A production method and system of calcium chloride dihydrate for calcium hydroxide saponification reaction

Abstract

The present invention provides a production method and system for calcium chloride dihydrate oriented to the saponification reaction of calcium hydroxide. Aiming at the problem of low concentration of calcium chloride in the by-product saponification liquid commonly existing in the process of the saponification reaction of calcium hydroxide, the present invention adopts a method and system of compounding and circulating a low-concentration calcium chloride solution to obtain a saponification liquid with a high calcium chloride content, and then through impurity removal, evaporation and flaking, a high-quality calcium chloride dihydrate product is obtained, reducing the energy consumption of brine concentration. The saponification reaction of calcium hydroxide described in the present invention specifically refers to the process of the reaction of calcium hydroxide with a chlorine-containing organic compound to undergo substitution, elimination and other reactions to obtain an organic product and calcium chloride.

Description

[0001] This case claims priority for application number: 2022107939265, invention name: A method and system for producing calcium chloride dihydrate by saponification reaction of calcium hydroxide. Technical Field

[0002] The invention relates to the field of chemical technology and chemical engineering technology, and more specifically to a method and system for producing calcium chloride dihydrate by calcium hydroxide saponification reaction. Background Art

[0003] Calcium chloride dihydrate is a grayish white flake or block solid, and is widely used as a de-icing agent, coagulant and refrigerant. The saponification reaction of calcium hydroxide is widely used in the chemical industry, and its general reaction process is as follows (R is an organic group):

[0004] Ca(OH) 2 +2R-Cl→CaCl 2 +R-OH (1)

[0005] Ca(OH) 2 +2RHCl→CaCl 2 +2R+2H 2 O (2)

[0006] The concentration of calcium chloride aqueous solution produced as a by-product of calcium hydroxide saponification reaction to produce calcium chloride dihydrate is a commonly used low-cost and resource-efficient process route. The calcium hydroxide saponification reaction is generally an oil-water two-phase reaction, and the organic product and the by-product salt are also in the oil phase and the water phase, respectively. In actual industrial production, after the emulsion after the reaction is separated into phases, the oil phase organic matter enters the subsequent product purification section, while the water phase is extracted as a by-product brine. Due to solubility limitations, the calcium hydroxide solution used in actual production is generally a dilute solution with a mass fraction of 10%-20%, and the mass fraction of the by-product calcium chloride solution is about 15%. The resulting dilute brine needs to be concentrated in multiple stages to a calcium chloride mass fraction of about 75% before it can be made into calcium chloride dihydrate crystals in a flake machine. At the same time, in order to improve the oil-water two-phase reaction effect, low-concentration and high-flow alkali solution is often used in industry to make the oil-water two-phase flow ratio similar and reduce the difficulty of mixing. At the same time, low-concentration alkali solution can reduce the side reactions caused by local excess alkali during the two-phase mixing reaction to a certain extent. At present, patents on by-product calcium chloride dihydrate are mainly concentrated on the equipment and process of the concentration unit, such as patent CN 113244642A. Summary of the invention

[0007] In order to directly obtain high-concentration by-product brine and save the equipment investment and energy consumption in the subsequent concentration section, the present invention provides a method and system for producing calcium chloride dihydrate for calcium hydroxide saponification reaction. Low-concentration brine is mixed with calcium hydroxide emulsion, and after saponification reaction, a high-concentration calcium chloride aqueous solution (saponified solution) is obtained. Subsequently, part of the saponified solution is refluxed as the mother liquor for mixing with low-concentration brine.

[0008] To solve at least one of the above problems, on the one hand, the present invention provides a method for producing calcium chloride dihydrate for calcium hydroxide saponification reaction, including:

[0009] A mixed solution of calcium hydroxide and calcium chloride and an organic reactant are introduced into a high-gravity reactor, and after saponification reaction, a saponified solution containing calcium chloride is obtained, wherein the mixed solution includes a calcium hydroxide emulsion with a set concentration and a calcium chloride solution with a set concentration;

[0010] Part of the saponified solution is re-introduced into the calcium hydroxide emulsion for saponification reaction to obtain the saponified solution again until the saponified solution reaches the set output;

[0011] The saponified solution is dehydrated to obtain calcium chloride dihydrate.

[0012] Further, the step of introducing the mixed solution of calcium hydroxide and calcium chloride and the organic reactant into the high-gravity reactor and obtaining the saponified solution containing calcium chloride after saponification reaction includes:

[0013] A calcium chloride solution with a set concentration is introduced into the calcium hydroxide emulsion to obtain a mixed solution;

[0014] The mixed solution and the organic reactant are introduced into the high-gravity reactor for saponification reaction to obtain a reaction colloid;

[0015] After oil-water separation of the reaction colloid, the saponified solution and an oil-phase solution are obtained.

[0016] Further, the method for producing calcium chloride dihydrate further includes:

[0017] The oil-phase solution is separated to obtain unreacted organic reactants;

[0018] The unreacted organic reactants are re-introduced into the high-gravity reactor for saponification reaction.

