Multistage flash pressure-stabilized heater drain recovery and anti-backflow device and method

Abstract

The embodiment of the present disclosure provides a multi-stage flash evaporation pressure stabilizing type heater drain recovery and anti-backflow device and method, the device comprises: a flash evaporation pressure stabilizing tank arranged between a high-stage heater drain outlet and a low-stage heater drain inlet, used for receiving and buffering the drain from the high-stage heater, and providing a vapor-liquid separation space; a cyclone vapor-liquid separator arranged in the flash evaporation pressure stabilizing tank, used for separating the vapor-liquid two-phase of the drain entering the flash evaporation pressure stabilizing tank; a liquid seal anti-backflow pipe connected between the liquid phase outlet of the flash evaporation pressure stabilizing tank and the low-stage heater; a variable nozzle steam return pipe connected between the vapor space of the upper part of the flash evaporation pressure stabilizing tank and the low-stage heater; and a bypass drain pump interface arranged in the bypass of the liquid seal anti-backflow pipe.

Description

Technical Field

[0001] The embodiments disclosed herein belong to the technical field of drainage system for regenerating heaters of thermal power units, drainage staged gravity flow and flash evaporation recovery, specifically involving a multi-stage flash evaporation pressure-stabilized heater drainage recovery and anti-backflow device and method. Background Technology

[0002] Regenerative heater drainage systems typically employ either gravity flow or pump-assisted drainage. During rapid load changes, the pressure difference between each heater stage changes rapidly, which can easily lead to poor drainage, flash evaporation, backflow, significant liquid level fluctuations, and drainage pipe vibration.

[0003] Under low load or cylinder cut-off conditions, the extraction steam pressure of some heaters drops and the condensate head is insufficient. Traditional condensate pipelines cannot simultaneously handle flash steam recovery and stable liquid phase discharge, resulting in reduced thermal economy and equipment safety risks.

[0004] Therefore, how to solve the above problems has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The embodiments disclosed herein aim to at least solve one of the technical problems existing in the prior art, and provide a device and method for hydrophobic recovery and backflow prevention of a multi-stage flash stabilizing heater.

[0006] A first aspect of the embodiments of this disclosure provides a multi-stage flash stabilizing heater condensate recovery and backflow prevention device, comprising: The flash pressure stabilizing tank is located between the condensate outlet of the higher-stage heater and the condensate inlet of the lower-stage heater. It is used to receive and buffer the condensate from the higher-stage heater and provide a space for vapor-liquid separation. A cyclone vapor-liquid separator is installed inside the flash pressure tank and is used to separate the vapor and liquid phases of the condensate entering the flash pressure tank. A liquid-sealed anti-backflow pipe is connected between the liquid phase outlet of the flash pressure stabilizing tank and the lower-level heater; A variable nozzle return pipe is connected between the steam space at the top of the flash pressure tank and the lower-level heater; The bypass drain pump interface is located in the bypass of the liquid seal anti-backflow pipe.

[0007] Optionally, the liquid seal anti-backflow pipe is one of a U-shaped, inverted U-shaped, or multi-fold liquid seal structure.

[0008] Optionally, the outlet end of the variable nozzle return pipe can be connected to any one of the following: the steam side of the lower-level heater, the steam space of the deaerator, or the mixing section of the low-pressure extraction steam pipeline.

[0009] Optionally, it also includes an emergency drainage bypass located beside the liquid seal anti-backflow pipe, the emergency drainage bypass having the bypass drainage pump interface.

[0010] Optionally, the nozzles on the variable nozzle return pipe are configured to adjust their opening based on pressure, liquid level signals, and the pressure difference between adjacent heaters.

[0011] A second aspect of the embodiments of this disclosure provides an operation method for a multi-stage flash stabilizing heater condensate recovery and backflow prevention device, the method being implemented according to the device described above, comprising: During normal load operation, the condensate from the higher-level heater flows into the flash pressure stabilizing tank. After separation by the cyclone vapor-liquid separator, the flash steam is recovered to the downstream thermal system through the variable nozzle return steam pipe, while the liquid phase condensate flows into the lower-level heater through the liquid seal anti-backflow pipe by natural pressure difference. When the unit rapidly reduces the load, it is detected that the pressure difference between adjacent heaters decreases. The opening of the variable nozzle return steam pipe is reduced, and the unidirectional flow of liquid phase hydrophobicity is regulated through the liquid seal anti-backflow pipe. When the unit rapidly increases its load, if the liquid level in the flash pressure tank exceeds the set high value, the condensate pump will be started through the bypass condensate pump interface to control the liquid level in the flash pressure tank.

