A control method for the main fuel trip signal of a pulverized coal boiler

Abstract

A control method for the main fuel trip signal of a pulverized coal boiler, belonging to the technical field of boiler protection. The present invention aims to solve the problem in the prior art of lacking an effective logic control method for the main fuel trip signal of a pulverized coal boiler. It includes: S1. Determine the fuel operation memory. If there is no fuel operation memory, repeat S1. If there is fuel operation memory, execute S2 and reset it with a 3-second delay after the main fuel trip signal is issued; S2. Determine the trip conditions of the main fuel trip signal. If there are no trip conditions, repeat S2. If there is any trip condition, execute S3; S3. Generate the main fuel trip signal and simultaneously interlock the equipment to perform a trip operation. The present invention is used for boilers with burners arranged in an octagonal form.

Description

Technical Field

[0001] The present invention relates to a control method for a main fuel trip valve signal, belonging to the technical field of boiler protection. Background Art

[0002] At present, as the main part of the boiler unit, the combustion condition inside the boiler furnace is extremely complex. At the same time, the boiler unit involves a large number of auxiliary equipment (such as coal conveying equipment, pulverized coal preparation equipment, and fan equipment). The coexistence of the two increases the unstable factors in the operation of the boiler. Therefore, the boiler always has potential risks of abnormal operation. Once an abnormal state occurs (including abnormal operation states of various equipment and abnormal shutdown of equipment), corresponding protection measures need to be taken immediately.

[0003] If the protection measures rely on operators to accurately start and stop or adjust parameters of important equipment within a short time to ensure the overall safety of the protection system, it is unrealistic. Therefore, it is necessary to upload the operation states of various equipment to the DCS (Distributed Control System). However, there is a lack of effective protection logic written into the DCS in the prior art. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of the lack of an effective logic control method for the main fuel trip signal of a pulverized coal boiler in the prior art, and provide a control method for the main fuel trip signal of a pulverized coal boiler.

[0005] A control method for the main fuel trip signal of a pulverized coal boiler according to the present invention includes:

[0006] S1. Determine the fuel operation memory. If there is no fuel operation memory, repeat S1. If there is a combustion operation memory, execute S2, and reset it with a 3S delay after the main fuel trip signal is issued;

[0007] S2. Determine the trip conditions of the main fuel trip signal. If there are no trip conditions, repeat S2. If there is any trip condition, execute S3;

[0008] S3. Generate a main fuel trip signal and simultaneously interlock the equipment to perform a trip action.

[0009] Preferably, the combustion operation memory in S1 includes:

[0010] When any one of the following three conditions exists, it is determined that there is a combustion operation memory:

[0011] The number of oil burners in operation is greater than or equal to 2;

[0012] The number of oil burners put into operation is greater than or equal to 3;

[0013] Any one of the coal corners is put into operation.

[0014] Preferably, the criterion for the oil burner to be put into operation is: the oil corner valve is open and there is fire;

[0015] The criterion for the low-oil burner to be put into operation is: the oil corner valve is open and there is fire;

[0016] The criterion for any one of the coal corners to be put into operation is: the coal mill is running, the coal feeder is running, and four out of five coal flame detectors have fire.

[0017] Preferably, the tripping conditions in S2 include: all forced draft fans stopped, all induced draft fans stopped, turbine tripped, feed water flow rate lower than 487.5 t / h, manual main fuel trip signal, furnace pressure high-high value ≥ 2.5 KPa, furnace pressure low-low value ≤ -2.5 KPa, total air volume low value < 25% of the maximum air volume, air preheater all stopped, fire detector cooling air lost, reheater protection lost, three ignition failures, ignition delay, all feed pumps stopped, all fuel lost, desulfurization requests main fuel trip, all flames lost, furnace skew protection, separator storage tank water level out of limit, and both power supplies of the main fuel trip lost.

