CN113354006A - High-acidity wastewater treatment process and device for polynitrotoluene waste sulfuric acid vacuum concentration device - Google Patents
High-acidity wastewater treatment process and device for polynitrotoluene waste sulfuric acid vacuum concentration device Download PDFInfo
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- CN113354006A CN113354006A CN202110601725.6A CN202110601725A CN113354006A CN 113354006 A CN113354006 A CN 113354006A CN 202110601725 A CN202110601725 A CN 202110601725A CN 113354006 A CN113354006 A CN 113354006A
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- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 title claims abstract description 151
- 239000002699 waste material Substances 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000004065 wastewater treatment Methods 0.000 title claims abstract description 18
- 239000002351 wastewater Substances 0.000 claims abstract description 99
- 238000001704 evaporation Methods 0.000 claims abstract description 22
- 230000008020 evaporation Effects 0.000 claims abstract description 20
- 239000007791 liquid phase Substances 0.000 claims abstract description 13
- 238000011084 recovery Methods 0.000 claims abstract description 12
- 239000000779 smoke Substances 0.000 claims abstract description 7
- 239000002253 acid Substances 0.000 claims description 42
- 239000007788 liquid Substances 0.000 claims description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 28
- 230000001105 regulatory effect Effects 0.000 claims description 22
- 238000007599 discharging Methods 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000009833 condensation Methods 0.000 claims description 11
- 230000005494 condensation Effects 0.000 claims description 11
- 230000001276 controlling effect Effects 0.000 claims description 4
- 230000008901 benefit Effects 0.000 abstract description 5
- 230000007547 defect Effects 0.000 abstract description 3
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 10
- 238000009835 boiling Methods 0.000 description 7
- 239000000498 cooling water Substances 0.000 description 7
- 239000012071 phase Substances 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000011144 upstream manufacturing Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- SPSSULHKWOKEEL-UHFFFAOYSA-N 2,4,6-trinitrotoluene Chemical compound CC1=C([N+]([O-])=O)C=C([N+]([O-])=O)C=C1[N+]([O-])=O SPSSULHKWOKEEL-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 239000000015 trinitrotoluene Substances 0.000 description 2
- DYSXLQBUUOPLBB-UHFFFAOYSA-N 2,3-dinitrotoluene Chemical compound CC1=CC=CC([N+]([O-])=O)=C1[N+]([O-])=O DYSXLQBUUOPLBB-UHFFFAOYSA-N 0.000 description 1
- ZPTVNYMJQHSSEA-UHFFFAOYSA-N 4-nitrotoluene Chemical compound CC1=CC=C([N+]([O-])=O)C=C1 ZPTVNYMJQHSSEA-UHFFFAOYSA-N 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000002894 chemical waste Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/048—Purification of waste water by evaporation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D19/00—Degasification of liquids
- B01D19/02—Foam dispersion or prevention
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1456—Removing acid components
- B01D53/1462—Removing mixtures of hydrogen sulfide and carbon dioxide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/18—Absorbing units; Liquid distributors therefor
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/043—Details
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/38—Organic compounds containing nitrogen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/03—Pressure
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/10—Energy recovery
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
Abstract
The invention discloses a high-acidity wastewater treatment process and a high-acidity wastewater treatment device for a polynitrotoluene waste sulfuric acid vacuum concentration device, wherein the treatment process specifically comprises the steps of preheating high-acidity wastewater of the polynitrotoluene waste sulfuric acid vacuum concentration device, then carrying out reduced pressure evaporation, and carrying out heat exchange on the obtained concentrated wastewater and feed wastewater to reuse the concentrated wastewater and feed wastewater in the polynitrotoluene waste sulfuric acid vacuum concentration device for recovering sulfuric acid; the vapor obtained by reduced pressure evaporation is condensed and separated into liquid phase for absorbing the smoke. The treatment process realizes component recovery and closed loop in the wastewater, fully utilizes heat exchange, reduces energy consumption, avoids the defects of biochemical treatment modes in the prior art, and integrally improves comprehensive benefits.
