Continuous production system for synthesizing calcium propionate using heavy calcium carbonate coupled with MVR heat pump

Abstract

This utility model relates to a continuous production system for synthesizing calcium propionate from heavy calcium carbonate using an MVR heat pump. Its structure includes a first batching vessel, a reaction vessel, a mixer, a neutralization intermediate vessel, an MVR evaporator, a crystallizer, a centrifuge, and a dryer, all connected sequentially by pipelines. The inlet of the mixer is connected to a second batching vessel via a pipeline. The first batching vessel has a calcium carbonate inlet, and the second batching vessel has a calcium hydroxide inlet. The reaction vessel has a propionic acid inlet. The centrifuge's centrifugal liquid outlet is connected to a centrifugal mother liquor tank via a pipeline. The outlet of the centrifugal mother liquor tank is connected to a mother liquor treatment vessel via a pipeline. The outlet of the second batching vessel is connected to the inlet of the mother liquor treatment vessel via a pipeline. The outlets of the centrifugal mother liquor tank and the mother liquor treatment vessel are respectively connected to the inlets of the neutralization intermediate vessel via pipelines. This utility model produces calcium propionate with low cost, high product quality, and no waste gas or wastewater discharge.

Description

Technical Field

[0001] This utility model relates to a calcium propionate production system, specifically a continuous production system for calcium propionate synthesized from heavy calcium carbonate coupled with an MVR heat pump. Background Technology

[0002] Calcium propionate (chemical formula C6H) 10 CaO (CaO4) is a highly efficient and safe food preservative, widely used in the prevention and preservation of mold-prone products such as bread, pastries, and animal feed. Its traditional production processes mainly include the following two routes: 1. Propionic acid-calcium hydroxide neutralization method Calcium propionate is produced from propionic acid and calcium hydroxide through a liquid-phase neutralization reaction, followed by concentration, crystallization, and drying to obtain the final product. While this process is simple, it has the following drawbacks: High raw material costs: Calcium hydroxide is obtained by calcining and digesting limestone, which involves a complex production process and high costs. Strongly alkaline environments can easily trigger side reactions: the pH of a saturated calcium hydroxide solution is greater than 12.5, which can easily catalyze the Cannizzaro side reaction of residual propionaldehyde in the raw material propionic acid, generating propanol as a byproduct, which affects the quality of calcium propionate. There is a problem with residual calcium hydroxide: In order to ensure complete neutralization of propionic acid, an excess of calcium hydroxide is generally required. However, calcium hydroxide has a high saturation solubility. If it remains in the reaction solution, it will precipitate out along with calcium propionate after evaporation and concentration, affecting product quality.

[0003] Environmental issues are prominent: the production process generates a large amount of wastewater containing propionic acid, and the cost of supporting environmental protection facilities is high.

[0004] 2. Biomass conversion method: calcium propionate is prepared by oxidative decarboxylation of calcium lactate as raw material. However, this route has problems such as high toxicity of catalysts (such as Co / Mn bromide) and low reaction selectivity (the proportion of by-product calcium acetate is >15%), and has not yet been industrialized.

[0005] In summary, existing technologies have failed to meet the triple requirements of product quality, environmental friendliness, and economic feasibility. There is an urgent need to develop a new calcium propionate production process that uses readily available raw materials, is clean, and has low emissions. Utility Model Content

[0006] The purpose of this invention is to provide a continuous production system for synthesizing calcium propionate using heavy calcium carbonate coupled with an MVR heat pump, in order to solve the problems of high raw material costs, poor product quality, and wastewater generation in existing production processes.

[0007] This invention is implemented as follows: A continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump includes a first batching vessel, a reaction vessel, a mixer, a neutralization intermediate vessel, an MVR evaporator, a crystallizer, a centrifuge, and a dryer, which are connected sequentially by pipelines. The inlet of the mixer is connected to a second batching vessel by a pipeline. The first batching vessel has a calcium carbonate inlet, and the second batching vessel has a calcium hydroxide inlet. The reaction vessel has a propionic acid inlet. The centrifuge's centrifugal liquid outlet is connected to a centrifugal mother liquor tank by a pipeline. The outlet of the centrifugal mother liquor tank is connected to a mother liquor treatment vessel by a pipeline. The outlet of the second batching vessel is connected to the inlet of the mother liquor treatment vessel by a pipeline. The outlets of the centrifugal mother liquor tank and the mother liquor treatment vessel are respectively connected to the inlets of the neutralization intermediate vessel by pipelines.

