System for extracting sodium nitrate from nitrification wastewater

Abstract

The utility model provides a system for extracting sodium nitrate from nitration wastewater, which belongs to the technical field of nitration wastewater treatment and is characterized in that after the reaction of a nitration reaction unit is finished, alkali liquor is added into the nitration reaction unit through an alkali liquor tank, so that nitric acid in a nitration reaction unit system is neutralized to generate sodium nitrate and water; the solution in the nitration reaction unit is conveyed into a centrifugal machine to be centrifuged, 3-nitrocarbazole is separated out, centrifugal mother liquor is conveyed into a mother liquor pool, layering is conducted through the mother liquor pool, sodium nitrate dissolved in a water phase is extracted, sodium nitrate is obtained, and nitric acid is neutralized into sodium nitrate through alkali liquor. Corrosion of nitric acid to follow-up use equipment such as a centrifugal machine is reduced, and the production safety is also improved; and on the other hand, by converting nitric acid into sodium nitrate, the wastewater treatment difficulty is reduced, the extracted sodium nitrate can be sold, and the income is increased.

Description

Technical Field

[0001] The utility model belongs to the technical field of nitrification wastewater treatment, and particularly relates to a system for extracting sodium nitrate from nitrification wastewater. Background Technique

[0002] The crude pigment of permanent violet can finally form the product after five reaction steps of alkylation, nitrification, reduction, condensation and ring closure. During the nitrification process, the generated 3-nitrocarbazole exists in the nitrification mother liquor. After centrifugation, pressure filtration and washing, 3-nitrocarbazole is obtained. After the nitrification mother liquor is simply distilled, part of the chlorobenzene solvent is recovered, and the remaining wastewater and residue enter the environmental protection treatment system, resulting in great difficulty in environmental protection treatment.

[0003] In the prior art, for example, the Chinese invention patent with the application number of 201710308562.6 discloses a method for efficiently treating the nitrification waste liquid of permanent violet. By stratifying the waste liquid generated during the nitrification reaction in the production of permanent violet, the acid concentration of the water layer is adjusted to 25% - 30% with concentrated nitric acid and then it can be returned to the nitrification reaction for continued use; the organic layer is distilled, and at the same time, the organic solvent is recovered. When the concentration of 3-nitrocarbazole in the organic layer is increased to 23% - 27%, the distillation is stopped, the organic layer is cooled and crystallized, 3-nitrocarbazole is crystallized out, filtered and dried, and 3-nitrocarbazole is recovered. The remaining filtrate is continuously distilled until it is evaporated to dryness to obtain the recovered organic solvent and the residue after distillation. The residue after distillation is sold as road asphalt; although the method of this invention reduces the waste of 3-nitrocarbazole, the above-mentioned nitrification waste liquid always contains nitric acid, and nitric acid belongs to a strong corrosive acid. During the whole treatment process, it is easy to cause corrosion to the equipment. Summary of the Invention

[0004] In view of this, the utility model provides a system for extracting sodium nitrate from nitrification wastewater to reduce the corrosion of equipment.

[0005] A system for extracting sodium nitrate from nitrification wastewater includes a nitrification reaction unit and a recovery unit. The recovery unit includes a sodium nitrate extraction module. The sodium nitrate extraction module includes a sodium nitrate separation part and a sodium nitrate purification part. The sodium nitrate separation part includes an alkali solution tank, a centrifuge and a mother liquor tank. The outlet of the alkali solution tank is connected to the inlet of the nitrification reaction unit. The outlet of the nitrification reaction unit is connected to the inlet of the centrifuge. The outlet of the centrifuge is connected to the inlet of the mother liquor tank. The aqueous phase outlet of the mother liquor tank is connected to the sodium nitrate purification part to convert the nitric acid in the nitrification reaction into sodium nitrate and then extract the sodium nitrate.

