WO2023088279A1

WO2023088279A1 - System and method for improving rb working condition of induced draft fan of two-boiler one-machine thermal power generating unit

Info

Publication number: WO2023088279A1
Application number: PCT/CN2022/132140
Authority: WO
Inventors: 王田; 李楠; 赵容; 李颖博; 刘育婷; 马乐; 郝德锋; 常威武; 景丽; 朱洁; 葛欢
Original assignee: 西安热工研究院有限公司
Priority date: 2021-11-18
Filing date: 2022-11-16
Publication date: 2023-05-25
Also published as: CN113898971A

Abstract

A system and method for improving an RB working condition of an induced draft fan of a two-boiler one-machine thermal power generating unit. An outlet of a first boiler (1) is in communication with one end of a first induced draft main pipe (10), and the other end of the first induced draft main pipe (10) is in communication with an input end of a first induced draft fan (4) and an input end of a second induced draft fan (6); an outlet of a second boiler (11) is in communication with one end of a second induced draft main pipe (17), and the other end of the second induced draft main pipe (17) is in communication with an input end of a third induced draft fan (14) and an input end of a fourth induced draft fan (16); one end of a communicating pipe (18) is in communication with the first induced draft main pipe (10), and the other end of the communicating pipe (18) is in communication with the second induced draft main pipe (17); an electric regulating valve (9) is arranged on the communicating pipe (18); a first pressure transmitter (2) and a second pressure transmitter (12) are respectively arranged on the first boiler (1) and the second boiler (11); and a PID controller (8) is connected to each of the first pressure transmitter (2), the second pressure transmitter (12) and the electric regulating valve (9). The system can effectively solve the problem of induced draft fan RB caused by the failure of only one boiler induced draft fan in a two-boiler one-machine unit.

Description

A system and method for improving the RB working conditions of induced draft fans of two furnaces and one thermal power unit

technical field

The present disclosure relates to the technical field of automatic control of thermal power plants, in particular to a system and method for improving the working condition of RB of induced draft fans of two furnaces and one thermal power unit.

Background technique

The function of RB means that in the case of abnormality and failure of the auxiliary machine in operation, the unit load command and fuel quantity can respond quickly, and the main automatic control system of the unit cooperates with each other to quickly and stably reduce the unit load to the actual maximum output allowed by the unit , and ensure the continued safe operation of the unit. Among the existing thermal power units, most of the units are equipped with two induced draft fans with 60% rated output (because the induced draft fan and the booster fan of the desulfurization system are combined into one) as the main power output of the air and smoke system of the boiler. It is an important means to maintain the normal operation of the boiler under the micro-negative pressure state. When an induced draft fan fails and trips and loses its output capacity, the unit needs to shed 50% of the load at the fastest speed a unit can bear, withdraw 50% of the solid fuel, and quickly restore a stable combustion state. In the thermal power industry, this failure process is called induced draft RNUBACK, commonly known as induced draft fan RB. There are two situations in the RB working condition of the induced draft fan of the thermal power unit with two boilers: 1. The induced draft fan RB of one of the boilers trips due to a failure. The boiler must also follow the boiler with the induced draft fan system failure, at the same time at the same speed and ensure the steam quality, reduce the output to the target load, until the load of the entire unit is reduced to 50% of the rated load; two, each of the two boilers has an induced draft fan failure trip at the same time , triggering the RB working condition of the induced draft fan of the whole unit.

