阅读说明：本技术 一种利用醋酸废水制备醋酸钠的方法及其装置 (Method and device for preparing sodium acetate by using acetic acid wastewater ) 是由 蒋其明 钱春龙 李爱红 于 2020-06-02 设计创作，主要内容包括：本发明公开了一种利用醋酸废水制备醋酸钠的方法及其装置,其中利用醋酸废水制备醋酸钠的方法包括以下步骤：将醋酸废水进行过滤；将过滤后的醋酸废水和烧碱进行中和反应；将中和反应后的产物进行过滤,得到滤液；将滤液进行蒸发浓缩,得到浓缩母液；将浓缩母液进行结晶处理,通过离心机将晶体和母液进行分离,得到醋酸钠晶体,本发明中的醋酸钠制备方法的原料使用的是醋酸废水,产品原料成本低,工艺流程简单,所以产品成本低,且减少了醋酸废水的排放,具有良好的经济价值和社会价值；本发明中的醋酸钠制备装置中综合利用各工序中放热和吸热过程,对水进行预加热和预冷却,有利于能源的综合利用,节省制备能源。(The invention discloses a method and a device for preparing sodium acetate by using acetic acid wastewater, wherein the method for preparing sodium acetate by using acetic acid wastewater comprises the following steps: filtering acetic acid wastewater; neutralizing the filtered acetic acid wastewater with caustic soda; filtering the product after the neutralization reaction to obtain a filtrate; evaporating and concentrating the filtrate to obtain concentrated mother liquor; the concentrated mother liquor is crystallized, and the crystals and the mother liquor are separated by a centrifugal machine to obtain sodium acetate crystals; the sodium acetate preparation device comprehensively utilizes the heat release and heat absorption processes in all the working procedures to preheat and pre-cool water, thereby being beneficial to the comprehensive utilization of energy and saving the preparation energy.)

1. A method for preparing sodium acetate by using acetic acid wastewater is characterized by comprising the following steps:

s1: filtering the acetic acid wastewater to remove impurities in the acetic acid wastewater;

s2: neutralizing the filtered acetic acid wastewater with caustic soda, controlling the temperature of the neutralization reaction to be 55-65 ℃, dropwise adding the caustic soda into the acetic acid wastewater, and keeping the mass of acetic acid in the acetic acid wastewater to be 4-8% more than that of the caustic soda after the dropwise adding of the caustic soda is finished;

s3: filtering the product after the neutralization reaction, and removing filter residues to obtain filtrate;

s4: evaporating and concentrating the filtrate to obtain concentrated mother liquor with concentration of 1250kg/m³；

S5: crystallizing the concentrated mother liquor;

s6: separating the crystals from the mother liquor by a centrifugal machine, collecting and packaging the crystals, and recrystallizing the mother liquor again;

in step S4, the evaporation and concentration are performed by heating the neutralization reaction cooling water, the self-evaporated liquefied water, and the crystallization cooling water using steam.

2. The device for preparing sodium acetate by using acetic acid wastewater as claimed in claim 1, which comprises a neutralization reaction kettle (1), a filter (2), a concentration reaction kettle (3), a crystallization tank (4) and a separator (5) which are sequentially communicated, wherein the communication pipelines among the above components are respectively provided with a delivery pump, and the liquid discharge port of the separator (5) is communicated with the feed port of the crystallization tank (4) through a return pipe.

3. The apparatus for preparing sodium acetate from acetic acid wastewater according to claim 2, wherein the neutralization reaction kettle (1) comprises a shell (11), a coiled pipe (13) and an anchor stirring rod (12) which are fixed on the inner wall of the shell (11) are arranged inside the shell (11), an inclined plate (121) is arranged above the anchor part of the stirring rod (12), a water inlet (131) and a water outlet (132) of the coiled pipe (13) extend to the outside of the shell (11), an acetic acid wastewater inlet (111), a caustic soda inlet (112) and a waste gas extraction port (114) are arranged on the upper part of the shell (11), and a discharge port (113) is arranged at the bottom of the shell (11); a temperature measuring instrument (14) is arranged on the shell (11).

4. The apparatus for preparing sodium acetate by using acetic acid wastewater according to claim 3, wherein the structures of the concentration reaction kettle (3) and the crystallization tank (4) are the same as the structure of the neutralization reaction kettle (1);

a steam generator (7) is arranged between the coiled pipes inside the neutralization reaction kettle (1) and the concentration reaction kettle (3), and a cooling pool (6) and a cooling structure (8) are arranged between the concentration reaction kettle (3) and the crystallizing tank (4).

