阅读说明：本技术 一种碳酸氢钠固体湿法热解制备碳酸钠晶体的工艺 (Process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solid ) 是由 杨仁春 于 2021-07-28 设计创作，主要内容包括：本发明公开了一种碳酸氢钠固体湿法热解制备碳酸钠晶体的工艺,属于碳酸钠晶体制备技术领域。包括以下步骤：S1：向氯化钠-碳酸钠双饱和溶液中,一边搅拌加热,一边缓慢加入碳酸氢钠固体；S2：加完料后,继续搅拌加热升温至90～118??°C,当没有二氧化碳气体生成时,停止加热；S3：冷却,过滤,得到一水碳酸钠晶体。本发明碳酸氢钠分解率高,能耗低,而且产物为碳酸钠固体。(The invention discloses a process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids, and belongs to the technical field of sodium carbonate crystal preparation. The method comprises the following steps: s1: adding sodium bicarbonate solid slowly into sodium chloride-sodium carbonate double saturated solution while stirring and heating; s2: after the materials are added, continuously stirring and heating to raise the temperature to 90-118℃, and stopping heating when no carbon dioxide gas is generated; s3: cooling and filtering to obtain sodium carbonate monohydrate crystals. The sodium bicarbonate has high decomposition rate and low energy consumption, and the product is sodium carbonate solid.)

1. A process for preparing sodium carbonate crystals by the wet pyrolysis of sodium bicarbonate solids is characterized in that: the method comprises the following steps:

s1: adding sodium bicarbonate solid slowly into sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s2: after the materials are added, continuously stirring and heating to raise the temperature to 90-118 ℃, and stopping heating when no carbon dioxide gas is generated;

s3: cooling and filtering to obtain sodium carbonate monohydrate crystals.

2. The process for the preparation of sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids according to claim 1, characterized in that: the method comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

s2: heating the sodium chloride-sodium carbonate double saturated solution to 60-80 ℃;

s3: adding sodium bicarbonate solid slowly into sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 90-118 ℃, keeping the temperature for 0.5-1 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 60-80 ℃, and filtering to obtain sodium carbonate monohydrate crystals.

3. The process for the preparation of sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids according to claim 2, characterized in that: the method comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

s2: heating the sodium chloride-sodium carbonate double saturated solution to 80 ℃;

s3: adding sodium bicarbonate solid slowly into sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 118 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 80 ℃, and filtering to obtain sodium carbonate monohydrate crystals.

4. The process for the preparation of sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids according to claim 3, characterized in that: the method comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

s2: 100 parts by weight of sodium chloride-sodium carbonate double saturated solution is taken and placed in a reaction kettle, and the temperature is heated to 80 ℃;

s3: slowly adding 108 parts by weight of sodium bicarbonate solid into the reaction kettle while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 118 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 60-80 ℃, and filtering to obtain sodium carbonate monohydrate crystals.

5. The process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids according to any one of claims 1 to 4, characterized in that: in S1, a method for preparing a sodium chloride-sodium carbonate double saturated solution: adding excessive sodium chloride and sodium carbonate solids into water, stirring to form a double saturated solution, and filtering out excessive sodium chloride and sodium carbonate solids to obtain a filtrate, namely the sodium chloride-sodium carbonate double saturated solution.

6. The process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids according to any one of claims 1 to 4, characterized in that: and in S5, adding the filtered filtrate into the reaction kettle for recycling.

7. The process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids according to any one of claims 1 to 4, characterized in that: no bubbles were released from the solution, and it was judged that no carbon dioxide gas was produced.

Technical Field

The invention relates to the technical field of sodium carbonate crystal preparation, in particular to a process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids.

Background

Sodium carbonate is prepared by thermal decomposition of sodium bicarbonate, and the following two processes are adopted in the prior art:

1. and (4) dry process. And pyrolyzing the sodium bicarbonate solid at 180-220 ℃ by using a rotary furnace to obtain the sodium carbonate solid. The process pyrolyzes sodium bicarbonate into sodium carbonate, carbon dioxide and water vapor, the theoretical decomposition rate of the sodium bicarbonate is 100%, but the heat transfer mode of the process is solid-solid heat transfer, the efficiency is low, the energy consumption is high, and the concentration of the carbon dioxide in tail gas is low, so that the process is inconvenient to recycle.

