CN101717794B - A technology and equipment for preparing biogas by solid-state fermentation - Google Patents

Abstract

The invention belongs to the field of methane preparation. Relates to a process and equipment for preparing methane by solid-state fermentation of livestock and poultry manure and crop straws. The process is characterized by comprising a system for preparing the biogas by solid state fermentation consisting of at least one group or a plurality of groups of biogas fermentation units and also comprising a step of pretreating the biogas raw material. Adopting a sequencing batch solid state fermentation process, namely tearing crop straws, and naturally composting for 3-7 days for fermentation to obtain a raw material 1; then piling up and retting dry and fresh excrement in the livestock and poultry excrement for acidification for 3-5 days for fermentation to obtain a raw material 2; then mixing the raw material 1 and the raw material 2 according to a proper carbon-nitrogen ratio to obtain a mixed fermentation raw material, and inoculating a proper amount of sludge of a methane tank or a sewage treatment plant into the mixed raw material to promote the production of methane by using the indigenous microorganisms. The device generally comprises 26 independent fermentation devices, a travelling crane conveying device, a feeding device, a discharging device, a biogas slurry output device, a biogas slurry reflux device and a biogas collecting device which are communicated with one another. The invention provides a new technology for low-carbon economy.

Description

A technology and equipment for preparing biogas by solid-state fermentation

technical field

The invention belongs to the technical field of agricultural bioenergy utilization, in particular to the technical field of agricultural biogas preparation. It specifically relates to a process and equipment for preparing biogas by two-phase solid-state fermentation using livestock and poultry manure and crop straw as fermentation raw materials.

Background technique

With the rapid development of intensive livestock and poultry breeding industry, the production mode has changed from the original courtyard production mode to the current intensive, large-scale and commercial production mode. The change of production mode will bring certain risks, because in intensive farming, livestock and poultry manure (including feces, urine and flushing water) is produced in a large amount and is highly concentrated. If it cannot be disposed of effectively, it will easily cause environmental pollution. Pollution, making intensive farms a large source of pollutant emissions; at the same time, it also provides the possibility for centralized management and disposal of pollutants in the production process. If reasonable technology is adopted, these pollutants can be recycled. H.

In response to the above problems, researchers have proposed many feasible technologies, including natural stacking fermentation method, solar greenhouse fermentation method, oxygenated dynamic fermentation method (composting), high temperature rapid drying method, thermal spray method, microwave drying method and biogas fermentation method, etc. Among them, biogas fermentation technology is considered to be the most feasible technology, which can not only effectively treat waste, but also generate convenient and clean biogas energy.

For the traditional biogas engineering technology, the anaerobic wet fermentation technology is mainly used, that is, the anaerobic fermentation of manure is used to produce biogas (generally, livestock and poultry manure needs to be diluted by 2-3 times with water), and the solid matter of raw materials is fermented in this way. The low concentration requires a huge volume of the reactor, low volumetric gas production rate, and the concentration of soluble COD in the biogas slurry after fermentation is very high, it is difficult to separate solid and liquid, it is extremely difficult to handle, and it is easy to cause secondary pollution to the environment.

Therefore, it is very necessary to develop a new anaerobic fermentation process and equipment suitable for agricultural biogas utilization with small size, low investment and simple post-treatment.

Contents of the invention

The purpose of the present invention is to solve the above problems, to provide a process and equipment that can be used for two-phase solid-state fermentation to prepare biogas in large and medium-sized livestock and poultry farms. It has been proved by small-scale long-term operation that the design of the process and equipment of the present invention is reasonable and feasible. It is easy to operate, not only can produce biogas efficiently and continuously, but also can develop biogas residue and biogas slurry after fermentation into organic fertilizer for further utilization. The process and equipment can be applied and promoted in a wide range of areas.

