A method and device for sliding parameter shutdown of a steam turbine in a thermal power plant

Abstract

The application discloses a thermal power plant steam turbine sliding parameter shutdown method and device, which adjusts the boiler fuel accurately, adjusts and controls the boiler output heat and the generation of nitrogen oxides according to the coal blending combustion ratio, ensures the emission standard, gradually reduces the steam turbine load, steadily reduces the steam turbine cylinder metal temperature, achieves the purpose of reducing the steam turbine body cylinder temperature in the shutdown process, ensures the safe shutdown of the unit, shortens the maintenance time, reduces the maintenance cost and the shutdown loss.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steam turbine control, and particularly relates to a sliding parameter shutdown method and device for a steam turbine of a thermal power plant. BACKGROUND

[0002] Sliding parameter shutdown is to manually control the descending speed of main and reheated steam pressure and temperature and reduce the unit load under the condition of ensuring the safety of the unit, so that the steam turbine body and the boiler body, especially each header, are uniformly and rapidly cooled, and then the steam turbine is stopped.

[0003] The existing sliding parameter shutdown technical solution has the technical problem of emission overrun caused by environmental protection data fluctuation when the deaerating system is put into operation during unit shutdown. SUMMARY

[0004] The purpose of the embodiment of the present application is to provide a sliding parameter shutdown method and device for a steam turbine of a thermal power plant to solve the technical problems in the prior art.

[0005] In a first aspect, the embodiment of the present application provides a sliding parameter shutdown method for a steam turbine of a thermal power plant, comprising:

[0006] The blending ratio of the coal in the raw coal bunker is adjusted, and the adjustment before the shutdown of the steam turbine is detected; wherein the raw coal bunker comprises A bunker, B bunker, C bunker, D bunker and E bunker, the ratio of Tianchi coal to well coal in the A bunker, B bunker and C bunker is 5:1, and the ratio of Tianchi coal to blending material in the D bunker and E bunker is 6:1;

[0007] The steam turbine load is controlled in stages, wherein in the first stage, the steam turbine is in a coordinated control mode CCS, and the steam turbine load is reduced from 340 MW to 250 MW; in the second stage, the steam turbine control mode is switched from the CCS mode to a power control mode, and the steam turbine load is reduced from 250 MW to 180 MW; in the third stage, the steam turbine load is reduced from 180 MW to 100 MW; and in the fourth stage, the steam turbine load is reduced from 180 MW to 35 MW;

[0008] The shutdown operation is performed to control the shutdown of the steam turbine.

[0009] Wherein, when the steam turbine load is controlled in stages, the raw coal bunker coal supplement amount is 30 tons / time, wherein the coal supplement ratio of the A bunker is 5:1 of Tianchi coal to well coal, the coal supplement ratio of the B bunker and C bunker is 1:3 of Tianchi coal to well coal, and the coal supplement ratio of the D bunker and E bunker is 6:1 of Tianchi coal to blending material.

[0010] Wherein, the pre-shutdown detection and adjustment of the steam turbine comprises at least one of the following operations:

[0011] The temperature of the steam turbine lubricating oil is adjusted to 38-43℃.

[0012] Switching the ammonia area steam supply to the adjacent furnace low-pressure steam auxiliary header;

[0013] Blowing the entire boiler heating surface once;

[0014] Performing boiler expansion detection according to the boiler expansion instruction operation card;

[0015] Performing turbine unit shutdown valve detection according to the turbine unit shutdown valve operation check card;

[0016] Boiler feedwater bypass electric door switch detection;

[0017] Boiler feedwater bypass regulating door switch detection;

[0018] Boiler water storage tank overflow electric door switch detection;

[0019] Boiler water storage tank overflow regulating door switch detection;

[0020] According to the fuel pump start-up operation ticket, detecting the boiler front fuel circulation;

[0021] Boiler internal oil gun and micro-oil gun detection;

[0022] Trial rotating the turbine AC lubricating oil pump, recording the outlet oil pressure and current value;

[0023] Trial rotating the turbine DC lubricating oil pump, recording the outlet oil pressure and current value;

[0024] Trial rotating the turbine air side DC sealing oil pump, recording the oil pressure;

[0025] Trial rotating the turbine hydrogen side DC sealing oil pump, recording the oil pressure;

[0026] Trial rotating the turbine top shaft oil pump, recording the mother pipe oil pressure and current value;

[0027] Trial starting the turbine turning gear motor, recording the current value;

[0028] Trial starting the turbine diesel generator, recording the voltage value and current value, and detecting the switch closing;

[0029] Warming the turbine high-pressure auxiliary steam supply seal pipe;

[0030] Warming the turbine high-pressure auxiliary steam supply deaerator pipe.

[0031] In the first stage, the turbine is in coordinated control mode CCS, and the turbine load is reduced from 340 MW to 250 MW, including:

[0032] Reducing the turbine load from 320 MW to 250 MW within 1 hour;

[0033] controlling the main steam pressure of the steam turbine at 17 MPa, controlling the main steam flow of the steam turbine at 800 t / h (ton / hour), controlling the main steam temperature of the steam turbine at 540℃, and controlling the reheat steam temperature of the steam turbine at 520℃;

[0034] maintaining the first state of the steam turbine for 30 minutes, the first state including: the steam turbine load being 250 MW, the main steam pressure of the steam turbine being 17 MPa, the main steam temperature of the steam turbine being 540℃, and the reheat steam temperature of the steam turbine being 520℃.

[0035] In the first stage, the steam turbine is in a coordinated control mode CCS, and the steam turbine load is reduced from 340 MW to 250 MW, and further comprising:

[0036] controlling the power of the induced draft fan and / or the supply fan, so that the oxygen content of the boiler flue gas is controlled at 3.5-3.6%, and the nitrogen oxide concentration is less than 50 mg per cubic.

[0037] In the second stage, the steam turbine control mode is switched from the CCS mode to the power control mode, and the steam turbine load is reduced from 250 MW to 180 MW, and comprising: maintaining the state of the steam turbine load being 180 MW for 30 minutes.

[0038] In the second stage, the steam turbine control mode is switched from the CCS mode to the power control mode, and the steam turbine load is reduced from 250 MW to 180 MW, and further comprising:

[0039] controlling the power of the induced draft fan and / or the supply fan, so that the oxygen content of the boiler flue gas is controlled at 3.6-4.0%, and the nitrogen oxide concentration is less than 50 mg per cubic.

[0040] In the second stage, the steam turbine control mode is switched from the CCS mode to the power control mode, and the steam turbine load is reduced from 250 MW to 180 MW, and further comprising at least one of the following operations:

[0041] adjusting the shaft pressure of the steam turbine to 25-45 kPa;

[0042] adjusting the PH value of the feed water to 9.6-10.5;

[0043] controlling the coal supply at 120 tons / hour, emptying the E bin, and shutting down the E bin pulverizing system.

[0044] In the third stage, the steam turbine load is reduced from 180 MW to 100 MW, and comprising:

[0045] controlling the main steam pressure of the steam turbine at 11.88 MPa, the unit pressure drop temperature, controlling the main steam temperature of the steam turbine at 500℃, and controlling the reheat steam temperature of the steam turbine at 480℃.

[0046] wherein, in the third stage, the turbine load is reduced from 180 MW to 100 MW, further comprising:

[0047] when the turbine load is less than 180 MW, the air preheater is continuously sooted, and the steam source is switched to the high-pressure steam auxiliary header;

[0048] when the turbine load is reduced to 170 MW, the feed water pump recirculation is started;

[0049] when the turbine load is reduced to 120 MW, the constant pressure operation mode is entered, the pressure is maintained at 9.88 MPa, the boiler is switched to the wet state, and the water tank overflow regulating valve is started;

[0050] when the turbine load is reduced to 110 MW, the main transformer neutral point 222D knife switch is closed;

[0051] when the turbine load is greater than 105 MW, the average temperature of the denitration inlet on either side is maintained at ≥320°C;

[0052] when the turbine load is less than 105 MW, the A-side and B-side regulating valves and quick-closing valves of the boiler denitration are closed;

[0053] when the turbine load is reduced to 100 MW, the plant power source is switched to the high standby transformer electrical switching operation, and the high and low pressure heating steam side gas supply is stopped.

