Method for preparing sodium hydrogen sulfite and utilizing byproduct

Abstract

The invention relates to the technical field of sodium hydrogen sulfite production, in particular to a sodium hydrogen sulfite preparation and byproduct utilization method which comprises the following steps: S1, incineration; s2, absorption; s3, removing impurities; s4, adsorption; s5, filtering; s6, evaporation and concentration; s7, centrifugal drying; and S8, circulating by-products. According to the method, the centrifugal mother liquor is returned to the neutralization process, so that the cyclic utilization of byproducts is realized, the emission of wastes is reduced, the treatment cost is reduced, the utilization rate of resources is increased, the production efficiency, the product quality and the energy utilization efficiency are remarkably improved, the production cost and the environmental pollution are reduced, and the method has remarkable economic and social benefits and is worthy of popularization. And an efficient, environment-friendly and sustainable solution is provided for industrial production of sodium hydrogen sulfite.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium bisulfite production, and specifically provides a method for preparing sodium bisulfite and utilizing by-products. Background Art

[0002] Sodium bisulfite is an important chemical raw material, widely used in industries such as food, pharmaceuticals, textiles, and papermaking. In the food industry, it is used as an antioxidant and preservative; in the pharmaceutical field, it is used to synthesize certain drug intermediates; in the textile and papermaking industries, it serves as a bleaching agent and reducing agent. With the continuous development of these industries, the demand for sodium bisulfite is also increasing continuously.

[0003] During the preparation process of sodium bisulfite, a certain amount of by-products, such as sodium sulfite solution, will be generated. How to effectively treat these by-products and achieve the recycling of resources is the key to improving the economy and sustainability of the entire process. Traditional methods for treating by-products are often simple and crude, resulting in resource waste and increased environmental pressure. Therefore, developing a method that can effectively recover and utilize by-products is of great significance for realizing green chemical production. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing sodium bisulfite and utilizing by-products to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A method for preparing sodium bisulfite and utilizing by-products, comprising the following steps:

[0006] S1. Incineration: The sulfur-containing tail gas generated during the production of dimethyl sulfoxide is transported to an incineration device and thermally incinerated at 600 - 800 °C to obtain a raw gas mainly composed of sulfur dioxide;

[0007] S2. Absorption: The raw gas is transported to an absorption tower, the temperature of the absorption tower is controlled at 25 - 40 °C, a sodium hydroxide solution with a mass concentration of 10% - 15% is used as the main absorption liquid, and a dilute sulfuric acid with a mass concentration of 3% - 5% is used as an auxiliary for pH adjustment. The pH value of the system is precisely controlled within the range of 4.0 - 5.0 through on-line pH monitoring, and finally a sodium bisulfite absorption liquid with a mass concentration of 15% - 40% is obtained;

[0008] S3. Impurity Removal: The sodium bisulfite absorption liquid is pumped into an ion exchange column loaded with strongly acidic cation exchange resin to remove metal ion impurities and obtain a purified liquid;

[0009] S4. Adsorption: The purified liquid is transferred to a neutralization kettle, an activated carbon adsorbent is added, and mechanical stirring is maintained for 30 - 60 min to obtain a sodium bisulfite suspension;

[0010] S5. Filtration: Filter the sodium bisulfite suspension through a plate and frame filter press, collect the filtered clear liquid to obtain a purified sodium bisulfite solution;

[0011] S6. Evaporation and concentration: Transport the purified sodium bisulfite solution to a single-effect evaporator for vacuum concentration, control the concentration temperature at 40 - 60 °C and the vacuum degree at 0.08 - 0.10 MPa to obtain a supersaturated sodium bisulfite mixture;

[0012] S7. Centrifugal drying: Separate the supersaturated sodium bisulfite mixture through a centrifuge, and vacuum-dry the obtained solid at 60 - 80 °C to obtain sodium bisulfite. Collect and recycle the centrifugal mother liquor as a by-product;

[0013] S8. By-product recycling: Return the mother liquor obtained in S7 to the neutralization process in S4, mix it with fresh purified liquid to participate in the neutralization reaction, and realize the utilization of by-products.

