CN1112345C - Short-path molecular distillation process for refining lactic acid - Google Patents

Short-path molecular distillation process for refining lactic acid Download PDF

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Publication number
CN1112345C
CN1112345C CN00114432A CN00114432A CN1112345C CN 1112345 C CN1112345 C CN 1112345C CN 00114432 A CN00114432 A CN 00114432A CN 00114432 A CN00114432 A CN 00114432A CN 1112345 C CN1112345 C CN 1112345C
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lactic acid
short
refining
molecular distillation
pump
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CN1270953A (en
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张金彬
梁廷德
王伟
蔡毅
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Wuhan Sanjiang Space Good Biotech Co.,Ltd.
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NATIONAL CHEMICAL CO Ltd GUANGSHUI CITY HUBEI PROV
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Abstract

The present invention relates to a short-path molecular distillation process for refining lactic acid. The process adopts a molecular distillation technique and has the basic process that 1, a lactic acid solution containing 30 to 80% of lactic acid is sent into an evaporator by a material pump and is quantitatively kept; under certain working pressure, the solution is heated and distilled, moisture is distilled out and cooled for collection, and the lactic acid content is kept more than 95%; 2, the concentrated lactic acid is uniformly sent into a short-path molecular distillation evaporator by a pump and is heated and distilled; different substances in materials can collect the moisture, the lactic acid and macromolecule organic matter via fractional condensation at certain pressure and temperature via different molecular free paths, the moisture, the lactic acid and the macromolecule organic matter are sent out by the pump, and material temperature in the evaporator is kept in 115 DEG C; 3, when the material temperature is higher than 115 DEG C in continuous distillation processes, a small amount of water vapor is led into the evaporator; when the material temperature is risen to 120 DEG C, the distillation is stopped, and residue is output by the pump; 4, the contents of the distilled moisture and the prepared lactic acid are adjusted, and the finished products of the lactic acid with 88 to 90% of content are obtained.