During the process of induced draft fan RB in two furnaces and one unit, the unit load controller will automatically and quickly shed the excess 50% load; The steam quality produced by each boiler is within the allowable deviation range for the normal operation of the unit) quickly reduce the excess fuel volume by 50%; at the same time, match the reduction speed of the fuel volume, and reduce the primary air volume of each boiler by 50% at the same time; two Boiler Furnace Negative Pressure Control System In order to maintain the constant furnace negative pressure, the blower fans of each boiler should also quickly reduce the output by 50%. The main function of the air induction system is to ensure the flow of air and smoke in the boiler furnace, thereby ensuring that the high-temperature flue gas after pulverized coal combustion passes through the high-temperature superheater, low-temperature superheater, economizer, air preheater, electrostatic precipitator, and desulfurization. A series of environmental protection and efficiency-enhancing facilities such as the system are arranged behind the furnace to make full use of the heat released by the pulverized coal after combustion and improve the thermal efficiency of the boiler; , leaving the furnace smoothly to provide enough power, thus also maintaining the pressure in the furnace is always within the allowable range of the unit. Therefore, when the output of the induced draft system is greatly reduced, it will directly affect the stability of the furnace negative pressure. When the induced draft fan RB occurs, the first thing that changes is the negative pressure of the furnace. The negative pressure of the furnace will suddenly drop off a cliff with the tripping of one induced draft fan in the induced draft system. The blower is used to match the induced draft system where the furnace suddenly loses 50% of its flow capacity. The negative pressure of the furnace will drop for a short time, and then the heat released by the burning of excess fuel that has not been withdrawn in time due to the sudden load reduction of the boiler in the furnace, The negative pressure of the furnace caused by the temporary and instantaneous climb, this process has a great challenge to the rapid response of the induced draft fan system. The rapid response of the induced draft fan may not be able to meet the rapid changes in the negative pressure of the furnace, and the result is that the unit trips due to the negative pressure of the furnace exceeding the limit.

Secondly, it reflects the instability of combustion in the furnace. When the induced draft fan RB occurs, the fuel system quickly withdraws from the pre-selected operating grinding group system at a certain rate (the maximum rate is set according to the boiler characteristics) to adapt to the unit load command after the induced draft fan RB. With the continuous withdrawal of the grinding group system , the rapid reduction of fuel entering the furnace, the heat released by the combustion of pulverized coal in the furnace is also less and less, but the boiler induced draft fan has to maintain the violently fluctuating negative pressure of the furnace at the protection value when its output is reduced by half In this way, the air flow field in the furnace is extremely unstable, which in turn causes the temperature field in the furnace to change drastically, and it is very easy to cause all the running grinding groups in the furnace to lose the fire conditions and exit the operating state, and finally the unit trips due to the fire extinguishing signal of the furnace.

After the occurrence of induced draft fan RB, because the auxiliary combustion air supply system also tripped a supply fan following the induced air system, the output of the auxiliary furnace combustion air supply system was insufficient, resulting in a large area of unburned pulverized coal remaining in the furnace. The extremely unstable aerodynamic field provides an opportunity for pulverized coal to stay in the tail flue of the boiler. As time goes on, the coal powder that is not fully burned in the tail flue will accumulate more and more. After reaching a certain level, it will Instant deflagration in the tail flue will damage the heat exchange area of the boiler tail flue and bring irreparable economic losses to the power generation company.

For two boilers and one machine master control unit, the consistency of boiler outlet steam quality is one of the key parameters restricting the safe operation of the unit. When the deviation of the steam parameters at the outlet of the two boilers exceeds the allowable value for the unit to maintain safe operation, the steam after the parallel valve During the fusion process, the steam pipe will vibrate violently, which will seriously break the steam pipe, expose high-temperature and high-pressure steam, and cause huge damage to personnel and equipment. When the induced draft fan RB occurs in the two boilers and one unit, the two boilers will keep the steam quality before the parallel valve within the allowable range under the premise of ensuring the safety of the unit, so as to ensure the smooth completion of the RB working condition of the unit. However, letting the two boilers drop to the target load of the RB working condition at the same limit speed is also a limit test for all auxiliary machines of the two boilers, and it is also a limit test for the professional skills of the boiler operators. Improper operation in any link will cause unplanned shutdown of the unit, and even equipment damage or personnel injury may occur, which will bring unimaginable personnel or economic losses to the power generation company.

There are several problems in the existing two-boiler and one-unit induced draft fan RB mode:

First, all the auxiliary machines of the entire unit quickly reduce the load by 50% at the same time, which brings obvious workload and mental pressure to the operating personnel; the rapid response of the equipment is also a great test for the quality of the equipment materials, and many times The hidden damage to the equipment caused by rapid and large load changes cannot be ignored.

