Method for preparing microbial protein from pyrolysis gas and co-producing power generation

Abstract

The invention discloses a method for preparing microbial protein from pyrolysis gas and co-producing power generation, which comprises the following steps: S1, inoculating domesticated hydrogen-oxidizing bacteria flora into a bioreactor containing a protein-producing culture medium, introducing the pyrolysis gas to obtain a microbial fermentation system for producing protein based on hydrogen-oxidizing bacteria by using the pyrolysis gas, and then carrying out fermentation culture to obtain a microbial fermentation product; fermentation flora is obtained; s2, treating the fermentation flora obtained in the step S1 to obtain microbial protein; s3, preparing the solid oxide fuel cell; s4, residual pyrolysis gas after fermentation is recycled and introduced into an anode of the solid oxide fuel cell for electrochemical reaction, meanwhile, air is compressed, heated and introduced into a cathode of the solid oxide fuel cell, O2 is provided for the electrochemical reaction, and then electric energy is output. According to the invention, the hydrogen oxidizing bacteria can be utilized to ferment the pyrolysis gas to prepare the microbial protein, and the solid oxide fuel cell can be utilized to recycle the fermentation residual gas for power generation.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of biomass resources, and particularly relates to a method for preparing microbial protein by pyrolysis gas and co-producing electricity. Background Art

[0002] Pyrolysis gasification is an important way to treat solid waste at present. It is a high-temperature pyrolysis process of organic matter under anaerobic or low-oxygen conditions, obtaining energy products such as pyrolysis oil, biochar, and pyrolysis gas. The main components of pyrolysis gas are hydrogen (H2), carbon monoxide (CO), methane (CH4), and carbon dioxide (CO2). Abandoning the combustible components therein will result in a large amount of energy loss, and the direct emissions of carbon monoxide (CO) and carbon dioxide (CO2) will pollute the environment. At present, the utilization technology of pyrolysis gas remains at heat supply and direct combustion power generation, still having problems such as low energy conversion efficiency and environmental pollution. In addition, the gas composition and content of pyrolysis gas vary greatly due to different raw materials, pyrolysis processes, and pyrolysis reactors, making it difficult to achieve high-value fractionated utilization, resulting in resource waste, which also restricts the large-scale utilization of pyrolysis gas.

[0003] At the same time, microbial protein, also known as single-cell protein, can be produced by yeast, algae, fungi, and bacteria. It is a high-value-added product and can be used as a protein supplement in animal feed. One of the production bottlenecks of traditional microbial protein is its dependence on a single carbon source (such as glucose, methane, etc.), with high costs and unstable carbon source supply. However, hydrogen-oxidizing bacteria (HOB) can use H2 as an energy source, CO2 as a carbon source, and O2 as an electron acceptor to synthesize their own cell substances. If microbial protein is produced by hydrogen-oxidizing bacteria using pyrolysis gas, it will have many advantages:

[0004] 1) Efficiently utilize various components in pyrolysis gas;

[0005] 2) Fix CO2 in pyrolysis gas, thereby reducing the greenhouse effect;

[0006] 3) Do not rely on large-scale land production of protein, reducing the pressure on arable land.

[0007] In addition, a solid oxide fuel cell (SOFC) is a new type of all-solid component electrochemical energy power generation device that can efficiently and environmentally friendly directly convert the chemical energy stored in fuels and oxidants into electrical energy through electrochemical reactions. It has the advantages of high power generation efficiency, strong fuel adaptability, and being unrestricted by scale. Pyrolysis gas belongs to renewable energy and has the characteristics of large total amount and wide distribution, making it very suitable for small and medium-sized distributed power generation systems. Therefore, solid oxide fuel cells also provide an effective solution for the efficient resource and energy utilization of pyrolysis gas with complex components.

[0008] However, the stoichiometric requirement of H2:CO2 for hydrogen-oxidizing bacteria to produce microbial protein is 5.22:1, and the CO2 content in conventional pyrolysis gas usually cannot meet this requirement. Therefore, there will still be a small amount of H2 in the fermented residual gas, and the utilization of pyrolysis gas is not sufficient. Combining the strong fuel adaptability of solid oxide fuel cells, CO, a small amount of CH4, and a small amount of H2 in the residual gas can still be used as fuels for solid oxide fuel cells to generate electricity, realizing the secondary utilization of the residual pyrolysis gas.