Description
Technical Field
The invention relates to the technical field of chemical waste acid treatment, in particular to a high-acidity wastewater treatment process and device for a polynitrotoluene waste sulfuric acid vacuum concentration device.
Background
The concentration of the sulfuric acid in the high-acidity organic wastewater generated in the polynitrotoluene waste sulfuric acid vacuum concentration device is about 1.5-2.0%, the concentration of the sulfuric acid in the high-acidity organic wastewater contains about 20mg/L of mono-and dinitrotoluene and about 200mg/L of trinitrotoluene; the traditional high-acidity organic wastewater and low-acidity organic wastewater are mixed and then enter a wastewater biochemical treatment device for treatment. The high acidity organic wastewater contains higher concentration of sulfuric acid and polynitro compound which is difficult to be biochemically degraded. In the biochemical treatment process of the acidic organic wastewater, the sulfuric acid with higher concentration consumes alkali and simultaneously generates sulfate with higher concentration. Organic wastewater containing higher concentration sulfate harms a wastewater treatment biochemical system and causes the salt content in the treated wastewater to rise.
In the prior art, the traditional high-acidity organic wastewater and low-acidity organic wastewater are mixed and then enter a wastewater biochemical treatment device for treatment. There are problems in that: (1) the high acidity organic wastewater contains higher concentration sulfuric acid, and the higher concentration sulfuric acid consumes alkali and simultaneously generates high concentration sulfate. Organic wastewater containing higher-concentration sulfate harms a wastewater treatment biochemical system and causes the salt content in the treated wastewater to be increased; (2) the polynitro compound difficult to be biochemically degraded increases the difficulty of the biochemical treatment of the wastewater; (3) the energy of the polynitrotoluene waste sulfuric acid vacuum concentration device is unbalanced in the operation process, a certain amount of low-quality steam (the pressure is 0.1MPa-0.2MPa) can not be recycled, and the environmental heat pollution is caused.
In fact, the sulfuric acid in the high acidity organic wastewater can be recycled, and in addition, a large amount of recoverable polynitrotoluene is contained in the wastewater, so that in order to reduce the treatment burden of a wastewater biochemical treatment device and improve the comprehensive benefit, a new high acidity wastewater treatment process needs to be provided.
Disclosure of Invention
The first purpose of the invention is to provide a high acidity wastewater treatment process of a polynitrotoluene waste sulfuric acid vacuum concentration device, and the second purpose of the invention is to provide a device of the treatment process; the above object is to solve at least one of the above problems in the prior art.
In view of the above, the technical scheme of the invention is as follows:
a high-acidity wastewater treatment process for a polynitrotoluene waste sulfuric acid vacuum concentration device comprises the following steps: preheating high-acidity wastewater produced by the polynitrotoluene waste sulfuric acid vacuum concentration device, then evaporating under reduced pressure, and reusing the concentrated wastewater and feed wastewater after heat exchange for recovering sulfuric acid in the polynitrotoluene waste sulfuric acid vacuum concentration device; the vapor obtained by reduced pressure evaporation is condensed and separated into liquid phase for absorbing the smoke.
According to an embodiment of the invention, the reduced pressure evaporation conditions are: 30-38 kPa.
According to an embodiment of the present invention, the sulfuric acid concentration in the polynitrotoluene wastewater is less than 4 wt%.
According to an embodiment of the invention, the concentration of sulphuric acid in the concentrated wastewater is less than 10 wt%.
A high acidity wastewater treatment device of a polynitrotoluene waste sulfuric acid vacuum concentration device is characterized by comprising a heat recoverer, an evaporator and a condenser; wherein: one side of the heat recoverer is communicated with a waste water feeding pipe, and the other side of the heat recoverer is communicated with the lower part of the evaporator through the hot waste water feeding pipe; the evaporator is provided with a steam feeding pipe, a steam return pipe and a hot acid discharging pipe communicated with the heat recoverer; the waste water and the concentrated waste water exchange heat in the heat recovery device through a waste water feeding pipe and a hot acid discharging pipe respectively, and then leave the heat recovery device through the hot waste water feeding pipe and the acid discharging pipe respectively;
one side of the condenser is provided with a steam pipe communicated with the upper part of the evaporator, and the other side is provided with a condensation discharging pipe.