[0019] On the other hand, the present invention provides a production system for calcium chloride dihydrate for calcium hydroxide saponification reaction, including: a high-gravity reaction component and an evaporation crystallization component;

[0020] The supergravity reaction component includes two inlets for introducing the calcium hydroxide mixed solution and the organic reactant required for the saponification reaction. The supergravity reaction component can intensify the saponification reaction between the mixed aqueous solution and the organic reactant, thereby obtaining a saponified liquid containing calcium chloride. Part of the saponified liquid is reintroduced into the calcium hydroxide emulsion to form a calcium hydroxide mixed solution, and the saponified liquid is obtained again through the saponification reaction until the saponified liquid reaches the set production volume.

[0021] An evaporation and crystallization component, whose inlet is connected to the liquid outlet of the supergravity reaction component. The evaporation and crystallization component processes the saponified liquid to obtain the calcium chloride dihydrate crystals.

[0022] Further, the calcium chloride dihydrate production system for calcium hydroxide saponification reaction further includes: an oil-water separation component;

[0023] The oil-water separation component includes a liquid inlet, an oil-phase liquid outlet, and a water-phase liquid outlet. The oil-water separation component can perform oil-water separation on the reaction colloid exported by the supergravity reaction component to obtain a saponified liquid containing calcium chloride and an oil-phase liquid. The saponified liquid is exported through the water-phase liquid outlet, and the oil-phase liquid is exported through the oil-phase liquid outlet. The water-phase liquid outlet is connected to the mixed aqueous solution inlet of the supergravity reaction component and the evaporation and crystallization component.

[0024] Further, the calcium chloride dihydrate production system for calcium hydroxide saponification reaction further includes: a liquid preparation component;

[0025] The liquid preparation component can be used to generate the calcium hydroxide mixed solution. The liquid preparation component includes two reactant inlets and a reactant outlet. One of the reactant inlets can introduce a calcium hydroxide emulsion with a set concentration, and the other reactant inlet can introduce a calcium chloride solution with a set concentration. The liquid outlet is connected to one of the inlets of the supergravity reaction component.

[0026] Further, the water-phase liquid outlet of the oil-water separation component is connected to the calcium chloride solution inlet of the liquid preparation component.

[0027] Further, the evaporation and crystallization component includes:

[0028] An evaporator, whose liquid inlet is connected to the water-phase liquid outlet of the oil-water separation component;

[0029] A flaker, which includes an inlet and an outlet. The inlet is connected to the evaporator, and the outlet can export the calcium chloride dihydrate crystals.

[0030] The evaporation and crystallization component further includes:

[0031] An organic stripping column, whose liquid inlet is connected to the aqueous liquid outlet of the oil-water separation component, and whose liquid outlet is connected to the evaporator.

[0032] Furthermore, the reactant outlet of the liquid dispensing component is of a sleeve structure, and cooling water or heating steam can be introduced into the sleeve.

[0033] Advantages of the present invention

[0034] The present invention provides a method for producing calcium chloride dihydrate for calcium hydroxide saponification reaction, which uses a high-gravity reactor to maximize the saponification reaction efficiency. Aiming at the possible adverse effects of the brine circulation process on the saponification reaction, such as inhibiting the forward movement of the reaction equilibrium and reducing the concentration of free hydroxide ions, the present invention specifically uses a high-gravity reactor, which can ensure that the original reaction conversion rate and selectivity are hardly affected. Due to the presence of compounded calcium chloride, the calcium ion concentration in the alkali solution increases, and under the condition of constant solubility product, the hydroxide ion concentration will decrease, which is not conducive to the substitution and elimination reactions. In the rotating packed bed, the fluid is subjected to high-speed shearing and fragmentation to achieve molecular-level uniform mixing. The calcium hydroxide particles suspended in the solution, the hydroxide ions in the aqueous solution and the organic reaction raw materials in the oil phase are quickly and fully mixed, and the surface is quickly updated, so that the dissolution equilibrium quickly moves forward. Therefore, the reaction rate is hardly affected. By using the method and system proposed by the present invention, a saponification solution containing 25% to 40% calcium chloride can be directly obtained, saving the subsequent concentration energy consumption.

[0035] The equipment and pipelines in the calcium chloride dihydrate production system for calcium hydroxide saponification reaction provided by the present invention are not easily blocked, easy to clean, and can operate continuously and stably for a long time. In the reaction of calcium hydroxide compounded with calcium chloride as the alkali solution, due to the existence of the common ion effect, the solubility of calcium hydroxide decreases and it is easy to precipitate from the solution. As mentioned above, the present invention can make some precipitated calcium hydroxide particles fully dissolve and react in the reaction stage through a high-gravity reactor and other new type of intensified reactors. At the same time, the system of the present invention makes full use of the head difference, and the circulating high-concentration brine is pumped to a high position, and after being mixed with dilute alkali water, a mixed alkali solution is obtained. Since the calcium hydroxide concentration in the high-concentration brine is extremely low and the solution is clear, there are no special requirements for the fluid conveying equipment. The mixed alkali solution can flow into the reactor by gravity under the action of the head difference, avoiding the problem of blockage in the fluid conveying equipment. At the same time, this section of pipeline is of a sleeve structure. For the calcium hydroxide system, cold water can be regularly passed through the shell layer to increase the solubility of calcium hydroxide and achieve the purpose of cleaning the solid deposits on the pipe wall without stopping. The whole system is three-dimensionally integrated, covering a small area and being convenient for management and operation. The main devices of the system described in the present invention are placed in layers in the vertical direction, three-dimensionally integrated, covering a small area, having few fluid conveying equipment, and being convenient for management and operation. Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 Schematic flow diagram of the production method of calcium chloride dihydrate for the calcium hydroxide saponification reaction in the embodiment of the present invention;

