Water electrolysis hydrogen production coupling anaerobic fermentation device and biogas production method

Abstract

The invention belongs to the technical field of synergy of biological energy sources and renewable energy sources, and particularly relates to a water electrolysis hydrogen production coupling anaerobic fermentation device and a method for producing biogas. The water electrolysis hydrogen production coupling anaerobic fermentation device comprises a generator set, a PEM electrolytic bath, a first-stage fermentation tank and a second-stage fermentation tank, an oxygen outlet of the PEM electrolytic cell is communicated with a gas inlet of the first-stage fermentation tank, a discharge port of the first-stage fermentation tank is communicated with a feed port of the second-stage fermentation tank, and a hydrogen outlet of the PEM electrolytic cell is communicated with a gas inlet of the second-stage fermentation tank; and the generator set provides electric energy for the PEM electrolytic bath. The device has the beneficial effects that renewable energy sources wind energy and solar energy are utilized to generate power, a power supply is provided for electrolyzed water to produce hydrogen, and the generated hydrogen and oxygen are directionally injected into an organic waste fermentation system; and by adjusting the introduction amount of hydrogen, the yield of biogas generated by fermentation is increased, the purity and the carbon neutralization efficiency of the biogas are improved, and hydrogen and oxygen generated by electrolysis are reasonably utilized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of bioenergy and renewable energy synergy, and particularly relates to a device for electrolysis of water to produce hydrogen coupled with anaerobic fermentation and a method for producing biogas. BACKGROUND

[0002] Currently, electrolysis of water driven by renewable energy such as wind power and photovoltaic power can achieve zero-carbon hydrogen production, but the oxygen generated by electrolysis is usually directly discharged, causing resource waste; the cost of hydrogen storage and transportation is high, and a local application scenario needs to be found.

[0003] Traditional anaerobic fermentation treatment of organic waste (such as straw and kitchen waste) has low carbon conversion rate (only 40-60%) and inhibitory gases such as hydrogen sulfide, which leads to system instability; the methane content is low (55-65%) and the purification cost is high. SUMMARY

[0004] The present application provides a device for electrolysis of water to produce hydrogen coupled with anaerobic fermentation and a method for producing biogas, which solves the problem of storage and transportation of hydrogen produced by wind and light electrolysis of water, provides a local application scenario; at the same time, the use of hydrogen and oxygen improves the biogas yield of the anaerobic fermentation system and the methane content in the biogas.

[0005] The first aspect of the present application provides a device for electrolysis of water to produce hydrogen coupled with anaerobic fermentation, comprising a generator set, a PEM electrolysis cell, a primary fermentation tank and a secondary fermentation tank; the oxygen outlet of the PEM electrolysis cell is in communication with the gas inlet of the primary fermentation tank, the discharge outlet of the primary fermentation tank is in communication with the feed inlet of the secondary fermentation tank, and the hydrogen outlet of the PEM electrolysis cell is in communication with the gas inlet of the secondary fermentation tank; the generator set provides electric energy for the PEM electrolysis cell.

[0006] The device for electrolysis of water to produce hydrogen coupled with anaerobic fermentation described in the present application uses renewable energy such as wind energy and solar energy to generate electricity, electrolyzes water to produce hydrogen, and directs the produced hydrogen and oxygen into an organic waste fermentation system to improve the biogas yield and the methane content in the biogas produced by fermentation, improve the purity and carbon neutralization efficiency, and reasonably utilize the hydrogen and oxygen produced by electrolysis.

[0007] According to some embodiments of the device for electrolysis of water to produce hydrogen coupled with anaerobic fermentation described in the present application, the oxygen outlet of the PEM electrolysis cell is in communication with an oxygen storage tank through a pipeline, and the oxygen storage tank is in communication with the gas inlet of the primary fermentation tank.

[0008] According to some embodiments of the device for electrolysis of water to produce hydrogen coupled with anaerobic fermentation described in the present application, an oxygen flow control valve is arranged on the pipeline connecting the oxygen storage tank and the gas inlet of the primary fermentation tank.

