CN112206640B - System and method for detecting pH value and concentration of limestone slurry in flying manner, control system and desulfurization system - Google Patents
System and method for detecting pH value and concentration of limestone slurry in flying manner, control system and desulfurization system Download PDFInfo
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- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 96
- 230000023556 desulfurization Effects 0.000 title claims abstract description 96
- 235000019738 Limestone Nutrition 0.000 title claims abstract description 69
- 239000006028 limestone Substances 0.000 title claims abstract description 69
- 239000002002 slurry Substances 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title abstract description 25
- 238000001514 detection method Methods 0.000 claims abstract description 91
- 238000005259 measurement Methods 0.000 claims abstract description 53
- 238000001914 filtration Methods 0.000 claims abstract description 38
- 230000008859 change Effects 0.000 claims abstract description 26
- 238000012545 processing Methods 0.000 claims abstract description 11
- 238000010521 absorption reaction Methods 0.000 claims description 21
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 15
- 239000003546 flue gas Substances 0.000 claims description 15
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 12
- 230000001502 supplementing effect Effects 0.000 claims description 9
- 238000002347 injection Methods 0.000 claims description 7
- 239000007924 injection Substances 0.000 claims description 7
- 229910021529 ammonia Inorganic materials 0.000 claims description 6
- 238000012790 confirmation Methods 0.000 claims description 6
- 239000000428 dust Substances 0.000 claims description 6
- 238000005507 spraying Methods 0.000 claims description 6
- 238000012546 transfer Methods 0.000 claims description 6
- 239000002250 absorbent Substances 0.000 claims description 4
- 230000002745 absorbent Effects 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 230000004044 response Effects 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 8
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 30
- 238000004140 cleaning Methods 0.000 description 9
- 239000003245 coal Substances 0.000 description 7
- 238000002485 combustion reaction Methods 0.000 description 7
- 239000003344 environmental pollutant Substances 0.000 description 5
- 230000006872 improvement Effects 0.000 description 5
- 231100000719 pollutant Toxicity 0.000 description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000004484 Briquette Substances 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000001139 pH measurement Methods 0.000 description 1
- 239000012716 precipitator Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
- B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
- B01D53/502—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific solution or suspension
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/76—Gas phase processes, e.g. by using aerosols
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/96—Regeneration, reactivation or recycling of reactants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D11/00—Control of flow ratio
- G05D11/02—Controlling ratio of two or more flows of fluid or fluent material
- G05D11/13—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means
- G05D11/139—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means by measuring a value related to the quantity of the individual components and sensing at least one property of the mixture
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/40—Alkaline earth metal or magnesium compounds
- B01D2251/404—Alkaline earth metal or magnesium compounds of calcium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/60—Inorganic bases or salts
- B01D2251/606—Carbonates
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Abstract
The invention discloses a limestone slurry pH value concentration fly-up detection system, a limestone slurry pH value concentration fly-up detection method, a limestone slurry pH value concentration fly-up control system and a desulfurization system, wherein the limestone slurry pH value fly-up detection system comprises a first-order inertia module, a second-order inertia module, a measurement deviation module and a height alarm module; the first-order inertia module carries out first filtering on the pH value measurement signal to obtain a first filtering value; the second first-order inertia module carries out second filtering on the pH value measurement signal to obtain a second filtering value; the measurement deviation module carries out deviation processing on the first filtering value and the second filtering value to obtain a deviation value; and the high-low alarm module obtains the change trend and the change quantity of the pH value according to the deviation value, judges the threshold value of the change quantity and outputs a flying detection result. When the real-time pH value signal is adopted to judge that the pH value signal is in a fly-up state, the current distortion signal can be eliminated, and the desulfurization control system can process the real-time pH value signal by using the fly-up detection judgment signal.
Description
Technical Field
The invention relates to the field of FGD (flue gas desulfurization) automatic control of a coal-fired power plant, in particular to a limestone slurry pH value concentration fly-rise detection system, a limestone slurry pH value concentration fly-rise detection method, a limestone slurry pH value concentration fly-rise control system and a limestone slurry FGD automatic control system.
