A kind of production method of instant sodium pyrophosphate

Abstract

The present invention provides a production method of instant sodium pyrophosphate, comprising the steps of neutralization, spray drying, polymerization, pre-hydration, cooling, and screening to obtain instant sodium pyrophosphate. Food phosphoric acid and soda ash are neutralized to obtain disodium hydrogen phosphate slurry, controlling the pH to 8.8-9.2 and the specific gravity to 1.4-1.5 g / ml; the neutralized slurry is transported to a pressure spray drying tower, and the tower bottom temperature is controlled to 120°C to 150°C; after drying, it enters a dynamic polymerization furnace, with a polymerization time of 30-40 min and a furnace tail temperature of 180°C to 210°C to obtain a semi-finished sodium pyrophosphate product. The semi-finished product passes through a cooling drum, and water mist is sprayed at the drum entrance for pre-hydration and cooling at the same time; the product is sieved to obtain instant sodium pyrophosphate.

Description

Technical Field

[0001] The invention relates to a production method of instant sodium pyrophosphate, in particular to the production of an instant sodium pyrophosphate product. Background Art

[0002] The solubility of sodium pyrophosphate in 100g of water at 20°C is 6.23g, and the pH of a 1% aqueous solution is approximately 10. In food processing, sodium pyrophosphate has a stronger ability to adjust the pH of meat tissue systems. Furthermore, pyrophosphate has an ATP-like effect, dissociating actomyosin into actin and myosin, which facilitates the extraction of salt-soluble proteins and improves water retention. Sodium pyrophosphate is the most efficient monomeric phosphate among phosphates for water retention. In meat and aquatic product processing, phosphates are often formulated into low-temperature curing solutions. Through soaking, tumbling, and injection, they gradually penetrate into muscle tissue and act on meat proteins. The solubility of sodium pyrophosphate, 6.23g, is half that of sodium tripolyphosphate, 13.5g. Conventional commercial sodium pyrophosphate contains over 96% sodium tripolyphosphate in a fine powder with a density of approximately 0.9. It tends to form lumps when dissolved at low temperatures, making it difficult to stir and dissolve, making it inconvenient to use. Application can also clog injection needles or leave small white phosphate clumps on the surface of food, affecting consumer taste. Another side effect of agglomeration is that the active ingredients are not completely dissolved, cannot fully exert their effects, and cannot achieve the desired effect; therefore, the poor solubility of conventional sodium pyrophosphate on the market limits its use, and it is necessary to develop instant sodium pyrophosphate.

[0003] Domestic patents are mostly focused on methods for producing sodium pyrophosphate using by-products or crude sodium pyrophosphate, disodium hydrogen phosphate and other industrial-grade raw materials. There are few studies on the production process of instant sodium pyrophosphate. Only patent CN104891466B uses a crystallization method to produce sodium pyrophosphate decahydrate, and then dries to obtain an anhydrous product. The process is relatively complicated and cannot be continuously industrialized. The present invention adopts a continuous phosphate production device to obtain a large-particle porous product through a special spray drying and polymerization process; pre-hydration and cooling are carried out on a cooling drum, and the product is directly sieved to remove the part above 40 mesh without being crushed, retaining a specific large particle shape. The obtained sodium pyrophosphate does not agglomerate when dissolved, and is completely dissolved within 3 minutes of stirring, with a fast dissolution rate. Summary of the Invention

[0004] The present invention provides the following technical solution: a production method of instant sodium pyrophosphate, comprising the following steps: neutralization, drying, polymerization, prehydration, cooling, screening, and packaging.

[0005] The neutralization process comprises mixing phosphoric acid, water and alkali and then heating the mixture to react to obtain a neutralized slurry of disodium hydrogen phosphate;

[0006] In some embodiments, 7000 L of 85% food phosphoric acid, water and 9.9 tons of sodium carbonate are added to a neutralization pot for reaction at a temperature of 90-100° C., and the end point is controlled to be a pH value of 8.9-9.2 and a specific gravity of 1.4-1.5 g / ml to obtain a disodium hydrogen phosphate slurry.

[0007] Preferably, the pH value during the neutralization process is controlled at 9.0-9.1.

