Recirculation small bypass system of electric feed pump

Abstract

The utility model discloses a small recirculation bypass system of an electric feed pump, and belongs to the technical field of energy conservation and consumption reduction of coal-fired units. According to the system, two stages of bypasses with different pipe diameters are arranged on a water outlet pipeline of a deaerator, a two-stage water return pipeline is formed for a circulation pipeline on each side, it is guaranteed that when peak regulation reaches a specific set value of a unit, water supply recirculation does not need to be started, the model selection size of a regulating valve is far smaller than that of an original recirculation valve, and the system is convenient to use. According to the utility model, the opening frequency of the water supply recirculation valve is reduced, the damage probability of the water supply recirculation regulating valve is reduced, and the high-precision regulating valve is arranged on the small bypass pipeline, so that the regulating precision of water supply recirculation is improved, and the safety and economical efficiency of the unit are further improved. According to the system, the investment is reduced, the fluctuation of water supply can be reduced, the adjusting precision is ensured, the power consumption of the water supply pump is reduced, and the safety and economy of a unit are improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of coal-fired unit energy saving and consumption reduction, and particularly relates to a small recirculation bypass system of electric feed pump. BACKGROUND

[0002] In a thermal power plant, the feed pump as a key auxiliary equipment plays a vital role in the stable operation of the unit. Some thermal power units adopt electric drive to drive the feed pump, that is, an electric motor is used to provide power for the feed pump. However, with the improvement of the operation flexibility of the unit and the frequent participation of the thermal power unit in the peak regulation task, the operating state of the feed pump changes increasingly, and the feed flow often deviates from the rated value, which greatly increases the risk of cavitation of the feed pump.

[0003] In order to ensure the safe operation of the feed pump, the method of frequently opening and closing the feed pump recirculation valve is currently used. However, this operation mode has many drawbacks. First, the feed recirculation valve works in a harsh condition of high temperature, high pressure and large pressure difference before and after for a long time, and frequent adjustment can easily cause the valve to malfunction, such as jamming and failure to open, thereby causing the water pump to trip. Second, frequent adjustment of the valve can cause large fluctuations in the feed flow, which can interfere with the automatic adjustment system of the boiler feed water, and in severe cases, can even cause the feed water automatic control to diverge, threatening the safe operation of the unit. In addition, frequent adjustment can also increase the load of the feed pump motor, resulting in increased power consumption. At the same time, frequent operation of the valve can also accelerate its wear and tear, shorten its service life, and thus increase the maintenance and replacement costs.

[0004] Although measures such as replacing the valve with better cavitation resistance and strengthening routine maintenance have been tried, the effect is not obvious, and the investment is large. CONTENT OF THE UTILITY MODEL

[0005] The utility model aims at overcoming the above-mentioned shortcomings of the prior art, and provides a small recirculation bypass system of electric feed pump to solve the problem that the feed pump recirculation valve needs to be frequently opened and closed in the prior art, which can cause the feed pump to malfunction.

[0006] To achieve the above-mentioned purpose, the utility model adopts the following technical solutions:

[0007] A small recirculation bypass system of electric feed pump, comprising a deaerator, the deaerator is provided with two water outlet pipelines, a first electric feed pump and a second electric feed pump are respectively arranged on the two water outlet pipelines, and the outlets of the first electric feed pump and the second electric feed pump are jointly connected with a high-pressure heater;

[0008] The outlet of the first electric feed pump is connected with a first recirculation pipeline, and the outlet of the second electric feed pump is connected with a second recirculation pipeline;

[0009] The first recirculation pipeline is parallel with a first recirculation bypass and a first recirculation small bypass; the inner diameter of the first recirculation bypass is smaller than that of the first recirculation pipeline, and the inner diameter of the first recirculation small bypass is smaller than that of the first recirculation pipeline.

[0010] The second recirculation pipeline is parallel with a second recirculation bypass and a second recirculation small bypass; the inner diameter of the second recirculation bypass is smaller than that of the second recirculation pipeline, and the inner diameter of the second recirculation small bypass is smaller than that of the second recirculation bypass.

[0011] Further improvement of the utility model lies in that:

[0012] Preferably, the inner diameter of the first recirculation bypass is half of that of the first recirculation pipeline, and the inner diameter of the second recirculation bypass is half of that of the second recirculation pipeline.

