阅读说明：本技术 一种醋酸钠制备方法及其节能制备系统 (Sodium acetate preparation method and energy-saving preparation system thereof ) 是由 蒋其明 钱春龙 李爱红 于 2020-05-12 设计创作，主要内容包括：本发明公开了一种醋酸钠制备方法及其节能制备系统,醋酸钠制备方法包括以下步骤：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系统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 sodium acetate preparation method and an energy-saving preparation system thereof, wherein the sodium acetate preparation method 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 system 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. 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: 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;

s5: crystallizing the concentrated mother liquor;

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

2. The method for preparing sodium acetate according to claim 1, characterized in that in the neutralization reaction of step S2, caustic soda is added dropwise into the acetic acid wastewater, and after the addition of caustic soda is completed, the mass of acetic acid in the acetic acid wastewater is kept 4% -8% more than that of caustic soda.

3. The sodium acetate preparation method and energy-saving preparation system thereof according to claim 2, wherein in the step S4, the density of the concentrated mother liquor is 1250kg/m³。

4. The energy-saving preparation system for preparing the sodium acetate according to claim 1 or 3, 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 components are provided with delivery pumps, and the liquid discharge port of the separator (5) is communicated with the feed port of the crystallization tank (4) through a return pipe.

5. The energy-saving sodium acetate preparation system according to claim 4, wherein the neutralization reaction kettle (1) comprises a shell (11), a coiled pipe (13) and an anchor type 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 an exhaust 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).

6. The energy-saving sodium acetate preparation system according to claim 5, 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 in the neutralization reaction kettle (1) and the concentration reaction kettle (3), and a cooling pool (6) and a cooling device (8) are arranged between the concentration reaction kettle (3) and the crystallizing tank (4).

7. The energy-saving sodium acetate preparation system according to claim 6, wherein the cooling device (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), 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.

8. The energy-saving sodium acetate preparation system of claim 7, 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).

9. The energy-saving sodium acetate preparation system according to claim 8, wherein the box (841) is rotatably connected with the freezing chamber (81), a push plate (87) and a cylinder (88) for pushing the push plate (87) downwards are arranged above the freezing chamber (81), and when the box (841) is turned over by 180 degrees, the press plate (845) corresponds to the push plate (87).

10. The energy-saving sodium acetate preparation system according to claim 9, wherein the cooling method of the cooling device (8) comprises the following steps:

a1: respectively freezing and cooling 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: the ice slush was mixed with the cooling water in a1 to form crystallized cooling water.

Technical Field

The invention relates to the technical field of sodium acetate production, in particular to a sodium acetate preparation method and an energy-saving preparation system thereof.

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 sodium acetate preparation method and an energy-saving preparation system thereof, which utilize acetic acid wastewater to prepare industrial sodium acetate so as to achieve the purpose of saving 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.

Preferably, in step S2, the temperature of the neutralization reaction is 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 1250kg/m³。

The invention also discloses an energy-saving preparation system 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 water 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; a cooling pool and a cooling device are arranged between the concentration reaction kettle and the crystallizing tank, the cooling pool is used for naturally cooling the liquefied water coming out of the coiled pipe of the concentration reaction kettle, the temperature of the liquefied water is reduced, the cooling device cools the liquefied water in the cooling pool to form crystallization cooling water, and the cooling crystal water in the cooling device can be used for cooling crystallization 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 system 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 device comprises the following steps:

a1: respectively freezing and cooling 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: the ice slush was mixed with the cooling water in a1 to form crystallized cooling water.

Specifically, the cooling device comprises 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 ℃, part of 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 and the water in the cooling chamber enter the mixing chamber to form the crystallization cooling water.

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.

The invention has the beneficial effects that:

1. 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 device in the sodium acetate preparation system can cool the neutralization reaction and the crystallization process through the ice-water mixture, ice 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 device has great superiority particularly in accurately controlling the reaction temperature.

4. The freezing chamber of the cooling device in the sodium acetate preparation system can realize freezing and automatic crushing of ice cakes, the cooling device can realize continuous cooling, and the cooling efficiency is high.

Drawings

FIG. 1 is a flow chart of the preparation method of sodium acetate;

FIG. 2 is a schematic structural diagram of the sodium acetate energy-saving preparation system;

FIG. 3 is a schematic structural diagram of a neutralization reaction kettle of the energy-saving sodium acetate preparation system;

FIG. 4 is a flow chart of the cooling method of the cooling device of the sodium acetate energy-saving preparation system;

FIG. 5 is a schematic structural diagram of a cooling device of the sodium acetate energy-saving preparation system;

FIG. 6 is a schematic structural diagram of a freezing box of the energy-saving sodium acetate preparation system;

fig. 7 is a schematic structural diagram of a freezing chamber of the energy-saving sodium acetate preparation system.

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 device; 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; 841. a box body; 842. a partition plate; 843. a silicone membrane; 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.