CN117198582A - Method for recovering radioactive organic waste liquid and recovery device used by same - Google Patents
Method for recovering radioactive organic waste liquid and recovery device used by same Download PDFInfo
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- CN117198582A CN117198582A CN202311254029.8A CN202311254029A CN117198582A CN 117198582 A CN117198582 A CN 117198582A CN 202311254029 A CN202311254029 A CN 202311254029A CN 117198582 A CN117198582 A CN 117198582A
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- 239000007788 liquid Substances 0.000 title claims abstract description 390
- 239000010815 organic waste Substances 0.000 title claims abstract description 154
- 230000002285 radioactive effect Effects 0.000 title claims abstract description 137
- 238000000034 method Methods 0.000 title claims abstract description 79
- 238000011084 recovery Methods 0.000 title claims abstract description 58
- STCOOQWBFONSKY-UHFFFAOYSA-N tributyl phosphate Chemical compound CCCCOP(=O)(OCCCC)OCCCC STCOOQWBFONSKY-UHFFFAOYSA-N 0.000 claims abstract description 222
- 239000003350 kerosene Substances 0.000 claims abstract description 92
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 50
- 229910001868 water Inorganic materials 0.000 claims abstract description 48
- 229910002651 NO3 Inorganic materials 0.000 claims abstract description 36
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims abstract description 36
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 35
- 239000003960 organic solvent Substances 0.000 claims abstract description 14
- 238000000926 separation method Methods 0.000 claims description 117
- 239000011552 falling film Substances 0.000 claims description 112
- 239000012071 phase Substances 0.000 claims description 80
- 238000010992 reflux Methods 0.000 claims description 73
- 238000010438 heat treatment Methods 0.000 claims description 60
- 239000002253 acid Substances 0.000 claims description 44
- 238000000605 extraction Methods 0.000 claims description 35
- 230000008569 process Effects 0.000 claims description 33
- 238000009833 condensation Methods 0.000 claims description 29
- 230000005494 condensation Effects 0.000 claims description 29
- 238000003608 radiolysis reaction Methods 0.000 claims description 29
- 238000002156 mixing Methods 0.000 claims description 21
- 238000005070 sampling Methods 0.000 claims description 19
- 239000007791 liquid phase Substances 0.000 claims description 17
- 239000002699 waste material Substances 0.000 claims description 14
- 238000007599 discharging Methods 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 13
- 238000001704 evaporation Methods 0.000 claims description 11
- 230000008020 evaporation Effects 0.000 claims description 11
- 238000003756 stirring Methods 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 10
- 230000001174 ascending effect Effects 0.000 claims description 9
- 239000012074 organic phase Substances 0.000 claims description 9
- 239000008346 aqueous phase Substances 0.000 claims description 7
- 238000004064 recycling Methods 0.000 claims description 7
- 239000000945 filler Substances 0.000 claims description 6
- 150000003839 salts Chemical class 0.000 claims description 6
- 238000004062 sedimentation Methods 0.000 claims description 5
- 238000005352 clarification Methods 0.000 claims description 4
- 238000002386 leaching Methods 0.000 claims description 4
- 239000003758 nuclear fuel Substances 0.000 claims description 4
- 238000005191 phase separation Methods 0.000 claims description 3
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 239000011364 vaporized material Substances 0.000 claims description 3
- 230000006641 stabilisation Effects 0.000 claims description 2
- 238000011105 stabilization Methods 0.000 claims description 2
- 238000009835 boiling Methods 0.000 abstract description 10
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 238000005979 thermal decomposition reaction Methods 0.000 abstract description 6
- 239000000047 product Substances 0.000 description 88
- 239000007789 gas Substances 0.000 description 37
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 14
- 229910019142 PO4 Inorganic materials 0.000 description 13
- 235000021317 phosphate Nutrition 0.000 description 13
- 238000000354 decomposition reaction Methods 0.000 description 12
- 239000010452 phosphate Substances 0.000 description 11
- -1 butanol Chemical compound 0.000 description 8
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 8
- NEAQRZUHTPSBBM-UHFFFAOYSA-N 2-hydroxy-3,3-dimethyl-7-nitro-4h-isoquinolin-1-one Chemical compound C1=C([N+]([O-])=O)C=C2C(=O)N(O)C(C)(C)CC2=C1 NEAQRZUHTPSBBM-UHFFFAOYSA-N 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 6
- NLSCHDZTHVNDCP-UHFFFAOYSA-N caesium nitrate Chemical compound [Cs+].[O-][N+]([O-])=O NLSCHDZTHVNDCP-UHFFFAOYSA-N 0.000 description 6
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 6
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 description 6
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- 125000000217 alkyl group Chemical group 0.000 description 4
- 230000007935 neutral effect Effects 0.000 description 4
- 150000002828 nitro derivatives Chemical class 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 230000000630 rising effect Effects 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 150000001735 carboxylic acids Chemical class 0.000 description 3
- 239000007857 degradation product Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000004992 fission Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000002901 radioactive waste Substances 0.000 description 3
- 235000010344 sodium nitrate Nutrition 0.000 description 3
- 239000004317 sodium nitrate Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- JYFHYPJRHGVZDY-UHFFFAOYSA-N Dibutyl phosphate Chemical compound CCCCOP(O)(=O)OCCCC JYFHYPJRHGVZDY-UHFFFAOYSA-N 0.000 description 2
- 229910052778 Plutonium Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 229910052770 Uranium Inorganic materials 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- BNMJSBUIDQYHIN-UHFFFAOYSA-N butyl dihydrogen phosphate Chemical compound CCCCOP(O)(O)=O BNMJSBUIDQYHIN-UHFFFAOYSA-N 0.000 description 2
- 238000011033 desalting Methods 0.000 description 2
- 150000002823 nitrates Chemical class 0.000 description 2
- 150000002826 nitrites Chemical class 0.000 description 2
- 229940082615 organic nitrates used in cardiac disease Drugs 0.000 description 2
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 2
- 238000007781 pre-processing Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000000638 solvent extraction Methods 0.000 description 2
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 2
- 238000005292 vacuum distillation Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229910002089 NOx Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000000622 liquid--liquid extraction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910001960 metal nitrate Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 239000002915 spent fuel radioactive waste Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
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- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
Abstract
The invention discloses a radioactive organic waste liquid recovery method and a recovery device used by the same, wherein the recovery method comprises the following steps: 1) Firstly, the radioactive organic waste liquid is pretreated to remove insoluble water phase and suspended matters in the radioactive organic waste liquid, and excessive nitrate and nitric acid are eluted; 2) Removing the radiolytic light products, the radionuclides and the radiolytic heavy products to obtain vaporized organic steam; 3) And (3) carrying out vacuum rectification treatment on the vaporized organic steam, and separating to obtain tributyl phosphate and kerosene. The recovery method of the invention not only can recover the organic solvent, but also greatly reduces the final disposal amount of the radioactive organic waste liquid, reduces disposal difficulty and saves disposal and operation cost. The invention greatly reduces the temperature of the rectification system, realizes the recovery and reuse of tributyl phosphate and kerosene in the radioactive organic waste liquid at a non-boiling point temperature, avoids the thermal decomposition reaction of tributyl phosphate, nitric acid, nitrate and the like at high temperature, improves the operation safety of the system and saves the energy consumption.
Description
Technical Field
The invention belongs to the technical field of cores, and particularly relates to a radioactive organic waste liquid recovery method and a recovery device used by the same.
Background
The nuclear fuel post-treatment plant mostly adopts a PUREX solvent extraction process, uses tributyl phosphate (TBP) as an extractant, and uses hydrocarbon as a diluent, such as kerosene, to extract and separate uranium and plutonium in spent fuel. During the extraction, the organic solvent is degraded under the action of physical, chemical and radiolysis to produce radiolytic light products (primary degradation products of TBP and kerosene, such as butanol, HDBP, H) 2 MBP, carboxylic acid, organic nitrate, nitrite, nitro compound, hydroxamic acid, etc.) and radiolytic heavy products (primary products polymerize with each other and complex with fission products to form a series of heavy radiolytic products, such as long-chain alkyl phosphate, metal organic complex, etc.), so that the extraction effect is gradually reduced, finally the requirements cannot be met, and solvent washing regeneration is needed. However, as the number of cycles increases, conventional caustic wash means do not meet the regeneration requirements and require further purification of the deteriorated solvent. Rectification is generally employed. The rectification is a separation process according to different volatilities of different substances, and not only does not introduce new reagents, but also canThe radiolytic product, nuclide and organic solvent are separated to achieve the purpose of recycling.
The Purex procedure is based on liquid-liquid extraction between concentrated aqueous nitric acid and an organic solvent. In the extraction process, tributyl phosphate (TBP) has high solubility to uranium and plutonium and has a certain extraction effect to nitrate, and can form a complex with the nitrate. Thus, the radioactive organic waste liquid has a composition other than the radiolytic product of not only TBP, kerosene, but also nitrate and nitric acid. The research shows that pure TBP is stable at high temperature, and when nitrogen oxides (nitric acid, metal nitrate and NOx) exist, obvious decomposition effect is caused to TBP, so that the working temperature is reduced sharply. For example, when varying proportions of NO are added to the TBP 2 Then, the decomposition temperature of TBP is reduced to 80-90 ℃, and black substances with complex components are generated; in the absence of HNO 3 In the presence of TBP at 225
No decomposition phenomenon is found in the temperature of HNO 3 The addition of (2) can obviously promote TBP decomposition, and the higher the nitric acid concentration is, the lower the TBP decomposition temperature is; TBP interacts to form nitro compounds at temperatures above 100 ℃ in the presence of nitrates and undergoes severe decomposition or even explosion when temperatures exceed 130 ℃. Therefore, the operation process needs to be controlled at a lower temperature, so that TBP decomposition and even safety accidents are avoided. However, TBP is a high boiling point substance, and even if the boiling point reaches 141 ℃ under a vacuum of 500Pa at atmospheric pressure, it still generates a significant decomposition reaction, and it is not economical to continue to reduce the operating temperature by reducing the pressure on an industrial scale.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a radioactive organic waste liquid recovery method and a recovery device used by the method, which slow down the decomposition reaction of TBP with substances such as nitrate, acid and the like in the rectification process, reduce the separation temperature, realize the recovery and reuse of tributyl phosphate (TBP) and kerosene in the radioactive organic waste liquid at a non-boiling point temperature, and realize the volume reduction of radioactive waste.