[0013] Preferably, the inner diameter of the first recirculation small bypass is one fourth of that of the first recirculation pipeline, and the inner diameter of the second recirculation small bypass is one fourth of that of the second recirculation bypass.

[0014] Preferably, a first recirculation regulating valve is arranged on the first recirculation pipeline, and a second recirculation regulating valve is arranged on the second recirculation pipeline.

[0015] Preferably, a first recirculation bypass regulating valve and a first recirculation bypass flow orifice plate are arranged on the first recirculation bypass, and a second recirculation bypass flow orifice plate and a second recirculation bypass regulating valve are arranged on the second recirculation bypass.

[0016] Preferably, a first small bypass regulating valve and a first small bypass flow orifice plate are arranged on the first recirculation small bypass, and a second small bypass regulating valve and a second small bypass flow orifice plate are arranged on the second recirculation small bypass.

[0017] Preferably, a first electric water supply pump inlet flow orifice plate is arranged before the first electric water supply pump, and a second electric water supply pump inlet flow orifice plate is arranged before the second electric water supply pump.

[0018] Preferably, a first pre-pump is arranged before the first electric water supply pump inlet flow orifice plate, and a second pre-pump is arranged before the second electric water supply pump inlet flow orifice plate.

[0019] Preferably, a first pre-pump inlet butterfly valve is arranged before the first pre-pump, and a second pre-pump inlet butterfly valve is arranged before the second pre-pump.

[0020] Compared with the prior art, the utility model has the following beneficial effects:

[0021] The utility model discloses a kind of electric feedwater pump recirculation small bypass systems, which is provided with two-stage bypass with different pipe diameters on the outlet pipeline of deaerator, forms two-stage backwater pipeline for each side of the circulation pipeline, ensures that when peak shaving to specific set value of unit, feedwater recirculation does not need to be opened again, so that the size of regulating valve selection is much smaller than original recirculation valve, reduces the opening frequency of feedwater recirculation valve, reduces the damage probability of feedwater recirculation regulating valve, and high-precision regulating valve is installed on small bypass pipeline, improves the regulation accuracy of feedwater recirculation, and further improves the safety and economy of unit. The system reduces investment and can reduce the fluctuation of feedwater, ensures the accuracy of regulation, reduces the power consumption of feedwater pump, and improves the safety and economy of unit.

[0022] Further, the designed bypass and recirculation small bypass pipe diameter are 50% of the circulation pipeline respectively, to ensure that feedwater recirculation is not opened again when peak shaving to 50% rated load of unit. The capacity of small bypass pipeline is reduced to 1 / 2 of original recirculation pipeline.

[0023] Further, the designed bypass and recirculation small bypass pipe diameter are 20% of the circulation pipeline respectively, to ensure that feedwater recirculation is not opened again when peak shaving to 20% rated load of unit. The capacity of small bypass pipeline is reduced to 1 / 4 of original recirculation pipeline. ACCURACY

[0024] Figure 1 The system structure diagram of the utility model is shown in the figure;

[0025] Among them: 1, deaerator;2, first recirculation pipeline;3, first recirculation bypass;4, first pre-pump inlet butterfly valve;5, first recirculation regulating valve;6, first pre-pump;7, first recirculation bypass regulating valve;8, first electric feedwater pump inlet flow orifice;9, first recirculation bypass flow orifice;10, first electric feedwater pump;11, high-pressure heater;12, second electric feedwater pump;13, second recirculation bypass flow orifice;14, second electric feedwater pump inlet flow orifice;15, second pre-pump;16, second recirculation bypass regulating valve;17, second recirculation regulating valve;18, second pre-pump inlet butterfly valve;19, second recirculation bypass;20, second recirculation pipeline;21, first recirculation small bypass;22, first small bypass regulating valve;23, first small bypass flow orifice;24, second recirculation small bypass;25, second small bypass regulating valve;26, second small bypass flow orifice. DETAILED DESCRIPTION

[0026] The utility model will be further described in detail as follows in combination with the drawings:

[0027] Embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application and cannot be understood as a limitation of the present application.