[0009] According to some embodiments of the water electrolysis hydrogen production coupled anaerobic fermentation device, the hydrogen outlet of the PEM electrolytic cell is connected to a hydrogen storage tank, and the hydrogen storage tank is connected to the gas inlet of the secondary fermentation tank.

[0010] According to some embodiments of the water electrolysis hydrogen production coupled anaerobic fermentation device, a hydrogen flow control valve is arranged on the pipeline connecting the hydrogen storage tank and the gas inlet of the secondary fermentation tank.

[0011] According to some embodiments of the water electrolysis hydrogen production coupled anaerobic fermentation device, a dissolved oxygen sensor is arranged in the primary fermentation tank.

[0012] According to some embodiments of the water electrolysis hydrogen production coupled anaerobic fermentation device, a VFA sensor is arranged in the secondary fermentation tank.

[0013] The second aspect of the present application provides a method for producing biogas, which uses the water electrolysis hydrogen production coupled anaerobic fermentation device of the first aspect of the present application.

[0014] According to some embodiments of the method for producing biogas, the method comprises the following steps:

[0015] A generator set is electrically connected to the PEM electrolytic cell to electrolyze water to generate hydrogen and oxygen; organic waste is added to the primary fermentation tank and oxygen is introduced for primary fermentation; after the primary fermentation is completed, the primary fermentation product is flowed into the secondary fermentation tank and hydrogen is introduced for secondary fermentation to obtain biogas.

[0016] According to some embodiments of the method for producing biogas, the organic waste includes one or more of livestock and poultry manure, crop straw, and kitchen waste.

[0017] According to some embodiments of the method for producing biogas, the solid content of the fermentation material in the primary fermentation tank is 10%-12%.

[0018] According to some embodiments of the method for producing biogas, the oxygen content of the fermentation material in the primary fermentation tank is 0.1wt%-0.5wt% after the oxygen is introduced.

[0019] According to some embodiments of the method for producing biogas, the fermentation bacteria used in the primary fermentation are hydrolytic enzymes.

[0020] According to some embodiments of the method for producing biogas, the temperature of the primary fermentation is 30-40℃, and the time of the primary fermentation is 3-8 days.

[0021] According to some embodiments of the method for producing biogas described in the present application, the volume of hydrogen gas introduced is 50%-100% of the amount of biogas produced by the method for producing biogas.

[0022] According to some embodiments of the method for producing biogas described in the present application, the temperature of the secondary fermentation is 50-60℃, and the time of the secondary fermentation is 20-30 days.

[0023] The beneficial effects of the present application include that the electrolysis water hydrogen production coupled anaerobic fermentation device described in the present application utilizes renewable energy wind power and solar power to generate electricity and provides power for electrolysis water to produce hydrogen, and the produced hydrogen and oxygen are injected into the organic waste fermentation system in a targeted manner to improve the biogas yield of fermentation, increase the purity and carbon neutralization efficiency, and reasonably utilize the hydrogen and oxygen produced by electrolysis. DETAILED DESCRIPTION

[0024] The embodiments of the present application are described in detail below, and the examples of the embodiments are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0025] In the present application, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the different embodiments or examples described in the present specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0026] The embodiment of the present application provides a water electrolysis hydrogen production coupled anaerobic fermentation device, which comprises a generator set, a PEM electrolytic cell, a primary fermentation tank and a secondary fermentation tank; the oxygen outlet of the PEM electrolytic cell is connected with the gas inlet of the primary fermentation tank, the discharge outlet of the primary fermentation tank is connected with the feed inlet of the secondary fermentation tank, and the hydrogen outlet of the PEM electrolytic cell is connected with the gas inlet of the secondary fermentation tank; and the generator set provides electric energy for the PEM electrolytic cell.