[0006] Preferably, the sodium nitrate purification section includes a nitrification wastewater storage tank, a first filter, a resin adsorption tower, a first distillation tower, and a suction filter. The inlet of the nitrification wastewater storage tank is connected to the aqueous phase outlet of the mother liquor tank. The outlet of the nitrification wastewater storage tank is connected to the inlet of the first filter. The outlet of the first filter is connected to the inlet of the resin adsorption tower. The outlet of the resin adsorption tower is connected to the inlet of the first distillation tower. The outlet of the first distillation tower is connected to the suction filter.

[0007] Preferably, the sodium nitrate purification section further includes a buffer tank. The inlet of the buffer tank is connected to the outlet of the resin adsorption tower. The outlet of the buffer tank is connected to the inlet of the first distillation tower.

[0008] Preferably, the nitrification reaction unit includes an alkylation product inlet pipe, a nitration kettle, a chlorobenzene storage tank, and a nitric acid storage tank. The alkylation product inlet pipe is connected to the first raw material inlet of the nitration kettle. The outlet of the chlorobenzene storage tank is connected to the solvent inlet of the nitration kettle. The outlet of the nitric acid storage tank is connected to the second raw material inlet of the nitration kettle. The neutralization inlet of the nitration kettle is connected to the outlet of the alkali solution tank.

[0009] Preferably, a first valve is provided on the alkylation product inlet pipe. A second valve is provided on the pipeline connecting the outlet of the chlorobenzene storage tank to the solvent inlet of the nitration kettle. A third valve is provided on the pipeline connecting the outlet of the nitric acid storage tank to the second raw material inlet of the nitration kettle. A fourth valve is provided on the pipeline connecting the neutralization inlet of the nitration kettle to the inlet of the alkali solution tank.

[0010] Preferably, the recovery unit further includes a solvent recovery module and a product recovery module. The inlet of the solvent recovery module is connected to the organic phase outlet of the mother liquor tank. The liquid phase outlet of the solvent recovery module is connected to the reuse inlet of the nitrification reaction unit. The solid phase outlet of the solvent recovery module is connected to the inlet of the product recovery module.

[0011] Preferably, the solvent recovery module includes a second filter and a second distillation kettle. The inlet of the second filter is connected to the organic phase outlet of the mother liquor tank. The outlet of the second filter is connected to the inlet of the second distillation kettle. The liquid phase outlet of the second distillation kettle is connected to the inlet of the nitrification reaction unit. The solid phase outlet of the second distillation kettle is connected to the inlet of the product recovery module.

[0012] Preferably, the product recovery module includes a heating kettle, a cooling crystallizer, a washing tower, and a third filter. The inlet of the heating kettle is connected to the solid phase outlet of the second distillation kettle. The outlet of the heating kettle is connected to the inlet of the cooling crystallizer. The outlet of the cooling crystallizer is connected to the inlet of the washing tower. The outlet of the washing tower is connected to the inlet of the third filter.

[0013] Preferably, the product recovery module further includes a recovery tank. The inlet of the recovery tank is connected to the solid-phase outlet of the second distillation kettle, and the outlet of the recovery tank is connected to the inlet of the heating kettle.

[0014] Preferably, the liquid-phase outlet of the second distillation kettle is also connected to the inlet of the heating kettle, and a fifth valve is provided on the pipeline connecting the liquid-phase outlet of the second distillation kettle and the heating kettle.

