CN116588899A - Online self-control method and system for sodium hypochlorite production - Google Patents
Online self-control method and system for sodium hypochlorite production Download PDFInfo
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- CN116588899A CN116588899A CN202310699656.6A CN202310699656A CN116588899A CN 116588899 A CN116588899 A CN 116588899A CN 202310699656 A CN202310699656 A CN 202310699656A CN 116588899 A CN116588899 A CN 116588899A
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- 239000005708 Sodium hypochlorite Substances 0.000 title claims abstract description 145
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 title claims abstract description 145
- 238000000034 method Methods 0.000 title claims abstract description 52
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 50
- 238000001514 detection method Methods 0.000 claims abstract description 111
- 239000003513 alkali Substances 0.000 claims abstract description 97
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 84
- 239000000460 chlorine Substances 0.000 claims abstract description 84
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 83
- 238000002329 infrared spectrum Methods 0.000 claims abstract description 77
- 238000005259 measurement Methods 0.000 claims abstract description 62
- 239000012295 chemical reaction liquid Substances 0.000 claims abstract description 59
- 238000004458 analytical method Methods 0.000 claims abstract description 36
- 238000006243 chemical reaction Methods 0.000 claims description 88
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 42
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 24
- 239000011734 sodium Substances 0.000 claims description 24
- 229910052708 sodium Inorganic materials 0.000 claims description 24
- 238000012795 verification Methods 0.000 claims description 16
- 238000012937 correction Methods 0.000 claims description 15
- 238000002835 absorbance Methods 0.000 claims description 11
- 230000003247 decreasing effect Effects 0.000 claims description 2
- NWZSZGALRFJKBT-KNIFDHDWSA-N (2s)-2,6-diaminohexanoic acid;(2s)-2-hydroxybutanedioic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O.NCCCC[C@H](N)C(O)=O NWZSZGALRFJKBT-KNIFDHDWSA-N 0.000 abstract description 29
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 abstract description 29
- 239000002994 raw material Substances 0.000 abstract description 13
- 239000012458 free base Substances 0.000 abstract description 11
- 239000000243 solution Substances 0.000 description 22
- 238000001228 spectrum Methods 0.000 description 8
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 4
- 239000004202 carbamide Substances 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000004088 foaming agent Substances 0.000 description 3
- 230000008676 import Effects 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- ULUZGMIUTMRARO-UHFFFAOYSA-N (carbamoylamino)urea Chemical compound NC(=O)NNC(N)=O ULUZGMIUTMRARO-UHFFFAOYSA-N 0.000 description 2
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 238000002790 cross-validation Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 238000012549 training Methods 0.000 description 2
- 238000002479 acid--base titration Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000004071 biological effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 229910001902 chlorine oxide Inorganic materials 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000010200 validation analysis Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B11/00—Oxides or oxyacids of halogens; Salts thereof
- C01B11/04—Hypochlorous acid
- C01B11/06—Hypochlorites
- C01B11/062—Hypochlorites of alkali metals
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/359—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using near infrared light
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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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/02—Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
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- Chemical & Material Sciences (AREA)
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- Life Sciences & Earth Sciences (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Inorganic Chemistry (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
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Abstract
The application relates to an online self-control method and system for sodium hypochlorite production, which are used for detecting the near infrared spectrum of a reaction liquid in a bypass pipeline and obtaining a predicted value of free alkali content and a predicted value of available chlorine content through a near infrared spectrum analysis method; fitting the predicted value of the free alkali content with a first measurement model to obtain an online detection value of the free alkali content of the reaction liquid; fitting the predicted value of the available chlorine content with a second measurement model to obtain an online detection value of the available chlorine content of the reaction liquid; sodium hypochlorite product is produced when the free base content is between 11.35% and 11.54% on-line. The method can be used for detecting the free alkali content and the effective chlorine content of the obtained reaction liquid on line in real time, and avoids the existence of certain time hysteresis caused by manual detection, so that the process parameters can be adjusted in real time, the detection accuracy of the method is high, and the free alkali content and the effective chlorine content in the finally produced sodium hypochlorite can meet the raw material requirement of producing hydrazine hydrate.
Description
Technical Field
The application relates to the technical field of sodium hypochlorite production, in particular to an online self-control method and system for sodium hypochlorite production.
Background
The first country of world foaming agent production mainly adopts a urea method to produce the foaming agent, firstly, chlorine gas reacts with alkali to generate sodium hypochlorite, then urea reacts with the sodium hypochlorite in alkaline solution to obtain hydrazine hydrate, the obtained hydrazine hydrate is refined, the refined hydrazine hydrate and urea undergo condensation reaction under an acidic environment to obtain intermediate biurea, and finally the biurea and the chlorine gas undergo oxidation reaction to prepare the foaming agent.
In the prior art, alkali and chlorine are generally used for reaction to generate sodium hypochlorite, and the generated sodium hypochlorite is used for producing hydrazine hydrate. Because the free alkali content and the effective chlorine content in the sodium hypochlorite greatly influence the production yield of the hydrazine hydrate, when the raw material sodium hypochlorite for producing the hydrazine hydrate is produced, the detection of the free alkali content and the effective chlorine content is needed, and the sodium hypochlorite production process parameters are adjusted according to the detection result, so that the free alkali content and the effective chlorine content in the finally produced sodium hypochlorite meet the raw material requirement for producing the hydrazine hydrate.
