Apparatus and method for the preparation of stearic acid and stearic acid derivatives

Abstract

This invention discloses an apparatus and method for preparing stearic acid and stearic acid derivatives, including a reaction vessel, a main tower connected to the reaction vessel, nitrogen distributors located at the upper and lower parts of the main tower, a pressure atomizer located above the upper nitrogen distributor, a vaporizer connected to the upper and lower nitrogen distributors, and a liquid nitrogen tank connected to the other end of the vaporizer. This invention employs melt spray atomization. Common atomization methods often involve dissolving the substance in a solvent and then spraying the resulting solution, which introduces new impurities, and solvent removal requires a significant amount of additional energy. This invention uses a melting process to obtain the liquid, followed by pressure spraying to obtain atomized droplets. It eliminates the need for solvent introduction, uses liquid nitrogen as a low-temperature source, and allows the particle size of the stearic acid and stearic acid derivatives to be adjusted between 200-1000 mesh, resulting in uniform particle size and a yield greater than 97%.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to an apparatus and method for preparing stearic acid and stearic acid derivatives. Background Technology

[0002] Stearic acid is a naturally occurring fatty acid found in almost all oils and fats to varying amounts. It is present in higher concentrations in animal fats, such as butter (up to 24%), while vegetable oils contain less, such as tea oil (0.8%) and palm oil (6%). However, cocoa butter contains as much as 34%. The main industrial methods for producing stearic acid are fractionation and pressing. In the fractionation method, a decomposing agent is added to the hardened oil, followed by hydrolysis to obtain crude fatty acids. These crude fatty acids are then washed, distilled, and decolorized to obtain the final product. Glycerin is produced as a byproduct.

[0003] Stearic acid is a white or slightly yellow solid with a faint fatty odor. It is non-toxic and melts into a colorless, transparent liquid. It is readily soluble in ether and in organic solvents such as alcohol, acetone, chloroform, carbon tetrachloride, benzene, and carbon disulfide, but insoluble in water. Its melting point is 70-71℃. It primarily functions as an internal lubricant, and the typical addition amount is 0.2-0.5 parts; excessive amounts can cause blooming. As a polar group, it has good compatibility with PVC resin and can improve lubrication within the melt. However, stearic acid molecules are also bonded by hydrogen bonds, which reduces its polarity and enhances its external lubrication. Therefore, stearic acid can be considered both an internal and external lubricant.

[0004] Stearic acid can also be used as a raw material to prepare a series of stearic acid derivatives, such as stearates and stearates. Stearic acid and its derivatives are widely used as basic raw materials for surfactants. In China, they are mainly used in: the rubber industry as vulcanizing activators; the plastics industry as lubricants and stabilizers; the textile industry and household detergents as softeners and bactericides; precision casting as wax molds; and the lubricating grease industry as soap bases.

[0005] In the application of stearic acid and its derivatives, different material morphologies are typically selected based on the specific application scenario. In recent years, with the expansion of applications in high-end materials, the requirements for stearic acid and its derivatives have become increasingly stringent, demanding smaller particle sizes and better particle uniformity. This places increasingly higher demands on the preparation of stearic acid and its derivatives.

[0006] Stearic acid and stearic acid derivatives can usually be prepared by ball milling or air jet milling. However, because stearic acid has a very low melting point and is very easy to bond through hydrogen bonds, the particles tend to agglomerate into large particles, making it impossible to prepare ultrafine stearic acid and stearic acid derivatives.

[0007] Currently, the market demand for ultrafine stearic acid and its derivatives is gradually increasing. However, due to technological bottlenecks, the production volume of these ultrafine particles cannot meet market demand, and they are expensive. Finding a process that can reduce production costs, is highly operable, and can be industrialized is urgently needed. Summary of the Invention

[0008] This invention addresses the various shortcomings of existing technologies by providing an apparatus and method for preparing stearic acid and stearic acid derivatives.

