Disclosure of Invention
The purpose of the invention is as follows: aiming at the defects in the prior art, the invention provides a biogas anaerobic preparation process based on agricultural and forestry waste.
The technical scheme is as follows: in order to achieve the aim, the invention provides a biogas anaerobic preparation process based on agricultural and forestry waste, which comprises the following steps:
s1, preparing guide section slurry, namely crushing the agricultural and forestry wastes, mixing the crushed agricultural and forestry wastes with water, and pulping the mixture into slurry, adjusting the proportion of the agricultural and forestry wastes of different sources to ensure that the carbon-nitrogen ratio of the slurry is 15-18:1, and adjusting the addition amount of the water to ensure that the solid content in the slurry is 0.55-0.60 kg/L;
s2, preparing primary pulp, namely crushing the agricultural and forestry wastes, mixing the crushed agricultural and forestry wastes with water, and pulping the mixture into pulp, adjusting the proportion of the agricultural and forestry wastes of different sources to ensure that the carbon-nitrogen ratio of the pulp is 15-18:1, and adjusting the addition amount of the water to ensure that the solid content in the pulp is 0.28-0.30 kg/L;
s3: pre-fermentation of a guide section: adding the slurry obtained in the step S1 into a fermentation tank for anaerobic fermentation; controlling the fermentation temperature to be 36-38 ℃; the pre-fermentation time is 6-8 days;
s4: fermentation in a main process: adding the slurry prepared in the step S2 into the slurry obtained in the step S3, uniformly mixing, and performing anaerobic fermentation to obtain biogas; the mass ratio of the slurry obtained from S3 to the slurry obtained from S2 is 6-9: 1; controlling the fermentation temperature to be 35-45 ℃; the fermentation time is 15-18 days;
s5: and (3) guiding out and pressurizing: leading out the biogas obtained in the step S4, and pressurizing to 0.4-0.9 MPa;
s6: and (3) purification treatment: decarbonizing and desulfurizing the marsh gas obtained in the step S5; then carrying out dehydration treatment;
s7: efficiency enhancement and storage: adding a combustion synergist into the biogas obtained in the step S6 to obtain the biogas based on the agricultural and forestry waste; pressurizing to 20-25 MPa, and storing in a pressure storage tank.
In a further preferred embodiment of the present invention, in step S3: stirring was continued using a stirring paddle at a speed of 5-8 rpm.
In a further preferred embodiment of the present invention, in step S4: stirring is carried out intermittently by a stirring paddle, stirring is carried out once every 3 days, the stirring time is 10-20min each time, and the stirring speed is 100-150 rpm.
In a further preferable scheme of the invention, in the step S4, a desulfurizing agent is further added, and the ratio of the desulfurizing agent to the total mass of the slurry is 1: 500-550. The desulfurizing agent is added to ensure that the desulfurization and the fermentation of the raw material are carried out synchronously, so that the desulfurizing agent and hydrogen sulfide generated by the raw material in the fermentation process generate water-insoluble sulfide, and the precipitate is discharged along with the discharge.
In a further preferred embodiment of the present invention, the desulfurizing agent is ferrite.
In a further preferred embodiment of the present invention, the iron salt is one or more of ferrous oxalate, ferrous chloride, ferrous sulfate, ferrous nitrate, ferrous carbonate, and ferrous citrate.
In a further preferred embodiment of the present invention, in step S6, the desulfurization treatment is performed by a wet desulfurization process, in which carbon dioxide is absorbed together with the alkali solution; the dehydration treatment mode is freeze dehydration.
In a further preferred embodiment of the present invention, in step S7, the combustion enhancer is a mixture of triethylene tetramine, ethanol, ethyl 3, 5-dibenzyloxybenzoate, tert-butyl ferrocene and azobisisobutyronitrile at a weight ratio of 2:4:1:3: 1.
Has the advantages that: compared with the prior art, the anaerobic biogas preparation process based on the agricultural and forestry waste can efficiently prepare high-purity biogas based on the agricultural and forestry waste, and has high economic benefit. The invention changes the traditional fermentation process, and divides the fermentation process into the guide segment pre-fermentation and the main segment fermentation, wherein the guide segment pre-fermentation obtains the high-efficiency fermentation liquid state through the fine control of the anaerobic fermentation process, and the high-efficiency anaerobic fermentation of the main segment fermentation is guided. The two are matched, the production efficiency of the biogas is higher than that of the conventional biogas production, the biogas yield is about 105-107% of that of the conventional one-step method, the regulation and control difficulty and the regulation and control cost are reduced, and the fine regulation and control of the whole fermentation process is not needed. In addition, a desulfurizing agent is synchronously added in the fermentation stage for preliminary desulfurization, and then subsequent deep desulfurization is carried out, so that the methane with low sulfur content can be obtained. In addition, the purified methane is added with a combustion synergist for combustion characteristic modification, so that better combustion performance is achieved.