At present, in the continuous sodium hypochlorite production process of a sodium hypochlorite reaction tower, a sample is manually extracted from the sodium hypochlorite reaction tower and is subjected to acid-base titration, so that the sample is subjected to free alkali content and effective chlorine content detection in a measuring cup, a certain time is required in the detection process, then, according to a detection result, a certain time hysteresis exists, the detection result of the free alkali content and the effective chlorine content cannot be obtained on line in real time, the sodium hypochlorite production process parameter cannot be adjusted in time, the manual detection error is large, the detection result is inaccurate, the free alkali content and the effective chlorine content in the finally produced sodium hypochlorite cannot meet the raw material requirement for producing hydrazine hydrate, and the production yield of the hydrazine hydrate in a subsequent process is seriously affected. Meanwhile, a certain potential safety hazard exists in manually extracting a sample from the sodium hypochlorite reaction tower.
Disclosure of Invention
Based on the above, it is necessary to solve the problems that in the prior art, the detection results of the free alkali content and the effective chlorine content cannot be obtained on line in real time, so that the sodium hypochlorite production process parameters cannot be adjusted in time, and the manual detection error is large, so that the free alkali content and the effective chlorine content in the finally produced sodium hypochlorite cannot meet the raw material requirements for producing hydrazine hydrate, the production yield of the hydrazine hydrate in the subsequent process is seriously affected, and meanwhile, a certain potential safety hazard exists in the manual extraction of a sample from a sodium hypochlorite reaction tower. The online self-control method and system for sodium hypochlorite production can detect the free alkali content and the effective chlorine content of the obtained reaction liquid in real time and online, avoid the existence of a certain time hysteresis caused by manual detection, and accordingly adjust the process parameters in real time.
An online self-control method for sodium hypochlorite production comprises the following steps:
s10, introducing sodium hydroxide solution into a sodium hypochlorite reaction tower from the tower top according to a preset flow, and introducing enough chlorine into the sodium hypochlorite reaction tower from the tower bottom;
s20, obtaining a reaction solution from the bottom of the sodium hypochlorite reaction tower, introducing the reaction solution into the sodium hypochlorite reaction tower from the top of the sodium hypochlorite reaction tower through a circulating pipeline, wherein the circulating pipeline is connected with a bypass pipeline, the head end and the tail end of the bypass pipeline are connected with the circulating pipeline, detecting the near infrared spectrum of the reaction solution in the bypass pipeline, and obtaining a predicted value of free alkali content and a predicted value of effective chlorine content through a near infrared spectrum analysis method;
s30, fitting the predicted value of the free alkali content with a first measurement model to obtain an online detection value of the free alkali content of the reaction liquid; fitting the predicted value of the available chlorine content with a second measurement model to obtain an online detection value of the available chlorine content of the reaction liquid;
s40, when the content of the free alkali is between 11.35% and 11.54%, sodium hypochlorite products are extracted from the circulating pipeline.
Preferably, in the above-mentioned online self-control method for sodium hypochlorite production, before the step S10, the method further includes the following steps:
s01, preparing a plurality of sodium hypochlorite samples with different concentrations, and respectively detecting near infrared spectrums of the sodium hypochlorite samples;
s02, obtaining a free alkali content analysis value of each sodium hypochlorite sample through a near infrared spectrum analysis method, and obtaining a first correction set for establishing a model; obtaining an effective chlorine content analysis value of each sodium hypochlorite sample through a near infrared spectrum analysis method, and obtaining a second correction set for establishing a model;
s03, detecting a free alkali content detection value of each sodium hypochlorite sample through physicochemical analysis to obtain a first verification set for verifying the prediction capacity of the model; detecting the effective chlorine content detection value of each sodium hypochlorite sample through physicochemical analysis to obtain a second verification set for verifying the prediction capability of the model;
s04, fitting the first correction set with the first verification set to establish the first measurement model, and fitting the second correction set with the second verification set to establish the second measurement model.
Preferably, in the above-mentioned online self-control method for sodium hypochlorite production, the acquisition conditions of the near infrared spectrum are as follows: the wavelength ranges from 950nm to 1650nm, the resolution is 2nm, the absorbance noise is less than 0.00005AU, and the wavelength temperature drift is less than 0.005 nm/DEG C.
Preferably, in the sodium hypochlorite production online self-control method, R of the first measurement model and R of the second measurement model 2 Greater than 0.9, the RMSECV of the first measurement model is less than or equal to 0.1, and the RMSECV of the second measurement model is less than or equal to 0.1.
Preferably, in the above-mentioned online self-control method for sodium hypochlorite production, the step S50 further includes the following steps:
and when the online detection value of the free alkali content is smaller than 11.35%, controlling the preset flow to be increased, and when the online detection value of the free alkali content is larger than 11.54%, controlling the preset flow to be decreased so as to keep the online detection value of the free alkali content of the reaction liquid between 11.35% and 11.54%.
The utility model provides an online autonomous system of sodium hypochlorite production, includes near infrared spectrum analyzer, controlling means and a plurality of sodium hypochlorite reaction unit, sodium hypochlorite reaction unit includes sodium hypochlorite reaction tower, circulation pipeline, bypass pipeline and finished product pipeline, sodium hydroxide pipeline is connected to the top of the tower import of sodium hypochlorite reaction tower, and is provided with first automatically controlled flow valve, the bottom of the tower access connection of sodium hypochlorite reaction tower has chlorine pipeline, and is provided with second automatically controlled flow valve, the export of sodium hypochlorite reaction tower with the one end of circulation pipeline links to each other, the other end with the top of the tower import links to each other, bypass pipeline end to end all with the circulation pipeline links to each other, just the last third automatically controlled flow valve that has set gradually of bypass pipeline near infrared spectrum analyzer and check valve, the last fourth automatically controlled flow valve that is provided with of finished product pipeline, the one end of finished product pipeline with circulation pipeline links to each other, and is located between the bypass pipeline tail end with the top of the tower import, near infrared spectrum analyzer first automatically controlled flow valve second automatically controlled flow valve third automatically controlled flow valve and fourth automatically controlled flow valve are all connected with the electrically controlled control device.