[0018] Preferably, the tripping conditions specifically include:

[0019] The condition for all forced draft fans to stop is that any two of the following three situations exist: the negated value of the forced draft fan running signal; the forced draft fan current ≤ 5 A; there is a forced draft fan stop signal;

[0020] The condition for all induced draft fans to stop is that any two of the following three situations exist: the negated value of the induced draft fan running signal; the induced draft fan current ≤ 5 A; there is an induced draft fan stop signal;

[0021] The condition for the turbine to trip is: unit load ≥ 90 MW;

[0022] The condition for the feed water flow rate to be lower than 487.5 t / h is: all fuel not lost, and the feed water flow rate is low;

[0023] The condition for the manual main fuel trip signal is: any two of the three shutdown buttons on the console are pressed;

[0024] The condition for the furnace pressure high-high value ≥ 2.5 KPa is that any two of the following three situations exist: furnace pressure high-high value is 1, furnace pressure high-high value is 2, furnace pressure high-high value is 3;

[0025] The condition for the furnace pressure low-low value ≤ -2.5 KPa is that any two of the following three situations exist: furnace pressure low-low value is 1, furnace pressure low-low value is 2, furnace pressure low-low value is 3;

[0026] The condition for the low value of the total air volume < 25% of the maximum air volume is that any two of the following three situations exist: total air volume < minimum value 1, total air volume < minimum value 2, total air volume < minimum value 3;

[0027] The condition for the full stop of the air preheater is that the air preheater has been completely shut down;

[0028] The condition for the loss of the flame detector cooling air is that any one of the following two situations exists: the pressure of the main pipe of the flame detector cooling air is extremely low ≤ 3.23 kpa, the flame detector cooling fans have all been shut down;

[0029] The condition for the loss of the reheater protection is that any one of the following two situations exists: when there is steam blockage, the total fuel quantity > 128 t / h, that is, the fuel quantity corresponding to 20% of the maximum output condition; when there is steam blockage, the total fuel quantity > 192 t / h, that is, the fuel quantity corresponding to 30% of the maximum output condition;

[0030] The condition for three failed ignition attempts is: when the coal mill is in operation and no oil burner is in operation, an operation memory is generated, and any one oil corner valve is closed, and it is counted three times;

[0031] The condition for delayed ignition is that there is no burner operation memory 30 minutes after the main fuel trip signal is reset;

[0032] The condition for the full stop of the feed water pump is that there is a fuel operation memory;

[0033] The condition for the loss of all fuel is that the following three situations exist simultaneously: there is a fuel operation memory, any one of the inlet oil quick cut-off valve and the oil corner valve is closed, and any one of the coal mill and the coal feeder is stopped;

[0034] The condition for the desulfurization system to request the main fuel trip is that any two of the following three situations exist: the desulfurization system requests the main fuel trip signal is 1, the desulfurization system requests the main fuel trip signal is 2, the desulfurization system requests the main fuel trip signal is 3;

[0035] The condition for the loss of all flames is that any one of the following two situations exists: the oil burner is in operation, and there is an operation memory for the coal feeder and coal mill unit;

[0036] The condition for the furnace skew combustion protection is that any one of the following two situations exists: when three adjacent coal mills are in operation and there is no fire signal for the other corner coal burners, the oil flame of the other stopped corners is < 2 within 40 minutes; less than three coal mills are in operation and no oil burner is in operation;

[0037] The condition for the water level of the separator storage tank to exceed the limit is: the water level of the separator storage tank is high and exceeds the limit ≥ 16.8 M, the unit load < 180 MW, and the superheat degree at the outlet of the steam-water separator < 5 °C.

[0038] Preferably, the condition of low feed water flow rate is any two of the following three cases: the low-low value of feed water flow rate is 1, the low-low value of feed water flow rate is 2, and the low-low value of feed water flow rate is 3.

[0039] Preferably, the condition that the low-low value of the pressure of the master pipe of the fire detection cooling air ≤ 3.23 kPa is any two of the following three cases: the low-low value of the pressure of the master pipe of the fire detection cooling air is 1, the low-low value of the pressure of the master pipe of the fire detection cooling air is 2, and the low-low value of the pressure of the master pipe of the fire detection cooling air is 3;

[0040] The condition that all the fire detection cooling fans have been stopped is that all the fire detection cooling fans have tripped.