Example 1
A biogas anaerobic preparation process based on agricultural and forestry wastes comprises the following steps:
s1, preparing guide section slurry, namely crushing the agricultural and forestry waste, mixing the crushed agricultural and forestry waste with water, and pulping the mixture into slurry, adjusting the proportion of the agricultural and forestry waste from different sources to ensure that the carbon-nitrogen ratio of the slurry is 15:1, and adjusting the addition amount of the water to ensure that the solid content in the slurry is 0.55 kg/L;
s2, preparing primary pulp, namely crushing the agricultural and forestry wastes, mixing the crushed agricultural and forestry wastes with water, and pulping the mixture into pulp, adjusting the proportion of the agricultural and forestry wastes from different sources to ensure that the carbon-nitrogen ratio of the pulp is 15:1, and adjusting the addition amount of the water to ensure that the solid content in the pulp is 0.28 kg/L;
s3: pre-fermentation of a guide section: adding the slurry obtained in the step S1 into a fermentation tank for anaerobic fermentation; controlling the fermentation temperature to be 36 ℃; the pre-fermentation time is 8 days;
s4: fermentation in a main process: adding the slurry prepared in the step S2 into the slurry obtained in the step S3, uniformly mixing, and performing anaerobic fermentation to obtain biogas; the mass ratio of the slurry obtained from S3 to the slurry obtained from S2 is 6: 1; controlling the fermentation temperature to be 35 ℃; the fermentation time is 18 days;
s5: and (3) guiding out and pressurizing: exporting the biogas obtained in the step S4, and pressurizing to 0.4 MPa;
s6: evolution treatment: decarbonizing and desulfurizing the marsh gas obtained in the step S5; then carrying out dehydration treatment;
s7: efficiency enhancement and storage: adding a combustion synergist into the biogas obtained in the step S6 to obtain the biogas based on the agricultural and forestry waste; and pressurized to 20MPa and stored in a pressure storage tank.
In this embodiment, in step S3: stirring was continued using a stirring paddle at a stirring speed of 5 rpm.
In this embodiment, in step S4: stirring is carried out intermittently by using a stirring paddle, the stirring is carried out once every 3 days, the stirring time is 10min each time, and the stirring speed is 100 rpm.
In this embodiment, in step S4, a desulfurizing agent is further added, and the ratio of the desulfurizing agent to the total mass of the slurry is 1: 500.
In this embodiment, the desulfurizing agent is ferrite.
In this embodiment, the iron salt is one or more of ferrous oxalate, ferrous chloride, ferrous sulfate, ferrous nitrate, ferrous carbonate, and ferrous citrate.
In this embodiment, in step S6, the desulfurization treatment is performed by a wet desulfurization process, in which carbon dioxide is absorbed by the alkali solution; the dehydration treatment mode is freeze dehydration.
In this embodiment, the combustion synergist in step S7 is a mixture of triethylene tetramine, ethanol, ethyl 3, 5-dibenzyloxybenzoate, tert-butyl ferrocene, and azobisisobutyronitrile at a weight ratio of 2:4:1:3: 1.
Comparative example 2
A biogas anaerobic preparation process based on agricultural and forestry wastes comprises the following steps:
s1, preparing guide section slurry, namely crushing the agricultural and forestry waste, mixing the crushed agricultural and forestry waste with water, and pulping the mixture into slurry, adjusting the proportion of the agricultural and forestry waste from different sources to ensure that the carbon-nitrogen ratio of the slurry is 18:1, and adjusting the addition amount of the water to ensure that the solid content in the slurry is 0.60 kg/L;
s2, preparing primary stage slurry, namely crushing the agricultural and forestry wastes, mixing the crushed agricultural and forestry wastes with water, and pulping the mixture into slurry, wherein the carbon-nitrogen ratio of the slurry is 18:1 by adjusting the proportion of the agricultural and forestry wastes from different sources, and the solid content of the slurry is 0.30 kg/L by adjusting the addition amount of the water;
s3: pre-fermentation of a guide section: adding the slurry obtained in the step S1 into a fermentation tank for anaerobic fermentation; controlling the fermentation temperature to be 38 ℃; the pre-fermentation time is 6 days;
s4: fermentation in a main process: adding the slurry prepared in the step S2 into the slurry obtained in the step S3, uniformly mixing, and performing anaerobic fermentation to obtain biogas; the mass ratio of the slurry obtained from S3 to the slurry obtained from S2 is 9: 1; controlling the fermentation temperature to be 45 ℃; the fermentation time is 15 days;
s5: and (3) guiding out and pressurizing: exporting the biogas obtained in the step S4, and pressurizing to 0.9 MPa;
s6: evolution treatment: decarbonizing and desulfurizing the marsh gas obtained in the step S5; then carrying out dehydration treatment;
s7: efficiency enhancement and storage: adding a combustion synergist into the biogas obtained in the step S6 to obtain the biogas based on the agricultural and forestry waste; and pressurized to 25MPa and stored in a pressure storage tank.
