Alkali liquor recovery system for filter-pressing indigo

Abstract

The alkali liquor recovery system comprises a first filter press, a calcining furnace, a dissolving tank, a second filter press, a first concentration evaporator, a mixing kettle, a third filter press, a second evaporation concentrator and a dehydration pot, a filter residue outlet of the first filter press is connected with a feed port of the calcining furnace, a discharge port of the calcining furnace is connected with a feed port of the dissolving tank, the desalted water pipeline is communicated with a water inlet of the dissolving tank, and a liquid outlet of the dissolving tank is communicated with a liquid inlet of the second filter press; a filtrate outlet of the first filter press is communicated with a liquid inlet of the first concentration evaporator, and a liquid outlet of the first concentration evaporator and a filtrate outlet of the second filter press are both communicated with a liquid inlet of the mixing kettle. The utility model has the advantages that the connecting structure is simple and easy to realize, the effective recycling of resources is realized, the environmental pollution caused by stockpiling is avoided, the economic benefit of enterprises is increased, and the environment is protected.

Description

Technical field:

[0001] The utility model relates to an alkali solution recovery system, in particular to an alkali solution recovery system for filter-pressing indigo. Background technology:

[0002] At present, the method for producing indigo is to firstly mix phenylaminoacetonitrile with alkali solution for hydrolysis reaction to obtain potassium (sodium) anilinoacetate, then mix potassium (sodium) anilinoacetate with sodium amide in a reaction kettle for reaction to obtain potassium (sodium) indoxylphenol, then send it to an oxidation kettle and blow air into it for further oxidation to obtain dioxybisindoxylphenol, then filter it through a filter press to obtain an indigo filter cake, the filtrate obtained by the filter press has an alkali concentration of 14-15%, and is sent to an alkali recovery system for recovery, that is, first evaporated and concentrated, then filtered, and the filtrate (alkali concentration) is 14-15%. The precipitate (with a concentration of 45%) is decolorized, evaporated, concentrated and dehydrated to form a mixed alkali as a raw material for mixed reaction with phenylaminoacetonitrile. The treatment methods of the filter residue from the filter press currently mainly include sea discharge method and damming and stockpiling treatment. Since the filter residue also contains a large amount of KOH, NaOH, Na2CO3 and organic matter (the organic matter components are phenylaminoacetonitrile and potassium sodium phenylaminoacetate), the above-mentioned sea discharge method and stockpiling method not only waste KOH, NaOH and Na2CO3 resources, but also cause great harm to the environment, polluting the land, water and atmospheric environment. Utility model content:

[0003] The utility model aims to provide an alkali solution recovery system for filter press indigo which has a simple connection structure, realizes effective resource recycling and utilization, and avoids environmental pollution caused by storage.

[0004] The utility model is implemented by the following technical scheme: The purpose of this patent is to provide an alkali solution recovery system for filter-filtered indigo, which includes a first filter press, a calcining furnace, a dissolving tank, a second filter press, a first concentrating evaporator, a mixing kettle, a third filter press, a second evaporating concentrator and a dehydrating pot; the filter residue outlet of the first filter press is connected to the feed port of the calcining furnace, the discharge port of the calcining furnace is connected to the feed port of the dissolving tank, the desalted water pipeline is connected to the water inlet of the dissolving tank, and the liquid outlet of the dissolving tank is connected to the liquid inlet of the second filter press; the filtrate outlet of the first filter press is connected to the liquid inlet of the first concentrating evaporator, the liquid outlet of the first concentrating evaporator and the filtrate outlet of the second filter press are both connected to the liquid inlet of the mixing kettle, the liquid outlet of the mixing kettle is connected to the liquid inlet of the third filter press, and the filtrate outlet of the third filter press, the second evaporating concentrator and the dehydrating pot are connected in sequence.

[0005] Furthermore, it comprises an incinerator, and the tail gas outlet of the incinerator is connected to the air inlet of the incinerator.

[0006] Furthermore, it also includes a first heat exchanger, a second heat exchanger, a cooler and a condensed water storage tank; the air outlet of the first concentrating evaporator is connected to the hot medium inlet of the first heat exchanger, the filtrate outlet of the first filter press is connected to the cold medium inlet of the first heat exchanger, and the cold medium outlet of the first heat exchanger is connected to the liquid inlet of the first concentrating evaporator; the air outlet of the second evaporation concentrator and the dehydration pot is connected to the hot medium inlet of the second heat exchanger, the filtrate outlet of the third filter press is connected to the cold medium inlet of the second heat exchanger, and the cold medium outlet of the second heat exchanger is connected to the liquid inlet of the second evaporation concentrator; the hot medium outlets of the first heat exchanger and the second heat exchanger are connected to the liquid inlet of the cooler, the liquid outlet of the cooler is connected to the water inlet of the condensed water storage tank, and the water outlet of the condensed water storage tank is connected to the water inlet of the dissolution tank.

