CN102649545B - Nitric acid pre-concentration method for waste acid concentration technology in production of dinitrotoluene - Google Patents
Nitric acid pre-concentration method for waste acid concentration technology in production of dinitrotoluene Download PDFInfo
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- CN102649545B CN102649545B CN201110330160.9A CN201110330160A CN102649545B CN 102649545 B CN102649545 B CN 102649545B CN 201110330160 A CN201110330160 A CN 201110330160A CN 102649545 B CN102649545 B CN 102649545B
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- 238000000034 method Methods 0.000 title claims abstract description 59
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 title claims abstract description 55
- 229910017604 nitric acid Inorganic materials 0.000 title claims abstract description 55
- 239000002253 acid Substances 0.000 title claims abstract description 32
- DYSXLQBUUOPLBB-UHFFFAOYSA-N 2,3-dinitrotoluene Chemical compound CC1=CC=CC([N+]([O-])=O)=C1[N+]([O-])=O DYSXLQBUUOPLBB-UHFFFAOYSA-N 0.000 title claims abstract description 28
- 238000004094 preconcentration Methods 0.000 title claims abstract description 19
- 239000002699 waste material Substances 0.000 title claims abstract description 10
- 238000004519 manufacturing process Methods 0.000 title abstract description 11
- 238000005516 engineering process Methods 0.000 title abstract description 4
- 238000009833 condensation Methods 0.000 claims abstract description 32
- 230000005494 condensation Effects 0.000 claims abstract description 32
- 239000007788 liquid Substances 0.000 claims abstract description 18
- 239000002351 wastewater Substances 0.000 claims abstract description 14
- 238000005406 washing Methods 0.000 claims abstract description 10
- 238000010992 reflux Methods 0.000 claims abstract description 7
- 230000008016 vaporization Effects 0.000 claims abstract description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 40
- 238000006396 nitration reaction Methods 0.000 abstract 2
- 238000003912 environmental pollution Methods 0.000 abstract 1
- 238000009834 vaporization Methods 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 13
- 239000012071 phase Substances 0.000 description 7
- 238000012856 packing Methods 0.000 description 5
- 239000002994 raw material Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 239000007792 gaseous phase Substances 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- OMBRFUXPXNIUCZ-UHFFFAOYSA-N dioxidonitrogen(1+) Chemical compound O=[N+]=O OMBRFUXPXNIUCZ-UHFFFAOYSA-N 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
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Abstract
The invention discloses a nitric acid pre-concentration method for waste acid concentration technology in production of dinitrotoluene, which comprises the steps of: leading waste acid coming from the washing process and/ or acid steam coming from the waste acid steam stripping process in a nitration system to enter a rectifying tower for vacuum rectification, then using a reboiler for vaporization, and obtaining products after concentration; sending the products obtained after concentration back into the nitration system; controlling the tower top temperature of the rectifying tower to be within the range of 73-78 DEG C and the tower bottom temperature of the rectifying tower to be within the range of 95-103 DEG C; leading gas phase arranged on the top of the rectifying tower to enter a first-stage condenser for condensation, sending first-stage condensate back into the top of the rectifying tower, and taking the first-stage condensate as reflux liquid, wherein the reflux ratio is 0.18-0.2; taking the rest stage condensate as waste water to be discharged; leading the tail gas of the first-stage condenser to enter a second-stage condenser for condensation, and sending all second-stage condensate back into the rectifying tower; and controlling the second-stage condensate to enter the rectifying tower at a rectifying section with the temperature of 80-82 DEG C. According to the nitric acid pre-concentration method, the content of nitric acid in the waste water can be reduced to less than 1%, so that the cost is greatly reduced, and the environmental pollution is reduced.
Description
Technical field
The present invention relates to the production method of dinitrotoluene (DNT), be specifically related to the nitric acid pre-concentration method of waste acid concentration technique in dinitrotoluene (DNT) production.
