阅读说明：本技术 一种二次碳化法制备大颗粒小苏打的方法及所得的小苏打 (Method for preparing large-particle baking soda by secondary carbonization method and baking soda obtained by method ) 是由 李佳佳 张元德 于 2020-05-14 设计创作，主要内容包括：本发明提出了一种二次碳化法制备大颗粒小苏打的方法及所得的小苏打。本发明包括以下步骤：1)取纯碱溶液,净化；2)溶液进入预碳化塔的上部,与二氧化碳气体发生预碳化反应；3)自预碳化塔的底部放出预碳化后的溶液,降温；4)分多股进入碳化塔的中部和上部,二氧化碳分多股进入碳化塔的中部和下部,碳化反应,生成小苏打晶浆；5)自碳化塔的顶部排出的二氧化碳尾气,压缩,进入预碳化塔的下部；6)小苏打晶浆自碳化塔的底部出料,分离,干燥,得小苏打。本发明经过预碳化、降温和碳化并在碳化塔中采用多股进料和多股进气的方式得到了大颗粒小苏打,并提高了小苏打的产量；预碳化塔吸收碳化塔的尾气,提高了二氧化碳的利用率,经济效益好。(The invention provides a method for preparing large-particle baking soda by a secondary carbonization method and the baking soda prepared by the method. The invention comprises the following steps: 1) taking a soda solution, and purifying; 2) the solution enters the upper part of the pre-carbonization tower and is subjected to pre-carbonization reaction with carbon dioxide gas; 3) discharging the solution after pre-carbonization from the bottom of the pre-carbonization tower, and cooling; 4) feeding the carbon dioxide into the middle part and the upper part of the carbonization tower in multiple strands, feeding the carbon dioxide into the middle part and the lower part of the carbonization tower in multiple strands, and carrying out carbonization reaction to generate sodium bicarbonate crystal slurry; 5) compressing carbon dioxide tail gas discharged from the top of the carbonization tower, and feeding the compressed carbon dioxide tail gas into the lower part of the pre-carbonization tower; 6) discharging the baking soda crystal slurry from the bottom of the carbonization tower, separating and drying to obtain baking soda. The large-particle baking soda is obtained by pre-carbonizing, cooling and carbonizing and adopting a mode of multi-strand feeding and multi-strand air inlet in a carbonizing tower, and the yield of the baking soda is improved; the pre-carbonization tower absorbs the tail gas of the carbonization tower, so that the utilization rate of carbon dioxide is improved, and the economic benefit is good.)

1. The method for preparing the large-particle baking soda by the secondary carbonization method is characterized by comprising the following steps:

1) taking the soda solution, purifying for later use;

2) the sodium carbonate solution obtained in the step 1) enters a pre-carbonization tower from the upper part of the pre-carbonization tower and is subjected to pre-carbonization reaction with carbon dioxide gas, and the flow rate of the carbon dioxide gas is 0.5-2m³Flow rate of the solution is 0.1-0.5m³The reaction temperature is 10-80 ℃, and a pre-carbonized solution is obtained;

3) discharging the solution after pre-carbonization from the bottom of the pre-carbonization tower, entering a storage tank cooled by a belt reel, and cooling to ensure that the temperature is 10-80 ℃;

4) the cooled solution obtained in the step 3) enters the carbonization tower from different positions of the middle part and the upper part of the carbonization tower in a plurality of strands, carbon dioxide enters the carbonization tower from the middle part and the lower part of the carbonization tower in a plurality of strands, and the carbonization reaction is carried out on the carbon dioxide gasThe flow velocity of (1-5 m)³The flow rate of the solution after temperature reduction is 0.1-0.5m³The reaction temperature is 10-100 ℃, and baking soda crystal slurry is generated;

5) compressing carbon dioxide tail gas discharged from the top of the carbonization tower, and entering the pre-carbonization tower from the lower part of the pre-carbonization tower to enable the carbon dioxide tail gas to have a pre-carbonization reaction with raw material sodium carbonate in the pre-carbonization tower;

6) discharging the baking soda crystal slurry obtained in the step 4) from the bottom of the carbonization tower, separating and drying to obtain baking soda.

2. The method for preparing large-particle baking soda by the secondary carbonization method according to claim 1, which is characterized in that:

in the step 3), the temperature of the cooled solution is 40-60 ℃.