[0054] wherein, in the third stage, the turbine load is reduced from 180 MW to 100 MW, further comprising:

[0055] the power of the induced draft fan and / or the supply fan is controlled to control the oxygen content of the boiler flue gas at 4.0-6.0%, and the nitrogen oxide concentration is less than 50 mg per cubic.

[0056] wherein, in the third stage, the turbine load is reduced from 180 MW to 100 MW, further comprising at least one of the following operations:

[0057] the coal supply is reduced to 100 tons / hour, the D bin is burned empty, and the D bin pulverizing system is shut down;

[0058] the vacuum is maintained at less than -85 kPa, and the air cooling fan frequency is reduced or shut down;

[0059] when the electrical load is less than 35%, the turbine electrical load is less than 30% and the water tank liquid level high protection is exited, the total air volume low protection is exited, and the feed water flow low protection is exited;

[0060] the boiler drainage is preferentially recovered to the exhaust steam device, secondly to the water storage tank, and thirdly to the non-pressure water drainage;

[0061] when the turbine four-stage extraction steam pressure is <0.147 MPa, the deaerator steam source is switched to the high-pressure steam auxiliary header;

[0062] The turbine third extraction pressure is 0.4 MPa, and the high-pressure drain is cut to the exhaust device when the deaerator pressure is 0.4 MPa.

[0063] In the fourth stage, the turbine load is reduced from 180 MW to 35 MW, and the turbine main steam pressure is controlled at 8.9 MPa, the turbine main steam temperature is controlled at 380 DEG C, and the turbine reheat steam temperature is controlled at 360 DEG C.

[0064] The turbine main steam pressure is controlled at 8.9 MPa, the turbine main steam temperature is controlled at 380 DEG C, and the turbine reheat steam temperature is controlled at 360 DEG C.

[0065] The turbine main steam pressure is controlled at 8.9 MPa, the turbine main steam temperature is controlled at 380 DEG C, and the turbine reheat steam temperature is controlled at 360 DEG C.

[0066] In the fourth stage, the turbine load is reduced from 180 MW to 35 MW, and the turbine main steam pressure is controlled at 8.9 MPa, the turbine main steam temperature is controlled at 380 DEG C, and the turbine reheat steam temperature is controlled at 360 DEG C.

[0067] When the turbine load is reduced to 90 MW, the feed water is cut from the main line to the bypass line.

[0068] When the turbine load is reduced to 70 MW, the low-pressure section drain valve is automatically opened.

[0069] When the turbine load is reduced to 50 MW, the low-pressure cylinder water injection is started.

[0070] When the turbine load is reduced to 35 MW, the high-pressure section drain valve is opened.

[0071] In the fourth stage, the turbine load is reduced from 180 MW to 35 MW, and the turbine main steam pressure is controlled at 8.9 MPa, the turbine main steam temperature is controlled at 380 DEG C, and the turbine reheat steam temperature is controlled at 360 DEG C.

[0072] The power of the induced draft fan and / or the supply fan is controlled to control the oxygen content of the boiler flue gas to 6.0-10.0%, and the de-oxidation operation is exited.

[0073] In the fourth stage, the turbine load is reduced from 180 MW to 35 MW, and at least one of the following operations is performed:

[0074] The turbine AC lubricating oil pump is started, the lubricating oil pressure is greater than or equal to 0.098 MPa, and the upper oil pressure of the diaphragm valve is greater than 0.7 MPa.

[0075] The turbine high-pressure discharge check valve activity test is performed.

[0076] The turbine high-pressure main steam valve full stroke test is performed.

[0077] The medium-pressure steam valve full stroke test is performed.

[0078] The micro-oil gun is put into operation when two coal mills in the boiler are operated.

[0079] According to the boiler combustion condition, determine whether to put in the oil gun, and stop the electric dust removal after putting in the oil gun;

[0080] The coal supply is reduced to 60t / h, the A bin is burned out, and the A bin pulverizing system is stopped;

[0081] The coal supply is reduced to 60t / h, the C bin is burned out, and the C bin pulverizing system is stopped.

[0082] Among them, the control of the turbine shutdown can specifically include:

[0083] Apply for the provincial governor to be out of column;

[0084] When the boiler coal mill coal supply is 0t / h, the turbine is blocked;

[0085] Check if the high and medium pressure main steam valve and the speed valve of the turbine are closed;

[0086] Perform the turbine generator reverse power protection operation, the de-excitation switch trips, and the turbine speed drops;

[0087] Report to the provincial governor that the turbine has been out of column;

[0088] According to the turbine generator transformer group cold standby operation ticket, perform the turbine generator transformer group cold standby operation;

[0089] Perform generator maintenance;

[0090] Check if the turbine extraction check valve and the electric door are closed;

[0091] Check if the turbine high-pressure exhaust check valve is closed and the high-pressure exhaust ventilation valve is opened;

[0092] After the boiler coal mill is purged, stop the boiler coal mill;

[0093] Exit the boiler oil gun, and the boiler main fuel trips MFT to extinguish;

[0094] Check if the boiler primary air fan and the sealing air fan are interlocked and stopped;

[0095] Adjust the boiler ventilation volume to be greater than or equal to 398 tons / hour, and purge for 5 minutes;

[0096] Stop the boiler air supply fan and the induced draft fan;

[0097] Seal the furnace, close all dampers and secondary air doors of the boiler air and smoke system;

[0098] Open the economizer exhaust valve;

[0099] Check if the boiler drain valve, air valve, and sampling valve are closed;

[0100] Close the overflow regulating valve and the electric door of the boiler water tank;

[0101] The boiler water tank is replenished with water, and the replenishment flow rate is 60-120 tons / hour.

[0102] The water level in the boiler water tank is 12 meters, and the water supply bypass adjustment door and the electric door are closed when the water level is less than or equal to 18 meters.

[0103] The last feed water pump of the steam turbine is stopped.

[0104] When the rotation speed of the steam turbine is 1020 rpm, the top shaft oil pump is started.

[0105] The pressure of the steam turbine top shaft oil main pipe and the lubricating oil pressure are checked.

[0106] When the rotation speed of the steam turbine is 400 r / min, the vacuum breaker door is opened to a preset angle, and when the rotation speed of the steam turbine is zero and the vacuum is zero.

[0107] The shaft seal system is exited, and the shaft air blower is stopped.

[0108] When the rotation speed of the steam turbine is zero, the turning gear motor is started.

[0109] The generator hot test insulation operation ticket is executed.

[0110] The steam turbine is executed.

[0111] The method further comprises the following steps:

[0112] The opening degree of each layer of the boiler is controlled.

[0113] The opening degree of the first layer of the boiler is controlled to be 15%, the opening degree of the second layer of the boiler is controlled to be 15%, the opening degree of the third layer of the boiler is controlled to be 15%, the opening degree of the fourth layer of the boiler is controlled to be 20%, the opening degree of the fifth layer of the boiler is controlled to be 30%, and the opening degree of the sixth layer of the boiler is controlled to be 50%.

[0114] The first layer of the boiler is located at the bottom layer, and the sixth layer of the boiler is located at the top layer.

[0115] In a second aspect, the embodiment of the present application further provides a steam turbine sliding parameter shutdown device for a thermal power plant, which comprises:

[0116] An adjusting module is configured to adjust the blending ratio of the coal in the raw coal bunker and to detect and adjust before the steam turbine is shut down.

[0117] The control module is used for controlling the load reduction of the steam turbine in stages, wherein, in a first stage: the steam turbine is in a coordinated control mode CCS, and the load of the steam turbine is reduced from 340 MW to 250 MW; in a second stage: the control mode of the steam turbine is switched from the CCS mode to a power control mode, and the load of the steam turbine is reduced from 250 MW to 180 MW; in a third stage, the load of the steam turbine is reduced from 180 MW to 100 MW; and in a fourth stage, the load of the steam turbine is reduced from 180 MW to 35 MW.

[0118] The shutdown module is used for performing a shutdown operation and controlling the shutdown of the steam turbine.

