CN107092186B - Furnace water dosing method and system - Google Patents
Furnace water dosing method and system Download PDFInfo
- Publication number
- CN107092186B CN107092186B CN201710355287.3A CN201710355287A CN107092186B CN 107092186 B CN107092186 B CN 107092186B CN 201710355287 A CN201710355287 A CN 201710355287A CN 107092186 B CN107092186 B CN 107092186B
- Authority
- CN
- China
- Prior art keywords
- conductivity
- dosing pump
- signal
- control
- threshold
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 124
- 238000000034 method Methods 0.000 title claims abstract description 36
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 65
- 239000010452 phosphate Substances 0.000 claims abstract description 63
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 57
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000005070 sampling Methods 0.000 abstract description 3
- 230000001276 controlling effect Effects 0.000 description 12
- 239000003814 drug Substances 0.000 description 8
- 239000000126 substance Substances 0.000 description 6
- 238000012544 monitoring process Methods 0.000 description 5
- 230000003247 decreasing effect Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 208000028659 discharge Diseases 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000009545 invasion Effects 0.000 description 1
- 238000013178 mathematical model Methods 0.000 description 1
- 229940085991 phosphate ion Drugs 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000008400 supply water Substances 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
- 229910000406 trisodium phosphate Inorganic materials 0.000 description 1
- 235000019801 trisodium phosphate Nutrition 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B11/00—Automatic controllers
- G05B11/01—Automatic controllers electric
- G05B11/36—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
- G05B11/42—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Control Of Non-Electrical Variables (AREA)
Abstract
The invention discloses a furnace water dosing method and system. The method comprises the following steps: acquiring index data in a furnace water sample, wherein the index data comprises phosphate concentration, pH, conductivity and water supply quantity; acquiring the change rate of the unit load; judging whether the change rate is within a set threshold range; when the judgment result shows that the water temperature is higher than the preset temperature, performing PID control on the furnace water by taking the phosphate concentration as a main control parameter and taking the pH and the conductivity as auxiliary control parameters to generate a first opening signal of the dosing pump; when the judgment result shows that the water feeding quantity is not the control parameter, performing PID control on the furnace water by taking the water feeding quantity as the control parameter to generate a second opening signal of the dosing pump; generating a control signal according to the opening degree signal; and controlling the rotating speed of a motor of the dosing pump according to the control signal. The invention can more comprehensively ensure the stability and reliability of the control parameters, reduce the delay of the control process, improve the control precision and avoid the fluctuation and the error of a single parameter caused by a signal sampling error.
Description
Technical Field
The invention relates to the field of furnace water automatic control, in particular to a furnace water dosing method and system.
Background
In order to ensure the safe and economic operation of a thermal power plant, reduce the corrosion rate of boiler tubes, reduce the sediment and scaling amount of the boiler tubes and improve the steam quality, the boiler water of the boiler needs to be regulated. For medium and low pressure drum boilers, the boiler water is generally treated by adopting a coordinated phosphate treatment method, and for high pressure large capacity units, the boiler water is treated by adopting a low phosphate treatment method. The pH value, the conductivity and the phosphate radical of the boiler water are 3 important indexes of the boiler water quality. For the low phosphate treatment process, the pH value is required to be 9-10, the conductivity is about 15 mu S/cm, and the phosphate radical is required to be 0.5-3 mg/L.
In fact, to achieve the above control objectives, Na3PO4 is generally added to the furnace water. In most cases, the low-phosphate treatment of the furnace water is carried out manually, firstly, the pH value, the conductivity and the phosphate content of the furnace water are measured manually, and whether a phosphate adding medicine pump needs to be started (or stopped) is determined according to parameter conditions. The manual medicine adding can not be well mastered due to the on-off control of the motor, and the control index is high due to the possibility of overhigh medicine concentration or overlong adding time; or the medicine concentration is too low, the adding time is too short, the stopping time is too long, and the control index is low. Therefore, the existing boiler water dosing mode can cause the actual parameters to seriously deviate from the optimal values, and threatens the safe operation of the boiler.
The most critical issue for achieving automation of phosphate dosing is real-time online monitoring of the furnace water PO 43-concentration. The phosphorus meter is required to be accurate in measurement and high in measurement speed, the time for the boiler water to be decompressed from a steam drum through a steam-water sampling device and reduced in temperature is about 10-20 minutes, and if the phosphorus meter is slow in measurement speed, for example, 10 minutes, the lag time of the whole system is about 20-30 minutes. The working conditions of the unit can change at any time, such as the change of the supply water quantity, the change of the pollution discharge of a steam drum, the start and stop of heat supply, the fluctuation of power generation load and the change of the concentration of a medicine box during manual medicine dispensing, which can cause the great change of the content of phosphate in the system. Therefore, the lag in the furnace water phosphate ion concentration signal is extremely detrimental to automatic dosing regulation.
Disclosure of Invention
The invention aims to provide a furnace water dosing method and a furnace water dosing system, which aim to solve the problem that the furnace water dosing adjustment precision is low due to data acquisition lag in the existing dosing method.