2. And (5) wet process. Sodium bicarbonate is added to the medium water to form a suspension, and is heated to decompose at 95-105 ℃. The method has the advantages that the heat transfer mode is solid-liquid-solid heat transfer, and the heat transfer efficiency is high; the sodium bicarbonate exists in the form of bicarbonate ions in the aqueous solution, is easy to be heated and decomposed, has high heat utilization rate and high initial reaction speed, 75 percent of the sodium bicarbonate is decomposed at 95 ℃, the energy consumption is saved by 50 percent compared with a dry method, and the concentration of carbon dioxide in tail gas is high, so that the recycling is convenient. However, sodium bicarbonate is reversibly decomposed by heating in an aqueous solution, the concentration of sodium carbonate increases with the increase of the amount of sodium carbonate generated, and when the concentration of sodium carbonate reaches about 17%, the sodium carbonate is in dynamic balance with the residual sodium bicarbonate, and the theoretical decomposition rate of sodium bicarbonate is 93%, but the actual production needs a long time to reach the theoretical value, and is unreasonable in economy, and generally controlled to about 85% industrially; and the sodium carbonate obtained by wet decomposition is in a solution state, and is subjected to evaporation and concentration to obtain a sodium carbonate solid.

However, with the strong national advocated "energy saving and efficiency increasing", a pyrolysis process of sodium bicarbonate with high decomposition rate of sodium bicarbonate, low energy consumption and solid sodium carbonate as a product is required.

Disclosure of Invention

In view of the above, the present invention provides a process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solid, which has high decomposition rate of sodium bicarbonate and low energy consumption, and the product is sodium carbonate solid, aiming at the defects of the prior art.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: adding sodium bicarbonate solid slowly into sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s2: after the materials are added, continuously stirring and heating to raise the temperature to 90-118 ℃, and stopping heating when no carbon dioxide gas is generated;

s3: cooling and filtering to obtain sodium carbonate monohydrate crystals.

Further, the method comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

s2: heating the sodium chloride-sodium carbonate double saturated solution to 60-80 ℃;

s3: adding sodium bicarbonate solid slowly into sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 90-118 ℃, keeping the temperature for 0.5-1 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 60-80 ℃, and filtering to obtain sodium carbonate monohydrate crystals.

Further, the method comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

s2: heating the sodium chloride-sodium carbonate double saturated solution to 80 ℃;

s3: adding sodium bicarbonate solid slowly into sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 118 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 80 ℃, and filtering to obtain sodium carbonate monohydrate crystals.

Further, the method comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

s2: 100 parts by weight of sodium chloride-sodium carbonate double saturated solution is taken and placed in a reaction kettle, and the temperature is heated to 80 ℃;

s3: slowly adding 108 parts by weight of sodium bicarbonate solid into the reaction kettle while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 118 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 60-80 ℃, and filtering to obtain sodium carbonate monohydrate crystals.

Further, in S1, a method for preparing a sodium chloride-sodium carbonate double saturated solution: adding excessive sodium chloride and sodium carbonate solids into water, stirring to form a double saturated solution, and filtering out excessive sodium chloride and sodium carbonate solids to obtain a filtrate, namely the sodium chloride-sodium carbonate double saturated solution.

Further, in S5, the filtered filtrate is added into the reaction kettle for recycling.

Further, it was judged that no carbon dioxide gas was generated by no more bubbles in the solution.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention relates to a process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solid, which takes sodium chloride-sodium carbonate double saturated solution as a circulating medium, adds the sodium bicarbonate solid, and heats and decomposes the sodium carbonate solid into sodium carbonate, wherein the sodium carbonate cannot be dissolved in the sodium chloride-sodium carbonate double saturated solution and is crystallized out in the form of sodium carbonate monohydrate.

2. In the traditional sodium bicarbonate wet process, the balance moves to the right along with the progress of pyrolysis reaction, the concentration of sodium carbonate is continuously increased, the alkalinity of the solution is continuously enhanced, the balance is reached when the concentration of sodium carbonate is 17.7%, and the reaction is terminated. The invention adopts sodium chloride-sodium carbonate double saturated solution, and adds sodium chloride, because of salt effect, the solubility of sodium carbonate is reduced, and the balance is continuously carried out, so that sodium carbonate monohydrate can be separated out from the solution, therefore, the decomposition rate of sodium bicarbonate can be up to 100%, in addition, the reacted filtrate (the essence is sodium chloride-sodium carbonate double saturated solution) is added into the reaction kettle for cyclic utilization, and the sodium chloride-sodium carbonate double saturated solution is not consumed in the reaction process.

