CN113091046A - Double reheat boiler and outlet steam temperature control method and device thereof - Google Patents
Double reheat boiler and outlet steam temperature control method and device thereof Download PDFInfo
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Abstract
The invention provides a double reheat boiler and an outlet steam temperature control method and device thereof, wherein the double reheat boiler comprises a flue gas recirculation system, and the method comprises the following steps: acquiring a reheater outlet temperature set value, a primary reheater outlet temperature and a secondary reheater outlet temperature; acquiring a flue gas recirculation quantity and an excess air coefficient; acquiring a combustor swing angle control signal according to a reheater outlet temperature set value, a primary reheater outlet temperature, a secondary reheater outlet temperature, a flue gas recirculation quantity and an excess air coefficient; and adjusting the swing angle of the burner according to the swing angle control signal of the burner so as to control the outlet steam temperature of the secondary reheating boiler. The control method can realize the control of the double reheat boiler, has higher automation control degree in the whole process, and improves the control efficiency of the double reheat boiler and the operation economy of the unit.
Description
Technical Field
The invention relates to the technical field of boiler control, in particular to an outlet steam temperature control method of a double reheat boiler, an outlet steam temperature control device of the double reheat boiler and the double reheat boiler.
Background
The reheat steam temperature is one of the important parameters characterizing the operating conditions of the boiler. The steam temperature is too high, so that the creep speed of the metal of the heating surface and the steam pipeline of the boiler is accelerated, and the service life of the boiler is influenced; the low steam temperature will cause the heat efficiency of the unit to be reduced, the steam consumption rate to be increased, and the steam humidity at the last stage blade of the steam turbine to be larger, which causes the erosion of the last stage blade of the steam turbine to be aggravated. The reheating steam temperature object has the characteristics of large delay and large inertia, and factors influencing the change of the reheating steam temperature are many, such as unit load change, coal quality change, temperature reduction water quantity, heating surface coking, air-coal ratio, combustion condition, excess air coefficient and the like, and the steam temperature object reflects the characteristics of nonlinearity, time variation and the like under various disturbance actions, so that the control difficulty is increased.
With the continuous development of the fire power generation technology in recent years, the double reheating ultra-supercritical power generation technology is mature gradually, and a plurality of double reheating units are built or are about to be built in China. The boiler of the double reheating unit is additionally provided with a first-stage double reheating cycle, the heating surface arrangement of the boiler is more complex, the complexity and difficulty of boiler steam temperature control are correspondingly increased, and the control of the two-stage reheating steam temperature is the most important. Therefore, reasonable reheat steam temperature control is powerful guarantee of safety, economy and reliability of the double reheat unit.
In the prior art, various reheating air temperature and steam temperature adjusting means exist, but the adjusting means increase the flexibility of control, but also increase the complexity of control operation of operators. Particularly, under different working conditions, how to select an adjusting means to automatically cooperate with the adjustment of the reheated steam temperature becomes a problem to be solved urgently.
Disclosure of Invention
The invention aims to solve the technical problems and provides the outlet steam temperature control method of the double reheat boiler, which can realize the control of the double reheat boiler, has higher automation control degree in the whole process and improves the control efficiency of the double reheat boiler and the unit operation economy.
The technical scheme adopted by the invention is as follows:
a method of outlet steam temperature control for a double reheat boiler, said double reheat boiler including a flue gas recirculation system, said method comprising the steps of: acquiring a reheater outlet temperature set value, a primary reheater outlet temperature and a secondary reheater outlet temperature; acquiring a flue gas recirculation quantity and an excess air coefficient; acquiring a combustor pivot angle control signal according to the reheater outlet temperature set value, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation amount and the excess air coefficient; and adjusting the swing angle of the burner according to the control signal of the swing angle of the burner so as to control the outlet steam temperature of the secondary reheating boiler according to the adjusted swing angle of the burner.
