CN116730543A - System and method for integrated dechlorination of chlorine water and light brine - Google Patents
System and method for integrated dechlorination of chlorine water and light brine Download PDFInfo
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- CN116730543A CN116730543A CN202310805299.7A CN202310805299A CN116730543A CN 116730543 A CN116730543 A CN 116730543A CN 202310805299 A CN202310805299 A CN 202310805299A CN 116730543 A CN116730543 A CN 116730543A
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- Prior art keywords
- brine
- dechlorination
- mixed
- tank
- chlorine
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- 239000012267 brine Substances 0.000 title claims abstract description 237
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 title claims abstract description 237
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 119
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 title claims abstract description 117
- 239000000460 chlorine Substances 0.000 title claims abstract description 117
- 229910052801 chlorine Inorganic materials 0.000 title claims abstract description 117
- 238000006298 dechlorination reaction Methods 0.000 title claims abstract description 115
- 238000000034 method Methods 0.000 title claims abstract description 32
- XTEGARKTQYYJKE-UHFFFAOYSA-M Chlorate Chemical compound [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 claims abstract description 126
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 113
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims abstract description 92
- 230000003068 static effect Effects 0.000 claims abstract description 78
- 150000003839 salts Chemical class 0.000 claims abstract description 60
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 46
- 235000010265 sodium sulphite Nutrition 0.000 claims abstract description 46
- 238000004519 manufacturing process Methods 0.000 claims abstract description 21
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims description 25
- 239000000243 solution Substances 0.000 claims description 25
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 230000010354 integration Effects 0.000 claims 1
- 230000001105 regulatory effect Effects 0.000 claims 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 4
- 229910052799 carbon Inorganic materials 0.000 abstract description 4
- 239000012535 impurity Substances 0.000 abstract description 3
- 239000002994 raw material Substances 0.000 abstract description 3
- 239000000126 substance Substances 0.000 abstract description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 28
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 22
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 12
- 239000000047 product Substances 0.000 description 11
- 235000011121 sodium hydroxide Nutrition 0.000 description 9
- 238000007599 discharging Methods 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 239000011780 sodium chloride Substances 0.000 description 6
- 239000011259 mixed solution Substances 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 4
- 239000003513 alkali Substances 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- 239000012528 membrane Substances 0.000 description 3
- 239000005708 Sodium hypochlorite Substances 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229920001429 chelating resin Polymers 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/06—Flash evaporation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
The invention relates to a system and a method for dechlorination production of chlorine water and electrolyzed light brine, belonging to the field of chemical industry. The system comprises a mixed dilute salt water tank, a heater, a hydrochloric acid static mixer, a chlorate decomposition tank, a dechlorination tower, a dechlorination dilute salt water pump, a sodium sulfite static mixer and a cooler. By adopting the system and the method, the target product, namely the dechlorinated light brine with few impurities and good quality is obtained and returned to the production system for repeated use, so that the consumption of raw materials in production is reduced, the environment is prevented from being polluted, and the carbon emission of a production device is reduced.
Description
Technical Field
The invention relates to the field of chemical industry, in particular to a system and a method for integrated dechlorination of chlorine water and dilute brine, which are used for collecting the chlorine water from a chlorine system and the electrolyzed dilute brine from an ion membrane electrolyzer in the chlor-alkali industry, carrying out centralized treatment, and carrying out integrated removal of free chlorine contained in the chlorine water and the dilute brine, wherein the free chlorine comprises dissolved chlorine and compound chlorine, so as to obtain a target product, namely, the dechlorinated dilute brine, which is returned to a new process for recycling the production system.
Background
Chlorine-containing gas of a chlorine system in the chlor-alkali industry can generate chlorine water in the cooling process, and an ionic membrane electrolyzer can generate electrolyzed light brine, wherein the two substances contain a large amount of free chlorine besides chloride ions which can be returned to a production system for reuse. The free chlorine exists in two forms, the first is dissolved free chlorine and the second is combined free chlorine, including hypochlorite and chlorate, and chlorate and sodium ions can form chlorate.
The electrolytic dilute brine flowing out of the ion membrane electrolytic tank has large flow rate, contains a large amount of sodium chloride, and has less impurity content except free chlorine and chlorate. The discharge of chlorine water and electrolyzed dilute brine can cause great waste, and has the problems of environmental pollution, worsening the operation environment and the like.
The chlorine water and the electrolyzed dilute brine contain free chlorine and chlorate, have strong corrosion and destruction effects on steel equipment and pipelines of a brine system, carbon sintering pipes and chelating resin, and simultaneously block Mg (OH) in the refining process 2 And CaCO (CaCO) 3 After dechlorination of the chlorine water with the electrolyzed brackish water, the target product, dechlorinated brackish water, may be returned to the production system for use.
