CN111675416A - Recycling process and device for salt-containing waste sulfuric acid - Google Patents
Recycling process and device for salt-containing waste sulfuric acid Download PDFInfo
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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
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- 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
- C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
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- C02F2101/101—Sulfur compounds
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- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
- C02F2103/36—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the manufacture of organic compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F2301/00—General aspects of water treatment
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F2303/00—Specific treatment goals
- C02F2303/14—Maintenance of water treatment installations
Abstract
The invention discloses a process and a device for recycling waste sulfuric acid containing salt. The recycling process of the waste sulfuric acid containing salt comprises the following steps: the method comprises the steps of carrying out countercurrent stage-by-stage effect preheating on the feed liquid containing the salt waste sulfuric acid, then carrying out cocurrent evaporation, introducing into an acid bath to be used as an evaporation crystallization carrier, and finally extracting the sulfate by a last effect or last double effect one-step method. According to the characteristics of waste acid to be treated, the invention adopts a process route of 'feed liquid countercurrent stage-by-stage efficient preheating, cocurrent flow evaporation, acid guiding bath as an evaporation crystallization carrier, and final or final two-effect one-step method for extracting sulfate', so that the purposes of extracting sulfate and returning the waste acid to an acid station workshop for recycling in the viscose production process are realized, and the current situation of high-salt wastewater discharge in the viscose production process is changed.
Description
Technical Field
The invention belongs to the technical field of viscose fiber production, and particularly relates to a process and a device for recycling salt-containing waste sulfuric acid.
Background
In the spinning and refining process of a spinning workshop of viscose fiber production enterprises, a large amount of salt-containing acidic wastewater is brought out in the scouring and washing processes, wherein sulfuric acid, zinc sulfate and aluminum sulfate are materials which must be supplemented every day in the spinning process, and sodium sulfate is a material which is generated by the reaction of sulfuric acid and sodium hydroxide in the spinning production process and must be removed. Usually, the two streams of water generated in the spinning car are directly discharged after neutralization, biochemical treatment and the like. However, the method not only produces a large amount of wastewater with high salt content, but also discharges useful substances together, thereby causing environmental pollution on the one hand and causing unnecessary economic loss on the other hand. With the stricter environmental protection and the continuous advocation of the concept of circular economy, how to treat the saline acid wastewater in an environmental-friendly and economic way becomes an important subject of the viscose industry.
Disclosure of Invention
The invention mainly aims to provide a process and a device for recycling salt-containing waste sulfuric acid, so as to overcome the defects in the prior art.
In order to achieve the purpose of the invention, the technical scheme adopted by the embodiment of the invention comprises the following steps:
the embodiment of the invention provides a recycling process of waste sulfuric acid containing salt, which comprises the following steps: the method comprises the steps of carrying out countercurrent stage-by-stage effect preheating on the feed liquid containing the salt waste sulfuric acid, then carrying out cocurrent evaporation, introducing into an acid bath to be used as an evaporation crystallization carrier, and finally extracting the sulfate by a last effect or last double effect one-step method.
The feed liquid is preheated by adopting countercurrent step-by-step effect, namely secondary steam among various effects is adopted as a preheating heat source, so that the fresh steam consumption is effectively reduced, and the steam-water ratio is reduced; parallel flow evaporation is adopted, the viscosity of the treated feed liquid is lower in a low-temperature section, solid-liquid separation can be realized in the low-temperature section, low-temperature discharging is realized, and the heat loss of a system is reduced; introducing an acid bath carrier, on one hand, in order to slow down the rapid rise of the boiling point of the feed liquid caused by the continuous increase of the concentration of sulfuric acid in the evaporation rear section and reduce the effective temperature difference among the effects, on the other hand, the concentration of sodium sulfate in the acid bath is close to saturation, and the evaporation amount is not excessively increased when the sodium sulfate in the solution is extracted; the anhydrous sodium sulfate is extracted by the last effect or last double effect one-step method, and the anhydrous sodium sulfate can be directly extracted when the temperature of the sodium sulfate solution is above 32.8 ℃, so that links of freezing crystallization, roasting and the like in the traditional method are omitted, the investment is saved, and the energy consumption is reduced.