[0041] Preferably, the judgment condition of the steam blockage is any one of the following two cases:

[0042] Any one of the high-pressure main steam valve and the high-pressure regulating valve is fully closed, and any one of the high bypass inlet motorized valve and the high bypass regulating valve is fully closed;

[0043] Any one of the intermediate-pressure main steam valve and the intermediate-pressure regulating valve is fully closed, and the low bypass valve is fully closed.

[0044] Preferably, the condition that the high limit of the water level in the separator storage tank ≥ 16.8 m is any two of the following three cases: the high limit of the water level in the separator storage tank is 1, the high limit of the water level in the separator storage tank is 2, and the high limit of the water level in the separator storage tank is 3.

[0045] Preferably, the tripping action of the interlocking device in S3 includes: the hard relay of the master fuel trip trips, the fuel valve trips, the oil burner trips, the fuel quick cut-off valve closes, the coal mill trips, the coal feeder trips, the cold air fan trips, and the motor-driven feed water pump trips.

[0046] Advantages of the present invention: A control method for the master fuel trip signal of a pulverized coal boiler proposed by the present invention can effectively judge whether the operation of the boiler system is normal. When it is judged that there is a working condition endangering the safe operation of the boiler, a master fuel trip (MFT) signal is issued. After the signal is issued, the corresponding equipment will be interlocked (such as cutting off all the inputs of oil and coal entering the furnace, and at the same time interlocking the actions of other related equipment) to ensure the safety of the boiler and avoid the occurrence of accidents or limit the further expansion of accidents.

[0047] A control method for the main fuel trip signal of a pulverized coal boiler proposed by the present invention is applied to a boiler with burners arranged in an octagonal form (different from most boilers with pulverized coal combustion arranged in layers). In this kind of boiler, there is a situation of uneven burning (that is, the temperature at the same elevation in the furnace may be unevenly distributed). By using the control method proposed by the present invention, due to the addition of the logical judgment of the uneven burning state of the boiler, it can effectively judge the occurrence of uneven burning conditions and simultaneously issue corresponding interlock protection action instructions. The control method proposed by the present invention also includes the logical judgment of whether there is a blockage state in the superheater steam channel, which improves the safety of the operation of large boilers. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flowchart of a control method for the main fuel trip signal of a pulverized coal boiler according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0050] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0051] Next, the present invention will be further described in conjunction with the accompanying drawings and specific embodiments, but it is not a limitation of the present invention.

[0052] Embodiment 1:

[0053] Next, in combination with Figure 1 This embodiment will be described. The control method for the main fuel trip signal of a pulverized coal boiler described in this embodiment includes:

[0054] S1. Determine the fuel operation memory. If there is no fuel operation memory, repeat S1. If there is a fuel operation memory, execute S2, and reset it after a 3S delay after the main fuel trip signal is issued;

[0055] S2. Determine the trip conditions of the main fuel trip signal. If there are no trip conditions, repeat S2. If there is any trip condition, execute S3;

[0056] S3. Generate the main fuel trip signal and simultaneously interlock the equipment to trip.

[0057] Further, the fuel operation memory described in S1 includes:

[0058] When any of the following three conditions exists, it is determined that there is a combustion operation memory:

[0059] The number of oil burners in operation is greater than or equal to 2;

[0060] The number of less-oil burners in operation is greater than or equal to 3;

[0061] Any one of the coal corners is in operation.

[0062] In this embodiment, when any one of the coal corners is in operation, a combustion operation memory is issued after a 10s delay.

[0063] Furthermore, the criterion for the operation of the oil burner is: the oil corner valve is open and there is fire;

[0064] The criterion for the operation of the less-oil burner is: the oil corner valve is open and there is fire;

[0065] The criterion for the operation of any one of the coal corners is: the coal mill is running, the coal feeder is running, and four out of five coal flame detectors have fire.

[0066] Furthermore, the tripping conditions in S2 include: all forced draft fans stopped, all induced draft fans stopped, turbine tripped, feed water flow rate lower than 487.5 t / h, manual main fuel trip signal, furnace pressure high high value ≥ 2.5 KPa, furnace pressure low low value ≤ -2.5 KPa, total air flow rate low value < 25% of the maximum air flow rate, air preheater all stopped, fire detector cooling air lost, reheater protection lost, three ignition failures, ignition delay, all feed pumps stopped, all fuel lost, desulfurization requests main fuel trip, all flames lost, furnace uneven burning protection, separator storage tank water level limit exceeded, and both power supplies for the main fuel trip lost.