According to one embodiment of the present invention, deriving a combustor tilt angle control signal based on the reheater outlet temperature setpoint, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation amount, and the excess air factor comprises: obtaining an average of the primary reheater outlet temperature and the secondary reheater outlet temperature; calculating a difference value between the reheater outlet temperature set value and the average value, and when the difference value is not zero, performing proportional integral control on the reheater outlet temperature set value and the average value to generate a first control signal; acquiring the total fuel quantity and the unit load of the current secondary reheating boiler; summing the first control signal, the current total fuel quantity of the double reheat boiler and the unit load to obtain a second control signal; and acquiring a combustor swing angle control signal according to the second control signal, the flue gas recirculation quantity and the excess air coefficient.
According to an embodiment of the invention, deriving a burner tilt angle control signal based on the second control signal, the amount of flue gas recirculation, and the excess air ratio comprises: summing the product of the second control signal and the flue gas recirculation quantity with a first preset value to obtain a third control signal; and carrying out summation operation on the third control signal, the product of the excess air coefficient and a second preset value to obtain the swing angle control signal of the combustor.
According to an embodiment of the present invention, the economic sum P of the reheat steam temperature is obtained by the following formula*：
Wherein f isEsfThe electricity price is converted for the increment of the power consumption of the secondary fan,
for denitration ammonia injection increment conversion of material price, fEcfReduction of electricity price for power consumption saving of recirculation fan, fCThe coal price is converted for saving fuel, and the prices are calculated according to the unit load and the electricity generation time of 1 kilowatt hour.
According to one embodiment of the invention, obtaining the flue gas recirculation amount and the excess air ratio according to the minimum value comprises: acquiring corresponding power consumption of the recirculation fan and the secondary fan according to the minimum value; acquiring the flue gas recirculation amount according to the power consumption of the recirculation fan; and acquiring the excess air coefficient according to the power consumption of the secondary air fan.
According to an embodiment of the present invention, the method for controlling outlet steam temperature of a double reheat boiler further includes:
and when a main fuel trip signal of the double reheat boiler is received, setting the burner swing angle control signal to be 0.
According to an embodiment of the present invention, the method for controlling outlet steam temperature of a double reheat boiler further includes:
when an auxiliary machine fault load reducing signal of the double reheat boiler is received, the current swing angle of the burner is kept unchanged.
The invention also provides an outlet steam temperature control device of the double reheat boiler, the double reheat boiler comprises a flue gas recirculation system, and the device comprises: the first acquisition module is used for acquiring a reheater outlet temperature set value, a primary reheater outlet temperature and a secondary reheater outlet temperature; the second acquisition module is used for acquiring the flue gas recirculation quantity and the excess air coefficient; a third obtaining module, configured to obtain a combustor tilt angle control signal according to the reheater outlet temperature set value, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation amount, and the excess air coefficient; and the control module is used for adjusting the swing angle of the burner according to the burner swing angle control signal so as to control the outlet steam temperature of the secondary reheating boiler according to the adjusted swing angle of the burner.
The invention also provides a double reheat boiler, comprising: a flue gas recirculation system and the outlet steam temperature control device of the double reheat boiler.
The invention has the beneficial effects that:
according to the invention, the outlet temperature of the primary reheater and the outlet temperature of the secondary reheater are introduced as control targets, and the swing angle of the burner is adjusted by combining the flue gas recirculation quantity and the excess air coefficient, so that the outlet steam temperature of the secondary reheater is adjusted, the automation control degree of the whole process is higher, and the control efficiency of the secondary reheater and the unit operation economy are improved.
Drawings
FIG. 1 is a flow chart of a method for controlling outlet steam temperature of a double reheat boiler in accordance with an embodiment of the present invention;
FIG. 2 is a schematic view of the overall heat receiving surface layout of a double reheat boiler according to an embodiment of the present invention;
FIG. 3 is a logic diagram of a method for controlling outlet steam temperature of a double reheat boiler in accordance with an embodiment of the present invention;
FIG. 4 is a block diagram of an outlet steam temperature control device of a double reheat boiler according to an embodiment of the present invention.
Detailed Description
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 only a part of the embodiments of the present invention, and not all of the embodiments. 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.
Fig. 1 is a flowchart of an outlet steam temperature control method of a double reheat boiler according to an embodiment of the present invention.