Second, the RB of the induced draft fan occurs, and the air supply system trips an air supply fan in an emergency to match the flow capacity lost by the boiler's air and smoke system. The reduction in air volume caused a large area of unburned pulverized coal to stay in the furnace; however, the extremely unstable aerodynamic field at this time provided opportunities for the pulverized coal to stay in the tail flue of the boiler. As time went on, the tail smoke The pulverized coal that has not been fully burned in the flue will accumulate more and more, and when it reaches a certain level, it will deflagrate instantly in the tail flue, damaging the heat exchange area of the tail flue of the boiler, and bringing irreparable economic losses to the power generation company.

Thirdly, the induced draft fan RB causes the furnace negative pressure to fluctuate violently, and can even reach the limit protection value of the boiler in an instant, or even exceed the limit value, causing the unit to shut down unplanned; although the time for exceeding the limit protection value is not long, it is frequently exceeded. Operation is also a great test for the life of the boiler material.

Fourth, the RB of the induced draft fan occurs, and the load of the two boilers changes drastically at the same time. It is a huge challenge for the operating personnel to maintain the consistency of the steam quality before the parallel valve. Obviously, a little carelessness will cause unplanned shutdown of the unit in the mild case, and serious damage to the equipment of the unit in severe cases, which will bring immeasurable economic losses to the power generation company.

Contents of the invention

Aiming at the problems existing in the prior art, the present disclosure provides a system and method for improving the RB working condition of the induced draft fan of the two-boiler and one-machine thermal power unit, which can effectively solve the problem caused by the failure of only one boiler-induced fan in the two-boiler and one-machine unit. The RB problem of the induced draft fan can improve the stability of the induced draft fan RB of the two boilers and one thermal power unit, prolong the life of key boiler equipment, reduce the number of unplanned shutdowns of the main auxiliary equipment of the unit due to the induced draft fan RB, and reduce maintenance and repair costs. Significance.

In order to solve the above technical problems, the present disclosure is realized through the following technical solutions:

A system for improving the RB working condition of the induced draft fan of a thermal power unit with two boilers, including a first boiler, a first induced air main pipe, a first pressure transmitter, a first induced draft fan, a second induced draft fan, a second boiler, The second induced air main pipe, the second pressure transmitter, the third induced draft fan, the fourth induced draft fan, the communication pipe, the electric regulating valve and the PID controller, the outlet of the first boiler is connected to the first induced air main One end of the pipe is connected, the other end of the first induced air main pipe is connected with the input ends of the first induced draft fan and the second induced draft fan, and the outlet of the second boiler is connected with the second induced air main pipe. One end is communicated, the other end of the second induced air main pipe is communicated with the input ends of the third induced air fan and the fourth induced air fan, and one end of the communication pipe is communicated with the first induced air main pipe, The other end of the communication pipe communicates with the second air induction main pipe, the electric regulating valve is arranged on the communication pipe, and the first pressure transmitter and the second pressure transmitter are respectively arranged On the first boiler and the second boiler, the PID controller is respectively connected with the first pressure transmitter, the second pressure transmitter and the electric regulating valve.

Further, the electric regulating valve is located in the middle of the communicating pipe.

Further, the connection position between the communication pipe and the first air induction main pipe is close to the outlet of the first boiler, and the connection position between the communication pipe and the second air induction main pipe is close to the second Boiler outlet location.

Further, the input ends of the first induced draft fan and the second induced draft fan are respectively provided with a first valve and a second valve, and the input ends of the third induced draft fan and the fourth induced draft fan are respectively provided with a first valve. Three valves and a fourth valve.

Further, chimneys are connected to output ends of the first induced draft fan, the second induced draft fan, the third induced draft fan and the fourth induced draft fan.

Further, the PID controller selects ovation system or HNICS-T316.

A method for improving the working condition of the induced draft fan RB of the thermal power unit with two furnaces and one machine. Using the system, when the first induced draft fan, the second induced draft fan, the third induced draft fan and the fourth induced draft fan When any one of the induced draft fans fails, and the induced draft fan RB of the two furnaces and one thermal power unit is triggered, including:

Control the remaining three induced draft fans to work normally, and the PID controller controls and adjusts the electric adjustment on the connecting pipe according to the boiler furnace pressure collected by the pressure transmitter installed on the boiler corresponding to the failed induced draft fan. The opening of the valve makes the boiler furnace pressure corresponding to the failed induced draft fan within a safe fluctuation range, thereby making the first boiler and the second boiler tend to a stable state.