In order to achieve the purpose, the invention provides the following scheme:
a method of dosing furnace water, the method comprising:
acquiring index data in a furnace water sample, wherein the index data comprises phosphate concentration, pH, conductivity and water supply quantity;
acquiring the change rate of the unit load;
judging whether the change rate is within a set threshold range to obtain a first judgment result;
when the first judgment result shows that the speed is within a set threshold range, performing proportional-integral-differential control on the furnace water by taking the phosphate concentration as a main control parameter and taking the pH and the conductivity as auxiliary control parameters to generate a first opening signal of the dosing pump;
generating a first control signal according to the first opening signal of the dosing pump;
controlling the rotating speed of a motor of the dosing pump according to the first control signal;
when the first judgment result shows that the speed is not in the range of the set threshold value, performing proportional-integral-derivative control on the furnace water by taking the water supply amount as a control parameter to generate a second opening signal of the dosing pump;
generating a second control signal according to the second opening signal of the dosing pump;
and controlling the rotating speed of a motor of the dosing pump according to the second control signal.
Optionally, when the first determination result indicates that the speed is within a set threshold range, performing proportional-integral-derivative control on the furnace water by using the phosphate concentration as a main control parameter and using the pH and the conductivity as auxiliary control parameters to generate a first opening signal of the dosing pump, specifically including:
judging whether the pH value is smaller than a first set pH threshold value and the conductivity is smaller than a first set conductivity threshold value to obtain a second judgment result;
when the second judgment result shows that the pH is smaller than a first set pH threshold value and the conductivity is smaller than a first set conductivity threshold value, determining that the opening of the dosing pump is controlled to be 100%, and determining that a signal with the opening of the dosing pump being 100% is a first opening signal;
when the second judgment result shows that the pH value is not less than a first set pH threshold value or the conductivity is not less than a first set conductivity threshold value, judging whether the pH value is greater than a second set pH threshold value or not and the conductivity is greater than a second set conductivity threshold value to obtain a third judgment result;
when the third judgment result shows that the pH value is greater than a second set pH threshold value and the conductivity is greater than a second set conductivity threshold value, determining that the opening of the dosing pump is controlled to be 0, and determining that a signal of the opening of the dosing pump being 0 is a first opening signal;
when the third judgment result shows that the pH value is not greater than a second set pH threshold value or the conductivity is not greater than a second set conductivity threshold value, judging whether the first set pH threshold value is not greater than the pH value and not greater than the second set pH threshold value and the first set conductivity threshold value is not greater than the conductivity and not greater than the second set conductivity threshold value to obtain a fourth judgment result;
when the fourth judgment result shows yes, using a formulaCalculating the opening degree N of the dosing pump1%, wherein c1Is the phosphate concentration, c2Determining the opening degree of the dosing pump to be N for the maximum phosphate content set in the control range1Percent, determining the opening degree of the dosing pump as N1% of the signal is the first opening signal.
Optionally, the first set pH threshold is 9.0, the second set pH threshold is 10.0, the first set conductivity threshold is 5 μ S/cm, and the second set conductivity threshold is 25 μ S/cm.
Optionally, when the first determination result indicates that the speed is not within the set threshold range, performing proportional-integral-derivative control on the furnace water by using the water supply amount as a control parameter to generate a second opening signal specifically includes:
using formulasCalculating the opening degree N of the dosing pump2%, wherein Q1Is that it isWater supply flow rate, Q2Determining the opening degree of the dosing pump to be N for the maximum water supply flow set in the control range2% of the signal is the second opening signal.
Optionally, the controlling the rotation speed of the motor of the dosing pump according to the second control signal further includes:
and adjusting the control parameters of the proportional-integral-derivative control according to the adding amount and the adding time of the dosing pump to the furnace water and the pH and the conductivity of the furnace water before dosing, and compensating the lag time between the index time and the dosing time.
A furnace water dosing system, the system comprising:
the index data acquisition module is used for acquiring index data in the furnace water sample, wherein the index data comprises phosphate concentration, pH, conductivity and water supply quantity;
the change rate acquisition module is used for acquiring the change rate of the unit load;
the first judgment module is used for judging whether the change rate is within a set threshold range to obtain a first judgment result;
the first opening signal generation module is used for performing proportional-integral-derivative control on the furnace water by taking the phosphate concentration as a main control parameter and taking the pH and the conductivity as auxiliary control parameters to generate a first opening signal of the dosing pump when the first judgment result shows that the speed is within a set threshold range;
the first control signal generation module is used for generating a first control signal according to the first opening signal of the dosing pump;
the rotating speed control module is used for controlling the rotating speed of a motor of the dosing pump according to the first control signal;
the second opening signal generating module is used for performing proportional-integral-derivative control on the furnace water by taking the water supply amount as a control parameter to generate a second opening signal of the dosing pump when the first judgment result shows that the speed is not in a set threshold range;
the second control signal generation module is used for generating a second control signal according to a second opening signal of the dosing pump;
the rotating speed control module is also used for controlling the rotating speed of a motor of the dosing pump according to the second control signal.