[0027] The water electrolysis hydrogen production coupled anaerobic fermentation device described in the present application utilizes renewable energy wind power and solar power to generate electricity, electrolyzes water to produce hydrogen, and injects the produced hydrogen and oxygen into the organic waste fermentation system in a targeted manner to improve the methane yield of fermentation, increase the purity and carbon neutralization efficiency, and reasonably utilize the hydrogen and oxygen produced by electrolysis.

[0028] In some embodiments of the present application, the oxygen outlet of the PEM electrolyzer is connected to an oxygen storage tank through a pipeline, and the oxygen storage tank is connected to the gas inlet of the primary fermentation tank. The main function of the primary fermentation tank is to hydrolyze and acidify the organic waste. The injection of trace oxygen can inhibit sulfate-reducing bacteria, reduce the generation of H2S, promote the activity of hydrolysis bacteria, and reduce air pollution.

[0029] In some embodiments of the present application, an oxygen flow control valve is arranged on the pipeline connecting the oxygen storage tank and the gas inlet of the primary fermentation tank. The arrangement of the oxygen flow control valve can control the amount of oxygen entering the primary fermentation tank. Since the primary fermentation tank is an anaerobic fermentation tank, controlling the amount of oxygen entering the tank can reduce the generation of H2S while ensuring normal fermentation.

[0030] In some embodiments of the present application, the hydrogen outlet of the PEM electrolyzer is connected to a hydrogen storage tank, and the hydrogen storage tank is connected to the gas inlet of the secondary fermentation tank. The main function of the secondary fermentation tank is to make the material enter the stage of producing acid, hydrogen, and methane. The injection of hydrogen can drive acetobacter to convert carbon dioxide into acetic acid, which can be converted into methane by methanogens. In addition, the injection of hydrogen can also promote the hydrogenotrophic methanogens to directly reduce carbon dioxide to produce methane, shorten the metabolic pathway, and increase the biogas yield and methane content.

[0031] In some embodiments of the present application, a hydrogen flow control valve is arranged on the pipeline connecting the hydrogen storage tank and the gas inlet of the secondary fermentation tank. The hydrogen flow control valve can adjust the amount of hydrogen entering according to the ORP (Oxidation-Reduction Potential, ORP≥400mV). If the ORP is too low, it means that the excessive hydrogen will inhibit the activity of the bacterial community. In addition, the hydrogen flow control valve can also adjust the amount of hydrogen entering according to the VFA (volatile fatty acid) concentration (VFA concentration≥1500-2000mg / L). If the hydrogen is injected too early or in excess, the material will be acidified and the production of methane will be inhibited.

[0032] In some embodiments of the present application, a dissolved oxygen sensor is arranged in the primary fermentation tank. The arrangement of the dissolved oxygen sensor facilitates the observation of the oxygen content in the primary fermentation tank and realizes the real-time control of the oxygen content.

[0033] In some embodiments of the present application, a VFA sensor is arranged in the secondary fermentation tank. The arrangement of the VFA sensor facilitates the observation of the hydrogen content in the primary fermentation tank and realizes the real-time control of the hydrogen content.

[0034] The present application also provides a method for producing biogas by using the electrolytic water hydrogen production and anaerobic fermentation device of the first aspect of the present application.

[0035] The electrolytic water hydrogen production and anaerobic fermentation device of the present application can improve the biogas yield and the methane content in the biogas.

[0036] In some embodiments of the present application, the following steps are included:

[0037] The generator set is electrically connected with the PEM electrolyzer to generate hydrogen and oxygen by electrolyzing water; the organic waste is added into the primary fermentation tank and oxygen is introduced for primary fermentation; after the primary fermentation is completed, the primary fermentation product is flowed into the secondary fermentation tank and hydrogen and carbon dioxide gas are introduced for secondary fermentation to obtain biogas.

