A method for adjusting the feed water temperature under deep peak shaving working condition of a coal-fired unit

Abstract

The present application relates to the technical field of deep peak regulation control of coal-fired units, and discloses an adjusting method for improving feed water temperature under deep peak regulation working condition of a coal-fired unit, comprising: confirming whether the coal-fired unit reaches a peak regulation standard; entering a deep peak regulation mode to adjust the opening degree of a medium-pressure cylinder governing valve when the coal-fired unit reaches the peak regulation standard; the deep peak regulation mode comprises: presetting a medium-pressure cylinder governing valve opening degree value based on the pressure of a high-pressure cylinder exhaust pipe; and adjusting the medium-pressure cylinder governing valve opening degree to the preset medium-pressure cylinder governing valve opening degree value step by step. The present application does not make great changes to the steam-water thermodynamic cycle of the coal-fired unit, and improves the heat exchange capacity of the high-pressure heater, reduces the heat exchange loss in the area of the tail flue economizer, and improves the feed water temperature by adjusting the medium-pressure cylinder governing valve opening degree under the deep peak regulation working condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deep peak regulation control of coal-fired units, and particularly relates to a method for adjusting the temperature of feed water in a deep peak regulation condition of a coal-fired unit. BACKGROUND

[0002] In recent years, the installed capacity of new energy power generation in China has been continuously expanded, and the traditional coal power capacity is in excess, and the grid peak regulation contradiction is very prominent. When the proportion of new energy in the power grid gradually expands, the demand for peak regulation power sources also gradually increases. Compared with new energy and other power sources, coal power has good peak regulation performance. In order to adapt to the new situation and new situation of the development of the power grid, coal-fired units need to tap the peak regulation potential of the units and improve the flexibility of unit operation.

[0003] At present, the selective catalytic reduction technology (SCR) is generally used in the denitration system of coal-fired power plants in China. The basic principle of the technology is that ammonia is sprayed into the flue, mixed with the original flue gas, and then enters the reaction tower. Under the action of the catalyst, the NOx in the flue gas selectively reacts to generate harmless ammonia and water. The technology is stable and reliable, but the reaction temperature needs to be controlled between 300-450℃. When the unit is in a deep peak regulation condition, the heat load of the furnace is low, and the flue gas temperature of the tail flue is low, which is often lower than the lower limit of the required reaction temperature. The denitration efficiency is low, the ammonia consumption is large, the ammonia escape rate is too high, and the ammonium bisulfate is easy to be generated to cause the air preheater to be blocked. In severe cases, the unit may be shut down due to environmental protection exceeding the standard.

[0004] At present, the methods for increasing the temperature of feed water in a deep peak regulation condition include: 1. Increasing a No. 0 high pressure heater to increase the temperature of feed water. This method can improve the efficiency of the heater and reduce the heat consumption rate of the steam turbine, but the ability to increase the temperature of feed water in a deep peak regulation condition is limited (<5℃), and the modification cost is very high; 2. Steam source modification of the heater. In a deep peak regulation condition, high-quality steam is used to heat the feed water. This method not only has a large modification cost, but also affects the operation of the steam turbine away from the design condition, which greatly affects the safety. Therefore, it is of great significance to study a method for increasing the temperature of main feed water in a deep peak regulation condition of a unit, reducing the heat loss in the region of the tail flue economizer, and improving the deep peak regulation capacity of the unit and the safety margin of the unit operation. SUMMARY

[0005] The present application provides a method for adjusting the temperature of feed water in a deep peak regulation condition of a coal-fired unit, which does not make large changes to the steam-water thermal cycle of the coal-fired unit. By adjusting the opening degree of the medium-pressure cylinder regulating valve to increase the heat exchange capacity of the high-pressure heater in a deep peak regulation condition, the heat loss in the region of the tail flue economizer is reduced, and the temperature of the feed water is increased.

[0006] The application adopts the technology to achieve the above-mentioned purpose, and provides the following scheme: the application provides an adjusting method for improving feed water temperature under deep peak regulation of a coal-fired unit, comprising:

[0007] Confirming whether the coal-fired unit reaches a peak regulation standard;

[0008] When the coal-fired unit reaches the peak regulation standard, entering a deep peak regulation mode to adjust a medium-pressure cylinder governing valve opening degree;

[0009] The deep peak regulation mode comprises:

[0010] Presetting the medium-pressure cylinder governing valve opening degree value based on the pressure of a high-pressure cylinder exhaust pipe;

[0011] Gradually adjusting the medium-pressure cylinder governing valve opening degree to the preset medium-pressure cylinder governing valve opening degree value.