Preferably, in the online automatic control system for sodium hypochlorite production, the plurality of sodium hypochlorite reaction units include a first sodium reaction unit and a second sodium reaction unit, and the control device controls the third electric control flow valve of the first sodium reaction unit and the third electric control flow valve of the second sodium reaction unit to be opened intermittently and alternately according to 0.1Hz to 0.2Hz, so that the first sodium reaction unit and the second sodium reaction unit share one near infrared spectrum analyzer.
Preferably, in the above-mentioned online automatic control system for sodium hypochlorite production, the bypass pipeline is vertically disposed, and in the bypass pipeline, a flow direction of the sodium hypochlorite reaction liquid is vertically upward.
Preferably, in the above-mentioned online automatic control system for sodium hypochlorite production, the configuration parameters of the near infrared spectrum analyzer are: the wavelength ranges from 950nm to 1650nm, the resolution is 2nm, the absorbance noise is less than 0.00005AU, and the wavelength temperature drift is less than 0.005 nm/DEG C.
The technical scheme adopted by the application can achieve the following beneficial effects:
according to the sodium hypochlorite production online self-control method and system disclosed by the embodiment of the application, a reaction liquid (generated sodium hypochlorite solution) can be detected in real time through a near infrared spectrum analysis method, a real-time near infrared spectrum can be obtained, a free alkali content predicted value and an effective chlorine content predicted value of the reaction liquid can be obtained in real time through the real-time near infrared spectrum, then the free alkali content predicted value and a first measurement model are fitted, the free alkali content online detection value of the reaction liquid at the moment, namely the real-time free alkali content of the reaction liquid, and simultaneously, the effective chlorine content predicted value and a second measurement model are fitted, so that the effective chlorine content of the reaction liquid, namely the real-time effective chlorine content of the reaction liquid at the moment, can be detected online in real time, so that the free alkali content and the effective chlorine content of the reaction liquid can be obtained, when the free alkali content online detection value is between 11.35% and 11.54%, sodium hypochlorite products are extracted from a circulation pipeline, and sodium hypochlorite meeting the requirements of producing hydrazine raw materials is obtained, otherwise, the online adjustment of technological parameters is carried out until the free alkali content detection value is between 11.35% and 11.54%. The method can be used for detecting the free alkali content and the effective chlorine content of the obtained reaction liquid on line in real time, so that the existence of certain time hysteresis caused by manual detection is avoided, the process parameters can be adjusted in real time, the detection accuracy of the detection in the mode is high, the inaccuracy of the detection result caused by human factors in the manual detection process is avoided, the free alkali content and the effective chlorine content in the finally produced sodium hypochlorite can meet the raw material requirement of hydrazine hydrate production, and the influence on the production yield of the hydrazine hydrate in the subsequent process is prevented. Meanwhile, the method replaces manual detection, so that the manual labor intensity and the workload can be reduced.
Drawings
Fig. 1 is a schematic diagram of an online automatic control system for sodium hypochlorite production, wherein a broken line in the diagram is an electric control connecting line;
fig. 2 is a schematic diagram of an online automatic control system for sodium hypochlorite production according to another embodiment of the present application, wherein a dotted line is an electric control connection line;
FIG. 3 is a near infrared spectrum of a plurality of sodium hypochlorite samples obtained in step S01 of the present application;
FIG. 4 is a first measurement model constructed in accordance with an embodiment of the present application;
FIG. 5 is a second measurement model constructed in accordance with an embodiment of the present application;
FIG. 6 is a near infrared spectrum corresponding to the on-line detection data in the verification example of the present application;
FIG. 7 is a graph showing the comparison of on-line test data and laboratory data in an example of the present application;
fig. 8 is a schematic diagram of the random detection of the present application during sodium hypochlorite production.
Description of the drawings: the sodium hypochlorite reaction tower 100, a sodium hydroxide pipeline 110, a first electric control flow valve 120, a chlorine pipeline 130, a second electric control flow valve 140, a circulation tank 210, a finished product tank 220, a circulation pipeline 310, a bypass pipeline 320, a third electric control flow valve 321, a check valve 322, a finished product pipeline 330, a fourth electric control flow valve 331, a near infrared spectrum analyzer 400 and a control device 500.
Detailed Description
In order that the application may be readily understood, a more particular description of the application will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Preferred embodiments of the present application are shown in the examples. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," "top," "bottom," "top," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1 to 2, an embodiment of the application discloses an online self-control method for sodium hypochlorite production, which comprises the following steps:
s10, introducing sodium hydroxide solution into the sodium hypochlorite reaction tower 100 from the top of the tower according to a preset flow, and introducing enough chlorine into the sodium hypochlorite reaction tower 100 from the bottom of the tower;
the sodium hydroxide solution reacts with chlorine gas in the sodium hypochlorite reaction tower 100 to produce a sodium hypochlorite solution, wherein sodium hypochlorite is called available chlorine, and sodium hydroxide is called free base.