At present, the discharge method is adopted to reduce the accumulation of chlorate in the production system, and the part of the dechlorinated fresh brine is discharged before being sent back to the production system, so that the discharged fresh brine not only pollutes the environment, but also causes the waste of sodium chloride in the fresh brine. The chlorine in the dilute brine is blown out by adopting an air blowing method in the dechlorination tower, and the blown chlorine has lower purity and can not be combined with a chlorine main pipe, and only alkaline liquor can be used for absorbing and producing byproduct sodium hypochlorite solution, so that the method has the defects of low recovery rate of the chlorine and high consumption of the alkaline liquor, and the sodium hypochlorite product has the defects of low price, inconvenience for long-time storage, difficulty in control of production and the like, so that the air blowing dechlorination method has poor economy.
The conventional treatment of the chlorine water and the electrolyzed dilute brine not only causes environmental pollution and wastes resources, but also has poor economy, and a system and a method with simple flow, large production capacity and good treatment effect are needed to be provided for the treatment of the chlorine water and the electrolyzed dilute brine.
Disclosure of Invention
The invention aims to provide a system and a method for integrated dechlorination of chlorine water and fresh brine, wherein the system comprises a mixed fresh brine tank, a mixed fresh brine pump, a heater, a hydrochloric acid static mixer, a chlorate decomposition tank, a dechlorinated salt fresh brine pump, a dechlorination tower, a dechlorinated fresh brine pump, a sodium sulfite static mixer, a cooler and a vacuum pump. The method comprises the steps of mixing electrolysis fresh brine from a boundary area with chlorine water in a mixed fresh brine tank, heating the mixed fresh brine by a mixed fresh brine pump dechlorination heater, adding hydrochloric acid before the mixed fresh brine enters a hydrochloric acid static mixer, discharging the hydrochloric acid static mixer, then entering a chlorate decomposition tank, decomposing chlorate into hypochlorite and hypochlorite into chlorine in the chlorate decomposition tank, discharging chlorine gas containing water vapor in a gas phase from a chlorine gas header pipe at the top of the chlorate decomposition tank, discharging liquid-phase dechlorination salt fresh brine from a dechlorination tower through a dechlorination salt fresh brine pump, discharging chlorine gas containing water vapor from a cooler at the top of the dechlorination tower, adding sodium hydroxide solution from the boundary area before the dechlorination fresh brine pump, discharging the dechlorination fresh brine of the dechlorination fresh brine pump into a sodium sulfite static mixer, adding sodium sulfite solution from the boundary area before the sodium sulfite static mixer, and discharging the dechlorination fresh brine of the sodium sulfite static mixer as a target product.
By adopting the system and the method, the target product, namely the dechlorinated light brine with few impurities and good quality is obtained and returned to the production system for repeated use, so that the consumption of raw materials in production is reduced, the environment is prevented from being polluted, and the carbon emission of a production device is reduced.
The aim of the invention can be achieved by the following technical scheme:
the system comprises a mixed dilute brine tank, a chlorate decomposition tank and a dechlorination tower; the mixed light salt water tank is connected with the dechlorination tower sequentially through a heater, a hydrochloric acid static mixer, a chlorate decomposition tank and a dechlorination tower.
In the above system: the dechlorination tower is connected with a vacuum pump through a cooler, the output end of the vacuum pump is connected with a chlorine main pipe, and the output ends of the mixed dilute salt water tank and the chlorate decomposition tank are also connected with the chlorine main pipe.
In the above system: the bottom of the dechlorination tower is connected with a sodium sulfite static mixer through a dechlorination fresh salt water pump, and the input end of the sodium sulfite static mixer is also connected with an output pipeline of the sulfurous acid solution.
In the above system: the mixed fresh brine tank is provided with an overflow weir plate, the bottom end of an inlet pipe at the top A, B, C of the mixed fresh brine tank is positioned in the overflow weir plate, the bottom end outlet of an inlet pipe A is lower than the height in the top plate of the mixed fresh brine tank, the bottom end outlet of an inlet pipe B, C is lower than the height above the overflow weir plate, and the lower outlet of the mixed fresh brine tank is outside the overflow weir plate.
