Methanol alkali metering and batching system and application

Abstract

The invention relates to the technical field of system batching, in particular to a methanol alkali metering and batching system and application. According to the method, the methanol and the sodium carbonate are quantitatively mixed and then are uniformly mixed by adopting a colloid mill, and then the volume of a methanol-alkali mixed system which is uniformly mixed is accurately metered, so that the quantitative addition of alkali is realized. In the preparation process of the D-erythorbic acid or the sodium salt thereof, the method solves the problem of incomplete product conversion reaction caused by inaccurate alkali metering and adding due to easy residual hardening of sodium carbonate on the tank wall of a conversion tank caused by an existing adding mode of adding methanol first and then adding sodium carbonate, and has the advantages of improving the product yield and reducing the production cost. And the production cost and the maintenance cost are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of system batching, and in particular to a methanol alkali metering batching system and application thereof. Background Art

[0002] In the preparation process of D-isoascorbic acid or its sodium salt, 2-keto-D-gluconate methyl ester needs to be converted into sodium D-isoascorbate through a conversion reaction in an alkaline environment of methanol / sodium methoxide; in the existing process, the conversion reaction is carried out in a conversion tank. In actual operation, 2-keto-D-gluconate methyl ester, concentrated sulfuric acid and methanol are first added to the conversion tank, and then soda ash is added to the conversion tank, thereby creating an alkaline environment of methanol / sodium methoxide, thereby realizing the conversion reaction of 2-keto-D-gluconate methyl ester and realizing the preparation of D-isoascorbic acid or its sodium salt.

[0003] Since methanol and soda ash are not miscible, in actual production, methanol is added first and then soda ash. During the addition process, some soda ash will remain on the wall of the conversion tank and form a cake. Since the conversion reaction has accurate requirements for the amount of alkali, when soda ash remains on the wall of the conversion tank and forms a cake, the conversion reaction will be incomplete, affecting the yield and production cost of the product, as well as the stable operation of the equipment, increasing labor and maintenance costs, and bringing inconvenience to actual production.

[0004] Therefore, based on production practice, the present invention proposes a methanol alkali metering and dosing system, which quantitatively mixes methanol and soda ash and then mixes them evenly through a rubber mill, and then quantitatively adds the alkali by measuring the volume of the methanol-soda ash mixed system after the mixing. Since the method of adding soda ash alone is avoided, no compaction will be formed on the tank wall of the conversion tank, which ensures accurate addition of reduced amount, and is of great significance to improving product yield and reducing production and maintenance costs. Summary of the invention

[0005] The purpose of the present invention is to provide a methanol alkali metering and dosing system and application thereof, so as to solve the problem that in the existing method of adding methanol first and then soda ash in the preparation process of D-isoascorbic acid or its sodium salt, soda ash is easy to remain on the tank wall of the conversion tank, thereby causing inaccurate alkali addition and further affecting product conversion.

[0006] To achieve the above object, the present invention adopts the following technical scheme: a methanol alkali metering and dosing system, comprising the following steps:

[0007] S1, mixing methanol and alkali uniformly to obtain a uniformly mixed methanol-alkali mixed system;

[0008] S2. Apply the methanol-alkali mixed system S1 after accurate measurement.

[0009] Furthermore, in the S1, methanol is anhydrous methanol; and the alkali includes one of sodium hydroxide, sodium carbonate and sodium bicarbonate.

[0010] Furthermore, in the above S1, methanol and alkali are quantitatively mixed and uniformly mixed by rubber grinding.

[0011] Furthermore, the methanol-alkali mixed system is stirred before accurate metering to ensure that the system is always in a uniformly mixed state.

[0012] Furthermore, in S2, the volume of the methanol-alkali mixture system is accurately measured by an electromagnetic flowmeter.

[0013] Furthermore, in S2, the density of the methanol-alkali mixture system is detected by a mass flow meter, and the amount of alkali is accurately measured based on the volume, density and quantitative ratio of methanol and alkali.

[0014] Furthermore, the methanol alkali metering and dosing system is used in the preparation of D-isoascorbic acid or its sodium salt.

[0015] Furthermore, the alkali is sodium carbonate.

[0016] Furthermore, the weight ratio of the mass of the sodium carbonate to the weight of the methanol is 1:1-2.

[0017] Furthermore, the measurement error of the electromagnetic flowmeter is no more than 1%.

