Process for producing sulfamic acid by solid-phase dilution method

Abstract

The invention discloses a process for producing sulfamic acid by a solid-phase dilution method. The invention relates to a sulfamic acid production process by a solid phase dilution method. The process comprises the following steps: S1, preparing a pre-reaction material with the sulfuric acid concentration of 105.5%; s2, adding the pre-reaction material and urea into a pre-sulfonation reactor for reaction, enabling reaction liquid to overflow into the sulfonation reactor, and performing sulfonation reaction to obtain a liquid mixture; s3, carrying out immobilization on the liquid mixture through speed-adjustable centrifugal anti-spiral immobilization equipment, and feeding an obtained immobilization material into a dilution kettle; s4, adding mother liquor into the dilution kettle to dilute and adjust the viscosity of the material; and S5, performing solid-liquid separation on the liquid material with the adjusted viscosity to obtain a sulfamic acid crude product and dilute sulphuric acid, and performing crystallization purification on the sulfamic acid crude product to obtain sulfamic acid. The sulfamic acid production process is improved, excessive fuming sulphuric acid entering the dilution process in the reaction process is remarkably reduced, the generation of a new byproduct dilute sulphuric acid is reduced, and the production cost is reduced.

Description

Technical Field:

[0001] The present invention relates to the technical field of sulfamic acid, and particularly to a production process of sulfamic acid by a solid-phase dilution method. Background Art:

[0002] Currently, the production process of sulfamic acid generally adopts a high-temperature liquid-phase continuous method, using 105.5% fuming sulfuric acid (free SO3 25%) and urea as raw materials to carry out a sulfonation reaction to produce sulfamic acid products and by-product 55% dilute sulfuric acid. The high-temperature liquid-phase continuous method for producing sulfamic acid has the following disadvantages:

[0003] 1. For every 1 ton of sulfamic acid produced by the existing process, approximately 2.31 tons of 55% sulfuric acid is by-produced. The amount of by-product dilute sulfuric acid is large and difficult to dispose of. If the dilute sulfuric acid cannot be disposed of in time, the continuous production and capacity utilization of sulfamic acid will be restricted.

[0004] 2. The existing process uses 105.5% fuming sulfuric acid (free SO3 25%) to produce sulfamic acid. To produce 1 ton of sulfamic acid products, 2.31 tons of 105.5% fuming sulfuric acid is consumed. The consumption of fuming sulfuric acid is large, and the market price of fuming sulfuric acid is high, resulting in high production costs.

[0005] 3. The more the amount of by-product dilute sulfuric acid, the more the amount of sulfamic acid dissolved and carried away in the dilute sulfuric acid, and the lower the product yield.

[0006] There is an urgent need to propose a new production process to solve the above problems. Summary of the Invention:

[0007] The present invention solves the problems of large amounts of 55% concentrated dilute sulfuric acid by-products and large consumption of fuming sulfuric acid existing in the prior art in the production of sulfamic acid, and provides a production process of sulfamic acid by a solid-phase dilution method. The production process of sulfamic acid is improved by adding a solid-phase process between the sulfonation reaction and the dilution process. After solid-phase formation, the material is then subjected to a dilution process, significantly reducing the excess fuming sulfuric acid in the reaction process from entering the dilution process, reducing the emergence of new by-product dilute sulfuric acid, and reducing production costs.

[0008] The purpose of the present invention is to provide a production process of sulfamic acid by a solid-phase dilution method, including the following steps:

[0009] S1. Prepare a pre-reaction material with a sulfuric acid concentration of 105.5% using 107% fuming sulfuric acid;

[0010] S2. Add the pre-reaction material obtained in step S1 and urea into a pre-sulfonation reactor, carry out a pre-sulfonation reaction, and then the reaction liquid overflows into a sulfonation reactor to continue the sulfonation reaction. The total time of the pre-sulfonation reaction and the sulfonation reaction is 12 - 15h to obtain a liquid mixture;

[0011] S3. Solidify the liquid mixture obtained after the reaction in S2 through an adjustable-speed centrifugal counter-helix solidification device. The solidification feed rate is ≤ 6 t / h, the difference between the inlet and outlet materials is ≤ 15 min, the operating pressure is slightly negative pressure of 70 - 80 kPa, and the operating temperature is 70°C - 80°C. The solidified material obtained is then sent to the dilution kettle.