Further, the mass of the introduced acid bath was recorded as WyThe concentration of sulfuric acid introduced into the acid bath is denoted XyThe mass of the initial evaporation feed liquid is recorded as WlThe quality of the last-effect evaporation feed liquid is recorded as WmThe concentration of sulfuric acid in the initial evaporation feed is recorded as XlThe concentration of sulfuric acid in the final-effect evaporation feed liquid is marked as XmThen, the following conditions are satisfied:
the embodiment of the invention also provides a recycling device of the salt-containing waste sulfuric acid, which is mainly applied to the recycling process of the salt-containing waste sulfuric acid and comprises the following components:
the multi-effect inter-effect preheating system is at least used for carrying out countercurrent stage-by-stage inter-effect preheating on the feed liquid containing the salt waste sulfuric acid;
the multi-effect evaporation system is at least used for carrying out cocurrent evaporation on the preheated feed liquid;
an acid bath feed system for at least introducing an acid bath;
a sulfate extraction system for at least extracting sulfate from a last-effect evaporation or a last-double-effect evaporation.
Further, the multiple-effect evaporation system comprises an n-effect evaporation crystallization device, the multiple-effect preheating system comprises an n-1-effect inter-preheater, the position of the evaporation crystallization device introduced into the acid bath in the acid bath feeding system is 1-n-1 effect, and n is any integer between 5 and 7.
Further, the recycling device for the waste sulfuric acid containing salt also comprises an alkaline washing system which is at least used for cleaning the multi-effect inter-effect preheating system and the multi-effect evaporation system.
Compared with the prior art, the invention has the following beneficial effects:
according to the recycling process and device for the waste sulfuric acid containing salt, disclosed by the invention, through multi-effect evaporation, useful materials such as sodium sulfate, sulfuric acid, zinc sulfate, aluminum sulfate and the like in the acidic waste water containing salt are taken out according to an advanced steam-water ratio in the industry and returned to an acid station for recycling, meanwhile, the discharge of the waste water containing salt is reduced, the purposes of extracting sulfate in the viscose production process and returning the waste acid to the acid station workshop for recycling are realized, and the current situation of high-salt waste water discharge in the viscose fiber production process is.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a flow chart of the process for recycling the waste sulfuric acid containing salt.
FIG. 2 is a process flow diagram of the device for recycling the waste sulfuric acid containing salt.
FIG. 3 is a process flow diagram of a device for recycling waste sulfuric acid containing salt in embodiment 1 of the invention.
FIG. 4 is a process flow diagram of a device for recycling waste sulfuric acid containing salt in embodiment 2 of the present invention.
Detailed Description
The present invention will be more fully understood from the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed embodiment.
In view of the defects of the prior art, the inventor of the present invention provides a technical scheme of the present invention through long-term research and a great deal of practice, and mainly aims at that a great deal of high-salt-content wastewater generated in the existing viscose fiber production process is directly discharged, and useful substances in the high-salt-content wastewater are discharged together, so that on one hand, environmental pollution is caused, and on the other hand, unnecessary economic loss is caused. The technical solution, its implementation and principles will be further explained as follows.
The embodiment of the invention provides a recycling process of waste sulfuric acid containing salt, which comprises the following steps: the method comprises the steps of carrying out countercurrent stage-by-stage effect preheating on the feed liquid containing the salt waste sulfuric acid, then carrying out cocurrent evaporation, introducing into an acid bath to be used as an evaporation crystallization carrier, and finally extracting the sulfate by a last effect or last double effect one-step method.
The feed liquid is preheated by adopting countercurrent step-by-step effect, namely secondary steam among various effects is adopted as a preheating heat source, so that the fresh steam consumption is effectively reduced, and the steam-water ratio is reduced; parallel flow evaporation is adopted, the viscosity of the treated feed liquid is lower in a low-temperature section, solid-liquid separation can be realized in the low-temperature section, low-temperature discharging is realized, and the heat loss of a system is reduced; introducing an acid bath carrier, on one hand, in order to slow down the rapid rise of the boiling point of the feed liquid caused by the continuous increase of the concentration of sulfuric acid in the evaporation rear section and reduce the effective temperature difference among the effects, on the other hand, the concentration of sodium sulfate in the acid bath is close to saturation, and the evaporation amount is not excessively increased when the sodium sulfate in the solution is extracted; the anhydrous sodium sulfate is extracted by the last effect or last double effect one-step method, and the anhydrous sodium sulfate can be directly extracted when the temperature of the sodium sulfate solution is above 32.8 ℃, so that links of freezing crystallization, roasting and the like in the traditional method are omitted, the investment is saved, and the energy consumption is reduced.