According to the embodiment of the invention, the waste water feeding pipe is provided with a waste water regulating valve, the steam feeding pipe is provided with a steam regulating valve, the feeding evaporator is provided with a liquid level meter, and the liquid level meter is respectively interlocked with the waste water regulating valve and the steam regulating valve and used for controlling the waste water feeding amount and the heating steam amount.
According to the embodiment of the invention, the device also comprises an acid storage tank and a condensed water storage tank; the acid discharge pipe is communicated with the lower part of the heat recoverer, and the other end of the acid discharge pipe enters below the liquid level of the acid storage tank; the condensation discharging pipe is communicated with the lower part of the condenser, and the other end of the condensation discharging pipe enters the position below the liquid level of the condensation water storage tank.
According to an embodiment of the invention, the hot waste water feed pipe communicates with the bottom of the evaporator.
According to an embodiment of the invention, a demister is provided at the connection of the steam pipe and the evaporator.
According to the embodiment of the invention, a baffle plate which vertically cuts the liquid level is arranged in the evaporator.
Compared with the prior art, the invention has the following effects:
1. the high-acidity wastewater treatment process provided by the invention can be used for obtaining concentrated sulfuric acid waste liquid with higher concentration, simultaneously reserving a polynitrotoluene component in a solute, and recycling sulfuric acid by using the polynitrotoluene waste sulfuric acid vacuum concentration device; the condensate phase containing part of low-boiling-point components can enter the smoke absorption device again for comprehensive utilization without direct treatment, thereby realizing the closed-loop recovery of the main components of the waste liquid and effectively avoiding the defects of the existing biochemical treatment technology.
2. In the invention, the heat recoverer is adopted to generate heat exchange, so that the heat is recycled, the energy consumption is reduced, and the evaporation efficiency is improved; in addition, the process requirements can be met without demanding the material of the equipment, the feasibility of the device is enhanced, the cost is effectively reduced, and the comprehensive benefits are improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic view of the whole of a high-acidity wastewater treatment apparatus according to the present invention.
FIG. 2 is a schematic view of the evaporator according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantageous effects of the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and the detailed description. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The invention provides a high-acidity wastewater treatment process of a polynitrotoluene waste sulfuric acid vacuum concentration device, wherein high-acidity wastewater produced by the polynitrotoluene waste sulfuric acid vacuum concentration device is preheated and then is subjected to reduced pressure evaporation, and the concentrated wastewater and feed wastewater are subjected to heat exchange and then are reused in the polynitrotoluene waste sulfuric acid vacuum concentration device for recovering sulfuric acid; the vapor obtained by reduced pressure evaporation is condensed and separated into liquid phase for absorbing the smoke.
Preferably, the reduced pressure evaporation conditions are: 30-38kPa, 75 ℃; the sulfuric acid concentration in the polynitrotoluene wastewater is lower than 4 wt%, and the sulfuric acid concentration in the concentrated wastewater is lower than 10 wt%. The above conditions are selected because the boiling point of the sulfuric acid solution at a low pressure of 30kPa is not more than 75 ℃ for the sulfuric acid waste water of less than 4 wt%; the boiling point of the sulfuric acid solution is not more than 80 ℃ under the condition of 38kPa low pressure, and the polynitrotoluene is not easy to volatilize along with water vapor under the condition of 75-80 ℃ in a dilute acid water solution; when the concentration of the sulfuric acid wastewater is below 10 wt%, and the temperature is 80 ℃ or below, 904L of stainless steel material has good corrosion resistance.
Furthermore, the content of sulfuric acid in the gas phase above the boiling surface of the sulfuric acid solution having a concentration of 70 wt% or less is 0 in terms of the characteristics of the aqueous sulfuric acid solution, and therefore, the problem of vaporization of sulfuric acid is not caused even when the concentration is less than 10 wt%.