[0038] Figure 2 Schematic flow diagram of the calcium hydroxide saponification reaction in the embodiment of the present invention;

[0039] Figure 3 Schematic flow diagram of the reflux of organic reactants in the calcium hydroxide saponification reaction in the embodiment of the present invention;

[0040] Figure 4 Schematic structural diagram of the high-gravity reaction component and the evaporation crystallization component of the calcium chloride dihydrate production system for the calcium hydroxide saponification reaction in the embodiment of the present invention;

[0041] Figure 5 Schematic structural diagram of the high-gravity reaction component, the evaporation crystallization component, and the oil-water separation component of the calcium chloride dihydrate production system for the calcium hydroxide saponification reaction in the embodiment of the present invention;

[0042] Figure 6 Schematic structural diagram of the high-gravity reaction component, the evaporation crystallization component, the oil-water separation component, and the liquid preparation component of the calcium chloride dihydrate production system for the calcium hydroxide saponification reaction in the embodiment of the present invention;

[0043] Figure 7 Schematic structural diagram of the calcium chloride dihydrate production system for the calcium hydroxide saponification reaction in the embodiment of the present invention;

[0044] Figure 8 Schematic structural diagram of the continuous preparation system for high-concentration by-product brine for the substitution and elimination reaction process in the embodiment of the present invention.

[0045] Description of the drawings: 1. High-gravity reaction component; 2. Evaporation crystallization component; 3. Oil-water separation component; 4. Liquid preparation component. Detailed embodiments

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] For the convenience of description, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0048] In order to directly obtain high-concentration by-product brine and save the equipment investment and energy consumption in the subsequent concentration section, the present invention provides a production method of calcium chloride dihydrate for calcium hydroxide saponification reaction. See Figure 1 , including:

[0049] Step S100: Introduce the mixed solution of calcium hydroxide and calcium chloride and the organic reactant into a high-gravity reactor, and obtain a saponified solution containing calcium chloride after saponification reaction, wherein the mixed solution includes a calcium hydroxide emulsion with a set concentration and a calcium chloride solution with a set concentration;

[0050] Step S200: Reintroduce part of the saponified solution into the calcium hydroxide emulsion for saponification reaction to obtain a saponified solution again until the saponified solution reaches the set output;

[0051] Step S300: Perform dehydration treatment on the saponified solution to obtain calcium chloride dihydrate.

[0052] It is understandable that saponification reactions generally refer to the reaction of an alkali (usually a strong alkali) with an ester to produce an alcohol and a carboxylate salt, especially the reaction of an oil or fat with an alkali. The saponification reaction of calcium hydroxide is generally an oil-water two-phase reaction, and the organic product and the by-product salt are also in the oil phase and the water phase respectively. In actual industrial production, after the reaction emulsion is phase-separated, the organic matter in the oil phase enters the subsequent product purification section, while the water phase is taken out as by-product brine. Due to solubility limitations, the calcium hydroxide solution used in actual production is generally a dilute solution with a mass fraction of 10%-20%, and the mass fraction of the by-product calcium chloride solution is about 15%. The obtained dilute brine needs to be concentrated through multiple stages to a calcium chloride mass fraction of about 75% before it can be made into calcium chloride dihydrate crystals in a flaker. This application uses a high-concentration calcium hydroxide suspension with a mass fraction exceeding 25% and a high-concentration calcium chloride solution with a mass fraction exceeding 35%, in combination with a rotating packed bed reactor. The calcium hydroxide mixed solution is subjected to high-speed shearing and fragmentation to achieve molecular-level uniform mixing. The calcium hydroxide particles suspended in the solution, the hydroxide ions in the solution, and the organic reaction raw materials in the oil phase are rapidly and fully mixed, and the surface is rapidly updated, causing the dissolution equilibrium to rapidly shift forward. Therefore, the reaction rate is hardly affected.

[0053] The reaction process is as follows (R is an organic group):

[0054] Ca(OH) 2 +2R-Cl→CaCl 2 +R-OH (1)

[0055] Ca(OH) 2 +2RHCl→CaCl 2 +2R+2H 2 O (2)

[0056] Part of the saponified liquid containing calcium chloride produced by the saponification reaction is used as the stock solution for producing calcium chloride dihydrate, and the remaining saponified liquid is refluxed as the mother liquor for compounding low-concentration brine. After being remixed with the calcium hydroxide emulsion, it is introduced into the rotating packed bed reactor, and part of the saponified liquid produced by the saponification reaction is refluxed again for re-saponification until the calcium chloride stock solution for producing calcium chloride dihydrate reaches the set output, and then calcium chloride dihydrate is obtained by crystallization.