The technical scheme adopted for solving the technical problems of the invention is to provide a method for recovering radioactive organic waste liquid, wherein the radioactive organic waste liquid comprises the following components: tributyl phosphate (TBP), kerosene, radiolytic light products, radiolytic heavy products, radionuclides, insoluble aqueous phase, suspended matter, nitrate, nitric acid, water, suspended matter, the recovery process comprising the steps of:
1) Firstly, the radioactive organic waste liquid is pretreated to remove insoluble water phase and suspended matters in the radioactive organic waste liquid, and excessive nitrate and nitric acid are eluted;
2) Removing the radiolytic light products, the radionuclides and the radiolytic heavy products to obtain vaporized organic steam;
3) And (3) carrying out vacuum rectification treatment on the vaporized organic steam, and separating to obtain tributyl phosphate and kerosene.
The radiolytic light products are tributyl phosphate (TBP) and the primary degradation products of kerosene, such as butanol, monobutyl phosphate (HDBP), dibutyl phosphate (H2 MBP), carboxylic acids, organic nitrates, nitrites, nitro compounds, hydroxamic acids, and the like. The radiolytic heavy products are primary products that polymerize with each other and complex with fission products to form a series of heavy radiolytic products, such as long chain alkyl phosphates, metal organic complexes, and the like.
Preferably, the step 1) specifically comprises: in a mixer-settler, stirring, mixing and clarifying the radioactive organic waste liquid by using a dilute nitric acid solution with a first concentration, and discharging and removing insoluble water phase and suspended matters and dissolved excessive nitrate and nitric acid carried in the radioactive organic waste liquid into the water phase waste liquid;
the step 2) is specifically as follows: the radioactive organic waste liquid after pretreatment is sent into a vertical feed liquid preheater, the feed liquid preheater is operated under the conditions of a first heating temperature and a first pressure, the radioactive organic waste liquid flows from top to bottom in the inner wall of a heating pipe of the feed liquid preheater, the radioactive organic waste liquid contains a radiation decomposition light product, a small amount of dissolved water and dissolved acid which are vaporized in the process, and reversely flows upwards, is discharged from a pipe orifice at the top end of an upper end enclosure of the feed liquid preheater and is discharged to a vacuum system after passing through a condensation cooler, condensate is discharged into a light oil phase tank, the preheated radioactive organic waste liquid is sent into a falling film evaporator, the falling film evaporator is operated under the conditions of a second heating temperature and a second pressure, the radioactive organic waste liquid flows from top to bottom in the heating pipe of the falling film evaporator, kerosene and tributyl phosphate (TBP) in the radioactive organic waste liquid are vaporized in the process, and the vaporized organic steam and unvaporized liquid flow downwards in parallel, and the gas enters a separation chamber of the falling film evaporator; the liquid enters a residual liquid circulation tank, is pumped back to an upper end socket circulation feed liquid inlet of the falling film evaporator by a residual liquid circulation pump, is circularly evaporated, and radiolytic heavy products and radionuclides in radioactive organic waste liquid are left in unvaporized liquid phase and are discharged as residual liquid, and vaporized organic steam enters a vacuum rectifying tower after entrained liquid drops are separated in a separation chamber of the falling film evaporator;
The step 3) is specifically as follows: the vacuum rectifying tower operates under the third temperature and the third pressure, vaporized organic steam entering the tower from the feeding port of the vacuum rectifying tower is continuously condensed in the ascending process, liquid drops fall into a tower kettle reboiler, after being heated by the tower kettle reboiler, part of the liquid drops are changed into organic steam again, mass transfer is carried out with the falling liquid drops, the liquid drops are discharged from the top of the vacuum rectifying tower together with the non-condensed organic steam, the organic steam extracted from the gas phase outlet of the top of the vacuum rectifying tower is condensed, after the condensed organic steam is condensed to the fourth temperature, the condensate is returned to the vacuum rectifying tower as reflux liquid for circulation, the reflux liquid and the organic steam in the vacuum rectifying tower are subjected to mass transfer in the vacuum rectifying tower, so that the content of tributyl phosphate (TBP) in the ascending organic steam is reduced, part of the condensate is extracted after the content of tributyl phosphate (TBP) in the condensate is reduced to the second concentration, the condensate is extracted, the condensate is continuously circulated in a reflux mode, the liquid in the tower is subjected to the liquid extraction tank, and when the content of tributyl phosphate (TBP) in the tower reaches the third concentration, the content of tributyl phosphate in the phosphoric acid is extracted by the tributyl phosphate cooling tower, and the tributyl phosphate is extracted by the cooling tower.
Preferably, tributyl phosphate (TBP) is supplemented to the outlet of the separation chamber of the falling film evaporator from the tower kettle reboiler, so as to balance the stabilization of the liquid level at the bottom of the heating chamber of the falling film evaporator and wash and purify the gas phase vaporized in the heating chamber of the falling film evaporator in the separation chamber of the falling film evaporator.
Preferably, the first concentration in the step 1) is 0.01-0.02 mol/L;
the first heating temperature in the step 2) is 80-110 ℃, and the first pressure is 4-8 kPa absolute pressure;
the second heating temperature is 105-125 ℃, and the second pressure is 0.3-1.0 kPa absolute pressure.
Preferably, the third temperature in the step 3) includes: the third temperature of the top of the vacuum rectifying tower is 60-75 ℃, the third temperature of the bottom of the vacuum rectifying tower is 100-125 ℃, and the third pressure comprises: the third pressure at the top of the vacuum rectifying tower is 0.15-0.5kPa, and the third pressure at the bottom of the vacuum rectifying tower is 0.4-1.1kPa.
Preferably, the fourth temperature is 5-20deg.C, the second concentration is that tributyl phosphate content in condensate is less than or equal to 0.02wt%, and the third concentration is that tributyl phosphate (TBP) content in sample is more than or equal to 80wt%.
Preferably, the radioactive organic waste liquid is waste tributyl phosphate-kerosene mixed organic waste liquid generated by a nuclear fuel post-treatment plant.
The invention also provides a recovery device for the radioactive organic waste liquid recovery method, which comprises the following steps:
the pretreatment unit is used for carrying out sedimentation separation on insoluble water phase and suspended matters in the radioactive organic waste liquid, and eluting nitrate and nitric acid;
the radiolytic product separation unit is connected with the pretreatment unit and is used for removing radiolytic light products, radionuclides and radiolytic heavy products;
the tributyl phosphate (TBP) and kerosene separating unit is connected with the radiolysis product separating unit and is used for carrying out vacuum rectification treatment on the organic solvent treated by the radiolysis product separating unit to separate tributyl phosphate and kerosene.
Preferably, the preprocessing unit includes: a feed liquid receiving tank, a feed liquid conveying pump, a mixing clarifying tank and a discharging pump,
the material liquid receiving tank, the material liquid conveying pump, the mixing clarifying tank and the discharging pump are connected in sequence through pipelines, and the discharging pump is connected to the radiolytic product separation unit;
the radioactive organic waste liquid is subjected to mixing, stirring and clarification pretreatment in a mixer-settler to remove insoluble water phase and suspended matters and reduce the salt content and the acidity content.
Preferably, the mixer-settler is a two-stage mixer-settler, and the flow ratio of the organic phase to the dilute acid in the mixer-settler is (10-20): 1.
Preferably, the radiolytic product separation unit comprises: the device comprises a feed liquid preheater, a feed tank, a feed pump, a condensation cooler, a light oil phase tank, a falling film evaporator, a residual liquid circulation tank, a residual liquid circulation pump and a residual liquid tank;
the upstream of the feed liquid preheater is connected with the pretreatment unit, the outlet of the feed liquid preheater is connected with the feed tank, the gas phase outlet of the upper end socket of the feed liquid preheater is connected with the condensation cooler, the outlet of the condensation cooler is connected with the light oil phase tank, and the non-condensing outlet of the condensation cooler is connected with the vacuum system; the feed tank, the feed pump and the falling film evaporator are connected in sequence through pipelines; the heating chamber and the liquid phase outlet of the separation chamber of the falling film evaporator are connected with a residual liquid circulation tank, the outlet of the residual liquid circulation tank is connected with a residual liquid circulation pump, and the outlet of the residual liquid circulation pump is respectively connected to a residual liquid tank and a circulating feed liquid inlet of an upper end socket of the falling film evaporator through pipelines; a gas phase outlet of a separation chamber of the falling film evaporator is connected with tributyl phosphate (TBP) and a kerosene separation unit; the outlet of the residual liquid circulating pump is provided with a sampling port;
after the pretreated organic waste liquid enters a feed liquid preheater for preheating, the radiolytic light products, at least the preset content of dissolved water and dissolved acid are removed, the organic waste liquid enters a heating chamber of a falling film evaporator for circular evaporation, the radionuclides and the radiolytic heavy products are left in a liquid phase, and the purified organic steam is discharged from a gas phase outlet of a separation chamber and enters a tributyl phosphate (TBP) and kerosene separation unit.
Preferably, the falling film evaporator comprises a heating chamber and a separation chamber, wherein the materials are sent into the falling film evaporator from the upper part of the heating chamber, flow downwards in a film-forming manner along the inner wall of a heat exchange pipe in the heating chamber and are partially vaporized along a pipe side, a part of the materials which are not vaporized in the heating chamber are circularly sent into an inlet of the falling film evaporator, and the rest parts are discharged as residual liquid; the vaporized material is sucked into a gas phase separation chamber of the falling film evaporator by downstream vacuum; the top of the separation chamber is provided with a filler and a liquid distributor, which are used for purifying radionuclides and radiolysis products carried by the separation chamber, and the liquid distributor is arranged above the filler.