[0012] The beneficial effects of the embodiments of this disclosure include: In this application, a flash pressure stabilizing tank is used to buffer and separate vapor and liquid. A liquid seal anti-backflow pipe is used to form a physical water seal to prevent fluid backflow. The flash steam recovery is adjusted by a variable nozzle return pipe to adapt to pressure difference changes. When the pressure difference is insufficient, a bypass pump interface is used to assist in condensation. This effectively suppresses condensation backflow, water hammer, and pipeline vibration under rapid load changes and low load conditions. At the same time, the waste heat from the condensate is recovered, which significantly improves the operational safety and thermal economy of the regenerative system. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of a multi-stage flash evaporation pressure-stabilized heater condensate recovery and backflow prevention device according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram of the structure of a flash pressure stabilizing tank according to an embodiment of the present disclosure; Figure 3 This is a schematic diagram illustrating the principle of hydrophobic backflow prevention and flash evaporation waste heat recovery in one embodiment of the present disclosure.

[0014] In the diagram, 1 is a flash pressure stabilizing tank; 2 is a cyclone vapor-liquid separator; 3 is a liquid seal anti-backflow pipe; 4 is a variable nozzle return steam pipe; 5 is a bypass drain pump interface; 6 is an emergency drain bypass; 11 is a variable nozzle return steam interface; and 12 is a liquid phase drain outlet. Detailed Implementation

[0015] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] The embodiments of this application will be further described in detail below with reference to the accompanying drawings and examples. The detailed descriptions and accompanying drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments. In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0017] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" 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 direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances.

[0018] like Figure 1-3 As shown, a multi-stage flash evaporation pressure-stabilized heater condensate recovery and backflow prevention device includes a flash evaporation pressure-stabilized tank 1, a cyclone vapor-liquid separator 2, a liquid seal backflow prevention pipe 3, a variable nozzle return steam pipe 4, and a bypass condensate pump interface 5.

[0019] The flash pressure stabilizing tank 1 is arranged between the condensate outlet of the higher-level heater and the condensate inlet of the lower-level heater. It is used to receive and buffer the condensate from the higher-level heater and provide a space for vapor-liquid separation.

[0020] A cyclone vapor-liquid separator 2 is installed inside the flash pressure stabilizing tank 1 to separate the vapor and liquid phases of the condensate entering the flash pressure stabilizing tank 1. A liquid-sealed anti-backflow pipe 3 is connected between the liquid phase outlet of the flash pressure stabilizing tank 1 and the lower-stage heater.

[0021] The variable nozzle return steam pipe 4 is connected between the steam space at the top of the flash pressure tank 1 and the lower-level heater. The bypass drain pump interface 5 is located in the bypass of the liquid seal anti-backflow pipe 3.

[0022] In this application, the flash pressure stabilizing tank 1 buffers and separates the condensate and vapor-liquid mixture. The liquid seal anti-backflow pipe 3 forms a physical water seal to prevent fluid backflow. The flash steam recovery is adjusted by the variable nozzle return steam pipe 4 to adapt to pressure difference changes. When the pressure difference is insufficient, the bypass pump interface assists in condensate drainage. This effectively suppresses condensate backflow, water hammer, and pipeline vibration under rapid load changes and low load conditions. At the same time, the waste heat from the condensate is recovered, significantly improving the operational safety and thermal economy of the regenerative system.

[0023] Specifically, the variable nozzle return steam pipe 4 is connected to the flash pressure stabilizing tank 1 through the variable nozzle return steam interface 11, and the liquid seal anti-backflow pipe 3 is connected to the liquid phase condensate outlet 12.

[0024] In some embodiments, the liquid seal anti-backflow pipe 3 is one of a U-shaped, inverted U-shaped, or multi-fold liquid seal structure.

[0025] In some embodiments, the outlet end of the variable nozzle return steam pipe 4 is connected to any one of the steam side of the lower-level heater, the steam space of the deaerator, or the mixing section of the low-pressure extraction steam pipe.

[0026] In some embodiments, an emergency drainage bypass 6 is also provided on the side of the liquid seal anti-backflow pipe 3, the emergency drainage bypass 6 having the bypass drainage pump interface 5.

[0027] In some embodiments, the nozzles on the variable nozzle return pipe 4 are configured to adjust their opening based on pressure, liquid level signals, and the pressure difference between adjacent heaters.