[0119] The steam turbine sliding parameter shutdown method and device for the thermal power plant provided by the embodiment of the present application can ensure that the emission meets the standard by accurately adjusting the boiler fuel, adjusting the generation of boiler output heat and nitrogen oxides according to the coal blending ratio, and gradually reducing the load of the steam turbine and stably reducing the metal temperature of the cylinder of the steam turbine, so that the purpose of reducing the cylinder temperature of the steam turbine body is achieved in the shutdown process, the safe shutdown of the unit is ensured, the maintenance time is shortened, and the maintenance cost and shutdown loss are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0120] Figure 1 The steam turbine sliding parameter shutdown method flowchart for the thermal power plant provided by the embodiment of the present application is shown in the figure.

[0121] Figure 2 The steam turbine sliding parameter shutdown device structure diagram for the thermal power plant provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0122] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0123] The terms “first”, “second”, and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein. In addition, “and / or” in the specification and claims indicates at least one of the connected objects, and the character “ / ” generally indicates that the front and rear associated objects are in an “or” relationship.

[0124] As shown in the figure, Figure 1 The embodiment of the present application provides a steam turbine sliding parameter shutdown method for a thermal power plant, which comprises:

[0125] Step 110, adjust the coal blending ratio in the raw coal bunker, and perform pre-shutdown detection adjustment; wherein the raw coal bunker includes A bunker, B bunker, C bunker, D bunker, and E bunker, the ratio of Tianchi coal to well coal in the A bunker, B bunker, and C bunker is 5:1, and the ratio of Tianchi coal to blending material in the D bunker and E bunker is 6:1.

[0126] Step 120, control the turbine load to decrease in stages, wherein in the first stage, the turbine is in the coordinated control mode CCS, and the turbine load is decreased from 340MW to 250MW; in the second stage, the turbine control mode is switched from the CCS mode to the power control mode, and the turbine load is decreased from 250MW to 180MW; in the third stage, the turbine load is decreased from 180MW to 100MW; and in the fourth stage, the turbine load is decreased from 180MW to 35MW.

[0127] Step 130, perform the shutdown operation to control the turbine to stop.

[0128] The turbine sliding parameter shutdown method provided by the embodiment of the present application can ensure that the turbine emission meets the standard by precisely adjusting the boiler fuel, adjusting the boiler heat output and nitrogen oxide generation according to the coal blending ratio, and gradually reducing the turbine load to steadily reduce the turbine cylinder metal temperature, so that the purpose of reducing the turbine cylinder temperature is achieved during the shutdown process, the unit safe shutdown is ensured, the maintenance time is shortened, and the maintenance cost and shutdown loss are reduced.

[0129] In order to ensure that the boiler can burn according to the coal blending ratio provided by the embodiment of the present application during the process of controlling the turbine load to decrease in stages, in an optional embodiment of the present application, the raw coal bunker can be charged with coal according to the coal blending ratio provided by the embodiment of the present application at a preset time, for example, 12 hours, before starting the sliding parameter shutdown, and the raw coal bunker is charged to a preset amount, for example, 13 meters.

[0130] The embodiment of the present application can use the following raw coal bunker empty control card: the raw coal bunker emptying sequence is E→D→A→C→B (that is, the coal supply amount is E>D>A>C>B in principle).

[0131] The raw coal bunker according to the embodiment of the present application can further include an F bunker, and the F bunker is used as a backup bunker for unexpected needs. In order to avoid the phenomenon of spontaneous combustion of the raw coal in the F bunker due to long storage time, the raw coal in the F bunker can be used up before the sliding parameter shutdown is performed according to the technical solution provided by the embodiment of the present application.

[0132] In an alternative embodiment of the present application, the loose device can also be used to loosen the raw coal in the raw coal bunker when the raw coal height is less than 8 meters, less than 4 meters, and the bunker is empty, to ensure that the coal supply meets the coal blending ratio provided by the present application during the process of controlling the load of the steam turbine in stages. In an alternative embodiment, after the raw coal bunker is empty, a sledgehammer can be used to knock the raw coal at a predetermined height layer (for example, 22 meters) of the raw coal bunker, such as the front, back, left and right of the raw coal bunker.

[0133] In a specific embodiment, if it is necessary to supplement the raw coal in the raw coal bunker during the process of controlling the load of the steam turbine in stages, it is recommended that the raw coal supplement amount is 30 tons / time, wherein the supplement ratio of A bunker is 5:1 of Tianchi coal to well coal, the supplement ratio of B bunker and C bunker is 1:3 of Tianchi coal to well coal, and the supplement ratio of D bunker and E bunker is 6:1 of Tianchi coal to the blended material, to ensure that the emission meets the standard.

[0134] In a specific embodiment, the detection and adjustment before the shutdown of the steam turbine related to the present application includes the following operations:

[0135] Adjust the lubricating oil temperature of the steam turbine to 38-43℃;

[0136] Switch the ammonia area steam supply to the adjacent furnace low-pressure steam auxiliary header;

[0137] Completely blow the ash of the boiler heating surface once;

[0138] Perform the boiler expansion detection according to the boiler expansion indication operation card;

[0139] Perform the steam turbine unit shutdown valve detection according to the steam turbine unit shutdown valve operation check card;

[0140] Detect the opening and closing of the boiler feedwater bypass electric door;

[0141] Detect the opening and closing of the boiler feedwater bypass regulating door;

[0142] Detect the opening and closing of the boiler water storage tank overflow electric door;

[0143] Detect the opening and closing of the boiler water storage tank overflow regulating door;

[0144] Detect the boiler front fuel oil circulation according to the fuel oil pump start-up operation ticket;

[0145] Detect the oil gun and micro oil gun in the boiler;

[0146] Test the steam turbine alternating current lubricating oil pump, and record the outlet oil pressure and current value;

[0147] Test the steam turbine direct current lubricating oil pump, and record the outlet oil pressure and current value;

[0148] Test the steam turbine air side direct current sealing oil pump, and record the oil pressure;

[0149] Test the turbine hydrogen side direct current seal oil pump, record the oil pressure;

[0150] Test the turbine top shaft oil pump, record the manifold oil pressure and current value;

[0151] Test the turbine turning gear motor, record the current value;

[0152] Test the turbine diesel generator, record the voltage value and current value, and detect the switch closing;

[0153] Warm the turbine high-pressure auxiliary steam supply seal pipe;

[0154] Warm the turbine high-pressure auxiliary steam supply deaerator pipe.

[0155] The above detection and adjustment operations are only illustrative, and the turbine shutdown detection and adjustment operations involved in the embodiment of the present application can further include other required technical operations, and the execution sequence of each detection and adjustment operation can be adjusted as required.

[0156] The embodiment of the present application gradually reduces the turbine load, stably reduces the turbine cylinder metal temperature, and reduces the turbine body cylinder temperature during shutdown, thereby ensuring safe shutdown of the unit, shortening the maintenance time, and reducing maintenance costs and shutdown losses.

[0157] In a specific embodiment, in the first stage of controlling the turbine load to decrease in stages, the turbine is in the coordinated control mode CCS, and the process of reducing the turbine load from 340 MW to 250 MW can specifically include:

[0158] Reducing the turbine load from 320 MW to 250 MW within 1 hour;

[0159] Controlling the turbine main steam pressure at 17 MPa, the turbine main steam flow at 800 t / h (ton / hour), the turbine main steam temperature at 540℃, and the turbine reheat steam temperature at 520℃.

[0160] The decrease rates of various parameters can be adjusted and set as required, for example, the load decrease rate can be greater than or equal to 1 MW / min, or less than 1 MW / min; the pressure decrease rate can be less than 0.1 MPa / min, the main steam temperature decrease rate can be less than 1℃ / min, and the reheat steam temperature decrease rate can be less than 1℃ / min;

[0161] Maintain the turbine in the first state for 30 minutes, and the first state includes: turbine load 250 MW, turbine main steam pressure 17 MPa, turbine main steam temperature 540℃, and turbine reheat steam temperature 520℃.

[0162] In an optional embodiment, in the first stage, the steam turbine is in the coordinated control mode CCS, and the steam turbine load is reduced from 340 MW to 250 MW, which can further include: switching from the sequence valve to the single valve when the steam turbine main steam flow is less than 850 t / h.

[0163] To ensure the emission compliance, the method for turbine sliding parameter shutdown of the power plant provided in the embodiments of the present application can not only precisely adjust the boiler fuel, but also control the environmental protection parameters according to the control card of the unit shutdown environmental protection parameters shown in Table 1 in different stages of the control of the steam turbine load reduction.