S20, obtaining a reaction solution (generated sodium hypochlorite solution) from the bottom of the sodium hypochlorite reaction tower 100, introducing the reaction solution into the sodium hypochlorite reaction tower 100 from the top of the tower through a circulating pipeline 310, connecting the circulating pipeline 310 with a bypass pipeline 320, connecting the front end and the tail end of the bypass pipeline 320 with the circulating pipeline 310, detecting the near infrared spectrum of the reaction solution in the bypass pipeline 320, and performing a near infrared spectrum analysis method (near infrared spectrum analysis, namely, utilizing the characteristic that substances containing hydrogen groups such as C-H, N-H, O-H in substances absorb the near infrared light more strongly, performing qualitative and quantitative analysis and measurement on relative characteristics (such as physical, chemical and biological properties), specifically, using a near infrared spectrometer to pass the near infrared light beam through a sample, measuring the absorbance of the sample at different wavelengths, generating a spectrum, and analyzing the spectrum by comparing the spectrum of the sample with a standard spectrum, thereby determining the components and characteristics of the sample. The near infrared spectrum shown in fig. 8 is analyzed by a near infrared spectrum analysis method (compared with a standard spectrum), and the free alkali content predicted value and the effective chlorine content predicted value can be obtained by comparing and analyzing according to the frequency band and the absorbance different from the absorbance of the standard spectrum.
S30, fitting the predicted value of the free alkali content with a first measurement model (as shown in fig. 4) to obtain an online detection value of the free alkali content of the reaction liquid; fitting the predicted value of the available chlorine content with a second measurement model (as shown in figure 5) to obtain an online detection value of the available chlorine content of the reaction liquid;
s40. sodium hypochlorite product is withdrawn from circulation line 310 when the free base content is between 11.35% and 11.54% on-line (when the available chlorine content is around 9.2%).
Specifically (by way of example), during the sodium hypochlorite production process, the near infrared spectrum of the reaction liquid in the bypass pipeline 320 is randomly detected, and a near infrared spectrum chart shown in fig. 8 is obtained at the same time, the near infrared spectrum chart shown in fig. 8 is analyzed by adopting a near infrared spectrum analysis method (compared with a standard spectrum chart), and the comparison analysis is carried out according to the frequency band and the absorbance different from the absorbance of the standard spectrum chart, so that the predicted value of the free alkali content is 11.81%, and the predicted value of the available chlorine content is 8.89%. Then, the predicted value of the free alkali content of 11.81% is fitted to the first measurement model (as shown in fig. 4) (substituted into the abscissa), and the value corresponding to the ordinate at the moment is the online detection value of the free alkali content, so that the online detection value of the free alkali content of the reaction liquid at the moment is 11.87%, which means that the free alkali content of the reaction liquid at the moment is 11.87%. And (3) carrying out (substituting into an abscissa) a predicted value of the effective chlorine content of 8.89% and a second measurement model (shown in figure 5), wherein the value corresponding to the ordinate at the moment is an online detection value of the effective chlorine content, so that the online detection value of the effective chlorine content of the reaction liquid at the moment is 8.83%, which means that the effective chlorine content of the reaction liquid at the moment is 8.83%.
As the free alkali content in the reaction liquid is 11.89% and is not between 11.35% and 11.54%, the reaction liquid can not meet the raw material requirement for producing hydrazine hydrate at the moment, and the process parameter adjustment is needed.
In the online self-control method for sodium hypochlorite production disclosed by the embodiment of the application, a reaction liquid (generated sodium hypochlorite solution) can be detected in real time through a near infrared spectrum analysis method, a real-time near infrared spectrum can be obtained, a predicted value of free alkali content and a predicted value of effective chlorine content of the reaction liquid at the moment can be obtained in real time through the real-time near infrared spectrum, and then the predicted value of the free alkali content is fitted with a first measurement model, so that an online detection value of the free alkali content of the reaction liquid at the moment, namely the real-time free alkali content of the reaction liquid at the moment is obtained; and simultaneously, fitting the predicted value of the available chlorine content with a second measurement model to obtain an online detection value of the available chlorine content of the reaction liquid. Namely, the real-time effective chlorine content of the reaction liquid can be detected on line in real time to obtain the free alkali content and the effective chlorine content of the reaction liquid, when the on-line detection value of the free alkali content is between 11.35 and 11.54 percent, sodium hypochlorite products are extracted from the circulating pipeline 310 to obtain sodium hypochlorite meeting the requirement of producing hydrazine hydrate raw materials, otherwise, the process parameters are adjusted until the on-line detection value of the free alkali content is between 11.35 and 11.54 percent. The method can be used for detecting the free alkali content and the effective chlorine content of the obtained reaction liquid on line in real time, so that the existence of certain time hysteresis caused by manual detection is avoided, the process parameters can be adjusted in real time, the detection accuracy of the detection in the mode is high, the inaccuracy of the detection result caused by human factors in the manual detection process is avoided, the free alkali content and the effective chlorine content in the finally produced sodium hypochlorite can meet the raw material requirement of hydrazine hydrate production, and the influence on the production yield of the hydrazine hydrate in the subsequent process is prevented. Meanwhile, the method replaces manual detection, so that the manual labor intensity and the workload can be reduced.