[0012] In one of the embodiments, the peak regulation standard is:

[0013] The coal-fired unit is in a normal working state;

[0014] The temperature in the first extraction pipe reaches a minimum temperature threshold value of the first heater for heating the feed water, and the temperature in the second extraction pipe reaches a minimum temperature threshold value of the second heater for heating the feed water.

[0015] In one of the embodiments, when the medium-pressure cylinder governing valve opening degree is gradually adjusted to the preset medium-pressure cylinder governing valve opening degree value, it is detected whether a plurality of parameter indexes are normal, and when any parameter index is not normal, the opening degree of the medium-pressure cylinder governing valve is stopped from being adjusted and an alarm is issued.

[0016] In one of the embodiments, the parameter indexes comprise axial displacement, bearing shell vibration, thrust pad temperature, reheater pressure, extraction pressure, medium-pressure cylinder exhaust temperature, low-pressure cylinder static blade retaining ring, and low-pressure cylinder exhaust temperature.

[0017] In one of the embodiments, the presetting of the medium-pressure cylinder governing valve opening degree value based on the pressure of the high-pressure cylinder exhaust pipe comprises:

[0018] Real-time detection of the pressure P of the high-pressure cylinder exhaust pipe;

[0019] Based on the relationship between the pressure P and each preset pressure, the opening degree value G of the medium-pressure cylinder governing valve is set.

[0020] In one of the embodiments, a preset pressure matrix P0 is preset, and P0=(P1, P2, P3, P4) is set, wherein P1 is a first preset pressure, P2 is a second preset pressure, P3 is a third preset pressure, and P4 is a fourth preset pressure, and P1

[0021] A preset opening degree value matrix G0 is preset, and G0=(G1, G2, G3, G4) is set, wherein G1 is a first preset opening degree value, G2 is a second preset opening degree value, G3 is a third preset opening degree value, and G4 is a fourth preset opening degree value, and G1

[0022] The opening degree value G is set according to the relationship between the pressure P and each preset pressure:

[0023] When P

[0024] When P1≤P

[0025] When P2≤P

[0026] When P3≤P

[0027] In one of the embodiments, the step of gradually adjusting the opening degree of the intermediate-pressure cylinder governor valve to the preset opening degree value of the intermediate-pressure cylinder governor valve comprises:

[0028] The opening degree of the intermediate-pressure cylinder governor valve is gradually adjusted to the preset opening degree value of the intermediate-pressure cylinder governor valve within a preset adjustment time;

[0029] The preset opening degree value of the intermediate-pressure cylinder governor valve is within a range of 0.5% to 3% of the opening degree, the preset adjustment time is 30 to 60 seconds, and each step of adjustment is 0.1 to 0.2% of the opening degree.

[0030] In one of the embodiments, the deep peak-shaving mode further comprises: the first gas extraction assembly and the second gas extraction assembly are alternately normally operated.

[0031] The first gas extraction assembly comprises a first gas extraction pipeline, and a first electromagnetic valve is installed on the first gas extraction pipeline.

[0032] The second gas extraction assembly comprises a second gas extraction pipeline, and a second electromagnetic valve is installed on the second gas extraction pipeline.

[0033] In one of the embodiments, the first gas extraction assembly and the second gas extraction assembly are alternately normally operated, comprising:

[0034] A first pressure value when the heating temperature of the first heater reaches a first minimum temperature threshold and a second pressure value when the heating temperature of the second heater reaches a second minimum temperature threshold are determined respectively;

[0035] A first minimum opening degree threshold of the first electromagnetic valve on the first gas extraction pipeline and a second minimum opening degree threshold of the second electromagnetic valve on the second gas extraction pipeline are determined based on the first pressure value and the second pressure value.

[0036] detecting a first extraction pressure of the first extraction pipeline and a second extraction pressure of the second extraction pipeline in real time;

[0037] adjusting the opening degree of the first electromagnetic valve and the opening degree of the second electromagnetic valve based on the relationship between the first extraction pressure and the first pressure value and the relationship between the second extraction pressure and the second pressure value.