3. The method for preparing large-particle baking soda by the secondary carbonization method according to claim 1, which is characterized in that:

in the step 4), the cooled solution enters the carbonization tower in 2-5 strands, and the carbon dioxide enters the carbonization tower in 2-5 strands.

4. The method for preparing large-particle baking soda by the secondary carbonization method according to claim 3, wherein the method comprises the following steps:

in the step 4), the cooled solution enters the carbonization tower in 3-4 strands, and the carbon dioxide enters the carbonization tower in 2-3 strands.

5. The method for preparing large-particle baking soda by the secondary carbonization method according to claim 1, which is characterized in that:

in the step 4), the reaction temperature of the carbonization reaction is 40-80 ℃.

6. The method for preparing large-particle baking soda by the secondary carbonization method according to claim 1, which is characterized in that:

in the step 5), the pressure of the compressed carbon dioxide tail gas is 1-3 bar.

7. The method for preparing large-particle baking soda by the secondary carbonization method according to claim 1, which is characterized in that:

in the step 1), the sodium carbonate solution further comprises sodium bicarbonate, wherein the mass concentration of the sodium carbonate is 300g/L, and the mass concentration of the sodium bicarbonate is 10-100 g/L.

8. The method for preparing large-particle baking soda by the secondary carbonization method according to claim 1, which is characterized in that:

in the step 1), an additive is added into the soda ash solution, wherein the additive is added in an amount of 10-100ppm, and the additive is sodium polystyrene sulfonate, calcium chloride, sodium hexametaphosphate, exogenous tartaric acid, calcium sulfate and calcium citrate.

9. The method for preparing large-particle baking soda by the secondary carbonization method according to any one of claims 1 to 8, wherein:

the pre-carbonization tower is a packed tower.

10. Baking soda is characterized in that:

the baking soda is prepared by the method for preparing large-grain baking soda according to the secondary carbonization method in claims 1-9, and the grain size of the baking soda is 200-330 μm.

Technical Field

The invention relates to the technical field of baking soda production methods, in particular to a method for preparing large-particle baking soda by a secondary carbonization method and the baking soda obtained by the same.

Background

Sodium bicarbonate, commonly known as baking soda, is an important basic chemical raw material and food additive, and is widely applied to almost all industry departments such as glass, feed, medicine and the like. According to incomplete statistics, the annual yield of the baking soda in China reaches 250 ten thousand tons. The preparation method of industrial sodium bicarbonate mainly comprises a double decomposition method, a synthesis method and a natural soda method, and in the preparation methods, the synthesis method mainly consumes sodium carbonate, and the product quality is stable and reliable, so that the method is a production technology of baking soda which is widely adopted in China. The process of synthesizing and producing the baking soda mainly comprises the steps of preparing a sodium carbonate solution, carbonating and then filtering and drying.

At present, the production method and crystallization kinetics of baking soda are studied in detail in domestic and foreign patents and literature. Chinese patent CN104402023A discloses a production method for improving the granularity of baking soda products by a carbonization method, wherein a part of crystal slurry obtained by carbonization reaction enters a thickener, and the other part of crystal slurry returns to a carbonization tower, so that large-particle baking soda products are prepared; however, in this method, the carbonized crystal slurry is returned to the carbonization tower, which reduces the production efficiency of the carbonization tower and affects the economic efficiency. Chinese patent CN107739038A discloses a semi-batch crystallization method of large-particle (granular) sodium bicarbonate, which uses sodium bicarbonate and sodium carbonate aqueous solution as raw materials, controls the supersaturation degree by a gas-liquid reaction through a method of adding seed crystals to obtain the large-particle sodium bicarbonate; however, in the production process of the baking soda, the reaction time is long, and the supersaturation degree is not easy to control. Chinese patent CN108996526A discloses a method for preparing large-particle heavy sodium bicarbonate, wherein the method comprises adding 0-500ppm of additive and adding sodium carbonate and/or a mixture of sodium carbonate and sodium bicarbonate into the mixture after carbonization reaction to obtain 250-300 μm heavy large-particle sodium bicarbonate; the method promotes crystallization through the same ion effect of sodium carbonate and sodium bicarbonate to improve yield, and sodium carbonate is introduced in the crystallization process to influence the quality of products. Breton et al developed a method of adding phosphate, carboxylate and carboxylic acid to trona to separate sodium carbonate and sodium bicarbonate, and the particle size of the product could be adjusted by changing the kind and concentration of the additive, and this method uses trona as the raw material, and the mass percentage of sodium bicarbonate in the product could only reach about 65%, and the product purity is low.