Referring to fig. 1, the present invention provides an apparatus for high acidity wastewater treatment of a polynitrotoluene waste sulfuric acid vacuum concentration device, comprising:
1. a heat recoverer; 2. an evaporator; 3. a condenser; 4. a vacuum pump; 5. an acid storage tank; 6. an acid delivery pump; 7. a condensed water storage tank; 8. a condensate water delivery pump; 9. a wastewater feeding pipe; 10. a hot wastewater feed pipe; 11. a hot acid discharge pipe; 12. an acid discharge pipe; 13. an acid delivery pipe; 14. a vapor tube; 15. condensing a discharge pipe; 16. a noncondensable gas outlet pipe; 17. a non-condensable gas conveying pipe; 18. a condensed water conveying pipe; 19. a steam feed pipe; 20. a steam flow meter; 21. a steam regulating valve; 22. a wastewater flowmeter; 23. a waste water regulating valve; 24. a cooling water feed pipe; 25. a cooling water discharge pipe; 26. a steam return pipe; 201. a liquid level meter. And other associated connecting lines, valves.
Wherein: the waste water feeding pipe 9 is communicated with the left side of the heat recoverer 1, and the waste water feeding pipe 9 is sequentially provided with a waste water flowmeter 22 and a waste water regulating valve 23 along the direction of the heat recoverer 1; the lower part of the heat recoverer 1 is sequentially provided with an acid discharge pipe 12 and an acid storage tank 5, and the acid storage tank 5 is communicated with an acid delivery pipe 13 and an acid delivery pump 6.
The right side of the heat recoverer 1 is communicated with the lower end of the evaporator 2 through a hot waste water feeding pipe 10; the left side of the evaporator 2 is communicated with a steam feeding pipe 19, and a steam regulating valve 21 is arranged on the steam feeding pipe 19; a steam return pipe 26 is arranged at the lower left side of the evaporator 2, and a steam flow meter 20 is arranged on the steam return pipe 26; a liquid level meter 201 is arranged on the evaporator 2; the right lower side of the evaporator 2 is provided with a hot acid discharging pipe 11 and is communicated with the upper part of the heat recoverer 1.
The waste water regulating valve 23 and the steam regulating valve 21 are interlocked with the liquid level meter 201 respectively, and are used for controlling the waste water regulating valve 23 and the steam regulating valve 21 respectively by mastering the dynamic value of the liquid level meter 201 so as to respectively realize the control of waste water feeding flow and steam flow to ensure the stability of evaporation in the evaporator 2. Specifically, the liquid level meter 201, the steam flow meter 20, the steam regulating valve 21, the waste water flow meter 22, and the waste water regulating valve 23 jointly form an evaporation liquid level control system of the evaporator 2, the material liquid level in the evaporator 2 is automatically controlled to be a normal value, and the liquid level control system can adopt a common DCS control.
The upper part of the evaporator 2 is communicated with the condenser 3 through a steam pipe 14; a cooling water feeding pipe 24 is arranged on the left side of the condenser 3, a cooling water discharging pipe 25 is arranged on the right side of the condenser, and a condensation discharging pipe 15 is arranged on the lower side of the condenser; the condensed water storage tank 7 is communicated with the condensed water discharge pipe 15, and the condensed water storage tank 7 is communicated with the condensed water delivery pump 8 and delivers condensed water by the condensed water delivery pipe; a gas outlet pipe 16 is also arranged on the condensation discharging pipe 15; the gas outlet pipe 16 delivers the non-condensable gas via the vacuum pump 4 via a gas delivery pipe 17.
In this embodiment, the heat recovery device 1 is similar to a common heat exchanger structure, such as a tubular heat exchanger, and generates heat exchange through contact between a tube side and a shell side, and the low-temperature high-acidity organic wastewater and the hot acid coming out from the evaporator 2 reversely flow in the tube side and the shell side to generate heat exchange, thereby realizing heat recovery.