[0009] To achieve the above objectives, the present invention employs the following technical solution:

[0010] This invention discloses an apparatus for preparing stearic acid and stearic acid derivatives, including a reaction vessel, a main tower connected to the reaction vessel, nitrogen distributors located at the upper and lower parts of the main tower, a pressure atomizer located above the upper nitrogen distributor, a vaporizer connected to the upper and lower nitrogen distributors, and a liquid nitrogen tank connected to the other end of the vaporizer.

[0011] As a further improvement, the reactor described in this invention is connected to the pressure atomizer inside the main tower, and a feed pump is provided between the reactor and the pressure atomizer.

[0012] As a further improvement, the top outlet of the main tower described in this invention is connected to a bag filter, and the other end of the bag filter is connected to an induced draft fan.

[0013] This invention also discloses a method for preparing stearic acid and stearic acid derivatives, comprising the following steps:

[0014] Stearic acid and stearic acid derivatives are added to the reaction vessel, heated to melt them, and stirred continuously.

[0015] Continue stirring, and control the temperature at 10-30°C above the melting point of stearic acid and stearic acid derivatives. At the same time, use a feed pump to send the liquid to the top of the tower, and spray it into atomized droplets through a pressure atomizer.

[0016] The liquid nitrogen in the liquid nitrogen tank is vaporized to obtain cryogenic nitrogen gas. Then, the cryogenic nitrogen gas is introduced into the main tower through two nitrogen gas distributors at the top and bottom of the main tower. The cryogenic nitrogen gas is tangentially introduced into the nitrogen gas distributor by a cyclone.

[0017] The stearic acid and stearic acid derivatives are atomized droplets, which solidify rapidly upon contact with ultra-low temperature nitrogen cold air and cool into finished products in a very short time, and are discharged from the bottom of the main tower.

[0018] When the nitrogen-cooled air comes into contact with the droplet clusters, the air temperature increases. It is then drawn out as waste gas by the induced draft fan, and the micro-powder entrained in the waste gas is recovered by a bag filter.

[0019] As a further improvement, the stearic acid and stearic acid derivatives described in this invention include any one of stearic acid, glyceryl monostearate, triglyceryl stearate, and zinc stearate.

[0020] As a further improvement, the cryogenic nitrogen gas described in this invention is introduced into the main tower through two nitrogen gas distributors at the top and bottom of the main tower. The distribution method is pulsed, and the pulse feeding time is 1-5s for the top and 5-50s for the bottom.

[0021] As a further improvement, the particle size of the product prepared by the present invention can be adjusted between 200-1000 mesh, the particle size is uniform, and the yield is greater than 97%.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. This invention employs a melt-spray atomization method. Common atomization methods often involve dissolving stearic acid in a solvent to form a solution before spraying it, which introduces new impurities, and solvent removal requires a significant amount of additional energy. Based on the physicochemical properties of stearic acid and its derivatives, this invention uses a melting process to obtain a liquid, which is then pressure-sprayed to produce a mist of droplets, eliminating the need for introducing a solvent.

[0024] 2. This invention uses liquid nitrogen as a cryogenic source. Common cooling methods often involve using air conditioning systems to prepare cold air, which is then fed into a tower for cooling the droplets. However, stearic acid and its derivatives are organic compounds, flammable and explosive; air entering the tower would pose a significant hazard. This invention uses liquid nitrogen as a cryogenic source. The liquid nitrogen entering the tower not only brings extremely low temperatures (far lower than those of air conditioning systems), but also ensures the inherent safety of the system within the nitrogen atmosphere, eliminating the risk of flammability and explosion.