[0067] Furthermore, the tripping conditions specifically include:

[0068] The condition for all forced draft fans to stop is that any two of the following three conditions exist: the inverted value of the forced draft fan running signal; the forced draft fan current ≤ 5 A; there is a forced draft fan stop signal;

[0069] The condition for all induced draft fans to stop is that any two of the following three conditions exist: the inverted value of the induced draft fan running signal; the induced draft fan current ≤ 5 A; there is an induced draft fan stop signal;

[0070] The condition for the turbine to trip is: unit load ≥ 90 MW;

[0071] The condition for the feed water flow rate to be lower than 487.5 t / h is: all fuel not lost, and the feed water flow rate is low;

[0072] The condition for the manual main fuel trip signal is: any two of the three boiler stop buttons on the console are pressed;

[0073] The condition for the high-high value of furnace pressure ≥ 2.5 KPa is that any two of the following three cases exist: the high-high value of furnace pressure is 1, the high-high value of furnace pressure is 2, and the high-high value of furnace pressure is 3;

[0074] The condition for the low-low value of furnace pressure ≤ -2.5 KPa is that any two of the following three cases exist: the low-low value of furnace pressure is 1, the low-low value of furnace pressure is 2, and the low-low value of furnace pressure is 3;

[0075] The condition for the low value of total air volume < 25% of the maximum air volume is that any two of the following three cases exist: total air volume < minimum value 1, total air volume < minimum value 2, and total air volume < minimum value 3;

[0076] The condition for the full stop of the air preheater is that the air preheater has been completely out of service;

[0077] The condition for the loss of fire detection cooling air is that any one of the following two cases exists: the low-low value of the fire detection cooling air main pipe pressure ≤ 3.23 kpa, and the fire detection cooling fans have all been out of service;

[0078] The condition for the loss of reheater protection is that any one of the following two cases exists: when the steam is blocked, the total fuel quantity > 128 t / h, which is the fuel quantity corresponding to 20% of the maximum output condition; when the steam is blocked, the total fuel quantity > 192 t / h, which is the fuel quantity corresponding to 30% of the maximum output condition;

[0079] The condition for three ignition failures is that when the coal mill is in operation and no oil burner is in operation, an operation memory is generated, and any one oil corner valve is closed and counted three times;

[0080] The condition for delayed ignition is that there is no burner operation memory 30 minutes after the main fuel trip signal is reset;

[0081] The condition for the full stop of the feed water pump is that there is a fuel operation memory;

[0082] The condition for the loss of all fuel is that the following three cases exist simultaneously: there is a fuel operation memory, any one of the inlet oil quick cut-off valve and the oil corner valve is closed, and any one of the coal mill and the coal feeder stops;

[0083] The condition for the desulfurization system to request the main fuel trip is that any two of the following three cases exist: the desulfurization system requests the main fuel trip signal as 1, the desulfurization system requests the main fuel trip signal as 2, and the desulfurization system requests the main fuel trip signal as 3;

[0084] The condition for the loss of all flames is that any one of the following two cases exists: the oil burner is in operation, and there is an operation memory for the coal feeder and coal mill unit;

[0085] The conditions for furnace uneven burning protection are as follows: either of the two situations exists: when three adjacent coal mills are in operation and there is no fire signal for the remaining corner coal burners, the other stopped corner oil flames are <2 within 40 minutes; less than three coal mills are in operation and no oil burner is put into operation.

[0086] The conditions for the water level of the separator storage tank to exceed the limit are: the water level of the separator storage tank is high and exceeds the limit ≥16.8M, the unit load <180MW, and the superheat degree at the outlet of the steam-water separator <5°C.