[0007] Furthermore, it also includes a triple-effect evaporator and a cold water tank; the liquid outlet of the triple-effect evaporator is connected to the liquid inlet of the cold water tank, and the liquid outlet of the cold water tank is connected to the liquid inlet of the first filter press.

[0008] Furthermore, a spiral channel steel is fixed to the outer wall of the cold water tank; a cooling water inlet is opened below the spiral channel steel, and a cooling water outlet is opened above the spiral channel steel.

[0009] The utility model has the advantages of simple connection structure and easy implementation. Organic matter is removed by calcining the filter residue, and the remaining material contains a large amount of KOH, NaOH and Na2CO3. Then it is dissolved in water and filtered. The remaining solid is treated as hazardous waste. The aqueous solution is sent to a mixing kettle to be mixed with a high-concentration mixed alkali solution. Sodium carbonate is precipitated from the saturated solution. After filtering by a third filter press, the obtained sodium carbonate solid is packaged and sold. The remaining mixed alkali solution is successively evaporated and dehydrated by a second evaporator and a dehydration pot to obtain a dehydrated mixed alkali that is reused as a raw material to react with anilinoacetonitrile to produce anilinoacetic acid potassium (sodium) salt, thereby realizing the effective recycling of resources and avoiding environmental pollution caused by storage, increasing the economic benefits of the enterprise and protecting the environment. Description of the drawings:

[0010] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0012] The first filter press 1, the calcining furnace 2, the dissolving tank 3, the first concentrating evaporator 4, the mixing kettle 5, the third filter press 6, the second evaporating concentrator 7, the dehydrating pot 8, the incinerator 9, the first heat exchanger 10, the second heat exchanger 11, the cooler 12, the condensed water storage tank 13, the triple-effect evaporator 14, the cold water tank 15, the spiral channel steel 16, the desalted water pipeline 17, and the second filter press 18. Specific implementation method:

[0013] Example: Figure 1 As shown, an alkali solution recovery system for filter-filtering indigo includes a first filter press 1, a calcining furnace 2, a dissolving tank 3, a second filter press 18, a first concentrating evaporator 4, a mixing kettle 5, a third filter press 6, a second evaporating concentrator 7, a dehydrating pot 8, an incinerator 9, a first heat exchanger 10, a second heat exchanger 11, a cooler 12, a condensed water storage tank 13, a triple-effect evaporator 14 and a cold water tank 15; the liquid outlet of the triple-effect evaporator 14 is connected to the liquid inlet of the cold water tank 15, and a spiral channel steel 16 is fixed on the outer wall of the cold water tank 15, wherein cooling water is continuously introduced for cooling the cold water tank The solution in 15 is not easy to wear and leak, and has good use effect; a cooling water inlet is provided below the spiral channel steel 16, and a cooling water outlet is provided above the spiral channel steel 16; the liquid outlet of the cold water tank 15 is connected with the liquid inlet of the first filter press 1; the filter residue outlet of the first filter press 1 is connected with the feed inlet of the calcining furnace 2, the tail gas outlet of the calcining furnace 2 is connected with the air inlet of the incinerator 9, the discharge port of the calcining furnace 2 is connected with the feed inlet of the dissolving tank 3, the desalted water pipeline 17 is connected with the water inlet of the dissolving tank 3, and the liquid outlet of the dissolving tank 3 is connected with the liquid inlet of the second filter press 18.

[0014] The filtrate outlet of the first filter press 1 is communicated with the cold medium inlet of the first heat exchanger 10, the cold medium outlet of the first heat exchanger 10 is communicated with the liquid inlet of the first concentrating evaporator 4, the liquid outlet of the first concentrating evaporator 4 and the filtrate outlet of the second filter press 18 are both communicated with the liquid inlet of the mixing kettle 5, the liquid outlet of the mixing kettle 5 is communicated with the liquid inlet of the third filter press, the filtrate outlet of the third filter press 6 is communicated with the cold medium inlet of the second heat exchanger 11, the cold medium outlet of the second heat exchanger 11 is communicated with the liquid inlet of the second evaporation concentrator 7, and the liquid outlet of the second evaporation concentrator 7 is communicated with the liquid inlet of the dehydration pot 8.

[0015] The air outlet of the first concentrating evaporator 4 is connected to the heat medium inlet of the first heat exchanger 10, the air outlets of the second evaporating concentrator 7 and the dehydration pot 8 are connected to the heat medium inlet of the second heat exchanger 11, the heat medium outlets of the first heat exchanger 10 and the second heat exchanger 11 are connected to the liquid inlet of the cooler 12, the liquid outlet of the cooler 12 is connected to the water inlet of the condensed water storage tank 13, and the water outlet of the condensed water storage tank 13 is connected to the water inlet of the dissolution tank 3.