[0025] 3. In this invention, cryogenic nitrogen is introduced into the main tower through two nitrogen distributors at the top and bottom, using a pulsed distribution method. The pulse feeding time is 1-5s for the top and 5-50s for the bottom. This pulsed feeding method can significantly improve the uniformity of product particles and significantly reduce the particle size. Introducing cryogenic nitrogen from the top allows the pressure spray droplets to rapidly condense and solidify into particles due to the large temperature difference. However, these ultrafine particles have high surface energy and are prone to adhesion, aggregation, and even agglomeration as they descend, leading to an increase in particle size. Introducing cryogenic nitrogen from the bottom creates a countercurrent contact, which prolongs the particle residence time. Furthermore, the pressure spray droplets are prone to merging and growth in the upper part, which is also detrimental to improving product particle uniformity and significantly reducing particle size. The pulsed feeding method presented in this invention not only allows the atomized droplets obtained from pressure spraying to rapidly condense and solidify into particles due to the significant temperature difference, but also, the pulsed feeding of ultra-low temperature nitrogen into the upper and lower parts creates a complex turbulent system within the tower, significantly increasing heat transfer intensity and particle collision and crushing force. This achieves the invention's objective of greatly improving product particle uniformity and significantly reducing product particle size. Furthermore, the improved particle uniformity also leads to a substantial increase in product yield.

[0026] 4. In this invention, the particle size of stearic acid and stearic acid derivatives can be adjusted between 200-1000 mesh, resulting in uniform particle size and a yield of over 97%. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the device of the present invention;

[0028] In the diagram, 1 is the reactor, 2 is the feed pump, 3 is the main tower, 4 is the nitrogen distributor, 5 is the pressure atomizer, 6 is the vaporizer, 7 is the liquid nitrogen tank, 8 is the bag filter, and 9 is the induced draft fan. Detailed Implementation

[0029] This invention discloses an apparatus for preparing stearic acid and stearic acid derivatives. Figure 1 This is a schematic diagram of the device of the present invention; it includes a reaction vessel 1, a main tower 3 connected to the reaction vessel 1, nitrogen distributors 4 located at the upper and lower parts of the main tower 3, a pressure atomizer 5 located above the upper nitrogen distributor 4, a vaporizer 6 connected to the upper and lower nitrogen distributors 4, and a liquid nitrogen tank 7 connected to the other end of the vaporizer 6. The reaction vessel 1 is connected to the pressure atomizer 5 inside the main tower 3, and a feed pump 2 is installed between the reaction vessel 1 and the pressure atomizer 5. A bag filter 8 is connected to the top outlet of the main tower 3, and an induced draft fan 9 is connected to the other end of the bag filter 8.

[0030] The preparation method of the present invention is as follows:

[0031] 1. Stearic acid and stearic acid derivatives are added to reactor 1, heated to melt them, and stirred continuously.

[0032] 2. Continue stirring and control the temperature at 10-30°C above the melting point of stearic acid and its derivatives. At the same time, use pump 2 to send the liquid to the top of the tower and spray it into atomized droplets through pressure atomizer 5.

[0033] 3. Liquid nitrogen in liquid nitrogen tank 7 is passed through vaporizer 6 to obtain cryogenic nitrogen gas. Then, the cryogenic nitrogen gas is introduced into main tower 3 through two nitrogen distributors 4 at the top and bottom of main tower 3.

[0034] 4. Stearic acid and stearic acid derivatives in the form of mist droplets rapidly solidify upon contact with ultra-low temperature nitrogen cold air, and cool into finished products in a very short time, which are then discharged from the bottom of the main tower 3.

[0035] 5. After the nitrogen-cooled air comes into contact with the droplet cluster, the air temperature increases, and it is extracted as waste gas by the induced draft fan 9. The fine powder entrained in the waste gas is recovered using a separation device.

[0036] Stearic acid and its derivatives include any one of stearic acid, glyceryl monostearate, glyceryl tristearate, and zinc stearate. Ultra-low temperature nitrogen is introduced into the main column 3 through two nitrogen distributors 4 at the top and bottom, using a pulse distribution method. The pulse feeding time is 1-5s for the top and 5-50s for the bottom. The resulting product particle size is adjustable between 200-1000 mesh, with uniform particle size and a yield greater than 97%.

[0037] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of the present invention is not limited to the embodiments.

[0038] Example 1

[0039] 1) Stearic acid is added to reactor 1, heated to melt it, and stirred continuously.