[0028] A second aspect of the embodiments of this disclosure provides an operation method for a multi-stage flash stabilizing heater condensate recovery and backflow prevention device, the method being implemented according to the device described above, comprising: During normal load operation, the condensate from the higher-level heater flows into the flash pressure stabilizing tank 1. After separation by the cyclone vapor-liquid separator 2, the flash steam is recovered to the downstream thermal system through the variable nozzle return steam pipe 4, while the liquid phase condensate flows into the lower-level heater through the liquid seal anti-backflow pipe 3 by natural pressure difference.

[0029] When the unit rapidly reduces the load, it is detected that the pressure difference between adjacent heaters decreases. The opening of the variable nozzle return steam pipe 4 is reduced, and the unidirectional flow of liquid phase hydrophobicity is adjusted through the liquid seal anti-backflow pipe 3.

[0030] When the unit rapidly increases its load, if the liquid level in the flash pressure tank 1 exceeds the set high value, the condensate pump will be started through the bypass condensate pump interface 5 to control the liquid level in the flash pressure tank 1.

[0031] This application discloses a multi-stage flash pressurized heater condensate recovery and anti-backflow device suitable for thermal power units operating under rapid load changes, low loads, and cylinder cut-off conditions. The device includes a flash pressurized tank 1, a cyclone vapor-liquid separator 2, a liquid-sealed anti-backflow pipe 3, a variable nozzle return steam pipe 4, and a bypass condensate pump interface 5. After entering the flash pressurized tank 1, the condensate undergoes vapor-liquid separation through the cyclone vapor-liquid separator 2, and the flash steam is recovered to the next lower-stage heater or deaerator. The liquid condensate is stably discharged through the liquid-sealed anti-backflow pipe 3, thereby suppressing backflow, water hammer, and flash impact, and improving the utilization rate of condensate waste heat.

[0032] Specifically, the present application discloses a multi-stage flash evaporation pressure-stabilized heater condensate recovery and anti-backflow device, characterized in that it includes a flash evaporation pressure-stabilized tank 1, a cyclone vapor-liquid separator 2, a liquid seal anti-backflow pipe 3, a variable nozzle return steam pipe 4, and a bypass condensate pump interface 5.

[0033] The flash pressure stabilizing tank 1 is located between the drain outlet of the higher-level heater and the drain inlet of the lower-level heater. The liquid seal anti-backflow pipe 3 is a U-shaped, inverted U-shaped, or multi-fold liquid seal structure. The variable nozzle return steam pipe 4 connects the upper steam space of the flash pressure stabilizing tank 1 with the steam side of the lower-level heater, the deaerator, or the low-pressure extraction steam mixing section.

[0034] In some embodiments, the variable nozzle opening is adjusted according to the pressure difference between adjacent heaters, the condensate level, and the flash pressure, and the bypass condensate pump interface 5 is activated when the natural pressure difference is insufficient.

[0035] This application proposes a condensate recovery and backflow prevention device for a multi-stage flash pressurized heater. The device comprises a flash pressurized tank 1, a cyclone vapor-liquid separator 2, a liquid-sealed backflow prevention pipe 3, a bypass condensate pump interface 5, and a variable nozzle return steam pipe 4, installed between adjacent heater stages. Condensate first enters the flash pressurized tank 1 to release some flash steam. The flash steam then returns to the steam side of the lower-stage heater or the deaerator via the variable nozzle return steam pipe 4. Liquid condensate is then stably discharged via the liquid-sealed backflow prevention pipe 3.

[0036] In this application, the above structure, through the synergy of flash space, liquid seal height and variable nozzle throttling area, enables the hydrophobic system to maintain a stable flow direction when the pressure difference changes rapidly, avoids backflow and water hammer, and improves the efficiency of hydrophobic waste heat recovery.

[0037] like Figure 3 As shown in the figure, the schematic diagram illustrates the principle of hydrophobic backflow prevention and flash evaporation waste heat recovery. The workflow includes: higher-level hydrophobic water entering the pressure stabilizing tank (flash evaporation pressure stabilizing tank 1) - flash evaporation pressure stabilization vapor-liquid separation - flash evaporation steam recovery and utilization, and liquid phase hydrophobic water seal discharge - lower-level heater or deaerator - backflow prevention and water hammer prevention.

[0038] Furthermore, the flash pressure stabilizing tank 1 is arranged between the condensate outlet of the higher-level heater and the condensate inlet of the lower-level heater. The upper part of the tank is the flash steam zone, the lower part is the liquid phase buffer zone, and the middle part is equipped with a cyclone vapor-liquid separator 2.

[0039] The outlet of the liquid phase buffer zone is connected to the liquid seal anti-backflow pipe 3. The liquid seal anti-backflow pipe 3 adopts a U-shaped or inverted U-shaped combination structure, and its liquid seal height is determined according to the minimum pressure difference between adjacent heaters.

