Backpressure machine shaft seal step cooling system

Abstract

The utility model provides a backpressure machine shaft seal step cooling system which comprises a demineralized water tank, a shaft seal cooler, a slag cooler and a deaerator, and a water outlet of the demineralized water tank is connected to a refrigerant water inlet of the shaft seal cooler through a demineralized water header pipe. A refrigerant water outlet of the shaft seal cooler is connected to a water inlet of the slag cooler through a desalted water mother pipe, and a water outlet of the slag cooler is connected to the deaerator through a pipeline III. The demineralized water is adopted as a cooling working medium of the cooling system, the flowing direction of the demineralized water strictly follows the temperature gradient matching principle, low-temperature or normal-temperature demineralized water firstly enters the shaft seal cooler to absorb middle-grade heat energy, and after being heated, the demineralized water has enough heat capacity and enters the slag cooler to treat high-grade hot slag, so that the process not only avoids quenching and cracking of the slag, but also improves the heat efficiency of the slag cooler. And the demineralized water is increased in a temperature gradient manner and finally enters the deaerator at a relatively high temperature, so that the energy consumption of the deoxygenated steam is remarkably reduced.

Description

Technical Field

[0001] This utility model relates to the field of industrial cooling system technology, specifically to a back pressure machine shaft seal stepped cooling system. Background Technology

[0002] In the field of industrial power generation and thermal energy utilization, back-pressure steam turbines, as a type of high-efficiency combined heat and power (CHP) equipment, rely heavily on the cooling effect of their shaft seal system, which directly impacts the safety and economy of unit operation. Traditional shaft seal cooling systems often employ a single cooling method, which has the following technical drawbacks:

[0003] Existing technologies typically involve directly condensing and discharging shaft seal steam or using single-stage cooling, failing to fully utilize the cascade cooling effect of the steam. Conventional systems often use industrial tap water as the cooling medium, which can easily lead to structural problems in pipelines, such as calcium and magnesium ions forming scale at high temperatures, reducing heat transfer efficiency; high dissolved oxygen content accelerating corrosion of metal pipelines; and when used directly for slag cooling, the contact between low-temperature water and high-temperature slag can easily cause slag explosion. Existing devices often handle shaft seal steam cooling and slag cooling processes independently, resulting in the inability to utilize heat energy in a cascade manner, large equipment footprint, and increased operating and maintenance costs.

[0004] To address the aforementioned issues, the industry urgently needs to develop an industrial cascade cooling system that utilizes a highly stable cooling medium, enables thermal coupling between systems, and improves overall energy efficiency. Utility Model Content

[0005] The purpose of this utility model is to provide a cascade cooling system for shaft seals of back-pressure turbines. Through reasonable system design, working fluid selection and cascade utilization of thermal energy, the system significantly improves cooling efficiency, reduces energy consumption, and enhances system stability and reliability. It is suitable for various back-pressure turbine shaft seal cooling scenarios.

[0006] To achieve the above objectives, the present invention proposes the following technical solution:

[0007] A back pressure compressor shaft seal staged cooling system includes a demineralized water tank, a shaft seal cooler, a slag cooler, and a deaerator;

[0008] The outlet of the deoxygenated water tank is connected to the refrigerant inlet of the shaft seal cooler via a demineralized water main pipe;

[0009] The refrigerant outlet of the shaft seal cooler is connected to the inlet of the slag cooler via a demineralized water header.

[0010] The outlet of the slag cooler is connected to the deaerator via a pipe.

[0011] As a preferred embodiment of this utility model, the shaft seal cooler is a shell-and-tube heat exchanger, with its shell-side inlet connected to the shaft seal steam pipe of the steam turbine, its tube-side water inlet being the refrigerant water inlet, and its tube-side water outlet being the refrigerant water outlet.

[0012] As a preferred embodiment of this utility model, the cooling system further includes a hot water recycling tank, and the shell-side outlet of the shaft seal cooler is connected to the hot water recycling tank.

[0013] As a preferred technical solution of this utility model, the recycled hot water tank is also provided with a low-pressure steam pipe for receiving steam from the low-pressure heating network;

[0014] And the hot water return main pipe connected to the deaerator.

[0015] As a preferred embodiment of this utility model, a connecting pipe is provided between the demineralized water tank and the recycled hot water tank, and a connecting valve is provided on the connecting pipe.

[0016] As a preferred technical solution of this utility model, the demineralized water main pipe is provided with pipe one and pipe four in parallel; pipe one is connected to the refrigerant inlet of the shaft seal cooler, and the refrigerant outlet of the shaft seal cooler is connected to the demineralized water main pipe through pipe two;

[0017] The outlet end of the fourth pipe is connected to the demineralized water main pipe.

[0018] As a preferred technical solution of this utility model, the cooling system includes at least two slag coolers, which are connected in parallel on the demineralized water header.