[0008] As a further improvement of this utility model, the condensate outlet of the MVR evaporator is connected to a condensate tank via a pipeline, and the condensate tank is connected to the first batching vessel and the second batching vessel via a pipeline.

[0009] As a further improvement of this utility model, the reaction vessel includes a first reaction vessel and a second reaction vessel connected in series by pipelines. The outlet of the first batching vessel is connected to the first reaction vessel by a pipeline. The propionic acid inlet is located on the first reaction vessel. The outlet of the second reaction vessel is connected to the inlet of the mixer by a pipeline.

[0010] As a further improvement of this utility model, carbon dioxide outlets are respectively provided on the first reaction vessel and the second reaction vessel.

[0011] As a further improvement of this utility model, a first activated carbon addition port is provided on the neutralization intermediate kettle, and a first filter is provided on the pipeline between the neutralization intermediate kettle and the MVR evaporator.

[0012] As a further improvement of this utility model, a second activated carbon addition port is provided on the mother liquor treatment vessel, and a second filter is provided at the outlet of the mother liquor treatment vessel.

[0013] As a further improvement of this utility model, the mixer is a static mixer.

[0014] As a further improvement of this utility model, the dryer is a fluidized bed dryer.

[0015] As a further improvement of this utility model, the crystal slurry tank is a high-level crystal slurry tank.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Calcium carbonate and propionic acid are used as the main reaction raw materials, especially heavy calcium carbonate, which is inexpensive and readily available, resulting in low production costs. The reaction is carried out in a weakly acidic environment, with no side reactions and good product quality. The mother liquor and condensate are all returned to the reaction system, and carbon dioxide is collected as a byproduct, so there is no wastewater or waste gas emission from the entire system. The mother liquor is treated before being returned to the system, which effectively avoids the excessive accumulation of metal ions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the continuous production system for synthesizing calcium propionate using heavy calcium carbonate coupled with an MVR heat pump, according to this utility model.

[0018] In the diagram: 1. First batching vessel; 2. Second batching vessel; 3. First reaction vessel; 4. Second reaction vessel; 5. Mixer; 6. Neutralization intermediate vessel; 7. MVR evaporator; 8. Crystallizer tank; 9. Centrifuge; 10. Dryer; 11. Centrifugal mother liquor tank; 12. Mother liquor treatment vessel; 13. First activated carbon inlet; 14. First filter; 15. Second activated carbon inlet; 16. Second filter; 17. Condensate tank; 18. Calcium carbonate inlet; 19. Propionic acid inlet; 20. Carbon dioxide outlet; 21. Calcium hydroxide inlet. Detailed Implementation

[0019] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0020] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] like Figure 1As shown, the continuous production system for synthesizing calcium propionate by coupling MVR heat pump with heavy calcium carbonate of this utility model mainly includes a first batching tank 1, a second batching tank 2, a reaction tank, a mixer 5, a neutralization intermediate tank 6, an MVR evaporator 7, a crystal slurry tank 8, a centrifuge 9, a dryer 10, a centrifugal mother liquor tank 11, a mother liquor treatment tank 12, and a condensate tank 17.

[0022] The first batching vessel 1 and the second batching vessel 2 are used to prepare calcium carbonate slurry and lime slurry, respectively. The first batching vessel 1 is equipped with a calcium carbonate inlet 18 and a water inlet. Calcium carbonate and water are added to the first batching vessel 1, and the mixture is continuously stirred to ensure homogeneity, thus obtaining calcium carbonate slurry. The second batching vessel 2 is equipped with a calcium hydroxide inlet 21 and a water inlet. Calcium hydroxide and water are added to the first batching vessel 1, and the mixture is continuously stirred to ensure homogeneity, thus obtaining lime slurry (calcium hydroxide slurry).

[0023] Heavy calcium carbonate is preferred as it effectively reduces raw material costs. The reaction mainly involves calcium carbonate and propionic acid, with propionic acid in excess at 2-16%. Therefore, the pH of the reaction system is 3-6, and no side reactions occur.

[0024] The reactor is connected to the outlet of the first batching vessel 1 via a pipeline. The reactor is used to react calcium carbonate emulsion and propionic acid to produce calcium propionate. At the beginning of the reaction, a certain amount of calcium propionate solution is added to the reactor. After heating to the required reaction temperature, calcium carbonate emulsion and propionic acid are added simultaneously using a pump to synthesize calcium propionate. At the same time, the reaction system is controlled to have a slight excess of propionic acid and a weakly acidic pH to prevent side reactions.

