CN115076679B - Reheat steam temperature control method for tail three-flue secondary reheat boiler - Google Patents
Reheat steam temperature control method for tail three-flue secondary reheat boiler Download PDFInfo
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 131
- 239000003546 flue gas Substances 0.000 claims description 131
- 238000012937 correction Methods 0.000 claims description 15
- 238000010248 power generation Methods 0.000 claims description 13
- 239000000779 smoke Substances 0.000 claims description 11
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- 239000004071 soot Substances 0.000 claims description 2
- 238000003303 reheating Methods 0.000 abstract description 13
- 239000007921 spray Substances 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 2
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Abstract
The invention discloses a reheat steam temperature control method of a tail three-flue secondary reheat boiler, which aims at the problem that the reheat steam temperature is difficult to control rapidly and accurately in a peak regulation transient process of a tail three-flue secondary reheat coal-fired generator set. The steam temperature control method for cooperatively improving the transient operation safety, high efficiency and flexibility of the double-reheat coal-fired generator set is formed by taking the outlet temperature control of the first and second low-temperature reheaters as low temperature Duan Huilu and taking the outlet temperature control of the first and second reheat steam as a high-temperature end loop and simultaneously cooperatively reheating micro water spray control.
Description
Technical Field
The invention belongs to the field of steam temperature control of coal-fired power plants, and particularly relates to baffle characteristics and transient temperature regulation control of a secondary reheating boiler with a three-flue at the tail part, which plays a key role in temperature control of a unit peak regulation transient process in baffle opening control, reduces reheat water spray quantity of the unit peak regulation transient process, and realizes cooperation of safety, flexibility and economy of the unit peak regulation transient process. The invention can be adopted and used for power plants frequently participating in peak shaving.
Background
In recent years, renewable energy sources such as wind energy, solar energy and the like are rapidly developed, and a power grid is in need of a high-flexibility power supply to stabilize load fluctuation of renewable energy source power generation. The coal-fired power generation is gradually changed from main energy sources to basic energy sources, and the secondary reheating coal-fired power generation technology has the remarkable advantages of ultrahigh operation efficiency, ultralow emission and the like, and is the development direction of efficient clean coal-fired power generation in the future. The heating surface of the tail three-flue boiler fully utilizes the heat of low-temperature section flue gas, and effectively controls the steam temperature through the opening adjustment of a tail flue gas baffle, so that the boiler is a main furnace type in the design of the secondary reheating boiler.
With further increase of peak shaving demands of the power grid on the coal-fired generator set, peak shaving of the secondary reheating unit is increasingly frequent. But the thermal inertia of the secondary reheating unit is larger than that of the primary reheating unit with the same grade, the reheat steam temperature delay characteristic is more obvious, and the steam temperature control logic is required to be further optimized in the peak shaving transient process so as to improve the dynamic response speed of parameters.
Disclosure of Invention
The invention provides a reheat steam temperature control method of a tail three-flue secondary reheat boiler for improving the reheat steam temperature control effect of the tail three-flue secondary reheat boiler, and the invention gives consideration to the sectional control of reheat steam outlet temperature and low-temperature section temperature, takes the control of the outlet temperature of a primary low-temperature reheater and the control of the outlet temperature of a secondary low-temperature reheater as low temperature Duan Huilu and takes the control of the outlet temperature of the primary reheat steam and the control of the outlet temperature of the secondary reheat steam as a high-temperature section loop, thereby forming a steam temperature control method for cooperatively improving the transient operation safety, high efficiency and flexibility of a secondary reheat coal-fired generator set.
