Method for synthesizing green methanol by coupling anaerobic fermentation and gasification of vinasse

Abstract

The invention belongs to the technical field of biomass waste resource utilization, and relates to a method for synthesizing green methanol by utilizing vinasse anaerobic fermentation coupled gasification, which comprises an anaerobic fermentation stage; a pyrolysis gasification stage and a gas tempering synthesis stage. According to the method, the vinasse is treated by coupling anaerobic fermentation with pyrolysis gasification, so that the utilization rate of the vinasse is remarkably increased, the yield of methanol converted from the vinasse is 34.1% and is higher than 27.4% of the yield of methanol converted from the vinasse by traditional independent gasification treatment, and meanwhile, the problems of carbon utilization efficiency and hydrogen supplementation are solved. Meanwhile, the optimized biomass vinasse is used as the raw material, the yield of the vinasse is large and concentrated, and compared with other biomass such as straw, the vinasse is easier to collect, so that sufficient raw material guarantee is provided for large-scale green methanol production. Secondly, the vinasse is stable in property and uniform in particle, and subsequent processing is facilitated; other chemical reagents are not introduced in the whole technological process, so that the method is environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of biomass waste resource utilization, and specifically relates to a method for synthesizing green methanol by coupling anaerobic fermentation of distiller's grains with gasification. Background Art

[0003] Biomass pyrolysis and gasification can produce synthesis gas mainly composed of H2, CO and CO2. After purification and conditioning, methanol can be synthesized under certain temperature, pressure and catalyst conditions. However, the use of biomass to synthesize methanol faces problems such as low gasification efficiency, low hydrogen-carbon ratio of synthesis gas, and tar in synthesis gas, resulting in low overall efficiency of biomass to methanol conversion. At the same time, due to the low energy density of biomass resources themselves, scattered distribution, and difficulty in collection, the overall economic benefits of synthesizing green methanol from biomass are poor.

[0004] In view of the above problems, the present invention proposes a method for synthesizing green methanol to improve the overall efficiency of biomass to methanol conversion and the overall economic benefits of synthesizing green methanol from biomass. Summary of the invention

[0005] The purpose of the present invention is to provide a method for synthesizing green methanol by coupling anaerobic fermentation of distiller's grains with gasification, so as to solve the problem of low conversion efficiency of biomass raw materials into methanol.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] A method for synthesizing green methanol by coupling anaerobic fermentation of distiller's grains with gasification comprises the following steps:

[0008] Step 1, anaerobic fermentation stage: using vinasse powder as raw material and anaerobic sludge as inoculum to perform anaerobic fermentation treatment to obtain fermentation residues, namely biogas, biogas liquid and biogas residue;

[0009] Step 2, pyrolysis and gasification stage: filtering the biogas slurry and biogas residue obtained in step 1 to achieve solid-liquid separation of the fermentation residue, thereby obtaining biogas residue, drying it to constant weight for gasification reaction, and collecting solid phase products, gas phase products and liquid phase products after the reaction is completed;

[0010] Step 3, gas conditioning synthesis stage: steam reforming reaction is performed on the biogas obtained in step 1 and the methane in the gas phase product obtained in step 2 to obtain H2 and CO, and H2 and CO are mixed with the remaining gas from the gas phase product obtained in step 2 after removing methane, and CO is reacted with water vapor to obtain H2 and CO2, which are further reformed and conditioned to obtain H2 and CO2, so that the mixed gas H2:CO reaches 2:1. Then the mixed gas is desulfurized and CO2 is separated, and compressed to synthesize green methanol.

[0011] Furthermore, the lees powder is powder of Luzhou-flavor liquor lees, and the content ratios of rice husk, grain residue and residual sugar in the lees are in the range of 75% to 80%, 10% to 15% and 4% to 5%, the mass content of lees volatile matter is higher than 76% and the particle size is 20 to 60 meshes.

[0012] Furthermore, the conditions of the anaerobic fermentation treatment in step 1 are: the organic load is 30-34 gTS / L, the temperature is maintained at 36-38°C; the fermentation cycle is 18-20 days, the total solid content TS is 9%-11%, and gas is collected daily according to the set fermentation time, and finally the biogas, biogas slurry and biogas residue are unloaded.