[0008] The spray drying process is as follows: the neutralized slurry is pumped into a spray drying tower through a high-pressure pump, and anhydrous disodium hydrogen phosphate is obtained by pressure spray drying;

[0009] In some preferred embodiments, the disodium hydrogen phosphate liquid is pumped into a spray drying tower through a high-pressure pump, the tower bottom temperature is 120° C. to 150° C., and anhydrous disodium hydrogen phosphate is obtained by pressure spray drying.

[0010] Preferably, the spray drying tower adopts pressure spraying, and the spray nozzle is specially designed. The nozzle part includes a disc core, a distributor and a nozzle. Six diversion holes are set around the disc core disk; the distributor has a sealed top, a hollow structure inside, a single hole obliquely opened on the side, and an open bottom. The sealed top of the distributor is connected to the disc core, and the lower opening is connected to the nozzle. The nozzle is inclined at an angle of 30-45 degrees up and down. The liquid flows down through the small holes in the disc core in the spray gun, swirls through the small holes on the side of the distributor into the inside of the distributor, and then reaches the nozzle. The diameter of the diversion hole is 2.5-3.0mm; the aperture of the distributor opening is 1.5-2mm.

[0011] The nozzle significantly increases the volume of atomized droplets and the spray angle by reducing the number of diversion ports in the core of the flower disc while increasing the aperture; and by opening oblique holes on the side of the distributor, so that the dried sodium dihydrogen phosphate has a fluffy large particle structure.

[0012] More preferably, the spray drying tower adopts downstream drying, with a drying pressure of 4-6 MPa and a nozzle spray angle of 30-45 degrees. The bottom temperature of the spray drying tower is 120°C to 150°C.

[0013] The polymerization process involves feeding anhydrous sodium dihydrogen phosphate into a polymerization furnace, ensuring the temperature at the furnace tail is between 180°C and 210°C, and allowing the powder to react in the furnace for 30 to 40 minutes. The material exiting the polymerization furnace is sampled and the main content is determined to obtain crude sodium pyrophosphate.

[0014] Preferably, the polymerization process is carried out in a dynamic polymerization furnace, so that the polymerization is more complete and uniform.

[0015] The pre-hydration and cooling process: the semi-finished sodium pyrophosphate flows into the cooling drum at a high temperature, the atomizing nozzle at the head of the drum is turned on to spray water mist on the material, the water molecules on the surface of the material are pre-hydrated, and the material is turned over and cooled in the drum before flowing out;

[0016] In some embodiments, the high-temperature material (around 200°C) exiting the polymerization furnace flows into a cooling drum. A misting nozzle installed at the drum head sprays the material with water mist at a temperature of 30-50°C, with the spray volume accounting for 1-5% of the powder mass. The granular material absorbs the water, pre-hydrating it and gradually cooling it as the cooling drum rotates. The residence time on the cooling drum is 30 minutes.

[0017] The screening and packaging process involves passing the cooled sodium pyrophosphate through a 40-mesh sieve, ensuring that all of the sodium pyrophosphate passes through, and then packaging. The final product particle size is as follows: all of the sodium pyrophosphate passes through a 40-mesh sieve, ≥50% of the residue on a 60-mesh sieve, ≥60% of the residue on an 80-mesh sieve, and ≥70% of the residue on a 100-mesh sieve.

[0018] Preferably, the particle size of the final product is: 60 mesh sieve residue ≥40%, 80 mesh sieve residue ≥55%, 100 mesh sieve residue ≥80%.

[0019] Compared with the prior art, the present invention provides a method for producing large-particle instant sodium pyrophosphate, which has the following beneficial effects:

[0020] (1) The present invention changes the nozzle to obtain fluffy granular disodium hydrogen phosphate during the drying process. The sodium pyrophosphate obtained by subsequent polymerization also exhibits fluffy large particles with a porous structure. During dissolution, the sodium pyrophosphate particles have a larger specific surface area in contact with water, and there are more channels for water molecules to enter the particles, resulting in a faster dissolution rate. Compared with fine powder, the particle morphology is less prone to sticking and agglomeration, and the agglomeration problem is improved.

[0021] (2) Pre-hydration reduces the degree of agglomeration of sodium pyrophosphate. A small amount of anhydrous sodium pyrophosphate molecules pre-absorb water, forming a small amount of hydrated sodium pyrophosphate mixed with the product. Hydrated sodium pyrophosphate is easily soluble, which hinders the mutual adsorption and agglomeration caused by the large amount of heat released by anhydrous sodium pyrophosphate in water, thereby improving solubility.

