Sodium bicarbonate crystallization production process

Abstract

The invention belongs to the technical field of chemical production, and particularly relates to a sodium bicarbonate crystallization production process which comprises the following steps: S1, heating a solution containing sodium bicarbonate in a negative pressure heater; s2, feeding the heated solution into a low-temperature evaporator for evaporation and concentration, and feeding carbon dioxide gas decomposed by heating into a reaction kettle; s3, feeding a crystal-containing mixed solution generated by evaporation and concentration of the solution in the low-temperature evaporator into a reaction kettle, and feeding steam generated by evaporation into a condensation separator; s4, feeding the carbon dioxide gas separated by the condensation separator into a reaction kettle, and discharging liquid obtained by condensation of the condensation separator; s5, enabling the carbon dioxide entering the reaction kettle to react with the mixed solution containing the crystals to generate the crystals; and S6, feeding the crystal-containing solution after the reaction into a filter for filtering to obtain a sodium bicarbonate product, so as to solve the problems of more equipment used for producing sodium bicarbonate and high operation cost in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical production, in particular to a sodium bicarbonate crystal production process. Background Art

[0002] Sodium bicarbonate, commonly known as baking soda, has the chemical formula NaHCO3. It is a white, fine crystal that is weakly alkaline when dissolved in water and is widely used in food, medicine, chemical industry and other fields. The Hou alkali process (combined alkali process) is used in industry: first, ammonia gas is passed into saturated salt water. The solubility of ammonia gas in water is extremely high, forming a saturated ammonia salt solution. The ammonia salt solution is alkaline, which is conducive to the absorption of carbon dioxide and can increase the concentration of bicarbonate ions in the solution, creating conditions for the formation of sodium bicarbonate. Then, carbon dioxide is passed into the ammonia salt solution. At this time, a chemical reaction occurs. Carbon dioxide reacts with water to form carbonic acid, and carbonic acid reacts with the ammonia salt solution to form ammonium bicarbonate. The ammonium bicarbonate further reacts with sodium chloride. Since the solubility of sodium bicarbonate is relatively small, it will precipitate in the reaction system.

[0003] In the prior art, the equipment required for the Hou's alkali production process includes an ammonia absorption tower, an evaporator, a carbonization tower, etc., which has many equipment and high operating costs. Therefore, the present invention provides a sodium bicarbonate crystallization production process. Summary of the invention

[0004] In order to make up for the shortcomings of the prior art, the problem of multiple equipments and high operating costs in the prior art for producing sodium bicarbonate is solved.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a sodium bicarbonate crystal production process described in the present invention comprises the following steps:

[0006] Step S1: a solution containing sodium bicarbonate enters a negative pressure heater for heating;

[0007] Step S2: the heated solution is sent to a low-temperature evaporator for evaporation and concentration, and the carbon dioxide gas decomposed by heating is sent to a reactor;

[0008] Step S3: the mixed solution containing crystals generated by evaporating and concentrating the solution in the low-temperature evaporator is sent to the reactor, and the steam generated by evaporation is sent to the condensation separator;

[0009] Step S4: the carbon dioxide gas separated by the condensation separator is fed into the reactor, and the liquid condensed by the condensation separator is discharged;

[0010] Step S5: the carbon dioxide entering the reactor reacts with the mixed liquid containing the crystals to generate crystals;

[0011] Step S6: The crystal-containing solution after the reaction is sent to a filter for filtration, and the crystals obtained by filtration are sodium bicarbonate products.

[0012] Preferably, the heating temperature in the negative pressure heater in step S1 ranges from 60°C to 70°C.

[0013] Preferably, the evaporation concentration temperature in step S2 is 45°C-55°C.

[0014] Preferably, the crystals generated by evaporation and concentration in step S3 are natural alkali crystals.

[0015] Preferably, the main reaction in step S1 and step S2 is an endothermic reaction, and the principle is:

[0016]

[0017] Preferably, the main reaction in step S5 is an exothermic reaction, and the principle is:

[0018] Na2CO3+CO2+H2O→2NaHCO3

[0019] Preferably, when the reaction in step S5 is carried out, there is circulating cooling water in the reactor to cool the interior of the reactor and control the temperature in the control range of 20°C-30°C.

[0020] Preferably, during filtering in the filter in step S6, a saturated sodium bicarbonate solution is sprayed to wash the crystals.

[0021] Preferably, the mother liquor obtained by filtering in the filter in step S6 is refluxed to the low-temperature evaporator for reuse.