The production method for realizing the integrated dechlorination of the chlorine water and the light brine by using the system comprises the following steps:
(1) Eliminating chlorate working section: the method comprises the steps that electrolytic fresh brine from a boundary area enters a mixed fresh brine tank from an inlet at the top A of the mixed fresh brine tank, chlorine water from the boundary area enters the mixed fresh brine tank from an inlet at the top B of the mixed fresh brine tank, condensate from a cooler enters the mixed fresh brine tank from an inlet at the top C of the mixed fresh brine tank, then the mixed fresh brine in the mixed fresh brine tank is sent to a heater for heating and heating, then a static mixer for removing hydrochloric acid is used, hydrochloric acid solution is also added into the static mixer for hydrochloric acid, the mixed fresh brine and hydrochloric acid are evenly mixed in the static mixer for hydrochloric acid, the mixed fresh brine enters a chlorate decomposition tank after even mixing, and a chlorine gas total pipe containing water vapor obtained after decomposition in the chlorate decomposition tank is removed;
(2) Dechlorination section: the method comprises the steps that the dilute hydrochloric acid salt-removed brine in a chlorate decomposition tank enters a dechlorination tower, the dechlorination tower works in a vacuum state, the dilute hydrochloric acid salt-removed brine is flashed in the dechlorination tower, the flashed chlorine containing water vapor enters a cooler from an outlet at the top of the dechlorination tower through a cooler tube side inlet, a chlorine gas removing main pipe of the cooled water vapor, and a condensed liquid removes a mixed dilute salt water tank from an outlet at the bottom of the tube side;
the dechlorinated dilute brine enters a sodium sulfite static mixer from the bottom of the dechlorination tower, the dechlorinated dilute brine is added into sodium sulfite solution from the boundary region in a pipeline of the sodium sulfite static mixer, and the dechlorinated dilute brine of the sodium sulfite static mixer is taken as the boundary region of the target product.
In some more specific technical schemes, the technical scheme of the invention is as follows:
the system comprises a mixed fresh salt water tank, a mixed fresh salt water pump, a heater, a hydrochloric acid static mixer, a chlorate decomposition tank, a dechlorinated salt fresh salt water pump, a dechlorination tower, a dechlorinated fresh salt water pump, a sodium sulfite static mixer, a cooler and a vacuum pump. The mixed fresh brine tank is connected with a mixed fresh brine inlet of a heater through a mixed fresh brine pump, a mixed fresh brine outlet of the heater is connected with a mixed fresh brine inlet of a chlorate decomposer through a hydrochloric acid static mixer, a dechlorinated salt fresh brine outlet of the chlorate decomposer is connected with a dechlorinated salt fresh brine inlet at the upper part of a dechlorination tower through a dechlorinated salt fresh brine pump, a dechlorinated fresh brine outlet at the bottom of the dechlorination tower is connected with a sodium sulfite static mixer inlet through a dechlorinated fresh brine pump, and a sodium sulfite static mixer outlet is connected with a pipeline of a target product-dechlorinated fresh brine boundary removing zone.
The technical scheme of the invention is as follows: the low-pressure steam inlet of the heater is connected with a low-pressure steam pipeline from the boundary region, the condensed water outlet of the heater is connected with a condensed water pipeline from the boundary region, and a hydrochloric acid solution pipeline from the boundary region is arranged on a pipeline connected with the mixed dilute brine outlet of the heater and the inlet of the hydrochloric acid static mixer; a sodium hydroxide solution pipeline from a boundary region is arranged on a pipeline of the dechlorination dilute brine outlet at the bottom of the dechlorination tower, which is connected with the inlet of the dechlorination dilute brine pump; the pipeline connecting the outlet of the dechlorination dilute brine pump with the inlet of the sodium sulfite static mixer is provided with a sodium sulfite solution pipeline from the boundary region.
The technical scheme of the invention is as follows: the mixed dilute brine tank top A inlet is connected with an electrolytic dilute brine pipeline from a boundary region, the mixed dilute brine tank top B inlet is connected with a chlorine water pipeline from the boundary region, the mixed dilute brine tank top C inlet is connected with a cooler pipeline bottom condensate outlet, the mixed dilute brine tank top D outlet is connected with a pipeline of a chlorine removal main pipe, and the pipeline is provided with a pipeline from a chlorate decomposition tank top outlet and a vacuum pump outlet. An overflow weir plate is arranged in the mixed dilute brine tank, the inlet of the top A, B, C of the mixed dilute brine tank is provided with an inlet pipe, the position of the inlet pipe is in the overflow weir plate, the outlet of the bottom end of the inlet pipe A is lower than the height of the inside of the top plate of the mixed dilute brine tank, the outlet of the bottom end of the inlet pipe B, C is lower than the height of the upper edge of the overflow weir plate, and the outlet of the lower part of the mixed dilute brine tank is outside the overflow weir plate.
The technical scheme of the invention is as follows: the cooler tube-pass inlet is connected with the outlet of the top of the dechlorination tower, and the outlet of the top of the cooler tube-pass is connected with the inlet of the vacuum pump; the inlet at the bottom of the cooler shell side is connected with a circulating water supply pipeline from the boundary region, and the outlet at the top of the cooler shell side is connected with a circulating water return pipeline from the boundary region.
The technical scheme of the invention is as follows: the heater is a plate heat exchanger; the cooler is a horizontal tube type heat exchanger.