[0015] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0016] The system for extracting sodium nitrate from nitrification wastewater of the present utility model includes a nitrification reaction unit and a recovery unit. The recovery unit includes a sodium nitrate extraction module. The sodium nitrate extraction module includes a sodium nitrate separation part and a sodium nitrate purification part. The sodium nitrate separation part includes an alkali solution tank, a centrifuge, and a mother liquor pool. The outlet of the alkali solution tank is connected to the inlet of the nitrification reaction unit. The outlet of the nitrification reaction unit is connected to the inlet of the centrifuge. The outlet of the centrifuge is connected to the inlet of the mother liquor pool. The aqueous-phase outlet of the mother liquor pool is connected to the sodium nitrate purification part. After the reaction in the nitrification reaction unit ends, an alkali solution is added to the nitrification reaction unit through the alkali solution tank, so that the nitric acid in the system of the nitrification reaction unit is neutralized to generate sodium nitrate and water. Then, the solution in the nitrification reaction unit is transported to the centrifuge for centrifugation to separate 3-nitrocarbazole. Then, the centrifugal mother liquor is transported to the mother liquor pool for stratification, and the sodium nitrate dissolved in the aqueous phase is extracted to obtain sodium nitrate. By neutralizing nitric acid with an alkali solution to become sodium nitrate, on the one hand, the corrosion of subsequent equipment such as centrifuges by nitric acid is reduced, and the production safety is improved; on the other hand, by converting nitric acid into sodium nitrate, the difficulty of wastewater treatment is reduced, and the extracted sodium nitrate can be sold externally, increasing the income. Description of the Drawings

[0017] Figure 1 It is a process flow diagram of the system for extracting sodium nitrate from nitrification wastewater.

[0018] In the figure: a system 10 for extracting sodium nitrate from nitrification wastewater, a nitrification reaction unit 100, an alkylation product inlet pipe 110, a first valve 111, a nitration kettle 120, a chlorobenzene storage tank 130, a second valve 131, a nitric acid storage tank 140, a third valve 141, a sodium nitrate extraction module 200, a sodium nitrate separation section 210, an alkali solution tank 211, a fourth valve 2111, a centrifuge 212, a mother liquor tank 213, a sodium nitrate purification section 220, a nitrification wastewater storage tank 221, a first filter 222, a resin adsorption tower 223, a first distillation tower 224, a suction filter 225, a buffer tank 226, a solvent recovery module 300, a second filter 310, a second distillation kettle 320, a product recovery module 400, a heating kettle 410, a fifth valve 411, a cooling crystallizer 420, a washing tower 430, a third filter 440, a recovery tank 450. Specific embodiments

[0019] The following further elaborates in detail on the technical solutions and technical effects of the embodiments of the present utility model in conjunction with the accompanying drawings of the present utility model.

[0020] Please refer to Figure 1 , a system 10 for extracting sodium nitrate from nitrification wastewater, comprising a nitrification reaction unit 100 and a recovery unit. The recovery unit includes a sodium nitrate extraction module 200, and the sodium nitrate extraction module 200 includes a sodium nitrate separation section 210 and a sodium nitrate purification section 220. The sodium nitrate separation section 210 includes an alkali solution tank 211, a centrifuge 212, and a mother liquor tank 213. The outlet of the alkali solution tank 211 is connected to the inlet of the nitrification reaction unit 100. The outlet of the nitrification reaction unit 100 is connected to the inlet of the centrifuge 212. The outlet of the centrifuge 212 is connected to the inlet of the mother liquor tank 213. The aqueous phase outlet of the mother liquor tank 213 is connected to the sodium nitrate purification section 220 to convert nitric acid in the nitrification reaction into sodium nitrate and then extract sodium nitrate.