[0012] S4. During the initial adjustment, add mother liquor to the dilution kettle and gradually dilute and adjust the viscosity of the material to 20 - 30 cP and the density to 1.5 - 1.6 g / cm 3 . During the subsequent adjustment process, gradually add the liquid dilute sulfuric acid after the first filtration to replace a part of the mother liquor for adjustment in the dilution kettle.

[0013] S5. The liquid material with the adjusted viscosity in the dilution kettle is subjected to solid-liquid separation to obtain crude sulfamic acid and dilute sulfuric acid. The crude sulfamic acid is purified by crystallization and dried to obtain sulfamic acid.

[0014] Preferably, the adjustable-speed centrifugal counter-helix solidification device uses a horizontal double-rotation structure, and the double-rotation mechanism is in an independently adjustable-speed form; the liquid material feeds from the inner central cylinder, and the high-speed rotation of the outer drum drives the liquid material to perform rotational centrifugal dispersion in the outer drum. The higher-density material is subjected to a greater centrifugal force and is preferentially thrown and concentrated on the inner wall of the outer drum. The lower-density material will gradually be squeezed away from the inner wall and tend to the center of the drum, resulting in the enrichment of solid phase on the inner wall side of the drum. The reverse hollow-tooth spiral blade spiral device in the drum mechanically conveys the solid-phase substance enriched on the inner side of the outer drum in the reverse direction to the solid-phase discharge port at the feed end, and the liquid phase is discharged from the liquid-phase discharge port at the tail end along the feed direction to achieve the solidification of the material.

[0015] The adjustable-speed centrifugal counter-helix solidification device separates the materials initially based on the principle that the centrifugal force F = mω 2 r is different. In the formula: F is the centrifugal force received by the object, m is the mass of the object, ω is the angular velocity of the object, and r is the radius of the circular motion of the object. Different substances per unit volume have different masses m due to the difference in density ρ. When performing circular motion, the higher-density substance is subjected to a greater centrifugal force F, and the lower-density substance is subjected to a smaller centrifugal force. The substance with a greater force will be thrown to a position farther from the center of the circle first.

[0016] The operating electrical signal of the solidification device is connected to the DCS system after data transformation, and the centrifugal speed is automatically matched and adjusted according to the material flow rate, storage tank liquid level, reaction temperature, operating pressure, etc., so as to achieve the best solidification effect.

[0017] In the original production process of aminosulfonic acid, the mixed solution of fuming sulfuric acid and aminosulfonic acid remaining after the reaction is in the liquid phase in the reactor. The liquid-phase material overflows into the dilution kettle in the next process, i.e., the dilution process. In the dilution process, mother liquor is added to the dilution kettle to adjust the sulfuric acid concentration and the viscosity of the material in the liquid-phase material. All the fuming sulfuric acid remaining in the reaction process enters the dilution process and is adjusted to dilute sulfuric acid with a concentration of about 55% by adding mother liquor. All the remaining fuming sulfuric acid is converted into a new by-product, dilute sulfuric acid.

[0018] In the production process of aminosulfonic acid by the solid-phase dilution method proposed by the present invention, a solid-phase process is added between the two processes of sulfonation reaction and dilution process. The liquid-phase material overflowing from the reactor is solidified by using the adjustable-speed centrifugal anti-helical solidification equipment proposed by the present invention. The material after solidification is transported to the dilution kettle in the next process, i.e., the dilution process, significantly reducing the entry of the remaining fuming sulfuric acid in the reaction process into the dilution process and reducing the appearance of new by-product dilute sulfuric acid. In the dilution process, dilute sulfuric acid is additionally added to the dilution kettle for re-liquefaction of the solid-phase material. After adjusting the viscosity of the material in the dilution kettle, it enters the next process, primary filtration. The dilute sulfuric acid filtered out is recycled in the dilution process.

