Desuperheating water system of steam turbine

Abstract

The invention relates to a steam turbine desuperheating water system. In order to solve the problems of nozzle blockage, poor atomization and the like caused by low condensed water pressure, easy damage of a control valve and poor water quality of an existing desuperheating water system, a desuperheating water control valve (No.13 valve) is additionally arranged to be connected with an original valve in parallel, and front and rear manual valves are additionally arranged; a water source with a small-flow water pump and a check valve are added; a filter screen and an isolation door are additionally arranged on a rear pipeline of the desuperheater; an original spray head is replaced by a two-stage spray head, the first stage is an all-copper four-branch-head atomizing spray head, and the second stage is an axial swirling flow type mechanical atomizing spray nozzle. The cooling water effect can be improved, the power consumption of the condensate pump is reduced, maintenance is convenient, the equipment reliability is improved, the existing problems are effectively solved, the running safety and economical efficiency of a steam turbine are improved, and good application prospects and practical values are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of steam turbines in power plants, and particularly to a desuperheating water system for a steam turbine. Background Art

[0002] In modern large-capacity thermal power generating units, due to the frequency conversion transformation of condensate pumps, the throttling of the outlet throttle valve of the condensate pump is reduced, the condensate pressure is reduced while ensuring the constant condensate flow rate, and the current of the condensate pump is reduced.

[0003] When the steam turbine is operating, there are strict restrictions on the exhaust steam temperature in its low-pressure cylinder. Generally, the temperature must be lower than 80°C. When the exhaust steam temperature of the low-pressure cylinder is higher than 80°C, it is necessary to spray water into the low-pressure cylinder to reduce the exhaust steam temperature of the low-pressure cylinder.

[0004] The desuperheating water system has the following problems:

[0005] (1) The low condensate pressure results in a small desuperheating water flow rate, making it impossible to reduce the exhaust steam temperature of the low-pressure cylinder of the steam turbine below the required value. When the unit is in hot start, the steam temperature is high, and the desuperheating water system requires a large amount of desuperheating water, which requires increasing the condensate pressure, resulting in high power consumption of the condensate pump.

[0006] (2) Due to the large fluctuation of the condensate pressure, the desuperheating water throttle valve operates frequently and is damaged many times, making maintenance difficult.

[0007] (3) When the condensate water quality is poor, the desuperheating water nozzles are blocked many times, resulting in uneven water spraying.

[0008] Due to the large amount of desuperheating water, there is a situation of poor atomization. When the opening of the desuperheating water is large, sometimes it sprays onto the last-stage blades of the steam turbine, causing an increase in the vibration of the steam turbine. Summary of the Invention

[0009] Based on the above purposes, the present invention provides a desuperheating water system for a steam turbine.

[0010] The present invention provides a new desuperheating water system for a steam turbine, adding pipelines, valves, etc. to avoid equipment damage.

[0011] The technical solution adopted by the present invention to solve its technical problems is: adding a desuperheating water regulating valve, increasing the water source for the desuperheating water pipeline, and adding nozzles and filters.

[0012] Add parts 1, 2, 3, 6, 7, 8, 9, 10, 12, 13, 14, 18, 20, and modify parts 17, 19.

[0013] Add a set of desuperheating water regulating valves (No. 13 valve), which are connected in parallel with the original desuperheating water regulating valve (No. 15 valve) of the steam turbine, to avoid the unit being unable to start due to the damage of the desuperheating water regulating valve.

[0014] The desuperheating water regulating valve is equipped with manual valves (valves 12 and 14) before and after, enabling on-line maintenance of the desuperheating water regulating valve during unit operation.

[0015] The original water source of the desuperheating water was condensate. An additional water source was added, and two small-flow pumps (pumps 2 and 3) were installed to increase the water source pressure. Check valves were added at the outlets of the two water sources, allowing them to be put into operation simultaneously and automatically switched. When the small-flow pumps are running, the condensate pump can be adjusted to a low speed by frequency conversion, saving plant electricity.

[0016] A set of filters (filter 9) was added to the desuperheating water pipeline after the desuperheater, and isolation valves (valves 8 and 10) were added before and after to improve the quality of the desuperheating water. When the filter is blocked, on-line isolation and maintenance can be carried out.

[0017] The original set of desuperheating water spray nozzles was replaced with two sets. The first-stage nozzles (nozzles 18 and 20) close to the blades use all-copper 1 / 4-inch four-head atomizing nozzles for large-flow, large-area, and rapid cooling. The second-stage nozzles (nozzles 17 and 19) use axial swirl mechanical atomizing nozzles with good atomization effect and precise temperature control.

[0018] The beneficial effects of the present invention: After the application and transformation of this project, the desuperheating water effect can be effectively improved, the power consumption of the condensate pump can be reduced, maintenance is facilitated, the reliability of the equipment is improved, and economic benefits are increased for the enterprise. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only those of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic structural diagram of the desuperheating water system of the steam turbine in the embodiment of the present invention. Detailed Embodiments

[0021] The present invention will be described in detail below in conjunction with the drawings and specific embodiments. At the same time, it should be noted here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments. For some well-known technologies, those skilled in the art can also adopt other alternative methods for implementation; moreover, the drawing part is only for more specific description of the embodiments and is not intended to specifically limit the present invention.