[0028] As the problem raised in the background, the feed water pump is a very critical auxiliary machine of the thermal power plant, and the drive mode of the feed water of part of the unit is selected to be electric drive, and a motor is used to provide power for the feed water pump. The unit operation needs high flexibility, and the running state of the electric feed water pump changes greatly. The current thermal power unit frequently adjusts the peak, and the feed water flow deviates from the rated value far away, which increases the risk of cavitation of the feed water pump. In order to ensure the safety of the feed water pump, the feed water pump recirculation valve can only be frequently opened and closed. Since the feed water recirculation valve is long-term worked in the working condition of high temperature, high pressure and large pressure difference before and after, frequent adjustment may cause valve failure, easy to jam and unable to open, causing the pump to trip; it can cause the feed water flow to fluctuate greatly, thereby affecting the automatic adjustment of the boiler feed water, and in severe cases, it may cause the divergence of the feed water automatic control, affecting the safe operation of the unit; it can cause the load of the feed water pump motor to increase, and increase the power consumption; the frequent action of the valve can also accelerate the wear of the valve, increase the maintenance and replacement cost.

[0029] In order to solve the above problems, the utility model discloses a kind of electric feed water pump recirculation small bypass system, and the recirculation small bypass system includes deaerator 1, first recirculation pipeline 2, first recirculation bypass 3, first pre-pump inlet butterfly valve 4, first recirculation regulating valve 5, first pre-pump 6, first recirculation bypass regulating valve 7, first electric feed water pump inlet flow orifice plate 8, first recirculation bypass flow orifice plate 9, first electric feed water pump 10, high-pressure heater 11, second electric feed water pump 12, second recirculation bypass flow orifice plate 13, second electric feed water pump inlet flow orifice plate 14, second pre-pump 15, second recirculation bypass regulating valve 16, second recirculation regulating valve 17, second pre-pump inlet butterfly valve 18, second recirculation bypass 19, second recirculation pipeline 20, first recirculation small bypass 21, first small bypass regulating valve 22, first small bypass flow orifice plate 23, second recirculation small bypass 24, second small bypass regulating valve 25 and second small bypass flow orifice plate 26.

[0030] The outlet of the deaerator 1 is provided with two outlet pipelines, which are a first outlet pipeline and a second outlet pipeline, and the terminals of the two outlet pipelines are collected and then flow to the high-pressure heater.

[0031] The first outlet pipeline is sequentially provided with a first pre-pump inlet butterfly valve 4, a first pre-pump 6, a first electric feed water pump inlet flow orifice plate 8 and a first electric feed water pump 10, and the first outlet pipeline is provided with a first recirculation pipeline 2 at the outlet of the first electric feed water pump 10, and the outlet of the first recirculation pipeline 2 is connected with the inlet of the deaerator 1.

[0032] The first recirculation pipeline 2 is provided with a first recirculation regulating valve 5, and the first recirculation regulating valve 5 is connected in parallel with a first recirculation bypass 3, and the first recirculation bypass 3 is provided with a first recirculation bypass flow orifice plate 9 and a first recirculation bypass regulating valve 7.

[0033] The first recirculation bypass 3 is connected in parallel with a first recirculation small bypass 21, and the first recirculation small bypass 21 is provided with a first small bypass regulating valve 22 and a first small bypass flow orifice plate 23.

[0034] In the above pipeline, the pipe diameter of the first recirculation bypass 3 is half of the diameter of the first recirculation pipeline 2, so that when the feed water passes through the first recirculation pipeline 2, the flow can be directly reduced by half.

[0035] The pipe diameter of the first recirculation small bypass 21 is 1 / 4 of the first recirculation pipeline 2, so that when the feed water passes through the first recirculation pipeline 2, the flow can be directly reduced by 1 / 4.

[0036] The second outlet pipeline is sequentially provided with a second pre-pump inlet butterfly valve 18, a second pre-pump 15, a second electric feed water pump inlet flow orifice plate 14 and a second electric feed water pump 12, and the second outlet pipeline is provided with a second recirculation pipeline 20 at the outlet of the second electric feed water pump 12, and the outlet of the second recirculation pipeline 20 is connected with the inlet of the deaerator 1.