Disclosure of Invention

The invention aims to provide a method for preparing large-particle baking soda by a secondary carbonization method and the baking soda prepared by the method, and aims to solve the problems that the operation process is not easy to control, the reaction time is long and the quality of the obtained product is poor in the preparation method of the large-particle baking soda in the prior art.

In order to solve the technical problem, the technical scheme of the invention is realized as follows:

in one aspect, the invention relates to a method for preparing large-particle baking soda by a secondary carbonization method, which comprises the following steps: 1) taking the soda solution, purifying for later use; 2) the sodium carbonate solution obtained in the step 1) enters the pre-carbonization tower from the upper part of the pre-carbonization tower and is subjected to pre-carbonization reaction with carbon dioxide gas, and the flow rate of the carbon dioxide gas is 0.5-2m³Flow rate of the solution is 0.1-0.5m³The reaction temperature is 10-80 ℃, and a pre-carbonized solution is obtained; 3) discharging the solution after pre-carbonization from the bottom of the pre-carbonization tower, entering a storage tank cooled by a belt reel, and cooling to ensure that the temperature is 10-80 ℃; 4) the cooled solution obtained in the step 3) enters the carbonization tower from different positions of the middle part and the upper part of the multi-strand carbonization tower, carbon dioxide enters the carbonization tower from the middle part and the lower part of the multi-strand carbonization tower for carbonization reaction, and the flow velocity of carbon dioxide gas is 1-5m³The flow rate of the solution after temperature reduction is 0.1-0.5m³The reaction temperature is 10-100 ℃, and baking soda crystal slurry is generated; 5) compressing carbon dioxide tail gas discharged from the top of the carbonization tower, and entering the pre-carbonization tower from the lower part of the pre-carbonization tower to enable the carbon dioxide tail gas to have a pre-carbonization reaction with raw material sodium carbonate in the pre-carbonization tower; 6) discharging the baking soda crystal slurry obtained in the step 4) from the bottom of the carbonization tower, separating and drying to obtain baking soda.

The raw material liquid is subjected to two carbonization processes of pre-carbonization and carbonization, so that the carbonization is uniform and sufficient, the temperature reduction treatment is adopted between the pre-carbonization process and the carbonization process, the supersaturation degree of the reaction is effectively controlled, the storage tank with coil cooling is adopted for reducing the temperature, the carbonized crystal slurry does not need to return or be additionally provided with a crystallizer, the operation is simple, no special requirements on equipment are required, and the investment is low; the carbonization tower adopts a mode of multi-strand feeding and multi-strand air inlet, the temperature of carbonization reaction is accurately controlled, and baking soda particles with uniform particles are prepared, and the particle size of the baking soda particles is large; the discharging temperature of the baking soda can be reduced, and the yield of the baking soda is improved; the pre-carbonization tower absorbs the tail gas of the carbonization tower, so that the utilization rate of carbon dioxide is improved, and the economic benefit is good.

In a preferred embodiment, in the step 3), the temperature of the solution after temperature reduction is 40-60 ℃. According to the invention, after pre-carbonization, the pre-carbonized product is firstly cooled, and then carbonized, so that the cooled pre-carbonized product can be better stranded to carry out carbonization reaction with carbon dioxide gas, the reaction temperature is easy to control, the particle size of the baking soda is effectively controlled, and the baking soda particles are uniform. The temperature after cooling in the invention is 10-80 ℃, such as 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ and the like, preferably 40-60 ℃; partial crystal seeds can be generated by cooling before entering the carbonization tower, which is beneficial to preparing large-particle baking soda; can also avoid cooling in the carbonization tower, reduce the scab of the carbonization tower and prolong the alkali preparation period.

In a preferable embodiment, in the step 4), the cooled solution enters the carbonization tower in 2-5 strands, and the carbon dioxide enters the carbonization tower in 2-5 strands. In the carbonization tower, the cooled soda solution and carbon dioxide gas enter the carbonization tower in a plurality of strands, and the manner of combining the plurality of strands of feeding materials and the plurality of strands of inlet gases ensures that the soda solution is fully contacted with the carbon dioxide gas, thereby effectively controlling the temperature of the carbonization reaction, easily controlling the operation process and ensuring that the baking soda particles are uniform.