[0022] It should be noted that in the specification, the mention of "an embodiment", "embodiments", "exemplary embodiments", "some embodiments", etc. indicates that the described embodiments may include specific features, structures or characteristics, but not necessarily every embodiment includes such specific features, structures or characteristics. Additionally, when combining embodiments to describe a specific feature, structure or characteristic, the implementation of such feature, structure or characteristic in combination with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the relevant art.

[0023] Generally, terms can be understood at least in part from their use in context. For example, at least in part depending on the context, the term "one or more" as used herein can be used to describe any feature, structure or characteristic in a singular sense, or can be used to describe a combination of features, structures or characteristics in a plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey a set of exclusive factors, but rather can alternatively, at least in part depending on the context, allow for the existence of other factors that may not be explicitly described.

[0024] Embodiment 1

[0025] Refer to Figure 1

[0026] Overall system composition and connection relationship

[0027] This steam turbine desuperheating water system has been improved in many aspects on the basis of the original system. Each component is connected by pipelines to form a complete desuperheating water system for desuperheating the exhaust steam of the low-pressure cylinder of the steam turbine to ensure that its temperature meets the requirements and guarantee the safe and stable operation of the unit.

[0028] Desuperheating water regulating valve part

[0029] New parallel regulating valve

[0030] Add a set of desuperheating water regulating valves (No. 13 valve), making it parallel to the original steam turbine desuperheating water regulating valve (No. 15 valve). During the operation of the unit, if the original regulating valve (No. 15 valve) is damaged, the No. 13 valve can be immediately put into use to ensure that the unit can start and operate normally, avoid unit shutdown caused by regulating valve failure, and improve the reliability and stability of the system.

[0031] Add manual valves before and after

[0032] Add manual valves (No. 12 and No. 14 valves) before and after the desuperheating water regulating valves (No. 13 and No. 15 valves). When the unit is in operation, if a certain desuperheating water regulating valve needs to be overhauled, the regulating valve can be isolated from the system by closing the manual valves before and after it to achieve on-line overhaul. This not only does not affect the normal operation of the unit, but also can timely maintain the regulating valve, reduce the downtime due to equipment failure, and improve the maintainability and operation efficiency of the unit.

[0033] Water source part

[0034] Add auxiliary water pumps and related components

[0035] The original desuperheating water source was condensate water, and now an additional water source is added. Two small-flow water pumps (2 and 3) are set up. These two water pumps can increase the water source pressure. Check valves are added at the outlets of the two water sources. Their function is to prevent the backflow of water.

[0036] When the small-flow water pumps are running, since they provide sufficient water pressure, the condensate water pump can reduce its speed through frequency conversion adjustment. The advantage of doing this is that on the premise of ensuring the supply of desuperheating water, the power consumption of the condensate water pump is reduced, achieving the purpose of energy conservation. For example, when the unit is operating normally and the demand for desuperheating water is relatively stable, the small-flow water pumps can undertake part of the water pressure boosting task, so that the condensate water pump does not have to be in a high-load operation state all the time, thereby reducing the consumption of plant electricity.

[0037] The two water sources can be put into use simultaneously and can be automatically switched according to the actual needs of the system. For example, when the pressure or quantity of condensate water is insufficient, it is automatically switched to the water source provided by the small-flow water pumps; when the condensate water conditions meet the requirements, it can be switched back to condensate water as the main water source, flexibly adapting to different working conditions and ensuring the stable water supply of the desuperheating water system.

[0038] Filter part

[0039] Add a filter and isolation valves

[0040] Add a set of filters (9) to the desuperheating water pipeline after the desuperheater, and at the same time add front and rear isolation valves (valves 8 and 10). The main function of the filter is to filter impurities in the water and improve the quality of the desuperheating water. When the filter has been running for a period of time and is blocked, the filter can be isolated from the system by closing the front and rear isolation valves, and then maintenance work such as online cleaning or filter replacement can be carried out. This can ensure that the quality of the desuperheating water is always in a good state, prevent problems such as nozzle blockage caused by poor water quality, and thus ensure the normal spraying of the desuperheating water and the desuperheating effect.

[0041] Nozzle part

[0042] Replace with two-stage nozzles

[0043] The original set of desuperheating water nozzles is replaced with two sets. The first-stage nozzles (18 and 20) close to the blades are made of all-copper 4-point four-head atomizing nozzles. These nozzles can achieve large-flow and large-area rapid cooling. When the exhaust steam temperature of the low-pressure cylinder of the steam turbine is relatively high, they can quickly reduce the temperature to make it close to or reach the required range.

[0044] The secondary nozzles (17 and 19) adopt axial swirl mechanical atomizing nozzles. They have good atomization effect and can precisely control the temperature. On the basis of the preliminary temperature reduction by the primary nozzles, the secondary nozzles further finely adjust the temperature, so that the exhaust steam temperature can be more stably controlled below the specified 80°C. The two-stage nozzles cooperate with each other, improving the efficiency and accuracy of desuperheating, and at the same time reducing a series of problems caused by poor atomization, such as the increase in vibration caused by the desuperheating water spraying onto the last-stage blades of the steam turbine.