The production method for realizing the integrated dechlorination of the chlorine water and the light brine by using the system comprises the following steps:
(1) Eliminating chlorate working section: the electrolytic fresh brine from the boundary area enters the mixed fresh brine tank from an inlet at the top A of the mixed fresh brine tank, the chlorine water from the boundary area enters the mixed fresh brine tank from an inlet at the top B of the mixed fresh brine tank, the condensate from the cooler enters the mixed fresh brine tank from an inlet at the top C of the mixed fresh brine tank, the mixed fresh brine consisting of three solutions is turned over an overflow weir plate to remove the mixed fresh brine pump from the lower outlet of the mixed fresh brine tank, and the chlorine in the mixed fresh brine tank is removed from an outlet at the top D of the mixed fresh brine tank to remove a chlorine main pipe. The mixed fresh brine pump sends mixed fresh brine into the heater from the mixed fresh brine inlet of the heater, the mixed fresh brine is heated by low-pressure steam in the heater, then the mixed fresh brine is subjected to temperature rise, the mixed fresh brine is subjected to a hydrochloric acid removal static mixer from the mixed fresh brine outlet of the heater, the low-pressure steam from the boundary region enters the heater from the low-pressure steam inlet of the heater, and the low-pressure steam is cooled into condensed water in the heater and then is subjected to boundary region removal from the condensed water outlet of the heater. The mixed dilute brine is added into hydrochloric acid from a boundary region in a pipeline of a dehydrohydrochloric acid static mixer, then enters the hydrochloric acid static mixer from an inlet of the hydrochloric acid static mixer, the mixed dilute brine and the hydrochloric acid are uniformly mixed in the hydrochloric acid static mixer, the uniform mixed solution enters a chlorate decomposition tank from an outlet of the hydrochloric acid static mixer through an inlet at the lower part of the chlorate decomposition tank, chlorate in the chlorate decomposition tank is decomposed into hypochlorite, the hypochlorite is decomposed into chlorine, chlorine gas containing water vapor in a gas phase of the chlorate decomposition tank is removed from a chlorine header pipe from an outlet at the top of the chlorate decomposition tank, and the liquid-phase dehydrochlorate dilute brine is subjected to a dehydrochlorate dilute brine pump to obtain a dehydrochlorate section.
(2) Dechlorination section: the dechlorinated salt brine from the dechlorinated salt brine pump enters the dechlorination tower through a dechlorination salt brine inlet at the upper part of the dechlorination tower, the dechlorination tower works in a vacuum state, and the dechlorination salt brine is flashed in the dechlorination tower. The chlorine containing water vapor which is flashed out enters a cooler from the outlet of the top of the dechlorination tower through the pipeline inlet of the cooler, the chlorine containing water vapor in the cooler is cooled, the chlorine is removed from the outlet of the top of the pipeline through a vacuum pump to a chlorine main pipe, condensate is removed from the outlet of the bottom of the pipeline to a mixed dilute salt water tank, circulating water from a boundary area enters the cooler from the shell side inlet of the cooler, and the chlorine containing water vapor in the pipeline is cooled and then removed from the shell side outlet. The dechlorinated dilute brine enters the sodium sulfite static mixer from the inlet of the sodium sulfite static mixer, the dechlorinated dilute brine is added into the sodium sulfite solution from the boundary zone in the pipeline of the sodium sulfite static mixer, and the dechlorinated dilute brine of the sodium sulfite static mixer is taken as the target product boundary zone.
The method for integrated dechlorination of chlorine water and fresh brine comprises the steps of mixing electrolytic fresh brine and chlorine water in a mixed fresh brine tank, heating the mixed fresh brine by a heater, adding hydrochloric acid after heating, then entering a hydrochloric acid static mixer, entering a chlorate decomposition tank after exiting the hydrochloric acid static mixer, decomposing chlorate into hypochlorite in the chlorate decomposition tank, decomposing hypochlorite into chlorine, removing chlorine gas containing water vapor in gas phase from a chlorine gas header pipe at the top of the chlorate decomposition tank, removing the chlorine gas of a liquid-phase dechlorinated salt fresh brine dechlorination tower, removing chlorine gas containing water vapor from a cooler at the top of the dechlorination tower, adding sodium hydroxide solution into the dechlorinated fresh brine from the outlet at the bottom of the dechlorination tower, then removing the dechlorinated fresh brine by the dechlorination fresh brine pump, adding sodium sulfite solution into the sodium sulfite static mixer, and exiting the dechlorinated fresh brine of the static mixer as a target product dechlorination area. The method is characterized in that chlorine water and light brine are collected together, and integrated dechlorination is carried out by the same process according to the common characteristics of the chlorine water and the light brine, and the production process comprises the following steps: (1) The method comprises the following steps of (1) a chlorate eliminating section, (2) a dechlorination section:
(1) Eliminating chlorate working section: the method comprises the steps that electrolytic fresh brine (the temperature is more than or equal to 80 ℃, sodium chloride is more than or equal to 190g/L, free chlorine is less than or equal to 800 mg/L) from a mixed fresh brine tank top A inlet, chlorine water (the temperature is less than or equal to 35 ℃, free chlorine is less than or equal to 5.0 g/L) from a mixed fresh brine tank top B inlet, condensate (the temperature is less than or equal to 55 ℃, free chlorine is less than or equal to 4.3 g/L) from a cooler enters the mixed fresh brine tank from a mixed fresh brine tank top C inlet, mixed fresh brine composed of three solutions is overturned through an overflow weir plate to remove the mixed fresh brine pump from a mixed fresh brine tank lower outlet, and chlorine in the mixed fresh brine tank is removed from a chlorine header pipe from a mixed fresh brine tank top D outlet. The mixed fresh brine pump sends mixed fresh brine into the heater from the mixed fresh brine inlet of the heater, the mixed fresh brine is heated by low-pressure steam in the heater to raise the temperature (the temperature is more than or equal to 90 ℃), then the mixed fresh brine is subjected to a hydrochloric acid static mixer from the mixed fresh brine outlet of the heater, the low-pressure steam from the boundary region enters the heater from the low-pressure steam inlet of the heater, and the low-pressure steam is cooled into condensed water in the heater and then is subjected to boundary region removal from the condensed water outlet of the heater. The mixed fresh brine is added into hydrochloric acid from a boundary region in a pipeline of a hydrochloric acid removal static mixer, then enters the hydrochloric acid static mixer from an inlet of the hydrochloric acid static mixer, the mixed fresh brine and hydrochloric acid are uniformly mixed in the hydrochloric acid static mixer, the pH value is controlled to be less than or equal to 3, uniform mixed solution (the temperature is more than or equal to 90 ℃ and free chlorine is less than or equal to 1400 mg/L) enters a chlorate decomposition tank from an outlet of the hydrochloric acid static mixer through an inlet at the lower part of the chlorate decomposition tank, the residence time of the mixed solution in the chlorate decomposition tank is controlled to be more than or equal to 3 hours, chlorate is decomposed into hypochlorite in the chlorate decomposition tank, the hypochlorite is decomposed into chlorine, the chlorine gas containing water vapor in a gas phase of the chlorate decomposition tank is removed from a chlorine header pipe at the top outlet of the chlorate decomposition tank, and the chlorine removal salt fresh brine (the temperature is more than or equal to 85 ℃ and free chlorine is less than or equal to 800 mg/L) is subjected to a chlorine removal section of a chlorine removal salt fresh brine pump.
(2) Dechlorination section: the dilute chlorine removing salt water (with the temperature not less than 85 ℃ and free chlorine not more than 800 mg/L) from the dilute chlorine removing salt water pump enters the dechlorination tower through the dilute chlorine removing salt water inlet at the upper part of the dechlorination tower, the dechlorination tower works in a vacuum state, the vacuum degree is not more than 50kPa, and the dilute chlorine removing salt water is flashed in the dechlorination tower. The chlorine gas containing water vapor (the temperature is less than or equal to 80 ℃) which is flashed out enters a cooler from a top outlet of a dechlorination tower through a pipeline inlet of the cooler, the chlorine gas containing water vapor in the cooler is cooled, a chlorine gas main pipe is removed from the top outlet of the pipeline through a vacuum pump, condensate (the temperature is less than or equal to 55 ℃ and contains free chlorine is less than or equal to 4.3 g/L) is removed from a bottom outlet of the pipeline, mixed dilute salt water tank is removed from circulating upper water from a boundary region enters the cooler from a shell side inlet of the cooler, and the chlorine gas containing water vapor in the pipeline is cooled and then removed from the shell side outlet. The dechlorinated fresh brine (the temperature is less than or equal to 80 ℃ and the free chlorine is less than or equal to 20 mg/L) is discharged from the outlet of the bottom of the dechlorination tower, the dechlorinated fresh brine is added into a sodium hydroxide solution from a boundary region in a pipeline of the dechlorination tower to control the pH to be more than or equal to 9, the dechlorinated fresh brine discharged from the dechlorination fresh brine pump enters a sodium sulfite static mixer from an inlet of the sodium sulfite static mixer, the dechlorinated fresh brine is added into a sodium sulfite solution from the boundary region in a pipeline of the sodium sulfite static mixer, and the dechlorinated fresh brine (the free chlorine is less than or equal to 1 mg/L) discharged from the sodium sulfite static mixer is used as a target product to be discharged from the boundary region. The invention has the beneficial effects that:
the invention provides a system and a method for integrated dechlorination of chlorine water and dilute brine, which can produce 6-8 cubic meters of chlorine water and electrolyzed dilute brine containing 190-210 g/L sodium chloride and less than or equal to 1400mg/L free chlorine per ton of caustic soda (100%) produced in the chlor-alkali industry. After the integrated dechlorination treatment, the chlorine water and the electrolyzed light brine are changed into dechlorinated light brine which can be returned to a production system for repeated use, and each ton of caustic soda (100%) produced reduces the discharge of the chlorine water and the electrolyzed light brine by 6-8 cubic meters, reduces the consumption of sodium chloride by 1.1-1.7 tons, and the removed chlorine is recycled by a chlorine removal system. The invention aims to reduce the consumption of raw materials in chlor-alkali production, reduce the emission of waste gas and waste liquid, save energy, reduce consumption, reduce carbon emission and protect the environment.