Realize the technology of the present invention as follows:

A method for preparing biogas by solid-state fermentation, which includes solid-state fermentation consisting of at least one or more groups of biogas fermentation units

The system for preparing biogas also includes a pretreatment step of raw materials for preparing said biogas, and its implementation steps are as follows:

(1) Wet the stalks of the crops after kneading and tearing with the raw biogas slurry of the biogas tank, and stack and retting the stalks for 3-7 days. Above 60 degrees and the pile temperature begins to drop from the highest value, white microorganisms can be seen in the pile to stop retting, and fermentation raw material 1 is obtained;

(2) stack the fresh and dry manure in the livestock and poultry manure for 3-5 days in the pond, control the fermentation temperature of the raw material heap to be 33-37° C. until the color of the raw material heap changes from yellow to dark brown, Make the pH of the raw material heap to 6.8-7.4, keep the pH value relatively stable until the stack retting is completed, and obtain the fermentation raw material 2;

(3) be 20-30 (optimum carbon-nitrogen ratio is 25) by carbon-to-nitrogen ratio as the benchmark amount mixing step 1) the fermentation raw material 1 of gained and step 2) the fermented raw material 2 of gained, press fermentation raw material 1 and fermented raw material 2. 20-40% of the total weight is inoculated with biogas tank sludge or sewage treatment plant sludge, mixed evenly and then loaded into the fermentation device in the fermentation equipment. The fermentation period is controlled to be 20-30 days (the best value is 25 days), The fermentation temperature is controlled to be 33°C-37°C (the optimal temperature is controlled at 35°C), and the pH of the fermented product is adjusted to 7.

The special equipment suitable for the above-mentioned process method consists of 20-30 single independent fermentation devices (1, 19, 20, 21, 22, 23, 24, 25, 26), driving transport device (2), feeding device (3), discharge device (4), biogas slurry collection device (5, 26), biogas slurry backflow device (6) and biogas collection device (7, 25); described fermentation device (1, 19, 20, 21, 22, 23, 24, 25, 26) have a cylindrical main body and a conical lower part, and the loading and unloading of fermentation raw materials is completed respectively through the feeding device (2) and the discharging device (3).

Each fermentation device (1, 19, 20, 21, 22, 23, 24, 25, 26) is made up of a fixed part base (8), a moving part liner (9) and a moving water seal (11), and the base ( 8) The inner support liner (9) at the lower end acts as heat preservation and is connected to the biogas slurry output device (5); the water seal cover (11) is placed in the water tank (10) at the upper end of the base (8) and connected to the biogas collection device ( 7 or 25) and biogas slurry backflow device (6); the inner tank (9) is equipped with fermentation raw materials, and after the water seal (11) is uncovered, it can be hoisted on each base and loaded by the driving transport device (2). Shipping to and from locations.

The lower end of each fermentation device (1, 19, 20, 21, 22, 23, 24, 25, 26) is connected to the biogas slurry collection device (5, 26) through the base (8), and the biogas slurry is automatically flowed to the biogas slurry by using the pressure difference. liquid collecting device (5, 26); the upper end of each fermentation device (1, 19, 20, 21, 22, 23, 24, 25, 26) passes through the water seal (11) and the biogas collecting device (7, 25) and The biogas slurry return device (6) is connected, the water seal cover (11) is placed in the water tank (10) with a depth of more than 40cm, and a biogas slurry return hole (12) and side A biogas output hole (14) is arranged on the side, and is connected to the gas storage tank and the liquid storage tank respectively.

The water tank (10) is U-shaped, and the groove depth is 40mm. The water seal cover (11) is installed on the base (8), and the water seal cover (11) is fixed on the bottom inner wall of the water tank with the The sink (10) is connected.

The biogas slurry backflow is provided with pressure by a pump connected to the biogas slurry collecting device (5, 26), and a water sealing circular surface 1 with a radius of 1 /3 radius circular spray pipe (13), the diameter of the spray pipe (13) is less than 10cm, and its surface has 3 rows of through holes whose diameter is 1-2mm.

Description of drawings

Fig. 1 is a schematic diagram of overall process equipment layout of the present invention.

Numbers in the figure: 1-fermentation device; 2-driving transport device; 3-feeding device; 4-discharging device; 5-biogas slurry collection device; 6-biogas slurry reflux device; 7-biogas collection device.

Fig. 2 is a schematic structural diagram of the solid biogas fermentation device of the present invention.

Numbers in the figure: 8-Fixed base; 9-Mobile liner; 10-Sink (U-shaped); 11-Water seal; 12-Biogas slurry return hole; 13-Spray pipe; 14-Biogas output hole; 15- Hot water injection hole; 16-temperature sensor insertion hole; 17-biogas slurry outlet.

Fig. 3 is a schematic structural diagram of a solid fermentation device.

Numbers in the figure: 18 - Biogas slurry return pump and valve; 19, 20, 21, 22, 23, 24 - Fermentation device (fermentation unit); 25 - Biogas collection device; 26 - Biogas slurry collection device.