Background technology
At present, in the production method of dinitrotoluene (DNT), from the spent acid of the washing procedure of nitrification, wherein the weight content of nitric acid is 18～20%, and the weight content of sulfuric acid is 5～8%, contains the dinitrotoluene (DNT) of solubilised state simultaneously, oxynitride etc., enter rectifying tower and carry out rectifying.In rectifying tower, under vacuum condition, operate, the sulfuric acid containing in spent acid, as extraction agent, changes the azeotropic point of nitric acid, the dinitrotoluene (DNT) of nitric acid, sulfuric acid and solubilised state after the reboiler outlet at the bottom of rectifying tower is concentrated, then by being pumped back to nitrification.
Rectifying tower top gaseous phase chief component is water, a small amount of nitric acid, dinitrotoluene (DNT), nitrogen peroxide and nitrogen protoxide etc.In first-stage condenser, by the water condensation in top gaseous phase, this phlegma is finally arranged processing outward as nitric acid preconcentration technique waste water, the nitric acid in the further condensation gas phase of secondary condenser, and this phlegma returns rectifying tower as the phegma of tower top.The gas phase of secondary condenser enters vacuum pump, finally enters tail gas absorption technology unit.
There is a defect in above-mentioned method: the nitric acid content in the phlegma of first-stage condenser, at 1.5～3wt%, fails to reach wastewater discharge standard, therefore increased the expense of wastewater treatment.In addition, because raw material nitric acid runs off and is greater than design load in waste water, this has also caused the increase of product cost.Actual nitric acid content in B-grade condensation liquid is at 7～12wt% simultaneously, and far above Design Theory value 3%, this doubt is present in nitric acid pre-concentration method all the time all the time.
Summary of the invention
The nitric acid content that technical problem to be solved by this invention has been to overcome in the phlegma that the existing dinitrotoluene (DNT) waste acid concentration technique in producing can cause first-stage condenser is high, thereby increased the expense of wastewater treatment and the defect of production cost, the nitric acid pre-concentration method of waste acid concentration technique in a kind of dinitrotoluene (DNT) production is provided.The method can make the content of nitric acid in waste water reach wastewater discharge standard, has significantly reduced the production cost of dinitrotoluene (DNT).
The nitric acid pre-concentration method that the invention provides waste acid concentration technique in a kind of dinitrotoluene (DNT) production, it comprises the steps:
Make to enter and in rectifying tower, under the vacuum tightness of 60～64kPa, carry out rectification under vacuum from the spent acid of washing procedure of nitrification and/or the sour vapour of spent acid stripping process, reboiler at the bottom of the being arranged at described rectifying tower concentrated after product of vaporizing to obtain, sends back to nitrification by described concentrated after product; The tower top temperature of described rectifying tower is 73～78 ℃, and column bottom temperature is 95～103 ℃;
Wherein, the gas phase that is arranged in the tower top of described rectifying tower enters first-stage condenser and carries out condensation, obtains one-level phlegma, described one-level phlegma is sent back to the tower top of described rectifying tower, and as the first phegma of described rectifying tower, reflux ratio is 0.18～0.2; Remaining one-level phlegma carries out outer row's processing as the waste water of nitric acid preconcentration technique; Remaining one-level phlegma and the first phegma sum are described one-level phlegma;
The tail gas of described first-stage condenser enters secondary condenser again, carry out condensation and obtain B-grade condensation liquid, all send described B-grade condensation liquid back to described rectifying tower as the second phegma, described B-grade condensation liquid locates to enter rectifying tower 80～82 ℃ of the rectifying section of described rectifying tower.
Wherein, described rectifying tower is preferably packing tower.The theoretical plate number of described packing tower is preferably 8～12, is more preferably 10.
Wherein, the conventional content that in the spent acid of the described washing procedure from nitrification, the content of nitric acid and sulfuric acid is this area, nitric acid content is generally 18～20wt%, and sulfuric acid content is generally 5～8wt%.
Wherein, the conventional content that in the sour vapour of described spent acid stripping process, the content of nitric acid and sulfuric acid is this area, nitric acid content is generally 10～12wt%, and sulfuric acid content is generally 0.2～0.5wt%.
Wherein, in described concentrated after product, nitric acid content general control is at 45～50wt%, and sulfuric acid content general control is at 5～10wt%.