In this embodiment, the acid discharge pipe 12 is inserted below the liquid level of the acid storing bath 5 to maintain the degree of vacuum of the evaporator 2; a condensed water discharging pipe 15 is inserted below the liquid level of the condensed water storage tank 7 to maintain the vacuum degree of the evaporator 2; the vacuum pump 4 is connected with a condensed water discharge pipe 15 through a gas outlet pipe 16, and separates out non-condensable gas, so that the evaporator 2 keeps vacuum degree.
In this embodiment, in order to improve the reliability and the working efficiency of the evaporator 2, a special structure is designed, as shown in fig. 2, wherein: 201 is a liquid level meter, 202 is a demister, 203 is a heating pipe, 204 is a baffle, 205 is a liquid phase feeding pipe, 206 is a shell, 207 is a liquid phase discharge port, and 208 is a gas phase discharge port. Wherein: the liquid phase feed pipe 205, the liquid phase discharge port 207 and the gas phase discharge port 208 are respectively communicated with the shell 206, and the shell 206 bears the internal and external pressure difference; the heating pipe 203 provides steam to provide heat for the evaporator 2; the demister 202 eliminates acid mist entrained in the gasified steam; the baffle 204 assists in controlling the liquid level, and improves the accuracy of the liquid level; the liquid phase feed pipe 205 enters the shell 206 from the bottom of the evaporator 2 to reduce entrainment; the liquid phase discharge port 207 is used for discharging concentrated dilute acid. Preferably, the heating tube 203 is a conventional heating coil, such as a serpentine, providing a large heat exchange area; the demister 202 comprises a mesh structure and is arranged at the lower end of the liquid phase discharge port 207; the baffle 204 is vertically arranged at the bottom of the evaporator 2 upwards, and cuts the liquid level to prevent the liquid level from generating severe fluctuation due to boiling.
Based on the device, the high-acidity wastewater treatment device of the polynitrotoluene waste sulfuric acid vacuum concentration device has the working process as follows:
1) high-acidity organic wastewater (about 20 ℃ and the mass concentration of less than 4%) generated by an upstream polynitrotoluene waste sulfuric acid vacuum concentration device enters a wastewater feeding pipe 9, the flow is respectively regulated and measured through a wastewater regulating valve 23 and a wastewater flow meter 22, a liquid level meter 201 displays the liquid level of an evaporator 2, and when the liquid level is higher than a set value, the liquid level meter is automatically closed, and wastewater feeding is stopped;
2) the high-acidity organic wastewater with flow to be treated exchanges heat through a heat recoverer 1;
3) the high-acidity organic wastewater after heat exchange enters the evaporator 2 from the bottom through the hot wastewater feeding pipe 10;
4) heating steam enters the steam feeding pipe 19, and enters the evaporator 2 for heating and evaporation after the flow is respectively controlled and metered by the steam regulating valve 21 and the steam flow meter 21; the condensed water generated after the heat of the steam is released is discharged through a condensed water outlet pipe 26, the liquid level meter 201 displays the liquid level in the evaporator 2, and when the liquid level is lower than a set value, the heating steam regulating valve 21 is automatically closed to stop heating the steam; the vacuum pump 4 is controlled to maintain the pressure inside the casing 201 of the evaporator 2 at 30-38 kPa.
5) Hot sulfuric acid obtained by concentration of the evaporator 2 enters the heat recovery device 1 through the hot acid discharge pipe 11 to exchange heat with feed wastewater and then is cooled, and the cooled concentrated dilute acid enters the acid storage tank 5 through the acid discharge pipe 12 and is conveyed to the upstream polynitrotoluene waste sulfuric acid vacuum concentration device through the acid conveying pump 6 and the acid conveying pipe 13 to further recover sulfuric acid.