[0045] System Operation and Maintenance

[0046] Daily Operation

[0047] During the normal operation of the unit, the desuperheating water system automatically adjusts the flow rate and pressure of the desuperheating water according to the exhaust steam temperature of the low-pressure cylinder of the steam turbine. When the exhaust steam temperature rises, by adjusting the opening of the desuperheating water regulating valves (valves No. 13 and 15), the injection volume of the desuperheating water is increased. At the same time, according to the water source pressure situation, the speed of the condensate pump and the start and stop of the small-flow pump are automatically controlled to ensure sufficient water pressure and water volume supply.

[0048] The strainer (9) continuously filters the desuperheating water to prevent impurities from entering the nozzles and causing blockage. The operator regularly checks the pressure difference before and after the strainer. When the pressure difference reaches a certain value, the strainer is cleaned or replaced in time to ensure the normal flow of the desuperheating water.

[0049] Equipment Maintenance and Repair

[0050] The desuperheating water regulating valves (valves No. 13 and 15) and the manual valves (valves No. 12 and 14) before and after them are regularly inspected and maintained to ensure good valve sealing and regulating performance. If problems such as abnormal valve operation or poor sealing are found, repairs or replacements are carried out during the operation gap of the unit or within the allowed shutdown time.

[0051] The small-flow pumps (2 and 3) are regularly maintained, and their operating parameters such as pressure, flow rate, and vibration are checked to ensure their normal operation. At the same time, the check valve is inspected to prevent its failure from causing water flow reversal and affecting the normal operation of the system.

[0052] For the nozzles, their atomization effect and whether the nozzles are blocked are regularly checked. If damage or blockage is found in the primary nozzles (18 and 20) or secondary nozzles (17 and 19), they are cleaned or replaced in time to ensure the desuperheating effect and the safe operation of the steam turbine.

[0053] Through the above specific implementation manners, the desuperheating water system of the present invention can effectively solve the problems existing in the existing desuperheating water system, improve the desuperheating water effect, reduce the power consumption of the condensate pump, facilitate equipment maintenance, and improve the reliability and economy of the entire unit.

[0054] The present invention encompasses any alternatives, modifications, equivalent methods, and solutions that are made to the essence and scope of the present invention. For the public to have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention. However, those skilled in the art can fully understand the present invention even without the description of these details. Additionally, well-known methods, processes, procedures, components, and circuits, etc. are not described in detail to avoid unnecessary confusion to the essence of the present invention.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A desuperheating water system for a steam turbine, characterized in that, Including: Desuperheating water regulating valve part: Add a set of desuperheating water regulating valves (valve No. 13) in parallel with the original desuperheating water regulating valve of the steam turbine (valve No. 15), and add manual valves before and after the desuperheating water regulating valve (valves No. 12 and 14); Water source part: Add a new water source on the basis of the original condensate water source. Install two small-flow pumps (pumps No. 2 and 3) on this water source to increase the water source pressure. Add check valves at the outlets of the two water sources, and they can be put into use simultaneously and automatically switched; Filter part: Add a set of filters (filter No. 9) and isolation valves before and after (valves No. 8 and 10) to the desuperheating water pipeline behind the desuperheater; Spray head part: Replace the original set of desuperheating water spray heads with two sets. The first-stage spray heads (spray heads No. 18 and 20) close to the blades adopt all-copper 1 / 4-inch four-nozzle atomizing spray heads, and the second-stage spray heads (spray heads No. 17 and 19) adopt axial swirl mechanical atomizing nozzles.

2. The desuperheating water system of the steam turbine according to claim 1, wherein The connection method of the desuperheating water regulating valve (valve No. 13) in parallel with the original desuperheating water regulating valve of the steam turbine (valve No. 15) enables valve No. 13 to be put into use to ensure the normal start-up of the unit when the original regulating valve is damaged.

3. The desuperheating water system of a steam turbine according to claim 1, wherein The front and rear manual valves (valves No. 12 and 14) can realize the on-line maintenance of the desuperheating water regulating valve during the operation of the unit.

4. The desuperheating water system of a steam turbine according to claim 1, wherein When the small-flow pumps (pumps No. 2 and 3) are running, the condensate pump can be adjusted to a low speed by frequency conversion to save plant power.

5. The desuperheating water system of a steam turbine according to claim 1, characterized in that, The setting of the filter (filter No. 9) and the isolation valves before and after (valves No. 8 and 10) can isolate and maintain on-line when the filter is blocked, improving the quality of desuperheating water.

6. The desuperheating water system of a steam turbine according to claim 1, characterized in that, The first-stage spray heads (spray heads No. 18 and 20) of the all-copper 1 / 4-inch four-nozzle atomizing spray heads are used for rapid cooling with large flow and large area, and the second-stage spray heads (spray heads No. 17 and 19) of the axial swirl mechanical atomizing nozzles are used for precise temperature control.

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