[0014] Optionally, the strongly acidic cation exchange resin is 15 ion exchange resin.

[0015] Optionally, the activated carbon adsorbent is columnar activated carbon, and the specific surface area of the activated carbon adsorbent ≥ 1200 m 2 / g.

[0016] Optionally, the addition amount of the activated carbon adsorbent is 1% - 5% of the mass of the purified liquid.

[0017] Optionally, the filtration accuracy of the plate and frame filter press is 0.45 μm.

[0018] Optionally, the density of the supersaturated sodium bisulfite mixture is 1.28 - 1.32 g / cm 3 .

[0019] Optionally, use a heat exchanger to recover the thermal energy of the raw material gas. The heat exchanger reduces the temperature of the raw material gas to 180 - 195 °C, and the recovered thermal energy provides heat source for the single-effect evaporator.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention returns the centrifugal mother liquor to the neutralization process, realizes the recycling of by-products, reduces the discharge of waste, lowers the treatment cost, improves the resource utilization rate, significantly improves the production efficiency, product quality and energy utilization efficiency, reduces the production cost and environmental pollution at the same time, has significant economic and social benefits, and provides an efficient, environmentally friendly and sustainable solution for the industrial production of sodium bisulfite;

[0022] 2. The present invention effectively treats sulfur-containing tail gas through an incineration and absorption process, reduces the emission of harmful gases such as sulfur dioxide, meets strict environmental protection requirements. By using a heat exchanger, the heat energy of the high-temperature raw gas generated by incineration is recovered, and the recovered heat energy is used for a single-effect evaporator, significantly improving the energy utilization efficiency. This not only reduces the dependence on external energy, lowers production costs, but also reduces carbon emissions and improves the sustainability of the process. Detailed implementation manners

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] Embodiment 1: The present invention provides a method for preparing sodium bisulfite and utilizing by-products, including the following steps:

[0025] S1. Incineration: The sulfur-containing tail gas generated during the production of dimethyl sulfoxide is transported to an incineration device and thermally incinerated at 600 °C to obtain a raw gas mainly composed of sulfur dioxide.

[0026] S2. Absorption: The raw gas is transported to an absorption tower. The temperature of the absorption tower is controlled at 25 °C. A sodium hydroxide solution with a mass concentration of 10% is used as the main absorption liquid, and a dilute sulfuric acid with a mass concentration of 3% is used as an auxiliary for pH adjustment. The pH value of the system is precisely controlled at 4.0 through on-line pH monitoring, and finally a sodium bisulfite absorption liquid with a mass concentration of 15% is obtained.

[0027] S3. Impurity removal: The sodium bisulfite absorption liquid is pumped into an ion exchange column loaded with strongly acidic cation exchange resin to remove metal ion impurities and obtain a purified liquid.

[0028] S4. Adsorption: The purified liquid is transferred to a neutralization kettle, activated carbon adsorbent is added, and mechanical stirring is maintained for 30 min to obtain a sodium bisulfite suspension.

[0029] S5. Filtration: The sodium bisulfite suspension is filtered through a plate and frame filter press, and the filtered clear liquid is collected to obtain a purified sodium bisulfite liquid.

[0030] S6. Evaporation and concentration: The purified sodium bisulfite liquid is transported to a single-effect evaporator for vacuum concentration. The concentration temperature is controlled at 40 °C and the vacuum degree is 0.08 MPa to obtain a supersaturated sodium bisulfite mixture.

[0031] S7. Centrifugal drying: The supersaturated sodium bisulfite mixture is separated by a centrifuge, and the obtained solid is dried under vacuum at 60 °C to obtain sodium bisulfite. The centrifugal mother liquor is collected as a by-product and recycled;

[0032] S8. By-product recycling: The mother liquor obtained in S7 is returned to the neutralization process in S4 and mixed with fresh purified liquid to participate in the neutralization reaction, realizing the utilization of by-products.