In some preferred versions of embodiments of the present invention, the mass of the introduced acid bath is denoted as WyThe concentration of sulfuric acid introduced into the acid bath is denoted XyThe mass of the initial evaporation feed liquid is recorded as WlThe quality of the last-effect evaporation feed liquid is recorded as WmThe concentration of sulfuric acid in the initial evaporation feed is recorded as XlThe concentration of sulfuric acid in the final-effect evaporation feed liquid is marked as XmThen, the following conditions are satisfied:
in some preferred embodiments, the concentration of sulfuric acid in the final-effect evaporation feed liquid is 7.5% ≦ Xm≤25％。
In some preferred embodiments, the concentration of sodium sulfate in the salt-containing waste sulfuric acid solution is 20 g/L-150 g/L, and the concentration of sulfuric acid is 5 g/L-30 g/L.
The embodiment of the invention also provides a recycling device of the salt-containing waste sulfuric acid, which is mainly applied to the recycling process of the salt-containing waste sulfuric acid and comprises the following components:
the multi-effect inter-effect preheating system is at least used for carrying out countercurrent stage-by-stage inter-effect preheating on the feed liquid containing the salt waste sulfuric acid;
the multi-effect evaporation system is at least used for carrying out cocurrent evaporation on the preheated feed liquid;
an acid bath feed system for at least introducing an acid bath;
a sulfate extraction system for at least extracting sulfate from a last-effect evaporation or a last-double-effect evaporation.
In some preferred embodiments, the multiple-effect evaporation system comprises an n-effect evaporation crystallization device, the multiple-effect preheating system comprises an n-1-effect inter-effect preheater, the position of the acid bath in the acid bath feeding system, which is introduced into the evaporation crystallization device, is 1-n-1 effects, wherein n is any integer between 5 and 7.
In some preferred embodiments, the n-effect evaporative crystallization device comprises n inter-effect evaporation chambers arranged in parallel and a falling film evaporator or a forced circulation heater respectively communicated with the inter-effect evaporation chambers, wherein the first 2-6 inter-effect evaporation chambers are arranged in communication with the falling film evaporator, and the last 1-4 inter-effect evaporation chambers are arranged in communication with the forced circulation heater.
In some preferred embodiments, the acid bath feeding system comprises a feeding tank and an acid pipeline, wherein the feeding tank is arranged behind the n-1-effect inter-preheater, and the acid pipeline sequentially passes through the n-1-effect inter-preheater reversely from the feeding tank and then passes through the n-effect evaporative crystallization device sequentially and sequentially.
In some preferred embodiments, the sulfate extraction system comprises a hydrocyclone and a centrifuge in sequential communication with the last effect evaporation chamber via a solid-liquid phase line, wherein the hydrocyclone can also be replaced with a thickener.
In some preferred embodiments, the recycling device for the waste sulfuric acid containing salt further comprises an effective condensed water flash tank arranged corresponding to the effective evaporative crystallization device.
In some preferred embodiments, the last-effect evaporation chamber is also sequentially communicated with a secondary steam condenser and a vacuum device through a gas pipeline; in one embodiment, the vacuum device may be a vacuum injection system, but is not limited thereto.
In some preferred embodiments, the recycling device for the waste sulfuric acid containing salt further comprises a caustic washing system, which is at least used for cleaning the multi-effect inter-effect preheating system and the multi-effect evaporation system.
In order to ensure that the recycling device of the waste sulfuric acid containing salt can stably operate, the systems can smoothly operate in a matched manner by arranging auxiliary equipment such as an effect room transfer pump, a forced circulation pump, a nitrate pump, a feed pump and the like.
In some specific embodiments, the heat exchange tube of the falling film evaporator or the forced circulation heater may be made of graphite or metal, the forced circulation pump may be suspended or horizontal, and the impeller of the forced circulation pump and the portion thereof contacting with the material may be made of corrosion-resistant and abrasion-resistant materials such as nickel-based materials or dual-phase steel.