In a preferred embodiment, in the step 4), the cooled soda ash solution enters the carbonization tower in 3 to 4 shares, and the carbon dioxide enters the carbonization tower in 2 to 3 shares. Feeding the cooled sodium carbonate solution into different strands and feeding the fed sodium carbonate solution into different parts of the middle upper part of the carbonization tower; the carbon dioxide gas is fed in a plurality of strands and enters different parts of the middle lower part of the carbonization tower, and the liquid and the gas are fed in a plurality of strands in a crossed manner, so that the liquid and the gas are uniformly mixed, and the reaction is easier to control.

In a preferred embodiment, in the step 4), the reaction temperature of the carbonization reaction is 40 to 80 ℃. The temperature of the carbonization reaction in the invention can be adjusted within the range of 10-100 ℃, such as 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ and the like, the temperature of the carbonization reaction is preferably 40-80 ℃, the control of the temperature of the carbonization reaction can effectively control the formation of the baking soda, and the particle size of the baking soda is controlled to ensure that the particles are uniform.

In a preferred embodiment, the pressure of the compressed carbon dioxide tail gas in the step 5) is 1-3 bar. In the invention, the carbon dioxide tail gas discharged from the top of the carbonization tower is compressed and then enters the pre-carbonization tower again for reuse, thus greatly improving the utilization rate of the carbon dioxide, saving the energy consumption, improving the economic benefit and protecting the environment.

As a preferred embodiment, in the step 1), the soda ash solution further comprises sodium bicarbonate, the mass concentration of the sodium carbonate is 100-300g/L, and the mass concentration of the sodium bicarbonate is 10-100 g/L. The method takes a sodium carbonate solution as a raw material, and obtains a filtering mother liquor after a series of reactions, wherein the filtering mother liquor contains sodium carbonate and sodium bicarbonate, and can be recycled; filtering mother liquor and returning it to sodium carbonate raw material, when preparing new reaction raw material, the raw material is the mixed solution containing sodium carbonate and sodium hydrogen carbonate.

As a preferred embodiment, in the step 1), an additive is added into the soda solution, wherein the additive is added in an amount of 10-100ppm, and the additive is sodium polystyrene sulfonate, calcium chloride, sodium hexametaphosphate, exogenous tartaric acid, calcium sulfate and calcium citrate. The use of the additive can enlarge the particles of the baking soda product, so that the carbonization tower is not easy to scab, the soda production period is prolonged, and the economic benefit is increased. The soda solution is purified to remove insoluble impurities in the solution, so that the impurities in the final product are avoided, and the quality of the product is improved.

As a preferred embodiment, the precarbonizer is a packed column. The invention carries out the pre-carbonization reaction in the packed tower, the packed tower has simple structure and small pressure drop, only the carbonized tail gas needs to be compressed to lower pressure, and the operation cost is saved.

In another aspect, the baking soda of the invention is prepared by the method for preparing large-grain baking soda by the secondary carbonization method, wherein the grain size of the baking soda is 200-330 μm.

The baking soda obtained by the method is large-particle baking soda, the particle size is 197-; the method has the advantages that the yield of the baking soda is improved while the large-particle baking soda is obtained, the yield of the baking soda is 58-80%, the yield of the baking soda is high, and the yield of the baking soda is over 52Kg/h, so that the method is used for industrially producing the baking soda; the utilization rate of the carbon dioxide is 73.5-84.8%, and the utilization rate of the carbon dioxide is greatly improved.