The technical scheme adopted for solving the technical problems is as follows:
the control logic comprises a low-temperature superheater side smoke baffle control logic, a primary low-temperature reheater side smoke baffle control logic and a secondary low-temperature reheater side smoke baffle control logic;
The low-temperature superheater side flue gas baffle control logic is used for adjusting heat distribution between the low-temperature superheater and the low-temperature reheater; in the peak regulation transient process of the coal-fired power generation unit, the opening of the low-temperature superheater side flue gas baffle takes a set value under a steady-state working condition of the unit as a reference, a low temperature Duan Huilu is formed by taking a deviation value of the steam outlet of the low-temperature reheater, namely, the difference between the set value and an actual value as a reference 1, and a high-temperature section loop is constructed by taking a deviation value of the steam outlet of the high-temperature reheater as a reference 2, so that a low-passing side flue gas baffle subsection control logic is formed; the method specifically comprises the following steps:
a function of setting load and controlling opening degree of a low-temperature superheater side flue gas baffle
Establishing a steady-state set value function F 1 (x) of the load and the low-temperature superheater side flue gas baffle, a function F 2 (x) between the load and the average value of the steam temperature set values of the outlets of the primary and secondary low-temperature reheaters, and a function F 3 (x) between the load and the average value of the steam temperature set values of the outlets of the primary and secondary high-temperature reheaters;
(II) establishing logic for controlling low temperature Duan Huilu by using low-temperature superheater side flue gas baffle
When the unit operates under a certain load x, an average value T rh,avg1,sp of steam temperature set values of the outlets of the primary and secondary low-temperature reheaters under the current load is obtained through F 2 (x); further calculating the average value of the steam temperature measured values of the outlets of the primary and secondary low-temperature reheaters; the average value of the set value and the average value of the measured value are subjected to difference, and are input into a PID controller, so that the flue gas baffle opening correction quantity delta beta sh,1 calculated by the low-temperature section loop control logic is obtained;
Third, a low-temperature superheater side smoke baffle control high-temperature section loop logic is formulated
When the unit operates under a certain load x, obtaining an average value T rh,avg2,sp of set values of the steam temperatures of the outlets of the primary and secondary high-temperature reheaters under the current load through F 3 (x); and further calculating the average value of the steam temperature measurement values of the outlets of the primary and secondary high-temperature reheaters. The average value of the set value and the average value of the measured value are subjected to difference, and are input into a PID controller, so that the flue gas baffle opening correction quantity delta beta sh,2 calculated by the control logic of the high-temperature section loop is obtained;
(IV) forming a low-temperature superheater side smoke baffle control instruction
Obtaining a set value beta sh,sp of the opening of a low-temperature superheater side flue gas baffle under the current load through F 1 (x), and adding beta sh,sp、Δβsh,1 and delta beta sh,2 to obtain a low-temperature superheater side flue gas baffle control instruction beta sh;
The control logic of the flue gas baffle at the side of the primary low-temperature reheater is used for adjusting heat distribution between the primary low-temperature reheater and the secondary low-temperature reheater; in the peak regulation transient process of the coal-fired power generator unit, the opening of a flue gas baffle at the side of the primary low-temperature reheater takes a set value under the steady-state working condition of the coal-fired power generator unit as a reference, a high-temperature section loop is formed by taking the relative value of the steam outlet temperature deviation of the secondary high-temperature reheater and the steam outlet temperature deviation of the primary high-temperature reheater as a flue gas baffle adjustment basis 1, a low-temperature Duan Huilu is formed by taking the relative value of the steam outlet temperature deviation of the secondary low-temperature reheater and the steam outlet temperature deviation of the primary low-temperature reheater as a flue gas baffle adjustment basis 2, and a primary low-temperature side flue gas baffle subsection control logic is constructed; the method specifically comprises the following steps:
Firstly, establishing a corresponding function F 4 (x) between the load and a set value of the opening of the flue gas baffle at the side of the primary low-temperature reheater by setting a corresponding function related to the opening control logic of the flue gas baffle at the side of the primary low-temperature reheater;
second, a control logic for controlling a high-temperature section loop by a flue gas baffle at the side of the primary low-temperature reheater is formulated