In some more specific embodiments, as shown in fig. 1, salt-containing waste sulfuric acid from outside is fed into a feeding tank, an acid bath from an acid station is introduced into the feeding tank to serve as an evaporation crystallization carrier, then a feed liquid containing the salt-containing waste sulfuric acid is subjected to n-1 effect countercurrent stage-by-stage preheating through a multi-effect preheating system, then is subjected to cocurrent evaporation through the n-effect preheating system, fresh steam is fed into a first-effect evaporation crystallization device, a clear liquid obtained after final effect evaporation is fed into a boundary region through a clear liquid pump to realize the recycling of useful substances (such as useful substances including sulfuric acid, zinc sulfate, aluminum sulfate and the like) in acid wastewater, a solid-containing liquid phase sequentially enters a hydrocyclone (or a thickener) and a centrifugal separator through a nitrate pump and then undergoes solid-liquid separation, a solid phase is discharged from the boundary region through a belt conveyor to produce industrial grade anhydrous sodium sulfate, and a mother liquid is returned to the last.
In some more specific embodiments, as shown in fig. 2, the salt-containing waste sulfuric acid from outside is preheated by 4-6 stages through a multi-effect intermediate preheating system, the used heat source is secondary steam flashed from an evaporation chamber of the evaporation crystallization device, the discharge temperature of each effect preheater is close to the temperature of the used secondary steam, the salt-containing acidic wastewater preheated by each effect enters a first effect evaporation crystallization device, the first effect heating steam is saturated fresh steam at about 130 ℃, the fresh steam and the salt-containing acidic wastewater are evaporated in a concurrent flow manner, the supplemented acid bath crystallization carrier is mixed with the salt-containing acidic wastewater at 1-5 effects by heating or not heating for subsequent evaporation, condensed water condensed by each effect enters a condensed water flash tank, the flashed secondary steam is mixed with the secondary steam from the evaporation crystallization device for next effect evaporation, and the flashed condensed water flows into the next effect flash tank, mixed with the next effect of condensed water and then flashed. The salt-containing waste sulfuric acid is discharged through a salt foot at the last effect or the last double effect, the discharged solid-liquid mixture enters a hydrocyclone or a thickener, the liquid phase discharged from the hydrocyclone or the thickener returns to an acid station, and the solid phase is further dehydrated by a centrifugal separator. The secondary steam from the last effect evaporation chamber enters a secondary steam condenser, the secondary steam condenser can be indirectly condensed or directly condensed, and the non-condensable gas is discharged through a vacuum device.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further explained with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention, and that experimental conditions and set parameters therein are not to be considered as limitations of the basic embodiments of the invention. And the scope of the present invention is not limited to the following examples. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example 1
Referring to fig. 3, the recycling device for waste sulfuric acid containing salt provided by the embodiment of the invention comprises an I-effect falling-film evaporator H1, an I-effect evaporation chamber V1, an II-effect falling-film evaporator H2, an II-effect evaporation chamber V2, an III-effect forced circulation heater H3, an III-effect evaporation chamber V3, an IV-effect forced circulation heater H4, an IV-effect evaporation chamber V4, a V-effect forced circulation heater H5, a V-effect evaporation chamber V5, an effect transfer pump P1, P2, a forced circulation pump P3, P4, P5, a saltpeter pump P6, a feed pump P7, an effect preheater Y1, Y2, Y3, Y4, Y5, a condensed water flash tank VP1, VP2, VP3, VP4, VP5, a secondary steam condenser LN, a cyclone separator X1, a centrifugal separator X2, a vacuum injection system X3, and a charging tank T.
The acid circuit pipeline 1 is connected with Y5, Y4, Y3, Y2, Y1, H1, V1, H2, V2, H3, V3, H4, V4, H5 and V5 in sequence, a liquid phase from V5 is recycled to an acid station, a solid-liquid phase from a salt foot is removed from a hydrocyclone X1 and a centrifugal separator X2, a solid phase is removed from the boundary, and a liquid phase is returned to V5.