[0164] Table 1

[0165]

[0166] In an optional embodiment, in the first stage, the steam turbine is in the coordinated control mode CCS, and the steam turbine load is reduced from 340 MW to 250 MW, which can further include:

[0167] The power of the induced draft fan and / or the supply fan is controlled, so that the oxygen content of the boiler flue gas is controlled at 3.5-3.6%, and the nitrogen oxide concentration is less than 50 mg per cubic meter.

[0168] In an optional embodiment, in the second stage, the steam turbine control mode is switched from the CCS mode to the power control mode, and the steam turbine load is reduced from 250 MW to 180 MW, which can include: maintaining the state of the steam turbine load of 180 MW for 30 minutes.

[0169] In an optional embodiment, in the second stage, the steam turbine control mode is switched from the CCS mode to the power control mode, and the steam turbine load is reduced from 250 MW to 180 MW, which can further include:

[0170] The power of the induced draft fan and / or the supply fan is controlled, so that the oxygen content of the boiler flue gas is controlled at 3.6-4.0%, and the nitrogen oxide concentration is less than 50 mg per cubic meter.

[0171] In an optional embodiment, in the second stage, the steam turbine control mode is switched from the CCS mode to the power control mode, and the steam turbine load is reduced from 250 MW to 180 MW, which further includes at least one of the following operations:

[0172] The steam turbine shaft pressure is adjusted to 25-45 kPa;

[0173] The feed water PH value is adjusted to 9.6-10.5;

[0174] The coal supply amount is controlled at 120 tons / hour, the E bin is burned out, and the E bin pulverizing system is shut down.

[0175] The above operation is only an example, and other required technical operations can be further included in the second stage of the phased control of the steam turbine load reduction, and the execution sequence of each detection and adjustment operation can be adjusted as required.

[0176] In an alternative embodiment, in the third stage, the steam turbine load is reduced from 180 MW to 100 MW, including:

[0177] The main steam pressure of the steam turbine is controlled at 11.88 MPa, the unit is controlled at a constant pressure and temperature, the main steam temperature of the steam turbine is controlled at 500°C, and the reheat steam temperature of the steam turbine is controlled at 480°C, wherein the load reduction rate can be less than 1 MW / min, and the temperature reduction rate can be less than 1°C / min.

[0178] In an alternative embodiment, in the third stage, the steam turbine load is reduced from 180 MW to 100 MW, further including:

[0179] When the steam turbine load is less than 180 MW, the air preheater continuous soot blowing is retained, and the steam source is switched to the high-pressure steam auxiliary header;

[0180] When the steam turbine load is reduced to 170 MW, the feed water pump recirculation is started for standby;

[0181] When the steam turbine load is reduced to 120 MW, the constant pressure operation mode is entered, the pressure is maintained at 9.88 MPa, the boiler is switched to wet state, and the water tank overflow regulating valve is started;

[0182] When the steam turbine load is reduced to 110 MW, the main transformer neutral point 222D knife switch is closed;

[0183] When the steam turbine load is greater than 105 MW, the average value of the flue gas temperature on either side of the denitration inlet is maintained at ≥320°C;

[0184] When the steam turbine load is less than 105 MW, the regulating valves and quick closing valves of the boiler denitration A side and B side are closed;

[0185] When the steam turbine load is reduced to 100 MW, the plant power source is switched to the high standby transformer electrical switching operation, and the high and low pressure heating steam side gas supply is stopped.

[0186] In an alternative embodiment, in the third stage, the steam turbine load is reduced from 180 MW to 100 MW, further including:

[0187] The power of the induced draft fan and / or the supply fan is controlled to control the oxygen content of the boiler flue gas at 4.0-6.0%, and the nitrogen oxide concentration is less than 50 mg per cubic.

[0188] In an alternative embodiment, in the third stage, the steam turbine load is reduced from 180 MW to 100 MW, further including at least one of the following operations:

[0189] The coal supply is reduced to 100 tons / hour, the D bin is burned out, and the D bin pulverizing system is shut down;

[0190] The vacuum is maintained at less than -85 kPa, and the air cooling fan frequency is reduced or shut down;

[0191] When the electric load is less than 35%, the turbine electric load is less than 30%, the water tank liquid level is high, the total air volume is low, and the water supply flow is low;

[0192] The boiler drainage is preferentially recovered to the exhaust device, then to the water storage pool, and then externally discharged to the non-pressure drainage;

[0193] When the fourth-stage extraction pressure of the turbine is less than 0.147 MPa, the deaerator steam source is switched to the high-pressure steam auxiliary header;

[0194] When the third-stage extraction pressure of the turbine is less than the deaerator 0.4 MPa, the high-pressure heater drainage is switched to the exhaust device.

[0195] The above operations are only illustrative, and in the third stage of controlling the turbine load to decrease in stages, other required technical operations can also be included, and the execution sequence of each detection and adjustment operation can be arbitrarily adjusted as required.

[0196] In an optional embodiment, in the fourth stage, the turbine load is decreased from 180 MW to 35 MW, including:

[0197] The turbine main steam pressure is controlled at 8.9 MPa, the turbine main steam temperature is controlled at 380°C, and the turbine reheat steam temperature is controlled at 360°C, wherein the load decrease rate can be less than 1 MW / min, and the temperature decrease rate can be less than 1°C / min;

[0198] The turbine is maintained in a second state for 30 minutes, and the second state includes: the turbine load is 35 MW, the turbine main steam pressure is 8.9 MPa, the turbine main steam temperature is 380°C, and the turbine reheat steam temperature is 360°C.

[0199] In an optional embodiment, in the fourth stage, the turbine load is decreased from 180 MW to 35 MW, further including:

[0200] When the turbine load is reduced to 90 MW, the water supply is switched from the main path to the bypass;

[0201] When the turbine load is reduced to 70 MW, the low-pressure section drainage valve is automatically opened;

[0202] When the turbine load is reduced to 50 MW, the low-pressure cylinder water injection is started;

[0203] When the turbine load is reduced to 35 MW, the high-pressure section drainage valve is opened.

[0204] In an alternative embodiment, in the fourth stage: the turbine load is reduced from 180 MW to 35 MW, further comprising:

[0205] Controlling the power of the induced draft fan and / or the supply fan to control the oxygen content of the boiler flue gas to 6.0-10.0%, and exiting the de-energized operation.

[0206] In an alternative embodiment, reducing the turbine load from 180 MW to 35 MW further comprises at least one of the following operations:

[0207] Starting the turbine AC lubricating oil pump, the lubricating oil pressure is greater than or equal to 0.098 MPa, and the upper oil pressure of the diaphragm valve is greater than 0.7 MPa;

[0208] Performing a turbine high-pressure discharge check valve activity test;

[0209] Performing a turbine high-pressure main steam valve full stroke test;

[0210] Performing a medium-pressure steam valve full stroke test;

[0211] When there are two coal mills operating in the boiler, the micro-oil gun is put into operation;

[0212] According to the boiler combustion condition, it is determined whether to put the oil gun into operation, and after the oil gun is put into operation, the electric precipitator is stopped;

[0213] The coal supply amount is reduced to 60 t / h, the A bin is burned out, and the A bin pulverizing system is stopped;

[0214] The coal supply amount is reduced to 60 t / h, the C bin is burned out, and the C bin pulverizing system is stopped.

[0215] The above operations are only illustrative, and in the fourth stage of controlling the turbine load to decrease in stages, other required technical operations can also be specifically included, and the execution order of each detection and adjustment operation can be arbitrarily adjusted as required.

[0216] In an alternative embodiment, the stop operation is performed, and the turbine is controlled to stop, comprising:

[0217] Applying for the provincial power dispatching turbine unit to be tripped;

[0218] When the coal supply amount of the boiler coal mill is 0 t / h, the turbine is tripped;

[0219] Checking whether the turbine high-pressure and medium-pressure main steam valves and the speed regulating valve are closed;

[0220] Performing a turbine generator reverse power protection operation, the de-energizing switch is tripped, and the turbine speed is reduced;

[0221] Reporting to the provincial power dispatching that the turbine has been tripped;

[0222] According to the turbine generator-transformer unit switching to cold standby operation ticket, perform the turbine generator-transformer unit switching to cold standby operation;

[0223] Perform generator maintenance;

[0224] Check whether the extraction non-return valves and electric valves of each section of the steam turbine are closed;

[0225] Check that the turbine high-pressure exhaust check valve is closed and the high-pressure exhaust ventilation valve is open.