6) Meanwhile, steam generated by heating and evaporating the high-acidity organic wastewater enters the condenser 3 through the steam pipe 14 for condensation; cooling water enters the condenser 3 from the cooling water feeding pipe 24 for heat exchange and then flows out from the cooling water discharging pipe 25; the condensed central condensed water of the condenser 3 enters a condensed water storage tank 7 from a condensed water discharge pipe 15 and enters an absorption device for comprehensive utilization through a condensed water delivery pump 8 and a condensed water delivery pipe 18;
7) the non-condensable gas is conveyed to the smoke absorbing device through a gas outlet pipe 16, a vacuum pump 4 and a gas conveying pipe 17.
The basic principle of the invention is as follows:
the concentration of high-acidity organic wastewater generated in upstream production is generally below 4 wt%, the boiling point of the sulfuric acid wastewater solution is close to 100 ℃ under normal pressure, but the boiling point is about 75-80 ℃ under the pressure condition of 30-38kPa, and trinitrotoluene is not easy to volatilize along with water vapor in the dilute acid aqueous solution under the condition; further, the content of sulfuric acid in the gas phase on the boiling surface of the sulfuric acid solution at a low concentration is 0, depending on the characteristics of the aqueous sulfuric acid solution. Therefore, by designing the waste sulfuric acid concentration and recovery process, the low-boiling-point volatile components are removed under the low-pressure condition, the concentrated sulfuric acid waste liquid with higher concentration is obtained, meanwhile, the polynitrotoluene component in the solute is also reserved, and the polynitrotoluene waste sulfuric acid can enter the polynitrotoluene waste sulfuric acid vacuum concentration device again to recover sulfuric acid. In addition, the sulfuric acid waste liquid after evaporation concentration and the sulfuric acid waste water stock solution are subjected to heat exchange, so that heat is recycled, energy consumption is reduced, and heat exchange efficiency is improved; in addition, the low-boiling-point components are condensed after low-pressure evaporation, and then the condensed liquid phase and the gas phase are separated, and the condensed liquid phase containing part of the low-boiling-point components can enter the smoke absorption device again for comprehensive utilization without direct treatment; in conclusion, the concentration and recovery process of the polynitrotoluene waste sulfuric acid provided by the invention recovers the main components of the wastewater and realizes closed-loop treatment, thereby promoting recycling economy, effectively reducing the burden of biochemical treatment of the wastewater in the prior art and integrally improving comprehensive benefits.
According to common knowledge, 904L stainless steel is adopted for sulfuric acid with the concentration of below 10 wt%, the temperature of 80 ℃ and below, the corrosion resistance is good, and the treatment process temperature is below 80 ℃, so that the process requirement can be met without demanding the material of equipment, the feasibility of the device is enhanced, and the cost is effectively reduced.
Example 1
A feed of 4 wt.% sulfuric acid wastewater at about 20 ℃ from an upstream generation is passed through a heat recovery unit 1 (heat exchange area about 10 m)2) Enters the evaporator 2 from the bottom after being heated to about 33 ℃; starting a vacuum pump 4 to maintain the pressure in the evaporator 2 at 35kPa and the heating steam with the pressure of 0.1MPa-0.2MPa to enter the evaporator 2 after steam adjustment (the area of a heating pipe is about 40 m)2) Carrying out low-pressure evaporation; the evaporation temperature is 80 ℃ under the condition of ensuring that the liquid level meter 201 is normal, and the feeding flow rate of the sulfuric acid wastewater is set to be 1500 kg/h. Under the working condition, the device normally operates, the discharge temperature in the acid discharge pipe 12 is 50 ℃, the detected sulfuric acid concentration in the acid storage tank 5 is 10 wt%, the detected polynitrotoluene content is 1.1g/L, and the detected sulfuric acid concentration in the condensed water storage tank 7 is 0.
Example 2
Under the condition of the same heat exchange area in example 1, the concentration of the fed sulfuric acid wastewater is 2 wt%, the low-pressure evaporation pressure is 30kPa, the feeding flow is set to 1200kg/h, and the evaporation temperature is 75 ℃ under the condition of ensuring that the liquid level meter 201 is normal. Under the working condition, the device runs normally, the discharge temperature in the acid discharge pipe 12 is 44 ℃, the detected sulfuric acid concentration in the acid storage tank 5 is 7.9 wt%, the detected polynitrotoluene content is 0.88g/L, and the detected sulfuric acid concentration in the condensed water storage tank 7 is 0.