[0057] The method described in the present invention can also be extended to the substitution and elimination reactions between aqueous solutions of alkaline substances such as sodium hydroxide, ammonia water, sodium carbonate, potassium hydroxide, barium hydroxide, etc. and organic substances containing elements such as chlorine, bromine, iodine, etc. to produce corresponding inorganic salts.

[0058] In some specific embodiments, the mixed solution of calcium hydroxide and calcium chloride and the organic reactant are introduced into the rotating packed bed reactor, and after the saponification reaction, a saponified liquid containing calcium chloride is obtained. See Figure 2 , including:

[0059] Step S101: Introduce a calcium chloride solution with a set concentration into the calcium hydroxide emulsion to obtain a mixed solution;

[0060] Step S102: Introduce the mixed solution and the organic reactant into a high-gravity reactor for saponification reaction to obtain a reaction colloid;

[0061] Step S103: Perform oil-water separation on the reaction colloid to obtain the saponified solution and the oil-phase solution.

[0062] It can be understood that during the calcium hydroxide saponification reaction, the calcium hydroxide emulsion, the calcium chloride solution, and the organic reactant can be simultaneously introduced into the high-gravity reactor for saponification reaction, or the calcium hydroxide emulsion and the calcium chloride solution can be pre-mixed to obtain a calcium hydroxide mixed solution first, and then introduced into the high-gravity reactor together with the organic reactant. In a specific implementation process, the second implementation method is preferably selected. Pre-mixing the calcium hydroxide emulsion and the calcium chloride solution facilitates high-speed shearing in the high-gravity reactor. The saponification reaction yields a reaction colloid of an oil-phase solution and an aqueous-phase saponified solution. After performing oil-water separation on the reaction colloid, the saponified solution and the oil-phase solution are obtained.

[0063] In some specific implementation manners, refer to Figure 3 , the calcium chloride dihydrate production method further includes:

[0064] Step S400: Perform separation treatment on the oil-phase solution to obtain the unreacted organic reactant;

[0065] Step S500: Reintroduce the unreacted organic reactant into the high-gravity reactor for saponification reaction.

[0066] It can be understood that the unreacted organic reactant is obtained by performing separation treatment on the oil-phase solution obtained after oil-water separation, and the unreacted organic reactant is recycled to the high-gravity reactor for continuous reaction.

[0067] As can be seen from the above description, the present invention provides a production method of calcium chloride dihydrate for the saponification reaction of calcium hydroxide, and a rotating packed bed is used to maximize the saponification reaction efficiency. Aiming at the possible adverse effects of the brine circulation process on the saponification reaction, such as inhibiting the forward movement of the reaction equilibrium and reducing the concentration of free hydroxide ions, the present invention specifically uses a rotating packed bed, which can ensure that the original reaction conversion rate and selectivity are hardly affected. Due to the presence of compounded calcium chloride, the calcium ion concentration in the lye increases, and under the condition of constant solubility product, the hydroxide ion concentration will decrease, which is not conducive to the substitution and elimination reactions. In the rotating packed bed, the fluid is subjected to high-speed shearing and fragmentation to achieve molecular-level uniform mixing. The calcium hydroxide particles suspended in the solution, the hydroxide ions in the aqueous solution and the organic reaction raw materials in the oil phase are quickly and fully mixed, and the surface is quickly updated, so that the dissolution equilibrium quickly moves forward. Therefore, the reaction rate is hardly affected. By using the method and system proposed by the present invention, a saponified solution containing 25% to 40% calcium chloride can be directly obtained, saving the energy consumption of subsequent concentration.

[0068] The saponification reaction of calcium hydroxide described in the present invention includes, but is not limited to, the processes of substitution, elimination, etc. of calcium hydroxide and chlorine-containing organic compounds to obtain organic products and calcium chloride; in particular, the method described in the present invention can also be extended to the processes of substitution and elimination reactions between aqueous solutions of alkaline substances such as sodium hydroxide, ammonia water, sodium carbonate, potassium hydroxide, barium hydroxide and organic compounds containing elements such as chlorine, bromine, and iodine to produce corresponding inorganic salts.

[0069] The present invention also provides a production system of calcium chloride dihydrate for the saponification reaction of calcium hydroxide, see Figure 4 , including: a high-gravity reaction assembly 1 and an evaporation and crystallization assembly 2;

[0070] The high-gravity reaction assembly 1 includes two inlets, which can introduce the calcium hydroxide mixed solution and the organic reactant required for the saponification reaction. The high-gravity reaction assembly 1 can strengthen the saponification reaction of the mixed aqueous solution and the organic reactant, and then obtain a saponified solution containing calcium chloride. Part of the saponified solution is re-introduced into the calcium hydroxide emulsion to form a calcium hydroxide mixed solution, and the saponification reaction is carried out again to obtain a saponified solution until the saponified solution reaches the set output;

[0071] The evaporation and crystallization assembly 2, its inlet is connected to the liquid outlet of the high-gravity reaction assembly 1, and the evaporation and crystallization assembly 2 processes the saponified solution to obtain the calcium chloride dihydrate crystals.