The condensate of each effect enters a corresponding condensate water flash tank from a condensate pipeline 4 at the bottom of each effect preheater (except a V-effect preheater), a falling film evaporator or a forced circulation heater, the condensate after flash evaporation enters a next effect condensate water flash tank one by one, and the condensate from the V-effect condensate water flash tank passes through a condensate water pump P7 and then passes through a V-effect preheater Y5 to be sent out of a boundary area.
The mass introduced into the acid bath is recorded as WyThe concentration of sulfuric acid introduced into the acid bath is denoted XyThe mass of the initial evaporation feed liquid is recorded as WlThe quality of the last-effect evaporation feed liquid is recorded as WmThe concentration of sulfuric acid in the initial evaporation feed is recorded as XlThe concentration of sulfuric acid in the final-effect evaporation feed liquid is marked as XmAnd (3) the acid wastewater containing salt from the outside enters a feed tank T by calculating the required acid bath according to the following formula:
after being uniformly mixed in a feeding tank T, the mixed feed liquid sequentially passes through a preheater Y5, a preheater Y4, a preheater Y3, a preheater Y2 and a preheater Y1 by a feeding pump P7, the mixed feed liquid is heated to about 112 ℃, the preheated feed liquid enters an I-effect falling-film evaporator H1, the feed liquid uniformly distributes in a film shape in an I-effect falling-film evaporator H1 pipe and is evaporated in the pipe, the heated gas-liquid mixture is further subjected to gas-liquid separation in an I-effect evaporation chamber V1, a gas phase enters a shell pass of an II-effect falling-film evaporator H2 by a gas pipeline 5, a liquid phase enters a tube pass of the II-effect falling-film evaporator H2 by a material transfer pump P1, the gas-liquid mixture from a tube pass of the II-effect falling-film evaporator H2 enters a II-effect evaporation chamber V2 for further gas-liquid separation, the gas phase enters a shell pass of a III-effect forced circulation heater H3 by a gas pipeline 5. Feed liquid is heated in a III-effect forced circulation heater H3 and then enters a III-effect evaporation chamber V3, gas and liquid are separated in the evaporation chamber, gas phase enters an IV-effect forced circulation heater H4 shell pass through a gas pipeline 5, liquid phase enters a circulation pipe of an IV-effect forced circulation heater H4 through an inter-effect pressure difference self-flow through a material transfer pipeline, feed liquid is heated in an IV-effect forced circulation heater H4 and then enters an IV-effect evaporation chamber V4, gas and liquid are separated in the evaporation chamber, gas phase enters a V-effect forced circulation heater H5 shell pass through a gas pipeline, liquid phase enters a circulation pipe of a V-effect forced circulation heater H5 through an inter-effect pressure difference self-flow through a material transfer pipeline, feed liquid is heated in a V-effect forced circulation heater H5 and then enters a V-effect evaporation chamber V5, gas and liquid are separated in the evaporation chamber, gas phase enters a secondary gas condenser LN through a gas pipeline 5, the condensed liquid phase exits a boundary area, non, and the solid-containing liquid phase sequentially enters a hydrocyclone X1 and a centrifugal separator X2 through a nitrate pump and then undergoes centrifugal solid-liquid separation, the solid phase is discharged out of the battery compartment through a belt conveyor, the liquid phase returns to the V-effect evaporation chamber V5, and the supernatant is sent to the battery compartment from the upper part of the V-effect evaporation chamber V5 through a clear liquid pump to realize the recycling of useful substances in the acidic wastewater.
The 170 ℃ superheated fresh steam outside the boundary region is reduced to 130 ℃ saturated steam through the temperature and pressure reducer 3, the 130 ℃ saturated steam enters the shell pass of the I-effect heater H1, and the salt-containing waste sulfuric acid in the pipe is heated.
The scaling condition of the outer walls of the falling-film evaporator and the forced circulation heater and the heat exchange efficiency of an evaporation system are regularly observed, when the heat exchange efficiency is obviously reduced, the evaporation is stopped, alkali liquor with certain concentration is used for cleaning the tube side and the shell side of the falling-film evaporator and the forced circulation heater according to an alkali washing pipeline system, and the heat exchange efficiency of the heat exchanger can be effectively recovered in the process.