[0022] (3) The present invention adopts a continuous phosphate production device, which has achieved large-scale continuous production. The process is easy to operate and has strong production guidance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a traditional nozzle, where 1' is the disc core, 2' is the distributor, and 3' is the nozzle.

[0024] Figure 2 The top view and front view of the traditional nozzle structure, where 1' is the disc core, 2' is the distributor, and 3' is the nozzle.

[0025] Figure 3 Schematic diagram of the nozzle structure of the present invention, wherein 1 is the disc core, 2 is the distributor, and 3 is the nozzle.

[0026] Figure 4 1 is a top view and a front view of the nozzle structure of the present invention, wherein 1 is the disc core, 2 is the distributor, and 3 is the nozzle.

[0027] Figure 5 The microstructure of the product particles obtained in Example 1 and Comparative Example 1, wherein a is Comparative Example 1 and b is Example 1.

[0028] Figure 6 These are the appearance pictures of the products obtained in Example 1, Comparative Example 1, and Comparative Example 2.

[0029] Figure 7 These are appearance pictures of the products obtained in Example 1, Comparative Example 1, and Comparative Example 2 after standing and agglomerating.

[0030] Figure 8 The residue after stirring the products obtained in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 for 3 minutes DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be described in detail below in conjunction with the embodiments of the present invention.

[0032] It should be noted that the following embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be determined by the claims. Any modifications or equivalent substitutions made by those skilled in the art without creative effort, provided that they fully understand the technical solution of the present invention, fall within the scope of protection of the present invention.

[0033] The nozzle part of the present application includes a flower disc core, a distributor and a nozzle. Six diversion holes are set around the flower disc core disc; the diameter of the diversion hole is 2.5mm; the top of the distributor is sealed, the interior is hollow, a single hole is obliquely opened on the side, and the bottom is open. The sealed top of the distributor is connected to the flower disc core, and the lower opening is connected to the nozzle. The nozzle is inclined at a 45-degree angle up and down. The liquid flows down through the small holes in the flower disc core in the spray gun, swirls through the small holes on the side of the distributor into the inside of the distributor, and then reaches the nozzle. The aperture of the distributor measuring hole is 2mm; if Figure 2 shown.

[0034] The nozzle part of the spray drying tower of the commonly used technology includes a flower disc core, which is equipped with 8 diversion holes, each with a diameter of 1.5mm, and is connected to the distributor; the distributor is a solid cylindrical shape with an oblique groove structure at the bottom, which is connected to the nozzle. The nozzle adopts a 45-degree angle up and down; Figure 1 shown.

[0035] Example 1

[0036] S1. Neutralization: Add 7000L of 85% food phosphoric acid, 9.9 tons of sodium carbonate and water into a neutralization pot for reaction at a temperature of 90-100°C. The end point is a pH value of 9.0-9.1 and a specific gravity of 1.4-1.5g / ml to obtain disodium hydrogen phosphate slurry.

[0037] S2. Spray drying: The neutralized slurry is pumped into the spray drying tower through a high-pressure pump. The pressure spray tower uses a special nozzle (such as Figure 3 、 4 As shown), the tower bottom temperature is 140°C to 150°C, and anhydrous disodium hydrogen phosphate particles are obtained.

[0038] S3. Polymerization: Anhydrous disodium hydrogen phosphate is fed into a dynamic polymerization furnace. The temperature at the end of the polymerization furnace is 200°C to 210°C. The materials react in the polymerization furnace for 30 minutes. Samples are taken from the end of the furnace and the main content is determined to be 96% or above to obtain semi-finished sodium pyrophosphate.

[0039] S4. Pre-hydration and cooling: The high-temperature material (200-210℃) at the tail of the furnace flows into the cooling drum. The atomizing nozzle at the head of the drum is turned on to spray water mist on the material. The water spray mass is 4% of the weight of the semi-finished sodium pyrophosphate. The water temperature is 30-50℃. The material absorbs water molecules to undergo local pre-hydration and flows out after cooling in the drum.

[0040] S5. Screening and packaging process: The cooled material is passed through a 40-mesh sieve and then packaged.