[0226] After the boiler coal mill is purged, the boiler coal mill is shut down.

[0227] Disconnect the boiler oil gun; the boiler main fuel trips and the MFT (Main Fuel Trip) is activated to extinguish the fire.

[0228] Check and stop the boiler primary air fan and sealing air fan interlocks;

[0229] Adjust the boiler ventilation volume to be greater than or equal to 398t / h, and purge for 5 minutes;

[0230] Shut down the boiler's forced draft fan and induced draft fan;

[0231] Seal the furnace and close all dampers and secondary air dampers in the boiler flue gas system;

[0232] Open the economizer exhaust valve;

[0233] Check and close the boiler drain valve, air valve, and sampling valve;

[0234] Close the overflow regulating valve and electric door of the boiler water storage tank;

[0235] The boiler water storage tank is replenished with water at a flow rate of 60–120 t / h.

[0236] When the water level in the boiler storage tank is 12 meters, close the water supply bypass regulating valve and electric valve. The highest water level is less than or equal to 18 meters.

[0237] Stop the last feedwater pump of the steam turbine;

[0238] When the turbine speed reaches 1020 rpm, start the jacking oil pump;

[0239] Check the pressure of the turbine jacking oil header and the lubricating oil pressure;

[0240] When the turbine speed is 400 r / min, the vacuum breaking door is opened to a preset angle. When the turbine speed reaches zero, the vacuum reaches zero.

[0241] Exit the shaft sealing system and stop the shaft fan;

[0242] Start the turning gear motor when the turbine speed reaches zero;

[0243] Execute the generator thermal insulation test operation ticket;

[0244] Performing a turbine wet steam operation.

[0245] The above operations are only for illustration, and other required technical operations can also be included in the control of the turbine shutdown process, and the execution sequence of each detection and adjustment operation can be adjusted as required.

[0246] In order to ensure that the emission is up to standard, and to ensure that the turbine unit can realize deep sliding parameter shutdown when the ultra-low emission is put into full working condition, in addition to the above-mentioned control of the coal blending ratio, the optimization of gradually reducing the turbine load and the steam parameter, the burner opening of different combustion layers in the boiler can also be controlled by adjusting the wind opening of the wind and smoke system according to the following Table 2.

[0247] Table 2

[0248]

[0249] In a specific embodiment, the turbine sliding parameter shutdown method of the thermal power plant can further include:

[0250] Controlling the opening of each layer of the burner; wherein:

[0251] The opening of the first layer of the burner is controlled to be 15%, the opening of the second layer of the burner is controlled to be 15%, the opening of the third layer of the burner is controlled to be 15%, the opening of the fourth layer of the burner is controlled to be 20%, the opening of the fifth layer of the burner is controlled to be 30%, and the opening of the sixth layer of the burner is controlled to be 50%;

[0252] The first layer of the burner is located at the bottom layer, and the sixth layer of the burner is located at the highest layer.

[0253] The implementation process of one specific embodiment of the turbine sliding parameter shutdown method of the thermal power plant provided by the embodiment will be described in detail below.

[0254] The embodiment can specifically include:

[0255] 1. Before the preset time before starting the sliding parameter shutdown, for example, 12 hours before, the raw coal bunker is charged with coal according to the coal blending ratio provided by the embodiment, and the raw coal bunker is charged to a preset amount, for example, the raw coal bunker is charged to 13 meters;

[0256] 2. After the raw coal height in the raw coal bunker is less than 8 meters, less than 4 meters, and the bunker is empty, the raw coal bunker is loosened by the loosening device;

[0257] 3. Inform the desulfurization foreman to start the turbine shutdown preparation adjustment operation;

[0258] 4. Adjust the turbine lubricating oil temperature to 38-43℃;

[0259] 5. Switch the ammonia area steam supply to the adjacent low-pressure steam auxiliary header;

[0260] 6. Blow down the boiler heating surface once;

[0261] 7. Perform boiler expansion detection according to the boiler expansion instruction operation card;

[0262] 8. Perform turbine unit shutdown valve detection according to the turbine unit shutdown valve operation check card;

[0263] 9. Perform detection of the opening and closing of the boiler feedwater bypass electric door;

[0264] 10. Perform detection of the opening and closing of the boiler feedwater bypass regulating door;

[0265] 11. Perform detection of the opening and closing of the boiler water storage tank overflow electric door (door 1, door 2);

[0266] 12. Perform detection of the opening and closing of the boiler water storage tank overflow regulating door (door 1, door 2);

[0267] 13. Perform detection of the boiler front fuel oil circulation according to the fuel oil pump start-up operation ticket;

[0268] 14. Perform detection of the oil gun and micro oil gun in the boiler;

[0269] 15. Perform trial rotation of the turbine AC lubricating oil pump and record the outlet oil pressure and current value;

[0270] 16. Perform trial rotation of the turbine DC lubricating oil pump and record the outlet oil pressure and current value;

[0271] 17. Perform trial rotation of the turbine air side DC sealing oil pump and record the oil pressure;

[0272] 18. Perform trial rotation of the turbine hydrogen side DC sealing oil pump and record the oil pressure;

[0273] 19. Perform trial rotation of the turbine top shaft oil pump and record the header oil pressure and current value (if there are multiple top shaft oil pumps, record the header oil pressure and current value for each top shaft oil pump);

[0274] 20. Perform trial start-up of the turbine turning gear motor and record the current value;

[0275] 21. Perform trial start-up of the turbine diesel generator and record the voltage value and current value, and detect the switch closing;

[0276] 22. Warm the turbine high-pressure auxiliary steam supply shaft seal pipe;

[0277] 23. Warm the turbine high-pressure auxiliary steam supply deaerator pipe;

[0278] 24. Make the turbine in the coordinated control mode CCS, and reduce the turbine load from 320 MW to 250 MW within 1 hour.

[0279] 25. Control the main steam pressure of the steam turbine at 17 MPa, control the main steam flow of the steam turbine at 800 t / h (ton / hour), control the main steam temperature of the steam turbine at 540°C, control the reheat steam temperature of the steam turbine at 520°C; when the main steam flow of the steam turbine is < 850 t / h, switch from a sequence valve to a single valve;

[0280] 26. Maintain a first state of the steam turbine for 30 minutes, the first state including: a steam turbine load of 250 MW, a steam turbine main steam pressure of 17 MPa, a steam turbine main steam temperature of 540°C, and a steam turbine reheat steam temperature of 520°C;

[0281] 27. Control the power of the induced draft fan and / or the forced draft fan so that the oxygen content of the boiler flue gas is controlled at 3.5-3.6%, and the nitrogen oxide concentration is less than 50 mg per cubic meter;

[0282] 28. Switch the control mode of the steam turbine from a CCS mode to a power control mode, and reduce the steam turbine load from 250 MW to 180 MW;

[0283] 29. Control the power of the induced draft fan and / or the forced draft fan so that the oxygen content of the boiler flue gas is controlled at 3.6-4.0%, and the nitrogen oxide concentration is less than 50 mg per cubic meter;

[0284] 30. Control the coal supply at 120 tons / hour, empty the E bin, and shut down the E bin pulverizing system

[0285] 31. Adjust the steam turbine shaft pressure to 25-45 kPa;

[0286] 32. Maintain the state of the steam turbine load of 180 MW for 30 minutes;

[0287] 33. Inform the auxiliary control shift leader to exit the polishing treatment, and adjust the feedwater pH value to 9.6-10.5;

[0288] 34. Reduce the steam turbine load from 180 MW to 100 MW;

[0289] 35. Control the power of the induced draft fan and / or the forced draft fan so that the oxygen content of the boiler flue gas is controlled at 4.0-6.0%, and the nitrogen oxide concentration is less than 50 mg per cubic meter;

[0290] 36. Control the main steam pressure of the steam turbine at 11.88 MPa, control the unit pressure drop temperature, control the main steam temperature of the steam turbine at 500°C, and control the reheat steam temperature of the steam turbine at 480°C;

[0291] 37. When the steam turbine load is less than 180 MW, keep the air preheater continuously soot-blowing, and switch the steam source to the high-pressure steam auxiliary header;