5. The apparatus for preparing sodium acetate by using acetic acid wastewater according to claim 4, wherein the cooling structure (8) comprises a freezing chamber (81), a water inlet pipe (82), a frozen sand discharging pipe (83), a freezing box (84) and a crushing box (85) are arranged inside the freezing chamber (81), the upper part of the freezing chamber (81) is provided with the reversible freezing box (84), the water inlet pipe (82) is arranged above the freezing box (84), the crushing box (85) is arranged below the freezing box (84), and the bottom of the crushing box (85) is provided with the frozen sand discharging pipe (83) inclined on the net.

6. The apparatus for preparing sodium acetate by using acetic acid wastewater as claimed in claim 5, wherein the freezing box (84) comprises a box body (841) and a pressure plate (845) below the box body (841), and a spring (846) is arranged between the pressure plate (845) and the box body (841);

box body (841) inside setting up baffle (842) and dividing into a plurality of freezing units (844) with box body (841), communicate each other between freezing unit (844), every the bottom of freezing unit (844) sets up pellosil (843), clamp plate (845) are close to box body (841) one side and set up lug (847) that correspond with pellosil (843).

7. The apparatus for preparing sodium acetate from acetic acid wastewater as claimed in claim 6, wherein the case (841) is rotatably connected to the freezing chamber (81), a push plate (87) and a cylinder (88) for pushing the push plate (87) downward are provided above the freezing chamber (81), and the push plate (845) corresponds to the push plate (87) after the case (841) is turned over by 180 °.

8. The apparatus for preparing sodium acetate from acetic acid wastewater according to claim 7, wherein the cooling structure (8) further comprises a mixing chamber (89), a fan (810), a dispersing box (811), a guide pipe (812) and a coolant discharging pipe (813) are arranged in the mixing chamber (89), an air outlet of the fan (810) is fixedly connected with an upper end of the dispersing box (811) and communicated with the inside of the dispersing box (811), one end of the guide pipe (812) is connected with an air outlet of the fan (810), the other end of the guide pipe (812) is fixedly connected with a lower end of the dispersing box (811) and communicated with the inside of the dispersing box (811), the dispersing box (811) is communicated with the crushing box (85) through an ice sand discharging pipe (83), and one end of the dispersing box (811) is provided with the coolant discharging pipe (813).

9. The apparatus for preparing sodium acetate from acetic acid wastewater according to claim 8, wherein the inner wall of the dispersion box (811) is provided with a spiral convex plate (814).

10. The apparatus for preparing sodium acetate from acetic acid wastewater according to claim 8, wherein the cooling method of the cooling structure (8) comprises the following steps:

a1: respectively freezing the liquefied water from the coiled pipe of the concentration reaction kettle by using a refrigerating piece;

a2: crushing ice blocks formed by freezing to form ice slush;

a3: and mixing the air of the ice sand box to form mixed air with ice sand.

Technical Field

The invention relates to the technical field of sodium acetate production, in particular to a method and a device for preparing sodium acetate by using acetic acid wastewater.

Background

In the production of glacial acetic acid, a certain amount of acetic acid wastewater can be generated in the acetic acid refining link due to rectification and concentration. The substances contained in the acetic acid wastewater mainly comprise acetic acid, formic acid, acetaldehyde, miscellaneous lipid and other substances, generally, the total acid content in the acetic acid wastewater is about 33 percent (wherein the acetic acid content is about 30 percent, and the formic acid content is about 3 percent), and the content of the acetaldehyde, miscellaneous lipid and other organic impurities is less than 66 percent. In most glacial acetic acid production devices, acetic acid wastewater is directly discharged as one of three industrial wastes. Thereby causing the reduction of the pH value of the wastewater in the main drainage ditch and causing environmental pollution.

Sodium acetate is industrially useful for measuring lead, zinc, aluminum, iron, cobalt, antimony, nickel, tin. The compound is used as an esterification agent for organic synthesis, and is used in the aspects of photographic medicines, printing and dyeing mordants, buffering agents, chemical reagents, meat preservation, pigments, tanning and the like.

The sodium acetate laboratory is usually prepared by the following method: adding proper amount of sodium carbonate or caustic soda into 15-40% dilute acetic acid to produce neutralization, and evaporating the reacted solution to concentrate and crystallize sodium acetate. In industrial production, sodium acetate is also generally produced by using this principle, but the raw material of acetic acid needs to be purchased.