[0072] It can be understood that using a rotating packed bed as the high-gravity reaction component 1 can ensure that the original reaction conversion rate and selectivity are hardly affected. Due to the presence of compounded calcium chloride, the calcium ion concentration in the lye increases. Under the condition of constant solubility product, the hydroxide ion concentration will decrease, which is not conducive to the substitution and elimination reactions. In the rotating packed bed, the fluid is subjected to high-speed shearing and fragmentation to achieve molecular-level uniform mixing. The calcium hydroxide particles suspended in the solution, the hydroxide ions in the aqueous solution, and the organic reaction raw materials in the oil phase are rapidly and fully mixed, and the surface is rapidly updated, so that the dissolution equilibrium rapidly moves forward. Therefore, the reaction rate is hardly affected. Preferably, the high-gravity reaction component adopts a new type of reactor that intensifies the liquid-liquid two-phase reaction, including but not limited to a rotating packed bed, a stator-rotor reactor, etc. When the reaction system is relatively complex, the reactor can be extended to the entire reaction separation unit. The partially saponified liquid containing calcium chloride produced by the saponification reaction is used as the original liquid for producing calcium chloride dihydrate, and the remaining partially saponified liquid is refluxed as the mother liquid for compounding low-concentration brine. After being remixed with the calcium hydroxide emulsion, it is introduced into the high-gravity reaction component 1. The saponified liquid produced by the saponification reaction is partially refluxed again for re-saponification until the calcium chloride original liquid for producing calcium chloride dihydrate reaches the set output. Then, the evaporation crystallization component 2 evaporates and crystallizes the saponified liquid to obtain the calcium chloride dihydrate product.

[0073] In some specific embodiments, referring to Figure 5 , the calcium chloride dihydrate production system for calcium hydroxide saponification reaction further includes: an oil-water separation component 3;

[0074] The oil-water separation component 3 includes a liquid inlet, an oil-phase liquid outlet, and a water-phase liquid outlet. The oil-water separation component 3 can perform oil-water separation on the reaction colloid derived from the high-gravity reaction component 1 to obtain a saponified liquid containing calcium chloride and an oil-phase liquid. The saponified liquid is exported through the water-phase liquid outlet, and the oil-phase liquid is exported through the oil-phase liquid outlet, wherein the water-phase liquid outlet is connected to the mixed aqueous solution inlet of the high-gravity reaction component 1 and the evaporation crystallization component 2.

[0075] It can be understood that the saponification reaction produces a reaction colloid of an oil-phase solution and a water-phase saponified liquid. The liquid inlet of the oil-water separation component 3 is connected to the high-gravity reaction component 1. After performing oil-water separation on the reaction colloid, a saponified liquid and an oil-phase solution are obtained. The separated oil-phase solution and water-phase solution are respectively exported from the oil-phase liquid outlet and the water-phase liquid outlet of the oil-water separation component; preferably, the oil-water separation component 3 includes but is not limited to a static oil-water separation tank, a centrifugal separation disk, a hydrocyclone, etc.

[0076] In some specific embodiments, referring to Figure 6 , the calcium chloride dihydrate production system for calcium hydroxide saponification reaction further includes: a liquid preparation component 4;

[0077] The liquid preparation assembly 4 can be used to generate the calcium hydroxide mixed solution. The liquid preparation assembly 4 includes two reactant inlets and one reactant outlet. One of the reactant inlets can introduce a calcium hydroxide emulsion with a set concentration, and the other reactant inlet can introduce a calcium chloride solution with a set concentration. The liquid outlet is connected to one of the inlets of the high-gravity reaction assembly 1.

[0078] It can be understood that one liquid inlet of the liquid preparation assembly 4 is connected to the calcium hydroxide emulsion inlet, the other liquid inlet is connected to the clear water inlet, and the liquid outlet is connected to the reactor liquid inlet; preferably, the outlet pipeline of the liquid preparation assembly 4 is a casing structure, and its shell layer can pass cooling water or heating steam. In the present application, the mass fraction of the calcium hydroxide suspension exceeds 25%, and the mass fraction of the high-concentration calcium chloride solution exceeds 35%.

[0079] In some specific embodiments, referring to Figure 7 , the aqueous phase liquid outlet of the oil-water separation assembly 3 is connected to the calcium chloride solution inlet of the liquid preparation assembly 4.

[0080] It can be understood that the liquid inlet of the liquid preparation assembly 4 is connected to the saponification liquid that circulates back. Therefore, in the calcium chloride dihydrate production system provided by the present invention, only the calcium chloride solution needs to be added at the initial stage of production during the entire calcium chloride dihydrate production process. The calcium chloride solution required in the subsequent production process is obtained by separating the reaction products after the saponification reaction of calcium hydroxide. Thus, there is no need to add a new calcium chloride solution, and the calcium chloride saponification liquid can be produced infinitely in a cycle with the initially added calcium chloride solution.