[0038] The method for producing biogas described in the present application solves the problem of resource utilization of the byproduct (oxygen) of water electrolysis, and at the same time, by introducing hydrogen / oxygen dual-path regulation of anaerobic fermentation microbial community, hydrogen-driven acetogenic bacteria are achieved to convert carbon dioxide into acetic acid, thereby improving carbon utilization rate; the introduction of trace oxygen inhibits sulfate-reducing bacteria, reduces the generation of H2S, and reduces environmental pollution; the biogas yield of organic matter anaerobic fermentation is improved, and the content of methane in the generated biogas is optimized.

[0039] In some embodiments of the present application, the organic waste includes one or more of livestock and poultry manure, crop straw and kitchen waste.

[0040] In some embodiments of the present application, the solid content of the fermentation material in the primary fermentation tank is 10%-12%; for example, 10%, 11%, 12%, etc.

[0041] In some embodiments of the present application, the introduction of oxygen into the primary fermentation tank makes the oxygen content of the fermentation material 0.1wt%-0.5wt%, for example, 0.1wt%, 0.2wt%, 0.3wt%, 0.35wt%, 0.5wt%, etc. The oxygen content in the fermentation material is controlled within this range, which is suitable for the growth of desulfurization bacteria. If the oxygen content is too high, it will affect the activity of anaerobic bacteria, and if the oxygen content is too low, it will affect the growth and reproduction of desulfurization bacteria.

[0042] In some embodiments of the present application, the fermentation bacteria used in the primary fermentation are hydrolytic bacteria. Hydrolytic bacteria are rich in efficient microbial strains suitable for anaerobic treatment of wastewater or solid waste, can enhance the impact resistance of microorganisms in the anaerobic stage, improve the anaerobic efficiency, are themselves composed of anaerobic bacteria, and belong to anaerobic bacteria.

[0043] In some embodiments of the present application, the temperature of the primary fermentation is 30-40℃; for example, 30℃, 35℃, 38℃, 40℃, etc., and the time of the primary fermentation is 3-8 days.

[0044] In some embodiments of the present application, the volume of hydrogen gas introduced is 50-100%, such as 50%, 60%, 65%, 73%, 80%, 100%, etc. of the amount of biogas produced by the method, and when the amount of hydrogen gas introduced is too high, the biogas production will be lower than that of the conventional fermentation method, because too much hydrogen gas injection will cause the material to be acidified and inhibit gas production.

[0045] In some embodiments of the present application, the temperature of the secondary fermentation is 50-60℃, such as 50℃, 53℃, 55℃, 58℃, 60℃, etc., and the time of the secondary fermentation is 20-30 days, such as 20 days, 22 days, 25 days, 28 days, 30 days, etc.

[0046] The technical solutions of the present application will be further described below in conjunction with specific embodiments.

[0047] The embodiment of the present application provides a water electrolysis hydrogen production coupled anaerobic fermentation device, which comprises a generator set, a PEM electrolytic cell, a primary fermentation tank and a secondary fermentation tank; the generator set generates electricity to provide electric energy for the PEM electrolytic cell, and the oxygen generated by electrolyzing water in the PEM electrolytic cell flows into an oxygen storage tank through a pipeline from an oxygen outlet of the PEM electrolytic cell, the oxygen storage tank is connected in communication with a gas inlet of the primary fermentation tank, and is used for introducing oxygen into the primary fermentation tank, and the amount of oxygen introduced is adjusted and controlled through an oxygen flow control valve arranged on the pipeline connecting the oxygen storage tank and the gas inlet of the primary fermentation tank; the amount of oxygen introduced is obtained by reading a dissolved oxygen sensor arranged in the primary fermentation tank; the hydrogen generated by electrolyzing water in the PEM electrolytic cell flows into a hydrogen storage tank through a pipeline from a hydrogen outlet of the PEM electrolytic cell, the hydrogen storage tank is connected in communication with a hydrogen inlet of the secondary fermentation tank, and the amount of hydrogen introduced is controlled through a hydrogen flow control valve arranged on the pipeline connecting the hydrogen storage tank and the gas inlet of the secondary fermentation tank, and the amount of hydrogen introduced is obtained by reading a VFA sensor arranged in the secondary fermentation tank.