Further, before the induced draft fan RB of the two furnaces and one thermal power unit is triggered, if the unit load is greater than 75% of the rated load, control the remaining three induced draft fans to adjust the output to the maximum;

After the first boiler and the second boiler tend to be in a stable state, the remaining three induced draft fans are controlled to operate at a rated load at a certain speed.

Further, after the first boiler and the second boiler tend to a stable state, continue to control the remaining three induced draft fans to work normally, so that the unit load remains at 75% of the rated load.

Further, after the first boiler and the second boiler tend to be in a stable state, the load of the unit is reduced to 50% according to the preset load change rate, until any boiler corresponding to the failed induced draft fan is not connected. The induced draft fan is safely stopped, and while reducing the load of the unit, the PID controller controls and adjusts the pressure on the connecting pipe according to the boiler furnace pressure collected by the pressure transmitter installed on the boiler corresponding to the failed induced draft fan. The opening of the valve is electrically adjusted, so that the furnace pressure of the boiler corresponding to the failed induced draft fan is within the safe fluctuation range, so that the first boiler and the second boiler tend to be in a stable state.

Compared with the prior art, the present disclosure has at least the following beneficial effects: when any one of the first induced draft fan, the second induced draft fan, the third induced draft fan and the fourth induced draft fan fails, the two furnaces and one thermal power plant When the RB of the induced draft fan of the unit is triggered, the remaining three induced draft fans are controlled to work normally. The opening of the valve is adjusted so that the boiler furnace pressure corresponding to the failed induced draft fan is within a safe fluctuation range, so that the first boiler and the second boiler tend to a stable state. In the RB process of the induced draft fan of the two furnaces and one thermal power unit, the disclosure improves the target value of the load command of the unit, improves the rate of decline of the load command of the two furnaces and one machine, and shortens the process time of the induced draft fan RB of the two furnaces and one thermal power unit. Thereby the process of withdrawing the solid fuel of the unit from the furnace is delayed. When the induced draft fan RB occurs in the thermal power unit with two furnaces and one machine, the load of the unit does not need to drop rapidly, and all auxiliary machines of the unit do not need to cooperate with the rapid decrease of the load of the unit. The main parameters of the unit are furnace negative pressure, main fuel volume, main steam pressure, main Steam temperature, main feed water flow, etc. do not need to fluctuate greatly, which will bring unexpected losses to the unit. With the help of the present disclosure, when the induced draft fan RB of the thermal power unit with two boilers and one machine occurs, the operator only needs to calmly wait for the end of the induced draft fan RB process, and the working condition of the unit returns to stability. The disclosure minimizes the probability of equipment damage in the process of the induced draft fan RB of the two furnaces and one thermal power unit of the power generation enterprise, and reduces the number of unplanned shutdowns of the unit caused by the induced draft fan RB. Indirectly created economic benefits for power generation enterprises. On the basis of the hardware structure of the existing thermal power plant system, there is no need for complex hardware equipment modification, only a set of electric control valves, which can improve the range of negative pressure fluctuations in the furnace, reduce the probability of non-stop of the unit, or even greatly reduce, or The occurrence of major accidents such as furnace implosion or external explosion caused by the unstable negative pressure of the furnace is eliminated. Traditionally, the occurrence of induced draft fan RB of two furnaces and one thermal power unit can only be quickly responded to the rapid change of unit load by means of the unit coordination control system. However, when the induced draft fan RB occurs in the two boilers and one thermal power unit, the present disclosure can improve the actual situation of the lack of ventilation power of the accidental boiler through substantial means, and at the same time increase the target load of the induced draft fan RB working condition of the two furnaces and one thermal power unit, Improved the coordinated control system to complete the induced draft fan RB process of two furnaces and one thermal power unit, and changed the process of two furnaces and one thermal power unit to complete the induced draft fan RB process of two furnaces and one thermal power unit in the past only by means of control means or human intervention History. This disclosure chooses another boiler induction system to compensate for the lack of ventilation power of the unit because the two boilers have the same induction system, and the process is simple and easy to implement.

In order to make the above-mentioned objects, features and advantages of the present disclosure more comprehensible, preferred embodiments will be described in detail below together with the accompanying drawings.