Calculating the difference between the steam temperature set value T rh2,2,sp of the outlet of the secondary high-temperature reheater and the steam temperature set value T rh1,2,sp of the outlet of the primary high-temperature reheater under the current load, wherein the difference is simply called as 'set value deviation'; further calculating the difference between the steam temperature measured value T rh2,2 of the outlet of the secondary high-temperature reheater and the steam temperature measured value T rh1,2 of the outlet of the primary high-temperature reheater, which is simply called as 'actual value deviation'; the deviation of the set value and the deviation of the actual value are subjected to difference and input into a PID controller, and the baffle opening correction quantity delta beta rh1,1 calculated by the control logic of the high-temperature section loop is obtained;
Third, a low-temperature section loop control logic for controlling a flue gas baffle of a primary low-temperature reheater is formulated
Calculating the difference value between the steam temperature set value T rh2,1,sp at the outlet of the secondary low-temperature reheater and the steam temperature set value T rh1,1,sp at the outlet of the primary low-temperature reheater under the current load; further calculating the difference between the steam temperature measured value T rh2,1 of the outlet of the secondary low-temperature reheater and the steam temperature measured value T rh1,1 of the outlet of the primary low-temperature reheater; the deviation of the set value and the deviation of the actual value are subjected to difference, and are input into a PID controller, so that the flue gas baffle opening correction quantity delta beta rh1,2 calculated by the low-temperature section loop control logic is obtained;
(IV) forming a control instruction of a flue gas baffle at the side of the low-temperature reheater
Obtaining a set value beta rh1,sp of the opening degree of a side baffle of the primary low-temperature reheater under the current load through F 4 (x), and adding beta rh1,sp、Δβrh1,1 and delta beta rh1,2 to obtain a control instruction beta rh1 of the side flue gas baffle of the primary low-temperature reheater;
The secondary low-temperature reheater side smoke baffle control logic is used for guaranteeing safe and normal operation of boiler tail smoke; in the peak regulation transient process of the coal-fired power generation unit, the opening of the flue gas baffle at the side of the secondary low-temperature reheater is based on a set value under the steady-state working condition of the coal-fired power generation unit; when the sum of the opening of the low-temperature superheater side flue gas baffle and the opening of the primary low-temperature reheater side flue gas baffle is smaller than 60%, the opening of the secondary low-temperature reheater side flue gas baffle is increased to ensure the normal circulation of flue gas; the method specifically comprises the following steps:
Firstly, setting a corresponding function of load and opening control logic of a flue gas baffle at the side of a secondary low-temperature reheater
Establishing a corresponding function F 5 (x) between the load and a set value of the opening degree of the flue gas baffle at the secondary low-temperature reheater side, setting a correction function F 6 (x) of the opening degree of the flue gas baffle at the secondary low-temperature reheater side by the sum of the opening degrees of the flue gas baffles at the primary low-temperature reheater side and the flue gas baffle at the low-temperature superheater, and setting an adjustment offset value of the flue gas baffle at the secondary low-temperature reheater side;
and (II) judging whether the sum of the opening of the flue gas baffle at the first low-temperature reheater side and the opening of the flue gas baffle at the low-temperature superheater side is more than 120 percent
Calculating the sum of the opening beta rh1 of a flue gas baffle at the primary low-temperature reheater side, the opening beta rh2 of a flue gas baffle at the secondary low-temperature reheater side and the opening of a flue gas baffle at the low-temperature superheater side, namely a flue gas baffle control instruction beta sh at the low-temperature superheater side, at the tail of the boiler in the current running state of the coal-fired generator set; when the sum of the opening degrees is more than or equal to 120%, the opening degree beta rh2 of the flue gas baffle at the side of the secondary low-temperature reheater is unchanged; otherwise, the opening degree of the side baffle of the secondary low-temperature reheater is adjusted to be (120% -beta rh1-βsh).
The load-dependent functions F i (x), i=1, 2, 3, 4, 5, 6 are piecewise linear interpolation functions, and represent values of the unit load and the control amount in one-to-one correspondence.
When the coal-fired unit of the tail three-flue boiler carries out peak shaving, the baffle opening control logic provided by the invention can timely feed back the temperature change trend of the low-temperature section of reheat steam to the control system, dynamically adjust the opening of the baffle in time and ensure the control effect of steam parameters in the transient process of unit peak shaving.