[0019] Each of the aforementioned slag coolers is equipped with one of the aforementioned deaerators.

[0020] As a preferred embodiment of this utility model, the cooling system further includes a condensate tank, the inlet of which is connected to the demineralized water header via a pipe five, and the outlet of which is connected to the deaerator via the condensate header.

[0021] As a preferred technical solution of this utility model, the deaerator is provided with an overflow water branch pipe, which is connected to the condensate tank and the recycled hot water tank respectively through the overflow water main pipe.

[0022] As can be seen from the above technical solutions, the present invention provides a back pressure compressor shaft seal staged cooling system, which uses demineralized water as the cooling medium. The flow direction of the demineralized water strictly follows the principle of temperature gradient matching. Low-temperature or room-temperature demineralized water first enters the shaft seal cooler to absorb medium-grade heat energy. After being heated to 70-80℃, it has sufficient heat capacity to enter the slag cooler to process high-grade hot slag. This process not only avoids the rapid cooling and cracking of slag, but also makes the temperature of the demineralized water increase in a gradient manner, and finally enters the deaerator at 90-100℃, which significantly reduces the energy consumption of deaeration steam.

[0023] Using demineralized water as the cooling medium avoids scaling and corrosion problems caused by traditional industrial water, thus extending the service life of equipment and pipelines.

[0024] Multiple slag coolers are connected in parallel, and the number of operating units can be dynamically adjusted according to the boiler slag discharge volume to avoid ash accumulation caused by insufficient water flow rate at low loads; if a single unit fails, the remaining equipment can still maintain system operation, improving the overall reliability of the system.

[0025] Waste heat recovery and utilization reduce operating costs. Steam condensate from the shaft seal cooler enters a reuse hot water tank and is then transported to the deaerator, increasing the initial water temperature of the deaerator and reducing steam consumption. Overflow water from the deaerator is diverted through an overflow header to a condensate tank or reuse hot water tank, achieving staged heat recovery and reducing makeup water consumption.

[0026] The demineralized water main is equipped with parallel branches, allowing for flexible adjustment of the flow rate into the shaft seal cooler and slag cooler, thus optimizing the cooling effect. A connecting pipe is installed between the demineralized water tank and the recycled hot water tank to balance water pressure and temperature, prevent overheating and vaporization, and improve system stability.

[0027] A stepped heating method is used to cool the slag, avoiding the high-temperature slag explosion problem caused by direct cooling with traditional low-temperature water. High-temperature demineralized water enters the deaerator, extending the service life of the equipment.

[0028] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered as part of the utility model subject matter of this disclosure, provided that such concepts do not contradict each other.

[0029] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0030] The accompanying drawings are not drawn to scale according to a true reference numeral. In the drawings, each identical or nearly identical component shown in the various figures can be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0031] Figure 1 This is a schematic diagram of the connection structure of the back pressure machine shaft seal stepped cooling system according to an embodiment of the present utility model;

[0032] Figure 2 This is a schematic diagram of the connection structure between the shaft seal cooler and the back-pressure steam turbine in an embodiment of this utility model.

[0033] The meanings of the reference numerals in the figure are as follows:

[0034] 1. Shaft seal cooler; 2. Demineralized water tank; 3. Reclaimed hot water tank; 4. Drain tank; 5. Slag cooler; 6. Deaerator; 7. Main inlet water pipe; 8. Demineralized water main pipe; 9. Pipe 1; 10. Pipe 4; 11. Steam turbine; 12. Pipe 2; 13. Demineralized water header; 14. Pipe 3; 15. Pipe 5; 16. Drain header; 17. Overflow header; 18. Pipe 6; 19. Pipe 7; 20. Connecting pipe; 21. Low-pressure steam pipe; 22. Reclaimed hot water header; 23. Pipe 8. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of this utility model without creative effort are within the scope of protection of this utility model. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this utility model pertains.

[0036] The terms "first," "second," and similar words used in this utility model patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" indicate that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0037] This utility model embodiment provides a cascade cooling system for a back pressure compressor shaft seal, including a shaft seal cooler 1, a demineralized water tank 2, a recycled hot water tank 3, a condensate tank 4, a slag cooler 5, and a deaerator 6. The system primarily uses demineralized water as the cooling medium. The demineralized water is finished water produced by removing most of the salts (including anions and cations) from water through a specific water treatment process. It has low conductivity, approaching that of pure water, and contains almost no calcium or magnesium ions, completely preventing scaling on system pipes and equipment, improving heat transfer efficiency, significantly reducing the risk of oxygen corrosion on system pipes and equipment, and extending equipment life. It also has high specific heat capacity and no impurity phase change, ensuring accurate temperature control. This utility model embodiment directly uses pre-prepared demineralized water and does not involve the preparation process of the demineralized water. The cooling system mainly includes a main system cooling flow path for the demineralized water flow and several branch pipe working medium flow paths. The main system cooling flow path for the demineralized water flow is: demineralized water tank 2 → shaft seal cooler 1 → slag cooler 5 → deaerator 6, returning to the system for recycling.