Disclosure of Invention

The invention provides a method and a device for preparing sodium acetate by using acetic acid wastewater, which aim to save acetic acid raw materials.

In order to achieve the purpose, the invention adopts the following technical scheme:

the preparation method of sodium acetate is characterized by comprising the following steps:

s1: filtering the acetic acid wastewater to remove impurities in the acetic acid wastewater;

s2: neutralizing the filtered acetic acid wastewater with caustic soda, wherein the temperature of the neutralization reaction is controlled to be between 55 and 65 ℃;

s3: when the pH value of the reaction liquid of the neutralization reaction is 7.5-8, filtering the product after the neutralization reaction, and removing filter residues to obtain a filtrate;

s4: evaporating and concentrating the filtrate to obtain concentrated mother liquor;

s5: crystallizing the concentrated mother liquor at 40-50 deg.c;

s6: separating the crystals and the mother liquor by a centrifuge, collecting and packaging the crystals, and recrystallizing the mother liquor again.

In the invention, the flaky caustic soda and the acetic acid wastewater are selected for neutralization reaction, and the concentration of sodium acetate in the reaction solution can be improved because of little moisture brought by the caustic soda, thereby greatly reducing the steam consumption of evaporation concentration in the subsequent process.

In step S2, the temperature of the neutralization reaction was 60 ℃. The reaction of acetic acid and caustic soda is acid-base neutralization reaction, and a large amount of heat is released, so that the temperature of reaction liquid is increased, the reaction is more violent when the temperature is high, and simultaneously, volatile materials in acetic acid wastewater begin to volatilize due to the temperature increase, and certain irritant gas is generated. The reaction temperature is controlled below 60 ℃, so that the generation of irritant gas can be effectively avoided, and a small amount of irritant gas generated is pumped to the waste gas absorption tower by using the vacuum pump to be absorbed.

The miscellaneous fat in the acetic acid wastewater also has the following side reaction in the presence of caustic soda: RCOOR '+ NaOH → RCOONa + R' OH, preferably, in the neutralization reaction in the step S2, caustic soda is slowly dripped into acetic acid wastewater, so that the caustic soda with relatively high cost can be fully reacted, and the caustic soda generated by side reaction due to excessive caustic soda can be avoided; after the dropwise addition is finished, the mass of acetic acid in the acetic acid wastewater is kept 4% -8% more than that of caustic soda, preferably, the mass of acetic acid in the acetic acid wastewater is 5% excessive, and the occurrence of side reactions is reduced.

The concentration of the concentrated mother liquor is low, although the crystallized crystal particles are large and the product purity is high, the crystallization speed is low, the yield is low and the production efficiency is low; and the concentration of the concentrated mother liquor is too high, and impurities can be separated out along with crystallization when the crystallized sodium acetate is separated out, so that the product quality is influenced. Preferably, in the step S4, the density of the concentrated mother liquor is 1250 kg/m.

In the step S4, the steam used for evaporation and concentration is generated by heating the neutralization reaction cooling water, the self-steam liquefied water, and the crystallization cooling water, so that comprehensive utilization of heat can be achieved.

The invention also discloses a preparation device for preparing the sodium acetate, which comprises a cloth bag filter, a neutralization reaction kettle, a filter, a concentration reaction kettle, a crystallization tank and a separator which are sequentially communicated, wherein the communication pipelines among the components are respectively provided with a delivery pump, namely acetic acid wastewater is filtered by the cloth bag filter and then enters the neutralization reaction kettle, caustic soda is dripped into the neutralization reaction kettle for neutralization reaction, reaction liquid after reaction enters the concentration reaction kettle after impurities are filtered by the filter, concentrated mother liquor after concentration enters the crystallization tank for crystallization, mixed liquor after crystallization enters the separator, the separator separates crystals from the mother liquor, a liquid discharge port of the pump is communicated with a feed port of the crystallization tank through a return pipe, and the separated mother liquor can be crystallized again.

Preferably, the neutralization reaction kettle comprises a shell, wherein a coiled pipe and an anchor stirring rod which are fixed on the inner wall of the shell are arranged inside the shell, the coiled pipe is used for introducing cooling water and cooling the neutralization reaction, and a water inlet and a water outlet of the coiled pipe extend to the outside of the shell. The stirring rod is used for stirring, the inclined plate is arranged above the anchor part of the stirring rod and used for promoting the upwelling of the reaction liquid and facilitating the uniform reaction of the reaction liquid.