[0040] 2) Continue stirring, keep the temperature at 100℃, and use the feed pump 2 to send the liquid to the top of the tower, where it is sprayed into atomized droplets by the pressure atomizer 5.

[0041] 3) Liquid nitrogen in liquid nitrogen tank 7 is passed through vaporizer 6 to obtain cryogenic nitrogen gas. Then, the cryogenic nitrogen gas is introduced into main tower 3 through two nitrogen distributors 4 at the top and bottom, using a pulse distribution method. The pulse feeding time is 1s for the top and 5s for the bottom.

[0042] 4) Stearic acid droplets, upon contact with ultra-low temperature nitrogen air, rapidly solidify and cool into a finished product within a very short time, which is then discharged from the bottom of the main tower 3.

[0043] 5) After the nitrogen-cooled air comes into contact with the droplet cluster, the air temperature increases, and it is extracted as waste gas by the induced draft fan 9. The fine powder entrained in the waste gas is recovered using a separation device.

[0044] The final obtained stearic acid ultrafine particles have a particle size between 200-300 mesh, uniform particle size, and a yield of over 97%.

[0045] Example 2

[0046] 1) In reaction vessel 1, add glyceryl monostearate, heat it to melt it, and stir continuously.

[0047] 2) Continue stirring, control the temperature at 90℃, and at the same time use the feed pump 2 to send the liquid to the top of the tower, and spray it into atomized droplets through the pressure atomizer 5.

[0048] 3) Liquid nitrogen in liquid nitrogen tank 7 is passed through vaporizer 6 to obtain cryogenic nitrogen gas. Then, the cryogenic nitrogen gas is introduced into main tower 3 through two nitrogen distributors 4 at the top and bottom, using a pulse distribution method. The pulse feeding time is 5s:50s for the top to the bottom.

[0049] 4) The mist-like droplets of glyceryl stearate solidify rapidly upon contact with ultra-low temperature nitrogen air, and cool into the finished product in a very short time, which is then discharged from the bottom of the main tower 3.

[0050] 5) After the nitrogen-cooled air comes into contact with the droplet cluster, the air temperature increases, and it is extracted as waste gas by the induced draft fan 9. The fine powder entrained in the waste gas is recovered using a separation device.

[0051] The final product obtained is ultrafine glyceryl monostearate particles with a particle size between 300-500 mesh, uniform particle size, and a yield of over 99%.

[0052] Example 3

[0053] 1) In reaction vessel 1, add triglyceride stearate, heat it to melt it, and stir continuously.

[0054] 2) Continue stirring, control the temperature at 85℃, and at the same time use the feed pump 2 to send the liquid to the top of the tower, and spray it into atomized droplets through the pressure atomizer 5.

[0055] 3) Liquid nitrogen in liquid nitrogen tank 7 is passed through vaporizer 6 to obtain cryogenic nitrogen gas. Then, the cryogenic nitrogen gas is introduced into main tower 3 through two nitrogen distributors 4 at the top and bottom, using a pulse distribution method. The pulse feeding time is 3s:30s for the top to the bottom.

[0056] 4) The mist-like droplets of triglyceride stearate solidify rapidly upon contact with ultra-low temperature nitrogen cold air, and cool into the finished product in a very short time, and are discharged from the bottom of the main tower 3.

[0057] 5) After the nitrogen-cooled air comes into contact with the droplet cluster, the air temperature increases, and it is extracted as waste gas by the induced draft fan 9. The fine powder entrained in the waste gas is recovered using a separation device.

[0058] The final obtained ultrafine triglyceride stearate particles have a particle size between 500-700 mesh, uniform particle size, and a yield of over 98%.

[0059] Example 4

[0060] 1) Add zinc stearate to reactor 1, heat it to melt it, and stir continuously.

[0061] 2) Continue stirring, control the temperature at 140℃, and at the same time use the feed pump 2 to send the liquid to the top of the tower, and spray it into atomized droplets through the pressure atomizer 5.

