CN1442360A

CN1442360A - Method of producing sodium formate method sodium hydrosulfite using liquid sulfur dioxide and solid sodium carbonate

Info

Publication number: CN1442360A
Application number: CN 03112164
Authority: CN
Inventors: 张宝健; 张心遵; 王国清; 邹广柱
Original assignee: Jinhe Safety Powder Factory Co Ltd Yantai City
Current assignee: Jinhe Safety Powder Factory Co Ltd Yantai City
Priority date: 2003-04-16
Filing date: 2003-04-16
Publication date: 2003-09-17
Anticipated expiration: 2023-04-16
Also published as: CN1284725C

Abstract

A process for preparing Na2S2O4.2H2O powder from liquid-state SO2 and soldi-state sodium carbonate by sodium formate method includes such steps as proportioning SO2, sodium formate and sodium carbonate, adding syntetic mother liquid and sodium formate to the reactor No.1, adding technological water, adding the methanol liquid absorbed by tail gas, washing methanol and sodium carbonate and feeding them to the reactor No.2, and adding the materials acidified in reactors No.1 and No.2 and liquid SO2 to the synthesizing reactor. Its advantages are saving energy, low cost, environmental protection and high output rate.

Description

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

The technical field is as follows: 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.

Background art: in the chemical field, sodium hydroxide method is adopted to produce sodium hydrosulfite, and the chemical equation of the chemical reaction principle is as follows: . The main process conditions are as follows: firstly, 700g/L aqueous solution of HCOONa, 42 percent aqueous solution of NaOH and methanolPreparing NaOH-CH of 160g/L₃OH solution, SO₂Is heated and vaporized, and then is absorbed into 260g/L SO by methanol₂-CH₃OH solution; secondly, using water and methanol as a solvent and a dispersion medium; and thirdly, the optimal molar ratio of the alkali to the alcohol is 1: 19-21. 7000L of mother liquor is generated for each ton of sodium hydrosulfite produced by using the method. 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 liquor₃Except that part of Na can be recovered₂SO₃And the rest parts except the methanol can not be utilized, and the environment is polluted after the emission. The recovery of the above process was only low at 47.9% (calculated as HCOONa). And a large amount of dispersion media enter the reaction system, so that the feeding coefficient of equipment is greatly reduced, the single-machine yield is low, the equipment capacity is small, and the product cost is high.

The invention content is as follows: the technical problems to be solved by the invention are that a large amount of caustic soda and energy are consumed by a large amount of mother liquor generated in the background technology, the components of the mother liquor cannot be completely utilized to pollute the environment, the recovery rate of sodium formate is low, and the yield of a single machine is low and the product cost is high because a large amount of dispersion medium enters a reaction system. The technical scheme for solving the technical problems is as follows: 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: 1. preparing materials: according to the weight ratio of sulfur dioxide, sodium formate and sodium carbonate of 2.9-3.5: 1.6-2.4: 1, adding more than 40% of synthetic mother liquor and sodium formate into No. 1 proportioning pot, stirring and beating to obtain suspension, then according to the weight ratio of methanol and water in the reaction system of 80: 20, adding process water into No. 1 proportioning pot, adding all methanol liquor absorbed by reaction tail gas, more than 40% of washing methanol and solid sodium carbonate into No. 2 proportioning pot, stirring, adding proper quantity of liquid SO₂Carrying out proper acidification, and controlling the pressure of the pot at 0.2-0.35Mpa (gauge pressure); 2. synthesizing and feeding materials: performing the following operation under the control conditions of 65-85 deg.C, 0.1-0.25Mpa, and pH 4.2-5.3, mixing the acidified materials in No. 1 and No. 2 batch pots with liquid SO₂Are respectively provided withControlling the corresponding flow rate and adding into the synthesis pot, testing the temperature, pressure and pH value in the synthesis pot, adjusting the flow rate of the materials according to the measured values until the materials in the two pots are added, keeping the temperature of the materials in the synthesis pot, measuring the pH value to reach the specified index, and controlling the liquid SO₂Adding the mixture at the 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 percent, absorbing the reaction tail gas by a methanol removal absorption tower to obtain methanol absorption liquid for recycling, preserving heat for 1 hour, cooling to 50-60 ℃, performing filter pressing, methanol washing, and finally performing vacuum drying to obtain the finished product sodium hydrosulfite; the chemical reaction principle of the method is as follows: . Wherein the preferable range of the weight ratio of the sulfur dioxide to the sodium formate to the sodium carbonate is 3.1-3.3: 1.6-1.8: 1; in the method, the materials and the liquid SO which are acidified by the No. 1 and the No. 2 batching pots₂Respectively controlling corresponding flow and simultaneously adding the flow into a synthesis pot, testing the temperature, the pressure and the pH value in the synthesis pot, adjusting the flow rate of materials according to the test result, and adding an ethylene oxide auxiliary agent to inhibit the side reaction of generating the sodium thiosulfate in the process of adding the materials in the two pots till the materials in the two pots are completely added, wherein the adding amount is adjusted according to the speed of the sodium thiosulfate generated in the reaction; the preferable range of the addition amount of the mother liquor is 30-65%; the preferred range of wash methanol addition is 40-70%. It is also to be noted that: the total methanol liquid absorbed by the reaction tail gas and the quantity of the washing methanol are obtained according to the feeding quantity of each batch naturally. Compared with the background technology, the invention has the advantages that: firstly, because the method adopts 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; liquid SO₂No need of heating for vaporization, saving energy, and simultaneously using mother liquor to replace water and methanol to dissolve and disperse HCOONa and using solid Na₂CO₃The substitution of 42% of liquid caustic provides conditions. Secondly, because solid Na is used₂CO₃Provides 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, such as washingWashing methanol to replace 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 Na₂S₂O₄And S, which affects the synthesis and cannot be used. The sodium hydrosulfite is stable under alkaline conditions, so the method can use washing methanol. The method can make the recycling rate of the mother liquor reach more than 40 percent, the recycling rate of the washing methanol also reach more than 40 percent, less fresh dispersion medium enters the reaction system of the method, the raw material brought away by the mother liquor can be greatly reduced, the utilization rate of the raw material is improved, and the product yield is greatly improved and can reach 70 percent (calculated by HCOONa). Fourthly, because the method uses the liquid SO₂Synthetic mother 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 specific implementation mode is as follows:

example 1, the inventive method was carried out as follows: 1. preparing materials: 736Kg of sodium formate (in solid form), 410Kg of Na are weighed out₂CO₃(solid state) and 1275Kg SO₂Firstly, 50 percent of the synthetic mother liquor of the previous reaction and sodium formate are put into a No. 1 proportioning pot, stirring is started to be beaten into suspension, then the weight ratio of methanol to water in a reaction system is controlled according to batch feeding amount to be 80: 20, process water is added into the No. 1 proportioning pot, methanol liquid absorbed by the tail gas of the previous reaction, 50 percent of methanol washed by the previous reaction and solid sodium carbonate are put into a No. 2 proportioning pot, stirring is started, then a proper amount of liquid sulfur dioxide is added for proper acidification, and the pressure of the pot is controlled to be 0.2-0.35 Mpa; 2, synthesizing and feeding: respectively controlling the flow rates of the materials acidified in the No. 1 and No. 2 batching pots and liquid sulfur dioxide according to the control conditions of 65-85 ℃, 0.1-0.25Mpa and 4.2-5.3 of PH value, simultaneously adding the materials and the liquid sulfur dioxide into a synthesis pot in large drops, testing the temperature, the pressure and the PH value in the synthesis pot according to the test conditionsThe flow rate of the materials is adjusted until the materials in the two pots are added, the materials in the synthesis pot are properly insulated, the measured PH value reaches the specified index, the flow rate droplet of the liquid sulfur dioxide is controlled to be added into the synthesis pot, the temperature, the pressure and the PH value of the synthesis pot are controlled, and the reaction is finished when the measured synthesis content is more than or equal to 88 percent; 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: 1. preparing materials: 485Kg of sodium formate (in solid form) and 212Kg of Na are weighed out₂CO₃(solid state) and 700Kg SO₂(liquid state) the following operations are carried out, firstly 60 percent of the synthetic mother liquor of the last reaction and sodium formate are put into a No. 1 proportioning pot, stirring is started to be beaten into suspension, then the weight ratio of methanol to water in the reaction system is controlled according to batch feeding amount to be 80: 20, process water is added into the No. 1 proportioning pot, the methanol liquid absorbed by the last reaction tail gas, 55 percent of the methanol washed by the last reaction and solid sodium carbonate are put into a No. 2 proportioning pot, proper amount of liquid sulfur dioxide is added for proper acidification after stirring is started, and the pressure of the pot is controlled to be 0.2-0.35 Mpa; 2. synthesizing and feeding materials: respectively controlling the flow rates of the materials which are acidified in the No. 1 and No. 2 batching pots and liquid sulfur dioxide according to the control conditions of 65-85 ℃, 0.1-0.25Mpa and 4.2-5.3 of PH value, simultaneously adding the materials and the liquid sulfur dioxide into a synthesis pot in a large drop manner, simultaneously adding a proper amount of ethylene oxide auxiliary agent to inhibit the side reaction of generating sodium thiosulfate, testing the temperature, the pressure and the PH value in the synthesis pot, and adjusting the flow rate of the materials according to the temperature, the pressure and the PH value until the materials are added in the two pots; 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, controlling the temperature, pressure and pH value of the synthesis pot, and ending the reaction when the synthesis content is more than or equal to 88%; then the temperature is kept for 1 hour and then the temperature is reduced toAnd (3) performing filter pressing at 50-60 ℃ (mother liquor required by the next reaction is generated), washing with methanol (washing methanol required by the next reaction is generated), and finally performing vacuum drying to obtain the finished product sodium hydrosulfite.