Optionally, the first opening degree signal generating module specifically includes:
the second judgment unit is used for judging whether the pH value is smaller than a first set pH threshold value and the conductivity is smaller than a first set conductivity threshold value to obtain a second judgment result;
a first opening signal determination unit, configured to determine that the opening of the dosing pump is controlled to be 100% and determine that a signal indicating that the opening of the dosing pump is 100% is a first opening signal when the second determination result indicates that the pH is less than a first set pH threshold and the conductivity is less than a first set conductivity threshold;
a third determining unit, configured to determine whether the pH is greater than a second set pH threshold and the conductivity is greater than a second set conductivity threshold when the second determination result indicates that the pH is not less than a first set pH threshold or the conductivity is not less than a first set conductivity threshold, so as to obtain a third determination result;
the first opening signal determining unit is further configured to determine that the opening of the dosing pump is controlled to be 0 and determine that a signal indicating that the opening of the dosing pump is 0 is a first opening signal when the third determination result indicates that the pH is greater than a second set pH threshold and the conductivity is greater than a second set conductivity threshold;
a fourth judging unit, configured to, when the third judgment result indicates that the pH is not greater than the second set pH threshold or the conductivity is not greater than the second set conductivity threshold, judge whether the first set pH threshold is not greater than the pH and not greater than the second set pH threshold, and the first set conductivity threshold is not greater than the conductivity and not greater than the second set conductivity threshold, so as to obtain a fourth judgment result;
a first opening degree signal determination unit further configured to use a formula when the fourth determination result indicates yes
ComputingOpening degree N of the dosing pump1%, wherein c1Is the phosphate concentration, c2Determining the opening degree of the dosing pump to be N for the maximum phosphate content set in the control range1Percent, determining the opening degree of the dosing pump as N1% of the signal is the first opening signal.
Optionally, the first set pH threshold is 9.0, the second set pH threshold is 10.0, the first set conductivity threshold is 5 μ S/cm, and the second set conductivity threshold is 25 μ S/cm.
Optionally, the second opening degree signal generating module specifically includes:
an opening degree calculation unit for using a formulaCalculating the opening degree N of the dosing pump2%, wherein Q1Is the feed water flow, Q2The maximum water supply flow is set in the control range;
a second opening signal determination unit for determining that the opening of the dosing pump is controlled to be N2% of the signal is the second opening signal.
Optionally, the system further includes:
and the control parameter adjusting module is used for adjusting the control parameters of the proportional-integral-derivative control according to the adding amount and the adding time of the dosing pump to the furnace water and the pH and the conductivity of the furnace water before dosing, and compensating the acquired lag time between the index time and the dosing time.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
by acquiring the phosphate content, pH, conductivity and water supply flow of the furnace water in real time and adopting a plurality of control parameters to simultaneously control the process of adding the chemicals into the furnace water, the stability and reliability of the control parameters are more comprehensively ensured, the delay of the control process is reduced, the control precision is improved, and the fluctuation and misoperation of a single parameter caused by a signal sampling error at one time are avoided; the establishment of the automatic dosing method lays a foundation for the design and development of the automatic dosing device, the automatic dosing is realized, the labor intensity of workers can be reduced, and adverse accidents caused by human factors are avoided; realizes scientific dosing and provides guarantee for the economic and stable operation of the boiler.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flowchart of a method for adding chemicals to furnace water according to example 1 of the present invention;
FIG. 2 is a structural view of a furnace water chemical-adding system in accordance with an embodiment 1 of the present invention;
FIG. 3 is a structural view of a furnace water chemical-adding system in accordance with an embodiment 2 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.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The furnace water dosing method of the invention comprises the following steps:
FIG. 1 is a flowchart of a method for adding chemicals to furnace water according to embodiment 1 of the present invention. As shown in fig. 1, the method includes:
step 101: index data is acquired. And acquiring index data in the furnace water sample, wherein the index data comprises phosphate concentration, pH, conductivity and water supply quantity. The index data is transmitted to the central controller in the form of a phosphate concentration meter, a conductivity meter, a pH meter and a water supply meter.
Step 102: and acquiring the change rate of the unit load. And monitoring the change rate of the unit load in real time, namely the speed of the unit for increasing and decreasing the load.
Step 103: and judging whether the change rate is within a set threshold value range. The judgment of whether the change rate is within the set threshold value range is to judge whether the state in the furnace water is the state of the make-up water at the moment. The set threshold range can be 5 MW/min-7 MW/min, the change rate is in the range, namely, the stable state, and the water supply state is not in the range. When the change rate is within the set threshold range, executing step 104; otherwise, step 107 is performed.