Drawings
FIG. 1 is a schematic diagram of the process flow in this patent
The device comprises a mixed dilute brine tank 1, a mixed dilute brine pump 2, a heater 3, a hydrochloric acid static mixer 4, a chlorate decomposition tank 5, a dechlorinated salt dilute brine pump 6, a dechlorination tower 7, a dechlorinated dilute brine pump 8, a sodium sulfite static mixer 9, a cooler 10 and a vacuum pump 11.
Detailed Description
The invention is further illustrated below with reference to examples, but the scope of the invention is not limited thereto:
the system for integrated dechlorination of chlorine water and fresh brine as shown in fig. 1 comprises a mixed fresh brine tank 1, a mixed fresh brine pump 2, a heater 3, a hydrochloric acid static mixer 4, a chlorate decomposition tank 5, a dechlorinated salt fresh brine pump 6, a dechlorination tower 7, a dechlorinated fresh brine pump 8, a sodium sulfite static mixer 9, a cooler 10 and a vacuum pump 11.
The mixed fresh salt water tank 1 is connected with a mixed fresh salt water inlet of the heater 3 through a mixed fresh salt water pump 2, a mixed fresh salt water outlet of the heater 3 is connected with a mixed fresh salt water inlet of the chlorate decomposition tank 5 through a hydrochloric acid static mixer 4, a chloride removal salt fresh salt water outlet of the chlorate decomposition tank 5 is connected with a chloride removal salt fresh salt water inlet at the upper part of the dechlorination tower 7 through a chloride removal salt fresh salt water pump 6, a dechlorination fresh salt water outlet at the bottom of the dechlorination tower 7 is connected with an inlet of the sodium sulfite static mixer 9 through a dechlorination fresh salt water pump 8, and an outlet of the sodium sulfite static mixer 9 is connected with a pipeline of a target product, namely a dechlorination fresh salt water boundary removing zone.
The low-pressure steam inlet of the heater 3 is connected with a low-pressure steam pipeline from the boundary region, the condensed water outlet of the heater 3 is connected with a condensed water pipeline from the boundary region, and a hydrochloric acid solution pipeline from the boundary region is arranged on a pipeline connected with the mixed dilute brine outlet of the heater 3 and the inlet of the hydrochloric acid static mixer 4; a sodium hydroxide solution pipeline from a boundary region is arranged on a pipeline of the bottom dechlorination dilute brine outlet of the dechlorination tower 7 connected with the inlet of the dechlorination dilute brine pump 8; the pipeline of the outlet of the dechlorination dilute brine pump 8 connected with the inlet of the sodium sulfite static mixer 9 is provided with a sodium sulfite solution pipeline from the boundary region.
The top A inlet of the mixed dilute salt water tank 1 is connected with an electrolytic dilute salt water pipeline from a boundary region, the top B inlet of the mixed dilute salt water tank 1 is connected with a chlorine water pipeline from the boundary region, the top C inlet of the mixed dilute salt water tank 1 is connected with a condensate outlet at the bottom of a tube side of the cooler 10, the top D outlet of the mixed dilute salt water tank 1 is connected with a pipeline of a chlorine removal main pipe, and the pipeline is provided with a pipeline from the top outlet of the chlorate decomposition tank 5 and the outlet of the vacuum pump 11. An overflow weir plate is arranged in the mixed dilute brine tank 1, the position of an inlet pipe at the top A, B, C of the mixed dilute brine tank 1 is in the overflow weir plate, the bottom end of an inlet pipe A is lower than the height inside a top plate of the mixed dilute brine tank 1, the bottom end of an inlet pipe B, C is lower than the upper edge of the overflow weir plate, and the outlet at the lower part of the mixed dilute brine tank 1 is outside the overflow weir plate.
The tube side inlet of the cooler 10 is connected with the top outlet of the dechlorination tower 7, and the top outlet of the tube side of the cooler 10 is connected with the inlet of the vacuum pump 11; the bottom inlet of the shell side of the cooler 10 is connected with a circulating water supply pipeline from the boundary region, and the top outlet of the shell side of the cooler 10 is connected with a circulating water return pipeline from the boundary region.