[0033] Example 2: The present invention provides a method for preparing sodium bisulfite and utilizing by-products, including the following steps:

[0034] S1. Incineration: The sulfur-containing tail gas generated in the production process of dimethyl sulfoxide is transported to an incineration device and thermally incinerated at 680 °C to obtain a raw material gas mainly composed of sulfur dioxide;

[0035] S2. Absorption: The raw material gas is transported to an absorption tower. The temperature of the absorption tower is controlled at 30 °C. A sodium hydroxide solution with a mass concentration of 12% is used as the main absorption liquid, and a dilute sulfuric acid with a mass concentration of 3.5% is supplemented for pH adjustment. The pH value of the system is precisely controlled at 4.2 through on-line pH monitoring, and finally a sodium bisulfite absorption liquid with a mass concentration of 24% is obtained;

[0036] S3. Impurity removal: The sodium bisulfite absorption liquid is pumped into an ion exchange column loaded with strongly acidic cation exchange resin to remove metal ion impurities and obtain a purified liquid;

[0037] S4. Adsorption: The purified liquid is transferred to a neutralization kettle, and an activated carbon adsorbent is added, and mechanical stirring is maintained for 40 min to obtain a sodium bisulfite suspension;

[0038] S5. Filtration: The sodium bisulfite suspension is filtered through a plate and frame filter press, and the filtered clear liquid is collected to obtain a purified sodium bisulfite liquid;

[0039] S6. Evaporation and concentration: The purified sodium bisulfite liquid is transported to a single-effect evaporator for vacuum concentration. The concentration temperature is controlled at 50 °C, and the vacuum degree is 0.09 MPa to obtain a supersaturated sodium bisulfite mixture;

[0040] S7. Centrifugal drying: The supersaturated sodium bisulfite mixture is separated by a centrifuge, and the obtained solid is dried under vacuum at 70 °C to obtain sodium bisulfite. The centrifugal mother liquor is collected as a by-product and recycled;

[0041] S8. By-product recycling: The mother liquor obtained in S7 is returned to the neutralization process in S4 and mixed with fresh purified liquid to participate in the neutralization reaction, realizing the utilization of by-products.

[0042] Example 3: The present invention provides a method for preparing sodium bisulfite and utilizing by-products, including the following steps:

[0043] S1. Incineration: The sulfur-containing tail gas generated in the production process of dimethyl sulfoxide is transported to an incineration device and subjected to thermal incineration at 750 °C to obtain a raw gas mainly composed of sulfur dioxide;

[0044] S2. Absorption: The raw gas is transported to an absorption tower. The temperature of the absorption tower is controlled at 35 °C. A sodium hydroxide solution with a mass concentration of 14% is used as the main absorption liquid, and a dilute sulfuric acid with a mass concentration of 4% is supplemented for pH adjustment. The pH value of the system is precisely controlled within 4.8 through on-line pH monitoring, and finally a sodium bisulfite absorption liquid with a mass concentration of 32% is obtained;

[0045] S3. Impurity removal: The sodium bisulfite absorption liquid is pumped into an ion exchange column loaded with strongly acidic cation exchange resin to remove metal ion impurities and obtain a purified liquid;

[0046] S4. Adsorption: The purified liquid is transferred to a neutralization kettle, and an activated carbon adsorbent is added. Mechanical stirring is maintained for 50 min to obtain a sodium bisulfite suspension;

[0047] S5. Filtration: The sodium bisulfite suspension is filtered through a plate and frame filter press, and the filtered clear liquid is collected to obtain a purified sodium bisulfite liquid;

[0048] S6. Evaporation and concentration: The purified sodium bisulfite liquid is transported to a single-effect evaporator for vacuum concentration. The concentration temperature is controlled at 55 °C, and the vacuum degree is 0.09 MPa to obtain a supersaturated sodium bisulfite mixed liquid;

[0049] S7. Centrifugal drying: The supersaturated sodium bisulfite mixed liquid is separated by a centrifuge, and the obtained solid is vacuum dried at 78 °C to obtain sodium bisulfite. The centrifugal mother liquor is collected as a by-product and recycled;

[0050] S8. By-product recycling: The mother liquor obtained in S7 is returned to the S4 neutralization process and mixed with fresh purified liquid to participate in the neutralization reaction to realize the utilization of by-products.