[0048] The primary fermentation tank is used for hydrolyzing organic waste, and the material produced by the fermentation of the primary fermentation tank flows out from a discharge port thereof, flows into the secondary fermentation tank through a feed inlet of the secondary fermentation tank, and generates biogas by fermentation.

[0049] Embodiment 1

[0050] A method for producing biogas, which uses the above-mentioned water electrolysis hydrogen production coupled anaerobic fermentation device for production;

[0051] The specific operation steps include:

[0052] (1) electrically connect the generator set and the PEM electrolytic cell of the above-mentioned water electrolysis hydrogen production coupled anaerobic fermentation device, so that the PEM electrolytic cell electrolyzes water to generate hydrogen and oxygen, and the generated hydrogen and oxygen are respectively stored in a hydrogen storage tank and an oxygen storage tank for standby;

[0053] (2) 1 ton of cow dung (containing 20% solid content) is mixed with 1.5 tons of biogas slurry (containing hydrolytic enzyme, containing 3% solid content) to adjust the solid content to 11.8%, and then sent to the primary fermentation tank, the temperature of the primary fermentation tank is controlled at 35°C, the oxygen flow control valve is opened to inject oxygen into the primary fermentation tank through the oxygen injector, and the dissolved oxygen sensor is observed, the oxygen flow control valve is adjusted to maintain the dissolved oxygen content in the material at 0.3wt%, and then the hydrolysis is carried out under the above conditions for 5 days;

[0054] (3) The acidified liquid produced by the hydrolysis reaction is sent to the secondary fermentation tank, the temperature of the secondary fermentation tank is controlled at 55°C, the hydrogen flow control valve is adjusted to meet the hydrogen injection rate of 1.52 L / min (the amount of hydrogen injected during the final fermentation period is 80% of the biogas production), the VFA sensor is observed, and the VFA concentration during fermentation is adjusted to be ≥1500 mg / L by adjusting the hydrogen flow control valve, and then the fermentation is carried out under the above conditions for 25 days.

[0055] Example 2

[0056] The method for producing biogas described in Example 2 is different from that of Example 1 only in that the volume of hydrogen injected in the method for producing biogas described in Example 2 is 40% of the biogas production of the method for producing biogas in this example.

[0057] The specific operation steps include:

[0058] (1) The generator set of the electrolytic water hydrogen production coupled anaerobic fermentation device is electrically connected with the PEM electrolytic cell, the PEM electrolytic cell electrolyzes water to produce hydrogen and oxygen, and the produced hydrogen and oxygen are respectively stored in the hydrogen storage tank and the oxygen storage tank for standby;

[0059] (2) 1 ton of cow dung (containing 20% solid content) is mixed with 1.5 tons of biogas slurry (containing hydrolytic enzyme, containing 3% solid content) to adjust the solid content to 11.8%, and then sent to the primary fermentation tank, the temperature of the primary fermentation tank is controlled at 35°C, the oxygen flow control valve is opened to inject oxygen into the primary fermentation tank through the oxygen injector, and the dissolved oxygen sensor is observed, the oxygen flow control valve is adjusted to maintain the dissolved oxygen content in the material at 0.3wt%, and then the hydrolysis is carried out under the above conditions for 5 days;

[0060] (3) The acidified liquid produced by the hydrolysis reaction is sent to the secondary fermentation tank, the temperature of the secondary fermentation tank is controlled at 55°C, the hydrogen flow control valve is adjusted to meet the hydrogen injection rate of 1.52 L / min (the amount of hydrogen injected during the final fermentation period is 80% of the biogas production), the VFA sensor is observed, and the VFA concentration during fermentation is adjusted to be ≥1500 mg / L by adjusting the hydrogen flow control valve, and then the fermentation is carried out under the above conditions for 25 days.

[0061] Example 3

[0062] The method for producing biogas according to Example 3 is different from the method for producing biogas according to Example 1 only in that the volume of hydrogen gas introduced in the method for producing biogas according to Example 3 is 100% of the amount of biogas produced in the method for producing biogas according to the present example.