Preferably, the tributyl phosphate (TBP) and kerosene separation unit comprises: a vacuum rectifying tower, a tower kettle reboiler, a tower kettle extraction pump, a tributyl phosphate (TBP) fraction cooler, a tributyl phosphate (TBP) receiving tank, a tower top condensation cooler, a gas-liquid separation tank, a tower top reflux pump and a kerosene receiving tank;
the vacuum rectifying tower feed inlet is connected with a gas phase outlet of the radiolysis product separation unit, and the vacuum rectifying tower top gas phase outlet, the tower top condensation cooler, the tower top reflux tank and the tower top reflux pump are connected in sequence through pipelines; the non-condensing outlet of the condensing cooler at the top of the tower is connected with a gas-liquid separation tank, and the gas-phase outlet of the gas-liquid separation tank is connected with a vacuum system; the liquid phase outlet of the gas-liquid separation tank is connected with the tower top reflux tank; the outlet of the tower top reflux pump is connected with a reflux port of the vacuum rectifying tower and a kerosene receiving tank, and a sampling port is arranged on a connecting pipeline between the outlet of the tower top reflux pump and the kerosene receiving tank; the lower outlet of the vacuum rectifying tower kettle, the tower kettle reboiler, the tower kettle extraction pump, the tributyl phosphate (TBP) fraction cooler and the tributyl phosphate (TBP) receiving tank are connected in sequence through pipelines; the gas phase outlet of the tower kettle reboiler is connected with the tower kettle of the vacuum rectifying tower; the tower kettle extraction pump outlet pipeline is provided with a branch and is connected with the radiolysis product separation unit; a tributyl phosphate (TBP) fraction cooler and a tributyl phosphate (TBP) receiving tank connecting pipeline are provided with sampling ports;
The gas phase outlet of the top of the vacuum rectifying tower is connected with a tower top condensation cooler, the extracted kerosene steam flows to a tower top reflux tank after being condensed and cooled, one part of the kerosene steam is returned into the tower as reflux liquid by a tower top reflux pump, and the other part of the kerosene steam enters a kerosene receiving tank; the outlet of the tower kettle reboiler is connected with the tower kettle extraction pump, and the extracted TBP enters the TBP receiving tank after passing through the TBP fraction cooler or returns to the liquid phase feed inlet at the upper end of the falling film evaporator.
Preferably, the vacuum rectifying tower is a vacuum packed rectifying tower, and the vacuum rectifying tower comprises: the rectifying separation zone and the stripping separation zone are arranged above the rectifying separation zone, the tower columns of each zone are connected through flanges, the separating level of the rectifying separation zone is 3-8, and the separating level of the stripping separation zone is 1-5.
Preferably, the radioactive organic waste liquid is fed in a continuous feeding mode, the radiolytic light products are continuously extracted, and kerosene, TBP and radiolytic heavy products are continuously extracted or intermittently extracted.
Compared with the existing process conditions, the radioactive organic waste liquid recovery method and the recovery device used by the method can recover the organic solvent, greatly reduce the final treatment amount of the radioactive organic waste liquid (the volume reduction ratio can reach 100:1), reduce the treatment difficulty and save the treatment and operation costs. The invention greatly reduces the temperature of the rectification system, realizes the recovery and reuse of tributyl phosphate (TBP) and kerosene in the radioactive organic waste liquid at a non-boiling point temperature, avoids the thermal decomposition reaction of tributyl phosphate (TBP) with nitric acid, nitrate and the like at a high temperature, improves the operation safety of the system and saves the energy consumption.
Drawings
FIG. 1 is a schematic view showing the structure of a recovery apparatus used in the method for recovering radioactive organic waste liquid in example 2 of the present invention.
In the figure: v1-feed liquid receiving tank, P1-feed liquid conveying pump, V2-acid washing desalting tank, P2-discharging pump, E1-feed liquid preheater, E2-condensing cooler, V3-light oil phase tank, V4-feed tank, P3-feed pump, E3-falling film evaporator, V6-raffinate circulating tank, P4-raffinate circulating pump, V5-raffinate tank, T1-vacuum rectifying tower, E4-tower kettle reboiler, P5-tower kettle extracting pump, E6-tributyl phosphate (TBP) fraction cooler, V9-tributyl phosphate (TBP) receiving tank, E5-tower top condensing cooler, F1-gas-liquid separating tank, V7-tower top reflux tank, P6-tower top reflux pump, V8-kerosene receiving tank, T1-rectifying separation zone, T1-2-rectifying separation zone, A1-vacuum rectifying tower reflux line sampling port, A2-tributyl phosphate (TBP) component line sampling port, A3-sampling port
And a sampling port of a rectification residual liquid pipeline.
Detailed Description
The present invention will be described in further detail below with reference to the drawings and detailed description for the purpose of better understanding of the technical solution of the present invention to those skilled in the art.
Embodiments of the present patent are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present patent and are not to be construed as limiting the present patent.
In the description of this patent, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the patent and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a particular orientation, be configured and operated in a particular orientation, and are therefore not to be construed as limiting the patent.
In the description of this patent, it should be noted that, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "disposed" are to be construed broadly, and may be fixedly connected, disposed, detachably connected, disposed, or integrally connected, disposed, for example. The specific meaning of the terms in this patent will be understood by those of ordinary skill in the art as the case may be.
Example 1
The embodiment provides a method for recovering radioactive organic waste liquid, the radioactive organic waste liquid includes: tributyl phosphate (TBP), kerosene, radiolytic light products, radiolytic heavy products, radionuclides, insoluble aqueous phase, suspended matter, nitrate, nitric acid, water, suspended matter, the recovery process comprising the steps of:
1) Firstly, the radioactive organic waste liquid is pretreated to remove insoluble water phase and suspended matters in the radioactive organic waste liquid, and excessive nitrate and nitric acid are eluted;
2) Removing the radiolytic light products, the radionuclides and the radiolytic heavy products to obtain vaporized organic steam;
3) And (3) carrying out vacuum rectification treatment on the vaporized organic steam, and separating to obtain tributyl phosphate and kerosene.
The embodiment also provides a recovery device for the radioactive organic waste liquid recovery method, which comprises:
the pretreatment unit is used for carrying out sedimentation separation on insoluble water phase and suspended matters in the radioactive organic waste liquid, and eluting nitrate and nitric acid;
the radiolytic product separation unit is connected with the pretreatment unit and is used for removing radiolytic light products, radionuclides and radiolytic heavy products;
the tributyl phosphate (TBP) and kerosene separating unit is connected with the radiolysis product separating unit and is used for carrying out vacuum rectification treatment on the organic solvent treated by the radiolysis product separating unit to separate tributyl phosphate and kerosene.
Compared with the existing process conditions, the radioactive organic waste liquid recovery method and the recovery device used by the same not only can recover the organic solvent, but also greatly reduce the final treatment amount of the radioactive organic waste liquid (the volume reduction ratio can reach 100:1), reduce the treatment difficulty and save the treatment and operation costs. According to the embodiment, the temperature of the rectification system is greatly reduced, the recovery and reuse of tributyl phosphate (TBP) and kerosene in radioactive organic waste liquid are realized at a non-boiling point temperature, the thermal decomposition reaction of tributyl phosphate (TBP) with nitric acid, nitrate and the like at a high temperature is avoided, the operation safety of the system is improved, and the energy consumption is saved.
Example 2
The embodiment provides a method for recovering radioactive organic waste liquid, the radioactive organic waste liquid includes: tributyl phosphate (TBP), kerosene, radiolytic light products, radiolytic heavy products, radionuclides, insoluble aqueous phase, suspensions, nitrates, nitric acid, the recovery process comprising the steps of:
1) Firstly, the radioactive organic waste liquid is pretreated to remove insoluble water phase and suspended matters in the radioactive organic waste liquid, and excessive nitrate and nitric acid are eluted;
2) Removing the radiolytic light products, the radionuclides and the radiolytic heavy products to obtain vaporized organic steam;
3) And (3) carrying out vacuum rectification treatment on the vaporized organic steam, and separating to obtain tributyl phosphate and kerosene.
The radiolytic light products are tributyl phosphate (TBP) and the primary degradation products of kerosene, such as butanol, monobutyl phosphate (HDBP), dibutyl phosphate (H2 MBP), carboxylic acids, organic nitrates, nitrites, nitro compounds, hydroxamic acids, and the like. The radiolytic heavy products are primary products that polymerize with each other and complex with fission products to form a series of heavy radiolytic products, such as long chain alkyl phosphates, metal organic complexes, and the like.
Specifically, in this embodiment, the radioactive organic waste liquid is pretreated, insoluble water phase and suspended matters in the organic waste liquid are subjected to sedimentation separation, and extracted nitrate and acid are subjected to back extraction to reduce the concentration; then sequentially removing the radiolytic light products, a small amount of dissolved water, dissolved acid, radionuclide and the radiolytic heavy products, and then carrying out vacuum rectification treatment to obtain TBP and kerosene.
Specifically, the radiolytic light products in step 2) include: nitrate, nitrite, hydroxamic acid, radionuclides include: se-79, sr-90, pu-239, U-235, radiolytic heavy products include: long-chain acid phosphate, acid tributyl phosphate, long-chain alkyl neutral phosphate.