[0009] In summary, as a renewable energy source, pyrolysis gas has great potential in the fields of energy transformation and environmental protection. It is urgent to find an efficient and universal coupling technology to achieve the efficient resource utilization and energy conversion of pyrolysis gas. Summary of the Invention

[0010] The object of the present invention is to provide a method for co-producing microbial protein and electricity by preparing pyrolysis gas, which can not only use hydrogen-oxidizing bacteria to ferment pyrolysis gas to produce microbial protein, but also use a solid oxide fuel cell to recover and generate electricity from the fermented residual gas.

[0011] To achieve the above object, the following technical solutions are adopted:

[0012] A method for co-producing microbial protein and electricity by preparing pyrolysis gas includes the following steps:

[0013] S1: Inoculate the domesticated hydrogen-oxidizing bacterial flora into a bioreactor filled with a protein-producing culture medium, and introduce pyrolysis gas to obtain a microbial fermentation system for producing protein by using hydrogen-oxidizing bacteria to utilize pyrolysis gas, and then perform fermentation culture to obtain a fermented bacterial flora, wherein the pyrolysis gas contains H2, CO2, CO, and CH4;

[0014] S2: Process the fermented bacterial flora obtained in S1 to obtain microbial protein;

[0015] S3: Prepare a solid oxide fuel cell;

[0016] S4: Recover the pyrolysis gas remaining after fermentation, introduce it into the anode of the solid oxide fuel cell for an electrochemical reaction, and at the same time, compress the air and heat it before introducing it into the cathode of the solid oxide fuel cell to provide O2 for the electrochemical reaction, thereby outputting electric energy.

[0017] Further, in S1, the formula of the protein-producing culture medium is as follows: per liter of the solution contains the following amounts of substances: 2.3 g of potassium dihydrogen phosphate, 2.9 g of disodium hydrogen phosphate, 0.5 g of magnesium sulfate, 0.5 g of sodium carbonate, 0.01 g of calcium chloride, 0.05 g of ammonium ferric citrate, 0.6 mg of boric acid, 0.4 mg of cobalt chloride, 0.2 mg of zinc sulfate, 0.06 mg of manganese chloride, 0.06 mg of sodium molybdate, 0.04 mg of nickel chloride, and 0.02 mg of copper sulfate.

[0018] Further, in the domestication process of the hydrogen-oxidizing bacterial flora in S1, it specifically includes the following steps:

[0019] S11: After the protein-producing culture medium is prepared, it is sterilized, and then 15 g / L of agar is added after the medium is cooled to room temperature to obtain the domestication medium. Among them, the blue-capped bottle used for domestication is 500 mL, the working volume is 200 mL, the headspace volume is 415 mL, and the inoculum is 10% aerobic sludge and 10% anaerobic sludge.

[0020] S12: Inject a mixed gas into the headspace of the blue-capped bottle, and continuously purge the headspace of the blue-capped bottle for a certain period of time and then seal the blue-capped bottle.

[0021] S13: Every once in a while, replace the mixed gas sealed in the blue-capped bottle. When the consumption rates of the mixed gas and hydrogen are stable and reach more than 60%, the domestication is completed, and a protein-producing hydrogen-oxidizing bacterial flora is obtained.

[0022] Further, in S11, the sterilization temperature of the prepared protein-producing culture medium is 120 - 122 °C, and the sterilization time is 18 - 22 min; in S12, the volume ratio of the components of the mixed gas is H2:O2:CO2 = 60:25:15. At the same time, the time for continuously purging the headspace of the blue-capped bottle with the mixed gas is 8 - 12 min; in S13, the mixed gas sealed in the blue-capped bottle is replaced once every 12 h, and during the culture process, the pH is controlled at 7.0 ± 0.2, the temperature is controlled at 20 - 40 °C, and the rotation speed is 150 rpm.

[0023] Further, S2 specifically includes the following steps:

[0024] S21: Centrifuge the fermentation bacterial flora and discard the supernatant.

[0025] S22: Wash the centrifuged product with deionized water and then centrifuge again, and repeat 1 - 3 times.

[0026] S23: Bake the centrifuged and washed product to obtain microbial protein.

[0027] Further, in S21, the fermentation flora is centrifuged at 9000 - 11000 rpm for 10 - 15 min; in S23, the baking temperature is 100 - 110 °C and the baking time is 20 - 30 h. Meanwhile, one or more of the following methods are adopted to judge the formation of microbial protein: the crude protein content in the product > 30%, and the crude protein yield in the product > 1.5 g / L.