Step 104: a first opening degree signal is generated. And performing proportional-integral-derivative (PID) control on the furnace water by taking the phosphate concentration as a main control parameter and taking the pH and the conductivity as auxiliary control parameters to generate a first opening signal of the dosing pump. The specific judgment process is as follows:
(1) judging whether the following conditions are met: the first set pH threshold is less than or equal to the pH value and less than or equal to the second set pH threshold, and the first set conductivity threshold is less than or equal to the conductivity and less than or equal to the second set conductivity threshold. When satisfied, using the formula
Calculating the opening degree N of the dosing pump1%, wherein c1Is the phosphate concentration, c2Determining the opening degree of the dosing pump to be N for the maximum phosphate content set in the control range, namely the allowed maximum phosphate content or the maximum phosphate content in the expected control range1Percent, determining the opening degree of the dosing pump as N1% of the signal is a first opening signal;
(2) judging whether the following conditions are met: pH < first set pH threshold, and the conductivity < first set conductivity threshold. When the first opening signal is met, determining that the opening of the dosing pump is controlled to be 100%, and determining that a signal of the opening of the dosing pump is 100% as a first opening signal;
(3) judging whether the following conditions are met: pH > a second set pH threshold, and the conductivity > a second set conductivity threshold. When the first opening signal is met, determining that the opening of the dosing pump is controlled to be 0, and determining that a signal of the opening of the dosing pump is 0 is a first opening signal;
the above three judgment processes are simultaneously operated in parallel, and generally, when the pH is less than the first set pH threshold, the conductivity also meets the condition that the conductivity is less than the first set conductivity threshold. When the pH > a second set pH threshold, the conductivity will also satisfy the condition that the conductivity > a second set conductivity threshold.
Step 105: a first control signal is generated. And calculating the output frequency of the dosing pump corresponding to the first opening signal according to the first opening signal generated in the step 104, and generating a first control signal for controlling the rotation speed of the dosing pump.
Step 106: and controlling the rotating speed of the motor. And adjusting the motor rotating speed of the dosing pump through the variable-frequency speed regulator according to the first control signal so as to adjust the dosing amount of the dosing pump.
Step 107: a second opening degree signal is generated. Performing proportional-integral-derivative (PID) control on the furnace water by taking the water supply amount as a control parameter to generate a second opening signal of the dosing pump; using formula specifically
Calculating the opening degree N of the dosing pump2%, wherein Q1Is the feed water flow, Q2Determining the opening degree of the dosing pump to be N for the maximum water supply flow set in the control range2% of the signal is the second opening signal.
Step 108: a second control signal is generated. And calculating the output frequency of the dosing pump corresponding to the second opening signal according to the second opening signal generated in the step 107, and generating a second control signal for controlling the rotation speed of the dosing pump.
Step 109: and controlling the rotating speed of the motor. And adjusting the motor rotating speed of the dosing pump through the variable-frequency speed regulator according to the second control signal so as to adjust the dosing amount of the dosing pump.
The embodiment 1 of the furnace water dosing system of the invention:
FIG. 2 is a structural diagram of a furnace water chemical-adding system in accordance with an embodiment 1 of the present invention. As shown in fig. 2, the system includes:
an index data acquisition module 201, configured to acquire index data in a furnace water sample, where the index data includes phosphate concentration, pH, conductivity, and water supply amount;
the change rate obtaining module 202 is used for obtaining the change rate of the unit load;
the first judging module 203 is configured to judge whether the change rate is within a set threshold range, so as to obtain a first judgment result;
a first opening signal generating module 204, configured to, when the first determination result indicates that the speed is within a set threshold range, perform proportional-integral-derivative control on the furnace water with the phosphate concentration as a main control parameter and the pH and the conductivity as auxiliary control parameters, so as to generate a first opening signal of the dosing pump;
a first control signal generating module 205, configured to generate a first control signal according to the first opening signal of the dosing pump;
a rotation speed control module 206, configured to control a rotation speed of a motor of the dosing pump according to the first control signal;
a second opening signal generating module 207, configured to perform proportional-integral-derivative control on the furnace water with the feed water amount as a control parameter when the first determination result indicates that the speed is not within a set threshold range, so as to generate a second opening signal of the dosing pump;
the second control signal generation module 208 is configured to generate a second control signal according to the second opening signal of the dosing pump;
the rotation speed control module 206 is further configured to control a rotation speed of a motor of the dosing pump according to the second control signal.
The furnace water dosing method of the invention embodiment 2:
the water in a 600MW subcritical wet cooling coal-fired unit is treated by phosphate, a continuous dosing mode is adopted, and the pH value of the water in the furnace is 9-10. The addition amount of the phosphate is ensured: at low load, PO is maintained4 3-0.5-3 mg/L; maintaining PO at medium load4 3-At 0.5-1.5 mg/L; maintaining PO at high load4 3-In the range of 0.5-1mg/L. When the condenser leaks, the addition of phosphate should be increased to maintain PO4 3-2-10 mg/L, and enhances the pollution discharge treatment. Meanwhile, the pH value of the furnace water is required to be 9.0-10.0, and the conductivity is required to be 5-25 mu S/cm. The control method of furnace water multi-parameter cooperative automatic dosing is adopted, four parameters of furnace water phosphate radical concentration, pH, DD and water supply flow are introduced, and a phosphate system is regulated and controlled. The method mainly combines an alternating current frequency conversion technology with a computer control technology, and multi-parameter coordination control enables a system to be more stable and reliable.
Firstly, establishing a mathematical model for dosing control: according to the correlation between the concentration of phosphate in the furnace water and the pH value, conductivity and conductivity, a model for automatically controlling phosphate dosing by adopting PID is established.