At present, the heating surface arrangement of the latest ultra-supercritical parameter secondary reheating single-hearth tower type coal-fired boiler designed and produced by a certain boiler plant is different from that of the conventional boiler, and the quality of the control of the reheating steam temperature of the boiler of the ultra-supercritical secondary reheating coal-fired power generating unit generally directly influences the heat efficiency of the unit and the safe and stable operation of the unit. Aiming at the novel boiler, a corresponding automatic control scheme is needed to ensure that the reheated steam temperature meets the design requirements of each load point. Therefore, the invention provides an outlet steam temperature control method of a double reheat boiler, so as to meet the requirement of automatic control.
In one embodiment of the present invention, the control method of the present invention is used in a boiler controller of a double reheat boiler. The double reheat boiler comprises a flue gas recirculation system so as to ensure that the deviation of the temperature of the reheated steam is as small as possible at each load point, particularly under low load, and the double reheat boiler has better low-load stable combustion performance and better start, stop and peak regulation performance.
For convenience of understanding, a 660MW ultra supercritical parameter secondary reheating coal-fired boiler (hereinafter referred to as a secondary reheating boiler) designed and produced in a certain boiler plant is taken as an example for explanation, specifically, the secondary reheating boiler is a variable-pressure operation spiral tube coil direct-current boiler, single-hearth tower type arrangement, four-corner tangential combustion, balanced ventilation, upward and downward swinging temperature regulation of a burner are adopted, a separated flue design is adopted, a flue gas baffle is arranged on the separated flue, a combined high-temperature heating surface arrangement is adopted, and fig. 2 shows a schematic diagram of the overall heating surface arrangement of the secondary reheating boiler.
As shown in fig. 2, the main heating surface includes: the first stage is a furnace hanging pipe, a double-flue partition wall and a low-temperature superheater, steam enters the low-temperature superheater through the furnace hanging pipe and the double-flue partition wall through two pipelines at the outlet of a separator respectively, wherein the furnace hanging pipe and the double-flue partition wall are not shown in the figure 2, and the low-temperature superheater is arranged at the outlet of a hearth; the second level is a high-temperature superheater and is arranged between a high-temperature reheater cold section and a high-temperature reheater hot section, wherein the high-temperature reheater cold section comprises a primary high-temperature reheater cold section and a secondary high-temperature reheater cold section, and the high-temperature reheater hot section comprises a primary high-temperature reheater hot section and a secondary high-temperature reheater hot section. The steam temperature of the superheated steam system is adjusted by roughly adjusting the traditional fuel/water supply ratio, and the superheated steam temperature deviation is accurately adjusted by spraying water and reducing the temperature at two stages of four points (one stage at each inlet of the low-temperature superheater and the high-temperature superheater, and one point at each point on the left side and the right side).
The heating surfaces of the primary reheater and the secondary reheater are divided into two stages, namely a primary/secondary low-temperature reheater and a primary/secondary high-temperature reheater. The low-temperature reheater is arranged between the upper high-temperature reheater and the economizer, the high-temperature reheater cold section is arranged between the lower low-temperature superheater and the high-temperature superheater, and the high-temperature reheater hot section is arranged between the middle high-temperature superheater and the low-temperature reheater. An accident water spray desuperheater is arranged on an inlet pipeline of the primary/secondary low-temperature reheater, and a reheat steam trace water spray desuperheater is arranged on an inlet pipeline of the primary/secondary high-temperature reheater.
According to the design requirement of boiler performance, the temperatures of steam inlets and outlets of a primary reheater and a secondary reheater are relatively close, therefore, when the arrangement design is carried out, the primary reheater and the secondary reheater are arranged in parallel, the primary reheater and the secondary reheater are in the same smoke temperature interval, the temperatures of the inlet smoke and the outlet smoke are basically the same, the proportion of the areas of the heating surfaces of the primary reheater and the secondary reheater is designed to be basically the same as the proportion of the heat absorption capacity of the primary reheater and the secondary reheater, and the design can ensure that the heat absorption capacity of the primary reheater and the secondary reheater has basically the same trend along with the change of load.