[0028] Further, S3 specifically includes the following steps:

[0029] S31: Mix 360 g of nickel oxide and 360 g of yttria-stabilized zirconia slurry.

[0030] S32: Add 72 g of graphite to the slurry as a pore former.

[0031] S33: Add 84 g of polyvinyl butyral-ethanol binder, 50.4 g of polyethylene glycol, and 50.4 g of dioctyl phthalate to the slurry as plasticizers, and perform ball milling to obtain a slurry suitable for tape casting.

[0032] S34: Use a doctor blade to evenly coat the slurry on a tape casting machine to form an anode support film, and after waiting for the solvent to volatilize, peel off the film.

[0033] S35: Stack the anode support film with a certain number of functional layer films and electrolyte films through a tablet press to form a green body.

[0034] S36: Sinter the green body in a high-temperature muffle furnace to obtain a Ni-YSZ / YSZ half-cell with different structures.

[0035] S37: Grind 42 g of strontium lanthanum manganite powder evenly in a mortar, and add 12.64 g of ethylene glycol diethyl ether as an organic binder to prepare a cathode slurry.

[0036] S38: Use the brushing method to evenly coat the cathode slurry on the electrolyte surface and perform sintering treatment to obtain a full cell.

[0037] S39: Use 738.4 g of 304 stainless steel, 178.4 g of glass wool, and 3.08 kg of chromium steel connectors as the shell and insulation material of the solid oxide fuel cell to complete the assembly of the cell.

[0038] Further, in S4, before the pyrolysis gas is introduced into the solid oxide fuel cell, it is first mixed with steam in a certain proportion and the appropriate water-carbon ratio is maintained to convert part of the CH4 and CO in the pyrolysis gas into H2 that can be easily utilized by the cell.

[0039] Adopting the above solution, the beneficial effects of the present invention are:

[0040] 1) Compared with the traditional pyrolysis gas utilization technology, the coupled pyrolysis gas protein production and pyrolysis gas power generation technology in the present invention can not only convert pyrolysis gas into high value-added protein products, but also generate electricity from the unused components in the pyrolysis gas, with a high energy conversion rate. At the same time, it can reduce the emission of carbon dioxide in the pyrolysis gas, reduce the greenhouse effect, and does not rely on a large amount of land, with good environmental benefits;

[0041] 2) The gas composition and content of pyrolysis gas vary greatly due to the differences in raw materials, pyrolysis processes and pyrolysis reactors, making it difficult to achieve high-value fractional utilization, resulting in resource waste, which also restricts the large-scale utilization of pyrolysis gas. The technology of preparing microbial protein from pyrolysis gas for co-generation of power generation of the present invention has strong fuel adaptability, and the two coupled pyrolysis gas technologies can effectively and comprehensively utilize the various components in the pyrolysis gas, providing an effective solution for realizing efficient resource energy utilization of pyrolysis gas with complex components. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0044] Reference Figure 1 As shown, the present invention provides a method for preparing microbial protein from pyrolysis gas and co-producing electricity. For ease of understanding, the main terms involved in this application are explained as follows:

[0045] Pyrolysis gas: refers to the heating of biomass using external heat sources or the biomass' own energy under the conditions of isolation from air or a small amount of air supply, releasing a large amount of gas. The main components of pyrolysis gas include hydrogen, carbon monoxide, carbon dioxide, methane and a small amount of hydrocarbons.

[0046] Microbial protein: refers to the bacterial cytoplasm composed of a mixture of proteins, carbohydrates, nucleic acids, fats, non-protein nitrogen-containing compounds, vitamins and inorganic compounds produced by bacteria, fungi, yeast or algae under a suitable growth environment.

[0047] Hydrogen oxidizing bacteria: refers to microorganisms that can use hydrogen as an electron donor to reduce carbon dioxide to organic matter.

[0048] Fermentation system: refers to a fermentation system composed of bacterial flora and culture medium cultured in a reactor. In form, it refers to a mixture of bacterial flora and mixed biological culture medium.

[0049] Solid Oxide Fuel Cell (SOFC): It refers to a new type of all-solid component electrochemical energy generation device that can efficiently and environmentally friendly directly convert the chemical energy stored in fuels and oxidants into electrical energy through electrochemical reactions.