Aiming at the safe operation problems of large steam temperature fluctuation, lag baffle adjusting effect and the like in the peak regulation transient process of the secondary reheating coal-fired generator set of the tail three-flue boiler, the invention provides a reheating steam temperature control method which takes account of the transient characteristics of steam parameters of the high-temperature section heating surface and the low-temperature section heating surface of the secondary reheating boiler. According to the invention, by optimizing the control logic of the tail baffle of the secondary reheating boiler, the reheating steam control effect in the peak regulation transient process of the secondary reheating unit can be improved, and the operation flexibility and the high efficiency of the unit are further improved.
The invention has the following advantages:
(1) The invention can improve the reheat steam control effect of the tail three-flue boiler, and comprehensively improve the operation safety, flexibility and high efficiency of the secondary reheat coal-fired generator set;
(2) In the application process, the invention only needs to modify the control logic, does not need extra hardware investment and has no limit on investment recovery years.
Drawings
FIG. 1 is a logic diagram of low temperature superheater side flue gas baffle control.
FIG. 2 is a logic diagram of a primary low temperature reheater side flue gas damper control.
FIG. 3 is a logic diagram of secondary low temperature reheater side flue gas baffle control.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
Examples of the invention
In the embodiment, the reheat steam temperature control strategy of the tail three-flue double reheat ultra supercritical coal-fired boiler is described by taking the tail three-flue double reheat ultra supercritical coal-fired boiler as a control object. The boiler tail comprises three flues, namely a low-temperature superheater flue, a primary low-temperature reheater flue and a secondary low-temperature reheater flue, a flue gas baffle is arranged at the outlet of each flue, each boiler flue is divided into A, B sides, and the control amounts at two sides are kept consistent in numerical value. Therefore, the A, B sides are not distinguished in the implementation of the present invention.
A reheat steam temperature control method of a tail three-flue secondary reheat boiler comprises the following three control strategies: low temperature superheater side fume baffle control logic, primary low temperature reheater side fume baffle control logic, and secondary low temperature reheater side fume baffle control logic.
The low temperature superheater side flue gas baffle control logic is used to adjust the heat distribution between the low temperature superheater and the low temperature reheater. The specific content is as shown in figure 1: in the peak regulation transient process of the coal-fired power generation unit, the opening of the low-temperature superheater side flue gas baffle takes a set value under a steady-state working condition of the unit as a reference, a low temperature Duan Huilu is formed by taking a low-temperature reheater steam outlet temperature deviation value, namely the difference between the set value and an actual value as a reference 1, and a high-temperature section loop is constructed by taking a high-temperature reheater steam outlet temperature deviation value as a reference 2, so that a low-passing side flue gas baffle sectional control logic is formed.
Further, according to the actual condition of the selected unit, the following controller function setting is completed:
Extracting opening data of a low-temperature superheater baffle, average value data of steam temperatures of outlets of a primary low-temperature reheater and a secondary low-temperature reheater and average value data of steam temperatures of outlets of the primary high-temperature reheater and the secondary high-temperature reheater which cover a full load section from a unit DCS control system, wherein the load rate range is 30% -100%, and performing noise reduction treatment on the data, so as to lay a data foundation for establishing a function F 1 (x) between the load and steady-state set values of the flue gas baffle at the side of the low-temperature superheater, a function F 2 (x) between the load and average values of steam temperature set values of the outlets of the primary low-temperature reheater and the secondary low-temperature reheater and a function F 3 (x) between the load and average values of steam temperature set values of the outlets of the primary high-temperature reheater and the secondary high-temperature reheater.
