CN101691537A - Integrated processing method for byproducts in lignocellulose-refining fuel ethanol - Google Patents

Abstract

The invention relates to an integrated treatment method for by-products in refining fuel ethanol from lignocellulose. The main content of the present invention is to develop and utilize the by-products CO ₂ , lignin, pretreatment waste liquid, alcoholic yeast, and alcohol waste liquid in the lignocellulose refining process, and recover a small amount of by-product fusel oil and aldehyde in the production process ester. That is to integrate the treatment of waste gas, waste liquid and waste residue in the process of lignocellulose refining fuel ethanol into a symbiosis mode, which also includes energy integration and water integration. The method of the present invention utilizes the by-products produced in each step of the production process to maximize the utilization value of the by-products; develop and utilize each by-product in an environment-friendly and low-pollution approach to form a green industrial chain in a complete sense; from the overall point of view, Effectively match energy and water to reduce energy consumption and save water. Through the implementation of this scheme, the process of refining fuel ethanol from lignocellulose can not only realize zero discharge of waste, but also bring better economic benefits to enterprises.

Description

Integrated treatment of by-products from lignocellulosic refining of fuel ethanol

technical field

The invention relates to an integrated treatment method for by-products in lignocellulose refining fuel ethanol, which belongs to the research field of ecological industry and system engineering.

Background technique

In recent years, the oil crisis has promoted the rapid development of biomass refining fuel ethanol technology in countries all over the world. However, the emergence of the current food crisis has prompted researchers to develop various lignocellulosic biomass materials represented by crop straws to replace food resources to produce fuel ethanol.

Although the refining of fuel ethanol from lignocellulose is beneficial to environmental protection, its processing and conversion is a typical industrial process. If the by-products produced in the process of refining fuel ethanol from lignocellulose are unreasonably developed and utilized, not only will it cause serious environmental damage, It also causes waste of resources. The process of refining fuel ethanol from lignocellulose will produce by-products CO ₂ , lignin, pretreatment waste liquid, alcohol yeast, alcohol waste liquid, and a small amount of fusel oil and aldehyde ester. These waste gases, waste residues, and waste liquids have high utilization value. Rational development of these by-products and energy integration and water integration in the production process are important ways to solve the current low economic benefits of lignocellulose refining fuel ethanol.

At present, the utilization level of by-products in the process of refining fuel ethanol from lignocellulose is relatively low. The main way is to treat all waste liquids together and discharge them. The waste residues are used as fuel, and the development and utilization of other by-products are rarely considered. The main problem in doing so is: without analyzing the utilization value of the by-products produced in each step of the production process, it is only general to treat all waste liquids and waste residues together, so that the utilization value of by-products has not been maximized; no attention has been paid to the Development and utilization of by-products CO ₂ , alcoholic yeast and recovery of fusel oil and aldehyde ester in the production process. Potential waste heat resources are not recycled, resulting in a waste of resources.

Contents of the invention

The purpose of the present invention is to provide an integrated treatment method for by-products in lignocellulose refining fuel ethanol to solve the problem of current lignocellulose refining fuel ethanol. The problem of low economic benefit of producing fuel ethanol.

The present invention adopts following technical scheme:

An integrated treatment method for by-products in lignocellulose refining fuel ethanol, characterized in that the method includes pretreatment of waste liquid, CO ₂ produced by ethanol fermentation, lignin, alcohol yeast, alcohol waste liquid, and aldehyde ester treatment And energy integration and water integration, as follows:

a. Fermentation of pretreated waste liquid to produce single-cell protein: the pretreated waste liquid contains water-soluble hemicellulose and its hydrolyzed products xylose and arabinose, which are used as carbon sources and fermented with Dermatothrichum 851 strains, to produce single-cell proteins;

b. CO ₂ synthesis of fully degradable plastics: the purity of CO ₂ produced by ethanol fermentation is as high as 90%, and its purity meets the requirements for the production of degradable plastics; the collected CO ₂ is polymerized to obtain CO ₂ copolymers;

c. Production of liquid mulch from lignin;

d. isolate the yeast emulsion from the fermented mash, and directly use it as feed yeast;

e. Recovery of by-product fusel oil and aldehyde esters in the rectification process;

f. Gradual development and utilization of alcohol waste residues: alcohol waste residues are filtered, the filter residue is used to produce feed, the filtrate is fermented to generate biogas for power generation, the by-product biogas slurry of the biogas fermentation process is used for irrigation, and the biogas residue is used as organic fertilizer;