[0038] The main cooling flow path of the aforementioned demineralized water system primarily involves the demineralized water tank 2, shaft seal cooler 1, slag cooler 5, and deaerator 6. These three components are connected sequentially via pipelines and undergo tiered cooling using low-temperature demineralized water. The demineralized water tank 2 stores demineralized water, providing a stable flow rate for the cooling system. It has an inlet with a main water pipe 7 serving as a makeup water pipe. It also has an outlet with a main demineralized water pipe 8. The outlet of the main demineralized water pipe 8 is connected in parallel to pipes 9 and 10, which respectively transport the demineralized water to the shaft seal cooler 1 or the slag cooler 5 for heat exchange.

[0039] The shaft seal cooler 1 used in this embodiment is a shell-and-tube heat exchanger, including heat exchange tubes and a shell. Multiple sets of heat exchange tubes are arranged inside the shell. The shell side is used to circulate steam (a mixture containing air) leaking from the shaft seal of the turbine 11, and the tube side is used to circulate low-temperature demineralized water. The low-temperature demineralized water is used to exchange heat and cool the high-temperature steam. Specifically, the tube-side inlet of the shaft seal cooler 1 is connected to the demineralized water main pipe 8 through pipe 19, and its tube-side outlet is connected to the demineralized water header pipe 13 through pipe 212. The outlet end of the demineralized water header pipe 13 is connected to the inlet of the slag cooler 5, and the outlet of the slag cooler 5 is connected to the deaerator 6 through pipe 314.

[0040] In some specific embodiments of this utility model, such as Figure 1 As shown, a fourth pipe 10 is installed at the outlet end of the demineralized water main pipe 8, which is connected in parallel with pipe 9 and serves as a system cooling branch directly connected to the demineralized water main pipe 13. Through pipe 10, a portion of the low-temperature demineralized water is diverted from the demineralized water main pipe 8 and directly enters the slag cooler 5 to regulate the inlet water temperature of the slag cooler 5 and prevent the slag from cracking due to rapid cooling or insufficient heat exchange efficiency.

[0041] The slag cooler 5 is a device used to cool boiler slag. Traditionally, industrial tap water is used for cooling. In some specific embodiments of this invention, the cooling system is equipped with at least two slag coolers 5, and multiple slag coolers 5 are connected in parallel on the demineralized water header 13. The number of coolers in operation is dynamically adjusted according to the boiler slag discharge volume to avoid ash accumulation caused by insufficient water flow rate at low loads. In the event of a single unit failure, the remaining equipment can maintain system operation. Parallel piping reduces flow resistance and ensures balanced pressure at each slag cooler 5. Each slag cooler 5 is equipped with a deaerator 6. Specifically, the outlet of each slag cooler 5 is connected to a deaerator 6 via pipe 14 or a valve group. The deaerator 6 heats the water to allow oxygen to escape, and directly using the high-temperature demineralized water after heat exchange can increase the initial temperature and save energy.

[0042] The demineralized water flow design of this embodiment is based on a temperature gradient. Low-temperature demineralized water preferentially enters the shaft seal cooler 1, where it absorbs heat from the medium-temperature steam and heats up (e.g., to 70-80°C). The heated demineralized water then enters the slag cooler 5, where the increased working fluid temperature buffers the rapid cooling of the slag, preventing slag brittleness and further raising the water temperature to 90-100°C. The high-temperature demineralized water finally enters the deaerator 6, where its initial temperature increase reduces heating steam consumption. If the slag cooler 5 were connected first, the high-temperature slag would cause the demineralized water to vaporize instantly, reducing cooling efficiency and potentially leading to pipeline cavitation damage.

[0043] The demineralized water header 13 is also equipped with a pipe 15 connecting to the condensate tank 4. The outlet of the condensate tank 4 is connected to the deaerator 6 through the condensate header 16, which transports the condensate to the deaerator 6. The condensate tank 4 is used to collect the wastewater from the demineralized water header 13, the overflow water from the deaerator 6, and other low-temperature residual water. It can buffer water hammer impact, recover condensate, and reduce the amount of makeup water.