[0292] 38. When the turbine load is reduced to 170 MW, the feed water pump recirculation is started for standby;

[0293] 39. The coal supply is reduced to 100 tons / hour, the D bin is burned out, and the D bin pulverizing system is shut down;

[0294] 40. The vacuum is maintained at less than -85 kPa, and the air cooling fan frequency is reduced or stopped;

[0295] 41. When the electric load is less than 35%, the turbine electric load is less than 30%, the water tank liquid level is high, the total air volume is low, and the feed water flow is low, the protections are exited;

[0296] 42. When the turbine load is reduced to 120 MW, the constant pressure operation mode is entered, the pressure is maintained at 9.88 MPa, the boiler is converted to wet state, and the water tank overflow regulating valve is started;

[0297] 43. The boiler drainage is preferentially recovered to the exhaust device, secondly to the water storage pool, and thirdly to the non-pressure water drainage;

[0298] 44. When the turbine four-stage extraction pressure is less than 0.147 MPa, the deaerator steam source is switched to the high-pressure steam auxiliary header;

[0299] 45. When the turbine three-stage extraction pressure is less than the deaerator 0.4 MPa, the high-pressure heater drainage is switched to the exhaust device;

[0300] 46. When the turbine load is reduced to 110 MW, the main transformer neutral point 222D knife switch is closed;

[0301] 47. When the turbine load is greater than 105 MW, the average value of the denitration inlet on either side is maintained at greater than or equal to 320°C;

[0302] 48. When the turbine load is less than 105 MW, the regulating valves and quick-closing valves of the boiler denitration A side and B side are closed;

[0303] 49. When the turbine load is reduced to 100 MW, the plant power source is switched to the high standby transformer electrical switching operation, and the high-pressure and low-pressure heating steam side gas supply is stopped;

[0304] 50. The turbine load is reduced from 180 MW to 35 MW;

[0305] 51. The power of the induced draft fan and / or the supply fan is controlled to control the oxygen content of the boiler flue gas to 6.0-10.0%, and the denitration operation is exited;

[0306] 52. When the turbine load is reduced to 90 MW, the feed water is switched from the main path to the bypass;

[0307] 53. When the turbine load is reduced to 70 MW, the low-pressure section drainage valve is automatically opened;

[0308] 54. Reduce the coal supply to 60 t / h, burn out the A bin, and stop the A bin pulverizing system;

[0309] 55. When two coal mills are running in the boiler, start the micro-oil gun;

[0310] 56. Determine whether to start the oil gun according to the combustion condition of the boiler, and stop the electric precipitator after starting the oil gun; since the unit is in a low load operation state at this stage, the remaining lower layer coal mill has an unstable combustion condition, and if the combustion condition is found to be deteriorating, the large oil gun should be started in time to stabilize combustion and prevent the boiler from going out;

[0311] 57. When the steam turbine load drops to 50 MW, start (automatically or manually) the low-pressure cylinder water injection;

[0312] 58. Burn out the C bin, and stop the C bin pulverizing system;

[0313] 59. When the steam turbine load drops to 35 MW, open the high-pressure section drain valve;

[0314] 60. Maintain the second state of the steam turbine for 30 minutes, the second state including: steam turbine load 35 MW, steam turbine main steam pressure 8.9 MPa, steam turbine main steam temperature 380°C, and steam turbine reheat steam temperature 360°C;

[0315] 61. Start the steam turbine AC lubricating oil pump, the lubricating oil pressure is greater than or equal to 0.098 MPa, and the upper oil pressure of the diaphragm valve is greater than 0.7 MPa;

[0316] 62. Perform the steam turbine high-pressure check valve activity test;

[0317] 63. Perform the steam turbine high-pressure main steam valve full stroke test;

[0318] 64. Perform the medium-pressure steam valve full stroke test;

[0319] 65. Apply for the provincial dispatching steam turbine unit to be tripped;

[0320] 66. When the boiler coal mill coal supply is 0 t / h, trip the steam turbine;

[0321] 67. Check whether the steam turbine high-pressure and medium-pressure main steam valves and the speed regulating valve are closed;

[0322] 68. Perform the steam turbine generator reverse power protection operation, the de-excitation switch trips, and the steam turbine speed drops;

[0323] 69. Report to the provincial dispatching, the steam turbine has been tripped;

[0324] 70. According to the steam turbine generator transformer group cold standby operation ticket, perform the steam turbine generator transformer group cold standby operation;

[0325] 71. Perform the generator maintenance;

[0326] 72, Check if the steam turbine section extraction check valve and electric valve are closed;

[0327] 73, Check if the steam turbine high pressure discharge check valve is closed and the high pressure discharge air valve is opened;

[0328] 74, After the boiler coal mill is purged, stop the boiler coal mill;

[0329] 75, Exit the boiler oil gun and the boiler main fuel trips MFT to extinguish;

[0330] 76, Check if the boiler primary air fan and seal air fan interlock is stopped;

[0331] 77, Adjust the boiler air volume to be greater than or equal to 398 t / h and purge for 5 minutes;

[0332] 78, Stop the boiler A side air fan and induced draft fan;

[0333] 79, Stop the boiler B side air fan and induced draft fan;

[0334] 80, Seal the furnace and close all dampers and secondary air doors of the boiler air and flue gas system;

[0335] 81, Open the economizer exhaust valve;

[0336] 82, Check if the boiler drain valve, air valve, and sampling valve are closed;

[0337] 83, Close the overflow regulating valve (valve 1, valve 2) and electric valve (valve 1, valve 2) of the boiler water storage tank;

[0338] 84, Add water to the boiler water storage tank at a flow rate of 60 to 120 t / h;

[0339] 85, Close the feedwater bypass regulating valve and electric valve when the water level in the boiler water storage tank is 12 meters, and the maximum water level is less than or equal to 18 meters;

[0340] 86, Stop the last feedwater pump of the steam turbine;

[0341] 87, When the steam turbine speed is 1020 rpm, start the top shaft oil pump;

[0342] 88, Check the steam turbine top shaft oil main pipe pressure and lubricating oil pressure;

[0343] 89, When the steam turbine speed is 400 r / min, open the vacuum breaking door to a preset angle, and when the steam turbine speed is zero, the vacuum is zero;

[0344] 90, Exit the shaft seal system and stop the shaft air supply fan;

[0345] 91, Start the turning gear motor when the steam turbine speed is zero;

[0346] 92. Execute the generator thermal insulation test operation ticket;

[0347] 93. Perform turbine cylinder shut-down operation.

[0348] The sliding parameter shutdown method for steam turbines in thermal power plants provided in this invention precisely adjusts the boiler fuel and controls the generation of heat and nitrogen oxides by adjusting the blending ratio to ensure emissions meet standards. Furthermore, it gradually reduces the turbine load and steadily lowers the turbine cylinder metal temperature, achieving the goal of reducing the turbine cylinder temperature during shutdown. This ensures safe unit shutdown, shortens maintenance time, reduces maintenance costs and downtime losses, and eliminates the risk of boiler flameout due to unstable combustion during low-load operation.

[0349] Secondly, embodiments of the present invention also provide a sliding parameter shutdown device for a steam turbine in a thermal power plant, such as... Figure 2 As shown, it includes:

[0350] The adjustment module 210 is used to adjust the coal blending ratio in the raw coal bunker and to perform pre-turbine shutdown testing and adjustment; wherein, the raw coal bunker includes bunker A, bunker B, bunker C, bunker D, and bunker E, the ratio of Tianchi coal to well coal in bunkers A, B, and C is 5:1, and the ratio of Tianchi coal to blending agent in bunkers D and E is 6:1;

[0351] The control module 220 is used to control the turbine load reduction in stages. In the first stage, the turbine is put into coordinated control mode (CCS) to reduce the turbine load from 340MW to 250MW. In the second stage, the turbine control mode is switched from CCS mode to power control mode to reduce the turbine load from 250MW to 180MW. In the third stage, the turbine load is reduced from 180MW to 100MW. In the fourth stage, the turbine load is reduced from 180MW to 35MW.

[0352] The shutdown module 230 is used to perform shutdown operations and control the turbine to shut down.

[0353] The specific operation process of the sliding parameter shutdown device for steam turbines in thermal power plants is detailed in the above-mentioned implementation process of the sliding parameter shutdown method for steam turbines in thermal power plants, and will not be repeated here.