[0081] In some specific embodiments, the evaporation and crystallization assembly 2 includes:

[0082] An evaporator, whose liquid inlet is connected to the aqueous phase liquid outlet of the oil-water separation assembly 3;

[0083] A flaker, which includes an inlet and an outlet. The inlet is connected to the evaporator, and the outlet can export the calcium chloride dihydrate crystals.

[0084] It can be understood that the liquid inlet of the evaporator is connected to the liquid outlet of the oil-water separation assembly 3, the outlet is connected to the inlet of the flaker, the inlet of the flaker is connected to the outlet of the evaporator, and the outlet is connected to the calcium chloride dihydrate outlet.

[0085] In some specific embodiments, the evaporation and crystallization assembly further includes:

[0086] An organic stripping tower, whose liquid inlet is connected to the aqueous phase liquid outlet of the oil-water separation assembly, and whose liquid outlet is connected to the evaporator.

[0087] It is understandable that the gas inlet of the organic stripping tower is connected to the hot air inlet, the gas outlet is connected to the waste gas outlet, the liquid inlet is connected to the aqueous phase outlet of the oil-water separation component via a circulation pump, and the liquid outlet is connected to the liquid inlet of the evaporator.

[0088] In some specific embodiments, the liquid dispensing component is higher than the high-gravity reaction component in the vertical height, and the high-gravity reaction component is higher than the oil-water separation component in the vertical height; there is a flow control device between the lye inlet pipeline and the brine circulation pipeline of the high-gravity component, which can control the two flows and their ratio.

[0089] As can be seen from the above description, the equipment and pipelines in the calcium chloride dihydrate production system for calcium hydroxide saponification reaction provided by the present invention are not easily blocked, easy to clean, and can operate continuously and stably for a long time. In the reaction of calcium hydroxide compounded with calcium chloride as the lye, due to the existence of the common ion effect, the solubility of calcium hydroxide decreases and it is easy to precipitate from the solution. As mentioned above, the present invention can make some precipitated calcium hydroxide particles fully dissolve and react in the reaction stage through a novel intensifying reactor such as a high-gravity reactor. At the same time, the system of the present invention makes full use of the head difference, and the recycled high-concentration brine is pumped to a high position and mixed with dilute lye to obtain a mixed lye. Since the calcium hydroxide concentration in the high-concentration brine is extremely low and the solution is clear, there are no special requirements for fluid conveying equipment. The mixed lye can flow into the reactor by itself under the action of the head difference, avoiding the problem of blockage in the fluid conveying equipment. At the same time, this section of the pipeline is a casing structure. For the calcium hydroxide system, cold water can be regularly passed through the shell layer to increase the solubility of calcium hydroxide and achieve the purpose of cleaning the solid deposits on the pipe wall without stopping the machine. The whole system is three-dimensionally integrated, covering a small area and being convenient for management and operation. The main devices of the system described in the present invention are placed in layers in the vertical direction, three-dimensionally integrated, covering a small area, having few fluid conveying equipment, and being convenient for management and operation.

[0090] The following describes the wastewater ammonia nitrogen removal system in combination with specific embodiments. In specific embodiments, the system can also be extended to the substitution and elimination reactions between aqueous solutions of alkaline substances such as sodium hydroxide, ammonia water, sodium carbonate, potassium hydroxide, barium hydroxide, etc. and organic substances containing elements such as chlorine, bromine, iodine, etc. to produce corresponding inorganic salts. The system structure is shown in Figure 8 .

[0091] Example 1

[0092] The system described in the present invention is used to produce vinylidene chloride from trichloroethane as a raw material, with calcium chloride aqueous solution as a by-product, and a rotating packed bed is used as the intensifying reactor. The reaction process is as follows: 2C 2 H 3 Cl 3 +Ca(OH) 2 →2C 2 H 2Cl 2 +CaCl 2 +2H 2 A calcium hydroxide suspension with a mass fraction of O(3) of 30.4% and a circulating calcium chloride aqueous solution with a mass fraction of 35% are continuously fed into a liquid mixing tank at a mass flow ratio of 1.33:1, resulting in a mixed aqueous solution with a mass fraction of calcium hydroxide of 17.2% and a mass fraction of calcium chloride of 15%. This mixed solution continuously flows into a rotating packed bed and reacts with the freshly fed trichloroethane liquid. The trichloroethane is in excess relative to calcium hydroxide, and the rotational speed of the rotating packed bed is 1500 rpm. The mixed liquid after sufficient shear emulsification in the rotating packed bed flows into an oil-water separator. The upper oil phase is taken out and sent to the product refining section, and the unreacted trichloroethane separated is recycled back to the rotating packed bed for continuous reaction; the lower aqueous phase is a calcium chloride aqueous solution with a mass fraction of 35%. A part is taken out, and a part is used as recycled brine, and the ratio of the taken-out flow to the recycled flow is 4:3. Through detection and analysis, the single-pass conversion rate of calcium hydroxide is 98.8%. The test device operates stably for 10 days, and the mass fraction of the taken-out calcium chloride solution is between 34.8% and 35.3%. There is no blockage or obvious siltation in the equipment and pipelines.