g. Energy integration approach: ferment alcohol waste residues to produce biogas, use the biogas to generate power for the system power supply; the steam generated by power generation is used for steam explosion pretreatment or ethanol distillation and rectification; use the hot water produced by biogas power generation to heat feed materials ; Use the waste heat at the top of the rectification tower to drive the absorption refrigerator to cool the ethanol fermentation liquid, and the high-temperature distillate in the distillation stage is used to heat the feed;

h. Water integration approach: reuse cooling water, such as cooling water for cleaning straw, mixing materials or water for washing; collect and clean straw water to be used for cleaning straw after simple filtration, and pre-treat waste water in the process of producing single-cell protein , after advanced treatment by membrane organisms, it can be reused as boiler water or water for mixing materials; waste heat (hot water) from biogas power generation is used as mixing materials; biogas slurry after biogas fermentation is used for agricultural irrigation; high-temperature distillate discharged from the distillation process is used for heating feed.

Compared with the existing ways of utilizing the by-products of lignocellulose refining fuel ethanol, the present invention has the following obvious substantive features and advantages: develop and utilize the by-products produced in each step of the production process, and maximize the utilization value of the by-products; By-products are developed and utilized in an environment-friendly and low-pollution way to form a green industrial chain in a complete sense. For example, CO ₂ is used as raw material to produce degradable plastics, and lignin is used as raw material to produce mulch film; taking into account the gradual utilization of by-products, such as the alcohol waste liquid is filtered, the filter residue is used to produce feed, the filtrate is fermented to produce biogas for power generation, and biogas fermentation The by-product biogas slurry is used for irrigation, and the biogas residue is used as organic fertilizer; from the overall point of view, energy and water can be effectively matched to reduce energy consumption and save water. Through the implementation of this scheme, the process of refining fuel ethanol from lignocellulose can not only realize zero discharge of waste, but also bring better economic benefits to enterprises.

Description of drawings

Figure 1 is a multi-product symbiosis model of lignocellulose refining ethanol.

Fig. 2 Energy integration of the multi-product symbiosis model.

Figure 3. Water integration in a multi-product symbiosis model.

Specific implementation methods

The present invention is implemented taking a fuel ethanol production enterprise with an annual output of 15,000 tons as an example, and the implementation method is referring to Fig. 1, 2, 3.

The first step: About one million tons of pretreatment waste liquid is produced every year. Collect the pretreated waste liquid in the steam explosion pretreatment stage, use it as a carbon source, put it into a fermenter, use Dermthrichum 851 as a fermentation strain, and use hot water at 75°C to extract steam-exploded lignocellulose for removal. At the same time, hemicellulose hydrolyzate is used for high-density single-cell protein fermentation, and the protein content of the obtained dry bacterial powder reaches 46%; the main process flow: steam explosion of hemicellulose hydrolyzate→repeated fed-batch fermentation→fermentation liquid Concentration→spray drying. For the detailed production method, refer to Chen Hongzhang's "Study on Continuous Fermentation of Hemicellulose Steam Explosion Hydrolyzate to Produce Single Cell Protein";

Step 2: About 10,000 tons of CO ₂ can be collected annually. The purity of CO ₂ produced by ethanol fermentation meets the requirements for the production of degradable plastics. CO ₂ is collected during the fermentation stage, and the combination catalyst of epoxy compound and rare earth is added to the pre-dried high-pressure reactor, and then a 515-610MPa CO ₂ , at a temperature of 60-80°C, adjust the stirring speed of the motor, react for 14 hours, and polymerize to obtain a CO ₂ copolymer; the specific production technology refers to Gao Jianping's "Synthesis of Biodegradable Plastics with Carbon Dioxide and Epoxy Compounds";

Third: About 15,000 tons of lignin can be recovered annually. Separate lignin from waste liquid, add a small amount of formaldehyde to the lignin solution as a cross-linking agent, add a small amount of short fibers or other soluble polymer compounds, and add some surfactants and foaming agents. The liquid mixture is sprayed onto the soil surface with a sprayer to form a thick layer of uniform foam. After defoaming, a uniform layer of plastic film is formed on the soil surface; for specific production techniques, refer to Jiang Tingda's "Lignin";