Before the model is operated every time, PID control parameters are adjusted according to the addition amount and the addition time of phosphate in the furnace water and the correlation among pH and conductivity, so that the lag time between the addition amount and the reading of a phosphate meter is effectively compensated.
The method for adding chemicals into furnace water is started to operate according to the established model:
step 1, taking a furnace water sample from the lower half side of a vertical section or a horizontal section of a continuous sewage discharge pipe, and analyzing and measuring the water sample after temperature reduction and pressure reduction;
step 2, measuring four parameters of phosphate concentration, pH, conductivity and water supply flow of the furnace water sample, and feeding back a parameter signal obtained by monitoring to a central controller;
and 3, monitoring the load increasing and decreasing speed of the unit, and feeding parameter signals back to the central controller.
And 4, comparing and calculating the monitored phosphate radical concentration, pH value and conductivity value with set values by the central controller, and adjusting PID control parameters according to the load increase and decrease speed of the unit to generate different control signals. After intelligent PID setting, the control signal is transmitted to the variable frequency speed regulator.
The specific PID setting process is as follows:
(1) when the unit works with stable load, namely the load change of the unit is stable within 6MW/min (which can be determined by unit parameters), phosphate radical (PO) is used4 3-) And as a main control parameter, a conductivity meter and a pH meter are used as auxiliary control parameters to control the dosage of the furnace water dosing pump. The method specifically comprises the following three steps:
a: when the pH value is between 9.0 and 10.0 and the conductivity is between 5 and 25 mu S/cm, the formula is used
Calculating the opening N of the dosing pump1％，c1The concentration of phosphate read on line is in mg/L; c. C2The unit is mg/L for the maximum phosphate content set in the control range or the maximum phosphate content in the expected control range; determining the opening degree of the dosing pump to be N1Percent, determining the opening degree of the dosing pump as N1% of the signal is the first opening signal,
b: when the pH value is less than 9.0, the output of the opening N% of the medicine feeding pump is 100%, and when the pH value is more than 10, the output of the N% is 0.
C: when the conductivity is less than 5 muS/cm, the output of the opening N% of the medicine feeding pump is 100%, and when the conductivity is more than 25 muS/cm, the output of the N% is 0.
The three steps are carried out in parallel and are independent of each other, the output frequencies of different dosing pumps correspond to different opening degrees, the output frequency of the dosing pump is calculated according to the determined opening degree signal of the dosing pump, the obtained calculation result is sent to a variable-frequency speed regulator, the output of the variable-frequency speed regulator is three-phase alternating current with variable frequency, and the motor can be driven to rotate.
The two parameters of the pH value and the conductivity of the furnace water are determined by the content of phosphate under the normal operation condition of the system, and PO is calculated according to theory4 3-The content is controlled within a reasonable range, the pH and the conductivity are also within reasonable ranges, so the system is normally PO4 3-As the master parameter. When other substances causing corrosion enter the boiler, if the system leaks or the quality of the make-up water is deteriorated, the conductivity value of the boiler water is increased on the contrary, the conductivity value is increased not because of adding phosphate but because of the entering of impurities, and the automatic feeding of phosphate by controlling the content of phosphate can not be realized,it must be controlled by conductivity. Meanwhile, the pH value is changed due to the invasion of other impurities, the content of the monitored phosphate is not greatly changed, and automatic phosphate feeding control by using the content of the phosphate cannot be realized, so that the control by the pH value is required.
(2) When the load of the unit is greatly increased or decreased, the feed water flow signal is taken as a control parameter to control the dosage of the furnace water dosing pump; using formula formulas
Calculating the opening degree N of the dosing pump2%, wherein Q1The unit is t/h, and the feed water flow is the unit; q2The unit of the maximum water supply flow set in the control range is t/h, namely the allowable maximum water supply flow. The output frequencies of different dosing pumps correspond to different opening degrees, the output frequency of the dosing pump is calculated according to the determined opening degree signal of the dosing pump, the obtained operation result is sent to a variable-frequency speed regulator, and the output of the variable-frequency speed regulator is three-phase alternating current with variable frequency and can drive a motor to rotate.
When the peak load of the unit is regulated, PO is generated due to large fluctuation of water supply flow4 3-The three parameters of the conductivity and the pH value have large fluctuation, and the flow can be used as the dosing basis. If the load increasing and decreasing speed of the unit is controlled, corresponding flow control indexes are recorded as at/h, and when the change value of the flow signal exceeds the current value corresponding to the at/h every minute in a certain stage (such as 5min, 10min and the like), the control parameters of the multi-parameter cooperative automatic dosing control system are switched to the water supply flow control.
S5, controlling the rotation speed of the motor by the variable-frequency speed regulator according to the frequency of the dosing pump corresponding to the opening degree to control the dosing amount of the dosing pump.