[0019] Preferably, in step S1, the mixed solution of fuming sulfuric acid and aminosulfonic acid obtained in the solidification process of step S3 is used to prepare a pre-reaction material with a sulfuric acid concentration of 105.5% by compounding with fuming sulfuric acid with a sulfuric acid concentration of 107%.

[0020] During the solidification process of the liquid-phase material overflowing from the sulfonation reactor, the remaining fuming sulfuric acid is simultaneously made into a mixed solution of fuming sulfuric acid and aminosulfonic acid. The mixed solution is then compounded with fuming sulfuric acid with a concentration of more than 107% to form a pre-reaction material with a sulfuric acid concentration of 105.5% and enters the pre-reactor, realizing the recycling of fuming sulfuric acid.

[0021] Preferably, in step S2, the mass ratio of the pre-reaction material to urea is 6.0 - 6.4:1.

[0022] Preferably, in step S2, the reaction temperature of the pre-sulfonation reaction is 59°C - 65°C, the reaction time is 5 - 7h, the reaction temperature of the sulfonation reaction is 70°C - 80°C, and the reaction time is 7 - 9h.

[0023] The solidification device converts the mixed material of aminosulfonic acid and fuming sulfuric acid overflowing from the sulfonation reactor from the liquid state to the solid state. The sulfuric acid content in the solidified material obtained in step S3 is more than 30% lower than that in the solidified material obtained by the traditional method.

[0024] Preferably, the dilute sulfuric acid obtained in step S5 can enter the dilution kettle in step S4 for stepwise dilution to adjust the viscosity of the material. The present invention changes the original dilution process that only uses mother liquor for dilution, and instead recycles the dilute sulfuric acid from the original primary filtration to adjust the viscosity of the material in the dilution kettle, controlling the physical properties of the material before primary filtration to remain unchanged. During the solidification of the liquid-phase material overflowing from the sulfonation reactor, the excess fuming sulfuric acid is simultaneously made into a mixed solution of fuming sulfuric acid and sulfamic acid. The mixed solution is then compounded with fuming sulfuric acid with a concentration of more than 107% to form a pre-reaction material with a sulfuric acid concentration of 105.5% and enters the pre-reactor, controlling the sulfuric acid concentration of the pre-reaction material entering the pre-reactor in the original production process to remain unchanged.

[0025] Preferably, the specific steps for the crystallization and purification of crude sulfamic acid in step S5 are as follows: after the crude sulfamic acid is dissolved, mother liquor is added and heated to a temperature of ~75 °C to obtain a sulfamic acid solution by dissolution. Then, it is cooled and crystallized. After the material temperature drops below 30 °C, solid-liquid separation is carried out to obtain high-quality sulfamic acid and mother liquor.

[0026] Preferably, the mother liquor added in step S4 or S5 comes from the mother liquor obtained after the crystallization and purification of crude sulfamic acid.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The solid-phase dilute acid dilution method for sulfamic acid production process proposed by the present invention adds a solid-phase chemical process on the basis of the existing sulfamic acid production process, changes the composition and state of the material entering the next process, converts the material that originally overflows from the liquid phase of the sulfonation reactor to the dilution kettle from the liquid phase to the solid phase and then sends it to the dilution kettle, and additionally circulates and adds the dilute sulfuric acid from the primary filtration process into the dilution kettle to adjust the viscosity of the material. During the solidification of the liquid-phase material overflowing from the reactor, the excess fuming sulfuric acid is simultaneously made into a mixed solution of fuming sulfuric acid and sulfamic acid. The mixed solution is then compounded with fuming sulfuric acid with a concentration of more than 107% to form a pre-reaction material with a sulfuric acid concentration of 105.5% and enters the pre-reactor, realizing the recycling of fuming sulfuric acid.