[0051] Example 4: The present invention provides a method for preparing sodium bisulfite and utilizing by-products, including the following steps:

[0052] S1. Incineration: The sulfur-containing tail gas generated in the production process of dimethyl sulfoxide is transported to an incineration device and subjected to thermal incineration at 800 °C to obtain a raw gas mainly composed of sulfur dioxide;

[0053] S2. Absorption: The raw gas is transported to an absorption tower. The temperature of the absorption tower is controlled at 40 °C. A sodium hydroxide solution with a mass concentration of 15% is used as the main absorption liquid, and a dilute sulfuric acid with a mass concentration of 5% is supplemented for pH adjustment. The pH value of the system is precisely controlled at 5.0 through on-line pH monitoring, and finally a sodium bisulfite absorption liquid with a mass concentration of 40% is obtained;

[0054] S3. Impurity removal: Pump the sodium bisulfite absorption solution into an ion exchange column loaded with strongly acidic cation exchange resin to remove metal ion impurities and obtain a purified solution.

[0055] S4. Adsorption: Transfer the purified solution to a neutralization kettle, add activated carbon adsorbent, and maintain mechanical stirring for 60 min to obtain a sodium bisulfite suspension.

[0056] S5. Filtration: Filter the sodium bisulfite suspension through a plate and frame filter press, collect the filtrated clear liquid, and obtain a purified sodium bisulfite solution.

[0057] S6. Evaporation and concentration: Transport the purified sodium bisulfite solution to a single-effect evaporator for vacuum concentration, control the concentration temperature at 60 °C, and the vacuum degree at 0.10 MPa to obtain a supersaturated sodium bisulfite mixture.

[0058] S7. Centrifugal drying: Separate the supersaturated sodium bisulfite mixture by a centrifuge, vacuum-dry the obtained solid at 80 °C to obtain sodium bisulfite, and collect and recycle the centrifugal mother liquor as a by-product.

[0059] S8. By-product recycling: Return the mother liquor obtained in S7 to the S4 neutralization process, mix it with the fresh purified solution to participate in the neutralization reaction, and realize the utilization of by-products.

[0060] In Examples 1-4, the strongly acidic cation exchange resin is 15 ion exchange resin, which can effectively remove calcium ions, magnesium ions, iron ions, etc. The activated carbon adsorbent is columnar activated carbon, and the specific surface area of the activated carbon adsorbent is ≥ 1200 m 2 / g. The filtration accuracy of the plate and frame filter press is 0.45 μm, and the density of the supersaturated sodium bisulfite mixture is 1.28-1.32 g / cm 3 , use a heat exchanger to recover the heat energy of the raw material gas. The heat exchanger adopts a shell-and-tube heat exchanger. In the shell-and-tube heat exchanger, the raw material gas passes through the shell side, and the condensed water passes through the tube side. After heat exchange, the condensed water is converted into saturated steam. The heat exchanger reduces the temperature of the raw material gas to 180-195 °C. The formation temperature range of dioxins is 200-500 °C. In this temperature range, the formation reaction of dioxins is relatively active. Therefore, by quickly reducing the temperature of the raw material gas below 200 °C through the heat exchanger, the formation temperature range of dioxins can be effectively crossed, thereby inhibiting its formation. The saturated steam serves as the heat source of the single-effect evaporator to provide heat for the single-effect evaporator. The present invention can make full use of the heat energy in the raw material gas, reduce production costs, and avoid energy waste.

[0061] Test example

[0062] Test content: Record the total mass M and mass concentration ρ of the sodium bisulfite absorption solution in Examples 1 to 4, and record the mass m of sodium bisulfite. According to the formula: The yield of sodium sulfite Calculate the yields of anhydrous sodium sulfite in Examples 1 to 4 and tabulate them in Table 1.