Preferably, the step 1) specifically comprises: in a mixer-settler, stirring, mixing and clarifying the radioactive organic waste liquid by using a dilute nitric acid solution with a first concentration, and discharging and removing insoluble water phase and suspended matters and dissolved excessive nitrate and nitric acid carried in the radioactive organic waste liquid into the water phase waste liquid;
the step 2) is specifically as follows: the radioactive organic waste liquid after pretreatment is sent into a vertical feed liquid preheater, the feed liquid preheater is operated under the conditions of a first heating temperature and a first pressure, the radioactive organic waste liquid flows from top to bottom in the inner wall of a heating pipe of the feed liquid preheater, the radioactive organic waste liquid contains a radiation decomposition light product, a small amount of dissolved water and dissolved acid which are vaporized in the process, and reversely flows upwards, is discharged from a pipe orifice at the top end of an upper end enclosure of the feed liquid preheater and is discharged to a vacuum system after passing through a condensation cooler, condensate is discharged into a light oil phase tank, the preheated radioactive organic waste liquid is sent into a falling film evaporator, the falling film evaporator is operated under the conditions of a second heating temperature and a second pressure, the radioactive organic waste liquid flows from top to bottom in the heating pipe of the falling film evaporator, kerosene and tributyl phosphate (TBP) in the radioactive organic waste liquid are vaporized in the process, and the vaporized organic steam and unvaporized liquid flow downwards in parallel, and the gas enters a separation chamber of the falling film evaporator; the liquid enters a residual liquid circulation tank, is pumped back to an upper end socket circulation feed liquid inlet of the falling film evaporator by a residual liquid circulation pump, is circularly evaporated, and radiolytic heavy products and radionuclides in radioactive organic waste liquid are left in unvaporized liquid phase and are discharged as residual liquid, and vaporized organic steam enters a vacuum rectifying tower after entrained liquid drops are separated in a separation chamber of the falling film evaporator;
The step 3) is specifically as follows: the vacuum rectifying tower operates under the third temperature and the third pressure, vaporized organic steam entering the tower from the feeding port of the vacuum rectifying tower is continuously condensed in the ascending process, liquid drops fall into a tower kettle reboiler, after being heated by the tower kettle reboiler, part of the liquid drops are changed into organic steam again, mass transfer is carried out with the falling liquid drops, the liquid drops are discharged from the top of the vacuum rectifying tower together with the non-condensed organic steam, the organic steam extracted from the gas phase outlet of the top of the vacuum rectifying tower is condensed, after the condensed organic steam is condensed to the fourth temperature, the condensate is returned to the vacuum rectifying tower as reflux liquid for circulation, the reflux liquid and the organic steam in the vacuum rectifying tower are subjected to mass transfer in the vacuum rectifying tower, so that the content of tributyl phosphate (TBP) in the ascending organic steam is reduced, part of the condensate is extracted after the content of tributyl phosphate (TBP) in the condensate is reduced to the second concentration, the condensate is extracted, the condensate is continuously circulated in a reflux mode, the liquid in the tower is subjected to the liquid extraction tank, and when the content of tributyl phosphate (TBP) in the tower reaches the third concentration, the content of tributyl phosphate in the phosphoric acid is extracted by the tributyl phosphate cooling tower, and the tributyl phosphate is extracted by the cooling tower.
Preferably, the outlet of the tower kettle reboiler is simultaneously introduced into a liquid supplementing pipe at the inlet of the falling film reboiler, a high-concentration tributyl phosphate (TBP) is supplemented to the outlet of the separation chamber of the falling film evaporator from the inside of the tower kettle reboiler, a high-concentration TBP component is supplemented when the falling film evaporator is continuously or at a low liquid level, the high-concentration TBP component is used for balancing the stability of the liquid level at the bottom of the heating chamber of the falling film evaporator, and the gas phase vaporized in the heating chamber of the falling film evaporator is leached and purified in the separation chamber of the falling film evaporator.
Preferably, the first concentration in the step 1) is 0.01-0.02 mol/L;
the first heating temperature in the step 2) is 80-110 ℃, and the first pressure is 4-8 kPa absolute pressure;
the second heating temperature is 105-125 ℃, and the second pressure is 0.3-1.0 kPa absolute pressure.
Preferably, the third temperature in the step 3) includes: the third temperature of the top of the vacuum rectifying tower is 60-75 ℃, the third temperature of the bottom of the vacuum rectifying tower is 100-125 ℃, and the third pressure comprises: the third pressure at the top of the vacuum rectifying tower is 0.15-0.5kPa, and the third pressure at the bottom of the vacuum rectifying tower is 0.4-1.1kPa.
Preferably, the fourth temperature is 5-20deg.C, the second concentration is that tributyl phosphate content in condensate is less than or equal to 0.02wt%, and the third concentration is that tributyl phosphate (TBP) content in sample is more than or equal to 80wt%.
Preferably, the radioactive organic waste liquid is waste tributyl phosphate-kerosene mixed organic waste liquid generated by a nuclear fuel post-treatment plant.
Specifically, this embodiment provides a method for recovering radioactive organic waste liquid, as shown in fig. 1, including the following steps:
s201, in a mixer-settler, carrying out two-stage mixing, stirring and clarifying treatment on the radioactive organic waste liquid and 0.02mol/L dilute nitric acid in a countercurrent manner, and separating insoluble water phase, suspended matters, excessive nitrate and extraction acid in the radioactive organic waste liquid, wherein the ratio of an organic phase to an aqueous phase is 20:1.
s202, the treated radioactive organic waste liquid is sent into a vertical feed liquid preheater. In the embodiment, the operation temperature of the feed liquid preheater is 80 ℃, the operation pressure is 4kPa absolute, the radioactive organic waste liquid flows from top to bottom on the inner wall of the heating pipe, the contained radiolysis produces light products (such as nitrate, nitrite, hydroxamic acid and the like), a small amount of dissolved water and dissolved acid are vaporized in the process, and the dissolved water and the dissolved acid are discharged from the pipe orifice at the top end of the upper end enclosure of the feed liquid preheater in the reverse direction, and are cooled to 20 ℃ by the condensing cooler, and then are discharged to a vacuum system without condensing, and the condensate automatically flows into a light oil phase tank. And sending the preheated radioactive organic waste liquid to a falling film evaporator for circular evaporation. The operation temperature of the falling film evaporator is 114 ℃, the operation pressure is absolute pressure of 0.6kPa, the radioactive organic waste liquid flows from top to bottom in the heating pipe of the falling film evaporator, and kerosene and TBP are vaporized in the process. The vaporized organic steam and unvaporized liquid flow downwards, and the gas enters a separation chamber of a falling film evaporator for separation and purification of entrained nuclides and then enters a vacuum rectifying tower; the unvaporized liquid enters a residual liquid circulation tank, the unvaporized liquid is enriched with radiolytic heavy products (such as long-chain acid phosphate, acid tributyl phosphate, long-chain alkyl neutral phosphate and the like) and radionuclides (such as Se-79, sr-90, pu-239, U-235 and the like) in the radioactive organic waste liquid, one part of unvaporized liquid is pumped back to a circulating feed liquid inlet of an upper seal head of the falling film evaporator by a residual liquid circulation pump, the circulating evaporation is carried out, the minimum liquid amount required by the operation of the falling film evaporator is ensured, and the other part of unvaporized liquid is continuously or intermittently discharged as residual liquid.
S203, the operating temperature of the vacuum rectifying tower in the embodiment is 64-118 ℃, and the operating pressure is 0.3-0.8 kPa. Specifically, the operation temperature of the tower kettle is 118 ℃, the operation pressure is 0.8kPa absolute, the operation temperature of the tower top is 64 ℃, and the operation pressure is 0.3kPa absolute. Organic steam entering the vacuum rectifying tower from the feeding port of the vacuum rectifying tower is continuously condensed in the rising process, and liquid drops fall into a reboiler of the tower kettle. After being heated by the tower kettle reboiler, a part of the organic vapor is changed into organic vapor again, mass transfer is carried out with the falling liquid drops, and the organic vapor and the uncondensed organic vapor are discharged from the top of the vacuum rectifying tower. And condensing the organic steam extracted from the gas phase outlet at the top of the vacuum rectifying tower, and returning the condensate to the vacuum rectifying tower as reflux liquid for reflux circulation after condensing and cooling to 20 ℃, wherein the reflux liquid and the organic steam in the vacuum rectifying tower are subjected to mass transfer in the vacuum rectifying tower, so that the TBP content in the ascending organic steam is reduced. And after repeated circulation until the TBP content in the condensate is reduced to less than or equal to 0.02wt%, extracting part of condensate, and delivering the part of condensate to a kerosene receiving tank, wherein the part of condensate is the kerosene. The other part of the condensate continues to be recirculated. In this example, the reflux ratio (i.e., the ratio of the flow rate of condensate returned to the vacuum distillation column (T1) to the flow rate of condensate drawn out to the kerosene receiving tank (V8)) was 1. Sampling liquid left in the tower kettle reboiler, and when the TBP content is more than or equal to 80wt%, extracting by a tower kettle extraction pump, wherein the part of liquid is the TBP. The extracted TBP is cooled to 40 ℃ by a TBP fraction cooler and then enters a TBP receiving tank. Meanwhile, a high-concentration TBP component is supplemented to the outlet of the separation chamber of the falling film evaporator from the reboiler of the tower kettle, so as to balance the stability of the liquid level at the bottom of the heating chamber of the falling film evaporator; and leaching and purifying the gas phase vaporized in the heating chamber of the falling film evaporator in the separation chamber.
As shown in fig. 1, this embodiment also provides a recovery device for the above-mentioned method for recovering radioactive organic waste liquid, which includes:
the pretreatment unit is used for carrying out sedimentation separation on insoluble water phase and suspended matters in the radioactive organic waste liquid, and eluting nitrate and nitric acid;
the radiolytic product separation unit is connected with the pretreatment unit and is used for removing radiolytic light products, radionuclides and radiolytic heavy products;
the tributyl phosphate (TBP) and kerosene separating unit is connected with the radiolysis product separating unit and is used for carrying out vacuum rectification treatment on the organic solvent treated by the radiolysis product separating unit to separate tributyl phosphate and kerosene.
Specifically, the pretreatment unit in this embodiment is used for settling separation of insoluble water phase and suspended matters in the radioactive organic waste liquid; and (3) carrying out back extraction separation on extraction salt and extraction acid in the radioactive organic waste liquid.
The radiolysis product separation unit is used for separating radiolysis products from most nuclides, a small amount of dissolved water and dissolved acid in the radioactive organic waste liquid. Firstly, the mixture enters a feed liquid preheater to remove radiolytic light products, then enters a falling film evaporator, and radionuclides and radiolytic heavy products are separated in a heating chamber of the falling film evaporator.
Tributyl phosphate (TBP) and kerosene separating unit for vacuum rectifying the vaporized gas phase in the separating chamber of falling film evaporator, recovering kerosene in the top of the vacuum rectifying tower and recovering TBP in the bottom of the tower.
Preferably, the preprocessing unit includes: a feed liquid receiving tank (V1), a feed liquid conveying pump (P1), a mixing clarifying tank (V2) and a discharging pump (P2),
the material liquid receiving tank (V1), the material liquid conveying pump (P1), the mixing clarifying tank (V2) and the discharging pump (P2) are connected in sequence through pipelines, and an outlet of the discharging pump (P2) is connected to the radiolytic product separation unit;
the radioactive organic waste liquid is subjected to mixing, stirring and clarification pretreatment in a mixing and clarifying tank (V2) to remove insoluble water phase and suspended matters and reduce the salt content and the acidity content.
Preferably, the mixer-settler (V2) is a two-stage mixer-settler, in which the flow ratio of the organic phase to the dilute acid is (10-20): 1.