Example 2
Referring to fig. 4, the recycling device for waste sulfuric acid containing salt provided by the embodiment of the present invention includes an I-effect falling-film evaporator H1, an I-effect evaporation chamber V1, an II-effect falling-film evaporator H2, an II-effect evaporation chamber V2, an III-effect falling-film evaporator H3, an III-effect evaporation chamber V3, an IV-effect forced circulation heater H4, an IV-effect evaporation chamber V4, a V-effect forced circulation heater H5, a V-effect evaporation chamber V5, a VI-effect forced circulation heater H6, a VI-effect evaporation chamber V6, an effect indirect pump P1, P2, P3, a forced circulation pump P4, P5, a P6, a nitrate slurry pump P7, a feed pump P8, an effect indirect preheater Y1, a Y2, a Y3, a Y4, a Y5, a Y6, a condensed water flash tank VP1, a VP2, a VP3, a VP4, a secondary vapor-liquid separator X, a vacuum feeding tank 4, a vacuum separator X feeding tank.
The acid circuit pipeline 1 is connected with Y6, Y5, Y4, Y3, Y2, Y1, H1, V1, H2, V2, H3, V3, H4, V4, H5, V5, H6 and V6 in sequence, a liquid phase from V6 is recycled to an acid station, a solid-liquid phase from a salt foot is removed from a hydrocyclone and a centrifugal separator, a solid phase is removed from the boundary, and a liquid phase is returned to V6.
The condensate of each effect enters a corresponding condensate water flash tank from a condensate pipeline 4 at the bottom of each effect preheater (except the VI effect preheater), the falling film evaporator or the forced circulation heater, the condensate after flash evaporation enters a next effect condensate water flash tank one by one, and the condensate from the VI effect condensate water flash tank is delivered out of a boundary area after passing through a VI effect preheater Y6 by a condensate water pump P9.
The method comprises the steps of enabling salt-containing acidic wastewater outside the boundary to enter a feeding tank T, enabling the salt-containing acidic wastewater to sequentially pass through a preheater Y6, a preheater Y5, a preheater Y4, a preheater Y3, a preheater Y2 and a preheater Y1 through a feeding pump P8, enabling the mixed feed liquid to be heated to about 112 ℃, enabling the preheated feed liquid to enter an I-effect falling-film evaporator H1, enabling the feed liquid to uniformly distribute in an I-effect falling-film evaporator H1 tube to flow in a film shape and evaporate in the tube, enabling the heated gas-liquid mixture to further undergo gas-liquid separation in an I-effect evaporation chamber V1, enabling a gas phase to enter a II-effect falling-film evaporator H2 shell pass through a gas pipeline 5, enabling a liquid phase to enter a II-effect falling-film evaporator H2 tube pass through a material transfer pump P1, enabling the gas-liquid mixture from an II-effect falling-film H2 tube pass through an II-effect evaporation chamber V2 to further undergo gas-liquid separation, enabling a gas phase to enter a III-effect falling-film evaporator H3 shell pass through a gas, gas phase enters an IV-effect forced circulation heater H4 shell pass through a gas pipeline, liquid phase enters an IV-effect forced circulation heater H4 circulating pipe through a material transfer pump P3, feed liquid enters an IV-effect evaporation chamber V4 after being heated in the IV-effect forced circulation heater H4, gas and liquid are separated in the evaporation chamber, gas phase enters a V-effect forced circulation heater H5 shell pass through a gas pipeline, liquid phase enters a circulating pipe of a V-effect forced circulation heater H5 through an inter-effect pressure difference self-current flow through a material transfer pipeline, feed liquid enters a V-effect evaporation chamber V5 after being heated in the V-effect forced circulation heater H5, gas and liquid are separated in the evaporation chamber, gas phase enters a VI-effect forced circulation heater shell pass through a gas pipeline, liquid phase enters a VI-effect forced circulation heater through an inter-effect pressure difference self-current flow through a material transfer pipeline, feed liquid phase enters a VI-effect forced circulation heater V6 after being heated in the VI-effect forced circulation heater, the gas phase enters a secondary steam condenser LN through a gas pipeline 5, the condensed liquid phase is discharged from a boundary area, the non-condensable gas enters a vacuum pump system X3 and is discharged to the atmosphere, the solid-containing liquid phase sequentially enters a hydrocyclone X1 and a centrifugal separator X2 through a nitrate pump and then undergoes centrifugal solid-liquid separation, the solid phase is discharged from the boundary area through a belt conveyor, the liquid phase returns to a V-effect evaporation chamber V5, and the supernatant is sent to the boundary area from the upper part of the V-effect evaporation chamber V5 through a clear liquid pump to realize the recycling of useful substances in the acidic wastewater.