The embodiment 2 of the furnace water dosing system of the invention:
FIG. 3 is a structural view of an embodiment 2 of the furnace water chemical adding system of the invention, and as shown in FIG. 3, the structure comprises: the four monitoring instruments (a phosphate meter 301, a pH meter 302, a DD meter 303 and a flow meter 304) output 4-20 mA signals to a central controller 305 on the variable frequency control cabinet, and set values in the central controller 305 are compared with corresponding measured values. The central controller 305 performs PID control according to the comparison value to output a control signal to the AC motor 306, and changes the output frequency of the AC motor 306, thereby changing the dosing amount of the phosphate dosing pump 307 and realizing the automatic control of the dosing amount. The control parameters can be subjected to common PID regulation and self-tuning automatic regulation.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (8)
1. A furnace water dosing method is characterized by comprising the following steps:
acquiring index data in a furnace water sample, wherein the index data comprises phosphate concentration, pH, conductivity and water supply quantity;
acquiring the change rate of the unit load;
judging whether the change rate of the unit load is within a set threshold range or not to obtain a first judgment result;
when the first judgment result shows that the change rate of the unit load is within a set threshold range, performing proportional-integral-derivative control on the furnace water by taking the phosphate concentration as a main control parameter and taking the pH and the conductivity as auxiliary control parameters to generate a first opening signal of the dosing pump; the method specifically comprises the following steps: judging whether the pH value is smaller than a first set pH threshold value and the conductivity is smaller than a first set conductivity threshold value to obtain a second judgment result; when the second judgment result indicates the pHWhen the pH value is smaller than a first set pH threshold value and the conductivity is smaller than a first set conductivity threshold value, determining that the opening of the dosing pump is controlled to be 100%, and determining that a signal of the opening of the dosing pump being 100% is a first opening signal; when the second judgment result shows that the pH value is not less than a first set pH threshold value or the conductivity is not less than a first set conductivity threshold value, judging whether the pH value is greater than a second set pH threshold value or not and the conductivity is greater than a second set conductivity threshold value to obtain a third judgment result; when the third judgment result shows that the pH value is greater than a second set pH threshold value and the conductivity is greater than a second set conductivity threshold value, determining that the opening of the dosing pump is controlled to be 0, and determining that a signal of the opening of the dosing pump being 0 is a first opening signal; when the third judgment result shows that the pH value is not greater than a second set pH threshold value or the conductivity is not greater than a second set conductivity threshold value, judging whether the pH value is not greater than the first set pH threshold value and not greater than the second set pH threshold value and the conductivity is not greater than the first set conductivity threshold value and not greater than the second set conductivity threshold value to obtain a fourth judgment result; when the fourth judgment result shows yes, using a formula
Calculating the opening degree N of the dosing pump1%, wherein c1Is the phosphate concentration, c2Determining the opening degree of the dosing pump to be N for the maximum phosphate content set in the control range1Percent, determining the opening degree of the dosing pump as N1% of the signal is a first opening signal;
generating a first control signal according to the first opening signal of the dosing pump;
controlling the rotating speed of a motor of the dosing pump according to the first control signal;
when the first judgment result shows that the change rate of the unit load is not in a set threshold range, performing proportional-integral-derivative control on the furnace water by taking the water supply amount as a control parameter to generate a second opening signal of the dosing pump;
generating a second control signal according to the second opening signal of the dosing pump;
and controlling the rotating speed of a motor of the dosing pump according to the second control signal.
2. The method of claim 1, wherein the first set pH threshold is 9.0, the second set pH threshold is 10.0, the first set conductivity threshold is 5 μ S/cm, and the second set conductivity threshold is 25 μ S/cm.
3. The method according to claim 1, wherein when the first determination result indicates that the change rate of the unit load is not within a set threshold value range, performing proportional-integral-derivative control on the furnace water by using the feed water amount as a control parameter to generate the second opening signal of the dosing pump specifically comprises:
using formulas
Calculating the opening degree N of the dosing pump2%, wherein Q1Is the feed water flow, Q2Determining the opening degree of the dosing pump to be N for the maximum water supply flow set in the control range2% of the signal is the second opening signal.
4. The method of claim 1, wherein controlling a rotational speed of a motor of the dosing pump based on the second control signal further comprises:
and adjusting the control parameters of the proportional-integral-derivative control according to the adding amount and the adding time of the dosing pump to the furnace water and the pH and the conductivity of the furnace water before dosing, and compensating the lag time between the index time and the dosing time.