In addition to the temperature adjusting means, the secondary reheating boiler in the embodiment of the invention is also provided with a flue gas recirculation system, cold flue gas at the tail part of the secondary reheating boiler can be sent to the lower part of the hearth through a fan of the flue gas recirculation system, the mixing of the cold flue gas can reduce the combustion temperature in the hearth and improve the flow velocity of the flue gas, the larger the flow of the cold flue gas is, the lower the temperature of the hearth is, but the temperature change of the flue gas at the outlet of the hearth is not large, so that the radiation heat exchange quantity of the hearth is reduced, the heat exchange quantity of a convection heating surface is increased, namely, the heat absorption quantity ratio of the radiation heating surface and the convection heating surface of the boiler is changed, the total heat. Specifically, cold flue gas of the flue gas recirculation system is taken from the back of the SCR denitration reaction device and the front of the air preheater, the left and right side flues are respectively pumped one way, the flue gas is combined in the center and then goes downwards, the left and right sides of the boiler are respectively provided with a centrifugal recirculation fan, and the fans spray the flue gas into a hearth from the left and right side walls. Generally, the temperature of the primary reheating steam and the secondary reheating steam is controlled to be 623 ℃, the deviation is not more than +/-5 ℃, and the steam temperature deviation of outlets at two sides is less than 10 ℃. Meanwhile, the temperature of each section of working medium does not exceed a specified value.
As shown in fig. 1, the method for controlling outlet steam temperature of a double reheat boiler according to an embodiment of the present invention may include the following steps:
s1, acquiring a reheater outlet temperature set value, a primary reheater outlet temperature and a secondary reheater outlet temperature.
S2, acquiring the smoke recirculation quantity and the excess air coefficient.
According to one embodiment of the invention, obtaining a flue gas recirculation amount and an excess air factor comprises: acquiring the minimum value of the economic sum of the reheated steam temperature; and acquiring the smoke recirculation quantity and the excess air coefficient according to the minimum value.
In one embodiment of the present invention, the economic sum P of the reheat steam temperature is obtained by the following formula*：
Wherein f isEsfConverting the power consumption increment of the secondary fan into electricityThe price of the mixture is higher than the standard value,
for denitration ammonia injection increment conversion of material price, fEcfReduction of electricity price for power consumption saving of recirculation fan, fCThe coal price is converted for saving fuel, and the prices are calculated according to the unit load and the electricity generation time of 1 kilowatt hour.
Further, according to an embodiment of the present invention, the obtaining of the flue gas recirculation amount and the excess air ratio according to the minimum value includes: acquiring corresponding power consumption of the recirculation fan and the secondary fan according to the minimum value; acquiring the flue gas recirculation amount according to the power consumption of the recirculation fan; and acquiring the excess air coefficient according to the power consumption of the secondary fan.
Specifically, the temperature of the primary reheat steam and the temperature of the secondary reheat steam can be simultaneously increased due to the fact that the flue gas recirculation amount is increased and the excess air coefficient is increased, but other different influences are caused on the operation of the unit. For example, increasing the amount of flue gas recirculation will increase the power consumption of the recirculation fan, and too much flue gas recirculation will increase the flue gas temperature at the economizer, possibly even resulting in vaporization of economizer feedwater; for another example, increasing the excess air factor will increase the power consumption of the secondary air fan, which may cause an increase in the amount of NOx generated at the outlet of the furnace, thereby increasing the amount of NOx sprayed during denitration, i.e. increasing the operating cost of the denitration system, but increasing the burnout rate of the fuel and reducing the unburnt loss of the fuel. If the means of flue gas recirculation and excess air coefficient increase are not adopted, the temperature of the reheated steam is difficult to reach the design value under partial low-load working conditions of the boiler. Therefore, how to obtain the optimal set values of the flue gas recirculation amount and the excess air factor under different working conditions and loads is a complex optimization problem. The optimization goal of this problem is to maximize the actual operating economics of the boiler. The best operation economy is that on the premise of ensuring that the temperature of the primary reheat steam and the secondary reheat steam of the unit reaches a set value and the economizer keeps the supercooling degree and does not vaporize, when flue gas recirculation and excess air coefficient increasing means are adopted, the economic sum of the power consumption saving amount of a recirculation fan, the power consumption increasing amount of a secondary fan, the denitration ammonia injection increasing amount and the fuel saving amount is minimum (the saving amount and the increasing amount are based on the working condition of only adopting the flue gas recirculation), so that the flue gas recirculation amount and the excess air coefficient can be determined according to the economic sum minimum.