[0021] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0022] The system 10 for extracting sodium nitrate from nitrification wastewater of the present utility model includes a nitrification reaction unit 100 and a recovery unit. The recovery unit includes a sodium nitrate extraction module 200. The sodium nitrate extraction module 200 includes a sodium nitrate separation part 210 and a sodium nitrate purification part 220. The sodium nitrate separation part 210 includes an alkali solution tank 211, a centrifuge 212, and a mother liquor tank 213. The outlet of the alkali solution tank 211 is connected to the inlet of the nitrification reaction unit 100. The outlet of the nitrification reaction unit 100 is connected to the inlet of the centrifuge 212. The outlet of the centrifuge 212 is connected to the inlet of the mother liquor tank 213. The aqueous phase outlet of the mother liquor tank 213 is connected to the sodium nitrate purification part 220. After the reaction in the nitrification reaction unit 100 ends, an alkali solution is added to the nitrification reaction unit 100 through the alkali solution tank 211, so that the nitric acid in the system of the nitrification reaction unit 100 is neutralized to generate sodium nitrate and water. Then, the solution in the nitrification reaction unit 100 is transported to the centrifuge 212 for centrifugation to separate 3-nitrocarbazole. Then, the centrifuged mother liquor is transported to the mother liquor tank 213, and the mother liquor tank 213 is used for stratification to extract the sodium nitrate dissolved in the aqueous phase to obtain sodium nitrate. By neutralizing nitric acid with an alkali solution to become sodium nitrate, on the one hand, the corrosion of subsequent equipment such as the centrifuge 212 by nitric acid is reduced, and the production safety is also improved; on the other hand, by converting nitric acid into sodium nitrate, the difficulty of wastewater treatment is reduced, and the extracted sodium nitrate can be sold externally, increasing the income.

[0023] Further, the sodium nitrate purification part 220 includes a nitrification wastewater storage tank 221, a first filter 222, a resin adsorption tower 223, a first distillation tower 224, and a suction filter 225. The inlet of the nitrification wastewater storage tank 221 is connected to the aqueous phase outlet of the mother liquor tank 213. The outlet of the nitrification wastewater storage tank 221 is connected to the inlet of the first filter 222. The outlet of the first filter 222 is connected to the inlet of the resin adsorption tower 223. The outlet of the resin adsorption tower 223 is connected to the inlet of the first distillation tower 224. The outlet of the first distillation tower 224 is connected to the suction filter 225. The aqueous phase separated by the mother liquor tank 213 is first stored in the nitrification wastewater storage tank 221. After storing a certain amount, the nitrification aqueous phase in the nitrification wastewater storage tank 221 is transported to the first filter 222 for filtering to remove impurities and prevent it from affecting the resin adsorption tower 223. Then, the filtered nitrification aqueous phase is transported to the resin adsorption tower 223 for adsorption to perform adsorption decolorization. Then, the decolorized nitrification aqueous phase is transported to the first distillation tower 224 for vacuum distillation, and then suction filtration is performed through the suction filter 225 to obtain sodium nitrate.

[0024] Further, the sodium nitrate purification unit 220 further includes a buffer tank 226. The inlet of the buffer tank 226 is connected to the outlet of the resin adsorption tower 223, and the outlet of the buffer tank 226 is connected to the inlet of the first distillation tower 224.

[0025] Further, the nitration reaction unit 100 includes an alkylation product inlet pipe 110, a nitration kettle 120, a chlorobenzene storage tank 130, and a nitric acid storage tank 140. The alkylation product inlet pipe 110 is connected to the first raw material inlet of the nitration kettle 120. The outlet of the chlorobenzene storage tank 130 is connected to the solvent inlet of the nitration kettle 120. The outlet of the nitric acid storage tank 140 is connected to the second raw material inlet of the nitration kettle 120. The neutralization inlet of the nitration kettle 120 is connected to the outlet of the lye tank 211. The alkylation product is transported to the nitration kettle 120 through the alkylation product inlet pipe 110. Then, chlorobenzene in the chlorobenzene storage tank 130 and nitric acid in the nitric acid storage tank 140 are input into the nitration kettle 120 to generate 3-nitrocarbazole products.

[0026] Further, a first valve 111 is provided on the alkylation product inlet pipe 110. A second valve 131 is provided on the pipeline connecting the outlet of the chlorobenzene storage tank 130 to the solvent inlet of the nitration kettle 120. A third valve 141 is provided on the pipeline connecting the outlet of the nitric acid storage tank 140 to the second raw material inlet of the nitration kettle 120. A fourth valve 2111 is provided on the pipeline connecting the neutralization inlet of the nitration kettle 120 to the inlet of the lye tank 211 to control the order of material addition.