[0013] Furthermore, in step 1, the anaerobic fermentation experiment uses a 2.5-3L reaction bottle with an effective volume of 1.5-1.8L. The reaction bottle is placed in a water bath to keep warm with circulating hot water. During the fermentation process, the anaerobic fermentation system is artificially shaken for 2-5 minutes every two days to prevent slagging on the surface of the fermentation system.

[0014] Furthermore, the method of using vinasse powder as raw material and anaerobic sludge as inoculum for anaerobic fermentation to obtain the fermentation residue is:

[0015] After sampling, the lees are naturally air-dried, crushed, and placed in a cool and dry place for later use;

[0016] Before the anaerobic fermentation experiment, the anaerobic sludge inoculum was activated in a constant temperature water tank at 36-38°C to ensure the activity of the microorganisms therein;

[0017] Adding 54-56 g of vinasse powder and 748-752 g of inoculum into a reaction bottle for fermentation reaction to obtain a fermentation residue;

[0018] Biogas is collected daily using gas bags, and the gas components in the biogas are measured by gas chromatography to determine the daily methane production. The gas volume is also measured to determine the daily gas production;

[0019] Furthermore, in step 2, a 200-mesh nylon filter is used to separate the fermentation residue into solid and liquid, and the solid obtained by filtration is placed in an oven at 105±1°C and dried to constant weight, and then crushed through a 20-60 mesh sieve, and the obtained dried biogas residue is placed in a ziplock bag and sealed for storage.

[0020] Furthermore, the obtained biogas residue is used for gasification experiment, and the method for collecting the solid phase product, gas phase product and liquid phase product after the reaction is completed is as follows:

[0021] Add 10g of biogas residue into the hanging basket of the electric heating fixed bed gasifier and introduce a gasifying agent, wherein the gasifying agent is water vapor and CO2, the ratio of water vapor to biomass in the gasification atmosphere is 2:1-3:1, and the reaction temperature is 750-850°C;

[0022] After reaching the set gasification time of 15 to 20 minutes, the tar is collected using a condenser and dichloromethane, and the gas phase products are collected using an air bag. After the hanging basket is cooled to room temperature, the charcoal yield is obtained using the difference method.

[0023] Furthermore, the solid phase product collected after the reaction is finished is dried to a water content of less than 20% and used as a gasification raw material.

[0024] Furthermore, the volume ratio of the biogas in the gas conditioning synthesis stage to the gas phase product in step 2 is 4:9.

[0025] Furthermore, the biogas obtained in step 1 and the methane in the gas phase product obtained in step 2 are subjected to steam reforming reaction to obtain H2 and CO, and the H2 and CO are mixed with the remaining gas from the gas phase product obtained in step 2 after removing methane, and CO is reacted with water vapor to obtain H2 and CO2, which are further reformed and tempered to obtain H2 and CO2. The chemical equation of the methane steam reforming and CO tempering reaction is as follows:

[0026] CH4+H2O=CO+3H2

[0027] CO+H2O=CO2+H2

[0028] Furthermore, in step 3, the synthesis gas collected above is desulfurized and decarbonized and then compressed to synthesize crude methanol, and then the crude methanol is distilled to obtain a green methanol product.

[0029] The advantages and positive effects of the present invention are:

[0030] The method for synthesizing green methanol by coupling anaerobic fermentation of distiller's grains with gasification uses anaerobic fermentation coupled with pyrolysis and gasification to treat distiller's grains, which significantly improves the utilization rate of distiller's grains. The yield of methanol from distiller's grains is 34.1%, which is higher than the 27.4% of traditional single gasification treatment, and solves the problem of carbon utilization efficiency and hydrogen replenishment at the same time.

[0031] At the same time, the present invention uses the preferred biomass distiller's grains as raw materials, which have a large and concentrated output and are easier to collect than other biomass such as straw, which provides sufficient raw material guarantee for large-scale green methanol production. Secondly, the distiller's grains are stable in nature and have uniform particles, which is conducive to subsequent processing;

[0032] In addition, the entire process of the present invention does not introduce other chemical reagents and is environmentally friendly. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are further described below:

[0034] The present invention utilizes wine grains as raw materials and realizes efficient conversion of biomass into methanol by means of anaerobic fermentation coupled with pyrolysis and gasification, so as to solve the problem of adjusting the hydrogen-to-carbon ratio of low-cost biomass gasification.