[0038] In one embodiment, adjusting the opening degree of the first electromagnetic valve and the opening degree of the second electromagnetic valve based on the relationship between the first extraction pressure and the first pressure value and the relationship between the second extraction pressure and the second pressure value comprises:

[0039] maintaining the first electromagnetic valve on the first extraction pipeline at a first minimum opening threshold value and maintaining the second electromagnetic valve on the second extraction pipeline at a normal opening degree within a first preset time, the first preset time being based on the time for the temperature of the feed water heated by the first heater to decrease from an initial temperature to a first minimum temperature threshold value;

[0040] maintaining the second electromagnetic valve on the second extraction pipeline at a second minimum opening threshold value and maintaining the first electromagnetic valve on the first extraction pipeline at a normal opening degree within a second preset time, the second preset time being based on the time for the temperature of the feed water heated by the second heater to decrease from an initial temperature to a second minimum temperature threshold value.

[0041] Technical effects of the present application: by adjusting the opening degree of the intermediate pressure cylinder governing valve after the coal-fired unit reaches the peak shaving standard and enters the deep peak shaving mode, and by presetting the intermediate pressure cylinder governing valve opening degree value based on the pressure of the high pressure cylinder exhaust pipeline, the accuracy of the preset intermediate pressure cylinder governing valve opening degree value is improved; the intermediate pressure cylinder governing valve opening degree is adjusted step by step to the preset intermediate pressure cylinder governing valve opening degree value, avoiding sudden adjustment of the intermediate pressure cylinder governing valve opening degree and causing sudden changes in the pressure of the first extraction pipeline and the high pressure cylinder exhaust pipeline. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0043] Figure 1 is a schematic diagram of the adjustment method for improving the temperature of the feed water under the deep peak shaving condition of the coal-fired unit provided by the embodiments of the present application;

[0044] Figure 2 is a schematic diagram of the position adjusting device provided by the embodiments of the present application;

[0045] Figure 3 is a schematic diagram of the rainwater collection and treatment device provided by the embodiments of the present application;

[0046] Figure 4 is a schematic view of a drying device provided by an embodiment of the present application;

[0047] Figure 5 is a flow chart of a cleaning method of a wind turbine nacelle provided by an embodiment of the present application. DETAILED DESCRIPTION

[0048] The specific embodiments of the present application will be further described in conjunction with the drawings and embodiments. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0049] In the description of the present application, it needs to be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship 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 device or element 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.

[0050] The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified and limited, the meaning of "a plurality of" is two or more.

[0051] In the description of the present application, it needs to be explained that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside 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.

[0052] As shown in Figure 2 The existing main steam 1 passes through the high-pressure main valve 2 and the high-pressure regulating valve 3 to enter the high-pressure cylinder 4 to do work. The steam after the work of the intermediate stage part enters the first high-pressure heater to heat the feed water through the first extraction pipe 8. The remaining steam enters the high-pressure cylinder exhaust pipe 6 through the high-pressure cylinder exhaust check valve 5 to be sent to the reheater for heating. Part of the high-pressure exhaust steam enters the second high-pressure heater to heat the feed water through the second extraction pipe 7. The reheated steam 9 after the reheater is heated enters the medium-pressure cylinder 12 to do work through the medium-pressure main valve 10 and the medium-pressure cylinder regulating valve 11.

[0053] After the medium-pressure cylinder governing valve 11, 13 is closed, the throttling effect of the medium-pressure cylinder governing valve will cause the steam pressure before the governing valve to rise, and the pressure of the high-pressure cylinder exhaust pipe 6 and the first steam extraction pipe 8 will also rise accordingly. Under the same heat load, the steam pressure entering the first and second heaters is higher, the flow is larger, the work capacity is stronger, and the temperature rise of the feed water is higher, thereby reducing the heat exchange amount in the economizer area, increasing the flue gas temperature before the SCR, ensuring the working efficiency of the denitration device, and avoiding unsafe events such as environmental protection exceeding the standard and air preheater blockage.

[0054] The improvement of the prior art is that a first electromagnetic valve is installed on the first steam extraction pipe, and a second electromagnetic valve is installed on the second steam extraction pipe; and a detection device is installed to detect parameters such as axial displacement, bearing shell vibration, thrust pad temperature, reheater pressure, extraction pressure, medium-pressure cylinder exhaust temperature, low-pressure cylinder static blade retaining ring, and low-pressure cylinder exhaust temperature.