[0063] Table 1

[0064] M / kg ρ / % m / kg η / % Example 1 85 15 12.11 94.98 Example 2 92 24 21.08 95.47 Example 3 110 32 33.84 96.13 Example 4 120 40 46.04 95.92

[0065] As can be seen from Table 1, the method for preparing sodium bisulfite and utilizing by-products of the present invention has a relatively high yield of sodium bisulfite, indicating that during the conversion process from the sodium bisulfite absorption solution to sodium bisulfite, most of the sodium bisulfite can be successfully converted into the final product with less loss. The yields of the four examples are between 94.98% and 96.13%, indicating that the process of the present invention has good stability.

[0066] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing sodium bisulfite and utilizing by-products, characterized in that: It includes the following steps: S1. Incineration: The sulfur-containing tail gas generated in the production process of dimethyl sulfoxide is transported to an incineration device and subjected to thermal incineration at 600 - 800 °C to obtain a raw gas mainly composed of sulfur dioxide; S2. Absorption: The raw gas is transported to an absorption tower. The temperature of the absorption tower is controlled at 25 - 40 °C. A sodium hydroxide solution with a mass concentration of 10% - 15% is used as the main absorption liquid, and at the same time, a dilute sulfuric acid with a mass concentration of 3% - 5% is used to adjust the pH. The pH value of the system is precisely controlled within the range of 4.0 - 5.0 through on-line pH monitoring, and finally, a sodium bisulfite absorption liquid with a mass concentration of 15% - 40% is obtained; S3. Impurity removal: The sodium bisulfite absorption liquid is pumped into an ion exchange column loaded with strongly acidic cation exchange resin to remove metal ion impurities and obtain a purified liquid; S4. Adsorption: The purified liquid is transferred to a neutralization kettle, and an activated carbon adsorbent is added, and mechanical stirring is maintained for 30 - 60 min to obtain a sodium bisulfite suspension; S5. Filtration: The sodium bisulfite suspension is filtered through a plate and frame filter press, and the filtered clear liquid is collected to obtain a purified sodium bisulfite liquid; S6. Evaporation and concentration: The purified sodium bisulfite liquid is transported to a single-effect evaporator for vacuum concentration. The concentration temperature is controlled at 40 - 60 °C, and the vacuum degree is 0.08 - 0.10 MPa to obtain a supersaturated sodium bisulfite mixed liquid; S7. Centrifugal drying: The supersaturated sodium bisulfite mixed liquid is separated by a centrifuge, and the obtained solid is vacuum dried at 60 - 80 °C to obtain sodium bisulfite, and the centrifugal mother liquor is collected as a by-product and recycled; S8. By-product recycling: The mother liquor obtained in S7 is returned to the S4 neutralization process and mixed with fresh purified liquid to participate in the neutralization reaction to realize the utilization of by-products.

2. The method for preparing sodium bisulfite and utilizing by-products according to claim 1, characterized in that: The strongly acidic cation exchange resin is 15 ion exchange resin.

3. A method for preparing sodium bisulfite and utilizing by-products according to claim 1, characterized in that: The activated carbon adsorbent is columnar activated carbon, and the specific surface area of the activated carbon adsorbent is ≥ 1200 m 2 / g.

4. A method for preparing sodium bisulfite and utilizing by-products according to claim 1, characterized in that: The addition amount of the activated carbon adsorbent is 1% - 5% of the mass of the purified liquid.

5. A method for preparing sodium bisulfite and utilizing by-products according to claim 1, characterized in that: The filtration accuracy of the plate and frame filter press is 0.45 μm.

6. A method for preparing sodium bisulfite and utilizing by-products according to claim 1, characterized in that: The density of the supersaturated sodium bisulfite mixture is 1.28 to 1.32 g / cm 3 .

7. A method for preparing sodium bisulfite and utilizing by-products according to claim 1, characterized in that: A heat exchanger is used to recover the heat energy of the raw gas. The heat exchanger reduces the temperature of the raw gas to 180 - 195 °C, and the recovered heat energy provides heat source for the single-effect evaporator.