Description of drawings

In order to more clearly illustrate the technical solutions in the specific embodiments of the present disclosure, the following will briefly introduce the drawings that need to be used in the description of the specific embodiments. Obviously, the drawings in the following description are some embodiments of the present disclosure , for those skilled in the art, other drawings can also be obtained according to these drawings on the premise of not paying creative work.

FIG. 1 is a schematic diagram of a system for improving the working condition of the induced draft fan RB of a thermal power unit with two furnaces and one machine according to the present disclosure.

In the figure: 1-the first boiler; 2-the first pressure transmitter; 3-the first valve; 4-the first induced draft fan; 5-the second valve; 6-the second induced draft fan; 7-the chimney; 8- PID controller; 9- electric regulating valve; 10- the first air induction main pipe; 11- the second boiler; 12- the second pressure transmitter; 13- the third valve; 14- the third induced draft fan; 15- the first Four valves; 16-the fourth induced draft fan; 17-the second induced draft main pipe; 18-connecting pipe.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are part of the embodiments of the present disclosure, not all of them. the embodiment. Based on the embodiments in the present disclosure, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present disclosure.

As a specific embodiment of the present disclosure, as shown in Figure 1, a system for improving the working condition of the induced draft fan RB of a thermal power unit with two furnaces and one machine includes a first boiler 1, a first induced air main pipe 10, a first pressure Transmitter 2, first induced draft fan 4, second induced draft fan 6, second boiler 11, second induced draft main pipe 17, second pressure transmitter 12, third induced draft fan 14, fourth induced draft fan 16, Connecting pipe 18, electric regulating valve 9 and PID controller 8, the outlet of the first boiler 1 communicates with one end of the first induced air main pipe 10, and the other end of the first induced air main pipe 10 communicates with the first induced draft fan 4 and the first induced air main pipe 10. The input ends of the two induced draft fans 6 are connected. Preferably, the input ends of the first induced draft fan 4 and the second induced draft fan 6 are respectively provided with a first valve 3 and a second valve 5 . The outlet of the second boiler 11 communicates with one end of the second induced air main pipe 17 , and the other end of the second induced air main pipe 17 communicates with the input ends of the third induced draft fan 14 and the fourth induced draft fan 16 . Preferably, the input ends of the third induced draft fan 14 and the fourth induced draft fan 16 are respectively provided with a third valve 13 and a fourth valve 15 . Preferably, chimneys 7 are connected to output ends of the first induced draft fan 4 , the second induced draft fan 6 , the third induced draft fan 14 and the fourth induced draft fan 16 .

One end of the communication pipe 18 communicates with the first air induction main pipe 10 , and the other end of the communication pipe 18 communicates with the second air induction main pipe 17 . Preferably, the connection position between the communication pipe 18 and the first air induction main pipe 10 is close to the outlet of the first boiler 1 , and the connection position between the communication pipe 18 and the second air induction main pipe 17 is close to the outlet of the second boiler 11 .

The electric regulating valve 9 is arranged on the connecting pipe 18 , preferably, the electric regulating valve 9 is located in the middle of the connecting pipe 18 .

The first pressure transmitter 2 and the second pressure transmitter 12 are arranged on the first boiler 1 and the second boiler 11 respectively, the first pressure transmitter 2 is used to collect the furnace pressure of the first boiler 1, and the second pressure The transmitter 12 is used to collect the furnace pressure of the second boiler 11 .

The PID controller 8 is respectively connected with the first pressure transmitter 2 , the second pressure transmitter 12 and the electric regulating valve 9 . The PID controller 8 is used to control and adjust the opening of the electric regulating valve 9 on the connecting pipe 18 according to the boiler furnace pressure collected by the pressure transmitter installed on the boiler corresponding to the induced draft fan that has failed, so that the induced draft fan that has failed can The corresponding boiler furnace pressure is within the safe fluctuation range, so that the first boiler 1 and the second boiler 11 tend to be in a stable state.

In this disclosure, the PID controller chooses Emerson's ovation system or Huaneng Ruiwo's HNICS-T316. For the electric control valve, choose Sibosi 2SA7321-2CE20-4BB4-Z or Shanghai Xingli LTCQ012.