[0050] The present invention specifically includes the following steps:

[0051] S1: Inoculate the domesticated hydrogen-oxidizing bacteria flora into a bioreactor filled with a protein-producing medium, and introduce pyrolysis gas to obtain a microbial fermentation system for protein production by hydrogen-oxidizing bacteria using pyrolysis gas, and then perform fermentation culture to obtain a fermentation flora, wherein the pyrolysis gas contains H2, CO2, CO, and CH4.

[0052] In this step, mainly to obtain a microbial fermentation system for "protein production by hydrogen-oxidizing bacteria using pyrolysis gas", and then perform fermentation culture to obtain a fermentation flora. Among them, the steps for obtaining the microbial fermentation system in S1 are specifically as follows:

[0053] 1) Prepare the protein-producing medium;

[0054] 2) Inoculate the domesticated hydrogen-oxidizing bacteria into the bioreactor;

[0055] 3) Fill the mixed gas tank with pyrolysis gas containing hydrogen, carbon dioxide, carbon monoxide, and methane;

[0056] 5) Start the peristaltic pump to transport the pyrolysis gas to the bioreactor;

[0057] 5) Form a microbial fermentation system for "protein production by hydrogen-oxidizing bacteria using pyrolysis gas".

[0058] Among them, in a feasible embodiment, the formula of the protein-producing medium in S1 is that each liter of solution contains the following amounts of substances: potassium dihydrogen phosphate 2.3 g, disodium hydrogen phosphate 2.9 g, magnesium sulfate 0.5 g, sodium carbonate 0.5 g, calcium chloride 0.01 g, ammonium ferric citrate 0.05 g, boric acid 0.6 mg, cobalt chloride 0.4 mg, zinc sulfate 0.2 mg, manganese chloride 0.06 mg, sodium molybdate 0.06 mg, nickel chloride 0.04 mg, copper sulfate 0.02 mg; at the same time, the protein-producing medium needs to be sterilized at 120 - 122 °C for 18 - 22 min, cooled to room temperature before use, the added organic carbon source is sodium acetate, and no additional nitrogen source is added to the prepared protein-producing medium.

[0059] In a feasible embodiment, the domestication process of the hydrogen-oxidizing bacteria flora in S1 specifically includes the following steps:

[0060] S11: After preparing the protein-producing medium, sterilize it, and then add 15 g / L of agar after the medium has cooled to room temperature to obtain the domestication medium. Among them, the blue-capped bottle used for domestication is 500 mL, with a working volume of 200 mL and a headspace volume of 415 mL. The inoculum is 10% aerobic sludge and 10% anaerobic sludge;

[0061] S12: Inject the mixed gas into the headspace of the blue-capped bottle, and continuously purge the headspace of the blue-capped bottle for a certain period of time before sealing the blue-capped bottle;

[0062] S13: Replace the mixed gas sealed in the blue-capped bottle at regular intervals. When the consumption rates of the mixed gas and hydrogen are stable and reach more than 60%, the domestication is completed, and a protein-producing hydrogen-oxidizing bacteria flora is obtained.

[0063] Among them, the sterilization temperature of the prepared protein-producing medium is 120 - 122 °C, and the sterilization time is 18 - 22 min; in S12, the volume ratio of the components of the mixed gas is H2:O2:CO2 = 60:25:15. At the same time, the time for the mixed gas to continuously purge the headspace of the blue-capped bottle is 8 - 12 min; in S13, the mixed gas sealed in the blue-capped bottle is replaced every 12 h, and the pH is controlled at 7.0 ± 0.2 during the cultivation process, the temperature is controlled at 20 - 40 °C, and the rotation speed is 150 rpm.

[0064] In addition, in a feasible embodiment, the rotation speed of the peristaltic pump is 5 - 50 rmp, the pH of the hydrogen-oxidizing bacteria protein-producing fermentation system using pyrolysis gas is 5.0 - 9.0, the H2 utilization rate of the hydrogen-oxidizing bacteria protein-producing fermentation system using pyrolysis gas > 60%, and the CO2 utilization rate > 50%.

[0065] S2: Process the fermentation flora obtained in S1 to obtain microbial protein.

[0066] In a feasible embodiment, S2 specifically includes the following steps:

[0067] S21: Centrifuge the fermentation flora and discard the supernatant;

[0068] S22: Wash the centrifuged product with deionized water and then centrifuge again, and repeat 1 - 3 times;

[0069] S23: Bake the centrifuged and washed product to obtain microbial protein.