3. According to the process for preparing the sodium carbonate crystal by the wet pyrolysis of the sodium bicarbonate solid, the sodium bicarbonate solid is added in the traditional wet process, and the sodium chloride-sodium carbonate double saturated solution is used, so that the high decomposition rate of the traditional dry process is realized in the form of the wet process, and the process has the advantages of the traditional wet process and the dry process, has the advantages of low energy consumption, high decomposition rate and solid product form, and is convenient to recycle due to high concentration of carbon dioxide generated in the reaction process.

The process for preparing the sodium carbonate crystal by the pyrolysis of the sodium bicarbonate solid by the wet method combines and improves the technical scheme on the basis of the traditional dry method and wet method processes, and overcomes the following technical difficulties: 1. selecting a sodium chloride-sodium carbonate double saturated solution as a reaction medium, preheating the reaction medium to 60-80 ℃, not affecting feeding, adding sodium bicarbonate solid, heating to 90-118 ℃ for carrying out pyrolysis reaction, and cooling to 60-80 ℃ after the reaction is finished for filtering, so that the filter equipment and operators cannot be damaged; 2. the pyrolysis temperature is controlled to be 90-118 ℃, so that the reaction rate is ensured on one hand, and the judgment of the pyrolysis reaction completion is visual and accurate on the other hand; 3. and controlling the weight parts of the added sodium chloride-sodium carbonate double saturated solution and the added sodium bicarbonate to ensure that the solid-to-liquid ratio after the reaction is controlled to be 40-50 percent, so that the stirring of reactants and the filtration of reaction products are not influenced. Therefore, the process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids according to the present invention is not easily conceivable and realizable by those skilled in the art.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

In order to better understand the present invention, the following examples are further provided to clearly illustrate the contents of the present invention, but the contents of the present invention are not limited to the following examples. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details.

Example one

A process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: adding 108 parts by weight of sodium bicarbonate solid slowly into 100 parts by weight of sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s2: after the materials are added, continuously stirring and heating to raise the temperature to 90 ℃, and stopping heating when no carbon dioxide gas is generated;

s3: cooling and filtering to obtain sodium carbonate monohydrate crystals.

In S1, a method for preparing a sodium chloride-sodium carbonate double saturated solution: adding excessive sodium chloride and sodium carbonate solids into water, stirring to form a double saturated solution, and filtering out excessive sodium chloride and sodium carbonate solids to obtain a filtrate, namely the sodium chloride-sodium carbonate double saturated solution.

As shown in fig. 1, in the preparation process of the present invention, a sodium chloride-sodium carbonate double saturated solution replaces water in the traditional wet method as a circulation medium, after adding sodium bicarbonate solid, heating and pyrolyzing are performed, sodium carbonate generated in the pyrolysis process is continuously separated out in the form of sodium carbonate monohydrate crystals, and carbon dioxide is emitted in the form of gas; and when no bubbles emerge from the solution, judging that the pyrolysis of the sodium bicarbonate is finished, cooling, filtering out sodium carbonate monohydrate, and recycling the filtrate which is still sodium chloride-sodium carbonate double saturated solution.

The solubility of sodium carbonate and sodium chloride in a double saturated solution at different temperatures is shown in table 1:

table 1: solubility of sodium carbonate and sodium chloride in double saturated solution

Temperature (. degree.C.)	60	70	80	90	100	110	118
								Sodium carbonate (wt%)	13.9	11.6	10.9	10.5	10.2	8.4	8.2
Sodium chloride (wt%)	17.8	20.3	21.2	22	22.5	23.8	24.2
								Water (wt%)	68.3	68.1	67.9	67.5	67.3	67.8	67.6