[0025] The reactor specifically includes a first reactor 3 and a second reactor 4 connected in series by pipelines. The outlet of the first batching vessel 1 is connected to the first reactor 3 by a pipeline. The propionic acid inlet 19 is located on the first reactor 3. The outlet of the second reactor 4 is connected to the inlet of the mixer 5 by a pipeline.

[0026] The reaction of calcium carbonate emulsion and propionic acid to synthesize calcium propionate is a continuous reaction at a temperature of 80-110℃. The reaction consists of two steps. The first step, at a slightly lower temperature, takes place in the first reactor (3), primarily to provide a reaction environment for propionic acid and calcium carbonate and release the heat of reaction. The second step takes place in the second reactor (4). Due to the accumulated heat from the first step, the temperature is higher in this step, carbon dioxide escapes rapidly, and the reaction is more complete. This two-step reaction method results in a uniform and rapid reaction, producing a product of high purity.

[0027] Carbon dioxide outlets 20 are provided on the first reactor 3 and the second reactor 4 respectively. The carbon dioxide generated by the reaction is discharged and collected through the carbon dioxide outlets 20. The by-product carbon dioxide has a high purity and can be made into compressed carbon dioxide gas or dry ice after drying and condensation.

[0028] The second reactor 4 is connected to the mixer 5 via a pipeline. The mixer 5 is connected to the neutralization intermediate reactor 6 via a pipeline. The inlet of the neutralization intermediate reactor 6 is connected to the outlet of the mother liquor treatment reactor 12 and the centrifugal mother liquor tank 11 via a pipeline. The material from the reactor is output to the mixer 5. At the same time, the second batching reactor 2 is connected to the inlet of the mixer 5 via a pipeline. In the mixer 5, the material from the reactor is mixed with lime slurry and then enters the neutralization intermediate reactor 6. At the same time, in the neutralization intermediate reactor 6, the mixture is mixed with the mother liquor from the mother liquor treatment reactor 12 and the mother liquor directly returned to the reactor. The lime slurry neutralizes the mixture to a weakly alkaline state, removing the propionic acid remaining from the reaction process.

[0029] During the neutralization phase, the pH range is controlled between 7.5 and 10.5, which can react off slightly excess propionic acid without leaving any calcium hydroxide residue, resulting in high product purity.

[0030] Mixer 5 can specifically be static mixer 5.

[0031] A first activated carbon addition port 13 is provided on the neutralization intermediate reactor 6, and a first filter 14 is provided on the pipeline between the neutralization intermediate reactor 6 and the MVR evaporator 7. When the material in the neutralization intermediate reactor 6 reaches the specified liquid level, activated carbon (1-5%) is added through the first activated carbon addition port 13, and the mixture is stirred for decolorization. The waste carbon is removed by filtration through a precision filter and then discharged. The filtrate is then transported to the MVR evaporator 7 through the pipeline.

[0032] Material enters MVR evaporator 7 and, after reaching the specified liquid level, the MVR compressor is turned on. Feeding continues until solids precipitate out, at which point material collection begins, while feeding continues to maintain a stable MVR liquid level.

[0033] The material outlet of MVR evaporator 7 is connected to crystal slurry tank 8 via a pipeline, and the condensate outlet of MVR evaporator 7 is connected to condensate tank 17 via a pipeline. The discharge port of crystal slurry tank 8 is connected to centrifuge 9 via a pipeline, the centrifuge liquid discharge port of centrifuge 9 is connected to centrifuge mother liquor tank 11 via a pipeline, and the material outlet of centrifuge 9 is connected to dryer 10 via a pipeline.

[0034] A centrifugal hopper is also provided between centrifuge 9 and dryer 10.

[0035] The condensate tank 17 is connected to the first batching vessel 1 and the second batching vessel 2 via pipelines. All the evaporation condensate generated in the continuous MVR stage is recycled to the calcium carbonate and calcium hydroxide emulsion batching stage.

[0036] The MVR evaporator 7 discharges and conveys the slurry to the high-level crystal slurry tank 8. When the high-level crystal slurry tank 8 reaches the designated liquid level, the crystal slurry is output to the centrifuge 9 for centrifugal separation.