Detailed ways

The specific design of this embodiment refers to the technical solutions described in the above-mentioned "Summary of the Invention" and "Description of Drawings". To save space, this paragraph will not repeat the above-mentioned disclosed technical details.

Process step of the present invention is as follows

1) According to the breeding scale of livestock and poultry farms, estimate the amount of feces discharged daily, and measure the moisture content and carbon-nitrogen ratio of feces according to conventional methods;

2) Determine the type of crop straw to be added as a conditioning agent. Generally, straw, wheat straw, rape stalk, corn stalk and other crop straws can be selected, or grass and leaves, etc., and the moisture content should be measured according to conventional methods before use and carbon-nitrogen ratio;

3) According to the carbon-nitrogen ratio of fermentation raw materials is 20 to 30, the optimal value is 25, the solid content concentration is 15% to 20%, the optimal value is 20%, determine the amount of feces and straw;

4) According to the consumption of step 3), measure and calculate the amount of inoculum needed for the first operation. The inoculum is biogas tank sludge or sewage treatment plant sludge, and the mass ratio of the inoculum is 20-40%, and the optimum value is 30%. , there is no need to add inoculum in the future, that is, the biogas slurry can be used as the inoculum in the way of biogas slurry reflux;

5) According to the amount of feces, straw and inoculum (digester sludge or sewage treatment plant sludge), measure and calculate its volume, and determine the volume of the required fermentation device;

6) Control the fermentation temperature to 33-37°C, the optimal temperature is controlled at 35°C, the fermentation cycle is controlled to 20 to 30 days, and the optimal value is 25 days, determine the appropriate fermentation temperature and fermentation cycle, and determine the total number of fermentation devices and the plant area, the length of the plant is twice the diameter of a single fermentation device multiplied by the number, and the width is 3 times the diameter of a single fermentation device;

7) Pretreatment of raw materials, the straw is mechanically rubbed and torn to 2-3cm, wetted with raw biogas slurry, and stacked for 3-7 days, until the high temperature drops and produces a large number of visible white microorganisms (such as white rot); livestock The dried and fresh manure in the poultry manure is stacked and retting in the acidification tank for 3-5 days, until the color changes from yellow to dark brown, so that the pH value reaches 6-8 and keeps the pH value relatively stable;

8) Mix the straw and manure pretreated in step 7) with the inoculum (i.e. the biogas digester sludge or sewage treatment plant sludge described in step 6) evenly, and then load it into a fermentation device.

The general fermenting equipment part of the special equipment suitable for the process of the present invention consists of fermenting device (1, 19, 20, 21, 22, 23, 24, 25, 26), driving transport device (2), feeding device (3), A discharge device (4), a biogas slurry collection device (5, 26), a biogas slurry reflux device (6) and a biogas collection device (7 or 25); the fermentation device (1, 19, 20, 21, 22, 23, 24, 25, 26) volume and quantity are determined by steps 5) and 6) in the above-mentioned process, and the fermentation device (1, 19, 20, 21, 22, 23, 24, 25, 26) is a steel structure or other composite The main body is cylindrical and the lower part is conical. Each fermentation device ((1, 19, 20, 21, 22, 23, 24, 25, 26) is made up of a fixed part base (8), a moving part liner (9), a moving water sealing cover (11), and the base (8) The lower end internally supports the liner (9) for heat preservation, and is connected to the biogas slurry output device (5); the water seal cover (11) is placed in the water tank (10) at the upper end of the base (8), and the water seal cover (11) There is a biogas slurry return hole (12) in the middle of the top to connect to the biogas slurry return device (6), and a biogas output hole (14) is opened on the side to connect to the biogas collection device (7, 25); the liner (9) Fermentation raw materials 1 and 2 and inoculum biogas tank sludge or sewage treatment plant sludge are loaded into the tank, and after the water cover (11) is uncovered, it can be hoisted on each base and loading site by the driving transport device (2) The loading and unloading of fermentation raw materials is completed at the loading site through the feeding device (2) and the discharging device (3); the lower end of each fermentation device (1, 19) passes through the base (8) and the biogas slurry collection device (5, 26) are connected, and the biogas slurry is self-flowed to the biogas slurry collection device (5, 26) by using the pressure difference; the upper end is connected with the biogas collection device (7 or ) and the biogas slurry return device (6) through the water seal (11), The water seal cover (11) is placed in the water tank with a depth of more than 40cm, and the biogas output hole and the biogas slurry return hole are opened on the side of the water seal cover (11), and are connected to the gas storage tank and the liquid storage tank respectively. (10) is U-shaped, the depth of the tank is 40mm, and the built-in tap water is used to seal the methane in the fermentation device (the depth of the tank depends on the gas pressure requirements in the fermentation device (1, 19), generally can be selected as 40mm), the water seal Cover (11) is installed on the base (8), and water seal cover (11) is connected with water tank (10) by the clamp post that is fixed on the bottom end inner wall of water tank.