Wherein, the condensation in described first-stage condenser can adopt the routine operation condition of this area to carry out, and preferably at 72～74 ℃, carries out.
Wherein, the condensation in described secondary condenser can adopt the routine operation condition of this area to carry out, and preferably at 58～62 ℃, carries out.
Meeting on the basis of this area general knowledge, above-mentioned each optimum condition can arbitrary combination, obtains the preferred embodiments of the invention.
Reagent, raw material and the equipment that the present invention uses is commercially available obtaining all.
Positive progressive effect of the present invention is:
1, adopt nitric acid pre-concentration method of the present invention can make nitric acid content in the final waste water emitting from nitric acid preconcentration technique be down to below 1% from original 2% left and right, reduced the loss to the pollution of environment and nitric acid, for the production equipment of producing 190000 tons of dinitrotoluene (DNT) per year, 550 tons, annual recyclable nitric acid.
2, from energy point of view analysis, because nitric acid content in rectifying column top return liquid is much smaller than original design, so quantity of reflux reduces greatly, the energy of reboiler will reduce to some extent, heat and the cold of nitric acid preconcentration technique are all reduced to some extent, meet the requirement of energy-saving and emission-reduction.
Accompanying drawing explanation
Fig. 1 is the schema of the inventive method.
Fig. 2 is the schema of existing nitric acid concentration method.
Embodiment
With embodiment, further illustrate the present invention below, but the present invention is not limited, the raw material in embodiment is conventional commercially available prod.
Referring to Fig. 1, the sour vapour of the spent acid of the washing procedure from nitrification and/or spent acid stripping process is entered to rectifying tower 1 and carry out rectifying, the reboiler at the bottom of rectifying tower exports the product after obtain concentrated, then sends back to nitrification;
The gas phase of rectifying tower 1 tower top enters first-stage condenser 2, then one-level phlegma is sent back to the tower top of rectifying tower 1, and as the first phegma of rectifying tower 1, remaining phlegma is arranged processing outward as nitric acid preconcentration technique waste water;
The tail gas of first-stage condenser 2 enters secondary condenser 3 again, then using B-grade condensation liquid as the second phegma, all sends rectifying tower 1 back to, and this B-grade condensation liquid locates to enter rectifying tower 1 80～82 ℃ of the rectifying section of rectifying tower 1.
Embodiment 1
Adopt the flow process of Fig. 1.
Rectifying tower adopts packing tower, and theoretical plate number is 10.
From the spent acid of the washing procedure of nitrification, flow is 4100 kgs/hour, and wherein the content of nitric acid is 20wt%, and the content of sulfuric acid is 8wt%.From the sour vapour of spent acid stripping process, flow is 7020 kgs/hour, and wherein nitric acid content is at 12wt%, and sulfuric acid content is at 0.2wt%.
Above-mentioned spent acid and sour vapour are sent into rectifying tower 1, under 60kPa vacuum tightness, carry out rectifying, tower top temperature is 76 ℃, 99 ℃ of column bottom temperatures, reboiler at the bottom of rectifying tower exports the product after obtain concentrated, and wherein nitric acid content is at 50wt%, and sulfuric acid content is at 10wt%, send back to nitrification, flow is 3480 kgs/hour again;
The gas phase of rectifying tower 1 tower top enters first-stage condenser 2, carries out condensation and obtain one-level phlegma at 73 ℃, then one-level phlegma is sent back to the tower top of rectifying tower 1, and as the first phegma of rectifying tower 1, reflux ratio is 0.19; Remaining one-level phlegma is arranged to processing outward as nitric acid preconcentration technique waste water, and flow is 7530 kgs/hour, and wherein, the content of nitric acid is 1wt%;
The tail gas of this first-stage condenser 2 enters secondary condenser 3 again, at 60 ℃, carry out condensation and obtain B-grade condensation liquid, then all send B-grade condensation liquid back to rectifying tower 1 as the second phegma, this B-grade condensation liquid locates to enter rectifying tower 1 81 ℃ of the rectifying section of rectifying tower 1.