[0087] In this embodiment, the conditions for turbine trip are: the unit load ≥90MW, and a main fuel trip signal is sent after a delay of 8s. The condition for the feed water flow to be lower than 487.5t / h is: all fuels are not lost, and the feed water flow is low, and a main fuel trip signal is sent after a delay of 10s. The condition for the total air volume low value <25% of the maximum air volume is that any two of the three situations exist: the total air volume < minimum value 1, the total air volume < minimum value 2, the total air volume < minimum value 3, and a main fuel trip signal is sent after a delay of 10s. The conditions for the loss of flame detector cooling air are that any one of the two situations exists: the pressure of the flame detector cooling air main pipe is extremely low and ≤3.23kpa, and a main fuel trip signal is sent after a delay of 900s; all flame detector cooling fans have been stopped, and a main fuel trip signal is sent after a delay of 600s. The conditions for the loss of reheater protection are that any one of the two situations exists: when the steam is blocked, the total fuel quantity >128t / h, that is, the fuel quantity corresponding to 20% of the BMCR (maximum output) condition, and the protection action is delayed for 20s; when the steam is blocked, the total fuel quantity >192t / h, that is, the fuel quantity corresponding to 30% of the BMCR (maximum output) condition, and the protection action is delayed for 10s; the oil burner fails to ignite 3 times: when any oil burner (excluding less oil) is put into operation without any coal mill in operation, it is delayed for 5s to generate an operation memory, any oil angle valve of #1 - #8 corners is closed, pulsed for 2s, and counted 3 times. The condition for delayed ignition is: there is no combustion burner operation memory 30 minutes after the main fuel trip signal is reset, specifically including: MFT is reset, delayed for 1800s, a 3s pulse is sent, all flame detectors have no fire (including less oil), and taking the non-operation of any oil layer or coal corner.

[0088] Furthermore, the conditions for the low feed water flow are that any two of the three situations exist: the low low value of the feed water flow is 1, the low low value of the feed water flow is 2, and the low low value of the feed water flow is 3.

[0089] Furthermore, the condition for the pressure of the flame detector cooling air main pipe to be extremely low and ≤3.23kpa is that any two of the three situations exist: the pressure of the flame detector cooling air main pipe is extremely low value 1, the pressure of the flame detector cooling air main pipe is extremely low value 2, and the pressure of the flame detector cooling air main pipe is extremely low value 3;

[0090] The condition for all flame detector cooling fans to have been stopped is: all flame detector cooling fans trip.

[0091] Further, the judgment conditions for steam blockage are any one of the following two cases:

[0092] Either the high-pressure main steam valve or the high-pressure governing valve is fully closed, and either the high bypass inlet motorized valve or the high bypass regulating valve is fully closed;

[0093] Either the intermediate-pressure main steam valve or the intermediate-pressure governing valve is fully closed, and the low bypass valve is fully closed.

[0094] Further, the condition for the water level in the separator storage tank to be higher than the limit ≥ 16.8M is any two of the following three cases: the water level in the separator storage tank is higher than the limit 1, the water level in the separator storage tank is higher than the limit 2, and the water level in the separator storage tank is higher than the limit 3.

[0095] Further, the tripping actions of the interlock device in S3 include: the main fuel trip hard relay trips, the fuel valve trips, the oil burner trips, the fuel quick cut-off valve closes, the coal mill trips, the coal feeder trips, the cold air fan trips, and the motor-driven feed water pump trips.

[0096] In the present invention, the condition for the unit load ≥ 90MW is that there are three hard wires set in the trip protection ETS cabinet, and any two of the three hard wires send out trip signals.

[0097] In the present invention, both the low value and the high value are alarm signals, which are only used to indicate mild abnormalities in the equipment operation and do not force the equipment to act. While the low-low value (lower than the low value) and the high-high value (higher than the high value) indicate serious abnormalities in the equipment operation, so reaching the high-high value or the low-low value will trigger necessary equipment actions.

[0098] In the present invention, there are three high furnace pressure high 2 / low 2 switches each, located at 84.25M of the high furnace, two on the left and one on the right.

[0099] In the present invention, the low value of the total air volume < 25%, that is, 642t / h.

[0100] In the present invention, the condition for the oil burner to lose all flames is that all the corner oils lose flames; the condition for any one corner oil to lose flames is that there is no fire detected by the oil flame detectors in the AB layer, CD layer, and EE layer.

[0101] The condition for the coal burner to lose all flames is that all the corner coal layers lose flames; the condition for any one corner coal layer to lose flames is any two of the following five cases: there is fire detected by the coal flame detectors in the A layer, B layer, C layer, D layer, and E layer of the burner.