Specifically, as can be seen from the above formula, the specific calculation process may include obtaining electric power consumption of the secondary air fan, an increase amount of the denitration ammonia injection, electric power consumption of the recirculation air fan, and a fuel saving amount of the secondary reheat boiler at the current time, to calculate the above economic total, obtaining electric power consumption of the recirculation air fan and electric power consumption of the secondary air fan when the economic total takes a minimum value, and obtaining the flue gas recirculation amount and the excess air coefficient at this time according to the corresponding formulas, respectively.
It should be noted that, under different loads, the theoretical values of the flue gas recirculation amount or the excess air coefficient required for ensuring the reheated steam temperature, the power consumption of the recirculation fan and the power consumption of the secondary fan under the conditions of different flue gas recirculation amounts and different excess air coefficients, and the theoretical curves of the furnace outlet flue gas NOx value and the fuel burnout rate under the conditions of different excess air coefficients can be provided by the design department of the boiler plant, and are corrected through performance tests and operation data in the process of engineering practical application. The power consumption of the fan can be converted into electricity price, the denitration ammonia injection amount can be converted through the NOx value, the fuel burnout rate can be converted into coal price, and therefore the operation optimization model of the flue gas recirculation amount and the excess air coefficient can be obtained. Further, after the unit accumulates enough operation data under each load and each working condition, a neural network relation model of power consumption saving amount of the recirculation fan, power consumption increasing amount of the secondary fan, denitration ammonia injection increasing amount and fuel saving amount can be established. Therefore, in the running process of the unit, the model is solved in real time under different working conditions, and the optimized set values of the flue gas recirculation quantity and the excess air coefficient can be obtained.
And S3, acquiring a combustor pivot angle control signal according to the reheater outlet temperature set value, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation quantity and the excess air coefficient.
According to one embodiment of the present invention, obtaining a combustor tilt angle control signal based on a reheater outlet temperature setpoint, a primary reheater outlet temperature, a secondary reheater outlet temperature, a flue gas recirculation amount, and an excess air factor comprises: acquiring an average value of primary reheater outlet temperature and secondary reheater outlet temperature; calculating a difference value between the reheater outlet temperature set value and the average value, and when the difference value is not zero, performing proportional integral control on the reheater outlet temperature set value and the average value to generate a first control signal; acquiring the total fuel quantity and unit load of the current secondary reheating boiler; summing the first control signal, the total fuel quantity of the current secondary reheating boiler and the unit load to obtain a second control signal; and acquiring a combustor swing angle control signal according to the second control signal, the flue gas recirculation quantity and the excess air coefficient.
Further in accordance with an embodiment of the present invention, deriving the burner tilt angle control signal based on the second control signal, the amount of flue gas recirculation, and the excess air ratio comprises: summing the product of the second control signal, the smoke recirculation quantity and the first preset value to obtain a third control signal; and carrying out summation operation on the third control signal, the product of the excess air coefficient and the second preset value to obtain a swing angle control signal of the combustor. The first preset value and the second preset value can be calibrated according to actual conditions, for example, the first preset value can be-0.5, and the second preset value can be-0.005.
Specifically, as shown in fig. 3, the primary reheater outlet temperature and the secondary reheater outlet temperature are obtained in real time, an average value of the primary reheater outlet temperature and the secondary reheater outlet temperature is obtained, whether the average value is the same as the reheater outlet temperature set value or not is judged, and if the average value is not the same as the reheater outlet temperature set value, proportional integral control is performed on the reheater outlet temperature set value and the average value to generate a first control signal. Because the total fuel quantity and the unit load of the secondary reheating boiler have a fixed setting relation with the swing angle of the combustor, when the average value is different from the set value of the outlet temperature of the reheater, the swing angle of the combustor needs to be adjusted, and the first control signal, the total fuel quantity and the unit load of the current secondary reheating boiler are summed to generate a second control signal. Taking the flue gas recirculation amount and the excess air coefficient as feedforward signals to obtain the swing angle control signal of the burner, for example, summing the products of the second control signal, the flue gas recirculation amount and the first preset value to obtain a third control signal, and summing the products of the third control signal, the excess air coefficient and the second preset value to obtain the swing angle control signal of the burner.