[0070] Among them, in the step S21, the fermentation flora is centrifuged at 9000 - 11000 rpm for 10 - 15 min; in the step S23, the baking temperature is 100 - 110 °C and the baking time is 20 - 30 h. Meanwhile, one or more of the following methods are adopted to judge the formation of microbial protein: the crude protein content in the product > 30%, and the crude protein yield in the product > 1.5 g / L.

[0071] S3: Prepare a solid oxide fuel cell.

[0072] In a feasible embodiment, the step S3 specifically includes the following steps:

[0073] S31: Mix 360 g of nickel oxide and 360 g of yttria-stabilized zirconia (YSZ) slurry.

[0074] S32: Add 72 g of graphite to the slurry as a pore former.

[0075] S33: Add 84 g of polyvinyl butyral (PVB)-ethanol binder, 50.4 g of polyethylene glycol (PEG), and 50.4 g of dioctyl phthalate (DOP) to the slurry as plasticizers, and perform ball milling to obtain a slurry suitable for casting.

[0076] S34: Use a doctor blade to evenly coat the slurry on a casting machine to form an anode-supported film, and after waiting for the solvent to volatilize, remove the film.

[0077] S35: Stack the anode-supported film (25 layers) with a certain number of functional layer films and electrolyte films through a tablet press to form a green body.

[0078] S36: Sinter the green body in a high-temperature muffle furnace to obtain Ni-YSZ / YSZ half-cells with different structures.

[0079] S37: Grind 42 g of lanthanum strontium manganite (LSM) powder evenly in a mortar, and add 12.64 g of ethylene glycol diethyl ether as an organic binder to prepare a cathode slurry.

[0080] S38: Use the brushing method to evenly coat the cathode slurry on the surface of the electrolyte and perform sintering treatment to obtain a full cell.

[0081] S39: Use 738.4 g of 304 stainless steel, 178.4 g of glass wool, and 3.08 kg of chromium steel connectors as the shell and insulating materials of the solid oxide fuel cell to complete the assembly of the cell.

[0082] Among them, the above are the preparation steps of a single cell. The effective area of the single cell is 100 cm 2 , and the power is 0.4 W / cm2 , 25 single cells are required to fabricate a stack with a power generation capacity of 1 kW; the preparation method of the anode functional layer film is the same as that of the support, except that no pore-forming agent is added to the functional layer.

[0083] S4: Recover the pyrolysis gas remaining after fermentation and introduce it into the anode of the solid oxide fuel cell for electrochemical reaction. At the same time, compress the air and heat it before introducing it into the cathode of the solid oxide fuel cell to provide O2 for the electrochemical reaction, and then output electric energy.

[0084] Among them, the pyrolysis gas contains carbon-containing fuels such as CO and CH4. To prevent carbon deposition on the anode of the solid oxide fuel cell, the pyrolysis gas is mixed with a certain proportion of water vapor before entering the fuel cell and the appropriate steam-carbon ratio (S / C) is maintained to convert part of the CH4 and CO in the pyrolysis gas into H2 that can be easily utilized by the solid oxide fuel cell; at the same time, the pyrolysis gas is added with water vapor and preheated and then enters the reformer, and the reformed fuel is introduced into the anode of the solid oxide fuel cell for electrochemical reaction; the air is compressed and heated before entering the cathode of the solid oxide fuel cell to provide O2 for the electrochemical reaction; the power generation efficiency of the above solid oxide fuel cell > 50%.

[0085] The following is further illustrated with specific examples:

[0086] Example 1:

[0087] 1) Prepare a protein-producing culture medium.

[0088] In this step, the formula of the protein-producing culture medium is as follows: per liter of solution contains the following amounts of substances: 2.3 g of potassium dihydrogen phosphate, 2.9 g of disodium hydrogen phosphate, 0.5 g of magnesium sulfate, 0.5 g of sodium carbonate, 0.01 g of calcium chloride, 0.05 g of ammonium ferric citrate, 0.6 mg of boric acid, 0.4 mg of cobalt chloride, 0.2 mg of zinc sulfate, 0.06 mg of manganese chloride, 0.06 mg of sodium molybdate, 0.04 mg of nickel chloride, 0.02 mg of copper sulfate.

[0089] 2) Inoculate the domesticated hydrogen-oxidizing bacterial flora into a bioreactor containing the protein-producing culture medium, where the domestication method of the hydrogen-oxidizing bacteria refers to the above.

[0090] 3) Introduce the pyrolysis gas and carry out fermentation culture to obtain a fermentation flora.