[0354] The method and apparatus for shutting down a steam turbine in a thermal power plant using sliding parameters provided in this invention precisely adjusts the boiler fuel and controls the generation of heat and nitrogen oxides by adjusting the blending ratio, ensuring that emissions meet standards. Furthermore, it gradually reduces the turbine load and steadily lowers the turbine cylinder metal temperature, achieving the goal of reducing the turbine cylinder temperature during shutdown. This ensures safe unit shutdown, shortens maintenance time, reduces maintenance costs and downtime losses, and eliminates the risk of boiler flameout due to unstable combustion during low-load operation.

[0355] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are merely illustrative, but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and all of them belong to the protection of the present application.

Claims

1. A method for sliding parameter shutdown of a steam turbine of a thermal power plant, characterized in that, Comprise: Adjust the blending ratio of coal in the raw coal bunker, and detect and adjust before the turbine is shut down; wherein the raw coal bunker comprises A bunker, B bunker, C bunker, D bunker and E bunker, the ratio of Tianchi coal to well coal in A bunker, B bunker and C bunker is 5:1, and the ratio of Tianchi coal to blending material in D bunker and E bunker is 6:1; Control the turbine load reduction in stages, wherein in the first stage, the turbine is in coordinated control mode CCS, and the turbine load is reduced from 340 MW to 250 MW; in the second stage, the turbine control mode is switched from CCS mode to power control mode, and the turbine load is reduced from 250 MW to 180 MW; in the third stage, the turbine load is reduced from 180 MW to 100 MW; in the fourth stage, the turbine load is reduced from 100 MW to 35 MW; wherein in the first stage, the turbine is in coordinated control mode CCS, and the turbine load is reduced from 340 MW to 250 MW, further comprising: controlling the power of the induced draft fan and / or the forced draft fan to control the oxygen content of the boiler flue gas at 3.5-3.6%, and the nitrogen oxide concentration is less than 50 mg per cubic; in the second stage, the turbine control mode is switched from CCS mode to power control mode, and the turbine load is reduced from 250 MW to 180 MW, further comprising: controlling the power of the induced draft fan and / or the forced draft fan to control the oxygen content of the boiler flue gas at 3.6-4.0%, and the nitrogen oxide concentration is less than 50 mg per cubic; in the third stage, the turbine load is reduced from 180 MW to 100 MW, further comprising: controlling the power of the induced draft fan and / or the forced draft fan to control the oxygen content of the boiler flue gas at 4.0-6.0%, and the nitrogen oxide concentration is less than 50 mg per cubic; in the fourth stage: the turbine load is reduced from 100 MW to 35 MW, further comprising: controlling the power of the induced draft fan and / or the forced draft fan to control the oxygen content of the boiler flue gas at 6.0-10.0%, and exiting the denitration operation; Perform the shutdown operation to control the turbine shutdown; Wherein, in the third stage, the turbine load is reduced from 180 MW to 100 MW, further comprising: When the turbine load is less than 180 MW, keep the air preheater continuous soot blowing, and switch the steam source to the high-pressure steam auxiliary header; When the turbine load is reduced to 170 MW, start the feed water pump recirculation for standby; When the turbine load is reduced to 120 MW, switch to constant pressure operation mode, maintain the pressure at 9.88 Mpa, the boiler is in wet state, and start the overflow regulating valve of the water storage tank; When the turbine load is reduced to 110 MW, close the main transformer neutral point 222D knife switch; When the turbine load is greater than 105 MW, keep the average value of the flue gas temperature on either side of the denitration inlet greater than or equal to 320℃; When the turbine load is less than 105 MW, close the regulating valve and quick closing valve of the boiler denitration A side and B side; When the turbine load is reduced to 100 MW, perform the operation of switching the plant power source to the high standby transformer, and stop the high and low pressure heating steam side gas supply.

2. The method of claim 1, wherein, In the phased control of the turbine load drop, the original coal bunker coal supplement is 30 tons / time, wherein the coal supplement proportion of A bin is 5:1 of Tianchi coal and well coal, the coal supplement proportion of B bin and C bin is 1:3 of Tianchi coal and well coal, and the coal supplement proportion of D bin and E bin is 6:1 of Tianchi coal and the mixture.

3. The method of claim 1, wherein, The pre-shutdown detection and adjustment of the steam turbine comprises at least one of the following operations: Adjusting the temperature of the steam turbine lubricating oil to 38-43℃; Switching the ammonia area steam supply to the adjacent furnace low-pressure steam auxiliary header; Fully blowing the ash of the boiler heating surface once; Performing the boiler expansion detection according to the boiler expansion indication operation card; Performing the turbine unit shutdown valve detection according to the turbine unit shutdown valve operation check card; Boiler feedwater bypass electric door opening and closing detection; Boiler feedwater bypass regulating door opening and closing detection; Boiler water storage tank overflow electric door opening and closing detection; Boiler water storage tank overflow regulating door opening and closing detection; Detecting the boiler front fuel oil circulation according to the fuel oil pump start-up operation ticket; Detecting the oil gun and micro oil gun in the boiler; Testing the turbine AC lubricating oil pump, and recording the outlet oil pressure and current value; Testing the turbine DC lubricating oil pump, and recording the outlet oil pressure and current value; Testing the turbine air side DC sealing oil pump, and recording the oil pressure; Testing the turbine hydrogen side DC sealing oil pump, and recording the oil pressure; Testing the turbine top shaft oil pump, and recording the mother pipe oil pressure and current value; Testing the turbine turning gear motor, and recording the current value; Testing the turbine diesel generator, and recording the voltage value and current value, and detecting the switch closing; Warming the turbine high-pressure auxiliary steam supply shaft seal pipe; Warming the turbine high-pressure auxiliary steam supply deaerator pipe.

4. The method of claim 1, wherein, In the first stage, the steam turbine is in a coordinated control mode CCS, and the steam turbine load is reduced from 340MW to 250MW, comprising: Reducing the steam turbine load from 320MW to 250MW within 1 hour; Controlling the steam turbine main steam pressure at 17MPa, the steam turbine main steam flow at 800 tons / hour, the steam turbine main steam temperature at 540℃, and the steam turbine reheat steam temperature at 520℃, wherein the pressure drop rate is less than 0.1MPa / min, the main steam temperature drop rate is less than 1℃ / min, and the reheat steam temperature rate is less than 1℃ / min; Maintaining the first state of the steam turbine for 30 minutes, wherein the first state comprises: the steam turbine load is 250MW, the steam turbine main steam pressure is 17MPa, the steam turbine main steam temperature is 540℃, and the steam turbine reheat steam temperature is 520℃.

5. The method of claim 1, wherein, In the second stage, the steam turbine control mode is switched from the CCS mode to the power control mode, and the steam turbine load is reduced from 250MW to 180MW, comprising: maintaining the state of the steam turbine load being 180MW for 30 minutes.

6. The method according to claim 1 or 5, characterized in that, In the second stage, the steam turbine control mode is switched from the CCS mode to the power control mode, and the steam turbine load is reduced from 250MW to 180MW, further comprising at least one of the following operations: Adjusting the steam turbine shaft pressure to 25-45kPa; Adjusting the feedwater PH value to 9.6-10.5; Controlling the coal supply amount to be 120 tons / hour, and stopping the E bin pulverizing system.

7. The method of claim 1, wherein, The third stage, the turbine load is reduced from 180MW to 100MW, comprising: The turbine main steam pressure is controlled at 11.88MPa, the unit pressure is reduced and the temperature is reduced, the turbine main steam temperature is controlled at 500℃, and the turbine reheat steam temperature is controlled at 480℃.

8. The method according to claim 1 or 7, characterized in that, The third stage, the turbine load is reduced from 180MW to 100MW, further comprising at least one of the following operations: The coal supply is reduced to 100 tons / hour, the D bin is burned out, and the D bin pulverizing system is shut down; Maintain the vacuum less than-85kPa, reduce the air cooling fan frequency or shut down; When the electrical load is less than 35%, exit the turbine electrical load less than 30% and the water tank liquid level high protection, exit the total air volume low protection, exit the feed water flow low protection; The boiler drainage is preferentially recovered to the exhaust device, then to the water storage tank, and then externally discharged to the non-pressure water drain; When the turbine four-stage extraction steam pressure is less than 0.147MPa, the deaerator steam source is switched to the high-pressure steam auxiliary header; When the turbine three-extraction pressure is less than the deaerator 0.4MPa, the high-pressure heater drainage is switched to the exhaust device.