The upper part of the shell is provided with an acetic acid wastewater feeding hole, a caustic soda feeding hole and a waste gas extraction hole, and the bottom of the shell is provided with a discharge hole; the shell is provided with a temperature measuring instrument for measuring the temperature in the reaction kettle.

Further, the structures of the concentration reaction kettle and the crystallization tank are the same as those of the neutralization reaction kettle. The coil pipes are also arranged in the concentration reaction kettle and the crystallization tank, and the coil pipes in the concentration reaction kettle are used for introducing high-temperature steam and heating the concentrated reaction solution; the coil pipe in the crystallizing tank is used for introducing crystallization cooling gas for concentrating the crystallization of the mother liquor.

A steam generator is arranged between the coiled pipes in the neutralization reaction kettle and the concentration reaction kettle and is used for heating cooling water from the coiled pipes in the neutralization reaction kettle to form steam; set up cooling tank and cooling structure between concentrated reation kettle and the crystallizer, the cooling tank is used for the liquefied water that natural cooling goes out from concentrated reation kettle coiled pipe, reduces the temperature of liquefied water, and the liquefied water in the cooling tank is followed in the cooling structure cooling, makes it form crystallization cooling gas, and the crystallization cooling gas in the cooling structure can be used to the cooling of crystallization cooling and neutralization reaction. Wherein the liquefied water from the coiled pipe of the concentration reaction kettle and the cooling water from the crystallization tank can enter a steam generator through a pipeline for evaporation concentration.

The cooling water from the coiled pipe of the neutralization reaction kettle and the crystallization tank is preheated due to heat absorption, the liquefied water from the coiled pipe of the concentration reaction kettle has the temperature, and the three parts are used as the liquid to be heated of the steam generator, so that the heating burden of the steam generator is reduced. The device comprehensively utilizes the heat release and heat absorption processes in each procedure to preheat and pre-cool water, thereby being beneficial to the comprehensive utilization of energy and saving the energy.

The cooling method of the cooling structure comprises the following steps:

a1: respectively freezing the liquefied water from the coiled pipe of the concentration reaction kettle by using a refrigerating piece;

a2: crushing ice blocks formed by freezing to form ice slush;

a3: and mixing the air of the ice sand box to form mixed air with ice sand.

Specifically, the cooling structure includes a cooling chamber, a freezing chamber, and a mixing chamber. The cooling chamber is used for cooling the liquefied water from the coiled pipe of the concentration reaction kettle to 5-10 ℃, the water in the cooling chamber is introduced into the freezing chamber and is frozen and crushed to form the ice sand, and the ice sand enters the air in the mixing chamber box to form mixed air with the ice sand, namely crystallized cooling gas.

It is specific, the freezer is inside to be set up inlet tube, the husky discharging pipe of ice, freezes box, crushing box, and the freezer outside sets up freezing subassembly, makes the temperature of freezer below 0 ℃, the upper portion of freezer sets up the box that freezes that can overturn, the top of freezing the box sets up the inlet tube, the below of freezing the box sets up crushing box, smashes the inside crushing blade that sets up of box, the bottom of smashing the box sets up the husky discharging pipe of online slope.

The water that the inlet tube came in gets into freezing the box and freezes, and the ice-cube after freezing falls into crushing box through freezing 180 upsets of box, smashes the ice-cube of box inside crushing blade, forms the ice-slush, and the ice-slush can go out from the ice-slush discharging pipe and get into the mixing chamber.

The freezing box comprises a box body and a pressing plate below the box body, wherein a spring is arranged between the pressing plate and the box body; the box body is internally provided with a partition plate which divides the box body into a plurality of freezing units, the upper end of the partition plate is lower than the upper end of the box body, the freezing units are communicated with one another, ice water can conveniently enter each freezing unit, each freezing unit is provided with a flexible silica gel film at the bottom, the pressing plate is provided with a convex block corresponding to the silica gel film at one side close to the box body, the pressing plate is pressed in the direction close to the box body, and the convex block can abut against the silica gel film to push the ice blocks of the box body, so.

Further, box body and freezer swivelling joint, the top of freezer sets up the push pedal and is used for down promoting the cylinder of push pedal, and after the box body carried out 180 upsets, the clamp plate was corresponding with the push pedal, and the cylinder promoted the push pedal and presses the clamp plate, makes the lug push away the ice-cube to crushing box in, smashes the blade and smashes the ice-cube, forms the ice-slush.