The above embodiments illustrate that the device and the process provided by the invention can realize concentration of sulfuric acid wastewater and normal operation of the device, achieve the purposes of increasing sulfuric acid concentration and zero loss, provide support for recycling main components of sulfuric acid wastewater, and effectively avoid the defects of the existing biochemical treatment technology.
The invention is not limited solely to that described in the specification and embodiments, and additional advantages and modifications will readily occur to those skilled in the art, so that the invention is not limited to the specific details, representative apparatus, and illustrative examples shown and described herein, without departing from the spirit and scope of the general concept as defined by the appended claims and their equivalents.
Claims (10)
1. A high acidity wastewater treatment process of a polynitrotoluene waste sulfuric acid vacuum concentration device is characterized in that high acidity wastewater produced by the polynitrotoluene waste sulfuric acid vacuum concentration device is preheated and then is subjected to reduced pressure evaporation, and the concentrated wastewater and feed wastewater are subjected to heat exchange and then are reused in the polynitrotoluene waste sulfuric acid vacuum concentration device for recovering sulfuric acid; the vapor obtained by reduced pressure evaporation is condensed and separated into liquid phase for absorbing the smoke.
2. The process of claim 1, wherein the reduced pressure evaporation conditions are 30-38 kPa.
3. The process of claim 1, wherein the sulfuric acid concentration in the polynitrotoluene wastewater is less than 4 wt.%.
4. The process of claim 1, wherein the concentrated wastewater has a sulfuric acid concentration of less than 10 wt%.
5. A high-acidity wastewater treatment device of a polynitrotoluene waste sulfuric acid vacuum concentration device is characterized by comprising a heat recoverer (1), an evaporator (2) and a condenser (3); wherein:
one side of the heat recoverer (1) is communicated with a waste water feeding pipe (9), and the other side of the heat recoverer is communicated with the lower part of the evaporator (2) through a hot waste water feeding pipe (10); the evaporator (2) is provided with a steam feeding pipe (19) and a steam return pipe (26), and is also provided with a hot acid discharging pipe (11) communicated with the heat recoverer (1); the waste water and the concentrated waste water exchange heat in the heat recovery device (1) through a waste water feeding pipe (9) and a hot acid discharging pipe (11) respectively, and then leave the heat recovery device (1) through a hot waste water feeding pipe (10) and an acid discharging pipe (12) respectively;
one side of the condenser (3) is provided with a steam pipe (14) communicated with the upper part of the evaporator (2), and the other side is provided with a condensation discharge pipe (15).
6. The treatment plant according to claim 5, characterized in that the waste water feed pipe (9) is provided with a waste water regulating valve (23), the steam feed pipe (19) is provided with a steam regulating valve (21), the evaporator (2) is fed with a liquid level meter (201), and the liquid level meter (201) is interlocked with the waste water regulating valve (23) and the steam regulating valve (21) respectively, for controlling the waste water feed amount and the heating steam amount.
7. The processing apparatus according to claim 5, further comprising an acid storage tank (5) and a condensed water storage tank (7); the acid discharge pipe (12) is communicated with the lower part of the heat recoverer (1), and the other end of the acid discharge pipe enters the position below the liquid level of the acid storage tank (5); the condensation discharging pipe (15) is communicated with the lower part of the condenser (3), and the other end of the condensation discharging pipe enters the position below the liquid level of the condensation water storage tank (7).
8. A treatment plant according to claim 5, characterized in that said hot waste water feed pipe (10) communicates with the bottom of said evaporator (2).
9. The treatment device according to claim 5, characterized in that a demister (202) is provided at the connection of the vapor pipe (14) and the evaporator (2).
10. Treatment device according to claim 5, characterized in that a baffle (204) is provided in the evaporator (2) that cuts the liquid level vertically.
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