Background
Sulfur dioxide (SO) 2 ) Mainly comes from the combustion process of coal, oil and natural gas, and is one of the main atmospheric pollutants. Thus controlling SO in coal-fired power plants 2 The emission being reduction of SO in the atmosphere 2 One of the main measures of content.
According to the emission standard of atmospheric pollutants of thermal power plants (GB13223-2011), in order to reduce the total pollutant emission of the coal-fired power plants, the emission standard of pollutants of the coal-fired power plants is looked at the emission standard of pollutants of the coal-fired power plants to the emission standard of gas turbines, namely: the emission limits of smoke, sulfur dioxide and nitrogen oxides are respectively 5mg/Nm3, 35mg/Nm3 and 50mg/Nm3, and the limit is generally defined as the standard of 'ultra-clean emission' of coal-fired boilers in the industry.
Reduction of SO 2 There are various methods of discharge. SO currently in common use 2 The control techniques are basically divided into three categories: "desulfurization before combustion, desulfurization during combustion, and desulfurization after combustion, i.e., Flue Gas Desulfurization (FGD).
Desulfurization before combustion refers to washing raw coal by a physical or chemical method to remove or reduce impurities such as sulfur, ash and the like in the raw coal. The adopted method comprises coal dressing, gasification, coal water slurry and briquette coal processing and the like. However, this method can only remove part of sulfur (mainly inorganic sulfur) in coal, and can not fundamentally solve SO 2 The pollution problem to the atmosphere; the desulfurization in the combustion refers to the injection of CaO/CaCO of lime into a hearth 3 Absorbent, thereby curing S0 2 /SO 3 The adopted method comprises the steps of spraying calcium in a furnace and desulfurizing by blending limestone with a fluidized bed; desulfurization after combustion, i.e. flue gas desulfurizationThe technology (FGD) is that a desulfurization device is additionally arranged at a tail flue of a boiler, and desulfurization is carried out on flue gas by utilizing a desulfurizer, and comprises a wet method and a dry method (semidry method) desulfurization process. Wherein: limestone-gypsum wet process is considered to be the current control of SO 2 The most effective way to discharge.
The existing desulfurization control system is a clean flue gas outlet SO of a coal-fired generating set 2 The concentration is a control target, and the pH value concentration of limestone slurry is simultaneously controlled in the limestone-gypsum wet desulphurization control SO as to control SO 2 Thereby controlling the degree of absorption of the clean flue gas outlet SO 2 The concentration meets the environmental protection requirement.
The pH value concentration of limestone slurry is needed to be used in the existing desulfurization control system, and the required opening degree of a limestone slurry valve is calculated, SO that the purified flue gas outlet SO after desulfurization is realized 2 And (4) controlling the content.
Analysis from the aspects of the operation status and the control logic: the automatic operation of the FGD desulfurization control system depends on the determination of the pH value concentration of limestone slurry.
Because the measuring device of lime stone thick liquid pH value concentration regularly washs (washs once every hour), lime stone thick liquid pH value concentration loses the authenticity, and control system can not correctly obtain the cleaning process, and the measured value rises by a wide margin, has influenced lime stone thick liquid pH value concentration measurement accuracy, causes desulfurization automatic control can't adapt to the pH value and change and put into automation.
Disclosure of Invention
In order to solve the problem of signal distortion caused by large-scale fly-up of the cleaning pH value, the invention provides a system and a method for detecting the fly-up of the pH value concentration of limestone slurry, a control system and a desulfurization system. The invention can ensure the normal work of the desulfurization control system PID after eliminating the distortion signal from the pH value signal in real time.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a limestone slurry pH value concentration fly-up detection system comprises: the system comprises a first-order inertia module, a second first-order inertia module, a measurement deviation module and a height alarm module;
the first order inertia module is used for carrying out first filtering on the pH value measurement signal to obtain a first filtering value;
the second first-order inertia module is used for carrying out second filtering on the pH value measurement signal to obtain a second filtering value;
the measurement deviation module is used for carrying out deviation processing on the first filtering value and the second filtering value to obtain a deviation value;
and the height alarm module is used for obtaining the change trend and the change quantity of the pH value according to the deviation value, judging the threshold value of the change quantity and outputting a flying detection result.