[0102] In the present invention, since the input and removal of the coal mill in the octagonal furnace are unitized by angle, there is a problem of flame center deviation. When the oil burner is out of service, if the position numbers and quantities of the coal mills put into operation at this time are inappropriate, it will cause serious deviation of the flame center, leading to water circulation failure; or the energy in the furnace cannot meet the minimum ignition energy of the coal burner, and the combustion condition at this time is very unstable, and the possibility of flameout is very high, and the furnace should be shut down accordingly. Therefore, the MFT caused by uneven combustion is included in the full furnace flameout condition for treatment.

[0103] In the present invention, the judgment of the coal mill being without fire or with fire: The boiler has a total of 40 coal burners, 24 ignition oil guns, 20 lean oil guns, and 4 duct burners. "When 4 or more of the 5 coal burners corresponding to a coal mill are on fire, it can be judged that this coal mill is on fire, and when 2 or more of the 5 coal burners corresponding to a coal mill are without fire, it can be judged that this coal mill is without fire.

[0104] In the present invention, when the MFT trips, the first-out trip cause is displayed; when the MFT is reset, the first-out trip memory is cleared.

[0105] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not depart from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A control method for the main fuel trip signal of a pulverized coal boiler, characterized in that It includes: S1. Determine the fuel operation memory. If there is no fuel operation memory, repeat S1. If there is combustion operation memory, execute S2, and reset it with a 3S delay after the main fuel trip signal is issued. S2. Determine the trip conditions of the main fuel trip signal. If there are no trip conditions, repeat S2. If there is any trip condition, execute S3. S3. Generate the main fuel trip signal and simultaneously interlock the equipment to trip. The combustion operation memory described in S1 includes: When any one of the following three conditions exists, it is determined that there is combustion operation memory: The number of oil burners in operation is greater than or equal to 2; The number of lean oil burners in operation is greater than or equal to 3; Any one coal corner is in operation; The trip conditions described in S2 include: all forced draft fans stopped, all induced draft fans stopped, turbine trip, feed water flow rate lower than 487.5 t / h, manual main fuel trip signal, furnace pressure high high value ≥ 2.5 KPa, furnace pressure low low value ≤ -2.5 KPa, total air volume low value < 25% of the maximum air volume, air preheater all stopped, flame detector cooling air lost, reheater protection lost, three ignition failures, ignition delay, all feed pumps stopped, all fuel lost, desulfurization requests main fuel trip, all flames lost, furnace uneven burning protection, separator storage tank water level out of limit, and both power supplies of the main fuel trip lost.

2. The control method of the main fuel trip signal of a pulverized coal boiler according to claim 1, characterized in that, The criterion for the oil burner in operation is: the oil corner valve is open and there is fire. The criterion for the lean oil burner in operation is: the oil corner valve is open and there is fire. The criterion for any one coal corner in operation is: the coal mill is running, the coal feeder is running, and four out of five coal flame detectors have fire.

