CN113154430A - Supercritical unit fan mill control system and method - Google Patents
Supercritical unit fan mill control system and method Download PDFInfo
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- CN113154430A CN113154430A CN202110383950.7A CN202110383950A CN113154430A CN 113154430 A CN113154430 A CN 113154430A CN 202110383950 A CN202110383950 A CN 202110383950A CN 113154430 A CN113154430 A CN 113154430A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K1/00—Preparation of lump or pulverulent fuel in readiness for delivery to combustion apparatus
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C25/00—Control arrangements specially adapted for crushing or disintegrating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K1/00—Preparation of lump or pulverulent fuel in readiness for delivery to combustion apparatus
- F23K1/04—Heating fuel prior to delivery to combustion apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
- F23K3/02—Pneumatic feeding arrangements, i.e. by air blast
Abstract
The invention discloses a supercritical unit fan mill control system and a supercritical unit fan mill control method. High-temperature flue gas (about 1000 ℃) at the outlet of a hearth is mixed with hot secondary air (about 340 ℃) at the outlet of an air preheater and cold flue gas (about 120 ℃), the mixture is used as a drying agent to carry coal to enter a fan mill, and the coal enters a pulverized coal pipe through a pulverized coal separator at the outlet of the fan mill through the processes of drying, crushing, air pressure lifting and the like in the fan mill, so that the pulverized coal enters a hearth to be combusted. Wherein the cold flue gas is obtained by boosting the flue gas at the outlet of the air preheater by a cold flue gas fan.
Description
Technical Field
The invention belongs to the technical field of automatic control of thermal power plants, and relates to a system and a method for controlling a fan mill of a supercritical unit.
Background
The coal mill with fan is widely used in thermal power plant, and has simple structure, convenient manufacture, small occupied area and low metal consumption. The fan mill also has the advantages of simple powder making system, high powder discharging speed and the like. In addition, the fan mill integrates three functions of drying, crushing and conveying, and compared with other direct-blowing powder making systems such as a steel ball mill and a medium-speed mill, the arrangement of a primary fan can be reduced, and the layout of a wind-smoke system is simple. The existing fan coal mill is mainly used for grinding lignite and soft bituminous coal with high moisture (Mar is more than 30%) and low ash content (Aar is less than 15%).
The fan grinding powder system comprises a fan coal mill, a coal feeder, a cold smoke blower, a drying agent and related auxiliary equipment, wherein the drying agent can adopt a hot air single medium, a high-temperature smoke and a hot air mixed medium or a high-temperature smoke, a hot air mixed medium and a cold smoke mixed medium. At present, a fan mill direct-fired pulverizing system of a drying agent is mostly adopted in a large supercritical (super) critical unit thermal power plant burning lignite, wherein three media of high-temperature furnace smoke, hot air and low-temperature furnace smoke are used for forming the drying agent.
High-temperature flue gas (about 1000 ℃) at the outlet of a hearth is mixed with hot secondary air (about 340 ℃) at the outlet of an air preheater and cold flue gas (about 120 ℃), the mixture is used as a drying agent to carry coal to enter a fan mill, and the coal enters a pulverized coal pipe through a pulverized coal separator at the outlet of the fan mill through the processes of drying, crushing, air pressure lifting and the like in the fan mill, so that the pulverized coal enters a hearth to be combusted.
High-temperature flue gas is extracted from the upper part of a boiler hearth, and the temperature of the flue gas is lower than 1000 ℃. The low temperature flue gas is about 130 ℃ after being pumped from the electric dust collector. When three media of high-low temperature flue gas and hot air are used as drying agents, the hot air quantity can be kept unchanged generally, and the drying requirements of the coal mill under different working conditions can be met by adjusting the cold and hot flue gas quantity. The cold flue gas is blended to ensure CO in the drying agent of the powder making system2The content is more than 4 percent, and the danger of explosion of a powder making system is avoided. Particularly, when the coal mill is stopped, cold smoke at 130 ℃ is introduced into the coal mill, and the hot coal mill is idled, so that residual powder can be blown out, and the fan coal mill can be cooled.
