the regulating valve 3 can be opened, and steam injection can be used to change the fluid state within the condensate riser section 11 to restore the driving force required for gravity flow of the condensate. This reduces heat loss caused by direct discharge of condensate under low-load conditions and helps maintain the economic efficiency of the regenerative system.

[0053] According to the control method of the low-pressure heater condensate gravity flow device 100 of the present invention, when the condensate flow rate in the condensate gravity flow pipe 1 is determined to be zero, the regulating valve 3 is opened, and the fluid state in the condensate riser pipe section 11 is changed by steam injection to restore the driving force required for condensate gravity flow. This can reduce the heat loss caused by direct discharge of condensate under low load conditions and help maintain the economic operation of the regenerative system.

[0054] In some embodiments of the present invention, the low-pressure heater drainage gravity flow device 100 further includes an ultrasonic flow meter 4, which is used to detect the drainage flow rate in the drainage gravity flow pipe 1, and the ultrasonic flow meter 4 is communicatively connected to the regulating valve 3.

[0055] Specifically, the ultrasonic flow meter 4 is used to acquire the condensate flow rate information in the gravity-flow condensate pipe 1. When the condensate flow rate drops to zero, it triggers the opening of the regulating valve 3, allowing the steam injection pipe 2 to deliver steam to the condensate riser pipe section 11. Thus, the condensate flow detection action and the opening action of the regulating valve 3 can form a linked control process to improve the timeliness of response.

[0056] In some embodiments of the present invention, the control method includes controlling the regulating valve 3 to close after determining that the drainage flow rate in the drainage gravity flow pipe 1 has been restored.

[0057] Specifically, after the regulating valve 3 opens and continuously injects steam into the condensate riser section 11, a two-phase vapor-liquid fluid is formed within the condensate riser section 11. A density difference is created between the condensate downcomer section 12 and the condensate riser section 11, and the condensate flow in the gravity-flow condensate pipe 1 resumes. When it is determined that the condensate flow rate in the gravity-flow condensate pipe 1 has been restored, the regulating valve 3 is closed to stop the continued injection of steam into the condensate riser section 11. With this setting, the regulating valve 3 can exit the working state after the condensate flow resumes, thereby reducing steam consumption.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] In the description of this specification, the references to terms such as "embodiment," "specific embodiment," and "example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A low-pressure heater drainage self-flow device, characterized in that, include: A gravity-flow drainage pipe includes a drainage riser section and a drainage faller section. The drainage riser section is used to form a vapor-liquid two-phase fluid after steam is introduced. The drainage faller section is used to allow drainage to flow and forms a density difference with the drainage riser section. The density difference is used to provide power for the drainage flow in the gravity-flow drainage pipe. A steam injection pipe is provided in the condensate riser section for injecting saturated steam into the condensate riser section to reduce the density of the fluid in the condensate riser section. A regulating valve is provided on the steam injection pipe and is used to regulate the steam flow rate injected into the condensate riser section.

2. The low-pressure heater drainage gravity flow device according to claim 1, characterized in that, The steam injection pipeline is provided with multiple steam inlets along the hydrophobic riser section.

3. The low-pressure heater drainage gravity flow device according to claim 2, characterized in that, Multiple steam inlets are evenly arranged along the hydrophobic riser pipe section.

4. The low-pressure heater drainage gravity flow device according to claim 1, characterized in that, Also includes: An ultrasonic flow meter is installed on the outside of the gravity-flow pipe to detect the flow rate of the drainage within the pipe.

5. The low-pressure heater drainage gravity flow device according to claim 4, characterized in that, The drainage gravity flow pipe also includes a drainage connecting pipe section that connects the drainage downflow pipe section and the drainage upflow pipe section, and the ultrasonic flow meter is located outside the drainage connecting pipe section.

6. The low-pressure heater drainage gravity flow device according to claim 1, characterized in that, Also includes: An upstream low-pressure heater, which is connected to the steam injection pipeline, is used to supply saturated steam to the steam injection pipeline.

7. The low-pressure heater drainage gravity flow device according to claim 6, characterized in that, Also includes: The downstream low-pressure heater is connected to the gravity-flow drainage pipe and is used to supply drainage to the downstream low-pressure heater. The upstream low-pressure heater and the downstream low-pressure heater are two low-pressure heaters arranged sequentially along the gravity-flow drainage direction.

8. A control method for a low-pressure heater condensate gravity flow device, characterized in that, The low-pressure heater drain gravity flow device is the low-pressure heater drain gravity flow device according to any one of claims 1-7, and the control method includes: When the drainage flow rate in the drainage pipe is determined to be zero, the regulating valve is opened.

9. The control method for the low-pressure heater drainage gravity flow device according to claim 8, characterized in that, The low-pressure heater drainage gravity flow device also includes an ultrasonic flow meter, which is used to detect the drainage flow rate in the drainage gravity flow pipe. The ultrasonic flow meter is communicatively connected to the regulating valve.

10. The control method for the low-pressure heater drainage gravity flow device according to claim 8, characterized in that, The control method includes: Once the drainage flow rate in the gravity drainage pipe is determined to be restored, the regulating valve is closed.

Images