[0029] 2. The solid-phase dilution method for sulfamic acid production process proposed by the present invention significantly reduces the output of by-product dilute sulfuric acid. The excess fuming sulfuric acid in the reaction process fails to fully enter the dilution process, effectively reducing the emergence of new by-product dilute sulfuric acid. The output of dilute sulfuric acid can be reduced by more than 30%. Reducing the output of dilute sulfuric acid alleviates the difficulty of disposing of dilute acid, and well solves the problem that restricts the continuous production and capacity utilization of the sulfamic acid production device. At the same time, it also reduces the sulfamic acid carried away by the dissolution of dilute sulfuric acid due to the reduction of by-product dilute sulfuric acid, improving the product recovery rate.

[0030] 3. The solid-phase dilution process for producing sulfamic acid proposed by the present invention reduces the consumption of fuming sulfuric acid. Using 107% fuming sulfuric acid ((free SO3 30%)) as the raw material, compared with using 105.5% fuming sulfuric acid (free SO3 25%) as the raw material, more than 30% of fuming sulfuric acid can be saved per ton of sulfamic acid produced, and the reduction of raw material consumption effectively reduces the production cost.

[0031] 4. The sulfamic acid production process proposed by the present invention has significant changes compared with the original production process, and the environmental protection and economic benefits are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS:

[0032] Figure 1 It is a schematic structural diagram of an adjustable-speed centrifugal anti-helical solidification device;

[0033] MARKING DESCRIPTION: 1. Inner central cylinder; 2. Outer drum; 3. Helical blade; 4. Solid-phase discharge port; 5. Liquid-phase discharge port. DETAILED DESCRIPTION OF THE INVENTION:

[0034] The following examples are further illustrations of the present invention rather than limitations thereof.

[0035] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. Unless otherwise specified, the experimental materials and reagents in this article are all conventional commercially available products in this technical field. The adjustable-speed centrifugal anti-helical solidification device proposed by the present invention is purchased from Jiangsu Qingfeng Environmental Protection Technology Co., Ltd., and the product number is ZHW550.

[0036] As Figure 1 shown, the adjustable-speed centrifugal anti-helical solidification device uses a horizontal double-rotation structure, and the double-rotation mechanism is an independently adjustable-speed form; the liquid material is fed from the inner central cylinder 1, and the high-speed rotation of the outer drum 2 drives the liquid material to do rotational centrifugal dispersion in the outer drum. The materials with high density are subjected to greater centrifugal force and are preferentially thrown towards the inner wall of the outer drum to concentrate. The materials with low density will be gradually squeezed away from the inner wall and tend to the center of the drum, resulting in the enrichment of solid phase on the inner wall side of the drum. The reverse hollow-toothed helical blade 3 in the drum mechanically conveys the solid-phase substances enriched on the inner side of the outer drum in the reverse direction to the solid-phase discharge port 4 at the feeding end, and the liquid phase is discharged from the liquid-phase discharge port 5 at the tail end along the feeding direction, realizing the solidification of the material. At the same time, the rotation speeds of the outer drum and the reverse hollow-toothed helical blade can be adjusted to adjust the solidification effect.

[0037] Example 1

[0038] A solid-phase dilution process for producing sulfamic acid, comprising the following steps:

[0039] S1. 107% oleum (free SO3 content: 30%) from the outer pipe is compounded with the liquid oleum and sulfamic acid mixed solution simultaneously prepared during the solidification process in step S3 to obtain a pre-reaction material with a sulfuric acid concentration of 105.5% (free SO3 content: 20%).