Because the cold flue gas is added, a cold flue gas fan and a relatively long cold flue gas pipeline are required to be added, and therefore the initial construction investment and the operation and maintenance cost are increased. Simultaneously; and will bring some difficulties to the arrangement of the pulverizing system. In addition, the extracted cold flue gas contains lower water vapor and dust content; so as to avoid influencing the combustion process and reducing the abrasion of the smoke cooling fan, and an electric dust remover is required to be adopted. In addition, the temperature level in the boiler is reduced when cold flue gas enters the hearth, the combustion process is slowed down, the content of ash and slag combustible substances is increased, and the incomplete combustion heat loss of the boiler is increased.
A fan mill pulverizing system is adopted, a primary fan is not required to be arranged in the system, and high-temperature flue gas, hot secondary air and cold flue gas of a boiler jointly form drying air which is mixed and heated with raw coal in a mill. Meanwhile, the fan mill runs, and the drying air is boosted while raw coal is crushed, so that the speed of the air-powder mixture is increased, the rigidity of the mixture entering the furnace is ensured, the burning speed of pulverized coal is accelerated, and the inertia of the boiler is reduced. But simultaneously, the mixing of the inlet drying agent is relatively complex, the coupling relation exists between the hot air and the cold flue gas, the inlet temperature and the outlet temperature, and the adjustment is easy to interfere with each other.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a control system and a control method for a fan mill of a supercritical unit, which ensure that the temperature of the inlet of the fan mill is not over-temperature, the temperature of the outlet of the fan mill is normal and the oxygen content of the inlet of a coal mill is not over-standard, and simultaneously effectively crush and dry coal powder in time and convey the coal powder to a hearth for combustion, thereby improving the response speed of a boiler.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a supercritical unit fan mill control system comprising:
the coal from the outlet of the coal feeder is mixed with the high-temperature flue gas at the outlet of the hearth and then is conveyed to the fan mill;
the outlet of the fan mill is connected with a plurality of outlet powder pipes; after the incoming coal is dried, crushed and lifted by wind pressure, the incoming coal enters a powder pipe through a coal powder separator at an outlet of a fan mill and enters a hearth for combustion through the powder pipe.
The invention further improves the following steps:
coal from the coal feeder outlet is mixed with hot secondary air and then enters the fan mill.
The hot secondary air enters the fan mill through the hot secondary air regulating valve.
Coal from the coal feeder outlet is mixed with cold smoke air and then enters the fan mill.
And the cold smoke air enters the fan mill through the cold smoke air adjusting valve.
The cold flue gas is obtained by boosting the pressure of the flue gas at the outlet of the air preheater by a cold flue gas fan.
And an outlet recirculation door of the fan mill conveys the pulverized coal back to the fan mill through a recirculation valve.
A control method for a fan mill of a supercritical unit comprises the following steps:
the temperature of the outlet of the fan mill is kept stable, so that pulverized coal can enter a hearth and be combusted in time;
when the load of the unit is increased, low-temperature cold flue gas is merged into the drying agent, so that the outlet temperature is controlled, and the oxygen content of a grinding inlet is prevented from exceeding the standard;
the hot secondary air adjusting baffle and the cold flue gas adjusting baffle adopt the same PID regulator; according to the difference of the distribution functions of the two, the two simultaneously control the outlet temperature; when the oxygen amount at the inlet reaches an alarm limit value, the hot secondary air adjusting baffle is closed, and at the moment, if the temperature of the outlet of the fan mill is high, the temperature is independently controlled by the cold smoke air adjusting baffle; when the temperature of the mill inlet reaches an alarm limit value, locking the PID regulator; taking the coal feeder instruction and the coal quantity feedback as the feedforward of temperature control;
the low-temperature smoke is pumped out from the outlet of the air preheater by the cold smoke fan system, pressurized by two centrifugal parallel cold smoke fans, sent to the coal dropping pipe at the inlet of each coal mill, mixed with hot secondary air and then enters the coal mill as the cold working medium of a drying agent; under normal conditions, one cold smoke blower operates, and the inlet regulating valve of the cold smoke blower controls the air pressure of a main pipe at the outlet of the cold smoke blower, so that the flow of cold smoke under various loads and different working conditions is ensured to meet the cooling requirement of a coal mill; and the other cold smoke fan is standby, and the inlet regulating valve of the cold smoke fan tracks the instruction of the inlet regulating valve of the running fan, so that the output can be rapidly increased when the fan is started in a chain manner, and the stable running of the system is ensured.