Examples: the 24% sodium hydroxide solution is stirred at a pressure of 0.4MPa and a concentration of 10m 3 Flow rate/h and speed up to 30m at 100% 3 /h (i.e. initial flow of 10m 3 And/h, the speed is 100%, and the final flow rate is 30m 3 /h, 2 hours. ) Introducing enough 96% chlorine gas from the tower top into the sodium hypochlorite reaction tower 100 at a pressure of 0.09MPa from the tower bottom, detecting the near infrared spectrum of the reaction liquid in the bypass pipeline 320 at intervals of 20 minutes, obtaining a predicted free alkali content value and a predicted effective chlorine content value through a near infrared spectrum analysis method, fitting the predicted free alkali content value with a first measurement model to obtain an online detection value of the free alkali content of the reaction liquid, fitting the predicted effective chlorine content value with a second measurement model to obtain an online detection value of the effective chlorine content of the reaction liquid, simultaneously, opening a sampling port on the bypass pipeline 320, sampling a sample while detecting the near infrared spectrum of the reaction liquid in the bypass pipeline 320 each time, synthesizing hydrazine hydrate with urea and sodium hydroxide in a ratio of 1:1.2:2.2 in a laboratory, and detecting the yield after each time of hydrazine hydrate synthesis to obtain the following table:
| batch of | Free base content | Yield of hydrazine hydrate |
| 1 (20 minutes) | 10.63％ | 70.1％ |
| 2 (40 minutes) | 10.91％ | 72.4％ |
| 3 (60 minutes) | 11.29％ | 74.8％ |
| 4 (80 minutes) | 11.57％ | 74.6％ |
| 5 (100 minutes) | 11.88％ | 71.6％ |
| 6 (120 minutes) | 12.16％ | 68.4％ |
As can be seen from the above table, the free alkali content in sodium hypochlorite has a great influence on the yield of hydrazine hydrate, and when the free alkali content in sodium hypochlorite is between 11.29% and 11.57%, the yield of hydrazine hydrate can reach more than 74.5%, so that the preferred content of free alkali is controlled between 11.35% and 11.54%, and the yield of hydrazine hydrate produced by the sodium hypochlorite is high in the subsequent production of hydrazine hydrate.
In the method, it is important to establish a first measurement model and a second measurement model, and optionally, before the step S10, the method further includes the following steps:
s01, preparing a plurality of sodium hypochlorite samples with different concentrations, and respectively detecting near infrared spectrums of the sodium hypochlorite samples (shown in figure 3);
s02, obtaining a free alkali content analysis value of each sodium hypochlorite sample through a near infrared spectrum analysis method, and obtaining a first correction set for establishing a model; obtaining an effective chlorine content analysis value of each sodium hypochlorite sample through a near infrared spectrum analysis method, and obtaining a second correction set for establishing a model;
s03, detecting the free alkali content detection value of each sodium hypochlorite sample by physicochemical analysis (such as a laboratory manual detection mode in the prior art), and obtaining a first verification set for verifying the prediction capability of the model; detecting the effective chlorine content detection value of each sodium hypochlorite sample through physical and chemical analysis (such as laboratory detection in the prior art), and obtaining a second verification set for verifying the prediction capability of the model;
s04, a first measurement model is built through fitting of a first correction set and a first verification set (shown in fig. 4), and a second measurement model is built through fitting of a second correction set and a second verification set (shown in fig. 5).
The first measurement model and the second measurement model are built by means of cross-validation, the basic idea of which is to divide the samples a number of times, each time using part of the samples (correction set) for training the model and the rest of the samples (validation set) for testing the model until all the samples are used for both training and testing, and then to combine all the results for estimating the generalization error.
By the method, a first measurement model and a second measurement model can be established. Fitting the predicted value of the free alkali content (the predicted value of the free alkali content is obtained by detecting the near infrared spectrum of the reaction liquid in the bypass pipeline 320 and adopting a near infrared spectrum analysis method) with a first measurement model to obtain an online detection value of the free alkali content of the reaction liquid; the predicted value of the available chlorine content (obtained by detecting the near infrared spectrum of the reaction liquid in the bypass pipeline 320 and adopting a near infrared spectrum analysis method) is fitted with a second measurement model (as shown in fig. 5) to obtain an online detection value of the available chlorine content of the reaction liquid, so that the free alkali content and the available chlorine content of the reaction liquid can be detected online in real time.
In order to improve the accuracy of the first and second measurement models, optionally R of the first and second measurement models 2 (R 2 Parameter estimation is carried out by adopting a least square method, R 2 The ratio of the regression square sum to the total dispersion square sum is expressed as the ratio of the total dispersion square sum which can be explained by the regression square sum, and the larger the ratio is, the better the model is, and the more accurate the regression effect is. R is R 2 The closer to 1 between 0 and 1, the better the regression fit, the higher the model goodness of fit exceeding 0.8 is generally considered. R is R 2 Is a statistic that measures the predictive power of the regression model. The larger the value, the stronger the predictive power of the model, wherein 0 indicates that the model cannot interpret the change of the target variable, and 1 indicates that the model can fully interpret the change of the target variable. ) Above 0.9, the RMSECV of the first measurement model (when cross-validation is performed, the generalization error of the calibration model is usually estimated according to the size of the RMSECV, and RMSECV is often used to characterize the quality of the calibration model, where smaller RMSECV indicates higher accuracy of analysis of the element content of the test set sample by the calibration model. ) And 0.1 or less, and the RMSECV of the second measurement model is 0.1 or less.
In the application, the first measurement model is verified in the process of establishing the first correction set and the first verification set, and the second measurement model is verified in the process of establishing the second correction set and the second verification set, so that the modeling effect of the following table is obtained;
| detection index | Model | R 2 | RMSECV |
| Available chlorine | Second measurement model | 0.999 | 0.09 |
| Free base | First measurement model | 0.999 | 0.10 |
As can be seen from the above table, R of the first measurement model 2 And RMSECV meets the above requirements, by R 2 And RMSECV characterizes the accuracy of the fit of the first and second measurement models, it can be seen that R of the first and second measurement models 2 The values (meeting the requirement of more than 0.9) are all close to 1, which means that the model fitting goodness is relatively high, the RMSECV of the first measurement model is equal to 0.1 (meeting the requirement of less than or equal to 0.1), the RMSECV of the second measurement model is equal to 0.09 (meeting the requirement of less than or equal to 0.1), and the analysis accuracy of the analysis of the element content in the sample by the model is relatively high, so that the accuracy of the first measurement model and the second measurement model can be improved.
Preferably, the acquisition conditions of the near infrared spectrum are: the wavelength ranges from 950nm to 1650nm, the resolution is 2nm, the absorbance noise is less than 0.00005AU, the wavelength temperature drift is less than 0.005 nm/DEG C, and the accuracy of near infrared spectrum detection on sodium hypochlorite under the condition is high.