[0055] As shown in Figures 1-3 The embodiment discloses an adjustment method for improving feed water temperature in a deep peak regulation mode of a coal-fired unit, which comprises the following steps:

[0056] In step S001, it is determined whether the coal-fired unit reaches a peak regulation standard.

[0057] In step S002, when the coal-fired unit reaches the peak regulation standard, the medium-pressure cylinder governing valve opening degree is adjusted in the deep peak regulation mode.

[0058] The deep peak regulation mode comprises the following steps:

[0059] In step S10, the medium-pressure cylinder governing valve opening degree value is preset based on the pressure of the high-pressure cylinder exhaust pipe.

[0060] In step S20, the medium-pressure cylinder governing valve opening degree is adjusted to the preset medium-pressure cylinder governing valve opening degree value step by step.

[0061] It can be understood that, in the above embodiment, the medium-pressure cylinder governing valve opening degree is adjusted in the deep peak regulation mode when the coal-fired unit reaches the peak regulation standard, the medium-pressure cylinder governing valve opening degree value is preset based on the pressure of the high-pressure cylinder exhaust pipe, the accuracy of the preset medium-pressure cylinder governing valve opening degree value is improved, and the medium-pressure cylinder governing valve opening degree is adjusted to the preset medium-pressure cylinder governing valve opening degree value step by step, thereby avoiding direct adjustment of the medium-pressure cylinder governing valve opening degree and causing sudden changes in the pressure of the first steam extraction pipe and the high-pressure cylinder exhaust pipe.

[0062] In some specific embodiments, the peak regulation standard is that the coal-fired unit is in a normal working state.

[0063] The temperature in the first steam extraction pipe reaches a minimum temperature threshold of the first heater for heating feed water, and the temperature in the second steam extraction pipe reaches a minimum temperature threshold of the second heater for heating feed water.

[0064] It is understandable that in the above embodiments, after the coal-fired unit is in normal working condition, it can stably heat the feedwater to the first heater and the second heater and then perform deep peak shaving to avoid subsequent deep peak shaving failure.

[0065] In some specific embodiments, when the opening of the intermediate pressure cylinder valve is adjusted step by step to the preset opening value, several parameters are checked to see if they are normal. If any parameter is abnormal, the adjustment of the opening of the intermediate pressure cylinder valve is stopped and an alarm is issued.

[0066] The parameters include axial displacement, bearing vibration, thrust bearing temperature, reheater pressure, extraction pressure, intermediate pressure cylinder exhaust temperature, low pressure cylinder stator ring, and low pressure cylinder exhaust temperature.

[0067] It is understood that in the above embodiments, the normal parameters are: axial displacement within the range of -0.5mm to +0.5mm, bearing vibration ≤9.3mm / s, thrust bearing temperature ≤120℃, reheater pressure ≤6.06MPa, first extraction pressure ≤8.03MPa, second extraction pressure ≤6.08MPa, intermediate pressure cylinder exhaust temperature ≤295℃, low pressure cylinder stationary vane retaining ring ≤180℃ or low pressure cylinder exhaust temperature ≤90℃.

[0068] It should be noted that the above-mentioned normal parameter indicators can be selected by those skilled in the art based on the actual situation of the specific coal-fired unit, and this does not affect the scope of protection of this application.

[0069] like Figure 4 As shown, in some specific embodiments, in step S10, the preset opening value of the intermediate pressure cylinder regulating valve based on the pressure of the high-pressure cylinder exhaust pipe includes:

[0070] Step S11: Real-time monitoring of the pressure P in the high-pressure cylinder exhaust pipe;

[0071] Step S12: Set the opening value G of the intermediate pressure cylinder regulating valve based on the relationship between pressure P and each preset pressure.

[0072] Preferably, a preset pressure matrix P0 is preset, and P0 = (P1, P2, P3, P4), where P1 is the first preset pressure, P2 is the second preset pressure, P3 is the third preset pressure, and P4 is the fourth preset pressure, where P1 < P2 < P3 < P4.

[0073] A preset opening value matrix G0 is set in advance, and G0 = (G1, G2, G3, G4), where G1 is the first preset opening value, G2 is the second preset opening value, G3 is the third preset opening value, G4 is the fourth preset opening value, and G1 < G2 < G3 < G4.

[0074] The opening degree value G is set according to the relationship between the pressure P and each preset pressure:

[0075] When P < P1, the first preset opening degree value G1 is selected as the opening degree value G;

[0076] When P1≤P < P2, the second preset opening degree value G2 is selected as the opening degree value G;

[0077] When P2≤P < P3, the third preset opening degree value G3 is selected as the opening degree value G;

[0078] When P3≤P < P4, the fourth preset opening degree value G4 is selected as the opening degree value G.