As a further improvement of the present invention, the transfer function formula of the first order inertia module is:
the transfer function formula of the second-order inertia module is as follows:
wherein G(s) characterizes the ratio of the Laplace transform of the linear system response input and output at zero initial condition; t1, T2 characterize the inertial time constant of the inertial element.
As a further improvement of the present invention, the inertia time T1 of the first order inertia module is 10s to 20 s; the inertia time T2 of the first order inertia module is 60 s-70 s.
As a further improvement of the invention, the system also comprises a fly-lift detection input switch and a fly-lift detection input confirmation module;
the flying detection input switch is used for giving the working state of the flying detection system;
and the flight lift detection input confirmation module is used for judging the validity of the flight lift detection result according to the flight lift detection result and the working state of the flight lift detection input switch.
A detection method of a limestone slurry pH value concentration fly-up detection system comprises the following steps:
carrying out first filtering on the pH value measurement signal to obtain a first filtering value;
carrying out second filtering on the pH value measurement signal to obtain a second filtering value;
carrying out deviation processing on the first filtering value and the second filtering value to obtain a deviation value;
and obtaining the change trend and the change quantity of the pH value according to the deviation value, judging the threshold value of the change quantity, and outputting a flight lift detection result.
As a further improvement of the invention, the method also comprises the following steps:
and judging the validity of the fly-lift detection result according to the working state of the fly-lift detection system and the fly-lift detection result.
The validity means that when the fly-lift detection switch is in a switch-in state and the fly-lift detection result output by the high-low alarm module is true, the output of the fly-lift detection control system is true; otherwise, the signal of the detected pH value is in a flying state, and the signal is distorted.
An FGD desulfurization automatic control system comprises a pH value measuring system, a desulfurization control system and a limestone slurry pH value concentration fly-up detection system;
the pH value measuring system is connected with the pH value measuring device and is used for obtaining a pH value measuring signal;
the limestone slurry pH value concentration fly-up detection system is used for judging whether a pH value measurement signal obtained by the pH value measurement device is in fly-up distortion or not;
the desulfurization control system is used for controlling SO according to the fly-up distortion result 2 The absorbent is controlled.
An FGD desulfurization system comprises a boiler descending section heat exchanger, a denitration ammonia injection grid, a denitration reactor, an air preheater, an electric dust remover, a desulfurization absorption tower, a chimney, a limestone slurry circulating pump, a pH value measuring device, a limestone new slurry supplementing pipeline and an FGD desulfurization automatic control system;
flue gas combusted by the boiler flows through the boiler descending section heat exchanger to reach a denitration ammonia injection grid, then is mixed with an injected ammonia-air mixture, enters a denitration reactor to carry out chemical reaction denitration, enters an air preheater to recover heat, and is discharged into the atmosphere through a chimney after passing through an electric precipitator and a desulfurization absorption tower;
the limestone slurry circulating pump is connected with a spraying device in the desulfurization absorption tower for limestone slurry; the pH value measuring device is arranged in limestone slurry in the desulfurization absorption tower and is electrically connected with the FGD desulfurization automatic control system; the limestone new slurry supplementing pipeline is communicated with the desulfurization absorption tower, and the FGD desulfurization automatic control system controls the on-off of the limestone new slurry supplementing pipeline.
As a further improvement of the invention, the chimney is also provided with clean flue gas SO 2 And (4) a measuring device.
Compared with the prior art, the PH value fly-up detection system provided by the invention has the advantages that PH value false distortion signals which are useless to a desulfurization control system and even interfere with the desulfurization control system can be automatically identified and eliminated, and a foundation can be laid for the desulfurization control system to be capable of realizing real-time online full-automatic detection.
According to the invention, two first-order inertia modules are adopted to filter the pH value measurement signal, carry out deviation processing, carry out threshold judgment on the variation, output a flying detection result, judge whether the pH value signal is distorted or not on the real-time pH value signal, and solve the problem that the pH value is unavailable due to the cleaning of the pH value measurement device. Because the pH value measuring device is cleaned regularly, the desulfurization control system can not obtain the cleaning information of the pH value measuring device, the pH value measuring signal can generate signal flying when the pH value measuring device is cleaned, the signal is distorted, the signal can not be used by the desulfurization control system, the pH value measuring value is greatly changed, the measuring accuracy and the corresponding time are influenced, the investment of the desulfurization control system is further influenced, and the environmental protection index controlled by the desulfurization system is influenced. When the real-time pH value signal is adopted to judge that the pH value signal is in a fly-up state, the current distortion signal can be eliminated, and the desulfurization control system can process the real-time pH value signal by using the fly-up detection judgment signal. The normal work of the desulfurization control system PID can be ensured after the distortion signal is removed from the real-time pH value signal.