Compared with the prior art, the invention has the following beneficial effects:
the invention aims at a fan mill analog quantity control system and a fan mill analog quantity control method, and considers the aspects of variable load feedforward (improving the quick response capability), inlet air temperature control, outlet air temperature control, inlet oxygen quantity control and the like, so that the inlet temperature of a fan mill is not over-temperature, the outlet temperature is normal, and the inlet oxygen quantity of a coal mill is not over-standard, and simultaneously, the pulverized coal fed into the mill is effectively crushed and dried in time and is conveyed to a hearth for burning, and the response speed of the boiler is improved.
Drawings
In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a diagram of a fan mill system;
FIG. 2 is a fan mill recirculation regulator valve logic diagram;
FIG. 3 is a variable load feed forward logic diagram for a boiler;
FIG. 4 is a variable load feedforward simulation curve for a boiler;
FIG. 5 is a logic diagram of fan mill temperature and oxygen control;
FIG. 6 is a control logic diagram of a cold fume fan.
Wherein: 1-fan mill, 2-recirculation valve, 3-cold smoke air regulating valve, 4-hot secondary air regulating valve.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually arranged when the product of the present invention is used, the description is merely for convenience and simplicity, and the indication or suggestion that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, cannot be understood as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, the embodiment of the invention discloses a supercritical unit fan mill control system, which comprises a coal feeder, a fan mill 1, high-temperature flue gas, a hot secondary air regulating valve, a cold flue gas regulating valve and a fan mill outlet recycling door. High-temperature flue gas (about 1000 ℃) at the outlet of a hearth is mixed with hot secondary air (about 340 ℃) at the outlet of an air preheater and cold flue gas (about 120 ℃), the mixture is used as a drying agent to carry coal to enter a fan mill, and the coal enters a pulverized coal pipe through a pulverized coal separator at the outlet of the fan mill through the processes of drying, crushing, air pressure lifting and the like in the fan mill, so that the pulverized coal enters a hearth to be combusted. Wherein the cold flue gas is obtained by boosting the flue gas at the outlet of the air preheater by a cold flue gas fan.
The operation of the fan mill is similar to that of a fan, along with the increase of the amount of coal entering the mill, the pulverized coal in the mill is crushed, the pressure head of the air-powder mixture is improved, and the powder discharging speed is increased, so that the variable load feedforward is directly applied to the fuel main control setting to directly control the rotating speed of the coal feeder.
Because the process of drying and striking and crushing the pulverized coal exists in the fan mill, the process has certain time inertia from coal feeding to pulverized coal output, and in order to further improve the response capability of the boiler, the variable load feedforward can be added to a control loop of a recirculation valve at the outlet of a coal mill: during the stable negative period, the recirculation valve is linearly controlled according to the output of the coal feeder to ensure proper coal powder fineness; when the load is increased (reduced), the opening degree of the recirculation valve is reduced (increased), so that the outlet pulverized coal is returned to the coal mill through the recirculation pipeline, the amount of the pulverized coal entering the coal mill is changed instantly, and the response capability of the boiler is improved.
Because the amount of the powder entering the boiler and the fineness of the pulverized coal are changed in a transient state in the variable load process, the actual water-coal ratio can be changed, and the oxygen amount at the outlet of the boiler and the temperature of a main steam reheater are changed, the variable load is fed forward to a water supply, air volume and temperature reduction water adjusting loop.
The purpose of controlling the temperature of the outlet of the fan mill is to ensure the drying degree of the pulverized coal, and under the condition of ensuring the safety of the coal mill, the temperature of the outlet of the fan mill is kept stable (130 ℃ and 180 ℃), so that the pulverized coal can be timely combusted when entering a hearth, and the control target of the pulverized coal requires that the temperature of the outlet is as stable as possible. The purpose of controlling the inlet temperature of the coal mill is to ensure that the inlet temperature is not over-temperature (less than or equal to 520 ℃) and ensure the safety of a coal pulverizing system, so a control loop of the coal mill has an over-temperature limiting function and ensures the safety of the system. Meanwhile, as the drying agent at the inlet of the coal mill contains air supply, if the air supply content is too large, the oxygen content in the coal mill is too high, and the drying agent is mixed with dry coal powder to easily cause explosion; therefore, the purpose of controlling the inlet oxygen is to ensure that the inlet oxygen does not exceed the limit (less than or equal to 12 percent) and ensure the safety of the system.