[0093] Example 1-1

[0094] Reduce the supergravity level of the rotating packed bed in Example 1 to 200 rpm, and keep the other conditions unchanged. The single-pass conversion rate of calcium hydroxide is measured to be 85.5%, and the mass fraction of calcium chloride in the taken-out brine is 26.5%. After continuous operation for 10 days, there is obvious solid siltation of calcium hydroxide in the equipment and pipelines.

[0095] Example 2

[0096] The system described in the present invention is used to produce epichlorohydrin from dichloropropanol as a raw material, with a by-product of calcium chloride aqueous solution, and a rotating packed bed is used as an intensified reactor. The reaction process is as follows:

[0097] 2C 3 H 5 Cl 2 OH+Ca(OH) 2 →2CH 2 OCHCH 2 Cl+CaCl 2 +H 2A calcium hydroxide suspension with a mass fraction of 28% of O(4) and a circulating calcium chloride aqueous solution with a mass fraction of 35% are continuously fed into a liquid mixing tank at a mass flow ratio of 1.33:1, resulting in a mixed aqueous solution with a mass fraction of calcium hydroxide of 16% and a mass fraction of calcium chloride of 15%. This mixed solution continuously flows into a rotating packed bed and reacts with freshly fed dichloropropanol liquid. The dichloropropanol is in excess relative to calcium hydroxide, and the rotational speed of the rotating packed bed is 1500 rpm. The mixed liquid after sufficient shear emulsification in the rotating packed bed flows into an oil-water separator. The upper oil phase is taken out and sent to the product refining section, and the unreacted dichloropropanol separated is recycled back to the rotating packed bed for continuous reaction; the lower aqueous phase is a calcium chloride aqueous solution with a mass fraction of 35%. A part is taken out, and a part is used as circulating brine, and the extraction and circulation flow ratio is 8:5. Through detection and analysis, the single-pass conversion rate of calcium hydroxide is 99.9%. The test device operates stably for 10 days, and the mass fraction of the extracted calcium chloride solution is between 35.1% and 35.4%. There is no blockage or obvious siltation in the equipment and pipelines.

[0098] Example 2-1

[0099] Reduce the supergravity level of the rotating packed bed in Example 2 to 200 rpm, and keep the other conditions unchanged. The measured single-pass conversion rate of calcium hydroxide is 89.1%, and the mass fraction of calcium chloride in the extracted brine is 27.6%. After continuous operation for 10 days, there is obvious solid siltation of calcium hydroxide in the equipment and pipelines.

[0100] Example 3

[0101] The system described in the present invention is used for the production of propylene oxide by chlorohydrin saponification, with by-product calcium chloride aqueous solution, and a rotating packed bed is used as the intensifying reactor. The reaction process is as follows: 2C 3 H 5 ClOH + Ca(OH) 2 → 2CH 2 OCHCH 2 + CaCl 2 + H 2A calcium hydroxide suspension with a mass fraction of O (4) of 28% and a circulating aqueous solution of chloropropanol with a mass fraction of 35% are continuously fed into a liquid preparation tank at a mass flow ratio of 1.33:1, resulting in a mixed aqueous solution with a mass fraction of calcium hydroxide of 16% and a mass fraction of calcium chloride of 15%. This mixed solution continuously flows into a rotating packed bed and reacts with the freshly fed chloropropanol liquid. The chloropropanol is in excess relative to calcium hydroxide, and the rotational speed of the rotating packed bed is 1500 rpm. The mixed liquid after sufficient shear emulsification in the rotating packed bed flows into an oil-water separator. The upper oil phase is taken out and sent to the product refining section, and the unreacted chloropropanol separated is recycled back to the rotating packed bed for further reaction; the lower aqueous phase is a calcium chloride aqueous solution with a mass fraction of 35%. Part of it is taken out, and part is used as recycled brine. The ratio of the taken-out flow to the recycled flow is 8:5. Through detection and analysis, the single-pass conversion rate of calcium hydroxide is 99.8%. The test device operates stably for 10 days, and the mass fraction of the taken-out calcium chloride solution is between 34.9% and 36.1%. There is no blockage or obvious siltation in the equipment and pipelines.

[0102] Example 2-1

[0103] Reduce the supergravity level of the rotating packed bed in Example 2 to 200 rpm, and keep the other conditions unchanged. The single-pass conversion rate of calcium hydroxide is measured to be 87.2%, and the mass fraction of calcium chloride in the taken-out brine is 23.8%. After continuous operation for 10 days, there is obvious solid siltation of calcium hydroxide in the equipment and pipelines.

[0104] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example.

[0105] In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. The above are only the embodiments of the embodiments of this specification and are not used to limit the embodiments of this specification. For those skilled in the art, various changes and modifications can be made to the embodiments of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the embodiments of this specification shall be included within the scope of the claims of the embodiments of this specification.

