阅读说明：本技术 一种生物柴油副产甘油的提纯工艺 (Purification process of biodiesel byproduct glycerol ) 是由 张家鹏 雷世勇 张军涛 于 2019-11-14 设计创作，主要内容包括：本发明提供一种生物柴油副产甘油的提纯工艺,甘油的提纯过程包括水洗、酸洗、絮凝和真空脱水步骤,在水洗过程采用饱和食盐水代替普通的纯水,在絮凝过程还添加改性壳聚糖絮凝剂进行了二次絮凝,采用本发明的甘油提纯工艺,粗甘油中的甘油成分近乎全部回收,回收的甘油的纯度可达到92.5-97.6%,另外,甘油中脂肪酸及酯类化合物含量降低至0.10-0.35%,实现了甘油纯度的提高以及回收效率的提高,同时生产工艺简单,成本较低,适用于大规模甘油提纯的应用。(The invention provides a purification process of biodiesel byproduct glycerol, wherein the purification process of the glycerol comprises the steps of washing, acid washing, flocculation and vacuum dehydration, saturated saline water is adopted to replace common pure water in the washing process, and a modified chitosan flocculating agent is also added in the flocculation process to carry out secondary flocculation.)

1. A purification process of biodiesel byproduct glycerol is characterized by comprising the steps of water washing, acid washing, flocculation and vacuum dehydration, wherein the water washing is carried out by adopting saturated salt water washing, and the mass ratio of crude glycerol to saturated salt water is 8-9: 1; the molecular weight of the polyacrylamide is 1000-1200 ten thousand; the addition amount of polyacrylamide is 4-6% of the total amount of the solution.

2. The purification process according to claim 1, wherein the washing temperature is 50-60 ℃, the washing time is 30-40min, and the heat preservation and standing time is 1-1.5 h.

3. The purification process according to claim 1, wherein the acid washing is carried out, and an acid is added to adjust the pH to 1-2, wherein the acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid.

4. The purification process according to claim 1, wherein the flocculation is performed at a solution pH of 8-9, a stirring speed of 80-100r/min and a stirring time of 3-5 h.

5. The purification process of claim 1, wherein the flocculation further comprises a secondary flocculation,

and in the second-stage flocculation, adding a modified chitosan flocculant, adding phosphoric acid to adjust the pH value to 1-3, and accelerating the stirring at the speed of 500-550r/min for vigorously stirring for 60-90 min.

6. The purification process of claim 5, wherein the secondary flocculation modified chitosan flocculant is added in an amount of 0.3-0.8% by weight based on the total weight of the sweet water.

7. The purification process of claim 6, wherein the modified chitosan flocculant is prepared by the following steps: adding chitosan solid into water, adding lactic acid to adjust pH to 3-5, adding polyvinyl alcohol to prepare a chitosan solution with mass concentration of 2.5-5%, then adding polymerized aluminum ferric silicate into the chitosan solution for a few times while stirring, and distilling and drying under reduced pressure to obtain the chitosan/aluminum/iron composite material.

8. The purification process of claim 7, wherein the modified chitosan flocculant comprises the following raw materials: chitosan, polyvinyl alcohol and polymeric aluminum ferric silicate, wherein the ratio of the chitosan to the polyvinyl alcohol to the polymeric aluminum ferric silicate is 6-9:3-4: 1.

9. The purification process as claimed in claim 8, wherein the degree of deacetylation of the chitosan is 85-95%, and the particle size is 100-130 mesh; the content of the polymeric aluminum ferric silicate, the flaky particles and the effective substances is 36-40%.

10. The purification process of claim 1, wherein the vacuum dehydration is carried out at a temperature of 75-80 ℃ under a vacuum of 0.04-0.05 MPa.

Technical Field

The invention belongs to the technical field of biology, and particularly relates to a process for purifying glycerol as a byproduct of biodiesel.

Background

With the increasing demand of the world at present for replaceable clean renewable fuels, the technology of replacing fossil fuel diesel with biodiesel is widely supported, with the active deepening of the research of the biodiesel and the mass production of the biodiesel, the yield of the byproduct crude glycerol is also rapidly increased, 100kg of byproduct crude glycerol can be generated every 1t of biodiesel is produced, the development and utilization of the byproduct glycerol are improved, the comprehensive utilization rate and the economical efficiency of the whole process are improved, and the source of the glycerol is increased. The common biodiesel byproduct, namely crude glycerol, has the glycerol content of about 30-50%, also contains various components such as grease, saponified substances, colloidal protein, inorganic salt and the like, has complex components, and is difficult to separate and recover by adopting a physical method.