The mass introduced into the acid bath is recorded as WyThe concentration of sulfuric acid introduced into the acid bath is denoted XyThe mass of the initial evaporation feed liquid is recorded as WlThe quality of the last-effect evaporation feed liquid is recorded as WmThe concentration of sulfuric acid in the initial evaporation feed is recorded as XlPowder, powderThe concentration of sulfuric acid in the effect evaporation feed liquid is marked as XmThe salt-containing acidic waste water from outside and the acid bath required by calculation according to the following formula enter an IV effect evaporation chamber V4 through a single pipeline, and are mixed with the acidic waste water in the evaporation chamber for downstream evaporation:
the 170 ℃ superheated fresh steam outside the boundary region is reduced to 130 ℃ saturated steam through the temperature and pressure reducer 3, the 130 ℃ saturated steam enters the shell pass of the I-effect heater H1, and the salt-containing waste sulfuric acid in the pipe is heated.
The scaling condition of the outer walls of the falling-film evaporator and the forced circulation heater and the heat exchange efficiency of an evaporation system are regularly observed, when the heat exchange efficiency is obviously reduced, the evaporation is stopped, alkali liquor with certain concentration is used for cleaning the tube side and the shell side of the falling-film evaporator and the forced circulation heater according to an alkali washing pipeline system, and the heat exchange efficiency of the heat exchanger can be effectively recovered in the process.
The aspects, embodiments, features and examples of the present invention should be considered as illustrative in all respects and not intended to be limiting of the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.
The use of headings and chapters in this disclosure is not meant to limit the disclosure; each section may apply to any aspect, embodiment, or feature of the disclosure.
Throughout this specification, where a composition is described as having, containing, or comprising specific components or where a process is described as having, containing, or comprising specific process steps, it is contemplated that the composition of the present teachings also consist essentially of, or consist of, the recited components, and the process of the present teachings also consist essentially of, or consist of, the recited process steps.
Unless specifically stated otherwise, use of the terms "comprising", "including", "having" or "having" is generally to be understood as open-ended and not limiting.
It should be understood that the order of steps or the order in which particular actions are performed is not critical, so long as the teachings of the invention remain operable. Further, two or more steps or actions may be performed simultaneously.
In addition, the inventors of the present invention have also made experiments with other materials, process operations, and process conditions described in the present specification with reference to the above examples, and have obtained preferable results.
While the invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.
Claims (10)
1. A recycling process of waste sulfuric acid containing salt is characterized by comprising the following steps: the method comprises the steps of carrying out countercurrent stage-by-stage effect preheating on the feed liquid containing the salt waste sulfuric acid, then carrying out cocurrent evaporation, introducing into an acid bath to be used as an evaporation crystallization carrier, and finally extracting the sulfate by a last effect or last double effect one-step method.
2. The recycling process of waste sulfuric acid containing salt according to claim 1, characterized in that: the mass of the introduction into the acid bath was recorded as WyThe concentration of sulfuric acid introduced into the acid bath is denoted XyThe mass of the initial evaporation feed liquid is recorded as WlThe quality of the last-effect evaporation feed liquid is recorded as WmThe concentration of sulfuric acid in the initial evaporation feed is recorded as XlLast effect evaporation materialThe concentration of sulfuric acid in the liquor is recorded as XmThen, the following conditions are satisfied:
3. the recycling process of waste sulfuric acid containing salt according to claim 2, characterized in that: the concentration of sulfuric acid in the final-effect evaporation feed liquid is more than or equal to 7.5 percent and less than or equal to Xm≤25％。
4. The recycling process of waste sulfuric acid containing salt according to any one of claims 1 to 3, characterized in that: the concentration of sodium sulfate in the salt-containing waste sulfuric acid solution is 20-150 g/L, and the concentration of sulfuric acid is 5-30 g/L.