[0091] In this step, the pyrolysis gas is a laboratory-simulated pyrolysis gas, and its main components are 40% H2, 25% CO, 5% CH4, 5% CO2, and 35% N2.

[0092] 4) Centrifuge the fermentation product at 10,000 rpm for 10 min, and discard the supernatant; wash the centrifuged fermentation product with deionized water and then centrifuge again, repeating 2 times; bake the fermentation product after 3 times of centrifugation at 105 °C for 24 hours to obtain microbial protein.

[0093] 5) Collect the remaining fermentation gas in a gas tank.

[0094] 6) Prepare a solid oxide fuel cell, and the preparation method refers to the above steps.

[0095] 7) Pass the collected remaining pyrolysis gas into the anode of the solid oxide fuel cell, and compress air and pass it into the cathode of the solid oxide fuel cell to carry out an electrochemical reaction and collect electric energy.

[0096] In Example 1, the analysis results of the H2 utilization rate, CO2 utilization rate, microbial protein yield in the fermentation stage, and the power generation amount in the power generation stage are shown in the following table.

[0097]

[0098] Table 1 Analysis result table of Example 1

[0099] In this example, the pyrolysis gas used in the protein-producing fermentation system by hydrogen-oxidizing bacteria using pyrolysis gas is a laboratory-simulated pyrolysis gas, with the main components being 40% H2, 25% CO, 5% CH4, 5% CO2, and 35% N2; as shown in Table 1, after the system operates in the fermentation stage, the H2 utilization rate is higher than 60%, the CO2 utilization rate is higher than 50%, and the microbial protein yield is higher than 1.5 g / L. In the power generation stage, the power generation efficiency of the solid oxide fuel cell using the remaining pyrolysis gas after protein production is higher than 50%. It can be seen that the present invention can achieve efficient resource utilization and energy utilization of pyrolysis gas.

[0100] Example 2:

[0101] The main steps are repeated in Example 1, with the only difference being that in step (3), the pyrolysis gas used is a simulated wood chip pyrolysis gas, with the main components being 51.6% H2, 22.4% CO, 4.9% CH4, 10.3% CO2, and 10.8% N2.

[0102] In Example 2, the analysis results of the H2 utilization rate, CO2 utilization rate, microbial protein yield in the fermentation stage, and the power generation amount in the power generation stage are shown in the following table.

[0103]

[0104] Table 2 Analysis result table of Example 2

[0105] As shown in Table 2, in this embodiment, after the pyrolysis gas composition is changed, the H2 utilization rate, CO2 utilization rate, and microbial protein production in the fermentation stage are all lower than those in Example 1, while the power generation efficiency in the power generation stage is higher than that in Example 1. However, in Example 2, the H2 utilization rate in the fermentation stage is still higher than 60%, the CO2 utilization rate is still higher than 50%, and the microbial protein production is higher than 1.5 g / L. The power generation efficiency of the solid oxide fuel cell using the remaining pyrolysis gas after protein production in the power generation stage is higher than 50%, and the high-efficiency resource utilization and energy utilization of the pyrolysis gas can still be achieved.

[0106] Example 3:

[0107] The main steps are the same as those in Example 1, except that in step (3), the pyrolysis gas used is simulated domestic waste pyrolysis gas, and the main components are 30.2% H2, 19.7% CO, 30% CH4, 6.5% CO2, and 13.6% N2.

[0108] In Example 3, the analysis results of the H2 utilization rate, CO2 utilization rate, microbial protein production in the fermentation stage, and the power generation amount in the power generation stage are shown in the following table.

[0109]

[0110] Table 3 Analysis results table of Example 3

[0111] As shown in Table 3, in this embodiment, after the pyrolysis gas composition is changed, the H2 utilization rate, CO2 utilization rate, microbial protein production in the fermentation stage, and the power generation efficiency in the power generation stage are all lower than those in Example 1. However, the H2 utilization rate in the fermentation stage is still higher than 60%, the CO2 utilization rate is still higher than 50%, and the microbial protein production is higher than 1.5 g / L. The power generation efficiency of the solid oxide fuel cell using the remaining pyrolysis gas after protein production in the power generation stage is higher than 50%, and the high-efficiency resource utilization and energy utilization of the pyrolysis gas can still be achieved.

[0112] Example 4:

[0113] The main steps are the same as those in Example 1, except that in step (3), the pyrolysis gas used is simulated sludge pyrolysis gas, and the main components are 27.9% H2, 24.5% CO, 10.7% CH4, 5.3% CO2, and 31.6% N2.