As can be seen from Table 1, the solubility of sodium carbonate in the double saturated solution decreases with the increase of temperature, and at 90-118 ℃, the solubility can be below 10.5%, that is, when the concentration (by mass fraction) of carbonate ions generated by the thermal hydrolysis of sodium bicarbonate in the double saturated solution is more than 10.5 (wt%), sodium carbonate monohydrate crystals are precipitated; in the traditional wet process, because the medium is water, the sodium bicarbonate can be hydrolyzed and pyrolyzed in the water (as shown in the following reaction equation), the balance moves to the right along with the pyrolysis reaction of the sodium bicarbonate, the concentration of the sodium carbonate is continuously increased, the alkalinity of the solution is continuously enhanced, the balance is reached when the concentration of the sodium carbonate is 17.7 percent, and the reaction is terminated; when sodium chloride is added to the solution, the solubility of sodium carbonate decreases due to the salt effect, and sodium carbonate is precipitated from the solution so that the concentration of carbonate ions never reaches 17.7%, whereby the pyrolysis reaction continues until the reaction of the added sodium bicarbonate is completed, and thus, the decomposition rate of sodium bicarbonate theoretically reaches 100%.

Hydrolysis: 2NaHCO₃⇌2HCO₃ ^-+2Na⁺

Pyrolysis: 2HCO₃ ^-⇌CO₃ ^2-+CO₂+H₂O

Example two

A process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: adding 108 parts by weight of sodium bicarbonate solid slowly into 100 parts by weight of sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s2: after the materials are added, continuously stirring and heating to 118 ℃, and stopping heating when no carbon dioxide gas is generated;

s3: cooling and filtering to obtain sodium carbonate monohydrate crystals.

The preparation method of the sodium chloride-sodium carbonate double saturated solution is the same as the first embodiment, and the description is omitted.

In the preparation process of the embodiment of the invention, in S2, the temperature is raised to 118 ℃, because the boiling point of the brine is higher than the boiling point of water, and the boiling point is also raised along with the increase of the concentration of the brine, and the boiling point of the sodium chloride-sodium carbonate double saturated solution is higher than 118 ℃, at 118 ℃, the solution does not boil, and no bubbles of water vapor appear, and at this time, the completion of the pyrolysis reaction can still be judged by no carbon dioxide bubbles.

EXAMPLE III

A process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: adding 108 parts by weight of sodium bicarbonate solid slowly into 100 parts by weight of sodium chloride-sodium carbonate double saturated solution while stirring and heating;

s2: after the materials are added, continuously stirring and heating to 100 ℃, and stopping heating when no carbon dioxide gas is generated;

s3: cooling and filtering to obtain sodium carbonate monohydrate crystals.

The preparation method of the sodium chloride-sodium carbonate double saturated solution is the same as the first embodiment, and the description is omitted.

Example four

A process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

adding excessive sodium chloride and sodium carbonate solids into water, stirring at 80 ℃ to form a saturated solution, filtering out excessive sodium chloride and sodium carbonate solids, and obtaining a filtrate which is a sodium chloride-sodium carbonate double saturated solution;

s2: 100 parts by weight of sodium chloride-sodium carbonate double saturated solution is taken and placed in a reaction kettle, and the temperature is heated to 80 ℃;

s3: slowly adding 108 parts by weight of sodium bicarbonate solid into the reaction kettle while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 105 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 60 ℃, filtering, and drying a filter cake after filtering to obtain sodium carbonate monohydrate crystals.

And adding the filtered filtrate into a reaction kettle for recycling.

No bubbles were released from the solution, and it was judged that no carbon dioxide gas was produced.

EXAMPLE five

A process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

adding excessive sodium chloride and sodium carbonate solids into water, stirring at 80 ℃ to form a saturated solution, filtering out excessive sodium chloride and sodium carbonate solids, and obtaining a filtrate which is a sodium chloride-sodium carbonate double saturated solution;

s2: 100 parts by weight of sodium chloride-sodium carbonate double saturated solution is taken and placed in a reaction kettle, and the temperature is heated to 80 ℃;

s3: slowly adding 100 parts by weight of sodium bicarbonate solid into a reaction kettle while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 105 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 80 ℃, filtering and drying to obtain sodium carbonate monohydrate crystals.