[0022] Preferably, after the mother liquor is refluxed to the low-temperature evaporator three times, the mother liquor is refluxed to the negative pressure heater for reuse the next time.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. The sodium bicarbonate crystal production process of the present invention requires less equipment, utilizes carbon dioxide and sodium bicarbonate generated by thermal decomposition of raw materials for chemical synthesis, and can finely control and purify the product during the cyclic synthesis process to obtain high-purity crystals, and can be reused by reflux of the mother liquor to a low-temperature evaporator, thereby improving solute utilization and saving costs and resources.

[0025] 2. The sodium bicarbonate crystal production process of the present invention can control the reaction temperature inside the reactor by arranging circulating cooling water to cool the inside of the reactor, prevent the sodium bicarbonate generated from decomposing due to heat accumulation caused by the reaction exothermic reaction, and improve the sodium bicarbonate yield.

[0026] 3. The sodium bicarbonate crystal production process of the present invention can remove impurities attached to the crystals by washing the crystals during filtration with a saturated sodium bicarbonate solution, thereby improving the quality of the product, and the washed saturated sodium bicarbonate solution can be refluxed together with the filtered mother liquor for reuse, thereby improving the solute utilization rate and the economic benefit of production.

[0027] 4. The sodium bicarbonate crystal production process of the present invention is characterized in that after the mother liquor is refluxed to the low-temperature evaporator three times, the mother liquor is refluxed to the negative pressure heater for reuse the next time, so that the sodium bicarbonate in the solute is decomposed into sodium carbonate in the negative pressure heater, the alkalinity of the solution is improved, the natural alkali is more easily precipitated in the low-temperature evaporator, and the sodium bicarbonate solute in the mother liquor is prevented from being decomposed too little in the low-temperature generator, the alkalinity of the circulating solution is reduced, and the energy consumption is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 is a process flow chart of Embodiment 1 of the present invention;

[0030] Figure 2 is a process flow chart of Embodiment 2 of the present invention;

[0031] Figure 3 It is a process flow chart of embodiment 3 of the present invention.

[0032] In the figure: 1. Negative pressure heater; 2. Low-temperature evaporator; 3. Condensation separator; 4. Reactor; 5. Filter. DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0034] Embodiment 1

[0035] like Figure 1 As shown, a sodium bicarbonate crystal production process according to an embodiment of the present invention comprises the following steps:

[0036] Step S1: a solution containing sodium bicarbonate enters the negative pressure heater 1 for heating;

[0037] Step S2: the heated solution is sent to the low-temperature evaporator 2 for evaporation and concentration, and the carbon dioxide gas decomposed by heating is sent to the reactor 4;

[0038] Step S3: the mixed solution containing crystals generated by evaporating and concentrating the solution in the low-temperature evaporator 2 is sent to the reactor 4, and the steam generated by evaporation is sent to the condensation separator 3;

[0039] Step S4: the carbon dioxide gas separated by the condensation separator 3 is fed into the reaction kettle 4, and the liquid condensed by the condensation separator 3 is discharged;

[0040] Step S5: the carbon dioxide entering the reactor 4 reacts with the mixed liquid containing the crystals to generate crystals;

[0041] Step S6: The crystal-containing solution after the reaction is sent to the filter 5 for filtration, and the crystals obtained by filtration are sodium bicarbonate products.

[0042] In the step S1, the heating temperature in the negative pressure heater 1 ranges from 60°C to 70°C.

[0043] The evaporation concentration temperature in step S2 is 45°C-55°C.

[0044] The crystals generated by evaporation and concentration in step S3 are natural alkali crystals.

[0045] The main reaction in step S1 and step S2 is an endothermic reaction, and the principle is:

[0046]

[0047] The main reaction in step S5 is an exothermic reaction, and the principle is:

[0048] Na2CO3+CO2+H2O→2NaHCO3

[0049] The mother liquor obtained by filtration in the filter in step S6 is refluxed to the low-temperature evaporator for reuse.

[0050] Embodiment 2

[0051] like Figure 2 As shown, based on Example 1, when the reaction in step S5 is carried out, there is circulating cooling water in the reactor 4 to cool and control the temperature inside the reactor 4, and the temperature is controlled in the range of 20°C-30°C.

[0052] When the filter 5 is filtering in step S6, a saturated sodium bicarbonate solution is sprayed to wash the crystals; during operation, the reaction of sodium carbonate with carbon dioxide and water to generate sodium bicarbonate is an exothermic reaction, and circulating cooling water is provided to cool the inside of the reactor 4, so that the reaction temperature inside the reactor body can be controlled, and the decomposition of the generated sodium bicarbonate due to the accumulation of heat due to the reaction exothermic heat can be prevented, thereby improving the yield of sodium bicarbonate; by using a saturated sodium bicarbonate solution to wash the crystals during filtration, impurities attached to the crystals can be removed, and the quality of the product can be improved, and the washed saturated sodium bicarbonate solution can be refluxed together with the filtered mother liquor for reuse, thereby improving the solute utilization rate and the economic benefits of production.