[0027] Further, the recovery unit further includes a solvent recovery module 300 and a product recovery module 400. The inlet of the solvent recovery module 300 is connected to the organic phase outlet of the mother liquor pool 213. The liquid phase outlet of the solvent recovery module 300 is connected to the reuse inlet of the chlorobenzene storage tank 130. The solid phase outlet of the solvent recovery module 300 is connected to the inlet of the product recovery module 400. The chlorobenzene solvent is recovered by the solvent recovery module 300, and the residual 3-nitrocarbazole in the organic phase is recovered by the product recovery module 400 to improve the yield and reduce waste.

[0028] Further, the solvent recovery module 300 includes a second filter 310 and a second distillation kettle 320. The inlet of the second filter 310 is connected to the organic phase outlet of the mother liquor tank 213. The outlet of the second filter 310 is connected to the inlet of the second distillation kettle 320. The liquid phase outlet of the second distillation kettle 320 is connected to the reuse inlet of the chlorobenzene storage tank 130. The solid phase outlet of the second distillation kettle 320 is connected to the inlet of the product recovery module 400, so as to filter and distill the organic phase separated from the mother liquor tank 213, recover the chlorobenzene solvent, and the recovered chlorobenzene solvent is used for the nitration reaction and the recovery of 3-nitrocarbazole.

[0029] Further, the product recovery module 400 includes a heating kettle 410, a cooling crystallizer 420, a washing tower 430, and a third filter 440. The inlet of the heating kettle 410 is connected to the solid phase outlet of the second distillation kettle 320. The outlet of the heating kettle 410 is connected to the inlet of the cooling crystallizer 420. The outlet of the cooling crystallizer 420 is connected to the inlet of the washing tower 430. The outlet of the washing tower 430 is connected to the inlet of the third filter 440. The distillation residue after distillation in the second distillation kettle 320 is collected and transported into the heating kettle 410, heated and dissolved with a small amount of chlorobenzene solvent, then cooled and crystallized by the cooling crystallizer 420, and then washed and filtered by the washing tower 430 to recover 3-nitrocarbazole, so as to improve the yield of 3-nitrocarbazole.

[0030] Further, the product recovery module 400 further includes a recovery tank 450. The inlet of the recovery tank 450 is connected to the solid phase outlet of the second distillation kettle 320. The outlet of the recovery tank 450 is connected to the inlet of the heating kettle 410.

[0031] Further, the liquid phase outlet of the second distillation kettle 320 is also connected to the inlet of the heating kettle 410, and a fifth valve 411 is provided on the pipeline connecting the liquid phase outlet of the second distillation kettle 320 and the heating kettle 410.

[0032] What is disclosed above is only the preferred embodiment of the present utility model. Of course, it cannot be used to limit the scope of rights of the present utility model. Those of ordinary skill in the art can understand all or part of the processes of the above embodiments, and the equivalent changes made according to the claims of the present utility model still fall within the scope covered by the utility model.

Claims

1. A system for extracting sodium nitrate from nitrification wastewater, characterized in that It includes a nitration reaction unit and a recovery unit. The recovery unit includes a sodium nitrate extraction module, and the sodium nitrate extraction module includes a sodium nitrate separation part and a sodium nitrate purification part. The sodium nitrate separation part includes an alkali solution tank, a centrifuge, and a mother liquor tank. The outlet of the alkali solution tank is connected to the inlet of the nitration reaction unit. The outlet of the nitration reaction unit is connected to the inlet of the centrifuge. The outlet of the centrifuge is connected to the inlet of the mother liquor tank. The aqueous phase outlet of the mother liquor tank is connected to the sodium nitrate purification part to convert nitric acid in the nitration reaction into sodium nitrate and then extract sodium nitrate.