In this embodiment, in step S3: stirring was continued using a stirring paddle at a stirring speed of 8 rpm.
In this embodiment, in step S4: stirring is carried out intermittently by using a stirring paddle, the stirring is carried out once every 3 days, the stirring time is 20min each time, and the stirring speed is 150 rpm.
In this embodiment, in step S4, a desulfurizing agent is further added, and the ratio of the desulfurizing agent to the total mass of the slurry is 1: 550.
In this embodiment, the desulfurizing agent is ferrite.
In this embodiment, the iron salt is one or more of ferrous oxalate, ferrous chloride, ferrous sulfate, ferrous nitrate, ferrous carbonate, and ferrous citrate.
In this embodiment, in step S6, the desulfurization treatment is performed by a wet desulfurization process, in which carbon dioxide is absorbed by the alkali solution; the dehydration treatment mode is freeze dehydration.
In this embodiment, the combustion synergist in step S7 is a mixture of triethylene tetramine, ethanol, ethyl 3, 5-dibenzyloxybenzoate, tert-butyl ferrocene, and azobisisobutyronitrile at a weight ratio of 2:4:1:3: 1.
Comparative example 3
A biogas anaerobic preparation process based on agricultural and forestry wastes comprises the following steps:
s1, preparing guide section slurry, namely crushing the agricultural and forestry wastes, mixing the crushed agricultural and forestry wastes with water, and pulping the mixture into slurry, adjusting the proportion of the agricultural and forestry wastes from different sources to ensure that the carbon-nitrogen ratio of the slurry is 16:1, and adjusting the addition amount of the water to ensure that the solid content in the slurry is 0.58 kg/L;
s2, preparing primary pulp, namely crushing the agricultural and forestry wastes, mixing the crushed agricultural and forestry wastes with water, and pulping the mixture into pulp, adjusting the proportion of the agricultural and forestry wastes from different sources to ensure that the carbon-nitrogen ratio of the pulp is 16:1, and adjusting the addition amount of the water to ensure that the solid content in the pulp is 0.28 kg/L;
s3: pre-fermentation of a guide section: adding the slurry obtained in the step S1 into a fermentation tank for anaerobic fermentation; controlling the fermentation temperature to be 36 ℃; the pre-fermentation time is 7 days;
s4: fermentation in a main process: adding the slurry prepared in the step S2 into the slurry obtained in the step S3, uniformly mixing, and performing anaerobic fermentation to obtain biogas; the mass ratio of the slurry obtained from S3 to the slurry obtained from S2 is 7: 1; controlling the fermentation temperature to be 40 ℃; the fermentation time is 17 days;
s5: and (3) guiding out and pressurizing: exporting the biogas obtained in the step S4, and pressurizing to 0.7 MPa;
s6: evolution treatment: decarbonizing and desulfurizing the marsh gas obtained in the step S5; then carrying out dehydration treatment;
s7: efficiency enhancement and storage: adding a combustion synergist into the biogas obtained in the step S6 to obtain the biogas based on the agricultural and forestry waste; and pressurized to 22MPa and stored in a pressure storage tank.
In this embodiment, in step S3: stirring was continued using a stirring paddle at a stirring speed of 6 rpm.
In this embodiment, in step S4: stirring is carried out intermittently by using a stirring paddle, the stirring is carried out once every 3 days, the stirring time is 15min each time, and the stirring speed is 120 rpm.
In this embodiment, in step S4, a desulfurizing agent is further added, and the ratio of the desulfurizing agent to the total mass of the slurry is 1: 520.
In this embodiment, the desulfurizing agent is ferrite.
In this embodiment, the iron salt is one or more of ferrous oxalate, ferrous chloride, ferrous sulfate, ferrous nitrate, ferrous carbonate, and ferrous citrate.
In this embodiment, in step S6, the desulfurization treatment is performed by a wet desulfurization process, in which carbon dioxide is absorbed by the alkali solution; the dehydration treatment mode is freeze dehydration.
In this embodiment, the combustion synergist in step S7 is a mixture of triethylene tetramine, ethanol, ethyl 3, 5-dibenzyloxybenzoate, tert-butyl ferrocene, and azobisisobutyronitrile at a weight ratio of 2:4:1:3: 1.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the present invention, and these modifications should also be construed as the protection scope of the present invention.