CN1273940A

CN1273940A - Process for preparing safety powder of sodium formate from liquid-state SO2 and solid-state sodium carbonate

Info

Publication number: CN1273940A
Application number: CN 99112203
Authority: CN
Inventors: 张心达; 黄继学; 陶积政
Original assignee: JINHE SAFETY POWDER FACTORY YANTAI CITY
Current assignee: JINHE SAFETY POWDER FACTORY YANTAI CITY
Priority date: 1999-05-12
Filing date: 1999-05-12
Publication date: 2000-11-22

Abstract

A process for preparing the safety powder of sodium formate from liquid-state SO2 and solid-state sodium carbonate technically features its chemical reaction equation: 4SO2+2HCOONa+Na2CO3=2NaS2O4+3CO2 +H2O. Its advantages include saving raw materials and energy, high output rate of product, and less environmental pollution.

Description

Method for producing sodium formate-process sodium hydrosulfite by using liquid sulfur dioxide and solid sodium carbonate

The invention relates to a method for producing sodium hydrosulfite by a sodium formate method, in particular to a method for producing sodium hydrosulfite by a sodium formate method by using liquid sulfur dioxide and solid sodium carbonate.

In the background art, sodium hydroxide method is adopted to produce sodium hydrosulfite in the chemical industry field. The chemical reaction principle equation is as follows: . The main process conditions are characterized in that: HCOONa is 700g/L aqueous solution, NaOH is 160g/L NaOH-CH prepared from 42% aqueous solution and methanol₃OH solution, SO₂Is heated and vaporized, and then is absorbed into 260g/L SO by methanol₂-CH₃OH solution; b. water and methanol are used as a solvent and a dispersion medium, and the optimal mass ratio of the alcohol to the water is 80: 20; C. the optimal molar ratio of the alkali to the alcohol is 1: 19-21. These above process conditions resulted in 7000L of mother liquor per ton of sodium hydrosulfite. The neutralization and distillation of the mother liquor consume a large amount of caustic soda and energy, and simultaneously, a large amount of methanol and NaHSO in the mother liquor₃Energy-removing deviceCollecting part Na₂SO₃And the rest parts except the methanol can not be utilized, and the environment is polluted after the emission. The product yield of the method can only reach 47.9 percent (calculated by HCOONa). On the other hand, a large amount of dispersion medium enters the reaction system, so that the feeding coefficient of the equipment is greatly reduced, the single-machine yield is low, the equipment capacity is small, and the product cost is high.

The invention aims to eliminate liquid SO in the traditional method for producing sodium hydrosulfite by a sodium formate method₂Heating for gasification, and then using methanol for absorption to reduce the amount of methanol and water entering the reaction system, thereby realizing the recovery of HCOONa and Na from the synthesized mother liquor and the dried and washed methanol₂CO₃While achieving the effect of Na as a solid₂CO₃The liquid amount entering the reaction system isreduced instead of liquid caustic, and the defects of the background art are overcome.

The technical scheme of the invention is realized in such a way. A method for producing sodium formate-process sodium hydrosulfite by using liquid sulfur dioxide and solid sodium carbonate is characterized by comprising the following steps: a, preparing materials: according to the weight ratio of sulfur dioxide, sodium formate and sodium carbonate of 2.8-3.8: 1.5-2.5: 1, a, adding more than 40% of synthetic mother liquor and sodium formate to 1^#Stirring and beating the mixture into suspension in a batching pot; b. adding 2 percent of process water, methanol liquid absorbed by reaction tail gas, over 40 percent of washing methanol and solid sodium carbonate according to batch feeding amount^#Starting a batching pot, stirring, adding a proper amount of liquid sulfur dioxide, and properly acidifying, wherein the pressure of the batching pot is controlled to be 0.2-0.35 Mpa (gauge pressure); B. synthesizing and feeding materials: the following operations are carried out according to the control conditions of 65-85 ℃ of temperature, 0.1-0.25Mpa of pressure and 4.2-5.3 of PH value, C. 1^#And 2^#Acidified materials and liquid SO in proportioning pot₂Respectively controlling the corresponding flow rate and simultaneously adding the large drops into the synthesis potIn the process, the temperature, the pressure and the PH value in the synthesis pot are tested, and the flow rate of the materials is adjusted according to the test until the materials in the two pots are added; d. the materials in the synthesis pot are properly insulated, the PH value is measured to reach the specified index, and the control is goodDropwise adding liquid sulfur dioxide at a small flow rate, controlling the temperature, pressure and pH value of a synthesis pot, ending the reaction when the synthesis content is more than or equal to 88%, preserving heat for 1 hour, cooling to 50-60 ℃, performing pressure filtration, washing with methanol, and finally performing vacuum drying to obtain the finished sodium hydrosulfite; the chemical reaction principle equation of the above method is: . Wherein, the preferable range of the weight ratio of the sulfur dioxide to the sodium formate to the sodium carbonate is as follows: 1.9-2.3: 3.0-3.4: 1; in the step C of the method, a proper amount of ethylene oxide auxiliary agent is dropwise added according to the reaction requirement; the preferable range of the addition amount of the mother liquor is 30-65%; the preferred range of wash methanol addition is 40-70%.