The biogas slurry backflow is provided with pressure by a pump connected to the biogas slurry collecting device (5, 26), and a water sealing circular surface 1 with a radius of 1 /3 radius circular spray pipe (13), the diameter of the spray pipe (13) is less than 10cm, and the surface has 3 rows of through holes whose diameter is 1-2mm. The bottom of the liner (9) of the fermentation device (1, 19) has a mesh structure, the liquid can flow to the base (8), and a filter wire with a pore size of less than 1 cm is placed at the junction of the base (8) and the liner (9) net. The bottom of the biogas slurry collection device (5, 26) is equipped with a filter wire mesh, the mesh diameter is less than 1mm, and the liquid inlet is located at the bottom of the liquid outlet, the filter is located between the two, and a large-diameter valve is installed at the bottom. for the discharge of biogas residues; the feeding device adopts an auger conveyor belt; the discharging device is placed near the feeding device, and the driving transport device (2) lifts the inner tank (9) in the fermentation device (1, 19) and transports it to the discharging device. place, placed on the discharge device, after fixing, turn the discharge device to dump the fermented raw materials.

For a pig farm with a scale of 10,000 heads, according to the actual inventory of about 5,000 commercial pigs, if each commercial pig produces 2 kg of dry fresh manure per day, the entire pig farm will produce a total of about 10 tons of dry fresh manure per day (raw material 2 ), the moisture content of these dry and fresh excrement is about 85% after measuring. The carbon-nitrogen ratio is about 13, if the added crop stalk (raw material) is rice straw (raw material 1), according to the water content of rice straw is about 13% and the carbon-nitrogen ratio is about 65, the fermentation raw material carbon-nitrogen ratio proposed according to the process of the present invention The optimal value is 25, and the optimal solid content concentration is calculated at 20%. It is necessary to add 2 tons of straw, so that the final moisture content of the biogas fermentation raw material is about 20% and the carbon-nitrogen ratio is about 25. Add according to the weight of the total amount of fermentation raw materials Inoculum (i.e. biogas tank sludge or sewage treatment plant sludge) 20% calculation, the total weight of the fermented product is about 13 tons, and the total volume is about 10m3, so the design volume of each fermentation device is ^10m3 ; according to the optimal fermentation period of 25 days , it is necessary to manufacture 25 fermentation devices, and another 1 turnover fermentation device is required, a total of 26 fermentation devices are required; the diameter and height of each fermentation device are equal, and the inner tank diameter and height of the fermentation device are determined to be about 2.5m, so the plant (Fermentation Workshop) The length is about 130m and the width is about 7.5m.

The fermentation equipment includes 26 sets of fermentation devices (see accompanying drawing 11, 19 in the accompanying drawing 2 and 19, 20, 21, 22, 23, 24, 25, 26 shown in the accompanying drawing 3), 1 set of driving transport device (2) , 1 set of feed device (3), 1 set of discharge device (4), 1 set of biogas slurry collection device (5, 26), 1 set of biogas slurry return device (6) and 1 set of biogas collection device (7, 25 ), wherein each set of fermentation devices includes interfaces and pipelines with biogas slurry collection devices (5, 26), biogas slurry return devices (6) and biogas collection devices (7, 25). In this example, the fermentation of the fermented product in the fermentation device adopts medium temperature, that is, 35°C fermentation, and its temperature control system adopts temperature control and detection instruments and components commonly used in the market.