Drawings
FIG. 1 is a block diagram of a pH fly-up detection system;
FIG. 2 is a schematic view of a pH measurement fly-lift detection system;
FIG. 3 is a flow diagram of a desulfurization system;
device and module code number description table in the figure:
1. a boiler descending section heat exchanger;
2. denitration ammonia injection grids;
3. a denitration reactor;
4. an air preheater;
5. an electric dust collector;
6. a desulfurization absorption tower;
7. a chimney;
8. clean flue gas SO 2 A measuring device;
9. a limestone slurry circulating pump;
10. limestone slurry pH value measuring device;
11. a limestone new slurry replenishing pipeline;
12. a LAG first order inertia module;
13. a LAG second first order inertia module;
an ON/OFF, fly-lift detection throw-in switch module;
ALARM and high-low ALARM module;
DEV, a measurement deviation module;
AND a flight detection input confirmation module.
Detailed Description
In order to make those skilled in the art better understand the technical solutions of the present invention, 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, not all of the embodiments, and do not limit the scope of the disclosure of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure. 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.
Various structural schematics according to the disclosed embodiments of the invention are shown in the drawings. The figures are not drawn to scale, wherein certain details are exaggerated and some details may be omitted for clarity of presentation. The shapes of the various regions, layers and their relative sizes, positional relationships are shown in the drawings as examples only, and in practice deviations due to manufacturing tolerances or technical limitations are possible, and a person skilled in the art may additionally design regions/layers with different shapes, sizes, relative positions, according to the actual needs.
In the context of the present disclosure, when a layer/element is referred to as being "on" another layer/element, it can be directly on the other layer/element or intervening layers/elements may be present. In addition, if a layer/element is "on" another layer/element in one orientation, then that layer/element may be "under" the other layer/element when the orientation is reversed.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in other sequences than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In view of the above problems, the utility model can not be applied to the desulfurization control of FGD because the pH value measuring device of limestone slurry is distorted due to the large-amplitude pH value-raising signal during the cleaning.
The invention provides a system for detecting pH value concentration fly-rise of limestone slurry, which comprises: the system comprises a first-order inertia module 12, a second first-order inertia module 13, a measurement deviation module DEV and a high-low ALARM module ALARM;
the first order inertia module 12 is configured to perform first filtering on the pH value measurement signal to obtain a first filtered value;
the second first-order inertia module 13 is configured to perform second filtering on the pH value measurement signal to obtain a second filtered value;
the deviation measuring module DEV is used for carrying out deviation processing on the first filtering value and the second filtering value to obtain a deviation value;
and the high-low ALARM module ALARM is used for obtaining the change trend and the change quantity of the pH value according to the deviation value, carrying out threshold judgment on the change quantity and outputting a flying detection result.
The limestone slurry pH value concentration fly-up detection system is positioned in DCS and between the pH value measurement system and the desulfurization control system. See figures 1 and 2.
The pH value measurement signal fly-up detection system comprises two links: the pH value deviation processing AND pH value alarming is that a first-order inertia module 12, a second-order inertia module 13, a deviation measuring module DEV, a high-low alarming module ALARM, a flying detection input switch ON/OFF AND a flying detection input confirming module AND form a flying detection control system. The above are key components of the fly-lift detection control system provided by the invention for desulfurization control.
The pH value flying detection control system provided by the invention is formed as shown in figure 1, and pH value measurement signals in a desulfurization absorption tower are obtained through a measurement device and are sent to a desulfurization control system for desulfurization control after being processed through a measurement link.
The transfer function formula of the first order inertia module 12 is:
the transfer function formula of the second first order inertia module 13 is:
wherein G(s) characterizes the ratio of the Laplace transform of the linear system response input and output at zero initial conditions; t1, T2 characterize the inertia time constant of the inertia element.