And S4, adjusting the swing angle of the burner according to the swing angle control signal of the burner, and controlling the outlet steam temperature of the secondary reheating boiler according to the adjusted swing angle of the burner.
That is, the total fuel quantity of the current double reheat boiler and the burner swing angle corresponding to the unit load are adjusted according to the burner swing angle control signal, for example, when the set value of the outlet temperature of the reheater is larger than the average value, the burner swing angle is increased by a preset value; when the temperature set value of the outlet of the reheater is smaller than the average value, the swing angle of the burner is adjusted to be smaller than a preset value; and when the reheater outlet temperature set value is equal to the average value, keeping the current swing angle of the combustor unchanged.
According to an embodiment of the present invention, the method for controlling outlet steam temperature of a double reheat boiler may further include: when a main fuel trip signal of the double reheat boiler is received, a burner tilt angle control signal is set to 0.
According to an embodiment of the present invention, the method for controlling outlet steam temperature of a double reheat boiler may further include: when an auxiliary machine fault load reducing signal of the double reheat boiler is received, the current swing angle of the burner is kept unchanged.
Specifically, in the schematic diagram shown in fig. 3, the boiler controller performs an operation using a proportional integral controller PI. And sending the superposed value as a burner swing angle control signal to the burner swing controllers of each layer. If the boiler MFT (MAIN FUEL TRIP), the burner tilt angle control signal is set to 0, that is, when the signal of the MAIN FUEL TRIP of the double reheat boiler is received, the burner tilt angle is set to 0, and the branch of the MFT in fig. 3 is executed.
When an auxiliary machine fault load Reduction (RUNBACK) load return request of the double reheat boiler is received, keeping the current burner swing angle unchanged; otherwise, the swing angle of the burner is adjusted through the output burner swing angle control signal, and the secondary reheating boiler is controlled. In the branch shown in fig. 3, where RUNBACK is located, if boiler RUNBACK is detected, the burner tilt control signal is set to hold the current command.
It should be noted that, when the primary reheater outlet temperature and the secondary reheater outlet temperature cannot be received, the manual control mode is switched to, and the above-mentioned entire process is not executed. Likewise, burner oscillation lockout increase/decrease, tracking of PID controllers, and manual automatic switching may be performed as in conventional, commonly used schemes, and are not described again.
In conclusion, the outlet steam temperature control method of the double reheat boiler can realize the automatic selection of the reheat steam temperature adjusting means and the automatic cooperative participation in the adjustment of the reheat steam temperature under different working conditions, relieves the coupling problem and the control time lag problem of the burner swing, the flue gas recirculation quantity adjustment and the excess air coefficient adjustment control loop, adopts the operation of the excess air coefficient adjustment mode and the flue gas recirculation temperature adjustment mode under different working conditions, and simultaneously establishes the power consumption saving amount of the recirculation fan, the power consumption increasing amount of the secondary fan, the denitration ammonia injection increasing amount and the fuel saving amount model; in the unit operation process, under different working conditions, the model is solved in real time, the optimized flue gas recirculation quantity and the set value of the excess air coefficient are obtained, and the unit operation economy is effectively improved.
Corresponding to the outlet steam temperature control method of the double reheat boiler in the embodiment, the invention further provides an outlet steam temperature control device of the double reheat boiler.
In one embodiment of the invention, the double reheat boiler includes a flue gas recirculation system.
As shown in fig. 4, the outlet steam temperature control device of the double reheat boiler according to the embodiment of the present invention may include: a first acquisition module 10, a second acquisition module 20, a third acquisition module 30 and a control module 40.
The first obtaining module 10 is configured to obtain a reheater outlet temperature set value, a primary reheater outlet temperature, and a secondary reheater outlet temperature. The second obtaining module 20 obtains the amount of flue gas recirculation and the excess air ratio. The third acquisition module 30 is configured to acquire a burner tilt angle control signal according to a reheater outlet temperature set value, a primary reheater outlet temperature, a secondary reheater outlet temperature, a flue gas recirculation amount, and an excess air factor. The control module 40 is used for adjusting the swing angle of the burner according to the swing angle control signal of the burner, so as to control the outlet steam temperature of the secondary reheating boiler according to the adjusted swing angle of the burner.