[0040] S2. The pre-reaction material with a sulfuric acid concentration of 105.5% (free SO3 content: 20%) obtained by compounding and urea are continuously added into the first reaction kettle in a mass ratio of 6.2:1 for pre-sulfonation reaction. The temperature of the materials in the reaction kettle is controlled at 61°C. After the materials are pre-reacted in the first reaction kettle for 6 h, the reaction liquid overflows into the second reaction kettle for continuous sulfonation reaction. The reaction temperature is maintained at 75°C, and the residence time of the materials is controlled at 7 h to achieve complete sulfonation reaction. The generated CO2 and a small amount of escaped SO3 are removed of acid mist through an electric demister and then discharged up to the standard.

[0041] S3. The surplus oleum and sulfamic acid liquid mixture after the reaction overflows to a speed-adjustable centrifugal reverse spiral solidification device for solidification. The solidification feed rate ≤ 6 t / h, the time difference between feeding and discharging ≤ 15 min, the operating pressure is slightly negative pressure of 75 kPa, and the operating temperature is 75°C. It is transformed from the liquid phase to the solid phase and then sent to the dilution kettle in a mechanical transmission manner. During the solidification process, the surplus oleum is simultaneously made into a mixed solution of oleum and sulfamic acid, generating a by-product mixed solution, which is compounded with the 107% sulfuric acid concentration oleum from the outer pipe into a pre-reaction material with a sulfuric acid concentration of 105.5% and sent to the first reaction kettle by an oleum feed pump to react with urea for sulfonation reaction.

[0042] S4. The solidified materials sent to the dilution kettle in a mechanical transmission manner are added with mother liquor and the liquid dilute sulfuric acid filtered for the first time in step S5 in the dilution kettle to gradually dilute and adjust the viscosity of the materials to 20 - 30 cP and the density to 1.5 - 1.6 g / cm 3 , and mother liquor is added to the dilution kettle during the initial adjustment. During the subsequent adjustment process, the liquid dilute sulfuric acid filtered for the first time is gradually added to replace a part of the mother liquor for adjustment in the dilution kettle.

[0043] S5. The liquid materials with adjusted viscosity in the dilution kettle are transported to a vacuum belt filter by a crude product pump for primary separation to obtain crude sulfamic acid and dilute sulfuric acid with a sulfuric acid concentration of 55%. The crude sulfamic acid is sent to the dissolution process for dissolution, and the 55% dilute sulfuric acid is transported to a dilute acid storage tank as a by-product. The crude sulfamic acid is transported to a dissolution tank, added with mother liquor for heating and dissolution, and the dissolved sulfamic acid solution is transported to a crystallization kettle by a pump for cooling and crystallization.

[0044] After the temperature of the material in the crystallization kettle drops below 30°C, it is pumped to a vacuum belt filter for secondary separation to obtain high-quality sulfamic acid and mother liquor. The mother liquor enters the mother liquor tank and is recycled in the system. The high-quality sulfamic acid enters the drying process for drying and then is packaged and stored in the warehouse to obtain the sulfamic acid product.

[0045] Comparative Example 1

[0046] A solid-phase dilution process for producing sulfamic acid includes the following steps:

[0047] S1. Take sulfuric acid with a concentration of 105.5% (free SO3 content of 20%) as the pre-reaction material.

[0048] S2. Continuously add the pre-reaction material and urea to the first reaction kettle at a mass ratio of 6.2:1 for pre-sulfonation reaction. Control the temperature of the material in the reaction kettle at 61°C. After the material pre-reacts in the first reaction kettle for 6 hours, the reaction liquid overflows into the second reaction kettle for continuous sulfonation reaction. The reaction temperature is maintained at 75°C, and the residence time of the material is controlled at 7 hours to achieve complete sulfonation reaction. The generated CO2 and a small amount of escaped SO3 are removed from the acid mist through an electric demister and then discharged up to standard.

[0049] S3. The excess fuming sulfuric acid and liquid mixture of sulfamic acid after the reaction overflow into the dilution kettle, and mother liquor is added to gradually dilute in the dilution kettle to adjust the viscosity of the material to 20 - 30 cP and the density to 1.5 - 1.6 g / cm 3 .