The heater 3 is a plate heat exchanger; the cooler 10 is a horizontal tube heat exchanger.
The production method for realizing the integrated dechlorination of the chlorine water and the light brine by using the system collects the chlorine water and the light brine together, and performs the integrated dechlorination by using the same process according to the common characteristics of the chlorine water and the light brine, and the method comprises the following steps:
(1) Eliminating chlorate working section: the electrolytic fresh brine (with the temperature of 85 ℃, 195g/L containing sodium chloride and 400mg/L containing free chlorine) from the boundary area enters the mixed fresh brine tank 1 from the inlet at the top A of the mixed fresh brine tank 1, the chlorine water (with the temperature of 28 ℃ and 4.23g/L containing free chlorine) from the boundary area enters the mixed fresh brine tank 1 from the inlet at the top B of the mixed fresh brine tank 1, the condensate (with the temperature of 50 ℃ and 4.07g/L containing free chlorine) from the cooler 10 enters the mixed fresh brine tank 1 from the inlet at the top C of the mixed fresh brine tank 1, the mixed fresh brine consisting of three solutions turns over an overflow weir plate to remove the mixed fresh brine pump 2 from the outlet at the lower part of the mixed fresh brine tank 1, and the chlorine in the mixed fresh brine tank 1 removes a chlorine header from the outlet at the top D of the mixed fresh brine tank 1. The mixed fresh brine pump 2 sends mixed fresh brine into the heater 3 from a mixed fresh brine inlet of the heater 3, the mixed fresh brine is heated by low-pressure steam in the heater 3 to rise temperature (temperature is 95 ℃), then the mixed fresh brine is sent to the hydrochloric acid static mixer 4 from a mixed fresh brine outlet of the heater 3, low-pressure steam from a boundary region enters the heater 3 from a low-pressure steam inlet of the heater 3, the low-pressure steam is cooled into condensed water in the heater 3, and then the condensed water is sent to the boundary region from a condensed water outlet of the heater 3. The mixed fresh brine is added into hydrochloric acid (HCl mass concentration 18%) from a boundary region in a pipeline of a hydrochloric acid removal static mixer 4, then enters the hydrochloric acid static mixer 4 from an inlet of the hydrochloric acid static mixer 4, the mixed fresh brine and the hydrochloric acid are uniformly mixed in the hydrochloric acid static mixer 4, the pH value is controlled to be 2.0, uniform mixed solution (with the temperature of 93 ℃ C., free chlorine of 698 mg/L) enters the chlorate decomposition tank 5 from an outlet of the hydrochloric acid static mixer 4 through a lower inlet of the chlorate decomposition tank 5, the residence time of the mixed solution in the chlorate decomposition tank 5 is controlled to be 3-4 hours, chlorate is decomposed into hypochlorite and the hypochlorite is decomposed into chlorine in the chlorate decomposition tank 5, the chlorine gas containing water vapor in a gas phase of the chlorate decomposition tank 5 is removed from a chlorine header pipe at the top outlet of the chlorate decomposition tank 5, and the liquid phase chlorine removal salt fresh brine (with the free chlorine of 300mg/L at the temperature of 88 ℃ C.) is removed from a chlorine removal salt fresh water pump 6.
(2) Dechlorination section: the dechlorinated salt brine (with the temperature of 88 ℃ C., and the free chlorine content of 300 mg/L) from the dechlorinated salt brine pump 6 enters the dechlorination tower 7 through the dechlorinated salt brine inlet at the upper part of the dechlorination towerAnd a chlorine tower 7, wherein the dechlorination tower 7 works under a vacuum state, the vacuum degree is 70kPa, and the dechlorination salt dilute brine is flashed in the dechlorination tower 7. The chlorine gas containing water vapor (temperature 70 ℃) which is flashed off enters the cooler 10 from the outlet at the top of the dechlorination tower 7 through the tube side inlet of the cooler 10, the chlorine gas containing water vapor in the cooler 10 is cooled, the chlorine gas (containing chlorine gas mass percent of 85%) is removed from the outlet at the top of the tube side through the vacuum pump 11 to the chlorine gas main pipe, the condensate (temperature 50 ℃ and free chlorine content of 4.07 g/L) is removed from the outlet at the bottom of the tube side to the mixed dilute salt water tank 1, the circulating upper water from the boundary area enters the cooler from the shell side inlet of the cooler 10, and the chlorine gas containing water vapor in the tube side is cooled and then removed from the shell side outlet. Dechlorinated dilute brine (with the temperature of 75 ℃ and free chlorine of 20 mg/L) is discharged from the bottom outlet of the dechlorination tower 7, the dechlorination dilute brine is added into sodium hydroxide solution (NaOH mass concentration of 32%) from a boundary region to control the pH value to 10 in a pipeline of the dechlorination dilute brine pump 8, the dechlorination dilute brine discharged from the dechlorination dilute brine pump 8 enters the sodium sulfite static mixer 9 from an inlet of the sodium sulfite static mixer 9, and the dechlorination dilute brine is added into sodium sulfite solution (Na) from the boundary region in a pipeline of the sodium sulfite static mixer 9 2 SO 3 10% by mass) of dechlorinated light brine (containing free chlorine 0.8 mg/L) of the sodium sulfite static mixer 9 was taken as the target product stripping zone.