EXAMPLE six

A process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

adding excessive sodium chloride and sodium carbonate solids into water, stirring at 80 ℃ to form a saturated solution, filtering out excessive sodium chloride and sodium carbonate solids, and obtaining a filtrate which is a sodium chloride-sodium carbonate double saturated solution;

s2: 100 parts by weight of sodium chloride-sodium carbonate double saturated solution is taken and placed in a reaction kettle, and the temperature is heated to 80 ℃;

s3: adding 80 parts by weight of sodium bicarbonate solid slowly into the reaction kettle while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 105 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 60-80 ℃, filtering and drying to obtain sodium carbonate monohydrate crystals.

EXAMPLE seven

A process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

adding excessive sodium chloride and sodium carbonate solids into water, stirring at 80 ℃ to form a saturated solution, filtering out excessive sodium chloride and sodium carbonate solids, and obtaining a filtrate which is a sodium chloride-sodium carbonate double saturated solution;

s2: 100 parts by weight of sodium chloride-sodium carbonate double saturated solution is taken and placed in a reaction kettle, and the temperature is heated to 80 ℃;

s3: slowly adding 118 parts by weight of sodium bicarbonate solid into the reaction kettle while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 105 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 60-80 ℃, filtering and drying to obtain sodium carbonate monohydrate crystals.

Example eight

A process for preparing sodium carbonate crystals by wet pyrolysis of sodium bicarbonate solids comprises the following steps:

s1: preparing a sodium chloride-sodium carbonate double saturated solution;

adding excessive sodium chloride and sodium carbonate solids into water, stirring at 80 ℃ to form a saturated solution, filtering out excessive sodium chloride and sodium carbonate solids, and obtaining a filtrate which is a sodium chloride-sodium carbonate double saturated solution;

s2: 100 parts by weight of sodium chloride-sodium carbonate double saturated solution is taken and placed in a reaction kettle, heated to 80 ℃ and preheated;

s3: adding 128 parts by weight of sodium bicarbonate solid slowly into the reaction kettle while stirring and heating;

s4: after the materials are added, continuously stirring and heating to 105 ℃, keeping the temperature for 0.5 hour, and stopping heating when no carbon dioxide gas is generated;

s5: cooling to 60-80 ℃, filtering and drying to obtain sodium carbonate monohydrate crystals.

The following table 2 was obtained by actual weighing of the sodium carbonate monohydrate crystals obtained in examples one, two, three, four, five, six, seven and eight:

according to the sodium bicarbonate pyrolysis equationPrepared by

Theoretical value of parts by weight of sodium carbonate monohydrate crystals = parts by weight of sodium bicarbonate solids sodium carbonate monohydrate relative molecular mass/sodium bicarbonate relative molecular mass;

sodium bicarbonate decomposition rate = decomposed sodium bicarbonate parts by weight/total added sodium bicarbonate parts by weight

(ii) = actual value of sodium bicarbonate relative molecular mass in parts by weight of sodium carbonate monohydrate crystals/(sodium carbonate monohydrate relative molecular mass:sodiumbicarbonate solid parts by weight)

The solid-to-liquid ratio when producing the sodium carbonate monohydrate crystals = actual value of parts by weight of sodium carbonate monohydrate crystals/(actual value of parts by weight of sodium carbonate monohydrate crystals + parts by weight of sodium chloride-sodium carbonate double saturated solution)

From table 2, it can be seen that:

(1) in the process for preparing the sodium carbonate crystal by the wet pyrolysis of the sodium bicarbonate solid with the sodium chloride-sodium carbonate double saturated solution as the reaction medium, when the reaction temperature is controlled to be 90-118 ℃, the decomposition rate of the sodium bicarbonate solid reaches over 99 percent and approaches to a theoretical value no matter the raw material ratio is changed or other reaction conditions (such as cooling temperature, heat preservation time, preheating and the like) are changed;

(2) when the weight part of the solid sodium bicarbonate is 80, the decomposition rate is the highest because the solid-liquid ratio is relatively small, the stirring resistance in the reaction kettle is small, the reaction is more sufficient, and the filtration is convenient; when 128 parts by weight of the solid sodium bicarbonate was added, the decomposition rate was the lowest because the solid-to-liquid ratio was relatively large, the stirring resistance in the reaction vessel was large, the reaction was insufficient, and the difficulty of filtration was increased.

Finally, the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and other modifications or equivalent substitutions made by the technical solutions of the present invention by those of ordinary skill in the art should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.