Adopt the flow process of Fig. 1.
Rectifying tower adopts packing tower, and theoretical plate number is 10.
From the spent acid of the washing procedure of nitrification, flow is 4100 kgs/hour, and wherein the weight content of nitric acid is 18wt%, and the weight content of sulfuric acid is 5wt%.From the sour vapour of spent acid stripping process, flow is 7020 kgs/hour, and wherein nitric acid content is 12wt%, and sulfuric acid content is 0.5wt%.
Above-mentioned spent acid and sour vapour are sent into rectifying tower 1, under 64kPa vacuum tightness, carry out rectifying, tower top temperature is 73 ℃, column bottom temperature is 96 ℃, reboiler at the bottom of rectifying tower exports the product after obtain concentrated, and wherein nitric acid content is 45wt%, and sulfuric acid content is 5wt%, send back to nitrification, flow is 3460 kgs/hour again;
The gas phase of rectifying tower 1 tower top enters first-stage condenser 2, carries out condensation and obtain one-level phlegma at 73 ℃, then one-level phlegma is sent back to the tower top of rectifying tower 1, and as the first phegma of rectifying tower 1, reflux ratio is 0.19; Remaining one-level phlegma is arranged to processing outward as nitric acid preconcentration technique waste water, and flow is 7550 kgs/hour, and wherein, the content of nitric acid is 0.9wt%;
The tail gas of first-stage condenser 2 enters secondary condenser 3 again, carries out condensation and obtain B-grade condensation liquid at 59 ℃, then all sends B-grade condensation liquid back to rectifying tower 1 as the second phegma, and this B-grade condensation liquid locates to enter rectifying tower 1 80 ℃ of rectifying tower 1 rectifying section.
Comparative example 1
Adopt the flow process of Fig. 2.
Rectifying tower adopts packing tower, and theoretical plate number is 10.
From the spent acid of the washing procedure of nitrification, flow is 4100 kgs/hour, and wherein the content of nitric acid is 20wt%, and the content of sulfuric acid is 8wt%.From the sour vapour of spent acid stripping process, flow is 7020 kgs/hour, and wherein nitric acid content is 10～12wt%, and sulfuric acid content is 0.2wt%.
Above-mentioned spent acid and sour vapour are sent into rectifying tower 1, rectifying under 60kPa vacuum tightness, tower top temperature is 78 ℃, column bottom temperature is 99 ℃, reboiler at the bottom of rectifying tower exports the product after obtain concentrated, and wherein nitric acid content is at 50wt%, and sulfuric acid content is at 10wt%, send back to nitrification, flow is 3500 kgs/hour again;
The gas phase of rectifying tower 1 tower top enters first-stage condenser 2, carries out condensation and obtain one-level phlegma at 74 ℃, and one-level phlegma is arranged to processing outward as nitric acid preconcentration technique waste water, and flow is 7510 kgs/hour, and wherein, the content of nitric acid is 2wt%;
The tail gas of first-stage condenser 2 enters secondary condenser 3 again, carries out condensation at 60 ℃, then B-grade condensation liquid is all sent back to the tower top of rectifying tower, as the phegma of rectifying tower 1.
Claims (10)
- A dinitrotoluene (DNT) produce in the nitric acid pre-concentration method of waste acid concentration technique, it comprises the steps: to make to enter and in rectifying tower, under the vacuum tightness of 60～64kPa, carry out rectification under vacuum from the spent acid of washing procedure of nitrification and/or the sour vapour of spent acid stripping process, reboiler at the bottom of the being arranged at described rectifying tower concentrated after product of vaporizing to obtain, sends back to nitrification by described concentrated after product; The tower top temperature of described rectifying tower is 73～78 ℃, and column bottom temperature is 95～103 ℃;Wherein, the gas phase that is arranged in the tower top of described rectifying tower enters first-stage condenser and carries out condensation, obtains one-level phlegma, described one-level phlegma is sent back to the tower top of described rectifying tower, and as the first phegma of described rectifying tower, reflux ratio is 0.18～0.2; Waste water using remaining one-level phlegma as nitric acid preconcentration technique is discharged;The tail gas of described first-stage condenser enters secondary condenser again, carry out condensation and obtain B-grade condensation liquid, all send described B-grade condensation liquid back to described rectifying tower as the second phegma, described B-grade condensation liquid locates to enter rectifying tower 80～82 ℃ of the rectifying section of described rectifying tower.