5. A furnace water dosing system, comprising:
the index data acquisition module is used for acquiring index data in the furnace water sample, wherein the index data comprises phosphate concentration, pH, conductivity and water supply quantity;
the change rate acquisition module is used for acquiring the change rate of the unit load;
the first judgment module is used for judging whether the change rate is within a set threshold range to obtain a first judgment result;
the first opening signal generation module is used for performing proportional-integral-differential control on the furnace water by taking the phosphate concentration as a main control parameter and taking the pH and the conductivity as auxiliary control parameters to generate a first opening signal of the dosing pump when the first judgment result shows that the change rate of the unit load is within a set threshold range; the first opening degree signal generating module specifically includes: the second judgment unit is used for judging whether the pH value is smaller than a first set pH threshold value and the conductivity is smaller than a first set conductivity threshold value to obtain a second judgment result; a first opening signal determination unit, configured to determine that the opening of the dosing pump is controlled to be 100% and determine that a signal indicating that the opening of the dosing pump is 100% is a first opening signal when the second determination result indicates that the pH is less than a first set pH threshold and the conductivity is less than a first set conductivity threshold; a third determining unit, configured to determine whether the pH is greater than a second set pH threshold and the conductivity is greater than a second set conductivity threshold when the second determination result indicates that the pH is not less than a first set pH threshold or the conductivity is not less than a first set conductivity threshold, so as to obtain a third determination result; the first opening signal determining unit is further configured to determine that the opening of the dosing pump is controlled to be 0 and determine that a signal indicating that the opening of the dosing pump is 0 is a first opening signal when the third determination result indicates that the pH is greater than a second set pH threshold and the conductivity is greater than a second set conductivity threshold; a fourth judging unit, configured to, when the third judgment result indicates that the pH is not greater than the second set pH threshold or the conductivity is not greater than the second set conductivity threshold, judge whether the first set pH threshold is not greater than the pH and not greater than the second set pH threshold, and the first set conductivity threshold is not greater than the conductivity and not greater than the second set conductivity threshold, and obtain a fourth judgment result; a first opening degree signal determination unit further configured to use a formula when the fourth determination result indicates yes
Calculating the opening degree N of the dosing pump1%, wherein c1Is the phosphate concentration, c2Determining the opening degree of the dosing pump to be N for the maximum phosphate content set in the control range1Percent, determining the opening degree of the dosing pump as N1% of the signal is a first opening signal;
the first control signal generation module is used for generating a first control signal according to the first opening signal of the dosing pump;
the rotating speed control module is used for controlling the rotating speed of a motor of the dosing pump according to the first control signal;
the second opening signal generation module is used for performing proportional-integral-derivative control on the furnace water by taking the water supply amount as a control parameter to generate a second opening signal of the dosing pump when the first judgment result shows that the change rate of the unit load is not within a set threshold range;
the second control signal generation module is used for generating a second control signal according to a second opening signal of the dosing pump;
the rotating speed control module is also used for controlling the rotating speed of a motor of the dosing pump according to the second control signal.
6. The system of claim 5, wherein the first set pH threshold is 9.0, the second set pH threshold is 10.0, the first set conductivity threshold is 5 μ S/cm, and the second set conductivity threshold is 25 μ S/cm.
7. The system according to claim 5, wherein the second opening degree signal generating module specifically includes:
an opening degree calculation unit for using a formula
Calculating the opening degree N of the dosing pump2%, wherein Q1Is as described forWater flow rate, Q2The maximum water supply flow is set in the control range;
a second opening signal determination unit for determining that the opening of the dosing pump is controlled to be N2% of the signal is the second opening signal.
8. The system of claim 5, further comprising:
and the control parameter adjusting module is used for adjusting the control parameters of the proportional-integral-derivative control according to the adding amount and adding time of the dosing pump to the furnace water and the pH and conductivity of the furnace water before dosing after controlling the rotating speed of the motor of the dosing pump according to the second control signal, and compensating the obtained lag time between the index time and the dosing time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710355287.3A CN107092186B (en) | 2017-05-19 | 2017-05-19 | Furnace water dosing method and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710355287.3A CN107092186B (en) | 2017-05-19 | 2017-05-19 | Furnace water dosing method and system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107092186A CN107092186A (en) | 2017-08-25 |
| CN107092186B true CN107092186B (en) | 2020-01-14 |
Family
ID=59638811