2. The system for extracting sodium nitrate from nitrification wastewater according to claim 1, characterized in that, The sodium nitrate purification part includes a nitration wastewater storage tank, a first filter, a resin adsorption tower, a first distillation tower, and a suction filter. The inlet of the nitration wastewater storage tank is connected to the aqueous phase outlet of the mother liquor tank. The outlet of the nitration wastewater storage tank is connected to the inlet of the first filter. The outlet of the first filter is connected to the inlet of the resin adsorption tower. The outlet of the resin adsorption tower is connected to the inlet of the first distillation tower. The outlet of the first distillation tower is connected to the suction filter.

3. The system for extracting sodium nitrate from nitrification wastewater according to claim 2, wherein The sodium nitrate purification part further includes a buffer tank. The inlet of the buffer tank is connected to the outlet of the resin adsorption tower. The outlet of the buffer tank is connected to the inlet of the first distillation tower.

4. The system for extracting sodium nitrate from nitrification wastewater according to claim 1, characterized in that, The nitration reaction unit includes an alkylation product inlet pipe, a nitration kettle, a chlorobenzene storage tank, and a nitric acid storage tank. The alkylation product inlet pipe is connected to the first raw material inlet of the nitration kettle. The outlet of the chlorobenzene storage tank is connected to the solvent inlet of the nitration kettle. The outlet of the nitric acid storage tank is connected to the second raw material inlet of the nitration kettle. The neutralization inlet of the nitration kettle is connected to the outlet of the alkali solution tank.

5. The system for extracting sodium nitrate from nitrification wastewater according to claim 4, characterized in that, A first valve is provided on the alkylation product inlet pipe. A second valve is provided on the pipeline where the outlet of the chlorobenzene storage tank is connected to the solvent inlet of the nitration kettle. A third valve is provided on the pipeline where the outlet of the nitric acid storage tank is connected to the second raw material inlet of the nitration kettle. A fourth valve is provided on the pipeline where the neutralization inlet of the nitration kettle is connected to the inlet of the alkali solution tank.

6. The system for extracting sodium nitrate from nitrification wastewater according to claim 1, characterized in that, The recovery unit further includes a solvent recovery module and a product recovery module. The inlet of the solvent recovery module is connected to the organic phase outlet of the mother liquor tank. The liquid phase outlet of the solvent recovery module is connected to the reuse inlet of the nitration reaction unit. The solid phase outlet of the solvent recovery module is connected to the inlet of the product recovery module.

7. The system for extracting sodium nitrate from nitrification wastewater according to claim 6, characterized in that, The solvent recovery module includes a second filter and a second distillation kettle. The inlet of the second filter is connected to the organic phase outlet of the mother liquor tank. The outlet of the second filter is connected to the inlet of the second distillation kettle. The liquid phase outlet of the second distillation kettle is connected to the inlet of the nitration reaction unit. The solid phase outlet of the second distillation kettle is connected to the inlet of the product recovery module.

8. The system for extracting sodium nitrate from nitrification wastewater according to claim 7, characterized in that, The product recovery module includes a heating kettle, a cooling crystallizer, a washing tower, and a third filter. The inlet of the heating kettle is connected to the solid-phase outlet of the second distillation kettle, the outlet of the heating kettle is connected to the inlet of the cooling crystallizer, the outlet of the cooling crystallizer is connected to the inlet of the washing tower, and the outlet of the washing tower is connected to the inlet of the third filter.

9. The system for extracting sodium nitrate from nitrification wastewater as claimed in claim 8, wherein, The product recovery module further includes a recovery tank. The inlet of the recovery tank is connected to the solid-phase outlet of the second distillation kettle, and the outlet of the recovery tank is connected to the inlet of the heating kettle.

10. The system for extracting sodium nitrate from nitrification wastewater as claimed in claim 8, wherein, The liquid-phase outlet of the second distillation kettle is also connected to the inlet of the heating kettle, and a fifth valve is provided on the pipeline connecting the liquid-phase outlet of the second distillation kettle and the heating kettle.

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