[0050] S4. The liquid material with adjusted viscosity in the dilution kettle is pumped to a vacuum belt filter through a crude product pump for primary separation to obtain crude sulfamic acid and dilute sulfuric acid with a concentration of 55% sulfuric acid. The crude sulfamic acid is sent to the dissolution process for dissolution, and the 55% dilute sulfuric acid is sent to the dilute acid storage tank as a by-product. The crude sulfamic acid is transported to the dissolution tank, mother liquor is added for heating and dissolution, and the dissolved sulfamic acid solution is pumped to the crystallization kettle for cooling crystallization.

[0051] S5. After the temperature of the material in the crystallization kettle drops below 30°C, it is pumped to a vacuum belt filter for secondary separation to obtain high-quality sulfamic acid and mother liquor. The mother liquor enters the mother liquor tank and is recycled in the system. The high-quality sulfamic acid enters the drying process for drying and then is packaged and stored in the warehouse to obtain the sulfamic acid product.

[0052] Comparing Example 1 with Comparative Example 1, Example 1 reduces the consumption of fuming sulfuric acid by more than 30%, and at the same time reduces the by-product 55% dilute sulfuric acid by more than 30%. Also, due to the reduction of the by-product dilute sulfuric acid, the sulfamic acid carried away by the dissolution of dilute sulfuric acid is reduced, and the product recovery rate is increased from 93.5% to 94%.

[0053] Comparative Example 1 used 105.5% fuming sulfuric acid (free SO3 25%) to produce sulfamic acid. To produce 1 ton of sulfamic acid product, about 2.3 tons of 105.5% fuming sulfuric acid was consumed, and about 2.3 tons of dilute sulfuric acid with a concentration of 55% was produced as a by-product. Example 1 used fuming sulfuric acid with a higher sulfuric acid concentration of 107% (free SO3 30%) to produce sulfamic acid. To produce 1 ton of sulfamic acid product, about 1.6 tons of 107% fuming sulfuric acid was consumed, and about 1.6 tons of dilute sulfuric acid with a concentration of 55% was produced as a by-product. The yield of sulfamic acid could be increased by about 0.5%.

[0054] Example 2

[0055] Same as Example 1, the difference is that in step S2, the pre-reaction material and urea were continuously added into the first reaction kettle at a mass ratio of 6:1 for pre-sulfonation reaction. The temperature of the material in the reaction kettle was controlled at 59°C. After the material was pre-reacted in the first reaction kettle for 7 h, the reaction solution overflowed into the second reaction kettle for continuous sulfonation reaction. The reaction temperature was maintained at 75°C, and the residence time of the material was controlled at 6 h to achieve complete sulfonation reaction. In step S3, the operating pressure was slightly negative pressure of 70 kPa, and the operating temperature was 70°C.

[0056] Example 3

[0057] Same as Example 1, the difference is that in step S2, the pre-reaction material and urea were continuously added into the first reaction kettle at a mass ratio of 6.4:1 for pre-sulfonation reaction. The temperature of the material in the reaction kettle was controlled at 65°C. After the material was pre-reacted in the first reaction kettle for 5 h, the reaction solution overflowed into the second reaction kettle for continuous sulfonation reaction. The reaction temperature was maintained at 75°C, and the residence time of the material was controlled at 9 h to achieve complete sulfonation reaction. In step S3, the operating pressure was slightly negative pressure of 80 kPa, and the operating temperature was 80°C.