[0053] Embodiment 3

[0054] like Figure 3 As shown, on the basis of Example 2, after the mother liquor refluxes to the low-temperature evaporator 2 three times, the next mother liquor refluxes to the negative pressure heater 1 for reuse; during operation, the washed saturated sodium bicarbonate solution is refluxed to the low-temperature evaporator 2 with the filtered mother liquor for reuse, but the evaporation temperature in the low-temperature evaporator 2 is low, and only a small amount of sodium bicarbonate in the solution is decomposed. As the sodium bicarbonate in the circulating solution of the process continues to increase, by setting the mother liquor to reflux to the low-temperature evaporator 2 three times, the next mother liquor refluxes to the negative pressure heater 1 for reuse, so that the sodium bicarbonate in the solute is decomposed into sodium carbonate in the negative pressure heater 1, the alkalinity of the solution is improved, and the natural alkali is easier to precipitate in the low-temperature evaporator 2, and the sodium bicarbonate solute in the mother liquor is prevented from being decomposed too little in the low-temperature generator 2, the alkalinity of the circulating solution is reduced, and the energy consumption is improved.

[0055] Working principle: After heating the sodium bicarbonate solution to decompose carbon dioxide and sodium carbonate, the sodium carbonate and carbon dioxide are used to synthesize sodium bicarbonate crystals. This can make full use of the sodium carbonate and carbon dioxide that have been generated, avoid excessive dependence on new raw materials, and reduce production costs. At the same time, in the cyclic synthesis process, the product can be finely controlled and purified. By adjusting the reaction conditions, such as temperature, pressure, concentration, etc., the growth of sodium bicarbonate crystals can be made more orderly, thereby obtaining higher purity crystals. Compared with synthesizing sodium bicarbonate directly from raw materials, the cyclic synthesis method can also reduce energy consumption.

[0056] The above-mentioned front, back, left, right, top and bottom are all based on the figures in the specification. Figure 1 As a benchmark, according to the person's observation perspective, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0057] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0058] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A sodium bicarbonate crystal production process, characterized in that: The following steps are involved: Step S1: a solution containing sodium bicarbonate enters a negative pressure heater (1) for heating; Step S2: the heated solution is sent to a low-temperature evaporator (2) for evaporation and concentration, and the carbon dioxide gas decomposed by heating is sent to a reaction kettle (4); Step S3: the mixed solution containing crystals generated by evaporating and concentrating the solution in the low-temperature evaporator (2) is sent to the reaction kettle (4), and the steam generated by evaporation is sent to the condensation separator (3); Step S4: the carbon dioxide gas separated by the condensation separator (3) is fed into the reaction kettle (4), and the liquid condensed by the condensation separator (3) is discharged; Step S5: the carbon dioxide entering the reactor (4) reacts with the mixed liquid containing the crystals to generate crystals; Step S6: The crystal-containing solution after the reaction is sent to a filter (5) for filtration, and the crystals obtained by filtration are sodium bicarbonate products.

2. A sodium bicarbonate crystal production process according to claim 1, characterized in that: In step S1, the heating temperature in the negative pressure heater (1) ranges from 60°C to 70°C.

3. A sodium bicarbonate crystal production process according to claim 2, characterized in that: The evaporation concentration temperature in step S2 is 45°C-55°C.

4. A sodium bicarbonate crystal production process according to claim 3, characterized in that: The crystals generated by evaporation and concentration in step S3 are natural alkali crystals.

5. A sodium bicarbonate crystal production process according to claim 4, characterized in that: The main reaction in step S1 and step S12 is an endothermic reaction, and the principle is:

6. A sodium bicarbonate crystal production process according to claim 5, characterized in that: The main reaction in step S5 is an exothermic reaction, and the principle is: Na2CO3+CO2+H2O→2NaHCO3 7. A sodium bicarbonate crystal production process according to claim 6, characterized in that: When the reaction in step S5 is carried out, there is circulating cooling water in the reactor (4) to cool the interior of the reactor (4) and control the temperature within the temperature range of 20°C-30°C.

8. A sodium bicarbonate crystal production process according to claim 7, characterized in that: When filtering in the filter (5) in step S6, a saturated sodium bicarbonate solution is sprayed to wash the crystals.

9. A sodium bicarbonate crystal production process according to claim 8, characterized in that: In step S6, the mother liquor obtained by filtering in the filter (5) is returned to the low-temperature evaporator (2) for reuse.

10. A sodium bicarbonate crystal production process according to claim 9, characterized in that: After the mother liquor is refluxed to the low-temperature evaporator (2) three times, the mother liquor is refluxed to the negative pressure heater (1) for reuse the next time.

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