[0044] The deaerator 6 is equipped with an overflow branch pipe, one end of which is connected to the deaerator 6, and the other end is connected to the overflow main pipe 17. Overflow water or effluent from the deaerator 6 is discharged to the overflow main pipe 17 through the branch pipe. The overflow main pipe 17 has two parallel pipes, a sixth pipe 18 and a seventh pipe 19. Pipe 6 18 connects to the recycled hot water tank 3, and pipe 7 19 connects to the condensate tank 4. Overflow water or effluent from the deaerator 6 is transported to the recycled hot water tank 3 or the condensate tank 4 through pipes 6 18 and 7 19, respectively. The overflow water from the deaerator 6 is diverted through the overflow main pipe 17 to the condensate tank 4 (low-temperature water) or the recycled hot water tank 3 (high-temperature water) for graded recycling according to water quality, thus avoiding heat energy waste.

[0045] The main equipment involved in the steam condensate flow path includes shaft seal cooler 1, recycled hot water tank 3, and deaerator 6. Among them, such as... Figure 2 As shown, the shell-side inlet of the shaft seal cooler 1 is connected to the steam turbine. High-temperature steam is transported to the shell side of the shaft seal cooler 1 through a pipeline. The shell-side outlet of the shaft seal cooler 1 is connected to the reuse hot water tank 3 through pipeline 823. The reuse hot water tank 3 is connected to the deaerator 6 through the reuse hot water header 22. The shaft seal steam is condensed in the shaft seal cooler 1, but its temperature is still higher than that of room temperature water. It exits from its shell-side outlet and enters the reuse hot water tank 3, and then is transported to the deaerator 6 through the reuse hot water header 22 to increase the initial temperature of the deoxygenated water in the deaerator 6. The reuse hot water tank 3 is also equipped with a low-pressure steam pipe 21 for connecting steam from the low-pressure heating network to further heat the water inside; and a main water supply pipe 7 for water replenishment.

[0046] A connecting pipe 20 connects the demineralized water tank 2 and the recycled hot water tank 3 to balance the water pressure and temperature of the two tanks. When the recycled hot water tank 3 overheats, low-temperature demineralized water is added to prevent vaporization, ensuring the thermal stability of the system and reducing emergency discharge.

[0047] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A tiered cooling system for a back pressure compressor shaft seal, characterized in that, It includes a demineralized water tank (2), a shaft seal cooler (1), a slag cooler (5), and a deaerator (6). The outlet of the demineralized water tank (2) is connected to the refrigerant inlet of the shaft seal cooler (1) via the demineralized water main pipe (8); The refrigerant outlet of the shaft seal cooler (1) is connected to the inlet of the slag cooler (5) via a demineralized water header (13); The outlet of the slag cooler (5) is connected to the deaerator (6) via pipe three (14).

2. The back pressure compressor shaft seal stepped cooling system according to claim 1, characterized in that, The shaft seal cooler (1) is a shell-and-tube heat exchanger. Its shell-side inlet is connected to the shaft seal steam pipe of the steam turbine (11), its tube-side water inlet is the refrigerant water inlet, and its tube-side water outlet is the refrigerant water outlet.

3. The back pressure compressor shaft seal stepped cooling system according to claim 2, characterized in that, The cooling system also includes a hot water tank (3), and the shell-side outlet of the shaft seal cooler (1) is connected to the hot water tank (3).

4. The back pressure compressor shaft seal stepped cooling system according to claim 3, characterized in that, The recycled hot water tank (3) is also equipped with a low-pressure steam pipe (21) for receiving steam from the low-pressure heating network; And the hot water main pipe (22) connected to the deaerator (6).

5. The back pressure compressor shaft seal stepped cooling system according to claim 3, characterized in that, A connecting pipe (20) is provided between the demineralized water tank (2) and the recycled hot water tank (3), and a connecting valve is provided on the connecting pipe (20).

6. The back-pressure compressor shaft seal stepped cooling system according to claim 1, characterized in that, Pipeline 1 (9) and Pipeline 4 (10) are connected in parallel on the demineralized water main pipe (8); Pipeline 1 (9) is connected to the refrigerant inlet of the shaft seal cooler (1), and the refrigerant outlet of the shaft seal cooler (1) is connected to the demineralized water main pipe (13) through Pipeline 2 (12); The outlet end of the fourth pipe (10) is connected to the demineralized water main pipe (13).

7. The back pressure compressor shaft seal stepped cooling system according to claim 1, characterized in that, The cooling system includes at least two of the aforementioned slag coolers (5), which are connected in parallel on the demineralized water header (13); Each of the aforementioned slag coolers (5) is equipped with one of the aforementioned deaerators (6).

8. The back pressure compressor shaft seal stepped cooling system according to claim 3, characterized in that, The cooling system also includes a condensate tank (4), the inlet of which is connected to the demineralized water header (13) via pipe five (15), and its outlet is connected to the deaerator (6) via condensate header (16).

9. The back pressure compressor shaft seal stepped cooling system according to claim 8, characterized in that, The deaerator (6) is equipped with an overflow branch pipe, which is connected to the drain tank (4) and the recycled hot water tank (3) respectively through the overflow main pipe (17).

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