The invention patent CN109721471A discloses a method for purifying glycerin from a by-product of biodiesel production, which adopts an ion exchange mode to purify crude glycerin by respectively passing through acidic cation exchange resin and basic anion exchange resin, but the recovery cost of the process is very high, organic molecules are easy to cause the pollution of the exchange resin, and the process is not suitable for large-scale glycerin recovery.

The invention patent CN109020785A provides a method for refining and purifying glycerin generated in the biodiesel production process, which improves the purity of glycerin by low-pressure distillation and decolorization, but does not disclose the purity index of glycerin, and in addition, from the treatment process, saponificate, gliadin, etc. in the biodiesel by-product cannot be effectively separated and recovered.

Disclosure of Invention

In order to solve the problems in the prior art and further optimize the prior art, the invention provides a purification process of biodiesel byproduct glycerol, so as to achieve the purposes of improving the glycerol recovery efficiency and the glycerol purity.

In order to solve the technical problems, the invention adopts the following technical scheme:

a purification process of biodiesel byproduct glycerol comprises the steps of water washing, acid washing, flocculation and vacuum dehydration:

the water washing is carried out by adopting saturated salt water washing, the water washing temperature is 50-60 ℃, the water washing time is 30-40min, and the heat preservation and standing time is 1-1.5 h; the mass ratio of the crude glycerol to the saturated salt water is 8-9: 1;

the acid washing is carried out, and acid is added to adjust the pH value to 1-2, wherein the acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid;

during the flocculation, firstly adding polyacrylamide, adding caustic soda flakes to adjust the pH value to 8-9, stirring at the rotating speed of 80-100r/min, and continuously stirring for 3-5 h; then filtering and separating, wherein the main component of the filter cake is organic protein colloid, and the filter cake enters a fertilizer making workshop to be prepared into the biological organic fertilizer through aerobic fermentation;

the molecular weight of the polyacrylamide is 1000-1200 ten thousand; the adding amount of the polyacrylamide accounts for 4-6% of the total amount of the solution;

the flocculation also comprises secondary flocculation, wherein the secondary flocculation is to add a modified chitosan flocculant, add phosphoric acid to adjust the pH value to 1-3, accelerate the speed to 500-550r/min and stir for 60-90min violently;

the secondary flocculation is carried out, wherein the addition amount of the modified chitosan flocculant is 0.3-0.8% of the total weight of the sweet water;

the preparation method of the modified chitosan flocculant comprises the following steps: adding chitosan solid into water, adding lactic acid to adjust pH to 3-5, adding polyvinyl alcohol to prepare a chitosan solution with mass concentration of 2.5-5%, then adding a small amount of polymeric aluminum ferric silicate into the chitosan solution while stirring, and distilling under reduced pressure and drying to obtain the chitosan-based water-soluble chitosan;

the modified chitosan flocculant comprises the following raw materials: chitosan, polyvinyl alcohol and polymeric aluminum ferric silicate, wherein the ratio of the chitosan to the polyvinyl alcohol to the polymeric aluminum ferric silicate is 6-9:3-4: 1;

the chitosan has the deacetylation degree of 85-95 percent and the granularity of 100-130 meshes;

the content of the polymeric aluminum ferric silicate, flaky particles and effective substances is 36-40%;

and (3) performing vacuum dehydration, raising the temperature to 75-80 ℃, controlling the vacuum degree to be 0.04-0.05MPa, recycling the recovered water, desalting in a desalter after 80-85% of the total amount of the dehydrated water is removed, and putting the desalted water into a glycerol storage tank after the qualified test.

By adopting the technical scheme, the invention has the beneficial effects that:

1. by adopting the purification process, the purity of the glycerol can be improved, and the purity of the recovered glycerol reaches 92.5-97.6%;

2. by adopting the purification process, the recovery efficiency of the glycerin component in the crude glycerin can reach 95-98.5%, and the glycerin component can be basically and completely recovered;

3. by adopting the purification process, the content of fatty acid and ester compounds in the glycerol is reduced to 0.10-0.45%, the acidity is 0.037-0.088 mmol/100g, and the saponification equivalent is 1.21-2.53mmol/100 g;

4. by adopting the purification process, the glycerol can be purified, the oil in the glycerol can be recycled, and the colloid protein in the glycerol enters a fertilizer making workshop and is prepared into the bio-organic fertilizer through aerobic fermentation, so that various components are fully recovered, and the added value of the product is increased.

The specific implementation mode is as follows:

the invention is further illustrated below with reference to specific examples.