[0018] Beneficial effects of the present invention:

[0019] 1. The method of the present invention mixes methanol and alkali evenly through rubber mill before adding, thus avoiding the problem of inaccurate alkali measurement caused by the alkali easily remaining on the body of the conversion tank when methanol and alkali are added separately in the prior art;

[0020] 2. After the methanol and the alkali are uniformly mixed in the method of the present invention, the accurate measurement of the alkali amount is achieved by measuring the volume. The measurement in the process is simpler and more accurate, which brings convenience to the actual production. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0022] The principle of the present invention is:

[0023] 2-keto-D-gluconate methyl ester is converted into sodium D-isoascorbate through a conversion reaction in an alkaline environment of methanol / sodium methoxide; in the existing process, the conversion reaction is carried out in a conversion tank. Since methanol and alkali are immiscible, 2-keto-D-gluconate methyl ester, concentrated sulfuric acid and methanol are first added to the conversion tank, and then soda ash is added to the conversion tank to create an alkaline environment of methanol / sodium methoxide, thereby realizing the conversion reaction of 2-keto-D-gluconate methyl ester.

[0024] In actual production, since methanol is added first and then soda ash, soda ash residues and compaction will be formed on the tank wall of the conversion tank, thus affecting the accurate addition of the alkali amount; in the method of the present invention, methanol and soda ash are quantitatively mixed, and then ground by a colloid mill and pumped into the conversion tank. Since soda ash is added together with methanol, no residue will appear on the tank body of the conversion tank, thereby completely solving the problem of alkali metering in the existing process.

[0025] Example 1

[0026] 1. Instrument calibration

[0027] The electromagnetic flowmeter is measured and calibrated so that the measurement error is no more than 1%. During the process, multiple sets of data are continuously monitored to ensure the accuracy of the measurement results.

[0028] Table 1 Electromagnetic flowmeter calibration data table

[0029]

[0030]

[0031] 2. Dosage of alkali

[0032] Since methanol and alkali are quantitatively mixed, the content of alkali in the methanol alkali solution can be calculated by measuring the density with a mass flowmeter and measuring the volume with an electromagnetic flowmeter.

[0033] In this example, a single batch reaction in the conversion tank requires a total of 1.3 m3 of anhydrous methanol. 3 , 725kg of soda ash; after quantitatively mixing methanol and soda ash, use colloid mill to mix them evenly, and then pump them to the conversion tank. The test data during the process are as follows:

[0034] Table 2 Data sheet of mass flow meter and electromagnetic flow meter

[0035]

[0036] In the table above, total weight = density * flow rate;

[0037] Methanol weight = total weight * (1.3 × 791) ÷ (1.3 × 791 + 725)

[0038] Soda ash mass = total weight - methanol weight

[0039] The density and volume of the mixed solution are measured by mass flow meter and electromagnetic flow meter, and the above formula is entered into the on-site PLC. When the measured amount of soda ash added reaches 725kg, the addition of the mixed system is automatically stopped.

[0040] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A methanol alkali metering and dosing system, characterized in that: The following steps are involved: S1, mixing methanol and alkali uniformly to obtain a uniformly mixed methanol-alkali mixed system; S2. Use the S1 methanol-alkali mixed system after accurate measurement.

2. A methanol alkali metering and dosing system according to claim 1, characterized in that: In the S1, methanol is anhydrous methanol; and the alkali includes one of sodium hydroxide, sodium carbonate and sodium bicarbonate.

3. A methanol alkali metering and dosing system according to claim 1, characterized in that: In the above-mentioned S1, methanol and alkali are quantitatively mixed and uniformly mixed by rubber grinding.

4. A methanol alkali metering and dosing system according to claim 3, characterized in that: The methanol-alkali mixed system is stirred before accurate metering to ensure that the system is always in a uniformly mixed state.

5. A methanol alkali metering and dosing system according to claim 3, characterized in that: In the above-mentioned S2, the volume of the methanol-alkali mixed system is accurately measured by an electromagnetic flowmeter.

6. A methanol alkali metering and dosing system according to claim 5, characterized in that: In the above-mentioned S2, the density of the methanol-alkali mixed system is detected by a mass flow meter, and the amount of alkali is accurately measured according to the volume, density and the quantitative ratio of methanol and alkali.

7. A methanol alkali metering and dosing system according to any one of claims 1 to 6, characterized in that: The invention discloses an application of the methanol alkali metering and dosing system in the preparation of D-isoascorbic acid or its sodium salt.

8. The use of the methanol-alkali metering and dosing system according to claim 7, characterized in that: The alkali is sodium carbonate.

9. The use of the methanol-alkali metering and dosing system according to claim 8, characterized in that: The weight ratio of the sodium carbonate to the methanol is 1:1-2.

10. The use of the methanol-alkali metering and dosing system according to claim 7, characterized in that: The measurement error of the electromagnetic flowmeter is no more than 1%.

Images