The present disclosure discloses a method for improving the working condition of the induced draft fan RB of a thermal power unit with two furnaces, using compensation means to improve the working condition of the induced draft fan RB of a thermal power unit with two furnaces, and the first induced draft fan 4 connected to the first boiler 1 fails to trip. Trigger the induced draft fan RB of two furnaces and one thermal power unit, and take the other three induced draft fans as an example to describe the function of the disclosed system in the process of the induced draft fan RB of two furnaces and one thermal power unit, as follows:

When the first induced draft fan 4 fails and trips, and the induced draft fan RB of two boilers and one unit is triggered, the second boiler 11 does not need to trip one induced draft fan at the same time, and will not trigger the induced draft fan RB working condition like the first boiler 1. After an induced draft fan 4 trips, while the first valve 3 at the input end of the first induced draft fan 4 is closed, the electric regulating valve 9 on the communication pipe 18 between the first induced draft main pipe 10 and the second induced air main pipe 17 is supplied. A certain opening degree (the opening degree is related to the load of the unit before RB occurs, the greater the load, the greater the opening degree command), and adjust the output of the remaining three induced draft fans of the two boilers to the maximum (the unit load before RB occurs When the load is greater than 75% of the rated load, the output of the three induced draft fans needs to be adjusted to the maximum; when the load of the unit before the RB occurs is less than 75% of the rated load, the output value of the three induced draft fans is determined according to the load before the RB occurs. The greater the output of the three induced draft fans), the PID controller 8 is based on the boiler furnace pressure collected by the first pressure transmitter 2 installed on the first boiler 1 at this time, by opening and closing the two boilers. The electric regulating valve 9 between the pipes assists the first induced draft fan 6 to automatically adjust the furnace negative pressure of the first boiler 1. At this time, the two induced draft fans of the second boiler 11 continue to maintain the fluctuation of the furnace negative pressure of the second boiler 11 at a safe level. within range. The two induced draft fans of the second boiler pass through the connecting pipe 18 between the main ducts of the two boilers to supplement the air and smoke circulation power lost by the first boiler due to the trip of the first induced draft fan 4; the induced draft fan RB of the standby unit After the working condition gradually tends to a stable state, the three induced draft fans are slowly turned off at a certain rate to run at the rated load according to the actual situation of the unit. During this process, the PID controller 8 between the two boilers always assists the first The induced draft fan 6 ensures that the negative pressure fluctuation of the furnace of the first boiler is within the allowable range for the safe operation of the unit. Under the improvement method of the present disclosure, after two furnaces and one induced draft fan RB are triggered, the induced draft system of the entire unit can be regarded as a whole, and in the case of losing the output of one induced draft fan, the furnace ventilation power of the entire unit has a surplus In other words, the entire unit still maintains 75% of the furnace ventilation capacity, so the RB target load of the induced draft fan for the thermal power unit with two furnaces and one machine can be completely optimized to 75% of the rated load. After the working condition of the induced draft fan RB of the thermal power unit with two furnaces and one machine is stable, the unit operators have two options: first, the unit continues to operate normally at 75% of the rated load; Safely reduce unit load to 50% until the ID fan of the other non-faulty boiler is safely stopped. During this process, the PID controller 8 always maintains the negative pressure of the first boiler furnace fluctuating within the allowable range for the safe operation of the unit through the electric regulating valve 9 on the connecting pipe between the main pipes of the two boiler induced draft fans, until the non-faulty boiler stops safely. One induced draft fan. At this time, after the output of the induced draft fan system of the two boilers is gradually balanced, the opening of the electric regulating valve 9 on the connecting pipe between the induced air main pipes of the two boilers is also slowly closed until it is closed. At this time The PID controller 8 also stops working, which indicates that the present disclosure successfully helps two furnaces and one thermal power unit to complete the RB working condition of the induced draft fan. If it is the induced draft fan RB of the thermal power unit with two furnaces and one machine caused by the tripping of the other three induced draft fans, the process is the same as the above induced draft fan RB process.

Example

As shown in Figure 1, taking the first induced draft fan 4 fault tripping, triggering the induced draft fan RB of the two boilers and one machine unit, the unit is running at 100% rated load before RB is triggered, and the other three induced draft fans are normal. The role of the system in the process of induced draft fan RB of two furnaces and one thermal power unit.