Verification example: the 24% sodium hydroxide solution was subjected to a pressure of 0.4MPa and a pressure of 20.9m 3 And (3) introducing the flow rate of/h into the sodium hypochlorite reaction tower 100 from the tower top, introducing 96% chlorine gas in a sufficient quantity from the tower bottom to the sodium hypochlorite reaction tower 100 at a pressure of 0.09MPa, detecting the near infrared spectrum of the reaction liquid in the bypass pipeline 320 for a plurality of times at intervals of 30 minutes (as shown in figure 6), obtaining a predicted free alkali content value and a predicted effective chlorine content value through a near infrared spectrum analysis method, fitting the predicted free alkali content value with a first measurement model to obtain a free alkali content online detection value of the reaction liquid, which is a free alkali online detection value set, and fitting the predicted effective chlorine content value with a second measurement model to obtain an online effective chlorine content detection value of the reaction liquid, which is an online effective chlorine detection value set.
Meanwhile, a sampling port is formed in the bypass pipeline 320, an off-line sample is taken while the near infrared spectrum of the reaction liquid in the bypass pipeline 320 is detected each time, and the off-line sample is detected in a laboratory to obtain an off-line detection value set of free alkali and an off-line detection value set of available chlorine.
Comparing and fitting the free alkali on-line detection value set and the free alkali off-line detection value set, comparing and fitting the available chlorine on-line detection value set and the available chlorine off-line detection value set to obtain an on-line detection data and laboratory data comparison result schematic diagram shown in figure 7, mathematically fitting the free alkali on-line detection value set into a curve, finding that the free alkali off-line detection value set is on the curve, and similarly mathematically fitting the available chlorine on-line detection value set into a curve, finding that the available chlorine off-line detection value is on the curve, thus the on-line detection data and the laboratory data are basically consistent, the established first measurement model and second measurement model are higher in accuracy, the model fitting effect is good, and the method can be used for practical use.
As described above, the free alkali content in the reaction solution is not between 11.35% and 11.54%, which means that the reaction solution can not meet the raw material requirement for producing hydrazine hydrate at the moment, and the process parameter adjustment is needed. Specifically, the step S50 further includes the steps of:
when the on-line detection value of the free base content is less than 11.35%, the preset flow rate is controlled to rise, and the preset flow rate can be controlled to rise at a speed of 5 to 10%, until the on-line detection value of the free base content is more than 11.35% or the on-line detection value of the free base content is equal to 11.40% (which can be stopped when reaching 11.40% due to the postponement of the reaction progress) is stopped. When the free base content on-line detection value is greater than 11.54%, the preset flow rate is controlled to be reduced, and the preset flow rate can be controlled to be reduced at a speed of 5-10%, until the free base content on-line detection value is less than 11.54% or the free base content on-line detection value is equal to 11.45% (stopping can be performed when reaching 11.45% due to the postponement of the reaction progress). Thereby the online detection value of the free alkali content of the reaction liquid is kept between 11.35 percent and 11.54 percent, and the online automatic control of sodium hypochlorite production is realized.
Referring to fig. 1 to 2 again, the embodiment of the application further discloses an online automatic control system for sodium hypochlorite production, which comprises a near infrared spectrum analyzer 400, a control device 500 and a plurality of sodium hypochlorite reaction units, wherein:
the sodium-containing reaction unit comprises a sodium-containing reaction tower 100, a circulating tank 210, a circulating pipeline 310, a bypass pipeline 320 and a finished product pipeline 330, wherein the top inlet of the sodium-containing reaction tower 100 is connected with a sodium hydroxide pipeline 110 and is provided with a first electric control flow valve 120, the bottom inlet of the sodium-containing reaction tower 100 is connected with a chlorine pipeline 130 and is provided with a second electric control flow valve 140, the outlet of the sodium-containing reaction tower 100 is connected with the inlet of the circulating tank 210, the outlet of the circulating tank 210 is connected with one end of the circulating pipeline 310, the other end of the circulating tank is connected with the top inlet of the tower, the head end and the tail end of the bypass pipeline 320 are connected with the circulating pipeline 310, a third electric control flow valve 321, a near infrared spectrum analyzer 400 and a check valve 322 are sequentially arranged on the bypass pipeline 320, one end of the finished product pipeline 330 is connected with the circulating pipeline 310 and is positioned between the tail end and the inlet of the bypass pipeline 320, and the near infrared spectrum analyzer 400, the first electric control flow valve 120, the second electric control flow valve 140, the third electric control flow valve 321 and the fourth electric control flow valve 331 are electrically connected with a control device 500.
The control device 500 controls the opening of the first electric control flow valve 120 to introduce sodium hydroxide solution into the sodium hypochlorite reaction tower 100 from the top of the tower according to a preset flow rate, the control device 500 controls the opening of the second electric control flow valve 140 to introduce a sufficient amount of chlorine into the sodium hypochlorite reaction tower 100 from the bottom of the tower, then the control device 500 controls the opening of the third electric control flow valve 321 to enable part of the reaction solution to enter the bypass pipeline 320, and then the near infrared spectrum of the reaction solution in the bypass pipeline 320 is detected by the near infrared spectrum analyzer 400, and a free alkali content predicted value and an effective chlorine content predicted value are obtained by a near infrared spectrum analysis method; the reaction liquid detected in the bypass pipe 320 is recombined into the circulation pipe 310 through the check valve 322, and the check valve 322 can prevent backflow, which affects the normal detection of the near infrared spectrum analyzer 400. The control device 500 fits the predicted value of the free alkali content with a first measurement model (as shown in fig. 4) to obtain an online detection value of the free alkali content of the reaction liquid; fitting the predicted value of the available chlorine content with a second measurement model (as shown in figure 5) to obtain an online detection value of the available chlorine content of the reaction liquid; when the online detection value of the free alkali content is between 11.35% and 11.54% (the effective chlorine content is about 9.2%), the control device 500 controls the opening of the fourth electronically controlled flow valve 331, and sodium hypochlorite products are extracted from the circulation pipeline 310 through the finished product pipeline 330 and stored in the finished product tank 220, so that the sodium hypochlorite products with the free alkali content between 11.35% and 11.54% are obtained. The sodium hypochlorite is produced by controlling a plurality of sodium hypochlorite reaction units in the same way. When the online detection value of the free alkali content is not between 11.35% and 11.54%, the control device 500 controls the fourth electrically controlled flow valve 331 to be closed, and sodium hypochlorite products are not extracted.