[0040] The flash steam zone is connected to the steam-side inlet of the lower-level heater, the steam space of the deaerator, or the low-pressure extraction steam mixing section via a variable nozzle return pipe 4.

[0041] A bypass drainage pump interface 5 and an emergency drainage bypass 6 are installed on the side of the liquid seal anti-backflow pipe 3, so that auxiliary transportation can be activated for a short time when the natural pressure difference is insufficient.

[0042] In some embodiments, under normal load, the condensate from the higher-level heater enters the flash pressure stabilizing tank 1, the flash steam is recovered through the return steam pipe, and the liquid phase condensate enters the lower-level heater through the liquid seal anti-backflow pipe 3.

[0043] When the load is reduced rapidly, the pressure difference between adjacent heaters decreases, the variable nozzle reduces its opening to suppress flash steam backflow, and the liquid seal anti-backflow pipe 3 maintains unidirectional liquid phase flow.

[0044] When the load increases rapidly, the amount of condensate increases. The flash pressure tank 1 provides a buffer volume, and the bypass condensate pump interface 5 provides short-term compensation according to the liquid level change to prevent high water level impact.

[0045] This application effectively suppresses backflow of condensate, flash evaporation impact, and water hammer in condensate pipes, improving safety under low load and rapid load changes.

[0046] Recovering hydrophobic flash steam improves the thermal economy of the regenerative system.

[0047] Passive safety is achieved through a liquid seal and pressure stabilizing tank structure, which reduces the risk of backflow even if the regulating valve response is delayed.

[0048] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A multi-stage flash evaporation pressure-stabilized heater condensate recovery and backflow prevention device, characterized in that, include: The flash pressure stabilizing tank is located between the condensate outlet of the higher-stage heater and the condensate inlet of the lower-stage heater. It is used to receive and buffer the condensate from the higher-stage heater and provide a space for vapor-liquid separation. A cyclone vapor-liquid separator is installed inside the flash pressure tank and is used to separate the vapor and liquid phases of the condensate entering the flash pressure tank. A liquid-sealed anti-backflow pipe is connected between the liquid phase outlet of the flash pressure stabilizing tank and the lower-level heater; A variable nozzle return pipe is connected between the steam space at the top of the flash pressure tank and the lower-level heater; The bypass drain pump interface is located in the bypass of the liquid seal anti-backflow pipe.

2. The multi-stage flash evaporation pressure-stabilized heater condensate recovery and backflow prevention device according to claim 1, characterized in that, The liquid seal anti-backflow pipe is one of the following: U-shaped, inverted U-shaped, or multi-fold liquid seal structure.

3. The multi-stage flash evaporation pressure-stabilized heater condensate recovery and backflow prevention device according to claim 1 or 2, characterized in that, The outlet end of the variable nozzle return pipe is connected to any one of the following: the steam side of the lower-level heater, the steam space of the deaerator, or the mixing section of the low-pressure extraction steam pipeline.

4. The multi-stage flash evaporation pressure-stabilized heater condensate recovery and backflow prevention device according to claim 1, characterized in that, It also includes an emergency drainage bypass located next to the liquid seal anti-backflow pipe, wherein the emergency drainage bypass has the bypass drainage pump interface.

5. The multi-stage flash evaporation pressure-stabilized heater condensate recovery and backflow prevention device according to claim 1, characterized in that, The nozzles on the variable nozzle return pipe are configured to adjust their opening based on pressure, liquid level signals, and the pressure difference between adjacent heaters.

6. A method for operating a multi-stage flash evaporation pressure-stabilized heater condensate recovery and backflow prevention device, wherein the method is implemented using the device according to any one of claims 1-5, characterized in that, include: During normal load operation, the condensate from the higher-level heater flows into the flash pressure stabilizing tank. After separation by the cyclone vapor-liquid separator, the flash steam is recovered to the downstream thermal system through the variable nozzle return steam pipe, while the liquid phase condensate flows into the lower-level heater through the liquid seal anti-backflow pipe by natural pressure difference. When the unit rapidly reduces the load, the pressure difference between adjacent heaters is monitored to decrease. The opening of the variable nozzle return steam pipe is closed, and the unidirectional flow of liquid phase hydrophobic water is regulated through the liquid seal anti-backflow pipe. When the unit rapidly increases its load, if the liquid level in the flash pressure tank exceeds the set high value, the condensate pump will be started through the bypass condensate pump interface to control the liquid level in the flash pressure tank.

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