Further, a logic for controlling the low temperature Duan Huilu by a low-temperature superheater side flue gas baffle is formulated, and the logic is specifically as follows: obtaining an average value T rh,avg1,sp of a set value of the steam temperature of the outlet of the primary low-temperature reheater under the current load through F 2 (x); further calculating the average value of the steam temperature measured values of the outlets of the primary and secondary low-temperature reheaters; the average value of the set value and the average value of the measured value are subjected to difference, and are input into a PID controller, so that the flue gas baffle opening correction quantity delta beta sh,1 calculated by the low-temperature section loop control logic is obtained; further, a low-temperature superheater side flue gas baffle control high-temperature section loop logic is formulated. The method comprises the following steps: when the unit operates under a certain load x, obtaining an average value T rh,avg2,sp of set values of the steam temperatures of the outlets of the primary and secondary high-temperature reheaters under the current load through F 3 (x); and further calculating the average value of the steam temperature measurement values of the outlets of the primary and secondary high-temperature reheaters. The average value of the set value and the average value of the measured value are subjected to difference, and are input into a PID controller, so that the flue gas baffle opening correction quantity delta beta sh,2 calculated by the control logic of the high-temperature section loop is obtained;
Further, a low temperature superheater side fume baffle control command is formed: and obtaining a set value beta sh,sp of the opening degree of the low-temperature superheater side flue gas baffle under the current load through F 1 (x), and adding beta sh,sp、Δβsh,1 and delta beta sh,2 to obtain a low-temperature superheater side flue gas baffle control instruction beta sh.
The control logic of the flue gas baffle at the side of the primary low-temperature reheater is used for adjusting heat distribution between the primary low-temperature reheater and the secondary low-temperature reheater, and the specific content is as shown in fig. 2: in the peak regulation transient process of the coal-fired power generator unit, the opening of the flue gas baffle at the side of the primary low-temperature reheater takes a set value under the steady-state working condition of the coal-fired power generator unit as a reference, a high-temperature section loop is formed by taking the relative value of the steam outlet temperature deviation of the secondary high-temperature reheater and the steam outlet temperature deviation of the primary high-temperature reheater as a flue gas baffle adjustment basis 1, a low-temperature Duan Huilu is formed by taking the relative value of the steam outlet temperature deviation of the secondary low-temperature reheater and the steam outlet temperature deviation of the primary low-temperature reheater as a flue gas baffle adjustment basis 2, and a primary low-temperature side flue gas baffle subsection control logic is constructed.
Further, according to the actual condition of the selected unit, the following controller function setting is completed:
and extracting opening data of the flue gas baffle at the side of the primary low-temperature reheater covering the full load section from a unit DCS control system, carrying out noise reduction treatment on the data, and establishing a corresponding function F 4 (x) between the load and a set value of the opening of the flue gas baffle at the side of the primary low-temperature reheater.
Further, a control logic of a high-temperature section loop controlled by a flue gas baffle at the side of the primary low-temperature reheater is formulated, and the difference value between the steam temperature set value T rh2,2,sp at the outlet of the secondary high-temperature reheater and the steam temperature set value T rh1,2,sp at the outlet of the primary high-temperature reheater under the current load is calculated according to the actual running condition of a unit, and is called as 'set value deviation' for short; further calculating the difference between the steam temperature measured value T rh2,2 of the outlet of the secondary high-temperature reheater and the steam temperature measured value T rh1,2 of the outlet of the primary high-temperature reheater, which is simply called as 'actual value deviation'; the deviation of the set value and the deviation of the actual value are subjected to difference, and are input into a first PID controller, so that a baffle opening correction quantity delta beta rh1,1 calculated by a high-temperature section loop control logic is obtained;
Further, a low-temperature section loop control logic for controlling a flue gas baffle of the primary low-temperature reheater is formulated, and the difference value between the steam temperature set value T rh2,1,sp of the outlet of the secondary low-temperature reheater and the steam temperature set value T rh1,1,sp of the outlet of the primary low-temperature reheater under the current load is calculated according to the actual running condition of the unit; further calculating the difference between the steam temperature measured value T rh2,1 of the outlet of the secondary low-temperature reheater and the steam temperature measured value T rh1,1 of the outlet of the primary low-temperature reheater; the deviation of the set value and the deviation of the actual value are subjected to difference and input into a second PID controller, and the flue gas baffle opening correction quantity delta beta rh1,2 calculated by the low-temperature section loop control logic is obtained;
Further, a low-temperature reheater side flue gas baffle control command is formed. Obtaining a set value beta rh1,sp of the opening degree of a side baffle of the primary low-temperature reheater under the current load through F 4 (x), and adding beta rh1,sp、Δβrh1,1 and delta beta rh1,2 to obtain a control instruction beta rh1 of the side flue gas baffle of the primary low-temperature reheater;
the control logic of the secondary low-temperature reheater side flue gas baffle is used for guaranteeing safe and normal operation of the tail flue gas of the boiler, and the specific content is shown in the accompanying figure 3: in the peak regulation transient process of the coal-fired power generation unit, the opening of the flue gas baffle at the side of the secondary low-temperature reheater is based on a set value under the steady-state working condition of the coal-fired power generation unit; when the sum of the opening of the low-temperature superheater side flue gas baffle and the opening of the primary low-temperature reheater side flue gas baffle is smaller than 60%, the opening of the secondary low-temperature reheater side flue gas baffle is increased to ensure the normal circulation of flue gas.