[0037] The second recirculation pipeline 20 is provided with a second recirculation regulating valve 17, and the second recirculation regulating valve 17 is connected in parallel with a second recirculation bypass 19, and the second recirculation bypass 19 is provided with a second recirculation bypass flow orifice plate 13 and a second recirculation bypass regulating valve 16.

[0038] The second recirculation bypass 19 is connected in parallel with a second recirculation small bypass 24, and the second recirculation small bypass 24 is provided with a second small bypass regulating valve 25 and a first small bypass flow orifice plate 26.

[0039] In the above pipeline, the pipe diameter of the second recirculation bypass 19 is half of the diameter of the second recirculation pipeline 20, so that when the feed water passes through the second recirculation pipeline 19, the flow can be directly reduced by half.

[0040] The pipe diameter of the second recirculation small bypass 24 is 1 / 4 of the second recirculation pipeline 20, so that when the feed water passes through the second recirculation small bypass 24, the flow can be directly reduced by 1 / 4.

[0041] The working process of the utility model is:

[0042] The water is heated and deoxygenated in the deaerator 1, enters the first pre-pump 6 and the second pre-pump 15 through the first pre-pump inlet butterfly valve 4 and the second pre-pump inlet butterfly valve 18 respectively to ensure that the water pump has sufficient NPSH, the inlet flow of the first electric water pump 10 and the second electric water pump 12 is measured through the first electric water pump inlet flow orifice plate 8 and the second electric water pump inlet flow orifice plate 14, and the water is finally pressurized into the first electric water pump 10 and the second electric water pump 12, and is combined into the water main pipe and enters the high-pressure heater 11.

[0043] Before the small bypass is added, when the first electric water pump inlet flow orifice plate 8 and the second electric water pump inlet flow orifice plate 14 detect that the water flow is lower than 50% of the rated water flow, the first recirculation regulating valve 5 and the second recirculation regulating valve 17 are generally opened, part of the water is recycled back to the deaerator 1 through the first recirculation pipeline 2 and the second recirculation pipeline 20, the flow into the water pump is ensured to be higher than 50%, and vaporization of the water in the pump is prevented, and even water pump vibration and water interruption accidents are prevented.

[0044] After the first recirculation bypass 3 and the second recirculation bypass 19 are added, when the water flow is lower than 50% of the rated water flow, the first recirculation regulating valve 5, the first small bypass regulating valve 22, the second recirculation regulating valve 17 and the second small bypass regulating valve 25 are closed, the first recirculation small bypass regulating valve 7 and the second recirculation bypass regulating valve 16 are opened, part of the water is recycled back to the deaerator through the first recirculation small bypass 3 and the second recirculation regulating valve 17, the circulating water no longer passes through the first recirculation pipeline 2 and the second recirculation pipeline 20, and the circulating water is recycled back to the deaerator through the first recirculation bypass 3 and the second recirculation bypass 19, because the diameters of the first recirculation bypass 3 and the second recirculation bypass 19 are half of the diameters of the corresponding circulating pipelines, the flow of the circulating water can be reduced, the recirculation flow is accurately controlled through the first recirculation small bypass flow orifice plate 9 and the second recirculation small bypass flow orifice plate 13, and the safety and economy of the unit operation are improved.

[0045] Further, after the first recirculation small bypass 21 and the second recirculation small bypass 24 are added, when the feed water flow is less than 30% of the rated feed water flow, the first recirculation regulating valve 5, the first recirculation bypass regulating valve 7, the second recirculation regulating valve 17 and the second recirculation bypass regulating valve 16 are closed, and the first small bypass regulating valve 22 and the second small bypass regulating valve 25 are opened, part of the feed water re-enters the deaerator circulation through the first recirculation small bypass 21 and the second recirculation small bypass 24, and due to the fact that the diameters of the first recirculation bypass 3 and the second recirculation bypass 19 are 1 / 4 of the diameters of the corresponding circulation pipelines, the flow of the circulating water can be reduced, and the recirculation flow is accurately controlled through the first small bypass flow orifice plate 23 and the second small bypass flow orifice plate 26, thereby improving the safety and economy of the unit operation.

[0046] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the features limited as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, "a plurality of" means two or more, unless otherwise specified. In the description of the present application, "above" or "below" of a first feature relative to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature therebetween.