Preferably, the radiolytic product separation unit comprises: a feed liquid preheater (E1), a feed tank (V4), a feed pump (P3), a condensation cooler (E2), a light oil phase tank (V3), a falling film evaporator (E3), a raffinate circulation tank (V6), a raffinate circulation pump (P4) and a raffinate tank (V5);
the upstream of the feed liquid preheater (E1) is connected with the outlet of a discharge pump (P2) of the pretreatment unit, the outlet of the feed liquid preheater (E1) is connected to a feed tank (V4), the gas phase outlet of the upper end socket of the feed liquid preheater (E1) is connected with a condensation cooler (E2), the outlet of the condensation cooler (E2) is connected to a light oil phase tank (V3), and the non-condensing outlet of the condensation cooler (E2) is connected to a vacuum system; the feed tank (V4), the feed pump (P3) and the falling film evaporator (E3) are sequentially connected through pipelines; the heating chamber and the liquid phase outlet of the separation chamber of the falling film evaporator (E3) are connected with a residual liquid circulation tank (V6), the outlet of the residual liquid circulation tank (V6) is connected with a residual liquid circulation pump (P4), and the outlet of the residual liquid circulation pump (P4) is respectively connected to a residual liquid tank (V5) and an upper end socket circulation feed liquid inlet of the falling film evaporator (E3) through pipelines; a gas phase outlet of a separation chamber of the falling film evaporator (E3) is connected with tributyl phosphate (TBP) and a feed inlet of a vacuum rectifying tower (T1) of the kerosene separation unit; a sampling port (A3) is arranged at the outlet of the residual liquid circulating pump (P4);
After the pretreated organic waste liquid enters a feed liquid preheater (E1) for preheating, the radiolytic light product, at least the preset content of dissolved water and dissolved acid are removed, the pretreated organic waste liquid enters a heating chamber of a falling film evaporator (E3) for circular evaporation, the radionuclide and the radiolytic heavy product are left in a liquid phase, and the purified organic steam is discharged from a gas phase outlet of a separation chamber and enters a tributyl phosphate (TBP) and kerosene separation unit.
Preferably, the falling film evaporator (E3) comprises a heating chamber and a separation chamber, wherein the materials are sent into the falling film evaporator from the upper part of the heating chamber, flow downwards in a film-forming manner along the inner wall of a heat exchange pipe in the heating chamber and are partially vaporized along a pipe side, a part of the materials which are not vaporized in the heating chamber are circularly sent into the inlet of the falling film evaporator (E3), and the rest parts are discharged as residual liquid; the vaporized material is sucked into a gas phase separation chamber of the falling film evaporator by downstream vacuum; the top of the separation chamber is provided with a filler and a liquid distributor, which are used for purifying radionuclides and radiolysis products carried by the separation chamber, and the liquid distributor is arranged above the filler.
Preferably, the tributyl phosphate (TBP) and kerosene separation unit comprises: a vacuum rectifying tower (T1), a tower kettle reboiler (E4), a tower kettle extraction pump (P5), a tributyl phosphate (TBP) fraction cooler (E6), a tributyl phosphate (TBP) receiving tank (V9), a tower top condensation cooler (E5), a gas-liquid separation tank (F1), a tower top reflux tank (V7), a tower top reflux pump (P6) and a kerosene receiving tank (V8);
The feeding port of the vacuum rectifying tower (T1) is connected with the gas phase outlet of the separation chamber of the falling film evaporator (E3) of the radiolysis product separation unit, and the gas phase outlet of the top of the vacuum rectifying tower (T1), the condensing cooler (E5) of the top of the tower, the reflux tank (V7) of the top of the tower and the reflux pump (P6) of the top of the tower are connected through pipelines in sequence; the non-condensing outlet of the tower top condensation cooler (E5) is connected with a gas-liquid separation tank (F1), and the gas phase outlet of the gas-liquid separation tank (F1) is connected with a vacuum system; the liquid phase outlet of the gas-liquid separation tank (F1) is connected with a tower top reflux tank (V7); an outlet of the tower top reflux pump (P6) is connected with a reflux port of the vacuum rectifying tower (T1) and a kerosene receiving groove (V8), and a sampling port (A1) is arranged on a connecting pipeline between the outlet of the tower top reflux pump (P6) and the kerosene receiving groove (V8); the lower outlet of the tower kettle of the vacuum rectifying tower (T1), a tower kettle reboiler (E4), a tower kettle extraction pump (P5), a tributyl phosphate (TBP) fraction cooler (E6) and a tributyl phosphate (TBP) receiving tank (V9) are sequentially connected through pipelines; the gas phase outlet of the tower kettle reboiler (E4) is connected with the tower kettle of the vacuum rectifying tower (T1); an outlet pipeline of the tower kettle extraction pump (P5) is provided with a branch and is connected with a falling film evaporator (E3) of the radiolysis product separation unit; a sampling port (A2) is arranged on a pipeline connected with a tributyl phosphate (TBP) fraction cooler (E6) and a tributyl phosphate (TBP) receiving tank (V9);
The gas phase outlet at the top of the vacuum rectifying tower (T1) is connected with a tower top condensation cooler (E5), the extracted kerosene steam flows to a tower top reflux tank (V7) automatically after being condensed and cooled, one part of the kerosene steam is returned into the tower as reflux liquid by a tower top reflux pump (P6), and the other part of the kerosene steam enters a kerosene receiving tank (V8); the extraction port of the tower kettle reboiler (E4) is connected with the extraction pump (P5) of the tower kettle, and the extracted TBP enters a TBP receiving tank (V9) after passing through a TBP fraction cooler (E6) or returns to the liquid phase feed inlet at the upper end of the falling film evaporator.
Preferably, the vacuum rectifying tower (T1) is a vacuum packed rectifying tower, and the vacuum rectifying tower (T1) includes: the rectifying and separating zone (T1-1) and the stripping and separating zone (T1-2), the stripping and separating zone (T1-2) is arranged above the rectifying and separating zone (T1-1), the tower columns of each zone are connected through a flange, each zone comprises a plurality of separation stages, the separation stages of the rectifying and separating zone (T1-1) are 3-8, and the separation stages of the stripping and separating zone (T1-2) are 1-5.
Preferably, the radioactive organic waste liquid is fed in a continuous feeding mode, the radiolytic light products are continuously extracted, and kerosene, TBP and radiolytic heavy products are continuously extracted or intermittently extracted.
Specifically, in the embodiment, the radioactive organic waste liquid is subjected to mixing, stirring and clarification pretreatment in a mixing and clarifying tank (V2) to remove insoluble water phase and suspended matters and reduce the salt content and the acidity content;
The pretreated organic waste liquid enters a feed liquid preheater (E1) for preheating, then the radiolytic light product, a small amount of dissolved water and dissolved acid are removed, the pretreated organic waste liquid enters a heating chamber of a falling film evaporator (E3) for circular evaporation, the radionuclide and the radiolytic heavy product are left in a liquid phase, and the purified organic steam is discharged from a gas phase outlet of a separation chamber and enters a vacuum rectifying tower (T1);
the gas phase outlet at the top of the vacuum rectifying tower (T1) is connected with a tower top condensation cooler (E5), the extracted kerosene steam flows to a tower top reflux tank (V7) automatically after being condensed and cooled, one part of the kerosene steam is returned into the tower as reflux liquid by a tower top reflux pump (P6), and the other part of the kerosene steam enters a kerosene receiving tank (V8);
the extraction port of the tower kettle reboiler (E4) is connected with the extraction pump (P5) of the tower kettle, and the extracted TBP enters a TBP receiving tank (V9) after passing through a TBP fraction cooler (E6) or returns to the liquid phase feed inlet at the upper end of the falling film evaporator.
The operation method of the recovery device used in the radioactive organic waste liquid recovery method in this embodiment is as follows:
and vacuumizing a feed liquid preheater (E1), a falling film evaporator (E3) and a vacuum rectifying tower (T1).
Introducing 0.12MPa saturated water vapor into a feed liquid preheater (E1); opening a mixing and clarifying tank (V2) and introducing 0.02mol/L dilute nitric acid solution to pretreat the radioactive organic waste liquid; the pretreated radioactive organic waste liquid is sent to a feed liquid preheater (E1) by a discharge pump (P2), and the temperature of a valve control on a steam supply pipeline is regulated to be within the range of 80 ℃; starting a condensation cooler (E2), condensing and cooling the removed light phase radiolysis product and water, and then entering a light oil phase tank (V3); the organic feed liquid with the light phase radiolysis product and water removed enters a feed tank (V4).
The organic waste liquid in the feed tank (V4) is sent into the falling film evaporator (E3) through the feed pump (P3) and automatically flows into the residual liquid circulation tank (V6). When the liquid level in the raffinate recycle tank (V6) reaches a high level, the feed is stopped. And starting a residual liquid circulating pump (P4) and regulating the circulating flow to a set value. And (3) introducing saturated water vapor of 0.12MPa into the falling film evaporator (E3) to start the cyclic evaporation of the organic waste liquid. At the same time, the overhead condenser (E5) is turned on. When the liquid level in the residual liquid circulating tank (V6) reaches a low liquid level, organic waste liquid is timely fed and supplemented. Along with the increase of TBP concentration in the feed liquid of the raffinate circulation tank (V6), the temperature in the falling film evaporator (E3) is gradually increased, when the temperature reaches 113-115 ℃ (the absolute pressure is 0.6 kPa), continuous feeding is started, and the steam flow is regulated to keep the liquid level in the raffinate circulation tank (V6) stable.