[0016] Working principle: The alkali concentration of the filtrate obtained by pressure filtration is 14-15%, which is sent to the triple-effect evaporator 14 for evaporation and concentration, and then cooled by the cold water tank 15, and then filtered by the first filter press 1. The filtrate (alkali concentration is 45%) is decolorized and evaporated and concentrated by the first concentration evaporator 4, and then sent to the mixing kettle 5. The filter residue is calcined in the calcining furnace 2, and the organic matter is calcined and carbonized. The flue gas generated by the calcination is incinerated in the incinerator 9 and then discharged. The calcined residue is sent to the dissolving tank 3. Under the action of condensed water and desalted water, KOH, NaOH and Na2CO3 are dissolved in water, and the remaining residue After being filtered by the second filter press 18, the aqueous solution is treated as hazardous waste, and the aqueous solution is sent to the mixing kettle 5 to be mixed with the high-concentration mixed alkali solution after evaporation and concentration. Sodium carbonate is precipitated from the saturated solution. After being filtered by the third filter press 6, the obtained sodium carbonate solid is packaged and sold. The remaining mixed alkali solution is evaporated and dehydrated by the second evaporator concentrator 7 and the dehydration pot 8 in turn to obtain dehydrated mixed alkali, which is reused as a raw material and reacted with phenylaminoacetonitrile to produce phenylaminoacetic acid potassium (sodium) salt, thereby realizing the effective recycling of resources, avoiding the pollution of the environment by stockpiling, increasing the economic benefits of the enterprise, and protecting the environment.

[0017] The water vapor evaporated from the first concentrating evaporator 4 is passed through the first heat exchanger 10 to preheat the filtrate to achieve heat recovery. The preheated water vapor is condensed into condensed water through the cooler 12 and then sent to the condensed water storage tank 13 for dissolving the calcined slag, thereby achieving the recycling of water resources; similarly, the water vapor evaporated from the second evaporating concentrator 7 and the dehydration pot 8 is passed through the second heat exchanger 11 to preheat the remaining mixed alkali solution to achieve heat recovery. The preheated water vapor is condensed into condensed water through the cooler 12 and then sent to the condensed water storage tank 13 for dissolving the calcined slag, thereby achieving the recycling of water resources.

[0018] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A alkali solution recovery system for filter-filtering indigo, characterized in that: It includes a first filter press, a calcining furnace, a dissolving tank, a second filter press, a first concentrating evaporator, a mixing kettle, a third filter press, a second evaporating concentrator and a dehydrating pot; the filter residue outlet of the first filter press is connected to the feed port of the calcining furnace, the discharge port of the calcining furnace is connected to the feed port of the dissolving tank, the desalted water pipeline is connected to the water inlet of the dissolving tank, and the liquid outlet of the dissolving tank is connected to the liquid inlet of the second filter press; The filtrate outlet of the first filter press is connected to the liquid inlet of the first concentrating evaporator, the liquid outlet of the first concentrating evaporator and the filtrate outlet of the second filter press are both connected to the liquid inlet of the mixing kettle, the liquid outlet of the mixing kettle is connected to the liquid inlet of the third filter press, and the filtrate outlet of the third filter press, the second evaporation concentrator and the dehydration pot are connected in sequence.

2. The alkali solution recovery system for filter-filtering indigo according to claim 1, characterized in that: The invention comprises an incinerator, wherein the tail gas outlet of the incinerator is communicated with the air inlet of the incinerator.

3. The alkali solution recovery system for filter-filtering indigo according to claim 1, characterized in that: It also includes a first heat exchanger, a second heat exchanger, a cooler and a condensed water storage tank; the air outlet of the first concentrating evaporator is connected to the hot medium inlet of the first heat exchanger, the filtrate outlet of the first filter press is connected to the cold medium inlet of the first heat exchanger, and the cold medium outlet of the first heat exchanger is connected to the liquid inlet of the first concentrating evaporator; the air outlet of the second evaporation concentrator and the dehydration pot is connected to the hot medium inlet of the second heat exchanger, the filtrate outlet of the third filter press is connected to the cold medium inlet of the second heat exchanger, and the cold medium outlet of the second heat exchanger is connected to the liquid inlet of the second evaporation concentrator; the hot medium outlets of the first heat exchanger and the second heat exchanger are connected to the liquid inlet of the cooler, the liquid outlet of the cooler is connected to the water inlet of the condensed water storage tank, and the water outlet of the condensed water storage tank is connected to the water inlet of the dissolution tank.

4. The alkali solution recovery system for filter-filtering indigo according to claim 3, characterized in that: It also includes a triple-effect evaporator and a cold water tank; the liquid outlet of the triple-effect evaporator is connected to the liquid inlet of the cold water tank, and the liquid outlet of the cold water tank is connected to the liquid inlet of the first filter press.

5. The alkali solution recovery system for filter-filtering indigo according to claim 4, characterized in that: A spiral channel steel is fixed on the outer wall of the cold water tank; a cooling water inlet is opened below the spiral channel steel, and a cooling water outlet is opened above the spiral channel steel.

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