The pH value measurement signal enters a first-order inertia module 12, and the inertia time of the inertia module is between 10s and 20 s; the pH value measurement signal enters the second-order inertia module 13, and the inertia time of the inertia module is between 60s and 70 s.
The output of the first order inertia module 12 and the output of the second order inertia module 13 enter a measurement deviation module DEV; the output of the deviation measuring module DEV enters a high-low ALARM module ALARM, the high-low ALARM module ALARM detects the change trend and the change quantity of the current pH value, and once the change trend and the change quantity exceed a preset threshold value, the high-low ALARM module ALARM outputs a flying detection result. The result of the flying-up detection AND the ON/OFF state of the flying-up detection input switch enter the flying-up detection input confirmation means AND.
The invention also provides a detection method of the limestone slurry pH value concentration fly-up detection system, which comprises the following steps:
carrying out first filtering on the pH value measurement signal to obtain a first filtered value;
carrying out second filtering on the pH value measurement signal to obtain a second filtering value;
carrying out deviation processing on the first filtering value and the second filtering value to obtain a deviation value;
and obtaining the change trend and the change quantity of the pH value according to the deviation value, judging the threshold value of the change quantity, and outputting a flying rise detection result.
When the ON/OFF of the fly-lift detection switch is in an ON state and the high-low ALARM module ALARM outputs a fly-lift detection result as true, the output of the fly-lift detection control system is true. Otherwise, at this time, the signal for detecting the pH value is in a flying state, and the signal is distorted and unavailable.
The third purpose of the invention is to provide an automatic FGD desulfurization control system, which comprises a pH value measuring system, a desulfurization control system and a limestone slurry pH value concentration fly-up detection system;
the pH value measuring system is connected with the pH value measuring device and is used for obtaining a pH value measuring signal;
the limestone slurry pH value concentration fly-up detection system is used for judging whether a pH value measurement signal obtained by the pH value measurement device is in fly-up distortion or not;
the desulfurization control system is used for controlling SO according to the fly-up distortion result 2 The absorbent is controlled.
The pH value flying detection control system is positioned between the pH value measuring system and the desulfurization control system. And after the pH value measurement signal is sent out from the measurement system, the pH value measurement signal enters a fly-lift detection control system before entering desulfurization control. The fly-up detection control system detects the pH value measurement signal in real time on line, and once the fly-up phenomenon of the pH value measurement signal due to the cleaning of the measuring instrument is detected, the signal is distorted, and the distorted pH value measurement signal is not sent to the desulfurization control system.
The limestone slurry pH value concentration fly-up detection system plays a role when desulfurization control is put into automation, and the pH value measurement fly-up detection system generates a fly-up judgment signal of a pH value measurement signal. When the pH value measurement flying detection system judges that the measurement signal is in a flying state, the pH value signal entering the desulfurization control is in a distorted state, and the distorted signal can be removed.
The limestone slurry pH value concentration fly-up detection system has the function of judging the distorted pH value measurement of the pH value measurement device caused by cleaning, and forming the judgment of whether a pH value measurement signal is in fly-up distortion or not. The system comprises two links: a pH value deviation processing module and a pH value deviation alarm module. The system generates a reasonable pH value signal distortion judgment signal for the control of the desulfurization system, ensures reasonable desulfurization control quality and prevents the desulfurization control system from being fluctuated greatly.
The fourth purpose of the invention is to provide an FGD desulfurization system, which comprises a boiler descending section heat exchanger 1, a denitration ammonia injection grid 2, a denitration reactor 3, an air preheater 4, an electric dust remover 5, a desulfurization absorption tower 6, a chimney 7, a limestone slurry circulating pump 9, a pH value measuring device 10, a limestone new slurry supplementing pipeline 11 and the FGD desulfurization automatic control system;
a typical desulfurization system flow is shown in fig. 3, flue gas combusted by a boiler flows through a boiler descending section heat exchanger 1, reaches a denitration ammonia injection grid 2, is mixed with an injected ammonia-air mixture, enters a denitration reactor 3 for chemical reaction, enters an air preheater 4 for further recovering heat, passes through an electric dust collector 5 and a desulfurization absorption tower 6, and is discharged into the atmosphere through a chimney 7.