The vaporized organic waste liquid of the falling film evaporator (E3) enters the vacuum rectifying tower (T1), one part of the organic waste liquid is condensed in the rising process and falls into the tower kettle, and the other part of the organic waste liquid enters the tower top reflux tank (V7) after being condensed by the tower top condensation cooler (E5). The feed liquid in the tower top reflux tank (V7) is pumped into a tower kettle reboiler by adopting a tower top reflux pump (P6). When the liquid level of the tower kettle reboiler (E4) is 100-200 mm higher than that of the heating pipe, the feeding and heating of the falling film evaporator (E3) are stopped, and the residual liquid circulating pump (P4) still keeps running. And (3) introducing steam into a tower kettle reboiler (E4), and controlling the temperature to be 118 ℃ (the absolute pressure is 0.8 kPa). Kerosene and part of TBP are heated to become organic steam, the organic steam enters under a stripping separation zone (T1-2) of a vacuum rectifying tower (T1) from a gas phase outlet on a tower kettle reboiler (E4), sequentially passes through the stripping separation zone (T1-2) and the rectifying separation zone (T1-1), enters into a tube side of a tower top condensation cooler (E5), is subjected to heat exchange with shell side chilled water of the tower top condensation cooler (E5) to be condensed and cooled, condensate enters into a tower top reflux tank (V7), and drops entrained in the condensate are separated by the gas-liquid separation tank (F1), and the trapped drops are also sent into the tower top reflux tank (V7). After the liquid level of 1/2-2/3 is contained in the reflux tank (V7), opening the reflux pump (P6) at the top of the tower to make part of the liquid in the reflux tank (V2) enter the vacuum rectifying tower (T1) for reflux. And the steam flow of the tower kettle reboiler (E4) is regulated so that the liquid level in the tower top reflux tank (V7) is kept stable. After stable circulation for a period of time, sampling and detecting liquid in the liquid, and if the TBP content in condensate is more than 0.02 wt%, increasing the reflux quantity to continue the circulation; if the TBP content in the condensate is less than or equal to 0.02 wt%, the condensate in a part of the tower top reflux tank (V7) is extracted in a kerosene receiving tank (V8) according to a set proportion. Starting a tower kettle extraction pump (P5) and a TBP fraction cooler (E6), sampling and analyzing the feed liquid in a tower kettle reboiler (E4), and if the TBP content in the sample is more than or equal to 80 wt%, extracting according to a set flow, and sending the sample into a TBP receiving tank (V9) for recycling; if the TBP content in the sample is less than 80 wt%, the steam flow of the tower kettle reboiler (E4) is properly adjusted, and the mixture is further concentrated. In the driving process of the vacuum rectifying tower, if the distance between the liquid level in the tower kettle reboiler (E4) and the heating pipe is smaller than 100mm, the falling film evaporator (E3) is fed and heated, and the feed liquid is supplemented for the vacuum rectifying tower (T1). After the vacuum rectifying tower (T1) is driven stably, a feed pump (P3) is started for feeding and steam is introduced into a falling film evaporator (E3), the vacuum rectifying tower (T1) is continuously fed, and the feeding flow in the feeding process is matched with the tower top extraction amount and the tower bottom extraction amount. In the process of stable operation, a high-concentration TBP component is supplemented to the outlet of the separation chamber of the falling film evaporator (E3) from the reboiler (E4) of the tower kettle, so that the liquid level at the bottom of the heating chamber of the falling film evaporator is stable, and meanwhile, the gas phase vaporized in the heating chamber of the falling film evaporator is leached and purified in the separation chamber.
Taking the simulated feed liquid (waste liquid simulator) with the composition shown in table 1 as an example, the radioactive organic extractant waste liquid treatment process is carried out by adopting the recovery device, specifically as follows:
table 1 simulates the composition of the feed solution
The operation method is the same as the above, firstly, 0.02mol/L dilute nitric acid and the simulated feed liquid in table 1 are sent into an acid pickling desalination tank (V2) for mixing, stirring and clarifying pretreatment, then sent into a feed liquid preheater (E1) for preheating to 80 ℃, the temperature of a falling film evaporator (E3) is 114 ℃, the pressure is 600Pa absolute pressure, and the circulation flow is 3500L/h. The temperature of the tower bottom of the vacuum rectifying tower (T1) is 118 ℃, the absolute pressure of the tower top is 300Pa, the absolute pressure of the tower bottom is 800Pa, the reflux ratio of the tower top is 1.0, the theoretical plate number is 9, and the product composition of each step is shown in Table 2.
TABLE 2 production compositions of the respective parts V2, V3, V4, E3, T1 of the recovery apparatus
As can be seen from tables 1 and 2, after the radioactive waste organic phase was pretreated by the acid washing desalting tank (V2), the acidity was reduced from 0.13mol/L to 0.003mol/L, the nitrate (sodium nitrate, strontium nitrate, cesium nitrate) was reduced from 13.3mg/L to 5.4mg/L, the acidity was removed by 97%, and the salts were removed by 59%. Residual water and acid are removed by preheating through a feed liquid preheater (E1), the water content is reduced from 1.5wt.% to 0.11wt.%, the acid concentration is further reduced to 0.00001mol/L, and the acid is almost completely removed. After being treated by a falling film evaporator (E3), the sodium nitrate content in the material finally entering a rectifying tower (T1) is only 1.3mg/L, strontium nitrate is 0.07mg/L, cesium nitrate is completely removed, and the re-radiolysis product is 3.4E-7mol/L of long-chain alkyl phosphate. After passing through the pretreatment unit and the radiolytic product separation unit, the removal rates of water, nitric acid, U, sodium nitrate, strontium nitrate and cesium nitrate long-chain alkyl phosphate respectively reach 100%, 84%, 90%, 87%, 100% and 99.6% compared with the feed. As can be seen from the table, the radionuclides and the re-radiolysis products in the treated waste organic phase are mainly concentrated into the residual liquid, the volume of the generated residual liquid is 99% less than that of the original waste organic phase, and the volume reduction ratio reaches 101.7:1, the amount of waste that needs further treatment is greatly reduced. The radioactive organic waste liquid recovery method and the recovery device used by the method in the embodiment slow down the decomposition reaction of TBP with substances such as nitrate, acid and the like in the rectification process, reduce the separation temperature, realize the recovery multiplexing of tributyl phosphate (TBP) and kerosene in the radioactive organic waste liquid at the non-boiling temperature, and realize the volume reduction of the radioactive waste.
Compared with the existing process conditions, the radioactive organic waste liquid recovery method and the recovery device used by the same not only can recover the organic solvent, but also greatly reduce the final treatment amount of the radioactive organic waste liquid (the volume reduction ratio can reach 100:1), reduce the treatment difficulty and save the treatment and operation costs. According to the embodiment, the temperature of the rectification system is greatly reduced, the recovery and reuse of tributyl phosphate (TBP) and kerosene in radioactive organic waste liquid are realized at a non-boiling point temperature, the thermal decomposition reaction of tributyl phosphate (TBP) with nitric acid, nitrate and the like at a high temperature is avoided, the operation safety of the system is improved, and the energy consumption is saved. Realize the volume reduction of the radioactive organic waste liquid, the volume reduction ratio reaches 100:1, and the waste amount required to be treated subsequently is reduced.
Example 3
This example provides a method for recovering radioactive organic waste liquid using the recovery apparatus of example 2, comprising the steps of:
s301, in a mixer-settler, carrying out two-stage mixing, stirring and clarifying treatment on the radioactive organic waste liquid and 0.01mol/L dilute nitric acid in a countercurrent manner, and separating insoluble water phase, suspended matters, excessive nitrate and extraction acid in the radioactive organic waste liquid, wherein the ratio of an organic phase to an aqueous phase is 10:1.
S302, the treated radioactive organic waste liquid is sent into a vertical feed liquid preheater. In the embodiment, the operation temperature of the feed liquid preheater is 100 ℃, the operation pressure is 8kPa absolute, the radioactive organic waste liquid flows from top to bottom on the inner wall of the heating pipe, the contained radiolysis produces light products (such as nitrate, nitrite, hydroxamic acid and the like), a small amount of dissolved water and dissolved acid are vaporized in the process, and the dissolved water and the dissolved acid are discharged from the pipe orifice at the top end of the upper end enclosure of the feed liquid preheater in the reverse direction, and are cooled to 20 ℃ by the condensing cooler, and then are discharged to a vacuum system without condensing, and the condensate automatically flows into a light oil phase tank. And sending the preheated radioactive organic waste liquid to a falling film evaporator for circular evaporation. The operation temperature of the falling film evaporator is 105 ℃, the operation pressure is absolute pressure of 0.3kPa, the radioactive organic waste liquid flows from top to bottom in the heating pipe of the falling film evaporator, and kerosene and TBP are vaporized in the process. The vaporized organic steam and unvaporized liquid flow downwards, and the gas enters a separation chamber of a falling film evaporator for separation and purification of entrained nuclides and then enters a vacuum rectifying tower; the unvaporized liquid enters a residual liquid circulation tank, the unvaporized liquid is enriched with radiolytic heavy products (such as long-chain acid phosphate, acid tributyl phosphate, long-chain alkyl neutral phosphate and the like) and radionuclides (such as Se-79, sr-90, pu-239, U-235 and the like) in the radioactive organic waste liquid, one part of unvaporized liquid is pumped back to a circulating feed liquid inlet of an upper seal head of the falling film evaporator by a residual liquid circulation pump, the circulating evaporation is carried out, the minimum liquid amount required by the operation of the falling film evaporator is ensured, and the other part of unvaporized liquid is continuously or intermittently discharged as residual liquid.
S303, the operating temperature of the vacuum rectifying tower in the embodiment is 60-100 ℃, and the operating pressure is 0.15-0.4 kPa. Specifically, the operation temperature of the tower kettle is 100 ℃, the operation pressure is 0.4kPa absolute, the operation temperature of the tower top is 60 ℃, and the operation pressure is 0.15kPa absolute. Organic steam entering the vacuum rectifying tower from the feeding port of the vacuum rectifying tower is continuously condensed in the rising process, and liquid drops fall into a reboiler of the tower kettle. After being heated by the tower kettle reboiler, a part of the organic vapor is changed into organic vapor again, mass transfer is carried out with the falling liquid drops, and the organic vapor and the uncondensed organic vapor are discharged from the top of the vacuum rectifying tower. And condensing the organic steam extracted from the gas phase outlet at the top of the vacuum rectifying tower, and returning the condensate to the vacuum rectifying tower as reflux liquid for reflux circulation after condensing and cooling to 5 ℃, wherein the reflux liquid and the organic steam in the vacuum rectifying tower are subjected to mass transfer in the vacuum rectifying tower, so that the TBP content in the ascending organic steam is reduced. And after repeated circulation until the TBP content in the condensate is reduced to less than or equal to 0.02wt%, extracting part of condensate, and delivering the part of condensate to a kerosene receiving tank, wherein the part of condensate is the kerosene. The other part of the condensate continues to be recirculated. The reflux ratio (i.e., the ratio of the flow rate of condensate returned to the vacuum rectifying column (T1) to the flow rate of condensate withdrawn to the kerosene receiving tank (V8)) in this example was 0.5. Sampling liquid left in the tower kettle reboiler, and when the TBP content is more than or equal to 80wt%, extracting by a tower kettle extraction pump, wherein the part of liquid is the TBP. The extracted TBP is cooled to 40 ℃ by a TBP fraction cooler and then enters a TBP receiving tank. Meanwhile, a high-concentration TBP component is supplemented to the outlet of the separation chamber of the falling film evaporator from the reboiler of the tower kettle, so as to balance the stability of the liquid level at the bottom of the heating chamber of the falling film evaporator; and leaching and purifying the gas phase vaporized in the heating chamber of the falling film evaporator in the separation chamber.