Claims

1. A production system for calcium chloride dihydrate for the saponification reaction of calcium hydroxide, characterized in that, it includes: a high-gravity reaction component and an evaporation crystallization component; The high-gravity reaction component includes two inlets, which can introduce the calcium hydroxide mixed solution and the organic reactant required for the saponification reaction. The high-gravity reaction component can strengthen the saponification reaction of the mixed aqueous solution and the organic reactant, and then obtain a saponified liquid containing calcium chloride. Part of the saponified liquid is re-introduced into the calcium hydroxide emulsion to form a calcium hydroxide mixed solution, and the saponification reaction is carried out again to obtain the saponified liquid until the saponified liquid reaches the set output; The evaporation crystallization component, its inlet is connected to the liquid outlet of the high-gravity reaction component, and the evaporation crystallization component processes the saponified liquid to obtain the calcium chloride dihydrate crystals; among them, The production system for calcium chloride dihydrate for the saponification reaction of calcium hydroxide further includes: a liquid preparation component; The liquid preparation component can be used to generate the calcium hydroxide mixed solution. The liquid preparation component includes two reactant inlets and one reactant outlet. One of the reactant inlets can introduce a calcium hydroxide emulsion with a set concentration, and the other reactant inlet can introduce a calcium chloride solution with a set concentration. The liquid outlet is connected to one of the inlets of the high-gravity reaction component; The reactant outlet of the liquid preparation component is a sleeve structure, and cooling water or heating steam can be introduced into the sleeve. Among them, the calcium hydroxide emulsion with a set concentration is a high-concentration calcium hydroxide suspension with a mass fraction exceeding 25%, and the calcium chloride solution with a set concentration is a high-concentration calcium chloride solution with a mass fraction exceeding 35%.

2. The production system for calcium chloride dihydrate for the saponification reaction of calcium hydroxide according to claim 1, characterized in that, The production system for calcium chloride dihydrate for the saponification reaction of calcium hydroxide further includes: an oil-water separation component; The oil-water separation component includes a liquid inlet, an oil-phase liquid outlet and a water-phase liquid outlet. The oil-water separation component can carry out oil-water separation on the reaction colloid exported by the high-gravity reaction component to obtain a saponified liquid containing calcium chloride and an oil-phase liquid. The saponified liquid is exported through the water-phase liquid outlet, and the oil-phase liquid is exported through the oil-phase liquid outlet. Among them, the water-phase liquid outlet is connected to the mixed aqueous solution inlet of the high-gravity reaction component and the evaporation crystallization component.

3. The production system for calcium chloride dihydrate for the saponification reaction of calcium hydroxide according to claim 1, characterized in that, The water-phase liquid outlet of the oil-water separation component is connected to the calcium chloride solution inlet of the liquid preparation component.

4. The production system for calcium chloride dihydrate for the saponification reaction of calcium hydroxide according to claim 2, characterized in that, The evaporation crystallization component includes: An evaporator, its liquid inlet is connected to the water-phase liquid outlet of the oil-water separation component; A flaker, which includes an inlet and an outlet. The inlet is connected to the evaporator, and the outlet can export the calcium chloride dihydrate crystals.

5. The production system for calcium chloride dihydrate for the saponification reaction of calcium hydroxide according to claim 4, characterized in that, The evaporation crystallization component further includes: An organic stripping column, whose liquid inlet is connected to the aqueous liquid outlet of the oil-water separation component, and whose liquid outlet is connected to the evaporator.

6. A method for producing calcium chloride dihydrate based on the calcium chloride dihydrate production system for calcium hydroxide saponification reaction according to any one of claims 1-5, characterized in that, it includes: feeding a mixed solution of calcium hydroxide and calcium chloride and an organic reactant into the high-gravity reaction component of the calcium chloride dihydrate production system for calcium hydroxide saponification reaction, and obtaining a saponified liquid containing calcium chloride after saponification reaction, wherein the mixed solution includes a calcium hydroxide emulsion with a set concentration and a calcium chloride solution with a set concentration; re-feeding part of the saponified liquid into the calcium hydroxide emulsion for saponification reaction to obtain the saponified liquid again until the saponified liquid reaches the set output; performing dehydration treatment on the saponified liquid to obtain calcium chloride dihydrate.

7. According to the method for producing calcium chloride dihydrate for calcium hydroxide saponification reaction described in claim 6, characterized in that, the step of feeding a mixed solution of calcium hydroxide and calcium chloride and an organic reactant into the high-gravity reaction component of the calcium chloride dihydrate production system for calcium hydroxide saponification reaction and obtaining a saponified liquid containing calcium chloride after saponification reaction includes: feeding a calcium chloride solution with a set concentration into the calcium hydroxide emulsion to obtain a mixed solution; feeding the mixed solution and the organic reactant into the high-gravity reaction component of the calcium chloride dihydrate production system for calcium hydroxide saponification reaction to perform saponification reaction to obtain a reaction colloid; performing oil-water separation on the reaction colloid to obtain the saponified liquid and an oil-phase solution.

8. According to the method for producing calcium chloride dihydrate for calcium hydroxide saponification reaction described in claim 7, characterized in that, the method for producing calcium chloride dihydrate further includes: performing separation treatment on the oil-phase solution to obtain unreacted organic reactants; re-feeding the unreacted organic reactants into the high-gravity reaction component of the calcium chloride dihydrate production system for calcium hydroxide saponification reaction to perform saponification reaction.

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