[0079] It can be understood that in the above embodiment, the opening degree value G is set according to the relationship between the pressure P and each preset pressure, the accuracy of setting the opening degree value G is improved, and the pressure of the first steam extraction pipe and the high-pressure cylinder exhaust pipe is prevented from suddenly changing due to the failure of adjusting the opening degree of the pressure cylinder, or the heating water temperature of the first high-pressure heater and the heating water temperature of the second high-pressure heater are prevented from being too low.

[0080] Specifically, it is assumed that the pressure P of the high-pressure cylinder exhaust pipe is in the range of 6-8 MPa, and the adjustment range of the opening degree value G is 1%-3% of the opening degree.

[0081] The preset pressure matrix P0 is set in advance, and P0=(6.5MPA, 7MPA, 7.5MPA, 8MPA) is set, wherein 6.5MPA is the first preset pressure, 7MPA is the second preset pressure, 7.5MPA is the third preset pressure, and 8MPA is the fourth preset pressure, and 6.0MP < 6.5MPA < 7MPA < 7.5MPA < 8MPA;

[0082] The preset opening degree value matrix G0 is set in advance, and G0=(99%, 98.5%, 98%, 97.5%) is set, wherein 99% is the first preset opening degree value, 98.5% is the second preset opening degree value, 98% is the third preset opening degree value, and 97.5% is the fourth preset opening degree value, and 99% < 98.5% < 98% < 97.5%;

[0083] The opening degree value G is set according to the relationship between the pressure P and each preset pressure:

[0084] When P < 6.5MPA, the first preset opening degree value 99% is selected as the opening degree value G;

[0085] When 6.5MPA≤P < 7MPA, the second preset opening degree value 98.5% is selected as the opening degree value G;

[0086] When 7MPA≤P < 7.5MPA, the third preset opening degree value 98% is selected as the opening degree value G;

[0087] When 7.5MPA≤P<8MPA, the fourth preset opening value of 97.5% is selected as the opening value G.

[0088] It should be noted that the above preferred embodiments are only one specific implementation method proposed in this application. Those skilled in the art can select other preset pressure matrix P0 and preset opening value matrix G0 according to the actual situation, which does not affect the protection scope of this application.

[0089] In some specific embodiments, in step S20, the opening degree of the intermediate pressure cylinder regulating valve is adjusted step by step to a preset intermediate pressure cylinder regulating valve opening value, including:

[0090] Within the preset adjustment time, the opening of the intermediate pressure cylinder valve is gradually adjusted to the preset intermediate pressure cylinder valve opening value;

[0091] The preset valve opening value of the intermediate pressure cylinder is within the range of 0.5%-3%; the preset adjustment time is 30-6.50 seconds; and the valve opening is reduced by 0.1-0.2% for each stage.

[0092] It is understandable that in the above embodiments, in order to prevent sudden adjustment of the intermediate pressure cylinder valve opening from causing a sudden change in pressure in the first extraction steam pipe and the high pressure cylinder exhaust steam pipe, the intermediate pressure cylinder valve opening is gradually adjusted to the preset intermediate pressure cylinder valve opening value within a preset adjustment time.

[0093] It should be noted that the preset intermediate pressure cylinder valve opening value is within the range of 0.5%-3%; the preset adjustment time is 30-6.50 seconds; and the valve opening is reduced by 0.1-0.2% at each stage. Other range values ​​can be selected by those skilled in the art based on the actual situation of the specific coal-fired unit, which does not affect the scope of protection of this application.

[0094] In some specific embodiments, the deep peak shaving mode further includes: step S30, where the first suction component and the second suction component operate normally alternately;

[0095] The first air extraction assembly includes a first air extraction pipe, and a first solenoid valve is installed on the first air extraction pipe.

[0096] The second air extraction assembly includes a second air extraction pipe, on which a second solenoid valve is installed.

[0097] It is understood that in the above embodiments, by alternately operating the first and second extraction components, a portion of the energy of the steam-water thermodynamic cycle of the coal-fired unit is transferred in time and space, thereby improving the efficiency of the heater and reducing the heat consumption rate of the turbine.