3. The control method of the main fuel trip signal of a pulverized coal boiler according to claim 1, characterized in that, The trip conditions specifically include: The condition for all forced draft fans stopped is that any two of the following three situations exist: the inverse value of the forced draft fan running signal; the forced draft fan current ≤ 5A; there is a forced draft fan stop signal. The condition for all induced draft fans stopped is that any two of the following three situations exist: the inverse value of the induced draft fan running signal; the induced draft fan current ≤ 5A; there is an induced draft fan stop signal. The condition for turbine trip is: the unit load ≥ 90 MW. The condition for the feed water flow rate lower than 487.5 t / h is: all fuel is not lost and the feed water flow rate is low. The condition for the manual main fuel trip signal is: any two of the three boiler stop buttons on the console are pressed. The condition for the furnace pressure high high value ≥ 2.5 KPa is that any two of the following three situations exist: furnace pressure high high value is 1, furnace pressure high high value is 2, furnace pressure high high value is 3. The condition for the furnace pressure low low value ≤ -2.5 KPa is that any two of the following three situations exist: furnace pressure low low value is 1, furnace pressure low low value is 2, furnace pressure low low value is 3. The condition for the total air volume low value < 25% of the maximum air volume is that any two of the following three situations exist: total air volume < minimum value 1, total air volume < minimum value 2, total air volume < minimum value 3. The condition for the air preheater all stopped is: the air preheater has been all stopped. The condition for the flame detector cooling air lost is that any one of the following two situations exists: the flame detector cooling air header pressure low low value ≤ 3.23 kpa, all flame detector cooling fans have been stopped. The conditions for the loss of reheater protection are any one of the following two cases: when there is steam blockage, the total fuel flow > 128 t / h, which is the fuel flow corresponding to 20% of the maximum output condition; when there is steam blockage, the total fuel flow > 192 t / h, which is the fuel flow corresponding to 30% of the maximum output condition; The conditions for three - time ignition failure are: when the coal mill is in operation and no oil burner is in operation, an operation memory is generated. If any one oil - angle valve is closed, it is counted three times; The conditions for delayed ignition are: there is no burner operation memory 30 minutes after the main fuel trip signal is reset; The conditions for all feed - water pumps to stop are: there is a fuel operation memory; The conditions for the loss of all fuel are the simultaneous presence of the following three cases: there is a fuel operation memory, any one of the inlet oil quick - cut valve and the oil - angle valve is closed, and any one of the coal mill and the coal feeder stops; The conditions for the desulfurization system to request a main fuel trip are any two of the following three cases: the desulfurization system requests a main fuel trip signal is 1, the desulfurization system requests a main fuel trip signal is 2, the desulfurization system requests a main fuel trip signal is 3; The conditions for the loss of all flames are any one of the following two cases: the oil burner is in operation, and there is an operation memory for the coal - grinding unit of the coal feeder; The conditions for furnace deviation - burning protection are any one of the following two cases: when three adjacent coal mills are in operation and there is no - fire signal for the other corner coal burners, the oil flame of the other stopped corners is < 2 within 40 minutes; less than three coal mills are in operation and no oil burner is in operation; The conditions for the separator storage tank water - level to exceed the limit are: the separator storage tank water - level high - limit ≥ 16.8 m, the unit load < 180 MW, and the superheat degree at the outlet of the steam - water separator < 5 °C.

4. The control method of the main fuel trip signal of a pulverized coal boiler according to claim 3, characterized in that, The conditions for the low feed - water flow are any two of the following three cases: the low - low value of the feed - water flow is 1, the low - low value of the feed - water flow is 2, the low - low value of the feed - water flow is 3.

5. A control method for the main fuel trip signal of a pulverized coal boiler according to claim 3, characterized in that, The conditions for the low - low value of the fire - detection cooling air main - pipe pressure ≤ 3.23 kPa are any two of the following three cases: the low - low value of the fire - detection cooling air main - pipe pressure is 1, the low - low value of the fire - detection cooling air main - pipe pressure is 2, the low - low value of the fire - detection cooling air main - pipe pressure is 3; The conditions for all fire - detection cooling fans to have stopped are: all fire - detection cooling fans have tripped.

6. The control method of the main fuel trip signal of a pulverized coal boiler according to claim 3, characterized in that, The judgment conditions for the steam blockage are any one of the following two cases: Any one of the high - pressure main steam valve and the high - pressure regulating valve is fully closed, and any one of the high - bypass inlet motorized valve and the high - bypass regulating valve is fully closed; Any one of the intermediate - pressure main steam valve and the intermediate - pressure regulating valve is fully closed, and the low - bypass valve is fully closed.

7. A control method for the main fuel trip signal of a pulverized coal boiler according to claim 3, characterized in that The conditions for the separator storage tank water - level high - limit ≥ 16.8 m are any two of the following three cases: the separator storage tank water - level high - limit is 1, the separator storage tank water - level high - limit is 2, the separator storage tank water - level high - limit is 3.

8. The control method of the main fuel trip signal of a pulverized coal boiler according to claim 1, wherein, The trip actions of the interlock equipment described in S3 include: the main fuel trip hard relay trips, the fuel valve trips, the oil burner trips, the fuel quick - cut valve closes, the coal mill trips, the coal feeder trips, the cold - air fan trips, and the motor - driven feed - water pump trips.

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