[0062] 3) Liquid nitrogen in liquid nitrogen tank 7 is passed through vaporizer 6 to obtain cryogenic nitrogen gas. Then, the cryogenic nitrogen gas is introduced into main tower 3 through two nitrogen distributors 4 at the top and bottom, using a pulse distribution method. The pulse feeding time is 2s:15s for the top to the bottom.

[0063] 4) The atomized droplets of zinc stearate solidify rapidly upon contact with ultra-low temperature nitrogen air, and cool down to become the finished product in a very short time, which is then discharged from the bottom of the main tower 3.

[0064] 5) After the nitrogen-cooled air comes into contact with the droplet cluster, the air temperature increases, and it is extracted as waste gas by the induced draft fan 9. The fine powder entrained in the waste gas is recovered using a separation device.

[0065] The final obtained zinc stearate ultrafine particles have a particle size between 800-1000 mesh, uniform particle size, and a yield of over 98%.

[0066] Compare with Example 1

[0067] 1) In reaction vessel 1, add glyceryl monostearate, heat it to melt it, and stir continuously.

[0068] 2) Continue stirring, control the temperature at 90℃, and at the same time use the feed pump 2 to send the liquid to the top of the tower, and spray it into atomized droplets through the pressure atomizer 5.

[0069] 3) Cool air is obtained through heat exchange using an industrial air conditioning refrigeration system, with a temperature of approximately 5-10℃. The cool air is introduced into the tower from the bottom.

[0070] 4) The mist-like droplets of stearic acid monoglyceride undergo a cooling and solidification process upon contact with cold air, and become the finished product after cooling, which is discharged from the bottom of the main tower 3.

[0071] 5) After the cold air comes into contact with the droplet group, the air temperature increases, and it is extracted as waste gas by the induced draft fan 9. The fine powder entrained in the waste gas is recovered by a separation device.

[0072] The final product, consisting of glyceryl monostearate particles, is mostly between 5 and 40 mesh, exhibiting highly uneven particle size distribution. Furthermore, this system poses significant safety risks.

[0073] As can be seen, liquid nitrogen was not used as a cryogenic source in Comparative Example 1. Cold air was prepared using an air conditioning refrigeration system and then sent into the tower for cooling the droplets. Due to the very small temperature difference, it was difficult to quickly achieve the cooling and condensation solidification process, resulting in product particles that were too large and had a very uneven particle size. Furthermore, this system poses significant safety hazards, including a risk of flammability and explosion.

[0074] Compare with Example 2

[0075] 1) In reaction vessel 1, add glyceryl monostearate, heat it to melt it, and stir continuously.

[0076] 2) Continue stirring, control the temperature at 90℃, and at the same time use the feed pump 2 to send the liquid to the top of the tower, and spray it into atomized droplets through the pressure atomizer 5.

[0077] 3) The liquid nitrogen in the liquid nitrogen tank 7 is passed through the vaporizer 6 to obtain cryogenic nitrogen gas. Then, the cryogenic nitrogen gas is introduced into the main tower 3 through the nitrogen distributor 4 at the top of the main tower 3.

[0078] 4) The mist-like droplets of glyceryl stearate solidify rapidly upon contact with ultra-low temperature nitrogen air, and cool into the finished product in a very short time, which is then discharged from the bottom of the main tower 3.

[0079] 5) After the nitrogen-cooled air comes into contact with the droplet cluster, the air temperature increases, and it is extracted as waste gas by the induced draft fan 9. The fine powder entrained in the waste gas is recovered using a separation device.

[0080] The final product obtained is glyceryl monostearate particles with a particle size between 40 and 200 mesh. The particle size is very uneven, and the yield is 83%.