Furthermore, the inside fan, dispersion box, guide tube, cooling thing discharging pipe that sets up of mixing chamber, the mixing chamber is located freezing room one side, and the inside temperature of mixing chamber is crossed the refrigeration subassembly and is kept below 0 ℃ all, is used for cooling air and keeps the sand ice not to melt. The air outlet fixed connection of fan disperses the upper end of box and communicates with the inside of dispersion box, the air outlet of fan is connected to the one end of guiding tube, and the other end of guiding tube is connected the lower extreme of fixed connection dispersion box and communicates with the inside of dispersion box, the dispersion box passes through the ice sand discharging pipe and smashes the box intercommunication, dispersion box one end sets up the cooling thing discharging pipe. The fan blows air into the dispersing box, the pump body is arranged above the ice sand discharging pipe and guides the ice sand in the crushing box into the dispersing box, the air and the ice sand in the dispersing box are mixed to form mixed air with the ice sand, and the guide pipe enables the upper end and the lower end of the dispersing box to enter the air so as to accelerate the dispersion of the ice sand in the air. The cooling medium outlet pipe guides the mixed air with the ice slush into the coil of the crystallization tank.

Preferably, the inner wall of the dispersing box is provided with a spiral convex plate to accelerate the mixing of the sand ice and the air in the dispersing box.

1. The invention has the beneficial effects that: the sodium acetate is prepared by using the acetic acid wastewater, the raw material is low in cost of raw materials, the process flow is simple, so that the product cost is low, the discharge of the acetic acid wastewater is reduced, and the sodium acetate has good economic value and social value.

2. The heat release and heat absorption processes in all the procedures are comprehensively utilized in the sodium acetate preparation system, water is preheated and precooled, comprehensive utilization of energy is facilitated, and energy is saved.

3. The cooling structure in the sodium acetate preparation system can cool the neutralization reaction and the crystallization process through the ice-water mixture, ice sand generated in the cooling process absorbs heat to form water, the cooling effect is strong, the cooling efficiency can be accelerated when needed, and the cooling structure has great superiority in the aspect of accurately controlling the reaction temperature.

4. The freezing chamber of the cooling structure in the sodium acetate preparation system can realize freezing and automatic crushing of ice blocks and automatic mixing of air and sand ice, the cooling structure can realize continuous cooling, and the cooling efficiency is high.

Drawings

FIG. 1 is a process diagram of the method for preparing sodium acetate from acetic acid wastewater;

FIG. 2 is a flow chart of the method for preparing sodium acetate by using acetic acid wastewater;

FIG. 3 is a schematic structural diagram of the apparatus for preparing sodium acetate from acetic acid wastewater;

FIG. 4 is a schematic structural diagram of a neutralization reaction kettle of the sodium acetate preparation device;

FIG. 5 is a flow chart of the cooling method of the cooling structure of the apparatus for preparing sodium acetate;

FIG. 6 is a schematic structural diagram of the cooling structure of the apparatus for preparing sodium acetate;

FIG. 7 is a schematic diagram of the structure of the freezing chamber of the apparatus for preparing sodium acetate;

FIG. 8 is a schematic view of the structure of the dispersing box part of the apparatus for preparing sodium acetate.

In the figure: 1. a neutralization reaction kettle; 2. a filter; 3. concentrating the reaction kettle; 4. a crystallization tank; 5. a separator; 6. a cooling pool; 7. a steam generator; 8. a cooling structure; 11. a housing; 12. a stirring rod; 13. a serpentine tube; 14. a temperature measuring instrument; 121. a sloping plate; 131. a water inlet; 132. a water outlet; 111. an acetic acid wastewater inlet; 112. a caustic soda feed port; 113. a discharge port; 114. an exhaust gas extraction port; 81. a freezing chamber; 82. a water inlet pipe; 83. a smoothie discharging pipe; 84. a freezing box; 85. a crushing box; 86. a crushing blade; 87. pushing the plate; 88. a cylinder; 89. a mixing chamber; 810. a fan; 811. a dispersion box; 812. a guide tube; 813. a cooling material discharge pipe; 814. a spiral convex plate; 841. a box body; 842. a partition plate; 843. silica gel; 844. a freezing unit; 845. pressing a plate; 846. a spring; 847. and (4) a bump.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.