9. The method of claim 1, wherein, The fourth stage, the turbine load is reduced from 100MW to 35MW, comprising: The turbine main steam pressure is controlled at 8.9MPa, the turbine main steam temperature is controlled at 380℃, and the turbine reheat steam temperature is controlled at 360℃; Maintain the turbine second state for 30 minutes, the second state comprising: turbine load 35MW, turbine main steam pressure 8.9MPa, turbine main steam temperature 380℃, turbine reheat steam temperature 360℃.

10. The method according to claim 1 or 9, characterized in that, The fourth stage, the turbine load is reduced from 100MW to 35MW, further comprising: When the turbine load is reduced to 90MW, the feed water is switched from the main path to the bypass; When the turbine load is reduced to 70MW, the low-pressure section drainage valve is automatically opened; When the turbine load is reduced to 50MW, start the low-pressure cylinder water injection; When the turbine load is reduced to 35MW, open the high-pressure section drainage valve.

11. The method of claim 1 or 9, wherein, The fourth stage, the turbine load is reduced from 100MW to 35MW, further comprising at least one of the following operations: Start the turbine alternating current lubricating oil pump, the lubricating oil pressure is greater than or equal to 0.098MPa, and the diaphragm valve upper oil pressure is greater than 0.7MPa; Perform the turbine high-pressure exhaust valve activity test; Perform the turbine high-pressure main steam valve full stroke test; Perform the medium-pressure steam valve full stroke test; When two coal mills in the boiler are running, the oil gun is put into operation; According to the boiler combustion condition, determine whether to put into the oil gun, and shut down the electric dust removal after putting into the oil gun; The coal supply is reduced to 60 tons / hour, the A bin is burned out, and the A bin pulverizing system is stopped; The coal supply is reduced to 60 tons / hour, the C bin is burned out, and the C bin pulverizing system is stopped.

12. The method of claim 1, wherein, The execution of the shutdown operation, controlling the turbine shutdown, comprising: Apply for the provincial governor turbine unit disconnection; When the boiler coal mill coal supply is 0 tons / hour, the turbine is tripped; Check whether the turbine high-pressure and medium-pressure main steam valves and speed regulating valves are closed; Perform the turbine generator reverse power protection operation, the de-excitation switch is tripped, and the turbine speed is reduced; Report to the provincial governor that the turbine has been disconnected; According to the turbine generator and transformer group cold standby operation ticket, perform the turbine generator and transformer group cold standby operation; Perform the generator maintenance; Check if the extraction check valve of each section of the steam turbine is closed; Check if the high-pressure extraction check valve is closed and the high-pressure extraction valve is opened; After the boiler coal mill is purged, stop the boiler coal mill; Exit the boiler oil gun and the main fuel trip MFT extinguishing; Check if the boiler primary air fan and the seal air fan are interlocked to stop; Adjust the boiler air volume to be greater than or equal to 398 tons / hour and purge for 5 minutes; Stop the boiler air supply fan and the induced draft fan; Seal the furnace and close all the dampers and secondary air doors of the boiler air and flue gas system; Open the economizer exhaust valve; Check if the boiler drain door, air door and sampling door are closed; Close the overflow adjustment door and the electric door of the boiler water storage tank; Supply water to the boiler water storage tank at a flow rate of 60-120 tons / hour; Close the feedwater bypass adjustment door and the electric door when the water level in the boiler water storage tank is 12 meters, and the maximum water level is less than or equal to 18 meters; Stop the last feedwater pump of the steam turbine; Start the top shaft oil pump when the steam turbine speed is 1020 rpm; Check the pressure of the steam turbine top shaft oil main pipe and the lubricating oil pressure; When the steam turbine speed is 400 r / min, open the vacuum breaker door to a preset angle, and when the steam turbine speed is zero and the vacuum is zero; Exit the shaft seal system and stop the shaft seal air fan; Start the turning gear motor when the steam turbine speed is zero; Perform the hot insulation test operation ticket of the generator; Perform the steam turbine cylinder filling operation.

13. The method of claim 1, wherein, Further comprising: Controlling the opening degree of each layer of the boiler burner; wherein: The opening degree of the first layer of the burner is controlled to be 15%, the opening degree of the second layer of the burner is controlled to be 15%, the opening degree of the third layer of the burner is controlled to be 15%, the opening degree of the fourth layer of the burner is controlled to be 20%, the opening degree of the fifth layer of the burner is controlled to be 30%, and the opening degree of the sixth layer of the burner is controlled to be 50%; The first layer of the burner is located at the bottom layer, and the sixth layer of the burner is located at the highest layer.

14. A sliding parameter shutdown device for a steam turbine of a thermal power plant, characterized in that Comprise: An adjustment module is configured to adjust the blending ratio of coal in the raw coal bunker and to detect and adjust before the steam turbine is stopped; wherein, the raw coal bunker comprises A bunker, B bunker, C bunker, D bunker and E bunker, the ratio of Tianchi coal to well coal in A bunker, B bunker and C bunker is 5:1, and the ratio of Tianchi coal to blending material in D bunker and E bunker is 6:

1. The control module is used for controlling the load reduction of the steam turbine in stages, wherein in the first stage: the steam turbine is in a coordinated control mode CCS, and the load of the steam turbine is reduced from 340 MW to 250 MW; in the second stage: the control mode of the steam turbine is switched from the CCS mode to a power control mode, and the load of the steam turbine is reduced from 250 MW to 180 MW; in the third stage, the load of the steam turbine is reduced from 180 MW to 100 MW; and in the fourth stage, the load of the steam turbine is reduced from 100 MW to 35 MW; wherein in the first stage, the steam turbine is in the coordinated control mode CCS, and the load of the steam turbine is reduced from 340 MW to 250 MW, further comprising: controlling the power of the induced draft fan and / or the supply fan, so that the oxygen content of the boiler flue gas is controlled at 3.5-3.6%, and the concentration of nitrogen oxides is less than 50 mg per cubic meter; in the second stage, the control mode of the steam turbine is switched from the CCS mode to the power control mode, and the load of the steam turbine is reduced from 250 MW to 180 MW, further comprising: controlling the power of the induced draft fan and / or the supply fan, so that the oxygen content of the boiler flue gas is controlled at 3.6-4.0%, and the concentration of nitrogen oxides is less than 50 mg per cubic meter; in the third stage, the load of the steam turbine is reduced from 180 MW to 100 MW, further comprising: controlling the power of the induced draft fan and / or the supply fan, so that the oxygen content of the boiler flue gas is controlled at 4.0-6.0%, and the concentration of nitrogen oxides is less than 50 mg per cubic meter; and in the fourth stage, the load of the steam turbine is reduced from 100 MW to 35 MW, further comprising: controlling the power of the induced draft fan and / or the supply fan, so that the oxygen content of the boiler flue gas is controlled at 6.0-10.0%, and the denitration operation is exited; wherein in the third stage, the load of the steam turbine is reduced from 180 MW to 100 MW, further comprising: when the load of the steam turbine is less than 180 MW, the continuous soot blowing of the air preheater is maintained, and the steam source is switched to the high-pressure steam auxiliary header; when the load of the steam turbine is reduced to 170 MW, the feed water pump recirculation is started; when the load of the steam turbine is reduced to 120 MW, the constant pressure operation mode is entered, the pressure is maintained at 9.88 MPa, the boiler is switched to the wet state, and the overflow regulating valve of the water storage tank is started; when the load of the steam turbine is reduced to 110 MW, the main transformer neutral point 222D knife switch is closed; when the load of the steam turbine is greater than 105 MW, the average value of the flue gas temperature on either side of the denitration inlet is greater than or equal to 320°C; when the load of the steam turbine is less than 105 MW, the regulating valves and the quick closing valves of the boiler denitration A side and B side are closed; and when the load of the steam turbine is reduced to 100 MW, the power supply for plant use is switched to the high standby transformer, the electrical switching operation is performed, and the high-pressure and low-pressure heating steam sides are stopped to supply gas; The shutdown module is used for performing a shutdown operation to control the shutdown of the steam turbine.

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