Compared with the background technology, the invention has the advantages and positive effects that: 1, since the method uses liquid SO₂Make the source used for absorbing SO₂The cold methanol is not used, so that a large amount of methanol is not required to enter a reaction system, and water originally used for adjusting the alcohol-water ratio is not required to enter the reaction system; liquid SO₂Does not need heating vaporization, saves energy, and simultaneously replaces water and methanol with mother liquor to dissolve and disperse HCOONa and uses solid Na₂CO₃The substitution of 42% of liquid caustic provides conditions. 2, due to the use of solid Na₂CO₃Provides conditions for recycling the washing methanol in the drying process, further reduces the neutralization and distillation amount and saves a large amount of energy. In the original process, for example, the washing methanol is used for replacing the refined methanol to absorb SO₂Because the washing methanol contains a certain amount of sodium hydrosulfite, when the washing methanol meets SO₂Post (strongly acidic) decomposition to Na₂S₂O₃And S, which affects the synthesis and cannot be used. The sodium hydrosulfite is stable under alkaline conditions, so the method can use washing methanol. 3, the method can ensure that the recycling rate of the mother liquor reaches more than 40 percent, the recycling rate of the washing methanol also reaches more than 40 percent, the proportion of the fresh dispersion medium entering the reaction system of the method only accounts for about 35 percent, the raw materials taken away by the mother liquor can be greatly reduced, the utilization rate of the raw materials is improved, and the product yield can be greatly improved and can reach 70 percent (calculated by HCOONa). 4, since the process uses liquid SO₂And synthesis ofMother liquor, HCOONa suspension, washing methanol and Na₂CO₃The acidification liquid leads the feeding coefficient to be multiplied, the single machine yield is improved by 2.5 times compared with the original process method, the mother liquid yield of unit product is reduced to 880L/t which is only 12.6 percent of the original process, the post-treatment capacity is greatly reduced, and the environmental pollution is reduced.

The invention is further illustrated by the following examples.

Example 1, the inventive method was carried out as follows: a, preparing materials: weigh out 798Kg of sodium formate (solid)State) 420KgNa₂CO₃(solid state) and 1272KgSO₂(liquid state) the following operations were carried out. a. 50 percent of the synthesis mother liquor of the previous reaction and sodium formate are added into 1^#Stirring and beating the mixture into suspension in a batching pot; b. adding 50% of process water, methanol liquid absorbed by last reaction tail gas, methanol washed by last reaction and solid sodium carbonate into the reactor 2^#Starting a dosing pot, stirring, adding a proper amount of liquidsulfur dioxide, and carrying out proper acidification, wherein the pressure of the pot is controlled to be 0.2-0.35 MPa; B. synthesizing and feeding materials: c, according to the control conditions of 65-85 ℃ of temperature, 0.1-0.25MPa of pressure and 4.2-5.3 of PH value, the following operations are carried out^#And 2^#Acidified materials and liquid SO in proportioning pot₂Respectively controlling the corresponding flow, simultaneously adding the large drops into a synthesis pot, testing the temperature, the pressure and the PH value in the synthesis pot, and adjusting the flow rate of the materials according to the test until the materials in the two pots are completely added; d. properly preserving the temperature of the materials in the synthesis pot, measuring the pH value to reach a specified index, controlling the flow rate of liquid sulfur dioxide droplet to be added into the synthesis pot, simultaneously controlling the temperature, pressure and pH of the synthesis pot, and finishing the reaction when the measured synthesis content is more than or equal to 88%; and then the temperature is reduced to 50-60 ℃ after the heat is preserved for 1 hour, then the pressure filtration is carried out (mother liquor required by the next reaction is generated), the methanol is washed (the washing methanol required by the next reaction is generated), and finally the finished product sodium hydrosulfite is prepared by vacuum drying.