According to an embodiment of the present invention, the third obtaining module 30 obtains the burner tilt angle control signal according to the reheater outlet temperature setpoint, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation amount, and the excess air factor, and is specifically configured to: acquiring an average value of primary reheater outlet temperature and secondary reheater outlet temperature; calculating a difference value between a reheater outlet temperature set value and the average value, and when the difference value is not zero, performing proportional integral control on the reheater outlet temperature set value and the average value to generate a first control signal; acquiring the total fuel quantity and unit load of the current secondary reheating boiler; summing the first control signal, the total fuel quantity of the current secondary reheating boiler and the unit load to obtain a second control signal; and acquiring a combustor swing angle control signal according to the second control signal, the flue gas recirculation quantity and the excess air coefficient.
According to an embodiment of the invention, the third obtaining module 30 obtains the burner tilt angle control signal according to the second control signal, the flue gas recirculation amount and the excess air ratio, and is specifically configured to: summing the product of the second control signal, the smoke recirculation quantity and the first preset value to obtain a third control signal; and carrying out summation operation on the third control signal, the product of the excess air coefficient and the second preset value to obtain a swing angle control signal of the combustor.
According to one embodiment of the invention, the second acquisition module 20 acquires the flue gas recirculation quantity and the excess air ratio, in particular for: acquiring the minimum value of the economic sum of the reheated steam temperature; and acquiring the smoke recirculation quantity and the excess air coefficient according to the minimum value.
According to one embodiment of the invention, the second acquiring moduleThe block 20 obtains the economic sum P of the reheat steam temperature by the following formula*：
Wherein f isEsfThe electricity price is converted for the increment of the power consumption of the secondary fan,
for denitration ammonia injection increment conversion of material price, fEcfReduction of electricity price for power consumption saving of recirculation fan, fCThe coal price is converted for saving fuel, and the prices are calculated according to the unit load and the electricity generation time of 1 kilowatt hour.
According to one embodiment of the invention, the second acquisition module 20 acquires the flue gas recirculation quantity and the excess air ratio according to a minimum value, in particular for: acquiring corresponding power consumption of the recirculation fan and the secondary fan according to the minimum value; acquiring the flue gas recirculation amount according to the power consumption of the recirculation fan; and acquiring the excess air coefficient according to the power consumption of the secondary fan.
According to one embodiment of the invention, the control module 40 is further configured to: when a main fuel trip signal of the double reheat boiler is received, a burner tilt angle control signal is set to 0.
According to one embodiment of the invention, the control module 40 is further configured to: when an auxiliary machine fault load reducing signal of the double reheat boiler is received, the current swing angle of the burner is kept unchanged.
It should be noted that, details not disclosed in the outlet steam temperature control device of the double reheat boiler in the embodiment of the present invention refer to details disclosed in the outlet steam temperature control method of the double reheat boiler in the embodiment of the present invention, and details are not repeated herein.
To sum up, in the outlet steam temperature control device of the double reheat boiler according to the embodiment of the present invention, the first obtaining module obtains the reheater outlet temperature set value, the primary reheater outlet temperature and the secondary reheater outlet temperature, the second obtaining module obtains the flue gas recirculation amount and the excess air coefficient, the third obtaining module obtains the burner pivot angle control signal according to the reheater outlet temperature set value, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation amount and the excess air coefficient, and the control module adjusts the burner pivot angle according to the burner pivot angle control signal to control the outlet steam temperature of the double reheat boiler according to the adjusted burner pivot angle. From this, the device can realize controlling double reheat boiler, and whole process automation control degree is higher, has improved double reheat boiler's control efficiency and unit operation economic nature.
Corresponding to the embodiment, the invention further provides a double reheating boiler.
According to the double reheat boiler, the outlet steam temperature control device of the double reheat boiler has high automation control degree in the whole process, and the control efficiency and the unit operation economy of the double reheat boiler are improved.