[0114] In Example 4, the analysis results of the H2 utilization rate, CO2 utilization rate, microbial protein production in the fermentation stage, and the power generation amount in the power generation stage are shown in the following table.

[0115]

[0116] Table 4 Analysis results table of Example 4

[0117] In this embodiment, after the composition of the pyrolysis gas is changed, the H2 utilization rate, CO2 utilization rate, microbial protein production in the fermentation stage, and power generation efficiency in the power generation stage are all lower than those in Embodiment 1. However, the H2 utilization rate in the fermentation stage is still higher than 60%, the CO2 utilization rate is still higher than 50%, and the microbial protein production is higher than 1.5 g / L. The power generation efficiency of the solid oxide fuel cell using the remaining pyrolysis gas after protein production in the power generation stage is higher than 50%, and the high-efficiency resource utilization and energy utilization of the pyrolysis gas can still be achieved.

[0118] From the results of Embodiments 1 to 4, although the components and contents of the pyrolysis gas are different, with the action of hydrogen-oxidizing bacteria and the utilization of solid oxide fuel cells, the effects of producing microbial protein and co-producing electricity are both very good. However, considering Embodiments 1 to 4 together, the hydrogen content in the pyrolysis gas is not the higher the better, because the stoichiometric requirement of H2:CO2 for hydrogen-oxidizing bacteria to produce microbial protein is 5.22:1. The closer the value of H2:CO2 in the pyrolysis gas is to 5.22, the higher the utilization rate of hydrogen in the fermentation stage and the higher the microbial protein production.

[0119] Considering Embodiment 1 and Embodiment 2 together, when the H2 and CO contents in the pyrolysis gas are relatively high, the power generation efficiency of the solid oxide fuel cell is also relatively high. This is because the calorific values of H2 and CO are relatively high, and hydrogen-oxidizing bacteria use less CO during protein production by fermentation. At this time, the relatively high calorific value of the remaining pyrolysis gas is conducive to improving the power generation efficiency.

[0120] In summary, the technology of using hydrogen-oxidizing bacteria to produce protein from pyrolysis gas and co-producing electricity using solid oxide fuel cells is completely feasible and has good effects.

[0121] So far, the embodiments of the present invention have been described in detail. To avoid obscuring the concept of the present invention, some details well known in the art have not been described; those skilled in the art can fully understand how to implement the technical solutions of the present invention based on the above description; at the same time, any range described in the present invention includes the end values and any numerical value between the end values and any sub-range constituted by any numerical value between the end values or the end values; in addition, unless otherwise specified, each raw material in the present invention can be obtained by purchasing commercially, and the equipment used in the present invention can adopt conventional equipment in the field or refer to the existing technology in the field.

[0122] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified or some technical features can be equivalently replaced without departing from the scope and spirit of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way.

[0123] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing microbial protein and co-producing electricity from pyrolysis gas, characterized in that, It includes the following steps: S1: Inoculate the domesticated hydrogen-oxidizing bacteria flora into a bioreactor containing a protein-producing medium, and introduce pyrolysis gas to obtain a microbial fermentation system for protein production by hydrogen-oxidizing bacteria using pyrolysis gas, and then carry out fermentation culture to obtain a fermentation flora. Among them, the pyrolysis gas contains H2, CO2, CO and CH4; S2: Process the fermentation flora obtained in S1 to obtain microbial protein; S3: Prepare a solid oxide fuel cell; S4: Recover the pyrolysis gas remaining after fermentation and introduce it into the anode of the solid oxide fuel cell for electrochemical reaction. At the same time, compress the air and heat it before introducing it into the cathode of the solid oxide fuel cell to provide O2 for the electrochemical reaction, and then output electric energy.

2. The method for preparing microbial protein and co - generating electricity from pyrolysis gas according to claim 1, wherein, In S1, the formula of the protein-producing medium is that each liter of solution contains the following amounts of substances: 2.3 g of potassium dihydrogen phosphate, 2.9 g of disodium hydrogen phosphate, 0.5 g of magnesium sulfate, 0.5 g of sodium carbonate, 0.01 g of calcium chloride, 0.05 g of ammonium ferric citrate, 0.6 mg of boric acid, 0.4 mg of cobalt chloride, 0.2 mg of zinc sulfate, 0.06 mg of manganese chloride, 0.06 mg of sodium molybdate, 0.04 mg of nickel chloride, and 0.02 mg of copper sulfate.