Example 2, the inventive method was carried out as follows: a, preparing materials: 483Kg of sodium formate (in solid form), 210KgNa, are weighed out₂CO₃(solid state) and 715KgSO₂(liquid state) the following operations were carried out. a. Will last time60 percent of the reaction synthesis mother liquor and sodium formate are put into 1^#Stirring and beating the mixture into suspension in a batching pot; b. adding appropriate amount of process water, methanol solution absorbed by tail gas of last reaction, 55% of methanol washed by last reaction and solid sodium carbonate into 2^#The proportioning pot is started and stirred, and then a proper amount of liquid SO is added₂Carrying out proper acidification, and controlling the pressure of the pot to be 0.2-0.35 MPa; B. synthesizing and feeding materials: c, controlling the temperature to be 65-85 ℃, the pressure to be 0.1-0.25Mpa and the PH value to be 4.2-5.3, and carrying out the following operation^#And 2^#Acidified materials and liquid SO in proportioning pot₂Adding the mixture into a synthesis pot in a large drop manner, simultaneously adding a proper amount of ethylene oxide auxiliary agent, testing the temperature, the pressure and the pH value in the synthesis pot, and adjusting the flow rate of the materials according to the test results until the materials in the two pots are completely added; d. properly preserving the temperature of the materials in the synthesis pot, measuring the pH value to reach a specified index, controlling the flow rate of liquid sulfur dioxide droplet to be added into the synthesis pot, simultaneously controlling the temperature, pressure and pH of the synthesis pot, and finishing the reaction when the measured synthesis content is more than or equal to 88%; and then the temperature is reduced to 50-60 ℃ after the heat is preserved for 1 hour, and then the pressure filtration and the methanol washing are carried out, and finally the finished product sodium hydrosulfite is prepared by vacuum drying.

Claims

1. A method for producing sodium formate-process sodium hydrosulfite by using liquid sulfur dioxide and solid sodium carbonate is characterized by comprising the following steps: a, preparing materials: according to the feeding weight ratio of 2.8-3.8: 1.5-2.5: 1 of sulfur dioxide, sodium formate and sodiumcarbonate, a, more than 40% of synthetic mother liquor and sodium formate are fed into 1^#Stirring and beating the mixture into suspension in a batching pot; b. according to the batch charging quantity, the process water, methanol liquid absorbed by reaction tail gas, over 40% of washing methanol and solid sodium carbonate are added into 2^#Starting a dosing pot, stirring, adding a proper amount of liquid sulfur dioxide, and properly acidifying, wherein the pressure of the pot is controlled to be 0.2-0.35 Mpa;

b, synthesis and feeding: the following operations are carried out according to the control conditions of 65-85 ℃ of temperature, 0.1-0.25Mpa of pressure and 4.2-5.3 of PH value, C. 1^#And 2^#Acidified materials in the batching potAnd liquid SO₂Respectively controlling the corresponding flow, simultaneously dropwise adding, testing the temperature, the pressure and the pH value in the synthesis pot, and adjusting the flow rate of the materials according to the test result until the materials in the two pots are completely added; d. properly preserving the temperature of the materials in the synthesis pot, measuring the pH value to reach a specified index, controlling the flow rate of liquid sulfur dioxide for small dripping, controlling the temperature, pressure and pH value of the synthesis pot, ending the reaction when the synthesis content is more than or equal to 88 percent, preserving the temperature for 1 hour, cooling to 50-60 ℃, carrying out filter pressing, methanol washing and finally vacuum drying to obtain the finished product sodium hydrosulfite;

the chemical reaction principle equation of the above method is:

。

2. the method for producing sodium formate-process sodium hydrosulfite by using liquid sulfur dioxide and solid sodium carbonate according to claim 1, wherein the preferable range of the feeding weight ratio of sulfur dioxide to sodium formate to sodium carbonate is as follows: 1.9-2.3: 3.0-3.4: 1.

3. The method for producing sodium formate-process sodium hydrosulfite from liquid sulfur dioxide and solid sodium carbonate according to claim 1 or 2, characterized in that during step C, a proper amount of ethylene oxide auxiliary agent is added dropwise according to the reaction requirement.

4. The method for producing sodium formate-process sodium hydrosulfite from liquid sulfur dioxide and solid sodium carbonate according to claim 1 or 2, characterized in that the addition amount of the synthetic mother liquor is preferably in the range of 30-65%.

5. The method for producing sodium formate-process sodium hydrosulfite by using liquid sulfur dioxide and solid sodium carbonate according to claim 3, wherein the preferable range of the addition amount of the synthetic mother liquor is 30-65%.

6. The method for producing sodium formate-process sodium hydrosulfite from liquid sulfur dioxide and solid sodium carbonate according to claim 1 or 2, wherein the addition amount of washing methanol is preferably in the range of 40-70%.

7. The method for producing sodium formate-process sodium hydrosulfite by using liquid sulfur dioxide and solid sodium carbonate according to claim 3, wherein the preferable range of the addition amount of the washing methanol is 40-70%.

8. The method for producing sodium formate-process sodium hydrosulfite from liquid sulfur dioxide and solid sodium carbonate according to claim 4, wherein the preferable range of the addition amount of the washing methanol is 40-70%.