Operation of fruiting bodies using the invention is shown for example in Table 1
Table 1 table of performance check results of 20 ten thousand ton mass concentration 50% naoh (100% folded) per year chlorine water/light brine integrated dechlorination apparatus
Table 1 table of performance test results of 20 ten thousand tons/year chlorine water and light brine integrated dechlorination apparatus
Claims (7)
1. The utility model provides a chlorine water and system of dechlorination of light brine integration which characterized in that: the system comprises a mixed dilute brine tank (1), a chlorate decomposition tank (5) and a dechlorination tower (7); the mixed light salt water tank (1) is connected with the dechlorination tower (7) through the heater (3), the hydrochloric acid static mixer (4), the chlorate decomposition tank (5) in sequence.
2. The system for integrated dechlorination of chlorine water and weak brine of claim 1, wherein: the dechlorination tower (7) is connected with a vacuum pump (11) through a cooler (10), the output end of the vacuum pump (11) is connected with a chlorine main pipe, and the output ends of the mixed dilute brine tank (1) and the chlorate decomposition tank (5) are also connected with the chlorine main pipe.
3. The system for integrated dechlorination of chlorine water and weak brine of claim 1, wherein: the bottom of the dechlorination tower (7) is connected with a sodium sulfite static mixer (9) through a dechlorination dilute brine pump (8), and the input end of the sodium sulfite static mixer (9) is also connected with an output pipeline of sulfurous acid solution.
4. The system for integrated dechlorination of chlorine water and weak brine of claim 1, wherein: the mixed fresh brine tank (1) is provided with an overflow weir plate, the bottom end of a A, B, C inlet pipe at the top of the mixed fresh brine tank is positioned in the overflow weir plate, the bottom end outlet of an A inlet pipe is lower than the height in the top plate of the mixed fresh brine tank, the bottom end outlet of a B, C inlet pipe is lower than the height above the overflow weir plate, and the lower outlet of the mixed fresh brine tank is outside the overflow weir plate.
5. A production method for realizing integrated dechlorination of chlorine water and light brine by using the system of claim 1, which is characterized in that: the method comprises the following steps:
(1) Eliminating chlorate working section: the method comprises the steps that electrolytic fresh brine from a boundary area enters a mixed fresh brine tank (1) from an inlet A at the top of the mixed fresh brine tank (1), chlorine water from the boundary area enters the mixed fresh brine tank (1) from an inlet B at the top of the mixed fresh brine tank (1), condensate from a cooler (10) enters the mixed fresh brine tank (1) from an inlet C at the top of the mixed fresh brine tank (1), then the mixed fresh brine of the mixed fresh brine tank (1) is sent to a heater (3) to be heated, then a hydrochloric acid static mixer (4) is used for removing hydrochloric acid, hydrochloric acid solution is further added into the hydrochloric acid static mixer (4), the mixed fresh brine is evenly mixed with hydrochloric acid in the hydrochloric acid static mixer (4), and then enters a chlorate decomposition tank (5), and chlorine gas containing water vapor obtained after decomposition in the chlorate decomposition tank (5) is removed into chlorine gas;
(2) Dechlorination section: the method comprises the steps that (1) chloride-free dilute brine in a chlorate decomposition tank (5) enters a dechlorination tower (7), the dechlorination tower (7) works in a vacuum state, the chloride-free dilute brine is flashed in the dechlorination tower (7), the flashed chlorine containing water vapor enters a cooler (10) from a top outlet of the dechlorination tower (7) through a tube side inlet of the cooler (10), a chlorine gas removing header pipe containing water vapor after cooling is performed, and condensate liquid is removed from a mixed dilute brine tank (1) from a bottom outlet of the tube side;
the dechlorinated dilute brine enters a sodium sulfite static mixer (9) from the bottom of a dechlorination tower (7), the dechlorinated dilute brine is added into sodium sulfite solution from a boundary region in a pipeline of the sodium sulfite static mixer (9), and the dechlorinated dilute brine of the sodium sulfite static mixer (9) is taken as a target product boundary region.
6. The method according to claim 5, wherein: the heating temperature in the step (1) is 90-95 ℃.
7. The method according to claim 5, wherein: and (3) uniformly mixing the mixed light salt water with hydrochloric acid in a hydrochloric acid static mixer (4), and regulating the pH value to be less than or equal to 3.
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