[0098] like Figure 5 As shown, in some specific embodiments, in step S30, the first suction assembly and the second suction assembly operate alternately and normally, including:

[0099] Step S31, respectively determine the first pressure value when the first heater heating feed water temperature reaches the first minimum temperature threshold, the second pressure value when the second heater heating feed water temperature reaches the second minimum temperature threshold;

[0100] Step S32, based on the first pressure value and the second pressure value to determine the minimum opening threshold of the first electromagnetic valve on the first suction pipe, the second opening threshold of the second electromagnetic valve on the second suction pipe;

[0101] Step S33, real-time detection of the first suction pressure of the first suction pipe and the second suction pressure of the second suction pipe;

[0102] Step S34, based on the relationship between the first suction pressure and the first pressure value, the relationship between the second suction pressure and the second pressure value, adjusting the opening of the first electromagnetic valve, the opening of the second electromagnetic valve.

[0103] Specifically, in step S34, based on the relationship between the first suction pressure and the first pressure value, the relationship between the second suction pressure and the second pressure value, adjusting the opening of the first electromagnetic valve, the opening of the second electromagnetic valve, comprising:

[0104] Step S341, within the first preset time, the first electromagnetic valve on the first suction pipe is kept at the first minimum opening threshold; the second electromagnetic valve on the second suction pipe is kept at the normal opening; the first preset time is based on the time when the first heater heating feed water temperature decreases from the initial temperature to the first minimum temperature threshold;

[0105] Step S342, within the second preset time, the second electromagnetic valve on the second suction pipe is kept at the second minimum opening threshold; the first electromagnetic valve on the first suction pipe is kept at the normal opening; the second preset time is based on the time when the second heater heating feed water temperature decreases from the initial temperature to the second minimum temperature threshold.

[0106] It can be understood that in the above embodiment, by adjusting the opening of the first electromagnetic valve and the opening of the second electromagnetic valve within the preset time, the first suction assembly and the second suction assembly are alternately normally operated, and the heat consumption rate of the steam turbine is reduced on the basis of meeting the normal heating of the feed water.

[0107] The adjustment method for improving the feed water temperature under the deep peak shaving working condition of the coal-fired unit has the following advantages:

[0108] 1. Only the operation mode of the existing equipment needs to be adjusted, without the need for new equipment or technical transformation, saving cost.

[0109] 2. The operation method is simple, and one-key automatic operation can be realized throughout the whole process, the valve limit is automatically limited throughout the whole process, the related parameters are checked, personnel misoperation is avoided, and the normal operation of the main parameters of the unit is ensured.

[0110] 3. In deep peak regulation mode, by gradually closing the small adjustment of intermediate pressure cylinder governing valve to increase the heat transfer of high pressure heater, the feed water temperature can be increased, which can effectively increase the inlet flue gas temperature before SCR, avoid environmental standard exceeding or air preheater blocking, and improve the safety margin of the unit. At the same time, the use of ammonia can be reduced, and the economy in deep peak regulation mode can be improved.

[0111] It should be understood that although each step in the flowchart of each embodiment of the present application is shown in sequence according to the arrow, these steps are not necessarily executed in sequence according to the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other sequences. Moreover, at least part of the steps in each embodiment can include multiple sub-steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these sub-steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least part of other steps or sub-steps or stages of other steps.