Further, according to the actual condition of the selected unit, the following controller function setting is completed:
And extracting opening data of the secondary low-temperature reheater side flue gas baffle which covers the full load section from a unit DCS control system, carrying out noise reduction treatment on the data, and establishing a corresponding function F 5 (x) between the load and a set value of the opening of the secondary low-temperature reheater side flue gas baffle.
Further, a correction function F 6 (x) of the opening degree of the secondary low-temperature reheater side baffle is established according to F 1(x)、F4 (x) and F 5 (x), and a secondary low-temperature reheater side baffle adjustment bias value is set.
Further, calculating the sum of the opening beta rh1 of the flue gas baffle at the primary low-temperature reheater side, the opening beta rh2 of the flue gas baffle at the secondary low-temperature reheater side and the opening of the flue gas baffle at the low-temperature superheater side, namely a control instruction beta sh of the flue gas baffle at the low-temperature superheater side, at the tail of the boiler in the current running state of the coal-fired generator set; when the sum of the opening degrees is more than or equal to 120%, the opening degree beta rh2 of the flue gas baffle at the side of the secondary low-temperature reheater is unchanged; otherwise, the opening degree of the side baffle of the secondary low-temperature reheater is adjusted to be (120% -beta rh1-βsh).
Further, when the hearth performs heating surface soot blowing operation, the opening of the low-temperature superheater side flue gas baffle, the opening of the primary low-temperature reheater flue gas baffle and the opening of the secondary low-temperature reheater flue gas baffle are set to be 100%; when the unit is in normal operation, the opening of the baffle is automatically operated.
Claims (3)
1. A reheat steam temperature control method of a tail three-flue secondary reheat boiler is characterized by comprising the following steps of: the reheat steam temperature control of the tail three-flue secondary reheat boiler adopts tail three-flue boiler baffle control, and the control logic comprises low-temperature superheater side flue gas baffle control logic, primary low-temperature reheater side flue gas baffle control logic and secondary low-temperature reheater side flue gas baffle control logic;
The low-temperature superheater side flue gas baffle control logic is used for adjusting heat distribution between the low-temperature superheater and the low-temperature reheater; in the peak regulation transient process of the coal-fired power generation unit, the opening of the low-temperature superheater side flue gas baffle takes a set value under a steady-state working condition of the unit as a reference, a low temperature Duan Huilu is formed by taking a deviation value of the steam outlet of the low-temperature reheater, namely, the difference between the set value and an actual value as a reference 1, and a high-temperature section loop is constructed by taking a deviation value of the steam outlet of the high-temperature reheater as a reference 2, so that a low-passing side flue gas baffle subsection control logic is formed; the method specifically comprises the following steps:
a function of setting load and controlling opening degree of a low-temperature superheater side flue gas baffle
Establishing a steady-state set value function F 1 (x) of the load and the low-temperature superheater side flue gas baffle, a function F 2 (x) between the load and the average value of the steam temperature set values of the outlets of the primary and secondary low-temperature reheaters, and a function F 3 (x) between the load and the average value of the steam temperature set values of the outlets of the primary and secondary high-temperature reheaters;
(II) establishing logic for controlling low temperature Duan Huilu by using low-temperature superheater side flue gas baffle
When the unit operates under a certain load x, an average value T rh,avg1,sp of steam temperature set values of the outlets of the primary and secondary low-temperature reheaters under the current load is obtained through F 2 (x); further calculating the average value of the steam temperature measured values of the outlets of the primary and secondary low-temperature reheaters; the average value of the set values and the average value of the measured values are subjected to difference and input into a PID controller, and the flue gas baffle opening correction quantity delta beta sh,1 calculated by the low-temperature section loop control logic is obtained;