[0041] Fluidity test method: Weigh 3g of the sodium pyrophosphate prepared above and pour it into a beaker containing 100ml of distilled water (20℃). After standing for a period of time (3min), gently shake the beaker to observe the fluidity and use a glass rod to feel for lumps.

[0042] Dissolution rate test method: Add 100 mL of distilled water (20°C) to a beaker and stir on a magnetic stirrer. Weigh 3 g of sodium pyrophosphate and pour the sample into the beaker quickly in the form of quicksand while pressing the stopwatch. Record the residue after 3 minutes and the time it takes for the sample to be completely dissolved.

[0043] Final product determination: main content is 96.8%, pH 10.2; the product has the appearance of large particles ( Figure 6 ), microporous structure ( Figure 5 The residue on 60 mesh sieve is 54%, the residue on 80 mesh sieve is 69%, the residue on 100 mesh sieve is 83%, and the apparent density is 0.49 g / ml.

[0044] from Figure 5 It can be seen that the sodium pyrophosphate particles obtained in Example 1 have a larger particle size, more pores on the surface, and are more fluffy inside. The specific surface area in contact with water during dissolution is larger, and the dissolution speed is faster.

[0045] from Figure 6It can be seen from the figure that the material particles obtained by using the special nozzle in Example 1 are the largest, the particles obtained by using the conventional nozzle are second, and the material crushed by using the conventional nozzle is the most powdery.

[0046] The product has good fluidity and does not agglomerate when placed in water ( Figure 7 ); dissolves quickly and dissolves completely after stirring for 3 minutes. ( Figure 8 ).

[0047] Example 2

[0048] The amount of water mist sprayed in step S4 of Example 1 was changed to 2% of the weight of the crude sodium pyrophosphate, and the rest remained unchanged;

[0049] Final product analysis revealed a main content of 96.8%, a pH of 10.2, and a large, microporous structure. The product had a 60-mesh sieve residue of 54%, an 80-mesh sieve residue of 69%, and a 100-mesh sieve residue of 83%. The apparent density was 0.49 g / ml.

[0050] The solubility of the final product was measured: the product had good fluidity and did not clump when placed in water; it dissolved quickly and was completely dissolved after stirring for 4 minutes.

[0051] Comparative Example 1

[0052] The pressure spray in step S2 of Example 1 was carried out using a conventional nozzle ( Figure 1 、 2 ), the rest remain unchanged.

[0053] Product Measurement: The product particle size is smaller than that of the example, with a 60-mesh sieve residue of 14%, an 80-mesh sieve residue of 30%, and a 100-mesh sieve residue of 43%. The apparent density is 0.65 g / ml. The product partially clumps when left standing in water, but complete dissolution requires stirring for 7 minutes.

[0054] Comparative Example 2

[0055] S1. Neutralization: Add 7000L of 85% food phosphoric acid, water and 9.9 tons of sodium carbonate into a neutralization pot for reaction at a temperature of 90-100°C. Control the end point to a pH of 9-9.1 and a specific gravity of 1.4-1.5g / ml to obtain disodium hydrogen phosphate slurry.

[0056] S2, spray drying: the neutralized slurry is pumped into the spray drying tower through a high-pressure pump, and a conventional spray nozzle ( Figure 1 、 2 ), the tower bottom temperature is 140℃~150℃, and anhydrous disodium hydrogen phosphate powder is obtained.

[0057] S3. Polymerization: Feed the anhydrous disodium hydrogen phosphate powder into a dynamic polymerization furnace. The temperature at the end of the polymerization furnace is 200°C to 210°C. The powder reacts in the polymerization furnace for 30 minutes. Samples are taken from the end of the furnace and the main content is determined to be qualified, thereby obtaining the semi-finished sodium pyrophosphate.

[0058] S4. Pre-hydration cooling: The high-temperature material at the tail of the furnace flows into the cooling drum. The atomizing nozzle at the head of the drum is turned on to spray water mist on the material. The water spray mass is 2% of the weight of the crude product. The material absorbs water molecules to be pre-hydrated, and then flows out after cooling in the drum.

[0059] S5. After cooling, the material is crushed in a pulverizer to obtain conventional commercial sodium pyrophosphate powder with a density of 0.9 g / ml, which is passed through a 40-mesh sieve and then packaged.

