阅读说明：本技术 一种高纯度低能耗的乳酸生产工艺 (High-purity low-energy-consumption lactic acid production process ) 是由 董立华 刘海涛 董卫涛 于 2018-08-23 设计创作，主要内容包括：本发明公开了一种低能耗高纯度的乳酸制备工艺,在乳酸生产过程中采用超滤膜将产物乳酸从发酵罐中源源不断的滤出,无需加入碱类调节发酵罐内pH,避免杂质引入同时还可避免酸抑制作用,省略了复杂的酸解及板框压滤步骤,避免大量副产物产生的同时降低了能耗,具有很高的环境保护价值及经济价值,并且本发明采用葡萄糖为原料,米根霉菌为发酵菌种,在制备过程中,通过米根霉的菌丝使其自团聚形成米根霉菌小球达到自固化的效果,避免游离的菌丝大面积团聚阻碍物料传质,发酵过后菌种易与料液分离,分离后的菌种还可进行重复利用,具有很高的经济价值,适用于工业生产。(The invention discloses a low-energy-consumption high-purity lactic acid preparation process, which adopts an ultrafiltration membrane to continuously filter out product lactic acid from a fermentation tank in the lactic acid production process, does not need to add alkalies to adjust the pH value in the fermentation tank, avoids impurity introduction and acid inhibition, omits complicated acidolysis and plate-and-frame filter pressing steps, reduces energy consumption while avoiding the generation of a large amount of byproducts, has high environmental protection value and economic value, adopts glucose as a raw material, takes rhizopus oryzae as a fermentation strain, in the preparation process, the rhizopus oryzae mycelia are self-agglomerated to form rhizopus oryzae pellets to achieve the self-curing effect, the free mycelia are prevented from being agglomerated in a large area to block mass transfer of materials, the strains are easy to separate from the feed liquid after fermentation, the separated strains can be recycled, and the rhizopus oryzae pellet preparation method has high economic value and is suitable for industrial production.)

1. A production process of lactic acid with high purity and low energy consumption is characterized by comprising the following steps:

(1) preparing raw materials: injecting a proper amount of water into the seasoning tank, heating the water to 50 ℃, opening the stirrer, pouring glucose powder, dissolving and stirring uniformly, adjusting the pH value to be between 5.5 and 6.0, and transferring the solution into a sugar solution storage tank for later use;

(2) heating and sterilizing: sterilizing material conveying equipment and fermentation equipment by adopting high-temperature steam, starting a material transferring pump after the material conveying equipment and the fermentation equipment are sterilized, enabling the material to enter a fermentation tank through an injection pump, simultaneously introducing the high-temperature steam into the injection pump, and heating and sterilizing the material by the high-temperature steam;

(3) fermentation: cooling the sterilized equipment and materials in the step (2) to 45-48 ℃, inoculating the strain into a fermentation tank, starting fermentation, keeping the temperature in the fermentation tank at 45-50 ℃ and the pressure at 0.4-0.8 Mpa, performing primary separation by using an ultrafiltration membrane in the fermentation process, continuously separating the product lactic acid from the fermentation liquid, and continuously fermenting the trapped liquid;

(4) and (3) purification: the filtrate obtained in the step (3) sequentially passes through a carbon column, a cation exchange column and an anion exchange column to remove impurities, and then enters an ion exchange liquid storage tank;

(5) MVR evaporation and concentration: starting a vacuum pump and a steam compressor, starting steam, heating the system, evaporating and concentrating the ion exchange liquid obtained in the step (4), and pumping the concentrated liquid into a storage tank before the membrane;

(6) and (3) nanofiltration membrane filtration: adjusting the pressure difference between the feeding and the discharging to be less than or equal to 0.5Mpa, leading the concentrated solution obtained in the step (5) to pass through a nanofiltration membrane, filtering impurities, and leading the filtrate to enter a membrane post-tank;

(7) concentrating by a plate evaporator: pumping the filtrate obtained in the step (6) into a plate evaporator, wherein the feeding flow rate is 5.2-6.0m³Heating by steam, controlling the air inlet pressure of a heat pump to be 0.35-0.4Mpa, controlling the discharge density to be 1.14-1.20kg/L, controlling the discharge concentration to reach more than 80%, and pumping into a finished product storage tank;

(8) blending and canning: and (5) detecting the material concentration in the finished product storage tank in the step (7), pumping the finished product into a blending tank according to the requirement, blending and canning.