When the first induced draft fan 4 fails and trips, and the induced draft fan RB of two boilers and one unit is triggered, the second boiler 11 does not need to trip one induced draft fan at the same time, and will not trigger the induced draft fan RB working condition like the first boiler 1. After an induced draft fan 4 trips, while the first valve 3 at the input end of the first induced draft fan 4 is closed, the electric regulating valve 9 on the communication pipe 18 between the first induced draft main pipe 10 and the second induced air main pipe 17 is supplied. Directly open to 80% (reserve a certain adjustment method), and adjust the remaining three induced draft fans of the two boilers to the maximum output (general induced draft fan selection, the maximum output is greater than 50% of the rated load), at this time PID control According to the fluctuation value of the boiler furnace negative pressure collected by the first pressure transmitter 2 installed on the first boiler 1 at this time, the device 8 assists the second induced draft fan 6 to automatically adjust the first pressure through the electric regulating valve 9 between the two boilers. The furnace negative pressure of boiler 1 fluctuates between -2000Pa and 2000Pa, try to supplement the ventilation power lost by the first boiler due to the tripping of the first induced draft fan 4; after the parameters of the two boilers gradually tend to a stable state, three According to the actual situation of the unit, the induced draft fan is slowly turned off at 1%/min to run at the rated load. During this process, the PID controller 8 always maintains the negative pressure of the first boiler furnace between -2000Pa and 2000Pa. Under the improvement method of the present disclosure, after two furnaces and one induced draft fan RB are triggered, the induced draft system of the entire unit can be regarded as a whole, and in the case of losing the output of one induced draft fan, the furnace ventilation power of the entire unit has a surplus In other words, the entire unit still maintains 75% of the furnace ventilation capacity, so the RB target load of the induced draft fan for the thermal power unit with two furnaces and one machine can be completely optimized to 75% of the rated load. After the working condition of the induced draft fan RB of the two furnaces and one thermal power unit is stable, the unit operators have two options: first, the unit continues to operate normally at 75% of the rated load; Speed, safely reduce the unit load to 50%, until the induced draft fan of the second boiler is safely stopped. During this process, the PID controller 8 always maintains the furnace negative pressure of the first boiler between -2000Pa and 2000Pa through the electric regulating valve 9 on the connecting pipe between the two boiler induction main pipes, until the second boiler safely stops one induction pipe. Fan, at this time, after the output of the induced draft fan system of the two boilers is gradually balanced, the opening of the electric regulating valve 9 on the connecting pipe between the induced draft main pipes of the two boilers is also slowly closed until it is closed. At this time, the PID controller It also stopped working, indicating that the improved method of the present disclosure successfully helped two furnaces and one thermal power unit to complete the RB working condition of the induced draft fan.

Finally, it should be noted that: the above-mentioned embodiments are only specific implementations of the present disclosure, and are used to illustrate the technical solutions of the present disclosure, rather than limit them, and the protection scope of the present disclosure is not limited thereto, although referring to the aforementioned The embodiments have described the present disclosure in detail, and those skilled in the art should understand that any person familiar with the technical field can still modify the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present disclosure Changes can be easily imagined, or equivalent replacements can be made to some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should be included in this disclosure. within the scope of protection. Therefore, the protection scope of the present disclosure should be defined by the protection scope of the claims.