Third, a low-temperature superheater side smoke baffle control high-temperature section loop logic is formulated
When the unit operates under a certain load x, obtaining an average value T rh,avg2,sp of set values of the steam temperatures of the outlets of the primary and secondary high-temperature reheaters under the current load through F 3 (x); further calculating the average value of the steam temperature measured values of the outlets of the primary and secondary high-temperature reheaters; the average value of the set values and the average value of the measured values are subjected to difference and input into a PID controller, and the flue gas baffle opening correction quantity delta beta sh,2 calculated by the high-temperature section loop control logic is obtained;
(IV) forming a low-temperature superheater side smoke baffle control instruction
Obtaining a set value beta sh,sp of the opening of a low-temperature superheater side flue gas baffle under the current load through F 1 (x), and adding beta sh,sp、Δβsh,1 and delta beta sh,2 to obtain a low-temperature superheater side flue gas baffle control instruction beta sh;
The control logic of the flue gas baffle at the side of the primary low-temperature reheater is used for adjusting heat distribution between the primary low-temperature reheater and the secondary low-temperature reheater; in the peak regulation transient process of the coal-fired power generator unit, the opening of a flue gas baffle at the side of the primary low-temperature reheater takes a set value under the steady-state working condition of the coal-fired power generator unit as a reference, a high-temperature section loop is formed by taking the relative value of the steam outlet temperature deviation of the secondary high-temperature reheater and the steam outlet temperature deviation of the primary high-temperature reheater as a flue gas baffle adjustment basis 1, a low-temperature Duan Huilu is formed by taking the relative value of the steam outlet temperature deviation of the secondary low-temperature reheater and the steam outlet temperature deviation of the primary low-temperature reheater as a flue gas baffle adjustment basis 2, and a primary low-temperature side flue gas baffle subsection control logic is constructed; the method specifically comprises the following steps:
Firstly, establishing a corresponding function F 4 (x) between the load and a set value of the opening of the flue gas baffle at the side of the primary low-temperature reheater by setting a corresponding function related to the opening control logic of the flue gas baffle at the side of the primary low-temperature reheater;
second, a control logic for controlling a high-temperature section loop by a flue gas baffle at the side of the primary low-temperature reheater is formulated
Calculating the difference between the steam temperature set value T rh2,2,sp of the outlet of the secondary high-temperature reheater and the steam temperature set value T rh1,2,sp of the outlet of the primary high-temperature reheater under the current load, wherein the difference is simply called as 'set value deviation'; further calculating the difference between the steam temperature measured value T rh2,2 of the outlet of the secondary high-temperature reheater and the steam temperature measured value T rh1,2 of the outlet of the primary high-temperature reheater, which is simply called as 'actual value deviation'; the deviation of the set value and the deviation of the actual value are subjected to difference and input into a PID controller, and the baffle opening correction quantity delta beta rh1,1 calculated by the control logic of the high-temperature section loop is obtained;
Third, a low-temperature section loop control logic for controlling a flue gas baffle of a primary low-temperature reheater is formulated
Calculating the difference value between the steam temperature set value T rh2,1,sp at the outlet of the secondary low-temperature reheater and the steam temperature set value T rh1,1,sp at the outlet of the primary low-temperature reheater under the current load; further calculating the difference between the steam temperature measured value T rh2,1 of the outlet of the secondary low-temperature reheater and the steam temperature measured value T rh1,1 of the outlet of the primary low-temperature reheater; the deviation of the set value and the deviation of the actual value are subjected to difference, and are input into a PID controller, so that the flue gas baffle opening correction quantity delta beta rh1,2 calculated by the low-temperature section loop control logic is obtained;