[0058] The descriptions of the above examples are only used to help understand the technical solution and its core idea of the present invention. It should be noted that for those skilled in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A production process of sulfamic acid by solid-phase dilution method, characterized in that, It includes the following steps: S1. Prepare a pre-reaction material with a sulfuric acid concentration of 105.5% using 107% fuming sulfuric acid; S2. Add the pre-reaction material obtained in step S1 and urea into a pre-sulfonation reactor. After pre-sulfonation reaction, the reaction liquid overflows into a sulfonation reactor and continues the sulfonation reaction. The total time of the pre-sulfonation reaction and the sulfonation reaction is 12 - 15 h to obtain a liquid mixture; S3. Solidify the liquid mixture obtained after the reaction in S2 through an adjustable-speed centrifugal reverse spiral solidification device. The solidification feeding amount ≤ 6 t / h, the time difference between feeding and discharging ≤ 15 min, the operating pressure is slightly negative pressure of 70 - 80 kPa, and the operating temperature is 70 °C - 80 °C. The obtained solidified material is then sent into a dilution kettle; S4. During initial adjustment, add mother liquor into the dilution kettle, gradually dilute and adjust the viscosity of the material to 20 - 30 cP, and the density to 1.5 - 1.6 g / cm 3 , and during subsequent adjustment, gradually add the liquid dilute sulfuric acid filtered once to replace a part of the mother liquor for adjustment in the dilution kettle; S5. The liquid material with adjusted viscosity in the dilution kettle undergoes solid-liquid separation to obtain crude sulfamic acid and dilute sulfuric acid. The crude sulfamic acid is purified by crystallization and dried to obtain sulfamic acid.

2. The solid-phase dilution method for producing sulfamic acid according to claim 1, wherein In step S1, use the fuming sulfuric acid and sulfamic acid mixed solution obtained during the solidification process in step S3 to compound with 107% fuming sulfuric acid to prepare a pre-reaction material with a sulfuric acid concentration of 105.5%.

3. The solid-phase dilution method for producing sulfamic acid according to claim 1, characterized in that, In step S2, the mass ratio of the pre-reaction material to urea is 6.0 - 6.4:

1.

4. The solid-phase dilution method for producing sulfamic acid according to claim 1, wherein In step S2, the reaction temperature of the pre-sulfonation reaction is 59 °C - 65 °C, and the reaction time is 5 - 7 h. The reaction temperature of the sulfonation reaction is 70 °C - 80 °C, and the reaction time is 7 - 9 h.

5. The solid-phase dilution method for producing sulfamic acid according to claim 1, characterized in that, The adjustable-speed centrifugal reverse spiral solidification device uses a horizontal double-rotation structure, and the double-rotation mechanism is an independently adjustable-speed form; the liquid material is fed from the inner central cylinder. The high-speed rotation of the outer drum drives the liquid material to do rotational centrifugal dispersion inside the outer drum. The material with a higher density is subjected to a greater centrifugal force and is preferentially thrown and concentrated on the inner wall of the outer drum. The material with a lower density will gradually be squeezed away from the inner wall and tend to the center of the drum, resulting in the enrichment of the solid phase on the inner wall side of the drum. The reverse hollow-tooth spiral blade spiral device inside the drum mechanically conveys the solid phase material enriched on the inner side of the outer drum in the reverse direction to the solid-phase discharge port at the feeding end, and the liquid phase is discharged from the liquid-phase discharge port at the tail end along the feeding direction to achieve the solidification of the material.

6. The solid-phase dilution method for producing sulfamic acid according to claim 1, characterized in that, The dilute sulfuric acid obtained in step S5 can enter the dilution kettle in step S4 to be gradually diluted to adjust the viscosity of the material.

7. The solid-phase dilution method for producing sulfamic acid according to claim 1, characterized in that, The specific steps for the crystallization purification of the crude sulfamic acid in step S5 are as follows: After the crude sulfamic acid is dissolved, add the mother liquor and heat it to a temperature of ~75 °C to dissolve and obtain a sulfamic acid solution, then perform cooling crystallization. After the material temperature drops below 30 °C, perform solid-liquid separation to obtain refined sulfamic acid and the mother liquor.

8. The solid-phase dilution method for producing sulfamic acid according to claim 1 or 7, characterized in that, The mother liquor added in step S4 or S5 comes from the mother liquor obtained after the crystallization purification of the crude sulfamic acid.

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