[0063] The specific operation steps include:

[0064] (1) The generator set of the water electrolysis hydrogen production coupled anaerobic fermentation device is electrically connected with the PEM electrolyzer, so that the PEM electrolyzer electrolyzes water to produce hydrogen gas and oxygen gas, and the produced hydrogen gas and oxygen gas are respectively stored in the hydrogen storage tank and the oxygen storage tank for standby;

[0065] (2) 1 ton of cow dung (containing 20% solid content) is mixed with 1.5 tons of biogas slurry (containing hydrolytic enzyme and 3% solid content) to adjust the solid content of the material to 11.8%, and then the material is sent to the primary fermentation tank, the temperature of the primary fermentation tank is controlled at 35°C, the oxygen flow control valve is opened to introduce oxygen into the primary fermentation tank through the oxygen injector, and the dissolved oxygen sensor is observed to adjust the oxygen flow control valve to maintain the dissolved oxygen content in the material at 0.3wt%, and then the material is hydrolyzed under the above conditions for 5 days;

[0066] (3) The acidified liquid produced by the hydrolysis reaction is sent to the secondary fermentation tank, the temperature of the secondary fermentation tank is controlled at 55°C, the hydrogen flow control valve is adjusted to make the hydrogen introduction rate meet 1.9 L / min (the amount of hydrogen introduced during the final fermentation period is 100% of the biogas production), the VFA sensor is observed, and the VFA concentration during the fermentation process is adjusted to be ≥1500 mg / L by adjusting the hydrogen flow control valve, and then the material is fermented under the above conditions for 25 days.

[0067] Comparative Example 1

[0068] The method for producing biogas according to Comparative Example 1 is different from the method for producing biogas according to Example 1 only in that no hydrogen gas is introduced in the secondary fermentation process of the method for producing biogas according to Comparative Example 1.

[0069] The specific operation steps include:

[0070] (1) The generator set of the water electrolysis hydrogen production coupled anaerobic fermentation device is electrically connected with the PEM electrolyzer, so that the PEM electrolyzer electrolyzes water to produce hydrogen gas and oxygen gas, and the produced hydrogen gas and oxygen gas are respectively stored in the hydrogen storage tank and the oxygen storage tank for standby;

[0071] (2) 1 ton of cow dung (containing 20% solid) is mixed with 1.5 tons of biogas slurry (inoculum, containing 3% solid) to adjust the solid content to 11.8%, and then is sent to the primary fermentation tank, the temperature of the primary fermentation tank is controlled at 35°C, oxygen is injected into the primary fermentation tank through an oxygen injector by opening the oxygen flow control valve, and the dissolved oxygen sensor is observed, the oxygen flow control valve is adjusted to maintain the dissolved oxygen content in the material at 0.3wt%, and then the hydrolysis is carried out under the above conditions for 5 days;

[0072] (3) The acidified liquid produced by the hydrolysis reaction is sent to the secondary fermentation tank, the temperature of the secondary fermentation tank is controlled at 55°C, and the fermentation is carried out at this temperature for 25 days.

[0073] Comparative Example 2

[0074] The method for producing biogas in Comparative Example 2 is different from that in Example 1 only in that no oxygen is injected in the primary fermentation process.

[0075] The specific operation steps include:

[0076] (1) The generator set of the electrolytic water hydrogen production coupled anaerobic fermentation device is electrically connected with the PEM electrolytic cell, the PEM electrolytic cell electrolyzes water to produce hydrogen and oxygen, and the produced hydrogen and oxygen are respectively stored in the hydrogen storage tank and the oxygen storage tank for standby;

[0077] (2) 1 ton of cow dung (containing 20% solid) is mixed with 1.5 tons of biogas slurry (containing hydrolytic enzyme, containing 3% solid) to adjust the solid content to 11.8%, and then is sent to the primary fermentation tank, the temperature of the primary fermentation tank is controlled at 35°C, and then the hydrolysis is carried out under the above conditions for 5 days;