Description

The short-path molecular distillation process for refining of lactic acid
The present invention relates to the short-path molecular distillation process for refining of a kind of complete processing of Chemicals, particularly lactic acid.It is a kind of process for refining of obtain lactic acid, is applicable to the refining processing to food grade or pharmaceutical grade work in-process lactic acid or finished product lactic acid (comprising left-handed or dextrorotation or DL lactic acid), makes it to reach heat-resisting level fine purification of lactic acid.
Lactic acid is a kind of purposes industrial chemicals comparatively widely, and it is mainly used in food service industry and medication chemistry industries such as beer, liquor beverage, and lactic acid is the a-hydroxy-propionic acid again, and its chemical molecular formula is: CH 3CHOHCOOH, molecular weight are 90.8.The price of food grade lactic acid is at 52 cents/pound in the international market, and the price of fine purification of lactic acid is at 1 dollar/pound, and both price differences are very big.The raw material that is used to prepare fine purification of lactic acid now is generally and adopts the food grade that fermentation method produces or the lactic acid of pharmaceutical grade, is substantially devoid of mineral ion, but contains reducing sugar.Its finished product is yellowly owing to contain organic impurity such as thalline degradation product, and multinomial physical and chemical index does not reach the requirement of fine purification of lactic acid, therefore, obtaining fine purification of lactic acid just must reprocess it, remove the organic impurities that wherein contains, wish that simultaneously refining cost of processing is cheap as far as possible, the lactic product quality that obtains is good.According to the knowledge of the applicant, now manufacturer produces fine purification of lactic acid and adopts esterification process usually, the steps include: 1) with food grade or pharmaceutical grade lactic acid under rough vacuum (760-20 mmhg) condition, the heating thickening reaches more than 95% lactic acid content.2) lactic acid behind the general is transferred in the retort, adds an amount of methanol esterification under the effect of catalyzer, generates methyl lactate, go out methyl lactate by vacuum distilling again and change hydrolytic decomposition pot over to, add distilled water, carry out the reflux hydrolysis, generate lactic acid and methyl alcohol, again methyl alcohol is distilled out, obtain fine purification of lactic acid.The weak point of this fine purification of lactic acid technology is: 1. the boiling point of methyl lactate and methyl alcohol is lower, and its methyl alcohol that contains of the purity requirement of the fine purification of lactic acid that will make must not be greater than 1,000,000/, so, the loss in vacuum distillation process of methyl lactate and methyl alcohol is serious, and the yield of product is lower.2. methyl alcohol evaporate in the air in process of production, and on-the-spot and environment are caused certain influence, and is harmful.3. because the deficiency that its technology self exists, make the fine purification of lactic acid of final gained, often, wherein methanol content becomes substandard product owing to exceeding standard.
The objective of the invention is, improve, propose the short-path molecular distillation process for refining of lactic acid at above-mentioned the deficiencies in the prior art.To remove organic impurities in the lactic acid, obtain highly purified fine purification of lactic acid, reduce refining cost of processing simultaneously.
Technical solution of the present invention is, adopts the lactic acid of food grade or pharmaceutical grade or low levels lactic acid work in-process as raw material, it is characterized in that adopt the thermal distillation that adds under the high vacuum state, its basic technology is:
1) will be that the lactic acid solution of 30-80% is sent in the vaporizer with product pump through the lactic acid content of ion-exchange, keep one quantitatively, under certain working pressure, the limit adds thermal distillation, the limit distillates moisture content, cooling is collected, and lactic acid content is remained on more than 95%, on one side spissated lactic acid is evenly exported with certain speed simultaneously, continue on one side to add rare lactic acid, distillate moisture content and should be equal to rare lactic acid magnitude of recruitment with the output lactic acid production;
2) with certain speed equably send in the vaporizer of short-range molecular distillation with mechanical pump spissated lactic acid, remain one and quantitatively under certain working pressure, open the rotation knifing, heat by chuck, the temperature of chuck is controlled at 120-150 ℃, adds thermal distillation; Collect moisture content, lactic acid and larger molecular organics according to the differing molecular free path fractional condensation under the shortly fixed pressure and temp condition of different substances in the material, and send with product pump, all distillate qualities are equal to the magnitude of recruitment of spissated lactic acid, and temperature of charge should remain in 60-115 ℃ in the vaporizer;
When 3) the material temperature is higher than 115 ℃ in continuing still-process, in vaporizer, feed a small amount of water vapor, to slow down the acid by dehydrating lactic auto-polymerization, guaranteeing operating pressure and feeding under the situation of water vapour, temperature of charge rises to 120 ℃, stops distillation, exports resistates with mechanical pump;
4) moisture content that distills out and the lactic acid that makes are carried out the content adjustment, adjusting to lactic acid content is that 88-90% promptly obtains fine purification of lactic acid.
Its feature in, the food grade of employing or the lactic acid of pharmaceutical grade or low levels lactic acid work in-process raw material are food grade or pharmaceutical grade DL or D-lactic acid.
The operating pressure of its feature in, vaporizer is 1 * 1.33322 * 10 3Handkerchief.
Its feature in, the major ingredient of the resistates of output is polymerization lactic acid, reducing sugar.
Its feature in, the resistates of output can utilize again, can add lower alcohol and produce lactic acid ester.
Advantage of the present invention is, adopted molecular distillation technique, obtain lactic acid under high vacuum condition, its process optimization is reasonable, and refining low processing cost is used common raw material, do not add catalyzer, do not add extraction agent, can obtain highly purified fine purification of lactic acid by consumption of power and steam, and can guarantee quality product.The physical and chemical index of fine purification of lactic acid reaches the level of developed countries like product.The resistates of technological process of the present invention can utilize again, can produce ethyl lactate, n-Butyl lactate etc.Use the present invention, the lactic acid overall losses is few.
Below, describe embodiments of the invention in detail.
1. at first, distillation concentrated lactic acid solution.Is that 30% lactic acid solution is sent in the luwa evaporator for 6 tons with product pump with lactic acid content, then opens the rotation knifing, opens the vacuum unit of being made up of lobe pump and water-ring pump, adjusts vacuum 30 * 1.33322 * 10 3About handkerchief, open vaporizer chuck steam, make vapour temperature remain on 130-150 ℃, the moisture content that distills out cooling is collected in the surge tank, send with product pump, and continue to replenish rare lactic acid with product pump simultaneously, magnitude of recruitment and quantity of distillate are equal to substantially, again by adjusting magnitude of recruitment and quantity of distillate, when making lactic acid in the vaporizer contain quality more than 95%, quality continues it to send with toothed gear pump from base of evaporator at the 5-6 ton, and its discharge is 300 kilograms/hour.2. promptly send into the luwa evaporator of short-range molecular distillation after the spissated lactic acid of above-mentioned process is exported by (adjustable speed) toothed gear pump, measure about 3 tons.Open the vacuum unit of forming by lobe pump and water-ring pump, cold-trap, and make the operating pressure in this vaporizer remain on 1.33322 * 10 2-1.33322 * 10 3About handkerchief, start rotatable knifing, open vaporizer chuck steam, make vapour temperature remain on 120-150 ℃, continue distillation, and continue to replenish dense lactic acid with toothed gear pump simultaneously.Magnitude of recruitment and quantity of distillate are equal to, distillate composition three grades of condensations of molecular free path different set according to its various materials under the working unit pressure and temperature, final stage condensation collection moisture content and part lactic acid continue output in surge tank with product pump, and lactic acid content is at 10-30%.B-grade condensation is collected lactic acid in surge tank, and its content continues output more than 95% with product pump.When temperature of charge in the vaporizer is not higher than 115 ℃, not at first level condensation.Behind 20 tons of products of continuous production, stop charging, continue distillation.When temperature of charge surpasses 115 ℃, open elementary condensation, collect organic colour generation thing of polymer and small part lactic acid and export back steaming in surge tank, and continue to feed a little steam from base of evaporator simultaneously, it is reference value that the feeding amount is no more than 120 ℃ with temperature of charge in the vaporizer.When the lactic acid that goes out to heat up in a steamer obviously reduces, when B-grade condensation is collected lactic acid production less than 1 kg/minute, stop distillation, with toothed gear pump resistates is exported, general each about 2.4 tons of salvage stores, the yield of lactic acid is not less than 85%, does not contain the utilization again of resistates.3. the lactic acid goods that the lactic acid that distills out blent into content and be 88-90% are the fine purification of lactic acid finished product.