Compared with the prior art, the invention has the beneficial effects that: the raw material liquid is subjected to two carbonization processes of pre-carbonization and carbonization, so that the carbonization is uniform and sufficient, the temperature reduction treatment is adopted between the pre-carbonization process and the carbonization process, the supersaturation degree of the reaction is effectively controlled, the storage tank with coil cooling is adopted for reducing the temperature, the carbonized crystal slurry does not need to return or be additionally provided with a crystallizer, the operation is simple, the special requirements on equipment are avoided, the investment is low, and the industrialization is easy; the carbonization tower adopts a mode of multi-strand feeding and multi-strand air inlet, the temperature and the supersaturation degree of carbonization reaction are accurately controlled, and the baking soda particles with uniform particles are prepared, and the particle size of the baking soda particles is large and is 197-ion 330 mu m; the discharging temperature of the baking soda can be reduced, the yield of the baking soda is improved, and the yield of the baking soda reaches 58-85%; due to the control of the additive and the carbonization reaction, the prepared baking soda has thick and uniform particles, reduces the scab of a carbonization tower, prolongs the alkali preparation period which can reach 45-51 h; the pre-carbonization tower absorbs the tail gas of the carbonization tower, so that the utilization rate of carbon dioxide is improved, the utilization rate of carbon dioxide is 73.5-84.8%, and the economic benefit is good.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings 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 of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a block flow diagram of a first embodiment of the present invention;

FIG. 2 is a process flow diagram of a second embodiment of the present invention;

FIG. 3 is a scanning electron microscope photograph of sodium bicarbonate obtained in example III of the present invention;

FIG. 4 is a scanning electron microscope photograph of sodium bicarbonate obtained in example five of the present invention;

FIG. 5 is a scanning electron microscope photograph of a sodium bicarbonate obtained according to a comparative example of the present invention;

in the figure: 1-an alkali liquor storage tank; 2-a pre-carbonization tower; 3-cooling the storage tank; 4-a carbonizer; 5-cooling tower; 6-thickener; 7-liquid return tank.

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. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention discloses a method for preparing large-particle baking soda by a secondary carbonization method, which comprises the following steps:

1) taking the soda solution, purifying for later use;

2) the sodium carbonate solution obtained in the step 1) enters the pre-carbonization tower from the upper part of the pre-carbonization tower and is subjected to pre-carbonization reaction with carbon dioxide gas, and the flow rate of the carbon dioxide gas is 0.5-2m³Flow rate of the solution is 0.1-0.5m³The reaction temperature is 10-80 ℃, and a pre-carbonized solution is obtained;

3) discharging the solution after pre-carbonization from the bottom of the pre-carbonization tower, entering a storage tank cooled by a belt reel, and cooling to ensure that the temperature is 10-80 ℃;

4) the cooled solution obtained in the step 3) enters the carbonization tower from different positions of the middle part and the upper part of the carbonization tower in multiple strands, carbon dioxide enters the carbonization tower from the middle part and the lower part of the carbonization tower in multiple strands for carbonization reaction, and the flow velocity of carbon dioxide gas is 1-5m³The flow rate of the solution after temperature reduction is 0.1-0.5m³The reaction temperature is 10-100 ℃, and baking soda crystal slurry is generated;

5) compressing carbon dioxide tail gas discharged from the top of the carbonization tower, and entering the pre-carbonization tower from the lower part of the pre-carbonization tower to enable the carbon dioxide tail gas to have a pre-carbonization reaction with raw material sodium carbonate in the pre-carbonization tower;

6) discharging the baking soda crystal slurry obtained in the step 4) from the bottom of the carbonization tower, separating and drying to obtain baking soda.

Preferably, in the step 3), the temperature of the solution after temperature reduction is 40-60 ℃.

Preferably, in the step 4), the cooled solution enters the carbonization tower by 2-5 strands, and the carbon dioxide enters the carbonization tower by 2-5 strands.

Further, in the step 4), the cooled solution enters the carbonization tower in 3-4 strands, and the carbon dioxide enters the carbonization tower in 2-3 strands.

Preferably, in the step 4), the reaction temperature of the carbonization reaction is 40-80 ℃.

Preferably, in the step 5), the pressure of the compressed carbon dioxide tail gas is 1-3 bar.

Preferably, in the step 1), the soda ash solution further comprises sodium bicarbonate, the mass concentration of the sodium carbonate is 300g/L, and the mass concentration of the sodium bicarbonate is 10-100 g/L.

Preferably, in the step 1), an additive is added into the soda solution, wherein the additive is added in an amount of 10-100ppm, and the additive is sodium polystyrene sulfonate, calcium chloride, sodium hexametaphosphate, exogenous tartaric acid, calcium sulfate and calcium citrate.

Preferably, the precarbonizer is a packed tower.

The baking soda is prepared by the method for preparing large-grain baking soda by the secondary carbonization method, and the grain size of the baking soda is 200-330 mu m.