[0060] Product analysis: Main content: 96.8%, pH: 10.2; Particle size: 7% on 60-mesh sieve, 13% on 80-mesh sieve, 20% on 100-mesh sieve. Apparent density: 0.9 g / ml.

[0061] Solubility test of the final product: It forms serious lumps when left standing in water and requires stirring for 12 minutes to completely dissolve.

[0062] Comparative Example 3

[0063] In Example 1, S4 is changed to be only cooled: the high-temperature material at the furnace tail flows into the cooling drum, is cooled in the drum, and then flows out. The rest remains unchanged.

[0064] Final product analysis revealed a particle size of 54% sodium pyrophosphate on a 60-mesh sieve, 69% on an 80-mesh sieve, and 83% on a 100-mesh sieve. The apparent density was 0.49 g / ml. The product dissolved rapidly in water, exhibiting minimal lumps upon standing. The product was completely dissolved in 4.5 minutes.

[0065]

[0066] from Figure 7 It can be seen that Example 1 has no caking, the bottom material is in the form of quicksand, is uniform and smooth, and has the best fluidity; Comparative Example 1 has a small amount of caking locally; Comparative Example 2 has a large amount of caking.

[0067] from Figure 8 It can be seen that after stirring for 3 minutes, Example 1 was completely dissolved; a very small amount of Example 2 was not dissolved, a large amount of Comparative Example 1 was not dissolved, and a large amount of Comparative Example 2 was not dissolved and agglomerated.

[0068] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for producing instant sodium pyrophosphate, characterized in that: The following steps are involved: S1. Neutralization: mixing phosphoric acid, water and alkali and heating the mixture to obtain a neutralized slurry of disodium hydrogen phosphate; S2, spray drying: the neutralized slurry is pumped into a spray drying tower through a high-pressure pump, and anhydrous disodium hydrogen phosphate is obtained by pressure spray drying. The nozzle part of the spray drying tower for spraying includes a disc core, a distributor and a nozzle; six guide holes with a diameter of 2.5-3.0 mm are set around the disc of the disc core; the distributor has a sealed top, a hollow structure inside, a single hole obliquely opened on the side, and an open bottom; the sealed top of the distributor is connected to the disc core, and the open bottom is connected to the nozzle, and the nozzle is inclined at 30-45 degrees from top to bottom; S3, polymerization: anhydrous disodium hydrogen phosphate is subjected to polymerization reaction to obtain semi-finished sodium pyrophosphate; S4, pre-hydration and cooling: The semi-finished sodium pyrophosphate flows into the cooling drum at high temperature, and the atomizing nozzle at the head of the drum is turned on to spray water mist on the material, so that the water molecules on the surface of the material are pre-hydrated, and the material is turned over and cooled in the drum before flowing out; S5. Screening and packaging process: The cooled material is passed through a 40-mesh sieve and then packaged.

2. The production method of instant sodium pyrophosphate according to claim 1, wherein In step S1, the reaction temperature is 90-100° C., the pH value of the neutralization solution is controlled to be 8.8-9.2, and the specific gravity is 1.4-1.5 g / ml.

3. The production method of instant sodium pyrophosphate according to claim 1, wherein In step S2, the spray drying tower has a bottom temperature of 120°C to 150°C.

4. The production method of instant sodium pyrophosphate according to claim 1, wherein The diameter of the single hole on the side of the distributor is 1.5-2 mm; the spray drying pressure is 4-6 MPa, and the nozzle spray angle is 30-45 degrees.

5. The production method of instant sodium pyrophosphate according to claim 1, wherein In step S3, the polymerization reaction temperature is 180° C. to 210° C., and the polymerization reaction time is 30 to 40 minutes.

6. The production method of instant sodium pyrophosphate according to claim 1, wherein The water mist temperature in step S4 is 30-50° C., the mass of the spray is 1-5% of the mass of the semi-finished sodium pyrophosphate, and the residence time in the cooling drum is maintained at 30 minutes.

7. The method for producing instant sodium pyrophosphate according to any one of claims 1 to 6, wherein The particle size of instant sodium pyrophosphate is: all pass through the standard 40-mesh sieve, the residue on the 60-mesh sieve is ≥40%, the residue on the 80-mesh sieve is ≥55%, and the residue on the 100-mesh sieve is ≥70%; it becomes quicksand after dissolution.

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