In the online automatic control system for sodium hypochlorite production disclosed by the embodiment of the application, the free alkali content and the effective chlorine content of the reaction liquid can be detected online in real time through the near infrared spectrum analyzer 400, when the online detection value of the free alkali content is between 11.35% and 11.54%, sodium hypochlorite products are extracted from the circulating pipeline 310 through the finished product pipeline 330, so that sodium hypochlorite meeting the requirement of producing hydrazine hydrate raw materials is obtained, otherwise, sodium hypochlorite is not extracted, and simultaneously, the process parameters are adjusted until the online detection value of the free alkali content is between 11.35% and 11.54%. The system can be used for detecting the free alkali content and the effective chlorine content of the obtained reaction liquid on line in real time, so that the process parameters can be adjusted in real time due to the fact that a certain time hysteresis exists due to manual detection, the detection accuracy of detection in the mode is high, the inaccuracy of detection results due to human factors in the manual detection process is avoided, the free alkali content and the effective chlorine content in the finally produced sodium hypochlorite can meet the raw material requirement of hydrazine hydrate production, and the production yield of hydrazine hydrate in the subsequent process is prevented from being influenced. Meanwhile, the system replaces manual detection, so that the manual labor intensity and the workload can be reduced.
Further, the plurality of sodium-containing reaction units include a first sodium-containing reaction unit and a second sodium-containing reaction unit, and the control device 500 controls the third electrically controlled flow valve 321 of the first sodium-containing reaction unit and the third electrically controlled flow valve 321 of the second sodium-containing reaction unit to be intermittently and alternately opened according to 0.1Hz (once detected for 10 seconds) to 0.2Hz (once detected for 5 seconds), so that the first sodium-containing reaction unit and the second sodium-containing reaction unit share one near infrared spectrum analyzer 400.
By alternately detecting the free alkali content and the effective chlorine content of two sodium hypochlorite reaction units in continuous production, the two sodium hypochlorite reaction units can share one set of infrared spectrum analyzer 400, so that one set of infrared spectrum analyzer 400 can be saved, the condition that each sodium hypochlorite reaction unit needs to be provided with one set of infrared spectrum analyzer 400 is avoided, the construction cost can be saved, and the investment cost is reduced. Meanwhile, because the intermittent and alternate detection is carried out according to the interval from 0.1Hz (once detected in 10 seconds) to 0.2Hz (once detected in 5 seconds), the time interval is shorter, the timeliness of the system for adjusting the production process parameters and extracting sodium hypochlorite products according to the detection result is not influenced, and the two sodium hypochlorite reaction units can normally operate, and the operation process is the same when each sodium hypochlorite reaction unit is provided with one set of infrared spectrum analyzer 400. Therefore, the infrared spectrum analyzer 400 can be saved and the cost investment can be reduced under the condition of not influencing the normal operation.
From the point of view of the sample taken in situ, the reaction solution contains a fine bubble-like substance, which should be salt (NaCl) instead of bubbles, as examined. The reaction principle is as follows: the chlorine gas introduced into the reaction tower reacts with water under the condition of pressure fluctuation to generate a small amount of hydrogen chloride (HCl), and the hydrogen chloride (HCl) reacts with liquid alkali (NaOH) to generate a small amount of salt (NaCl). The salt is suspended in a sodium hypochlorite solution, which is similar to bubbles because of its fine morphology, and does not affect the near infrared spectrum detection result, but blocks the detection head of the near infrared spectrum analyzer 400. Based on this, the bypass pipe 320 is optionally provided vertically, and in the bypass pipe 320, the flow direction of the sodium hypochlorite reaction liquid is vertically upward. The vertical installation mode is adopted to enable the reaction liquid for detection to flow vertically upwards, so that the suspension can be prevented from blocking the detection head of the near infrared spectrum analyzer 400, and the reliability and the stability of the system are improved.
Of course, the bypass pipe 320 may be connected with a cleaning water port to clean the detection head of the near infrared spectrum analyzer 400 periodically, and the third electric control flow valve 321 and the check valve 322 are closed to be filled with cleaning water for cleaning during cleaning.