[0078] (3) The acidified liquid produced by the hydrolysis reaction is sent to the secondary fermentation tank, the temperature of the secondary fermentation tank is controlled at 55°C, the hydrogen flow control valve is adjusted to make the hydrogen injection rate meet 1.52 L / min (the amount of hydrogen injected during the final fermentation period is 80% of the biogas production), the VFA sensor is observed, and the VFA concentration ≥ 1500 mg / L during the fermentation process is used by adjusting the hydrogen flow control valve, and the fermentation is carried out under the above conditions for 25 days.

[0079] Comparative Example 3

[0080] The method for producing biogas in Comparative Example 3 includes the following steps:

[0081] 1 ton of cow dung (containing 20% solid) is mixed with 1.5 tons of biogas slurry (inoculum, containing 3% solid) to adjust the solid content to 11.8%, and then is sent to the fermentation tank, the temperature is controlled at 35°C, and the fermentation is carried out for 30 days.

[0082] Comparative Example 4

[0083] The method for producing biogas according to Comparative Example 4 is different from that of Example 1 only in that the volume of hydrogen gas introduced in the method for producing biogas according to Comparative Example 4 is 160% of the amount of biogas produced in the method for producing biogas according to the present example.

[0084] The specific operation steps include:

[0085] (1) Electrically connect the generator set of the water electrolysis hydrogen production coupled anaerobic fermentation device with the PEM electrolytic cell to make the PEM electrolytic cell electrolyze water to produce hydrogen gas and oxygen gas, and store the produced hydrogen gas and oxygen gas in the hydrogen gas storage tank and the oxygen gas storage tank, respectively, for standby;

[0086] (2) Mix 1 ton of cow dung (containing 20% solid content) with 1.5 tons of biogas slurry (containing hydrolytic enzyme and 3% solid content) to adjust the solid content of the mixture to 11.8%, and then send the mixture into the primary fermentation tank, control the temperature of the primary fermentation tank to be 35°C, open the oxygen flow control valve to introduce oxygen into the primary fermentation tank through the oxygen injector, and observe the dissolved oxygen sensor to adjust the oxygen flow control valve to maintain the dissolved oxygen content in the material to be 0.3wt%, and then hydrolyze under the above conditions for 5 days;

[0087] (3) Send the acidified liquid produced by the hydrolysis reaction into the secondary fermentation tank, control the temperature of the secondary fermentation tank to be 55°C, adjust the hydrogen flow control valve to make the hydrogen introduction rate meet 3.04 L / min (the amount of hydrogen introduced during the final fermentation period is 160% of the biogas production), observe the VFA sensor, and use the VFA concentration ≥ 1500 mg / L during the fermentation process by adjusting the hydrogen flow control valve, and then ferment under the above conditions for 25 days.

[0088] The amount of biogas obtained in the methods for producing biogas according to Examples 1-3 and Comparative Examples 1-4 of the present application is shown in Table 1.

[0089] Table 1

[0090] Biogas production Methane content [H2S concentration] Example 1 128m 3 ]]> 78％ 200 ppm Example 2 95m 3 ]] 61％ 210 ppm Example 3 117m 3 ]] 70％ 204 ppm Comparative Example 1 75m 3 ]] 56％ 205 ppm Comparative Example 2 109m 3 ]] 75％ 2355 ppm Comparative Example 3 66m 3 ]] 54％ 2678 ppm Comparative Example 4 45m 3 ]] 50.2％ 450 ppm

[0091] As can be seen from Table 1, during the hydrogen production, acid production, and methane production stage, the introduction of hydrogen gas can significantly improve the biogas production, but excessive hydrogen gas introduction will inhibit the biogas production (as can be seen from Comparative Example 1 and Comparative Example 4), and as can be seen from Comparative Examples 1-3 and Comparative Example 4, when the amount of hydrogen gas introduced is 80%-100% of the amount of biogas produced in the method for producing biogas, the amount of biogas produced is the largest.