Claims (5)

1, the short-path molecular distillation process for refining of lactic acid, the lactic acid of employing food grade or pharmaceutical grade or lactic acid work in-process is characterized in that as raw material, adopt the thermal distillation that adds under the high vacuum state, and its basic technology is:
1) will be that the lactic acid solution of 30-80% is sent in the vaporizer with product pump through the lactic acid content of ion-exchange, keep quantitatively, under operating pressure, the limit adds thermal distillation, the limit distillates moisture content, cooling is collected, and lactic acid content is remained on more than 95%, on one side spissated lactic acid is exported with uniform rate simultaneously, continue on one side to add rare lactic acid, distillate moisture content and should be equal to rare lactic acid magnitude of recruitment with the output lactic acid production;
2) spissated lactic acid is sent in the short-range molecular distillation vaporizer with uniform rate with mechanical pump, remained quantitatively, open the rotation knifing under operating pressure, by the chuck heating, the temperature of chuck is controlled at 120-150 ℃, adds thermal distillation; Collect moisture content, lactic acid and larger molecular organics according to the differing molecular free path fractional condensation under the shortly fixed pressure and temp condition of different substances in the material, and send with product pump, all distillate qualities should be equal to the magnitude of recruitment of spissated lactic acid, and temperature of charge should remain in 60-115 ℃ in the vaporizer;
When 3) temperature of charge is higher than 115 ℃ in continuing still-process, in vaporizer, feed a small amount of water vapor, to slow down the acid by dehydrating lactic auto-polymerization, guaranteeing operating pressure and feeding under the situation of water vapour, temperature of charge rises to 120 ℃, stops distillation, exports resistates with mechanical pump;
4) moisture content that distills out and the lactic acid that makes are carried out the content adjustment, adjusting to lactic acid content is that 88-90% promptly obtains fine purification of lactic acid.
2, the short-path molecular distillation process for refining of lactic acid according to claim 1, its feature in, the food grade of employing or the lactic acid of pharmaceutical grade or lactic acid work in-process raw material are food grade or pharmaceutical grade DL or D-lactic acid.
3, the short-path molecular distillation process for refining of lactic acid according to claim 1, the operating pressure of its feature in, vaporizer is 30 * 1.33322 * 10 3Handkerchief.
4, the short-path molecular distillation process for refining of lactic acid according to claim 1, its feature in, the composition of the resistates of output is polymerization lactic acid, reducing sugar.
5, the short-path molecular distillation process for refining of lactic acid according to claim 1, its feature in, the resistates of output can utilize again.
CN00114432A 2000-03-20 2000-03-20 Short-path molecular distillation process for refining lactic acid Expired - Fee Related CN1112345C (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2534252B1 (en) 2010-02-08 2015-06-17 PURAC Biochem BV Process for manufacturing lactic acid
CN102225892A (en) * 2011-05-10 2011-10-26 武汉三江航天固德生物科技有限公司 Preparation method of low-sodium potassium lactate
CN102351686B (en) * 2011-08-16 2013-11-06 武汉三江航天固德生物科技有限公司 Lactic acid extraction and purification production method by methanol esterification-vacuum distillation hybrid method
CN103724183B (en) * 2013-12-16 2015-10-28 河南金丹乳酸科技股份有限公司 Utilize the method for molecular distillation technique industrial production of lactic acid
CN105399622B (en) * 2015-11-20 2017-09-19 武汉三江航天固德生物科技有限公司 A kind of method of use heavy constituent production of lactic acid potassium lactate
CN107098808B (en) * 2017-05-05 2020-01-31 湖北壮美生物科技有限公司 Preparation method and production device of high-purity high-content normal-temperature non-crystallized lactic acid products
CN109265338A (en) * 2018-10-09 2019-01-25 武汉三江航天固德生物科技有限公司 The production method of medical sodium lactate solution
CN109160877A (en) * 2018-10-09 2019-01-08 武汉三江航天固德生物科技有限公司 The production method of medical calcium lactate
CN111574360A (en) * 2020-05-25 2020-08-25 中粮营养健康研究院有限公司 Method for separating lactic acid
CN114276233A (en) * 2021-11-01 2022-04-05 欧尚元(天津)有限公司 Refining and purifying method and purifying device for crude L-lactic acid

Citations (2)

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Publication number Priority date Publication date Assignee Title
WO1995003268A1 (en) * 1993-07-26 1995-02-02 A.E. Staley Manufacturing Company Process for recovering organic acids
WO1998055442A1 (en) * 1997-06-06 1998-12-10 'BRUSSELS BIOTECH' en abrégé '2B' Method for purifying lactic acid

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995003268A1 (en) * 1993-07-26 1995-02-02 A.E. Staley Manufacturing Company Process for recovering organic acids
WO1998055442A1 (en) * 1997-06-06 1998-12-10 'BRUSSELS BIOTECH' en abrégé '2B' Method for purifying lactic acid

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