Preferably, the configuration parameters of the near infrared spectrum analyzer 400 are: the wavelength ranges from 950nm to 1650nm, the resolution is 2nm, the absorbance noise is less than 0.00005AU, and the wavelength temperature drift is less than 0.005 nm/DEG C. The near infrared spectrum analyzer 400 has high performance and high accuracy of near infrared spectrum detection for sodium hypochlorite.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (9)
1. An online automatic control method for sodium hypochlorite production is characterized by comprising the following steps:
s10, introducing sodium hydroxide solution into a sodium hypochlorite reaction tower (100) from the top of the tower according to a preset flow, and introducing enough chlorine into the sodium hypochlorite reaction tower (100) from the bottom of the tower;
s20, obtaining a reaction solution from the bottom of the sodium hypochlorite reaction tower (100), introducing the reaction solution into the sodium hypochlorite reaction tower (100) from the top of the tower through a circulating pipeline (310), wherein the circulating pipeline (310) is connected with a bypass pipeline (320), the head end and the tail end of the bypass pipeline (320) are connected with the circulating pipeline (310), detecting the near infrared spectrum of the reaction solution in the bypass pipeline (320), and obtaining a predicted value of free alkali content and a predicted value of effective chlorine content through a near infrared spectrum analysis method;
s30, fitting the predicted value of the free alkali content with a first measurement model to obtain an online detection value of the free alkali content of the reaction liquid; fitting the predicted value of the available chlorine content with a second measurement model to obtain an online detection value of the available chlorine content of the reaction liquid;
s40, when the online detection value of the free alkali content is between 11.35% and 11.54%, sodium hypochlorite product is extracted from the circulating pipeline (310).
2. The on-line automatic control method for sodium hypochlorite production according to claim 1, further comprising the following steps before the step S10:
s01, preparing a plurality of sodium hypochlorite samples with different concentrations, and respectively detecting near infrared spectrums of the sodium hypochlorite samples;
s02, obtaining a free alkali content analysis value of each sodium hypochlorite sample through a near infrared spectrum analysis method, and obtaining a first correction set for establishing a model; obtaining an effective chlorine content analysis value of each sodium hypochlorite sample through a near infrared spectrum analysis method, and obtaining a second correction set for establishing a model;
s03, detecting a free alkali content detection value of each sodium hypochlorite sample through physicochemical analysis to obtain a first verification set for verifying the prediction capacity of the model; detecting the effective chlorine content detection value of each sodium hypochlorite sample through physicochemical analysis to obtain a second verification set for verifying the prediction capability of the model;
s04, fitting the first correction set with the first verification set to establish the first measurement model, and fitting the second correction set with the second verification set to establish the second measurement model.
3. The on-line automatic control method for sodium hypochlorite production according to claim 1 or 2, wherein the acquisition conditions of the near infrared spectrum are as follows: the wavelength ranges from 950nm to 1650nm, the resolution is 2nm, the absorbance noise is less than 0.00005AU, and the wavelength temperature drift is less than 0.005 nm/DEG C.
4. According to claimThe online automatic control method for sodium hypochlorite production as claimed in claim 2, wherein R of the first measurement model and the second measurement model 2 Greater than 0.9, the RMSECV of the first measurement model is less than or equal to 0.1, and the RMSECV of the second measurement model is less than or equal to 0.1.
5. The on-line automatic control method for sodium hypochlorite production according to claim 1, wherein the step S50 further comprises the steps of:
and when the online detection value of the free alkali content is smaller than 11.35%, controlling the preset flow to be increased, and when the online detection value of the free alkali content is larger than 11.54%, controlling the preset flow to be decreased so as to keep the online detection value of the free alkali content of the reaction liquid between 11.35% and 11.54%.
6. The utility model provides an online automatic control system of sodium hypochlorite production, its characterized in that includes near infrared spectrum analyzer (400), controlling means (500) and a plurality of sodium hypochlorite reaction unit, sodium hypochlorite reaction unit includes sodium hypochlorite reaction tower (100), circulation pipeline (310), bypass pipeline (320) and finished product pipeline (330), the top of a tower access connection of sodium hypochlorite reaction tower (100) has sodium hydroxide pipeline (110), and is provided with first automatically controlled flow valve (120), the bottom of a tower access connection of sodium hypochlorite reaction tower (100) has chlorine pipeline (130), and is provided with second automatically controlled flow valve (140), the export of sodium hypochlorite reaction tower (100) with the one end of circulation pipeline (310) links to each other, the other end with the top of a tower access links to each other, bypass pipeline (320) both ends all with circulation pipeline (310) link to each other, just third automatically controlled flow valve (321) have been set gradually on bypass pipeline (320) near infrared spectrum analyzer (400) and check valve (322), be provided with fourth automatically controlled flow valve (120) on finished product pipeline (330), tail end of a tower access connection has chlorine pipeline (130), and second automatically controlled flow valve (140), the electrically controlled flow valve (320) are located between the first automatically controlled flow valve (310) and the first automatically controlled flow valve (320) The third electrically controlled flow valve (321) and the fourth electrically controlled flow valve (331) are electrically connected with the control device (500).
7. The sodium hypochlorite production online automatic control system according to claim 6, wherein the sodium hypochlorite reaction units comprise a first sodium reaction unit and a second sodium reaction unit, and the control device (500) controls the third electric control flow valve (321) of the first sodium reaction unit and the third electric control flow valve (321) of the second sodium reaction unit to be opened intermittently and alternately according to 0.1Hz to 0.2Hz, so that the first sodium reaction unit and the second sodium reaction unit share one near infrared spectrum analyzer (400).
8. The on-line automatic control system for sodium hypochlorite production according to claim 6, wherein the bypass pipe (320) is vertically arranged, and the flow direction of the sodium hypochlorite reaction liquid in the bypass pipe (320) is vertically upward.
9. The on-line automatic control system for sodium hypochlorite production according to claim 6, wherein the configuration parameters of the near infrared spectrum analyzer (400) are: the wavelength ranges from 950nm to 1650nm, the resolution is 2nm, the absorbance noise is less than 0.00005AU, and the wavelength temperature drift is less than 0.005 nm/DEG C.
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| CN117742278B (en) * | 2024-02-07 | 2024-04-30 | 四川飞洁科技发展有限公司 | Intelligent monitoring and management method and system for sodium hypochlorite production process |
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