[0081] As can be seen, in Comparative Example 2, the cryogenic nitrogen gas was only introduced into the main tower 3 through the nitrogen distributor 4 at the top of the main tower 3. Introducing cryogenic nitrogen from the top allows the atomized droplets from the pressure spray to rapidly condense and solidify into particles due to the huge temperature difference. However, these ultrafine particles have high surface energy and are prone to adhesion, aggregation, or even agglomeration as they descend with increasing temperature, leading to an increase in particle size. Ultimately, the product particles are too large, resulting in a highly uneven particle size distribution.

[0082] Compare with Example 3

[0083] 1) In reaction vessel 1, add glyceryl monostearate, heat it to melt it, and stir continuously.

[0084] 2) Continue stirring, control the temperature at 90℃, and at the same time use the feed pump 2 to send the liquid to the top of the tower, and spray it into atomized droplets through the pressure atomizer 5.

[0085] 3) The liquid nitrogen in the liquid nitrogen tank 7 is passed through the vaporizer 6 to obtain cryogenic nitrogen gas. Then, the cryogenic nitrogen gas is introduced into the main tower 3 through the nitrogen distributor 4 at the bottom of the main tower 3.

[0086] 4) The mist-like droplets of glyceryl stearate solidify rapidly upon contact with ultra-low temperature nitrogen air, and cool into the finished product in a very short time, which is then discharged from the bottom of the main tower 3.

[0087] 5) After the nitrogen-cooled air comes into contact with the droplet cluster, the air temperature increases, and it is extracted as waste gas by the induced draft fan 9. The fine powder entrained in the waste gas is recovered using a separation device.

[0088] The final product obtained is glyceryl monostearate particles with a particle size between 60 and 200 mesh. The particle size is uneven, and the yield is 88%.

[0089] As can be seen, in Comparative Example 3, the cryogenic nitrogen gas is only introduced into the main tower 3 through the nitrogen distributor 4 at the bottom of the main tower 3. Introducing cryogenic nitrogen gas from the bottom creates a countercurrent contact, which can prolong the residence time of particles. Furthermore, the atomized droplets obtained from pressure spraying are prone to merging and growing in the upper part, which is also detrimental to improving product particle uniformity and significantly reducing product particle size.

[0090] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. An apparatus for the preparation of stearic acid and stearic acid derivatives, characterized in that, The application relates to a reaction kettle, a main tower connected with the reaction kettle, nitrogen distributors located at the upper and lower parts of the main tower, a pressure atomizer located above the upper nitrogen distributor, a vaporizer connected with the upper and lower nitrogen distributors, a liquid nitrogen tank connected with the other end of the vaporizer, and the like.

2. A process for the preparation of stearic acid and stearic acid derivatives, characterized in that, The device is realized by the method of claim 1, comprising the following steps: 1) in the reaction kettle, stearic acid and stearic acid derivatives are put in, heated to melt, and continuously stirred; 2) the temperature is controlled to be 10-30 DEG C higher than the melting point of the stearic acid and stearic acid derivatives, meanwhile, the liquid is sent to the top of the tower by the pump, and is sprayed into mist droplets by the pressure atomizer; 3) the liquid nitrogen in the liquid nitrogen tank is obtained by the vaporizer, and then the ultra-low temperature nitrogen is introduced into the main tower by the upper and lower nitrogen distributors in a pulse mode, the pulse feeding time is upper: lower = 1-5s: 5-50s, and the ultra-low temperature nitrogen is tangentially introduced into the nitrogen distributor by cyclone; 4) the mist droplets of the stearic acid and stearic acid derivatives are rapidly solidified after contacting with the ultra-low temperature nitrogen cold wind, and are cooled to be finished products and discharged from the bottom discharge port of the main tower; 5) the wind temperature is increased after the nitrogen cold wind contacts with the droplet group, and the waste gas is extracted by the induced draft fan, and the micro powder in the waste gas is recycled by the bag dust collector.

3. The method of claim 2, wherein, The stearic acid and stearic acid derivatives include any one of stearic acid, stearic acid monoglyceride, stearic acid triglyceride and stearic acid zinc.

4. The method of claim 2, wherein, The prepared product particles are between 200-1000 meshes, and the finished product rate is greater than 97%.

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