[0112] Those skilled in the art can understand that the above are only preferred embodiments of the present application, and are not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments. For those skilled in the art, the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced equivalently. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for adjusting feedwater temperature under deep peak-shaving conditions in a coal-fired power unit, characterized in that, include: Confirm whether the coal-fired power units have reached the peak-shaving standard; When a coal-fired power unit reaches the peak shaving standard, it enters the deep peak shaving mode to adjust the opening of the intermediate pressure cylinder regulating valve. The deep peak shaving mode includes: The pressure preset of the high-pressure cylinder exhaust pipe is used to determine the opening value of the intermediate-pressure cylinder regulating valve. Adjust the opening of the intermediate pressure cylinder valve step by step to the preset opening value of the intermediate pressure cylinder valve; When adjusting the opening of the intermediate pressure cylinder valve step by step to the preset opening value, several parameters are checked to see if they are normal. If any parameter is abnormal, the adjustment of the opening of the intermediate pressure cylinder valve is stopped and an alarm is issued. The parameters include axial displacement, bearing vibration, thrust bearing temperature, reheater pressure, extraction pressure, intermediate pressure cylinder exhaust temperature, low pressure cylinder stator ring, and low pressure cylinder exhaust temperature. The pressure preset intermediate pressure cylinder regulating valve opening value based on the high-pressure cylinder exhaust pipeline includes: Real-time monitoring of the pressure P in the high-pressure cylinder exhaust pipe; The opening value G of the intermediate pressure cylinder regulating valve is set based on the relationship between the pressure P and each preset pressure. A preset pressure matrix P0 is set in advance, and P0 = (P1, P2, P3, P4), where P1 is the first preset pressure, P2 is the second preset pressure, P3 is the third preset pressure, and P4 is the fourth preset pressure, where P1 < P2 < P3 < P4. A preset opening value matrix G0 is set in advance, and G0 = (G1, G2, G3, G4), where G1 is the first preset opening value, G2 is the second preset opening value, G3 is the third preset opening value, G4 is the fourth preset opening value, and G1 < G2 < G3 < G4. The opening value G is set according to the relationship between the pressure P and each preset pressure: When P < P1, the first preset opening value G1 is selected as the opening value G; When P1≤P<P2, the second preset opening value G2 is selected as the opening value G; When P2≤P<P3, the third preset opening value G3 is selected as the opening value G; When P3≤P<P4, the fourth preset opening value G4 is selected as the opening value G.

2. The method for adjusting feedwater temperature under deep peak-shaving conditions in coal-fired power units according to claim 1, characterized in that, The peak-shaving standard is as follows: The coal-fired power unit is in normal working condition; The temperature in the first extraction pipe reaches the minimum temperature threshold for the first heater to heat the water supply, and the temperature in the second extraction pipe reaches the minimum temperature threshold for the second heater to heat the water supply.

3. The method for adjusting feedwater temperature under deep peak-shaving conditions in coal-fired power units according to claim 1, characterized in that, The step of adjusting the opening of the intermediate pressure cylinder valve to the preset intermediate pressure cylinder valve opening value includes: Within the preset adjustment time, the opening of the intermediate pressure cylinder valve is gradually adjusted to the preset intermediate pressure cylinder valve opening value; The preset intermediate pressure cylinder valve opening value is within the range of 0.5%-3%; the preset adjustment time is 30-60 seconds; and the valve opening is reduced by 0.1-0.2% at each level.

4. The method for adjusting feedwater temperature under deep peak-shaving conditions in coal-fired power units according to claim 1, characterized in that, The deep peak shaving mode also includes: the first air extraction component and the second air extraction component operating alternately; The first air extraction assembly includes a first air extraction pipe, and a first solenoid valve is installed on the first air extraction pipe. The second air extraction assembly includes a second air extraction pipe, on which a second solenoid valve is installed.

5. The method for adjusting feedwater temperature under deep peak-shaving conditions of a coal-fired power unit according to claim 4, characterized in that, The first and second air extraction components operate alternately, including: The first pressure value when the first heater heats the feed water temperature to reach the first minimum temperature threshold and the second pressure value when the second heater heats the feed water temperature to reach the second minimum temperature threshold are determined respectively. The minimum opening threshold of the first solenoid valve on the first extraction pipe and the second opening threshold of the second solenoid valve on the second extraction pipe are determined based on the first pressure value and the second pressure value. Real-time monitoring of the first suction pressure in the first suction pipe and the second suction pressure in the second suction pipe; The opening degree of the first solenoid valve and the opening degree of the second solenoid valve are adjusted based on the relationship between the first suction pressure and the first pressure value, and the relationship between the second suction pressure and the second pressure value.

6. The method for adjusting feedwater temperature under deep peak-shaving conditions in coal-fired power units according to claim 5, characterized in that, Adjusting the opening degree of the first solenoid valve and the opening degree of the second solenoid valve based on the relationship between the first suction pressure and the first pressure value, and the relationship between the second suction pressure and the second pressure value, includes: Within a first preset time, the first solenoid valve on the first extraction pipe is kept at a first minimum opening threshold; the second solenoid valve on the second extraction pipe is kept at a normal opening; the first preset time is based on the time it takes for the temperature of the water heated by the first heater to drop from the initial temperature to the first minimum temperature threshold. Within a second preset time period, the second solenoid valve on the second extraction pipe is kept at a second minimum opening threshold; the first solenoid valve on the first extraction pipe is kept at a normal opening; the second preset time period is based on the time it takes for the temperature of the water heated by the second heater to drop from the initial temperature to the second minimum temperature threshold.

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