2. The process for producing high-purity lactic acid according to claim 1, wherein the amount of glucose added in step (1) is adjusted according to the concentration required for production.

3. The process for producing high-purity lactic acid according to claim 1, wherein the fermentation strain in the step (3) is fermented by rhizopus oryzae, the rhizopus oryzae is granular rhizopus oryzae which is cultured and self-flocculated by hyphae of the rhizopus oryzae, the volume of the inoculated mold solution is 10-15% of the total volume of the feed solution in the fermentation tank, and the amount of the added yeast powder is 0.15-0.2% of that of the rhizopus oryzae.

4. A process for producing high purity lactic acid according to claim 1, wherein the feed liquid is diluted with ultrapure water before the ultrafiltration in step (3).

5. The production process of high-purity lactic acid according to claim 1, wherein the ion exchange flow rate of the feed liquid in the step (4) is 7-12 m³/h，Fe^3﹢≤10PPm,Cl^﹣The color is less than or equal to 20PPm, and the APHA is qualified when the chroma is less than or equal to 50.

6. The process for producing high-purity lactic acid according to claim 1, wherein the MVR evaporation concentration in the step (5) has a discharge density of 1.116-1.118 kg/L.

7. The process for producing high-purity lactic acid according to claim 1, wherein the water used for blending the materials in the step (8) is softened tap water, and the conductivity of the water is less than or equal to 20 μ s/cm.

Technical Field

The invention relates to the technical field of fermentation engineering, in particular to a high-purity low-energy-consumption lactic acid production process.

Background

Lactic acid has many uses in industry, food, medicine, and the like, and is widely used as a preservative, an acidulant, and a reducing agent. In the production process of cans, sauces and beverages, lactic acid can replace preservatives such as benzoic acid, potassium sorbate and the like which have side effects on human bodies, and can be used as a sour agent of the foods; in the production process of the beer, the pH value can be adjusted by using lactic acid, so that the saccharification of raw materials can be promoted, and the growth of mixed bacteria can be inhibited; lactic acid has many important applications in medical applications, both as a disinfectant and as a carrier; the solution prepared from sodium lactate can be used for treating acidosis and hyperkalemia; the lactate substances can be used as a solvent of the medicine, increase the absorption of the medicine by human body, reduce side effects, and can also be prepared into a lubricant of a tablet, wherein the lubricant is prepared from polylactic acid and is widely applied clinically, such as a slow release capsule preparation, a biodegradable surgical suture, a biological implantation tablet and the like; in the chemical industry, lactic acid is the main raw material of biodegradable plastic polylactic acid; the lactic acid can also be used in the leather manufacturing industry to ensure that the leather is soft and fine and the fiber is glossy; lactic acid can also be used as a synthetic resin coating, an adhesive, a perfume and a cleaning agent for petroleum pipelines.

Disclosure of Invention

In view of the above, the invention provides a process for directly purifying lactic acid from fermentation broth, which continuously separates lactic acid from materials in the production process, avoids the addition of calcium hydroxide and subsequent complex treatment steps, and has good purification effect.

In order to achieve the purpose, the invention adopts the following technical scheme:

a process for producing lactic acid with high purity and low energy consumption comprises the following steps:

(1) preparing raw materials: injecting a proper amount of water into the seasoning tank, heating the water to 50 ℃, opening the stirrer, pouring glucose powder, dissolving and stirring uniformly, adjusting the pH value to be between 5.5 and 6.0, and transferring the solution into a sugar solution storage tank for later use;

(2) heating and sterilizing: sterilizing material conveying equipment and fermentation equipment by adopting high-temperature steam, starting a material transferring pump after the material conveying equipment and the fermentation equipment are sterilized, enabling the material to enter a fermentation tank through an injection pump, simultaneously introducing the high-temperature steam into the injection pump, and heating and sterilizing the material by the high-temperature steam;

(3) fermentation: cooling the sterilized equipment and materials in the step (2) to 45-48 ℃, inoculating strains into a fermentation tank, starting fermentation, keeping the temperature in the fermentation tank at 45-50 ℃ and the pressure at 0.4-0.8 Mpa, performing primary separation by using an ultrafiltration membrane in the fermentation process, continuously separating the product lactic acid from the fermentation liquid, and continuously fermenting the trapped liquid;

(4) and (3) purification: sequentially passing the filtrate obtained in the step (3) through a carbon column, a cation exchange column and an anion exchange column to remove impurities, and then entering an ion exchange liquid storage tank;