[0037] The outlet of the centrifuged mother liquor is connected to the mother liquor treatment vessel 12, and is also connected to the inlet of the neutralization intermediate vessel 6 through a pipeline. The outlet of the second batching vessel 2 is connected to the inlet of the mother liquor treatment vessel 12 through a pipeline. A second activated carbon addition port 15 is provided on the mother liquor treatment vessel 12, and a second filter 16 is provided at the outlet of the mother liquor treatment vessel 12.

[0038] The centrifuged mother liquor is divided into Mother Liquor I and Mother Liquor II. Mother Liquor I is fed into Mother Liquor Treatment Tank 12, where activated carbon (1-5%) is added through the second activated carbon addition port 15, and calcium hydroxide emulsion is added through the second batching tank 2 to adjust the pH to strongly alkaline. After filtration by the second filter 16 to remove waste carbon and impurities (mainly metallic impurities), it enters the neutralization intermediate tank 6. Mother Liquor II is directly transferred to the neutralization intermediate tank 6 and undergoes neutralization and decolorization treatment along with normal products. By adopting a mother liquor reuse method, the entire production system has no wastewater discharge.

[0039] In the mother liquor treatment vessel 12, the pH of mother liquor I is adjusted to 10-14 using calcium hydroxide emulsion to precipitate metal ions and prevent them from accumulating gradually with the reuse of mother liquor, thus affecting product quality. Controlling mother liquor I to account for 20-60% of the total mother liquor volume avoids the accumulation of metal ions that could affect product quality, while also reducing the amount of mother liquor processed and lowering operating costs.

[0040] Dryer 10 is a fluidized bed dryer. The parameters of dryer 10 are determined based on the product's moisture and particle size requirements. The dryer uses a fluidized bed drying process. The inlet air temperature, bed material thickness, and residence time are adjusted according to the final product's moisture requirements to produce products with a moisture content of 4%-9%. In the drying system, material removed by the cyclone dust collector is directly returned to the fluidized bed. The fluidized bed discharge undergoes multi-stage screening; large (very few) pieces of material are returned to the fluidized bed, while material meeting the particle size requirements is packaged in the packaging system.

[0041] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump, characterized in that, The system includes a first batching vessel, a reaction vessel, a mixer, a neutralization intermediate vessel, an MVR evaporator, a crystallizer, a centrifuge, and a dryer, all connected sequentially by pipelines. The inlet of the mixer is connected to a second batching vessel via a pipeline. The first batching vessel has a calcium carbonate inlet, and the second batching vessel has a calcium hydroxide inlet. The reaction vessel has a propionic acid inlet. The centrifuge's centrifugal liquid outlet is connected to a centrifugal mother liquor tank via a pipeline. The outlet of the centrifugal mother liquor tank is connected to a mother liquor treatment vessel via a pipeline. The outlet of the second batching vessel is connected to the inlet of the mother liquor treatment vessel via a pipeline. The outlets of the centrifugal mother liquor tank and the mother liquor treatment vessel are respectively connected to the inlets of the neutralization intermediate vessel via pipelines.

2. The continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump according to claim 1, characterized in that, The condensate outlet of the MVR evaporator is connected to a condensate tank via a pipeline, and the condensate tank is connected to the first batching vessel and the second batching vessel via a pipeline.

3. The continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump according to claim 1, characterized in that, The reactor includes a first reactor and a second reactor connected in series by pipelines. The outlet of the first batching reactor is connected to the first reactor by a pipeline. The propionic acid inlet is located on the first reactor. The outlet of the second reactor is connected to the inlet of the mixer by a pipeline.

4. The continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump according to claim 3, characterized in that, Carbon dioxide outlets are provided on the first and second reactors respectively.

5. The continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump according to claim 1, characterized in that, A first activated carbon addition port is provided on the neutralization intermediate vessel, and a first filter is provided on the pipeline between the neutralization intermediate vessel and the MVR evaporator.

6. The continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump according to claim 1, characterized in that, A second activated carbon inlet is provided on the mother liquor treatment vessel, and a second filter is provided at the outlet of the mother liquor treatment vessel.

7. The continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump according to claim 1, characterized in that, The mixer is a static mixer.

8. The continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump according to claim 1, characterized in that, The dryer is a fluidized bed dryer.

9. The continuous production system for synthesizing calcium propionate from heavy calcium carbonate coupled with an MVR heat pump according to claim 1, characterized in that, The crystal slurry tank is a high-level crystal slurry tank.

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