Fourth: About 1,000 tons of alcoholic yeast are collected annually. The yeast emulsion can be directly used as feed yeast by separating the yeast emulsion from the waste liquid; for the specific method, please refer to Ma Xiaojian's "Fuel Ethanol Production and Application Technology";

Fifth: Separating fusel oil and aldehyde ester from the rectification tower, about 75 tons of fusel oil and 300 tons of aldehyde ester can be recovered annually. For the specific recovery method, refer to Ma Xiaojian's "Fuel Ethanol Production and Application Technology";

Sixth: About 220,000 tons of alcohol waste liquid is produced annually. In the distillation stage, the waste alcohol waste liquid is collected, filtered, and the filtrate is put into the fermenter for biogas fermentation, and the biogas is collected for power generation, and the filter residue is dried to make DDG; then the biogas fermentation liquid is filtered to produce biogas slurry For irrigation, biogas residue is used as organic fertilizer to condition the soil. . For the specific method, refer to Liu Ronghou's "Production Process and Examples of Fuel Ethanol";

Specific implementation methods for energy integration: ferment alcohol waste residues to produce biogas, use the biogas to generate power for the system; steam generated by power generation is used for steam explosion pretreatment or ethanol distillation and rectification; use the hot water produced by biogas power generation to heat feed materials ;Use the waste heat at the top of the rectification tower to drive the absorption refrigerator to cool the ethanol fermentation liquid, and the high-temperature distillate in the distillation stage is used to heat the feed. For specific methods, refer to Wang Sheng's "Lithium Bromide Absorption Refrigerator and Its Advantages and Disadvantages"

Specific implementation methods of water integration: reuse cooling water, such as cooling water for cleaning straw, mixing materials or water for washing; collect and clean straw water to be used for cleaning straw after simple filtration, and pre-treat waste water in the process of producing single-cell protein , after advanced treatment by membrane organisms, it can be reused as boiler water or water for mixing materials; waste heat (hot water) from biogas power generation is used as mixing materials; biogas slurry after biogas fermentation is used for agricultural irrigation; high-temperature distillate discharged from the distillation process is used for heating feed.

Claims (1)

1. An integrated treatment method for by-products in lignocellulose refining fuel ethanol, characterized in that the method includes pretreatment waste liquid, CO ₂ produced by ethanol fermentation, lignin, alcohol yeast, alcohol waste liquid, aldehyde Ester processing and energy integration and water integration, as follows: a. Fermentation of pretreated waste liquid to produce single-cell protein: the pretreated waste liquid contains water-soluble hemicellulose and its hydrolyzed products xylose and arabinose, which are used as carbon sources and fermented with Dermatothrichum 851 strains, to produce single-cell proteins; b. CO ₂ synthesis of fully degradable plastics: the purity of CO ₂ produced by ethanol fermentation is as high as 90%, and its purity meets the requirements for the production of degradable plastics; the collected CO ₂ is polymerized to obtain CO ₂ copolymers; c. Production of liquid mulch from lignin; d. isolate the yeast emulsion from the fermented mash, and directly use it as feed yeast; e. Recovery of by-product fusel oil and aldehyde esters in the rectification process; f. Gradual development and utilization of alcohol waste residues: alcohol waste residues are filtered, the filter residue is used to produce feed, the filtrate is fermented to generate biogas for power generation, the by-product biogas slurry of the biogas fermentation process is used for irrigation, and the biogas residue is used as organic fertilizer; g. Energy integration approach: ferment alcohol waste residues to produce biogas, use the biogas to generate power for the system power supply; the steam generated by power generation is used for steam explosion pretreatment or ethanol distillation and rectification; use the hot water produced by biogas power generation to heat feed materials ; Use the waste heat at the top of the rectification tower to drive the absorption refrigerator to cool the ethanol fermentation liquid, and the high-temperature distillate in the distillation stage is used to heat the feed; h. Water integration approach: reuse cooling water, such as cooling water for cleaning straw, mixing materials or water for washing; collect and clean straw water to be used for cleaning straw after simple filtration, and pre-treat waste water in the process of producing single-cell protein , after advanced treatment by membrane organisms, it can be reused as boiler water or water for mixing materials; waste heat (hot water) from biogas power generation is used as mixing materials; biogas slurry after biogas fermentation is used for agricultural irrigation; high-temperature distillate discharged from the distillation process is used for heating feed.

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