Claims

A system for improving the working condition of the induced draft fan RB of a thermal power unit with two furnaces, characterized in that it includes a first boiler (1), a first induced air main pipe (10), a first pressure transmitter (2), a second One induced draft fan (4), the second induced draft fan (6), the second boiler (11), the second induced draft main pipe (17), the second pressure transmitter (12), the third induced draft fan (14), The fourth induced draft fan (16), connecting pipe (18), electric regulating valve (9) and PID controller (8), the outlet of the first boiler (1) and the first induced air main pipe (10) One end of the first induced draft main pipe (10) communicates with the input ends of the first induced draft fan (4) and the second induced draft fan (6), and the second boiler (11) The outlet communicates with one end of the second induced-air main pipe (17), and the other end of the second induced-air main pipe (17) is connected with the third induced-air fan (14) and the fourth induced-air fan (16). ), one end of the communication pipe (18) communicates with the first air induction main pipe (10), and the other end of the communication pipe (18) communicates with the second air induction main pipe (17 ), the electric regulating valve (9) is set on the connecting pipe (18), and the first pressure transmitter (2) and the second pressure transmitter (12) are respectively set on the On the first boiler (1) and the second boiler (11), the PID controller (8) is connected with the first pressure transmitter (2) and the second pressure transmitter (12) respectively It is connected with the electric regulating valve (9).
A system for improving the working condition of induced draft fan RB of two furnaces and one thermal power unit according to claim 1, characterized in that the electric regulating valve (9) is located in the middle of the connecting pipe (18).
A system for improving the working condition of induced draft fan RB of thermal power unit with two furnaces and one engine according to claim 1, characterized in that, the connection position between the connecting pipe (18) and the first induced air main pipe (10) Close to the outlet of the first boiler (1), the connecting position of the communication pipe (18) and the second air induction main pipe (17) is close to the outlet of the second boiler (11).
A system for improving the working condition of the induced draft fan RB of a thermal power unit with two furnaces and one engine according to claim 1, wherein the input ends of the first induced draft fan (4) and the second induced draft fan (6) A first valve (3) and a second valve (5) are respectively provided, and the input ends of the third induced draft fan (14) and the fourth induced draft fan (16) are respectively provided with a third valve (13) and a second Four valves (15).
A system for improving the working condition of the induced draft fan RB of a thermal power unit with two furnaces and one machine according to claim 1, characterized in that, the first induced draft fan (4), the second induced draft fan (6), the described Chimneys (7) are connected to output ends of the third induced draft fan (14) and the fourth induced draft fan (16).
A system for improving the working condition of induced draft fan RB of two furnaces and one thermal power unit according to claim 1, characterized in that the PID controller (8) selects the ovation system or HNICS-T316.
A method for improving the working condition of the induced draft fan RB of a thermal power unit with two furnaces, characterized in that, the system according to any one of claims 1 to 6 is applied, when the first induced draft fan (4), the second induced draft fan (4) Any one of the second induced draft fan (6), the third induced draft fan (14) and the fourth induced draft fan (16) fails, and when the induced draft fan RB of the two furnaces and one thermal power unit is triggered, it includes:

Control the remaining three induced draft fans to work normally, and the PID controller (8) controls and adjusts the connecting pipe (18) according to the boiler furnace pressure collected by the pressure transmitter installed on the boiler corresponding to the failed induced draft fan The electric adjustment valve (9) on the opening degree makes the boiler furnace pressure corresponding to the failed induced draft fan within the safe fluctuation range, so that the first boiler (1) and the second boiler (11) tends to a stable state.
According to claim 7, a method for improving the working condition of the induced draft fan RB of the thermal power unit with two furnaces, characterized in that, before the induced draft fan RB of the thermal power unit with two furnaces is triggered, if the load of the unit is greater than 75% of the rated load , control the remaining three induced draft fans to adjust the output to the maximum;

After the first boiler (1) and the second boiler (11) tend to be in a stable state, the remaining three induced draft fans are controlled to operate at a rated load at a certain speed.
A method for improving the working condition of the induced draft fan RB of a thermal power unit with two boilers and one engine according to claim 7, characterized in that, after the first boiler (1) and the second boiler (11) tend to be in a stable state , continue to control the normal operation of the remaining three induced draft fans, so that the unit load remains at 75% of the rated load.
A method for improving the working condition of the induced draft fan RB of a thermal power unit with two boilers and one engine according to claim 7, characterized in that, after the first boiler (1) and the second boiler (11) tend to be in a stable state , reduce the unit load to 50% according to the preset load change rate, until any induced draft fan corresponding to the boiler that is not connected to the failed induced draft fan stops safely, while reducing the unit load, the PID controller ( 8) According to the boiler furnace pressure collected by the pressure transmitter installed on the boiler corresponding to the induced draft fan that has failed, control and adjust the opening of the electric regulating valve (9) on the connecting pipe (18), so that The furnace pressure of the boiler corresponding to the faulty induced draft fan is within the safe fluctuation range, so that the first boiler (1) and the second boiler (11) tend to be in a stable state.