In the desulfurization absorption tower 6, limestone slurry is provided for spraying equipment of the absorption tower by a limestone slurry circulating pump 9, and the limestone slurry and SO in the original flue gas 2 Reacting and absorbing to remove most SO 2 . The limestone concentration of the limestone slurry is detected by the pH measuring device 10 and sent to the desulfurization control system of the DCS. When the pH value of the limestone slurry is higher, the absorption of SO in the limestone slurry is proved 2 Will be replenished through the limestone fresh slurry replenishing conduit 11.
The limestone slurry circulating pump 9 is connected with a spraying device in the desulfurization absorption tower 6 for limestone slurry; the pH value measuring device 10 is arranged in limestone slurry in the desulfurization absorption tower 6, and the pH value measuring device 10 is electrically connected with an FGD desulfurization automatic control system; the limestone new slurry supplementing pipeline 11 is communicated with the desulfurization absorption tower 6, and the FGD desulfurization automatic control system controls the on-off of the limestone new slurry supplementing pipeline 11. The chimney 7 is also provided with clean flue gas SO 2 A measuring device 8.
The design method of the pH value measurement signal flying detection system comprises the following steps: the pH value signal enters the DCS through the measuring signal system and passes through the pH value signal flying detection system before being sent to the desulfurization control system. And the fly-lift detection system detects the current pH value measurement signal in real time on line, and when the fly-lift trend is detected and the current pH value is judged to be in the fly-lift state, the current pH value signal is not adopted, and the numerical value before the fly-lift is used as the control quantity of the pH value and is sent to the desulfurization control system.
For example: the DEV module of the pH value signal flying detection system detects the deviation of a first-order inertia module 12 and a second-order inertia module 13 in real time, and an ALARM detection module ALARM outputs the diagnosis result information of signal flying according to a preset threshold (a judgment threshold is given according to an actually measured signal curve on site, a high-limit ALARM judgment value is set between 8 and 10 according to site experience, and a low-limit ALARM judgment value is set between-8 and-10).
The technical scheme is mainly characterized in that:
1. the real-time pH value signal is adopted to judge whether the pH value signal is distorted, so that the problem that the pH value is unavailable due to cleaning of a pH value measuring device is solved. Because the pH value measuring device is cleaned regularly, the desulfurization control system can not obtain the cleaning information of the pH value measuring device, the pH value measuring signal can generate signal flying when the pH value measuring device is cleaned, the signal is distorted, the signal can not be used by the desulfurization control system, the pH value measuring value is greatly changed, the measuring accuracy and the corresponding time are influenced, the investment of the desulfurization control system is further influenced, and the environmental protection index controlled by the desulfurization system is influenced.
2. When the real-time pH value signal is adopted to judge that the pH value signal is in a fly-up state, the current distortion signal can be eliminated, and the desulfurization control system can process the real-time pH value signal by using the fly-up detection judgment signal. And after the distortion signal is removed from the real-time pH value signal, the normal work of a desulfurization control system PID can be ensured.
3. When the real-time pH value signal is adopted to judge that the pH value signal is in a fly-up state, the limestone slurry supply valve can be accurately controlled, the valve is prevented from exiting an automatic operation state due to large distortion and opening and closing of the pH value signal, and the desulfurization control system can stably operate.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (5)
1. The utility model provides a lime stone thick liquid pH value concentration fly-lift detecting system which characterized in that includes: the system comprises a first-order inertia module (12), a second-order inertia module (13), a measurement deviation module (DEV) and an ALARM module (ALARM);
the first order inertia module (12) is used for carrying out first filtering on the pH value measurement signal to obtain a first filtering value;
the second first-order inertia module (13) is used for carrying out second filtering on the pH value measurement signal to obtain a second filtering value;
the deviation measuring module (DEV) is used for carrying out deviation processing on the first filtering value and the second filtering value to obtain a deviation value;
the high-low ALARM module (ALARM) is used for obtaining the change trend and the change quantity of the pH value according to the deviation value, carrying out threshold judgment on the change quantity and outputting a flight-rise detection result;
the first-order inertia module (12) and the second first-order inertia module (13) are arranged in parallel;
the transfer function formula of the first order inertia module (12) is as follows:
；
the transfer function formula of the second first order inertia module (13) is as follows:
；
wherein G(s) characterizes the ratio of the Laplace transform of the linear system response input and output at zero initial condition; t1 and T2 represent inertia time of the inertia link;
the inertia time T1 of the first-order inertia module (12) is 10 s-20 s; the inertia time T2 of the first-order inertia module (12) is 60 s-70 s;
the system also comprises a flying detection input switch (ON/OFF) AND a flying detection input confirmation module (AND);
the flying detection input switch (ON/OFF) is used for providing the working state of the flying detection system;
AND the flying detection input confirmation module (AND) is used for judging the validity of the flying detection result according to the flying detection result AND the working state of a flying detection input switch (ON/OFF).