The fan mill drying agent is formed by mixing high-temperature flue gas, hot secondary air and cold flue gas. The high-temperature flue gas comes from the furnace outlet and provides a heating source. In the low-load stage of the unit, hot secondary air is used as a main cold source and is mixed with high-temperature flue gas, so that the inlet temperature of the coal mill is not over-temperature, the outlet temperature is controlled to be normal, and the drying output is ensured. When the load of the unit is increased, the temperature of the hot secondary air is increased, and in order to ensure the cooling effect, cold flue gas with lower temperature needs to be merged into the drying agent, so that the outlet temperature is effectively controlled, and the oxygen content of the ground inlet is prevented from exceeding the standard.
In order to avoid mutual disturbance, the hot secondary air adjusting baffle and the cold flue gas adjusting baffle adopt the same PID regulator, and under the normal condition, the hot secondary air adjusting baffle and the cold flue gas adjusting baffle simultaneously control the outlet temperature according to the difference of distribution functions of the hot secondary air adjusting baffle and the cold flue gas adjusting baffle. When the oxygen content at the inlet reaches the alarm limit value, the hot secondary air adjusting baffle is locked to be opened, and at the moment, if the temperature of the outlet of the fan mill is high, the temperature is independently controlled by the cold smoke air adjusting baffle. When the temperature of the inlet of the coal mill reaches the alarm limit value, the PID regulator is locked to be closed, so that the phenomenon of jumping and grinding caused by further increase of the temperature of the inlet of the coal mill is avoided. Meanwhile, in order to ensure the stability of the outlet temperature when the coal amount changes, the instruction of the coal feeder and the feedback of the coal amount are taken as feedforward of temperature control after being increased, and the temperature change is ensured to be normal under the dynamic condition.
The low-temperature smoke is pumped out from the outlet of the air preheater by the cold smoke fan system, pressurized by two centrifugal parallel cold smoke fans, sent to the coal dropping pipe at the inlet of each coal mill, mixed with hot secondary air and then enters the coal mill as the cold working medium of the drying agent. Under the normal condition, a cold smoke blower operates, and the inlet regulating valve controls the air pressure of the outlet main pipe of the cold smoke blower, so that the flow of cold smoke under various loads and different working conditions is ensured to meet the cooling requirement of a coal mill. And the other cold smoke fan is standby, and the inlet regulating valve of the cold smoke fan tracks the instruction of the inlet regulating valve of the running fan, so that the output can be rapidly increased when the fan is started in a chain manner, and the stable running of the system is ensured.
The principle and the working process of the invention are as follows:
the fan mill pulverizing system is not provided with a primary fan, a drying agent is formed by mixing high-temperature flue gas, hot secondary air and cold flue gas, and pulverized coal conveying force is provided by the rotation and boosting of the fan mill, so that the variable load feedforward response link is different from that of other direct-blowing pulverizing systems.
The operation of the fan mill is similar to that of a fan, along with the increase of the amount of coal entering the mill, the pulverized coal in the mill is crushed, the pressure head of the air-powder mixture is improved, and the powder discharging speed is increased, so that the variable load feedforward is directly applied to the fuel main control setting to directly control the rotating speed of the coal feeder.
As the fan mill has the processes of drying and striking and crushing the pulverized coal, the process has certain time inertia from coal feeding to pulverized coal output, and the variable load feed-forward can be added to the control loop of the coal mill outlet recirculation valve in order to further improve the response capability of the boiler. The control logic is shown in figure 2, and during the period of stable load, the recirculation valve is linearly controlled according to the output force of the coal feeder, so that the proper coal powder fineness is ensured. When the load is increased (reduced), the opening degree of the recirculation valve is reduced (increased), so that the outlet pulverized coal is returned to the coal mill through the recirculation pipeline, the amount of the pulverized coal entering the coal mill is changed instantly, and the response capability of the boiler is improved.
Because the amount of the powder entering the boiler and the fineness of the pulverized coal are changed in a transient state in the variable load process, the actual water-coal ratio can be changed, and the oxygen amount at the outlet of the boiler and the temperature of a main steam reheater are changed, the variable load is fed forward to a water supply, air volume and temperature reduction water adjusting loop.