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710355287.3A Active CN107092186B (en) | 2017-05-19 | 2017-05-19 | Furnace water dosing method and system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107092186B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108319129A (en) * | 2018-01-24 | 2018-07-24 | 江苏国信靖江发电有限公司 | Ammonification method, apparatus, equipment and the storage medium of condensate system |
| CN110850908B (en) * | 2019-11-08 | 2021-01-29 | 润电能源科学技术有限公司 | Method and device for adjusting pH value of boiler feed water and computer readable storage medium |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2176026A (en) * | 1985-05-31 | 1986-12-10 | Grace W R & Co | A method of and apparatus for dosing a material |
| CN1118768A (en) * | 1994-05-09 | 1996-03-20 | 上海电力学院 | Automatic monitoring system for boiler water in concert with PH-phosphate treatment |
| CN1328261A (en) * | 2001-07-17 | 2001-12-26 | 武汉凯迪电力股份有限公司 | Method for detecting phosphoric acid radical in boiler water of electric power plant |
| CN201272696Y (en) * | 2008-09-04 | 2009-07-15 | 江苏兴邦环保工程科技有限公司 | Full-automatic medicine adding apparatus |
| CN201526952U (en) * | 2009-09-23 | 2010-07-14 | 长沙理工大学 | Automatic Phosphate Adding Device for Power Plant Boiler |
| CN102295354A (en) * | 2010-06-25 | 2011-12-28 | 宝山钢铁股份有限公司 | Dosing control method of phosphate in middle-low pressure boiler |
| CN205787929U (en) * | 2016-05-31 | 2016-12-07 | 大唐贵州发耳发电有限公司 | The Automatic Dosing of a kind of therrmodynamic system controls device |
| CN206281525U (en) * | 2016-12-23 | 2017-06-27 | 北京京诚科林环保科技有限公司 | Soda water quality detection and regulation system |
-
2017
- 2017-05-19 CN CN201710355287.3A patent/CN107092186B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2176026A (en) * | 1985-05-31 | 1986-12-10 | Grace W R & Co | A method of and apparatus for dosing a material |
| CN1118768A (en) * | 1994-05-09 | 1996-03-20 | 上海电力学院 | Automatic monitoring system for boiler water in concert with PH-phosphate treatment |
| CN1328261A (en) * | 2001-07-17 | 2001-12-26 | 武汉凯迪电力股份有限公司 | Method for detecting phosphoric acid radical in boiler water of electric power plant |
| CN201272696Y (en) * | 2008-09-04 | 2009-07-15 | 江苏兴邦环保工程科技有限公司 | Full-automatic medicine adding apparatus |
| CN201526952U (en) * | 2009-09-23 | 2010-07-14 | 长沙理工大学 | Automatic Phosphate Adding Device for Power Plant Boiler |
| CN102295354A (en) * | 2010-06-25 | 2011-12-28 | 宝山钢铁股份有限公司 | Dosing control method of phosphate in middle-low pressure boiler |
| CN205787929U (en) * | 2016-05-31 | 2016-12-07 | 大唐贵州发耳发电有限公司 | The Automatic Dosing of a kind of therrmodynamic system controls device |
| CN206281525U (en) * | 2016-12-23 | 2017-06-27 | 北京京诚科林环保科技有限公司 | Soda water quality detection and regulation system |
Non-Patent Citations (2)
| Title |
|---|
| 火电厂锅炉水质调节加药系统的自动控制;曹顺安，等;《工业水处理》;20030930;第23卷(第9期);摘要、第54-56页 * |
| 电厂锅炉加氨加联胺的自动水处理方法;王树东，等;《电气传动自动化》;20011031;第23卷(第5期);摘要、第72-74页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107092186A (en) | 2017-08-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110182924B (en) | Full-automatic ammonia preparing and adding integrated machine device and full-automatic ammonia preparing and adding method | |
| Veza et al. | Electrodialysis desalination designed for off-grid wind energy | |
| CN102008998A (en) | Automatic control device and automatic control method of hydrocyclone | |
| CN102997222B (en) | Boiler drum water level self-adaptation PID (proportion integration differentiation) control method | |
| CN104020800B (en) | Online dyeing feedback control system and method | |
| CN107092186B (en) | Furnace water dosing method and system | |
| CN110492497B (en) | A comprehensive diagnosis method and system for power oscillation of generator set | |
| CN201381846Y (en) | Screw pump well dynamic liquid level monitoring device | |
| CN101709863B (en) | Hybrid control method for furnace pressure system of coal-fired boiler | |
| CN206039234U (en) | Once -through boiler condensate water ammonifying personalizes and patrols and examines formula intelligence control system | |
| CN107543141B (en) | Steam generator analogue body water supply system and control method during increasing temperature and pressure | |
| CN1094592C (en) | Automatic testing and control method of dryness fraction of boiler | |
| CN108877973A (en) | Steam turbine for nuclear power station control method and control system | |
| CN112650050A (en) | Chemical ammonia addition automatic control method based on data modeling and multi-feedforward PID | |
| CN111987750A (en) | Online monitoring method and system for safety phase-advancing capability margin of generator | |
| CN201526952U (en) | Automatic Phosphate Adding Device for Power Plant Boiler | |
| CN114646051B (en) | Method and system for automatic control of boiler feed water in wet state of supercritical thermal power unit | |
| CN107628691B (en) | Aeration sewage treatment system and multi-parameter fuzzy control method thereof | |
| CN207082035U (en) | A kind of condensate polishing treatment control system | |
| CN114321722B (en) | Pressure balancing method and device for steam pipe network, storage medium and processor | |
| CN104638681A (en) | Method for preventing power fluctuation caused by water head signal change for automatic generation control hydropower station | |
| CN211264115U (en) | Accurate water-saving transmission control system of wet-cold thermal power generating unit based on intelligent wireless LoRa | |
| CN220223777U (en) | Adjusting and controlling system applied to chemical device water system | |
| CN112083704A (en) | Chemical plant control loop performance quantitative evaluation method and machine readable storage medium | |
| CN112628073B (en) | Yaw control method and device of wind generating set |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CB03 | Change of inventor or designer information |
Inventor after: Zhao Qiang Inventor after: Pang Zhanzhou Inventor after: Liu Jun Inventor after: Zhu Zhiping Inventor after: Jin Xuliang Inventor after: Li Yongli Inventor after: Wang Yinggao Inventor before: Zhao Qiang Inventor before: Pang Zhanzhou Inventor before: Liu Jun Inventor before: Zhu Zhiping Inventor before: Jin Xuliang Inventor before: Li Yongli Inventor before: Wang Yinggao |
|
| CB03 | Change of inventor or designer information |