Compared with the existing process conditions, the radioactive organic waste liquid recovery method and the recovery device used by the same not only can recover the organic solvent, but also greatly reduce the final treatment amount of the radioactive organic waste liquid (the volume reduction ratio can reach 100:1), reduce the treatment difficulty and save the treatment and operation costs. According to the embodiment, the temperature of the rectification system is greatly reduced, the recovery and reuse of tributyl phosphate (TBP) and kerosene in radioactive organic waste liquid are realized at a non-boiling point temperature, the thermal decomposition reaction of tributyl phosphate (TBP) with nitric acid, nitrate and the like at a high temperature is avoided, the operation safety of the system is improved, and the energy consumption is saved. Realize the volume reduction of the radioactive organic waste liquid, the volume reduction ratio reaches 100:1, and the waste amount required to be treated subsequently is reduced.
Example 4
This example provides a method for recovering radioactive organic waste liquid using the recovery apparatus of example 2, comprising the steps of:
s401, in a mixer-settler, carrying out two-stage mixing, stirring and clarifying treatment on the radioactive organic waste liquid and 0.015mol/L dilute nitric acid in a countercurrent manner, and separating insoluble water phase, suspended matters, excessive nitrate and extraction acid in the radioactive organic waste liquid, wherein the ratio of an organic phase to an aqueous phase is 20:1.
S402, the treated radioactive organic waste liquid is sent into a vertical feed liquid preheater. In the embodiment, the operation temperature of the feed liquid preheater is 110 ℃, the operation pressure is 6kPa absolute, the radioactive organic waste liquid flows from top to bottom on the inner wall of the heating pipe, the contained radiolysis produces light products (such as nitrate, nitrite, hydroxamic acid and the like), a small amount of dissolved water and dissolved acid are vaporized in the process, and the dissolved water and the dissolved acid are discharged from the pipe orifice at the top end of the upper end enclosure of the feed liquid preheater in the reverse direction, and are cooled to 20 ℃ by the condensing cooler, and then are discharged to a vacuum system without condensing, and the condensate automatically flows into a light oil phase tank. And sending the preheated radioactive organic waste liquid to a falling film evaporator for circular evaporation. The operation temperature of the falling film evaporator is 125 ℃, the operation pressure is 1.0kPa, the radioactive organic waste liquid flows from top to bottom in the heating pipe of the falling film evaporator, and kerosene and TBP are vaporized in the process. The vaporized organic steam and unvaporized liquid flow downwards, and the gas enters a separation chamber of a falling film evaporator for separation and purification of entrained nuclides and then enters a vacuum rectifying tower; the unvaporized liquid enters a residual liquid circulation tank, the unvaporized liquid is enriched with radiolytic heavy products (such as long-chain acid phosphate, acid tributyl phosphate, long-chain alkyl neutral phosphate and the like) and radionuclides (such as Se-79, sr-90, pu-239, U-235 and the like) in the radioactive organic waste liquid, one part of unvaporized liquid is pumped back to a circulating feed liquid inlet of an upper seal head of the falling film evaporator by a residual liquid circulation pump, the circulating evaporation is carried out, the minimum liquid amount required by the operation of the falling film evaporator is ensured, and the other part of unvaporized liquid is continuously or intermittently discharged as residual liquid.
S403, the operating temperature of the vacuum rectifying tower in the embodiment is 75-125 ℃, and the operating pressure is 0.5-1.1 kPa. Specifically, the operation temperature of the tower kettle is 125 ℃, the operation pressure is 1.1kPa absolute, the operation temperature of the tower top is 75 ℃, and the operation pressure is 0.5kPa absolute. Organic steam entering the vacuum rectifying tower from the feeding port of the vacuum rectifying tower is continuously condensed in the rising process, and liquid drops fall into a reboiler of the tower kettle. After being heated by the tower kettle reboiler, a part of the organic vapor is changed into organic vapor again, mass transfer is carried out with the falling liquid drops, and the organic vapor and the uncondensed organic vapor are discharged from the top of the vacuum rectifying tower. And condensing the organic steam extracted from the gas phase outlet at the top of the vacuum rectifying tower, and returning the condensate to the vacuum rectifying tower as reflux liquid for reflux circulation after condensing and cooling to 10 ℃, wherein the reflux liquid and the organic steam in the vacuum rectifying tower are subjected to mass transfer in the vacuum rectifying tower, so that the TBP content in the ascending organic steam is reduced. And after repeated circulation until the TBP content in the condensate is reduced to less than or equal to 0.02wt%, extracting part of condensate, and delivering the part of condensate to a kerosene receiving tank, wherein the part of condensate is the kerosene. The other part of the condensate continues to be recirculated. In this example, the reflux ratio (i.e., the ratio of the flow rate of condensate returned to the vacuum distillation column (T1) to the flow rate of condensate drawn out to the kerosene receiving tank (V8)) was 2. Sampling liquid left in the tower kettle reboiler, and when the TBP content is more than or equal to 80wt%, extracting by a tower kettle extraction pump, wherein the part of liquid is the TBP. The extracted TBP is cooled to 40 ℃ by a TBP fraction cooler and then enters a TBP receiving tank. Meanwhile, a high-concentration TBP component is supplemented to the outlet of the separation chamber of the falling film evaporator from the reboiler of the tower kettle, so as to balance the stability of the liquid level at the bottom of the heating chamber of the falling film evaporator; and leaching and purifying the gas phase vaporized in the heating chamber of the falling film evaporator in the separation chamber.
Compared with the existing process conditions, the radioactive organic waste liquid recovery method and the recovery device used by the same not only can recover the organic solvent, but also greatly reduce the final treatment amount of the radioactive organic waste liquid (the volume reduction ratio can reach 100:1), reduce the treatment difficulty and save the treatment and operation costs. According to the embodiment, the temperature of the rectification system is greatly reduced, the recovery and reuse of tributyl phosphate (TBP) and kerosene in radioactive organic waste liquid are realized at a non-boiling point temperature, the thermal decomposition reaction of tributyl phosphate (TBP) with nitric acid, nitrate and the like at a high temperature is avoided, the operation safety of the system is improved, and the energy consumption is saved. Realize the volume reduction of the radioactive organic waste liquid, the volume reduction ratio reaches 100:1, and the waste amount required to be treated subsequently is reduced.
It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (15)
1. A method for recovering radioactive organic waste liquid, the radioactive organic waste liquid comprising: tributyl phosphate, kerosene, radiolytic light products, radiolytic heavy products, radionuclides, insoluble aqueous phase, suspended matter, nitrate, nitric acid, water, suspended matter, characterized in that the recovery method comprises the following steps:
1) Firstly, the radioactive organic waste liquid is pretreated to remove insoluble water phase and suspended matters in the radioactive organic waste liquid, and excessive nitrate and nitric acid are eluted;
2) Removing the radiolytic light products, the radionuclides and the radiolytic heavy products to obtain vaporized organic steam;
3) And (3) carrying out vacuum rectification treatment on the vaporized organic steam, and separating to obtain tributyl phosphate and kerosene.
2. The method for recovering radioactive organic waste liquid according to claim 1, wherein,
the step 1) is specifically as follows: in a mixer-settler, stirring, mixing and clarifying the radioactive organic waste liquid by using a dilute nitric acid solution with a first concentration, and discharging and removing insoluble water phase and suspended matters and dissolved excessive nitrate and nitric acid carried in the radioactive organic waste liquid into the water phase waste liquid;
the step 2) is specifically as follows: the radioactive organic waste liquid after pretreatment is sent into a feed liquid preheater, the feed liquid preheater operates under the conditions of a first heating temperature and a first pressure, the radioactive organic waste liquid flows from top to bottom in the inner wall of a heating pipe of the feed liquid preheater, the radiolytic light products, the dissolved water and the dissolved acid contained in the radioactive organic waste liquid are gasified in the process, the radioactive organic waste liquid is discharged from a pipe orifice at the top end of an upper end socket of the feed liquid preheater and is discharged to a vacuum system after passing through a condensation cooler, condensate is discharged into a light oil phase tank, the preheated radioactive organic waste liquid is sent into a falling film evaporator, the falling film evaporator operates under the conditions of a second heating temperature and a second pressure, kerosene and tributyl phosphate in the radioactive organic waste liquid are gasified in the process, the gasified organic steam and unvaporized liquid flow downwards in the process, and the gas enters a separation chamber of the falling film evaporator; the liquid enters a residual liquid circulation tank, is pumped back to an upper end socket circulation feed liquid inlet of the falling film evaporator by a residual liquid circulation pump, is circularly evaporated, and radiolytic heavy products and radionuclides in radioactive organic waste liquid are left in unvaporized liquid phase and are discharged as residual liquid, and vaporized organic steam enters a vacuum rectifying tower after entrained liquid drops are separated in a separation chamber of the falling film evaporator;
The step 3) is specifically as follows: the vacuum rectifying tower operates under the third temperature and the third pressure, vaporized organic steam entering the tower from a feed inlet of the vacuum rectifying tower is continuously condensed in the ascending process, liquid drops fall into a tower kettle reboiler, after being heated by the tower kettle reboiler, part of the liquid drops are changed into organic steam again, mass transfer is carried out with the falling liquid drops, the liquid drops are discharged from the top of the vacuum rectifying tower together with the non-condensed organic steam, the organic steam extracted from a gas phase outlet of the top of the vacuum rectifying tower is condensed, after the condensed organic steam is condensed to the fourth temperature, the condensate is returned to the vacuum rectifying tower as reflux liquid for carrying out reflux circulation, the reflux liquid and the organic steam in the vacuum rectifying tower are subjected to mass transfer in the vacuum rectifying tower, so that the content of tributyl phosphate in the ascending organic steam is reduced, after the content of tributyl phosphate in the condensate is reduced to the second concentration, part of condensate is extracted, namely kerosene, the other part of condensate is continuously subjected to reflux circulation, liquid in the tower is sampled, the tributyl phosphate is extracted after the content in the reboiler reaches the third concentration, the tributyl phosphate is extracted by the tributyl phosphate cooling tower, and the tributyl phosphate is extracted by the cooling tower.