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: 1. preparing materials: adding more than 40% of mother liquor synthesized according to the batch charging amount and sodium formate into a No. 1 proportioning pot according to the charging weight ratio of sulfur dioxide, sodium formate and sodium carbonate of 2.9-3.5: 1.6-2.4: 1, starting stirring and beating into suspension, then adding process water into the No. 1 proportioning pot according to the batch charging amount controlling the weight ratio of methanol to water in a reaction system to be 80: 20, adding all methanol liquid absorbed by reaction tail gas, more than 40% of washing methanol and solid sodium carbonate into the No. 2 proportioning pot, starting stirring and adding more than 40% of liquid SO₂Acidifying, andcontrolling pressure of the pot at 0.2-0.35Mpa (gauge pressure); 2. synthesizing and feeding materials: performing the following operation under the control conditions of 65-85 deg.C, 0.1-0.25Mpa, and pH 4.2-5.3, mixing the acidified materials in No. 1 and No. 2 batch pots with liquid SO₂Respectively controlling the flow rate and adding into the synthesis pot, testing the temperature, pressure and pH value in the synthesis pot, adjusting the flow rate of the materials until the materials are added, keeping the temperature of the materials in the synthesis pot, measuring the pH value to reach a specified index, and controlling the liquid SO₂Adding the mixture at the 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 percent, absorbing the reaction tail gas by a methanol removal absorption tower to obtain methanol absorption liquid for recycling, preserving heat for 1 hour, cooling to 50-60 ℃, performing filter pressing, methanol washing, and finally performing vacuum drying to obtain the finished product sodium hydrosulfite; the chemical reaction principle of the method is as follows: 。

2. the method for producing sodium formate-process sodium hydrosulfite with liquid sulfur dioxide and solid sodium carbonate according to claim 1, wherein the preferred range of the weight ratio of sulfur dioxide to sodium formate to sodium carbonate is 3.1-3.3: 1.6-1.8: 1.

3. According to the claimsClaim 1 or 2 the method for producing sodium formate-process sodium hydrosulfite by using liquid sulfur dioxide and solid sodium carbonate is characterized in that materials which are well acidified in No. 1 and No. 2 batching pots and liquid SO₂And respectively controlling the corresponding flow and simultaneously adding the materials into a synthesis pot, testing the temperature, the pressure and the pH value in the synthesis pot, adjusting the flow rate of the materials according to the test result, and dripping an ethylene oxide auxiliary agent in the process until the materials in the two pots are completely added to inhibit the side reaction of generating the sodium thiosulfate.

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 from liquid sulfur dioxide and solid sodium carbonate according to claim 3, wherein the addition amount of the synthetic mother liquor is preferably in the range of 30-65%.

6. A process for the production of sodium formate-process sodium hydrosulfite from liquid sulfur dioxide and solid sodium carbonate according to claim 1 or 2, characterized in that the washing methanol is added in a preferred range of 40-70%.

7. A process for the manufacture of sodium formate-process sodium hydrosulfite from liquid sulfur dioxide and solid sodium carbonate according to claim 3, characterized in that the washing methanol is added in the preferred range of 40-70%.

8. A process for the production of sodium formate-process sodium hydrosulfite from liquid sulfur dioxide and solid sodium carbonate as claimed in claim 4, characterized in that the washing methanol is added inthe preferred range of 40-70%.