The charging position of the fermented product is generally controlled at 10 cm from the upper edge of the inner tank (9) of the fermentation device 1. After the charging is stopped, the water seal (11) is covered and rotated so that it can be connected to the water tank through the clamping column. The water tank is filled with water to seal it, and at the same time connect the interface and pipeline of the biogas slurry collection device (5, 26), the biogas slurry return device (6) and the biogas collection device (7, 25), and open the relevant valves. After the fermentation starts, the biogas slurry in the fermentation device flows to the biogas slurry collection device (5, 26) through the pressure difference, and the generated biogas will enter the biogas collection device (7, 25) after exceeding the pressure of the biogas collection device (7, 25). The upper end of the biogas slurry collection tank (5) is connected with the biogas collection device (7, 25) through a pipeline to ensure that the internal pressure of the biogas slurry tank is balanced and an anaerobic environment is maintained during backflow. The backflow biogas slurry is evenly sprayed from the top of the fermenter to the fermentation raw materials, and the contact between various microorganisms and fermentation raw materials can be increased through backflow. During the entire fermentation cycle, the controlled fermentation time is 20-30 days as a cycle, the controlled fermentation temperature is 33°C-37°C, and the pH of the fermented product is adjusted to 6.8-7.4 (for example, by adding lime water to the reflux liquid to adjust the reflux pH of the liquid or ferment).

The above examples are only used to illustrate the technical solutions of the present invention without limitation. Those of ordinary skill in the art should understand that the technical solutions of the present invention are modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention. Within the scope of the claims of the present invention.

Claims (1)

1. the technology of a preparing marsh gas by solid fermentation is characterized in that:

(1) will rub the stalks of the farm crop after tearing; With behind the said stalk of former natural pond liquid wetting of methane-generating pit stack retting system 3-7 days; The leavening temperature of control stockpile is 33-37 ℃; Above and heap temperature is begun to descend by mxm. to stockpile temperature to 60 degree, in windrow, it is thus clear that white microorganisms stops the system of macerating, obtains fermentation raw material 1;

(2) with the fresh and dried excrement dirt in the livestock and poultry feces in the pond stack retting 3-5 days; The leavening temperature of control stockpile is 33-37 ℃, and extremely described stockpile color becomes chocolate by yellow, makes the pH to 6.8-7.4 of this stockpile; Keep the relatively stable of this pH value, obtain fermentation raw material 2 to the stack retting end;

(3) be that 20-30 is the amount mixing step 1 of benchmark by C/N ratio) fermentation raw material of gained 1 and step 2) fermentation raw material 2 of gained; Press the 20-40% inoculation methane-generating pit mud or the sludge of sewage treatment plant of fermentation raw material 1 and fermentation raw material 2 gross weights; Pack into after mixing in the fermentation unit of fermentation in the specific equipment; The control fermentation period is 20-30 days, and the control leavening temperature is 33 ℃-37 ℃, the pH to 7 of adjustment fermented product;

Described fermentation specific equipment comprises 20-30 single independently fermentation unit (1,19,20; 21,22,23; 24), traveling transport (2), feeding unit (3), drawing mechanism (4), natural pond liquor collecting device (5,26), natural pond liquid reflux (6) and sludge gas collecting device (7,25) constitute; The main body of said fermentation unit (1,19,20,21,22,23,24) is cylindrical, and its underpart is taper, and it also comprises following characteristic:

A, each fermentation unit (1,19,20,21,22,23,24) are made up of fixed part base (8), moving portion inner bag (9) and mobile manhole cover (11), base (8) lower end inner support inner bag (9), and connect natural pond liquor collecting device (5); Manhole cover (11) is placed in the tank (10) of base (8) upper end, connects sludge gas collecting device (7,25) and natural pond liquid reflux (6);

The lower end of B, each fermentation unit (1,19,20,21,22,23,24) links to each other with natural pond liquor collecting device (5,26) through base (8), utilizes pressure official post natural pond liquid to flow automatically to natural pond liquor collecting device (5,26); Each fermentation unit (1,19,20; 21,22,23; 24) upper end links to each other with natural pond liquid reflux (6) through manhole cover (11) and sludge gas collecting device (7,25), and it is in the above tank (10) of 40cm that manhole cover (11) is placed on the degree of depth; And having natural pond liquid return port (12) in the top middle portion of manhole cover (11), its side has biogas delivery outlet (14), is connected respectively to gas storage holder and liquid storage tank;

C, said tank (10) are the U type, and groove depth is 40cm, and described manhole cover (11) is installed on the base (8), and manhole cover (11) is connected with tank (10) through the card post that is fixed on tank bottom inwall;

D, each fermentation unit (1,19,20; 21,22,23; 24) manhole cover (11) inner tip is installed the shower (13) that radius is manhole cover disc 1/3 a radius annular, and the diameter of shower (13) is less than 10cm, and it is the through hole of 1-2mm that its surface has 3 row's diameters.

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