3. The method for preparing microbial protein and co-producing electricity from pyrolysis gas according to claim 2, characterized in that, In S1, the domestication process of the hydrogen-oxidizing bacteria flora specifically includes the following steps: S11: After the protein-producing medium is prepared, sterilize it, and then add 15 g / L of agar after the medium cools to room temperature to obtain a domestication medium. Among them, the blue-capped bottle used for domestication is 500 mL, the working volume is 200 mL, the headspace volume is 415 mL, and the inoculum is 10% aerobic sludge and 10% anaerobic sludge; S12: Inject a mixed gas into the headspace of the blue-capped bottle, and continuously purge the headspace of the blue-capped bottle for a certain period of time and then seal the blue-capped bottle; S13: Replace the mixed gas sealed in the blue-capped bottle every once in a while. When the consumption rate of the mixed gas and hydrogen is stable and reaches more than 60%, the domestication is completed to obtain a protein-producing hydrogen-oxidizing bacteria flora.

4. The method for preparing microbial protein and co-producing electric power from pyrolysis gas according to claim 3, characterized in that, In S11, the sterilization temperature of the prepared protein-producing medium is 120 - 122 °C, and the sterilization time is 18 - 22 min; in S12, the volume ratio of the components of the mixed gas is H2:O2:CO2 = 60:25:

15. At the same time, the time for continuously purging the headspace of the blue-capped bottle with the mixed gas is 8 - 12 min; in S13, the mixed gas sealed in the blue-capped bottle is replaced once every 12 h, and the pH is controlled at 7.0 ± 0.2, the temperature is controlled at 20 - 40 °C, and the rotation speed is 150 rpm during the culture process.

5. The method for preparing microbial protein and co - generating electricity from pyrolysis gas according to claim 1, wherein, S2 specifically includes the following steps: S21: Centrifuge the fermentation flora and discard the supernatant; S22: Wash the centrifuged product with deionized water and then centrifuge again, and repeat 1 - 3 times; S23: Bake the centrifuged and washed product to obtain microbial protein.

6. The method for preparing microbial protein and co-producing electricity from pyrolysis gas according to claim 5, characterized in that, In S21, the fermentation flora is centrifuged at 9000 - 11000 rpm for 10 - 15 min; in S23, the baking temperature is 100 - 110 °C and the baking time is 20 - 30 h. Meanwhile, one or more of the following methods are adopted to judge the formation of microbial protein: the crude protein content in the product > 30%, and the crude protein yield in the product > 1.5 g / L.

7. The method for preparing microbial protein and co-producing electric power from pyrolysis gas according to claim 1, wherein S3 specifically includes the following steps: S31: Mix 360 g of nickel oxide and 360 g of yttria-stabilized zirconia slurry. S32: Add 72 g of graphite to the slurry as a pore former. S33: Add 84 g of polyvinyl butyral-ethanol binder, 50.4 g of polyethylene glycol, and 50.4 g of dioctyl phthalate to the slurry as plasticizers, and perform ball milling to obtain a slurry suitable for tape casting. S34: Use a doctor blade to evenly coat the slurry on a tape casting machine to form an anode support film, and after waiting for the solvent to volatilize, peel off the film. S35: Stack the anode support film with a certain number of functional layer films and electrolyte films through a tablet press to form a green body. S36: Sinter the green body in a high-temperature muffle furnace to obtain a Ni-YSZ / YSZ half-cell with different structures. S37: Grind 42 g of lanthanum strontium manganite powder evenly in a mortar, and add 12.64 g of ethylene glycol diethyl ether as an organic binder to prepare a cathode slurry. S38: Use the brushing method to evenly coat the cathode slurry on the surface of the electrolyte and perform sintering treatment to obtain a complete cell. S39: Use 738.4 g of 304 stainless steel, 178.4 g of glass wool, and 3.08 kg of chromium steel connectors as the shell and insulation material of the solid oxide fuel cell to complete the assembly of the cell.

8. The method for preparing microbial protein and co-producing electric power from pyrolysis gas according to claim 1, characterized in that In S4, before the pyrolysis gas is introduced into the solid oxide fuel cell, it is first mixed with steam in a certain proportion and the appropriate water-carbon ratio is maintained to convert part of the CH4 and CO in the pyrolysis gas into H2 that can be easily utilized by the cell.

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