(IV) forming a control instruction of a flue gas baffle at the side of the low-temperature reheater
Obtaining a set value beta rh1,sp of the opening of a side baffle of the primary low-temperature reheater under the current load through F 4 (x), and adding beta rh1,sp、Δβrh1,1 and delta beta rh1,2 to obtain an opening beta rh1 of a side flue gas baffle of the primary low-temperature reheater;
The secondary low-temperature reheater side smoke baffle control logic is used for guaranteeing safe and normal operation of boiler tail smoke; in the peak regulation transient process of the coal-fired power generation unit, the opening of the flue gas baffle at the side of the secondary low-temperature reheater is based on a set value under the steady-state working condition of the coal-fired power generation unit; when the sum of the opening of the low-temperature superheater side flue gas baffle and the opening of the primary low-temperature reheater side flue gas baffle is smaller than 60%, the opening of the secondary low-temperature reheater side flue gas baffle is increased to ensure the normal circulation of flue gas; the method specifically comprises the following steps:
Firstly, setting a corresponding function of load and opening control logic of a flue gas baffle at the side of a secondary low-temperature reheater
Establishing a corresponding function F 5 (x) between the load and a set value of the opening degree of the flue gas baffle at the secondary low-temperature reheater side, setting a correction function F 6 (x) of the opening degree of the flue gas baffle at the secondary low-temperature reheater side by the sum of the opening degrees of the flue gas baffles at the primary low-temperature reheater side and the flue gas baffle at the low-temperature superheater, and setting an adjustment offset value of the flue gas baffle at the secondary low-temperature reheater side;
Judging whether the sum of the opening of the flue gas baffle at the first low-temperature reheater side and the opening of the flue gas baffle at the low-temperature superheater side is more than 120%; calculating the sum of the opening beta rh1 of a flue gas baffle at the primary low-temperature reheater side, the opening beta rh2 of a flue gas baffle at the secondary low-temperature reheater side and the opening of a flue gas baffle at the low-temperature superheater side, namely a flue gas baffle control instruction beta sh at the low-temperature superheater side, at the tail of the boiler in the current running state of the coal-fired generator set; when the sum of the opening degrees is more than or equal to 120%, the opening degree beta rh2 of the flue gas baffle at the side of the secondary low-temperature reheater is unchanged; otherwise, the opening degree of the side baffle of the secondary low-temperature reheater is adjusted to be (120% -beta rh1-βsh).
2. The method for controlling reheat steam temperature of a tail three flue secondary reheat boiler as set forth in claim 1, wherein: f i (x), i=1, 2, 3, 4, 5, 6, is a piecewise linear interpolation function, representing a value of one-to-one correspondence of unit load and control amount.
3. The method for controlling reheat steam temperature of a tail three flue secondary reheat boiler as set forth in claim 1, wherein: when the hearth performs soot blowing operation on a heating surface, the opening of a low-temperature superheater side flue gas baffle, the opening of a primary low-temperature reheater flue gas baffle and the opening of a secondary low-temperature reheater flue gas baffle are set to be 100%, and when the unit is in normal operation, the opening of the baffle is automatically operated.
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| CN202210704485.7A CN115076679B (en) | 2022-06-21 | Reheat steam temperature control method for tail three-flue secondary reheat boiler |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103776020A (en) * | 2014-02-26 | 2014-05-07 | 章礼道 | Double reheat power station boiler with three rear flues and double rear baffles and capable of recycling jet flow flue gas |
| CN109084293A (en) * | 2018-08-06 | 2018-12-25 | 东方电气集团东方锅炉股份有限公司 | A kind of three damper adjustment control method of double reheat boiler |
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103776020A (en) * | 2014-02-26 | 2014-05-07 | 章礼道 | Double reheat power station boiler with three rear flues and double rear baffles and capable of recycling jet flow flue gas |
| CN109084293A (en) * | 2018-08-06 | 2018-12-25 | 东方电气集团东方锅炉股份有限公司 | A kind of three damper adjustment control method of double reheat boiler |
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