[0047] In the description of the present application, "above", "upper" and "upper surface" of a first feature relative to a second feature include that the first feature is directly above and obliquely above the second feature, or only means that the first feature is higher in horizontal height than the second feature.

[0048] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or indirectly connected through an intermediate medium; can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0049] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0050] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made thereto without departing from the principles and spirit of the present application, and the scope of the present application is defined by the claims and their equivalents.

[0051] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An electrically driven feedwater pump recirculation small bypass system characterized by, Including deaerator (1), the deaerator (1) is provided with two water outlet pipelines, two water outlet pipelines are respectively provided with first electric feed water pump (10) and second electric feed water pump (12), the outlet of first electric feed water pump (10) and second electric feed water pump (12) is connected with high pressure heater (11) in common; The outlet of the first electric feed water pump (10) is connected with a first recirculation pipeline (2), and the outlet of the second electric feed water pump (12) is connected with a second recirculation pipeline (20). The first recirculation pipeline (2) is connected with a first recirculation bypass (3) and a first recirculation small bypass (21) in parallel; the inner diameter of the first recirculation bypass (3) is smaller than the inner diameter of the first recirculation pipeline (2), and the inner diameter of the first recirculation small bypass (21) is smaller than the inner diameter of the first recirculation pipeline (2). The second recirculation pipeline (20) is connected with a second recirculation bypass (19) and a second recirculation small bypass (24) in parallel; the inner diameter of the second recirculation bypass (19) is smaller than the inner diameter of the second recirculation pipeline (20), and the inner diameter of the second recirculation small bypass (24) is smaller than the inner diameter of the second recirculation bypass (19).

2. An electrically driven feed water pump recirculation small bypass system as claimed in claim 1, characterized in that The inner diameter of the first recirculation bypass (3) is half of the inner diameter of the first recirculation pipeline (2); the inner diameter of the second recirculation bypass (19) is half of the inner diameter of the second recirculation pipeline (20).

3. An electrically driven feed water pump recirculation small bypass system as claimed in claim 1, characterized in that The inner diameter of the first recirculation small bypass (21) is one fourth of the inner diameter of the first recirculation pipeline (2); the inner diameter of the second recirculation small bypass (24) is one fourth of the inner diameter of the second recirculation bypass (19).

4. A small recirculation bypass system for an electric water pump as set forth in claim 1, characterized in that The first recirculation pipeline (2) is provided with a first recirculation regulating valve (5); the second recirculation pipeline (20) is provided with a second recirculation regulating valve (17).

5. A small recirculation bypass system for an electric water pump as set forth in claim 1, characterized in that, The first recirculation bypass (3) is provided with a first recirculation bypass regulating valve (7) and a first recirculation bypass flow orifice (9); the second recirculation bypass (19) is provided with a second recirculation bypass flow orifice (13) and a second recirculation bypass regulating valve (16).

6. A small recirculation bypass system for an electric water pump as set forth in claim 1, characterized in that, The first recirculation small bypass (21) is provided with a first small bypass regulating valve (22) and a first small bypass flow orifice (23).

7. A small recirculation bypass system for an electric water pump as set forth in claim 1, characterized in that, The second recirculation small bypass (24) is provided with a second small bypass regulating valve (25) and a second small bypass flow orifice (26).

8. An electrically driven water feed pump recirculation small bypass system according to any one of claims 1-7, characterized in that, The water outlet pipeline is provided with a first electric feed water pump inlet flow orifice (8) before the first electric feed water pump (10); the water outlet pipeline is provided with a second electric feed water pump inlet flow orifice (14) before the second electric feed water pump (12).

9. An electrically driven feed water pump recirculation small bypass system as claimed in claim 8, characterized in that The first electric feed water pump inlet flow orifice (8) is provided with a first pre-pump (6) before it; the second electric feed water pump inlet flow orifice (14) is provided with a second pre-pump (15) before it.

10. A small recirculation bypass system for an electric water pump as set forth in claim 9, characterized in that The first pre-pump (6) is provided with a first pre-pump inlet butterfly valve (4) before it; the second pre-pump (15) is provided with a second pre-pump inlet butterfly valve (18) before it.

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