5. A recycling device of waste sulfuric acid containing salt, which is mainly applied to the recycling process of waste sulfuric acid containing salt in any one of claims 1 to 4, and is characterized by comprising:
the multi-effect inter-effect preheating system is at least used for carrying out countercurrent stage-by-stage inter-effect preheating on the feed liquid containing the salt waste sulfuric acid;
the multi-effect evaporation system is at least used for carrying out cocurrent evaporation on the preheated feed liquid;
an acid bath feed system for at least introducing an acid bath;
a sulfate extraction system for at least extracting sulfate from a last-effect evaporation or a last-double-effect evaporation.
6. The recycling device of waste sulfuric acid containing salt according to claim 5, characterized in that: the multi-effect evaporation system comprises an n-effect evaporation crystallization device, the multi-effect inter-preheating system comprises an n-1-effect inter-preheater, the position of the evaporation crystallization device introduced into the acid bath in the acid bath feeding system is 1-n-1 effect, wherein n is any integer between 5 and 7.
7. The recycling device of waste sulfuric acid containing salt according to claim 6, characterized in that: the n-effect evaporative crystallization device comprises n inter-effect evaporation chambers which are arranged in parallel and a falling film evaporator or a forced circulation heater which is respectively communicated with the inter-effect evaporation chambers, wherein the inter-effect evaporation chambers of the first 2-6 effects are communicated with the falling film evaporator, and the inter-effect evaporation chambers of the last 1-4 effects are communicated with the forced circulation heater.
8. The recycling device of waste sulfuric acid containing salt according to claim 7, characterized in that: the acid bath feeding system comprises a feeding tank and an acid pipeline which are arranged behind the n-1-effect inter-preheater, the acid pipeline sequentially passes through the n-1-effect inter-preheater in a reverse direction through the feeding tank and then sequentially passes through the n-effect evaporative crystallization device in a forward direction; and/or the sulfate extraction system comprises a hydrocyclone and a centrifugal separator which are sequentially communicated with the final-effect evaporation chamber through a solid-liquid phase pipeline.
9. The recycling device of waste sulfuric acid containing salt according to claim 8, characterized in that: the recycling device of the waste sulfuric acid containing salt further comprises each effect condensed water flash tank which is correspondingly arranged with each effect evaporation crystallization device, and/or the last effect evaporation chamber is sequentially communicated with a secondary steam condenser and a vacuum device through a gas pipeline.
10. The recycling device of waste sulfuric acid containing salt according to any one of claims 5 to 9, characterized in that: the recycling device for the waste sulfuric acid containing salt also comprises an alkaline washing system which is at least used for cleaning the multi-effect inter-effect preheating system and the multi-effect evaporation system.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113403710A (en) * | 2021-07-22 | 2021-09-17 | 上海神农节能环保科技股份有限公司 | Treatment method and device suitable for removing sodium sulfate from viscose fiber acid bath |
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| CN106517626A (en) * | 2016-11-30 | 2017-03-22 | 江苏迈安德节能蒸发设备有限公司 | Sodium sulfate wastewater treatment process |
| CN107008027A (en) * | 2017-05-22 | 2017-08-04 | 许达人 | A kind of multiple-effect evaporation concentration technology, evaporative crystallization technique and the device of sulfur acid and its salting liquid |
| CN110330039A (en) * | 2019-07-16 | 2019-10-15 | 南通三圣石墨设备科技股份有限公司 | The production system and production technology of anhydrous sodium sulphate are continuously produced in a kind of acid bath |
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| CN106517626A (en) * | 2016-11-30 | 2017-03-22 | 江苏迈安德节能蒸发设备有限公司 | Sodium sulfate wastewater treatment process |
| CN107008027A (en) * | 2017-05-22 | 2017-08-04 | 许达人 | A kind of multiple-effect evaporation concentration technology, evaporative crystallization technique and the device of sulfur acid and its salting liquid |
| CN110330039A (en) * | 2019-07-16 | 2019-10-15 | 南通三圣石墨设备科技股份有限公司 | The production system and production technology of anhydrous sodium sulphate are continuously produced in a kind of acid bath |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113403710A (en) * | 2021-07-22 | 2021-09-17 | 上海神农节能环保科技股份有限公司 | Treatment method and device suitable for removing sodium sulfate from viscose fiber acid bath |
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