In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The meaning of "plurality" is two or more unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A method of outlet steam temperature control for a double reheat boiler, said double reheat boiler including a flue gas recirculation system, said method comprising the steps of:
acquiring a reheater outlet temperature set value, a primary reheater outlet temperature and a secondary reheater outlet temperature;
acquiring a flue gas recirculation quantity and an excess air coefficient;
acquiring a combustor pivot angle control signal according to the reheater outlet temperature set value, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation amount and the excess air coefficient;
and adjusting the swing angle of the burner according to the control signal of the swing angle of the burner so as to control the outlet steam temperature of the secondary reheating boiler according to the adjusted swing angle of the burner.
2. The outlet steam temperature control method of a double reheat boiler of claim 1, wherein obtaining a burner tilt angle control signal based on the reheater outlet temperature setpoint, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation amount and the excess air factor comprises:
obtaining an average of the primary reheater outlet temperature and the secondary reheater outlet temperature;
calculating a difference value between the reheater outlet temperature set value and the average value, and when the difference value is not zero, performing proportional integral control on the reheater outlet temperature set value and the average value to generate a first control signal;
acquiring the total fuel quantity and the unit load of the current secondary reheating boiler;
summing the first control signal, the current total fuel quantity of the double reheat boiler and the unit load to obtain a second control signal;
and acquiring a combustor swing angle control signal according to the second control signal, the flue gas recirculation quantity and the excess air coefficient.
3. The outlet steam temperature control method of a double reheat boiler of claim 2, wherein obtaining a burner tilt angle control signal based on the second control signal, the flue gas recirculation amount and the excess air factor, comprises:
summing the product of the second control signal and the flue gas recirculation quantity with a first preset value to obtain a third control signal;
and carrying out summation operation on the third control signal, the product of the excess air coefficient and a second preset value to obtain the swing angle control signal of the combustor.
4. The outlet steam temperature control method of a double reheat boiler of claim 1, wherein obtaining a flue gas recirculation amount and an excess air factor, comprises:
acquiring the minimum value of the economic sum of the reheated steam temperature;
and acquiring the smoke recirculation quantity and the excess air coefficient according to the minimum value.
5. The outlet steam temperature control method of a double reheat boiler as set forth in claim 4, wherein the economical sum P of the reheat steam temperatures is obtained by the following formula*：
Wherein f isEsfThe electricity price is converted for the increment of the power consumption of the secondary fan,
for denitration ammonia injection increment conversion of material price, fEcfReduction of electricity price for power consumption saving of recirculation fan, fCConversion of coal prices to fuel economy, aboveThe grids are calculated according to the unit load conversion as the electric quantity per 1 kilowatt hour.
6. The outlet steam temperature control method of a double reheat boiler of claim 5, wherein obtaining the flue gas recirculation amount and the excess air factor according to the minimum value comprises:
acquiring corresponding power consumption of the recirculation fan and the secondary fan according to the minimum value;
acquiring the flue gas recirculation amount according to the power consumption of the recirculation fan;
and acquiring the excess air coefficient according to the power consumption of the secondary air fan.
7. The outlet steam temperature control method of a double reheat boiler according to claim 1, further comprising:
and when a main fuel trip signal of the double reheat boiler is received, setting the burner swing angle control signal to be 0.
8. The outlet steam temperature control method of a double reheat boiler according to claim 1, further comprising:
when an auxiliary machine fault load reducing signal of the double reheat boiler is received, the current swing angle of the burner is kept unchanged.
9. An outlet steam temperature control apparatus of a double reheat boiler, wherein the double reheat boiler comprises a flue gas recirculation system, the apparatus comprising:
the first acquisition module is used for acquiring a reheater outlet temperature set value, a primary reheater outlet temperature and a secondary reheater outlet temperature;
the second acquisition module is used for acquiring the flue gas recirculation quantity and the excess air coefficient;
a third obtaining module, configured to obtain a combustor tilt angle control signal according to the reheater outlet temperature set value, the primary reheater outlet temperature, the secondary reheater outlet temperature, the flue gas recirculation amount, and the excess air coefficient;
and the control module is used for adjusting the swing angle of the burner according to the burner swing angle control signal so as to control the outlet steam temperature of the secondary reheating boiler according to the adjusted swing angle of the burner.
10. A double reheat boiler, comprising: a flue gas recirculation system and an outlet steam temperature control device of a double reheat boiler as set forth in claim 9.
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