2. A detection method of a limestone slurry pH value concentration fly-up detection system is based on the limestone slurry pH value concentration fly-up detection system of claim 1, and is characterized by comprising the following steps:
carrying out first filtering on the pH value measurement signal to obtain a first filtered value;
carrying out second filtering on the pH value measurement signal to obtain a second filtering value;
carrying out deviation processing on the first filtering value and the second filtering value to obtain a deviation value;
obtaining the change trend and the change quantity of the pH value according to the deviation value, carrying out threshold judgment on the change quantity, and outputting a fly-up detection result;
further comprising:
judging the validity of the fly-lift detection result according to the working state of the fly-lift detection system and the fly-lift detection result;
the validity means that when a flying lift detection switch (ON/OFF) is in a switching state and a high-low ALARM module (ALARM) outputs a flying lift detection result to be true, the output of a flying lift detection control system is true; otherwise, the signal for detecting the pH value is in a flying state, and the signal is distorted.
3. An automatic FGD desulfurization control system, which is characterized by comprising a pH value measuring system, a desulfurization control system and a limestone slurry pH value concentration fly-up detection system of claim 1;
the pH value measuring system is connected with the pH value measuring device and is used for obtaining a pH value measuring signal;
the limestone slurry pH value concentration fly-up detection system is used for judging whether a pH value measurement signal obtained by the pH value measurement device is in fly-up distortion or not;
the desulfurization control system is used for controlling SO according to the fly-up distortion result 2 The absorbent is controlled.
4. An FGD desulfurization system is characterized by comprising a boiler descending section heat exchanger (1), a denitration ammonia-spraying grid (2), a denitration reactor (3), an air preheater (4), an electric dust remover (5), a desulfurization absorption tower (6), a chimney (7), a limestone slurry circulating pump (9), a pH value measuring device (10), a limestone new slurry supplementing pipeline (11) and the FGD desulfurization automatic control system of claim 3;
flue gas combusted by the boiler flows through the boiler descending section heat exchanger (1) to reach the denitration ammonia injection grid (2), then is mixed with an injected ammonia-air mixture, enters the denitration reactor (3) for chemical reaction denitration, enters the air preheater (4) for recovering heat, passes through the electric dust collector (5) and the desulfurization absorption tower (6), and is discharged into the atmosphere through the chimney (7);
the limestone slurry circulating pump (9) is connected with spraying equipment in the limestone slurry supply desulfurization absorption tower (6); the pH value measuring device (10) is arranged in limestone slurry in the desulfurization absorption tower (6), and the pH value measuring device (10) is electrically connected with an FGD desulfurization automatic control system; the limestone new slurry supplementing pipeline (11) is communicated with the desulfurization absorption tower (6), and the FGD desulfurization automatic control system controls the on-off of the limestone new slurry supplementing pipeline (11).
5. A FGD desulfurization system according to claim 4, characterized in that the stack (7) is further provided with clean flue gas SO 2 A measuring device (8).
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Application publication date: 20210112 Assignee: Huaneng Longdong Energy Co.,Ltd. Zhengning Power Plant Assignor: Xi'an Thermal Power Research Institute Co.,Ltd. Contract record no.: X2023980052171 Denomination of invention: Limestone slurry pH concentration soaring detection system, method, control system, and desulfurization system Granted publication date: 20220819 License type: Common License Record date: 20231213 |
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