As shown in fig. 3, the load command obtains the actual load change rate through a differential loop, the load change span and the set load change rate are calculated to obtain a variable load ending coefficient for performing the early braking function at the time of variable load ending, and the variable load ending coefficient are multiplied to obtain a basic boiler variable load feedforward value bir (boiler input rate). The BIR value is corrected by a lifting load function and respectively applied to loops such as coal feeding, water feeding, air supplying, temperature reducing water, a coal mill recirculation regulating valve and the like, so that the rapidity response of the boiler in a dynamic process and the stability of important parameters of steam temperature, steam pressure and oxygen quantity are ensured.
The process simulation curve is shown in fig. 4, at the time t0, the unit load instruction is increased, and the variable load feedforward value is output according to the actual load change rate. And at the time t1, a brake loop acts, and the variable load feedforward is reduced in advance, so that the overpressure of the system is prevented after the variable load is finished. At time t2, the unit load command reaches the target value, and the variable load feedforward is reduced to 0 according to the actual change rate. The braking point t1 is obtained according to the variable load span and the variable load rate, so as to meet the pressure regulation requirement when the variable load is finished under different working conditions.
The purpose of controlling the temperature of the outlet of the fan mill is to ensure the drying degree of the pulverized coal, and under the condition of ensuring the safety of the coal mill, the temperature of the outlet of the fan mill is kept stable (130 ℃ and 180 ℃), so that the pulverized coal can be timely combusted when entering a hearth, and the control target of the pulverized coal requires that the temperature of the outlet is as stable as possible. The purpose of controlling the inlet temperature of the coal mill is to ensure that the inlet temperature is not over-temperature (less than or equal to 520 ℃) and ensure the safety of a coal pulverizing system, so a control loop of the coal mill has an over-temperature limiting function and ensures the safety of the system. Meanwhile, as the drying agent at the inlet of the coal mill contains air supply, if the air supply content is too large, the oxygen content in the coal mill is too high, and the drying agent is mixed with dry coal powder to easily cause explosion; therefore, the purpose of controlling the inlet oxygen is to ensure that the inlet oxygen does not exceed the limit (less than or equal to 12 percent) and ensure the safety of the system.
The fan mill drying agent is formed by mixing high-temperature flue gas, hot secondary air and cold flue gas. The high-temperature flue gas comes from the furnace outlet and provides a heating source. In the low-load stage of the unit, hot secondary air is used as a main cold source and is mixed with high-temperature flue gas, so that the inlet temperature of the coal mill is not over-temperature, the outlet temperature is controlled to be normal, and the drying output is ensured. When the load of the unit is increased, the temperature of the hot secondary air is increased, and in order to ensure the cooling effect, cold flue gas with lower temperature needs to be merged into the drying agent, so that the outlet temperature is effectively controlled, and the oxygen content of the ground inlet is prevented from exceeding the standard.
The fan mill temperature and oxygen control logic is shown in fig. 5, and in order to avoid mutual disturbance, the hot secondary air adjusting baffle and the cold flue gas adjusting baffle adopt the same PID regulator. Normally, the two control the outlet temperature according to the difference of the two distribution functions. When the oxygen content at the inlet reaches the alarm limit value, the hot secondary air adjusting baffle is locked to be opened, and at the moment, if the temperature of the outlet of the fan mill is high, the temperature is independently controlled by the cold smoke air adjusting baffle. When the temperature of the inlet of the coal mill reaches the alarm limit value, the PID regulator is locked to be closed, so that the phenomenon of jumping and grinding caused by further increase of the temperature of the inlet of the coal mill is avoided. Meanwhile, in order to ensure the stability of the outlet temperature when the coal amount changes, the instruction of the coal feeder and the feedback of the coal amount are taken as feedforward of temperature control after being increased, and the temperature change is ensured to be normal under the dynamic condition.