(5) MVR evaporation and concentration: starting a vacuum pump and a steam compressor, starting steam, heating the system, evaporating and concentrating the ion exchange liquid obtained in the step (4), and pumping the concentrated liquid into a storage tank before the membrane;

(6) and (3) nanofiltration membrane filtration: adjusting the pressure difference between the feeding and the discharging to be less than or equal to 0.5Mpa, leading the concentrated solution obtained in the step (5) to pass through a nanofiltration membrane, filtering impurities, and leading the filtrate to enter a membrane post-tank;

(7) concentrating by a plate evaporator: pumping the filtrate obtained in the step (6) into a plate evaporator, wherein the feed flow rate is 5.2-6.0m³Heating by steam, controlling the air inlet pressure of a heat pump to be 0.35-0.4Mpa, controlling the discharge density to be 1.14-1.20kg/L, controlling the discharge concentration to reach more than 80%, and pumping into a finished product storage tank;

(8) blending and canning: and (5) detecting the material concentration in the finished product storage tank in the step (7), pumping the finished product into a blending tank according to the requirement, blending and canning.

By adopting the scheme, the invention provides the lactic acid production process without adding the calcium salt, in the lactic acid production process, the lactic acid is continuously filtered out from the fermentation tank by adopting the ultrafiltration membrane, alkali liquor is not required to be added for regulating the pH value, the acid inhibition effect is avoided, the complicated steps of flocculation, acidolysis, filter pressing and the like are avoided, the generation of a large amount of calcium sulfate waste in the filter pressing process is avoided, the waste of a large amount of water resources is avoided, the production process is simplified, and the preparation cost is saved.

Preferably, the adding amount of the glucose in the step (1) is adjusted according to the concentration required by production.

Preferably, the fermentation strain in the step (3) is fermented by rhizopus oryzae, the rhizopus oryzae is granular rhizopus oryzae which is cultured and self-flocculated by hypha, the volume of the inoculated mold liquid is 10-15% of the total volume of the feed liquid in the fermentation tank, and the added yeast powder accounts for 0.15-0.2% of the rhizopus oryzae.

The beneficial effects of the preferred technical scheme are as follows: the rhizopus oryzae needs to be immobilized to avoid the aggregation of a large amount of free hyphae to block the mass transfer of materials when the rhizopus oryzae is fermented to produce lactic acid, the rhizopus oryzae aggregated into small particles plays a self-curing role, the production efficiency of the lactic acid is ensured, the rhizopus oryzae particle strains are easy to separate from products and can be recycled, and the addition of yeast can accelerate the fermentation speed, shorten the fermentation period and increase the economic benefit.

Preferably, the feed liquid is diluted with ultrapure water before the ultrafiltration in the step (3).

The beneficial effects of the preferred technical scheme are as follows: dilution is beneficial to improving the retention rate of protein and the flux of the membrane.

Preferably, the ion exchange flow of the feed liquid in the step (4) is 7-12 m³/h，Fe^3﹢≤10PPm,Cl^﹣The color is less than or equal to 20PPm, and the APHA is qualified when the chroma is less than or equal to 50.

Preferably, the discharge density of MVR evaporation concentration in the step (5) is 1.116-1.118 kg/L.

Preferably, the water for blending the materials in the step (8) is softened tap water, and the conductivity of the softened tap water is less than or equal to 20 mu s/cm.

According to the technical scheme, compared with the prior art, the invention discloses a low-energy-consumption high-purity lactic acid preparation process, the product lactic acid is continuously filtered from a fermentation tank by adopting an ultrafiltration membrane in the lactic acid production process, alkali is not required to be added for regulating the pH value in the fermentation tank, impurities are prevented from being introduced, the acid inhibition effect is avoided, the complicated steps of acidolysis and plate-and-frame filter pressing are omitted, the energy consumption is reduced while a large amount of byproducts are avoided, the high environmental protection value and economic value are achieved, the invention adopts glucose as a raw material, rhizopus oryzae is used as a fermentation strain, in the preparation process, the rhizopus oryzae is self-agglomerated by hyphae of the rhizopus oryzae to form rhizopus oryzae pellets to achieve the self-solidification effect, the free hypha is prevented from being agglomerated in a large area to block the mass transfer of materials, and the strain is easy to separate from feed liquid after fermentation, the separated strain can be recycled, and importantly, the lactic acid product fermented by rhizopus oryzae has high optical purity and high utilization rate of raw materials, and the subsequent purification treatment steps are combined to ensure that the product lactic acid has high purity.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.