3. The method for recovering radioactive organic waste liquid according to claim 2, wherein tributyl phosphate is supplemented to the outlet of the separation chamber of the falling film evaporator from the reboiler of the tower kettle, so as to balance the stabilization of the liquid level at the bottom of the heating chamber of the falling film evaporator, and the leaching and purifying of the gas phase vaporized in the heating chamber of the falling film evaporator in the separation chamber of the falling film evaporator.
4. The method for recovering radioactive organic waste according to claim 2, wherein the first concentration in the step 1) is 0.01 to 0.02mol/L;
the first heating temperature in the step 2) is 80-110 ℃, and the first pressure is 4-8 kPa absolute pressure
The second heating temperature is 105-125 ℃, and the second pressure is 0.3-1.0 kPa absolute pressure.
5. The method of claim 2, wherein the third temperature in step 3) comprises: the third temperature of the top of the vacuum rectifying tower is 60-75 ℃, the third temperature of the bottom of the vacuum rectifying tower is 100-125 ℃, and the third pressure comprises: the third pressure at the top of the vacuum rectifying tower is 0.15-0.5kPa, and the third pressure at the bottom of the vacuum rectifying tower is 0.4-1.1kPa.
6. The method for recycling radioactive organic waste liquid according to claim 2, wherein the fourth temperature is 5-20 ℃, the second concentration is that the tributyl phosphate content in condensate is less than or equal to 0.02wt%, and the third concentration is that the tributyl phosphate content in sampling is more than or equal to 80wt%.
7. The method for recovering radioactive organic waste according to any one of claims 1 to 6, wherein the radioactive organic waste is waste tributyl phosphate-kerosene mixed organic waste produced in a nuclear fuel post-treatment plant.
8. A recycling apparatus for a method for recycling radioactive organic waste liquid according to any one of claims 1 to 7, comprising:
the pretreatment unit is used for carrying out sedimentation separation on insoluble water phase and suspended matters in the radioactive organic waste liquid, and eluting nitrate and nitric acid;
the radiolytic product separation unit is connected with the pretreatment unit and is used for removing radiolytic light products, radionuclides and radiolytic heavy products;
the tributyl phosphate and kerosene separating unit is connected with the radiolysis product separating unit and is used for carrying out vacuum rectification treatment on the organic solvent treated by the radiolysis product separating unit and separating the organic solvent into tributyl phosphate and kerosene.
9. The recycling apparatus for radioactive organic waste liquid recycling method according to claim 8, wherein the pretreatment unit comprises: a feed liquid receiving tank (V1), a feed liquid conveying pump (P1), a mixing clarifying tank (V2) and a discharging pump (P2),
The material liquid receiving tank (V1), the material liquid conveying pump (P1), the mixing clarifying tank (V2) and the discharging pump (P2) are connected in sequence through pipelines, and an outlet of the discharging pump (P2) is connected to the radiolytic product separation unit;
the radioactive organic waste liquid is subjected to mixing, stirring and clarification pretreatment in a mixing and clarifying tank (V2) to remove insoluble water phase and suspended matters and reduce the salt content and the acidity content.
10. The recovery apparatus for a radioactive organic waste liquid recovery method according to claim 9, wherein the mixer-settler (V2) is a two-stage mixer-settler in which the flow ratio of the organic phase to the dilute acid is (10 to 20): 1.
11. The recovery apparatus for use in a radioactive organic waste liquid recovery method according to claim 8, wherein the radiolytic product separation unit includes: a feed liquid preheater (E1), a feed tank (V4), a feed pump (P3), a condensation cooler (E2), a light oil phase tank (V3), a falling film evaporator (E3), a raffinate circulation tank (V6), a raffinate circulation pump (P4) and a raffinate tank (V5);
the upstream of the feed liquid preheater (E1) is connected with a pretreatment unit, the outlet of the feed liquid preheater (E1) is connected to a feed tank (V4), the gas phase outlet of the upper end socket of the feed liquid preheater (E1) is connected with a condensation cooler (E2), the outlet of the condensation cooler (E2) is connected to a light oil phase tank (V3), and the non-condensing outlet of the condensation cooler (E2) is connected to a vacuum system; the feed tank (V4), the feed pump (P3) and the falling film evaporator (E3) are sequentially connected through pipelines; the heating chamber and the liquid phase outlet of the separation chamber of the falling film evaporator (E3) are connected with a residual liquid circulation tank (V6), the outlet of the residual liquid circulation tank (V6) is connected with a residual liquid circulation pump (P4), and the outlet of the residual liquid circulation pump (P4) is respectively connected to a residual liquid tank (V5) and an upper end socket circulation feed liquid inlet of the falling film evaporator (E3) through pipelines; the gas phase outlet of the separation chamber of the falling film evaporator (E3) is connected with a tributyl phosphate and kerosene separation unit; a sampling port (A3) is arranged at the outlet of the residual liquid circulating pump (P4);
After the pretreated organic waste liquid enters a feed liquid preheater (E1) for preheating, the radiolytic light products, at least the preset content of dissolved water and dissolved acid are removed, the pretreated organic waste liquid enters a heating chamber of a falling film evaporator (E3) for circular evaporation, the radionuclides and the radiolytic heavy products are left in a liquid phase, and the purified organic steam is discharged from a gas phase outlet of a separation chamber and enters a tributyl phosphate and kerosene separation unit.
12. The recovery apparatus for radioactive organic waste liquid recovery method according to claim 11, wherein the falling film evaporator (E3) comprises a heating chamber and a separation chamber, wherein the material is fed into the falling film evaporator from the upper part of the heating chamber, flows down in a film-forming manner along the inner wall of the heat exchange tube in the heating chamber and is partially vaporized along the tube side, a part of the material which is not vaporized in the heating chamber is circulated into the inlet of the falling film evaporator (E3), and the remaining part is discharged as a residual liquid; the vaporized material is sucked into a gas phase separation chamber of the falling film evaporator by downstream vacuum; the top of the separation chamber is provided with a filler and a liquid distributor, which are used for purifying radionuclides and radiolysis products carried by the separation chamber, and the liquid distributor is arranged above the filler.
13. The recovery apparatus for the radioactive organic waste liquid recovery method according to claim 8, wherein the tributyl phosphate and kerosene separation unit includes: a vacuum rectifying tower (T1), a tower kettle reboiler (E4), a tower kettle extraction pump (P5), a tributyl phosphate fraction cooler (E6), a tributyl phosphate receiving tank (V9), a tower top condensation cooler (E5), a gas-liquid separation tank (F1), a tower top reflux tank (V7), a tower top reflux pump (P6) and a kerosene receiving tank (V8);
The feeding port of the vacuum rectifying tower (T1) is connected with the gas phase outlet of the radiolysis product separation unit, and the gas phase outlet at the top of the vacuum rectifying tower (T1), the condensing cooler (E5) at the top of the tower, the reflux tank (V7) at the top of the tower and the reflux pump (P6) at the top of the tower are connected through pipelines in sequence; the non-condensing outlet of the tower top condensation cooler (E5) is connected with a gas-liquid separation tank (F1), and the gas phase outlet of the gas-liquid separation tank (F1) is connected with a vacuum system; the liquid phase outlet of the gas-liquid separation tank (F1) is connected with a tower top reflux tank (V7); an outlet of the tower top reflux pump (P6) is connected with a reflux port of the vacuum rectifying tower (T1) and a kerosene receiving groove (V8), and a sampling port (A1) is arranged on a connecting pipeline between the outlet of the tower top reflux pump (P6) and the kerosene receiving groove (V8); the lower outlet of the tower kettle of the vacuum rectifying tower (T1), the reboiler (E4) of the tower kettle, the extraction pump (P5) of the tower kettle, the tributyl phosphate fraction cooler (E6) and the tributyl phosphate receiving tank (V9) are connected in sequence through pipelines; the gas phase outlet of the tower kettle reboiler (E4) is connected with the tower kettle of the vacuum rectifying tower (T1); an outlet pipeline of the tower kettle extraction pump (P5) is provided with a branch and is connected with the radiolysis product separation unit; a sampling port (A2) is arranged on a pipeline connected with the tributyl phosphate fraction cooler (E6) and the tributyl phosphate receiving tank (V9);
the gas phase outlet at the top of the vacuum rectifying tower (T1) is connected with a tower top condensation cooler (E5), the extracted kerosene steam flows to a tower top reflux tank (V7) automatically after being condensed and cooled, one part of the kerosene steam is returned into the tower as reflux liquid by a tower top reflux pump (P6), and the other part of the kerosene steam enters a kerosene receiving tank (V8); the extraction port of the tower kettle reboiler (E4) is connected with the extraction pump (P5) of the tower kettle, and the extracted TBP enters a TBP receiving tank (V9) after passing through a TBP fraction cooler (E6) or returns to the liquid phase feed inlet at the upper end of the falling film evaporator.
14. The recovery apparatus for a radioactive organic waste liquid recovery method according to claim 13, wherein the vacuum rectification column (T1) is a vacuum packed rectification column, and the vacuum rectification column (T1) includes: the rectifying separation zone (T1-1) and the stripping separation zone (T1-2), the stripping separation zone (T1-2) is arranged above the rectifying separation zone (T1-1), the tower columns of each zone are connected through flanges, the separation level number of the rectifying separation zone (T1-1) is 3-8, and the separation level number of the stripping separation zone (T1-2) is 1-5.
15. The recovery apparatus for the radioactive organic waste liquid recovery method according to any one of claims 8 to 14, wherein the radioactive organic waste liquid is fed in a continuous feeding manner, the light product of radiolysis is continuously extracted, and kerosene, tributyl phosphate, the heavy product of radiolysis is continuously extracted or intermittently extracted.
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