[0092] As can be seen from Comparative Example 1 and Comparative Example 1, the introduction of hydrogen gas during the secondary fermentation process can significantly improve the biogas production and the methane content in the biogas.

[0093] As can be seen from Comparative Example 1 and Comparative Example 2, the content of hydrogen sulfide in the biogas can be significantly reduced by introducing oxygen during the hydrolysis stage. As can be seen from the data of Comparative Example 1 and Comparative Example 2, the content of hydrogen sulfide in the biogas is reduced by about 90% by introducing oxygen during the hydrolysis stage.

[0094] Although the above embodiments have been shown and described, it should be understood by those ordinary skilled in the art that the above embodiments are exemplary and cannot be construed as limiting the present application, and any changes, modifications, replacements and variations made by those ordinary skilled in the art to the above embodiments are within the protection scope of the present application.

Claims

1. A device for producing hydrogen through water electrolysis coupled with anaerobic fermentation, characterized in that, The device comprises a generator set, a PEM electrolytic cell, a primary fermentation tank and a secondary fermentation tank; the oxygen outlet of the PEM electrolytic cell is connected with the gas inlet of the primary fermentation tank, the discharge outlet of the primary fermentation tank is connected with the feed inlet of the secondary fermentation tank, and the hydrogen outlet of the PEM electrolytic cell is connected with the gas inlet of the secondary fermentation tank; the generator set provides electric energy for the PEM electrolytic cell.

2. The device for hydrogen production by water electrolysis coupled to anaerobic fermentation according to claim 1, characterized in that, The oxygen outlet of the PEM electrolytic cell is connected with an oxygen storage tank through a pipeline, and the oxygen storage tank is connected with the gas inlet of the primary fermentation tank; Preferably, an oxygen flow control valve is arranged on the pipeline connecting the oxygen storage tank and the gas inlet of the primary fermentation tank; Preferably, the hydrogen outlet of the PEM electrolytic cell is connected with a hydrogen storage tank, and the hydrogen storage tank is connected with the gas inlet of the secondary fermentation tank; Preferably, a hydrogen flow control valve is arranged on the pipeline connecting the hydrogen storage tank and the gas inlet of the secondary fermentation tank.

3. The apparatus for hydrogen production by water electrolysis coupled with anaerobic fermentation according to claim 1, characterized in that, A dissolved oxygen sensor is arranged in the primary fermentation tank; Preferably, a VFA sensor is arranged in the secondary fermentation tank.

4. A method of producing biogas, characterized in that, The device is used for production.

5. The method of producing biogas according to claim 4, characterized in that, The device comprises the following steps: The generator set is electrically connected with the PEM electrolytic cell to electrolyze water to generate hydrogen and oxygen; the organic waste is added into the primary fermentation tank, and oxygen is introduced to perform primary fermentation; after the primary fermentation is completed, the primary fermentation product is flowed into the secondary fermentation tank, and hydrogen is introduced to perform secondary fermentation to obtain biogas.

6. The method of producing biogas according to claim 5, characterized in that, The organic waste comprises one or more of livestock and poultry manure, crop straw and kitchen waste; Preferably, the solid content of the fermentation material in the primary fermentation tank is 10%-12%.

7. The method of producing biogas according to claim 5, characterized in that, The oxygen introduced into the primary fermentation tank is 0.1wt%-0.5wt% of the fermentation material.

8. The method of producing biogas according to claim 5, wherein, The fermentation bacteria used in the primary fermentation are hydrolase; Preferably, the temperature of the primary fermentation is 30-40℃, and the time of the primary fermentation is 3-8 days.

9. The method of producing biogas according to claim 5, wherein, The volume of the introduced hydrogen is 50%-100% of the amount of the biogas produced by the method.

10. The method of producing biogas according to claim 5, wherein, The temperature of the secondary fermentation is 50-60℃, and the time of the secondary fermentation is 20-30 days.