- 2. the method for claim 1, is characterized in that: in the spent acid of the described washing procedure from nitrification, the content of nitric acid is 18～20wt%, and the content of sulfuric acid is 5～8wt%.
- 3. the method for claim 1, is characterized in that: in the sour vapour of described spent acid stripping process, the content of nitric acid is 10～12wt%, and the content of sulfuric acid is 0.2～0.5wt%.
- 4. the method for claim 1, is characterized in that: in described concentrated after product, nitric acid content is 45～50wt%, and sulfuric acid content is 5～10wt%.
- 5. the method as described in any one in claim 1～4, is characterized in that: being condensate at 72～74 ℃ in described first-stage condenser carried out.
- 6. the method as described in any one in claim 1～4, is characterized in that: being condensate at 58～62 ℃ in described secondary condenser carried out.
- 7. method as claimed in claim 5, is characterized in that: being condensate at 58～62 ℃ in described secondary condenser carried out.
- 8. the method for claim 1, is characterized in that: described rectifying tower is packed tower.
- 9. method as claimed in claim 8, is characterized in that: the theoretical plate number of described packed tower is 8～12.
- 10. method as claimed in claim 9, is characterized in that: the theoretical plate number of described packed tower is 10.
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| CN105329864B (en) * | 2015-12-01 | 2017-05-17 | 南京师范大学 | Resourceful treatment method of waste acid solution in nitrobenzene production process |
| CN113786639A (en) * | 2021-10-13 | 2021-12-14 | 中国天辰工程有限公司 | Quenching and dewatering process method for cyclohexanol dehydrogenation product |
| CN114715863B (en) * | 2022-05-06 | 2023-06-13 | 天津大学浙江绍兴研究院 | Nitrifying waste acid recovery process of insoluble organic matters |
| CN115611746A (en) * | 2022-11-02 | 2023-01-17 | 天津大学浙江绍兴研究院 | Process and equipment for continuous nitration production of 3-methyl-2-nitrobenzoic acid |
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| DE10356499B3 (en) * | 2003-12-03 | 2005-06-02 | Qvf Engineering Gmbh | Subazeotropic concentration of nitrogen oxide-containing diluted aqueous waste acids is effected using a dual liquid/vapor feed and 2-stage water vapor condensation |
| CN102030336A (en) * | 2010-12-23 | 2011-04-27 | 江西嘉柏新材料有限公司 | Method for purifying high-purity trichlorosilane |
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| ATE295334T1 (en) * | 2000-05-22 | 2005-05-15 | Qvf Engineering Gmbh | METHOD FOR PRODUCING CONCENTRATED NITRIC ACID AND SYSTEM FOR IMPLEMENTING SUCH A METHOD |
| DE502006001608D1 (en) * | 2006-06-21 | 2008-10-30 | Qvf Engineering Gmbh | Process and installation for concentrating waste sulfuric acids from nitriding processes |
| CN101254906B (en) * | 2008-03-17 | 2010-06-23 | 大连理工大学 | Method and device for vacuum nitric acid gas recovering during preparation of nitric acid |
| EP2295375B1 (en) * | 2009-09-15 | 2016-04-13 | De Dietrich Process Systems GmbH | Method and device for processing waste sulphuric acids from nitration processes |
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| DE10356499B3 (en) * | 2003-12-03 | 2005-06-02 | Qvf Engineering Gmbh | Subazeotropic concentration of nitrogen oxide-containing diluted aqueous waste acids is effected using a dual liquid/vapor feed and 2-stage water vapor condensation |
| CN102030336A (en) * | 2010-12-23 | 2011-04-27 | 江西嘉柏新材料有限公司 | Method for purifying high-purity trichlorosilane |
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