The low-temperature smoke is pumped out from the outlet of the air preheater by the cold smoke fan system, pressurized by two centrifugal parallel cold smoke fans, sent to the coal dropping pipe at the inlet of each coal mill, mixed with hot secondary air and then enters the coal mill as the cold working medium of the drying agent. The control logic of the cold smoke blower is shown in fig. 6, under normal conditions, one cold smoke blower operates, and the inlet regulating valve controls the air pressure of the outlet main pipe of the cold smoke blower, so that the flow of cold smoke under various loads and different working conditions can meet the cooling requirement of the coal mill. And the other cold smoke fan is standby, and the inlet regulating valve of the cold smoke fan tracks the instruction of the inlet regulating valve of the running fan, so that the output can be rapidly increased when the fan is started in a chain manner, and the stable running of the system is ensured.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A supercritical unit fan mill control system is characterized by comprising:
the coal feeding machine is used for mixing the coal coming from the outlet of the coal feeding machine with the high-temperature flue gas at the outlet of the hearth and then conveying the mixture to the fan mill (1);
the fan mill (1), the outlet of the fan mill (1) is connected into a plurality of outlet powder pipes; after the incoming coal is dried, crushed and lifted by wind pressure, the incoming coal enters a powder pipe through a coal powder separator at an outlet of a fan mill and enters a hearth for combustion through the powder pipe.
2. The supercritical unit fan mill control system according to claim 1 is characterized in that the coal from the coal feeder outlet is mixed with hot secondary air and enters the fan mill (1).
3. Supercritical unit fan mill control system according to claim 2, characterized in that the hot secondary air enters the fan mill (1) through a hot secondary air regulating valve (4).
4. The supercritical unit fan mill control system according to claim 1 is characterized in that the coal from the coal feeder outlet is also mixed with cold flue gas and enters the fan mill (1).
5. Supercritical unit fan mill control system according to claim 4, characterized in that the cold flue gas enters the fan mill (1) through a cold flue gas regulating valve (3).
6. The control system of claim 5, wherein the cold flue gas is obtained by boosting the pressure of the flue gas at the outlet of the air preheater by a cold flue gas blower.
7. The supercritical unit fan mill control system according to claim 1 is characterized by the exit recirculation gate of the fan mill (1) transporting pulverized coal back to the fan mill (1) through the recirculation valve (2).
8. A supercritical unit fan mill control method using the system of any one of claims 1-7, comprising the steps of:
the temperature of the outlet of the fan mill is kept stable, so that pulverized coal can enter a hearth and be combusted in time;
when the load of the unit is increased, low-temperature cold flue gas is merged into the drying agent, so that the outlet temperature is controlled, and the oxygen content of a grinding inlet is prevented from exceeding the standard;
the hot secondary air adjusting baffle and the cold flue gas adjusting baffle adopt the same PID regulator; according to the difference of the distribution functions of the two, the two simultaneously control the outlet temperature; when the oxygen amount at the inlet reaches an alarm limit value, the hot secondary air adjusting baffle is closed, and at the moment, if the temperature of the outlet of the fan mill is high, the temperature is independently controlled by the cold smoke air adjusting baffle; when the temperature of the mill inlet reaches an alarm limit value, locking the PID regulator; taking the coal feeder instruction and the coal quantity feedback as the feedforward of temperature control;
the low-temperature smoke is pumped out from the outlet of the air preheater by the cold smoke fan system, pressurized by two centrifugal parallel cold smoke fans, sent to the coal dropping pipe at the inlet of each coal mill, mixed with hot secondary air and then enters the coal mill as the cold working medium of a drying agent; under normal conditions, one cold smoke blower operates, and the inlet regulating valve of the cold smoke blower controls the air pressure of a main pipe at the outlet of the cold smoke blower, so that the flow of cold smoke under various loads and different working conditions is ensured to meet the cooling requirement of a coal mill; and the other cold smoke fan is standby, and the inlet regulating valve of the cold smoke fan tracks the instruction of the inlet regulating valve of the running fan, so that the output can be rapidly increased when the fan is started in a chain manner, and the stable running of the system is ensured.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114669389A (en) * | 2022-03-01 | 2022-06-28 | 苏州西热节能环保技术有限公司 | Primary air pressure control method and device for coal mill, storage medium and electronic equipment |
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2021
- 2021-04-09 CN CN202110383950.7A patent/CN113154430A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114669389A (en) * | 2022-03-01 | 2022-06-28 | 苏州西热节能环保技术有限公司 | Primary air pressure control method and device for coal mill, storage medium and electronic equipment |
| CN114669389B (en) * | 2022-03-01 | 2024-01-02 | 苏州西热节能环保技术有限公司 | Primary air pressure control method and device for coal mill, storage medium and electronic equipment |
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