[0035] Example

[0036] A method for synthesizing green methanol by coupling anaerobic fermentation of distiller's grains with gasification, the innovation of which is that it comprises the following steps:

[0037] 56 g of vinasse and 750 g of inoculum were added to a 2.5 L reaction bottle with an effective volume of 1.5 L, so that the organic load of the fermentation system was 34 g TS / L, and the fermentation cycle was set to 20 days;

[0038] The reaction system maintains the fermentation temperature at 37±1℃ through a circulating water bath, and shakes it every two days to avoid surface hardening and slagging;

[0039] Replace the gas bag every day, measure the daily gas production and gas composition, and stop collecting gas when the daily gas production drops below 10% of the average daily gas production;

[0040] After stopping gas collection, unload the material and use a 200-mesh nylon filter to separate the solid and liquid of the fermentation residue;

[0041] The filtered solid was placed in an oven at 105°C to dry completely, then crushed through a 20-mesh sieve, and the obtained biogas residue was sealed in a ziplock bag for storage;

[0042] 10 g of biogas residue was added to the fixed bed gasifier and water vapor and CO2 were introduced as gasifying agents for gasification reaction. The reaction temperature was 800 °C and the reaction time was set to 15 min.

[0043] After the reaction is finished, the tar is washed and collected with dichloromethane, the synthesis gas is collected with a gas bag, and the char is collected after the gasifier is cooled to room temperature;

[0044] The synthesis gas obtained above was wet reformed and tempered together with the obtained gasification gas. After the gas ratio was adjusted, 4.26 g of crude methanol was obtained and 3.41 g of the final green methanol product was obtained after distillation.

[0045] Comparative Example

[0046] Biomass gasification to produce green methanol

[0047] 10g of biomass, i.e., wine lees, was added to the fixed bed gasifier, and water vapor was introduced as a gasifying agent for gasification reaction. The reaction temperature was 800℃ and the reaction time was set to 15min;

[0048] After the reaction is finished, the tar is washed and collected with dichloromethane, the synthesis gas is collected with a gas bag, and the char is collected after the gasifier is cooled to room temperature;

[0049] After conditioning the synthesis gas obtained above, the gas ratio was adjusted to synthesize 3.42 g of crude methanol, and after distillation, 2.74 g of the final green methanol product was obtained.

[0050] Based on the above experimental data, it can be seen that one ton of biomass with a water content of 10% can produce 149.2 m 3 The biogas and 0.675 tons of biogas residue were wet reformed to obtain 596.7m3 methanol synthesis gas. 3 The biogas residue was simultaneously gasified with steam to obtain 641.25m 3 Methanol synthesis gas, after conditioning, can be used for synthesis to obtain 0.425 tons of crude methanol, and after distillation, 0.341 tons of final green methanol product can be obtained. In the comparative example, one ton of water content is 10% and water vapor is gasified in a biomass gasifier to obtain 0.342 tons of crude methanol, which can be distilled to obtain 0.274 tons of final green methanol product.

[0051] It can be seen that the green methanol conversion efficiency of the embodiment of the present invention, which is 34.1%, is significantly higher than the conversion efficiency of 27.4% of the comparative example, compared with the conventional single-route gasification to produce methanol or only anaerobic fermentation process route, by treating distiller's grains with anaerobic fermentation coupled with pyrolysis and gasification process to prepare green methanol.

[0052] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for synthesizing green methanol by coupling anaerobic fermentation of distiller's grains with gasification, characterized in that: The following steps are involved: Step 1, anaerobic fermentation stage: using vinasse powder as raw material and anaerobic sludge as inoculum to perform anaerobic fermentation treatment to obtain fermentation residues, which are biogas, biogas liquid and biogas residue; Step 2, pyrolysis and gasification stage: filtering the biogas slurry and biogas residue obtained in step 1 to achieve solid-liquid separation of the fermentation residue, thereby obtaining biogas residue, drying the biogas residue to constant weight for gasification reaction, and collecting solid phase products, gas phase products and liquid phase products after the reaction is completed; Step 3, gas conditioning and synthesis stage: steam reforming the biogas obtained in step 1 and the methane in the gas phase product obtained in step 2 to obtain H2 and CO. H2 and CO are then mixed with the remaining gas from the gas phase product obtained in step 2 after removing methane, and CO is reacted with water vapor to obtain H2 and CO2, which are further reformed and conditioned to make the mixed gas H2:CO reach 2:1, and then the mixed gas is desulfurized and CO2 is separated, and compressed to synthesize green methanol.

2. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: The lees powder is powder of Luzhou-flavor liquor lees, and the content ratios of rice husk, grain residue and residual sugar in the lees are in the range of 75% to 80%, 10% to 15% and 4% to 5%, the mass content of lees volatile matter is higher than 76% and the particle size is 20 to 60 meshes.

3. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: The conditions of the anaerobic fermentation treatment in step 1 are: the organic load is 30-34 gTS / L, the temperature is maintained at 36-38°C; the fermentation cycle is 18-20 days, the total solid content TS is 9%-11%, and gas is collected daily according to the set fermentation time, and finally unloaded to obtain biogas, biogas liquid and biogas residue.

4. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: In step 1, the anaerobic fermentation experiment uses a 2.5-3L reaction bottle with an effective volume of 1.5-1.8L. The reaction bottle is placed in a water bath and kept warm by circulating hot water. During the fermentation process, the anaerobic fermentation system is artificially shaken for 2-5 minutes every two days to prevent slagging on the surface of the fermentation system.

5. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: The method of using vinasse powder as raw material and anaerobic sludge as inoculum to perform anaerobic fermentation to obtain fermentation residues, wherein the fermentation residues are biogas, biogas liquid and biogas residues, is as follows: After sampling, the lees are naturally air-dried, crushed, and placed in a cool and dry place for later use; Before the anaerobic fermentation experiment, the anaerobic sludge inoculum was bottled and placed in a constant temperature water tank at 36-38℃ to activate it to ensure the activity of the microorganisms therein; Add 54-56g of vinasse powder and 748-752g of inoculum into the reaction bottle for fermentation reaction, and obtain fermentation residue after the reaction cycle ends. The fermentation residue is biogas, biogas liquid and biogas residue; Biogas is collected daily using gas bags, and the gas components in the biogas are measured by gas chromatography to determine the daily methane production. The gas volume is also measured to determine the daily gas production; Use a 200-mesh nylon filter to separate the solid-liquid separation of the biogas slurry and the biogas residue. Place the filtered solid in an oven at 105±1℃ and dry it to constant weight. Then crush it through a 20-60 mesh sieve. Place the dried biogas residue in a ziplock bag and seal it for storage.

6. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: The biogas slurry and biogas residue obtained in step 1 are filtered to achieve solid-liquid separation of the fermentation residue, thereby obtaining biogas residue, which is dried to a constant weight for gasification reaction, and after the reaction is completed, solid phase products, gas phase products and liquid phase products are collected and obtained by the method of: Add 10g of biogas residue into the hanging basket of the electric heating fixed bed gasifier and introduce a gasifying agent, wherein the gasifying agent is water vapor and CO2, the ratio of water vapor to biomass in the gasification atmosphere is 2:1-3:1, and the reaction temperature is 750-850°C; After reaching the set gasification time of 15 to 20 minutes, the tar is collected using a condenser and dichloromethane, and the gas phase products are collected using an air bag. After the hanging basket is cooled to room temperature, the charcoal yield is obtained using the difference method.

7. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: The biogas residue collected after the reaction is dried to a water content of less than 20% and used as a gasification raw material.

8. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: The volume ratio of biogas in the gas conditioning synthesis stage to the gas phase product in step 2 is 4:

9.

9. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: The biogas obtained in step 1 and the methane in the gas phase product obtained in step 2 are subjected to steam reforming reaction to obtain H2 and CO, and the H2 and CO are mixed with the remaining gas in the gas phase product obtained in step 2 after removing methane, and CO is reacted with water vapor to obtain H2 and CO2, and further reformed and tempered to obtain H2 and CO2. The chemical equation of the methane steam reforming and CO tempering reaction is as follows: CH4+H2O=CO+3H2 CO+H2O=CO2+H2.

10. The method for synthesizing green methanol by anaerobic fermentation coupled with gasification of wine lees according to claim 1, characterized in that: In step 3, the synthesis gas collected above is desulfurized and decarbonized and then compressed to synthesize crude methanol, and then the crude methanol is distilled to obtain a green methanol product.